ClC-2 chloride secretion mediates prostaglandin-induced recovery of barrier function in ischemia-injured porcine ileum

Abstract

Background & Aims Ischemia results in the breakdown of the intestinal barrier, predisposing patients to sepsis and multiple organ failure. Prostaglandins play a critical role in mediating recovery of barrier function in ischemia-injured intestine through a mechanism involving stimulation of Cl - secretion. In the present study, we investigated the contributory role of individual Cl- channels in the recovery of barrier function in ischemia-injured porcine ileum. Methods Ischemia-injured porcine ileal mucosa was mounted in Ussing chambers. Short-circuit current (Isc) and transepithelial resistance (TER) were measured in response to prostaglandin E2 (PGE2) and pharmacologic inhibitors of epithelial Cl- channels. Immunoassays were used to assess the expression and localization of ion channels. Results Application of PGE2 to ischemia-injured ileal mucosa stimulated increases in Isc, an indicator of Cl- secretion, that was followed by marked increases in TER, an indicator of barrier function recovery. In vitro studies revealed that although PGE2 induced Cl- secretion via at least 3 distinct secretory pathways, recovery of barrier function was initiated by Cl- secretion via ClC-2 Cl - channels co-expressed with occludin and localized to tight junctions within restituting epithelium. Intravenous administration of furosemide to pigs subjected to 1 hour of ileal ischemia impaired recovery of barrier function, as evidenced by decreased TER and increased mucosal-to-serosal 3H-mannitol flux after a 2-hour reperfusion/recovery period, confirming an important role for Cl- secretory pathways in vivo. Conclusions ClC-2-mediated intestinal Cl- secretion restores TER in ischemia-injured intestine. These data may provide the basis for targeted pharmacologic therapy for diseases associated with impaired barrier function.