Given that alternation of intestinal microbiota regulated AhR activation (Fig. 3A–C), deteriorated pathogen-induced endometritis (Fig. 4A–J), and reversed Trp protective effects in gut-dysbiotic mice (Fig. 5A-J), we then tested whether AhR ligand production by gut microbial Trp metabolism accounted for the protective effects of Trp against E. coli-induced endometritis. Here, AHR is linked to endometritis.