An investigation of the role of intraluminal proteolytic enzymes and intracellular enzyme inhibitors in ulcerative colitis.

The output of trypsin and chymotrypsin was determined in 26 patients with ulcerative colitis and 8 with polyposis coli, each of whom had undergone total colectomy and ileostomy. Measurements were made in each subject over periods ranging from 3 to 8 days on a standard diet. The output of each enzyme was lower in the group with ulcerative colitis, but serial post-operative measurements suggested that this was due to the relatively poorer nutritional status of patients in this group, and no consistent difference was apparent between individuals in both groups whose ileostomy had been established more than one year before the measurements were made. The activity of proteolytic enzyme inhibitors was determined in 20 samples of colonic mucosa obtained from patients with ulcerative colitis and 18 samples of histologically normal colonic mucosa from patients with carcinoma of the colon. Higher levels of trypsin inhibitor were found in mucosa affected by ulcerative colitis, there being an apparent correlation between inhibitor level and the severity of the lesion as assessed by the extent of ulceration, necrosis and haemorrhage. The data do not support the view that a high intraluminal concentration of pancreatic proteases, or a reduced cellular protection against their action, are primary or secondary causes of mucosal damage in ulcerative colitis.