Effect Of HHcy Research Articles

Identification of methylation-regulated genes modulating microglial phagocytosis in hyperhomocysteinemia-exacerbated Alzheimer’s disease

BackgroundHyperhomocysteinemia (HHcy) has been linked to development of Alzheimer’s disease (AD) neuropathologically characterized by the accumulation of amyloid β (Aβ). Microglia (MG) play a crucial role in uptake of Aβ fibrils, and its dysfunction worsens AD. However, the effect of HHcy on MG Aβ phagocytosis remains unstudied.MethodsWe isolated MG from the cerebrum of HHcy mice with genetic cystathionine-β-synthase deficiency (Cbs−/−) and performed bulk RNA-seq. We performed meta-analysis over transcriptomes of Cbs−/− mouse MG, human and mouse AD MG, MG Aβ phagocytosis model, human AD methylome, and GWAS AD genes.ResultsHHcy and hypomethylation conditions were identified in Cbs−/− mice. Through Cbs−/− MG transcriptome analysis, 353 MG DEGs were identified. Phagosome formation and integrin signaling pathways were found suppressed in Cbs−/− MG. By analyzing MG transcriptomes from 4 AD patient and 7 mouse AD datasets, 409 human and 777 mouse AD MG DEGs were identified, of which 37 were found common in both species. Through further combinatory analysis with transcriptome from MG Aβ phagocytosis model, we identified 130 functional-validated Aβ phagocytic AD MG DEGs (20 in human AD, 110 in mouse AD), which reflected a compensatory activation of Aβ phagocytosis. Interestingly, we identified 14 human Aβ phagocytic AD MG DEGs which represented impaired MG Aβ phagocytosis in human AD. Finally, through a cascade of meta-analysis of transcriptome of AD MG, functional phagocytosis, HHcy MG, and human AD brain methylome dataset, we identified 5 HHcy-suppressed phagocytic AD MG DEGs (Flt1, Calponin 3, Igf1, Cacna2d4, and Celsr) which were reported to regulate MG/MΦ migration and Aβ phagocytosis.ConclusionsWe established molecular signatures for a compensatory response of Aβ phagocytosis activation in human and mouse AD MG and impaired Aβ phagocytosis in human AD MG. Our discoveries suggested that hypomethylation may modulate HHcy-suppressed MG Aβ phagocytosis in AD.

Surgical outcomes following encephaloduroarteriosynangiosis in moyamoya disease associated with hyperhomocysteinemia.

This study investigated the effect of indirect revascularization surgery in adult patients with moyamoya disease (MMD) complicated with hyperhomocysteinemia (HHcy), and the effect of HHcy on the progression of adult MMD. A retrospective case-control study was conducted in patients with MMD, with or without HHcy (n=123). Postoperative collateral angiogenesis was evaluated using the Matsushima grading system and disease progression using the Suzuki staging system. Cerebral blood flow was evaluated before and after surgery using dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) and neurological function prognosis using the improved Rankin score (mRS). Univariate and multivariate logistic regression analyses were performed to determine risk factors for the clinical outcomes. There was no significant difference in the Suzuki stage composition ratios between the HHcy group and the non-HHcy group before and after surgery. Non-HHcy patients were more likely to grow new collateral circulating vessels after encephaloduroarteriosynangiosis (EDAS). Moreover, postoperative DSC-MRI indicated that the time to peak significantly improved. HHcy level may be a specific predictor of adverse clinical outcomes after EDAS in patients with MMD and a risk factor for poor collateral circulation and poor prognosis. Patients with MMD complicated with HHcy need to strictly control homocysteine levels before EDAS surgery.

Hyperhomocysteinemia is a risk factor for postoperative ischemia in adult patients with moyamoya disease.

Growing evidence has suggested that hyperhomocysteinemia (HHcy) is a risk factor for cerebral infarction. However, the effect of HHcy on postoperative cerebral ischemia is still unclear. We aim to investigate the relationship between HHcy and postoperative ischemia of adult patients with moyamoya disease (MMD). A total of 138 adult patients with MMD were prospectively recruited from July 1 to December 31, 2019. After excluding 14 patients accepting conservative therapy, all 124 patients who underwent surgical treatment were enrolled. Patients were grouped according to postoperative ischemia and HHcy presentation, respectively. Clinical data and laboratory examinations were compared by statistical analyses. Potential risk factors were evaluated by univariate and multivariate logistic regression analysis. Comparing to the normal, patients with postoperative ischemia were higher in serum homocysteine (Hcy) level (P = 0.039) and HHcy ratio (P = 0.035). Furthermore, HHcy was more common in males (P = 0.007) than females. Logistic analysis results showed that HHcy (OR 5.234, 95% CI 1.127-24.315; P = 0.035) was an independent risk factor. HHcy was significantly associated with postoperative ischemia in MMD patients. Our study found that HHcy was correlated to the risk of postoperative ischemia. HHcy can be used as an indicator and a potential therapeutic target for postoperative ischemia in adult patients with MMD. URL: http://www.chictr.org . Unique identifier: ChiCTR2000031412.

