Homocysteine imbalance: a pathological metabolic marker

Evaluation of relationship between serum homocysteine and Vitamin B12 levels in oral submucous fibrosis patients using chemiluminescence immunoassay

Background:

Serum homocysteine (Hcy), a nonessential amino acid, is considered as a helpful indicator of vitamin status for its strong correlation with Vitamin B12. Although Hcy levels in oral submucous fibrosis (OSMF) have been studied, the relationship between Hcy and Vitamin B12 has not been studied yet. This study is the first one to compare and correlate the levels of serum Hcy and Vitamin B12 in OSMF patients.

Materials and Methods:

The study group comprised 60 patients. Serum Hcy and Vitamin B12 estimation were done by chemiluminescence immunoassay. These levels in OSMF patients were compared and correlated with corresponding levels in healthy controls.

Results:

Hcy levels were elevated in OSMF and were found to be statistically significant (P = 0.014) as compared to healthy controls. On the contrary, although Vitamin B12 levels were found to be higher in healthy controls, the difference was statistically nonsignificant (P = 0.657). A significant correlation was found (P = 0.01) between Hcy and Vitamin B12 in both groups, i.e., decreased Vitamin B12 levels led to elevated Hcy levels but vice versa was not found. No correlation was found between levels of Hcy and the severity of OSMF (P = 0.806).

Conclusion:

Chronic inflammation in OSMF leads to hyperhomocysteinemia, which may also be seen in cases of Vitamin B12 deficiency and certain systemic disorders. Thus, while serum Hcy could be used as biomarker for OSMF, Vitamin B12 deficiency and certain systemic disorders should be ruled out.

Role of homocysteine metabolism in animal reproduction: A review

Homocysteine (Hcy) is a thiol-containing essential amino acid, important for the growth of cells and tissues. Several hypotheses exist regarding Hcy toxicity in humans; Hcy is involved in protein structural modifications, oxidative stress, and neurotoxicity induction and is therefore associated with several pathological conditions in humans. In veterinary science, knowledge regarding Hcy has increased recently due to several studies; however, many aspects remain undiscovered. Many details remain unknown regarding the effect of Hcy levels on pregnancy and the optimal management of pathological conditions associated with Hcy levels during pregnancy in various species. In this review, we aimed to compile various studies on Hcy metabolism to elucidate its current status in the veterinary field, particularly for ovine, bovine, equine, porcine, canine, and feline species.

Hydrogen sulfide alleviates hyperhomocysteinemia-mediated skeletal muscle atrophy via mitigation of oxidative and endoplasmic reticulum stress injury

Although hyperhomocysteinemia (HHcy) occurs because of the deficiency in cystathionine-β-synthase (CBS) causing skeletal muscle dysfunction, it is still unclear whether this effect is mediated through oxidative stress, endoplasmic reticulum (ER) stress, or both. Nevertheless, there is no treatment option available to improve HHcy-mediated muscle injury. Hydrogen sulfide (H₂S) is an antioxidant compound, and patients with CBS mutation do not produce H₂S. In this study, we hypothesized that H₂S mitigates HHcy-induced redox imbalance/ER stress during skeletal muscle atrophy via JNK phosphorylation. We used CBS^+/- mice to study HHcy-mediated muscle atrophy, and treated them with sodium hydrogen sulfide (NaHS; an H₂S donor). Proteins and mRNAs were examined by Western blots and quantitative PCR. Proinflammatory cytokines were also measured. Muscle mass and strength were studied via fatigue susceptibility test. Our data revealed that HHcy was detrimental to skeletal mass, particularly gastrocnemius and quadriceps muscle weight. We noticed that oxidative stress was reversed by NaHS in homocysteine (Hcy)-treated C2C12 cells. Interestingly, ER stress markers (GRP78, ATF6, pIRE1α, and pJNK) were elevated in vivo and in vitro, and NaHS mitigated these effects. Additionally, we observed that JNK phosphorylation was upregulated in C2C12 after Hcy treatment, but NaHS could not reduce this effect. Furthermore, inflammatory cytokines IL-6 and TNF-α were higher in plasma from CBS as compared with wild-type mice. FOXO1-mediated Atrogin-1 and MuRF-1 upregulation were attenuated by NaHS. Functional studies revealed that NaHS administration improved muscle fatigability in CBS^+/- mice. In conclusion, our work provides evidence that NaHS is beneficial in mitigating HHcy-mediated skeletal injury incited by oxidative/ER stress responses.

Interaction between plasma homocysteine and the MTHFR c.677C > T polymorphism is associated with site-specific changes in DNA methylation in humans

One-carbon metabolism provides a direct link among dietary folate/vitamin B₁₂ exposure, the activity of the enzyme methylenetetrahydrofolate reductase (MTHFR), and epigenetic regulation of the genome via DNA methylation. Previously, it has been shown that the common c.677C > T polymorphism in MTHFR influences global DNA methylation status through a direct interaction with folate status and (indirectly) with total homocysteine (tHcy) levels. To build on that and other more recent observations that have further highlighted associations among MTHFR c.677C > T, tHcy, and aberrations in DNA methylation, we investigated whether the interaction between mildly elevated plasma tHcy and the c.677C > T polymorphism is associated with site-specific changes in DNA methylation in humans. We used data on plasma tHcy levels, c.677C > T polymorphism, and site-specific DNA methylation levels for a total of 915 white women and 335 men from the TwinsUK registry ( n = 610) and the Rotterdam study ( n = 670). We performed methylome-wide association analyses in each cohort to model the interaction between levels of tHcy and c.677C > T genotypes on DNA methylation β values. Our meta-analysis identified 13 probes significantly associated with rs1801133 × tHcy levels [false-discovery rate (FDR) < 0.05]. The most significant associations were with a cluster of probes at the AGTRAP-MTHFR-NPPA/B gene locus on chromosome 1 (FDR = 1.3E-04), with additional probes on chromosomes 2, 3, 4, 7, 12, 16, and 19. Our top 2 hits on chromosome 1 were functionally associated with variability in expression of the TNF receptor superfamily member 8 ( TNFRSF8) gene/locus on that chromosome. This is the first study, to our knowledge, to provide a direct link between perturbations in 1-carbon metabolism, through an interaction of tHcy and the activity of MTHFR enzyme on epigenetic regulation of the genome via DNA methylation.-Nash, A. J., Mandaviya, P. R., Dib, M.-J., Uitterlinden, A. G., van Meurs, J., Heil, S. G., Andrew, T., Ahmadi, K. R. Interaction between plasma homocysteine and the MTHFR c.677C>T polymorphism is associated with site-specific changes in DNA methylation in humans.

Nutritional Needs of the Older Adult

Older adults are particularly vulnerable to compromised nutritional status. With advancing age, the consumption of a high-quality, nutritionally dense diet is increasingly essential to optimize health and well-being. Proportionally, macronutrient needs for older adults are similar to younger adults, however overall calorie requirements tend to decline with age. Unique factors influencing food intake should be considered and individualized guidance should be designed to help overcome medical, physical, and social barriers to a healthy diet. The goal for nutrition intervention should ultimately be to promote health and quality of life across the continuum of the aging process.

Hyperhomocysteinemia in polycystic ovary syndrome: decreased betaine-homocysteine methyltransferase and cystathionine β-synthase-mediated homocysteine metabolism

RESEARCH QUESTION

What are the metabolic characteristics of homocysteine in polycystic ovary syndrome (PCOS)?

