Hyperhomocysteinemia activates nuclear factor-kappaB in endothelial cells via oxidative stress

Mild hyperhomocysteinemia alters oxidative stress profile via Nrf2, inflammation and cholinesterases in cardiovascular system of aged male rats

Homocysteine (Hcy) is an independent cardiovascular disease (CVD) risk factor, whose mechanisms are poorly understood. We aimed to explore mild hyperhomocysteinemia (HHcy) effects on oxidative status, inflammatory, and cholinesterase parameters in aged male Wistar rats (365 days old). Rats received subcutaneous Hcy (0.03 μmol/g body weight) twice daily for 30 days, followed by euthanasia, blood collection and heart dissection 12 h after the last injection. Results revealed increased dichlorofluorescein (DCF) levels in the heart and serum, alongside decreased antioxidant enzyme activities (superoxide dismutase, catalase, glutathione peroxidase), reduced glutathione (GSH) content, and diminished acetylcholinesterase (AChE) activity in the heart. Serum butyrylcholinesterase (BuChE) levels also decreased. Furthermore, nuclear factor erythroid 2-related factor 2 (Nrf2) protein content decreased in both cytosolic and nuclear fractions, while cytosolic nuclear factor kappa B (NFκB) p65 increased in the heart. Additionally, interleukins IL-1β, IL-6 and IL-10 showed elevated expression levels in the heart. These findings could suggest a connection between aging and HHcy in CVD. Reduced Nrf2 protein content and impaired antioxidant defenses, combined with inflammatory factors and altered cholinesterases activity, may contribute to understanding the impact of Hcy on cardiovascular dynamics. This study sheds light on the complex interplay between HHcy, oxidative stress, inflammation, and cholinesterases in CVD, providing valuable insights for future research.

High plasma homocysteine level is associated with increased prevalence of the non-remission state in rheumatoid arthritis: Findings from the KURAMA cohort

OBJECTIVES

We aimed to determine the clinical impact of plasma homocysteine levels on disease activity and clinical remission in patients with rheumatoid arthritis (RA).

METHODS

A cross-sectional study was conducted using KURAMA (Kyoto University Rheumatoid Arthritis Management Alliance) database. We enrolled 291 female patients, who were treated in a treat-to-target manner. We measured plasma total homocysteine using a liquid chromatography-tandem mass spectrometry system and collected clinical data including a 28-joint RA disease activity score-erythrocyte sedimentation rate (DAS28-ESR). Clinical remission of disease activity was defined as a DAS28-ESR < 2.6.

RESULTS

In a univariable analysis, the plasma homocysteine concentration was significantly and positively associated with DAS-28-ESR and was higher in the non-remission group than in the remission group. The cutoff value of the plasma homocysteine level was calculated to be 7.9 nmol/mL by the test of the receiver operating characteristic curve analysis. In a multivariable analysis, after adjusting for clinically relevant variables, the high homocysteine level remained a significant positive association for DAS28-ESR (estimate 0.27, P = .0019) and a positive factor for the presence of RA non-remission (odds ratio 2.39, P = .0071).

CONCLUSIONS

Increased plasma homocysteine levels showed a significant positive association with current disease activity and the non-remission state in female patients with RA under treat-to-target treatment. The findings suggest the potential utility of plasma homocysteine as a disease state marker reflecting conditions that are treatment failure and difficult to remission and may provide clinical evidence on the interplay between homocysteine and inflammatory activation in RA.

Inflammation and hypertension: Underlying mechanisms and emerging understandings

Hypertension remains a major contributor to cardiovascular disease (CVD), a leading cause of global death. One of the major insults that drive increased blood pressure is inflammation. While it is the body's defensive response against some homeostatic imbalances, inflammation, when dysregulated, can be very deleterious. In this review, we highlight and discuss the causative relationship between inflammation and hypertension. We critically discuss how the interplay between inflammation and reactive oxygen species evokes endothelial damage and dysfunction, ultimately leading to narrowing and stiffness of blood vessels. This, along with phenotypic switching of the vascular smooth muscle cells and the abnormal increase in extracellular matrix deposition further exacerbates arterial stiffness and noncompliance. We also discuss how hyperhomocysteinemia and microRNA act as links between inflammation and hypertension. The premises we discuss suggest that the blue-sky scenarios for targeting the underlying mechanisms of hypertension necessitate further research.

The association of homocysteine level with the risk of diabetic nephropathy and diabetic retinopathy in NHANES

AIMS

To examine the association of homocysteine (Hcy) with diabetic nephropathy (DN) and diabetic retinopathy (DR) in a representative United States population.

METHODS

This was a cross-sectional study using data from participants in the National Health and Nutrition Examination Survey 2005-2006. Metrics including Hcy level, urinary albumin to creatinine ratio, estimated glomerular filtration rate, and retinopathy grading were collected. Multiple logistic regression models were employed to assess the association of Hcy with DN and DR.

RESULTS

630 participants were included in this study. The Hcy level was significantly higher in those with DN and DR than those without DN and DR. Hcy was associated with an increased risk of DN (OR = 1.31, 95% CI 1.18-1.46; P < 0.001). In the fully adjusted model of DN (model II), compared to participants in quartiles 1 of Hcy, the adjusted ORs for participants in quartiles 2-4 were 1.49 (95% CI 0.52-4.26; P = 0.426), 3.81 (95% CI 1.35-10.73; P = 0.015), and 14.08 (95% CI 3.84-51.66; P = 0.001), respectively. Hcy was also associated with an increased risk of DR (OR = 2.260, 95% CI 1.212-4.216; P = 0.014), but this association was non-significant in the fully adjusted model of DR (model II).

CONCLUSIONS

In diabetic patients, Hcy was associated with increased risk of DN in a non-linear manner. In addition, Hcy was associated with the risk of DR, but the association was attenuated after adjusting for confounders. In the future, Hcy can potentially be used as an early screening indicator for diabetic microvascular complications.

Anti-inflammatory therapy of atherosclerosis: focusing on IKKβ

Chronic low-grade inflammation has been identified as a major contributor in the development of atherosclerosis. Nuclear Factor-κappa B (NF-κB) is a critical transcription factors family of the inflammatory pathway. As a major catalytic subunit of the IKK complex, IκB kinase β (IKKβ) drives canonical activation of NF-κB and is implicated in the link between inflammation and atherosclerosis, making it a promising therapeutic target. Various natural product derivatives, extracts, and synthetic, show anti-atherogenic potential by inhibiting IKKβ-mediated inflammation. This review focuses on the latest knowledge and current research landscape surrounding anti-atherosclerotic drugs that inhibit IKKβ. There will be more opportunities to fully understand the complex functions of IKKβ in atherogenesis and develop new effective therapies in the future.

Nontargeted metabolomics reveals the potential mechanism underlying the association between birthweight and metabolic disturbances

AIMS

The aim of this study was to characterize the metabolites associated with small- and large-gestational-age newborns in maternal and cord blood, and to investigate potential mechanisms underlying the association between birthweight and metabolic disturbances.

RESEARCH DESIGN AND METHODS

We recorded detailed anthropometric data of mother-offspring dyads. Untargeted metabolomic assays were performed on 67 pairs of cord blood and maternal fasting plasma samples including 16 pairs of small-for-gestational (SGA, < 10th percentile) dyads, 28 pairs of appropriate-for-gestational (AGA, approximate 50 percentile) dyads, and 23 pairs of large-for-gestational (LGA, > 90th percentile) dyads. The association of metabolites with newborn birthweight was conducted to screen for metabolites with U-shaped and line-shaped distributions. The association of metabolites with maternal and fetal phenotypes was also performed.

RESULTS

We found 2 types of metabolites that changed in different patterns according to newborn birthweight. One type of metabolite exhibited a "U-shaped" trend of abundance fluctuation in the SGA-AGA-LGA groups. The results demonstrated that cuminaldehyde level was lower in the SGA and LGA groups, and its abundance in cord blood was negatively correlated with maternal BMI (r = -0.352 p = 0.009) and weight gain (r = -0.267 p = 0.043). 2-Methoxy-estradiol-17b 3-glucuronide, which showed enrichment in the SGA and LGA groups, was positively correlated with homocysteine (r = 0.44, p < 0.001) and free fatty acid (r = 0.42, p < 0.001) in maternal blood. Serotonin and 13(S)-HODE were the second type of metabolites, denoted as "line-shaped", which both showed increasing trends in the SGA-AGA-LGA groups in both maternal and cord blood and were both significantly positively correlated with maternal BMI before pregnancy. Moreover, cuminaldehyde, serotonin, 13(S)-HODE and some lipid metabolites showed a strong correlation between maternal and cord blood.

