Imprinting of the COPD airway epithelium for dedifferentiation and mesenchymal transition.

In chronic obstructive pulmonary disease (COPD), epithelial changes and subepithelial fibrosis are salient features in conducting airways. Epithelial-to-mesenchymal transition (EMT) has been recently suggested in COPD, but the mechanisms and relationship to peribronchial fibrosis remain unclear. We hypothesised that de-differentiation of the COPD respiratory epithelium through EMT could participate in airway fibrosis and thereby, in airway obstruction.

Polymeric immunoglobulin receptor down-regulation in chronic obstructive pulmonary disease. Persistence in the cultured epithelium and role of transforming growth factor-β.

Rationale: The generation of protective secretory IgA relies on the epithelial polymeric immunoglobulin receptor (pIgR). pIgR expression is reduced in chronic obstructive pulmonary disease (COPD), but correlation to disease severity and underlying mechanisms remains unknown.

Objectives: To address the hypothesis that pIgR down-regulation in COPD concerns severe disease in relation to aberrant programming of the bronchial epithelium.