Brain fog with compromised ability to concentrate has been the most frequent Long Covid (LC) complaint. This is due to an increased transforming growth factor (TGF) β/interferon (IFN)-γ ratio with consequently increased bradykinin (BKN), especially in Caucasian females. Brain and lung blood vessels “leak.” This same ratio is increased in Alzheimer’s disease (AD), but decreased in Parkinson’s disease (PD), because CD4⁺ and CD8⁺ T cells are differentially affected by the invading associated viruses, e.g., SARS CoV2, HIV, Varicella Zoster (VZV) aka Human Herpesvirus 3 (HHV3), HBV, HCV, …. In Covid-19 CD147 receptors on immune cells are critical in generating the increased TGF-β/IFN-γ and those on endothelial cells, platelets, and erythrocytes are critical to the abnormal microvascular blood flow. ACE2 receptors on pneumocytes and enterocytes enable pulmonary and GI entry, initiating gut dysbiosis. Epigenetics, methylation, magnesium, vitamin D, the B vitamins, and antioxidants suggest that these issues can be surmounted. Biochemical, physiologic, and epidemiologic data are analyzed to answer these questions. An LC model is presented and discussed in the context of the most recent research. Suggestions to avoid these and other worrisome concerns are included. Other topics discussed include estrogen, the gut microbiome, type 2 diabetes (T2D), and homocysteine.

Homocysteine (Hcy) is a sulfur-containing amino acid that is generated during methionine metabolism. Hyperhomocysteinemia (HHcy) is typically defined as levels >15 micro mols/L. Elevated plasma levels of Hcy can be caused by the deficiency of either vitamin B12 or folate. The active role of homocysteine is quite ambivalent: many studies detected its potential impact on neurological events; others try to identify it as one of the possible risk factors of cardiovascular events, but with a complementary and secondary role. HHcy has been reported in many neurologic disorders, including cognitive impairment and stroke, independent of long-recognized factors such as hyperlipidemia, hypertension, diabetes mellitus, and smoking. Nowadays, homocysteine could be considered as a possible link between a common vascular risk factor and potential alterations in degenerative neuronal disorders. HHcy-induced oxidative stress, endothelial dysfunction, inflammation, smooth muscle cell proliferation, and endoplasmic reticulum stress; all these aspects have been considered to play an essential role in the pathogenesis of several diseases, including atherosclerosis, major stroke, and vascular dementia. Specific models of astrocytes impairment in HHcy-mice, which mimic small vessel disease, have been developed with a three-step investigation (at 6, 10, 14 weeks of B6, B9, and B12 detrimental diet in wild type HHcy mouse). These studies found out that after ten weeks on a diet (at the most after 14 weeks), end-feet disruption occurs. This phenomenon is concomitant to reduced vascular labeling for aquaporin -4-water channels, lower protein/mRNA levels for Kir4.1, and BK potassium channels, associated with a higher expression of MMP-9. The most exciting finding is that microglial activation in this mice model was evident since the precocious time of observation (6-week time) and precedes astrocytic changes. Our research aims to review the possible role of HHcy in neurodegenerative disease and small-vessel disease and to understand its pathogenic impact.

These three syndromes - long covid (LC), postural orthostatic tachycardia syndrome (POTS), and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) - have many symptoms in common. The common denominator remains elusive. The blood brain barrier (BBB) has been a barrier not only to microbes and toxins but also to understanding pathogenetic links. There are several areas within the brain that have no BBB. These are known as circumventricular organs (CVOs) and their location relative to CNS nuclei that direct autonomic and neuroendocrine functions is provocative in the quest for pathogenesis. In addition the majority afflicted with LC and ME/CFS appear to be those with two MTHFR polymorphisms, present in over 50% of Americans. These polymorphisms elevate homocysteine. When homocysteine is combined with CVOs, the fog of POTS and its paradox are lifted. POTS may represent the intersection of LC and ME/CFS in those with the MTHFR gene (hypermethylation or 677TT). The gut microbiomes of LC and ME/CFS, deficient in butyrates, GABA, and diversity, are then linked with MTHFR genotype 677TT. Reactivation of neurotropic EBV and VZV, due to loss of surveillance by CD4+/CD8+ T cells, is seen as secondary. The oxidative stress generated by homocysteine, loss of glutathione, low fiber diet, and persistent chronic inflammation exhaust available mitochondria and, assisted by BKN and estrogen, exacerbate all the elements of these post viral fatigue syndromes.

