Introduction
Polycystic ovary syndrome (PCOS) is a leading endocrine cause of female
infertility characterized by oligo-amenorrhea or
ovulatory
dysfunction (OA), hyperandrogenism (HA), and polycystic ovarian
morphology (PCOM)1. The global prevalence of PCOS is
estimated to be 5-15% based on the diagnostic criteria
applied2. PCOS can also lead to metabolic
manifestations such as obesity, hyperinsulinemia/insulin resistance
(IR), and an increase in the risk of developing type 2 diabetes
(T2D)3, 4 and coronary heart
disease5. One of the most widely used diagnostic
criteria for PCOS is the Rotterdam criteria6, which
requires the presence of at least two of above three cardinal traits.
This results in four different phenotypes: phenotype A: HA + OA + PCOM;
phenotype B: HA + OA; phenotype C: HA + PCOM; phenotype D: OA+ PCOM,
which diversifies the presentation of PCOS.
Despite its prominent impact on female reproductive and metabolic
health, the etiology of PCOS remains unclear. Although attention has
been focused on key genetic factors during the past
decade2, recent studies on PCOS intestinal microbiota
have suggested a novel environmental-related disease
mechanism7, 8. Apart from the gut, another important
microbial niche in women is the vagina. Dysbiosis of the microbiome in
the lower female reproductive tract has been implicated in a variety of
diseases, such as preterm birth9, sexually transmitted
infections 10, 11, pelvic inflammatory
disease12, and gynecological
cancers13, 14. Recent studies have also begun to
explore the role of the vaginal microbiome (VMB) in PCOS. However, due
to a limited sample size and complex confounding factors of the selected
cohort, studies that used 16S ribosomal RNA (16s rRNA) gene sequencing
techniques to compare women diagnosed with PCOS and healthy controls
have led to different results regarding the diversity and composition of
the vaginal microbiota15, 16. Furthermore, endocrine
and metabolic characteristics vary among different PCOS
subsets17, but discrepancies in vaginal microbial PCOS
subtypes have rarely been clarified.
In this study, we analyzed the vaginal microbial characteristics of
1,446 subjects using high-throughput sequencing to determine the
microbial characteristics, bacterial community interactions, as well as
functional prediction of the vaginal microbiota and different subsets
related to PCOS.