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

Effects of MTHFR C677T polymorphism on homocysteine and vitamin D in women with polycystic ovary syndrome

OBJECTIVES

To evaluate the correlation between serum vitamin D, homocysteine and the methylene tetrahydrofolate reductase (MTHFR) C677T polymorphism in women with polycystic ovary syndrome (PCOS). Study design We retrospectively compared the serum homocysteine and vitamin D levels and the MTHFR C677T polymorphism in 104 PCOS patients and 104 controls. Parameters related to PCOS were statistically analysed.

RESULTS

Comparative analysis revealed that women with PCOS had significantly greater serum homocysteine levels (P = 0.002) and lower vitamin D concentrations (P = 0.040) than controls. The distribution frequency of the MTHFR C677T genotype did not significantly differ between the PCOS group and the control group. (P > 0.05). In the PCOS group, the serum level of homocysteine in the TT group was significantly greater than that in the CT (P = 0.003) and CC (P = 0.002) groups and the level of vitamin D in the TT group was significantly less than that in the CC (P < 0.001) and CT (P = 0.172) groups. The results were similar when the PCOS and control groups were divided according to whether they had insulin resistance. Vitamin D levels were significantly negatively correlated with homocysteine levels in all PCOS patients (r = -0.281, P = 0.004), similarly, vitamin D levels were negatively correlated with homocysteine levels in the CC, CT and TT of PCOS patients. According to multivariate analysis, vitamin D concentration was an independent risk factor for hyperhomocysteinaemia (adjusted OR 1.372, 95 % CI: 1.100-1.712).

CONCLUSIONS

No significant differences were found in the distributions of MTHFR C677T genotypes between the PCOS and control groups but these genotypes affected the patients' serum homocysteine and vitamin D concentrations. Women with the TT genotype have significantly lower vitamin D levels and higher homocysteine levels than women with the CC and CT genotypes. However, because of the limitations of this investigation, large-sample, high-quality prospective studies are needed to further verify these results in the future.

Homocysteine and Glaucoma

Elevated levels of homocysteine (Hcy), a non-proteinogenic amino acid, may lead to a host of manifestations across the biological systems, particularly the nervous system. Defects in Hcy metabolism have been associated with many neurodegenerative diseases including glaucoma, i.e., the leading cause of blindness. However, the pathophysiology of elevated Hcy and its eligibility as a risk factor for glaucoma remain unclear. We aimed to provide a comprehensive review of the relationship between elevated Hcy levels and glaucoma. Through a systemic search of the PubMed and Google Scholar databases, we found that elevated Hcy might play an important role in the pathogenesis of glaucoma. Further research will be necessary to help clarify the specific contribution of elevated Hcy in the pathogenesis of glaucoma. A discovery and conceptual understanding of Hcy-associated glaucoma could be the keys to providing better therapeutic treatment, if not prophylactic treatment, for this disease.

Increased homocysteine regulated by androgen activates autophagy by suppressing the mammalian target of rapamycin pathway in the granulosa cells of polycystic ovary syndrome mice

The purpose of this study was to explore the potential molecular mechanisms of excess homocysteine in relation to autophagic activity in the ovarian tissue of polycystic ovarian syndrome (PCOS) with hyperandrogenism.A PCOS model was constructed using ICR mice. ELISA was used to detect the Hcy levels in the serum and ovarian tissues of PCOS model. The expression level of key enzymes (Methionine synthase and Betaine-homocysteine methyltransferase, MTR and BHMT) in homocysteine metabolism and autophagy-related proteins were detected in ovarian tissues and mouse granulosa cells (mGCs) that were treated with homocysteine, androgen, autophagy inhibitors or BHMT-expressing plasmid by western blot and immunohistochemistry. Electron microscope experiments were used to evaluate autophagosomes in Hcy-treated mGCs. The prenatally androgenized (PNA) PCOS mouse model showed hyperhomocysteinemia and hyperandrogenism. Homocysteine levels displayed a significant increase, while its metabolic enzymes levels were significantly decreased in ovarian tissues of PCOS mice and dihydrotestosterone (DHT)-stimulated mGCs. The LC3II and Beclin1 expression levels were increased and the P62 and p-mTOR levels were decreased in vivo in ovarian tissue from the PCOS mice. The in vitro data were similarly with the in vivo by stimulation of mGCs with DHT or homocysteine. These effects could be diminished by the autophagy inhibitor (MHY1485), androgen receptor antagonists (ARN509) or BHMT-expressing plasmid. Androgen increases homocysteine concentration by downregulating the key enzymes in homocysteine metabolism. And then Hcy promotes GCs autophagy via the mTOR signal pathway.

