REVIEW | doi:10.20944/preprints202107.0116.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Parkinson’s disease; Alzheimer’s Disease; Clinical trial; Precision medicine.
Online: 5 July 2021 (16:08:41 CEST)
Concomitant neuropathological hallmarks of Alzheimer’s Disease (AD) are common in the brains of people with Parkinson’s disease (PD). Furthermore, AD biomarkers are associated with cognitive decline and dementia in PD patients during life. Here, we highlight the considerable overlap between AD and PD, emphasizing neuropathological, biomarker, and mechanistic studies. We suggest that precision medicine approaches may successfully identify PD patients most likely to develop concomitant AD. The ability to identify PD patients at high risk for future concomitant AD in turn provides an ideal cohort for trials of AD-directed therapies in PD patients, aimed at delaying or preventing cognitive symptoms.
REVIEW | doi:10.20944/preprints201909.0270.v1
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: Alzheimer’s disease; clinical trial fails; disease-modifying treatments; alzheimer’s disease biomarkers; combination treatment; clinical trial designs
Online: 24 September 2019 (11:23:25 CEST)
Despite all scientific efforts and many protracted and expensive clinical trials, no new drug has been approved by FDA for treatment of Alzheimer disease (AD) since 2003. Indeed, more than 200 investigational programs have failed or have been abandoned in the last decade. The most probable explanations for failures of disease-modifying treatments (DMTs) for AD may include late initiation of treatments during the course of AD development, inappropriate drug dosages, erroneous selection of treatment targets, and mainly an inadequate understanding of the complex pathophysiology of AD, which may necessitate combination treatments rather than monotherapy. Clinical trials’ methodological issues have also been criticized. Current drug-development research for AD is aimed to overcome these drawbacks. Preclinical and prodromal AD populations, as well as traditionally investigated populations representing all the clinical stages of AD, are included in recent trials. Systematic use of biomarkers in staging preclinical and prodromal AD and of a single primary outcome in trials of prodromal AD are regularly integrated. The application of amyloid, tau, and neurodegeneration biomarkers, including new biomarkers—such as Tau positron emission tomography, neurofilament light chain (blood and CSF biomarker of axonal degeneration) and neurogranin (CSF biomarker of synaptic functioning)—to clinical trials allows more precise staging of AD. Additionally, use of the Bayesian statistics, modifiable clinical trial designs, and clinical trial simulators enrich the trial methodology. Besides, combination therapy regimens are currently assessed in clinical trials. The abovementioned diagnostic and statistical advances, which have been recently integrated in clinical trials, are consequential to the recent failures of studies of disease-modifying treatments. Their experiential rather than theoretical origins may better equip potentially successful drug-development strategies.
REVIEW | doi:10.20944/preprints202101.0527.v1
Online: 26 January 2021 (08:25:13 CET)
Keywords: lactic acid; ceramide; folate; nicotinamide; Alzheimer’s disease
REVIEW | doi:10.20944/preprints201712.0023.v2
Subject: Life Sciences, Endocrinology & Metabolomics Keywords: physical exercise; irisin; neurodegeneration; aging; Alzheimer’s disease
Online: 11 February 2018 (04:28:07 CET)
Irisin, a skeletal muscle-secreted myokine, produced in response to physical exercise, has protective functions in both the central and the peripheral nervous systems, including the regulation of brain-derived neurotrophic factors and modification of telomere length. Such beneficial effects may inhibit or delay the emergence of neurodegenerative diseases, including Alzheimer’s disease (AD). This review is based on the hypothesis that irisin produced by physical exercise helps control AD progression. Herein, we describe the physiology of irisin and its potential role in delaying or preventing AD. Although current and ongoing studies on irisin show promising results, further research is required to clarify its potential as a meaningful therapeutic target for treating human diseases.
ARTICLE | doi:10.20944/preprints202105.0032.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Alzheimer’s disease; cellular prion protein; amyloid β and PrP interaction in Alzheimer’s; BACE1; Aβ
Online: 5 May 2021 (10:45:04 CEST)
Alzheimer’s disease (AD) is the most common cause of dementia worldwide. Pathological deposits of neurotoxin proteins within the brain, such as amyloid-Beta and hyperphosphorylated tau tangles, are prominent features in AD. The prion protein (PrP) is involved in neurodegeneration via its conversion from the normal cellular form PrPc, to the infection form PrP Sc. Some studies indicated that posttranslationally modified PrPc isoforms plays a fundamental role in AD pathological progression. Several studies have shown that interaction of Aβ oligomers with N-terminal residues of the PrPc protein region appears critical for neuronal toxicity. The PrPc-Aβ binding always occur in AD brains and is never detected in nondemented controls and the binding of Aβ aggregates to PrPc is restricted to the N-terminus of PrPc.
REVIEW | doi:10.20944/preprints202002.0203.v1
Subject: Life Sciences, Other Keywords: Alzheimer’s disease; biomarkers dynamics; interaction; time order
Online: 15 February 2020 (15:06:18 CET)
The Aβ cascade and alternations of biomarkers in neuro-inflammation, synaptic dysfunction and neuronal injury followed by Aβ have progressed. But the question is how to use the biomarkers. Here, we examine the evidence and pathogenic implications of protein interactions and the time order of alternation. After the deposition of Aβ, the change of tau, NfL and NG is the main alternation and connection to others. The neuro-inflammation, synaptic dysfunction and neuronal injury function is exhibited prior the structural and metabolic changes in the brain following Aβ deposition. The time order of such biomarkers compared to the tau protein is not clear. Despite the close relationship between biomarkers and plaque Aβ deposition, several factors favor one or the other. There is an interaction between the proteins that CSF SNAP-25, VILIP-1 and YKL-40 can predict the brain amyloid burden. The Aβ cascade hypothesis could be the pathway, but not all subjects are converted to AD, even with very high elevated Aβ. The interaction of biomarkers and the time order of change require further research to identify the right subjects and right molecular target for precision medicine therapies.
ARTICLE | doi:10.20944/preprints202203.0180.v1
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: seizures; epilepsy; Alzheimer’s disease; antiseizure medications; hyperexcitability
Online: 14 March 2022 (09:36:19 CET)
Epilepsy and Alzheimer's disease (AD) incidence increase with age. There are reciprocal relationships between epilepsy and AD. Epilepsy is a risk factor for AD and, in turn, AD is an independent risk factor for developing epilepsy in old age and abnormal AD biomarkers in PET and or CSF are frequently found in late onset epilepsies of unknown etiology. Accordingly, epilepsy and AD share pathophysiological processes including neuronal hyperexcitability and an early excitatory-inhibitory dysregulation leading to dysfunction in the inhibitory GABAergic and excitatory glutamatergic systems. Moreover, both β-amyloid and tau protein aggregates, the anatomopathological hallmarks of AD, have proepileptic effects. Finally, these aggregates have been found in the resection material of refractory temporal lobe epilepsies suggesting that epilepsy leads to amyloid and tau aggregates. Some epileptic syndromes, such as medial temporal lobe epilepsy share structural and functional neuroimaging findings with AD, leading to overlapping symptomatology such as episodic memory deficits and toxic synergistic effects. In this respect, the existence of epileptiform activity and electroclinical seizures in AD appears to accelerate progression of cognitive decline and the presence of cognitive decline is much more prevalent in epileptic patients than in elderly without epilepsy. Notwithstanding their clinical significance, the diagnosis of clinical seizures in AD is a challenge. Most are focal and manifest with altered level of consciousness without motor symptoms, and are often interpreted as cognitive fluctuations. Finally, despite the frequent association of epilepsy and AD dementia, there is a lack of clinical trials to guide the use of antiseizure medications (ASM). There is also a potential role for ASMs to be used as disease-modifying drugs in AD.
REVIEW | doi:10.20944/preprints202209.0204.v1
Subject: Life Sciences, Genetics Keywords: Alzheimer’s disease; inflammation; non-coding RNAs; exosomes vesicles
Online: 14 September 2022 (09:20:29 CEST)
Alzheimer´s Disease (AD) has currently no effective treatment; however, preventive measures can significantly delay the progress/onset of the disease. Thus, accurate and early prediction of risk is an important strategy to alleviate the AD burden. Neuroinflammation is a major factor prompting the onset of the disease. Inflammation exerts its toxic effect via multiple mechanisms. Amongst others, it is affecting gene expression via modulation of non-coding RNAs (ncRNAs), such as miRNAs. Recent evidence supports that inflammation can also affect long non-coding RNAs (lncRNAs) expression. While the association between miRNAs and inflammation in AD has been extensively studied, the role of lncRNAs in neurodegenerative diseases has been less explored. In this review, we focus on lncRNAs and inflammation in the context of AD. Furthermore, since plasma-isolated extracellular vesicles (EVs) are increasingly recognized as an effective monitoring strategy of brain pathologies, we have focused on the studies reporting dysregulated lncRNAs in EVs isolated from AD patients and controls. The revised literature shows a positive association between pro-inflammatory lncRNAs and AD. However, the reports evaluating lncRNAs alterations in EVs isolated from plasma of patients and controls, although still limited confirm the value of specific lncRNAs associated with AD as reliable biomarkers. This is an emerging field that will open new avenues to improve risk prediction, patients’ stratification and may lead to the discovery of potential novel therapeutic targets for AD
REVIEW | doi:10.20944/preprints202206.0302.v1
Subject: Medicine & Pharmacology, Pathology & Pathobiology Keywords: Neuroproteomics; Alzheimer’s disease biomarker; neurodegeneration
Online: 22 June 2022 (03:44:49 CEST)
Alzheimer’s disease (AD) is an irreversible neurodegenerative disease characterized by progressive cognitive decline. The two cardinal neuropathological hallmarks of AD include buildup of cerebral β amyloid (Aβ) plaques and neurofibrillary tangles of hyperphosphorylated tau. The current disease-modifying treatments are still not effective enough to lower the rate of cognitive decline. The paucity of early detection and disease progression biomarkers also seems to present a major obstacle to AD drug development. The current established readouts based on expression levels of amyloid beta, tau and phospho tau have shown many discrepancies in patient samples when linked to disease progression. There is an urgent need to identify diagnostic and disease progression biomarkers from blood, CSF or other biofluids that can facilitate early detection of the disease and provide pharmacodynamic readouts for new drugs being tested in clinical trials. Advances in proteomic approaches using state-of-the-art mass spectrometry, are now being increasingly applied to study AD disease mechanisms, identify drug targets and novel disease biomarkers. In this report, we describe applications of the quantitative proteomic approaches for understanding AD pathophysiology, summarize the current knowledge gained from proteomic investigations of AD and discuss development and validation of new predictive and diagnostic disease biomarkers.
REVIEW | doi:10.20944/preprints202110.0231.v1
Subject: Life Sciences, Other Keywords: Alzheimer’s disease; magnetic resonance imaging; animal model; amyloid-beta
Online: 15 October 2021 (15:06:55 CEST)
Amyloid-beta plays an important role in the pathogenesis of Alzheimer’s disease. Aberrant amyloid-beta and tau accumulation induce neuroinflammation, cerebrovascular alterations, synaptic deficits, functional deficits, and neurodegeneration, leading to cognitive impairment. Animal models recapitulating the amyloid-beta pathology such as transgenic, knock-in mouse and rat models have facilitated the understanding of disease mechanisms and development of therapeutics targeting at amyloid-beta. There is a rapid advance in high-field MR in small animals. Versatile high-field magnetic resonance imaging (MRI) sequences such as diffusion tensor imaging, arterial spin labelling, resting-state functional MRI, anatomical MRI, MR spectroscopy as well as contrast agents have been developed for the applications in animal models. These tools have enabled high-resolution in vivo structural, functional, and molecular readouts with a whole brain field-of-view. MRI have been utilized to visualize non-invasively the amyloid-beta deposits, synaptic deficits, regional brain atrophy, impairment in white matter integrity, functional connectivity, cerebrovascular and glymphatic system in animal models of amyloidosis. Many of the readouts are translational in clinical MRI in the brain of patients with Alzheimer’s disease. In this review, we summarize the recent advance of using MRI for visualizing the pathophysiology in amyloidosis animal model. We discuss the outstanding challenges in brain imaging using MRI in small animal and propose future outlook in visualizing amyloid-beta-related alterations in brain of animal models.
REVIEW | doi:10.20944/preprints201804.0233.v1
Subject: Medicine & Pharmacology, Psychiatry & Mental Health Studies Keywords: Alzheimer’s Disease; network medicine; inflammation; network and system pharmacology; traditional Chinese medicine
Online: 18 April 2018 (07:41:00 CEST)
Alzheimer’s Disease (AD) is a neurodegenerative condition that currently has no known cure. The principles of the expanding field of network medicine (NM) have recently been applied to AD research. The main principle of NM proposes that diseases are much more complicated than one mutation in one gene, and incorporate different genes, connections between genes, and pathways that may include multiple diseases to create full scale disease networks. AD research findings as a result of the application of NM principles have suggested that functional network connectivity, myelination, myeloid cells, and genes and pathways may play an integral role in AD progression, and may be integral to the search for a cure. Different aspects of the AD pathology could be potential targets for drug therapy to slow down or stop the disease from advancing, but more research is needed to reach definitive conclusions. Additionally, the holistic approaches of network pharmacology in traditional Chinese medicine (TCM) research may be viable options for the AD treatment, and may lead to an effective cure for AD in the future.
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: Alzheimer’s disease; artificial intelligence; clinical trials; eligibility assessment; randomization
Online: 8 October 2021 (11:31:14 CEST)
Clinical trials for Alzheimer’s disease (AD) face multiple challenges, such as the high screen failure rate and even allocation of heterogeneous participants. Artificial intelligence (AI), which has become a potent tool of modern science with the expansion in the volume, variety, and velocity of biological data, offers promising potential to address these issues in AD clinical trials. In this review, we introduce the current status of AD clinical trials and topic of machine learning. Then, a comprehensive review is focused on the potential applications of AI in the steps of AD clinical trials, including the prediction of AD biomarkers and differential diagnosis of AD in the prescreen during eligibility assessment and the likelihood stratification of patients who will progress to AD dementia and fast cognitive decline group from the slow decline group in randomization. Finally, this review provides challenges, developments and the future outlook on the integration of AI into AD clinical trials.
Subject: Biology, Anatomy & Morphology Keywords: Hypoxia Inducible Factor; HIF; Ischemia; Hypoxia; Adaptation; Alzheimer’s Disease; Parkinson Disease; Neurodegeneration
Online: 26 February 2021 (15:34:31 CET)
Hypoxia is one of the most common pathological conditions which results from ischemic injury, trauma, inflammatory conditions, tumors, The adaptation of the body to hypoxia is a phenomenon that is of great importance both in normal conditions and in Most of the cellular response’ reactions to hypoxia is associated with a family of transcription factors called hypoxia-inducible factors (HIF). They induce the expression of a wide range of genes that help cells adapt to a hypoxic HIF functions are currently being extensively studied. In 2019, William G. Kaelin and Gregg Semenza from the USA and Sir Peter J. Ratcliffe from the UK received the Nobel Prize in Physiology or Medicine for the discovery of the basic mechanisms of adaptation to hypoxia and investigation of the role of HIF factor in the regulation of the hormone erythropoietin Based on its pivotal physiological importance, the HIF factor attracts more and more attention as a new potential target for treating a large number of diseases associated with Most of the experimental work dealing with the HIF factor is focused on its role in liver and However, increasing amount of experimental results clearly demonstrates that the HIF factor-based response represents an universal adaptation mechanism for all kinds of tissues, including the nervous system where HIF is critical for regulating neurogenesis, nerve cell differentiation, and neuronal This review provides actual overview about the complex role of HIF-1 in the adaptation of nerve cells to hypoxia with the focus on its potential role by various neuronal
REVIEW | doi:10.20944/preprints202101.0184.v1
Subject: Life Sciences, Biochemistry Keywords: Alzheimer’s Disease; antibacterial; anti-biofilm; antifungal; antiviral; bacteria; infectious burden; parasites; pathogens; viruses
Online: 11 January 2021 (11:28:10 CET)
Alzheimer’s disease (AD) is a chronic neurodegenerative disease associated with the overproduction and accumulation of amyloid-β peptide and hyperphosphorylation of tau proteins in the brain. Despite extensive research on the amyloid-based mechanism of AD pathogenesis, the underlying cause of AD remains poorly understood. No disease-modifying therapies currently exist, and numerous clinical trials have failed to demonstrate any benefits. The recent discovery that the amyloid-β peptide has antimicrobial activities supports the possibility of an infectious aetiology of AD and suggests that amyloid-β plaque formation might be induced by infection. AD patients have a weakened blood-brain barrier and immune system and are thus at elevated risk of microbial infections. Such infections can cause chronic neuroinflammation, production of the antimicrobial amyloid-β peptide, and neurodegeneration. Various pathogens, including viruses, bacteria, fungi, and parasites have been associated with AD. Most research in this area has focused on individual pathogens, with herpesviruses and periodontal bacteria being most frequently implicated. The purpose of this review is to highlight the potential role of multi-pathogen infections in AD. Recognition of the potential coexistence of multiple pathogens and biofilms in AD's aetiology may stimulate the development of novel approaches to its diagnosis and treatment. Multiple diagnostic tests could be applied simultaneously to detect major pathogens, followed by anti-microbial treatment using antiviral, antibacterial, antifungal, and anti-biofilm agents.
REVIEW | doi:10.20944/preprints202101.0062.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Alzheimer’s disease (AD); aggregation; autophagy; aggresome; autophagosomes; aggrephagy
Online: 4 January 2021 (16:35:17 CET)
Alzheimer’s disease (AD) is one of the most prevailing neurodegenerative diseases in the world, which is characterized by memory dysfunction and the formation of tau and amyloid β (Aβ) aggregate in multiple brain regions, including the hippocampus and cortex. The formation of senile plaques involving tau hyperphosphorylation, fibrillar Aβ, and neurofibrillary tangles (NFTs) are used as pathological markers of AD, and eventually produces aggregation or misfolded protein. Importantly, it has been found that failure to degrade these aggregate-prone proteins leads to pathological consequences, such as synaptic impairment, cytotoxicity, neuronal atrophy, and memory deficits associated with AD. Recently, increasing evidences have been suggested that autophagy pathway plays a role as a central cellular protection system to prevent the toxicity induced by aggregate or misfolded proteins. Moreover, it has also been related that AD-related protein aggresomes could be selectively degraded by autophagosome and lysosomal fusion through autophagy pathway which is known as aggrephagy. Therefore, the regulation of autophagy might be served as a useful approach to modulate the formation of aggresome associated in AD. This review focuses on the recent improvements in the application of natural compounds and small molecules as a potential therapeutic approach for AD prevention and treatment via aggrephagy.
