Gut microbiota dysbiosis in polycystic ovary syndrome: association with obesity - a preliminary report

Tempol ameliorates polycystic ovary syndrome through attenuating intestinal oxidative stress and modulating of gut microbiota composition-serum metabolites interaction

Polycystic ovary syndrome (PCOS) is a complex endocrine and metabolic disorder, which is often accompanied by oxidative stress. Tempol, a superoxide dismutase mimetic, protects against several diseases caused by oxidative stress. However, the effect of tempol on PCOS has not been investigated. The present study demonstrated the alleviation of ovarian dysfunction and glucose tolerance in dehydroepiandrosterone (DHEA)-induced PCOS rats treated with tempol. Tempol significantly reduced the intestinal oxidative stress in PCOS rats without affecting the ovarian redox rate. The 16S rDNA sequencing of the intestinal microbiome and non-targeted metabolomics analysis indicated significant differences in gut microbiota composition and serum metabolite profiles between the control and PCOS rats, and most of these differences were reduced after tempol intervention. Tempol alters the gut microbiome by increasing the abundance of genus Ruminococcus_1 and by decreasing the abundance of Ruminococcus_2, Staphylococcus, Ideonella, and Corynebnacterium genera. Tempol also attenuates the reduction of serum bile acid and stachyose levels in PCOS rats, and the serum stachyose level was significantly correlated with the abundance of 15 genera, particularly Ruminococcus_1 and Ruminococcus_2. Moreover, stachyose administration improved ovarian dysfunction in PCOS rats. Thus, our data indicate that tempol ameliorates PCOS phenotype by reducing intestinal oxidative stress, restoring gut dysbiosis, and modulating the interaction between gut microbiota and host metabolite. Therefore, tempol intervention is a potential therapeutic approach for PCOS.

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Tempol improved ovarian dysfunction and glucose tolerance in polycystic ovary syndrome rats.

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Tempol ameliorates intestinal oxidative stress and gut microbiota dysbiosis.

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The protective effect of tempol is associated alternations in serum bile acid and stachyose levels.

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Stachyose administration improved ovarian dysfunction in polycystic ovary syndrome rats.

Intersection of Polycystic Ovary Syndrome and the Gut Microbiome

The etiology of polycystic ovary syndrome (PCOS) remains unclear, although studies indicate that both genetic and environmental factors contribute to the syndrome. In 2012, Tremellen and Pearce proposed the idea that dysbiosis of the intestinal (gut) microbiome is a causative factor of metabolic and reproductive manifestations of PCOS. In the past 5 years, studies in both humans and rodent models have demonstrated that changes in the taxonomic composition of gut bacteria are associated with PCOS. Studies have also clearly shown that these changes in gut microbiota are associated with PCOS as opposed to obesity, since these changes are observed in women with PCOS that are both of a normal weight or obese, as well as in adolescent girls with PCOS and obesity compared with body mass index- and age-matched females without the disorder. Additionally, studies in both women with PCOS and rodent models of PCOS demonstrated that hyperandrogenism is associated with gut microbial dysbiosis, indicating that androgens may modulate the gut microbial community in females. One study reported that the fecal microbiome transplantation of stool from women with PCOS or exposure to certain bacteria resulted in a PCOS-like phenotype in mice, while other studies showed that exposure to a healthy gut microbiome, pre/probiotics, or specific gut metabolites resulted in protection from developing PCOS-like traits in mice. Altogether, these results suggest that dysbiosis of the gut microbiome may be sufficient to develop PCOS-like symptoms and that modulation of the gut microbiome may be a potential therapeutic target for PCOS.

Gut Microbiota in Patients with Polycystic Ovary Syndrome: a Systematic Review

Polycystic ovary Syndrome (PCOS) is one of the most popular diseases that cause menstrual dysfunction and infertility in women. Recently, the relationships between the gastrointestinal microbiome and metabolic disorders such as obesity, type 2 diabetes and PCOS have been discovered. However, the association between the gut microbiome and PCOS symptoms has not been well established. We systematically reviewed existing studies comparing gut microbial composition in PCOS and healthy volunteers to explore evidence for this association. A systematic search was carried out in PubMed, Embase, Cochrane Library, and Web of Science from inception to May 26, 2020, for all original cross-sectional, cohort, or case-control studies comparing the fecal microbiomes of patients with PCOS with microbiomes of healthy volunteers (controls). The primary outcomes were differences in specific gut microbes between patients with PCOS and controls. The search identified 256 citations; 10 studies were included. The total population study of these articles consists of 611 participants (including PCOS group and healthy controls group). Among the included 10 studies, nine studies compared α-diversity, and six studies demonstrated that α-diversity has a significant reduction in PCOS patients. Seven of them reported that there was a significant difference of β-diversity composition between healthy controls groups and PCOS patients. The most common bacterial alterations in PCOS patients included Bacteroidaceae, Coprococcus, Bacteroides, Prevotella, Lactobacillus, Parabacteroides, Escherichia/Shigella, and Faecalibacterium prausnitzii. No consensus has emerged from existing human studies of PCOS and gut microbiome concerning which bacterial taxa are most relevant to it. In this systematic review, we identified specific bacteria associated with microbiomes of patients with PCOS vs controls. Higher level of evidence is needed to determine whether these microbes are a product or cause of PCOS.

