Search Results (197)

Background/Objectives: Vitamin B₁₂ deficiency is increasingly recognized as a contributor in both vascular and neurodegenerative aging-related disorders. Its deficiency disrupts one-carbon metabolism, leading to impaired homocysteine (Hcy) cycling. Elevated Hcy is a well-established risk factor for vascular dysfunction. Previously, we established that elevated Hcy contributes to aging retinal diseases and plays a central role in blood retinal barrier (BRB) dysfunction. Building on this foundation, the present study examines how B-vitamin deficiency disrupts one-carbon metabolism and whether restoring these vitamins can serve as a preventive or therapeutic strategy. Since B-vitamins (B₆, B₉, and B₁₂) are crucial cofactors in the metabolism of Hcy, we investigated how dietary changes in these vitamins affect serum Hcy levels and retinal vascular integrity in mice. Methods: C57BL/6- Wild-type (WT) and cbs^+/− mice (Cystathionine Beta-Synthase heterozygotes, common mouse model for elevated Hcy) were fed specially formulated diets, which contained different levels of B-vitamins (normal, deficient (B-Vit (−)) or enriched (B-Vit (+)). Initially, two groups of mice were placed on either a normal or a deficient diet. After 12–16 weeks, the success of the diet regimes was confirmed by observing serum B₁₂ deficiency in the B-Vit (−) group, along with elevated Hcy levels. Subsequently, a subgroup of the B-Vit (−) mice was switched to an enriched diet. The BRB integrity was evaluated in living mice using fluorescein angiography (FA), optical coherence tomography (OCT), and in the perfused mice retinas with Western blot analysis of leaked retinal albumin and tight junction proteins (occludin and ZO-1) levels. Results: The B-vitamin deficiency caused significant drop in serum vitamin B₁₂ and an increase in plasma Hcy, leading to vascular leakage, altered retinal thickness, choroidal neovascular changes, increased retinal albumin leak, and decreased tight junction protein expression, indicating BRB disruption, which was restored with B-vitamin supplementation. Conclusions: a long-term deficiency of vitamins B₆, B₉, and B₁₂ can lead to disruptions in the BRB. However, supplementation with these B-vitamins has the potential to reverse these effects and help maintain the integrity of BRB. This under-score the significance of one-carbon metabolism for retinal health and suggests that ensuring adequate levels of B-vitamins may aid in preventing aging retinal diseases with BRB disruption such as diabetic retinopathy and age-related macular degeneration. Full article

Treatment-resistant depression (TRD) is a subtype of major depressive disorder (MDD) that fails to respond to first-line pharmacotherapy. This cross-sectional study compared blood concentrations of folic acid, vitamin B12, and homocysteine between female depressed patients with or without TRD, and examined the association of these parameters with the severity of depression. It included 116 female patients treated for MDD, of whom 59 (51%) developed TRD. The diagnosis of MDD was established via a structured clinical interview, while the severity of depression was measured with the Montgomery–Asberg Depression Rating Scale. Blood samples were taken at the initial psychiatric examination to determine the serum levels of folic acid and vitamin B12 and plasma levels of homocysteine. Folic acid levels were significantly lower in the female TRD group (p < 0.001), whereas homocysteine levels were significantly higher in the female TRD group (p < 0.001), compared to the female depressed group without TRD. In the regression analyses, higher levels of homocysteine (p < 0.001) were associated with TRD, while lower levels of folic acid (p = 0.036) were related to higher severity of depression, independently of sociodemographic and clinical parameters. Our findings showed that folate correlated with symptom severity, while homocysteine correlated with the TRD status in female MDD patients. Full article