Background: Vitamin B12 is a water-soluble vitamin with important cellular functions and is an essential vitamin. The aim of this study is to determine the B12 levels of children in the period from the 6th month when they start taking additional foods to the age of 7 and the risk factors affecting them. Methods: One hundred pediatric patients aged 6-72 months who were diagnosed with vitamin B12 deficiency and their parents who agreed to participate in Istanbul Atlas University, Medical Faculty, “Medicine Hospital” Pediatric Clinic between September 2022 and June 2023 were prospectively included in this study. Results: B12 deficiency was significantly higher in the 6-11 (25%) month group than those in the 12-23 (5.8%) and 24-47 (2.8%) month groups. Homocysteine levels were highest in those with insufficient B12 levels compared to the other groups. There was no statistically significant difference in weekly dairy and meat consumption levels between age groups. B12 levels were lower in the 6-11-month group than in the other groups. Homocysteine levels were highest in those with insufficient B12 levels [<200 pg/mL (148 pmol/L)]. Folic acid levels were lower in the 24-47 month and 48-72 month groups than in the 6-11 month and 12-23 month groups. Conclusions: The results obtained in this study showed that low vitamin B12 and increased homocysteine levels seem to be important risk factors in children, especially from the 6th month when they start taking additional foods. The diagnosis of B12 deficiency can be confirmed by elevated serum total homocysteine levels, which are evidence of functional cobalamin deficiency.

The main treatment for pyridoxine nonresponsive cystathionine-β-synthase deficiency is a strict diet. Most centers prescribe low-protein diets based on gram-protein exchanges, and all protein sources are weighed. The purpose of this study is to investigate the effects of a more liberal methionine (Met)-based diet with relaxed consumption of fruits and vegetables on metabolic outcomes and dietary adherence. Ten patients previously on a low-protein diet based on a gram-protein exchange list were enrolled. The natural protein exchange lists were switched to a "Met portion exchange list". Foods containing less than 0.005 g methionine per 100 g of the food were accepted as exchange-free foods. A questionnaire was conducted to assess the effects of the new dietary approach on dietary compliance. The switch to Met portioning had no adverse effects on the control of plasma homocysteine levels in terms of metabolic outcomes. It resulted in a significant reduction in patients' daily betaine dose. The questionnaire results indicated significantly increased dietary compliance, and all patients preferred to continue with this modality. In conclusion, methionine portion-based medical nutrition therapy with relaxed consumption of fruits and vegetables seems to be a good and safe option to achieve good metabolic outcomes and high treatment adherence.