CONCLUSIONS

These investigations demonstrate broad-scale metabolomic differences associated with newborn birthweight in both pregnant women and their newborns. The U-shaped metabolites associated with both the SGA and LGA groups might explain the U-shaped association between birthweight and metabolic dysregulation. The line-shaped metabolites might participate in intrauterine growth regulation. These observations might help to provide new insights into the insulin resistance and the risk of metabolic disturbance of SGA and LGA babies in adulthood and might identify potential new markers for adverse newborn outcomes in pregnant women.

The 677C > T variant in methylenetetrahydrofolate reductase causes morphological and functional cerebrovascular deficits in mice

Vascular contributions to cognitive impairment and dementia (VCID) particularly Alzheimer's disease and related dementias (ADRDs) are increasing; however, mechanisms driving cerebrovascular decline are poorly understood. Methylenetetrahydrofolate reductase (MTHFR) is a critical enzyme in the folate and methionine cycles. Variants in MTHFR, notably 677 C > T, are associated with dementias, but no mouse model existed to identify mechanisms by which MTHFR677C > T increases risk. Therefore, MODEL-AD created a novel knock-in (KI) strain carrying the Mthfr677C > T allele on the C57BL/6J background (Mthfr677C > T) to characterize morphology and function perturbed by the variant. Consistent with human clinical data, Mthfr677C > T mice have reduced enzyme activity in the liver and elevated plasma homocysteine levels. MTHFR enzyme activity is also reduced in the Mthfr677C > T brain. Mice showed reduced tissue perfusion in numerous brain regions by PET/CT as well as significantly reduced vascular density, pericyte number and increased GFAP-expressing astrocytes in frontal cortex. Electron microscopy revealed cerebrovascular damage including endothelial and pericyte apoptosis, reduced luminal size, and increased astrocyte and microglial presence in the microenvironment. Collectively, these data support a mechanism by which variations in MTHFR perturb cerebrovascular health laying the foundation to incorporate our new Mthfr677C > T mouse model in studies examining genetic susceptibility for cerebrovascular dysfunction in ADRDs.

Induction of apoptosis and autosis in cardiomyocytes by the combination of homocysteine and copper via NOX-mediated p62 expression

High levels of homocysteine (Hcy) associated with cardiovascular events are accompanied by increased copper (Cu) concentrations in the blood. Hcy has been shown to promote endothelial dysfunction, whereas the effect of Hcy on cardiomyocytes and the role of Cu in the pathogenesis remain less understood. In the present study, it is demonstrated that the combination of Hcy and Cu²⁺-induced apoptosis and autosis of cardiomyocytes simultaneously, and thus led to cardiac dysfunction in hyperhomocysteinemic rats. These effects were associated with p22^phox activation and NADPH oxidase (NOX)-mediated p62 upregulation. Inhibition of the expression of p22^phox or p62 in cardiomyocytes significantly attenuated Hcy and Cu²⁺-mediated reactive oxygen species (ROS) generation and cell death. Furthermore, interrupting the NOX-p62 axis prevented diastolic dysfunction in hyperhomocysteinemic rats (HcyR). These findings establish that the induction of apoptosis and autosis of cardiomyocytes through stimulating the NOX-p62-signaling pathway constitutes a novel mechanism of Hcy and Cu-induced cardiac dysfunction.

Impaired Folate-Mediated One-Carbon Metabolism in Type 2 Diabetes, Late-Onset Alzheimer's Disease and Long COVID

Impaired folate-mediated one-carbon metabolism (FOCM) is associated with many pathologies and developmental abnormalities. FOCM is a metabolic network of interdependent biosynthetic pathways that is known to be compartmentalized in the cytoplasm, mitochondria and nucleus. Currently, the biochemical mechanisms and causal metabolic pathways responsible for the initiation and/or progression of folate-associated pathologies have yet to be fully established. This review specifically examines the role of impaired FOCM in type 2 diabetes mellitus, Alzheimer's disease and the emerging Long COVID/post-acute sequelae of SARS-CoV-2 (PASC). Importantly, elevated homocysteine may be considered a biomarker for impaired FOCM, which is known to result in increased oxidative-redox stress. Therefore, the incorporation of hyperhomocysteinemia will be discussed in relation to impaired FOCM in each of the previously listed clinical diseases. This review is intended to fill gaps in knowledge associated with these clinical diseases and impaired FOCM. Additionally, some of the therapeutics will be discussed at this early time point in studying impaired FOCM in each of the above clinical disease states. It is hoped that this review will allow the reader to better understand the role of FOCM in the development and treatment of clinical disease states that may be associated with impaired FOCM and how to restore a more normal functional role for FOCM through improved nutrition and/or restoring the essential water-soluble B vitamins through oral supplementation.

Reduction of protein-bound uraemic toxins in plasma of chronic renal failure patients: A systematic review

BACKGROUND

Protein-bound uraemic toxins (PBUTs) accumulate in patients with chronic kidney disease and impose detrimental effects on the vascular system. However, a unanimous consensus on the most optimum approach for the reduction of plasma PBUTs is still lacking.

METHODS

In this systematic review, we aimed to identify the most efficient clinically available plasma PBUT reduction method reported in the literature between 1980 and 2020. The literature was screened for clinical studies describing approaches to reduce the plasma concentration of known uraemic toxins. There were no limits on the number of patients studied or on the duration or design of the studies.

RESULTS

Out of 1274 identified publications, 101 studies describing therapeutic options aiming at the reduction of PBUTs in CKD patients were included in this review. We stratified the studies by the PBUTs and the duration of the analysis into acute (data from a single procedure) and longitudinal (several treatment interventions) trials. Reduction ratio (RR) was used as the measure of plasma PBUTs lowering efficiency. For indoxyl sulphate and p-cresyl sulphate, the highest RR in the acute studies was demonstrated for fractionated plasma separation, adsorption and dialysis system. In the longitudinal trials, supplementation of haemodialysis patients with AST-120 (Kremezin®) adsorbent showed the highest RR. However, no superior method for the reduction of all types of PBUTs was identified based on the published studies.

CONCLUSIONS

Our study shows that there is presently no technique universally suitable for optimum reduction of all PBUTs. There is a clear need for further research in this field.

Current progress on the mechanisms of hyperhomocysteinemia-induced vascular injury and use of natural polyphenol compounds

Cardiovascular disease is one of the most common diseases in the elderly population, and its incidence has rapidly increased with the prolongation of life expectancy. Hyperhomocysteinemia is an independent risk factor for various cardiovascular diseases, including atherosclerosis, and damage to vascular function plays an initial role in its pathogenesis. This review presents the latest knowledge on the mechanisms of vascular injury caused by hyperhomocysteinemia, including oxidative stress, endoplasmic reticulum stress, protein N-homocysteinization, and epigenetic modification, and discusses the therapeutic targets of natural polyphenols. Studies have shown that natural polyphenols in plants can reduce homocysteine levels and regulate DNA methylation by acting on oxidative stress and endoplasmic reticulum stress-related signaling pathways, thus improving hyperhomocysteinemia-induced vascular injury. Natural polyphenols obtained via daily diet are safer and have more practical significance in the prevention and treatment of chronic diseases than traditional drugs.

Causal Effects of Homocysteine, Folate, and Cobalamin on Kidney Function: A Mendelian Randomization Study

Blood homocysteine level and related vitamin levels are associated with various health outcomes. We aimed to assess causal effects of blood homocysteine, folate, and cobalamin on kidney function in the general population by performing Mendelian randomization (MR) analysis. Genetic instruments for blood homocysteine, folate, and cobalamin levels were introduced from a previous genome-wide association (GWAS) meta-analysis of European individuals. Summary-level MR analysis was performed for the estimated glomerular filtration rate (eGFR) from the CKDGen consortium GWAS that included 567,460 European ancestry individuals. For replication, allele-score-based MR was performed with an independent U.K. Biobank cohort of 337,138 individuals of white British ancestry. In summary-level MR for the CKDGen data, high genetically predicted homocysteine levels were significantly associated with low eGFR (per 1 standard deviation, beta for eGFR change -0.95 (-1.21, -0.69) %), supported by pleiotropy-robust MR sensitivity analysis. Genetically predicted high folate levels were significantly associated with high eGFR change (0.86 (0.30, 1.42) %); however, causal estimates from cobalamin were nonsignificant (-0.11 (-0.33, 0.11) %). In the U.K. Biobank data, the results were consistently identified. Therefore, a high blood homocysteine level causally decreases eGFR. Future trials with appropriate homocysteine-lowering interventions may be helpful for the primary prevention of kidney function impairment.

