Peptidase inhibitor 3 (PI3)

Peptidase inhibitor 3 (PI3), also known as elafin, is a small, secreted protein that functions as a serine protease inhibitor predominantly targeting neutrophil elastase and to a lesser extent pancreatic elastase. It is mainly expressed in epithelial tissues, especially at mucosal surfaces and the skin, and plays a critical role in protecting host tissues from excessive proteolytic damage during inflammation. Besides its antiprotease activity, PI3/elafin also exhibits antimicrobial properties and modulates immune responses, contributing to host defense mechanisms. Genetic polymorphisms in PI3 are associated with disease susceptibility, notably in acute respiratory distress syndrome (ARDS), and decreased levels or defective forms have been implicated in greater tissue injury in inflammatory conditions. PI3/elafin is also under investigation as a clinical biomarker, particularly for skin graft-versus-host disease and possibly other inflammatory states[1][2][3][5].

Other names

ElafinSkin-derived antileukoproteinase (SKALP)WAP four-disulfide core domain protein 14 (WFDC14)Elastase-specific inhibitorPre-elafinTrappin-2CementoinProtease inhibitor WAP3

Direct inhibition of serine proteases, especially neutrophil elastase and, to a lesser extent, pancreatic elastase. Some inhibitory activity on certain receptor channels (e.g., weak inhibition of Kv11.1/KCNH2/ERG1 and TRPV1)