BGI-L99 alleviates PCOS-like symptoms in mice through a gut microbiota-bile acid-IL-22 pathway

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders among women of reproductive age and is linked to ovulatory dysfunction, hyperandrogenism, metabolic complications and a higher risk of mood disorders. Growing evidence suggests that gut microbiota dysbiosis contributes to PCOS, but the mechanisms by which individual probiotic strains may help remain unclear.

In a study published in iMetaMed, researchers investigated Bifidobacterium animalis subsp. lactis BGI-L99, a human-derived probiotic strain, in a dehydroepiandrosterone (DHEA)-induced mouse model of PCOS. After PCOS-like symptoms were induced, mice received oral BGI-L99 for 21 days.

BGI-L99 treatment improved several PCOS-like phenotypes in mice. The intervention restored estrous cycle regularity, increased corpora lutea, reduced cystic follicles, lowered serum testosterone and increased estradiol. The study also reported improved fasting glucose and lipid profiles and reduced depression-like and anxiety-like behaviors in the mouse model.

Multi-omics analyses suggested that the probiotic acted through a gut microbiota-bile acid-IL-22 axis. BGI-L99 shifted gut microbial composition and function, restored fecal levels of the bile acids chenodeoxycholic acid (CDCA) and tauroursodeoxycholic acid (TUDCA), and increased IL-22, a cytokine involved in intestinal and ovarian homeostasis. Direct supplementation with CDCA or TUDCA reproduced key reproductive and immune effects, supporting a causal role for these bile acids in the pathway.

The authors emphasize that the findings are preclinical. The work was performed mainly in mouse models, with public human metagenomic data re-analyzed to assess clinical relevance, and the efficacy of BGI-L99 in people with PCOS will need to be tested in well-designed clinical trials.