Hyperhomocysteinaemia and vascular injury: advances in mechanisms and drug targets

Dysregulated homocysteine metabolism and cardiovascular disease and clinical treatments

Elevated homocysteine (Hcy) levels, known as hyperhomocysteinemia (HHcy), are recognized as a separate risk factor for cardiovascular disease. Mutations in methylenetetrahydrofolate reductase (MTHFR) and cystathionine beta synthase (CBS)-enzymes pivotal at the juncture of the trans-sulfuration and remethylation pathways-underlie the pathogenesis of HHcy. Although vitamin supplementation has been proven to effectively decrease Hcy levels, there is still uncertainty about whether this reduction translates to a decrease in the incidence rates from cardiovascular diseases (CVDs). This review seeks to explore the linking between Hcy and specific diseases, the role of Hcy in vascular homeostasis, and the research on the possible advantages of therapies designed to lower Hcy levels. Understanding the intricate mechanisms of their metabolism and interactions is essential for pharmacological treatments to mitigate the adverse effects associated with metabolic dysregulation of Hcy. Given the widespread availability and ease of use of Hcy test kits, we strongly advocate for the routine administration of rapid blood tests for individuals at high risk of CVDs, particularly among the elderly population.

Homocysteine induced N6-methyldeoxyadenosine modification perturbation elicits mitochondria dysfunction contributes to the impairment of learning and memory ability caused by early life stress in rats

Mitochondrial dysfunction is the key pathological mechanism of cognitive decline, and homocysteine (Hcy) plays a vital role in modulating mitochondrial homeostasis. However, the regulating mechanism and intervention targets of Hcy-induced mitochondrial damage involved in brain impairment remain unclear. Herein, it is found that elevated Hcy levels lead to the increasement of METTL4 expression and augmentation of N6-methyldeoxyadenosine (6 mA) modification in mitochondrial DNA (mtDNA) induced by maternal separation (MS) stress. Meanwhile, mtDNA copy number and gene expression level were suppressed in the hippocampus and the binding of the mitochondrial transcription factor A (TFAM) to the mtDNA promoters can be obstructed, leading to mitochondrial dysfunction and learning and memory impairment. Thus, there was a pivotal role of mtDNA 6 mA regulated by METTL4 in Hcy mediated mitochondrial dysfunction and cognitive damage in rat exposed to early life stress, and targeted regulation of Hcy to rectify mtDNA 6 mA excess may be a strategy for developing mitochondria-focused cognitive disorders interventions.

Role and Relationship Between Homocysteine and H2S in Ischemic Stroke

Homocysteine (Hcy), a sulfur-containing amino acid, is an important intermediate product of methionine metabolism. Hcy can be either metabolized to cysteine, a precursor for glutathione synthesis and hydrogen sulfide (H2S) production, or regenerated back to methionine. Besides, the Hcy metabolism is central to supply methyl groups, which are essential for DNA methylation. In the transsulfuration pathway of Hcy metabolism, Hcy is metabolized to form cysteine and H2S by catalytic enzymes, containing cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE). Hcy metabolism-related enzymes and coenzymes, such as vitamin B6, vitamin B12, and folic acid, are closely related to hyperhomocysteinemia (HHcy), which is frequently accompanied by reduced H2S content. An accumulating study has revealed that HHcy is a risk factor for ischemic stroke, while H2S, served as a gaseous mediator at the physiological level, has protective effects against ischemic stroke. This review outlined the literature data from recent research related to Hcy metabolism and H2S production and described the roles and relationship among Hcy metabolism and H2S in ischemic stroke.

Association of vitamin B12 deficiency and hyperhomocystinemia with acute coronary syndromes - A case series

Acute coronary syndromes (ACS) are the most common presentation of atherosclerotic cardiovascular diseases in the emergency department. Numerous risk factors such as smoking, low High Density Lipoprotein (HDL) levels, metabolic syndrome, high triglycerides, diabetes, etc. have been implicated in the development of coronary artery disease and ACS. The management tools instead of focusing on the reversal of the above risk factors relies on lipid lowering drugs. Our series of patients suffering from ACS shows a possible association with low serum vitamin B12, high homocysteine, high Triglyceride, low HDL, low cholesterol and low LDL levels. There needs to be a paradigm shift in managing patients of ACS and the advice prescribed to them at the time of discharge. It would be prudent for emergency physicians to test for vitamin B12 and homocysteine levels in ACS patients.

Prevalence of MTHFR C677T polymorphism and its association with serum homocysteine and blood pressure among different ethnic groups: insights from a cohort study of Nepal

BACKGROUND

The risk of hypertension varies based on ethnicity, environmental factors, and genetic predispositions. Studies have reported a higher risk of cardiovascular diseases (CVD) and hypertension among the Newar ethnic groups in Nepal. However, the genetic analysis for Methylenetetrahydrofolate reductase (MTHFR C677T) gene mutations, serum homocysteine, and high-sensitivity C-reactive protein (hs-CRP) levels across different ethnicities remains unexplored.

METHODS

Sociodemographic information and baseline data of 489 participants were obtained from the first phase of the Dhulikhel Heart Study. Preserved blood samples were analyzed for MTHFR C677T polymorphism using real-time polymerase chain reaction (TaqMan assay), and serum homocysteine was measured through immunoassay techniques. Descriptive analysis, the Hardy-Weinberg equilibrium test, and multinomial regression were performed.

RESULTS

The prevalence of homozygous mutation (TT) was 19.8% in the Newar group and 12.5% in the Brahmin/Chhetri ethnicity. The highest mean value of homocysteine (19.4 µmol/L) was observed in homozygous participants, followed by the heterozygous mutant group (17.4 µmol/L). A statistically significant association (P = < 0.001) was found between homocysteine levels and blood pressure.

CONCLUSIONS

The Dhulikhel Heart Study reveals a significant prevalence of the MTHFR C677T gene mutation among the Newar ethnicity compared to other groups. Elevated levels of homocysteine and high-sensitivity C-reactive protein (hs-CRP) were associated with increased blood pressure.

CLINICAL TRIAL NUMBER

Not applicable.

Evaluation of homocysteine, folate, vitamin B12, and vitamin D levels in pregnant women with recurrent vaginitis

OBJECTIVE

The aim of this study was to evaluate the levels of homocysteine, vitamin B12, folic acid, and vitamin D in pregnant women with recurrent vaginitis and determine whether these parameters contribute to the etiology of the disease.

METHODS

The study included 30 pregnant women diagnosed with recurrent vaginitis in their first trimester (group I), who presented at least twice between 1.5.2019 and 1.5.2022 at the obstetrics and gynecology clinic, and 30 healthy pregnant women in their first trimester without any complaints (group II). The vagititis group was compared with the control group for serum levels of vitamin B12, homocysteine, folic acid, and vitamin D.

RESULTS

A comparison of the results between the groups revealed the following: homocysteine levels (μmol/L) were 10.75 (6.38-24.90) in group I (vaginitis positive) and 9.32 (4.26-17.10) in group II (control); vitamin B12 levels (ng/L) were 149.00 (63.00-328.00) in group I and 261.00 (126.00-544.00) in group II; folate levels (μg/L) were 10.56 (3.93-23.33) in group I and 9.48 (3.53-24.10) in group II; vitamin D levels (ng/mL) were 36.54 (23.65-75.68) in group I and 52.45 (26.57-105.00) in group II. Statistically significant elevation in homocysteine levels was observed in the vaginitis group (group I) (p<0.05). Vitamin B12 and D levels were significantly lower in the vaginitis group (group I) (p<0.05).

CONCLUSION

In pregnant women with recurrent vaginitis, the levels of homocysteine, vitamin B12, and vitamin D may play a role in the etiology of the condition, and vitamins B12 and D may be considered for use in treatment.

Association Between Elevated Total Homocysteine and Heart Failure Risk in the Multi-Ethnic Study of Atherosclerosis Cohort

BACKGROUND

Limited studies show an association between elevated total homocysteine (tHcy) and heart failure (HF) risk, but no studies have assessed whether this association differs by HF subtype. This study examines the relationship between tHcy, HF overall, and HF subtype (HF with preserved ejection fraction [HFpEF] and HF with reduced ejection fraction) in the Multi-Ethnic Study of Atherosclerosis cohort.

METHODS

Multi-Ethnic Study of Atherosclerosis participants with baseline tHcy and HF data were included (N=6765). Cox proportional hazards regression was used to calculate hazard ratios and 95% CI for tHcy and risk of HF. Models were stratified by impaired fasting glucose/type 2 diabetes status, and the combined impact of elevated tHcy and impaired fasting glucose/type 2 diabetes on HF incidence was examined.

RESULTS

Elevated tHcy (>12 μmol/L) was statistically significantly associated with HF overall and HFpEF, and conferred a higher risk for HF overall among individuals with dysglycemia impaired fasting glucose/type 2 diabetes compared with those with normoglycemia. Additionally, there was a statistically significant increased risk of HF overall and HF with reduced ejection fraction and a trend towards increased risk of HFpEF in individuals with both elevated tHcy and dysglycemia. tHcy appears to be a more significant contributor to HFpEF risk than dysglycemia, whereas dysglycemia seems to be more important in driving HF with reduced ejection fraction risk.

