Alpha-1 antitrypsin genotypes and associated inhibitory activity towards neutrophil serine proteinases, in vitro

Abstract

Active neutrophil serine proteases (NSPs):human neutrophil elastase (HNE),proteinase 3 (PR3) and cathepsin G (CG) released during inflammation are involved in the degradation of elastin fibers in the lungs. Imbalance between HNE and alpha-1 antitrypsin (AAT) plays a key role in COPD development. AAT favors HNE, thus PR3 and CG might exert their destructive effect in lungs much longer and play more important role. Material & Methods: Sera from 110 healthy and respiratory (COPD/pneumothorax/ granulomatosis with polyangiitis) subjects with PI*MM, MZ, ZZ and FM AAT phenotype were s analyzed for free NSPs level by ELISA; in vivo inhibitory activity towards NSPs by fluorescence resonance energy transfer (FRET) method. Results: The concentration of free HNE was the lowest and CG level was the highest in comparison to other proteases irrespective to subject AAT phenotype and health status. Overall mean serum level of free proteases was 0.06±0.05 for HNE, 5.58±4.52 for PR3 and 90.09±60.60 ng/ml for CG. Regression analysis confirmed the trend towards increasing HNE, PR3 and CG activity in MM 0.8).PR3 activity was significantly higher (p=0.0041) in ZZ COPD patients (275±145 pM] than in MM controls (65±34 pM), likewise CG activity in ZZ COPD patients (222±132 pM] vs. MM controls (101±82 pM) (p=0.0434). Conclusions: Concentration of free proteases in serum corresponded with AAT affinity towards respective NSPs but not with AAT phenotype or patient9s clinical status. However, serum AAT inhibitory activity towards HNE, PR3 and CG was directly related with AAT phenotype and clinical status of patients.