Rejuvenated Circulating Endothelial Progenitor Cells and Nitric Oxide in Premenopausal Women with Hyperhomocysteinemia

Hyperhomocysteinemia (HHcy) induced endothelial dysfunction is associated with disturbance in circulating endothelial progenitor cells (EPCs). Nevertheless, whether this unfavorable effect of HHcy on circulating EPCs also exists in premenopausal women is still unknown. Therefore, this leaves an area for the investigation of the difference on the number and activity of circulating EPCs in premenopausal women with hyperhomocysteinemia and its underlying mechanism. The number of circulating EPCs was measured by fluorescence-activated cell sorter analysis, as well as DiI-acLDL and lectin fluorescent staining. The migration and proliferation of circulating were evaluated by the Transwell chamber assay and MTT. Additionally, the endothelial function and levels of nitric oxide (NO), VEGF, and GM-CSF in plasma and culture medium were determined. The number or activity of circulating EPCs and flow-mediated dilatation (FMD) in premenopausal women with or without HHcy were higher than those in postmenopausal women. However, no significant effect of HHcy on the number or activity of circulating EPCs in premenopausal women was observed. A similar alteration in NO level between the four groups was observed. There was a correlation between FMD and the number or activity of EPCs, as well as NO level in plasma or secretion by EPCs. For the first time, our findings illuminated the quantitive or qualitative alterations of circulating EPCs and endothelial function in premenopausal patients with HHcy are preserved, which was associated with retained NO production. The recuperated endothelial repair capacity is possibly the potential mechanism interpreting cardiovascular protection in premenopausal women with HHcy.

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.

Cerebroprotective effects of hydrogen sulfide in homocysteine-induced neurovascular permeability: Involvement of oxidative stress, arginase, and matrix metalloproteinase-9.

An elevated level of homocysteine (Hcy) leads to hyperhomocysteinemia (HHcy), which results in vascular dysfunction and pathological conditions identical to stroke symptoms. Hcy increases oxidative stress and leads to increase in blood-brain barrierpermeability and leakage. Hydrogen sulfide (H2 S) production during the metabolism of Hcy has a cerebroprotective effect, although its effectiveness in Hcy-induced neurodegeneration and neurovascular permeability is less explored. Therefore, the current study was designed to perceive the neuroprotective effect of exogenous H 2 S against HHcy, a cause of neurodegeneration. To test this hypothesis, we used four groups of mice: control, Hcy, control + sodium hydrosulfide hydrate (NaHS), and Hcy + NaHS, and an HHcy mice model in Swiss albino mice by giving a dose of 1.8 g of dl-Hcy/L in drinking for 8-10 weeks. Mice that have 30 µmol/L Hcy were taken for the study, and a H 2 S supplementation of 20 μmol/L was given for 8 weeks to all groups of mice. HHcy results in the rise of the levels of superoxide and nitrite, although a concomitant decrease in the level of superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione, and arginase in oxidative stress and a concomitant decrease in the endogenous level of H 2 S. AlthoughH 2 S supplementation ameliorated, the effect of HHcy and the levels of H 2 S returned to the average level in HHcy animals supplemented with H 2 S. Interestingly, H 2 S supplementation ameliorated neurovascular remodeling and neurodegeneration. Thus, our study suggested that H 2 S could be a beneficial therapeutic candidate for the treatment of Hcy-associated neurodegeneration, such as stroke and neurovascular disorders.