ARTICLE | doi:10.20944/preprints201805.0070.v1
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: Hyperpolarized gas MRI; xenon; gas retention; Alzheimer’s disease; wash out; vascular
Online: 3 May 2018 (12:02:44 CEST)
Biomarkers have the potential to aid in the study of Alzheimer’s disease (AD); unfortunately, AD biomarker values often have a high degree of overlap between healthy and AD individuals. This study investigates the potential utility of a series of novel AD biomarkers, the sixty second 129Xe retention time, and the xenon washout parameter, based on the washout of hyperpolarized 129Xe from the brain of AD participants following inhalation. The xenon washout parameter is influenced by cerebral perfusion, T1 relaxation of xenon, and the xenon partition coefficient, all factors influenced by AD. Participants with Alzheimer’s disease (n=4) and healthy volunteers (n=4) were imaged using hyperpolarized 129Xe magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) to determine the amount of retain xenon in the brain. At 60 sec post breath hold, AD patients retained significantly higher amounts of 129Xe compared to healthy controls. Data was fit to a pharmacokinetic model and the xenon washout parameter was extracted. Xenon washout in white and grey matter occurs at a slower rate in Alzheimer’s participants (129Xe half-life time of 42s and 43s, respectively) relative to controls (20s and 16s, respectively). Following larger scale clinical trials for validation, the xenon washout parameter has the potential to become a useful biomarker for the support of an AD diagnosis.
HYPOTHESIS | doi:10.20944/preprints202108.0454.v1
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: Alzheimer’s disease; DNA damage; somatic mutation; integrin; synaptic adhesion
Online: 23 August 2021 (14:34:00 CEST)
Alzheimer’s disease (AD) is a genetically complex senile neurodegeneration with unknown etiology. The first gene discovered to be mutated in early-onset AD, the amyloid precursor protein (APP), has been widely assumed as a causal factor in the disease cascade due to its generation of Aβ species. APP has an evolutionarily conserved biological role and activates a signaling program with notable similarities to integrin—a cell adhesion receptor with a wide array of functions. Intriguingly, several AD genome-wide association study (GWAS) candidate genes, including the SHARPIN locus recently reported by us and others, influence signaling of the integrin pathway. Integrins are focal adhesion regulators and serve in nervous system development, synaptic plasticity, and Tau phosphorylation. These observations suggest that the function of APP probably goes beyond Aβ generation in AD. Aging—the strongest risk factor for AD—is associated with various clock-like events in cells. For instance, neurons are continuously impacted by stochastic ‘hits’ to their genomes in aging, in the forms of DNA damage, insertion-deletions, copy-number variations (CNVs) and other types of somatic mutations. DNA damage and somatic mutations can result in neoplastic changes and cancer in mitotically active cells. However, their consequences in post-mitotic cells such as aging neurons are less defined. The current hypothesis holds that the stochastic loss of DNA sequence data at random loci in aging affects longer genes by chance more frequently. As a result, the biological processes coordinated by long genes may be more vulnerable to such random aging effects. Curiously, as shown by us and others, long genes are strongly enriched for synapse- and cell adhesion-related ontologies, more than any other biological process or cellular compartment. In addition, among various cell types, neurons possess the highest levels of long gene expression and are therefore more vulnerable to such harmful effects. The long gene vulnerability hypothesis provides a simple link between aging and the genetic landscape of AD and warrants new strategies for disease modification.
REVIEW | doi:10.20944/preprints201808.0410.v1
Subject: Chemistry, Analytical Chemistry Keywords: metabolomics; direct mass spectrometry; Alzheimer’s disease; pathogenesis; biomarkers
Online: 23 August 2018 (10:10:47 CEST)
Direct mass spectrometry-based metabolomics has been widely employed in the last years to characterize metabolic alterations underlying to Alzheimer’s disease development and progression. This high-throughput approach presents a great potential for fast and simultaneous fingerprinting of a vast number of metabolites, which can be applied to multiple biological samples such as serum/plasma, urine, cerebrospinal fluid and tissues. In this review article we present the main advantages and drawbacks of metabolomics based on direct mass spectrometry compared with conventional analytical techniques, and provide a comprehensive revision of the literature on the application of these tools in Alzheimer’s disease research.
REVIEW | doi:10.20944/preprints202108.0518.v2
Subject: Medicine & Pharmacology, General Medical Research Keywords: liquid biopsy; circulating biomarkers; Alzheimer’s disease; neurodegeneration; cell-free; diagnosis
Online: 8 March 2022 (09:56:01 CET)
Alzheimer’s disease is the most common neurodegenerative disease and affects persons of all races, ethnic groups, and sexes. The disease is characterized by neuronal loss leading to cognitive decline and memory loss. There is no cure and the effectiveness of existing treatments is limited and depends on the time of diagnosis. The long prodromal period, during which patients’ ability to live a normal life is not affected despite neuronal loss, often leads to a delayed diagnosis because it can be mistaken for normal aging of the brain. In order to make a substantial impact on AD patients, early diagnosis may provide a greater therapeutic window for future therapies to slow AD-associated neurodegeneration. Current gold standards for disease detection include magnetic resonance imaging and positron emission tomography scans, which visualize amyloid β and phosphorylated tau depositions and aggregates. Liquid biopsies, already an active field of research in precision oncology, are hypothesized to provide early disease detection through minimally or non-invasive sample collection techniques. Liquid biopsies in Alzheimer’s disease have been studied in cerebrospinal fluid, blood, ocular, oral, and olfactory fluids. However, most of the focus has been on blood and cerebrospinal fluid due to biomarker specificity and sensitivity attributed to the effects of the blood-brain barrier and inter-laboratory variation during sample collection. Many studies have identified amyloid β and phosphorylated tau levels as putative biomarkers, however, advances in next-generation sequencing-based liquid biopsy methods have led to significant interest in identifying nucleic acids species associated with Alzheimer’s disease from liquid tissues. Differences in cell-free RNAs and DNAs have been described as potential biomarkers for AD and hold the potential to affect disease diagnosis, treatment, and future research avenues.
REVIEW | doi:10.20944/preprints202012.0059.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Alzheimer’s disease; mitochondrial dysfunctions; phytochemicals; reactive oxygen species (ROS); autophagy
Online: 2 December 2020 (11:14:07 CET)
Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by a decline in cognitive function with neuronal damage. Although the precise pathobiology of AD is still elusive, accumulating evidences suggest that mitochondrial dysfunction is one of the underlying causes of AD. Mutations of mitochondrial or nuclear DNA that encode mitochondrial constituents may cause mitochondrial dysfunctions. In particular, dysfunction of electron transport chain complexes along with interactions of mitochondrial pathological proteins are associated with mitochondrial dysfunctions in AD. Mitochondrial dysfunction causes an imbalance in reactive oxygen species, leading to oxidative stress (OS) and vice-versa. Neuroinflammation is another potential contributory factor to induce mitochondrial dysfunction. Phytochemicals or other natural compounds have the potential to scavenge oxygen free radicals and enhance cellular antioxidant defense system, and thereby protect against OS-mediated cellular damage. Phytochemicals can also modulate other cellular processes, including autophagy and mitochondrial biogenesis. Pharmacological intervention through neuroprotective phytochemicals can, therefore, be a potential strategy to combat mitochondrial dysfunctions as well as AD. This review focuses on the role of phytochemicals to mitigate mitochondrial dysfunction in the therapy of AD pathogenesis.
HYPOTHESIS | doi:10.20944/preprints202012.0813.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Alzheimer’s disease; beta-amyloid; protease; membrane; membrane channel; lysosome; autophagy; mitochondrion
Online: 31 December 2020 (13:32:26 CET)
Alzheimer's disease (AD) is the most common cause of dementia and affects millions of people around the world. Neuronal death in AD is initiated by the toxic action of oligomeric amyloid-β (Aβ) peptides. The formation of membrane channels by Aβ is a primary molecular action and does not require any other proteins. Channels are formed by short amyloid fragments faster and more frequently than by full-length peptides. The channel formation is dependent on an electrostatic interaction between a positively charged peptide and a negatively charged membrane. Negative membranes can be found in several locations of a cell – the inner leaflet of plasma membrane, mitochondria, and lysosomes, which all are well-known cellular targets in AD. Considering that the amyloid enters a cell by endocytosis and is exposed to lysosomal enzymes, we propose the amyloid degradation toxicity hypothesis. Endopeptidases degrade the endocytosed peptide. Produced fragments form membrane channels, which can transfer various ions (including protons) and even relatively large compounds. The neutralization of lysosomal content inactivates enzymes, which fails the whole system of recycling cellular content, including autophagy. The permeabilization of lysosomes could also lead to cell death through necrotic and apoptotic mechanisms. We discuss several mechanisms that describe how amyloid degradation products reach plasma and mitochondrial membranes, and form membrane channels. The pathogenesis of AD is discussed at various levels in a context of how the primary molecular mechanism of membrane channel formation could progress into the disease state. The discussion starts at the molecular level and extends to why the development of a disease takes years and is closely associated with aging. The proposed hypothesis offers an interpretation to several clinical observations such as the involvement of iron metabolism and an inverse association between developing Alzheimer's disease and cancer. Predictions about potential biomarkers and effectiveness of future treatments are discussed.
REVIEW | doi:10.20944/preprints202106.0471.v2
Subject: Biology, Physiology Keywords: Alzheimer’s Disease; microfluidics; lab-on-chip; 3D culture; organ-on-chip
Online: 23 August 2021 (13:38:28 CEST)
Alzheimer’s disease (AD) is a significant health concern worldwide with enormous social and economic impact globally. The gradual deterioration of cognitive functions and irreversible neuronal losses are primary features of the disease. Even after decades of research, most therapeutic options are merely symptomatic, and drugs in clinical practice present numerous side effects. Lack of effective diagnostic techniques prevents the early prognosis of disease, resulting in a gradual deterioration in the quality of life. Furthermore, the mechanism of cognitive impairment and AD pathophysiology is poorly understood. Microfluidics exploits different microscale properties of fluids to mimic environments on microfluidic chip-like devices. These miniature multichambered devices can be used to grow cells and 3D tissues in vitro, analyze cell-to-cell communication, decipher the roles of neural cells like microglia, and gain insights into AD pathophysiology. This review focuses on the applications and impact of microfluidics on AD research. We discuss the technical challenges and possible solutions provided by this new cutting-edge technique to understand disease-associated pathways and mechanisms.
ARTICLE | doi:10.20944/preprints202008.0091.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: induced pluripotent stem cells; disease modelling; neuronal differentiation; cholinergic neurons; Alzheimer’s disease; frontotemporal dementia
Online: 4 August 2020 (11:17:44 CEST)
The study of neurodegenerative diseases using pluripotent stem cells requires new methods to assess neurodevelopment and neurodegeneration of specific neuronal subtypes. The cholinergic system, characterized by its use of the neurotransmitter acetylcholine, is one of the first to degenerate in Alzheimer’s disease and is also affected in frontotemporal dementia. We developed a differentiation protocol to generate basal forebrain cholinergic neurons (BFCNs) from induced pluripotent stem cells (iPSCs) aided by the use of small molecule inhibitors and growth factors. Ten iPSC lines were successfully differentiated into BFCNs using this protocol. The neuronal cultures were characterised through RNA and protein expression, and functional analysis of neurons was confirmed by whole-cell patch clamp. We have developed a reliable protocol using only small molecule inhibitors and growth factors, while avoiding transfection or cell sorting methods, to achieve a BFCN culture that expresses the characteristic markers of cholinergic neurons.
ARTICLE | doi:10.20944/preprints202105.0018.v1
Subject: Mathematics & Computer Science, Algebra & Number Theory Keywords: Ambient Intelligence; Internet of Things; Context; Prediction; Context Histories; Alzheimer’s Disease
Online: 4 May 2021 (13:47:01 CEST)
The new Internet of Things (IoT) applications are enabling the development of projects that help monitoring people with different diseases in their daily lives. Alzheimer’s is a disease that affects neurological functions and needs support to maintain maximum independence and security of patients during this stage of life, as the cure and reversal of symptoms have not yet been discovered. The IoT-based monitoring system provides the caregivers’ support in monitoring people with Alzheimer’s Disease (AD). This paper presents an ontology-based computational model which receives physiological data from external IoT applications, allowing to identify of potentially dangerous behaviors for patients with AD. The main scientific contribution of this work is the specification of a model focusing on Alzheimer’s disease using the analysis of Context Histories and Context Prediction, which considering the state of the art, it is the only one that uses analysis of Context Histories to perform predictions. The research also proposes a simulator to generate activities of the daily life of patients allowing the creation of datasets. These datasets were used to evaluate the contributions of the model and were generated according to the standardization of the ontology. The simulator generated 1025 scenarios applied to guide the predictions, which achieved average accurary of 97.44%. The experiments also allowed the learning of 20 relevant lessons on technological, medical and methodological aspects of DCARE that are recorded in this article.
ARTICLE | doi:10.20944/preprints201909.0308.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: Alzheimer’s disease; emphasis learning; multi-modal classification; svm; pca
Online: 27 September 2019 (10:26:34 CEST)
A method for classification is introduced in this article, and it is tested on ADNI database to diagnose alzheimer’s disease (AD). It is obvious that tunning the performance of a classification to get better results is a complicated problem, and when we want model’s accuracy or other peformance measurments higher than 90%, the problem will be more complicated. In this study, we tried and succeeded to discover a method to solve this problem. The final feature set can be used clustering too, because outgrowth feature set of the proposed method is invigorated. In the recent years, a lot of activities is done to develop computer aided systems (CAD) for alzheimer’s disease diagnosis. Most of these recently developed systems concenterated on extracting and combining features from MRI, PET, CSF, and …; in this article, we made attempt to do so and utilized one more technique to increase classification performance. Finding and producing the best features to solve three binary classiﬁcation problems of AD vs. Normal Control (NC), Mild Cognitive Impairment (MCI) vs. NC, and MCI vs. AD are the purposes of this article. Experiments indicate performance and effectiveness rates of the proposed method, which are accuracies of 98.81%, 81.61%, and 81.40% for AD vs. NC, MCI vs. NC, and AD vs. MCI classification problems, respectively. As can be seen, using this method increased the performance of the three binary problems incredibly.
REVIEW | doi:10.20944/preprints202010.0195.v1
Subject: Life Sciences, Biochemistry Keywords: Autophagy; Amyloid precursor protein (APP); β‐amyloid (Aβ); mTOR; Alzheimer’s disease (AD).
Online: 9 October 2020 (11:07:53 CEST)
Autophagy refers to the degradation of cytoplasmic constituents by a lysosomal-mediated pathway, which plays a critical role in maintaining cellular homeostasis. Importantly, dysregulation of autophagy has been implicated in multiple neurodegenerative disorders. Previous studies reported that autophagy affects the processing of amyloid precursor protein (APP), thus stimulating β‐amyloid (Aβ) production in Alzheimer’s disease (AD) eventually. Although the mechanism of autophagy modulation on APP processing and its pathogenesis has not yet been fully elucidated at the molecular level, but modulation of autophagy has received considerable attention as a promising approach for the treatment of AD. In the early stage of AD, Aβ may prompt autophagy to facilitate its removal via mTOR‐independent as well as-dependent pathways. However, a recent study proposed that autophagy processes are not properly regulated as AD continues to progress, and consequently, the production of Aβ tends to accumulate rapidly. Meanwhile, a number of autophagy-related genes (Atg) as well as APP genes are also thought to influence the development of AD, which may serve as a bi‐directional link to autophagy and AD pathology. In this review, we summarized current observations related to autophagy regulation and APP processing, focusing on their dynamic modifications associated with the progression of AD. Recent findings together highlight the essential role of autophagy in the removal and clearance of APP and Aβ deposition in the pathological condition of AD.
ARTICLE | doi:10.20944/preprints201907.0345.v1
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: Alzheimer’s Disease; Extreme Gradient Boosting; Deep Residual Learning; conolutional neural networks; machine learning; dementia
Online: 31 July 2019 (04:33:43 CEST)
Alzheimer's is a disease for which there is no cure. Diagnosing Alzheimer's Disease (AD) early facilitates family planning and cost control. The purpose of this study is to predict the presence of AD using socio-demographic, clinical, and Magnetic Resonance Imaging (MRI) data. Early detection of AD enables family planning and may reduce costs by delaying long-term care. Accurate, non-imagery methods also reduce patient costs. The Open Access Series of Imaging Studies (OASIS-1) cross-sectional MRI data were analyzed. A gradient boosted machine (GBM) predicted the presence of AD as a function of gender, age, education, socioeconomic status (SES), and Mini-Mental State Exam (MMSE). A Residual Network with 50 layers (ResNet-50) predicted CDR presence and severity from MRI's (multi-class classification). The GBM achieved a mean 91.3% prediction accuracy (10-fold stratified cross validation) for dichotomous CDR using socio-demographic and MMSE variables. MMSE was the most important feature. ResNet-50 using image generation techniques based on an 80% training set resulted in 98.99% three class prediction accuracy on 4,139 images (20% validation set) at Epoch 133 and nearly perfect multi-class predication accuracy on the training set (99.34%). Machine Learning methods classify AD with high accuracy. GBM models may help provide initial detection based on non-imagery analysis, while ResNet-50 network models might help identify AD patients automatically prior to provider review.
