Evidence that colitis is initiated by environmental stress and sustained by fecal factors in the cotton-top tamarin (Saguinus oedipus)

Parallel changes in spontaneously occurring inflammation in colonic Thiry-V ella loops and the in-line colon of cotton-top tamarins were studied in a c olitis-inducing environment at 8 and 15 months following surgical preparati on of the loops. Gross disease severity and numbers of inflammatory/immune cells per unit area of lamina propria in histological sections from endosco pic biopsies were analyzed. Cell counts and severity of colitis declined ov er time in the Thiry-Villa loops while the disease followed its characteris tic course in the remaining large bowel and in the colons of controls. Perf usion of the loops with the animals' feces increased the density of the cel lular infiltrate in the lamina propria in parallel with increased severity of inflammation. Electron micrographs of the colonic mucosa showed invasion by microorganisms. The predominant microorganism had characteristics of He licobacter sp. The results implicate the fecal stream as a factor in the pe rsistence of colitis in the tamarin model. Nevertheless, fecal factors appe ar not to be the primary trigger, as evidenced by findings that the disease is not expressed in wild-living tamarins and that it enters remission when affected animals are transferred to natural conditions from a colitis-indu cing environment. Both an adverse environment and the fecal contents appear to be required for expression of the disease.