HYPERHOMOCYSTEINEMIA LEAD TO TRANSMURAL INFLAMMATION OF COLON AND INCREASE SEVERITY OF DISEASE IN ACETIC ACID-INDUCED COLITIS IN RAT

Objective: The present study was designed to evaluate the effect of hyperhomocysteinemia (Hhcy) induced by feeding rats high methionine diet on the colon wall. Colonic damages caused by Hhcy were compared with those induced by acetic –acid induced colitis.Methods: Sprague-Dawley rats (200-250g) were divided into four groups: group C (control), group M (received 1 g/kg methionine p. o. during 15 d), group A (colitis was induced by transrectal administration of acetic acid 4% on 8th day) and group MA (received methionine and acetic acid). At the end of the study, plasma homocysteine, C-reactive protein (CRP) and leukocytes (WBC) count were evaluated, all rats were sacrificed and distal 8 cm of the colon was dissected. Colon was weighed for disease activity index (DAI) and injuries were assessed macroscopically and histologically.Results: High methionine diet induced significant (P<0.001) increase of homocysteine (hcy), CRP levels and WBC count compared to control. Acetic acid rats showed a significant decrease of WBC count. Mixed treatment caused a significant increase of hcy, CRP and a significant decrease of WBC count. Our results showed that Hhcy causes significant damages and immune cells infiltration in all layers of the colonic wall.Conclusion: The present investigation demonstrated that Hhcy increased the major inflammatory markers as CRP and leukocytes count and produced transmural colitis in rats. Effect of Hhcy is more toxic on the colonic wall than acetic acid indeed while acetic acid lesions are localized in mucosa and submucosa the lesions of hcy extend to the all layers (mucosa, submucosa and muscularis propria). Acetic acid induced colitis in hyperhomocysteinemic rats increased the severity of colitis.

The role of homocysteine in seminal vesicles remodeling in rat

Elevated plasma homocysteine (Hcy) levels have been associated with several tissue injuries including heart and liver fibrosis. In these diseases, hyperhomocysteinemia (Hhcy) plays a major role in modulating the alteration of the balance between matrix metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMPs), leading to the pathological accumulation of extracellular matrix (ECM) proteins. Since the effect of Hhcy on ECM of seminal vesicle was not studied, the aim of our research was to check if Hcy can induce a remodeling within seminal vesicles ECM. The study was conducted in 22 adult male Wistar rats. The rats were divided into two groups: a control group, which received standard diet and tap water; the treated group received the same diet and water supplemented with solution of L-methionine (200 mg/kg b.w./day) for 6 months. Plasma homocysteine concentration was measured. Histological changes were observed with light microscope. The presence of collagen I and III and metalloproteinases (2, 3, 7 and 9) in the seminal vesicles was examined using immunohistochemistry and Western blotting. Plasma Hcy levels increased significantly after methionine treatment and interfered significantly with body weight in treated rats. The content of fibrillar collagens (I and III) in the wall of seminal vesicles was elevated in hyperhomocysteinemic rats. Moreover, we found that hyperhomocysteinemia increased the expression of MMP-2, -3, -7 and -9 in seminal vesicles of experimental rats. Increased plasma concentration of Hcy accompanied by the accumulation of collagen and upregulation of MMPs in rat seminal vesicles might contribute to the remodeling of seminal vesicles.

HYPERHOMOCYSTEINEMIA LEAD TO TRANSMURAL INFLAMMATION OF COLON AND INCREASE SEVERITY OF DISEASE IN ACETIC ACID-INDUCED COLITIS IN RAT

Objective: The present study was designed to evaluate the effect of hyperhomocysteinemia (Hhcy) induced by feeding rats high methionine diet on the colon wall. Colonic damages caused by Hhcy were compared with those induced by acetic –acid induced colitis.Methods: Sprague-Dawley rats (200-250g) were divided into four groups: group C (control), group M (received 1 g/kg methionine p. o. during 15 d), group A (colitis was induced by transrectal administration of acetic acid 4% on 8th day) and group MA (received methionine and acetic acid). At the end of the study, plasma homocysteine, C-reactive protein (CRP) and leukocytes (WBC) count were evaluated, all rats were sacrificed and distal 8 cm of the colon was dissected. Colon was weighed for disease activity index (DAI) and injuries were assessed macroscopically and histologically.Results: High methionine diet induced significant (P<0.001) increase of homocysteine (hcy), CRP levels and WBC count compared to control. Acetic acid rats showed a significant decrease of WBC count. Mixed treatment caused a significant increase of hcy, CRP and a significant decrease of WBC count. Our results showed that Hhcy causes significant damages and immune cells infiltration in all layers of the colonic wall.Conclusion: The present investigation demonstrated that Hhcy increased the major inflammatory markers as CRP and leukocytes count and produced transmural colitis in rats. Effect of Hhcy is more toxic on the colonic wall than acetic acid indeed while acetic acid lesions are localized in mucosa and submucosa the lesions of hcy extend to the all layers (mucosa, submucosa and muscularis propria). Acetic acid induced colitis in hyperhomocysteinemic rats increased the severity of colitis.

