Vascular oxidant stress and inflammation in hyperhomocysteinemia

Calpain Inhibition Restores Autophagy and Prevents Mitochondrial Fragmentation in a Human iPSC Model of Diabetic Endotheliopathy

The relationship between diabetes and endothelial dysfunction remains unclear, particularly the association with pathological activation of calpain, an intracellular cysteine protease. Here, we used human induced pluripotent stem cells-derived endothelial cells (iPSC-ECs) to investigate the effects of diabetes on vascular health. Our results indicate that iPSC-ECs exposed to hyperglycemia had impaired autophagy, increased mitochondria fragmentation, and was associated with increased calpain activity. In addition, hyperglycemic iPSC-ECs had increased susceptibility to cell death when subjected to a secondary insult-simulated ischemia-reperfusion injury (sIRI). Importantly, calpain inhibition restored autophagy and reduced mitochondrial fragmentation, concurrent with maintenance of ATP production, normalized reactive oxygen species levels and reduced susceptibility to sIRI. Using a human iPSC model of diabetic endotheliopathy, we demonstrated that restoration of autophagy and prevention of mitochondrial fragmentation via calpain inhibition improves vascular integrity. Our human iPSC-EC model thus represents a valuable platform to explore biological mechanisms and new treatments for diabetes-induced endothelial dysfunction.

Effects of Folate Supplementation on Carotid Intima-Media Thickness, Biomarkers of Inflammation, and Oxidative Stress in Carbamazepine-Treated Epileptic Children

Background:

This study was conducted to assess the effects of folate supplementation on carotid intima-media thickness (CIMT), biomarkers of inflammation, and oxidative stress in carbamazepine-treated epileptic children.

Methods:

This randomized, double-blind, placebo-controlled trial was carried out in 54 epileptic children aged 2–12 years old receiving carbamazepine monotherapy. Participants were randomly allocated into two groups to receive either 5 mg folate supplements or placebo (n = 27 in each group) for 12 weeks.

Results:

After the 12-week intervention, compared with the placebo, folate supplementation resulted in a significant reduction in plasma homocysteine (Hcy) (changes from baseline − 2.1 ± 2.5 vs. +0.1 ± 0.4 μmol/L, P < 0.001), serum high-sensitivity C-reactive protein (hs-CRP) (changes from baseline − 1.5 ± 3.5 vs. +0.4 ± 1.4 mg/L, P = 0.01), a significant increase in plasma nitric oxide (NO) (changes from baseline + 1.9 ± 5.8 vs. −2.0 ± 6.4 μmol/L, P = 0.02), and total antioxidant capacity (TAC) concentrations (changes from baseline + 88.6 ± 116.0 vs. +1.8 ± 77.4 mmol/L, P = 0.002). We did not observe any significant effects in mean levels of left and right CIMT, maximum levels of left and right CIMT, and total glutathione (GSH) and malondialdehyde (MDA) levels following the supplementation of folate compared with the placebo.

Conclusions:

Overall, folate supplementation at a dosage of 5 mg/day for 12 weeks among epileptic children receiving carbamazepine had beneficial effects on Hcy, hs-CRP, NO, and TAC levels, but did not affect CIMT, and GSH and MDA levels.

Vitamin B12 Levels in Methamphetamine Addicts

Objective: It has been established that reduced vitamin B12 serum levels are associated with cognitive decline and mental illness. The chronic use of methamphetamine (MA), which is a highly addictive drug, can induce cognitive impairment and psychopathological symptoms. There are few studies addressing the association of MA with vitamin B12 serum levels. This study examined whether the serum levels of B12 are associated with MA addiction.

Methods: Serum vitamin B12, homocysteine (Hcy), glucose and triglyceride concentrations were measured in 123 MA addicts and 108 controls. In addition, data were collected on their age, marital status, level of education and Body Mass Index (BMI) for all participants. In the patient group, the data for each subject were collected using the Fagerstrom Test for Nicotine Dependence (FTND), the Alcohol Use Disorders Identification Test (AUDIT), and a drug use history, which included the age of onset, total duration of MA use, the number of relapses and addiction severity.

Results: Our results showed that MA addicts had lower vitamin B12 levels (p < 0.05) than those of healthy controls, but Hcy levels were not significantly different between the two groups (p > 0.05). Serum B12 levels were negatively correlated with the number of relapses in the MA group. Furthermore, binary logistics regression analysis indicated that the B12 was an influencing factor contributing to addiction severity.

Conclusion: The findings of this study suggest that some MA addicts might have vitamin B12 deficiency, and serum B12 levels may be involved in the prognosis of MA addiction.

Is hyperhomocysteinemia associated with the structural changes of the substantia nigra in Parkinson's disease? A two-year follow-up study

OBJECTIVE

It was recently found that structural changes in the substantia nigra (SN) and motor symptoms become more prominent in Parkinson's disease (PD) patients with striatal silent lacunar infarction (SSLI) than in those without SSLI. Hyperhomocysteinemia (HHCY) was an independent risk factor for SSLI in PD patients. In this follow-up study, we investigated the relationship between HHCY and structural changes of the SN in PD patients.

METHODS

A total of 72 untreated early PD patients without SSLI, divided into control and HHCY groups, were enrolled in this study. All participants underwent conventional MRI and diffusion kurtosis imaging (DKI) twice; at baseline and at the 2-year visit. The differences of the following variables between the two groups were analyzed: mean kurtosis (MK) values of the SN, the severity of disease, daily dosage of levodopa, and the variation of these indexes from baseline to 2-year visit. Logistic regression analysis was used to identify the relationship between HHCY and structural changes of the SN in PD patients.

RESULTS

1.All variables mentioned above showed significant differences between the two groups. 2. The variation in MK values of the SN were positively correlated with the variation in the severity of disease. 3. HHCY was an independent risk factor for the variation in MK values of the SN in PD patients.

CONCLUSION

HHCY is associated with the structural changes of the SN in PD patients. As PD progresses, motor symptoms become aggravated with increased structural changes to the SN, especially in patients with HHCY.

Homocysteine and homocysteine-related compounds: an overview of the roles in the pathology of the cardiovascular and nervous systems

Homocysteine, an amino acid containing a sulfhydryl group, is an intermediate product during metabolism of the amino acids methionine and cysteine. Hyperhomocysteinemia is used as a predictive risk factor for cardiovascular disorders, the stroke progression, screening for inborn errors of methionine metabolism, and as a supplementary test for vitamin B₁₂ deficiency. Two organic systems in which homocysteine has the most harmful effects are the cardiovascular and nervous system. The adverse effects of homocysteine are achieved by the action of several different mechanisms, such as overactivation of N-methyl-d-aspartate receptors, activation of Toll-like receptor 4, disturbance in Ca²⁺ handling, increased activity of nicotinamide adenine dinucleotide phosphate-oxidase and subsequent increase of production of reactive oxygen species, increased activity of nitric oxide synthase and nitric oxide synthase uncoupling and consequent impairment in nitric oxide and reactive oxygen species synthesis. Increased production of reactive species during hyperhomocysteinemia is related with increased expression of several proinflammatory cytokines, including IL-1β, IL-6, TNF-α, MCP-1, and intracellular adhesion molecule-1. All these mechanisms contribute to the emergence of diseases like atherosclerosis and related complications such as myocardial infarction, stroke, aortic aneurysm, as well as Alzheimer disease and epilepsy. This review provides evidence that supports the causal role for hyperhomocysteinemia in the development of cardiovascular disease and nervous system disorders.

