Increased expression of heat shock protein 70 on airway cells in asthma and chronic bronchitis

Heat shock proteins (HSPs) appear to be involved in inflammation. Because asthma is an inflammatory disease, HSPs may be expressed. We studied the expression of HSP-70 by immunohistochemistry using the alkaline-phosphatase anti-alkaline phosphatase technique on epithelial cells and alveolar macrophages (AMs) from 19 patients with asthma, eight patients with chronic bronchitis (CB), and 13 control subjects and in bronchial biopsies from 15 asthmatics, 15 CB patients, and nine control subjects. The specificity of the antibody was confirmed by Western blotting on heated AM. The specificity of the immunostaining was confirmed by inhibition experiments. The expression of HSPs in the asthmatics in comparison with the CB patients and control subjects was significantly increased on epithelial cells (P < 0.002 and P < 0.007, respectively) and AMs (P < 0.0004 and P < 0.0002, respectively) and was significantly correlated with the severity of asthma (P < 0.005 for AMs) and the percentage of eosinophils in bronchoalveolar lavage fluid (P < 0.004). In biopsies from the asthmatics but not from the CB patients or control subjects, a positive staining for HSP-70 was observed on epithelium, mononuclear cells, and basement membrane and was correlated with the severity of asthma (P < 0.0005, P < 0.002, and P < 0.007, respectively). This study demonstrates that bronchial inflammation in asthma but not in CB may be linked to the production of HSPs.