REVIEW | doi:10.20944/preprints201810.0707.v1
Online: 30 October 2018 (06:45:05 CET)
The immune system plays a major role in the surveillance and control of malignant cells, with the presence of tumor infiltrating lymphocytes (TILs) correlating with better patient prognosis in multiple tumor types. The development of ‘checkpoint blockade’ and adoptive cellular therapy has revolutionized the landscape of cancer treatment and highlights the potential of utilizing the patient’s own immune system to eradicate cancer. One mechanism of tumor-mediated immunosuppression that has gained attention as a potential therapeutic target is the purinergic signaling axis, whereby the production of the purine nucleoside adenosine in the tumor microenvironment can potently suppress T and NK cell function. The production of extracellular adenosine is mediated by the cell surface ectoenzymes CD73, CD39 and CD38 and therapeutic agents have been developed to target these as well as the downstream adenosine receptors (A1R, A2AR, A2BR, A3R) to enhance anti-tumor immune responses. This review will discuss the role of adenosine and adenosine receptor signaling in tumor and immune cells with a focus on their cell-specific function and their potential as targets in cancer immunotherapy.
REVIEW | doi:10.20944/preprints202011.0143.v1
Subject: Medicine & Pharmacology, Allergology Keywords: serotonin; norepinephrine; dopamine; histamine; adenosine, trace amines
Online: 3 November 2020 (08:57:54 CET)
Atypical antipsychotic drugs were introduced in the early 1990th. Unlike typical antipsychotics, which are effective only against positive symptoms of schizophrenia, atypical antipsychotics show effectiveness against negative and cognitive symptoms as well. Furthermore, they are effective not only in psychotic, but also in affective disorders, by their own or as adjuncts to antidepressant drugs. While typical antipsychotics act, almost exclusively, via dopamine-2 (D2) receptors, atypical target serotonin-1A/1B/2A/2C (5-HT1A/1B/2A/2C), α1/2-adrenergic, and/or histamine-1 (H1) receptors as well. Blocking of 5-HT1A/1B autoreceptors, inducing their early desensitization, and/or activation of α1-adrenoceptors, allow some atypical drugs to enhance 5-HT transmission. Blocking of 5-HT2A/2C and/or α2-adrenoceptors enable some atypical antipsychotics to stimulate catecholamine transmission and/or diminish the inhibition of catecholamine neurons induced by some antidepressants. It is possible, that the activation of H1 and/or blocking of H3 boost monoamine transmission as well, via a mechanism involving stimulation of firing activity of dopamine neurons. The experimental drugs with antipsychotic potential, acting on adenosine and trace amino associated (TAAR) receptors, might be effective in mood disorders as well, because of the ability to modulate the excitability of monoamine-secreting neurons and to potentiate extracellular concentrations of monoamines in the limbic areas of the brain.
ARTICLE | doi:10.20944/preprints201804.0033.v1
Subject: Life Sciences, Endocrinology & Metabolomics Keywords: cordycepin; adenosine A1 receptor; prolactin; anti-obesity
Online: 3 April 2018 (07:53:24 CEST)
Cordycepin is an extract from the insect fungus Cordyceps. militaris, which is a traditional medicine with various biological function. In previous studies, cordycepin had been reported with excellent anti-obesity effect, but the mechanism is unclear. A large quantity of evidences showed that prolactin plays an important part in body weight regulation, hyperprolactinemia can promote appetite and accelerate fat deposition. In this study, we explored the molecular mechanism of the anti-obesity effect of cordycepin by reducing prolactin release via an adenosine A1 receptor. In vivo, obese rats model was induced by high fat diet for 5 weeks, the serum and liver lipids coupling with serum prolactin were reduced by treatment of cordycepin, the results suggested that cordycepin is a potential drug for therapying obesity which could be related with prolactin. In vitro, cordycepin could inhibit prolactin secretion in GH3 cells via upregulating the expression of adenosine A1 receptor, the inhibition effect could be blocked by an antagonist of adenosine receptor A1 DPDPX, prolactin induced the upregulation of lipogenesis genes PRLR, and P-JAK2 in 3T3-L1 cells. Intriguingly, cordycepin would down-regulate the expression of prolactin receptor (PRLR). Thus, we concluded that cordycepin modulate body weight by reducing prolactin release via an adenosine A1 receptor.
ARTICLE | doi:10.20944/preprints202203.0157.v1
Subject: Chemistry, Medicinal Chemistry Keywords: Adenosine receptors; methanocarba; bicyclo[3.1.0]hexane; A3 receptors
Online: 10 March 2022 (15:47:10 CET)
In this paper, a series of bicyclo[3.1.0]hexane-based nucleosides were synthesized and evaluated for their P1 receptor affinities in radioligand binding studies. The most potent derivative 30 displayed moderate A3AR affinity (Ki of 0.38 μM) and high A3R selectivity. A subset of compounds varied at 5’-position was further evaluated in functional P2Y1R assays displaying no off-target activity.
