Hyperhomocysteinemia (HHcy) is considered to be an independent risk factor for cardiovascular diseases, but the molecular mechanisms underlying its pathogenesis are not fully understood. Endothelial dysfunction is a key initiating factor in the pathogenesis of atherosclerosis, which is commonly observed in almost all HHcy-induced vascular diseases. HHcy promotes oxidative stress, inhibits nitric oxide production, suppresses hydrogen sulfide signaling pathway, promotes endothelial mesenchymal transition, activates coagulation pathways, and promotes protein N-homocysteination and cellular hypomethylation, all of which can cause endothelial dysfunction. This article reviews the specific links between HHcy and endothelial dysfunction, and highlights recent evidence that endothelial mesenchymal transition contributes to HHcy-induced vascular damage, with a hope to provide new ideas for the clinical treatment of HHcy-related vascular diseases.
Humans ; Atherosclerosis ; Cardiovascular Diseases ; Endothelium, Vascular ; Homocysteine/metabolism* ; Hyperhomocysteinemia/complications* ; Oxidative Stress ; Risk Factors

Objective To explore the association between plasma homocysteine (Hcy) level and hyper-uricemia (HUA) in the elderly patients with hypertension.Methods From March to August in 2018,9902 hypertensive patients ≥ 60 years were routinely tested for blood biochemical indicators in Wuyuan county,Jiangxi province.The patients were assigned into a HUA group and a normal uric acid group.Multivariate Logistic regression was adopted to analyze the relationship between Hcy level and the risk of HUA.Results Compared with the normal uric acid group,the HUA group showed increased incidence of hyperhomocysteinemia (99.9% vs.98.7%,P<0.001) and elevated Hcy level[16.8 (13.8-21.5) μmol/L vs.14.4 (12.3-17.7) μmol/L,P<0.001].The multivariate Logistic regression analysis showed that after adjusting for influencing factors,the risk of HUA in the patients with hyperhomocysteinemia was 2.92 times of that in the patients with a normal Hcy level.The threshold effect analysis showed that the Hcy level was positively correlated with the occurrence of HUA in the case of Hcy<20 μmol/L (OR=1.05,95%CI=1.04-1.07,P<0.001).In the case of Hcy ≥ 20 μmol/L,there was no correlation between Hcy level and HUA (OR=1.00,95%CI=0.99-1.00,P=0.055),and the likelihood ratio test showed statistically significant results (P<0.001).Conclusion The elderly with hypertension should pay attention to control the Hcy level,which will be helpful to prevent the occurrence of HUA.
Humans ; Aged ; Hyperuricemia/complications* ; Hyperhomocysteinemia/epidemiology* ; Uric Acid ; Hypertension ; Homocysteine ; Risk Factors

Chronic stress is generally accepted as the main risk factor in the development of cognitive decline; however, the underlying mechanisms remain unclear. Previous data have demonstrated that the levels of homocysteine (Hcy) are significantly elevated in the plasma of stressed animals, which suggests that Hcy is associated with stress and cognitive decline. To test this hypothesis, we analyzed the cognitive function, plasma concentrations of Hcy, and brain-derived neurotropic factor (BDNF) levels in rats undergoing chronic unpredicted mild stress (CUMS). The results showed that decreased cognitive behavioral performance and decreased BDNF transcription and protein expression were correlated with hyperhomocysteinemia (HHcy) levels in stressed rats. Diet-induced HHcy mimicked the cognitive decline and BDNF downregulation in the same manner as CUMS, while Hcy reduction (by means of vitamin B complex supplements) alleviated the cognitive deficits and BDNF reduction in CUMS rats. Furthermore, we also found that both stress and HHcy disturbed the DNA methylation process in the brain and induced DNA hypermethylation in the BDNF promoter. In contrast, control of Hcy blocked BDNF promoter methylation and upregulated BDNF levels in the brain. These results imply the possibility of a causal role of Hcy in stress-induced cognitive decline. We also used ten-eleven translocation (TET1), an enzyme that induces DNA demethylation, to verify the involvement of Hcy and DNA methylation in the regulation of BDNF expression and the development of stress-related cognitive decline. The data showed that TET1-expressing viral injection into the hippocampus inhibited BDNF promoter methylation and significantly mitigated the cognitive decline in HHcy rats. Taken together, novel evidence from the present study suggests that Hcy is likely involved in chronic stress-induced BDNF reduction and related cognitive deficits. In addition, the negative side-effects of HHcy may be associated with Hcy-induced DNA hypermethylation in the BDNF promoter. The results also suggest the possibility of Hcy as a target for therapy and the potential value of vitamin B intake in preventing stress-induced cognitive decline.
Animals ; Brain-Derived Neurotrophic Factor/metabolism* ; Cognitive Dysfunction/complications* ; DNA Methylation ; Homocysteine/metabolism* ; Hyperhomocysteinemia/metabolism* ; Rats ; Stress, Psychological/physiopathology*

