Association Between Polycystic Ovary Syndrome and the Vaginal Microbiome

A Case-Control Study

Xiang Hong; Pengfei Qin; Kaiping Huang; Xiaoling Ding; Jun Ma; Yan Xuan; Xiaoyue Zhu; Danhong Peng; Bei Wang

Disclosures

Clin Endocrinol. 2020;93(1):52-60. 

In This Article

Abstract and Introduction

Abstract

Background: Polycystic ovary syndrome (PCOS) is the most common endocrinopathy in women of reproductive age. Some evidence suggests that dysbiosis of the gut microbiota could be associated with PCOS clinical parameters, but little is known for the association between vaginal microbiome and PCOS.

Objective: To determine differences in the vaginal microbiome between women with PCOS and healthy control women.

Research design and methods: In this case-control study, the women with newly diagnosed PCOS (n = 39) and healthy controls (n = 40) were included from the hospital and maternal and child health centre, respectively. The vaginal swabs were collected, and microbiome structures were identified by 16S rRNA gene sequencing. The screening values for potential bacteria biomarker for PCOS were assessed by receiver operating characteristic (ROC) curve method.

Results: There was significant difference in vaginal bacterial structures between PCOS and healthy control women. The vaginal bacterial species in the PCOS group were more diverse than the control group (Simpson index for PCOS group vs. control group: median 0.49 vs. 0.80, P = .008; Shannon index: median 1.07 vs. 0.44, P = .003; Chao1 index: median 85.12 vs. 66.13, P < .001). The relative abundance of Lactobacillus crispatus in the PCOS group was significantly lower than controls (P = .001), and the relative abundance of Mycoplasma and Prevotella was higher than controls (P < .001, P = .002, respectively). The Mycoplasma genus could be a potential biomarker for PCOS screening, as ROC analysis showed that the area under the curve (AUC) for the relative abundance of Mycoplasma was 0.958 (95% CI: 0.901–0.999). Subgroup analyses also showed these associations would not change among the women with the same BMI level and vagina cleanliness grading.

Conclusions: In the vaginal microbiome, the Mycoplasma genus was associated with PCOS. Further research is required to explore causal correlations between PCOS and the vaginal microbiome.

Introduction

Polycystic ovary syndrome (PCOS) is the most common endocrinopathy in women of reproductive age, the prevalence of which is approximately 10% globally.[1] The syndrome is a serious public health problem, with long-term health consequences. Apart from the usual clinical symptoms (menstrual disorders, hirsutism, infertility and obesity), women with PCOS have long-term metabolic consequences (ie impaired glucose tolerance, type 2 diabetes mellitus, metabolic syndrome and nonalcoholic fatty liver disease[2]). The disease aetiology is still unclear; however, some hypotheses include hypothalamic-pituitary-ovary axis dysfunction, androgen excess[3] and insulin resistance and glucagon.[4] Equally, genetic and environmental factors (such as endocrine disruption) play critical roles in PCOS occurrence.[5,6]

With developments in human microbiome research, some evidence suggests that dysbiosis of the gut microbiota could be associated with PCOS clinical parameters,[7,8] which could be potentially helpful in unravelling syndrome pathogenesis and biomarker exploration. But the stool samples are not collected routinely in gynaecological clinics, which limited the application value for gut microbiome. Conversely, vaginal swabs are relatively easy to be collected, but to the best of our knowledge, no studies have yet shown any associations between the vaginal microbiome and PCOS. Although the vaginal microbiome is relatively simple and dominated by Lactobacillus,[9] recent studies have suggested that vaginal dysbiosis might be associated with gynaecological cancer,[10] gestational diabetes,[11] adverse pregnancy outcome[12] and infertility.[13] It is accepted that infertility is a common clinical complication caused by PCOS.[1] Equally, not all Lactobacillus are beneficial, especially L iners which is a controversial species in the vagina.[9] Research has suggested that sexually transmitted infections (STIs) are important risk factors for female tubal infertility,[14] but whether they impact on PCOS is not known. In considering the microbiome continuum along the female reproductive system, including vaginal, cervix, uterine cavity and fallopian tube areas,[15] the vaginal microbiome exerts potential effects on ovary development. Furthermore, changes in vaginal microbiota communities may become effective biomarkers for disease screening.[16]

Meanwhile, with developments in bioinformatics technology, some omics-based indices, such as Shannon, Simpson and Chao1 indices, were used to refer to the average species diversity of microbiome community in a specific area in human, instead of describing specific species.[17] Through these indices, some subtle human microbiota structure changes can be observed to be associated with diseases.[13,18] Hence, we conducted a case-control study to determine differences in the vaginal microbiome between women with PCOS and healthy control women. We sought to understand associations between PCOS and the vaginal microbiome and determine potential vaginal bacterial biomarker for PCOS.

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