Homocysteine and neurologic disease

The effects of the MTHFR 677C>T (rs1801133) genetic variant on susceptibility and disability worsening in multiple sclerosis patients are mediated by homocysteine

BACKGROUND

Interactions between genetic and environmental variables contribute to the autoimmune inflammatory process in multiple sclerosis (MS). Elevated homocysteine levels, and vitamin D, vitamin B12, and folate deficiencies are some of the environmental factors associated with the pathogenesis of MS. Considering that the relationship between MTHFR 677C>T (rs1801133) genetic variant, homocysteine, and folate in patients with MS remains unclear and that their role were not extensively explored in the clinical course of the disease, we investigated whether this variant and plasma homocysteine and folate levels are associated with MS susceptibility, disability, disability progression, and inflammatory biomarkers.

METHODS

The case-control study included 163 patients with MS categorized using the Expanded Disability Status Scale (EDSS) as mild (EDSS<3) and moderate/high (EDSS≥3) disability, and 226 healthy controls (HC). Disability progression was evaluated using Multiple Sclerosis Severity Score (MSSS) and the MTHFR 677C>T variant was genotyped using real time polymerase chain reaction. The plasma levels of some inflammatory biomarkers were determined. Two new composed scores were proposed: the first, namely as inflammatory activity index (IAI), was entered as a latent vector extracted from the macrophage M1 + T helper (Th)1 + Th17 + Th2 + T regulatory (Treg) cytokines, + tumor necrosis factor (TNF)-α+ soluble TNF receptor (sTNFR)-1 + sTNFR2. The second score, namely MS-severity index was entered as a latent vector extracted from the EDSS + MSSS scores + MS diagnosis.

RESULTS

Patients with MS showed higher homocysteine and folate than controls (p < 0.001); homocysteine, and the M1, Th1, Th17, and Th2 Treg cytokine values were different between the three study groups and increased from HC to MS patients with mild disability and to MS patients with moderate/high disability (p < 0.0001). The levels of TNF-α and their soluble receptors sTNFR1 and sTNFR2 were higher in MS patients with EDSS≥3 than in the two other groups (EDSS<3 and HC) (p < 0.001). There was no association between the MTHFR 677 C > T genotypes and MS susceptibility, disability and disability progression (p > 0.05). Moreover, 21.8 % of the disability variance was explained by age, IAI and C-reactive protein (CRP) (all positively associated); 10.9 % of the disability progression variance was predicted by IAI and CRP (both positively) and 25-hydroxyvitamin D (negatively), whereas 54.4 % of the severity index (MS-EDSS-MSSS) was explained by the regression on age, IAI, homocysteine, folate, and CRP (all positively), and adiponectin, body mass index, and 25-hydroxyvitamin D (all negatively), female sex, and the MTHFR 677 TT genotype. In patients and controls, 16.6 % of the variance in the homocysteine was explained by the MTHFR 677 TT genotype and age (both positively), folate (negatively) and male sex.

CONCLUSION

The MTHFR 677C>T variant has an indirect effect on the increase in disability in patients with MS, which also depends on factors such as age, sex, ad folate status.

Vitamin B12 status and hyperhomocysteinemia in patients with Rheumatoid arthritis treated with methotrexate and folic acid

BACKGROUND

Rheumatoid arthritis (RA) is an inflammatory arthritis in which the immune system targets synovial joints. Methotrexate serves as the mainstay of treatment for RA due to its efficacy. However, patients treated with methotrexate are uniquely at risk for vitamin B12 deficiency and hyperhomocysteinemia due to coincident disease risk factors and the fact that methotrexate use is associated with malabsorption. The objective of this study was to assess for vitamin B12 deficiency among patients with RA treated with methotrexate and folic acid.

METHODS

This cross-sectional study included 50 patients with RA treated with methotrexate and folic acid and 49 patients with RA treated with other therapies. Patients were matched by age, sex, race, renal function, and disease activity. We compared plasma vitamin B12, methylmalonic acid, and homocysteine levels between these two groups utilizing quantitative and categorical analyses.

RESULTS

Thirty-seven (74%) RA patients on methotrexate and folic acid had elevated plasma homocysteine levels compared with only 27 (55%) RA patients receiving other therapies (P < 0.05). The proportion of patients with low vitamin B12 and high methylmalonic acid levels did not differ between the two groups.

CONCLUSIONS

Our data show high plasma homocysteine levels among RA patients treated with methotrexate and folic acid. While plasma vitamin B12 levels were similar between the two groups, high plasma homocysteine is also a sensitive marker of vitamin B12 deficiency. Additional studies should evaluate for the presence of clinical features of vitamin B12 deficiency and hyperhomocysteinemia among RA patients treated with methotrexate and folic acid.

Relationship Between Plasma Homocysteine and Bone Density, Lean Mass, Muscle Strength and Physical Function in 1480 Middle-Aged and Older Adults: Data from NHANES

Hyperhomocysteinemia induces oxidative stress and chronic inflammation (both of which are catabolic to bone and muscle); thus, we examined the association between homocysteine and body composition and physical function in middle-aged and older adults. Data from the National Health and Nutrition Examination Survey was used to build regression models. Plasma homocysteine (fluorescence immunoassay) was used as the exposure and bone mineral density (BMD; dual-energy X-ray absorptiometry; DXA), lean mass (DXA), knee extensor strength (isokinetic dynamometer; newtons) and gait speed (m/s) were used as outcomes. Regression models were adjusted for confounders (age, sex, race/Hispanic origin, height, fat mass %, physical activity, smoking status, alcohol intakes, cardiovascular disease, diabetes, cancer and vitamin B12). All models accounted for complex survey design by using sampling weights provided by NHANES. 1480 adults (median age: 64 years [IQR: 56, 73]; 50.3% men) were included. In multivariable models, homocysteine was inversely associated with knee extensor strength (β = 0.98, 95% CI 0.96, 0.99, p = 0.012) and gait speed (β = 0.85, 95% CI 0.78, 0.94, p = 0.003) and borderline inversely associated with femur BMD (β = 0.84, 95% CI 0.69, 1.03, p = 0.086). In the sub-group analysis of older adults (≥ 65 years), homocysteine was inversely associated with gait speed and femur BMD (p < 0.05) and the slope for knee extensor strength and whole-body BMD were in the same direction. No significant associations were observed between homocysteine and total or appendicular lean mass in the full or sub-group analysis. We found inverse associations between plasma homocysteine and muscle strength/physical function, and borderline significant inverse associations for femur BMD.

A systematic review and meta-analysis expounding the relationship between methylene tetrahydrofolate reductase gene polymorphism and the risk of intracerebral hemorrhage among populations

Background: The relationship between methylenetetrahydrofolate reductase (MTHFR) gene C677T and A1298C polymorphism with the risk of intracerebral hemorrhage (ICH) has remained to be controversial in recent years. This meta-analysis is aimed to confirm the association of these.

