The Role of Proteolytic Enzymes in Inflammation: Measurement of Esterolytic Activity of Protease in Croton Oil-Induced Inflammation

Abstract

In recent years, many investigators have reported that during the inflammatory response, numerous proteolytic and hydrolytic enzymes were activated. It was noted that in the early stage of inflammation, various zymogens, such as Hageman factor, plasminogen, kallikreinogen, and the first component of complement Cl, were activated, and these activated enzymes produced various chemical mediators, such as histamin, serotonin, anaphylatoxin, kinin, etc. In this study, to determine the role played by proteolytic enzymes in inflammation, the esterolytic activities of protease in nonspecific inflammation induced by croton oil were measured.
The increased TAME esterolytic activities of the serum, exudate and inflammatory tissue were obtained. Because of no increased activities of inhibitors and available TAME esterase, the increased TAME esterolytic activity might be due to the activation of zymogens. In addition, these TAME esterases were inhibited by some synthetic inhibitors of trypsin, plasmin, plasma kallikrein, thrombin and Cl-esterase in vitro. It was found that carboxyethylphenyl esters of trans-4-aminomethylcyclohexanecarboxylic acid (AMCHA-CEP) and r-guanidinocaproic acid (ε-GCA-CEP) exhibited an extensive inhibitory effect, not only on TAME, but also on the ATME esterolytic activities of exudate and serum. The gel filtration of the body fluids on Sephadex G-200, three peaks of TAME esterase, named peak 1,2,3, respectively, were obtained. The differences of the gel filtration pattern of TAME esterase through a Sephadex G-200 column between the exudate and serum were examined. Peak 2 and peak 1 of TAME esterase obtained by gel filtration of exudate on the Sephadex G-200 column (possibly involved Hageman factor, PF/dil and kallikrein) were thought to be playing a role in enhancing the permeability of the vessel walls, while these esterase activities were strongly inhibited by ε-GCA-CEP or AMCHA-CEP.
Local administration of ε-GCA-CEP and AMCHA-CEP into the granuloma pouch resulted in a reduced volume of inflammatory exudate, and a dose-dependent relationship in the anti-inflammatory effect of ε-GCA-CEP was observed. It was also disclosed that kinin-like substances were responsible for the reduced effect of inflammatory exudate due to inhibition of protease activity.