Background: Neutrophil releases several mediators during inflammation, including neutrophil elastase (NE) that impairs bronchial epithelial function. The stress response and stress proteins protect cells against a variety of cytotoxic conditions. Accordingly, we tested the hypothesis that bronchial epithelial heat shock protein (Hsp-70) would protect a NE-induced cell injury.
Methods: Bronchial epithelial cells (BECs) obtained by bronchial brushing under bronchoscopy were cultured and used for experiments. Expression of Hsp-70 in BECs was confirmed by Western blot and flowcytometric analysis. To test Hsp-70 in BECs, induction of Hsp-70 protein into BECs was carried out by liposome-based delivery system. Introduction of Hsp-70 into BECs were examined by direct fluorescence microscope examination and flowcytometric analysis. NE-induced cytotoxicity was evaluated by cell culture supernatant LDH assay and cell detachment assay.
Results: Higher expressions of Hsp-70 were observed in BECs, which were induced by sodium arsenite. Over expression of Hsp-70 in BECs reduced NE-induced cell injury. Introduction of Hsp-70 protein into BECs by liposomal delivery decreased LDH release, and inhibited necrosis and apoptosis of the cells by NE as compared to untreated control.
Conclusion: These data suggested that Hsp-70 in BECs may inhibit NE-induced airway epithelial damage. Liposomal delivery of Hsp-70 into BECs may be a possible means of protecting bronchial epithelium against inflammatory airway diseases including acute and chronic bronchitis.