CONCLUSIONS

Our study confirms an association between hyperhomocysteinemia and HF risk in a large, multi-ethnic cohort. This is the first study to demonstrate that the impact of tHcy differs by HF subtype and appears to contribute more to HFpEF risk than HF with reduced ejection fraction risk.

Lipoprotein(a), high-sensitivity c-reactive protein, homocysteine and cardiovascular disease in the Multi-Ethnic Study of Atherosclerosis

Background and aims

Elevated lipoprotein(a) [Lp(a)], high-sensitivity C-Reactive Protein (hs-CRP), and total homocysteine (tHcy) are associated with atherosclerotic cardiovascular disease (ASCVD) risk. This study investigated the individual and joint associations of Lp(a), hs-CRP and tHcy with coronary heart disease (CHD) and stroke.

Methods

This study was conducted in the Multi-Ethnic Study of Atherosclerosis (MESA) cohort (2000-2017) (CHD analytic N = 6,676; stroke analytic N = 6,674 men and women). Associations between Lp(a) (<50 vs. ≥50 mg/dL), hs-CRP (<2 vs. ≥2 mg/L) and tHcy (<12 vs. ≥12 µmol/L) and CHD and stroke incidence were evaluated individually and jointly using Cox proportional hazards regression.

Results

Individually, elevated tHcy was associated with CHD and stroke incidence, Lp(a) with CHD only and hs-CRP with stroke only. In combined analyses, CHD risk was higher when multiple biomarkers were elevated [hs-CRP+Lp(a), hazard ratio (HR)=1.39, 95 % confidence interval (CI): 1.06, 1.82; hs-CRP+ tHcy, HR = 1.34, 95 % CI: 1.02, 1.75; Lp(a)+ tHcy HR = 1.58, 95 % CI: 1.08, 2.30; hs-CRP+Lp(a)+ tHcy HR = 2.02, 95 % CI: 1.26, 3.24]. Stroke risk was elevated when hs-CRP and either Lp(a) (HR = 1.51, 95 % CI: 1.02, 2.23) or tHcy (HR = 2.10, 95 % CI: 1.44, 3.06) was also high, when all three biomarkers were elevated (HR = 2.99, 95 % CI: 1.61, 5.58), or when hs-CRP and tHcy (HR = 1.79, 95 % CI: 1.16, 2.76) were both high.

Conclusions

Risk of ASCVD was highest with concomitant elevation of tHcy, hs-CRP and Lp(a). Inclusion of tHcy and consideration of biomarker combination rather than individual biomarker levels may help better identify individuals at greatest risk for ASCVD events.

Prognostic Significance of Homocysteine Levels in Patients with ST-Segment Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention: A Propensity Score Matching and Weighting Analysis

Background

Elevated homocysteine (Hcy) levels have been linked to poorer outcomes in acute coronary syndrome. This study aimed to assess the predictive value of elevated Hcy levels for major adverse cardiac events (MACE) in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI).

Methods

This retrospective cohort study included 183 STEMI patients who underwent primary PCI at a tertiary university hospital in southern China from January 2020 to December 2021. Laboratory values, including Hcy levels, were obtained within 24 hours of admission. Patients were categorized into elevated and normal Hcy groups using a threshold of 12 μmol/L. The study outcome was the occurrence of 6-point MACE, defined as cardiac death, nonfatal myocardial infarction, stroke, ischemia-driven revascularization (PCI or coronary artery bypass grafting), heart failure and all-cause death. Survival analyses were conducted using Kaplan-Meier and Cox proportional hazard methods. Propensity score matching (PSM) and inverse probability of treatment weighting (IPTW) approaches were employed to minimize bias.

Results

The mean age of the patients was 64.8 years, with 76.0% being male. After adjusting with PSM or IPTW, covariate imbalances between the two groups were corrected. Over a median follow-up period of 25.8 months, 55 MACE events occurred, resulting in an event rate of 30.1%. Patients with elevated Hcy levels had a higher incidence of MACE in both unadjusted (hazard ratio [HR] = 2.778; 95% confidence interval [CI]: 1.591-4.850; p < 0.001) and adjusted analyses (PSM: HR = 2.995; 95% CI: 1.397-6.423, p = 0.005; IPTW: HR = 3.2; 95% CI: 1.631-6.280, p < 0.001). Multivariate Cox regression further confirmed that elevated Hcy levels were associated with a worse prognosis across the entire cohort (HR = 1.062, 95% CI: 1.029-1.097, p < 0.001), PSM cohort (HR = 1.089, 95% CI: 1.036-1.145, p < 0.001), and IPTW cohort (HR = 1.052, 95% CI: 1.020-1.086, p = 0.001).

Conclusions

Elevated plasma levels of Hcy (≥12 μmol/L) are associated with worse outcomes in STEMI patients undergoing primary PCI, highlighting the potential role of Hcy as a prognostic marker in this population.

Hyperhomocysteinemia: Underlying Links to Stroke and Hydrocephalus, with a Focus on Polyphenol-Based Therapeutic Approaches

Hyperhomocysteinemia (HHcy), characterized by elevated homocysteine (HCys) levels, is associated with increased risks of neurovascular diseases such as stroke or hydrocephalus. HHcy promotes oxidative stress, neuroinflammation, and endothelial dysfunction, disrupting the blood-brain barrier and accelerating neurodegeneration. These processes highlight HCys as both a biomarker and a potential therapeutic target in vascular-related neurological disorders. Current research suggests that polyphenols, known for their antioxidant and anti-inflammatory properties, may reduce HCys levels and offer neuroprotection. Polyphenols have demonstrated effectiveness in modulating oxidative stress and inflammatory pathways triggered by HHcy. These compounds may also upregulate enzymatic functions involved in HCys metabolism, thus reducing neurotoxicity. Furthermore, polyphenol-rich diets, like the Mediterranean diet, have been linked to lower HCys levels and a reduced incidence of neurovascular disorders. This review provides an overview of HHcy's role in neurovascular pathologies and examines the therapeutic potential of polyphenols in managing HCys levels and preventing HCys-induced neurovascular damage.

Linking homocysteine and ferroptosis in cardiovascular disease: insights and implications

Homocysteine (Hcy) is a metabolic intermediate product derived from methionine. Hyperhomocysteinemia is a condition associated with various diseases. Hcy is recognized as a risk factor for cardiovascular disease (CVD). Ferroptosis, a novel form of cell death, is primarily characterized by substantial iron accumulation and lipid peroxidation. Recent research indicates a close association between ferroptosis and the pathophysiological processes of tumors, neurological diseases, CVD, and other ailments. However, limited research has been conducted on the impact of Hcy on ferroptosis. Therefore, this paper aimed to investigate the potential roles and mechanisms of homocysteine and ferroptosis in the context of cardiovascular disease. By conducting comprehensive literature research and analysis, we aimed to summarize recent advancements in understanding the effects of homocysteine on ferroptosis in cardiovascular diseases. This research contributes to a profound understanding of this critical domain.

Homocysteine aggravates intestinal inflammation through promotion of 5-LOX and COX-2 in IBD

BACKGROUND

Homocysteine (Hcy) is a pro-inflammatory molecule that has the potential to induce oxidative damage to cells and stimulate the release of inflammatory mediators. Hcy has been observed to enhance the production of inflammatory agents in vascular endothelial cells. However, the impact of Hcy on intestinal mucosal inflammation remains largely unexplored. Therefore, the objective of this study was to examine the potential of Hcy to stimulate the synthesis of inflammatory mediators and elucidate the underlying mechanisms in the intestinal mucosa.

METHODS

A total of 99 patients diagnosed with inflammatory bowel disease (IBD) and 10 healthy individuals were included in this study to assess the impact of homocysteine (Hcy) on the levels of leukotriene E4 (LTE4) and prostaglandin E2 (PGE2). The underlying mechanism responsible for the generation of LTE4 and PGE2 induced by Hcy was investigated using colitis rats and Caco-2 cells. 32 Sprague-Dawley rats were categorized into four groups: normal control, TNBS model, normal with Hcy injection, and TNBS model with Hcy injection. The mRNA expressions of 5-LOX, COX-2, and NF-κB were assessed using reverse transcription quantitative polymerase chain reaction (RT-qPCR). Caco-2 cells were subjected to treatment with varying concentrations (10, 20, 50, 100 μmol/L) of Hcy and incubated for different durations (1, 3, 6 h). The alterations in NF-κB activity, as well as the levels of Hcy, LTE4, and PGE2, were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

The excretion of Hcy, LTE4, and PGE2 in urine exhibited significant increases in patients with inflammatory bowel disease (IBD), Crohn's disease (CD), and ulcerative colitis (UC). In addition, Hcy demonstrated a significant increase in the expression of 5-LOX, COX-2, and NF-κB, as well as elevated levels of LTE4 and PGE2 in rats with colitis. Furthermore, Hcy was found to induce NF-κB activation and nuclear translocation, thereby contributing to the enhanced synthesis of LTE4 and PGE2 in Caco-2 cells.