ARTICLE | doi:10.20944/preprints202001.0109.v1
Subject: Medicine & Pharmacology, Pharmacology & Toxicology Keywords: Alzheimer’s disease; curcumin; network pharmacology; molecular simulation; neurodegeneration; TrkB/PI3K signaling; autophagy
Online: 11 January 2020 (13:53:12 CET)
Curcumin is one of the bioactive metabolites of turmeric (Curcuma longa), known for its pleiotropic pharmacological actions, including antioxidant and anti-inflammation, anticholinesterase, immunomodulation, and neuroprotection. Substantial evidence suggests the therapeutic benefits of curcumin against neurodegenerative disorders, including Alzheimer’s disease (AD), acting on a diverse array of brain targets that make the molecular mechanisms complicated. System biology level-investigation could potentially present a comprehensive molecular mechanism to delineate the neuropharmacological action of curcumin. In this study, we used integrated system pharmacology and molecular simulation analysis to gain insights into the underlying mechanism of curcumin action against AD. Network pharmacology study identified curcumin-targeted potential cellular pathways such as phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling, neurotrophin signaling, toll-like receptor (TLR) signaling, and autophagy, and proteins such as tropomyosin receptor kinase B (TrkB), liver X-receptor-beta (LXR-β), estrogen receptor-β (ER-β), mammalian target of rapamycin (mTOR), TLR-2, N-methyl-D-acetate receptor subunit 2B (GluN2B), β-secretase and glycogen synthase kinase-3β (GSK-3β), which are intimately associated with neuronal growth and survival, immune response, and inflammation. Moreover, the molecular modeling further verified that curcumin showed a significant binding affinity to mTOR, TrkB, LXR-β, TLR-2, ER-β, GluN2B, β-secretase, and GSK-3β, which are the crucial regulators of molecular and cellular processes associated with AD. Together, the present system pharmacology and in silico findings demonstrate that curcumin might play a significant role in modulating AD-pathobiology, supporting its therapeutic application for the prevention and treatment of AD.
REVIEW | doi:10.20944/preprints201806.0407.v2
Subject: Medicine & Pharmacology, Behavioral Neuroscience Keywords: glial cells; astrocytes; NG2 glia; microglia; oligodendrocytes; Alzheimer’s disease; neurodegenerative disease; Aβ-peptides
Online: 14 September 2018 (03:13:57 CEST)
Even though Alzheimer’s disease (AD) is of significant interest to the scientific community, its pathogenesis is very complicated and not well-understood. A great deal of progress has been made in AD research recently and with the advent of these new insights more therapeutic benefits may be identified that could help patients around the world. Much of the research in AD thus far has been very neuron-oriented; however, recent studies suggest that glial cells, i.e., microglia, astrocytes, oligodendrocytes, and oligodendrocyte progenitor cells (NG2 glia), are linked to the pathogenesis of AD and may offer several potential therapeutic targets against AD. In addition to a number of other functions, glial cells are responsible for maintaining homeostasis (i.e., concentration of ions, neurotransmitters, etc.) within the central nervous system (CNS) and are crucial to the structural integrity of neurons. This review explores the: (i) role of glial cells in AD pathogenesis; (ii) complex functionalities of the components involved; and (iii) potential therapeutic targets that could eventually lead to a better quality of life for AD patients
REVIEW | doi:10.20944/preprints201807.0481.v2
Subject: Medicine & Pharmacology, Behavioral Neuroscience Keywords: protein tau; Alzheimer’s disease; neurodegenerative disease; synaptic dysfunction; Aβ-peptides; tau-imaging
Online: 27 August 2018 (11:25:45 CEST)
One of the most commonly known chronic neurodegenerative disorders, Alzheimer’s disease (AD), manifests the common type of dementia in 60–80% of cases. From a clinical standpoint, a patent cognitive decline and a severe change in personality, as caused by a loss of neurons, is~usually evident in AD with about 50 million people affected in 2016. The disease progression in patients is distinguished by a gradual plummet in cognitive functions, eliciting symptoms such as memory loss, and eventually requiring full-time medical care. From a histopathological standpoint, the~defining characteristics are intracellular aggregations of hyper-phosphorylated tau protein, known as neurofibrillary tangles (NFT), and depositions of amyloid β-peptides (Aβ) in the brain. The~abnormal phosphorylation of tau protein is attributed to a wide gamut of neurological disorders known as tauopathies. In addition to the hyperphosphorylated tau lesions, neuroinflammatory processes could occur in a sustained manner through astro-glial activation, resulting in the disease progression. Recent findings have suggested a strong interplay between the mechanism of Tau phosphorylation, disruption of microtubules, and synaptic loss and pathology of AD. The mechanisms underlying these interactions along with their respective consequences in Tau pathology are still ill-defined. Thus, in this review: (1) we highlight the interplays existing between Tau pathology and AD; and (2) take a closer look into its role while identifying some promising therapeutic advances including state of the art imaging~techniques.
ARTICLE | doi:10.20944/preprints201808.0371.v1
Subject: Medicine & Pharmacology, Behavioral Neuroscience Keywords: Alzheimer’s disease; central nervous system; hypertension; brain-derived neurotrophy factor; NADPH oxidase
Online: 21 August 2018 (06:04:03 CEST)
Recent studies have indicated that several anti-hypertensive drugs may delay the development and progression of Alzheimer’s disease (AD). However, the relationships among AD, hypertension, and oxidative stress remain to be elucidated. In the present study, we aimed to determine whether treatment with resveratrol reduces reactive oxygen species (ROS) generation in the brain, thereby reducing cognitive impairment in rats with angiotensin II (Ang-II)-induced early AD. Male WKY rats with Ang-II-induced AD were treated with losartan or resveratrol for 2 weeks. Our results revealed that treatment with resveratrol (10 mg/kg/day) decreased blood pressure, increased levels of brain-derived neurotrophic factor (BDNF) in the hippocampus, and decreased ROS production in the nucleus tractus solitarius (NTS) in the Ang-II groups. In addition, inhibition of TauT231 phosphorylation in the hippocampus using resveratrol significantly abolished Ang-II-induced expression of Ab precursors, active caspase 3, and glycogen synthase kinase 3b (GSK-3b)Y216 while increasing AktS473 phosphorylation. Notably, resveratrol reversed impairments in hippocampal-dependent contextual memory induced by deleting NADPH oxidase and NOX2. Overall, our results suggest that resveratrol exerts neuroprotective effects against memory impairment and hippocampal damage in a rat model of early stage AD by reducing oxidative stress. These novel findings indicate that resveratrol may represent a pharmacological option for patients with hypertension at a risk of AD during old age.
REVIEW | doi:10.20944/preprints202201.0098.v1
Subject: Medicine & Pharmacology, Behavioral Neuroscience Keywords: BPSD; Alzheimer’s dementia; agitation; psychosis; SSRIs; antipsychotics; brexpiprazole; dextromethorphan
Online: 10 January 2022 (11:12:38 CET)
Background: The psychomotor agitation of the BPSD is one of the common issues in aged care facilities, leading to the poor functional and medical consequences. Psychotropic interventions are the preferable choice of treatment. But which medication should be the prescribers first preference? This review aims to compare pharmacological interventions for psychomotor agitation, judging them according to their effectuality and justifiability profiles. This is to be achieved by retrieving information from RCTs and systematic reviews. Objectives: This review evaluates evidence from RCTs, systematic reviews, and meta-analyses of BPSD patients who had taken agitation treatments. Assessing the efficacy of antidepressants and antipsychotic treatments when compared to each other for the purpose of improving agitation outcomes. Methods: This narrative review includes RCTs and retrospective studies that were comparing one or more active ingredient medications with another or with a placebo, along with sys-tematic reviews comparing antidepressants with antipsychotics such as quetiapine, olanzapine, and risperidone. Studies extracted by searching accessing databases, such as PubMed, OVID, and Cochrane with restrictions of date from 2000 to 2021 and English language. Quality of evidence: The quality of systematic reviews was judged against AMSTAR score, and RCTs were judged according to CONSORT checklist for RCT protocols. Conclusion: There are still few studies of serotonin targeting treatment of agitation in BPSD. The SSRIs such as citalopram were associated with a reduction in symptoms of agitation, and lower risk of adverse effects compared to antipsychotics. This review also illustrates brexpiprazole as a target of multimodal neurotransmitters such as dopamine, serotonin, and norepinephrine; and dextromethorphan, OR dextromethorphan associated with bupropion or quinidine as a blockade of NMDA receptors. The outcome of this review suggests that further studies involving more dementia/Alzheimer’s participants should be conducted. Future studies are required also to assess the long-term safety and efficacy of SSRI, brexpiprazole, dextromethorphan treatments for agitation in BPSD.
ARTICLE | doi:10.20944/preprints202105.0267.v1
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: Alzheimer’s disease; AD; blood-based biomarker; p53; unfolded p53; U-p53
Online: 12 May 2021 (11:21:18 CEST)
Background: Research continues to search for blood-based biomarkers sensitive to Alzheimer’s disease (AD) pathology during the initial stages when symptoms of cognitive decline are not yet apparent. A blood-based biomarker candidate is metalloprotein p53, the conformation of which was previously found to be altered in peripheral cells from individuals with mild cognitive impairment (MCI) and AD, presenting as an unfolded p53 (U-p53) conformational variant. Methods: Plasma samples from the well-characterized Australian Imaging, Biomarkers, and Lifestyle (AIBL) cohort were used to identify the clinically relevant AZ 284® peptide, specifically present in samples from individuals with symptomatic AD. The AZ 284® peptide, which is a marker of the U-p53 conformational variant (U-p53AZ), was identified by immunoprecipitation (IP) with a novel U-p53 conformational variant-specific antibody followed by liquid chromatography (LC) tandem mass spectrometry (MS/MS) and protein sequencing. Using IP-LC surface-activated chemical ionization (SACI) MS/MS analysis, the prognostic and diagnostic performance of U-p53AZ were examined in the longitudinal AIBL cohort, including 252 plasma samples derived from 214 elderly individuals. For the prognostic analyses, U-p53AZ levels were assessed at 36, 72, and 90 months after baseline assessment. Results: The prognostic performance of U-p53AZ to predict the progression to AD from preclinical or prodromal AD was high, with area under the receiver operating characteristic curve (AUC) values close to or above 0.90. Furthermore, U-p53AZ predicted the progression to AD more than 6 years prior to symptom onset with positive and negative predictive values of about 90%. Additionally, the estimated prognostic performance of U-p53AZ was superior to other main risk factors (i.e., age, sex, and either alone or in combination with amyloid status. Furthermore, U-p53AZ had high diagnostic performance to differentiate cognitively normal individuals from those with AD (AUC values >0.88). Conclusion: These findings support the use of U-p53AZ as a prognostic blood-based biomarker accurately predicting the progression to AD dementia during the preclinical and prodromal stages at least 6 years before receiving the clinical diagnosis of AD dementia.
Subject: Keywords: paraoxonases; oxidative stress; Alzheimer’s disease; brain; Tg2576 mice; astrocytes; hippocampus; amyloid-β; microglia; neurons
Online: 18 December 2020 (11:53:45 CET)
Background: Brain oxidative lipid damage and inflammation are common in neurodegenerative diseases such as Alzheimer’s disease (AD). Paraoxonase-1 and 3 (PON1 and PON3) protein expression have been described in tissues with no PON1 and PON3 gene expression. In the present study, we aimed to examine differences in PON1 and PON3 protein expression in the brain of a mouse model of AD. Methods: We used peroxidase-based and fluorescence-based immunohistochemistry in 5 brain regions (olfactory bulb, forebrain, posterior midbrain, hindbrain and cerebellum) of transgenic (Tg2576) mice with the Swedish mutation (KM670/671NL) responsible for a familial form of AD and corresponding wild-type mice. Results: We found intense PON1 and PON3 positive staining in star-shaped cells surrounding Aβ plaques in all Tg2576 mouse brain regions studied. Although we could not co-localize PON1 and PON3 with astrocytes, brain star-shaped cells, we found some co-localization of PON3 with microglia. Conclusions: These results suggest that 1) PON1 and PON3 cross the blood-brain barrier in discoidal HDLs and are transferred to specific brain cell types, and 2) PON1 and PON3 play an important role in preventing oxidative stress and lipid peroxidation in particular cell types, likely astrocytes and microglia, in AD pathology, and potentially in other neurodegenerative diseases
REVIEW | doi:10.20944/preprints202108.0237.v1
Subject: Life Sciences, Biochemistry Keywords: Alzheimer’s disease; cytokines; chemokines; neuroinflammation; neurotrophic factors; pathophysiology; Blood brain barrier; mild cognitive impairment; brain health; therapeutics
Online: 10 August 2021 (15:49:12 CEST)
Alzheimer’s disease (AD) is a neurodegenerative disorder characterized mainly by the gradual decay in neuronal function as a consequence of diverse degenerating events primarily including mitochondria dysfunction and cascades of neuro-immune reactions. Besides the acquired harmful reactive oxygen species (ROS), neurotoxins, and amyloid-beta (Aβ) and TAU pathologies in neurons, accumulating evidence with time underlined the roles of cytokines and growth factors in the AD pathogenesis. It may help us in evaluating the propensities and specific mechanism(s) of cytokines and factors impacting neuron upon apoptotic decline. Proinflammatory cytokines often induce inflammation in AD and AD-like pathogenesis in response to the apoptotic scenarios where some growth factors are involved in cytokinetic reactions to activate microglia and causing inflammation in AD. In this report, we comprehensively reviewed role of cytokines and chemokines in immune response to AD and neuropsychiatry. We provided insights into the neuroinflammation and the role of diverse factors including the pro-/anti-inflammatory cytokines, APP, TAU phosphorylation, glycation end products, complement system, and the role of glial cells. Also, we discussed the pathogenic and protective role of macrophage migration inhibitory factors, choroid plexus-, neurotrophic- and hematopoietic -related growth factors in AD. We further shed light on the availability and accessibility of the cytokines across the blood-brain barrier in AD pathophysiology. Taken together, the emerging role of these factors in AD pathology emphasized the importance of building novel strategies for an effective therapeutic/neuropsychiatric management of AD in clinics.
ARTICLE | doi:10.20944/preprints202104.0532.v3
Subject: Behavioral Sciences, Applied Psychology Keywords: Locus Coeruleus; Reserve; Brain Age; Visual Attention; Alzheimer’s Disease; Mild Cognitive Impairment; normal Aging; Neuroimaging; Voxel Based Morphometry
Online: 21 June 2021 (11:41:40 CEST)
The noradrenergic theory of Cognitive Reserve (Robertson, 2013-2014) postulates that the upregulation of the Locus Coeruleus - Noradrenergic System (LC-NA) originating in the Brainstem might facilitate cortical networks involved in attention, and protracted activation of this system throughout the lifespan may enhance cognitive stimulation contributing to Reserve. To test the above-mentioned theory, a study was conducted on a sample of 686 participants (395 controls, 156 Mild Cognitive Impairment, 135 Alzheimer’s Disease) investigating the relationship between LC volume, attentional performance and a biological index of brain maintenance (BrainPAD – an objective measure which compares an individual’s structural brain health, reflected by their voxel-wise grey matter density, to the state typically expected at that individual’s age). Further analyses were carried out on Reserve indices including education and occupational attainment. Volumetric variation across groups was also explored along with gender differences. Control analyses on the Serotoninergic (5-HT), Dopaminergic (DA) and Cholinergic (Ach) systems were contrasted with the Noradrenergic (NA) hypothesis. The antithetic relationships were also tested across the neuromodulatory subcortical systems.Results supported by bayesian modelling showed that LC volume disproportionately predicted higher attentional performance as well as biological brain maintenance across the three groups. These findings lend support to the role of the noradrenergic system as a key mediator underpinning the neuropsychology of Reserve, and they suggest that early prevention strategies focused on the noradrenergic system (e.g. cognitive-attentive training, physical exercise, pharmacological and dietary interventions) may yield important clinical benefits to mitigate cognitive impairment with age and disease.
REVIEW | doi:10.20944/preprints202101.0625.v1
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: Alzheimer’s disease; dementia, beta-amyloid; germ theory; drug development; clinical trials; herpes; spirochetes; Chlamydia pneumoniae; Porphyromonas gingivalis; toxoplasma; mycobacteria
Online: 29 January 2021 (13:57:18 CET)
There is now considerable evidence that several infectious agents (viruses, bacteria, or parasites) may play a contributing role in the development of Alzheimer’s disease (AD). The six primary suspects are herpes viruses, spirochetal bacteria, Chlamydia pneumoniae, Porphyromonas gingivalis, mycobacteria, and toxoplasma parasites. Also, some of the antimicrobial and antiviral agents that are used to treat them have shown promise for AD interventions. I describe this evidence and assert it is now time to accelerate clinical trials of these existing drugs, already federally approved, to determine if such treatments can delay, halt, or reverse AD.
ARTICLE | doi:10.20944/preprints202003.0297.v1
Subject: Mathematics & Computer Science, Information Technology & Data Management Keywords: Data Mining; Alzheimer’s Dementia; Composite Hybrid Feature Selection; Machine learning; Stack Hybrid Classification; AI Techniques; Classification; AD Diagnose; Clinical AD Dataset
Online: 19 March 2020 (10:52:31 CET)
Alzheimer's disease (AD) is a significant regular type of dementia that causes damage in brain cells. Early detection of AD acting as an essential role in global health care due to misdiagnosis and sharing many clinical sets with other types of dementia, and costly monitoring the progression of the disease over time by magnetic reasoning imaging (MRI) with consideration of human error in manual reading. Our proposed model, in the first stage, apply the medical dataset to a composite hybrid feature selection (CHFS) to extract new features for select the best features to improve the performance of the classification process due to eliminating obscures features. In the second stage, we applied a dataset to a stacked hybrid classification system to combine Jrip and random forest classifiers with six model evaluations as meta-classifier individually to improve the prediction of clinical diagnosis. All experiments conducted on a laptop with an Intel Core i7- 8750H CPU at 2.2 GHz and 16 G of ram running on windows 10 (64 bits). The dataset evaluated using an explorer set of weka data mining software for the analysis purpose. The experimental show that the proposed model of (CHFS) feature extraction performs better than principal component analysis (PCA), and lead to effectively reduced the false-negative rate with a relatively high overall accuracy with support vector machine (SVM) as meta-classifier of 96.50% compared to 68.83% which is considerably better than the previous state-of-the-art result. The receiver operating characteristic (ROC) curve was equal to 95.5%. Also, the experiment on MRI images Kaggle dataset of CNN classification process with 80.21% accuracy result. The results of the proposed model show an accurate classify Alzheimer's clinical samples against MRI neuroimaging for diagnoses AD at a low cost.
