The possible role of hematopoietic cell kinase in the pathophysiology of COPD

Background: Hematopoietic cell kinase (Hck) is a myeloid cell-specific tyrosine kinase, which is known to induce neutrophil infiltration to the lungs. Although the overexpression of Hck causes emphysema-like histologic changes in mice, its expression and activity in patients with COPD are unclear. Method: The aim of this study was to clarify the expression and activity of Hck in neutrophils from COPD patients, and to investigate the association between the degree of Hck expression and the lung function parameters in COPD patients. Peripheral blood neutrophils were isolated from 22 patients with COPD and 9 healthy subjects (HSs). The protein levels of Hck and phosphorylated Hck were assessed, and the correlation with various background characteristics was evaluated. Results: The Hck protein level was significantly higher in neutrophils from COPD patients compared with HSs (COPD patients, 1.094; HSs, 0.801; p < 0.05). A significant positive correlation was observed between the protein level of Hck and the surface expression of the integrin molecule CD-11b (r = 0.540; p < 0.01) or CXC chemokine receptor-1 (r = 0.432; p < 0.05). In contrast, there was no difference in the phosphorylation of the Hck protein between COPD patients and HSs. Conclusion: The Hck protein level in peripheral blood neutrophils was increased in COPD patients, suggesting that Hck might have an important role in the neutrophil function and play a key role in the pathophysiology of COPD.