DESIGN

Homocysteine concentrations were determined in serum samples from non-obese and obese control subjects and PCOS patients. Homocysteine metabolism was studied in a rat model of PCOS established using dehydroepiandrosterone (DHEA) or DHEA in combination with a high-fat diet (HFD).

RESULTS

It was shown that (i) serum homocysteine concentrations were greater in PCOS patients than in control subjects in the obese group (P < 0.05) and serum homocysteine concentrations were significantly higher in the obese group than in the non-obese group, regardless of PCOS status (both P < 0.05); (ii) serum homocysteine concentrations were significantly increased in DHEA + HFD-induced rats compared with controls (P < 0.05); (iii) when compared with the control group, mRNA concentrations of homocysteine metabolic enzymes Bhmt and Cbs were significantly reduced in the liver tissues of DHEA + HFD-induced rats (both P < 0.0001); (iv) when compared with the control group, there was a significant decrease in the methylation concentrations of the Cbs (P < 0.05) and Bhmt (P < 0.05 and P < 0.0001) promoter in the DHEA + HFD group. The methylation patterns, together with previous data, indicate that hypomethylated promoter-mediated transcriptional activation of Bhmt and Cbs might be a defence mechanism against PCOS-related hyperhomocysteinemia.

CONCLUSIONS

These findings indicate that decreased liver Bhmt and Cbs-mediated homocysteine metabolism might have a role in hyperhomocysteinemia in PCOS and provides further evidence for a potential role of decreased liver function in PCOS.

Homocysteine regulates fatty acid and lipid metabolism in yeast

S-Adenosyl-l-homocysteine hydrolase (AdoHcy hydrolase; Sah1 in yeast/AHCY in mammals) degrades AdoHcy, a by-product and strong product inhibitor of S-adenosyl-l-methionine (AdoMet)-dependent methylation reactions, to adenosine and homocysteine (Hcy). This reaction is reversible, so any elevation of Hcy levels, such as in hyperhomocysteinemia (HHcy), drives the formation of AdoHcy, with detrimental consequences for cellular methylation reactions. HHcy, a pathological condition linked to cardiovascular and neurological disorders, as well as fatty liver among others, is associated with a deregulation of lipid metabolism. Here, we developed a yeast model of HHcy to identify mechanisms that dysregulate lipid metabolism. Hcy supplementation to wildtype cells up-regulated cellular fatty acid and triacylglycerol content and induced a shift in fatty acid composition, similar to changes observed in mutants lacking Sah1. Expression of the irreversible bacterial pathway for AdoHcy degradation in yeast allowed us to dissect the impact of AdoHcy accumulation on lipid metabolism from the impact of elevated Hcy. Expression of this pathway fully suppressed the growth deficit of sah1 mutants as well as the deregulation of lipid metabolism in both the sah1 mutant and Hcy-exposed wildtype, showing that AdoHcy accumulation mediates the deregulation of lipid metabolism in response to elevated Hcy in yeast. Furthermore, Hcy supplementation in yeast led to increased resistance to cerulenin, an inhibitor of fatty acid synthase, as well as to a concomitant decline of condensing enzymes involved in very long-chain fatty acid synthesis, in line with the observed shift in fatty acid content and composition.

One-carbon metabolism markers are associated with cardiometabolic risk factors

BACKGROUND AND AIMS

Alterations to one-carbon metabolism, especially elevated plasma homocysteine (Hcy), have been suggested to be both a cause and a consequence of the metabolic syndrome (MS). A deeper understanding of the role of other one-carbon metabolites in MS, including s-adenosylmethionine (SAM), s-adenosylhomocysteine (SAH), and the methylation capacity index (SAM:SAH ratio) is required.

METHODS AND RESULTS

118 men and women with MS-risk factors were included in this cross-sectional study and cardiometabolic outcomes along with markers of one-carbon metabolism, including fasting plasma SAM, SAH, Hcy and vitamin B₁₂ concentrations, were analysed. Multiple linear regression models were also used to examine the association between plasma one-carbon metabolites and cardiometabolic health features. We found that fasting plasma concentrations of Hcy, SAM and SAH were all positively correlated with markers of adiposity, including BMI (increase in BMI per 1-SD increase in one-carbon metabolite: 0.92 kg/m² 95% CI (0.28; 1.56), p = 0.005; 0.81 (0.15; 1.47), p = 0.02; 0.67 (-0.01; 1.36), p = 0.05, respectively). Hcy, but not SAM, SAH or SAM:SAH ratio was associated with BMI and body fat percentage after mutual adjustments. SAM concentrations were associated with higher fasting insulin (9.5% 95% CI (0.3; 19.5) per SD increase in SAM, p = 0.04), HOMA-IR (10.8% (0.8; 21.9), p = 0.03) and TNF-α (11.8% (5.0; 19.0), p < 0.001).

CONCLUSION

We found little evidence for associations between SAM:SAH ratio and cardiometabolic variables, but higher plasma concentrations of SAM, SAH and Hcy are related to an overall higher risk of metabolic dysfunctions. The studies were registered at www.clinicaltrials.gov (NCT01719913 &NCT01731366).

Homocysteine causes dysfunction of chondrocytes and oxidative stress through repression of SIRT1/AMPK pathway: A possible link between hyperhomocysteinemia and osteoarthritis

Emerging evidence has indicated that the perturbed expression of homocysteine (Hcy) may induce mitochondrial dysfunction and disturb bone metabolism. Sirtuin 1 (SIRT1) and AMP-activated protein kinase (AMPK) are two critical sensors that regulate mitochondrial biogenesis and have been recognized as therapeutic targets in osteoarthritis (OA). This study was designed to test whether Hcy caused pro-osteoarthritic changes through modulation of SIRT1 and AMPK. Our results showed that administration of Hcy reduced the SIRT1/AMPK/PGC-1α signaling in chondrocytes, leading to mitochondrial dysfunction as a result of increased oxidative stress and apoptosis. Moreover, we demonstrated that the expression of NF-κB, COX-2, IL-8, and MMP-13 were elevated subsequent to inhibition of SIRT1/AMPK/PGC-1α/PPAR-γ pathway by homocysteine, thereby causing detrimental effects on chondrocytes. In the animal model of diet-induced hyperhomocysteinemia (HHcy), we observed the similar findings that SIRT1/PGC-1α/PPAR-γ cascades were downregulated with elevated MMP-13 and COX-2. Taken together, data from the current study revealed that the reduced SIRT1 by Hcy may contribute to degradative cartilage process, which provided insight into the etiology of OA.