CONCLUSIONS

Hcy was found to enhance the expression of 5-LOX and COX-2 by activating NF-κB, thereby augmenting the production of LTE4 and PGE2, which ultimately exacerbates colonic inflammation in individuals with inflammatory bowel disease (IBD).

Coupled single-cell and bulk RNA-seq analysis reveals the engulfment role of endothelial cells in atherosclerosis

The clearance of apoptotic cell debris, containing professional phagocytosis and non-professional phagocytosis, is essential for maintaining the homeostasis of healthy tissues. Here, we discovered that endothelial cells could engulf apoptotic cell debris in atherosclerotic plaque. Single-cell RNA sequencing (RNA-seq) has revealed a unique endothelial cell subpopulation in atherosclerosis, which was strongly associated with vascular injury-related pathways. Moreover, integrated analysis of three vascular injury-related RNA-seq datasets showed that the expression of scavenger receptor class B type 1 (SR-B1) was up-regulated and specifically enriched in the phagocytosis pathway under vascular injury circumstances. Single-cell RNA-seq and bulk RNA-seq indicate that SR-B1 was highly expressed in a unique endothelial cell subpopulation of mouse aorta and strongly associated with the reorganization of cellular adherent junctions and cytoskeleton which were necessary for phagocytosis. Furthermore, SR-B1 was strongly required for endothelial cells to engulf apoptotic cell debris in atherosclerotic plaque of both mouse and human aorta. Overall, this study demonstrated that apoptotic cell debris could be engulfed by endothelial cells through SR-B1 and associated with the reorganization of cellular adherent junctions and cytoskeleton.

Association between folate intake and radiographic progression, pain function scores in subjects with radiographic knee osteoarthritis: Data from the osteoarthritis initiative

BACKGROUND

Folate has an important role in the functioning of the musculoskeletal system, including modulation of inflammation, immunity, cartilage regeneration, prevention of osteoporosis, and maintenance of muscle strength, but evidence on the association between folate intake and knee pain, functional scores, and radiographic progression in patients with knee osteoarthritis (OA) is still limited.

METHODOLOGY

Our population-based cohort was extracted from the osteoarthritis initiative (OAI), focusing on individuals with prevalent radiographic knee OA (with a Kellgren-Lawrence score ≥2). Folate consumption was determined using the food frequency questionnaire. Data regarding the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores and radiographic readings were collected over 48 months. We analyzed the compiled data using generalized additive mixed models.

RESULTS

Our cohort consisted of 1472 OA patients (626 men and 846 women, mean [SD] age 62.35 [8.92]). At the 48-month follow-up, we observed a significant correlation between higher folate intake and a slower progression of knee pain and functional scores, as evidenced by a statistically significant decrease in the WOMAC total score, WOMAC pain subscale score, and WOMAC function/disability subscale score (p < .05). The fully adjusted models estimated a reduction of -0.028 points per 50 μg/1000 kcal of daily folate intake on the WOMAC pain subscale, -0.117 points on the WOMAC function subscale, and -0.160 points on the total WOMAC scale. Furthermore, our nonparametric fit analysis suggested that a higher intake of folate might decelerate the radiographic progression of OA. Stratified analyses indicated that an increase in folate consumption might particularly benefit men, older adults, overweight and obese individuals, and those with a higher dietary fiber intake.

CONCLUSION

Higher folate intake is correlated with improved knee function and reduced pain in patients with knee OA and might deter the radiographic progression of OA. The benefits appear to be more pronounced in men, older adults, overweight and obese individuals, and those with a higher dietary fiber intake.

Homocysteine Metabolism, Subclinical Myocardial Injury, and Cardiovascular Mortality in the General Population

Background

Homocysteine (Hcy) is a recognized cardiovascular disease (CVD) risk factor linked with atherosclerosis. However, the association between Hcy and myocardial injury is little known.

Objectives

This study aimed to examine the associations between Hcy metabolism, subclinical myocardial injury, and cardiovascular mortality.

Methods

We included 10,871 participants without diagnosed CVD. Generalized linear regression was used to investigate the relationship between Hcy-related indicators (plasma total Hcy [tHcy], vitamin B12, and folate) and myocardial injury biomarkers (high-sensitivity troponin T [hs-cTnT], high-sensitivity troponin I [hs-cTnI] measured using 3 assays [Abbott, Siemens, and Ortho], and N-terminal pro-B-type natriuretic peptide [NT-proBNP]).

Results

Among 10,871 participants, the weighted mean levels for tHcy, folate, and vitamin B12 were 8.58 μmol/L, 32.43 nmol/L, and 447.08 pmol/L, respectively. Plasma tHcy levels were positively associated with elevated hs-cTnT, hs-cTnI, and NT-proBNP, whereas folate and vitamin B12 were not inversely related to myocardial injury biomarkers. Multivariable-adjusted odds ratios for elevated hs-cTnT (19 ng/L) and NT-proBNP (125 pg/mL) per doubling of tHcy were 2.80 (95% CI: 1.17-6.73; P < 0.001) and 1.58 (95% CI: 1.20-2.08; P < 0.001), respectively. The associations of tHcy levels with elevated hs-cTnI (Abbott: 28 ng/L; Siemens: 46.5 ng/L; Ortho: 11 ng/L) were consistent. Indirect effects of tHcy on cardiovascular mortality risk via hs-cTnT and NT-proBNP explained up to 26.6% and 12.3% of the total effect, respectively.

Conclusions

Plasma tHcy, not folate or vitamin B12, is significantly associated with elevated hs-cTnT, hs-cTnI, and NT-proBNP in adults without CVD. Subclinical myocardial injury may substantially mediate Hcy-related cardiovascular mortality risk.

The role of taurine through endoplasmic reticulum in physiology and pathology

Taurine is a sulfur-containing amino acid found in many cell organelles that plays a wide range of biological roles, including bile salt production, osmoregulation, oxidative stress reduction, and neuromodulation. Taurine treatments have also been shown to ameliorate the onset and development of many diseases, including hypertension, fatty liver, neurodegenerative diseases and ischemia-reperfusion injury, by exerting antioxidant, anti-inflammatory, and antiapoptotic effects. The endoplasmic reticulum (ER) is a dynamic organelle involved in a wide range of cellular functions, including lipid metabolism, calcium storage and protein stabilization. Under stress, the disruption of the ER environment leads to the accumulation of misfolded proteins and a characteristic stress response called the unfolded protein response (UPR). The UPR protects cells from stress and helps to restore cellular homeostasis, but its activation promotes cell death under prolonged ER stress. Recent studies have shown that ER stress is closely related to the onset and development of many diseases. This article reviews the beneficial effects and related mechanisms of taurine by regulating the ER in different physiological and pathological states, with the aim of providing a reference for further research and clinical applications.

Implications of endoplasmic reticulum stress and autophagy in aging and cardiovascular diseases

The average lifespan of humans has been increasing, resulting in a rapidly rising percentage of older individuals and high morbidity of aging-associated diseases, especially cardiovascular diseases (CVDs). Diverse intracellular and extracellular factors that interrupt homeostatic functions in the endoplasmic reticulum (ER) induce ER stress. Cells employ a dynamic signaling pathway of unfolded protein response (UPR) to buffer ER stress. Recent studies have demonstrated that ER stress triggers various cellular processes associated with aging and many aging-associated diseases, including CVDs. Autophagy is a conserved process involving lysosomal degradation and recycling of cytoplasmic components, proteins, organelles, and pathogens that invade the cytoplasm. Autophagy is vital for combating the adverse influence of aging on the heart. The present report summarizes recent studies on the mechanism of ER stress and autophagy and their overlap in aging and on CVD pathogenesis in the context of aging. It also discusses possible therapeutic interventions targeting ER stress and autophagy that might delay aging and prevent or treat CVDs.

