Colonic mucin composition in primates. Selective alterations associated with spontaneous colitis in the cotton-top tamarin

Abstract

Heterogeneity of colonic mucin glycoprotein was examined in rectal mucosal biopsy specimens from a variety of primate species (Saguinus oedipus, n = 18; Macaca mulatta, n = 2; Macaca fascicularis, n = 2; Aotus trivirgatus, n = 2; Saimiri sciureus, n = 2; and Callithrix jacchus, n = 2). After initial separation of radiolabeled mucin and nonmucin glycoproteins solubilized from mucosal biopsy specimens, at least five labeled mucin components were found in monkey rectal mucosa in contrast to the six mucin fractions observed in the human colon. Although primates consistently lacked the earliest eluting component present in human colonic mucin, other mucin components cochromatographed with comparable fractions previously identified in human colonic biopsy specimens. The relative proportions of each fraction were consistent throughout all species except the cotton-top tamarin (S. oedipus), an animal that develops a chronic colitis. The cotton-top tamarin was found to have a markedly reduced amount of one mucin component (IV) in a manner analogous to the reduction in a human mucin fraction previously noted in patients with ulcerative colitis. Sequential evaluation of mucin profiles in cotton-top tamarins (n = 12) treated with sulfasalazine (50 mg/kg X day) or placebo in a 10-wk double-blind crossover study demonstrated the persistence of the selective reduction in tamarin species IV unrelated to disease activity. In contrast, the relative amount of tamarin mucin III was greater in association with increased disease activity than that observed in association with reduced disease activity (46% +/- 11% total mucin vs. 19% +/- 7% total mucin posttreatment).