Background/Objectives: The causal role of homocysteine (tHcy) in atrial fibrillation (AF) is unclear. To (re)explore the causal effect of tHcy in non-valvular AF (NVAF). Methods: In a case–control study in overweight/obese adults, cases were patients with NVAF and controls were their peers without AF. They were assessed for clinical, laboratory, and echocardiographic particulars and were genotyped for MTHFR 677C>T (rs1801133), PITX2 C>T (rs2200733), and KCNE1 112A>G (rs1805127) polymorphisms. We employed a conventional case–control, mediation analysis, and one-sample Mendelian randomization (MR) analyses to evaluate forward and reverse tHcy-NVAF associations. Results: We enrolled 180 cases and 179 controls. With an extensive confounder control (i) the MTHFR 677C>T variant allele associated with higher tHcy; (ii) PITX2 C>T variant allele associated with NVAF while KCNE1 112A>G did not; (iii) MTHFR variant associated with NVAF indirectly, through tHcy assuming wild type but not variant genotype (exposure–mediator interaction); (iv) considering all subjects, tHcy associated with NVAF through the effect on renal function and NT-proBNP levels (no exposure–mediator interaction); (v) considering MTHFR wild-type subjects (n = 160), tHcy “directly” strongly associated with NVAF, and considering variant carriers (n = 199), it indirectly associated with NVAF and directly tended to associate with a lower probability of NVAF; (vi) in MR analysis (MTHFR SNP instrument), tHcy associated with NVAF; and vii) mediation and MR analyses [PITX2 SNP (exposure/instrument)—NVAF, (mediator/exposure)—tHcy outcome] excluded the reverse tHcy-NVAF association. Conclusions: Data strongly support the causal role of tHcy in NVAF in overweight/obese patients and suggest that the effect might be modified by the MTHFR 677C>T variant allele. Full article

Aim: Nephrotic syndrome (NS) represents a complex glomerular disorder with significant clinical heterogeneity across pediatric and adult populations. Although glucocorticosteroids have constituted the mainstay of therapeutic intervention for more than six decades, primary treatment resistance manifests in approximately 20% of pediatric patients and 50% of adult cohorts. Steroid-resistant nephrotic syndrome (SRNS) is associated with substantially greater morbidity compared to steroid-sensitive nephrotic syndrome (SSNS), characterized by both iatrogenic glucocorticoid toxicity and progressive nephron loss with attendant decline in renal function. Based on this, the current study aims to develop a robust machine learning (ML) model integrated with explainable artificial intelligence (XAI) to distinguish SRNS and identify important biomarker candidate metabolites. Methods: In the study, biomarker candidate compounds obtained from proton nuclear magnetic resonance (1 H NMR) metabolomics analyses on plasma samples taken from 41 patients with NS (27 SSNS and 14 SRNS) were used. We developed ML models to predict steroid resistance in pediatric NS using metabolomic data. After preprocessing with MICE-LightGBM imputation for missing values (<30%) and standardization, the dataset was randomly split into training (80%) and testing (20%) sets, repeated 100 times for robust evaluation. Four supervised algorithms (XGBoost, LightGBM, AdaBoost, and Random Forest) were trained and evaluated using AUC, sensitivity, specificity, F1-score, accuracy, and Brier score. XAI methods including SHAP (for global feature importance and model interpretability) and LIME (for individual patient-level explanations) were applied to identify key metabolomic biomarkers and ensure clinical transparency of predictions. Results: Among four ML algorithms evaluated, Random Forest demonstrated superior performance with the highest accuracy (0.87 ± 0.12), sensitivity (0.90 ± 0.18), AUC (0.92 ± 0.09), and lowest Brier score (0.20 ± 0.03), followed by LightGBM, AdaBoost, and XGBoost. The superiority of the Random Forest model was confirmed by paired t-tests, which revealed significantly higher AUC and lower Brier scores compared to all other algorithms (p < 0.05). SHAP analysis identified key metabolomic biomarkers consistently across all models, including glucose, creatine, 1-methylhistidine, homocysteine, and acetone. Low glucose and creatine levels were positively associated with steroid resistance risk, while higher propylene glycol and carnitine concentrations increased SRNS probability. LIME analysis provided patient-specific interpretability, confirming these metabolomic patterns at individual level. The XAI approach successfully identified clinically relevant metabolomic signatures for predicting steroid resistance with high accuracy and interpretability. Conclusions: The present study successfully identified candidate metabolomic biomarkers capable of predicting SRNS prior to treatment initiation and elucidating critical molecular mechanisms underlying steroid resistance regulation. Full article

