ELASTASE-TYPE ENDOPEPTIDASE OF FIBROBLAST S - EFFECT OF METALLOPROTEASE INHIBITORS

Human skin fibroblasts produce in culture an elastase-type metalloendo peptidase which can hydrolyze synthetic elastase-substrate as Suc ala( 3) pNA and degrade also elastic fibers when injected in the dermis or deposited on cryostat-skin sections [3-8]. Here we describe further ch aracterization of this enzyme activity using metallo-enzyme inhibitors as well as specific inhibitors of known Zn-endopeptidases such as ang iotensin converting enzyme and enkephalinase. Among the metal complexi ng agents tested only EDTA and o-phenanthrolin could inhibit the elast ase-type activity of fibroblasts, other Known metal complexing substan ces capable of reacting with Zn (2,2' dipyridyl, diethyl dithiocarbama te and other metal chelators) were ineffective as was also lisinopril, an ACE-inhibitor [13]. Phosphoramidon and retrothiorphan, specific en kephalinase inhibitors [12] did strongly inhibit the elastase type act ivity of human skin fibroblasts (IC50 10(8)M). Ethanol at conc-s used to dissolve organic, water insoluble inhibitors (50-100 mu l/ml) stron gly inhibited the enzyme. It appears that the metal prosthetic group o f fibroblast elastase (presumably, Zn) is not directly accessible to s everal of the low M. Wt complexing agents. The efficiency of enkephali nase inhibitors suggests a possible relationship between this enzyme a nd fibroblast-elastase.