Antileukoprotease inhibits stratum corneum chymotryptic enzyme. Evidence for a regulative function in desquamation

The stratum corneum chymotryptic enzyme (SCCE) has been previously purified from human stratum corneum and resembles a chymotryptic serine endopeptidase involved in physiological detachment of corneocytes from human stratum corneum. From human stratum corneum two inhibitory activities of SCCE could be extracted. These were due to serine protease inhibitors already known to be present in human epidermis, antileukoprotease (secretory leukocyte protease inhibitor) and elafin (skin-derived antileukoprotease). The Inhibition of SCCE by antileukoprotease shows a hyperbolic, mixed type inhibition with an equilibrium dissociation constant of 63 n. Antileukoprotease also inhibits detachment of corneocytes from human plantar callus in vitro almost completely (>96%). In addition, elafin was shown to be a weak inhibitor for SCCE activity, and elafin significantly reduces the shedding of corneocytes. Thus, antileukoprotease, which is known to be produced by human keratinocytes, is likely to be the major physiological inhibitor of SCCE in the epidermis. It seems to be involved in the regulation of desquamation under physiological and pathophysiological conditions.