Methods: Systematically searching the related studies from the PubMed, Embase, Cochrane Library, China national knowledge internet database from 1 January 1990 to 1 June 2022. The odd ratio (ORs) and 95% confidence interval (CIs) of gene-disease correlation in various gene models were calculated by fixed or random effect model of meta-analysis. We included 20 case-control studies in this meta-analysis with a total of 1,989 ICH patients and 4,032 health controls originated from Asian, Caucasian, and African populations.

Results: The statistical analysis demonstrated the association of MTHFR C677T gene polymorphism with ICH in allele model [OR_{T VS. C} = 1.20 (95%CI: 1.06–1.36)]; homozygote model [OR _{TT VS. CC} = 1.50 (95%CI: 1.20–1.88)]; dominant model [OR _{CT+ TT VS. CC} = 1.23 (95%CI: 1.03–1.48)] and recessive model [OR_{TT VS. CT+CC} = 1.37 (95%CI: 1.17–1.60)]. Besides, we also found the relationship of MTHFR C677T gene polymorphism with Asian in four comparison model (OR_{T VS. C} = 1.19.95%CI:1.09–1.37, OR_{TT VS. CC} = 1.46.95%CI: 1.15–1.85, OR _{CT+ TT VS. CC} = 1.25.95%CI: 1.01–1.54, OR_{TT VS. CT+CC} = 1.34.95%CI: 1.54–1.17) and Caucasian in four comparison model (OR_{T VS. C} = 1.90.95%CI: 1.22–2.97, OR_{TT VS. CC} = 2.67.95%CI: 1.42–5.00, OR _{CT+ TT VS. CC} = 1.56.95%CI: 1.05–2.32, OR_{TT VS. CT+CC} = 2.25.95%CI: 1.46–4.00). But no statistically significant correlation between A1298C polymorphism and the occurrence of ICH was detected in four studies.

Conclusion: MTHFR C677T gene polymorphism increases the risk of ICH in Asian and Caucasian populations but has no impact on the incidence in African communities. More importantly, the risk of ICH increases in TT genotype individuals in comparison to CT and CC genotype individuals in Asian and Caucasian populations.

Oxidative stress and antioxidant defenses in mild cognitive impairment: A systematic review and meta-analysis

This study aims to systematically review and meta-analyze the nitro-oxidative stress (O&NS)/antioxidant (ANTIOX) ratio in the peripheral blood of people with mild cognitive impairment (MCI). We searched PubMed, Scopus, Google Scholar, and Web of Science for articles published from inception until July 31, 2021. Forty-six studies on 3.798 MCI individuals and 6.063 healthy controls were included. The O&NS/ANTIOX ratio was significantly higher in MCI than in controls with a Standardized Mean Difference (SMD)= 0.378 (95% CI: 0.250; 0.506). MCI individuals showed increased lipid peroxidation (SMD=0.774, 95%CI: 4.416; 1.132) and O&NS-associated toxicity (SMD=0.621, CI: 0.377; 0.865) and reduced glutathione (GSH) defenses (SMD=0.725, 95%CI: 0.269; 1.182) as compared with controls. MCI was also accompanied by significantly increased homocysteine (SMD=0.320, CI: 0.059; 0.581), but not protein oxidation, and lowered non-vitamin (SMD=0.347, CI: 0.168; 0.527) and vitamin (SMD=0.564, CI: 0.129; 0.999) antioxidant defenses. The results show that MCI is at least in part due to increased neuro-oxidative toxicity and suggest that treatments targeting lipid peroxidation and the GSH system may be used to treat or prevent MCI.

The effects of regular swimming exercise during sodium valproate treatment on seizure behaviors and EEG recordings in pentylenetetrazole-kindled rats

We investigated the effects of alone/combined regular swimming exercise and sodium valproate on epileptic seizure behaviors and EEG recordings, anti-oxidative mechanism, learning, and memory in pentylenetetrazole (PTZ)-kindled rats. Forty-eight healthy rats were randomly divided into eight equal groups as control (CONT), swimming exercise (EX), sodium valproate (SV), SV+EX, PTZ, EX+PTZ, SV+PTZ and SV+EX+PTZ. The rats were forced to regular swimming exercise for 60 min every other day, 13 doses of PTZ (40 mg/kg) were given to induce epileptic seizures and 200 mg/kg SV was given for 28 days. Epileptic seizures were evaluated by visual observation and EEG recordings (total spike numbers and number of epileptiform discharges). Memory and learning skills were assessed with passive avoidance test. According to our visual seizure observations, seizure latency was prolonged only in SV+EX+PTZ (p < 0.001) group, seizure severity score decreased in SV+PTZ (p < 0.05) and SV+EX+PTZ (p < 0.001) groups and seizure frequency was reduced in SV+PTZ (p < 0,001), EX+PTZ (p < 0,001), and SV+EX+PTZ (p < 0,001) groups. Total spike numbers and number of epileptiform discharges highly increased in PTZ group, whereas they decreased in swimming exercise and/or SV treatment groups. The most effective result was seen in the combined therapy group. Memory deficit was observed in PTZ -kindling group, but it didn't change with exercise or SV. Based on our results, regular swimming exercise had positive effects on PTZ-induced seizure frequency, and combined therapy of regular swimming exercise and SV is the most effective way to ameliorate visual seizure behaviors and decrease spike numbers and number of epileptiform discharges according to EEG recordings. Regular swimming exercise could be an alternative option to reduce the dose of SV and the side effects of SV can be avoided in clinical aspects.

Homocysteine as a Predictor Tool in Multiple Sclerosis

Multiple sclerosis (MS) is a progressive and irreversible disease which affects the central nervous system (CNS) with still unknown etiology. Our study aimes to establish the homocysteine pattern that can predict the MS diseases progression and to identify a potential disease progression marker that can be easy to perform and non-invasive, in order to predict the diseases outcome. In order to achieve this goal, we included 10 adult RRMS subjects, 10 adult SPMS subjects and 10 age-matched healthy subjects. The homocysteine plasma level was measured using automated latex enhanced immunoassay and the cobalamin and folate measurements were performed using automated chemiluminescence immunoassay (CLIA). HCR was calculated by dividing the homocysteine plasma level by cobalamin plasma level. We found that the homocysteine level in plasma of both RRMS patients and SPMS group are significantly increased compared with the control group. There is a significantly higher concentration of homocysteine in SPMS group compared with the RRMS group. In addition, the HCR is significantly increased in SPMS compared with the RRMS group and is a very good index of disease severity.

