Interstitial cells of Cajal in patients with chagasic megacolon originating from a region of old endemicity.

UNLABELLED: Megacolon is the second most frequent and most important digestive manifestation of Chagas' disease. It is characterized by motor disorders and dilatation of the distal segments of the colon. Several theories have been presented to explain the physiopathology of chagasic megacolon, e.g. the plexus theory. OBJECTIVE: In the present study the distribution of interstitial cells of Cajal (ICC) was evaluated in colon biopsies from chronic chagasic patients originating from a region of old endemicity for Trypanosoma cruzi and for comparison in subjects with other colon disorders. The chagasic patients had been submitted to colectomy for the investigation of other possible mechanisms underlying the physiopathogenesis of megacolons. DESIGN STUDY: Twenty-two colon biopsies (15 from chagasic patients and 7 from nonchagasic patients) were examined. ICC were identified by immunohistochemistry by using the anti-CD117 antibody. The number of ICC was determined in longitudinal and circular muscle layers and in the myenteric plexus, and the results were analyzed by the Kruskal-Wallis and Student t-tests. RESULTS: A reduced number of ICC was observed in all layers and in the myenteric plexus of patients with chagasic megacolon (P<0.05). CONCLUSIONS: We conclude that the physiopathological manifestations observed in the large bowel of chagasic patients originate from alterations that occur in the ICC, which play an important role in the control of gut motility.

Hepatocyte metaplasia in experimental chagasic pancreatitis: preliminary report.

Beginning the study of chronic pathologic changes in pancreas of hamsters experimentally infected with Trypanosoma cruzi Vic strain, hepatocyte metaplasia was observed in one animal from infected group. This is the first report of oncocytes in Chagas' disease, which could be due to aberrant regenerative response to pancreas inflammatory process.

Trypanosoma cruzi: characterization of reinfection and search for tissue tropism in hamsters (Mesocricetus auratus).

Tissue tropism, the role of reinfection in the development of Chagas' disease, and the selection of subpopulations of Trypanosoma cruzi were evaluated in hamsters inoculated with the VIC strain of T. cruzi. Adult allogeneic male hamsters were inoculated once or reinoculated by the intraperitoneal route up to four times with 2000 blood trypomastigotes. Animals were studied by blood culture, histopathology, immunohistochemistry, and molecular techniques (PCR and low-stringency single specific primer-PCR). Homogeneity of the T. cruzi population observed in different tissues suggests that selective tropism of the VIC strain extends only to various muscle tissues in hamsters and that reinfection is not a factor in the development of the inflammatory processes, although it may aggravate it, possibly due to an increase in tissue parasitism, which might induce autoimmune mechanisms. Reinfection did not induce selection of subpopulations in the tissue or in the blood.