Association of homocysteine with ankylosing spondylitis: a systematic review and meta-analysis

Background

Hyperhomocysteinemia is associated with autoimmune diseases such as ankylosing spondylitis (AS), systemic lupus erythematosus (SLE), and rheumatoid arthritis (RA). Current findings regarding plasma/serum homocysteine (HCY) levels in AS patients are inconsistent. This study aims to systematically evaluate the association between circulating HCY levels and AS.

Methods

Online electronic databases (PubMed, Web of Science, Embase, ScienceDirect, China National Knowledge Infrastructure (CNKI), and Wanfang data) were used to retrieve all relevant articles published up to May 7, 2020. The pooled standardized mean difference (SMD) with 95% confidence interval (CI) was calculated using the random-effect model, Stata16 software.

Results

Nine articles containing 778 AS patients and 522 controls were included in this meta-analysis. No significant differences in HCY levels were found between AS and control groups (pooled SMD = 0.46, 95% CI = − 0.30 to 1.23, P = 0.23). However, subgroup analysis suggested that HCY levels were significantly higher (P < 0.05) in the AS group treated with methotrexate (MTX) compared with the control group. In contrast, HCY levels were significantly (P < 0.05) lower in the AS group receiving anti-TNF-α treatment compared with the control group. No significant differences were detected between HCY levels and disease activity scores (Bath AS disease activity index, BASDAI), and methylenetetrahydrofolate reductase (MTHFR) C677T genotype.

Conclusion

This meta-analysis indicates that HCY levels are similar between AS and controls, and do not correlate with disease activity. However, different medical treatments cause fluctuations of circulating HCY levels in AS patients. Further and larger-scale studies are needed to confirm these findings.

Trial registration

This study was registered at international prospective register of systematic reviews (PROSPERO), registration number: CRD42020184426.

Relationship between the risk factors of cardiovascular disease by testing biochemical markers and young men with erectile dysfunction: a case-control study

Background

Erectile dysfunction (ED) shares common risk factors with cardiovascular disease (CVD), such as diabetes mellitus (DM) and dyslipidemia, but the relationship between the risk factors of CVD in biochemical markers and young men with ED age 20–40 years is not fully clarified.

Methods

A total of 289 ED outpatients (20–40 years old) were allocated under ED group, based on patients’ complaints and physical examinations. According to the frequency matching ratio of 1:4, 1,155 male individuals (20–40 years old) without ED were set as control group. All participants were tested for lipid profiles including total cholesterol (TC), triglyceride (TG), high density lipoprotein (HDL), low density lipoprotein (LDL), blood glucose (BG), homocysteine (HCY), liver function including alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and renal function including uric acid (UA) and creatinine (CR). The study was designed to compare the two groups using an established binary logistic regression analysis model. The ED group was then subdivided into a younger ED group (20–30 years old) and an older ED group (31–40 years old) for further comparisons.

Results

After comparison, no obvious differences were found in medians of age, TC, TG, HDL, HCY, UA, and ALT in the two groups. Median LDL, BG, and CR were significantly higher and AST was much lower in the ED group (P<0.01). In binary logistic regression analysis, odds ratios (OR) for LDL, BG, CR, and AST were 1.279, 1.237, 1.026, and 0.978, respectively. The sensitivity value and specificity value were 43.25% and 72.56%, respectively. The medians of LDL, TG, and TC were higher and HDL was much lower in the older ED group, as compared with the younger group (P<0.05). No significant differences were displayed in medians of other biochemical markers in the above comparisons.

Conclusions

Elevated LDL, BG, and CR were related factors of ED in young men. Lipid profile was significantly different between young men with ED aged 20–30 and 31–40 years.

Epigenetic factors in atherosclerosis: DNA methylation, folic acid metabolism, and intestinal microbiota

Atherosclerosis is a complex disease, influenced by both genetic and non-genetic factors. The most important epigenetic mechanism in the pathogenesis of atherosclerosis is DNA methylation, which involves modification of the gene without changes in the gene sequence. Nutrients involved in one-carbon metabolism interact to regulate DNA methylation, especially folic acid and B vitamins. Deficiencies in folic acid and other nutrients, such as vitamins B6 and B12, can increase homocysteine levels, induce endothelial dysfunction, and accelerate atherosclerotic pathological processes. Supplemented nutrients can improve DNA methylation status, reduce levels of inflammatory factors, and delay the process of atherosclerosis. In this review, the influence of intestinal flora on folate metabolism and epigenetics is also considered.

Polymorphism of MTHFR C677T Gene and the Associations with the Severity of Essential Hypertension in Northern Chinese Population

Objective

Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme of homocysteine metabolism and is closely related to the occurrence of hypertension. The aim of this study was to investigate the polymorphism of the (MTHFR) C677T and the factors influencing the severity of hypertension. Material and Methods. A total of 985 subjects were enrolled to analyze the polymorphisms of the MTHFR C677T gene by polymerase chain reaction (PCR). 306 people with essential hypertension were selected from 985 subjects to estimate the severity of hypertension by the ordinal multivariate logistical regression model.

Results

The frequencies of CC, CT, and TT genotypes were 19.5%, 49.95%, and 30.46%, respectively. The allelic frequency of mutant T was 55.43%. The plasma homocysteine level of the homozygous TT in individuals was significantly higher than in those with CC or CT (P < 0.01). MTHFR677CT genotype, MTHFR677TT genotype, smoking, family history of hypertension, Hcy, and triglycerides (TG) were independent risk factors for the severity of hypertension (OR = 2.29, 2.24, 2.04, 1.81, 1.04, 1.26).

Conclusion

MTHFR gene, smoking, family history of hypertension, Hcy, and triglycerides could be important genetic and high-risk factors of the development of severe hypertension in northern Chinese. These factors will contribute to the identification of high-risk populations of hypertension and facilitate the development of hypertension control strategies.

Carotid intraplaque haemorrhage: pathogenesis, histological classification, imaging methods and clinical value

Vulnerable carotid atherosclerotic plaques are characterised by several risk factors, such as inflammation, neovascularization and intraplaque haemorrhage (IPH). Vulnerable plaques can lead to ischemic events such as stroke. Many studies reported a relationship between IPH, plaque rupture, and ischemic stroke. Histology is the gold standard to evaluate IPH, but it required carotid endarterectomy (CEA) surgery to collect the tissue sample. In this context, several imaging methods can be used as a non-invasive way to evaluate plaque vulnerability and detect IPH. Most imaging studies showed that IPH is associated with plaque vulnerability and stroke, with magnetic resonance imaging (MRI) being the most sensitive and specific to detect IPH as a predictor of ischemic events. These conclusions are however still debated because of the limited number of patients included in these studies; further studies are required to better assess risks associated with different IPH stages. Moreover, IPH is implicated in plaque vulnerability with other risk factors which need to be considered to predict ischemic risk. In addition, MRI sequences standardization is required to compare results from different studies and agree on biomarkers that need to be considered to predict plaque rupture. In these circumstances, IPH detection by MRI could be an efficient clinical method to predict stroke. The goal of this review article is to first describe the pathophysiological process responsible for IPH, its histological detection in carotid plaques and its correlation with plaque rupture. The second part will discuss the benefits and limitations of imaging the carotid plaque, and finally the clinical interest of imaging IPH to predict plaque rupture, focusing on MRI-IPH.

Association of single nucleotide polymorphisms of MTHFR, TCN2, RNF213 with susceptibility to hypertension and blood pressure

Methylenetetrahydrofolate reductase gene (MTHFR), transcobalaminII (TCN2) and ring finger protein 213 (RNF213) are related to homocysteine (Hcy) level and are of great significance for hypertension. We aimed to evaluate the associations of MTHFR (rs1801133, rs1801131, rs9651118), TCN2 (rs117353193) and RNF213 (rs9916351) with hypertension and blood pressure (BP). A total of 953 patients with hypertension and 1103 controls were enrolled. Genotyping was performed by Taqman. Logistic regression analysis indicated that A allele of TCN2 rs117353193 under the dominant model had a significantly protective effect (P=0.045) after adjustment, which showed that AA+GA genotype has a lower risk than GG. Additionally, the average diastolic BP (DBP) (P=0.044) and mean arterial pressure (MAP) (P=0.035) levels were significantly different between genotypes of RNF213 rs9916351. Further pairwise comparison showed that the average systolic BP (SBP) level of the TT genotype carriers were significantly higher than in CC (P=0.024), and the average DBP and MAP levels of the TT genotype carriers were higher than in CT (P=0.044, P=0.012, respectively) and CC (P=0.048, P=0.010, respectively). In the recessive model, the average SBP (P=0.043), DBP (P=0.018) and MAP (P=0.017) levels with the TT genotype carriers were significantly higher than in CT+CC. Multiple linear regression analysis suggested that RNF213 rs9916351 in the recessive model had significant effects on SBP (P=0.025), DBP (P=0.017) and MAP (P=0.010) as a risk factor. However, no associations were observed between MTHFR and hypertension. TCN2 rs117353193 might serve as a protective factor in hypertension, and RNF213 rs9916351 might be a risk factor that is linked to increase BP level in Northeast Chinese population.