Higher intake of fish and fat is associated with lower plasma s-adenosylhomocysteine: a cross-sectional study

Several B-vitamins act as co-factors in one-carbon metabolism, a pathway that plays a central role in several chronic diseases. However, there is a lack of knowledge of how diet affects markers in one-carbon metabolism. The aim of this study was to explore dietary patterns and components associated with one-carbon metabolites. We hypothesized that intake of whole-grains and fish would be associated with lower Hcy, and higher SAM:SAH ratio due to their nutrient content. We assessed dietary information using a four-day dietary record in 118 men and women with features of the metabolic syndrome. In addition we assessed whole-blood fatty acid composition and plasma alkylresorcinols. Plasma s-adenosylmethionine (SAM), s-adenosylhomocysteine (SAH), homocysteine (Hcy) and vitamin B₁₂ was included as one-carbon metabolism markers. We used principal component analysis (PCA) to explore dietary patterns and multiple linear regression models to examine associations between dietary factors and one-carbon metabolites. PCA separated subjects based on prudent and unhealthy dietary patterns, but the dietary pattern score was not related to the one-carbon metabolites. Whole grain intake was found to be inversely associated to plasma Hcy (-4.7% (-9.3; 0.0), P=.05) and total grain intake tended to be positively associated with SAM and SAH (2.4% (-0.5; 5.5), P=.08; 5.8% (-0.2; 12.1), P=.06, respectively, per SD increase in cereal intake). Fish intake was inversely associated with plasma Hcy and SAH concentrations (-5.4% (-9.7; -0.8), P=.02 and -7.0% (-12.1; -1.5), P=.01, respectively) and positively associated with the SAM:SAH ratio (6.2% (1.6; 11.0), P=.008). In conclusion, intake and fish and whole-grain appear to be associated with a beneficial one-carbon metabolism profile. This indicates that dietary components could play a role in regulation of one-carbon metabolism with a potential impact on disease prevention.

A genetic variant in a homocysteine metabolic gene that increases the risk of congenital cardiac septal defects in Han Chinese populations

Elevated homocysteine levels are known to be a risk factor for congenital cardiac septal defects (CCSDs), but the mechanism underlying this effect is unknown. The genetic variants that were significantly associated with circulating homocysteine concentrations have been systematically identified through the genome-wide association studies of one-carbon core metabolites. To examine the role of the genome-wide significant homocysteine related variants in the occurrence of CCSDs, we investigated the association between these variants and CCSDs in Han Chinese populations. Five variants of the genome-wide significant homocysteine-related genes were selected for analysis in two stages of case-controlled studies with a total of 904 CCSD patients and 997 controls. SYT9 expression was detected in human cardiovascular tissue using qRT-PCR. The intronic variant rs11041321 of the SYT9 gene was associated with an increased risk of developing CCSDs in both the separate and combined case-controlled studies. Combined samples from the two stage cohorts had a significant elevation in CCSD risk for the T allele (OR = 1.43, P = 2.6 × 10^-6 ), CT genotype and TT genotype (CT: OR = 1.30, TT: OR = 2.21; P = 1 × 10^-4 ) compared with the wild-type C allele and CC genotype, respectively. The risky T allele carriers exhibited decreased SYT9 mRNA expression, compared with wild-type C allele carriers. The intronic SYT9 variant rs11041321, which exhibits a significant genome-wide association with circulating homocysteine, was associated with the occurrence of CCSDs. This finding helps to characterize the unexpected role of SYT9 in homocysteine metabolism and the development of CCSDs, which further highlighted the interplay of diet, genetics, and human birth defects. © 2017 IUBMB Life, 69(9):700-705, 2017.

Serum allantoin and aminothiols as biomarkers of chronic heart failure

Background Oxidative stress (OS) represents the primary mediator of chronic heart failure (CHF) development and progression. It is well established that homocysteine is able to generate reactive oxygen species. Small amounts of allantoin in human serum result from free radical action on urate and may provide a stable marker for in vivo free radical activity. To investigate whether some easily measurable indexes such as antioxidants (uric acid, glutathione) and related molecules (allantoin, homocysteine and cysteine) can serve as OS biomarkers. Methods We investigated 75 stable CHF patients. Aminothiols and purine compound levels were determined by capillary electrophoresis. Results The homocysteine level was markedly elevated in CHF patients, whatever the aetiology. Parameters of the transsulfuration pathway and the investigated purine compounds were significantly increased. Conversely, total glutathione was decreased. The allantoin/uric acid ratio was significantly higher in CHF patients with an hyperhomocysteinaemia >17 μmol/L. All parameters of the transsulfuration and purine degadation pathways were significantly correlated, suggesting an OS in CHF patients. Conclusion Our data show an imbalance of serum aminothiols and purine compounds in these CHF patients on adapted therapy. We suggest that the evaluation and control of these new markers may help improve the OS that participates in the progression of the disease.

Independent impact of plasma homocysteine levels on neurological outcome following head injury

Homocysteine (tHcy) has been hardly studied among patients with head injury. This study was to evaluate whether there is any independent impact of tHcy levels on neurological outcome following head injury in a multivariate model. Patients admitted within 24 h of injury were included in the study, along with 20 age- and gender-matched controls. Plasma levels of tHcy were measured at admission using direct immunoassay. All the variables were analyzed with respect to tHcy levels and outcome according to Glasgow Outcome Score (GOS) at 3 months. Univariate and multivariate analyses were performed using SPSS 21. There were a total of 72 patients in the study. tHcy levels were significantly higher after head injury (mean 24.03[SD ± 16.0] μmol/L), compared to matched controls (mean 16.62 [SD ± 10.4] μmol/L) (p = 0.05). Patients with severe head injury, acute SDH, or diffuse higher radiological grades had greater levels of tHcy compared to others. There was a significant relationship between tHcy level and neurological outcome. tHcy levels were significantly higher in patients who had unfavorable GOS (mean 36.22[±25.3] μmol/L), compared to those with favorable GOS (mean 22.71[±14.3] μmol/L) (P = 0.03). In multivariate analysis, tHcy level (adj. odds ratio [OR] 1.17, P = 0.05) and Glasgow Coma Scale (adj. OR 5.17, P = 0.01) had significant association with neurological outcome at 3 months independent of age, dietary habit, radiological grading and of each other. tHcy level has significant independent impact on neurological outcome and may be useful as a prognostic marker following head injury.

Nrf2 mediates the protective effects of homocysteine by increasing the levels of GSH content in HepG2 cells

Homocysteine (Hcy) and glutathione (GSH) are crucial reduction-oxidation mediators. The underlying mechanisms governing the effects of Hcy on GSH generation in the progression of alcoholic liver disease has so far received little attention. The present study hypothesized that the antioxidant transcriptional factor nuclear factor (erythroid-derived 2)-like 2 (Nrf2) may participate in Hcy-mediated regulation of GSH production in HepG2 human liver cancer cells. MTT assay was used to study the cytotoxicity of homocysteine, western blot analysis and immunofluorescence staining were used to determine the effect of Hcy on Nrf2 expression. Our data demonstrated that HepG2 cells exposed to exogenous levels of Hcy (0–100 µM) exhibited elevated GSH levels in a concentration-dependent manner. Furthermore, 4-hydroxynonenal (4-HNE)-induced cell injury was attenuated by Hcy; however, this protective effect was blocked by the GSH-production inhibitor buthionine sulfoximine. Hcy treatment was able to induce Nrf2 protein expression in HepG2 cells. Treatment with the Nrf2 activator tert-butylhydroquinone (0–100 µM) increased GSH expression in a concentration-dependent manner; however, Nrf2-siRNA abolished the Hcy-induced increase in GSH expression and cellular protection in 4-HNE-stressed HepG2 cells. In conclusion, the antioxidant transcriptional factor Nrf2 was demonstrated to mediate the Hcy-induced increase in GSH expression levels and cellular protection in HepG2 cells.

