Antibiotic cocktail-induced changes in gut microbiota drive alteration of bile acid metabolism to restrain Th17 differentiation through the FXR–NLRP3 axis

Antibiotics influence both gut microbial composition and immune regulation, but the detailed mechanisms are still undefined. Shifts in the microbiome caused by antibiotic exposure can modulate immune activity through various pathways. Therefore, we aimed to explore how antibiotics affect immune-inflammation by regulating Th17 cells through the gut microbiota of mice with experimental autoimmune prostatitis (EAP). Antibiotic-driven shifts in gut microbial communities and metabolite profiling in EAP mice were performed by integrating 16S rRNA sequencing with mass spectrometry–driven metabolomic analysis. Antibiotic cocktail (ABX) therapy mitigated EAP, modified the gut microbiome composition, and influenced bile acid metabolism. Fecal microbiota transplantation (FMT) using microbiota from ABX-treated feces into EAP mice effectively altered gut microbiome composition and alleviated disease symptoms, indicating that microbiome intervention reduces autoimmune inflammation and decreases deoxycholic acid (DCA) in mice. Subsequent experiments demonstrated that DCA suppresses farnesol X receptor (FXR) expression which can inhibit the NLRP3‒ IL17A axis, thus promoting Th17 cell development and exacerbating inflammatory cell infiltration of the prostate. Our initial clinical examination of patients with prostatitis and antibiotic treatment indicated that bile acid metabolism and Th17 cell development are affected by antibiotic therapy. This work revealed that antibiotic-induced gut microbiota dysbiosis decreases the bile acid metabolite DCA, further restraining Th17 cell differentiation via the FXR‒NLRP3 axis to alleviate autoimmune prostatitis. Our results reveal new perspectives regarding the interconnected dynamics of antibiotics, gut microbiota, bile acid metabolism, and immune regulation, with potential relevance for therapies targeting immune-mediated diseases.