REVIEW | doi:10.20944/preprints202205.0166.v1
Subject: Life Sciences, Molecular Biology Keywords: Antimicrobial Peptides (AMPs); Alzheimer’s Disease (AD); infectious hypothesis; beta-amyloid (Ab); lactoferrin; defensins; cystatins; thymosin β4; histatin 1; statherin
Online: 12 May 2022 (09:40:33 CEST)
Alzheimer's Disease (AD) represents the most frequent type of dementia in elderly people. There are two major forms of the disease: sporadic (SAD) - whose causes are not completely understood - and familial (FAD) - with clear autosomal dominant inheritance. The two main hallmarks of AD are extracellular deposits of amyloid-beta (Ab) peptide and intracellular deposits of the hyperphosphorylated form of the tau protein (P-tau). An ever-growing body of research supports the infectious hypothesis of sporadic forms of AD. Indeed, it has been documented that some pathogens, such as herpesviruses and certain bacterial species, are commonly present in AD patients, prompting recent clinical research to focus on the characterization of Antimicrobial Peptides (AMPs) in this pathology. Literature also demonstrates that Ab can be considered itself as an AMP thus representing a type of innate immune defense peptide that protect the host against a variety of pathogens. Beyond Ab, other proteins with antimicrobial activity, such as lactoferrin, defensins, cystatins, thymosin β4, LL37, histatin 1 and statherin have been shown to be involved in AD. Here we have summarized and discussed these findings and explored the diagnostic and therapeutic potential of AMPs in AD.
REVIEW | doi:10.20944/preprints201812.0267.v1
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: Alzheimer’s disease; CTH gene; DNA methylation; epigenetics; epigenome-wide association study; methylome; MTHFR gene; nutrition; S-adenosylmethionine; vitamin B complex
Online: 24 December 2018 (04:48:53 CET)
DNA methylation and other epigenetic factors are important in the pathogenesis of late-onset Alzheimer’s disease (LOAD). Methylenetetrahydrofolate reductase (MTHFR) gene mutations occur in most elderly patients with memory loss. MTHFR is critical for production of S-adenosyl-L-methionine (SAM), the principal methyl donor. A common mutation (1364T/T) of the cystathionine-γ-lyase (CTH) gene affects the enzyme that converts cystathionine to cysteine in the trans-sulfuration pathway causing plasma elevation of total homocysteine (tHcy) or hyperhomocysteinemia – a strong and independent risk factor for cognitive loss and AD. Other causes of hyperhomocysteinemia include aging, nutritional factors, and deficiencies of B vitamins. We emphasize the importance of supplementing vitamin B12 (methylcobalamin), vitamin B9 (folic acid), vitamin B6 (pyridoxine), and SAM to patients in early stages of LOAD.
REVIEW | doi:10.20944/preprints201907.0265.v2
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: Aging; Alzheimer’s disease; brain insulin resistance; db/db diabetic mouse model; diabetic cognopathy; insulin resistance; metabolic syndrome; mixed dementia; obesity; type 2 diabetes mellitus
Online: 9 September 2019 (06:12:15 CEST)
Type 2 diabetes mellitus (T2DM) and late-onset Alzheimer’s disease-dementia (LOAD) are increasing in global prevalence and current predictions indicate they will only increase over the coming decades. These increases may be a result of the concurrent increases of obesity and aging. T2DM is associated with cognitive impairments associated with metabolic factors and increases the cellular vulnerability to develop the age-related increased risk of LOAD. This review addresses possible mechanisms due to obesity, aging, multiple intersections between T2DM and LOAD and mechanisms for the continuum of progression. Multiple ultrastructural images in female diabetic db/db models are utilized to demonstrate marked cellular remodeling changes of mural and glia cells and provide for the discussion of functional changes in T2DM. Throughout this review multiple endeavors to demonstrate how T2DM increases the vulnerability of the brain’s neurovascular unit (NVU), neuroglia and neurons are presented. Five major intersecting links are considered: i. aging (chronic age-related diseases); ii. metabolic (hyperglycemia - advanced glycation end-products and its receptor (AGE/RAGE) interactions and hyperinsulinemia – insulin resistance (a linking linchpin); iii. oxidative stress (reactive oxygen-nitrogen species); iv. inflammation (peripheral macrophage and central brain microglia); v. vascular (macrovascular accelerated atherosclerosis - vascular stiffening and microvascular NVU/neuroglial remodeling) with resulting impaired cerebral blood flow.
ARTICLE | doi:10.20944/preprints202003.0299.v1
Subject: Mathematics & Computer Science, Information Technology & Data Management Keywords: Data Mining; Alzheimer’s Dementia; Composite Hybrid Feature Selection; Machine learning; stack Hybrid Classification; AI; MRI; Neuroimaging; MPEG7 edge histogram feature extraction; CNN
Online: 19 March 2020 (11:25:01 CET)
Alzheimer's disease (AD) detection acting as an essential role in global health care due to misdiagnosis and sharing many clinical sets with other types of dementia, and costly monitoring the progression of the disease over time by magnetic reasoning imaging (MRI) with consideration of human error in manual reading. This paper goal a comparative study on the performance of data mining techniques on two datasets of Clinical and Neuroimaging Tests with AD. Our proposed model in the first stage, Apply clinical medical dataset to a composite hybrid feature selection (CHFS), for extract new features to select the best features due to eliminating obscures features, In parallel with Apply a novel hybrid feature extraction of three batch edge detection algorithm and texture from MRI images dataset and optimized with fuzzy 64-bin histogram. In the second stage, we applied a clinical dataset to a stacked hybrid classification(SHC) model to combine Jrip and random forest classifiers with six model evaluations as meta-classifier individually to improve the prediction of clinical diagnosis. At the same stage of improving the classification accuracy of neuroimaging (MRI) dataset images by applying a convolution neural network (CNN) in comparison with traditional classifiers, running on extracted features from images. The authors have collected the clinical dataset of 426 subjects with (1229 potential patient sample) from oasis.org and (MRI) dataset from a benchmark kaggle.com with a total of around ~5000 images each segregated into the severity of Alzheimer's. The datasets evaluated using an explorer set of weka data mining software for the analysis purpose. The experimental show that the proposed model of (CHFS) feature extraction lead to effectively reduced the false-negative rate with a relatively high overall accuracy with a stack hybrid classification of support vector machine (SVM) as meta-classifier of 96.50% compared to 68.83% of the previous result on a clinical dataset, Besides a compared model of CNN classification on MRI images dataset of 80.21%. The results showed the superiority of our CHFS model in predicting Alzheimer's disease more accurately with the clinical medical dataset in early-stage compared with the neuroimaging (MRI) dataset. The results of the proposed model were able to predict with accurately classify Alzheimer's clinical samples at a low cost in comparison with the MRI-CNN images model at the early stage and get a good indicator for high classification rate for MRI images when applying our proposed model of SHC.
REVIEW | doi:10.20944/preprints202012.0079.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Mitochondria; Alzheimer’s Disease; mitophagy; neurodegeneration; aging
Online: 3 December 2020 (10:36:29 CET)
Stress mechanisms have long been associated with neuronal loss and neurodegenerative diseases. The origin of cell stress and neuronal loss likely stems from multiple pathways. These include (but are not limited to) bioenergetic failure, neuroinflammation, and loss of proteostasis. Cells have adapted compensatory mechanisms to overcome stress and circumvent death. One mechanism is mitophagy. Recent studies have implicated mitophagy in several neurodegenerative diseases and clinical trials are underway which target mitophagy pathways. Here, we review mitophagy pathways, the role of mitophagy in neurodegeneration, potential therapeutics, and the need for further study.
ARTICLE | doi:10.20944/preprints201807.0275.v1
Subject: Life Sciences, Molecular Biology Keywords: tau protein amyloids; Alzheimer’s disease; tauopathy
Online: 16 July 2018 (10:49:49 CEST)
Abnormal filamentous aggregates formed by tangled tau protein turn out to be classic amyloid fibrils, meeting all criteria defined under the fuzzy oil drop model in the context of amyloid characterization. The model recognizes amyloids as linear structures where local hydrophobicity minima and maxima propagate in an alternating manner along the fibril’s long axis. This distribution of hydrophobicity differs greatly from the classic monocentric hydrophobic core observed in globular proteins. Rather than becoming a globule, the amyloid instead forms a ribbonlike (or cylindrical) structure, which can be thought of as a distorted spherical micelle, which in limit form appears to be the ribbon-like micelle.
ARTICLE | doi:10.20944/preprints202101.0530.v1
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: Alzheimer’s disease; biomarker; prognosis; P53; mass spectrometry
Online: 26 January 2021 (10:01:35 CET)
Despite the increasing number of individuals affected by Alzheimer’s disease (AD) every year, no effective therapy has been developed to treat this neurodegenerative disease yet. The current methods for AD diagnosis are effective for clinical confirmation of the disease only when symptoms become apparent, years after molecular damage started within the patients’ brains. As higher expression of a conformationally altered p53 has been correlated with AD, we developed a mass spectrometry-based method for highly sensitive, specific, and reproducible quantification of a p53 conformational variant in plasma samples of patients with known clinical outcome. In particular, we tested the prognostic performance of an AD-specific 2D3A8-immunoselected p53 peptide (AZ 284™) in different sets of individuals progressing from both cognitively unimpaired (CU) and mild cognitive impairment (MCI) patients progressing to AD dementia. Our data showed that quantitative analysis of AZ 284™ is a reliable tool for predicting AD progression up to 6 years prior to dementia onset with AUC >90%. Taken together, these results support the implementation of p53 conformational variant quantification as an affordable and powerful diagnostic tool for early, non-invasive AD diagnosis.
ARTICLE | doi:10.20944/preprints201806.0329.v1
Subject: Life Sciences, Genetics Keywords: Alzheimer’s disease; Parkinson’s disease; Genetic testing; bioethics
Online: 21 June 2018 (04:38:35 CEST)
Over the last decade, advances in our understanding about the genetic architecture of complex traits and common diseases, have increased our ability to perform susceptibility genetic testing for diseases in asymptomatic individuals. These technological developments raise complex ethical, legal and social considerations. Here we discuss a series of ethical issues associated with susceptibility genetic testing for Alzheimer's and Parkinson's disease. These include, amongst others, informed consent, disclosure of results and unexpected findings, mandatory screening, privacy and confidentiality, and stigma and genetic discrimination. As knowledge of the genetic basis of these diseases continues growing, and as genetic testing becomes more widespread, we anticipate that it will become increasingly important for scientists and clinicians to engage in the conversation about the ethical, social and policy implications of these technologies.
ARTICLE | doi:10.20944/preprints202209.0235.v1
Subject: Biology, Physiology Keywords: lipid homeostasis; APOE4; Alzheimer’s Disease; Aβ peptide; tau
Online: 16 September 2022 (02:57:37 CEST)
The association of the APOE4 (vs APOE3) isoform with an increased risk of Alzheimer’s Disease (AD) is unequivocal, but the underlying mechanisms remain incompletely elu-cidated. A prevailing hypothesis incriminates the impaired ability of APOE4 to clear neurotoxic amyloid-β peptides (Aβ) from the brain as the main mechanism linking apolipoprotein isoform to disease aetiology. APOE protein mediates lipid transport both within the brain and from the brain to the periphery, suggesting that lipids may be potential co-factors in APOE4-associated physiopathology. The present study reveals several alterations in pathways of lipid homeostasis in the brains of mice expressing the human APOE4 versus APOE3 isoform. Carriers of APOE4 had deficient cholesterol turnover, an imbalance in the ratio of specific classes of phospholipids, lower levels of phosphatidylethanolamines bearing poly-unsaturated fatty acids and an overall eleva-tion in levels of monounsaturated fatty acids. These modifications in lipid homeostasis were related with increased production of Aβ peptides as well as augmented levels of tau and phosphorylated tau in primary neuronal cultures. This suite of AP-OE4-associated anomalies in lipid homeostasis and neurotoxic protein levels may be related to the accrued risk for AD in APOE4 carriers and provides novel insights into potential strategies for therapeutic intervention.
CONCEPT PAPER | doi:10.20944/preprints202111.0564.v1
Subject: Life Sciences, Biochemistry Keywords: gamma-secretase; APP; Alzheimer’s disease; modelling; protein disorder
Online: 30 November 2021 (11:52:10 CET)
Proteolytic processing of amyloid precursor protein (APP) plays a critical role in pathogenesis of Azheimer’s disease (AD). Sequential cleavage of APP by β and γ secretases leads to generation of Aβ40 (non-amyloidogenic) and Aβ42 (amyloidogenic) peptides. Presenilin-1 (PS1) or presenilin-2 (PS2) pay a role of catalytic subunit of γ-secretase. Multiple familial AD (FAD) mutations in APP, PS1, or PS2 result in increased Aβ42:Aβ40 ratio and accumulation of toxic Aβ42 oligomers and plaques in patient brains. In this study we performed molecular modeling of APP complex with γ-secretase and analyzed potential effects of FAD mutations in APP and PS1. We noticed that all FAD mutations in APP transmembrane domain are predicted to cause an increase in the local disorder of its secondary structure. Based on structural analysis of known γ-secretase structures we proposed that APP can form a complex with γ-secretase in 2 potential conformations – M1 and M2. In conformation M1 transmembrane domain of APP forms a contact with perimembrane domain that follows the transmembrane domain 6 (TM6) in PS1 structure. In conformation M2 transmembrane domain of APP forms a contact with transmembrane domain 7 (TM7) in PS1 structure. By analyzing effects of PS1-FAD mutations on local protein disorder index, we discovered that these mutations increase conformational flexibility of M2 and reduce conformational flexibility of M1. Based on these results we proposed that M2 conformation, but not M1 conformation, of γ secretase complex with APP leads to amyloidogenic (Aβ42-generating) processing of APP. Our model predicts that APP processing in M1 conformation is favored by a curved membranes, such as membranes of early endosomes. In contrast, APP processing in M2 conformation is likely to be favored by a relatively flat memranes such as membranes of late endosomes and plasma membrane. These predictions are consistent with published biochemical analysis of APP processing at different subcellular locations. Our results suggest that specific inhibitors of Aβ42 production could be potentially developed by selectively targeting M2 conformation of γ secretase complex with APP.
ARTICLE | doi:10.20944/preprints202102.0310.v1
Subject: Behavioral Sciences, Applied Psychology Keywords: physical activity; Alzheimer’s disease; 5xFAD; acute, wheel running
Online: 12 February 2021 (15:03:25 CET)
Physical activity is considered a promising preventive intervention to reduce the risk of developing Alzheimer’s disease (AD). However, the positive effect of exercise therapy has not been proven conclusively yet, likely due to confounding factors such as varying activity regimens and life or disease stages. To examine the impact of different routines of physical exercise in the early disease stages, we subjected young 5xFAD and wild-type mice to 1-day (acute) and 30-day (chronic) voluntary wheel running and compared them with age-matched sedentary controls. We observed a significant increase in brain lactate levels in acutely trained 5xFAD mice relative to all other experimental groups. Subsequent brain RNA-seq analysis did not reveal major differences in transcriptomic regulation between training durations in 5xFAD mice. In contrast, acute training yielded substantial gene expression changes in wild-type animals relative to their chronically trained and sedentary counterparts. The comparison of 5xFAD and wild-type mice showed the highest transcriptional differences in the chronic and sedentary groups, whereas acute training was associated with much fewer differentially expressed genes. In conclusion, our results suggest that different training durations did not affect the global transcriptome of 3-month-old 5xFAD mice, whereas acute running seemed to induce a similar transcriptional stress state in wild-type animals as already known for 5xFAD mice.
ARTICLE | doi:10.20944/preprints202009.0675.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Fenugreek; Alzheimer’s disease; nootropic; cognitive disorders; herbs; memory
Online: 27 September 2020 (10:45:51 CEST)
Background: Alzheimer’s disease affecting about 24 million people world-wide. The socio-economic burden on world-economies costing more than 172 billion US $ annually for the US alone. Objectives: To prepare aqueous extract of T. foenum graecum seeds (FSE) to explore the possible treatment for cognitive deficit in experimental animals. Materials and methods: FSE was subjected to preliminary phytochemical evaluation and antioxidant effect using free radical scavenging method (DPPH). All the animal behavior was video recorded with no human intervention during observation and animal groupings were blinded to avoid investigator bias. Different doses of FSE (5%, 10% and 20%), control, standard (Piracetam, 200 mg/kg, IP.) were given for male albino mice a period of 15 days followed by cognitive assessment in elevated plus maze and novel objection recognition tests. Ttransfer latencies and time exploring novel and familiar objects were recorded in respective tests. Retention of this learned-task was examined again 24 h later and inflexion ratio (IR) and discriminative index (DI) were calculated respectively. Next in the second set of experiment same groups and treatments were continued but scopolamine was administered to all the groups except normal control one hour after the last dose and examined similarly. Results: FSE showed potential antioxidant effect and a dose dependent increase in transfer latency and improved DI indicating a nootropic effect. FSE at 20% showed significant reversal of scopolamine induced dementia in the second set of experiment. Conclusion: FSE improved memory as well as reversed the chemically induced memory deficits in experimental mice.