Oxidative stress and platelet activation in subjects with moderate hyperhomocysteinaemia due to MTHFR 677 C→T polymorphism

The methylenetetrahydrofolate reductase (MTHFR) 677 C→T polymorphism may be associated with elevated total homocysteine (tHcy) levels, an independent risk factor for cardiovascular disease. It was the study objective to evaluate in vivo lipid peroxidation and platelet activation in carriers of the MTHFR 677 C→T polymorphism and in non-carriers, in relation to tHcy and folate levels. A cross-sectional comparison of urinary 8-iso-prostaglandin (PG)F2α and 11-dehydro-thromboxane (TX)B2 (markers of in vivo lipid peroxidation and platelet activation, respectively) was performed in 100 carriers and 100 non-carriers of the polymorphism. A methionine-loading test and folic acid supplementation were performed to investigate the causal relationship of the observed associations. Urinary 8-iso-PGF2α and 11-dehydro-TXB2 were higher in carriers with hyperhomocysteinaemia than in those without hyperhomocysteinaemia (p<0.0001). Hyperhomocysteinaemic carriers had lower folate levels (p=0.0006), higher urinary 8-iso-PGF2α (p<0.0001) and 11-dehydro-TXB2 (p<0.0001) than hyperhomocysteinaemic non-carriers. On multiple regression analysis, high tHcy (p<0.0001), low folate (p<0.04) and MTHFR 677 C→T polymorphism (p<0.001) independently predicted high rates of 8-iso-PGF2α excretion. Methionine loading increased plasma tHcy (p=0.002), and both urinary prostanoid metabolites (p=0.002). Folic acid supplementation was associated with decreased urinary 8-iso-PGF2α and 11-dehydro-TXB2 excretion (p<0.0003) in the hyperhomocysteinaemic group, but not in the control group, with substantial inter-individual variability related to baseline tHcy level and the extent of its reduction. In conclusion, hyperhomocysteinaemia due to the MTHFR 677 C→T polymorphism is associated with enhanced in vivo lipid peroxidation and platelet activation that are reversible, at least in part, following folic acid supplementation. An integrated biomarker approach may help identifying appropriate candidates for effective folate supplementation.

Serum homocysteine levels in acne patients

OBJECTIVE

This study was designed to investigate serum homocysteine (HCY) levels in acne patients.

METHODS

Acne patients (n = 124) and healthy volunteers (n = 70), matched in terms of both age and sex, were enrolled. Serum HCY levels for all subjects were measured by a clinical laboratory.

RESULTS

Serum HCY levels in male and female patients with severe and moderate acne were significantly higher than in the healthy control group (P < .05). The constituent ratio of male and female acne patients with HCY above the normal range (10 mmol/L) was significantly higher than the healthy control group. The severity of acne patients was positively correlated with serum homocysteine concentration, (P < .01).

CONCLUSION

Hyperhomocysteinemia may be an independent risk factor for acne vulgaris. Detection of serum HCY is important for acne patients.

Plasma proteomics reveals coagulation, inflammation, and metabolic shifts in H-type hypertension patients with and without acute ischemic stroke

Systematic profiling of a larger portion of circulating plasma proteome provide opportunities for unbiased discovery of novel markers to improve diagnostic, therapeutic, or predictive accuracy. This study aimed to identify differentially expressed proteins (DEPs) in plasma that could provide overall insight into the molecular changes of both H- type hypertension (HH) and HH-related acute ischemic stroke (AIS). This study used an iTRAQ-based LC-MS/MS proteomics approach to screen for plasma DEPs in HH patients with and without AIS, and controls. After excluding highly abundant plasma proteins, more than 600 proteins, and their relative levels, were identified. Of these, 26 DEPs, each showing > 1.2-fold change, were identified in HH and HH-related AIS patients compared with controls. Bioinformatics analysis revealed that these DEPs were enriched in 21 functional gene ontology items; “blood coagulation” was the most predominant pathway showing enrichment. Of these, eight DEPs were located in the hub position of networks involved with protein-protein interactions. AT-3, CRP, ApoB, and AHSG were further validated in each group by enzyme-linked immune sorbent assays. Comparing HH-related AIS with HH, the areas under the curve for AT-3, CRP, ApoB, and AHSG were 0.698, 0.892, 0.626, and 0.847, respectively. This proteomic profiling study provided enhanced pathophysiological understanding of the regulatory processes involved in coagulation, inflammation, and metabolism, and identified a panel of novel biomarkers for detecting HH-related AIS during its pre-stroke stage.

Impact of exudative diathesis induced by selenium deficiency on LncRNAs and their roles in the oxidative reduction process in broiler chick veins

Selenium deficiency may induce exudative diathesis (ED) in broiler chick, and this damage is closely related to oxidative damage. Long noncoding RNA (LncRNA) can regulate the redox state in vivo. The aim of the present study was to clarify the LncRNA expression profile in broiler veins and filter and verify the LncRNAs related to oxidative damage of ED. This study established an ED model induced by selenium deficiency and presented the expression and characterization of LncRNAs in normal and ED samples. A total of 15412 LncRNAs (including 8052 novel LncRNAs) were generated in six cDNA libraries using the Illumina Hi-Seq 4000 platform. 635 distinct changes in LncRNAs (up-regulated fold change > 1.5, down-regulated fold change < 0.67 and differentially expressed LncRNAs) were filtered. Gene ontology enrichment on LncRNAs target genes showed that the oxidative reduction process was important. This study also defined and verified 19 target mRNAs of 23 LncRNAs related to the oxidative reduction process. The in vivo and vitro experiments also demonstrated these 23 LncRNAs can participate in the oxidative reduction process. This study presents LncRNAs expression profile in broiler chick veins for the first time and confirmed 23 LncRNAs involving in the vein oxidative damage in ED.

Homocysteine Induces Apoptosis of Human Umbilical Vein Endothelial Cells via Mitochondrial Dysfunction and Endoplasmic Reticulum Stress

Homocysteine- (Hcy-) induced endothelial cell apoptosis has been suggested as a cause of Hcy-dependent vascular injury, while the proposed molecular pathways underlying this process are unclear. In this study, we investigated the adverse effects of Hcy on human umbilical vein endothelial cells (HUVEC) and the underlying mechanisms. Our results demonstrated that moderate-dose Hcy treatment induced HUVEC apoptosis in a time-dependent manner. Furthermore, prolonged Hcy treatment increased the expression of NOX4 and the production of intracellular ROS but decreased the ratio of Bcl-2/Bax and mitochondrial membrane potential (MMP), resulting in the leakage of cytochrome c and activation of caspase-3. Prolonged Hcy treatment also upregulated glucose-regulated protein 78 (GRP78), activated protein kinase RNA-like ER kinase (PERK), and induced the expression of C/EBP homologous protein (CHOP) and the phosphorylation of NF-κb. The inhibition of NOX4 decreased the production of ROS and alleviated the Hcy-induced HUVEC apoptosis and ER stress. Blocking the PERK pathway partly alleviated Hcy-induced HUVEC apoptosis and the activation of NF-κb. Taken together, our results suggest that Hcy-induced mitochondrial dysfunction crucially modulated apoptosis and contributed to the activation of ER stress in HUVEC. The excessive activation of the PERK pathway partly contributed to Hcy-induced HUVEC apoptosis and the phosphorylation of NF-κb.

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.