Both primary and secondary hemostasis consist of finely regulated pathways, forming a blood clot to stop bleeding. These orchestrated mechanisms involve multiple plasma- and platelet/endothelial-derived receptors, factors, enzymes, and proteins, such as the von Willebrand factor (vWF), fibrinogen, and thrombin. Over-activation or improper resolution of the coagulation cascade leads to severe pathological disorders, arterial and venous. Despite the fact that the genetic etiology of thrombophilia has gained the main research interest, there is growing evidence that the disturbed redox network of key hemostatic pathways signals thrombus formation. Oxidized LDL in dyslipidemias and many endogenous and exogenous compounds act as pro-oxidant stimuli that lead to post-translational modifications of proteins, such as sulfenylation, nitrosation, disulfide formation, glutathionylation, etc. Oxidation of cysteine and methionine residues of vWF, fibrinogen, and thrombomodulin has been detected at thrombotic episodes. Increased homocysteine levels due to, but not restricted to, methylenetetrahydrofolate reductase gene (MTHFR) mutations have been incriminated as a causative factor for oxidative stress, leading to a pro-thrombotic phenotype. Alterations in the vascular architecture, impaired vascular relaxation through decreased bioavailability of NO, accumulation of Nε-homocysteinylated proteins, ER stress, and endothelial cells’ apoptosis are among the pro-oxidant mechanisms of homocysteine. This review article focuses on describing key concepts on the oxidant-based molecular pathways that contribute to thrombotic episodes, with emphasis on the endogenous compound, homocysteine, aiming to promote further molecular, clinical, and pharmacological research in this field. Full article

Background/Objectives: The amino acid cysteine (Cys) plays an important role in the neuronal injury process in stroke. Cys is present in blood plasma in various forms. The relationship between Cys and its forms and the severity of acute stroke has not been sufficiently studied. We investigated the levels of total Cys and two of its forms (reduced Cys and its disulfide (cystine, CysS)) in blood plasma and their influence on stroke severity in patients at admission. Methods: A total of 210 patients (39–59 years old) with ischemic stroke and intracerebral or subarachnoid hemorrhage were examined. The contents of the different forms of Cys were determined in the first 10–72 h. Stroke severity was estimated using the National Institutes of Health Stroke Scale (NIHSS) and the modified Rankin Scale (mRs). Results: CysS levels < 54 μM were associated with severe (NIHSS > 13) neurological deficit (ischemic stroke: RR = 5.58 and p = 0.0021; hemorrhagic stroke: RR = 3.56 and p = 0.0003). Smoking and high levels of total Cys and other thiols (glutathione and homocysteine) appear to be factors determining this relationship. Conclusions: Low CysS levels may serve as a potential biomarker of acute stroke severity. Full article

Elevated plasma homocysteine (tHcy) is a modifiable risk factor for stroke and cardiovascular disease, influenced by genetic and lifestyle factors. Resistance-based training may reduce tHcy, but the impact of methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism remains unclear. This study examined the effects of a 26-week combined aerobic and resistance training program on stroke-related risk factors and tHcy levels in patients with chronic ischemic stroke, stratified by MTHFR genotype. Forty-six patients (mean age: 57.7 ± 8.9 years) completed supervised training three times per week. Assessments before and after the intervention included anthropometry, cardiorespiratory fitness, biochemical markers, and tHcy. Dietary intake was monitored and remained stable. Significant improvements were observed in body weight, fat mass, waist-to-hip ratio, VO₂max, and 6 min walk distance. tHcy decreased significantly overall (p < 0.01), with reductions confined to the CC genotype group (p < 0.01). BMI declined in CC and CT groups (p < 0.01 and p < 0.05), while fat-free mass, triglycerides, fasting glucose, and blood pressure showed no changes, likely due to pharmacological control. These findings suggest that combined training improves body composition and functional capacity, while genotype-specific reductions in tHcy highlight the potential of personalized rehabilitation strategies integrating genetic and nutritional considerations in stroke care. Full article