Correlation of serum homocysteine levels and hyperinsulinaemia with body mass index in polycystic ovarian syndrome

Background:

Polycystic ovary syndrome (PCOS) is one of the most common endocrinopathies affecting women in reproductive age group. The interrelationship of serum homocysteine, homoeostatic assessment of insulin resistance (HOMA-IR) and body mass index amongst overweight, obese and non-obese PCOS patients is not fully established.

Aims:

We aimed to study the correlation of serum homocysteine levels and hyperinsulinaemia with body mass index (BMI) in PCOS patients.

Study Setting and Design:

This was a case–control study in which 35 women with PCOS and 35 non-PCOS women acting as controls were enrolled.

Materials and Methods:

Cases were identified by Rotterdam's criteria. (IR) indices, HOMA determination and serum homocysteine levels were determined and their correlation with BMI was studied.

Statistical Analysis Used:

Student's t-test and analysis of variance test were used for statistical analysis. The Pearson correlation coefficient was then used to estimate the correlation.

Results:

On overall evaluation, a significant positive correlation of fasting insulin, HOMA-IR and serum homocysteine) was observed (P < 0.05), however, on evaluating the correlation of these markers independently in cases and controls, only fasting insulin and HOMA-IR showed a significant correlation. In a multivariate model where PCOS was considered a dependent variable with age, fasting glucose, HOMA-IR, serum homocysteine and body mass index as the independent variables, only serum homocysteine levels were found to be significantly associated with the dependent variable (odds ratio = 1.172; 95% confidence interval = 1.032–1.330).

Conclusion:

PCOS women had significantly higher mean fasting glucose, fasting insulin, HOMA-IR and homocysteine levels as compared to non-PCOS controls. Mean HOMA-IR, homocysteine and fasting insulin levels showed a significant incremental trend with increasing BMI category in overall evaluation as well as in cases and controls independently.

Discovery of novel serum metabolic biomarkers in patients with polycystic ovarian syndrome and premature ovarian failure

Several widely recognized metabolites play a role in regulating the pathophysiological processes of various disorders. Nonetheless, the lack of effective biomarkers for the early diagnosis of polycystic ovarian syndrome (PCOS) and premature ovarian failure (POF) has led to the discovery of serum-based metabolic biomarkers for these disorders. We aimed to identify various differentially expressed metabolites (DEMs) through serum-based metabolic profiling in patients with PCOS and POF and in healthy individuals by using liquid chromatography–mass spectrometry analysis. Furthermore, heatmap clustering, correlation, and Z-score analyses were performed to identify the top DEMs. Kyoto Encyclopedia of Genes and Genomes enriched pathways of DEMs were determined using metabolite-based databases. Moreover, the clinical significance of these DEMs was evaluated on the basis of area under the receiver operating characteristic curve. Significantly dysregulated expressions of several metabolites were observed in the intergroup comparisons of the PCOS, POF, and healthy control groups. Furthermore, 6 DEMs were most frequently observed among the three groups. The expressions of these DEMs were not only directly correlated but also exhibited potential significance in patients with PCOS and POF. Novel metabolites with up/downregulated expressions can be discovered in patients with PCOS and POF using serum-based metabolomics; these metabolites show good diagnostic performance and can act as effective biomarkers for the early detection of PCOS and POF. Furthermore, these metabolites might be involved in the pathophysiological mechanisms of PCOS and POF via interplay with corresponding genes.

Proteomic profile of the effects of low-dose bisphenol A on zebrafish ovaries

Human exposure to bisphenol-A (BPA) is largely unavoidable because BPA is an environmental contaminant found in soil, water, food and indoor dust. The safety of authorized BPA amounts in consumer products is under question because new studies have reported adverse effects of BPA at doses far below that previously established by the NOAEL (50 μg/kg per day). To protect public health, the consequences of low-dose BPA exposure in different organs and organismal functions must be further studied to generate relevant data. This study attempted to investigate the effects and potential molecular mechanisms of short-term exposure to 1 μg/L BPA on zebrafish ovarian follicular development. We observed only minor changes at the histopathological level with a small (3 %) increase in follicular atresia. However, a shotgun proteomics approach indicated deep alterations in BPA-exposed ovarian cells, including induction of the oxidative stress response, metabolic shifts and degradome perturbations, which could drive oocytes towards premature maturation. Based on these results, it could be suggested that inadvertent exposure to small concentrations of BPA on a continuous basis causes alteration in biological processes that are essential for healthy reproduction.

