Immunology, genetics and microbiota in the COPD pathophysiology: potential scope for patient stratification

Chronic obstructive pulmonary disease (COPD) is characterized by sustained inflammation of the airways, leading to destruction of lung tissue and declining pulmonary function. Although smoking is the most obvious risk factor for COPD, only about 20% of smokers develop COPD and smoking cessation does not reverse progression of COPD, indicating that while smoking is an important cause or initiating factor, it is not the only driver of ongoing chronic inflammation and disease progression in COPD patients. We hypothesize that smoking-induced changes in lung microbiota, epithelial integrity and epigenetic control of gene expression result in autoantigen induction and perturbed immune regulation in genetically vunerable individuals. In our view, COPD patients may be stratified according to their immunological and inflammatory status related to specific changes in the lung microbiota (innate and adaptive immunity), presence of autoantigens (adaptive immunity: Th1-B-cell axis) and epigenetic modifications (inflammation and structural changes).