Mast cell tryptase and chymase - mediators in skin diseases

Upon stimulation, mast cells may release the serin proteases tryptase and c hymase from their granules. Depending on the expression of these proteases, three mast cell phenotypes are distinguished containing either tryptase al one (MCT), tryptase and chymase (MCTC) or rarely exclusively chymase (MCC). In vitro mast cell proteases have been shown to cleave structural and func tional proteins, to activate or inactivate pro-inflammatory cytokines and p eptides, to stimulate directly a variety of cell types and to activate othe r proteolytic systems. Changes of the number and localization of MCT and MC TC, extracellularly located tryptase and chymase in the tissue as well as e levated tryptase levels in body fluids suggest a role of these enzymes in t he pathogenesis of allergic and other inflammatory skin conditions. The pha rmacologic inhibition of the enzymatic activity of mast cell proteases may provide a future therapeutic approach for these disorders.