Fructose levels are elevated in women with polycystic ovary syndrome with obesity and hyperinsulinemia

STUDY QUESTION

Are fructose levels altered in women with polycystic ovary syndrome (PCOS)?

SUMMARY ANSWER

Elevated serum fructose levels are associated with PCOS in Chinese Han women with overweight/obesity and hyperinsulinemia, and fructose levels are higher in follicular fluids from PCOS patients than from control subjects.

WHAT IS KNOWN ALREADY

Both fructose levels and PCOS are closely linked to obesity and insulin resistance. However, the relationship between fructose and PCOS remains largely unknown.

STUDY DESIGN, SIZE, DURATION

A total of 157 Chinese Han women (67 controls and 90 PCOS patients) were recruited at Shengjing Hospital of China Medical University. To systematically study the relationship between serum fructose levels and PCOS, the study population of control subjects and PCOS patients was divided into overweight/obese and lean subgroups, and hyper-fasting serum insulin (FSI) and normal-FSI subgroups, respectively.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Fructose levels were measured in serum samples collected from 80 patients with PCOS (32 lean, 48 overweight/obese) and 59 control subjects (27 lean, 32 overweight/obese) and in follicular fluid samples collected from mature follicles (17-22 mm) and matched immature follicles (8-13 mm) from 10 patients with PCOS and 8 control subjects.

MAIN RESULTS AND THE ROLE OF CHANCE

Serum fructose levels were increased in overweight/obese and hyper-FSI PCOS patients compared with the control subjects. Fructose had an area under the curve (AUC) of 79.7% at a cutoff value of 10.13 pmol/μl, with a sensitivity of 91.7% and a specificity of 59.3% for the prediction of PCOS in overweight/obese patients. In the hyper-FSI group, fructose had an AUC of 72% at a cutoff value of 10.49 pmol/μl, with a sensitivity of 71.1% and a specificity of 64.4% for the prediction of PCOS. There were no differences between fructose, total testosterone, free testosterone or dehydroepiandrosterone sulfate levels with respect to the reliability of predicting PCOS in the overweight/obese or hyper-FSI groups using the method outlined by Hanley and McNeil. Notably, the combination of fructose and total testosterone levels resulted in the highest AUC of 86.0% and high sensitivity (85.4%) and specificity (83.1%) for the prediction of PCOS in overweight/obese patients. The positive predictive value (PPV) and negative predictive value (NPV) were 80.4 and 87.5%, respectively. Similarly, the combination of fructose and total testosterone levels also resulted in a high AUC of 80.2% and moderate sensitivity (73.3%) and high specificity (84.7%) for the prediction of PCOS in hyper-FSI patients. The PPV and NPV were 78.6 and 80.6%, respectively. Furthermore, fructose levels were significantly higher in follicular fluids from PCOS patients than from control subjects, regardless of whether the follicles were mature or immature.

LIMITATIONS, REASONS FOR CAUTION

It remains unclear whether fructose levels contribute directly to follicular development and the pathogenesis of PCOS or are merely a biomarker of these processes.

WIDER IMPLICATIONS OF THE FINDINGS

The results of the present study, together with our previous study, show that monosaccharide status may be a novel marker for PCOS, highlighting the importance of further investigation into the role of monosaccharides, especially fructose, in the pathogenesis of PCOS.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Natural Science Foundation of China (No. 81671423 and No. 81402130), the National Key Research and Development Program of China (No. 2018YFC1003100), Liaoning Provincial Key Research and Development Program (No. 2018225090), the Fok Ying Tung Education Foundation (No. 151039), Distinguished Talent Program of Shengjing Hospital (No. ME76) and Distinguished Teacher Program of China Medical University (No. QGZ2018079). No competing interests were declared.

Association of three missense mutations in the homocysteine-related MTHFR and MTRR gene with risk of polycystic ovary syndrome in Southern Chinese women

BACKGROUND

The etiology between homocysteine and polycystic ovary syndrome (PCOS) is unclear. In humans, the level of homocysteine is mainly affected by two enzymes: methylene tetrahydrofolate reductase (MTHFR) and methionine synthase reductase (MTRR). While the activity of these two enzymes is mainly affected by three missense mutations, namely C677T (MTHFR), A1298C (MTHFR), and A66G (MTRR). This study aims to examine the association between the three missense mutations and PCOS and investigate whether the three missense mutations exerted their effect on PCOS by affecting the homocysteine level.

