Comparison of the chloride channel activator lubiprostone and the oral laxative Polyethylene Glycol 3350 on mucosal barrier repair in ischemic-injured porcine intestine.

AIM: To investigate the effects of lubiprostone and Polyethylene Glycol 3350 (PEG) on mucosal barrier repair in ischemic-injured porcine intestine. METHODS: Ileum from 6 piglets (approximately 15 kg body weight) was subjected to ischemic conditions by occluding the local mesenteric circulation for 45 min in vivo. Ileal tissues from each pig were then harvested and mounted in Ussing chambers and bathed in oxygenated Ringer's solution in vitro. Intestinal barrier function was assessed by measuring transepithelial electrical resistance (TER) and mucosal-to-serosal fluxes of (3)H-mannitol and (14)C-inulin. Statistical analyses of data collected over a 120-min time course included 2-way ANOVA for the effects of time and treatment on indices of barrier function. RESULTS: Application of 1 micromol/L lubiprostone to the mucosal surface of ischemic-injured ileum in vitro induced significant elevations in TER compared to non-treated tissue. Lubiprostone also reduced mucosal-to-serosal fluxes of (3)H-mannitol and (14)C-inulin. Alternatively, application of a polyethylene laxative (PEG, 20 mmol/L) to the mucosal surface of ischemic tissues significantly increased flux of (3)H-mannitol and (14)C-inulin. CONCLUSION: This experiment demonstrates that lubiprostone stimulates recovery of barrier function in ischemic intestinal tissues whereas the PEG laxative had deleterious effects on mucosal repair. These results suggest that, unlike osmotic laxatives, lubiprostone stimulates repair of the injured intestinal barrier.

Neutrophils increase paracellular permeability of restituted ischemic-injured porcine ileum.

BACKGROUND: We have previously shown minimal evidence of neutrophil infiltration during early reperfusion of porcine ischemic ileum. However, we noted marked neutrophil infiltration 6 to 18 hours after ischemia during mucosal repair. We postulated such neutrophil infiltration would disrupt restituting epithelium. METHODS: Pigs were pretreated with anti-CD11/CD18 monoclonal antibody, superoxide dismutase-polyethylene glycol, or saline solution before inducing 1 hour of ischemia. Pigs recovered for up to 18 hours, after which mucosal repair was assessed. RESULTS: One hour of ischemia induced loss of 19 +/- 7% of the villous epithelial surface area. Epithelial restitution covered the mucosal defect within 2 hours, although full recovery of mucosal barrier function required 6 hours. By 18 hours, a significant decrease in transepithelial electrical resistance and increase in transmucosal mannitol flux was noted despite the continued presence of complete epithelial coverage. Accumulation of neutrophils within restituting epithelium was noted on histologic examination, associated with electron-microscopic evidence of widened paracellular spaces. Pretreatment with anti-CD11/CD18 monoclonal antibody and superoxide dismutase-polyethylene glycol significantly reduced neutrophil infiltration and normalized transepithelial electrical resistance and mannitol fluxes. CONCLUSIONS: Mucosal inflammation during epithelial repair resulted in increased paracellular permeability as neutrophils traversed restituted epithelium. Blocking neutrophil adhesion or scavenging superoxide prevented mucosal dysfunction in recovering tissue.