Evaluation of Novel Serine Protease Inhibitors to Ameliorate Cockroach‐Induced Airway Inflammation and Cell Damage

Abstract

Exposure to cockroach can lead to allergic airway inflammation. Serine proteases in cockroach extract (CRE) have been demonstrated to affect airway epithelial cells via activation of PARs (protease‐activated receptors) and via release of inflammatory cytokines (GM‐CSF, IL‐8 and IL‐6). The serine protease inhibitor gabexate mesilate (GM) has been shown to attenuate both cockroach‐induced bronchial cell damage and the release of inflammatory cytokines.The aim of this study was to examine a number of natural peptides, derived from amphibian skin secretions, shown to be trypsin‐like protease inhibitors in an initial screen.Trypsin‐like protease activity present in German cockroach (Blattella germanica) extract was assayed in the presence or absence of candidate protease inhibitors using a fluorogenic substrate based assay. Cell viability was determined using the RealTime‐Glo assay (Promega). Inflammatory markers were assayed by ELISA.Four natural peptides were tested versus CRE tryptic activity. A pIC50 of −8.2, −9.1, −5.5 and −7.5 was calculated for QUB‐1812, QUB‐1813, QUB‐1913 and QUB‐2136 respectively. The two inhibitors that displayed greatest potency (QUB‐1813 and QUB‐1812) were further evaluated and shown to rescue CRE‐induced cytotoxicity and inflammation; to a greater extent than elicited by GM.We have identified two novel natural peptides that potently inhibit the abundant serine trypsin‐like protease activity present in cockroach preparations. Moreover, these peptides protect airway epithelial cells from the toxic and inflammatory effects normally induced by CRE. We will now proceed to test these peptides in advanced models to gain insight as to their potential clinical utility.Support or Funding InformationBREATH (Border and REgions Airways Training Hub) is funded by the EU's INTERREG Va programme managed by the Special EU Programmes Body (SEUPB).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.