Gut microbiota and risk of polycystic ovary syndrome: Insights from Mendelian randomization

Gut Microbiota Modulation by Inulin Improves Metabolism and Ovarian Function in Polycystic Ovary Syndrome

The management of metabolic disorder associated with polycystic ovary syndrome (PCOS) has been suggested as an effective approach to improve PCOS which is highly involved with gut microbiota, while the underlying mechanism is unclear. Here, we investigated the role of inulin, a gut microbiota regulator, in the alleviation of PCOS. Our findings showed that inulin treatment significantly improved hyperandrogenism and glucolipid metabolism in both PCOS cohort and mice. Consistent with the cohort, inulin increased the abundance of microbial co-abundance group (CAG) 12 in PCOS mice, including Bifidobacterium species and other short-chain fatty acids (SCFAs)-producers. We further verified the enhancement of SCFAs biosynthesis capacity and fecal SCFAs content by inulin. Moreover, inulin decreased lipopolysaccharide-binding protein (LBP) and ameliorated ovarian inflammation in PCOS mice, whereas intraperitoneal lipopolysaccharide (LPS) administration reversed the protective effects of inulin. Furthermore, fecal microbiota transplantation (FMT) from inulin-treated patients with PCOS enhanced insulin sensitivity, improved lipid accumulation and thermogenesis, reduced hyperandrogenism and ovarian inflammatory response in antibiotic-treated mice. Collectively, these findings revealed that gut microbiota mediates the beneficial effects of inulin on metabolic disorder and ovarian dysfunction in PCOS. Therefore, modulating gut microbiota represents a promising therapeutic strategy for PCOS.

Polycystic ovary syndrome and epithelial-mesenchymal transition: Mendelian randomization and single-cell analysis insights

BACKGROUND

The process of epithelial-mesenchymal transition (EMT) may promote fibrosis in ovarian tissue related to polycystic ovary syndrome (PCOS), thus affecting ovarian function and hormonal balance.

OBJECTIVE

This study aimed to explore key genes associated with EMT in PCOS and their potential molecular regulatory mechanisms, exclusively from the perspective of transcriptomics and single-cell RNA sequencing (scRNA-seq), combined with Mendelian Randomization (MR) analysis.

METHODS

The dataset for PCOS and EMT-related genes (EMT-RGs) were sourced from public databases. The key genes in this study were identified via differential expression analysis, MR, and evaluation of expression levels. Enrichment analysis and a series of functional analyses were conducted on these genes to further elucidate their potential mechanisms. Subsequently, using scRNA-seq data and validation of the expression of key genes, key cell group in PCOS were identified, followed by pseudo-time and cell communication analyses to provide deeper insights.

RESULTS

Three key genes, NUCB2 [odds ratio (OR) = 0.8634, 95% confidence interval (CI): 0.8145-0.9152, P < 0.0001], PGF (OR = 0.8393, 95% CI: 0.7185-0.9805, P < 0.05), and CRIM1 (OR = 0.7539, 95% CI: 0.6556-0.670, P < 0.0001), were identified as having a unidirectional causal association with PCOS and were associated with a reduced risk of PCOS. In public datasets, NUCB2 exhibited significantly increased expression in PCOS samples, while PGF and CRIM1 showed the opposite trends. These three genes were enriched in pathways related to cellular functions, metabolic processes, and the operation of the nervous system, and they were co-expressed in smooth muscle. Additionally, five cell clusters were annotated, among which fibroblasts were identified as key cells due to their highest expression of all three key genes. Further analysis revealed a bifurcation event occurring during the mid-development stage of fibroblasts, with PCOS samples displaying a higher abundance of fibroblasts. In PCOS samples, fibroblasts exhibited more extensive communication with secretory epithelial cells, indicating a more complex intercellular interaction within this condition.

CONCLUSION

This study identified three EMT-RGs: NUCB2, PGF, and CRIM1, which were associated with a reduced risk of PCOS, with fibroblast identified as a key cell group in the disease's pathology. This provides new insights for PCOS research.

Impact of Dietary Patterns and Serum Amino Acid Profile on Metabolic Syndrome Development in Mexican Women with Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is the main endocrine disorder in women of reproductive age worldwide. This condition is often associated with various metabolic alterations that contribute to the development of metabolic syndrome (MetS). Recent research suggests that branched-chain amino acid (BCAA) dysregulation is observed in PCOS. This study aims to investigate the relationship between dietary patterns, body composition, metabolic analytes, and serum amino acid levels in Mexican women with PCOS. Utilizing a cross-sectional design, we found that both study groups, PCOS (n = 24) and PCOS + MetS (n = 21), exhibited increased relative fat mass and dietary habits characterized by high simple sugar intake and low protein consumption, correlating with levels of relative fat mass and leptin. Notably, serum concentrations of BCAAs and glutamic acid were significantly elevated in the PCOS + MetS group. Our findings suggest that a metabolic approach may enhance the prediction and management of MetS in women with PCOS, highlighting the importance of dietary interventions in this population.