Sulfheme formation during homocysteine S-oxygenation by catalase in cancers and neurodegenerative diseases

Accumulating evidence suggests that abnormal levels of homocysteine are associated with vascular dysfunctions, cancer cell proliferation and various neurodegenerative diseases. With respect to the latter, a perturbation of transition metal homeostasis and an inhibition of catalase bioactivity have been reported. Herein, we report on some of the molecular bases for the cellular toxicity of homocysteine and demonstrate that it induces the formation of sulfcatalase, an irreversible inactive state of the enzyme, without the intervention of hydrogen sulfide. Initially, homocysteine reacts with native catalase and/or redox-active transition metal ions to generate thiyl radicals that mediate compound II formation, a temporarily inactive state of the enzyme. Then, the ferryl centre of compound II intervenes into the unprecedented S-oxygenation of homocysteine to engender the corresponding sulfenic acid species that further participates into the prosthetic heme modification through the formation of an unusual Fe(II) sulfonium. In addition, our ex cellulo studies performed on cancer cells, models of neurodegenerative diseases and ulcerative colitis suggest the likelihood of this scenario in a subset of cancer cells, as well as in a cellular model of Parkinson's disease. Our findings expand the repertoire of heme modifications promoted by biological compounds and point out another deleterious trait of disturbed homocysteine levels that could participate in the aetiology of these diseases.

High levels of homocysteine in cells are linked to pathological states. Here, the authors report that homocysteine inactivates catalase by modifying the heme group, impairing cellular redox homeostasis, and show that this modification occurs in cancer cells and in a cellular model of Parkinson's disease.

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.

Association of methionine synthase gene polymorphisms with wool production and quality traits in Chinese Merino population

Methionine synthase (MTR) plays a crucial role in maintaining homeostasis of intracellular methionine, folate, and homocysteine, and its activity correlates with DNA methylation in many mammalian tissues. Our previous genomewide association study identified that 1 SNP located in the gene was associated with several wool production and quality traits in Chinese Merino. To confirm the potential involvement of the gene in sheep wool production and quality traits, we performed sheep tissue expression profiling, SNP detection, and association analysis with sheep wool production and quality traits. The semiquantitative reverse transcription PCR analysis showed that the gene was differentially expressed in skin from Merino and Kazak sheep. The sequencing analysis identified a total of 13 SNP in the gene from Chinese Merino sheep. Comparison of the allele frequencies revealed that these 13 identified SNP were significantly different among the 6 tested Chinese Merino strains ( < 0.001). Linkage disequilibrium analysis showed that SNP 3 to 11 were strongly linked in a single haplotype block in the tested population. Association analysis showed that SNP 2 to 11 were significantly associated with the average wool fiber diameter and the fineness SD and that SNP 4 to 11 were significantly associated with the CV of fiber diameter trait ( < 0.05). Single nucleotide polymorphism 2 and SNP 5 to 12 were weakly associated with wool crimp. Similarly, the haplotypes derived from these 13 identified SNP were also significantly associated with the average wool fiber diameter, fineness SD, and the CV of fiber diameter ( < 0.05). Our results suggest that is a candidate gene for sheep wool production and quality traits, and the identified SNP might be used in sheep breeding.

The Effects of Folate Supplementation on Carotid Intima-Media Thickness and Metabolic Status in Patients with Metabolic Syndrome

BACKGROUND

This study was carried out to evaluate the effects of folate supplementation on carotid intima-media thickness (CIMT) and metabolic status among patients with metabolic syndrome (MetS).

METHODS

This randomized, double-blind, placebo-controlled trial was conducted among 60 patients with type 2 diabetes mellitus and coronary heart disease. They were all overweight in the age range 40-85 years. Participants were randomly divided into 2 groups: group A (n = 30) received 5 mg folate supplements and group B (n = 30) received placebo for 12 weeks.

RESULTS

Folate supplementation resulted in a significant reduction in maximum levels of left CIMT (-0.05 ± 0.13 vs. +0.02 ± 0.11 mm, p = 0.01) compared with the placebo. Changes in fasting plasma glucose (-2.2 ± 37.5 vs. +30.2 ± 65.8 mg/dl, p = 0.02), serum insulin concentration (-2.0 ± 10.7 vs. +3.0 ± 7.6 µIU/ml, p = 0.04) and homeostasis of assessment-estimated insulin resistance (-0.6 ± 2.3 vs. +0.9 ± 2.3, p = 0.01) in supplemented patients were significantly different from those of patients in the placebo group. Changes in serum triglycerides (p = 0.04), high-density lipoprotein-cholesterol (p = 0.001), high sensitivity C-reactive protein (p = 0.01) and plasma nitric oxide concentrations (p < 0.001) were significantly different between the supplemented patients and placebo group.

CONCLUSIONS

Overall, 5 mg/day folate supplementation for 12 weeks among patients with MetS had beneficial effects on CIMT and the metabolic status.

The Perioperative Use of Albumin

Human serum albumin (HSA) is the predominant product of hepatic protein synthesis and one of the more abundant plasma proteins. HSA is a monomeric multidomain macromolecule, representing the main determinant of plasma oncotic pressure and the main modulator of fluid distribution between body compartments. HSA displays an essential role in maintaining the integrity of the vascular barrier. HSA is the most important antioxidant capacity of human plasma, in addition to its ability to protect the body from the harmful effects of heavy metals such as iron and copper and reduce their ability to produce reactive oxygen radicals. HSA is the main depot for nitric oxide (NO) transport in the blood. HSA represents the main carrier for fatty acids, affects pharmacokinetics of many drugs, and provides the metabolic modification of some drugs and displays pseudo-enzymatic properties. HSA has been widely used successfully for more than 50 years in many settings of perioperative medicine including hypovolemia, shock, burns, surgical blood loss, sepsis, and acute respiratory distress syndrome (ARDS). Recently, the use of HSA has shown a promising neuroprotective effect in patients with subarachnoid hemorrhage. The most recent evidence-based functions and uses of HSA in the perioperative period are reviewed in this chapter.

High levels of homocysteine downregulate apolipoprotein E expression via nuclear factor kappa B

AIM: To investigate the effect of high homocysteine (Hcy) levels on apolipoprotein E (apoE) expression and the signaling pathways involved in this gene regulation.

METHODS: Reverse transcriptase polymerase chain reaction (RT-PCR) and Western blot were used to assess apoE expression in cells treated with various concentrations (50-500 μmol/L) of Hcy. Calcium phosphate-transient transfections were performed in HEK-293 and RAW 264.7 cells to evaluate the effect of Hcy on apoE regulatory elements [promoter and distal multienhancer 2 (ME2)]. To this aim, plasmids containing the proximal apoE promoter [(-500/+73)apoE construct] alone or in the presence of ME2 [ME2/(-500/+73)apoE construct] to drive the expression of the reporter luciferase gene were used. Co-transfection experiments were carried out to investigate the downstream effectors of Hcy-mediated regulation of apoE promoter by using specific inhibitors or a dominant negative form of IKβ. In other co-transfections, the luciferase reporter was under the control of synthetic promoters containing multiple specific binding sites for nuclear factor kappa B (NF-κB), activator protein-1 (AP-1) or nuclear factor of activated T cells (NFAT). Chromatin immunoprecipitation (ChIP) assay was accomplished to detect the binding of NF-κB p65 subunit to the apoE promoter in HEK-293 treated with 500 μmol/L Hcy. As control, cells were incubated with similar concentration of cysteine. NF-κB p65 proteins bound to DNA were immunoprecipitated with anti-p65 antibodies and DNA was identified by PCR using primers amplifying the region -100/+4 of the apoE gene.

