Elevation of Plasma Truncated Elastase α1-Proteinase Inhibitor Complexes in Patients with Inflammatory Lung Diseases

Abstract

Human neutrophil elastase plays an important role in the development of several inflammatory lung diseases; however, there have been relatively few investigations using plasma samples. In this report, we describe alterations in the plasma elastase:alpha 1-PI complex in patients with chronic obstructive pulmonary disease (COPD) (15 cases), COPD with infection (8), diffuse panbronchiolitis (DPB) (8), bronchiectasis (9), pneumonia (10), and the adult respiratory distress syndrome (ARDS) (14), and in 15 normal volunteers. The elastase:alpha 1-PI complex concentration was determined by an enzyme-linked immunosorbent assay. Western immunoblot analysis of the elastase:alpha 1-PI complex was also performed. Plasma elastase:alpha 1-PI complex was also performed. Plasma elastase:alpha 1-PI complex levels in patients with COPD with infection (504 micrograms/L +/- 93 micrograms/L) were significantly higher, as compared with those with COPD but without infection (118 micrograms/L +/- 9 micrograms/L) and normal volunteers (122 micrograms/L +/- 4 micrograms/L). Increased complex concentrations were also found in patients with DPB and bronchiectasis (643 micrograms/L +/- 222 micrograms/L and 558 micrograms/L +/- 198 micrograms/L, respectively) as compared with normal volunteers. Increased complex concentrations were also found in patients with pneumonia and ARDS (450 micrograms/L +/- 101 micrograms/L and 1,400 micrograms/L +/- 438 micrograms/L, respectively). Western immunoblot analysis using anti-alpha 1-PI antibody and antineutrophil elastase antibody showed two types of elastase:alpha 1-PI complexes, one with a molecular weight of 60,000 daltons (60 kilodaltons [KD]) and the other at 50,000 daltons (50 KD). Although the native 80-KD elastase:alpha 1-PI complex was detected in bronchoalveolar lavage fluid, it was not found in plasma. In summary, these results demonstrated that levels of the truncated complex were increased in patients with various inflammatory lung diseases. This truncated form may play an important role in the pathophysiology of inflammatory processes.