Hyperhomocysteinemia suppresses bone marrow CD34 + /VEGF receptor 2 + cells and inhibits progenitor cell mobilization and homing to injured vasculature—a role of β1‐integrin in progenitor cell migration and adhesion

Hyperhomocysteinemia (HHcy) impairs re-endothelialization and accelerates vascular remodeling. The role of CD34(+)/VEGF receptor (VEGFR) 2(+) progenitor cells (PCs) in vascular repair in HHcy is unknown. We studied the effect of HHcy on PCs and its role in vascular repair in severe HHcy (∼150 μM), which was induced in cystathionine-β synthase heterozygous mice fed a high-methionine diet for 8 weeks. Vascular injury was introduced by carotid air-dry endothelium denudation. CD34(+)/VEGFR2(+) cells were examined by flow cytometry. HHcy reduced bone marrow (BM) CD34(+)/VEGFR2(+) cells and suppressed replenishment of postinjury CD34(+)/VEGFR2(+) cells in peripheral blood (PB). Donor green fluorescent protein-positive PC homing to the injured vessel was reduced in HHcy after CD34(+) PCs from enhanced green fluorescent protein mice were adoptively transferred following carotid injury. CD34(+) PC transfusion partially reversed HHcy-suppressed re-endothelialization and HHcy-induced neointimal formation. Furthermore, homocysteine (Hcy) inhibited proliferation, adhesion, and migration and suppressed β1-integrin expression and activity in human CD34(+) endothelial colony-forming cells (ECFCs) isolated from PBs in a dose-dependent manner. A functional-activating β1-integrin antibody rescued Hcy-suppressed adhesion and migration in CD34(+) ECFCs. In conclusion, HHcy reduces BM CD34(+)/VEGFR2(+) generation and suppresses CD34(+)/VEGFR2(+) cell mobilization and homing to the injured vessel via β1-integrin inhibition, which partially contributes to impaired re-endothelialization and vascular remodeling.

Effect of experimental hyperhomocysteinemia on plasma lipid profile, insulin sensitivity and paraoxonase 1 in the rat

Hyperhomocysteinemia (hHcy) is a well-known risk factor of cardiovascular diseases, however, the mechanism of its detrimental effect is incompletely understood. Some studies suggest that, paradoxically, hHcy may promote traditional risk factors such as hyperlipidemia. We examined the effect of experimental hHcy on plasma lipid profile, glucose and insulin concentrations as well as on high-density lipoprotein (HDL)-associated antiatherosclerotic enzyme, paraoxonase 1 (PON1). Hyperhomocysteinemia was induced by feeding male Wistar rats with diet enriched with methionine or diet enriched in methionine and deficient in folate, vitamin B6 and B12 for 8 weeks. These diets resulted in the 3.3- and 9.6-fold elevation of plasma Hcy, respectively. Plasma total and HDL-cholesterol, triglycerides and apolipoprotein A-I were similar in all groups. High-methionine diets had no effect on fasting plasma glucose but significantly increased fasting plasma insulin concentration indicating impaired ability of insulin to suppress hepatic glucose output. PON1 activity was unchanged in high methionine vitamin B-sufficient diet-fed rats, but was decreased by 30-40% toward various substrates in high methionine vitamin B-deficient diet-fed animals. The results indicate that hHcy has no effect on lipid metabolism, however, induces insulin resistance and, above certain Hcy level, PON1 deficiency. Impaired insulin signaling and reduced PON1 activity may contribute to detrimental effects of hHcy. Adipobiology 2012; 4: 77-84.

Reduction of Superior Mesenteric Hemodynamic Responsiveness to [Sar^1, Thr^8]-Angiotensin Ⅱ and Bradykinin, But Not Sodium Nitroprusside, in the Presence of Homocysteine Infusion