RESULTS: RT-PCR revealed that high levels of Hcy (250-750 μmol/L) induced a 2-3 fold decrease in apoE mRNA levels in HEK-293 cells, while apoE gene expression was not significantly affected by treatment with lower concentrations of Hcy (100 μmol/L). Immunoblotting data provided additional evidence for the negative role of Hcy in apoE expression. Hcy decreased apoE promoter activity, in the presence or absence of ME2, in a dose dependent manner, in both RAW 264.7 and HEK-293 cells, as revealed by transient transfection experiments. The downstream effectors of the signaling pathways of Hcy were also investigated. The inhibitory effect of Hcy on the apoE promoter activity was counteracted by MAPK/ERK kinase 1/2 (MEK1/2) inhibitor U0126, suggesting that MEK1/2 is involved in the downregulation of apoE promoter activity by Hcy. Our data demonstrated that Hcy-induced inhibition of apoE took place through activation of NF-κB. Moreover, we demonstrated that Hcy activated a synthetic promoter containing three NF-κB binding sites, but did not affect promoters containing AP-1 or NFAT binding sites. ChIP experiments revealed that NF-κB p65 subunit is recruited to the apoE promoter following Hcy treatment of cells.

CONCLUSION: Hcy-induced stress negatively modulates apoE expression via MEK1/2 and NF-κB activation. The decreased apoE expression in peripheral tissues may aggravate atherosclerosis, neurodegenerative diseases and renal dysfunctions.

Effects of long-term folate supplementation on metabolic status and regression of cervical intraepithelial neoplasia: A randomized, double-blind, placebo-controlled trial

OBJECTIVE

This study was conducted to determine the effects of long-term folate supplementation on regression and metabolic status of patients with cervical intraepithelial neoplasia grade 1 (CIN1).

METHODS

This randomized, double-blind, placebo-controlled trial was performed among 58 women diagnosed with CIN1, ages 18 to 55 y old. Participants were randomly divided into two groups to receive 5 mg/d folate supplements (n = 29) or placebo (n = 29) for 6 mo. Fasting blood samples were taken at baseline and 6 mo after intervention to quantify related markers.

RESULTS

A greater percentage of women in the folate group had regressed CIN1 (83.3 versus 52.0%, P = 0.019) than those in the placebo group. Long-term folate supplementation resulted in a significant decrease in serum insulin levels (-1.6 ± 6.2 versus +2.6 ± 6.9 μIU/mL, P = 0.018) and homeostatic model assessment-beta cell function (HOMA-B) (-13.0 ± 39.0 versus +11.2 ± 42.3, P = 0.028) compared with the placebo. Additionally, plasma glutathione (GSH) levels were significantly increased (+81.5 ± 264.1 versus -220.9 ± 342.5 μmol/L, P < 0.001) and malondialdehyde (MDA) levels were significantly reduced (-1.0 ± 1.1 versus +0.1 ± 1.6 μmol/L, P = 0.004) in the folate group compared to the placebo.

CONCLUSIONS

Taken together, folate supplementation (5 mg/d) for 6 mo among women with CIN1 resulted in its regression as well as led to decreased serum insulin, HOMA-B, plasma MDA and increased plasma GSH levels; however, it did not affect other metabolic profiles.

Pathological concentrations of homocysteine increases IL-1β production in macrophages in a P2X7, NF-ĸB, and erk-dependent manner

Elevated plasma levels of homocysteine (Hcy) are associated with the development of coronary artery disease (CAD), peripheral vascular disease, and atherosclerosis. Hyperhomocysteinemia is likely related to the enhanced production of pro-inflammatory cytokines including IL-1β. However, the mechanisms underlying the effects of Hcy in immune cells are not completely understood. Recent studies have established a link between macrophage accumulation, cytokine IL-1β, and the advance of vascular diseases. The purpose of the present study is to investigate the effects of Hcy on IL-1β secretion by murine macrophages. Hcy (100 μM) increases IL-1β synthesis via enhancement of P2X7 expression and NF-ĸB and ERK activation in murine macrophages. In addition, the antioxidant agent N-acetylcysteine (NAC) reduces NF-κB activation, ERK phosphorylation, and IL-1β production in Hcy-exposed macrophages, indicating the importance of ROS in this pro-inflammatory process. In summary, our results show that Hcy may be involved in the synthesis and secretion of IL-1β via NF-ĸB, ERK, and P2X7 stimulation in murine macrophages.

Autologous Bone Marrow Mononuclear Cell Transplantation Delays Progression of Carotid Atherosclerosis in Rabbits

Bone marrow mononuclear cells (BMMNCs) can counteract oxidative stress and inhibit the inflammatory response in focal ischemic stroke models. However, the effect of BMMNC transplantation on carotid atherosclerosis needs to be determined. The carotid atherosclerotic plaque model was established in New Zealand White rabbits by balloon injury and 8 weeks of high-fat diet. Rabbits were randomized to receive an intravenous injection of autologous bromodeoxyuridine (BrdU)-labeled BMMNCs or an equal volume of phosphate-buffered saline. Plaques were evaluated for expression of proinflammatory and anti-inflammatory cytokines, anti-oxidant proteins, and markers of cell death. BMMNCs migrated into atherosclerotic plaque on the first day after cell transplantation. BMMNC-treated rabbits had smaller plaques and more collagen deposition than did the vehicle-treated controls on day 28 (p < 0.05). BMMNC treatment significantly increased endothelial nitric oxide synthase and the anti-oxidant enzymes glutathione peroxidase and superoxide dismutase in plaques compared to vehicle treatment on day 7. BMMNC-treated rabbits also had lower levels of cleaved caspase-3 expression; lower levels of proinflammatory cytokines interleukin-1β, tumor necrosis factor alpha, and matrix metalloproteinase 9; and higher levels of insulin-like growth factor-1 and its receptor (p < 0.05). Autologous BMMNC transplantation can suppress the process of atherosclerotic plaque formation and is associated with enhanced anti-oxidative effect, reduced levels of inflammatory cytokines and cleaved caspase-3, and increased expression of insulin-like growth factor-1 and its receptor. BMMNC transplantation represents a novel approach for the treatment of carotid atherosclerosis.

Emodin Inhibits Homocysteine-Induced C-Reactive Protein Generation in Vascular Smooth Muscle Cells by Regulating PPARγ Expression and ROS-ERK1/2/p38 Signal Pathway

Atherosclerosis is an inflammatory disease. As an inflammatory molecule, C-reactive protein (CRP) plays a direct role in atherogenesis. It is known that the elevated plasma homocysteine (Hcy) level is an independent risk factor for atherosclerosis. We previously reported that Hcy produces a pro-inflammatory effect by inducing CRP expression in vascular smooth muscle cells (VSMCs). In the present study, we observed effect of emodin on Hcy-induced CRP expression in rat VSMCs and molecular mechanisms. The in vitro results showed that pretreatment of VSMCs with emodin inhibited Hcy-induced mRNA and protein expression of CRP in a concentration-dependent manner. The in vivo experiments displayed that emodin not only inhibited CRP expression in the vessel walls in mRNA and protein levels, but also reduced the circulating CRP level in hyperhomocysteinemic rats. Further study revealed that emodin diminished Hcy-stimulated generation of reactive oxygen species (ROS), attenuated Hcy-activated phosphorylation of ERK1/2 and p38, and upregulated Hcy-inhibited expression of peroxisome proliferator-activated receptor gamma (PPARγ) in VSMCs. These demonstrate that emodin is able to inhibit Hcy-induced CRP generation in VSMCs, which is related to interfering with ROS-ERK1/2/p38 signal pathway and upregulating PPARγ expression. The present study provides new evidence for the anti-inflammatory and anti-atherosclerotic effects of emodin.

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.

