Cockroach Allergen Proteinases Regulate Proteinase‐Activated Receptor‐1 (PAR1) Signalling

Abstract

ObjectiveTo assess potential pro‐fibrotic PAR1 MAPKinase signaling by cockroach allergen‐derived trypsin‐like proteinases.MethodsCockroach allergen‐derived trypsin‐like enzymes, known to cause lung inflammation, were identified with serine proteinase activity‐based probes (ABP). Enzymes were purified (ion‐exchange chromatography) and analyzed for their ABP reactivity & substrate‐inhibitor kinetic profiles. Each enzyme was evaluated for causing calcium (Fluo‐4) and MAPKinase signaling (western blot) in PAR1‐expressing KNRK cells. Additionally, the cleavage‐internalization of fluorescently‐tagged PAR1 constructs was monitored as an index of receptor activation.ResultsCockroach allergen contained three ABP‐labeled 20–26 kDa MW proteinases with distinct enzyme kinetics. The allergen‐derived enzymes activated PAR1 MAPK and calcium signaling, but with distinct concentration‐effect kinetics. PAR1 cleavageinternalization caused by the allergen proteinases was similar to that caused by trypsin, but NOT thrombin.ConclusionsCockroach allergen contains three different trypsin‐like proteinases that can activate “biased” PAR1 pro‐fibrogenic MAPKinase (but not Ca++) signaling pathways. We suggest that the allergen proteinases can act as pro‐fibrotic factors in the setting of airway allergic inflammation and asthma. Support: CIHR, NIH USA and Lung Assn. of AB & NWT