Background/Objectives: The associations between plasma homocysteine and pre-stroke antithrombotic medication and the effects these have on clinical outcomes of patients undergoing ischemic stroke remains unclear. This study aimed to evaluate the combined effect of plasma homocysteine levels and the use of pre-stroke antithrombotic medication on the clinical outcomes of patients experiencing first-ever and recurrent ischemic strokes. Methods: Anonymized data from consecutive patients who experienced ischemic stroke and had their plasma homocysteine levels evaluated were retrospectively analyzed. Pre-stroke antithrombotic medication status, clinical variables potentially influencing homocysteine concentrations, and stroke recurrence data were collected. Clinical outcomes were assessed using the modified Rankin Scale 3 months after stroke onset. The association between hyperhomocysteinemia and clinical outcomes was evaluated using logistic regression models. Results: Hyperhomocysteinemia was significantly associated with unfavorable clinical outcomes (adjusted odds ratio [aOR], 1.32; 95% confidence interval, 1.04–1.69) in the 2767 patients who were analyzed. The absence of pre-stroke antithrombotic medication use was associated with unfavorable outcomes (aOR range, 1.29–1.56), specifically in patients with first-ever stroke (aOR range, 1.45–1.64) but not in patients with recurrent strokes (aOR range, 0.70–1.04). Conclusions: Hyperhomocysteinemia and non-use of pre-stroke antithrombotic medication were significantly related to unfavorable outcomes in patients experiencing their first-ever stroke. These findings might provide prognostic insights into stroke management and patient stratification. Full article

Background/Objectives: Low folate intake before and during pregnancy increases the risk of neural tube defects and other adverse outcomes. Gene variants such as MTHFR 677C>T (rs1801133) may increase risks associated with suboptimal folate intake. Our objective was to use BALB/cJ Mthfr^677C>T mice to evaluate the effects of the TT genotype and low folate diets on embryonic development and MTHFR protein expression in pregnant mice. Methods: Female 677CC (mCC) and 677TT (mTT) mice were fed control (2 mg folic acid/kg (2D)), 1 mg folic acid/kg (1D) and 0.3 mg folic acid/kg (0.3D) diets before and during pregnancy. Embryos and maternal tissues were collected at embryonic day 10.5. Embryos were examined for developmental delays and defects. Methyltetrahydrofolate (methylTHF) and total homocysteine (tHcy) were measured in maternal plasma, and MTHFR protein expression was evaluated in maternal liver. Results: MethylTHF decreased due to the experimental diets and mTT genotype. tHcy increased due to 0.3D and mTT genotype; mTT 0.3D mice had significantly higher tHcy than the other groups. MTHFR expression was lower in mTT liver than mCC. MTHFR protein expression increased due to low folate diets in mCC mice, whereas in mTT mice, MTHFR expression increased only due to 1D. Developmental delays were increased in the litters of mTT mice fed 1D and 0.3D. Conclusions: The Mthfr^677C>T mouse models the effects of the MTHFR 677TT genotype in humans and provides a folate-responsive model for examination of the effects of folate intake and the MTHFR 677C>T variant during gestation. Full article

Methyl groups can be obtained either from the diet (labile methyl groups) or produced endogenously (methylneogenesis) via one-carbon (C1-) metabolism as S-adenosylmethionine (SAM). The essential nutrients folate and choline (through betaine) are metabolically entwined to feed their methyl groups into C1-metabolism. A choline-deficient diet in rats produces a 31–40% reduction in liver folate content, 50% lower hepatic SAM levels, and a doubling of plasma homocysteine. Similarly, folate deficiency results in decreased total hepatic choline. Thus, sufficient intakes of both folate and choline (or betaine) contribute to safeguarding the methyl balance in the body. A significant amount of choline (as phosphatidylcholine) is produced in the liver via the SAM-dependent phosphatidylethanolamine methyltransferase. Experimental studies using diets deficient in several methyl donors have shown that supplemental betaine was able to rescue not only plasma betaine but also plasma folate. Fasting plasma homocysteine concentrations are mainly determined by folate intake or status, while the effect of choline or betaine on fasting plasma homocysteine is minor. This appears to contradict the finding that approximately 50% of cellular SAM is provided via the betaine-homocysteine methyltransferase (BHMT) pathway, which uses dietary choline (after oxidation to betaine) or betaine to convert homocysteine to methionine and then to SAM. However, it has been shown that the relative contribution of choline and betaine to cellular methylation is better reflected by measuring plasma homocysteine after a methionine load test. Choline or betaine supplementation significantly lowers post-methionine load homocysteine, whereas folate supplementation has a minor effect on post-methionine load homocysteine concentrations. This review highlights the interactions between folate and choline and the essentiality of choline as a key player in C1-metabolism. We further address some areas of interest for future work. Full article