Homocysteine fibrillar assemblies display cross-talk with Alzheimer's disease β-amyloid polypeptide

High levels of homocysteine are reported as a risk factor for Alzheimer's disease (AD). Correspondingly, inborn hyperhomocysteinemia is associated with an increased predisposition to the development of dementia in later stages of life. Yet, the mechanistic link between homocysteine accumulation and the pathological neurodegenerative processes is still elusive. Furthermore, despite the clear association between protein aggregation and AD, attempts to develop therapy that specifically targets this process have not been successful. It is envisioned that the failure in the development of efficacious therapeutic intervention may lie in the metabolomic state of affected individuals. We recently demonstrated the ability of metabolites to self-assemble and cross-seed the aggregation of pathological proteins, suggesting a role for metabolite structures in the initiation of neurodegenerative diseases. Here, we provide a report of homocysteine crystal structure and self-assembly into amyloid-like toxic fibrils, their inhibition by polyphenols, and their ability to seed the aggregation of the AD-associated β-amyloid polypeptide. A yeast model of hyperhomocysteinemia indicates a toxic effect, correlated with increased intracellular amyloid staining that could be rescued by polyphenol treatment. Analysis of AD mouse model brain sections indicates the presence of homocysteine assemblies and the interplay between β-amyloid and homocysteine. This work implies a molecular basis for the association between homocysteine accumulation and AD pathology, potentially leading to a paradigm shift in the understanding of AD initial pathological processes.

Epidemiology and (Patho)Physiology of Folic Acid Supplement Use in Obese Women before and during Pregnancy

Preconception folic acid supplement use is a well-known method of primary prevention of neural tube defects (NTDs). Obese women are at a higher risk for having a child with a NTD. As different international recommendations on folic acid supplement use for obese women before and during pregnancy exist, this narrative review provides an overview of epidemiology of folate deficiency in obese (pre)pregnant women, elaborates on potential mechanisms underlying folate deficiency, and discusses considerations for the usage of higher doses of folic acid supplements. Women with obesity more often suffer from an absolute folate deficiency, as they are less compliant to periconceptional folic acid supplement use recommendations. In addition, their dietary folate intake is limited due to an unbalanced diet (relative malnutrition). The association of obesity and NTDs also seems to be independent of folate intake, with studies suggesting an increased need of folate (relative deficiency) due to derangements involved in other pathways. The relative folate deficiency, as a result of an increased metabolic need for folate in obese women, can be due to: (1) low-grade chronic inflammation (2) insulin resistance, (3) inositol, and (4) dysbiotic gut microbiome, which plays a role in folate production and uptake. In all these pathways, the folate-dependent one-carbon metabolism is involved. In conclusion, scientific evidence of the involvement of several folate-related pathways implies to increase the recommended folic acid supplementation in obese women. However, the physiological uptake of synthetic folic acid is limited and side-effects of unmetabolized folic acid in mothers and offspring, in particular variations in epigenetic (re)programming with long-term health effects, cannot be excluded. Therefore, we emphasize on the urgent need for further research and preconception personalized counseling on folate status, lifestyle, and medical conditions.

Involvements of Hyperhomocysteinemia in Neurological Disorders

Homocysteine (HCY), a physiological amino acid formed when proteins break down, leads to a pathological condition called hyperhomocysteinemia (HHCY), when it is over a definite limit. It is well known that an increase in HCY levels in blood, can contribute to arterial damage and several cardiovascular disease, but the knowledge about the relationship between HCY and brain disorders is very poor. Recent studies demonstrated that an alteration in HCY metabolism or a deficiency in folate or vitamin B12 can cause altered methylation and/or redox potentials, that leads to a modification on calcium influx in cells, or into an accumulation in amyloid and/or tau protein involving a cascade of events that culminate in apoptosis, and, in the worst conditions, neuronal death. The present review will thus summarize how much is known about the possible role of HHCY in neurodegenerative disease.

Clinical Validation of a Multi-Biomarker Assay for the Evaluation of Chronic Pain Patients in a Cross-Sectional, Observational Study

INTRODUCTION

Chronic pain assessment and post-treatment evaluation continues to be challenging due to a lack of validated, objective tools to measure patient outcomes. Validation of mechanistic pain biomarkers would allow clinicians to objectively identify abnormal biochemistry contributing to painful symptoms.

METHODS

We describe the clinical validation of a multi-biomarker assay with algorithmic analysis known as the Foundation Pain Index (FPI) in diverse cohorts of chronic pain patients in a prospective, cross-sectional, observational validation study. Levels of 11 urinary pain biomarkers were measured and tabulated using a proprietary algorithm to generate FPI scores for chronic pain subjects (N = 153) and age- and sex-matched pain-free controls (N = 334).

RESULTS

FPI scores were significantly correlated with the 36-Item Short Form Health Survey (SF-36) scores among chronic pain subjects (P value < 0.015) and specific components of SF-36, including emotional well-being, limitations due to emotional problems, and general health (P value < 0.05). Area under ROC analysis (AUROC) revealed FPI to accurately distinguish biomarker profiles between pain-free and chronic pain cohorts (AUROC: 0.7490, P value < 0.0001) as well as the SF-36 scores between chronic pain subjects with low vs. high FPI scores (AUROC: 0.7715, P value < 0.01).

CONCLUSIONS

Our findings establish the validity and discriminatory power of a novel multi-biomarker test that evaluates the role of biochemistry in chronic pain and correlates with clinical assessments of patients. This test provides novel, reproducible, objective data which may pave the way for non-opioid therapeutic strategies to treat chronic pain.

Impact of Hyperhomocysteinemia and Different Dietary Interventions on Cognitive Performance in a Knock-in Mouse Model for Alzheimer's Disease

BACKGROUND

Hyperhomocysteinemia is considered a possible contributor to the complex pathology of Alzheimer's disease (AD). For years, researchers in this field have discussed the apparent detrimental effects of the endogenous amino acid homocysteine in the brain. In this study, the roles of hyperhomocysteinemia driven by vitamin B deficiency, as well as potentially beneficial dietary interventions, were investigated in the novel App^NL-G-F knock-in mouse model for AD, simulating an early stage of the disease.

METHODS

Urine and serum samples were analyzed using a validated LC-MS/MS method and the impact of different experimental diets on cognitive performance was studied in a comprehensive behavioral test battery. Finally, we analyzed brain samples immunohistochemically in order to assess amyloid-β (Aβ) plaque deposition.

RESULTS

Behavioral testing data indicated subtle cognitive deficits in App^NL-G-F compared to C57BL/6J wild type mice. Elevation of homocysteine and homocysteic acid, as well as counteracting dietary interventions, mostly did not result in significant effects on learning and memory performance, nor in a modified Aβ plaque deposition in 35-week-old App^NL-G-F mice.

CONCLUSION

Despite prominent Aβ plaque deposition, the App^NL-G-F model merely displays a very mild AD-like phenotype at the investigated age. Older App^NL-G-F mice should be tested in order to further investigate potential effects of hyperhomocysteinemia and dietary interventions.

