Antimicrobial peptides in COPD

Background: Antimicrobial peptides (AMP) are part of the epithelial innate immune defense. The role of AMPs in chronic obstructive pulmonary disease (COPD) with recurrent exacerbations is not known.

Methods: We analyzed the expression of human-beta-defensis 1–3, psoriasin and RNase 7 in pulmonary epithelia and bronchoalveolar-lavage (BAL)-fluid from healthy controls and patients at different stages of COPD. Clinical and lung function parameters were collected.

Results: Thirty-two patients at different stages of COPD, 16 with acute exacerbations and 10 healthy controls were enrolled in the study. In bronchial biopsy samples, but not in BAL-fluid, we observed a significant overexpression of human-beta-defensin-1 (hBD-1) in patients with COPD compared to healthy controls. Detection of microbial pathogens in BAL specimen was associated with a significantly higher mRNA expression of Psoriasin and RNase7 regardless of viral or bacterial infection. In patients with COPD the level of AMP expression was not correlated with the level of airway obstruction/severity of COPD.

Conclusion: In COPD, upregulation of hBD-1 in the pulmonary epithelium could be a marker of chronic inflammation. Expression of RNase7 and Psoriasin by BAL-derived cells is unspecifically related to with viral or bacterial infection/colonisation. The upregulation of AMPs seems independent of the level of disease in COPD.