523 Helicobacter pylori cag+ Strains Stimulate Expansion of Lrig1+ Progenitor Cells Within the Gastric Mucosa in a Strain-Specific Manner

Abstract

Background & Aims. Despite the preponderance of stress-related diseases and inflammatory bowel disease (IBD) in women, the role of the corticotropin-releasing factor (CRF) system in mediating sex-specific effects on cellular signaling and immune function has not been systematically investigated. In this study, we determined the contribution of CRF receptor 2 (CRF2) in mediating sex-specific responses during colitis in mice. Methods. Colitis was induced by 2,4,6-trinitrobenzenesulfonic acid (TNBS) in wild-type, CRF2, and CRF2 mice of both sexes and treated with the CRF2 agonist urocortin1 (Ucn1) or saline. Changes in gastrointestinal permeability were detected using Evan's blue dye method to measure plasma extravasation. Changes in immune cell infiltration were determined using flow cytometry and changes in the MAPK signaling pathway were assessed by western blot analysis. Results. Baseline plasma extravasation in the gastrointestinal tract was ~1.4-1.74fold higher in females than in males in all three different genotypes. Colitis increased plasma extravasation in the distal colon in both sexes in all three different genotypes. Interestingly, the sex-specific difference in plasma extravasation was maintained in Wt, but lost in CRF2 and CRF2 mice during colitis. Colitis resulted in greater thymus atrophy, loss of spleen mass, adrenal hypertrophy, and neutrophil infiltration in the blood and in the colon in Wt female mice than in Wt males. Wt females showed a ~4-fold higher neutrophil infiltration in the colon than Wt males and this sex-specific difference was lost in CRF2 and CRF2 mice. Surprisingly, colitis-induced mortality was abolished in male CRF2 mice, but exceeded 25% in female CRF2 mice. Although Ucn1 intervention rescued colitis-induced mortality in male CRF2 mice, female CRF2 mice showed increased mortality and worsened inflammation after Ucn1 intervention. The p38 MAPK signaling pathway regulates inflammatory responses and is altered in IBD. We found dysregulated p38 MAPK signaling in CRF2 mice of both sexes, accompanied by decreased phosphorylation of downstream target heat shock protein 27 (Hsp27) during colitis. Ucn1 restored the phosphorylation levels of Hsp27 back to baseline levels in male, but not female CRF2 mice. Conclusions. Ucn1 and CRF2 mediate contextand sex-dependent inflammatory responses at the molecular, cellular and organ levels during IBD. Our observations suggest that Ucn1 intervention can rescue colitisinduced mortality in males alone. In males, Ucn1 ameliorates inflammation by mechanisms that involve the MAPK signaling pathway and phosphorylation of Hsp27 that regulates stabilization and formation of tight junctions in the gut epithelium.