Homocysteine and psoriasis

Psoriasis is caused by a complex interplay among the immune system, genetic background, autoantigens, and environmental factors. Recent studies have demonstrated that patients with psoriasis have a significantly higher serum homocysteine (Hcy) level and a higher prevalence of hyperhomocysteinaemia (HHcy). Insufficiency of folic acid and vitamin B₁₂ can be a cause of HHcy in psoriasis. Hcy may promote the immuno-inflammatory process in the pathogenesis of psoriasis by activating Th1 and Th17 cells and neutrophils, while suppressing regulatory T cells. Moreover, Hcy can drive the immuno-inflammatory process by enhancing the production of the pro-inflammatory cytokines in related to psoriasis. Hcy can induce nuclear factor kappa B activation, which is critical in the immunopathogenesis of psoriasis. There may be a link between the oxidative stress state in psoriasis and the effect of HHcy. Hydrogen sulfide (H₂S) may play a protective role in the pathogenesis of psoriasis and the deficiency of H₂S in psoriasis may be caused by HHcy. As the role of Hcy in the pathogenesis of psoriasis is most likely established, Hcy can be a potential therapeutic target for the treatment of psoriasis. Systemic folinate calcium, a folic acid derivative, and topical vitamin B12 have found to be effective in treating psoriasis.

Value of plasma homocysteine to predict stroke, cardiovascular diseases, and new-onset hypertension: A retrospective cohort study

The influences of hyperhomocysteinemia on cardiovascular diseases (CVDs), stroke and new-onset hypertension are unclear. The aim of the study is to explore the associations of homocysteine levels with stroke, CVDs, and new-onset hypertension in Chinese individuals.This retrospective cohort study included outpatients and inpatients from the Department of Geriatrics at Ruijin Hospital affiliated to Shanghai Jiaotong University School of Medicine from January to December 2000. They were divided based on their homocysteine (Hcy) levels in 2000: Q1 (<10 μmol/L), Q2 (10-15 μmol/L), and Q3 (>15 μmol/L) and according to whether they had hypertension at baseline. Information about stroke, mortality and major adverse cardiac events, and newly onset hypertension was gathered in December each year until 2017. The effects of Hcy levels on the risk for stroke and CVDs among all patients, and new-onset hypertension among patients without hypertension at baseline were evaluated.After adjustment for confounders, compared with the Q1 group (Hcy <10 μmol/L), when the Hcy increased to 10 to 15 μmol/L, the risks for stroke, CVDs, and new-onset hypertension significantly increased, and the hazard ratio and 95% confidence interval were 2.02 (1.35-3.05, P = .001), 2.22 (1.32-3.76, P = .003), and 7.20 (4.52-11.48, P < .001), respectively. Hcy improved the predictive capability of traditional risk factors for stroke. The optimal cut-off value of Hcy for predicting stroke was 13.4 μmol/L (sensitivity: 70.9%, specificity: 62.2%).Hcy 10 to 15 μmol/L is significantly associated with the risks for stroke, mortality and major adverse cardiac events, and hypertension. The best cut-off point of Hcy for predicting stroke is 13.4 μmol/L.

Anti-Oxidant and Anti-Endothelial Dysfunctional Properties of Nano-Selenium in vitro and in vivo of Hyperhomocysteinemic Rats

Purpose

Elevation of blood homocysteine (Hcy) level (hyperhomocysteinemia) is a risk factor for cardiovascular disorders and is closely associated with endothelial dysfunction. The present study aims to investigate the protective effect and underlying mechanism of nanoscale selenium (Nano-Se) in Hcy-mediated vascular endothelial cell dysfunction in vitro and in vivo.

Materials and Methods

By incubating vascular endothelial cells with exogenous Hcy and generating hyperhomocysteinemic rat model, the effects of Nano-Se on hyperhomocysteinemia-mediated endothelial dysfunction and its essential mechanisms were investigated.

Results

Nano-Se inhibited Hcy-induced mitochondrial oxidative damage and apoptosis by preventing the downregulation of glutathione peroxidase enzyme 1 and 4 (GPX1, GPX4) in the vascular endothelial cells, thus effectively prevented the vascular damage in vitro and in vivo in the hyperhomocysteinemic rats. Nano-Se possessed similar protective effects but lower toxicity against Hcy in vascular endothelial cells when compared with other forms of Se.

Conclusion

The application of Nano-Se could serve as a novel promising strategy against Hcy-mediated vascular dysfunction with reduced risk of Se toxicity.

Kidney Ischemia-Reperfusion Elicits Acute Liver Injury and Inflammatory Response

Ischemia-reperfusion (IR) is a common risk factor that causes acute kidney injury (AKI). AKI is associated with dysfunction of other organs also known as distant organ injury. The liver function is often compromised in patients with AKI and in animal models. However, the underlying mechanisms are not fully understood. Inflammatory response plays an important role in IR-induced tissue injury. Although increased proinflammatory cytokines have been detected in the kidney and the distant organs after renal IR, their original sources remain uncertain. In the present study, we investigated the acute effect of renal IR on hepatic inflammatory cytokine expression and the mechanism involved. Sprague-Dawley rats that were subjected to renal IR (ischemia for 45 min followed by reperfusion for 1 h or 6 h) had increased plasma levels of creatinine, urea, and transaminases, indicating kidney and liver injuries. There was a significant increase in the expression of proinflammatory cytokine mRNA (MCP-1, TNF-α, IL-6) in the kidney and liver in rats with renal IR. This was accompanied by a significant increase in proinflammatory cytokine protein levels in the plasma, kidney, and liver. Activation of a nuclear transcription factor kappa B (NF-κB) was detected in the liver after renal IR. The inflammatory foci and an increased myeloperoxidase (MPO) activity were detected in the liver after renal IR, indicating hepatic inflammatory response and leukocyte infiltration. These results suggest that renal IR can directly activate NF-κB and induce acute production of proinflammatory cytokines in the liver. Renal IR-induced hepatic inflammatory response may contribute to impaired liver function and systemic inflammation.

Comprehensive epigenome characterization reveals diverse transcriptional regulation across human vascular endothelial cells

Background

Endothelial cells (ECs) make up the innermost layer throughout the entire vasculature. Their phenotypes and physiological functions are initially regulated by developmental signals and extracellular stimuli. The underlying molecular mechanisms responsible for the diverse phenotypes of ECs from different organs are not well understood.

Results

To characterize the transcriptomic and epigenomic landscape in the vascular system, we cataloged gene expression and active histone marks in nine types of human ECs (generating 148 genome-wide datasets) and carried out a comprehensive analysis with chromatin interaction data. We developed a robust procedure for comparative epigenome analysis that circumvents variations at the level of the individual and technical noise derived from sample preparation under various conditions. Through this approach, we identified 3765 EC-specific enhancers, some of which were associated with disease-associated genetic variations. We also identified various candidate marker genes for each EC type. We found that the nine EC types can be divided into two subgroups, corresponding to those with upper-body origins and lower-body origins, based on their epigenomic landscape. Epigenomic variations were highly correlated with gene expression patterns, but also provided unique information. Most of the deferentially expressed genes and enhancers were cooperatively enriched in more than one EC type, suggesting that the distinct combinations of multiple genes play key roles in the diverse phenotypes across EC types. Notably, many homeobox genes were differentially expressed across EC types, and their expression was correlated with the relative position of each organ in the body. This reflects the developmental origins of ECs and their roles in angiogenesis, vasculogenesis and wound healing.

Conclusions

This comprehensive analysis of epigenome characterization of EC types reveals diverse transcriptional regulation across human vascular systems. These datasets provide a valuable resource for understanding the vascular system and associated diseases.

Hyperhomocysteinemia and myocardial remodeling in the sand rat, Psammomys obesus

OBJECTIVE

Numerous studies have shown that a methionine-rich diet induces hyperhomocysteinemia (Hhcy), a risk factor for cardiovascular diseases. The objective of the present study was to determine the involvement of Hhcy in cardiac remodeling in the sand rat Psammomys obesus.