Homocysteinemia is Associated with the Presence of Microbleeds in Cognitively Impaired Patients

BACKGROUND & OBJECTIVE

Homocysteine is possibly associated with cerebral small vessel diseases such as leukoaraiosis, silent brain infarction and cerebral microbleeds, which are in turn associated with cognitive dysfunction. We aimed to examine the relationships between cerebral microbleeds (CMBs) and plasma total homocysteine (tHcy) level, methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and cognitive function.

METHODS

A total of 819 patients with memory disturbance who visited a dementia clinic consecutively were included in this study. We retrospectively collected demographic, clinical and laboratory data including tHcy level, MTHFR C677T polymorphism and Mini-Mental State Examination (MMSE). All patients underwent brain MRI including fluid attenuated inversion recovery (FLAIR) image and T2*-weighed gradient-echo (GRE) image. Logistic regression analysis was performed to test the association between risk factors and the presence of microbleeds.

RESULTS

One hundred and sixty-one (19.7%) patients had CMBs, of whom 88 (54.7%) had CMBs in the lobar region. CMBs were more common in older hypertensive male patients with hyperhomocysteinemia. In multivariable analysis, plasma tHcy remained an independent predictor of the presence of CMBs after adjusting other confounders (OR: 1.035, 95% CI: 1.009-1.062, p = 0.009). Higher plasma tHcy level was also associated with number of CMBs, TT MTHFR genotype, and lower MMSE scores.

CONCLUSIONS

Elevated plasma tHcy level is related to high prevalence of CMBs and cognitive dysfunction. Lowering plasma tHcy could be helpful in cognitively impaired patients who have CMBs or the MTHFR TT genotype.

Hyperhomocysteinemia in patients with acute porphyrias: A potentially dangerous metabolic crossroad?

BACKGROUND

Acute porphyrias (AP) are characterized by heme deficiency and induction of hepatic 5-aminolevulinate synthase (ALAS1). Hyperhomocysteinemia (HHcy) is associated with endothelial damage, neurotoxicity and increased risk for vascular diseases. Interestingly, both heme biosynthesis and sulphur amino acid metabolism require vitamin B6, (Pyridoxal-phosphate, PLP) an important cofactor of ALAS1 and of cystathionine β-synthase (CBS) and cystathionine γ-lyase (CGL) enzymes that catabolize homocysteine (Hcy). Moreover, heme itself is an important cofactor for CBS.

AIM

to assess plasma Hcy status and HHcy main determinants in patients with AP.

MATERIALS AND METHODS

A total of 46 patients with AP (31 with Acute Intermittent Porphyria,15 with Variegate Porphyria) were assessed for clinical status (symptomatic vs. asymptomatic), serum Hcy, Cysteine (Cys), Vit.B6, Vit.B12, red blood cell folates and urinary delta-aminolevulinic acid (ALA) and porphobilinogen(PBG) levels (mean of six measurements).

RESULTS

Symptomatic AP patients had significantly higher urinary ALA and PBG levels, plasma Hcy, HHcy prevalence and Hcy/Cys ratio when compared to asymptomatic carriers of AP. Even though no significant correlation was observed between ALA/PBG urinary levels and serum Hcy levels, patients with higher levels of ALA and PBG had significantly higher levels of Hcy, a higher prevalence of moderate-to severe HHcy and serum PLP levels below the 25^th percentile of a reference assessment with 300 healthy Italian subjects(<45nmol/L).

CONCLUSIONS

Most patients with symptomatic AP present HHcy resulting from alterations in sulphur amino acid metabolism. HHcy may represent an indirect marker of ALAS1 induction and its prevalence may be suggestive of a role of HHcy in the pathogenesis and/or comorbidities of AP.

The Relationship Between Blood Hypoxia-Inducible Factor-1α, Fetuin-A, Fibrinogen, Homocysteine, and Amputation Level

Reduced life expectancy has resulted from an increased incidence of chronic complications in patients with diabetes. The diabetic foot is one of these complications and generally presents together with diabetic neuropathy and vascular insufficiency. Hypoxia-inducible factor-1α (HIF-1α) is important in developing the adaptation response to hypoxia and facilitates healing through regulation of keratinocyte migration and epithelium restoration in wounds. Fetuin-A is a transporter protein that is synthesized in the liver and inhibits vascular and ectopic calcifications. It has been observed that altered fetuin-A is associated with peripheral artery disease through vascular calcification and is associated with inflammation and metabolic syndrome occurrence in diabetic patients. Fibrinogen is an acute-phase reactant and has a major role in homeostasis, tissue repair, and wound healing. Increased fibrinogen blood level is one of the factors that facilitates the hypercoagulability in diabetics. Homocysteine has atherogenic features and causes vascular toxicity by enhancing low-density lipoprotein oxidation. We evaluated the association of serum HIF-1α, fetuin-A, fibrinogen, and homocysteine levels with amputation in 31 patients diagnosed with diabetes mellitus. According to our evaluation, a negative correlation was determined between fetuin-A and amputation level (P = .012, r = -0.450), which was statistically significant. Unfortunately, there was no significant correlation between HIF-1α, fibrinogen, homocysteine, and amputation level (P > .05). As a result, it was suggested that vascular calcification due to fetuin-A deficiency may be important in the diabetic foot pathogenesis and that fetuin-A levels may be a predictor for amputation level.

DNA methylation patterns of LINE-1 and Alu for pre-symptomatic dementia in type 2 diabetes

The identification of early markers of dementia is important for higher-risk populations such as those with type 2 diabetes (T2D). Retrotransposons, including long interspersed nuclear element 1 (LINE-1) and Alu, comprise ~40% of the human genome. Although dysregulation of these retrotransposons can induce aberrant gene regulation and genomic instability, their role in the development of pre-symptomatic dementia (PSD) among T2D patients is unknown. Here, we examined locus-specific changes in LINE-1 and Alu methylation in PSD and the potential to offset these changes via supplementation with folate and vitamin B₁₂. We interrogated DNA methylation patterns corresponding to 22,352 probes for LINE-1 and Alu elements using publicly-available Illumina Infinium 450K methylation datasets from i) an 18-month prospective study in 28 T2D patients (GSE62003) and ii) an intervention study in which 44 individuals were supplemented with folic acid (400 μg/day) and vitamin B₁₂ (500 μg/day) over two years (GSE74548). We identified 714 differentially methylated positions (DMP) mapping to retrotransposons in T2D patients who developed PSD in comparison to those who did not (P_FDR < 0.05), comprised of 2.4% (228 probes) of all LINE-1 probes and 3.8% (486 probes) of all Alu probes. These loci were enriched in genes with functions related to Alzheimer's disease and cognitive decline, including GNB5, GNG7 and PKN3 (p < 0.05). In older individuals supplemented with folate/vitamin B₁₂, 85 (11.9%) PSD retrotransposon loci showed significant changes in methylation (p < 0.05): participants with the MTHFR CC genotype predominantly showed hypermethylation at these loci, while hypomethylation was observed more frequently in those with the TT genotype. In T2D patients, LINE-1 and Alu elements are differentially methylated in PSD in a locus-specific manner and may offer clinical utility in monitoring risk of dementia. Further work is required to examine the potential for dietary supplementation in lowering the risk of PSD.

