Study on polymorphonucleocytal elastase-alpha 1-protease inhibitor complex in bronchoalveolar lavage fluid (BALF)

Proteases and lung injury

OBJECTIVE

Acute respiratory distress syndrome (ARDS) represents an inflammatory process that is initiated by diverse systemic and/or pulmonary insults, resulting in a clinical syndrome of severe respiratory distress and refractory hypoxemia. Neutrophils and their cytotoxic products, including oxidants and proteases, such as elastase, have been implicated as playing a key role in the pathophysiology of ARDS. This article reviews some of the physiologic actions of proteases, specifically elastase, the evidence for neutrophil elastase involvement in ARDS, and the potential therapeutic use of neutrophil elastase inhibitors in lung injury.

DATA SOURCE

A review of published literature (original articles and reviews) in English from 1965 to 2002.

CONCLUSION

Although the data support a key role for neutrophil elastase in the pathogenesis of ARDS, further study is needed to fully define the actions of neutrophil elastase, and how these actions affect host functions, before we can exploit this knowledge for therapeutic benefit.

Effects of neutrophil elastase inhibitor on bleomycin-induced pulmonary fibrosis in mice

Neutrophils play an important role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). To elucidate the possible involvement of neutrophil elastase (NE) in pulmonary fibrosis, we investigated the efficacy of a new specific NE inhibitor (ONO-5046 Na) in a murine model of human IPF, bleomycin-induced pulmonary fibrosis. Bronchoalveolar lavage (BAL) and histopathological analysis were performed on bleomycin-treated mice (group A), bleomycin and ONO-5046 Na-treated mice (group B), and saline control groups at 1, 15, and 29 d after the end of bleomycin treatment. At 29 d, multifocal fibrosis was observed in group A, whereas no fibrotic regions were observed in group B. Interleukin-1 beta and macrophage inflammatory protein-2 mRNA levels in BAL cells on day 1, and platelet-derived growth factor-A and insulin-like growth factor-1 mRNA levels on days 1 and 15, were significantly lower in group B than in group A. Thus, we demonstrated an inhibitory effect of ONO-5046. Na on pulmonary fibrosis in mice, indicating the involvement of NE in the pathogenesis of pulmonary fibrosis. We propose that this effect might be related to suppressed expression of particular cytokines in alveolar macrophages and that this specific NE inhibitor could be a novel therapeutic agent for IPF.

Plasma and synovial fluid levels of granulocytal elastase-alpha-1-protease inhibitor complex in patients with rheumatoid arthritis

Plasma and synovial fluid levels and granulocytal elastase-alpha-1-protease inhibitor complex (EIC) in patients with rheumatoid arthritis (RA) were measured by enzyme-linked immunoassay and the results compared with those in patients with osteoarthrosis (OA). It was found that the plasma and synovial fluid levels of EIC in RA patients were higher than those in OA patients. There was a positive correlation between plasma EIC level in RA patients in Lansbury's index score of disease activity, as this tends to be higher when titer of RAHA in the plasma is high. The level of EIC in the synovial fluids correlated positively with granulocyte count and alpha-1-protease inhibitor (alpha-1-PI) level, and this, too, tends to be higher when titer of RAHA in synovial fluid is high. The results suggested that the level of EIC in the plasma or synovial fluids can be a good marker for the systemic or localized activation of the granulocytes and that IgM rheumatoid factor (IgMRF) is involved in the mechanism of the release of elastase.