Effect of proteinase inhibitors having anti-inflammatory activity on gelatinase, elastase and cathepsin G isolated from rat polymorphonuclear leukocytes.

Gelatinase, elastase and cathepsin G isolated from the granule extract of rat polymorphonuclear leukocytes (PMNs) had similar properties to the enzymes of human PMNs already reported. Effect of proteinase inhibitors on these neutral proteinases isolated from rat PMNs was studied. Epsilon-Amino-n-caproic acid n-hexyl ester, a proteinase inhibitor having anti-inflammatory activity, inhibited cathepsin G, whereas elastase was activated by the inhibitor. On the other hand, leupeptin, L-1-tosylamide-2-phenylethyl chloromethyl ketone and N-alpha-p-tosyl-L-lysine chloromethyl ketone, which had been reported as anti-inflammatory inhibitors, had no inhibitory effect on these neutral proteinases. These results suggest that proteinase inhibitors reported as anti-inflammatory agents exert their anti-inflammatory actions not by direct inhibition of the neutral proteinases released from PMNs, but by other effects such as suppression of the infiltration of PMNs into inflammatory locus.