Pre-eclampsia (PE) is a hypertensive pregnancy complication. Oxidative stress is hypothesized to contribute to the pathophysiology of PE. Both the hydrogen sulfide (H₂S) and oxytocin (OT) systems might play a role in the pathophysiology of PE, like their antioxidant and hypotensive effects. Thus, the role of the interaction of the OT and H₂S systems in the context of PE was further elucidated in the present clinical case–control study “NU-HOPE” (Nürnberg-Ulm: The role of H₂S and Oxytocin Receptor in Pre-Eclampsia; ethical approval by the Landesärztekammer Bayern, file number 19033, 29 August 2019), comparing uncomplicated pregnancies, early onset PE (ePE, onset < 34 weeks gestational age) and late onset PE (lPE, onset > 34 weeks gestational age). Routine clinical data, serum H₂S and homocysteine levels, and tissue protein expression, as well as nitrotyrosine formation, were determined. The main findings were (i) unchanged plasma sulfide levels, (ii) significantly elevated homocysteine levels in ePE, but not lPE, (iii) significantly elevated expression of H₂S enzymes and OT receptor in the placenta in lPE, and (iv) significantly elevated nitrotyrosine formation in the lPE myometrium. Taken together, these findings suggest a role for the interaction of the endogenous H₂S- and OT/OTR systems in the pathophysiology of pre-eclampsia, possibly linked to impaired antioxidant protection. Full article

Homocysteine (Hcy) is becoming a well-established risk factor for cardiovascular disease (CVD), mainly involving endothelial dysfunction and atherogenesis. Endothelial dysfunction is reflected primarily in the complex regulation of the main physiological and pathophysiological processes. There is increasing evidence regarding abnormally high concentrations of plasma total homocysteine, or plasma hyperhomocysteinemia, contributing to endothelial dysfunction, inflammation, and CVD. This clinical and experimental study examined the connection between Hcy and cardiovascular disease risk. Homocysteine is a marker of total vascular damage that must be monitored and controlled as early as possible. Dietary and lifestyle changes are recommended for most patients with hyperhomocysteinemia (Hhcy). The purpose of this paper is to review the data from the specialized literature that demonstrate that there is a direct link between endothelial injury and increased homocysteine levels, identifying existing evidence, describing new mechanisms, and exploring potential new therapeutic options. These aspects continue to be debated, and additional efforts are required to refine therapeutic strategies and to investigate the potential implications of Hcy in health and disease. Full article

Purpose: Homocysteine (HCY) metabolism is regulated by the methionine cycle, which is essential for DNA methylation and is associated with the folate cycle. This study examines the alterations in DNA methylation signature including epigenetic age changes, measure cell-free DNA (cfDNA), and HCY concentrations, and identifies genetic markers that may influence homocysteine response following folic acid (FA) supplementation in individuals with hyperhomocysteinemia (HHC). Methods: Blood samples were obtained from 43 HHC patients undergoing FA supplementation. We quantified FA and HCY levels, separated plasma and white blood cell fractions, and evaluated global DNA methylation using LINE-1 bisulfite pyrosequencing. Biological age was determined using Illumina BeadArray technology, and whole-exome sequencing was performed to investigate the patients’ genetic backgrounds. Results: Following FA supplementation, cfDNA levels significantly decreased and correlated positively with HCY (r = 0.2375). Elevated average LINE-1 methylation of cfDNA and PBMC-origin DNA was observed, with mean relative changes of 1.9% for both sample types. Regarding HCY levels, we categorized patients based on their response to FA supplementation. FA responders showed decreased HCY from 15.7 ± 5.5 to 11 ± 2.9 µmol/L, while in FA non-responders, an opposite trend was detected. The average biological age was reduced by 2.6 years, with a notable reduction observed in 80% of non-responders and 48% of responders. Sequencing identified mutations in several genes related to the one-carbon cycle, including MTRR, CHAT, and MTHFD1, with strong correlations to the non-responder phenotypes found in genes like PRMT3, TYMS, DNMT3A, and HIF3A. Conclusions: FA supplementation influences the HCY level, as well as affects the cfDNA amount and the DNA methylation pattern. However, genetic factors may play a crucial role in mediating individual responses to folate intake, emphasizing the need for personalized approaches in managing hyperhomocysteinemia. Full article