Impact of physical activity and cardiovascular fitness on total homocysteine concentrations in European adolescents: The HELENA study

We examined the association of physical activity (PA), cardiovascular fitness (CVF) and fatness with total homocysteine (tHcy) concentrations in European adolescents. The present study comprised 713 European adolescents aged 14.8 ± 1.2 y (females 55.3%) from the multicenter HELENA cross-sectional study. PA was assessed through accelerometry, CVF by the 20-m shuttle run test, and body fat by skinfold thicknesses with the Slaughter equation. Plasma folate, cobalamin, and tHcy concentrations were measured. To examine the association of tHcy with PA, CVF, and fatness after controlling for a set of confounders including age, maturity, folate, cobalamin, creatinine, smoking, supplement use, and methylenetetrahydrofolate reductase 677 genotype (CC 47%, CT 43%, TT 10%), bivariate correlations followed by multiple regression models were performed. In the bivariate correlation analysis, tHcy concentrations were slightly negatively correlated (p<0.05) with CVF in females (measured both by stages: r=-0.118 and by VO2max: r=-0.102) and positively with body mass index (r=0.100). However, daily time spent with moderate and vigorous PA showed a weak positive association with tHcy in females (p<0.05). tHcy concentrations showed a tendency to decrease with increasing CVF and increase with increasing BMI in female European adolescents. However, tHcy concentrations were positively associated with moderate and vigorous PA in female European adolescents.

Effect of long-term supplementation with folic acid and B vitamins on risk of depression in older women

BACKGROUND

Homocysteine-lowering nutrients may have preventive/ameliorative roles in depression.

AIMS

To test whether long-term B-vitamin/folate supplementation reduces depression risk.

METHOD

Participants were 4331 women (mean age 63.6 years), without prior depression, from the Women's Antioxidant and Folic Acid Cardiovascular Study - a randomised controlled trial of cardiovascular disease prevention among 5442 women. Participants were randomly assigned to receive a combination of folic acid (2.5 mg/d), vitamin B6 (50 mg/d) and vitamin B12 (1 mg/d) or a matching placebo. Average treatment duration was 7 years. The outcome was incident depression, defined as self-reported physician/clinician-diagnosed depression or clinically significant depressive symptoms.

RESULTS

There were 524 incident cases. There was no difference between active v. placebo groups in depression risk (adjusted relative risk 1.02, 95% CI 0.86-1.21, P = 0.81), despite significant homocysteine level reduction.

CONCLUSIONS

Long-term, high-dose, daily supplementation with folic acid and vitamins B6 and B12 did not reduce overall depression risk in mid-life and older women.

Helicobacter pylori seropositivity's association with markers of iron, 1-carbon metabolism, and antioxidant status among US adults: a structural equations modeling approach

Objectives

We tested a model in which Helicobacter pylori seropositivity (Hp_s) predicted iron status, which in turn acted as a predictor for markers of 1-C metabolism that were then allowed to predict antioxidant status.

Methods

National Health and Nutrition Examination Surveys (NHANES 1999–2000) cross-sectional data among adults aged 20–85 y were analyzed (n = 3,055). Markers of Hp_s, iron status (serum ferritin and transferrin saturation (TS)); 1-C metabolism (serum folate (FOL_serum), B-12, total homocysteine (tHcy), methylmalonic acid (MMA)) and antioxidant status (vitamins A and E) were entered into a structural equations model (SEM).

Results

Predictors of Hp_s included older age, lower education and income, racial/ethnic groups (lowest among Non-Hispanic Whites), and lifetime cigarette smoking. SEM modeling indicated that Hp_s had a direct inverse relationship with iron status (combining serum ferritin and TS) which in turn was positively related to 1-C metabolites (higher serum folate, B-12 or lower tHcy/MMA) that were positively associated with antioxidant status (combining serum vitamins A and E). Another pathway that was found bypassed 1-C metabolites (Hps → Iron_st → Antiox). The sum of all indirect effects from Hp_s combining both pathways and the other indirect pathways in the model (Hps → Iron_st → OneCarbon; Hps →OneCarbon →Antiox) was estimated at β = -0.006±0.003, p<0.05.

Conclusions

In sum, of the total effect of H. pylori seropositivity on antioxidant status, two significant indirect pathways through Iron status and 1-Carbon metabolites were found. Randomized controlled trials should be conducted to uncover the concomitant causal effect of H. pylori eradication on improving iron status, folate, B-12 and antioxidant status among H. pylori seropositive individuals.

Vitamin B status in patients with type 2 diabetes mellitus with and without incipient nephropathy

AIM

To investigate the vitamin B status, with particular focus on vitamin B6, in adults with and without incipient nephropathy secondary to type 2 diabetes mellitus.

METHODS

Plasma and/or urine concentrations of vitamins B₆, B₁, B₁₂, related vitamers and biomarkers (including total homocysteine, methylmalonic acid) were measured in 120 adults with type 2 diabetes (including 46 patients with microalbuminuria) and 52 non-diabetic control subjects.

RESULTS

Plasma concentrations of pyridoxal 5'-phosphate (PLP) were significantly lower in patients with type 2 diabetes than in control subjects (median: 22.7 nmol/L, diabetes with microalbuminuria; 26.8 nmol/L, diabetes without microalbuminuria; 39.5 nmol/L, non-diabetic control; p<0.0001). The prevalence of low PLP (<30 nmol/L) was 63%, 58%, and 25% in the diabetes groups with and without microalbuminuria and the control group, respectively. Plasma levels of pyridoxine and pyridoxal were also lower (p<0.0001), but levels of pyridoxamine, pyridoxamine 5'-phosphate, and pyridoxic acid were higher in both groups with diabetes compared to the control group (p<0.001). Thiamine deficiency was highly prevalent in all groups, whereas low vitamin B₁₂ and elevated methylmalonic acid were rare. Increased levels of C-reactive protein and soluble vascular cell adhesion molecule-1 were observed in the groups with diabetes (p<0.05, versus healthy control).

CONCLUSIONS

Deficiency of vitamin B₆ (PLP, pyridoxine, pyridoxal) and vitamin B₁ (thiamine) was prevalent in type 2 diabetes. Incipient nephropathy was associated with more pronounced alterations in vitamin B₆ metabolism and stronger indications of endothelial dysfunction and inflammation.

Epigenetic reprogramming in atherosclerosis

Recent data support the involvement of epigenetic alterations in the pathogenesis of atherosclerosis. The most widely investigated epigenetic mechanism is DNA methylation although also histone code changes occur during the diverse steps of atherosclerosis, such as endothelial cell proliferation, vascular smooth muscle cell (SMC) differentiation, and inflammatory pathway activation. In this review, we focus on the main genes that are epigenetically modified during the atherogenic process, particularly nitric oxide synthase (NOS), estrogen receptors (ERs), collagen type XV alpha 1 (COL15A1), vascular endothelial growth factor receptor (VEGFR), and ten-eleven translocation (TET), which are involved in endothelial dysfunction; gamma interferon (IFN-γ), forkhead box p3 (FOXP3), and tumor necrosis factor-α (TNF-α), associated with atherosclerotic inflammatory process; and p66shc, lectin-like oxLDL receptor (LOX1), and apolipoprotein E (APOE) genes, which are regulated by high cholesterol and homocysteine (Hcy) levels. Furthermore, we also discuss the role of non-coding RNAs (ncRNA) in atherosclerosis. NcRNAs are involved in epigenetic regulation of endothelial function, SMC proliferation, cholesterol synthesis, lipid metabolism, and inflammatory response.

The effects of folate supplementation on inflammatory factors and biomarkers of oxidative stress in overweight and obese women with polycystic ovary syndrome: a randomized, double-blind, placebo-controlled clinical trial

OBJECTIVE

This study was conducted to determine the effects of folate supplementation on inflammatory factors and biomarkers of oxidative stress among women with polycystic ovary syndrome (PCOS).