ARTICLE | doi:10.20944/preprints202008.0716.v1
Subject: Medicine & Pharmacology, Behavioral Neuroscience Keywords: amyloid beta; neuropsychological assessment; machine learning; Alzheimer’s disease
Online: 31 August 2020 (09:30:08 CEST)
Substantial studies have focused on early detection of Alzheimer's disease (AD). Cerebral amyloid beta (Aβ), is hallmark of AD, can be observed in vivo via positron emission tomography imaging using amyloid tracer or cerebrospinal fluid assessment, but costly expensive. The current study aims to identify and compared predictability in magnetic resonance imaging (MRI) markers and neuropsychological markers to predict cerebral Aβ status in AD cohort using machine learning (ML) approaches. The predictability in candidate markers for cerebral Aβ status was examined by analyzing 724 participants from the ADNI-2 cohort. Demographic variables, structural MRI markers, and neuropsychological test scores were used as input in several ML algorithms to predict cerebral Aβ positivity. Out of five combination of candidate markers, neuropsychological markers with demographics showed the most cost-efficient result. A feature selection model could distinguish abnormal levels of Aβ with the predictability of 0.85, indicating the same performance with MRI-based models. The result has first to identified the predictability in MRI markers using ML approaches, and secondary to demonstrate the neuropsychological model with demographics could predict Aβ positivity, suggesting a more cost-efficient method for detecting cerebral Aβ status compared to MRI markers.
ARTICLE | doi:10.20944/preprints202007.0645.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: Alzheimer’s disease; Tau phosphorylation; Heat stress; GSK-3β
Online: 26 July 2020 (17:04:50 CEST)
Alzheimer’s disease is a prominent neurological disorder, which leads to progressive dementia. The microtubule-associated protein Tau is been considered as one of the major causes of Alzheimer’s disease. Physiologically Tau assists in the stabilization of microtubules, contrary to this the pathological state of Tau results in the formation of neurotoxic tangles of Tau. The posttranslational modifications, such as GSK-3β-mediated Tau phosphorylation results in the generation of Tau pathology. Neuroinflammation generated in Alzheimer’s disease, contributes to elevated body temperature. The aim of present work is to study the effect of high temperature on Tau phosphorylation. The neuroblastoma cells were exposed to heat stress for 40 minutes. The immunofluorescence and western blot studies suggested that high temperature increases the levels of GSK-3β in cells. Heat stressed cells was also observed to have elevated levels of phosphorylated Tau. Additionally, heat stressed cells found to have modulated nuclear transport as the level of Ran was reduced. The results of present work suggested that increased temperature could be considered as a risk factor in Alzheimer’s disease as it elevated the GSK-3β levels in cells thus, resulting in increased Tau phosphorylation.
ARTICLE | doi:10.20944/preprints202206.0303.v2
Subject: Biology, Other Keywords: Methylmercury; Alzheimer’s; Parkinson’s; Blood-Brain Barrier; L-Cysteine; Neurotoxicity
Online: 23 June 2022 (04:26:46 CEST)
Methylmercury is a neurotoxin present in fish tissues that permeates the blood-brain barrier after consumption. Previous research has shown that methylmercury is harmful to neurons, causing pH alterations, oxidative stress, excitotoxicity, and parenchymal damage. Methylmercury is a known factor of neurological disorders including Alzheimer's and Parkinson's. The method by which methylmercury passes through the blood-brain barrier is largely unknown. According to preliminary studies, one way methylmercury crosses the blood-brain barrier is by creating a complex with L-Cysteine, which facilitates its passage by the LATs system through mimicking another amino acid existing in the body. The human blood-brain barrier was studied using C. elegans as a model organism. It was hypothesized that if methylmercury passes through the blood-brain barrier of C. elegans faster with L-Cysteine present than without L-Cysteine present, the methylmercury's adverse effects (death and locomotive difficulty) will occur sooner. Each of the four experimental groups contained one C. elegans: the control, the L-Cysteine group, the methylmercury group, and the methylmercury and L-Cysteine combination group. The effects of L-Cysteine and methylmercury on C. elegans were studied using three metrics: viability, locomotive disability, and time for locomotive effects to occur. The group that received both methylmercury and L-Cysteine had reduced viability rates and a decreased time for locomotive difficulty to develop, supporting the hypothesis. These findings suggest that L-Cysteine aids methylmercury permeation through the blood-brain barrier. Because the experiment indicates how methylmercury penetrates the blood-brain barrier, these results aid in finding a therapeutic solution to reverse methylmercury neurotoxicity in the brain. Additionally, this study further opens channels into potential therapeutic and preventative measures for dementia, improving morbidity and mortality in neurodegenerative diseases.
ARTICLE | doi:10.20944/preprints202104.0548.v1
Subject: Medicine & Pharmacology, Allergology Keywords: microglia; neurodegeneration; Alzheimer’s disease; neurooncology; 4R-tauopathies; TSPO-PET
Online: 20 April 2021 (13:28:14 CEST)
TSPO-PET tracers are sensitive to a single-nucleotide-polymorphism (rs6971-SNP) resulting in low (LAB), medium (MAB) and high (HAB) affinity binders, but the clinical relevance for [18F]GE-180 is still unclear. We evaluate the impact of rs6971-SNP on in vivo [18F]GE-180 binding in healthy brain and in pseudo-reference tissue in neurooncological and neurodegenerative diseases. Standardized uptake values (SUV) of [18F]GE-180-PET were assessed using a manually drawn region of interest in the fronto-parietal and cerebellar hemisphere. SUVs were compared between LAB, MAB and HAB in controls, glioma, 4-repeat tauopathies (4RT) and Alzheimer’s disease (AD) subjects. Second, SUVs were compared between patients and controls within their rs6971-subgroup. After exclusion of patients with prior therapy, n=24 LABs (n=7 controls, n=5 glioma, n=6 4RT, n=6 AD) were analysed. Age- and sex-matched MABs (n=38) and HABs (n=50) were selected. LABs had lower fronto-parietal and cerebellar SUVs when compared to MABs and HABs, but no significant difference was observed between MABs and HABs. Within each rs6971 group no SUV difference between patients and controls was detected in the pseudo-reference tissues. The rs6971-SNP affects [18F]GE-180 quantification, revealing lower binding in LABs when compared to MABs/HABs. Fronto-parietal and cerebellar ROIs were successfully validated as pseudo-reference regions.
ARTICLE | doi:10.20944/preprints202007.0532.v1
Subject: Biology, Other Keywords: Phosphatidylinositol; actin remodeling; phagocytosis; dietary fatty acids; Alzheimer’s disease
Online: 22 July 2020 (14:15:35 CEST)
Alzheimer’s disease is one of the neurodegenerative diseases, characterized by the accumulation of abnormal protein deposits, which disrupt the signal transduction in neurons and other glia cells. The pathological protein Tau and amyloid-β contributes to the disrupted microglial signaling pathways, actin cytoskeleton, and cellular receptor expression. The important secondary messenger lipids i.e., phosphatidylinositols are largely affected by protein deposits of amyloid-beta in Alzheimer’s disease. Phosphatidylinositols are the product of different phosphatidylinositol kinases and the state of phosphorylation at D3, D4, and D5 positions of inositol ring. PI 3, 4, 5-P3 involves in phagocytic cup formation and relates actin remodeling whereas PI 4, 5-P2-mediates the process of phagosomes formation and further fusion with early endosome. The necessary activation of actin-binding proteins such as Rac, WAVE complex, and ARP2/3 complex for the actin polymerization in the process of phagocytosis, migration is regulated and maintained by PI 3, 4, 5-P3 and PI 4, 5-P2. Dietary fatty acids depending on their ratio and types of intake influence secondary lipid messenger along with the cellular content of phaphatidylcholine and phosphatidylethanolamine. The deposited Aβ deposits and extracellular Tau seed disrupt levels of phosphatidylinositol and actin cytoskeletal changes that hamper microglia signaling pathways in AD. We hypothesize that being a lipid species intracellular levels of phosphatidylinositol would be regulated by dietary fatty acids. We keen to understand different types of phosphatidylinositol species levels in signaling events such as phagocytosis and actin remodeling owing to the exposure of various types of dietary fatty acids.
Subject: Medicine & Pharmacology, Nutrition Keywords: Alzheimer’s disease; lactoferrin; cognitive function; gut microbiota; amyloid β
Online: 17 February 2020 (01:00:26 CET)
Existing evidence suggest that lactoferrin might be beneficial for Alzheimer’s disease. We aimed to determine the effects of lactoferrin intervention on cognitive function from APP/PS1 mice, and possible mechanisms involved in. Both young and middle-aged male APP/PS1 mice were divided into control and lactoferrin group with 16 weeks’ intervention. Lactoferrin intervention had no effects on cognitive function from both young and middle-aged mice, and no key markers involved in Aβ, tau pathology, neuro-inflammation and synaptic plasticity were altered post lactoferrin intervention. In regards to gut microbiota profiles, in the young mice, lactoferrin elevated α diversity index including ACE and Chao 1, and reduced the relative abundance of the genera Bacteroides and Alistipes and elevated Oscillibacter, in addition, Oscillibacter, Anaerotruncus, EF096579_g, EU454405_g, Mollicutes_RF39, EU474361_g, EU774448_g, and EF096976_g were specifically abundant post Lf intervention via LEfSe analysis. In the middle-aged mice, the relative abundance of the phylum Proteobacteria, as well as the genera Oscillospira, Coprococcus and Ruminococcus was significantly reduced post Lf intervention, additionally, S24_7, Bacteroidia, Bacteroidetes and Methylobacterium were specific via LEfSe analysis post lactoferrin intervention. In conclusion, dietary lactoferrin might be beneficial for gut microbiota homeostasis although might have no effects on cognition.
ARTICLE | doi:10.20944/preprints201808.0448.v2
Subject: Life Sciences, Endocrinology & Metabolomics Keywords: Alzheimer’s disease; Diabetes; Diet control diet; AMPK; Tau hyperphosphorylation
Online: 8 October 2018 (15:32:11 CEST)
Alzheimer’s disease (AD) is a chronic neurodegenerative disease, and typical pathologic findings include abnormally hyperphosphorylated tau aggregation and neurofibrillary tangles. Insulin resistance and hyperglycemia have been assessed as risk factors for AD development. As the maintenance of optimal blood glucose levels is an important indicator of diabetes mellitus (DM) treatment, diet control is essential. AMPK is a crucial sensor of cellular bioenergetics for controlling anabolic and catabolic metabolism. Diet restriction to achieve euglycemia can increase AMPK activity in the liver and heart. Since AMPK is a direct regulator of tau phosphorylation, we hypothesized that strict diet control to achieve euglycemia affects tau protein phosphorylation through increased AMPK activity in the hippocampus of DM rats. To confirm this hypothesis, we generated insulin-deficient DM rats by subtotal pancreatectomy. Animals were categorized into the restriction (R) group, control (C) group and ad libitum (AL) group according to the diet. We found that tau phosphorylation was significantly increased in the R group compared with the C or AL group. AMPK activity in the R group significantly increased compared to that of the C group or AL group, as expected. Furthermore, the R group showed more critical tau pathology in the hippocampus than the other groups. These results suggest that diet control to achieve euglycemia in insulin-deficient DM conditions is harmful because of the increased possibility of AD development through increased tau phosphorylation by AMPK activation in the hippocampus. We propose that not only hyperglycemia but also euglycemia, which is beneficial in DM patients, must be considered a potential risk factor for AD development, especially when euglycemia is achieved by diet control during insulin deficiency.
ARTICLE | doi:10.20944/preprints202209.0290.v1
Subject: Life Sciences, Molecular Biology Keywords: Sulfatide; cerebroside sulfotransferase; ventricular enlargement; Alzheimer’s disease; brain MRI; aquaporins
Online: 20 September 2022 (03:56:30 CEST)
Alzheimer’s disease (AD) is a neurodegenerative disease characterized by progressive memory loss and a decline in activities of daily life. Ventricular enlargement has been associated with worse performance on global cognitive tests and AD. Our previous studies demonstrated that brain sulfatides, myelin-enriched lipids, are dramatically reduced in subjects at the earliest clinically recognizable AD stages via an apolipoprotein E (APOE)-dependent and isoform-specific process. Herein, we provided pre-clinical evidence that sulfatide deficiency is causally associated with brain ventricular enlargement. Specifically, taking advantage of genetic mouse models of global and adult-onset sulfatide deficiency, we demonstrated that sulfatide losses cause ventricular enlargement without significantly affecting hippocampal or whole brain volumes using histological and magnetic resonance imaging approaches. Mild decreases in sulfatide content and mild increases in ventricular areas were also observed in human APOE4 compared to APOE2 knock-in mice. Finally, we provided Western blot and immunofluorescence evidence that aquaporin-4, the most prevalent aquaporin channel in the central nervous system (CNS) that provides fast water transportation and regulates cerebrospinal fluid in the ventricles, is significantly increased under sulfatide-deficient conditions, while other major brain aquaporins (e.g., aquaporin-1) are not altered. In short, we unraveled a novel molecular mechanism that may contribute to ventricular enlargement in AD.
ARTICLE | doi:10.20944/preprints202207.0152.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: Alzheimer’s disease; oxidative stress; presenilin; mitochondria; calcium; neuronal dysfunction; Nrf2
Online: 11 July 2022 (08:03:08 CEST)
A Mitochondrial dysfunction and oxidative stress are major contributors to the pathophysiology of neurodegenerative diseases, including Alzheimer’s disease (AD). However, the mechanisms driving mitochondrial dysfunction and oxidative stress are unclear. Familial AD (fAD) is an early onset form of AD caused primarily by mutations in the presenilin-encoding genes. Previously, using Caenorhabditis elegans as a model system to study presenilin function, we found that loss of C. elegans presenilin orthologue, SEL-12, results in elevated mitochondrial and cytosolic calcium levels. Here, we provide evidence that elevated neuronal mitochondrial generated reactive oxygen species (ROS) and subsequent neurodegeneration in sel-12 mutants are a consequence of the increase of mitochondrial calcium levels and not cytosolic calcium levels. We also identify mTORC1 signaling as a critical factor in sustaining high ROS in sel-12 mutants in part through its repression of the ROS scavenging system SKN-1/Nrf. Our study reveals that SEL-12/presenilin loss disrupts neuronal ROS homeostasis by increasing mitochondrial ROS generation and elevating mTORC1 signaling, which exacerbates this imbalance by suppressing SKN-1/Nrf antioxidant activity.
ARTICLE | doi:10.20944/preprints202106.0576.v1
Subject: Chemistry, Analytical Chemistry Keywords: Hypericum oblongifolium; Alzheimer’s disease; Folecitin; Memory impairment; Neurodegenerative disease; Neuroprotection
Online: 23 June 2021 (11:25:28 CEST)
Neurological disorders, such as amyotrophic lateral sclerosis, Parkinson’s disease, and Alzheimer’s disease, are commonly associated with persistent neuro-inflammation, and there is an urgent need to discover new therapeutic agents that may target the various pathways involved in neurodegeneration. In this study, we investigated the therapeutic potential of folecitin, a flavonoid isolated from Hypericum oblongifolium, against lipopolysaccharide (LPS)-induced oxidative stress associated with neurodegeneration, amyloidogenic Aβ production pathway, and memory dysfunction in mice. LPS was administered i.p. at 250 µg/kg/day for 3 weeks, followed by the administration of folecitin at a dose of 30 mg/kg/day for the last two weeks. A Western blot technique was used to assess the expression of different proteins involved in oxidative stress, neurodegeneration, and neuronal synapse. Results indicated that folecitin significantly reduced LPS-induced apoptotic neurodegeneration, including the expression of BAX, Caspase-3, and PARP-1 proteins, inhibited BACE1, and the amyloidogenic Aβ production pathway. Folecitin improved both pre- and post-neuronal synapse, as well as memory dysfunction. Furthermore, folecitin significantly activated endogenous antioxidant proteins such as Nrf-2 and HO-1 via stimulating the phosphorylation of Akt proteins. These findings suggest that folecitin may be a suitable lead to design new drugs for neurotoxin-triggered neurodegenerative disorders.
ARTICLE | doi:10.20944/preprints202105.0556.v1
Subject: Life Sciences, Biochemistry Keywords: Alzheimer’s disease; amyloid-beta; amyloid plaques; bacterial DNA; protein aggregation
Online: 24 May 2021 (10:33:22 CEST)
Alzheimer’s disease is associated with prion-like aggregation of the amyloid β (Aβ) peptide and the subsequent accumulation of misfolded neurotoxic aggregates in the brain. Therefore, it is critical to clearly identify the factors that trigger the cascade of Aβ misfolding and aggregation. Numerous studies have pointed out the association between microorganisms and their virulence factors and Alzheimer’s disease; however, their exact mechanisms of action remain unclear. Recently, we discovered a new pathogenic role of bacterial extracellular DNA, triggering the formation of misfolded Tau aggregates. In this study, we investigated the possible role of DNA extracted from different bacterial and eukaryotic cells in triggering Aβ aggregation in vitro. Interestingly, we found that the extracellular DNA of some, but not all, bacteria is an effective trigger of Aβ aggregation. Furthermore, the acceleration of Aβ nucleation and elongation can vary based on the concentration of the bacterial DNA and the bacterial strain from which this DNA had originated. Our findings suggest that bacterial extracellular DNA might play a previously overlooked role in the Aβ protein misfolding associated with Alzheimer’s disease pathogenesis. Moreover, it highlights a new mechanism of how distantly localized bacteria can remotely contribute to protein misfolding and diseases associated with this process. These findings might lead to the use of bacterial DNA as a novel therapeutic target for the prevention and treatment of Alzheimer’s disease.
Subject: Life Sciences, Biochemistry Keywords: copper; amyloid-β peptides; Alzheimer’s disease; oxidative stress; dopamine; neurodegeneration.
