CAMP and chronic obstructive pulmonary disease: The benefits of vitamin D relevant to COPD risk and severity include increases in the production of the antimicrobial peptide cathelicidin (LL-37) and downregulation of proinflammatory cytokines and effects on airway remodeling, together with inhibition of the production of several proinflammatory cytokines and suppression of the T-cell helper Th1 and Th17 responses thought to aggravate the pathogenesis of COPD.