Interestingly, E. coli-treated gut-dysbiotic mice developed more serious endometritis than E. coli-treated conventional mice, as shown by increased uterine macroscopic inflammatory changes (Fig. 4B), inflammatory infiltration and barrier disruption (Fig. 4C and D), and inflammatory markers including MPO activity (Fig. 4E), TNF-α (Fig. 4F), and IL-1β (Fig. 4G) in the E. coli-treated gut-dysbiotic mice compared with conventional mice. Here, MPO is linked to endometritis.