MATERIALS AND METHODS

An experimental Hhcy was induced, in the sand rat Psammomys obesus, by intraperitoneal injection of 300 mg/kg of body weight/day of methionine for 1 month. The impact of Hhcy on the cellular and matricial structures of the myocardium was analyzed with histological techniques (Masson trichrome and Sirius red staining). Immunohistochemistry allowed us to analyze several factors involved in myocardial remodeling, such as fibrillar collagen I and III, metalloproteases (MMP-2 and -9) and their inhibitors (TIMP-1 and -2), TGF-β1 and activated caspase 3.

RESULTS

Our results show that Hhcy induced by an excess of methionine causes, in the myocardium of Psammomys obesus, a significant accumulation of fibrillar collagens I and III at the interstitial and perivascular scales, indicating the appearance of fibrosis, which is associated with an immuno-expression increase of TGF-β1, MMP-9 and TIMP-2 and an immuno-expression decrease of MMP-2 and TIMP-1. Also, Hhcy induces apoptosis of some cardiomyocytes and cardiac fibroblasts by increasing of activated caspase 3 expression. These results highlight a remodeling of cardiac tissue in hyperhomocysteinemic Psammomys obesus.

Metabolomics reveals a link between homocysteine and lipid metabolism and leukocyte telomere length: the ENGAGE consortium

Telomere shortening has been associated with multiple age-related diseases such as cardiovascular disease, diabetes, and dementia. However, the biological mechanisms responsible for these associations remain largely unknown. In order to gain insight into the metabolic processes driving the association of leukocyte telomere length (LTL) with age-related diseases, we investigated the association between LTL and serum metabolite levels in 7,853 individuals from seven independent cohorts. LTL was determined by quantitative polymerase chain reaction and the levels of 131 serum metabolites were measured with mass spectrometry in biological samples from the same blood draw. With partial correlation analysis, we identified six metabolites that were significantly associated with LTL after adjustment for multiple testing: lysophosphatidylcholine acyl C17:0 (lysoPC a C17:0, p-value = 7.1 × 10⁻⁶), methionine (p-value = 9.2 × 10⁻⁵), tyrosine (p-value = 2.1 × 10⁻⁴), phosphatidylcholine diacyl C32:1 (PC aa C32:1, p-value = 2.4 × 10⁻⁴), hydroxypropionylcarnitine (C3-OH, p-value = 2.6 × 10⁻⁴), and phosphatidylcholine acyl-alkyl C38:4 (PC ae C38:4, p-value = 9.0 × 10⁻⁴). Pathway analysis showed that the three phosphatidylcholines and methionine are involved in homocysteine metabolism and we found supporting evidence for an association of lipid metabolism with LTL. In conclusion, we found longer LTL associated with higher levels of lysoPC a C17:0 and PC ae C38:4, and with lower levels of methionine, tyrosine, PC aa C32:1, and C3-OH. These metabolites have been implicated in inflammation, oxidative stress, homocysteine metabolism, and in cardiovascular disease and diabetes, two major drivers of morbidity and mortality.

Catalpol Inhibits Homocysteine-induced Oxidation and Inflammation via Inhibiting Nox4/NF-κB and GRP78/PERK Pathways in Human Aorta Endothelial Cells

Hyperhomocysteinemia (HHCY) has been recognized as an independent risk factor for atherosclerosis and plays a vital role in the development of atherosclerosis. Catalpol, an iridoid glucoside extracted from the root of Rehmannia glutinosa, can produce anti-inflammatory, anti-oxidant, anti-tumor, and dopaminergic neurons protecting effects. This study aimed to determine the protecting effects of catalpol against homocysteine (HCY)-induced injuries in human aortic endothelial cells (HAECs) and uncover the underlying mechanisms: 1. HAECs were cultured with different concentrations of HCY (3 mM) and catalpol (7.5 μΜ, 15 μΜ, 30 μΜ) for 24 h. (1) The level of MDA and GSH as well as LDH release was measured with colorimetric assay. (2) Reactive oxygen species (ROS) were detected by flow cytometry analysis. (3) Western blotting analysis was performed to detect the expression of Nox4, p22^phox, ICAM-1, MCP-1, VCAM-1, IκB, nucleus p65, p65 phosphorylation, caspase-3, −9, bax, bcl-2, and ER stress-related proteins. (4) The expressions of CHOP, ATF4 were measured by qRT-PCR. (5) Mitochondrial membrane potential in HCY-treated HAECs was measured by rhodamine 123 staining, and the samples were observed by confocal laser scanning microscopy. 2. DPI, PDTC, and TUDCA were used to determine the interaction among Nox4/ROS, NF-κB, and endoplasmic reticulum stress. 3. TUDCA or Nox4 siRNA were used to investigate whether the effect of catalpol inhibiting the over-production of ROS were associated with inhibiting ER stress and Nox4 expression. Catalpol significantly suppressed LDH release, MDA level, and the reduction of GSH. Catalpol reduced HCY-stimulated ROS over-generation, inhibited the NF-κB transcriptional activation as well as the protein over-expressions of Nox4, ICAM-1, VCAM-1, and MCP-1. Catalpol elevated bcl-2 protein expression and reduced bax, caspase-3, −9 protein expressions in the HCY-treated HAECs. Simultaneously, catalpol could also inhibit the activation of ER stress-associated sensors GRP78, IRE1α, ATF6, P-PERK, P-eIF2α, CHOP, and ATF4 induced by HCY. In addition, the extent of catalpol inhibiting ROS over-generation and NF-κB signaling pathway was reduced after inhibiting Nox4 or ER stress with DPI or TUDCA. The inhibitor of NF-κB PDTC also reduced the effects of catalpol inhibiting the expressions of Nox4 and GRP78. Furthermore, the effect of catalpol inhibiting the over-generation of ROS was reduced by Nox4 siRNA. Catalpol could ameliorate HCY-induced oxidation, cells apoptosis and inflammation in HAECs possibly by inhibiting Nox4/NF-κB and ER stress.

Hydrogen Sulfide Protects Hyperhomocysteinemia-Induced Renal Damage by Modulation of Caveolin and eNOS Interaction

The accumulation of homocysteine (Hcy) during chronic kidney failure (CKD) can exert toxic effects on the glomeruli and tubulo-interstitial region. Among the potential mechanisms, the formation of highly reactive metabolite, Hcy thiolactone, is known to modify proteins by N-homocysteinylation, leading to protein degradation, stress and impaired function. Previous studies documented impaired nitric oxide production and altered caveolin expression in hyperhomocysteinemia (HHcy), leading to endothelial dysfunction. The aim of this study was to determine whether Hhcy homocysteinylates endothelial nitric oxide synthase (eNOS) and alters caveolin-1 expression to decrease nitric oxide bioavailability, causing hypertension and renal dysfunction. We also examined whether hydrogen sulfide (H₂S) could dehomocysteinylate eNOS to protect the kidney. WT and Cystathionine β-Synthase deficient (CBS+/-) mice representing HHcy were treated without or with sodium hydrogen sulfide (NaHS), a H₂S donor (30 µM), in drinking water for 8 weeks. Hhcy mice (CBS+/-) showed low levels of plasma H₂S, elevated systolic blood pressure (SBP) and renal dysfunction. H₂S treatment reduced SBP and improved renal function. Hhcy was associated with homocysteinylation of eNOS, reduced enzyme activity and upregulation of caveolin-1 expression. Further, Hhcy increased extracellular matrix (ECM) protein deposition and disruption of gap junction proteins, connexins. H₂S treatment reversed the changes above and transfection of triple genes producing H₂S (CBS, CSE and 3MST) showed reduction of vascular smooth muscle cell proliferation. We conclude that during Hhcy, homocysteinylation of eNOS and disruption of caveolin-mediated regulation leads to ECM remodeling and hypertension, and H₂S treatment attenuates renovascular damage.

Folic Acid and Vitamin B12 Administration in CKD, Why Not?

Patients affected by chronic kidney disease (CKD) or end-stage renal disease (ESRD) experience a huge cardiovascular risk and cardiovascular events represent the leading causes of death. Since traditional risk factors cannot fully explain such increased cardiovascular risk, interest in non-traditional risk factors, such as hyperhomocysteinemia and folic acid and vitamin B12 metabolism impairment, is growing. Although elevated homocysteine blood levels are often seen in patients with CKD and ESRD, whether hyperhomocysteinemia represents a reliable cardiovascular and mortality risk marker or a therapeutic target in this population is still unclear. In addition, folic acid and vitamin B12 could not only be mere cofactors in the homocysteine metabolism; they may have a direct action in determining tissue damage and cardiovascular risk. The purpose of this review was to highlight homocysteine, folic acid and vitamin B12 metabolism impairment in CKD and ESRD and to summarize available evidences on hyperhomocysteinemia, folic acid and vitamin B12 as cardiovascular risk markers, therapeutic target and risk factors for CKD progression.

