IL22 and polycystic ovary syndrome: Fecal microbiota transplantation from women with PCOS or B. vulgatus transfer into recipient mice led to the development of PCOS clinical phenotypes such as insulin resistance, altered bile acid metabolism, decreased IL‐22 secretion, and infertility [438], and these changes were chiefly mediated by agmatine, a metabolite derived from B. vulgatus.