Ciliary neurotrophic factor promotes the development of homocysteine-induced vascular endothelial injury through inflammation mediated by the JAK2/STAT3 signaling pathway

Elevated homocysteine (Hcy) levels have been recognized as significant risk factor for cardiovascular and cerebrovascular diseases, closely related to endothelial injury. While expression of Ciliary Neurotrophic Factor (CNTF) significantly increases during Hcy-induced vascular endothelial cell injury, the precise molecular pathways through which CNTF operates remain to be clarified. To induce vascular endothelial cell injury, human umbilical vein endothelial cells (HUVECs) were treated with Hcy. Cell viability and apoptosis in HUVECs were assessed using the CCK-8 assay and flow cytometry. Western blot analysis determined the expression levels of the JAK2-STAT3 pathway, inflammation-related factors (IL-1β, NLRP3, ICAM-1, VCAM-1), and apoptosis-related factors (cleaved Caspase-3 and Bax). Immunofluorescence staining and western blotting were employed to examine CD31 and α-SMA expression. Knockdown of CNTF was achieved using lentiviral interference, and its effects on inflammation and cell injury were evaluated. Chromatin immunoprecipitation (ChIP) and dual luciferase reporter analysis were conducted to investigate the interaction between the MAFK and CNTF promoters. Our results indicated that Hcy induced high expression of CNTF and activated the JAK2-STAT3 signaling pathway, thereby upregulating factors associated with inflammation and cell apoptosis. Inhibiting CNTF alleviated Hcy-induced inflammation and cell injury. MAFK was identified as a transcription factor promoting CNTF transcription, and its overexpression exacerbated inflammation and cell injury in Hcy-treated HUVECs through the CNTF-JAK2-STAT3 axis, which could be reversed by knocking down CNTF. Activation of MAFK leads to CNTF upregulation, which activates the JAK2-STAT3 signaling pathway, regulating inflammation and inducing injury in Hcy-exposed vascular endothelial cells. Targeting CNTF or its upstream regulator MAFK may represent potential therapeutic strategies for mitigating endothelial dysfunction associated with hyperhomocysteinemia and cardiovascular diseases.

Homocysteine as a predictor of apnea-hypopnea index in obstructive sleep apnea: a longitudinal epidemiological study (EPISONO)

BACKGROUND

Obstructive sleep apnea (OSA) affects nearly 1 billion people globally, and has established links with cardiovascular and neurocognitive complications. Although it has some limitations, the apnea-hypopnea index (AHI) is commonly used to gauge OSA severity and therapeutic response. Homocysteine (Hcy) metabolism, when impaired, can elicit cellular senescence mechanisms that may be shared with OSA. Hence, our objective was to explore the role of Hcy concentrations both as a predictor of AHI values and as a potential risk factor for OSA.

METHODS

Involving 1042 volunteers aged 20 to 80 years, the initial study (2007) included polysomnographic evaluations, questionnaires on sleep and general health, as well as biochemical analyses. After an 8-year interval, 715 participants from the initial study were invited for a follow-up assessment in 2015.

RESULTS

Our findings showed that Hcy was a predictor for an increased AHI, and AHI increased over time. Individuals with plasma Hcy concentrations ≥ 15 µmol/L experienced an average AHI increase of 7.43 events/hour ([beta coefficient] β = 7.43; 95%CI 2.73 to 12.13) over time, compared to those with plasma concentrations < 10 µmol/L. A similar trend was apparent in those with plasma Hcy concentrations between 10 ≥  and  < 15 µmol/L, who had an AHI increase with an average beta coefficient of 3.20 events/hour (95%CI 1.01 to 5.39) compared to those with plasma Hcy concentrations < 10 µmol/L.

CONCLUSIONS

In summary, our study suggests that increased plasma Hcy concentrations could be considered a risk factor for the development of OSA. These findings highlight that elevated plasma Hcy concentrations can predict the severity of OSA, underscoring their correlation with the AHI.

Dietary vitamin B6 intake and stroke are negatively associated in adults: A cross-sectional study from the NHANES

Background

The relationship between dietary vitamin B6 and stroke risk is controversial; thus, we analyzed their correlation using data from the National Health and Nutrition Examination Survey (NHANES).

Method

Data from 2005 to 2018 were collected from the NHANES database. Two 24-h dietary recalls and a standard questionnaire were used to evaluate vitamin B6 intake and stroke prevalence. We used logistic regression models to estimate the association between dietary vitamin B6 intake and stroke risk and investigated the nonlinear relationship between them using a restricted cubic spline (RCS). Sensitivity analysis was conducted using propensity score matching (PSM).

Results

Among 24,214 participants, 921 were patients diagnosed with stroke, while 23,293 were without stroke. The multivariate logistic regression model revealed that individuals in the highest quartile of vitamin B6 consumption had a significantly lower stroke risk than those in the lowest quartile under the fully adjusted model (OR: 0.48, 95 % CI: 0.35-0.66, P < 0.001). Subgroup analyses showed that dietary intake of vitamin B6 was a significant protective factor against stroke risk in different populations, with the most pronounced effect in the population engaging in moderate-intensity physical activity (OR: 0.34, 95%CI: 0.20-0.57). The RCS models revealed a non-linear L-shaped relationship (P for nonlinearity = 0.006) between stroke and dietary intake of vitamin B6.

Conclusions

Our study shows that an increased intake of vitamin B6 could be an effective strategy in reducing the risk of stroke.

Hyperhomocysteinemia is associated with the risk of venous thromboembolism in patients with mental illness: a case-control study

Objective

The risk of venous thromboembolism in patients with mental illness has been insufficiently addressed. This study aimed to assess the correlation between hyperhomocysteinemia and venous thromboembolism prevalence among this population.

Methods

Patients with a diagnosis of mental illness and concurrent venous thromboembolism, admitted to Sir Run Run Shaw Hospital at Zhejiang University School of Medicine between January 2014 and December 2021, were included in the venous thromboembolism group. The control group, approximately twice the size, comprised individuals with mental illness but without venous thromboembolism. Basic clinical data were gathered for both cohorts.

Results

In psychiatric patients, elevated D-dimer levels(OR=5.60,95% CI 3.28-10.00), hyperhomocysteinemia (OR=2.37,95% CI 1.10-5.14), and hyperprolactinemia(OR= 2.68,95% CI 1.12-6.42)were significant risk factors for venous thromboembolism. According to further subgroup analyses, hyperhomocysteinemia is a significant risk factor associated with pulmonary embolism, with an OR of 5.08 (95% CI 1.20-21.48). An interaction effect between gender and homocysteine level was found, with a p-interaction of 0.022. A subsequent analysis confirmed the association between hyperhomocysteinemia and venous thromboembolism in female psychiatric patients, with an OR of 3.34 (95% CI 1.68-6.65), indicating that hyperhomocysteinemia is a significant risk factor for venous thromboembolism in women.

Conclusion

Patients with psychiatric disorders were found to have an elevated risk of venous thromboembolism, which was associated with increased levels of D-dimer, hyperprolactinemia, and hyperhomocysteinemia. A strong correlation between hyperhomocysteinemia and pulmonary embolism was identified in patients with mental illnesses. Furthermore, the study revealed that female psychiatric patients with hyperhomocysteinemia constituted a high-risk group for venous thromboembolism. This finding holds significant clinical implications, suggesting that early preventative measures could be implemented for this high-risk population to reduce the incidence of thromboembolic events during hospitalization for psychiatric patients.

Elucidating VSMC phenotypic transition mechanisms to bridge insights into cardiovascular disease implications

Cardiovascular diseases (CVD) are the leading cause of death worldwide, despite advances in understanding cardiovascular health. Significant barriers still exist in effectively preventing and managing these diseases. Vascular smooth muscle cells (VSMCs) are crucial for maintaining vascular integrity and can switch between contractile and synthetic functions in response to stimuli such as hypoxia and inflammation. These transformations play a pivotal role in the progression of cardiovascular diseases, facilitating vascular modifications and disease advancement. This article synthesizes the current understanding of the mechanisms and signaling pathways regulating VSMC phenotypic transitions, highlighting their potential as therapeutic targets in cardiovascular disease interventions.

Plasma Biomarkers for Hypertension-Mediated Organ Damage Detection: A Narrative Review

Hypertension (HT) is a disease that poses a serious threat to human health, mediating organ damage such as the cardiovascular (CV) system, kidneys, central nervous system (CNS), and retinae, ultimately increasing the risk of death due to damage to the entire vascular system. Thus, the widespread prevalence of hypertension brings enormous health problems and socioeconomic burdens worldwide. The goal of hypertension management is to prevent the risk of hypertension-mediated organ damage and excess mortality of cardiovascular diseases. To achieve this goal, hypertension guidelines recommend accurate monitoring of blood pressure and assessment of associated target organ damage. Early identification of organ damage mediated by hypertension is therefore crucial. Plasma biomarkers as a non-invasive test can help identify patients with organ damage mediated by hypertension who will benefit from antihypertensive treatment optimization and improved prognosis. In this review, we provide an overview of some currently available, under-researched, potential plasma biomarkers of organ damage mediated by hypertension, looking for biomarkers that can be detected by simple testing to identify hypertensive patients with organ damage, which is of great significance in clinical work. Natriuretic peptides (NPs) can be utilized as a traditional biomarker to detect hypertension-mediated organ damage, especially for heart failure. Nevertheless, we additionally may need to combine two or more plasma biomarkers to monitor organ damage in the early stages of hypertension.