Innate Immune Signaling and Its Role in Metabolic and Cardiovascular Diseases

The innate immune system is an evolutionarily conserved system that senses and defends against infection and irritation. Innate immune signaling is a complex cascade that quickly recognizes infectious threats through multiple germline-encoded cell surface or cytoplasmic receptors and transmits signals for the deployment of proper countermeasures through adaptors, kinases, and transcription factors, resulting in the production of cytokines. As the first response of the innate immune system to pathogenic signals, inflammatory responses must be rapid and specific to establish a physical barrier against the spread of infection and must subsequently be terminated once the pathogens have been cleared. Long-lasting and low-grade chronic inflammation is a distinguishing feature of type 2 diabetes and cardiovascular diseases, which are currently major public health problems. Cardiometabolic stress-induced inflammatory responses activate innate immune signaling, which directly contributes to the development of cardiometabolic diseases. Additionally, although the innate immune elements are highly conserved in higher-order jawed vertebrates, lower-grade jawless vertebrates lack several transcription factors and inflammatory cytokine genes downstream of the Toll-like receptors (TLRs) and retinoic acid-inducible gene-I (RIG-I)-like receptors (RLRs) pathways, suggesting that innate immune signaling components may additionally function in an immune-independent way. Notably, recent studies from our group and others have revealed that innate immune signaling can function as a vital regulator of cardiometabolic homeostasis independent of its immune function. Therefore, further investigation of innate immune signaling in cardiometabolic systems may facilitate the discovery of new strategies to manage the initiation and progression of cardiometabolic disorders, leading to better treatments for these diseases. In this review, we summarize the current progress in innate immune signaling studies and the regulatory function of innate immunity in cardiometabolic diseases. Notably, we highlight the immune-independent effects of innate immune signaling components on the development of cardiometabolic disorders.

Effect of homocysteine on pregnancy: A systematic review

Research purpose was to put together the available pieces of present scientific data and to close the gap in the knowledge of Hcy levels in pregnancy and its association with some pregnancy complications. Scientific data were taken from research papers published between January 1990 and December 2017, and found on the Internet (PubMed, ClinicalKey and Embase databases) by the following tags entered in English, Russian, French and German languages: pregnancy, homocysteine, pregnancy complications, pregnancy loss, preeclampsia, intrauterine growth restriction, and placental abruption. The review showed that Hcy levels range in uncomplicated pregnancy. Upon that, Hcy level tends to decrease during the second and third trimesters. Some studies have revealed a link between polymorphism and abortion. Sufficient data were obtained indicating the relationship between HHcy and PE. Placental abruption was also associated with high Hcy levels increasing the risk 5.3-fold, but still there are data not supporting the hypothesis that Hcy levels correlate with placental abruption.

Murine models of vascular endothelial injury: Techniques and pathophysiology

Vascular endothelial injury (VEI) triggers pathological processes in various cardiovascular diseases, such as coronary heart disease and hypertension. To further elucidate the in vivo pathological mechanisms of VEI, many animal models have been established. For the easiness of genetic manipulation and feeding, murine models become most commonly applied for investigating VEI. Subsequently, countless valuable information concerning pathogenesis has been obtained and therapeutic strategies for VEI have been developed. This review will highlight some typical murine VEI models from the perspectives of pharmacological intervention, surgery and genetic manipulation. The techniques, pathophysiology, advantages, disadvantages and the experimental purpose of each model will also be discussed.

Melatonin attenuates homocysteine-induced injury in human umbilical vein endothelial cells

Homocysteine (Hcy) is a major risk factor for vascular disease and is closely associated with endothelial dysfunction. Melatonin is a neurohormone that is mostly produced by the pineal gland. Studies have reported that melatonin exhibits neuroprotective effects in several neurodegenerative disorders. The aim of the current study was to investigate the possible protective effect of melatonin against Hcy-induced endothelial cell apoptosis in human umbilical vein endothelial cells (HUVECs) and to explore the underlying mechanisms. HUVECs were exposed to Hcy in the presence or absence of melatonin. The effect of melatonin on viability was examined by MTT assay. Intracellular reactive oxygen species (ROS) levels were determined by 2',7'-dichlorofluorescein diacetate (DCF-DA). Further, expression of Bax, Bcl-2, and caspase-3 was analyzed by Western blot analysis. Lipid peroxidation (LPO) levels, total antioxidant power (TAP), and total thiol molecules were also evaluated. The results of this study revealed that melatonin significantly prevented Hcy-induced loss in cell viability in HUVECs. It was found that ROS significantly increased in the presence of Hcy, whereas melatonin reduced ROS production. Melatonin also downregulated Bax, upregulated Bcl-2, and decreased the expression and activity of caspase-3. Hcy increased the levels of LPO, and this effect was significantly attenuated by melatonin. Melatonin also increased the levels of TAP and total thiol molecules. It was concluded that melatonin played a protective role against Hcy-induced endothelium cell apoptosis through inhibition of ROS accumulation and the mitochondrial-dependent apoptotic pathway.

Homocysteine‑induced oxidative stress through TLR4/NF‑κB/DNMT1‑mediated LOX‑1 DNA methylation in endothelial cells

Atherosclerosis (AS) is a progressive disease of multifactorial origin, which occurs in response to endothelial injury. Increased homocysteine (Hcy) is considered a major cause of endothelial dysfunction, oxidative stress and DNA methylation; however, the mechanisms remain to be fully elucidated. The aim of the present study was to investigate whether Hcy causes injury to endothelial cells (ECs) by the effect of lectin‑like oxidized‑low density lipoprotein receptor‑1 (LOX‑1) DNA methylation through toll‑like receptor 4(TLR4)/nuclear factor (NF)‑κB/DNA methyltransferase (DNMT)1. The ECs were treated with different concentrations of Hcy, and it was found that Hcy promoted the expression of TLR4, leading to EC injury. The effect of oxidative stress was analyzed by measuring superoxide dismutase, malondialdehyde and hydrogen peroxide in the ECs. In addition, the association between NF‑κB and DNMT1 was examined by treatment of the ECs with pyrrolidine dithiocarbamate (PDTC). The results suggested that Hcy induced LOX‑1 DNA hypomethyaltion to promote the expression levels of LOX‑1. Taken together, Hcy injured the ECs through the effect of methylation and trans‑sulfuration metabolism of LOX‑1 through TLR4/NF‑κB/DNMT1. Following injury to the ECs, lipids, particularly ox‑LDL, accumulated in the sub‑endothelial layer to promote the formation of AS.

Hyperhomocysteinaemia and vascular injury: advances in mechanisms and drug targets

Homocysteine is a sulphur-containing non-proteinogenic amino acid. Hyperhomocysteinaemia (HHcy), the pathogenic elevation of plasma homocysteine as a result of an imbalance of its metabolism, is an independent risk factor for various vascular diseases, such as atherosclerosis, hypertension, vascular calcification and aneurysm. Treatments aimed at lowering plasma homocysteine via dietary supplementation with folic acids and vitamin B are more effective in preventing vascular disease where the population has a normally low folate consumption than in areas with higher dietary folate. To date, the mechanisms of HHcy-induced vascular injury are not fully understood. HHcy increases oxidative stress and its downstream signalling pathways, resulting in vascular inflammation. HHcy also causes vascular injury via endoplasmic reticulum stress. Moreover, HHcy up-regulates pathogenic genes and down-regulates protective genes via DNA demethylation and methylation respectively. Homocysteinylation of proteins induced by homocysteine also contributes to vascular injury by modulating intracellular redox state and altering protein function. Furthermore, HHcy-induced vascular injury leads to neuronal damage and disease. Also, an HHcy-activated sympathetic system and HHcy-injured adipose tissue also cause vascular injury, thus demonstrating the interactions between the organs injured by HHcy. Here, we have summarized the recent developments in the mechanisms of HHcy-induced vascular injury, which are further considered as potential therapeutic targets in this condition.

LINKED ARTICLES

This article is part of a themed section on Spotlight on Small Molecules in Cardiovascular Diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.8/issuetoc.