Online: 26 April 2021 (13:23:52 CEST)
The redox chemistry of copper(II) is strongly modulated by the coordination to amyloid-β peptides and by the stability of the resulting complexes. Amino terminal copper and nickel binding motifs (ATCUN) identified in truncated Aβ sequences starting with Phe4 show very high affinity for copper(II) ions. Herein, we study the oxidase activity of [Cu-Aβ4-x] and [Cu-Aβ1-x] complexes toward dopamine and other catechols. The results show that the CuII-ATCUN site is not redox-inert, the reduction of the metal is induced by coordination of catechol to the metal and occurs through an inner sphere reaction. The generation of a ternary [CuII-Aβ-catechol] species determines the efficiency of the oxidation, although the reaction rate is ruled by re-oxidation of the CuI complex. In addition to the N-terminal coordination site, the two vicinal histidines, His13 and His14, provide a second Cu-binding motif. Catechol oxidation studies together with structural insight from the mixed dinuclear complexes Ni/Cu-Aβ4-x reveal that the His-tandem is able to bind CuII ions independently of the ATCUN site, but the N-terminal metal complexation reduces the conformational mobility of the peptide chain, preventing the binding and oxidative reactivity toward catechol of CuII bound to the secondary site.
ARTICLE | doi:10.20944/preprints201805.0335.v2
Subject: Life Sciences, Other Keywords: Alzheimer’s Dementia; anaerobic neurotoxicity; inflammation; neuronal apoptosis; Non-REM Sleep
Online: 4 June 2018 (13:16:46 CEST)
Research into the causes of neurotoxicity in Alzheimer’s Dementia (AD) has focused on neurofibrillary tangles and beta amyloid (Aβ) plaques. This paper proposes the heterodox theory that these hallmarks of AD are the visible effects, not direct causes of neuronal necrosis. Rather AD results from a combination of age-induced, disproportional decline in physiological support for aerobic metabolism, and dysregulation of the sleep cycle processes. The hypothesis is that the decimation of neurons in AD results from a combination of neurotoxicity and increased apoptosis caused by: 1. direct damage from toxic waste products of anaerobic glycolysis due to a progressive decline in the capacity of neurons to perform oxidative phosphorylation (OXPHOS) and an increased reliance on anaerobic glycolysis to meet metabolic needs; 2. impaired cellular repair and effluent release due to dysregulation of non-rapid eye movement (NREM) sleep allowing damage to cell membranes and synaptic junctions to accumulate inducing a chronic inflammatory response; 3. indirect damage from products produced by inflammatory reaction to toxic metabolites; 4. neuronal apoptosis from the AβPP-mediated pathway due to the age-induced decline of growth hormone (GH), GH-releasing hormone (GHRH) and insulin-like growth factor (IGF).
REVIEW | doi:10.20944/preprints202006.0203.v2
Subject: Life Sciences, Other Keywords: SH-SY5Y-derived neurons; TAU sorting; neuronal identity; tauopathy; Alzheimer’s disease
Online: 23 December 2020 (10:30:47 CET)
The microtubule-associated protein TAU is sorted into the axon in healthy brain neurons. Somatodendritic missorting of TAU is a pathological hallmark of many neurodegenerative diseases called tauopathies, including Alzheimer’s Disease (AD). Cause, consequence, and (patho)physiological mechanisms of TAU sorting and missorting are understudied, in part also due to the lack of readily available human neuronal model systems. The human neuroblastoma cell line SH-SY5Y is widely used for studying TAU physiology and TAU-related pathology in AD and related tauopathies. SH-SY5Y cells can be differentiated into neuron-like cells (SH-SY5Y-derived neurons) using various substances. This review evaluates whether SH-SY5Y-derived neurons are a suitable model for i) investigating intracellular TAU sorting in general, and ii) with respect to neuron subtype-specific TAU vulnerability. I) SH-SY5Y-derived neurons show pronounced axodendritic polarity, high levels of axonally localized TAU protein, expression of all six major human brain isoforms, and TAU phosphorylation similar to the human brain. As proliferative cells, SH-SY5Y cells are readily accessible for genetic engineering, stable transgene integration and leading-edge genome editing are valuable and promising tools for TAU-related studies. II) Depending on the used differentiation procedure, SH-SY5Y-derived neurons resemble cells of distinct subcortical nuclei, i.e. the Locus coeruleus (LC), Nucleus basalis (NB) and Substantia nigra (SN), all of which early affected in many tauopathies. This allows to analyse neuron-specific TAU isoform expression and intracellular localization, also in the context of vulnerability to TAU pathology. Limitations are e.g. the lack of mimicking age-related tauopathy risk factors and the difficulty to define the exact neuronal subtype of SH-SY5Y-derived neurons. In brief, this review discusses the suitability of SH-SY5Y-derived neurons for investigating TAU (mis)sorting mechanisms and neuron-specific TAU vulnerability in disease paradigms.
ARTICLE | doi:10.20944/preprints202011.0001.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Alzheimer’s Disease; Task Performance; Cognition; Human Activities; Amyloid Beta Protein; Dementia
Online: 2 November 2020 (08:06:39 CET)
The purpose of this study is to explore the effects of dual-task training, including cognitive tasks, on cognitive and bodily functioning and β-amyloid levels in Alzheimer's dementia patients. The subjects were 34 inpatients diagnosed with Alzheimer's dementia at a nursing hospital located in Gyeongsansi, South Korea. The patients were randomly divided into a dual-task group (n = 16) and a single-task group (n = 18). The dual-task group performed cognitive tasks at the same time as exercising tasks, while the single-task group performed only exercise tasks. Each group was trained for 30 minutes three times a week for eight weeks. The Mini-Mental State Examination was used to measure the patients’ cognitive function. Static and dynamic balance were measured to evaluate bodily functioning. Static balance was measured using Biorescue, while dynamic balance was measured using the Berg Balance Scale. Blood analysis was performed to measure levels of β-amyloid, which is known to cause Alzheimer's dementia. Both groups exhibited statistically significant improvements in gait function after the training (p < .05). The dual-task group exhibited statistically significant differences in cognitive function, static and dynamic balance function, and β-amyloid levels after training (p < .05). A significant difference was observed between the two groups (p < .05). Dual-task activities were found to be effective in improving cognitive and bodily functioning and reducing β-amyloid levels in Alzheimer's dementia patients. Therefore, dual-task training is thought to be an effective method of treating and preventing Alzheimer's dementia.
REVIEW | doi:10.20944/preprints201907.0289.v1
Subject: Medicine & Pharmacology, Nutrition Keywords: omega-3 polyunsaturated fatty acids; Parkinson’s disease; Alzheimer’s disease; clinical trials
Online: 25 July 2019 (11:38:57 CEST)
A nutritional approach could be a promising strategy to prevent or slow the progression of neurodegenerative diseases such as Parkinson’s and Alzheimer’s disease, since there is no effective therapy for these diseases so far. The beneficial effects of omega-3 fatty acids are now well established by a plethora of studies through their involvement in multiple biochemical functions, including synthesis of antinflammatory mediators, cell membrane fluidity, intracellular signalling and gene expression. This systematic review will consider epidemiological studies and clinical trials that assessed the impact of supplementation or dietary intake of omega-3 polyunsaturated fatty acids on neurodegenerative diseases such as Parkinson’s and Alzheimer’s diseases. Indeed, treatment with omega-3 fatty acids, being safe and well tolerated, represent a valuable and biologically plausible tool in the management of neurodegenerative diseases in their early stages.
ARTICLE | doi:10.20944/preprints201810.0022.v1
Subject: Keywords: Alzheimer’s disease; dementia; therapeutic environment; Virtual reality; Stress recovery; therapeutic gardens
Online: 2 October 2018 (11:03:03 CEST)
Purpose: This paper extends previous works to include the role of therapeutic gardens in the healing environment as an intervention for bettering the clinical outcomes of Alzheimer’s and dementia patients, the positive impact of healing gardens and the innovative application of technologies with nature, for promoting cognitive rehabilitation in this particular patient population.Methods: Using ISI Web of Science, PubMed, ProQuest Central, MEDLIN, Scopus and Google Scholar, a relevant literature search on the positive health implications of therapeutic gardens on Alzheimer’s and dementia patients’ in the healthcare milieu was conducted.Results: Health implication of therapeutic gardens on Alzheimer’s and dementia patients’ spans across physical, social, psychological and cognitive effects. Virtual reality (VR) technologies offer positive cognitive outcomes to Alzheimer's disease (AD) and dementia patients.Conclusion: Therapeutic gardens should be extended for speedier recovery of other patient populations. Future directions in the design of healthcare gardens with a focus on patient experience are inferred.
REVIEW | doi:10.20944/preprints202201.0241.v1
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: Diabetes Mellitus; Vascular Dementia; Alzheimer’s Disease; Inflammation; Atherosclerosis; Mitochondrial dysfunction; Cognitive dysfunction
Online: 17 January 2022 (15:46:10 CET)
Type 2 Diabetes Mellitus is being increasingly associated with dysfunction of cognition. Dementia, including vascular dementia and Alzheimer’s disease, is being recognized as comorbidities of this metabolic disorder. The progressive hallmarks of this cognitive dysfunction include mild impairment of cognition and cognitive decline. Dementia and mild impairment of cognition appear in older patients primarily. Studies on risk factors, neuropathology, and brain imaging have provided important suggestions for mechanisms that lie behind the development of dementia. It is a significant challenge to understand the disease processes related to diabetes which affect the brain and lead to dementia development. The connection between Diabetes Mellitus and dysfunction of cognition has been observed in many human and animal studies that have noted mechanisms related to Diabetes Mellitus are possibly responsible for aggravating cognitive dysfunction. This article attempts to narrate the possible association between type 2 diabetes and Dementia, reviewing studies that have noted this association in vascular dementia and Alzheimer’s disease and helping to explain the potential mechanisms behind the disease process. The Google search for ‘Diabetes Mellitus and Dementia’ was carried out. Also, the search was done using ‘Diabetes Mellitus,’ ‘Vascular Dementia,’ ‘Alzheimer’s Disease.’ The literature search was done from Google Scholar, Pubmed, Embase, ScienceDirect, and MEDLINE. Keeping in mind the increasing rate of Diabetes Mellitus, it is important to establish the type 2 diabetes effect on the brain and diseases of neurodegeneration. This narrative review aims to build awareness regarding different types of dementia and their relationship with diabetes.
ARTICLE | doi:10.20944/preprints202004.0318.v1
Subject: Life Sciences, Other Keywords: Alzheimer’s disease; amyloid β; β-secretase; bax; caspase; lamiaceae; mint; oxidative stress
Online: 19 April 2020 (03:57:56 CEST)
Alzheimer’s disease (AD) is a progressive neurodegenerative disorder that develops as a consequence of different factors such as oxidative stress and accumulation of the protein amyloid β (Aβ) in the brain, resulting in apoptosis of neuronal cells. The search for a treatment for this disorder is essential as current medications are limited to alleviating symptoms and palliative effects. The aim of this study is to investigate the effects of mint extracts on selected mechanisms implicated in the development of AD. To enable a thorough investigation of mechanisms, including effects on -secretase (the enzyme the leads to the formation of A), on Aβ aggregation, and on oxidative stress and apoptosis pathways, a neuronal cell model, SH-SY5Y cells was selected. Six Mentha taxa were investigated for their in vitro β-secretase (BACE) and Aβ-aggregation inhibition activities. Also, their neuroprotective effects on H2O2-induced oxidative stress and apoptosis in SH-SY5Y cells were evaluated through caspase activity. Real-time PCR and Western blot analysis were carried out for the two most promising extracts to determine their effects on signalling pathways in SH-SY5Y cells. All mint extracts had strong BACE inhibition activity. M. requienii extracts showed excellent inhibition of Aβ-aggregation, while other extracts showed moderate inhibition. M. diemenica and M. requienii extracts lowered caspase activity. Exposure of SH-SY5Y cells to M. diemenica extracts resulted in a decrease in the expression of pro-apoptotic protein, Bax, and an elevation in the anti-apoptotic protein, Bcl-xL, potentially mediated by down-regulation of ASK1-JNK pathway. These results indicate that mint extracts could prevent the formation of Aβ and also could prevent their aggregation if they had already formed. M. diemenica and M. requienii extracts have potential to suppress apoptosis at the cellular level. Hence, mint extracts could provide a source of efficacious compounds for a therapeutic approach for AD.
REVIEW | doi:10.20944/preprints202209.0069.v1
Subject: Medicine & Pharmacology, Psychiatry & Mental Health Studies Keywords: acetylated E2F4; synapsis; tissue homeostasis; Alzheimer’s disease; 5xFAD mice; neuroinflammation; microgliosis; reactive astrocytes.
Online: 5 September 2022 (13:52:27 CEST)
E2F4 was initially described as a transcription factor with a key function in the regulation of cell quiescence. Nevertheless, a number of recent studies have established that E2F4 can also play a relevant role in cell and tissue homeostasis as well as tissue regeneration. For these non-canonical functions, E2F4 can also act in the cytoplasm, where it is able to interact with many homeostatic and synaptic regulators. Since E2F4 is expressed in the nervous system, it may fulfill a crucial role in brain function and homeostasis, being a promising multifactorial target for neurodegenerative diseases and brain aging. The regulation of E2F4 is complex as it can be chemically modified through acetylation, from which we present evidence in the brain, as well as methylation, and phosphorylation. The phosphorylation of E2F4 within a conserved threonine motif induces cell cycle re-entry in neurons, while a dominant negative form of E2F4 (E2F4DN), in which the conserved threonines have been substituted by alanines, has been shown to act as a multifactorial therapeutic agent for Alzheimer’s disease (AD). We have generated transgenic mice neuronally expressing E2F4DN. We have recently shown using this mouse strain that expression of E2F4DN in 5xFAD mice, a known murine model of AD, improved cognitive function, reduced neuronal tetraploidization, and induced a transcriptional program consistent with modulation of amyloid-beta (Abeta) peptide proteostasis and brain homeostasis recovery. 5xFAD/E2F4DN mice also showed reduced microgliosis and astrogliosis in both cerebral cortex and hippocampus at 3-6 months of age. Here we have analyzed the immune response in 1 year-old 5xFAD/E2F4DN mice, concluding that reduced microgliosis and astrogliosis is maintained at this late stage. In addition, the expression of E2F4DN also reduced age-associated microgliosis in wild-type mice, thus stressing its role as a brain homeostatic agent. We conclude that E2F4DN transgenic mice represent a promising tool for the evaluation of E2F4 as a therapeutic target in neuropathology and brain aging.
REVIEW | doi:10.20944/preprints202207.0130.v1
Subject: Medicine & Pharmacology, Psychiatry & Mental Health Studies Keywords: Keywords: mitochondria; stress resilience; plasticity; stress; kynurenine; Alzheimer’s disease; neurodegenerative; depression; anxiety; psychiatric
Online: 8 July 2022 (03:56:36 CEST)
Nearly half a century has passed since the discovery of cytoplasmic inheritance of human chloramphenicol resistance. The inheritance was then revealed to take place maternally by mitochondrial DNA (mtDNA). Later, a number of mutations in mtDNA were identified as a cause of severe inheritable metabolic diseases with neurological manifestation, and the impairment of mitochondrial functions has been probed in the pathogenesis of a wide range of illnesses including neurodegenerative diseases. Recently growing number of preclinical studies has revealed that animal behaviors are influenced by the impairment of mitochondrial functions and possibly by the loss of mitochondrial stress resilience. Indeed, as high as 54% of patients with one of the most common primary mitochondrial diseases, mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome, present psychiatric symptoms including cognitive impairment, mood disorder, anxiety, and psychosis. Mitochondria are multifunctional organelles which produce cellular energy and play a major role in other cellular functions including homeostasis, cellular signaling, and gene expression, among other. Mitochondrial functions are observed to be compromised and to become less resilient under continuous stress. Meanwhile, stress and inflammation have been linked to the activation of the tryptophan (Trp)-kynurenine (KYN) metabolic system, which observably contributes to development of pathological conditions including neurological and psychiatric disorders. This narrative review discusses the functions of mitochondria and the Trp-KYN system, the interaction of the Trp-KYN system with mitochondria, and the current understanding of the involvement of mitochondria and the Trp-KYN system in preclinical and clinical studies of major neurological and psychiatric diseases.
REVIEW | doi:10.20944/preprints202005.0342.v1
Subject: Medicine & Pharmacology, Pharmacology & Toxicology Keywords: seaweed; metabolites; neuroprotection; Alzheimer’s disease; Parkinson’s disease; ischemic stroke; computer-aided drug discovery
Online: 21 May 2020 (09:49:29 CEST)
Beyond their significant contribution to the dietary and industrial supplies, marine algae are considered to be a potential source of some unique metabolites with diverse health benefits. The pharmacological properties, such as antioxidant, anti-inflammatory, cholesterol homeostasis, protein clearance and anti-amyloidogenic potentials of algal metabolites endorse their protective efficacy against oxidative stress, neuroinflammation, mitochondrial dysfunction, and impaired proteostasis which are known to be implicated in the pathophysiology of neurodegenerative disorders and the associated complications after cerebral ischemia and brain injuries. As was evident in various preclinical studies, algal compounds conferred neuroprotection against a wide range of neurotoxic stressors, such as oxygen/glucose deprivation, hydrogen peroxide, glutamate, amyloid β, or 1-methyl-4-phenylpyridinium (MPP+) and, therefore, hold therapeutic promise for brain disorders. While a significant number of algal compounds with promising neuroprotective capacity have been identified over the last decades, a few of them have had access to clinical trials. However, the recent approval of an algal oligosaccharide, sodium oligomannate, for the treatment of Alzheimer's disease enlightened the future of marine algae-based drug discovery. In this review, we briefly outline the pathophysiology of neurodegenerative diseases and brain injuries for identifying the targets of pharmacological intervention, and then review the literature on the neuroprotective potentials of algal compounds along with the underlying pharmacological mechanism, and present an appraisal on the recent therapeutic advances. We also propose a rational strategy to facilitate algal metabolites-based drug development.
