Moreover, E. coli treatment caused colitis: it caused colon shortening [F(1,14) = 73.263, p < 0.001]; increased myeloperoxidase activity [F(1,14) = 524.384, p < 0.001], IL-6 [F(1,14) = 10.814, p = 0.005], and TNF-α [F(1,14) = 57.048, p < 0.001] expression and monocyte population; suppressed the expression of tight junction proteins; increased NF-κB activation and CD11b+/CD45+ population in the colon; and increased Proteobacteria in gut microbiota (Figs 4n–r and S3c–i). Here, MPO is linked to colitis.