What are the different characteristics of the vaginal microbiome (VMB) between patients with polycystic ovary syndrome (PCOS) and healthy women?
A cross-sectional study was conducted in a single university-affiliated academic center.
1446 participants were recruited the group with polycystic ovary syndrome consisting of 713 people and the control group consisting of 733 people. Vaginal swabs were analyzed by 16S rRNA gene sequencing. The diversity and composition of the microbiome were compared between the PCOS group and the control group, and microbial interaction networks and functional prediction were studied.
The results of the study showed that the group with polycystic ovary syndrome had higher alpha diversity than the control group (Shannon P = 0.03, Simpson P = 0.02), and greater intragroup variability was observed in the PCOS group (P < 2.2E-16).
At the gender level, the percentage of Lactobacillus decreased 85.1% vs. 89.3%, false discovery rate [FDR] = 0.02, while the percentage of Gardnerella vaginalis and Ureaplasma increased in the PCOS group (5.1% vs. 3.3%, FDR = 0.006; 1.2% vs. 0.6%, FDR = 0.002, respectively). Lactobacillus acidophilus, Prevotella buccalis and G. vaginalis were identified as the main differential species.
L. acidophilus was positively correlated with serum levels of anti-Müllerian hormone (AMH) and triglycerides (P = 2.01E-05, P = 0.004, respectively). P. buccalis was negatively correlated with serum AMH and testosterone levels (P = 0.002, P = 0.003, respectively). G. vaginalis was positively correlated with serum levels of AMH, estradiol and progesterone (P = 0.004, P = 0.005, P = 0.03, respectively).
The network of interactions with the vaginal microbiome indicated that Lactobacillus crispus, Prevotella timonensis and P. buccalis could be key factors in the group with polycystic ovary syndrome. Overall, 55 predicted genes were found to be differentially abundant between PCOS and control (FDR < 0.25).
In conclusion, the group with polycystic ovary syndrome has a greater diversity of the vaginal microbiome and shows a higher level of heterogeneity. The proportion of Lactobacillus in the group with polycystic ovary syndrome decreased, while the proportions of Gardnerella and Ureaplasma increased.
A study on polycystic ovary in women
A team of Chinese researchers conducted a cross-sectional study on an academic center affiliated with Shandong University in order to investigate the characteristics of the vaginal microbiota and networks of bacterial interactions in women with polycystic ovary disease (PCOS). The study sample included a total of 1,446 participants, including 713 in the PCOS group and 733 in the control group. The results of this research were published in the scientific journal Reproductive BioMedicine.
Swabs subjected to 16S rRNA gene sequencing were used to analyze the vaginal microbiota. In addition, the PCOS group was divided into two subgroups: PA (with the presence of amenorrhea, hyperandrogenism and multifollicular polycystic ovary) and PD (with the presence of amenorrhea and multifollicular polycystic ovary).
The following are the main results obtained:
- PCOS presents greater diversity and heterogeneity of vaginal microbiota within the study group.
- In the PCOS group, a percentage decrease in the genus Lactobacillus was observed, while the presence of Gardnerella and Ureaplasma increased.
Correlations were found between vaginal microbiota and clinical indicators of PCOS. The bacterial species G. vaginalis, Prevotella buccalis and Prevotella timonensis were identified as differential species and found to be significantly associated with blood parameters of PCOS.
For example, G. vaginalis was found to be positively correlated with serum levels of anti-Mullerian hormone (AMH), estradiol and progesterone; Ureaplasma parvum and Acinetobacter baumannii were found to be positively correlated with AMH, LH and testosterone, while Prevotella buccalis was found to be negatively correlated. In addition, HDL and triglyceride levels were found to be associated with the abundance of Lactobacillus acidophilus, Prevotella buccalis and Ureaplasma parvum.
Lactobacillus crispatus and Prevotella timonensis were found to be the key bacterial species in the changes of vaginal microbiota interactions in the PCOS group.
The findings of the article indicate that the significant decrease of Lactobacillus in patients with PCOS may cause changes in vaginal pH and destruction of the immune barrier. This could facilitate the colonization and growth of potentially pathogenic vaginal commensal anaerobic bacteria such as G. vaginalis, U. parvum, Prevotella spp. and A. baumannii. These bacteria can not only cause more frequent and serious illnesses, but also potentially be related to bacterial vaginosis, miscarriages, premature births, and precancerous and cancerous cervical lesions.
The authors of the article point out that the poor prognosis of pregnancies in patients with PCOS could be influenced not only by the disease itself, but also by the vaginal microbiological status, which should not be neglected. Therefore, changing the composition of the vaginal microbiota could be a new therapeutic approach to improve clinical outcomes.
However, endocrine disorders in PCOS cannot be neglected, as they could affect the diversity and composition of the vaginal microbiota. In other words, there might be a mutual causal relationship between PCOS and vaginal microbiota.
Further studies will be needed to validate the correlation between PCOS and vaginal microbiota and to verify the model that emerged from this research, which seems to be able to accurately distinguish PCOS patients from healthy control subjects.
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