ARTICLE | doi:10.20944/preprints201805.0380.v1
Subject: Chemistry, General & Theoretical Chemistry Keywords: molecular dynamics simulation; biophenols; natural compounds; amyloid fibrils; Alzheimer’s disease; ligand-protofiber interactions
Online: 27 May 2018 (13:09:22 CEST)
One of the principal hallmarks of Alzheimer’s disease (AD) is related to the aggregation of amyloid-β fibrils in an insoluble form in the brain, also known as amyloidosis. Therefore, a prominent therapeutic strategy against AD consists either in blocking the amyloid aggregation and/or destroying the already formed aggregates. Natural products have shown significant therapeutic potential as amyloid inhibitors from in vitro studies as well as in vivo animal tests. In this study, the interaction of five natural biophenols (curcumin, dopamine, (-)-Epigallocatechin-3-gallate, Quercetin, and Rosmarinic acid) with the amyloid-β(1-40) fibrils has been studied through computational simulations. The results allowed the identification and characterization of the different binding modalities of each compounds and their consequences on fibril dynamics and aggregation. It emerges that the lateral aggregation of the fibrils is strongly influenced by the intercalation of the ligands, which modulate the double-layered structure stability.
ARTICLE | doi:10.20944/preprints202107.0564.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Neurological activity; GC-MS; ADMET profile; Molecular Docking; Beta-amyloid precursor protein; Alzheimer’s disease
Online: 26 July 2021 (10:27:40 CEST)
Medicinal plants possess a surplus of novel and biologically active secondary metabolites that are responsible for counteracting diseases. Traditionally, Gomphandra tetrandra (Wall.) Sleumer is used to treat mental disorders. The present research was designed to explore phytochemicals from the ethanol leaf extract of Gomphandra tetrandra (Wall.) Sleumer to identify the potential pharmacophore(s) in the treatment of neurological disorders. The chemical compounds of the experimental plant were identified through GC-MS analysis. Besides, in-vitro antioxidant activity was assessed using different methods. Furthermore, in-vivo neurological activity was assessed in Swiss-albino mice. Computer aided analysis was appraised to determine the best-fit phytoconstituent of a total of fifteen identified compounds in the experimental plant extract against beta-amyloid precursor protein. The experimental extract revealed fifteen compounds in GC-MS analysis and the highest content was 9, 12, 15-octadecatrienoic acid (Z, Z, Z). Also, the extract showed potent anti-oxidant activity in in-vitro assays. Furthermore, in in-vivo neurological assays, the extract disclosed significant (p<0.05) neurological activity. The most favorable phytochemicals as neurological agents were selected via ADMET profiling and molecular docking was studied with beta-amyloid precursor protein. Moreover, in the computer aided study, 1, 5-Diphenyl-2H-1, 2, 4-triazoline-3-thione (Pub Chem CID: 2802516) was more active than other identified compounds with strong binding affinity to beta-amyloid precursor protein. The present in vivo and in silico studies revealed neuropharmacological features of G. tetrandra leaves extract as a natural agent against neurological disorders, especially Alzheimer’s disease.
REVIEW | doi:10.20944/preprints201901.0275.v1
Subject: Medicine & Pharmacology, Other Keywords: canine enteroid/colonoids; gut-on-a-chip; translational medicine; Alzheimer’s disease; canine cognitive disfunction
Online: 28 January 2019 (10:30:57 CET)
Identifying appropriate animal models is critical in developing translatable in vitro and in vivo systems for therapeutic development and investigating disease pathophysiology. These animal models should have direct biological and translational relevance to the underlying disease they are supposed to mimic. Aging dogs naturally develop a cognitive decline in many aspects including learning and memory, but also exhibit human-like individual variability in the aging process. Neurodegenerative processes that can be observed in both human and canine brains include the progressive accumulation of β-amyloid (Aβ) found as diffuse plaques in the prefrontal cortex, including the gyrus proreus, the hippocampus, and in the cerebral vasculature. A growing body of epidemiological data shows that human patients with neurodegenerative diseases have concurrent intestinal lesions, and histopathological changes in the gastrointestinal (GI) tract occurs decades that evolve before neurodegenerative changes. Gut microbiome alterations also have been observed in many neurodegenerative diseases including Alzheimer’s and Parkinson’s diseases, and inflammatory CNS diseases. Interestingly, only recently has the dog gut microbiome been recognized to more closely resemble in composition and in functional overlap with the human gut microbiome as compared to rodent models. This article aims to review the physiology of the gut-brain axis (GBA), and its involvement with neurodegenerative diseases in dogs and humans. Additionally, we outline the advantages and disadvantages of traditional in vitro and in vivo models and discuss future research directions investigating major human neurodegenerative diseases such as Alzheimer’s and Parkinson’s diseases using dogs.
ARTICLE | doi:10.20944/preprints201705.0144.v1
Subject: Biology, Animal Sciences & Zoology Keywords: Alzheimer’s disease (AD); amyloid-β1-42(Aβ1–42); Lycium ruthenicum Murray (LRA); neuroprotective effect
Online: 19 May 2017 (06:26:45 CEST)
Alzheimer’s disease (AD) is an age-related neurodegenerative disease and is clinically characterized by cognitive impairment, memory loss, and personality disorder. Oligomers of amyloid beta-peptides (Aβ) and enhanced oxidative stress in senile plaques are prevalent pathologic hallmarks of AD. In this study, we detected the behavioral performance of Lycium ruthenicum Murray anthocyanin (LRA) -treated rats using the Morris water maze test and then investigated the effect of LRA on oxidative damage, neuronal apoptosis, and inflammatory response induced by Aβ1–42. Our results showed that LRA treatment markedly ameliorated the behavioral performance of Aβ1–42-induced rats and reduced the level of malondialdehyde, formation of protein carbonyl, and 8-hydroxy-2’-deoxygua-nosine. Furthermore, LRA also inhibited activated astrocytes and neuroinflammation via suppression of glial fibrillary acidic protein and tumor necrosis factor-alpha in the hippocampus of Aβ1–42-treated rat brain. These data suggest that LRA could be a potential anti-oxidant and anti-neuroinflammatory agent for the treatment of AD.
REVIEW | doi:10.20944/preprints202103.0783.v1
Subject: Medicine & Pharmacology, Pharmacology & Toxicology Keywords: ursolic acid; oleanolic acid; neuroprotection; ischaemia; neurodegeneration; Alzheimer’s disease; Parkinson’s disease; neuro-inflammation; cancer; glioblastoma
Online: 31 March 2021 (16:17:04 CEST)
Ursolic and oleanolic acids are secondary plant metabolites that are known to be involved in the plant defence system against water loss and pathogens. Nowadays these triterpenoids are also regarded as potential pharmaceutical compounds and there is mounting experimental data that either purified compounds or triterpenoid-enriched plant extracts exert various beneficial effects, including anti-oxidative, anti-inflammatory and anticancer, on model systems of both human or animal origin. Some of those effects have been linked to the ability of ursolic and oleanolic acids to modulate intracellular antioxidant systems and also inflammation- and cell death-related pathways. Therefore, our aim was to review the current knowledge about the distribution of ursolic and oleanolic acids in plants, bioavailability and pharmacokinetic properties of these triterpenoids and their derivatives, and to discuss their neuromodulatory effects in vitro and in vivo.
REVIEW | doi:10.20944/preprints202009.0732.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Rosemary; Alzheimer’s disease; cognition; meta-analysis; preclinical study; mild cognitive dysfunction; herbal drugs; rosmarinic acid
Online: 30 September 2020 (10:04:01 CEST)
Background: Patients with mild cognitive impairment end up progressing to Alzheimer’s disease (AD) leading to straining burden on public health. R. officinalis long been known as the herb of remembrance and can be a potential cognition enhancer for AD. The aims of the review were to summarize the qualitative and quantitative aspects of R.O and its active constituents in enhancing the cognition. MATERIALS AND METHOD Google scholar and PubMed structured search to find relevant studies that assessed the effect of R.O extract or any of its active constituents on cognitive performance in animals. Data extraction: Following information from each included study was extracted: (1) article information (2) characteristics of study animals (3) type of intervention; type, dose, duration, and frequency of administration of R.O (4) type of outcome measure. Data synthesis: Data were analyzed using Review Manager (RevMan 5.3, 2014] and meta-analysis was performed for the outcome measures on all relevant tasks within the included papers by computing the standardized mean difference ps. RESULTS. 23 studies for qualitative and fifteen for meta-analysis were selected. From fifteen included papers, 22 studies with 35 comparisons were meta-analyzed. Effect sizes for intact animals and impaired animals respectively was (mean g and 95% CI 1.19 [0.74, 1.64; 0.57 [0.19,0.96]. The R. officinalis had positive effect on both groups of animals. The subgroup analyses exhibited substantial unexplained heterogeneity between studies. Mechanisms of R.O was anticholinesterase, procholinergic, antioxidant, anti-amyloid, neuroprotective and anti-inflammatory agent CONCLUSIONS: R.O improves cognitive function. Limitations: Considerable heterogeneity between studies.
REVIEW | doi:10.20944/preprints202109.0376.v1
Subject: Life Sciences, Other Keywords: Alzheimer’s disease; Parkinson’s disease; Aβ cascade hypothesis; a-synuclein aggregation and spreading; transcriptomics of nervous system
Online: 22 September 2021 (11:33:22 CEST)
Alzheimer’s and Parkinson's diseases (AD and PD) are amongst top of the prevalent neurodegenerative disease. One-third of PD patients are diagnosed with dementia, a pre-symptom of AD, but the underlying mechanism is elusive. Amyloid beta (Aβ) and α-synuclein are two of the most investigated proteins, whose pathological aggregation and spreading are crucial to the pathogenesis of AD and PD, respectively. Transcriptomic studies of the mammalian central nervous system shed light on gene expression profiles at molecular levels, regarding the complexity of neuronal morphologies and electrophysiological inputs/outputs. In the last decade, the booming of the single-cell RNA sequencing technique helped to understand gene expression patterns, alternative splicing, novel transcripts, and signal pathways in the nervous system at single-cell levels, providing insight for molecular taxonomy and mechanistic targets of the degenerative nervous system. Here, we re-visited the cell-cell transmission mechanisms of Aβ and α-synuclein in medi-ating disease propagation, and summarized recent single-cell transcriptome sequencing from different perspectives and discussed its understanding of neurodegenerative diseases.
ARTICLE | doi:10.20944/preprints202001.0244.v1
Subject: Life Sciences, Molecular Biology Keywords: Stress; epigenetics; senescence; cognition; age-related cognitive decline; Alzheimer’s disease; SAMP8; SAMR1; oxidative stress; inflammation; autophagy
Online: 21 January 2020 (11:44:35 CET)
Cognitive and behavioural disturbances are growing public healthcare issue for the modern society, as stressful lifestyle is becoming more and more common. Besides, several pieces of evidence state that environment is crucial in the development of several diseases as well as compromising healthy aging. Therefore, it is important to study the effects of stress on cognition and its relationship with aging. To address these queries, Chronic Mild Stress (CMS) paradigm was used in the senescence-accelerated mouse prone 8 (SAMP8) and resistant 1 (SAMR1). On one hand, we determined the changes produced in the three main epigenetic marks after 4 weeks of CMS treatment, such as a reduction in histone posttranslational modifications and DNA methylation, and up-regulation or down-regulation of several miRNA involved in different cellular processes in mice. In addition, CMS treatment induced reactive oxygen species (ROS) accumulation and loss of antioxidant defence mechanisms, as well as inflammatory signalling activation through NF-κB pathway and astrogliosis markers, like Gfap. Remarkably, CMS altered mTORC1 signalling in both strains, decreasing autophagy only in SAMR1 mice. We found a decrease in glycogen synthase kinase 3 β (GSK-3β) inactivation, hyperphosphorylation of Tau and an increase in sAPPβ protein levels in mice under CMS. Moreover, reduction in the non-amyloidogenic secretase ADAM10 protein levels was found in SAMR1 CMS group. Consequently, detrimental effects on behaviour and cognitive performance were detected in CMS treated mice, affecting mainly SAMR1 mice, promoting a turning to SAMP8 phenotype. In conclusion, CMS is a feasible intervention to understand the influence of stress on epigenetic mechanisms underlying cognition and accelerating senescence.
ARTICLE | doi:10.20944/preprints201712.0106.v2
Subject: Life Sciences, Biochemistry Keywords: graphene; electrochemical biosensors; cancer; diagnosis; electrical detection; Alzheimer’s disease; dementia; neurodegenerative disorders; cardiovascular; blood biomarkers; antibodies; proteins
Online: 2 January 2018 (05:21:45 CET)
We report on the development of chemical vapour deposition (CVD) based graphene field effect transistor (GFET) immunosensors for the sensitive detection of Human Chorionic Gonadotropin (hCG), a glycoprotein risk biomarker of certain cancers. The GFET sensors were fabricated on Si/SiO2 substrate using photolithography with evaporated chromium and sputtered gold contacts. GFET channels were functionalized with a linker molecule to immobile anti-hCG antibody on the surface of graphene. Binding reaction of the antibody with varying concentration levels of hCG antigen demonstrated the limit of detection of the GFET sensors to be below 1 pg/mL using four-probe electrical measurements. We also show annealing can significantly improve the carrier transport properties of GFETs and shift the Dirac point (Fermi level) with reduced p-doping in back-gated measurements. The developed GFET biosensors are generic and could find applications in a broad range of medical diagnostics in addition to cancer, such as neurodegenerative (Alzheimer’s, Parkinson’s and Lewy body) and cardiovascular disorders.
REVIEW | doi:10.20944/preprints202110.0197.v1
Subject: Medicine & Pharmacology, Cardiology Keywords: AGING; Age-related comorbidities; Angiotensin-Converting Enzyme; Amyloid-degrading enzyme; Alzheimer’s disease; Dementia; Hypertension; Life extension; Stress resistance
Online: 13 October 2021 (11:04:43 CEST)
A recent report from the American Heart Association in 2018 shows that over 103 million American adults have hypertension. The angiotensin-converting enzyme (ACE) (EC 188.8.131.52) is a dipeptidyl carboxylase that, when inhibited, can reduce blood pressure through the renin-angiotensin system. ACE inhibitors are used as a first-line medication to be prescribed to treat hypertension, chronic kidney disease, heart failure among others. It has been suggested that ACE inhibitors can reduce the symptoms in mouse models. Despite the benefits of ACE inhibitors, previous studies also have suggested that alterations in the ACE gene are risk factors for Alzheimer’s disease (AD) and other neurological diseases. In mice, overexpression of ACE in the brain reduces symptoms of the AD-model systems. Thus, we find opposing effects of ACE on health. To clarify the effects, we dissect the functions of ACE as follows: (1) angiotensin-converting enzyme that hydrolyzes angiotensin I to make angiotensin II in the renin-angiotensin system; (2) amyloid-degrading enzyme that can hydrolyze beta-amyloid and reduce amyloid toxicity. The efficacy of the ACE inhibitors is well established in humans, while the knowledge specific to AD remains to be open for further research. We provide an overview of ACE and inhibitors that link a wide variety of age-related comorbidities from hypertension to Alzheimer’s disease to aging. ACE also serves as an example of the middle-life crisis theory that assumes deleterious events during the midlife, leading to age-related later events.
ARTICLE | doi:10.20944/preprints202012.0635.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Free fatty acid receptor 2; microbiota; metabolite; sensor; G-coupled protein receptor; signaling; Alzheimer’s disease; senescence; C. elegans
Online: 24 December 2020 (14:56:00 CET)
Gut microbiota and its metabolites like short chain fatty acids (SCFAs) are linked with pathology of Alzheimer’s disease (AD)- a debilitating public health problem in older adults. However, strategies to beneficially modulate gut microbiota and its sensing signaling pathways remain largely unknown. Here, we screened, validated and established the agonists of free fatty acid receptor 2 (FFAR2) signaling, which senses beneficial signals from SCFAs produced by microbiota in the gut. We demonstrated that inhibition of FFAR2 signaling increases amyloid-beta (Aβ) stimulated neuronal toxicity. Thus, we screened FFAR2 agonists, using in-silico library of more than 144,000 natural compounds, and 15 compounds were selected based on binding with FFAR2 agonist sites. Further, cell culture toxicity and FFAR2 stimulatory experiments demonstrated that Fenchol (a natural compound commonly present in basil) was potent FFAR2 agonist in neuronal cells. Interestingly, we also demonstrated that Fenchol protects Aβ-stimulated neurodegeneration in FFAR2 dependent manner. In addition, Fenchol reduced AD like phenotypes such as Aβ-accumulation and, learning and memory behaviors in Caenorhabditis (C.) elegans. Fenchol increased Aβ-clearance by increasing proteasome/lysosome activity and reduced senescence in neuronal cells. These results demonstrated that the inhibition of FFAR2 signaling promotes Aβ-induced neurodegeneration, while activating it by Fenchol as a natural agonist reverse it by promoting Aβ-clearance and reducing cellular senescence; thus stimulation of FFAR2 signaling can be a therapeutic approach to prevent/ treat AD.
REVIEW | doi:10.20944/preprints202011.0396.v1
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: neurodegenerative disease; Alzheimer’s disease; Parkinson’s disease; amyotrophic lateral sclerosis; Huntington’s disease; multiple sclerosis; tryptophan; kynurenines; biomarkers; personalized medicine
Online: 13 November 2020 (20:57:22 CET)
Neurodegenerative diseases are multifactorial, initiated by a series of the causative complex which develops into a certain clinical picture. The pathogenesis and disease course vary from patient to patient. Thus, it should be likewise to the treatment. Peripheral biomarkers are to play a central role for tailoring a personalized therapeutic plan for patients who suffered from neurodegenerative diseases such as Alzheimer’s diseases, Parkinson’s disease, and multiple sclerosis, among others. Nevertheless, the use of biomarkers in clinical practice is still underappreciated and data presented in biomarker research for clinical use is still uncompelling, compared to abundant data available for drug research and development. So is the case with kynurenines (KYNs) and the kynurenine pathway (KP) enzymes which have been associated with a wide range of diseases including cancer, autoimmune diseases, inflammatory diseases, neurologic diseases, and psychiatric disorders. This review article discusses current knowledge of the KP alteration observed in the central nervous system as well as the periphery, its involvement in pathogenesis and disease progression, and emerging evidence of roles of microbiota to the gut-brain axis, searching for practical peripheral biomarkers which ensure personalized treatment plans for neurodegenerative diseases.