DESIGN, PATIENTS AND MEASUREMENTS

This randomized, double-blind, placebo-controlled clinical trial was conducted among 69 women diagnosed with PCOS and aged 18-40 year old. Participants were randomly assigned to three groups receiving the following: (1) folate-1: 1 mg/d folate supplements (N = 23); (2) folate-5: 5 mg/d folate supplements (N = 23) and (3) placebo (N = 23) for 8 weeks. Fasting blood samples were taken at the beginning of the study and after 8 weeks to measure homocysteine (Hcy), inflammatory factors including high-sensitivity C-reactive protein (hs-CRP), nitric oxide (NO), biomarkers of oxidative stress including total antioxidant capacity (TAC), glutathione (GSH), malondialdehyde (MDA) and homoeostatic model assessment-beta cell function (HOMA-B).

RESULTS

Supplementation with 5 mg/d folate resulted in reduced plasma Hcy (-2·23 vs -1·86 and 1·16 μm, respectively, P < 0·05), HOMA-B (-7·63 vs 1·43 and 13·66, respectively, P < 0·05), serum hs-CRP (-212·2 vs -262·4 and 729·8 μg/l, respectively, P < 0·05) and plasma MDA concentrations (-0·48 vs -0·24 and 0·69 μm, respectively, P < 0·01) compared with folate-1 and placebo groups. Furthermore, a significant rise in plasma TAC (0·64 vs -3·53 and -215·47 mm, respectively, P < 0·01) and GSH levels (162·1 vs 195·8 and -158·2 μm, respectively, P < 0·01) was also observed following the administration of 5 mg/d folate supplements compared with folate-1 and placebo groups.

CONCLUSIONS

In conclusion, folate supplementation (5 mg/d) in women with PCOS had beneficial effects on inflammatory factors and biomarkers of oxidative stress.

High‑dose folic acid improves endothelial function by increasing tetrahydrobiopterin and decreasing homocysteine levels

The aim of this study was to investigate the effect of folic acid (FA) on tetrahydrobiopterin (BH4), neopterin, nitric oxide (NO) and homocysteine (Hcy) levels in endothelial cells. Human umbilical vein endothelial cells (HUVECs) were cultured in vitro in the presence or absence of Hcy. The effect of various doses of FA on Hcy, BH4, neopterin and NO concentrations in HUVECs was then assessed. In the 5 and 10 nmol/l FA treatment groups, FA was found to significantly increase the levels of BH4 (10.56±3.86 and 11.23±2.1919 pmol/g vs 6.32+2.87 nmol/g; P<0.05 vs. control) and NO production (37.86±12.34 nmol/l, 38.45±11.23 nmol/l vs 26.21±9.24 nmol/l; P<0.001 vs. paired Hcy group), but reduce the levels of Hcy (132.87±29.67 and 140.87±26.76 nmol/l vs. 165.23±30.56 nmol/l; P<0.05 vs. Hcy group). No significant differences were observed in neopterin levels among the different groups of HUVECs. In conclusion, high doses of FA may be capable of protecting endothelial cells through reducing levels of Hcy and increasing BH4 and NO production.

Sulforaphane attenuates homocysteine-induced endoplasmic reticulum stress through Nrf-2-driven enzymes in immortalized human hepatocytes

In the present study, we investigated the potential efficacy of cruciferous vegetable-derived sulforaphane (SFN) in improving homocysteine (HCY)-stressed cells. After human hepatocyte line HHL-5 was preincubated with SFN and subsequently with 10 mmol/L HCY, SFN improved the pathologic changes which are caused by HCY, including cell morphological abnormality, endoplasmic reticulum (ER) swelling, excessive generation of reactive oxygen species (ROS), the increased malondialdehyde (MDA) levels, as well as the increased activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Phase II enzymes, thioredoxin reductase-1 (TrxR-1) and

NAD(P)H

quinone oxidoreductase 1 (NQO1), were involved in the protective effect of SFN against injury by HCY. The ER stress-specific proteins, such as glucose-regulated protein-78 (GRP78) and protein kinase RNA (PKR)-like ER kinase (PERK), were strikingly abolished by SFN. Furthermore, Nrf-2 translocation was enhanced by SFN, which lead to the induction of TrxR-1and NQO1.

Increased pulse wave velocity and relationship with inflammation, insulin, and insulin resistance in inflammatory bowel disease

OBJECTIVE

Both ulcerative colitis and Crohn's disease are forms of inflammatory bowel disease (IBD), which is characterized by chronic, progressive inflammation of the gastrointestinal tract. Recent studies have shed new light on the importance of inflammation in the pathogenesis of arterial stiffness.

AIM

This study aimed to evaluate the relationship between pulse wave velocity (PWV) measurement and biochemical parameters in inactive and active IBD patients without cardiovascular risk factors and perform a comparison with the control group.

MATERIALS AND METHODS

We enrolled 102 IBD patients without cardiovascular risk factors and 74 matched controls, and evaluated each patient in active and inactive disease periods. All patients completed a standard questionnaire form and we assessed various laboratory parameters. We carried out vascular measurements using a Mobil-O-Graph 24-h pulse wave analysis monitor, an automatic oscillometric device.

RESULTS

Although cardiovascular risk factors, such as total cholesterol and low-density lipoprotein cholesterol, were significantly lower (P<0.05) in IBD patients than the controls, 24 h, day and night PWV values, erythrocyte sedimentation rate, C-reactive protein, insulin, homeostasis model assessment of insulin resistance, and homocysteine were higher in patients with active and inactive IBD than the controls (P<0.05). Multiple linear regression analysis showed that PWV was correlated positively with age and duration of IBD.

CONCLUSION

This study showed increased PWV, homocysteine, erythrocyte sedimentation rate, C-reactive protein, insulin, and homeostasis model assessment of insulin resistance in patients with active and inactive IBD and provides evidence of the potential contribution of inflammation and inflammation-related factors toward arterial stiffening independent from conventional cardiovascular risk factors.

Homocysteine induces the expression of C-reactive protein via NMDAr-ROS-MAPK-NF-κB signal pathway in rat vascular smooth muscle cells

OBJECTIVE

Homocysteine (Hcy) is known as an independent risk factor for atherosclerosis. C-reactive protein (CRP) directly participates in initiation and progression of atherosclerosis. However, there is no direct evidence to demonstrate pro-inflammatory effect of Hcy on vascular smooth muscle cells (VSMCs) through CRP. In the present study, we examined the effect of Hcy on CRP expression and investigated the related mechanism in VSMCs.

METHODS AND RESULTS

Protein expression and secretion were detected by Western blot and ELISA, respectively. mRNA expression was detected by RT-PCR. Superoxide anion was detected by lucigenin chemiluminometry and the immunofluorescence staining was observed by a fluorescence microscope. The results revealed that Hcy significantly induced mRNA and protein expressions of CRP in VSMCs both in vitro and in vivo, and anti-IL-1β or anti-IL-6 neutralizing antibody alone or in combination partially reduced Hcy-induced CRP expression. Hcy increased the expression of NR1 subunit of N-methyl-d-aspartate receptor (NMDAr), and MK-801 alleviated Hcy-induced CRP expression in VSMCs. Further studies showed that Hcy-stimulated superoxide anion generation in VSMCs. Nevertheless, pretreatment of the cells with MK-801, TTFA and DPI significantly reduced Hcy-stimulated superoxide anion generation, and antioxidant NAC decreased Hcy-induced CRP expression in VSMCs. Additionally, PD98059, SB205380 or PDTC antagonized Hcy-induced CRP expression, and MK-801, NAC, PD98059 or SB205380 inhibited Hcy-activated phosphorylations of ERK1/2 and p38.

CONCLUSION

The present study demonstrates that Hcy is able to initiate an inflammatory response in VSMCs by stimulating CRP production, which is mediated through NMDAr-ROS-ERK1/2/p38-NF-κB signal pathway. These findings provide new evidence for a role of Hcy in pathogenesis of atherosclerosis.