Echinocystic acid ameliorates hyperhomocysteinemia-induced vascular endothelial cell injury through regulating NF-κB and CYP1A1

The present study investigated the role of echinocystic acid (EA) on the expression of nuclear factor (NF)-κB and cytochrome P450 1A1 (CYP1A1), and aortic morphology, in a rat model of hyperhomocysteinemia (Hhcy). A total of 50 Sprague Dawley rats were randomly divided into five groups as follows: Normal control (NC), model control (MC), vitamin control (VC; folic acid 1 mg/kg + vitamin B2 2 mg/kg + vitamin B12 10u g/kg), EA1 (20 mg/kg EA) and EA2 (40 mg/kg EA). Plasma homocysteine (Hcy) levels were determined via high performance liquid chromatography, and the morphology of the aorta was investigated using hematoxylin and eosin staining. Furthermore, aortic mRNA and protein levels of NF-κB and CYP1A1 were measured using reverse transcription-quantitative polymerase chain reaction analysis and western blotting, respectively. Plasma Hcy levels, and aortic mRNA and protein levels of NF-κB and CYP1A1, were significantly lower in the EA-treated group compared with the MC group (all P<0.05). However, the aortic morphology remained normal, including the endothelial cells of the inner layer, and smooth muscle cells of the media layer and adventitia. In conclusion, the results of the present study indicate that EA has a protective role on vascular endothelial cells in Hhcy through decreasing plasma Hcy, and thus NF-κB and CYP1A1 expression.

Folic Acid and Homocysteine in Chronic Kidney Disease and Cardiovascular Disease Progression: Which Comes First?

Background

Hyperhomocysteinemia (Hhcy) occurs in about 85% of chronic kidney disease (CKD) patients because of impaired renal metabolism and reduced renal excretion. Folic acid (FA), the synthetic form of vitamin B₉, is critical in the conversion of homocysteine (Hcy) to methionine. If there is not enough intake of FA, there is not enough conversion, and Hcy levels are raised.

Summary

Hhcy is regarded as an independent predictor of cardiovascular morbidity and mortality in end-stage renal disease. Hhcy exerts its pathogenic action on the main processes involved in the progression of vascular damage. Research has shown Hhcy suggests enhanced risks for inflammation and endothelial injury which lead to cardiovascular disease (CVD), stroke, and CKD. FA has also been shown to improve endothelial function without lowering Hcy, suggesting an alternative explanation for the effect of FA on endothelial function. Recently, the role of FA and Hhcy in CVD and in CKD progression was renewed in some randomized trials.

Key Messages

In the general population and in CKD patients, it remains a topic of discussion whether any beneficial effects of FA therapy are to be referred to its direct effect or to a reduction of Hhcy. While waiting for the results of confirmatory trials, it is reasonable to consider FA with or without methylcobalamin supplementation as appropriate adjunctive therapy in patients with CKD.

T-cell subsets are associated with serum homocysteine concentration in patients with essential hypertension

OBJECTIVE

To explore the association between serum homocysteine (Hcy) concentration and T-cell subsets from patients with essential hypertension.

PATIENTS AND METHODS

A total of 218 essential hypertension patients were recruited, of which 170 were H-type essential hypertensive and 48 were non-H-type essential hypertensive. H-type essential hypertensive patients were divided into three groups by concentration of serum Hcy. The peripheral blood T-cell subsets (CD3⁺%, CD4⁺%, CD8⁺ T%, CD4⁺/CD8⁺) and clinical features including age, sex, serum creatinine, uric acid, total cholesterol, triglycerides, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol were recorded and analyzed with T-cell subsets which were counted by fluorescence activated cytometry.

RESULTS

Compared with non-H-type hypertensive patients, CD4⁺ T-cell percentage in peripheral blood was significantly decreased in H-type hypertensive patients. Because of the increase of Hcy level, CD4⁺ T-cell percentage decreased. Linear regression analysis showed that Hcy level was negatively correlated with CD4⁺ T-cell percentage; however, it was positively correlated with CD3⁺ T-cell percentage.

CONCLUSION

A direct association between serum Hcy concentrations and T-cell percentage was observed in patients with essential hypertension. This observation indicates that T-cell subsets might play an important role in hypertension.

Hypermethylation: Causes and Consequences in Skeletal Muscle Myopathy

A detrimental consequence of hypermethylation is hyperhomocysteinemia (HHcy), that causes oxidative stress, inflammation, and matrix degradation, which leads to multi-pathology in different organs. Although, it is well known that hypermethylation leads to overall gene silencing and hypomethylation leads to overall gene activation, the role of such process in skeletal muscle dysfunction during HHcy condition is unclear. In this study, we emphasized the multiple mechanisms including epigenetic alteration by which HHcy causes skeletal muscle myopathy. This review also highlights possible role of methylation, histone modification, and RNA interference in skeletal muscle dysfunction during HHcy condition and potential therapeutic molecules, putative challenges, and methodologies to deal with HHcy mediated skeletal muscle dysfunction. We also highlighted that B vitamins (mainly B12 and B6), with folic acid supplementation, could be useful as an adjuvant therapy to reverse these consequences associated with this HHcy conditions in skeletal muscle. However, we would recommend to further study involving long-term trials could help to assess efficacy of the use of these therapeutic agents. J. Cell. Biochem. 118: 2108-2117, 2017. © 2017 Wiley Periodicals, Inc.

Demethylation treatment restores erectile function in a rat model of hyperhomocysteinemia

Methylation modification is an important cellular mechanism of gene expression regulation. Dimethylarginine dimethylaminohydrolase-2 (DDAH-2) protein is a pivotal molecular for endothelium function. To explore the effects of 5-aza-deoxycytidine (5-aza), a demethylation agent, in hyperhomocysteinemia (hhcy)-related erectile dysfunction (ED) rats, 5-aza (1 mg kg⁻¹) was administrated to Sprague-Dawley hhcy-rats induced by supplemented methionine chow diet. Erectile function, nitric oxide-cyclic guanosine monophosphate (NO-cGMP) levels, expression of DDAH-2 protein and promoter methylation status of DDAH-2 were studied in the corpora cavernosa. We found that supplemented methionine diet induced a high homocysteine level after 6 weeks of treatment. DDAH-2 protein was down-regulated in the corpora cavernosa while the administration of 5-aza up-regulated DDAH-2 expression and restored erectile function. The methionine-fed rats showed high methylation levels of DDAH-2 promoter region while the group treated with 5-aza demonstrated lower-methylation levels when compared to the methionine-fed group. Besides, the administration of 5-aza improved NO and cGMP levels in methionine-fed rats. Therefore, the methylation mechanism involves in ED pathogenesis, and demethylation offers a potential new strategy for ED treatment.

Elevated serum homocysteine level as an independent risk factor for erectile dysfunction: a prospective pilot case-control study

Homocysteine is an amino acid that is produced from the metabolic demethylation of dietary methionine. It has gained arising attention for its association with increased risk of myocardial infarction, stroke and venous thromboembolism. Erectile dysfunction (ED), especially for vasculogenic ED, is a vascular disorder of cavernosal vascular bed. In this prospective pilot case-control study, we investigated plasma homocysteine levels in 32 ED patients and 20 healthy control men. Related patients characteristics including age, weight, height, marital status, smoking and drinking status, level of education were collected and analysed as well as penile colour Doppler ultrasound parameters. ED patients were further categorised into mild, moderate and severe ED based on 5-item of the International Index of Erectile Function. Higher homocysteine levels were observed in ED patients as compared with controls (p < .05). A multivariate logistic regression with likelihood ratio test revealed that homocysteine and penile peak systolic blood flow velocity (PSV) levels posed significant indicators for ED (chi-square of likelihood ratio = 20.42, df = 2, p < .005) as well as moderate and severe ED occurrence (chi-square of likelihood ratio = 28.50, df = 2, p < .005). The threshold value of homocysteine concentration to discriminate ED and control subjects was 12.65 μmol/L by performing receiver operating characteristic curve analyses. These data suggested that elevation of homocysteine levels was associated with an increased risk of ED.

Is there a causal role for homocysteine concentration in blood pressure? A Mendelian randomization study

BACKGROUND

An understanding of whether homocysteine is a cause or a marker of increased blood pressure is relevant because blood homocysteine can be effectively lowered by safe and inexpensive interventions (e.g., vitamin B-6, B-9, and B-12 supplementation).

OBJECTIVE

The aim was to assess the causal influence of homocysteine on systolic and diastolic blood pressure (SBP and DBP, respectively) in adults with the use of Mendelian randomization (MR).

DESIGN

Data from the 1982 Pelotas Birth Cohort (Brazil) were used. A total of 4297 subjects were evaluated in 2004-2005 (mean age: 22.8 y). The association of homocysteine concentration with SBP and DBP was assessed by conventional ordinary least-squares (OLS) linear regression and 2-stage least-squares (2SLS) regression (MR analysis). The single nucleotide polymorphism (SNP) methylenetetrahydrofolate reductase (MTHFR) C677T (rs1801133) was used as proxy for homocysteine concentration. We also applied MR to data from the International Consortium for Blood Pressure (ICBP) genomewide association studies (>69,000 participants) using rs1801133 and additional homocysteine-associated SNPs as instruments.

