Antimicrobial peptides in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a frequent, chronic lung disease associated with significant morbidity and mortality. Respiratory infections play a central role in the disease, not only during exacerbations but also in the stable phase of the disease. These infections contribute to the development and progression of the disease, and many patients are colonized by respiratory pathogens. The pathogens are present in the lung, despite the presence of large numbers of neutrophils, especially during acute states of inflammation. These neutrophils may release antimicrobial peptides (AMPs) that may not only serve to kill these pathogens but also contribute to tissue injury and inflammation. In addition, smoke affects many elements of the host immune system, including the expression of epithelial AMPs. Furthermore, the activity of AMPs may be decreased in the purulent airway secretions often present in COPD patients. Possibly vitamin D treatment may contribute to restoring local AMP deficiency and thereby to reducing exacerbations in COPD.