Increased resistance to malaria in mice with methylenetetrahydrofolate reductase (Mthfr) deficiency suggests a mechanism for selection of the MTHFR 677C>T (c.665C>T) variant

The polymorphism 677C>T (NM_005957.4:c.665C>T/p.Ala222Val, rs1801133:C>T) in methylenetetrahydrofolate reductase (MTHFR) results in mild enzymatic deficiency and increased risk for several complex traits including adverse reproductive outcomes, birth defects, and heart disease. Despite these deleterious effects, homozygosity is high (5%-15%) in many populations, and among the highest in Mediterranean regions, where malaria was historically endemic and may have conferred a selective advantage for other mutations. We infected Mthfr-deficient (Mthfr(+) (/-) ) and MTHFR overexpressing (MTHFR(Tg) ) mice with Plasmodium berghei ANKA to induce cerebral malaria. Mthfr(+/-) mice survived longer (P < 0.02, log-rank test), and MTHFR(Tg) mice died earlier (P < 0.05, log-rank test) after infection compared with wild-type littermates. Flow cytometry revealed increased lymphocyte populations and increased CCR4(+) NK cells in spleen of Mthfr(+) (/-) mice; MTHFR(Tg) animals had decreased numbers of these NK cells. Interferon-γ and interleukin-10 immunoreactive proteins were increased and decreased, respectively, in brain of Mthfr(+/-) mice compared with wild-type. We suggest that mild MTHFR deficiency protects against malarial infection and that this phenomenon may have led to the high frequency of the 677C>T/c.665C>T variant in human populations.

Vitamin status as a determinant of serum homocysteine concentration in type 2 diabetic retinopathy

We investigated the association of serum homocysteine levels and vitamin status with type 2 diabetic retinopathy. This study included 65 patients with and 75 patients without diabetic retinopathy. Patients with diabetic retinopathy had significantly higher serum homocysteine levels (P < 0.001), higher prevalence of hyperhomocysteinemia (P < 0.001), lower serum folic acid (P < 0.001), and vitamin B12 (P = 0.014) levels than those without diabetic retinopathy. Regression analysis revealed that homocysteine was an independent risk factor for diabetic retinopathy and there was a threshold in its serum level (13.7  μ mol/L), above which the risk of diabetic retinopathy greatly increases (OR = 1.66, P = 0.001). Folic acid was associated with decreased odds for diabetic retinopathy (OR = 0.73, P < 0.001). There was a threshold in serum vitamin B12 level (248.4 pg/mL), below which serum homocysteine concentration significantly increases with decreasing serum vitamin B12 (P = 0.003). Our findings suggest that hyperhomocysteinemia is an independent risk factor for the development and progression of diabetic retinopathy. Decreased serum levels of folic acid and vitamin B12, through raising serum homocysteine concentrations, may also affect the diabetic retinopathy risk.

Plasma homocysteine levels increase following stress in older but not younger men

BACKGROUND

The incidence and prevalence of cardiovascular disease (CVD) increases with age. Some evidence suggests that mental stress may increase plasma homocysteine (Hcy), an amino acid relating to CVD. However, none of these studies assessed age effects on Hcy stress reactivity, nor did they control for age. The objective of this study was (a) to investigate whether Hcy reactivity to psychosocial stress differs between younger and middle-aged to older men and (b) to study whether psychosocial stress induces Hcy increases independent of age.

METHODS

Twenty eight younger (20-30 years) and 22 middle-aged to older (47-65 years) apparently healthy men underwent an acute standardized psychosocial stress task combining public speaking and mental arithmetic in front of an audience. Blood samples for Hcy measurements were obtained immediately before and after, as well as 10 and 20min after stress. Moreover, salivary cortisol was repeatedly measured to test the effectiveness of the stress task in triggering a neuroendocrine stress response.

RESULTS

Hcy reactivity to stress differed between age groups (F(1.4, 60.7)=5.41, p=.014). While the older group displayed an increase in the Hcy response to stress (F(2.5, 39.8)=3.86, p=.022), Hcy levels in the younger group did not change (p=.27). Psychosocial stress per se did not change Hcy levels independent of age (p=.53).

CONCLUSIONS

Our findings suggest that psychosocial stress does not evoke an Hcy response per se, but only in interaction with age pointing to a mechanism by which mental stress may increase CVD risk in older individuals.

Specific antioxidant properties of human serum albumin

Human serum albumin (HSA) has been used for a long time as a resuscitation fluid in critically ill patients. It is known to exert several important physiological and pharmacological functions. Among them, the antioxidant properties seem to be of paramount importance as they may be implied in the potential beneficial effects that have been observed in the critical care and hepatological settings. The specific antioxidant functions of the protein are closely related to its structure. Indeed, they are due to its multiple ligand-binding capacities and free radical-trapping properties. The HSA molecule can undergo various structural changes modifying its conformation and hence its binding properties and redox state. Such chemical modifications can occur during bioprocesses and storage conditions of the commercial HSA solutions, resulting in heterogeneous solutions for infusion. In this review, we explore the mechanisms that are responsible for the specific antioxidant properties of HSA in its native form, chemically modified forms, and commercial formulations. To conclude, we discuss the implication of this recent literature for future clinical trials using albumin as a drug and for elucidating the effects of HSA infusion in critically ill patients.

Molecular and cellular effects of vitamin B12 in brain, myocardium and liver through its role as co-factor of methionine synthase

Vitamin B12 (cobalamin, cbl) is a cofactor of methionine synthase (MTR) in the synthesis of methionine, the precursor of the universal methyl donor S-Adenosylmethionine (SAM), which is involved in epigenomic regulatory mechanisms. We have established a neuronal cell model with stable expression of a transcobalamin-oleosin chimer and subsequent decreased cellular availability of vitamin B12, which produces reduced proliferation, increased apoptosis and accelerated differentiation through PP2A, NGF and TACE pathways. Anti-transcobalamin antibody or impaired transcobalamin receptor expression produce also impaired proliferation in other cells. Consistently, the transcription, protein expression and activity of MTR are increased in proliferating cells of skin and intestinal epitheliums, in rat intestine crypts and in proliferating CaCo2 cells, while MTR activity correlates with DNA methylation in rat intestine villi. Exposure to nitrous oxide in animal models identified impairment of MTR reaction as the most important metabolic cause of neurological manifestations of B12 deficiency. Early vitamin B12 and folate deprivation during gestation and lactation of a 'dam-progeny' rat model developed in our laboratory is associated with long-lasting disabilities of behavior and memory capacities, with persisting hallmarks related to increased apoptosis, impaired neurogenesis and altered plasticity. We found also an epigenomic deregulation of energy metabolism and fatty acids beta-oxidation in myocardium and liver, through imbalanced methylation/acetylation of PGC-1alpha and decreased expression of SIRT1. These nutrigenomic effects display similarities with the molecular mechanisms of fetal programming. Beside deficiency, B12 loading increases the expression of MTR through internal ribosome entry sites (IRES) and down-regulates MDR-1 gene expression. In conclusion, vitamin B12 influences cell proliferation, differentiation and apoptosis in brain. Vitamin B12 and folate combined deficiency impairs fatty acid oxidation and energy metabolism in liver and heart through epigenomic mechanisms related to imbalanced acetylation/methylation. Some but not all of these effects reflect the upstream role of vitamin B12 in SAM synthesis.

