[Correlations between chymase activity, levels of tryptase, and eotaxin in the sputum of patients with chronic obstructive pulmonary disease and their clinical implications].

OBJECTIVE

To investigate the correlations between chymase activity, levels of tryptase, interleukin-8 (IL-8), eotaxin, neutrophil and eosinophil numbers in the sputum of elderly patients with chronic obstructive pulmonary disease (COPD) and their clinical implications.

METHODS

A total of 73 elderly patients with COPD (21 severe, 21 moderate and 31 mild) were recruited into the study. IL-8 and eotaxin levels were detected with Sandwich enzyme-linked immunosorbent assay (ELISA) procedures and tryptase levels were measured with antibody against tryptase with Uni CAP system. Chymase activity was determined spectrophotometrically (410 nm) by the rate of hydrolysis of 0.7 mmol/L N-succinyl-L-Ala-L-Ala-L-Pro-L-Phe-p-nitroanilide (SAAPP) in NaCl 1.5 mol/L and Tris 0.3 mol/L The specific activity of chymase was expressed as mU/ml. Actions of protease inhibitors on chymase activities were also examined with enzyme assay.

RESULTS

(1) At acute attack stage, the sputum levels of tryptase of patients with severe, moderate and mild COPD were 284.0, 215.0 and 59.5 ng/L, respectively. The sputum levels of tryptase in the severe and moderate patients were greater than that in mild patients (P <0.01). The tryptase levels in the sputum of all patients were significantly decreased following treatment( 151.0, 92.0, 3.3 ng/L respectively; P <0. 01). At acute attack stage, the sputum levels of IL-8 and eotaxin were 1 299. 8,454. 9,78.7 ng/L; 22.7, 15.1, 7.4 ng/L, respectively. Severe and moderate-patients were greater than that of patients at mild stages. At convalescent stage,the sputum levels of IL-8 and eotaxin were 1 037. 5,326.6, 67.9 ng/L; 7.9, 6.3, 6.8 ng/L, respectively. The IL-8 and eotaxin levels in the sputum of severe and moderate patients were significantly decreased following treatment (P < 0.01). (2) The specific chymase activities of severe and moderate patients were higher than mild patients. Native protease inhibitors alpha1-antitrypsin (alpha1-AT) and soy bean trypsin inhibitor (SBTI) inhibited 83% and 89% enzymatic chymase activity, respectively. (3) The numbers of neutrophils and eosinophils in sputum were increased in patients with COPD at the acute stage compared with the mild convalescent stage. At all remission stages, the elevated numbers of cells were significantly reduced. (4) At acute attack stage of patients with COPD, there were correlations between the sputum levels of tryptase, IL-8, eotaxin, neutrophils and eosinophils; and there were correlations between the sputum levels of tryptase, chymase and neutrophils.

CONCLUSION

COPD is not merely a neutrophil associated disease, but mast cells, eosinophils and their released mediators also actively contribute to the pathogenesis of the disease.