Analysis of Airway Epithelial Cell Autoantigens Recognized by IgG Autoantibodies from Patients with Severe Asthma and Chronic Obstructive Pulmonary Disease

Abstract

Background: The presence of circulating autoantibodies to airway epithelial cells has been reported in patients with asthma and chronic obstructive pulmonary disease (COPD). Objective: To evaluate the possibility of a common autoantigen associated with both asthma and COPD, we analyzed airway epithelial cell autoantigens recognized by circulating IgG autoantibodies from patients with severe asthma and COPD. Method: IgG autoantibodies to human airway epithelial cells (A549) were examined in serum samples from patients with severe asthma and COPD by immunoblot analysis. Result: A 54-kDa airway epithelial autoantigen was commonly recognized by circulating IgG antibodies from patients with severe asthma and COPD. The 54-kDa auto-antigen was identified as cytokeratin 8 protein by mass spectrometry. IgG autoantibodies to recombinant human cytokeratin 8 protein were detected in serum samples from 5 (31.3%) of the 16 patients with severe asthma, 4 (26.6%) of 15 patients with COPD, 1 (7.7%) of 13 patients with mild-to-moderate asthma, and 1 (7.7%) of 13 healthy controls (P=0.056). Conclusion: In this study, we identified cytokeratin 8 as an airway epithelial autoantigen associated with both severe asthma and COPD. Further studies are needed to determine the role of this autoantigen in the pathogenesis of severe asthma and COPD.