Homocysteine, vitamin B12, and folate levels in patients with multiple sclerosis in Chinese population: A case-control study and meta-analysis

BACKGROUND

Current studies suggested discrepancies on the correlations between multiple sclerosis (MS) and blood levels of homocysteine (Hcy), vitamin B12 (VB12), and folate. We performed a case-control study and meta-analysis to help resolve the controversy of these lab values in Chinese patients with MS.

METHODS

We recruited 80 Chinese MS patients, 86 age/sex matched neurological controls (patients with peripheral vertigo or sleep disorders), and 80 age- and sex-matched healthy controls. Serum Hcy levels were measured using flourimetric high-performance liquid chromatography, serum levels of VB12 and folate using immune assay. A literature search of PubMed, Embase, Web of Science, Chinese National Knowledge Infrastructure, Wanfang, and SinoMed was conducted for case-control studies with pure Chinese populations published up to March 16, 2019. The effective size was estimated by the pooled standardized mean difference (SMD) and associated 95% confidence interval (CI).

RESULTS

The case-control study results suggest higher Hcy levels (mean ± SD) and frequency of hyperhomocysteinemia in the Chinese MS cases than control groups (all p < 0.001), lower for VB12 levels (mean ± SD, p = 0.043 or 0.039). No significant difference was observed for levels of folate (mean ± SD, both p > 0.05), and for frequency of folate or VB12 deficiency (all p > 0.05). Analysis of pooled SMDs and 95% CIs suggested increased Hcy levels in Chinese MS patients (SMD: 2.31, 95% CI: 1.33-3.28, p < 0.001), and in relapsing or remitting cases relative to controls (SMD: 0.94 or 0.85, 95% CI: 0.49-1.39 or 0.35-1.34, both p < 0.001). The meta-analysis results also suggested reduced VB12 levels in Chinese MS patients (SMD: -0.30, 95% CI: -0.46-0.14, p < 0.001), and in relapsing MS patients compared to controls (SMD: -0.31, 95% CI: -0.47-0.15, p < 0.001), while no statistical difference for cases in remission. No significant difference was observed for levels folate in all comparisons.

CONCLUSION

Patients with MS tend to have increased blood Hcy levels compared to controls. MS patients of Chinese origin and those in relapse may have decreased levels of VB12. Hcy and VB12 may contribute to pathogenesis of the disease, and VB12 may correlate with MS relapse.

Use of Direct Current Electroretinography for Analysis of Retinal Pigment Epithelium Function in Mouse Models

A monolayer of pigmented epithelial cells, the retinal pigment epithelium (RPE), supports photoreceptor function in many ways. Consistent with these roles, RPE dysfunction underlies a number of hereditary retinal disorders. To monitor RPE function in vivo models for these conditions, we adapted an electroretinographic (ERG) technique based on direct current amplification (DC-ERG). This chapter describes the main features of this approach and its application to mouse models involving the RPE.

Postnatal Administration of Homocysteine Induces Cerebellar Damage in Rats: Protective Effect of Folic Acid

A widely held view suggests that homocysteine (Hcy) can contribute to neurodegeneration through promotion of oxidative stress. There is evidence that homocysteine is toxic to cerebellar Purkinje neurons in vitro; however, in vivo action of Hcy on Purkinje cell has not been investigated so far. Thus, this study was designed to evaluate the Hcy effects on neonatal rat cerebellum and cerebellar oxidative stress. We also evaluated the folic acid effects on biochemical alterations elicited by hyperhomocysteinemia (hHcy) in the cerebellum. Group I received normal saline, group II received Hcy subcutaneously twice a day at 8-h intervals (0.3-0.6 μmol/g body weight), group III received Hcy + folic acid (0.011 μmol/g body weight), and group IV received folic acid on postnatal day (PD) 4 until 25. On day 25, superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities in the cerebellum and motor cortex were assayed. Malondialdehyde (MDA) levels were also evaluated as a marker of lipid peroxidation. Rotarod and locomotor activity tests were performed in PD 25-27. Our results indicated that administration of Hcy increased plasma, cortical, and cerebellar total Hcy levels; reduced GPx activity; and induced lipid peroxidation in the cerebellum. Hcy impaired performance on the rotarod in rats. However, treatment with folic acid significantly attenuated motor coordination impairment, GPx activity reduction, the lipid peroxidation process, and significantly reduced plasma total Hcy levels. Histological analysis indicated that Hcy could decrease Purkinje cell count and folic acid prevented this toxic effect. We conclude that Hcy can induce neurotoxicity and folic acid has neuroprotective effects against cerebellar Hcy toxicity.

Metabolic etiologies in West syndrome

West syndrome (WS) is an early life epileptic encephalopathy associated with infantile spasms, interictal electroencephalography (EEG) abnormalities including high amplitude, disorganized background with multifocal epileptic spikes (hypsarrhythmia), and often neurodevelopmental impairments. Approximately 64% of the patients have structural, metabolic, genetic, or infectious etiologies and, in the rest, the etiology is unknown. Here we review the contribution of etiologies due to various metabolic disorders in the pathology of WS. These may include metabolic errors in organic molecules involved in amino acid and glucose metabolism, fatty acid oxidation, metal metabolism, pyridoxine deficiency or dependency, or acidurias in organelles such as mitochondria and lysosomes. We discuss the biochemical, clinical, and EEG features of these disorders as well as the evidence of how they may be implicated in the pathogenesis and treatment of WS. The early recognition of these etiologies in some cases may permit early interventions that may improve the course of the disease.

Ameliorative effects of supplemental folinic acid on Lamotrigine-induced fetal malformations in the mouse

Data from our previous work indicate that Lamotrigine (LTG) is teratogenic in the mouse. In the present study, we attempted to determine the possible protective effects of exogenous folate on LTG-induced fetal anomalies in TO mouse. Experiment I entailed administering 4 mg/kg of folinic acid (FA) and (25 mg/kg) of LTG intraperitoneally three times on gestation day (GD) 8 to a group of mice; other groups were a group that received similar volumes of saline, a group that received LTG and Saline, a group that received FA and saline. Experiment 2 involved administering groups of mice with daily 3 doses FA (or proportionate volume of saline) on GD 5 through 10 and either 3 doses of saline on GD8, or 3 doses of LTG on GD8. Maternal plasma concentrations of FA, vitamin B12 and homocysteine were determined an hour after the last injection from one-half of all animals. The other half were allowed to go to term (GD18) when they were euthanized and their fetuses were examined for visceral and skeletal malformations. A high incidence of resorption, abortion, embryolethality, congenital malformations, and intrauterine growth restriction (IUGR), was observed in the LTG-treated group. Folic acid and B12 levels were decreased and homocysteine concentration increased significantly in LTG groups. Mice receiving LTG with FA had normal levels of folate, Vitamin B12 and homocysteine levels, and the fetuses had fewer birth defects similar to the controls which were given saline only. Supplemental FA ameliorated to a great extent the LTG-induced embryonic resorption and malformations and restored the FA status.