The inability to efficiently metabolize homocysteine (Hcy), which occurs in nutritional and genetic deficiencies, leads to hyperhomocysteinemia (HHcy) thereby causing endothelial dysfunction, a hallmark of atherosclerosis which underpins cardiovascular disease (CVD). The dysregulation of mammalian target of rapamycin (mTOR) signaling, and impaired autophagy play important roles in CVD. Biochemically, HHcy is characterized by elevated levels of Hcy and its metabolites, Hcy-thiolactone (HTL) and N-Hcy-protein (N-Hcy). However, whether these metabolites can dysregulate mTOR signaling and autophagy in endothelial cells is not known. Here, we examined the influence of HTL, N-Hcy, and Hcy on the PHF8/H4K20me1/mTOR/autophagy pathway in human umbilical vein endothelial cells (HUVEC). We found that treatments with HTL, N-Hcy, or Hcy significantly reduced PHF8 protein and mRNA expression, increased H4K20me1, and upregulated mTOR signaling. Autophagy was also impaired (significantly downregulated BECN1, ATG5, ATG7, and LC3 protein and mRNA levels). We also found that these changes were mediated by PHF8-targeting microRNA (miR): miR-22-3p and miR-1229-3p. The effects of HTL, N-Hcy, or Hcy on the miR expression and on the PHF8/H4K20me1/mTOR/autophagy pathway were abrogated by treatments with an inhibitor of miR-22 or miR-1229. Taken together, these findings show that Hcy metabolites can upregulate miR-22-3p and miR-1229-3p expression, which then dysregulate the PHF8/H4K20me1/mTOR/autophagy pathway, important for vascular homeostasis.

Vitamin B9(folate)/B12 deficiency is known to induce brain structural and/or functional retardations. Besides neural tube defects in case of major consequences, several mild deregulations also lead to deleterious effect after birth, and folate supplementation recommended in some countries usually stop at the end of the first trimester. Various hormonal receptors were shown to be deregulated in brain tissue under this context. The glucocorticoid receptor (GR) is particularly sensitive to epigenetic regulation and post-traductional modifications. In a mother-offspring rat model of vitamin B9/B12 deficiency, we investigated whether a prolonged folate supplementation could restore the GR signalization in the hypothalamus. Our data showed that a deficiency in folate and vitamin B12 during the in-utero and the early postnatal periods was associated with reduced GR expression inn the hypothalamus. We also described for the first time a new post-traductional modification of GR that impaired ligand binding and GR activation, leading to decreased the expression of one of the GR targets in the hypothalamus, AgRP. Moreover, this brain-impaired GR pathway was associated with behavioral perturbations during offspring growth. Importantly, perinatal and postnatal supplementation with folic acid helped restore GR mRNA level and activity in hypothalamus cells and improved behavioral deficits.

Elevation of the intermediate amino acid metabolite Homocysteine (Hcy) causes Hyperhomocysteinemia (HHcy), a metabolic disorder frequently associated with mutations in the methionine-cysteine metabolic cycle as well as with nutritional deficiency and aging. Previous literature suggest that HHcy is a strong risk factor for cardiovascular diseases. Severe HHcy is well established to correlate with vascular pathologies primarily via endothelial cell death. Though moderate HHcy is more prevalent and associated with an increased risk of cardiovascular abnormalities in later part of life, its precise role in endothelial physiology is largely unknown. In this study, we report that moderate elevation of Hcy causes endothelial dysfunction through impairment of their migration and proliferation. We established that unlike severe elevation of Hcy, moderate HHcy is not associated with suppressed endothelial VEGF/VEGFR signaling and oxidative stress induction. We further showed that moderate HHcy induces a sub-lethal ER stress that causes defective endothelial migration through abnormal actin cytoskeletal remodeling. We also found that sub-lethal increase of Hcy causes endothelial proliferation defect by suppressing mitochondrial respiration and concomitantly increases glycolysis to compensate the consequential ATP loss and maintain overall energy homeostasis. Finally, analyzing an available microarray dataset, we confirmed that these hallmarks of moderate HHcy are conserved in adult endothelial cells as well. Thus, we identified adaptive UPR and metabolic rewiring as two key mechanistic signatures in moderate HHcy-associated endothelial dysfunction. As HHcy is clinically associated with enhanced vascular inflammation and hypercoagulability, identifying these mechanistic pathways may serve as future targets to regulate endothelial function and health.

