Schistosoma mansoni infection causing diffuse enteric inflammation and damage of the enteric nervous system in the mouse small intestine.

Schistosomiasis mansoni is a major health problem, mainly occurring in developing countries. A large proportion of infected individuals suffers from motility-related gastrointestinal problems. In the present study, the diffuse inflammatory response in the small bowel wall, as compared to the egg-induced granulomatous inflammation, was investigated. For this purpose, OF1 mice infected with Schistosoma mansoni 8-16 weeks prior to the experiment, and uninfected control mice were studied. The ileum showed both a diffuse mucosal inflammation as well as a granulomatous reaction. The diffuse mucosal inflammation caused an increase in the thickness of the mucosa, with blunting of the villi. A significant, transient increase of thickness of the muscularis propria after 12 weeks of infection was noted. There was an infection-related mast cell infiltrate in the muscularis propria, consisting of formalin fixation-insensitive connective tissue mast cells. Ganglionitis of the myenteric plexus was noted. Rarely, ganglia of the myenteric plexus contained apoptotic cells. A general pharmacological set of experiments showed a significant increase in intestinal contractility, both to exogenously administered, as well as to endogenously released neurotransmitters. Our results demonstrate that S. mansoni infection in the mouse ileum leads to diffuse specific enteric inflammation that is associated with an enhanced response to contractile agents.