The pharmacogenomics of severe traumatic brain injury

Pharmacotherapy for traumatic brain injury (TBI) is focused on resuscitation, prevention of secondary injury, rehabilitation and recovery. Pharmacogenomics may play a role in TBI for predicting therapies for sedation, analgesia, seizure prevention, intracranial pressure-directed therapy and neurobehavioral/psychiatric symptoms. Research into genetic predictors of outcomes and susceptibility to complications may also help clinicians to tailor therapeutics for high-risk individuals. Additionally, the expanding use of genomics in the drug development pipeline has provided insight to novel investigational and repurposed medications that may be useful in the treatment of TBI and its complications. Genomics in the context of treatment and prognostication for patients with TBI is a promising area for clinical progress of pharmacogenomics.

Comparison of Protein N-Homocysteinylation in Rat Plasma under Elevated Homocysteine Using a Specific Chemical Labeling Method

Elevated blood concentrations of homocysteine have been well established as a risk factor for cardiovascular diseases and neuropsychiatric diseases, yet the etiologic relationship of homocysteine to these disorders remains poorly understood. Protein N-homocysteinylation has been hypothesized as a contributing factor; however, it has not been examined globally owing to the lack of suitable detection methods. We recently developed a selective chemical method to label N-homocysteinylated proteins with a biotin-aldehyde tag followed by Western blotting analysis, which was further optimized in this study. We then investigated the variation of protein N-homocysteinylation in plasma from rats on a vitamin B₁₂ deficient diet. Elevated “total homocysteine” concentrations were determined in rats with a vitamin B₁₂ deficient diet. Correspondingly, overall levels of plasma protein N-homocysteinylation displayed an increased trend, and furthermore, more pronounced and statistically significant changes (e.g., 1.8-fold, p-value: 0.03) were observed for some individual protein bands. Our results suggest that, as expected, a general metabolic correlation exists between “total homocysteine” and N-homocysteinylation, although other factors are involved in homocysteine/homocysteine thiolactone metabolism, such as the transsulfuration of homocysteine by cystathionine β-synthase or the hydrolysis of homocysteine thiolactone by paraoxonase 1 (PON1), may play more significant or direct roles in determining the level of N-homocysteinylation.

1,25-Dihydroxyvitamin D3 exerts neuroprotective effects in an ex vivo model of mild hyperhomocysteinemia

Elevated plasma homocysteine (Hcy) levels have been detected in patients with various neurodegenerative conditions. Studies of brain tissue have revealed that hyperhomocysteinemia may impair energy metabolism, resulting in neuronal damage. In addition, new evidence has indicated that vitamin D plays crucial roles in brain development, brain metabolism and neuroprotection. The aim of this study was to investigate the neuroprotective effects of 1,25-dihydroxivitamin D3 (calcitriol) in cerebral cortex slices that were incubated with a mild concentration of Hcy. Cerebral cortex slices from adult rats were first pre-treated for 30 min with one of three different concentrations of calcitriol (50 nM, 100 nM and 250 nM), followed by Hcy for 1h to promote cellular dysfunction. Hcy caused changes in bioenergetics parameters (e.g., respiratory chain enzymes) and mitochondrial functions by inducing changes in mitochondrial mass and swelling. Here, we used flow cytometry to analyze neurons that were double-labelled with Propidium Iodide (PI) and found that Hcy induced an increase in NeuN(+)/PI cells but did not affect GFAP(+)/Pi cells. Hcy also induced oxidative stress by increasing reactive oxygen species generation, lipid peroxidation and protein damage and reducing the activity of antioxidant enzymes (e.g., SOD, CAT and GPx). Calcitriol (50 nM) prevented these alterations by increasing the level of the vitamin D receptor. Our findings suggest that using calcitriol may be a therapeutic strategy for treating the cerebral complications caused by Hcy.

Folic acid supplementation on homocysteine levels in children taking antiepileptic drugs: A randomized controlled trial

OBJECTIVES

To assess the level of homocysteine (tHcy) in children taking AEDs and to study whether daily oral supplementation of folic acid for 1 month will reduce the tHcy level.

MATERIALS AND METHODS

This was a double-blinded, randomized control trial conducted in Institute of Maternal and Child Health, Kozhikode, India. Totally 60 children were recruited and of them, 48 were enrolled. Of these children, 32 were assigned to the experimental group and 16 to the control group. Baseline data collection and tHcy estimation were done. One mg folic acid tablets were given to the experimental group and placebo tablets to the control group for 30 days. tHcy levels were re-estimated after 1 month follow-up. Statistical significance was tested by χ(2) test, and paired and unpaired t-tests, as appropriate. Correlation was tested by Pearson correlation test and P value less than 0.05 was taken as the cut-off for statistical significance.

RESULTS

Baseline plasma tHcy concentrations in both groups were comparable [11.90 (6.3) and 13.02 (2.4) μmol/l, respectively]. During the follow-up period, no increase in seizure episodes or no serious adverse reactions were noticed in either group. The reduction of tHcy in the experimental group was 1.92 μmol/l (P = 0.04) and in the control group, there was an increase of 1.05 μmol/l (P = 0.16).

CONCLUSIONS

In children on AED treatment, folic acid supplementation may reduce tHcy level and thus reduce CVD risk.

Association between methylenetetrahydrofolate reductase C677T polymorphism and epilepsy susceptibility: a meta-analysis

PURPOSE

Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism has been implicated as a potential risk factor for epilepsy. To date, many case-control studies have investigated the association between MTHFR C677T polymorphism and epilepsy susceptibility. However, those findings were inconsistent. The objective of this study is to evaluate the precise association between MTHFR C677T polymorphism and epilepsy.

METHODS

An electronic search of PubMed, EMBASE for papers on the MTHFR C677T polymorphism and epilepsy susceptibility was performed. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess the association.

RESULTS

Ten case-control studies containing 1713 cases and 1867 controls regarding MTHFR C677T polymorphism were selected. A significant association between the MTHFR C677T polymorphism and epilepsy susceptibility was revealed in this meta-analysis (for T vs. C: OR=1.19, 95% CI=1.08-1.32; for TT+CT vs. CC: OR=1.20, 95% CI=1.05-1.38; for TT vs. CC: OR=1.48, 95% CI=1.20-1.83; for TT vs. CT+CC: OR=1.35, 95% CI=1.12-1.64). In subgroup analysis by ethnicity, the results also indicated the association between the MTHFR C677T polymorphism and epilepsy susceptibility within the Asian populations (for T vs. C: OR=1.55, 95% CI=1.15-2.07; for TT+CT vs. CC: OR=1.67, 95% CI=1.08-2.59; for TT vs. CC: OR=2.33, 95% CI=1.30-4.20; for TT vs. CT+CC: OR=1.89, 95% CI=1.12-3.18).