Systemic and ocular fluid compounds as potential biomarkers in age-related macular degeneration

Biomarkers can help unravel mechanisms of disease and identify new targets for therapy. They can also be useful in clinical practice for monitoring disease progression, evaluation of treatment efficacy, and risk assessment in multifactorial diseases, such as age-related macular degeneration (AMD). AMD is a highly prevalent progressive retinal disorder for which multiple genetic and environmental risk factors have been described, but the exact etiology is not yet fully understood. Many compounds have been evaluated for their association with AMD. We performed an extensive literature review of all compounds measured in serum, plasma, vitreous, aqueous humor, and urine of AMD patients. Over 3600 articles were screened, resulting in more than 100 different compounds analyzed in AMD studies, involved in neovascularization, immunity, lipid metabolism, extracellular matrix, oxidative stress, diet, hormones, and comorbidities (such as kidney disease). For each compound, we provide a short description of its function and discuss the results of the studies in relation to its usefulness as AMD biomarker. In addition, biomarkers identified by hypothesis-free techniques, including metabolomics, proteomics, and epigenomics, are covered. In summary, compounds belonging to the oxidative stress pathway, the complement system, and lipid metabolism are the most promising biomarker candidates for AMD. We hope that this comprehensive survey of the literature on systemic and ocular fluid compounds as potential biomarkers in AMD will provide a stepping stone for future research and possible implementation in clinical practice.

Cochlear Homocysteine Metabolism at the Crossroad of Nutrition and Sensorineural Hearing Loss

Hearing loss (HL) is one of the most common causes of disability, affecting 360 million people according to the World Health Organization (WHO). HL is most frequently of sensorineural origin, being caused by the irreversible loss of hair cells and/or spiral ganglion neurons. The etiology of sensorineural HL (SNHL) is multifactorial, with genetic and environmental factors such as noise, ototoxic substances and aging playing a role. The nutritional status is central in aging disability, but the interplay between nutrition and SNHL has only recently gained attention. Dietary supplementation could therefore constitute the first step for the prevention and potential repair of hearing damage before it reaches irreversibility. In this context, different epidemiological studies have shown correlations among the nutritional condition, increased total plasma homocysteine (tHcy) and SNHL. Several human genetic rare diseases are also associated with homocysteine (Hcy) metabolism and SNHL confirming this potential link. Accordingly, rodent experimental models have provided the molecular basis to understand the observed effects. Thus, increased tHcy levels and vitamin deficiencies, such as folic acid (FA), have been linked with SNHL, whereas long-term dietary supplementation with omega-3 fatty acids improved Hcy metabolism, cell survival and hearing acuity. Furthermore, pharmacological supplementations with the anti-oxidant fumaric acid that targets Hcy metabolism also improved SNHL. Overall these results strongly suggest that cochlear Hcy metabolism is a key player in the onset and progression of SNHL, opening the way for the design of prospective nutritional therapies.

Homocysteine as a Pathological Biomarker for Bone Disease

In the last few decades, perturbation in methyl-group and homocysteine (Hcy) balance have emerged as independent risk factors in a number of pathological conditions including neurodegenerative disease, cardiovascular dysfunction, cancer development, autoimmune disease, and kidney disease. Recent studies report Hcy to be a newly recognized risk factor for osteoporosis. Elevated Hcy levels are known to modulate osteoclastgenesis by causing detrimental effects on bone via oxidative stress induced metalloproteinase-mediated extracellular matrix degradation and decrease in bone blood flow. Evidence from previous studies also suggests that the decreased chondrocytes mediated bone mineralization in chick limb-bud mesenchymal cells and during the gestational period of ossification in rat model. However, Hcy imbalance and its role in bone loss, regression in vascular invasion, and osteoporosis, are not clearly understood. More investigations are required to explore the complex interplay between Hcy imbalance and onset of bone disease progression. This article reviews the current body of knowledge on regulation of Hcy mediated oxidative stress and its role in bone remodeling, vascular blood flow and progression of bone disease. J. Cell. Physiol. 232: 2704-2709, 2017. © 2016 Wiley Periodicals, Inc.

Proteome response of fish under multiple stress exposure: Effects of pesticide mixtures and temperature increase

Aquatic systems can be subjected to multiple stressors, including pollutant cocktails and elevated temperature. Evaluating the combined effects of these stressors on organisms is a great challenge in environmental sciences. To the best of our knowledge, this is the first study to assess the molecular stress response of an aquatic fish species subjected to individual and combined pesticide mixtures and increased temperatures. For that, goldfish (Carassius auratus) were acclimated to two different temperatures (22 and 32°C) for 15 days. They were then exposed for 96h to a cocktail of herbicides and fungicides (S-metolachlor, isoproturon, linuron, atrazine-desethyl, aclonifen, pendimethalin and tebuconazole) at two environmentally relevant concentrations (total concentrations of 8.4μgL^-1 and 42μgL^-1) at these two temperatures (22 and 32°C). The molecular response in liver was assessed by 2D-proteomics. Identified proteins were integrated using pathway enrichment analysis software to determine the biological functions involved in the individual or combined stress responses and to predict the potential deleterious outcomes. The pesticide mixtures elicited pathways involved in cellular stress response, carbohydrate, protein and lipid metabolisms, methionine cycle, cellular functions, cell structure and death control, with concentration- and temperature-dependent profiles of response. We found that combined temperature increase and pesticide exposure affected the cellular stress response: the effects of oxidative stress were more marked and there was a deregulation of the cell cycle via apoptosis inhibition. Moreover a decrease in the formation of glucose by liver and in ketogenic activity was observed in this multi-stress condition. The decrease in both pathways could reflect a shift from a metabolic compensation strategy to a conservation state. Taken together, our results showed (1) that environmental cocktails of herbicides and fungicides induced important changes in pathways involved in metabolism, cell structure and cell cycle, with possible deleterious outcomes at higher biological scales and (2) that increasing temperature could affect the response of fish to pesticide exposure.

Oxidative Stress and Environmental Exposures are Associated with Multiple System Atrophy in Chinese Patients

OBJECTIVE

Oxidative stress is involved in the pathogenesis of multiple system atrophy (MSA). The aim of this study is to examine oxidant biomarkers including homocysteine (Hcys), bilirubin, uric acid, lipids, and potential environmental risk factors and to ascertain whether these data correlate with MSA in a Chinese population.

METHODS

In this study, serum levels of Hcys, bilirubin, uric acid, and lipids were studied in 55 MSA patients and 76 healthy controls (HCs). Education, anti-parkinsonian agent usage, smoking, drinking, farming, and living area of the subjects also were analyzed. The Unified MSA Rating Scale (UMSARS), Hoehn & Yahr stage, International Cooperative Ataxia Rating Scale, and Mini-Mental State Examination were used to assess the disease severity, the parkinsonism, ataxia, and the cognitive ability of MSA, respectively.

RESULTS

The levels of Hcys were higher (p<0.001) and those of total bilirubin (p=0.007), indirect bilirubin (p=0.011), and total cholesterol (p=0.046) were lower in MSA patients than in healthy controls, whereas uric acid levels did not differ significantly between MSA and healthy controls. Moreover, Hcys levels in MSA patients had positive correlations with illness duration (r s =0.422, p=0.001) and UMSARS-I (r s =0.555, p<0.001), respectively. High-density lipoprotein cholesterol levels were negatively correlated with UMSARS-I (r s =-0.325, p=0.015). Farming was more frequent in MSA patients (1-20 years: odds ratio, 6.36; p20 years: odds ratio, 10.26; p=0.001), whereas current smoking was less frequent (odds ratio, 0.13, p=0.002).