An update on the cell-free DNA-derived methylome as a non-invasive biomarker for coronary artery disease

Cardiovascular diseases are the foremost contributor to global mortality, presenting a complex etiology and an expanding array of risk factors. Coronary artery disease characterized by atherosclerotic plaque build-up in the coronary arteries, imposes significant mortality and financial burdens, especially in low- and middle-income nations. The pathogenesis of coronary artery disease involves a multifaceted interplay of genetic, environmental, and epigenetic factors. Epigenetic regulation contributes to the dynamic control of gene expression without altering the underlying DNA sequence. The mounting evidence that highlights the pivotal role of epigenetic regulation in coronary artery disease development and progression, offering potential avenues for the development of novel diagnostic biomarkers and therapeutic targets. Abnormal DNA methylation patterns are linked to the modulation of gene expression involved in crucial processes like lipid metabolism, inflammation, and vascular function in the context of coronary artery disease. Cell-free DNA has become invaluable in tumor biology as a liquid biopsy, while its applications in coronary artery disease are limited, but intriguing. Atherosclerotic plaque rupture causes myocardial infarction, by depriving heart muscles of oxygen, releasing cell-free DNA from dead cardiac cells, and providing a minimally invasive source to explore tissue-specific epigenetic alterations. We discussed the methodologies for studying the global methylome and hydroxy-methylome landscape, their advantages, and limitations. It explores methylome alterations in coronary artery disease, considering risk factors and their relevance in coronary artery disease genesis. The review also details the implications of MI-derived cell-free DNA for developing minimally invasive biomarkers and associated challenges.

Blood Homocysteine Levels Mediate the Association Between Blood Lead Levels and Cardiovascular Mortality

Lead is a heavy, toxic metal and its exposure to humans can lead to increased risk of cardiovascular disease development and mortality. Lead exposure has been shown to induce hyperhomocysteinemia (HHCy) which may be a major pathogenic risk for the risk of CVDs. The aim of this study was to investigate whether homocysteine (Hcy) mediates the effect of lead on cardiovascular mortality. A total of 17,915 adults aged ≥ 20 who participated in the National Health and Nutrition Examination Survey (1999 to 2006). Information on mortality was ascertained via probabilistic matching to the death certificates from the National Death Index recorded up to December 31, 2015. Cox proportional hazards regression was performed to assess the association between blood lead levels and mortality. Mediation via Hcy was examined using a logit model. During a mean follow-up of 11.6 years, the incidences of CVD mortality were 0.73, 2.18, 3.03 and 4.94 per 1000 person-years across quarterlies of blood lead levels from low to high. Following multivariable adjustment, blood lead levels were strongly associated with CVD mortality in all mortality models (p-trend < 0.001). This association remained statistically significant after further adjusting for quartiles of homocysteine (model 3; HR 1.38 (95% CI 1.01-1.89) p-trend < 0.001). Furthermore, blood lead levels increased the odds of CVD mortality via homocysteine (indirect effect) (OR 1.42 (95% CI 1.30-1.55)), demonstrating the mediatory effect of homocysteine. This the first study that demonstrates that increased homocysteine mediates nearly half of CVD mortality related to blood lead levels.

Recreational use of nitrous oxide causes seizure, pneumothorax, pneumomediastinum, and pneumopericardium: nitrous oxide and its harm, a case report

Nitrous oxide, commonly known as 'laughing gas', has become a popular recreational drug. Whippets, small canisters containing gas in pressurized form, can be easily obtained from a food store. However, inhaling nitrous oxide from these canisters, which contain a 100% concentration, can lead to hypoxia, resulting in seizures or even death. Inhalation of nitrous oxide rarely causes pneumothorax, pneumomediastinum, and pneumopericardium. This case study highlights the potential dangers of recreational abuse of nitrous oxide.

A Comprehensive Investigation into the Association Between Mthfr C677t, A1298c, and Ace I/D Variants and Risk of Migraine: an Updated Meta-Analysis of Genetic Association Studies with Trial Sequential Analysis and Meta-Regression

Many homeostatic genes are thought to play a role in the susceptibility to migraine, making it a highly complex neurovascular disease. In this meta-analysis, our primary objective was to evaluate whether or not MTHFR variants (such as C677T and A1289C) and ACE I/D were associated with an increased risk of migraine. Using a PRISMA-based systematic literature-review guideline, internet sources such as PubMed and Google Scholar were searched to identify the genes of interest and migraine risk. To pool the data, odds ratios with 95% confidence intervals were calculated utilizing different genetic models. Cochran's Q Test and I2 statistics were used to access heterogeneity, while Begg's and Egger's tests were used to identify publication bias. All tests were two-sided, and a p-value of < 0.05 was regarded as statistically significant. The present meta-analysis observed that the C677T variant is significantly associated with the increased risk of migraine (allele model: OR:1.19, CI [1.07-1.33], I2 = 78%) and its clinical subtype i.e., MA (allele model: OR: 1.26, CI [1.09-1.45], I2 = 80%) in the overall population. Concerning the ACE- I/D, it significantly increased the risk of overall migraine and both clinical subtypes after utilizing the dominant genetic models (OR: 1.14, CI [1.01-1.29], I2% = 32). Concerning the MTHFR A1289C, only the codominant model (HR vs HT) and recessive model significantly increased the risk of overall migraine. Therefore, the findings of the present meta-analysis showed that MTHFR-C677T is an important risk factor for migraine and its clinical subtype.

Homocysteine impairs the anticontractile/vasorelaxing activity of perivascular adipose tissue surrounding human internal mammary artery

OBJECTIVES

Perivascular adipose tissue (PVAT) surrounding human internal mammary artery (IMA) possesses anticontractile property. Its function under pathological conditions is barely studied. We previously reported that homocysteine impairs the vasodilator function of IMA through endothelium and smooth muscle-dependent mechanisms. This study investigated the effect of homocysteine on the function of PVAT and the associated mechanisms.

METHODS

Residual IMA tissues were collected from patients undergoing coronary artery bypass grafting. Vasoreactivity was studied using myograph. Adiponectin was measured by ELISA. Expressions of adiponectin receptors (AdipoRs), eNOS and p-eNOS were determined by RT-qPCR and Western blot.

RESULTS

Exposure to homocysteine augmented the contractile responses of PVAT-intact IMA to U46619 and potassium chloride, regardless with or without endothelium. Such augmentation was also observed in skeletonized IMA with transferred, homocysteine-exposed PVAT. Homocysteine attenuated the relaxant response of PVAT-intact while endothelium-denuded vessels to acetylcholine. Homocysteine lowered adiponectin content in the PVAT, downregulated the expression of AdipoR1 and AdipoR2 as well as eNOS and p-eNOS in skeletonized IMA. The relaxant response of skeletonized IMA to AdipoR agonist AdipoRon was blunted by homocysteine or eNOS inhibitor, and homocysteine significantly attenuated the inhibitory effect of eNOS inhibitor on AdipoRon-induced relaxation.

CONCLUSIONS

Homocysteine impairs the anticontractile/vasorelaxing activity of PVAT surrounding the IMA through inhibiting adiponectin/AdipoR/eNOS/nitric oxide signalling pathway.

Sex differences in cardiometabolic biomarkers during the pre-diabetes stage

Using two large prospective epidemiological studies in the U.S., we examined biomarkers that reflect sex-specific pathophysiological pathways to cardiovascular complications among people with pre-diabetes. Women with pre-diabetes exhibited higher levels of adipokines, while men had lower eGFR. Sex differences in lipoproteins and vascular inflammatory markers during pre-diabetes indicate sex-specific lipoprotein and inflammatory mechanisms to cardiovascular complications.

Hyperhomocysteinaemia Promotes Doxorubicin-Induced Cardiotoxicity in Mice

Doxorubicin, a widely used chemotherapeutic drug in clinical oncology, causes a series of cardiac side effects referred to as doxorubicin-induced cardiotoxicity. Hyperhomocysteinaemia is an independent risk factor for multiple cardiovascular diseases. However, whether hyperhomocysteinaemia contributes to doxorubicin-induced cardiotoxicity is currently unknown. In this study, we explored the pathogenic effects of hyperhomocysteinaemia induced by dietary methionine supplementation (2% wt/wt in rodent chow) in a mouse model of doxorubicin-induced cardiotoxicity. Our data showed that methionine supplementation doubled serum homocysteine levels, inducing mild hyperhomocysteinaemia. Doxorubicin at a cumulative dosage of 25 mg/kg body weight led to significant weight loss and severe cardiac dysfunction, which were further exacerbated by methionine-induced mild hyperhomocysteinaemia. Doxorubicin-induced cardiac atrophy, cytoplasmic vacuolisation, myofibrillar disarray and loss, as well as cardiac fibrosis, were also exacerbated by methionine-induced mild hyperhomocysteinaemia. Additional folic acid supplementation (0.006% wt/wt) prevented methionine-induced hyperhomocysteinaemia and inhibited hyperhomocysteinaemia-aggravated cardiac dysfunction and cardiomyopathy. In particular, hyperhomocysteinaemia increased both serum and cardiac oxidative stress, which could all be inhibited by folic acid supplementation. Therefore, we demonstrated for the first time that hyperhomocysteinaemia could exacerbate doxorubicin-induced cardiotoxicity in mice, and the pathogenic effects of hyperhomocysteinaemia might at least partially correlate with increased oxidative stress and could be prevented by folic acid supplementation. Our study provides preliminary experimental evidence for the assessment of hyperhomocysteinaemia as a potential risk factor for chemotherapy-induced cardiotoxicity in cancer patients.