CONCLUSION

The results indicated that MTHFR C677T polymorphism was associated with an increased risk of epilepsy. However, further studies in various regions are needed to confirm the findings from this meta-analysis.

Inhibition of cystathionine β-synthase is associated with glucocorticoids over-secretion in psychological stress-induced hyperhomocystinemia rat liver

Hyperhomocysteinemia (HHcy), a pathological condition characterized by an increase in plasma concentration of total homocysteine (Hcy), is recognized as a risk factor for several diseases. The transsulfuration pathway is the main metabolic fate of Hcy utilization, which requires the activity of cystathionine β-synthase (CBS). Our results showed the development of HHcy induced by psychological stress was mainly derived from a reduction of CBS activity in the liver, which was accompanied by a significant decrease in its mRNA level. It suggested that the hepatic CBS enzyme regulated by stress at the level of transcription would have a profound effect on circulating Hcy levels. The expression of Sp3, a negative factor for cbs transcription, obviously increased in hepatocytes nuclei of stressed rats, but Sp1 was not altered. It indicated that Sp3 was the key point of variations in cbs transcription caused by stress. Meanwhile, we detected that augmented plasma Hcy concentrations correlated with glucocordicoids (GCs) over-secretion in response to stress, and CBS mRNA levels were markedly lowered in GCs-treated rat hepatocytes. Further results found that glucocorticoids receptor (GR) expression in hepatocyte nuclei of stress rats and GR nuclear translocation ratio was increased, and the same results were proved by experiments in vitro, i.e., GR nuclear translocation and Sp3 expression was remarkably increased in GCs-treated hepatocytes. Moreover, results from ChIP suggested GCs enhanced the binding of GR to the regulatory region of the Sp3 promoter. These results indicated that GCs inhibit CBS transcription by up-regulating Sp3 in psychological stress-induced HHcy.

Homocysteine induces cerebral endothelial cell death by activating the acid sphingomyelinase ceramide pathway

Homocysteine (Hcy) levels may rise after a stroke, but the mechanism of Hcy-induced cerebral endothelial cell (CEC) dysfunction has not been explored. In this study we examined the role of the acid sphingomyelinase (Asm)-ceramide pathway in the molecular mechanism of Hcy-induced CEC dysfunction. Murine CECs were prepared from fresh mouse brains. CECs were treated with 50-500 μM Hcy and 30-100 μM C2-ceramide for 48 h. Sphingomyelinase assays were performed to determine Asm activity. Quantitative assessments of cell survival and death by the MTT reduction and LDH release were conducted. Treatment of murine CECs with Hcy and ceramide caused cell death in a dose-dependent manner as determined by LDH and MTT assays. 250 μM Hcy and 50 μM C2-ceramide caused 50% cell death. Hcy induced murine CEC death also occurred in a time-dependant manner with substantial cell death noted as early as 24h after Hcy exposure. C2-ceramide-induced murine CEC death occurred earlier than Hcy-induced cell death by about 18h. Hcy treatment increased Asm activity and intracellular ceramide accumulation. This study demonstrated that Hcy and C2-ceramide can cause murine CEC death. Hcy induces CEC death possibly by activating the Asm-ceramide pathway.

Homocysteine, vitamin B12 and folate levels in Iranian patients with Multiple Sclerosis: a case control study

BACKGROUND

Recently, homocysteine (Hcy), folate, and vitamin B12 have been proposed to have several roles on MS pathogenesis.

OBJECTIVE

We performed this study to determine the role of serum levels of Hcy, vitamin B12, and folate in patients with relapsing remitting MS (RRMS) and compared them with healthy controls.

METHODS

We recruited 75 RRMS patients and 75 subjects as controls with the same age and sex. Homocysteine was measured using fluorimetric high-performance liquid chromatography. Plasma folate and vitamin B12 levels were measured through ion-capture method.

RESULTS

Mean plasma levels of vitamin B12, folate, and Hcy in cases were 342.64 ± 210.66 pg/ml, 9.74 ± 4.77 ng/ml, and 22.73 ± 11.63 μM/L, respectively, which showed significant difference in comparison with the controls. In addition, there were significant correlations between mean serum Hcy levels and duration of disease (r=0.2, p=0.05) and treatment with interferon (r=0.21, p=0.01). In cases, Hcy level was higher among those on β interferon (24.56 ± 11.87 vs. 19.71 ± 10.75, p=0.01).

CONCLUSIONS

We concluded that serum levels of vitamin B12 and folate decreased in RRMS patients, but Hcy levels increased significantly. It seems necessary to conduct prospective trials to determine whether the treatment with supplements and correct biomarker levels in the early stage of the disease can change the course of the disease. We recommend regular checking of the serum level of Hcy in patients who use disease-modifying drugs.

Transcriptome Profiling Following Neuronal and Glial Expression of ALS-Linked SOD1 in Drosophila

Amyotrophic lateral sclerosis (ALS) generally is a late-onset neurodegenerative disease. Mutations in the Cu/Zn superoxide dismutase 1 (SOD1) gene account for approximately 20% of familial ALS and 2% of all ALS cases. Although a number of hypotheses have been proposed to explain mutant SOD1 toxicity, the molecular mechanisms of the disease remain unclear. SOD1-linked ALS is thought to function in a non-cell-autonomous manner such that motoneurons are critical for the onset, and glia contribute to progression of the disease. Recently, it has been shown in Drosophila melanogaster that expression of human SOD1 in a subset of neuronal cells causes synaptic transmission defects, modified motor function, and altered sensitivity to compounds that induce oxidative stress. Here we used the Gal4-UAS (Upstream Activation Sequence) system to further characterize flies expressing wild-type Drosophila SOD1 (dSOD1) and the mutant human SOD1^G85R (G85R) allele in motoneurons and glia. Cell-specific expression of both dSOD1 and G85R was found to influence lifespan, affect sensitivity to hydrogen peroxide, and alter lipid peroxidation levels. To better understand the genetic consequences of G85R expression in motoneurons and glia, we conducted microarray analysis of both young flies (5 days old) and old flies (45 days old) expressing G85R selectively in motoneurons or glia and concurrently in motoneurons and glia. Results from this microarray experiment identified candidate genes for further investigation and may help elucidate the individual and combined contributions of motoneurons and glia in ALS.

Lack of association between the MTHFR C677T variant and migraine with aura in an older population: could selective survival play a role?

BACKGROUND

Several studies, but not all, of primarily middle-aged or younger adults have suggested that the common MTHFR C677T variant is a genetic risk factor for migraine with aura (MA). Here, we consider whether this variant is associated with MA risk in an older non-clinical population (AGES-Reykjavik cohort).

