Fig. 4

Fpr2 is required for E. coli to promote the colon epithelial cell regeneration. A, B The germ-free (GF) mice pre-orally inoculated with E. coli increased mouse survival (A) and reduced the loss of body weight (B) after challenged with DSS. C. Reduced crypt damage in the colon of GF mice pre-orally inoculated with E. coli. Scale bar = 50 µm. Right: Quantitative scores for crypt damage. n = 99–122 crypts from 4 mice per group, ****P < 0.0001. D Increased number of Ki67 + cells in the colon mucosa of GF mice pre-orally inoculated with E. coli. Red: Ki67 + cells, Blue: Nuclei. Scale bar = 50 µm. Right: Quantitative Ki67 + fluorescence intensity/crypt. n = 30 crypts from 4 mice per group, ****P < 0.0001. E Upregulation of Fpr2 expression by colon epithelial cells with E. coli infection in GF wild type (WT) mice. Upper: Scale bar = 30 µm, lower: Scale bar = 40 µm. Right: Quantitative Fpr2 + fluorescence intensity/crypt. n = 32 crypts from 4 mice/group, ****P < 0.0001. F E. coli supernatant induced CT26 cell migration. n = 3 mice/group, ***P < 0.001. G E. coli supernatant induced CT26 cell migration can be inhibited by the Fpr2 antagonist WRW4 (5 µg/ml) and Fpr1/Fpr2 antagonist BOC2 (5 µg/ml). n = 3 per group, ***P < 0.001. The results of F and G are expressed as the mean ± S.D. of the chemotaxis index (CI). H E. coli supernatant-enhanced closure of CT26 cell monolayer wound was attenuated by Fpr1/Fpr2 antagonist BOC2 (5 µg/ml). Scale bar = 40 µm. Right: Quantitative CT26 cells migration distance (µm) induced by E. coli supernatant. BOC2 (5 µg/ml). n = 8 fields/group, ***P < 0.001