Hyperhomocysteinemia (Hhcy) is an independent risk factor for Alzheimer's disease (AD). Visual dysfunction is commonly found and is positively correlated with the severity of cognitive defects in AD patients. Our previous study demonstrated that Hhcy induces memory deficits with AD-like tau and amyloid-β (Aβ) pathologies in the hippocampus, and supplementation with folate and vitamin B12 (FB) prevents the Hhcy-induced AD-like pathologies in the hippocampus. Here, we investigated whether Hhcy also induces AD-like pathologies in the retina and the effects of FB. An Hhcy rat model was produced by vena caudalis injection of homocysteine for 14 days, and the effects of FB were assessed by simultaneous supplementation with FB in drinking water. We found that Hhcy induced vessel damage with Aβ and tau pathologies in the retina, while simultaneous supplementation with FB remarkably attenuated the Hhcy-induced tau hyperphosphorylation at multiple AD-related sites and Aβ accumulation in the retina. The mechanisms involved downregulation of amyloid precursor protein (APP), presenilin-1, beta-site APP-cleaving enzyme 1, and protein phosphatase-2A. Our data suggest that the retina may serve as a window for evaluating the effects of FB on hyperhomocysteinemia-induced Alzheimer-like pathologies.
Alzheimer Disease ; etiology ; metabolism ; pathology ; therapy ; Amyloid beta-Peptides ; metabolism ; Animals ; Dietary Supplements ; Disease Models, Animal ; Folic Acid ; therapeutic use ; Homocysteine ; Hyperhomocysteinemia ; complications ; metabolism ; pathology ; therapy ; Male ; Rats, Sprague-Dawley ; Retina ; metabolism ; pathology ; Retinal Vessels ; metabolism ; pathology ; Vitamin B 12 ; therapeutic use ; tau Proteins ; metabolism

The aim of this study was to investigate the mechanism by which a diet inducing high hyperhomocysteinemia (HHcy) leads to the deterioration of erectile function in rats and whether this is inhibited by expression of the human tissue kallikrein-1 (hKLK1) gene. We established a rat model of HHcy by feeding methionine (Met)-rich diets to male Sprague-Dawley (SD) rats. Male wild-type SD rats (WTRs) and transgenic rats harboring the hKLK1 gene (TGRs) were fed a normal diet until 10 weeks of age. Then, 30 WTRs were randomly divided into three groups as follows: the control (n = 10) group, the low-dose (4% Met, n = 10) group, and the high-dose (7% Met, n = 10) group. Another 10 age-matched TGRs were fed the high-dose diet and designated as the TGR+7% Met group. After 30 days, in all four groups, erectile function was measured and penile tissues were harvested to determine oxidative stress, endothelial cell content, and penis fibrosis. Compared with the 7% Met group, the TGR+7% Met group showed diminished HHcy-induced erectile dysfunction (ED), indicating the improvement caused by hKLK1. Regarding corpus cavernosum endothelial cells, hKLK1 preserved endothelial cell-cell junctions and endothelial cell content, and activated protein kinase B/endothelial nitric oxide synthase (Akt/eNOS) signaling. Fibrosis assessment indicated that hKLK1 preserved normal penis structure by inhibiting apoptosis in the corpus cavernosum smooth muscle cells. Taken together, these findings showed that oxidative stress, impaired corpus cavernosum endothelial cells, and severe penis fibrosis were involved in the induction of ED by HHcy in rats, whereas hKLK1 preserved erectile function by inhibiting these pathophysiological changes.
Animals ; Apoptosis ; Diet ; Endothelial Cells ; Erectile Dysfunction/prevention & control* ; Fibrosis ; Humans ; Hyperhomocysteinemia/complications* ; Male ; Methionine ; Oxidative Stress ; Penis/pathology* ; Rats ; Rats, Sprague-Dawley ; Rats, Transgenic ; Signal Transduction/genetics* ; Tissue Kallikreins/genetics*

Homocysteine (Hcy) is an intermediate metabolite of methionine metabolism. Hyperhomocysteinemia (HHcy) is defined as a condition characterized by plasma Hcy level above 16 μmol/L which can result from abnormal Hcy metabolism. HHcy has been confirmed to be related to cardio-cerebrovascular disease, peripheral vascular disorders, neurodegenerative diseases, diabetes, pregnancy-induced hypertension syndrome, liver cirrhosis and kidney diseases. In this review, we summarize the correlation between HHcy and kidney diseases. Elucidating the role of HHcy in kidney diseases may provide a new strategy to prevent and treat kidney diseases.
Homocysteine ; Humans ; Hyperhomocysteinemia ; complications ; Kidney Diseases ; complications

OBJECTIVETo study the clinical features and treatment outcomes of cardiovascular system involvement in children with methylmalonic aciduria combined with hyperhomocysteinemia (MMACHC).

METHODSThe clinical data of 10 children with methylmalonic aciduria combined with hyperhomocysteinemia and who had cardiovascular system involvement were retrospectively analyzed and the treatment outcomes were followed up.

