Background & aims: Corticotropin-releasing hormone (CRH) released at local sites of inflammation promotes inflammation in the periphery. We investigated its effects in the intestinal responses caused by toxin A from Clostridium difficile, the causative agent of antibiotic-associated colitis.
Methods: Ileal loops were injected with 10 microg of toxin A, and enterotoxic responses were measured at various time points.
Results: Pretreatment of mice with 2.5 microg/kg of the CRH receptor antagonist alpha-helical CRH((9-41)) that blocks both CRH receptor subtypes reduced toxin A-mediated ileal secretion, epithelial cell damage, mucosal edema, neutrophil infiltration, and mucosal content of interleukin 1 beta and tumor necrosis factor alpha. Pretreatment with the specific CRH(1) receptor antagonist antalarmin (20 mg/kg, IP) also inhibited toxin A-induced fluid secretion and toxin A-associated histologic changes. CRH messenger RNA and protein were increased in mouse ileum 30 minutes after intraluminal toxin A administration. In situ hybridization and immunohistochemistry demonstrated that toxin A at 1 hour caused a substantial increase in the expression of both CRH receptor subtypes in the ileal mucosa.
Conclusions: Peripheral CRH may play a proinflammatory role in toxin A-induced intestinal secretion and inflammation and that CRH(1) receptor, at least in part, is important in the mediation of these responses.