Advances in the role of epigenetics in homocysteine-related diseases

Homocysteine has a wide range of biological effects. However, the specific molecular mechanism of its pathogenicity is still unclear. The diseases induced by hyperhomocysteinemia (HHcy) are called homocysteine-related diseases. Clinical treatment of HHcy is mainly through folic acid and B-complex vitamins, which are not effective in reducing the associated end point events. Epigenetics is the alteration of heritable genes caused by DNA methylation, histone modification, noncoding RNAs and chromatin remodeling without altering the DNA sequence. In recent years the role of epigenetics in homocysteine-associated diseases has been gradually discovered. This article summarizes the latest evidence on the role of epigenetics in HHcy, providing new directions for its prevention and treatment.

Associations between homocysteine and B vitamins and stroke: a cross-sectional study

Objective

Homocysteine (Hcy) is a predictor for stroke. B vitamins are required for the metabolism of Hcy. We designed a study to investigate the associations of plasma Hcy and B vitamins with the prevalence of stroke in adults.

Methods

A total of 8,371 adults were included in the National Health and Examination Survey (NHANES) between 2003-2006 in the United States. Multivariate regression analysis and smooth curve fitting were conducted to evaluate the associations of stroke prevalence with Hcy, folate, vitamin B6, and B12. A segmented regression model was used to analyze the threshold effects. Sample weights were calculated to ensure the results' generalizability.

Results

The mean age of all participants was 46.43 years (51.8% women), and the prevalence of stroke was 2.72%. A nonlinear and positive association was found between plasma Hcy levels and the prevalence of stroke. Furthermore, L-shaped associations were found between plasma vitamin B6 and folate levels and stroke, with the turning point at 65.2 nmol/L for vitamin B6 and 26 nmol/L for folate, respectively. Vitamin B12 revealed a U-shaped relationship with stroke, with the turning points at 492.98 pmol/L for vitamin B12.

Conclusion

Non-linear associations of plasma Hcy and B vitamins levels with stroke prevalence were found in American adults. These associations may have an implication that higher plasma Hcy levels should be reduced, and plasma vitamin B6, vitamin B12 and folate levels should be moderately improved in stroke prevention. Future studies are needed to verify the causality of these associations and elucidate the underlying mechanisms.

Homocysteine induces ferroptosis in endothelial cells through the systemXc-/GPX4 signaling pathway

OBJECTIVES

To investigate whether ferroptosis is involved in HCY-induced endothelial injury and the possible mechanism of HCY-induced ferroptosis.

METHODS

EA. hy926 cells were cultured in vitro. Cells were intervened using HCY and Fer-1. The cells were divided into Control groups, HCY (4 mM), HCY (8 mM), HCY + Fer-1 (4 mM HCY + 0.5/2.5/5 µM Fer-1). CCK-8 assay was used to detect cell viability; Flow Cytometry was used to detect cellular Lip-ROS, TBA and Microplate assay was used to detect MDA&GSH, Western blot was used to detect the expression of ferroptosis-related proteins GPX4 and SLC7A11.

RESULTS

HCY can inhibited the proliferation of EA. hy926 cells in a time- and concentration-dependent manner; Fer-1 inhibits HCY-induced ferroptosis in EA.hy926 cells in a concentration-dependent manner; Compared with the control group, the cell viability and GSH content in the HCY group was significantly decreased (p < 0.05), and the Lip-ROS and MDA were significantly increased (p < 0.05); After co-culture of HCY and Fer-1, compared with the HCY (4 mM) group, the cell viability and GSH content in the co-culture group were significantly increased (p < 0.05), and the Lip-ROS and MDA were significantly decreased (p < 0.05) in a concentration-dependent manner; Western blotting results showed that the protein expression levels of ferroptosis-related proteins GPX4 and SLC7A11 in each experimental were significantly decreased after HCY treatment (p < 0.05), and Fer-1 could significantly reverse this effect.

CONCLUSIONS

(1) HCY can induce ferroptosis in vascular endothelial cells. (2) HCY may induce vascular endothelial cell ferroptosis through the system Xc-GSH-GPX4 signaling pathway.

Association between Micronutrients and Hyperhomocysteinemia: A Case-Control Study in Northeast China

Hyperhomocysteinemia (HHcy) is an independent risk factor for cardiovascular and cerebrovascular diseases where the plasma homocysteine (Hcy) concentration exceeds 15 µmol/L. HHcy is affected by vitamins B12, B6, and folic acid (fol); however, its relationship with other nutrients is not fully understood. We investigated the nutritional and genetic factors associated with HHcy and the possible dose-response relationships or threshold effects in patients in Northeast China. Genetic polymorphisms and micronutrients were tested with polymerase chain reaction and mass spectrometry, respectively. This trial was registered under trial number ChiCTR1900025136. The HHcy group had significantly more males and higher body mass index (BMI), methylenetetrahydrofolate reductase (MTHFR 677TT) polymorphism proportion, and uric acid, Zn, Fe, P, and vitamin A levels than the control group. After adjusting for age, sex, BMI, vitamin B12, fol, and MTHFR C677T, the lowest Zn quartile reduced the odds ratio of HHcy compared with the highest Zn quartile. The dose-response curves for the association between plasma Zn and HHcy were S-shaped. High plasma Zn concentrations were significantly correlated with high HHcy odds ratios, and the curve leveled off or slightly decreased. Most importantly, HHcy risk decreased with decreasing plasma Zn concentration; the threshold was 83.89 µmol/L. Conclusively, individuals residing in Northeast China, especially those with the MTHFR 677TT polymorphism, must pay attention to their plasma Zn and Hcy levels.

Homocysteine accelerates hepatocyte autophagy by upregulating TFEB via DNMT3b-mediated DNA hypomethylation

Autophagy plays a critical role in the physiology and pathophysiology of hepatocytes. High level of homocysteine (Hcy) promotes autophagy in hepatocytes, but the underlying mechanism is still unknown. Here, we investigate the relationship between Hcy-induced autophagy level and the expression of nuclear transcription factor EB (TFEB). The results show that Hcy-induced autophagy level is mediated by upregulation of TFEB. Silencing of TFEB decreases the level of autophagy-related protein LC3BII/I and increases p62 expression level in hepatocytes after exposure to Hcy. Moreover, the effect of Hcy on the expression of TFEB is regulated by hypomethylation of the TFEB promoter catalyzed by DNA methyltransferase 3b (DNMT3b). In summary, this study shows that Hcy can activate autophagy by inhibiting DNMT3b-mediated DNA methylation and upregulating TFEB expression. These findings provide another new mechanism for Hcy-induced autophagy in hepatocytes.

Metallothionein-2: An emerging target in inflammatory diseases and cancers

Metallothionein-2 (MT-2) was originally discovered as a mediator of zinc homeostasis and cadmium detoxification. However, MT-2 has recently received increased attention because altered expression of MT-2 is closely related to various diseases such as asthma and cancers. Several pharmacological strategies have been developed to inhibit or modify MT-2, revealing its potential as drug target in diseases. Therefore, a better understanding of the mechanisms of MT-2 action is warranted to improve drug development for potential clinical applications. In this review, we highlight recent advances in determining the protein structure, regulation, binding partners, and new functions of MT-2 in inflammatory diseases and cancers.

MiR18a5p aggravates homocysteineinduced myocardial injury via autophagy

OBJECTIVES

Hyperhomocysteinaemia (Hcy) is an independent risk factor for cardiovascular and cerebrovascular diseases. MicroRNA (miR)-18a-5p is closely related to cardiovascular diseases. This study aims to investigate the effects of miR-18a-5p on homocysteine (Hcy)-induced myocardial cells injury.

METHODS

H9c2 cells were transfected with miR-18a-5p mimic/miR-18a-5p mimic negative control (NC) or combined with Hcy for intervention, and untreated cells were set as a control group. The transfection efficiency was verified by real-time RT-PCR, and cell counting kit-8 (CCK-8) assay was used to determine cell viability. Flow cytometry was used to detect apoptosis and reactive oxygen species (ROS) levels. Western blotting was performed to measure the protein levels of microtubule-associated protein 1 light chain 3 (LC3)-I, LC3-II, Beclin1, p62, Bax, Bcl-2, and Notch2. Dual luciferase reporter assay was used to detect the interaction of miR-18a-5p with Notch2.

RESULTS

Compared with the control, treatment with Hcy or transfection with miR-18a-5p mimic alone, or combined treatment with Hcy and miR-18a-5p mimic/miR-18a-5p mimic NC significantly reduced the H9c2 cell viability, promoted apoptosis and ROS production, up-regulated the expressions of Bax and Beclin, down-regulated the expressions of Bcl-2, p62, and Notch2, and increased the ratio of LC3-II/LC3-I (all P<0.05). Compared with the combined intervention of miR-18a-5p mimic NC and Hcy group, the above indexes were more significantly changed in the combined intervention of miR-18a-5p mimic and Hcy group, and the difference between the 2 groups was statistically significant (all P<0.05). There is a targeted binding between Notch2 and miR-18a-5p.