Hyperhomocysteinemia (HHcy) has been shown to be an independent risk factor for cardiovascular diseases, superior mesenteric thrombosis and inflammatory bowel disease. Superior mesenteric artery (SMA) supplies the intestine and reduced SMA blood flow results in intestinal ischemia. Although in vitro studies have shown that endothelium-dependent vasorelaxation of SMA is reduced in the presence of homocysteine incubation, it is not confirmed with in vivo studies. In this work, we evaluated responsiveness of SMA to endothelium-dependent or -independent vasodilators and a vasoconstrictor in the absence and presence of acute HHcy in vivo to clarify effect of HHcy on superior mesenteric vascular function. Sodium nitroprusside (SNP), bradykinin (BK), and [Sar1,Thr8]angiotensin II ([Sar1,Thr8]-ANG II) were intravenously administrated in sequence in male Sprague-Dawley rats with or without D,L-homocysteine infusion (6 mg/kg/min) through femoral vein. Agonists-induced changes in carotid artery blood pressure, superior mesenteric blood flow and vascular resistance were measured in the present study. We found that acute HHcy infusion had little effects on SNP-induced hemodynamic changes; however, BK-induced changes in blood pressure, blood flow and vascular resistance were significantly reduced in the presence of HHcy infusion. Additionally, HHcy also markedly decreased [Sar1,Thr8]-ANG II-induced superior mesenteric hemodynamic changes. These results demonstrated that responsiveness of SMA to vasoconstrictor, endothelium-dependent, but not endothelium-independent vasodilator, was inhibited in the presence of Hcy infusion. This HHcy-associated vascular hyporesponsiveness to vasoconstrictors and endothelium-dependent vasodilators may partially contribute to circulatory dysfunctions.

Acute Hyperhomocysteinemia Induces Microvascular and Macrovascular Endothelial Dysfunction

Hyperhomocysteinemia (Hhcy) has been shown to induce endothelial dysfunction due to a decrease in bioavailable nitric oxide (NO) by increased vascular oxidant stress. This can be detected as an impairment of endothelium-dependent vasodilation in conductance arteries, like brachial or coronary arteries. The effect of Hhcy on endothelial function (EF) in small resistance vessels that critically determine organ perfusion, however, has not been studied systematically in humans. Therefore, we simultaneously determined macro- and microvascular EF in 11 healthy subjects before and during acute Hhcy induced by an oral methionine challenge. Macrovascular EF was determined by measuring endothelium-dependent flow-mediated vasodilation of the brachial artery by vascular ultrasound and microvascular EF by measuring skin perfusion during iontophoresis of acetylcholine using laser Doppler fluxmetry. Oral methionine significantly increased homocysteine levels by about 5.1-fold. Acute Hhcy leads to a significant decrease in flow-mediated vasodilation of the brachial artery from 8.1 +/- 0.5% to 3.6 +/- 0.6% and to a significant decrease in the ratio of acetylcholine-stimulated vs. baseline laser Doppler flow in the forearm skin (from 9.2 +/- 1.0- to 7.8 +/- 1.3-fold). Acute Hhcy impairs macro- as well as microvascular (EF) in humans.

Impaired Nitric Oxide-Mediated Flow-Induced Coronary Dilation in Hyperhomocysteinemia: Morphological and Functional Evidence for Increased Peroxynitrite Formation

Hyperhomocysteinemia (HHcy) is a newly recognized risk factor for myocardial infarction, however, the effect of HHcy on endothelium-dependent flow-induced dilation of coronary arteries is not known. Thus, changes in diameter of small intramural coronary arteries (diameter, approximately 145 microm) isolated from control rats and rats with methionine diet-induced HHcy were investigated by videomicroscopy. Increases in intraluminal flow (from 0 to 40 microl/min) elicited dilations of control vessels (maximum, 25 +/- 2 microm), responses that were absent in HHcy arteries. The nitric oxide (NO) synthase inhibitor L-NAME inhibited flow-induced dilation of control coronaries, whereas it had no effect on responses of HHcy arteries. Dilations of control and HHcy arteries to the NO donor sodium nitroprusside were not different. Responses to flow in HHcy coronary arteries were unaffected by administration of L-arginine or the prostaglandin H(2)/thromboxane A(2) receptor antagonist SQ 29,548. However, in the presence of superoxide dismutase (plus catalase) or the superoxide scavenger Tiron increases in flow elicited L-NAME-sensitive dilations of HHcy coronaries (maximum, 18 +/- 5 microm). Also, superoxide dismutase significantly reduced the enhanced superoxide production of HHcy coronaries (measured by the lucigenin chemiluminescence method). Single vessel Western blotting showed an increased tyrosine nitrosation (a stable biomarker of tissue peroxynitrite formation) in HHcy coronaries. Also, extensive prevalence of 3-nitrotyrosine immunoreactivity was observed in HHcy coronaries that was confined primarily to the subendothelial layers of smooth muscle. We propose that in HHcy an increased level of superoxide scavenges NO forming peroxynitrite, which increases protein nitrosation. The reduced bioavailability of NO impairs flow-induced dilations of coronary arteries, which may contribute to the development of coronary atherosclerosis and ischemic heart disease.