RESULTS

In OLS regression, a 1-SD unit increase in log homocysteine concentration was associated with an increase of 0.9 (95% CI: 0.4, 1.4) mm Hg in SBP and of 1.0 (95% CI: 0.6, 1.4) mm Hg in DBP. In 2SLS regression, for the same increase in homocysteine, the coefficients were -1.8 mm Hg for SBP (95% CI: -3.9, 0.4 mm Hg; P = 0.01) and 0.1 mm Hg for DBP (95% CI: -1.5, 1.7 mm Hg; P = 0.24). In the MR analysis of ICBP data, homocysteine concentration was not associated with SBP (β = 0.6 mm Hg for each 1-SD unit increase in log homocysteine; 95% CI: -0.8, 1.9 mm Hg) but was positively associated with DBP (β = 1.1 mm Hg; 95% CI: 0.2, 1.9 mm Hg). The association of genetically increased homocysteine with DBP was not consistent across different SNPs.

CONCLUSION

Overall, the present findings do not corroborate the hypothesis that homocysteine has a causal role in blood pressure, especially in SBP.

Adropin is associated with hyperhomocysteine and coronary atherosclerosis

Homocysteine has been recognized as a risk factor for atherosclerosis and cardiovascular diseases. Adropin is a newly-identified energy homeostasis protein with a potential protective effect against coronary artery disease (CAD). This study attempted to measure the correlation between serum homocysteine and adropin levels in patients with CAD, and to ascertain how the two hormones could affect the severity of coronary atherosclerosis. A cohort of CAD patients who had undergone coronary angiography was prospectively recruited. The serum homocysteine and adropin levels of the patients were measured and the severity of coronary atherosclerosis was quantified with the SYNTAX score. The data were analyzed with a generalized structural equation model. In total, 170 consecutive patients were recruited with a mean serum homocysteine level of 15.9±8.3 µmol/l, and 76 (44.7%) patients were identified as hyperhomocysteinemic with a serum homocysteine level >15 µmol/l. Serum homocysteine level was found to be significantly negatively correlated with serum adropin level (r=-0.169, P=0.028). Patients with hyperhomocysteinemia had lower serum adropin levels and higher SYNTAX scores than patients without hyperhomocysteinemia. Further analysis with a generalized structural equation model showed that adropin was significantly associated with hyperhomocysteinemia (adjusted odds ratio: 0.95, 95% confidence interval: 0.93 to 0.98; P=0.002), which in turn was significantly associated with the SYNTAX score (coefficient: 4.71, 95% confidence interval: 1.39 to 8.03; P=0.005). In conclusion, the serum homocysteine level was inversely correlated with the serum adropin level in patients with CAD. A low serum adropin level was associated with hyperhomocysteinemia and more severe coronary atherosclerosis, as reflected by a higher SYNTAX score.

Endothelial dysfunction: the link between homocysteine and hydrogen sulfide

High level of homocysteine (hyperhomocysteinemia, HHcy) is associated with increased risk for vascular disease. Evidence for this emerges from epidemiological studies which show that HHcy is associated with premature peripheral, coronary artery and cerebrovascular disease independent of other risk factors. Possible mechanisms by which homocysteine causes vascular injury include endothelial injury, DNA dysfunction, proliferation of smooth muscle cells, increased oxidative stress, reduced activity of glutathione peroxidase and promoting inflammation. HHcy has been shown to cause direct damage to endothelial cells both in vitro and in vivo. Clinically, this manifests as impaired flow-mediated vasodilation and is mainly due to a reduction in nitric oxide synthesis and bioavailability. The effect of impaired nitric oxide release can in turn trigger and potentiate atherothrombogenesis and oxidative stress. Endothelial damage is a crucial aspect of atherosclerosis and precedes overt manifestation of disease. In addition, endothelial dysfunction is also associated with hypertension, diabetes, ischemia reperfusion injury and neurodegenerative diseases. Homocysteine is a precursor of hydrogen sulfide (H2S) which is formed by transulfuration process catalyzed by the enzymes, cystathionine β-synthase and cystathionine γ-lyase. H2S is a gasotransmitter that has emerged recently as a novel mediator in cardiovascular homeostasis. As a potent vasodilator, it plays several roles which include regulation of vessel diameter, protection of endothelium from redox stress, ischemia reperfusion injury and chronic inflammation. However, the precise mechanism by which it mediates these beneficial effects is complex and still remains unclear. Current evidence indicates H2S modulates cellular functions by a variety of intracellular signaling processes. In this review, we summarize the mechanisms of HHcy-induced endothelial dysfunction and the metabolism and physiological functions of H2S as a protective agent.

The role of homocysteine-lowering B-vitamins in the primary prevention of cardiovascular disease

Cardiovascular disease (CVD) is the leading cause of mortality in the Western world. The effort of research should aim at the primary prevention of CVD. Alongside statin therapy, which is maintained to be an effective method of CVD prevention, there are alternative methods such as vitamin B substitution therapy with folic acid (FA), and vitamins B12 and B6 . B-vitamins may inhibit atherogenesis by decreasing the plasma level of homocysteine (Hcy)-a suspected etiological factor for atherosclerosis-and by other mechanisms, primarily through their antioxidant properties. Although Hcy-lowering vitamin trials have failed to demonstrate beneficial effects of B-vitamins in the prevention of CVD, a meta-analysis and stratification of a number of large vitamin trials have suggested their effectiveness in cardiovascular prevention (CVP) in some aspects. Furthermore, interpretation of the results from these large vitamin trials has been troubled by statin/aspirin therapy, which was applied along with the vitamin substitution, and FA fortification, both of which obscured the separate effects of vitamins in CVP. Recent research results have accentuated a new approach to vitamin therapy for CVP. Studies undertaken with the aim of primary prevention have shown that vitamin B substitution may be effective in the primary prevention of CVD and may also be an option in the secondary prevention of disease if statin therapy is accompanied by serious adverse effects. Further investigations are needed to determine the validity of vitamin substitution therapy before its introduction in the protocol of CVD prevention.

Cardiovascular risk in pediatric-onset rheumatological diseases

Cardiovascular morbidity and mortality are becoming major health concerns for adults with inflammatory rheumatic diseases. The enhanced atherogenesis in this patient population is promoted by the exposure to traditional risk factors as well as nontraditional cardiovascular insults, such as corticosteroid therapy, chronic inflammation and autoantibodies. Despite definite differences between many adult-onset and pediatric-onset rheumatologic diseases, it is extremely likely that atherosclerosis will become the leading cause of morbidity and mortality in this pediatric patient population. Because cardiovascular events are rare at this young age, surrogate measures of atherosclerosis must be used. The three major noninvasive vascular measures of early atherosclerosis--namely, flow-mediated dilatation, carotid intima-media thickness and pulse wave velocity--can be performed easily on children. Few studies have explored the prevalence of cardiovascular risk factors and even fewer have used the surrogate vascular measures to document signs of early atherosclerosis in children with pediatric-onset rheumatic diseases. The objective of this review is to provide an overview on cardiovascular risk and early atherosclerosis in pediatric-onset systemic lupus erythematosus, juvenile idiopathic arthritis and juvenile dermatomyositis patients, and to review cardiovascular preventive strategies that should be considered in this population.

Endothelial microparticles mediate inflammation-induced vascular calcification

Stimulation of endothelial cells (ECs) with TNF-α causes an increase in the expression of bone morphogenetic protein-2 (BMP-2) and the production of endothelial microparticles (EMPs). BMP-2 is known to produce osteogenic differentiation of vascular smooth muscle cells (VSMCs). It was found that EMPs from TNF-α-stimulated endothelial cells (HUVECs) contained a significant amount of BMP-2 and were able to enhance VSMC osteogenesis and calcification. Calcium content was greater in VSMCs exposed to EMPs from TNF-α-treated HUVECs than EMPs from nontreated HUVECs (3.56 ± 0.57 vs. 1.48 ± 0.56 µg/mg protein; P < 0.05). The increase in calcification was accompanied by up-regulation of Cbfa1 (osteogenic transcription factor) and down-regulation of SM22α (VSMC lineage marker). Inhibition of BMP-2 by small interfering RNA reduced the VSMC calcification induced by EMPs from TNF-α-treated HUVECs. Similar osteogenic capability was observed in EMPs from both patients with chronic kidney disease and senescent cells, which also presented a high level of BMP-2 expression. Labeling of EMPs with CellTracker shows that EMPs are phagocytized by VSMCs under all conditions (with or without high phosphate, control, and EMPs from TNF-α-treated HUVECs). Our data suggest that EC damage results in the release of EMPs with a high content of calcium and BMP-2 that are able to induce calcification and osteogenic differentiation of VSMCs.