CONCLUSIONS

Elevated Hcys and decreased high-density lipoprotein cholesterol may be associated with the disease severity of MSA. Environmental exposures such as farming and smoking may contribute to the occurrence but not the progression of MSA.

Homocysteine and all-cause mortality in hypertensive adults without pre-existing cardiovascular conditions: Effect modification by MTHFR C677T polymorphism

BACKGROUND

Previous studies support an association between elevated total homocysteine (tHcy) levels and increased all-cause mortality. However, few prospective studies have examined this association in hypertensive patients, and/or tested any effect modification by the methylene tetrahydrofolate reductase (MTHFR) C677T genotype.

METHODS

This was a post hoc analysis of the China Stroke Primary Prevention Trial. Serum tHcy and folate were measured at baseline. Individual MTHFR C677T genotype (CC, CT, and TT) was determined. Evidence for death included death certificates or home visits. Cumulative hazards of all-cause mortality by tHcy quartiles were estimated using the Kaplan-Meier method, and group differences were compared by log-rank tests. Hazard ratios (HRs) and 95% confidence intervals were estimated by Cox proportional-hazard regression models, adjusting for age, sex, baseline folate, vitamin B12, blood pressure, body mass index, smoking and alcohol drinking status, study center, total cholesterol, triglycerides, high-density lipoprotein cholesterol, fasting glucose, creatinine, and treatment group. Potential effect modification by the MTHFR genotype on the relationship between tHcy and all-cause mortality was tested.

RESULTS

The analyses included 20,424 hypertensive patients (41% males) without a history of myocardial infarction or stroke. Baseline mean age (SD) was 60 ± 7.5 years and mean (SD) serum tHcy was 14.5 ± 8.4 μmol/L. After a mean follow-up period of 4.5 years, there were 612 (3%) all-cause deaths. Kaplan-Meier survival curves revealed a graded relationship between tHcy quartiles and all-cause mortality. The HRs, using the lowest quartile as the reference, were 1.2, 1.2, and 1.5 in Q2, Q3, and Q4, respectively. A linear trend test, using natural log-transformed tHcy, resulted in an HR of 1.5 (95% confidence interval 1.2-1.9, P < .001) after adjustment for lifestyle and health-related variables. Whereas the MTHFR genotype alone had little effect on mortality, it significantly modified the tHcy-mortality association, which was much stronger in the CC/CT genotype than in the TT genotype (P for interaction < 0.05).

CONCLUSIONS

Among Chinese hypertensive patients without cardiovascular comorbidities, elevated tHcy was a significant risk marker for death from all causes, and the association was subject to effect modification by MTHFR genotypes. If confirmed that tHcy and MTHFR genotypes may serve as useful biomarkers for mortality risk assessment and targeted intervention.

Maternal consumption of low-isoflavone soy protein isolate alters hepatic gene expression and liver development in rat offspring

In utero environment is known to affect fetal development. Especially, the distinct fetal programming of carcinogenesis was reported in offspring exposed to maternal diets containing soy protein isolate (SPI) or genistein. Therefore, we investigated whether maternal consumption of low-isoflavone SPI or genistein alters hepatic gene expression and liver development in rat offspring. Female Sprague-Dawley rats were fed a casein diet, a low-isoflavone SPI diet or a casein diet supplemented with genistein (250 mg/kg diet) for 2 weeks before mating and throughout pregnancy and lactation. Male offspring were studied on postnatal day 21 (CAS, SPI and GEN groups). Among 965 differentially expressed hepatic genes related to maternal diet (P<.05), the expression of 590 was significantly different between CAS and SPI groups. Conversely, the expression of 88 genes was significantly different between CAS and GEN groups. Especially, genes involved in drug metabolism were significantly affected by the maternal diet. SPI group showed increased cell proliferation, reduced apoptosis and activation of the mTOR pathway, which may contribute to a higher relative liver weight compared to other groups. We observed higher serum homocysteine levels and lower global and CpG site-specific DNA methylation of Gadd45b, a gene involved in cell proliferation and apoptosis, in SPI group compared to CAS group. Maternal SPI diet also reduced histone H3-Lysine 9 (H3K9) trimethylation and increased H3K9 acetylation in offspring. These results demonstrate that maternal consumption of a low-isoflavone SPI diet alters the hepatic gene expression profile and liver development in offspring possibly by epigenetic processes.

Hypermethylation in the promoter of the MTHFR gene is associated with diabetic complications and biochemical indicators

BACKGROUND

DNA methylation is an epigenetic mechanism for regulating the transcription of many genes and has been linked to the development of various diseases. A promising gene to investigate is methylenetetrahydrofolate reductase (MTHFR), since the enzyme methylenetetrahydrofolate reductase (MTHFR) promotes methyl radical synthesis in the homocysteine cycle and can provide methyl groups for DNA methylation. In addition, several studies have correlated gene polymorphisms of this enzyme with a greater risk of diabetes, but little is known regarding the relationship between epigenetic changes in this gene and diabetes and its complications. The aim of this study was to investigate the relationship between methylation profile in the MTHFR gene promoter and biochemical, inflammatory and oxidative stress markers in individuals with type 2 diabetes (T2DM) who have been diagnosed for 5-10 years with or without diabetic retinopathy (DR) and nephropathy (DN).

METHODS

Specific PCR for methylation (MSP) was used to analyze MTHFR methylation profile in leucocytes DNA. Biochemical markers (glycemia, glycated hemoglobin, total cholesterol, LDL, HDL, triglycerides, serum creatinine), inflammatory markers (C-reactive protein and alpha-1 acid glycoprotein) and oxidative stress (total antioxidant and malonaldehyde) were determined in peripheric blood samples and microalbuminuria in 24 h urine samples. The X² and Mann-Whitney statistical tests were performed and p < 0.05 were considered significant.

RESULTS

The hypermethylated profile was most frequently observed in individuals with retinopathy (p < 0.01) and was associated with higher total cholesterol and LDL levels (p = 0.0046, 0.0267, respectively). Individuals with DN and hypermethylated profiles had higher levels of alpha-1 acid glycoprotein (p = 0.0080) and total antioxidant capacity (p = 0.0169) compared to subjects without complications.

CONCLUSIONS

Hypermethylation in the promoter of the MTHFR gene is associated with the occurrence of DR and with biochemical, inflammatory and oxidative stress parameters in the context of chronic complications.

Methionine and Choline Supply during the Periparturient Period Alter Plasma Amino Acid and One-Carbon Metabolism Profiles to Various Extents: Potential Role in Hepatic Metabolism and Antioxidant Status

The objective of this study was to profile plasma amino acids (AA) and derivatives of their metabolism during the periparturient period in response to supplemental rumen-protected methionine (MET) or rumen-protected choline (CHOL). Forty cows were fed from −21 through 30 days around parturition in a 2 × 2 factorial design a diet containing MET or CHOL. MET supply led to greater circulating methionine and proportion of methionine in the essential AA pool, total AA, and total sulfur-containing compounds. Lysine in total AA also was greater in these cows, indicating a better overall AA profile. Sulfur-containing compounds (cystathionine, cystine, homocystine, and taurine) were greater in MET-fed cows, indicating an enriched sulfur-containing compound pool due to enhanced transsulfuration activity. Circulating essential AA and total AA concentrations were greater in cows supplied MET due to greater lysine, arginine, tryptophan, threonine, proline, asparagine, alanine, and citrulline. In contrast, CHOL supply had no effect on essential AA or total AA, and only tryptophan and cystine were greater. Plasma 3-methylhistidine concentration was lower in response to CHOL supply, suggesting less tissue protein mobilization in these cows. Overall, the data revealed that enhanced periparturient supply of MET has positive effects on plasma AA profiles and overall antioxidant status.