Impact of Gut Microbiota and SCFAs in the Pathogenesis of PCOS and the Effect of Metformin Therapy

Polycystic ovary syndrome (PCOS) is a complex disorder that impacts both the endocrine and metabolic systems, often resulting in infertility, obesity, insulin resistance, and cardiovascular complications. The aim of this study is to investigate the role of intestinal flora and its metabolites, particularly short-chain fatty acids (SCFAs), in the development of PCOS, and to assess the effects of metformin therapy on these components. SCFA levels in fecal and blood samples from women with PCOS (n=69) and healthy controls (n=18) were analyzed using Gas Chromatography-Mass Spectrometry (GC/MS) for precise measurement. Fecal microbiota were quantitatively detected by real-time polymerase chain reaction (PCR). To assess the efficacy of six months of metformin treatment, changes in the microbiota and SCFAs in the PCOS group (n=69) were also evaluated. The results revealed that women with PCOS exhibited a significant reduction in beneficial bacteria (namely, the C. leptum group and Prevotella spp.) alongside a notable overgrowth of opportunistic microorganisms (C. perfringens, C. difficile, Staphylococcus spp., and Streptococcus spp.). An overproduction of acetic acid (AA, FC=0.47, p<0.05) and valeric acid (VA, FC=0.54, p<0.05) suggests a link between elevated SCFAs and the development of obesity and PCOS. Interestingly, AA in the bloodstream might offer a protective effect against PCOS by ameliorating key symptoms such as high body mass index (r=-0.33, p=0.02), insulin resistance (r=-0.39, p=0.02), and chronic inflammation. Although serum SCFA levels showed non-significant changes following metformin treatment (p>0.05), the normalization of AA in the gut underscores that metformin exerts a more pronounced effect locally within the gastrointestinal tract. Furthermore, the study identified the most effective model for predicting the success of metformin therapy, based on serum concentrations of butyric acid (BA) and VA, achieving a 91% accuracy rate, 100% sensitivity, and 80% specificity. These promising findings highlight the potential for developing targeted interventions and personalized treatments, ultimately improving clinical outcomes for women with PCOS.

The gut microbiota: emerging biomarkers and potential treatments for infertility-related diseases

Infertility is a disease of impaired fertility. With socioeconomic development, changes in human lifestyles, and increased environmental pollution, the problem of low human fertility has become increasingly prominent. The incidence of global infertility is increasing every year. Many factors lead to infertility, and common female factors include tubal factors, ovulation disorders, endometriosis, and immune factors. The gut microbiota is involved in many physiological processes, such as nutrient absorption, intestinal mucosal growth, glycolipid metabolism, and immune system regulation. An altered gut flora is associated with female infertility disorders such as polycystic ovary syndrome (PCOS), endometriosis (EMs), and premature ovarian failure (POF). Dysbiosis of the gut microbiota directly or indirectly contributes to the development of female infertility disorders, which also affect the homeostasis of the gut microbiota. Identifying the etiology and pathogenesis of infertility in patients is the focus of reproductive medicine physicians. We studied the developmental mechanism between the gut microbiota and PCOS, EMs, and POF from a new perspective, providing new ideas for diagnosing and treating female infertility diseases and specific reference values for eugenics.

Mineral Metabolism and Polycystic Ovary Syndrome and Metabolic Risk Factors: A Mendelian Randomization Study

Observational investigations recommend that mineral supplements were associated with a higher risk of polycystic ovary syndrome (PCOS) and its risk factors (insulin resistance, hyperandrogenism, and obesity), but the relationship with risk of PCOS, hyperandrogenism, obesity, and insulin resistance was unclear. This study was to investigate the potential causal impact of genetically predicted levels of magnesium (Mg), calcium (Ca), selenium (Se), zinc (Zn), iron (Fe), and omega-3 (ω-3) on polycystic ovary syndrome (PCOS) and its associated risk factors. A two-sample Mendelian randomization (MR) analysis was conducted. The genetic variations obtained from GWAS of individuals with European ancestry were found to be associated with the genetically predicted levels of Ca, Mg, Zn, Se, Fe, or ω-3. The data obtained from the FinnGen Consortium and MAGIC were utilized for the outcome of GWAS. The study found that there was a correlation between genetically predicted higher levels of Se and a reduced risk of insulin resistance, with a decrease of 2.2% according to random-effect IVW (OR 0.978, 95% CI 0.960-0.996, p = 0.015). The association between genetically determined mineral levels and PCOS was found to be limited, with an odds ratio (OR) ranging from 0.875 (95% CI: 0.637-1.202, p value = 0.411) for Ca. Limited scientific proof was found for the efficacy of other genetically determined mineral levels on hyperandrogenism, obesity, and insulin resistance. These findings suggested a causal relationship between genetically predicted higher levels of Se and a reduced risk of insulin resistance. Nonetheless, there is limited evidence supporting a causal association between various genetically determined mineral levels and the risk factors associated with PCOS.

Reducing the Risk of Pre-Eclampsia in Women with Polycystic Ovary Syndrome Using a Combination of Pregnancy Screening, Lifestyle, and Medical Management Strategies

Polycystic ovary syndrome (PCOS) is a multisystem disorder that presents with a variety of phenotypes involving metabolic, endocrine, reproductive, and psychological symptoms and signs. Women with PCOS are at increased risk of pregnancy complications including implantation failure, miscarriage, gestational diabetes, fetal growth restriction, preterm labor, and pre-eclampsia (PE). This may be attributed to the presence of specific susceptibility features associated with PCOS before and during pregnancy, such as chronic systemic inflammation, insulin resistance (IR), and hyperandrogenism, all of which have been associated with an increased risk of pregnancy complications. Many of the features of PCOS are reversible following lifestyle interventions such as diet and exercise, and pregnant women following a healthy lifestyle have been found to have a lower risk of complications, including PE. This narrative synthesis summarizes the evidence investigating the risk of PE and the role of nutritional factors in women with PCOS. The findings suggest that the beneficial aspects of lifestyle management of PCOS, as recommended in the evidence-based international guidelines, extend to improved pregnancy outcomes. Identifying high-risk women with PCOS will allow targeted interventions, early-pregnancy screening, and increased surveillance for PE. Women with PCOS should be included in risk assessment algorithms for PE.