METHODS

A case-control study was designed, comprising 150 people with PCOS and 300 controls. Logistic regression analysis was used to assess the association between the three missense mutations and PCOS. Linear regression analysis was used to assess the association between the three missense mutations and the homocysteine level. Mediation analysis was used to investigate whether the three missense mutations exerted their effect on PCOS by affecting the homocysteine level.

RESULTS

Following adjustments and multiple rounds of testing, MTHFR A1298C was found to be significantly associated with PCOS in a dose-dependent manner (compared to AA, OR = 2.142 for AC & OR = 3.755 for CC; P < 0.001). MTRR A66G was nominally associated with PCOS. Mutations in MTHFR A1298C and MTRR A66G were significantly associated with the homocysteine level. Mediation analysis suggested the effect of MTHFR A1298C on PCOS was mediated by homocysteine.

CONCLUSIONS

MTHFR A1298C and MTRR A66G were associated with PCOS, and MTHFR A1298C might affect the risk of PCOS by influencing the homocysteine level.

Hyperhomocysteinemia: Clinical Insights

Homocysteine (Hcy) is a sulfhydryl-containing amino acid, and intermediate metabolite formed in metabolising methionine (Met) to cysteine (Cys); defective Met metabolism can increase Hcy. The effect of hyperhomocysteinemia (HHcy) on human health, is well described and associated with multiple clinical conditions. HHcy is considered to be an independent risk factor for common cardiovascular and central nervous disorders, where its role in folate metabolism and choline catabolism is fundamental in many metabolic pathways. HHcy induces inflammatory responses via increasing the pro-inflammatory cytokines and downregulation of anti-inflammatory cytokines which lead to Hcy-induced cell apoptosis. Conflicting evidence indicates that the development of the homocysteine-associated cerebrovascular disease may be prevented by the maintenance of normal Hcy levels. In this review, we discuss common conditions associated with HHcy and biochemical diagnostic workup that may help in reaching diagnosis at early stages. Furthermore, future systematic studies need to prove the exact pathophysiological mechanism of HHcy at the cellular level and the effect of Hcy lowering agents on disease courses.

Elevated Serum Mannose Levels as a Marker of Polycystic Ovary Syndrome

Background: Recent reports have highlighted the role of monosaccharide biosynthesis in the pathogenesis of polycystic ovary syndrome (PCOS), suggesting that these processes may serve as a biomarker in PCOS. Mannose is the main monosaccharide for protein glycosylation in mammals; however, the correlation between mannose and PCOS remains largely unknown. Materials and Methods: A total of 132 Chinese Han women were recruited at Shengjing Hospital of China Medical University. Mannose levels were measured in serum samples collected from 71 patients with PCOS (29 lean, 42 obese) and 61 control subjects (28 lean, 33 obese). Receiver operating characteristics (ROC) curves were prepared to compare the diagnostic performance of mannose and hormonal parameters, individually or in combination. Multivariate logistic regression analysis was used to assess whether serum mannose levels were associated with PCOS after adjusting for other co-variables. Results: We showed that serum mannose levels were significantly increased in PCOS patients compared with control subjects regardless of obese status, and hyperandrogenic PCOS patients had higher serum mannose levels than normo-androgenic PCOS and control subjects. In addition, serum mannose levels were significantly correlated with serum androgen levels. Mannose had an area under the curve (AUC) of 73% at a cutoff value of 225.79 ng/mL with a sensitivity of 66.2% and specificity of 73.8% for predicting PCOS. There were no differences between mannose, total testosterone, free testosterone, or dehydroepiandrosterone sulfate in the reliability of predicting PCOS using the method outlined by Hanley and McNeil. Combining mannose and total testosterone resulted in a higher AUC of 83.3%, and had moderate sensitivity (78.9%) and specificity (77%) for predicting PCOS. The positive and negative predictive values were 80% and 75.8%, respectively. Multivariate logistic regression revealed that higher serum mannose levels were strongly associated with an increased risk of PCOS (P = 0.016; odds ratio, 5.623; 95% confidence interval, 1.371-23.070). Conclusion: Taken together, substantially elevated serum mannose levels are significantly associated with PCOS, highlighting the importance of further research into the role of mannose in the pathogenesis of PCOS.