RESULTSIn the 10 patients, there were 4 cases with initial presentations of cardiovascular system symptoms such as shortness of breath and dyspnea, 3 cases with urinary tract symptoms such as edema, hematuria and proteinuria, and 3 cases with nervous system symptoms such as developmental retardation and convulsions. The 10 patients had different types and severity of cardiovascular injuries. After 3 months to 8 years of follow-up, the congenital heart defects resolved naturally in 2 cases, and the patient with arrhythmia had no obvious changes. In 5 cases of hypertension, blood pressures recovered to normal in 3 cases, and 1 case was lost to follow-up. In 5 patients with pulmonary hypertension, 2 died, 2 recovered, and 1 case had mildly elevated pulmonary artery pressure. Seven patients underwent MMACHC gene testing, and 5 showed c.80A>G mutations.

CONCLUSIONSMetabolic disease should be taken into account for the children with unexplained pulmonary hypertension and hypertension with the onset of the shortness of breath and dyspnea. The severity of cardiovascular system involvement might be one of the most important factors affecting the prognosis of children with MMACHC. Cardiavascular system involvement of the patients may be related to MMACHC c.80A>G mutations.

Amino Acid Metabolism, Inborn Errors ; complications ; genetics ; Cardiovascular Diseases ; etiology ; Child ; Child, Preschool ; Female ; Follow-Up Studies ; Humans ; Hyperhomocysteinemia ; complications ; genetics ; Infant ; Infant, Newborn ; Male ; Retrospective Studies

PURPOSE: The purpose of the study was to differentiate ischemic central retinal vein occlusion (CRVO) from nonischemic CRVO during the early acute phase using plasma homocysteine as a biochemical marker. METHODS: Fasting plasma homocysteine, serum vitamin B12, and folate levels were measured in 108 consecutive unilateral elderly adult (age >50 years) ischemic CRVO patients in the absence of local and systemic disease and compared with a total of 144 age and sex matched nonischemic CRVO patients and 120 age and sex matched healthy control subjects. RESULTS: Homocysteine level was significantly increased in the patients with ischemic CRVO in comparison with nonischemic CRVO patients (p = 0.009) and also in comparison with control subjects (p < 0.001). Analysis also showed that hyperhomocysteinemia was associated with increased incidence of ischemic CRVO (odds ratio, 18) than that for nonischemic CRVO (odds ratio, 4.5). Serum vitamin B12 and folate levels were significantly lower (p < 0.001) in CRVO patients compared to the control but were not significantly different between nonischemic and ischemic CRVO patients (p > 0.1). CONCLUSIONS: Hyperhomocysteinemia can be regarded as useful in differentiating nonischemic and ischemic CRVO during the early acute phase in absence of local and systemic disease in the elderly adult (age >50 years) population.
Acute Disease ; Aged ; Biomarkers/*blood ; Case-Control Studies ; Diagnosis, Differential ; Female ; Follow-Up Studies ; Humans ; Hyperhomocysteinemia/blood/*complications/diagnosis ; Male ; Middle Aged ; Prospective Studies ; Retinal Vein Occlusion/complications/*diagnosis ; Time Factors

BACKGROUNDThe high blood homocysteine (Hcy) levels found in patients with hyperhomocysteinemia (HHcy) have been implicated in an increased risk of cardiovascular disease morbidity and mortality in end-stage renal disease (ESRD). This study investigated the association of HHcy with progression of IgA nephropathy.

METHODSWe analyzed 108 participants newly diagnosed with IgA nephropathy between August 2005 and August 2007 in the Department of Nephrology, Chinese People's Liberation Army General Hospital. The association between clinicopathological factors and the Hcy levels were analyzed by Logistic regression and those with ESRD risk were analyzed by Cox regression.

RESULTSPatients were aged (35.71 ± 10.73) years and included 45.71% women and 12.04% patients with HHcy. In multivariate Logistic regression analysis, HHcy was associated with arterial lesions (OR 2.60; 95% CI 1.55 ± 4.34; P < 0.001) even when age, body mass index, estimated glomerular filtration rate, mean arterial pressure, and initial proteinuria were taken into account. Mean follow-up was (67.37 ± 16.21) months. HHcy was also associated with worse ESRD-free survival (HR 4.71; 95% CI 1.45 to 15.31; P = 0.010).

CONCLUSIONHHcy is associated with the risk of intrarenal arterial lesions and may be useful for estimating the prognosis of IgA nephropathy.

Adult ; Body Mass Index ; Female ; Glomerular Filtration Rate ; physiology ; Glomerulonephritis, IGA ; etiology ; physiopathology ; Humans ; Hyperhomocysteinemia ; complications ; physiopathology ; Logistic Models ; Male ; Middle Aged ; Retrospective Studies

No abstract available.
Aged ; Anticoagulants/therapeutic use ; DNA Mutational Analysis ; Echocardiography ; Genetic Predisposition to Disease ; Homozygote ; Humans ; Hyperhomocysteinemia/blood/complications/diagnosis/drug therapy/*genetics ; Male ; Methylenetetrahydrofolate Reductase (NADPH2)/*genetics ; *Mutation ; Phenotype ; Pulmonary Embolism/blood/diagnosis/drug therapy/*etiology ; Severity of Illness Index ; Thrombolytic Therapy ; Tomography, X-Ray Computed ; Treatment Outcome ; Vitamins/therapeutic use