REVIEW | doi:10.20944/preprints202007.0426.v1
Subject: Medicine & Pharmacology, Anesthesiology Keywords: COVID-19; ARDS; Adenosine; CT-scan; Cytokines Storm
Online: 19 July 2020 (19:31:13 CEST)
Some COVID-19 patients develop interstitial pneumonia that can evolve into Acute Respiratory Distress Syndrome (ARDS). This is accompanied by an inflammatory cytokine storm. SarS-CoV has proteins capable of promoting cytokine storm, especially in patients with comorbidities, including obesity. Since there is currently no resolutive therapy for ARDS and given the scientific literature regarding the use of adenosine, its application has been hypothesized. Adenosine through its receptors is able to inhibit the acute inflammatory process, increase the protection capacity of the epithelial barrier and reduce the damage due to an overactivation of the immune system, such as in cytokine storms. These features are known in ischemia / reperfusion models and could also be exploited in acute lung injury, with hypoxia. In light of these hypotheses, for compassionate use, a COVID-19 patient, with unresponsive respiratory failure, was treated with adenosine. The results showed a rapid and clear improvement in clinical conditions, with the negative effect of detection of SarS-CoV2.
Subject: Medicine & Pharmacology, Pharmacology & Toxicology Keywords: adenosine receptor; nucleoside transport; CNS; inflammation; cardiovascular system; pain
Online: 9 April 2020 (16:19:14 CEST)
Many ligands directly target adenosine receptors (ARs). Here we review the effects of noncanonical AR drugs on adenosinergic signaling. Non-AR mechanisms include raising adenosine levels by inhibiting adenosine transport (e.g. ticagrelor, ethanol, cannabidiol), affecting intracellular metabolic pathways (e.g. methotrexate, nicotinamide riboside, salicylate, 5‐aminoimidazole‐4‐carboxamide riboside), or undetermined means (e.g. acupuncture). Yet other compounds bind ARs in addition to their canonical ‘on-target’ activity (e.g. mefloquine). The strength of experimental support for an adenosine-related role in a drug’s effects varies widely. AR knockout mice are the ‘gold standard’ method for investigating an AR role, but few drugs have been tested in these mice. Given the interest in AR modulation for treatment of cancer, CNS, immune, metabolic, cardiovascular, and musculoskeletal conditions, it is informative to consider AR and non-AR adenosinergic effects of approved drugs and conventional treatments.
HYPOTHESIS | doi:10.20944/preprints202006.0038.v1
Subject: Keywords: T-lymphocytes; programmed cell death protein-1; mitochondria; adenosine triphosphate
Online: 4 June 2020 (13:54:40 CEST)
It has been demonstrated that a decrease in cellular adenosine triphosphate (c-ATP) causes cellular dysfunction. T-cells are not an exception. One of their roles is to properly detect and eliminate cancer cells. These processes occur at the expense of ATP. Therefore, it can be concluded that a decrease in c-ATP can defect T-cell function and promote cancer evolution. In this article, we provide a hypothesis to describe the correlation between the expression of PD-1 protein on T-cells and their c-ATP levels. Moreover, we present the possible predictive factors of Anti–PD(L)-1 therapy which has not yet been determined definitely.
REVIEW | doi:10.20944/preprints201910.0149.v1
Subject: Medicine & Pharmacology, Pharmacology & Toxicology Keywords: adenosine receptor; immune system; cancer therapy; tumor microenvironment; cell proliferation; metastasis
Online: 13 October 2019 (16:28:09 CEST)
There are four subtypes of adenosine receptors (ARs), named A1, A2A, A2B and A3, all of which are G protein-coupled receptors. The A2BAR, coupled to both Gαi and Gαq G proteins, is one of the several G-protein-coupled receptors that are expressed in a significantly higher level in some cancer tissues in comparison to adjacent normal tissues. There is growing evidence that the A2BAR plays an important role in tumor cell proliferation, angiogenesis, metastasis, and immune suppression. Thus, A2BAR antagonists are potentially novel attractive anticancer agents. Several antagonists targeting at the A2BAR are currently in clinical trials for various types of cancers. In this review, we first describe the signaling, agonists, and antagonists of the A2BAR. We further discuss the role of the A2BAR in the progression of various types cancers, and the rationale of using A2BAR antagonists in cancer therapy
REVIEW | doi:10.20944/preprints201809.0397.v1
Subject: Medicine & Pharmacology, Gastroenterology Keywords: lactobacilli; bifidobacilli; arthritis; inflammatory bowel; microbiome; metabolomics; aryl hydrocarbon reductase; adenosine; histamine; short chain fatty acid
Online: 20 September 2018 (05:12:00 CEST)
Probiotics have been used to ameliorate gastrointestinal symptoms since ancient times. Over the past 40 years, probiotics have been shown to exert major effects on the immune system, both in vivo and in vitro. This interaction is clearly linked to gut microbes, their polysaccharide antigens, and key metabolites produced by these bacteria. At least four metabolic pathways have been implicated in mechanistic studies of probiotics, based on carefully studied animal models. Microbial-immune system crosstalk has been linked to short chain fatty acid production and signaling, tryptophan metabolism and the activation of aryl hydrocarbon receptors, nucleoside signaling in the gut, and activation of the intestinal histamine-2 receptor. Several randomized controlled trials have now shown that microbial modification by probiotics may improve gastrointestinal symptoms and multi-organ inflammation in rheumatoid arthritis, ulcerative colitis, and multiple sclerosis. Future work will need to carefully assess safety issues, selection of optimal strains and combinations, and attempts to prolong the duration of colonization of beneficial microbes.