Determinants of hyperhomocysteinemia in healthy and hypertensive subjects: A population-based study and systematic review

AIMS

Hyperhomocysteinemia (HHcy) is known to increase the risk of many diseases. Factors influencing HHcy in healthy and hypertensive subjects remain under-researched.

METHODS

A large population-based study was conducted in 60 communities from Shenzhen, China. Responses to standardized questions on lifestyle factors and blood samples were collected from all participants after a 12-h overnight fast. Multiple linear and multivariate logistic regressions were used to explore risk factors for HHcy. Results were then compared to those from a systematic review of English-language articles listed in Pubmed, EBSCOhost, Web of Science, Embase and Cochrane libraries that investigated HHcy risk factors in healthy and hypertensive subjects.

RESULTS

A total of 1586 healthy (Male/Female = 642/944) and 5935 hypertensive subjects (Male/Female = 2928/3007) participated in our population-based study. In logistic regression analyses, age, BMI and creatinine (Cr) were risk factors, while being female, fruit intake and physical activity were protective factors for HHcy in healthy subjects. In hypertensive subjects, seven [age, smoking, salt intake, systolic blood pressure (SBP), uric acid, triglycerides (TG), and Cr] and four [female, fruit intake, total cholesterol (TC), and glucose] factors were associated with higher and lower HHcy respectively. The review of 71 studies revealed that potential risk factors for Hcy included nutritional, physiologic, lifestyle habits, ethnicity, genetics, interactions between gene-environment, gene-gene, gene-nutritional, environment-environment, nutritional-nutritional.

CONCLUSION

Our study indicates the potential importance of increasing folic acid and vitamin B supplementation, daily fruit and vegetable intake, regular exercise and refraining from tobacco smoking and alcohol consumption as preventive strategies for Hcy.

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.

Interactions between lifestyle and MTHFR polymorphisms on homocysteine concentrations in young adults belonging to the 1982 Pelotas Birth Cohort

BACKGROUND/OBJECTIVES

Homocysteine (Hcy) is a key intermediate in methionine metabolism. A high plasma concentration of Hcy is an independent risk factor for cardiovascular diseases among other determinants. In this study, we aimed to investigate the interactions between methylenetetrahydrofolate reductase enzyme gene (MTHFR) polymorphisms and lifestyle variables (smoking, alcohol intake and physical activity) on Hcy concentrations in a young Brazilian population.

SUBJECTS/METHODS

The study population comprised 3803 individuals from the Pelotas Birth Cohort, aged 22-23 years. Allelic discrimination assays and chemiluminescence immunoassays were performed for genotyping and serum Hcy measurements, respectively. Linear regression models were used to explore the effect of gene-lifestyle interactions on Hcy concentrations.

RESULTS

Men carrying the MTHFR 677TT genotype, who were also smokers and drinkers (⩾15 g of alcohol per day), had the highest concentration of Hcy (P-value for the interaction <0.001 for smoking and 0.002 for alcohol intake). In contrast, high folate concentrations attenuated the effects of the MTHFR C677T genotype on serum Hcy concentrations (P-value for interaction <0.001). Also, among males, blood folate concentration was the only lifestyle variable able to modify the influence of MTHFR A1298C genotypes on Hcy concentrations (P-value for the interaction <0.001). There was no strong evidence of an interaction between the MTHFR genotypes and the lifestyle variables in women.

CONCLUSIONS

In summary, our study demonstrates a sex difference in Hcy concentrations among Brazilian young adults regarding MTHFR C677T-lifestyle interactions that are worsened under conditions of low blood folate. Identification of potentially modifiable factors related to an increase in homocysteine in young adults, especially in those who are genetically susceptible, is important to prevent negative health consequences in the future.

The Molecular and Cellular Effect of Homocysteine Metabolism Imbalance on Human Health

Homocysteine (Hcy) is a sulfur-containing non-proteinogenic amino acid derived in methionine metabolism. The increased level of Hcy in plasma, hyperhomocysteinemia, is considered to be an independent risk factor for cardio and cerebrovascular diseases. However, it is still not clear if Hcy is a marker or a causative agent of diseases. More and more research data suggest that Hcy is an important indicator for overall health status. This review represents the current understanding of molecular mechanism of Hcy metabolism and its link to hyperhomocysteinemia-related pathologies in humans. The aberrant Hcy metabolism could lead to the redox imbalance and oxidative stress resulting in elevated protein, nucleic acid and carbohydrate oxidation and lipoperoxidation, products known to be involved in cytotoxicity. Additionally, we examine the role of Hcy in thiolation of proteins, which results in their molecular and functional modifications. We also highlight the relationship between the imbalance in Hcy metabolism and pathogenesis of diseases, such as cardiovascular diseases, neurological and psychiatric disorders, chronic kidney disease, bone tissue damages, gastrointestinal disorders, cancer, and congenital defects.

Transient Decrease in Circulatory Testosterone and Homocysteine Precedes the Development of Metabolic Syndrome Features in Fructose-Fed Sprague Dawley Rats

Background. Increased fructose consumption is linked to the development of metabolic syndrome (MS). Here we investigated the time course of development of MS features in high-fructose-fed Sprague Dawley rats along with circulatory testosterone and homocysteine levels. Methods. Rats were divided into control and experimental groups and fed with diets containing 54.5% starch and fructose, respectively, for 4, 12, and 24 weeks. Plasma testosterone and homocysteine levels were measured along with insulin, glucose, and lipids. Body composition, insulin resistance, and hepatic lipids were measured. Results. Increase in hepatic triglyceride content was first observed in metabolic disturbance followed by hypertriglyceridemia and systemic insulin resistance in fructose-fed rats. Hepatic lipids were increased in time-dependent manner by fructose-feeding starting from 4 weeks, but circulatory triglyceride levels were increased after 12 weeks. Fasting insulin and Homeostatis Model Assessment of Insulin Resistance (HOMA-IR) were increased after 12 weeks of fructose-feeding. Decreased visceral adiposity, circulatory testosterone, and homocysteine levels were observed after 4 weeks of fructose-feeding, which were normalized at 12 and 24 weeks. Conclusions. We conclude that transient decrease in circulatory testosterone and homocysteine levels and increased hepatic triglyceride content are the earliest metabolic disturbances that preceded hypertriglyceridemia and insulin resistance in fructose-fed SD rats.

Increased homocysteine plasma level is associated with shortened prothrombin time in HIV-infected patients

OBJECTIVE

To find factors associated with increased homocysteine plasma level in HIV-infected patients.

METHODS

Cross-sectional study, carried out as a supplementary task to the standard care of HIV-infected patients. The possible association of increased homocysteine plasma level with blood analyses results was assessed with a multiple linear regression analysis, using the automatic linear modeling available in SPSS version 22.

