Probiotic <italic>Bifidobacterium lactis</italic> V9 regulates the intestinal microbiome in patients with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common metabolic disorders among women of reproductive age worldwide. It is also one of the common causes of female infertility. The effect of probiotics has been gradually revealed and recognized by the public. Previous studies have shown that probiotic intervention can effectively improve intestinal microbiome and relieve metabolic diseases represented by obesity and type 2 diabetes. Although a few studies have investigated the intestinal microbiota profiles of women with PCOS, the regulatory effect of the probiotic Bifidobacterium lactis V9 has yet to be revealed. We hope that Bifidobacterium lactis V9 can improve the metabolism of patients by regulating the intestinal flora, thus slowing down the disease. To address this gap, in this study, metagenomics and metabolomics were used together to analyze the effects of Bifidobacterium lactis V9 on patients with PCOS. Nine patients with PCOS were selected to comsume 15 billion probiotic Bifidobacterium lactis V9 every day during the intervention period. Fecal samples were collected from patients at week 0, week 1, week 2 and week 4. The results showed that Bifidobacterium lactis V9 had stable colonization ability in the intestinal tract of patients. The abundance of Bifidobacterium and Faecalibacterium significantly increased, while that of other bacteria significantly decreased, including Clostridium , Collinsella , Ochrobactrum , Streptococcus , Prevotella , Coprococcus and Actinomyces and the opportunistic pathogen Klebsiella is almost gone. The results of metabonomic analysis showed that the metabolic level of glucocorticoids was significantly reduced and the metabolic level of short chain fatty acids such as acetic acid, propionic acid and butyric acid was significantly increased. PPAR signal pathway and adipocytokine signal pathway associated with insulin resistance and lipid metabolism were decreased significantly based on PICRUSt. Furthermore, the regulation functions of Bifidobacterium lactis V9 on intestinal microbiome in patients with polycystic ovary syndrome was further revealed based on the analysis of the network interaction between different genus and metabolic functional units. As expected, Bifidobacterium lactis V9 can improve the bodys metabolism by regulating the intestinal flora of patients with PCOS, which is conducive to slowing down the clinical symptoms of patients. To sum up, this study revealed the changes of intestinal microbiome and metabolites of patients with PCOS after 4 weeks of consumption of probiotic Bifidobacterium lactis V9 by using multi-group technique including metagenomics and metabolomics. Although we have observed that Bifidobacterium lactis V9 is beneficial to patients with PCOS, the regulatory mechanism needs to be revealed in larger clinical trials. At the same time, we need to find biomarkers and target them for the treatment of metabolic diseases through probiotics. The results of this study provide new insights into the treatment of PCOS and offer objective and detailed data supporting the use of probiotic treatments for metabolic diseases.