Coronavirus Disease 2019 (SARS-CoV-2) and polycystic ovarian disease: Is there a higher risk for these women?

The new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been associated with acute respiratory distress syndrome and infected patients have a relatively high risk of death. Emerging risk factors for poor outcome in this disease include age, male gender, cardiovascular co-morbidities including hypertension, prior cardiovascular disease, diabetes and more recently obesity. To date there are no data relating to SARS-CoV-2 in PCOS women. The present Clinical Opinion represents a summary of the epidemiological evidence and possible pathophysiological mechanisms regarding PCOS and COVID-19. PCOS women could be more susceptible to infections compared to non-PCOS women. Insulin resistance and the associated hyperinsulinaemia are drivers for enhanced steroidogenesis in women with PCOS. Weight-gain and obesity, through their worsening effects on insulin resistance, thereby drive enhanced steroidogenesis and hyperandrogenism. All these features represent key points to provide an explanation for the possible association between PCOS and SARS-CoV-2. Indeed, androgens may drive clinical results in COVID-19, through the expression of TMPRSS2, a cellular co-receptor necessary for SARS-CoV-2 infection and through androgen-mediated immune modulation. In women with PCOS the endocrine-immune axis leads to immune dysfunction with a state of chronic inflammation, and hyperandrogenism and IR with compensatory hyperglycaemia could play a determining role in the pathophysiogenesis of the infection. However, it is possible that only specific PCOS phenotypes may be more susceptible. In addition, vitamin D deficiency and gut dysbiosis are another important factor potentially involved in the increased risk of developing severe forms of COVID-19 in PCOS women. Further scientific investigations are needed with the aim of understanding which women are most at risk of becoming infected or developing complications, what are the causal mechanisms on which it is possible to intervene with prophylactic and therapeutic measures and what the long-term consequences will be on the health of these patients.

Gut microbiota steroid sexual dimorphism and its impact on gonadal steroids: influences of obesity and menopausal status

BACKGROUND

Gonadal steroid hormones have been suggested as the underlying mechanism responsible for the sexual dimorphism observed in metabolic diseases. Animal studies have also evidenced a causal role of the gut microbiome and metabolic health. However, the role of sexual dimorphism in the gut microbiota and the potential role of the microbiome in influencing sex steroid hormones and shaping sexually dimorphic susceptibility to disease have been largely overlooked. Although there is some evidence of sex-specific differences in the gut microbiota diversity, composition, and functionality, the results are inconsistent. Importantly, most of these studies have not taken into account the gonadal steroid status. Therefore, we investigated the gut microbiome composition and functionality in relation to sex, menopausal status, and circulating sex steroids.

RESULTS

No significant differences were found in alpha diversity indices among pre- and post-menopausal women and men, but beta diversity differed among groups. The gut microbiota from post-menopausal women was more similar to men than to pre-menopausal women. Metagenome functional analyses revealed no significant differences between post-menopausal women and men. Gonadal steroids were specifically associated with these differences. Hence, the gut microbiota of pre-menopausal women was more enriched in genes from the steroid biosynthesis and degradation pathways, with the former having the strongest fold change among all associated pathways. Microbial steroid pathways also had significant associations with the plasma levels of testosterone and progesterone. In addition, a specific microbiome signature was able to predict the circulating testosterone levels at baseline and after 1-year follow-up. In addition, this microbiome signature could be transmitted from humans to antibiotic-induced microbiome-depleted male mice, being able to predict donor's testosterone levels 4 weeks later, implying that the microbiota profile of the recipient mouse was influenced by the donor's gender. Finally, obesity eliminated most of the differences observed among non-obese pre-menopausal women, post-menopausal women, and men in the gut microbiota composition (Bray-Curtis and weighted unifrac beta diversity), functionality, and the gonadal steroid status.

CONCLUSIONS

The present findings evidence clear differences in the gut microbial composition and functionality between men and women, which is eliminated by both menopausal and obesity status. We also reveal a tight link between the gut microbiota composition and the circulating levels of gonadal steroids, particularly testosterone. Video Abstract.

Obesity as a risk factor for COVID-19: an overview

The current coronavirus disease-2019 (COVID-19) pandemic presents a huge challenge for health-care systems worldwide. Many different risk factors are associated with disease severity, such as older age, diabetes, hypertension, and most recently obesity. The incidence of obesity has been on the rise for the past 25 years, reaching over 2 billion people throughout the world, and obesity itself could be considered a pandemic. In this review, we summarize aspects involved with obesity, such as changes in the immune response, nutritional factors, physiological factors, and the gut-lung axis, that impact the viral response and the COVID-19 prognosis.