RESULTS

A total of 145 patients were included. Creatinine was higher than normal in 7 patients (5%), prothrombin time was shortened in 36 patients (25%), and a monoclonal gammopathy was detected in 2 patients (1%). In the regression analysis, an association was found between high homocysteine plasma level and the following variables: low prothrombin time (β coefficient -0.286, confidence interval -1.1854 to -0.754, p < 0.001), high creatinine (coefficient 9.926, confidence interval 6.351-15.246, p < 0.001), low folic acid (coefficient -0.331, confidence interval -0-483 to -0.187, p < 0.001), and low vitamin B12 (coefficient -0.007, confidence interval -0.01 to -0.001, p = 0.005).

CONCLUSION

An association was found between increased homocysteine plasma level and shortened prothrombin time.

One-Carbon Metabolism in Prostate Cancer: The Role of Androgen Signaling

Cancer cell metabolism differs significantly from the metabolism of non-transformed cells. This altered metabolic reprogramming mediates changes in the uptake and use of nutrients that permit high rates of proliferation, growth, and survival. The androgen receptor (AR) plays an essential role in the establishment and progression of prostate cancer (PCa), and in the metabolic adaptation that takes place during this progression. In its role as a transcription factor, the AR directly affects the expression of several effectors and regulators of essential catabolic and biosynthetic pathways. Indirectly, as a modulator of the one-carbon metabolism, the AR can affect epigenetic processes, DNA metabolism, and redox balance, all of which are important factors in tumorigenesis. In this review, we focus on the role of AR-signaling on one-carbon metabolism in tumorigenesis. Clinical implications of one-carbon metabolism and AR-targeted therapies for PCa are discussed in this context.

Homocysteinemia and early outcome of acute ischemic stroke in elderly patients

OBJECTIVES

Plasma total homocysteine (tHcy) is a risk factor for ischemic stroke (IS) but its relationship with IS outcome is uncertain. Moreover, previous studies underrepresented older IS patients, although risk of both hyperhomocysteinemia and IS increases with age. We investigated whether, in elderly patients with acute IS, tHcy measured on admission to the Stroke Unit (SU) is an independent predictor of SU discharge outcomes.

MATERIALS AND METHODS

Data are for 644 consecutive patients aged 80.3 ± 8.7 years, admitted to an Italian SU with diagnosis of acute IS. Plasma tHcy was measured on SU admission. Investigated outcomes included mortality during SU stay and poor functional status (modified Rankin Scale score ≥3) at SU discharge for survivors. The association of plasma tHcy with the study outcomes was assessed using Odds Ratios (OR) and their corresponding 95% confidence intervals (95%CI) from logistic regression models adjusted for demographics, pre-stroke features, IS severity, and laboratory data on SU admission (serum C-reactive protein, serum albumin, and renal function).

RESULTS

Median plasma tHcy was 16.7 μmol/L (interquartile range, 13.0-23.3 μmol/L). Outcome incidence was 5.3% for mortality and 49.7% for poor functional status. Plasma tHcy was unrelated to mortality in both univariate and multivariable-adjusted analyses. Conversely, plasma tHcy was associated with poor functional status of survivors in univariate analyses (P = 0.014). Multivariable-adjusted analyses showed that, compared to normal homocysteinemia (tHcy <16 μmol/L), risk of being discharged with poor functional status significantly increased for moderate (tHcy ≥30 mol/L) but not mild (16.0-29.9 μmol/L) hyperhomocysteinemia.

CONCLUSIONS

In elderly patients with acute IS, high admission plasma tHcy is unrelated to mortality during SU stay but is an independent predictor of poor functional status at SU discharge in survivors. The association, however, is limited to patients with moderate hyperhomocysteinemia.

Changes in one-carbon metabolism after duodenal-jejunal bypass surgery

Bariatric surgery alleviates obesity and ameliorates glucose tolerance. Using metabolomic and proteomic profiles, we evaluated metabolic changes in serum and liver tissue after duodenal-jejunal bypass (DJB) surgery in rats fed a normal chow diet. We found that the levels of vitamin B₁₂ in the sera of DJB rates were decreased. In the liver of DJB rats, betaine-homocysteine S-methyltransferase levels were decreased, whereas serine, cystathionine, cysteine, glutathione, cystathionine β-synthase, glutathione S-transferase, and aldehyde dehydrogenase levels were increased. These results suggested that DJB surgery enhanced trans-sulfuration and its consecutive reactions such as detoxification and the scavenging activities of reactive oxygen species. In addition, DJB rats showed higher levels of purine metabolites such as ATP, ADP, AMP, and inosine monophosphate. Decreased guanine deaminase, as well as lower levels of hypoxanthine, indicated that DJB surgery limited the purine degradation process. In particular, the AMP/ATP ratio and phosphorylation of AMP-activated protein kinase increased after DJB surgery, which led to enhanced energy production and increased catabolic pathway activity, such as fatty acid oxidation and glucose transport. This study shows that bariatric surgery altered trans-sulfuration and purine metabolism in the liver. Characterization of these mechanisms increases our understanding of the benefits of bariatric surgery.

NADPH oxidase 4 regulates homocysteine metabolism and protects against acetaminophen-induced liver damage in mice

Glutathione is the major intracellular redox buffer in the liver and is critical for hepatic detoxification of xenobiotics and other environmental toxins. Hepatic glutathione is also a major systemic store for other organs and thus impacts on pathologies such as Alzheimer's disease, Sickle Cell Anaemia and chronic diseases associated with aging. Glutathione levels are determined in part by the availability of cysteine, generated from homocysteine through the transsulfuration pathway. The partitioning of homocysteine between remethylation and transsulfuration pathways is known to be subject to redox-dependent regulation, but the underlying mechanisms are not known. An association between plasma Hcy and a single nucleotide polymorphism within the NADPH oxidase 4 locus led us to investigate the involvement of this reactive oxygen species- generating enzyme in homocysteine metabolism. Here we demonstrate that NADPH oxidase 4 ablation in mice results in increased flux of homocysteine through the betaine-dependent remethylation pathway to methionine, catalysed by betaine-homocysteine-methyltransferase within the liver. As a consequence NADPH oxidase 4-null mice display significantly lowered plasma homocysteine and the flux of homocysteine through the transsulfuration pathway is reduced, resulting in lower hepatic cysteine and glutathione levels. Mice deficient in NADPH oxidase 4 had markedly increased susceptibility to acetaminophen-induced hepatic injury which could be corrected by administration of N-acetyl cysteine. We thus conclude that under physiological conditions, NADPH oxidase 4-derived reactive oxygen species is a regulator of the partitioning of the metabolic flux of homocysteine, which impacts upon hepatic cysteine and glutathione levels and thereby upon defence against environmental toxins.