METHODS

Participants are a sub-sample ( N  = 1976) of subjects from the Reykjavik Study (RS; mean age 50) and its continuation, AGES-RS (mean age 76). We estimated the relative odds of MA in TT versus CC carriers using multinomial logistic regression. As both MA and the TT genotype may be linked with modestly reduced longevity, we performed a simple simulation to illustrate the effect that selective survival may have had on our observed gene-disease association.

RESULTS

TT versus CC carriers were at marginally reduced odds of MA (ORTT 0.55 (0.3-1.0), P  = 0.07), significantly for women (ORTT 0.45 (0.2-0.9), P  = 0.03). Assuming the 'true' (e.g. mid-life) effect of the TT genotype is ORTT 1.26, from a recent meta-analysis, our simulation suggested that if 25-year mortality had been (hypothetically) 13% higher in MA subjects with the TT versus CC genotype, the measured effect of the TT genotype on MA would have been attenuated to non-significance (e.g. ORTT 1.00). Our observed protective effect was consistent with the most extreme selective mortality scenario, in which essentially all of the previously reported increased mortality in MA subjects was (hypothetically) found in CT or TT carriers.

CONCLUSION

The MTHFR 677TT genotype was associated with marginally reduced risk of MA in our older population. Our simulation illustrated how even modest selective survival might obscure the apparent effect of a genetic or other risk factor in older populations. We speculate that some of the heterogeneity previously observed for this particular genetic variant may be due to age range differences in the studied populations.

Elevated homocysteine by levodopa is detrimental to neurogenesis in parkinsonian model

BACKGROUND

Modulation of neurogenesis that acts as an endogenous repair mechanism would have a significant impact on future therapeutic strategies for Parkinson's disease (PD). Several studies demonstrated dopaminergic modulation of neurogenesis in the subventricular zone (SVZ) of the adult brain. Levodopa, the gold standard therapy for PD, causes an increase in homocysteine levels that induces neuronal death via N-methyl-D-aspartate (NMDA) receptor. The present study investigated whether elevated homocysteine by levodopa treatment in a parkinsonian model would modulate neurogenesis via NMDA receptor signal cascade and compared the effect of levodopa and pramipexol (PPX) on neurogenic activity.

METHODOLOGY/PRINCIPAL FINDINGS

Neurogenesis was assessed in vitro using neural progenitor cells (NPCs) isolated from the SVZ and in vivo with the BrdU-injected animal model of PD using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. Modulation of homocysteine levels was evaluated using co-cultures of NPCs and astrocytes and PD animals. Immunochemical and Western blot analyses were used to measure neurogenesis and determine the cell death signaling. Levodopa treatment increased release of homocysteine on astrocytes culture media as well as in plasma and brain of PD animals. Increased homocysteine by levodopa led to increased apoptosis of NPCs through the NMDA receptor-dependent the extracellular signal-regulated kinase (ERK) signaling pathways. The administration of a NMDA antagonist significantly attenuated apoptotic cell death in levodopa-treated NPCs and markedly increased the number of BrdU-positive cells in the SVZ of levodopa-treated PD animals. Comparative analysis revealed that PPX treatment significantly increased the number of NPCs and BrdU-positive cells in the SVZ of PD animals compared to levodopa treatment. Our present study demonstrated that increased homocysteine by levodopa has a detrimental effect on neurogenesis through NMDA receptor-mediated ERK signaling pathway.

CONCLUSIONS/SIGNIFICANCE

Modulation of levodopa-induced elevated homocysteine by NMDA antagonist or dopamine agonist has a clinical relevance for PD treatment in terms of adult neurogenesis.

Comparison of endothelial progenitor cells in Parkinson's disease patients treated with levodopa and levodopa/COMT inhibitor

Background

Levodopa treatment in Parkinson's disease (PD) increases in serum homocysteine levels due to its metabolism via catechol O-methyltransferase. Endothelial progenitor cells (EPCs) have the capacity to differentiate into mature endothelial cells and are markers for endothelial functions and cardiovascular risks. Along with traditional vascular risk factors, hyperhomocysteinemia is known to decrease the level of EPCs. In the present study, we hypothesized that that levodopa-induced hyperhomocysteinemia leads to a change in EPC levels.

Methodology/Principal Findings

We prospectively enrolled PD patients who had been prescribed either levodopa/carbidopa (PD-L group, n = 28) or levodopa/carbidopa/COMT inhibitor (PD-LC group, n = 25) for more than 1 year. The number of circulating EPCs was measured by flow cytometry using dual staining of anti-CD34 and anti-KDR antibodies. The EPCs were divided into tertiles based on their distributions and a logistic regression analysis was used to estimate independent predictors of the highest tertile of EPCs. The number of endothelial progenitor cells was significantly decreased in PD-L patients (118±99/mL) compared with either PD-LC patients (269±258/mL, p = 0.007) or controls (206±204/mL, p = 0.012). The level of homocysteine was significantly increased in PD-L patients (14.9±5.3 µmol/L) compared with either PD-LC patients (11.9±3.0 µmol/L, p = 0.028) or controls (11.1±2.5 µmol/L, p = 0.012). The level of homocysteine was negatively correlated with endothelial progenitor cell levels (r = −0.252, p = 0.028) and was an independent predictor of the highest tertile of endothelial progenitor cell levels (OR; 0.749 [95% CI: 0.584–0.961]).

Conclusions/Significance

These data indicate that a higher consumption of EPC for restoration of endothelial damage may be associated with chronic levodopa treatment in PD patients.

Increased expression of tumor necrosis factor-alpha in the rat hippocampus after acute homocysteine administration

Background and Purpose:

This paper evaluated the effect of acute homocysteine administration on inflammatory cytokine tumor necrosis factor-alpha (TNF-α) expression and neuronal apoptosis in the rat hippocampus and investigated the effects of vitamin C treatment on homocysteine-induced inflammation and neuronal death.

Methods:

Subjects were three-week-old, male Sprague-Dawley rats. Rats for the control group, we injected saline solution into the rats’ abdominal cavities for one week. Rats in the second group received 1 injection of homocysteine (11 mmol/kg) into their abdominal cavities after 1 week of saline solution administration. For the third group, we injected the rats with vitamin C (100 mg/kg) for a week, followed by 1 injection of homocysteine. The hippocampi were stained with an anti-TNF-α antibody, and apoptosis was evaluated using the TUNEL staining method.

Results:

The homocysteine-injected rats had strong TNF-α expression in every hippocampal region. Vitamin C significantly reduced TNF-α expression in the hippocampus’s CA1 region. Acute homocysteine administration did not cause apoptosis in the hippocampus.

Conclusions:

The pro-inflammatory cytokine TNF-α may mediate elevated homocysteine levels’ contributions to inflammatory reactions, and vitamin C has some protective effect on inflammatory reactions in the CA1 hippocampal region.