Hsp70.1 has dual functions as chaperone protein and lysosomal stabilizer. Previously, we reported that calpain-mediated cleavage of carbonylated Hsp70.1 causes ischemic neuronal death by inducing lysosomal rupture. Recently, we found that the consecutive injections of vegetable oil-peroxidation product ‘hydroxynonenal’ induces hepatocyte death via the similar cascade. As Hsp70.1 is related also to fatty acid β-oxidation in the liver, its deficiency is known to cause accumulation of fat. Genetic deletion of betaine-homocysteine S-methyltransferase (BHMT) was reported to perturb choline metabolism, inducing decrease of phosphatidylcholine with the resultant hepatic steatosis. Here, focusing on disorders of Hsp70.1 and BHMT, we studied the mechanism of hepatocyte degeneration and steatosis, using monkeys after the consecutive injections of synthetic hydroxynonenal. As these monkeys showed a significant impairment of liver functions, the liver tissues without and with hydroxynonenal injections were compared by proteomics, immunoblotting, immunohisto-chemical and electron microscopic analyses. Western blotting showed upregulation of neither Hsp70.1 nor BHMT, but an increased cleavage of both proteins. Proteomics showed downregulation of Hsp70.1, while 2-fold increments of carbonylated BHMT. Hsp70.1 carbonylation was negligible, showing a marked contrast to ischemic neurons which were associated with ~10-fold increments. The control liver histologically showed lipid droplets in Ito cells, but lipid depositions within hepatocytes were very little. In contrast, after hydroxynonenal injections, widespread fatty degeneration and focal coagulation necrosis were observed with accumulation of numerous tiny lipid droplets within and around the degenerating/dying hepatocytes. Electron microscopy showed lysosomal membrane permeabilization/rupture, remarkable dissolution of mitochondria and rough ER membrane, and proliferation of abnormal peroxisomes. It is probable that disruptions of rough ER caused impaired synthesis of Hsp70.1 and BHMT proteins, while impairments of mitochondria and peroxisomes presumably contributed to the sustained generation of reactive oxygen species. Since both Hsp70.1 and BHMT are vulnerable to the long-standing oxidative stressor, hydroxynonenal-induced disorders facilitated degeneration and steatosis of hepatocytes, respectively.

There is an increasing interest in biomarkers of nitric oxide dysregulation and oxidative stress to guide management and identify new therapeutic targets in patients with chronic obstructive pulmonary disease (COPD). We conducted a systematic review and meta-analysis of the association between circulating metabolites within the arginine (arginine, citrulline, ornithine, asymmetric, ADMA, and symmetric, SDMA dimethylarginine), transsulfuration (methionine, homocysteine, and cysteine) and folic acid (folic acid, vitamin B6, and vitamin B12) metabolic pathways and COPD. We searched electronic databases from inception to 30 June 2023 and assessed the risk of bias and the certainty of evidence. In 21 eligible studies, compared to healthy controls, patients with stable COPD had significantly lower methionine (standardized mean difference, SMD=-0.50, 95% CI -0.95 to -0.05, p=0.029) and folic acid (SMD=-0.37, 95% CI -0.65 to -0.09, p=0.009), and higher homocysteine (SMD=0.78, 95% CI 0.48 to 1.07, p˂0.001) and cysteine concentrations (SMD=0.34, 95% CI 0.02 to 0.66, p=0.038). Additionally, COPD was associated with significantly higher ADMA (SMD=1.27, 95% CI 0.08 to 2.46, p=0.037), SDMA (SMD=3.94, 95% CI 0.79 to 7.08, p=0.014), and ornithine concentrations (SMD=0.67, 95% CI 0.13 to 1.22, p=0.015). In subgroup analysis, the SMD of homocysteine was significantly associated with the biological matrix assessed and the forced expiratory volume in the first second to forced vital capacity ratio, but not with age, study location, or analytical method used. Our study suggests the presence of significant alterations in metabolites within the arginine, transsulfuration, and folic acid pathways which can be useful for assessing nitric oxide dysregulation and oxidative stress and identifying novel treatment targets in COPD. (PROSPERO registration number: CRD42023448036)