Impact of Maternal Diet on the Epigenome during In Utero Life and the Developmental Programming of Diseases in Childhood and Adulthood

Exposure to environmental factors in early life can influence developmental processes and long-term health in humans. Early life nutrition and maternal diet are well-known examples of conditions shown to influence the risk of developing metabolic diseases, including type 2 diabetes mellitus and cardiovascular diseases, in adulthood. It is increasingly accepted that environmental compounds, including nutrients, can produce changes in the genome activity that, in spite of not altering the DNA sequence, can produce important, stable and, in some instances, transgenerational alterations in the phenotype. Epigenetics refers to changes in gene function that cannot be explained by changes in the DNA sequence, with DNA methylation patterns/histone modifications that can make important contributions to epigenetic memory. The epigenome can be considered as an interface between the genome and the environment that is central to the generation of phenotypes and their stability throughout the life course. To better understand the role of maternal health and nutrition in the initiation and progression of diseases in childhood and adulthood, it is necessary to identify the physiological and/or pathological roles of specific nutrients on the epigenome and how dietary interventions in utero and early life could modulate disease risk through epigenomic alteration.

An evolutionary perspective on the immunomodulatory role of hydrogen sulphide

Most preclinical studies on endogenous hydrogen sulphide signalling have given little consideration to the fact that the human body contains more bacterial cells than human cells, and that evolution provides the context for all biology. Whether hydrogen sulphide is pro or anti-inflammatory is heavily debated within the literature, yet researchers have not fully considered that invasive bacteria produce hydrogen sulphide, often at levels far above the endogenous levels of the host. Here I argue that if hydrogen sulphide is an endogenous signalling molecule with immunomodulatory functions, then it must have evolved in the presence of virulent bacteria which produce hydrogen sulphide. This context leads to two competing theories about the evolution of endogenous hydrogen sulphide signalling. The detectable emission theory proposes that bacteria produce hydrogen sulphide as part of normal metabolism and hosts which evolved to detect and respond to this hydrogen sulphide would gain a selective survival advantage. This predicts that the endogenous production of hydrogen sulphide is a mechanism which amplifies the bacterial hydrogen sulphide signal. The opposing protective agent theory predicts that bacterial hydrogen sulphide is an effective defence against the bactericidal mechanisms of the host's immune response. In this case, endogenous hydrogen sulphide production is either at inconsequential levels to alter the immune response, or is involved in the inflammation resolution process. Evidence suggests that the direct interactions of hydrogen sulphide with the bactericidal mechanisms of the innate immune system are most congruent with the protective agent theory. Therefore, I argue that if hydrogen sulphide is an immunomodulatory endogenous signalling molecule its effects are most likely anti-inflammatory.

The potential physiological crosstalk and interrelationship between two sovereign endogenous amines, melatonin and homocysteine

The antioxidant melatonin and the non-proteinogenic excitotoxic amino acid homocysteine (Hcy) are very distinct but related reciprocally to each other in their mode of action. The elevated Hcy level has been implicated in several disease pathologies ranging from cardio- and cerebro-vascular diseases to neurodegeneration owing largely to its free radical generating potency. Interestingly, melatonin administration potentially normalizes the elevated Hcy level, thereby protecting the cells from the undesired Hcy-induced excitotoxicity and cell death. However, the exact mechanism and between them remain obscure. Through literature survey we have found an indistinct but a vital link between melatonin and Hcy i.e., the existence of reciprocal regulation between them, and this aspect has been thoroughly described herein. In this review, we focus on all the possibilities of co-regulation of melatonin and Hcy at the level of their production and metabolism both in basal and in pathological conditions, and appraised the potential of melatonin in ameliorating homocysteinemia-induced cellular stresses. Also, we have summarized the differential mode of action of melatonin and Hcy on health and disease states.

Electrocardiogram Derived QRS Duration >120 ms is Associated With Elevated Plasma Homocysteine Levels in a Rural Australian Cross-Sectional Population

Homocysteine levels in the low to moderate range for cardiovascular risk have been previously associated with left ventricular cardiac hypertrophy (LVH). Electrocardiogram (ECG) derived QRS duration has also been used as an epidemiological screening marker for cardiac hypertrophy risk. QRS duration cut offs have not been previously modeled to assess homocysteine levels in community populations. Our aims are to determine if QRS duration is associated with an elevated homocysteine level in a cross-sectional Australian aging rural population.A retrospective study design utilizing a rural health diabetic screening clinic database containing observational data from the period January 9, 2002 till September 25, 2012. One hundred seventy-eight individuals (>21 years of age) from the database were included in the study. Inclusion criteria included being nondiabetic and having both a QRS duration measure and a matching homocysteine level within the same subject. All participants were from the Albury-Wodonga area, with a mean age of >64 years for both sexes.Mean population homocysteine plasma levels were 10.4 μmol/L (SD = 3.6). The mean QRS duration was 101.8 ms (SD = 17.4). Groups were stratified on the basis of QRS duration (≤120 ms [n = 157] and >120 ms [n = 21]). QRS duration subgroup (≤120 ms vs >120 ms) mean differences across homocysteine levels were 10.1 μmol/L (SD = 3.3) and 12.2 μmol/L (SD = 4.7), respectively (P = 0.016). Other ECG parameters (PQ interval, QTc interval, and QT dispersion) measurements were not significantly associated with differences in plasma homocysteine (P = not significant).We conclude that in community populations homocysteine may be moderately elevated when QRS durations are >120 ms. Small additional increases in homocysteine levels may suggest a risk factor for ECG diagnosis of LVH.

Interactions Between Nuclear Receptor SHP and FOXA1 Maintain Oscillatory Homocysteine Homeostasis in Mice

BACKGROUND & AIMS

Hyperhomocysteinemia is often associated with liver and metabolic diseases. We studied nuclear receptors that mediate oscillatory control of homocysteine homeostasis in mice.

METHODS

We studied mice with disruptions in Nr0b2 (called small heterodimer partner [SHP]-null mice), betaine-homocysteine S-methyltransferase (Bhmt), or both genes (BHMT-null/SHP-null mice), along with mice with wild-type copies of these genes (controls). Hyperhomocysteinemia was induced by feeding mice alcohol (National Institute on Alcohol Abuse and Alcoholism binge model) or chow diets along with water containing 0.18% DL-homocysteine. Some mice were placed on diets containing cholic acid (1%) or cholestyramine (2%) or high-fat diets (60%). Serum and livers were collected during a 24-hour light-dark cycle and analyzed by RNA-seq, metabolomic, and quantitative polymerase chain reaction, immunoblot, and chromatin immunoprecipitation assays.

RESULTS

SHP-null mice had altered timing in expression of genes that regulate homocysteine metabolism compared with control mice. Oscillatory production of S-adenosylmethionine, betaine, choline, phosphocholine, glyceophosphocholine, cystathionine, cysteine, hydrogen sulfide, glutathione disulfide, and glutathione, differed between SHP-null mice and control mice. SHP inhibited transcriptional activation of Bhmt and cystathionine γ-lyase by FOXA1. Expression of Bhmt and cystathionine γ-lyase was decreased when mice were fed cholic acid but increased when they were placed on diets containing cholestyramine or high-fat content. Diets containing ethanol or homocysteine induced hyperhomocysteinemia and glucose intolerance in control, but not SHP-null, mice. In BHMT-null and BHMT-null/SHP-null mice fed a control liquid, lipid vacuoles were observed in livers. Ethanol feeding induced accumulation of macrovesicular lipid vacuoles to the greatest extent in BHMT-null and BHMT-null/SHP-null mice.

CONCLUSIONS

Disruption of Shp in mice alters timing of expression of genes that regulate homocysteine metabolism and the liver responses to ethanol and homocysteine. SHP inhibits the transcriptional activation of Bhmt and cystathionine γ-lyase by FOXA1.