Mucosal enterokinase activity in cow's milk protein sensitive enteropathy

Enterokinase has a critical role in initiating proteolytic digestion by hydrolysing the conversion of pancreatic trypsinogen into trypsin. The enzyme is synthesised by enterocytes of the proximal small intestine and initially incorporated into the brush border from where it is released into the intestinal lumen by the action of pancreatic secretions. The aim of the study was to analyse enterokinase activity in the duodenal mucosa of infants with diarrhoeal disease including cow's milk protein-sensitive enteropathy. Our observations show that the mean depletion of enterokinase was only 17% compared to 60-80% for other brush border enzymes like disaccharidases, peptidases and alkaline phosphatases in infants with diarrhoea. This suggests that enterokinase activity in the small bowel enteropathies may be dependent not only on the degree of mucosal damage specifically but also on the extent of damage to the goblet cell population where the enzyme is synthesised. Thus the enterokinase activity was reduced in acute and chronic diarrhoea with marked mucosal damage where significant reduction of goblet cell population was evident but the enzyme was relatively little affected when the mucosa was damaged mildly.