Effect of Schistosoma mansoni-induced granulomatous inflammation on murinegastrointestinal motility

In Schistosoma mansoni-infected mice, gastrointestinal transit was measured in vivo and the neuromuscular function of longitudinal muscle strips of in flamed ileum and noninflamed gastric fundus was assessed in vitro. Eight we eks after infection, the ileal wall was acutely inflamed, as shown by a muc osal inflammatory infiltrate, leading to an increase in mucosal thickness, in myeloperoxidase (MPO) activity, and in interleukin (IL)-1 beta productio n. At that time, both gastrointestinal transit and in vitro ileal contracti lity were normal. Twelve weeks after infection, chronic granulomatous infla mmation led to proliferation of the muscle layer and to a further increase in MPO activity, whereas IL-1 beta production normalized. Gastrointestinal transit was decreased, whereas in vitro ileal contractility was increased i rrespective of the contractile stimulus. In vitro incubation with IL-1 beta (10 ng/ml for 60 min) significantly increased ileal contractility only at 8 wk after infection. Indomethacin, tetrodotoxin, and atropine had no diffe rential effect on ileal contractility in controls and infected mice. In vit ro contractility of noninflamed gastric fundus was normal both 8 and 12 wk after infection. We conclude that intestinal schistosomiasis 8 wk after inf ection is associated only with structural changes of the ileum, whereas 12 wk after infection, both structural and functional changes are present. The se changes are characterized by increased ileal wall thickness, decreased g astrointestinal transit, and increased smooth muscle contractility restrict ed to the inflamed gut segment.