CONCLUSIONS

MiR-18a-5p could induce autophagy and apoptosis via increasing ROS production in cardiomyocytes, and aggravate Hcy-induced myocardial injury. Notch2 is a target of miR-18a-5p.

Mechanism of homocysteine-mediated endothelial injury and its consequences for atherosclerosis

Homocysteine (Hcy) is an intermediate amino acid formed during the conversion from methionine to cysteine. When the fasting plasma Hcy level is higher than 15 μmol/L, it is considered as hyperhomocysteinemia (HHcy). The vascular endothelium is an important barrier to vascular homeostasis, and its impairment is the initiation of atherosclerosis (AS). HHcy is an important risk factor for AS, which can promote the development of AS and the occurrence of cardiovascular events, and Hcy damage to the endothelium is considered to play a very important role. However, the mechanism by which Hcy damages the endothelium is still not fully understood. This review summarizes the mechanism of Hcy-induced endothelial injury and the treatment methods to alleviate the Hcy induced endothelial dysfunction, in order to provide new thoughts for the diagnosis and treatment of Hcy-induced endothelial injury and subsequent AS-related diseases.

Sleep Duration, Midday Napping, and Serum Homocysteine Levels: A Gene-Environment Interaction Study

The associations of sleep duration and midday napping with homocysteine (Hcy) levels, and whether these sleep behaviors modify the association between genetic predisposition and Hcy levels, has yet to be investigated. We included 19,426 participants without severe health conditions at baseline from the Dongfeng−Tongji cohort. In a subgroup of 15,126 participants with genetic data, a genetic risk score (GRS) based on 18 Hcy-related loci was constructed to test the gene−sleep interactions in Hcy. Hcy levels were higher in subjects with a long sleep duration (≥9 h) and midday napping (>90 min), as compared to those who reported a moderate sleep duration (7 to <8 h) and midday napping (1−30 min) (all p values < 0.05). A long sleep duration and midday napping showed a joint effect in increasing Hcy (p for trend < 0.001). Significant interactions regarding Hcy levels were observed for a long sleep duration with GRS and MTHFR rs1801133, and long midday napping with DPEP1 rs12921383 (all p values for interaction < 0.05). Overall findings indicated that a long sleep duration and midday napping were associated with elevated serum Hcy levels, independently and jointly, and amplified the genetic susceptibility to higher Hcy.

Modulation of the Inflammatory Response in Polycystic Ovary Syndrome (PCOS)-Searching for Epigenetic Factors

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age. Despite its incidence, the syndrome is poorly understood and remains underdiagnosed, and female patients are diagnosed with a delay. The heterogenous nature of this complex disorder results from the combined occurrence of genetic, environmental, endocrine, and behavioral factors. Primary clinical manifestations of PCOS are derived from the excess of androgens (anovulation, polycystic ovary morphology, lack of or scanty, irregular menstrual periods, acne and hirsutism), whereas the secondary manifestations include multiple metabolic, cardiovascular, and psychological disorders. Dietary and lifestyle factors play important roles in the development and course of PCOS, which suggests strong epigenetic and environmental influences. Many studies have shown a strong association between PCOS and chronic, low-grade inflammation both in the ovarian tissue and throughout the body. In the vast majority of PCOS patients, elevated values of inflammatory markers or their gene markers have been reported. Development of the vicious cycle of the chronic inflammatory state in PCOS is additionally stimulated by hyperinsulinemia and obesity. Changes in DNA methylation, histone acetylation and noncoding RNA levels are presented in this review in the context of oxidative stress, reactive oxygen species, and inflammatory signaling in PCOS. Epigenetic modulation of androgenic activity in response to inflammatory signaling is also discussed.

DNA methylation in diabetic retinopathy: pathogenetic role and potential therapeutic targets

Background

Diabetic retinopathy (DR), a specific neuron-vascular complication of diabetes, is a major cause of vision loss among middle-aged people worldwide, and the number of DR patients will increase with the increasing incidence of diabetes. At present, it is limited in difficult detection in the early stages, limited treatment and unsatisfactory treatment effects in the advanced stages.

Main body

The pathogenesis of DR is complicated and involves epigenetic modifications, oxidative stress, inflammation and neovascularization. These factors influence each other and jointly promote the development of DR. DNA methylation is the most studied epigenetic modification, which has been a key role in the regulation of gene expression and the occurrence and development of DR. Thus, this review investigates the relationship between DNA methylation and other complex pathological processes in the development of DR. From the perspective of DNA methylation, this review provides basic insights into potential biomarkers for diagnosis, preventable risk factors, and novel targets for treatment.

Conclusion

DNA methylation plays an indispensable role in DR and may serve as a prospective biomarker of this blinding disease in its relatively early stages. In combination with inhibitors of DNA methyltransferases can be a potential approach to delay or even prevent patients from getting advanced stages of DR.

Epigenetic Regulation by microRNAs in Hyperhomocysteinemia-Accelerated Atherosclerosis

Increased serum levels of homocysteine (Hcy) is a risk factor for cardiovascular disease and is specifically linked to various diseases of the vasculature such as atherosclerosis. However, the precise mechanisms by which Hcy contributes to this condition remain elusive. During the development of atherosclerosis, epigenetic modifications influence gene expression. As such, epigenetic modifications are an adaptive response to endogenous and exogenous factors that lead to altered gene expression by methylation and acetylation reactions of different substrates and the action of noncoding RNA including microRNAs (miRNAs). Epigenetic remodeling modulates cell biology in both physiological and physiopathological conditions. DNA and histone modification have been identified to have a crucial role in the progression of atherosclerosis. However, the potential role of miRNAs in hyperHcy (HHcy)-related atherosclerosis disease remains poorly explored and might be essential as well. There is no review available yet summarizing the contribution of miRNAs to hyperhomocystein-mediated atherogenicity or their potential as therapeutic targets even though their important role has been described in numerous studies. Specifically, downregulation of miR-143 or miR-125b has been shown to regulate VSCMs proliferation in vitro. In preclinical studies, downregulation of miR-92 or miR195-3p has been shown to increase the accumulation of cholesterol in foam cells and increase macrophage inflammation and atherosclerotic plaque formation, respectively. Another preclinical study found that there is a reciprocal regulation between miR-148a/152 and DNMT1 in Hcy-accelerated atherosclerosis. Interestingly, a couple of studies have shown that miR-143 or miR-217 may be used as potential biomarkers in patients with HHcy that may develop atherosclerosis. Moreover, the current review will also update current knowledge on miRNA-based therapies, their challenges, and approaches to deal with Hcy-induced atherosclerosis.

Serum Homocysteine and Vascular Calcification: Advances in Mechanisms, Related Diseases, and Nutrition

Identifying and preventing modifiable risk factors for cardiovascular disease is very important. Vascular calcification has been studied clinically as an asymptomatic preclinical marker of atherosclerosis and a risk factor for cardio-cerebrovascular disease. It is known that higher homocysteine levels are associated with calcified plaques and the higher the homocysteine level, the higher the prevalence and progression of vascular calcification. Homocysteine is a byproduct of methionine metabolism and is generally maintained at a physiological level. Moreover, it may increase if the patient has a genetic deficiency of metabolic enzymes, nutritional deficiencies of related cofactors (vitamins), chronic diseases, or a poor lifestyle. Homocysteine is an oxidative stress factor that can lead to calcified plaques and trigger vascular inflammation. Hyperhomocysteinemia causes endothelial dysfunction, transdifferentiation of vascular smooth muscle cells, and the induction of apoptosis. As a result of transdifferentiation and cell apoptosis, hydroxyapatite accumulates in the walls of blood vessels. Several studies have reported on the mechanisms of multiple cellular signaling pathways that cause inflammation and calcification in blood vessels. Therefore, in this review, we take a closer look at understanding the clinical consequences of hyperhomocysteinemia and apply clinical approaches to reduce its prevalence.

Hyperhomocysteinemia Promotes Cardiac Hypertrophy in Hypertension

Hyperhomocysteinemia (HHcy) is positively linked with several cardiovascular diseases; however, its role and underlying mechanisms in pathological cardiac hypertrophy are still unclear. Here, we focused on the effects and underlying mechanisms of HHcy in hypertensive cardiac hypertrophy, one of the most common and typical types of pathological cardiac hypertrophy. By a retrospective analysis of the association between HHcy and cardiac hypertrophy in a hypertensive cohort, we found that the prevalence of HHcy was higher in patients with hypertrophy and significantly associated with the presence of cardiac hypertrophy after adjusting for other conventional risk factors. In mice, HHcy induced by a methionine (2% wt/wt) diet feeding significantly promoted cardiac hypertrophy as well as cardiac inflammation and fibrosis induced by 3-week angiotensin ІІ (AngІІ) infusion (1000 ng/kg/min), while folic acid (0.006% wt/wt) supplement corrected HHcy and attenuated AngII-stimulated cardiac phenotypes. Mechanistic studies further showed that homocysteine (Hcy) exacerbated AngII-stimulated expression of Calcineurin and nuclear factor of activated T cells (NFAT), which could be attenuated by folic acid both in mice and in neonatal rat cardiomyocytes. Moreover, treatment with cyclosporin A, an inhibitor of Calcineurin, blocked Hcy-stimulated Calcineurin-NFAT signaling and hypertrophy in neonatal rat cardiomyocytes. In conclusion, our study indicates that HHcy promotes cardiac hypertrophy in hypertension, and Calcineurin-NFAT pathway might be involved in the pro-hypertrophic effect of Hcy.

