Chymotrypsin-like enzyme secretion is stimulated in cultured epithelial cells during proliferation and in response to Actinobacillus actinomycetemcomitans.

A chymotrypsin-like enzyme was partially purified from culture medium of epithelial cells of human skin, human gingiva and porcine periodontal ligament by aprotinin-affinity chromatography. The enzyme levels from all three cell types were low in quiescent cultures but increased markedly when the cells were allowed to proliferate. The biphasic elution profile of the enzyme from the affinity column closely matched that of alpha-chymotrypsin and the protein comigrated with it on polyacrylamide gels at 27,000 ML. Synthetic substrate tests of purified fractions showed strong chymotrypsin-like but no trypsin-like or elastase-like activity. Inhibition of protease activity and pH optimum in the range of 7.5-8.0 were consistent with chymotrypsin-like enzymes. Secreted activity was found to be significantly increased by phorbol myristate acetate treatment in a time-course that differed from that of elastase-like activity. Keratinocyte growth factor and epidermal growth factor but not transforming growth factor-beta increased the chymotrypsin-like activity in a concentration-dependent manner. The enzyme secretion by epithelial cells was strongly elevated by exposure to 5 of 6 Actinobacillus actinomycetemcomitans strains isolated from plaque samples of juvenile periodontitis patients. These results indicate that chymotrypsin-like enzymes are secreted by proliferative phenotypes of normal epithelial cells. This enzyme may, therefore, play a role in epithelial physiology and in cell response to certain pathogenic bacteria.