Renal dysfunction in methylmalonic acidurias: review for the pediatric nephrologist

Methylmalonic acidurias are a heterogeneous group of inborn errors of branched-chain amino acid metabolism. Depending on the underlying etiology, acute or chronic renal disease constitutes major (long-term) complications. In recent decades, overall survival has improved due to optimized treatment strategies based on the use of standardized emergency protocols and dialysis techniques. The majority of these patients, especially those having mut°, cblB, and cblA deficiency, are at increased risk of developing chronic kidney disease secondary to tubulointerstitial nephritis to require hemo- or peritoneal dialysis. Kidney and/or liver transplantation, as organ replacement, or even gene therapy on a limited scale, are controversially discussed treatment options in methylmalonic acidurias. The pathophysiological basis of renal disease has not been clarified in detail until now, but a severe mitochondrial dysfunction and an impairment of tubular dicarboxylic acid transport due to accumulated toxic metabolic compounds has been recently proposed. Another severe renal complication of methylmalonic acidurias is the occurrence of cblC-associated infantile atypical hemolytic syndrome, which can result in acute kidney injury. Close collaboration between (pediatric) nephrologists and metabolic specialists is required for the long-term management of these patients.

[Correlation between plasma concentrations of homocysteine and diabetic polyneuropathy evaluated with the Semmes-Weinstein monofilament test in patients with type 2 diabetes mellitus]

BACKGROUND AND OBJECTIVE

Few modifiable risk factors are known to be associated with the presence and progression of diabetic polyneuropathy (DPN).

MATERIAL AND METHOD

We have analyzed in 405 type 2 diabetic (T2DM) subjects (169 women) the association of plasma homocysteine with the presence of DPN measured with the Semmes-Weinstein (SW) monofilament test. A score below 4 was considered an altered SW monofilament test. Plasma homocysteine, vitamin B12 and folic acid were measured using standard procedures (ELISA).

RESULTS

Patients with T2DM with altered SW test have significantly higher age, evolution of disease, HbA1c and lower creatinine clearance values. In addition, plasma homocysteine values were independently and significantly higher in T2DM with DPN measured as altered SW test (13.64 ± 4.93 vs. 12.22 ± 4.48 μmol/l, P<.01) with similar vitamin B12 and folic acid values comparing the 2 groups.

CONCLUSION

Plasma homocysteine and HbA1c values are the 2 modifiable biological factors associated with the presence of DPN evaluated as an altered SW monofilament test in T2DM subjects.

Aged garlic extract restores nitric oxide bioavailability in cultured human endothelial cells even under conditions of homocysteine elevation

ETHNOPHARMACOLOGICAL RELEVANCE

Supplementation with aged garlic extract (AGE) has been shown to restore impaired endothelium-dependent vasodilator response in subjects with acutely elevated plasma homocysteine (Hcy) levels after an oral methionine load and in patients with chronic coronary artery disease. Moreover, AGE has been shown to inhibit the progression of coronary calcifications in patients with coronary artery disease. The molecular mechanisms, by which AGE preserves endothelial function is unknown. Our objective was to explore whether AGE preserves endothelial nitric oxide (NO) output even under conditions of elevated Hcy levels by preventing oxidative inactivation of the NO synthase cofactor tetrahydrobiopterin.

MATERIAL AND METHODS

Endothelial (EA.hy 926) cells were incubated with hypoxanthine, aminopterin, thymidine and methionine (HAT/MET) to increase cellular Hcy levels, and with and without AGE. Agonist stimulated NO output was measured using the fluorescent probe DAF-2, and cellular thiol levels (Hcy, cysteine, reduced and oxidized glutathione) and cellular tetrahydrobiopterin levels were measured by high performance liquid chromatography.

RESULTS

HAT/MET incubation resulted in significantly increased cellular Hcy levels, unaffected by coincubation with AGE. Elevated Hcy went along with significantly decreased NO output (to 34.4 ± 4.4% of control) and levels of tetrahydrobiopterin (from 4.67 ± 2.17 to 2.17 ± 0.97 pmol/mg). Incubation with AGE (5mg/mL) in HAT/MET-treated cells prevented the declines in NO output and tetrahydrobiopterin levels. AGE increased cellular levels of cysteine and total glutathione, and prevented glutathione and tetrahydrobiopterin oxidation induced by elevated Hcy.

CONCLUSION

Incubation with AGE preserved normal NO output from endothelial cells even under conditions of elevated Hcy levels by increasing cellular thiol antioxidant and prevention of tetrahydrobiopterin oxidation. This suggests that AGE might be useful in the prevention of endothelial dysfunction.

Plasma homocysteine levels are independently associated with the severity of peripheral polyneuropathy in type 2 diabetic subjects

Peripheral polyneuropathy (PN) is a frequent complication of diabetes. However, mechanisms underlying the development of PN are multifactorial and not well understood. Our aim was to examine the association of plasma homocysteine (Hcy) with the prevalence and grade of peripheral PN in patients with type 2 diabetes (T2DM). We studied a cohort of 196 subjects with T2DM classified according to the grade of PN (Neuropathy Disability Score, NDS). Subjects with the highest grade of PN were older and had significantly increased levels of creatinine, microalbuminuria, HbA1c, and plasma Hcy compared to the other two groups. The differences in plasma Hcy values were maintained after correcting for confounding factors. Plasma Hcy, HbA1c, duration of diabetes, and age were predictors of the grade of PN. In conclusion, for each increase of 1 µmol in plasma Hcy there was a 23% increase of the risk of diabetic PN evaluated by NDS. Moreover, the grade of PN was predicted by plasma Hcy and HbA1c values, age and duration of diabetes. Further prospective studies should be conducted to confirm the association of plasma Hcy levels with the grade of PN in subjects with T2DM.

Hyperhomocysteinemia exaggerates adventitial inflammation and angiotensin II-induced abdominal aortic aneurysm in mice

RATIONALE

A number of epidemiological studies have suggested an association of hyperhomocysteinemia (HHcy) and abdominal aortic aneurysm (AAA), but discrepancies exist. In addition, we lack direct evidence supporting a causal role.

OBJECTIVE

We determined the association and contribution of HHcy to AAA formation.

METHODS AND RESULTS

We first performed a meta-analysis of studies involving 1489 subjects and found a strong association of HHcy and AAA (odds ratio, 7.39). Next, we used angiotensin II-infused male apolipoprotein E-deficient mice and tested whether HHcy contributes to AAA pathogenesis. Homocysteine (Hcy) supplement (1.8 g/L) in drinking water resulted in mild HHcy. Intriguingly, HHcy greatly increased the incidence of angiotensin II-induced AAA and aortic dissection in apolipoprotein E-deficient mice (vehicle versus Hcy: 50% versus 100%; P<0.05). Histology indicated HHcy markedly exaggerated aortic adventitial inflammation. Increased levels of proinflammatory interleukin-6 and monocyte chemoattractant protein-1 were preferentially colocalized within adventitial fibroblasts in HHcy plus angiotensin II mice, which suggested the importance of adventitial fibroblasts activation in Hcy-aggravated AAA. Hcy sequentially stimulated adventitial fibroblasts transformation into myofibroblasts, secretion of interleukin-6 and monocyte chemoattractant protein-1, and consequent recruitment of monocytes/macrophages to adventitial fibroblasts, which was abolished by the NADPH oxidase inhibitor diphenyliodonium. NADPH oxidase 4, but not other homologs of NADPH oxidase, was significantly upregulated by Hcy in adventitial fibroblasts, whereas NADPH oxidase 4 small interfering RNA silencing diminished Hcy-induced adventitial fibroblasts activation. Finally, folic acid supplement (0.071 μg/g per day) markedly reduced HHcy-aggravated angiotensin II-induced AAA formation in apolipoprotein E-deficient mice.

CONCLUSIONS

HHcy may aggravate AAA formation at least partially via activating adventitial fibroblast NADPH oxidase 4.