ARTICLE | doi:10.20944/preprints202009.0185.v1
Subject: Life Sciences, Endocrinology & Metabolomics Keywords: eel luteinizing hormone receptor; constitutively activating mutation; inactivating mutation; cyclic adenosine monophosphate response; cell surface loss of receptor
Online: 8 September 2020 (10:56:48 CEST)
We analyzed signal transduction of three constitutively activating mutants (M410T, L469R, and D590Y) and two inactivating mutants (D417N and Y558F) of the eel luteinizing hormone receptor (eel LHR), known to occur in human LHR. The objective of this study was to assess the functional effects of these mutations in signal transduction and cell surface loss of receptor. Mutant receptors were transiently expressed in Chinese hamster ovary (CHO-K1) cells. Eel LH-stimulated accumulation of cyclic adenosine monophosphate (cAMP) was measured by homogeneous time-resolved fluorescence (HTRF) assays. The loss of receptors from the cells surface was measured using an enzyme-linked immunosorbent assay (ELISA) in human embryonic kidney (HEK) 293 cells. The cAMP response in cells expressing the wild type eel LHR was increased in a dose-dependent manner using eel LH ligand stimulation. Compared with the wild type, cells expressing the activating mutants (M410T, L469R, and D590Y), exhibited a 4.0-, 19.1-, and 7.8-fold increase in basal cAMP response without agonist stimulation, respectively. Their maximal responses to agonist stimulation were approximately 65%, 52%, and 98%, respectively, of those of the wild type. The inactivating mutants (D417N and Y558F) did not completely impair signal transduction, and their maximal responses were only 33% and25 % of those of wild type. These data clearly showed that the eel LHR-L469R and D590Y, activating mutants enhanced the rate of the loss of cell surface receptors following treatment with eel LH. Thus, the loss of cell surface receptors in cells expressing mutant eel LHRs was consistent with the eel LH agonist-induced production of cAMP. Our results suggested that the activation of the eel LHR requires appropriate loss of LHR-ligand complexes from the cell surface.
ARTICLE | doi:10.20944/preprints201611.0111.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: Y-shaped microfluidic device; wall shear stress; adenosine triphosphate (ATP) signal; combined effect; vascular endothelial cells; calcium dynamics
Online: 22 November 2016 (09:51:31 CET)
The intracellular calcium dynamics in vascular endothelial cells (VECs) in response to wall shear stress (WSS) and/or adenosine triphosphate (ATP) have been commonly regarded as an important factor in regulating VEC function and behavior including proliferation, migration and apoptosis. However, the effects of time-varying ATP signals have been usually neglected in the past investigations in the field of VEC mechanobiology. In order to investigate the combined effects of WSS and dynamic ATP signals on the intracellular calcium dynamic in VECs, a Y-shaped microfluidic device, which can provide the cultured cells on the bottom of its mixing micro-channel with stimuli of WSS signal alone and different combinations of WSS and ATP signals in one single micro-channel, is proposed. Both numerical simulation and experimental studies verify the feasibility of its application. Cellular experimental results also suggest that a combination of WSS and ATP signals rather than a WSS signal alone might play a more significant role in VEC Ca2+ signal transduction induced by blood flow.
ARTICLE | doi:10.20944/preprints202003.0215.v1
Subject: Life Sciences, Other Keywords: major depression; skin fibroblasts; mitochondria; bioenergetics; oxidative phosphorylation; adenosine triphosphate; calcium imaging; mitochondrial membrane potential; mitochondrial DNA copy number
Online: 12 March 2020 (14:11:25 CET)
Mitochondrial malfunction is supposed to be involved in the etiology and pathology of major depressive disorder (MDD). Here, we aimed to identify and characterize the molecular pathomechanisms related to mitochondrial disfunction in adult human skin fibroblasts which were derived from MDD patients or non-depressive control subjects. We found that MDD fibroblasts showed significantly impaired mitochondrial functioning: basal and maximal respiration, spare respiratory capacity, non-mitochondrial respiration and ATP-related oxygen consumption was lower. Moreover, MDD fibroblasts harbor lower ATP levels and showed hyperpolarized mitochondrial membrane potential. To investigate cellular resilience, we challenged both groups of fibroblasts with hormonal (dexamethasone) or metabolic (galactose) stress for one week, and found that both stressors increased oxygen consumption but lowered ATP content in MDD as well as in non-depressive control fibroblasts. Interestingly, the bioenergetic differences between fibroblasts from MDD or non-depressed subjects, which were observed under non-treated conditions, could not be detected after stress. Our findings support the hypothesis that altered mitochondrial function causes a bioenergetic imbalance which is associated with the molecular pathophysiology of MDD. The observed alterations in OXPHOS and other mitochondria-related properties represent a basis for further investigations of pathophysiological mechanisms and might open new ways to gain insight into antidepressant signaling pathways.