REVIEW | doi:10.20944/preprints201802.0190.v1
Subject: Life Sciences, Biotechnology Keywords: Alzheimer’s disease; biomimetic nanocarriers; blood-brain barrier; dementia; drug targeting; lipid cubic phases; nanoemulsion; SR-BI; scavenger receptors
Online: 28 February 2018 (07:49:13 CET)
Over past decades, a frequent co-morbidity of cerebrovascular pathology and Alzheimer's disease pathology has been observed. Numerous published studies indicate that preservation of healthy cerebrovascular endothelium can be an important therapeutic target. By incorporating appropriate drug(s) into biomimetic (lipid cubic-phase) nanocarriers, one obtains a multitasking combination therapeutic which targets certain cell-surface scavenger receptors, mainly class B type 1 (i.e., SR-BI), and crosses the blood-brain barrier. This targeting allows for various Alzheimer’s-related cell types to be simultaneously searched out for localized drug treatment in vivo.
REVIEW | doi:10.20944/preprints202103.0219.v1
Subject: Life Sciences, Biochemistry Keywords: Alzheimer’s disease; blood-brain barrier; endothelial cell; laminin; multiple sclerosis; pericyte; perivascular macrophage; sonic hedgehog; vascular smooth muscle cell
Online: 8 March 2021 (13:35:25 CET)
Pericytes are increasingly recognized as being important in the control of blood-brain barrier permeability and vascular flow. Research on this important cell type has been hindered by widespread confusion regarding the phenotypic identity and nomenclature of pericytes and other perivascular cell types. In addition, pericyte heterogeneity and mouse-human species differences have contributed to confusion. Herein we summarize our present knowledge on the identification of pericytes and pericyte subsets in humans, primarily focusing on recent findings in humans and nonhuman primates. Precise identification and definition of pericytes and pericyte subsets in humans may help us to better understand pericyte biology and develop new therapeutic approaches specifically targeting disease-associated pericyte subsets.
REVIEW | doi:10.20944/preprints202102.0193.v1
Subject: Biology, Anatomy & Morphology Keywords: mild cognitive impairment (MCI); mild dementia; Alzheimer’s disease; Ginkgo biloba (EGb761®); Tebonin; anti-dementia drugs; randomized controlled trials
Online: 8 February 2021 (11:37:05 CET)
Mild cognitive impairment (MCI) and mild dementia are a clinically relevant health problem in the elderly and Alzheimer's disease being the most common neurodegenerative disorder. Furthermore, MCI and mild dementia are characterized by a deterioration of cognitive function and their diagnosis is mainly based on cognitive examination and, the prognosis of the disease seems to be an essential reason for the diagnosis, because there is a high risk of cognitive decline in the two syndromes. This review describes the effectiveness of Ginkgo biloba (EGb761®) leaf extract for the treatment of dementia syndrome and EGb761® combination therapy with other medications for symptomatic dementia. Tebonin® is a drug of plant origin based on the active ingredient “Ginkgo biloba”. This drug has shown encouraging results, improving cognitive function, neuropsychiatric disorders and consequent reduction of caregiver stress and maintenance of autonomy in patients with age-related cognitive decline, MCI and mild dementia. Nowadays, there is little evidence to support the efficacy of EGb761® combination therapy with anti-dementia drugs and, therefore, more evidence is needed to evaluate the role of EGb761® in mixed therapy.
REVIEW | doi:10.20944/preprints202204.0189.v1
Subject: Life Sciences, Other Keywords: astrocytes; reactive astrogliosis; TGF-β; traumatic brain injury; stroke; aging; Alzheimer’s disease; Parkinson’s disease; amyotrophic lateral sclerosis; multiple sclerosis; epilepsy
Online: 20 April 2022 (09:06:47 CEST)
Astrocytes are essential for normal brain development and functioning. They respond to brain injury and disease through a process referred to as reactive astrogliosis, where the reactivity is highly heterogenous and context dependent. Reactive astrocytes are active contributors to brain pathology and can exert beneficial, detrimental, or mixed effects following brain insults. Transforming growth factor-β (TGF-β) has been identified as one of the key factors regulating astrocyte reactivity. Genetic and pharmacological manipulation of TGF-β signaling pathway in animal models of CNS injury and disease alters pathological and functional outcomes. This review aims to provide recent understanding regarding astrocyte reactivity and TGF-β signaling in brain injury, aging, and neurodegeneration. Further, it explores how TGF-β signaling modulates astrocyte reactivity and function.
ARTICLE | doi:10.20944/preprints201811.0463.v1
Subject: Life Sciences, Other Keywords: Mass Spectroscopy, Bioinformatics, FGF14, Voltage Gated Channels, Schizophrenia, Alzheimer’s Disease, Sex-Specific Differences, Synaptic Plasticity, Cognitive Impairment, Excitatory/Inhibitory Tone
Online: 19 November 2018 (11:54:50 CET)
Fibroblast growth factor 14 (FGF14) is a member of the intracellular FGFs, a group of proteins with roles in neuronal ion channel regulation and synaptic transmission. We have previously demonstrated that a male Fgf14-/- mouse model recapitulates salient endophenotypes of synaptic dysfunction and behaviors associated with schizophrenia (SZ). As the underlying etiology of SZ and its sex-specific onset remain elusive, the Fgf14-/- model provides a valuable tool to interrogate pathways that might be related to the disease mechanism. Here, we performed label free quantitative proteomics and bioinformatics to identify enriched pathways at the proteome level in the male and female hippocampi from Fgf14+/+ and Fgf14-/- mice. We discovered that many differentially expressed proteins in Fgf14-/- animals are associated with SZ. In addition, measured changes in the proteome and signaling pathways were predominantly sex-specific with the male Fgf14-/- being distinctly enriched for pathways associated with neuropsychiatric disorders and addiction and the female exhibiting modest changes. In the male Fgf14-/- mouse the major protein changes that could in part explain the previously described neurotransmission and behavioral phenotype of this model were loss of ALDH1A1 and PRKAR2B. ALDH1A1 has been shown to mediate an alternative pathway for GABA synthesis, while PRKAR2B is essential for dopamine 2 receptor signaling, which is the basis of current antipsychotics. Collectively, our results provide new insights in the role of FGF14 and support the use of the Fgf14-/- mouse as a useful preclinical model of SZ for generating hypothesis on the disease mechanism, sex-specific manifestation and therapy.
REVIEW | doi:10.20944/preprints201802.0077.v1
Subject: Medicine & Pharmacology, Pharmacology & Toxicology Keywords: nose to brain delivery; nanoparticles; pharmaceutical nanotechnology; mucoadhesion; mucus penetrating particles; targeting; CNS disorders; neurodegenerative diseases; Alzheimer’s disease; Parkinson’s disease
Online: 9 February 2018 (10:37:33 CET)
In the field of nasal delivery, one of the most fascinating applications is the delivery of drugs directly to the central nervous system bypassing the blood brain barrier. This approach would provide a series of benefits, such as dose lowering and direct targeting of potent drugs, ultimately reducing their systemic side effects. Recently, clinical trials have explored the nasal administration of insulin for the treatment of Alzheimer’s disease, with promising results. The use of nanomedicines could provide further options for making nose-to-brain delivery reality. In particular, apart from the selection of devices able to deposit the formulation in the upper part of the nose, surface modification of these nanomedicines appears the key strategy to optimize the delivery of drugs from the nasal cavity to the brain. In this review, nanomedicines delivery approaches based on surface electrostatic charges, mucoadhesive polymers, as well as chemical moieties targeting nasal epithelium, will be discussed and critically evaluated for nose-to-brain delivery.
ARTICLE | doi:10.20944/preprints201804.0079.v1
Subject: Life Sciences, Molecular Biology Keywords: Alzheimer’s disease (AD); amyloid precursor protein (APP); familial AD (FAD); sporadic AD (SAD); BACE1 inhibitors; APP-independent generation of beta amyloid
Online: 6 April 2018 (15:16:08 CEST)
The present article analyzes the results of recent clinical trials of beta secretase inhibition in sporadic Alzheimer’ disease (SAD), considers the striking dichotomy between successes in tests of BACE1 inhibitors in healthy subjects and familial AD (FAD) models versus persistent failures of clinical trials and interprets it as a confirmation of key predictions for a mechanism of APP-independent, beta secretase inhibition-resistant production of beta amyloid in SAD, previously proposed by us. In the light of this concept, FAD and SAD should be regarded as distinctly different diseases as far as beta-amyloid generation mechanisms are concerned, and whereas beta secretase inhibition would be neither applicable nor effective in treatment of SAD, the BACE1 inhibitor(s) deemed failed in SAD trials could be perfectly suitable for treatment of FAD. Moreover, targeting the aspects of AD other than cleavages of the APP by beta and alpha secretases should have analogous impacts in both FAD and SAD.
REVIEW | doi:10.20944/preprints201707.0019.v1
Subject: Chemistry, Medicinal Chemistry Keywords: affective disorders; alzheimer’s disease; l-Deprenyl (Selegiline); donepezil; galantamine; value; inhibitor constant; mechanism-based inhibition; multitarget-directed ligand (MTDL); rasagiline; rivastigmine
Online: 11 July 2017 (05:58:53 CEST)
The actions of many drugs involve enzyme inhibition. This is exemplified by the inhibitors of monoamine oxidases (MAO) and the cholinsterases (ChE) that have been used for several pharmacological purposes. This review describes key principles and approaches for the reliable determination of enzyme activities and inhibition as well as some of the methods that are in current use for such studies with these two enzymes. Their applicability and potential pitfalls arising from their inappropriate use are discussed. Since inhibitor potency is frequently assessed in terms of the quantity necessary to give 50% inhibition (the IC50 value), the relationships between this and the mode of inhibition is also considered, in terms of the misleading information that it may provide. Incorporation of more than one functionality into the same molecule to give a multi-target-directed ligands (MTDLs) requires careful assessment to ensure that the specific target effects are not significantly altered and that the kinetic behaviour remains as favourable with the MTDL as it does with the individual components. Such factors will be considered in terms of recently developed MTDLs that combine MAO and ChE inhibitory functions.
REVIEW | doi:10.20944/preprints201710.0006.v1
Subject: Medicine & Pharmacology, Nutrition Keywords: essential fatty acids; ascorbic acid; glutathione; aging; parkinson’s disease; alzheimer’s disease; senescence; nervous system; growth factors; neuroprotection; docosahexaenoic acid; α-linolenic acid.
Online: 2 October 2017 (08:59:13 CEST)
Polyunsaturated fatty acids (PUFAs) and antioxidants are important mediators in the central nervous system (CNS). Lipid derivatives may be used to generate endocannabinoids or prostanoids derived from arachidonic acid, which attenuates excitotoxicity in quadripartite synapses with a focus in astrocytes and microglia; on the other hand, antioxidants, such as glutathione (GSH) and ascorbate, have been shown to signal through transmitter receptors and protect against acute and chronic oxidative stress, modulating the activity of different signaling pathways. Several authors have investigated the role of these nutrients in young and senescent brain, as well as in degenerative conditions such as Alzheimer’s and Parkinson's diseases. Through literature review, we aimed to highlight recent data on the role of fatty acids, antioxidants and physical activity in physiology and in molecular mechanisms of brain senescence. Data indicate the complexity and essentiality of endogenous/dietary antioxidants for maintenance of the redox status and control of neuroglial signaling under stress. Recent studies also indicate that omega-3 and -6 fatty acids act in a competitive manner to generate mediators for energy metabolism, feeding behavior, plasticity and memory mechanisms throughout aging. Finding pharmacological or dietary resources that mitigate or prevent neurodegenerative affections continues to be a great challenge and require additional efforts from researchers, clinicians and nutritionists in the field.
REVIEW | doi:10.20944/preprints202207.0171.v1
Subject: Medicine & Pharmacology, Behavioral Neuroscience Keywords: Alzheimer’s; aging; amygdala; brain plasticity; CA1; CA3; chronic stress; cognition; GABA; HIF-1; hippocampus; hypoxia; neurogenesis; Parkinson’s; prefrontal cortex; PSA-NCAM; ROS; spatial learning
Online: 12 July 2022 (04:25:55 CEST)
Stress plays a central role in functioning for all life forms. As humans, we experience stress in a multitude of ways through various types of stimuli. Due to the constancy of stressors in our lives, the nervous system has learned to allosterically adapt to the stimuli, but when the body cannot adapt, chronic stress can have morphological and degenerative impacts on neuroanatomy and cognitive function that may or may not be reversible. This literature review aimed to identify the specific neuroanatomical structures impacted most by the long-term effects of chronic stress and the subsequent relationship the morphological changes had on cognitive function in rodent models. We examined articles published from PubMed, Google Scholar, and Science Direct, while focusing the search on anatomical and neurodegenerative effects associated with chronic stress stimuli. The degenerative effects of various types simulated physiological chronic stress showed the most impact on neurogenesis and neuronal development, brain plasticity, and spatial learning and memory with association to the hippocampus. The hippocampus, amygdala, prefrontal cortex, and hypothalamic-pituitary-adrenal axis (HPA) all had reversible and non-reversible morphological alterations, which also had a direct impact on the brain’s cognitive abilities. While studies regarding chronic stress are still being conducted, future research may be able to further highlight why stressful stimuli can particularly impact these structures and the tangential impacts that it may have on related or adjacent structures.
REVIEW | doi:10.20944/preprints202208.0383.v1
Subject: Life Sciences, Genetics Keywords: Calabria; Italy; neurodegenerative diseases; Alzheimer’s disease; Frontotemporal dementia; Par-kinson’s disease; Niemann Pick type C disease; Spino-cerebellar ataxia; Creutzfeldt–Jakob disease; Gerstmann Straussler Scheincker disease
Online: 22 August 2022 (11:23:49 CEST)
Although originally multi-ethnic in its structure, nowadays the Calabria region of southern Italy represents an area with a low genetic heterogeneity and a high level of consanguinity that allows rare mutations to be maintained due to the founder effect. A complex research methodology ranging from clinical activity to genealogical reconstruction of families/populations along the centuries, creation of databases, and molecular/genetic research, has been modelled on the characteristics of the Calabrian population for more than three decades. This methodology allows to the identification of several novel genetic mutations or variants associated with neurodegenerative diseases. In addition, in this population it has been reported a higher prevalence of several hereditary neurodegenerative diseases such as Alzheimer’s disease, Frontotemporal dementia, Parkinson’s disease, Niemann Pick type C disease, Spino-cerebellar ataxia, Creutzfeldt–Jakob disease and Gerstmann Straussler Scheincker disease. Thus, Calabria constitutes a model for the study of neurodegenerative diseases, a sort of "outdoor laboratory" useful for the advancement of knowledge in this field. Here, we summarize and discuss some results of research data supporting the view that Calabria is a genetic isolate and could represent a useful model for the study and characterization of neurodegenerative diseases.
REVIEW | doi:10.20944/preprints202209.0139.v1
Subject: Medicine & Pharmacology, General Medical Research Keywords: Bacillus Calmette-Guérin (BCG); tuberculosis; Non-tuberculous mycobacteria (NTM); nonspecific effects; Trained Immunity; Type 1 Diabetes; Multiple Sclerosis; Parkinson’s Disease; Alzheimer’s disease; Mycobacterium avium ss. paratuberculosis (MAP); molecular mimicry; Global Burden of Disease
Online: 12 September 2022 (09:36:16 CEST)
The Bacillus Calmette-Guérin (BCG) vaccine has been used for over one hundred years to protect against the most lethal infectious agent in human history, tuberculosis. Over four billion BCG doses have been given and, worldwide, most newborns receive BCG. A few countries, including the United States, did not adopt the WHO recommendation for routine use of BCG. Moreover, within the past several decades, most of Western Europe and Australia, having originally employed routine BCG, have discontinued its use. This review article articulates the impacts of those decisions. The associated consequences include increased tuberculosis, increased infections caused by non-tuberculous mycobacteria (NTM), increased autoimmune disease (autoimmune diabetes and multiple sclerosis) and increased neurodegenerative disease (Parkinson’s disease and Alzheimer’s disease). This review also offers an emerged zoonotic pathogen, Mycobacterium avium ss. paratuberculosis (MAP) as a mostly unrecognized NTM that may have a causal role in some, if not all, of these diseases. Current clinical trials with BCG for varied infectious, autoimmune and neurodegenerative diseases have brought this century-old vaccine to the fore due to its presumed immuno-modulating capacity. With its historic success and strong safety profile, the new and novel applications for BCG may lead to its universal use –putting the Western World back onto the road not taken.
ARTICLE | doi:10.20944/preprints202208.0176.v1
Subject: Behavioral Sciences, General Psychology Keywords: psychological distress/anxiety/depression; dementia; Alzheimer’s disease; Parkinson’s disease; short form of the Depression Anxiety Stress Scale 21; Depression Anxiety Stress Scale 8-items; factor structure; psychometric properties; structural validity; validation; measurement invariance; old age/elders/elderly; informal; family caregivers; spouse; adult children
Online: 9 August 2022 (08:44:11 CEST)
Dementia patients express a set of problematic and deteriorating symptoms, along self-care dependency. Overtime, the mental health of family caregivers of persons with dementia may suffer, putting them at a high risk for psychopathology, which may be associated with endangered wellbeing of demented people. This cross-sectional study examined the psychometric properties of the Depression Anxiety Stress Scale 8-items (DASS-8), DASS-12, DASS-21 in a convenient sample of 571 caregivers from northern Italy and southern Switzerland (Mean age = 53, SD = 12, range = 24–89 years). A bifactor structure of the three measures had the best fit; some items of the DASS-12/DASS-21 failed to load on their domain-specific factors. The three-factor structure was invariant across various groups (e.g., gender, education, etc.), expressed adequate reliability and convergent validity, and had strong positive correlation with the 3-item UCLA Loneliness Scale (UCLALS3). Dementia type had no effect on distress scores, which were higher among females, adult children caregivers, those caring for dependent patients, and those who received help with care. For 54.9 and 38.8% of the latter, care was provided by relatives and health professionals, respectively. Since the DASS-8 expresses adequate psychometrics comparable with the DASS-21, it may be used as a brief measure of distress in this population.