THE ROLE OF PROTEASES IN STRATUM-CORNEUM - INVOLVEMENT IN STRATUM-CORNEUM DESQUAMATION

The effects of protease inhibitors on cell dissociation were studied i n vitro in order to examine the involvement of proteases in stratum co rneum desquamation. Stratum corneum sheet (peeled from human backs aft er sunburn) was incubated in a detergent mixture containing 8 mM N,N-d imethyldodecylamine oxide, 2 mM sodium lauryl sulphate and 60 mu g/ml kanamycin with or without protease inhibitors, and the number of relea sed cells was counted after incubation for 48 h. Cell dissociation was inhibited strongly by antipain or aprotinin, but not at all by -trans carboxyoxiran-2-carbonyl)-L-leucyl]-agmatin, N-ethylmaleimide or pepst atin, which suggests that only serine proteases are associated with de squamation. Furthermore, leupeptin and chymostatin each reduced cell d issociation about half as effectively as aprotinin or antipain, while a mixture of leupeptin and chymostatin prevented stratum corneum disso ciation as potently as antipain or aprotinin. In addition, the activit y of chymotrypsin-like protease in scaly skin was higher than that in normal skin, as we have previously found for trypsin-like protease. Th ese results suggest that both trypsin-like and chymotrypsin-like serin e proteases are involved in stratum corneum desquamation.