Background/Objectives: Low vitamin D status seems to be associated with increased cardiometabolic risk, and was found to attenuate cardiometabolic benefits of statins in men. The aim of the current study was to investigate whether a different vitamin D status determines the pleiotropic effects of statins in women. Methods: This pilot, single-center, prospective, matched-cohort study included 78 women with hypercholesterolemia requiring statin therapy, assigned into one of three age-, plasma lipid-, and body mass index-matched groups: women with vitamin D deficiency (group I), women with vitamin D insufficiency (group II), and women with normal vitamin D homeostasis (group III). Throughout the study (16 weeks), all patients were treated with atorvastatin. The outcome of interest included plasma lipids, glucose homeostasis markers (fasting glucose, HOMA-IR and glycated hemoglobin), plasma levels of 25-hydroxyvitamin D, creatine kinase, uric acid, high-sensitivity C-reactive protein, homocysteine, fibrinogen, urinary albumin-to-creatinine ratio (UACR), and computed values of a 10-year risk of atherosclerotic events. Results: Compared to the control group (group III), group I was characterized by higher values of HOMA-IR, glycated hemoglobin, uric acid, hsCRP, homocysteine, fibrinogen, a UACR, and a 10-year risk of atherosclerotic events, whereas group II had higher values of hsCRP, homocysteine and a UACR. Atorvastatin reduced plasma levels of total and LDL cholesterol and a 10-year risk of atherosclerotic events in all study groups, but this effect was weakest in group I and strongest in group III. In group III, the drug decreased uric acid, hsCRP, homocysteine, fibrinogen, and the UACR. In the remaining groups, its effect was limited to a small decrease in only hsCRP (group I) or in hsCRP and homocysteine (group II). In group I, atorvastatin treatment was associated with an increase in HOMA-IR, glycated hemoglobin, and creatine kinase. Conclusions: Low vitamin D status may exert an unfavorable effect on the lipid-dependent and lipid-independent effects of atorvastatin in middle-aged or elderly women. Full article

Background/Objectives: Arterial stiffness is a prevalent age-related condition that can significantly increase the risk of cardiovascular disease and mortality in older adults. Understanding the factors that contribute to vascular health, including metabolic dysfunction and hyperhomocysteinemia, alongside vitamin B status, is essential for developing effective interventions. This study aimed to explore the relationship between plasma levels of homocysteine, folate, and vitamin B12, as well as various indices of metabolic dysfunction, in elderly individuals with arterial stiffness. Methods: We conducted a cross-sectional analysis involving 884 participants aged 65 and older, assessing arterial stiffness using the cardio/ankle vascular index method. Additionally, we collected fasting blood samples to evaluate plasma homocysteine, folate, vitamin B12 levels, and other relevant biochemical markers. Results: Higher plasma homocysteine levels are significantly correlated with elevated CAVI scores and increased indices of metabolic dysfunction (p < 0.05). Furthermore, a multivariate logistic regression analysis demonstrated that elevated plasma homocysteine levels, along with higher levels of lipid accumulation product (LAP), triglyceride/glucose index (TyG), and visceral adiposity index (VAI), are associated with increased arterial stiffness. Conclusions: These findings suggest that monitoring and optimizing homocysteine, folate, and vitamin B12 levels may be beneficial for preventing or managing arterial stiffness and related metabolic disorders in the elderly population. Full article