Increase in permeability and phospholipase A2 activity of colonic mucosa in Crohn's colitis.

Patients with Crohn's colitis were investigated regarding the relationship between intestinal inflammation, mucosal activity of phospholipase A2 and intestinal permeability to different-sized polyethylene glycols (PEG). Mucosal specimens for phospholipase A2 were obtained at colonoscopy and PEG (590-942 daltons) were deposited in the descending colon. Colonic absorption was measured as urinary output of deposited PEG. Colonic absorption of PEG was higher in these patients, even when the colitis was in remission at colonoscopy, than in ileal Crohn's disease or control patients. Mucosal phospholipase A2 activity was increased in active colitis, but in the patients with endoscopic remission it was at the same level as in the controls or in the patients with ileal Crohn's disease. The observations suggest that increased intestinal permeability may be a primary factor in activation of mucosal phospholipase A2 activity and in intestinal inflammation.