Thromboembolic complications of recreational nitrous oxide (ab)use: a systematic review

The recreatinal use of nitrous oxide has become more common in recent years, especially in adolescents and young adults. It has been mainly associated with medical conditions like megaloblastic anemia and (myelo)neuropathy. We report on the thromboembolic complications, a less known side effect, associated with recreational inhalation of nitrous oxide. An extensive literature search was performed for publications reporting on the thromboembolic complications associated with recreational nitrous oxide abuse. Data about sex, age, location of thrombosis, laboratory findings, therapy and outcome were collected. A total of 13 case reports or case series were identified comprising a total of 14 patients. The reported thromboembolic side effects included deep venous thrombosis, pulmonary embolism, mesenterial-, portal and splenic vein thrombosis, cerebral sinus thrombosis, cortical vein thrombosis, stroke, acute myocardial infarction and peripheral artery thromboembolism. These side effects are possibly mediated by the interaction of nitrous oxide with vitamin B12, a cofactor of the methionine synthase complex, which eventually results in elevation of plasma levels of homocysteine. Despite being a known risk factor for cardiovascular disease, the exact pathophysiological mechanism remains unclear. Cessation of nitrous oxide inhalation is necessary to prevent recurrent thrombosis. Nitrous oxide abuse may thus result in a wide spectrum of thromboembolic complications. One should be aware of this etiology, especially in a young person with no obvious risk factors for cardiovascular disease. Spreading awareness is important to inform people about the potentially serious side effects associated with nitrous oxide inhalation.

Serum folate levels and hypertension

We aimed to examine the association between serum folate levels and hypertension in Korean adults. Our study population was 6343 Korean adults whose blood pressure and folate levels were measured in the Korea National Health and Nutrition Examination Survey 2016–2018. We aggregated the study populations into quintiles according to serum folate levels (1.5–4.3, 4.4–5.7, 5.8–7.5, 7.6–10.3, and 10.4–35.9 ng/mL). Multivariable logistic and linear regression models were used to analyze the relationships between serum folate levels, blood pressure, and hypertension. The weighted average of serum folate levels was 7.4 ng/mL, and the weighted prevalence of hypertension was 30.4% in the study populations. After adjusting for all potential confounders, compared to those in the lowest quintile of serum folate levels, systolic and diastolic blood pressure of the people in the other quintiles were not significantly different. The linear relationship between serum folate levels and blood pressure was not statistically significant. The odds for hypertension were not significantly different across the quintiles of serum folate levels. This study showed high serum folate levels was not significantly associated with lowering hypertension in Korean adults.

Serum uric acid concentration is associated with hyperhomocysteinemia in hypertensive Chinese adults

PURPOSE

This study is to investigate the correlation between serum uric acid levels and hyperhomocysteinemia Chinese adult patients with hypertension.

METHODS

We enrolled 981 hypertensive patients, including unmedicated hypertensives, in our study. There were 453 patients with hyperhomocysteinemia (hyperhomocysteinemia hypertension group) and 528 without it (ordinary hypertension group). We collected histories of coronary heart disease, diabetes, and smoking and tested patients' BMI, blood pressure, fasting serum uric acid, serum total cholesterol, triglycerides, low-density lipoprotein cholesterol, serum creatinine, and homocysteine. Subjects were stratified into four groups according to their serum uric acid quartiles: Q1 group, 249 cases (≤268 μmol/L); Q2 group, 245 cases (269-322 μmol/L); Q3 group, 244 cases (323-378 μmol/L); and Q4 group, 243 cases (≥379 μmol/L). We employ logistic regression analysis to investigate the relationship between serum uric acid levels and the risk of hyperhomocysteinemia in patients with hypertension.

RESULTS

We find that there were significant differences in gender distribution, serum uric acid, BMI, serum creatinine, total cholesterol, and diastolic blood pressure between the two groups (P < 0.05). The prevalence of hyperhomocysteinemia in groups Q1 through Q4 was 26.91% (67/249), 45.31% (111/245), 47.01% (117/244), and 65.02% (158/243), respectively, after adjusting for relevant factors, we find that the risk of hyperhomocysteinemia in the Q4 group was significantly higher than that in the Q1 group (odds ratio = 3.00, 95% confidence interval: 1.83-4.93).

CONCLUSION

We find evidence that an elevated serum uric acid level is an independent indicator for hyperhomocysteinemia in patients with hypertension.

Consumption of Cashew (Anacardium occidentale L.) Nuts Counteracts Oxidative Stress and Tissue Inflammation in Mild Hyperhomocysteinemia in Rats

Hyperhomocysteinemia (HHcy) is a methionine metabolism problem that causes a variety of inflammatory illnesses. Oxidative stress is among the processes thought to be involved in the pathophysiology of the damage produced by HHcy. HHcy is likely to involve the dysfunction of several organs, such as the kidney, liver, or gut, which are currently poorly understood. Nuts are regarded as an important part of a balanced diet since they include protein, good fatty acids, and critical nutrients. The aim of this work was to evaluate the anti-inflammatory and antioxidant effects of cashew nuts in HHcy induced by oral methionine administration for 30 days, and to examine the possible pathways involved. In HHcy rats, cashew nuts (100 mg/kg orally, daily) were able to counteract clinical biochemical changes, oxidative and nitrosative stress, reduced antioxidant enzyme levels, lipid peroxidation, proinflammatory cytokine release, histological tissue injuries, and apoptosis in the kidney, colon, and liver, possibly by the modulation of the antioxidant nuclear factor erythroid 2-related factor 2 NRF-2 and inflammatory nuclear factor NF-kB pathways. Thus, the results suggest that the consumption of cashew nuts may be beneficial for the treatment of inflammatory conditions associated with HHcy.

Homocysteine as a marker for predicting disease severity in patients with COVID-19

Aim: Our study was designed on the hypothesis that homocysteine levels are a prognostic parameter that can predict the severity of COVID-19 disease. Materials & methods: 117 COVID-19 patients and 34 non COVID-19 individuals were included in the study. Receiver operating characteristic (ROC) analysis was performed for homocysteine, D-dimer and monocyte/lymphocyte ratio (MLR) levels. Results: According to the ROC analysis, in COVID-19 patients group, Area under curve (AUC) values were 0.835 for homocysteine, 0.859 for D-dimer and 0.882 for MLR. According to the ROC analysis, in which homocysteine, MLR and D-dimer parameters were evaluated together, AUC values were 0.951 in the mild disease group, 1,000 in severe disease group and 0.967 in COVID-19 patients group. Conclusion: It was concluded that homocysteine level is an important parameter in the follow-up of COVID-19 disease.

The Controversial Role of HCY and Vitamin B Deficiency in Cardiovascular Diseases

Plasma homocysteine (HCY) is an established risk factor for cardiovascular disease CVD and stroke. However, more than two decades of intensive research activities has failed to demonstrate that Hcy lowering through B-vitamin supplementation results in a reduction in CVD risk. Therefore, doubts about a causal involvement of hyperhomocysteinemia (HHcy) and B-vitamin deficiencies in atherosclerosis persist. Existing evidence indicates that HHcy increases oxidative stress, causes endoplasmatic reticulum (ER) stress, alters DNA methylation and, thus, modulates the expression of numerous pathogenic and protective genes. Moreover, Hcy can bind directly to proteins, which can change protein function and impact the intracellular redox state. As most mechanistic evidence is derived from experimental studies with rather artificial settings, the relevance of these results in humans remains a matter of debate. Recently, it has also been proposed that HHcy and B-vitamin deficiencies may promote CVD through accelerated telomere shortening and telomere dysfunction. This review provides a critical overview of the existing literature regarding the role of HHcy and B-vitamin deficiencies in CVD. At present, the CVD risk associated with HHcy and B vitamins is not effectively actionable. Therefore, routine screening for HHcy in CVD patients is of limited value. However, B-vitamin depletion is rather common among the elderly, and in such cases existing deficiencies should be corrected. While Hcy-lowering with high doses of B vitamins has no beneficial effects in secondary CVD prevention, the role of Hcy in primary disease prevention is insufficiently studied. Therefore, more intervention and experimental studies are needed to address existing gaps in knowledge.