Understanding novel mechanisms of microbial pathogenesis in chronic lung disease: implications for new therapeutic targets

Inhaled corticosteroids (ICS) are important in reducing exacerbation frequency associated with chronic obstructive pulmonary disease (COPD). However, little is known about the risk of associated infections. In a post hoc analysis of the TOwards a Revolution in COPD Health (TORCH) study, we analysed and identified potential risk factors for adverse event reports of pneumonia in this randomised, double-blind trial comparing twice-daily inhaled salmeterol (SAL) 50 microg, fluticasone propionate (FP) 500 microg, and the combination (SFC) with placebo in 6,184 patients with moderate-to-severe COPD over 3 yrs. Despite a higher withdrawal rate in the placebo arm, after adjusting for time on treatment, a greater rate of pneumonia was reported in the FP and SFC treatment arms (84 and 88 per 1,000 treatment-yrs, respectively) compared with SAL and placebo (52 and 52 per 1,000 treatment-yrs, respectively). Risk factors for pneumonia were age > or =55 yrs, forced expiratory volume in 1 s <50% predicted, COPD exacerbations in the year prior to the study, worse Medical Research Council dyspnoea scores and body mass index <25 kg.m(-2). No increase in pneumonia deaths with SFC was observed; this could not be concluded for FP. Despite the benefits of ICS-containing regimens in COPD management, healthcare providers should remain vigilant regarding the possible development of pneumonia as a complication in COPD patients receiving such therapies.

The pervasive burden of lung infections receives proportionately little attention from the biomedical and public health communities, argues Mizgerd.

Asthma is a disease of airway inflammation that in most cases fails to resolve. The resolution of inflammation is an active process governed by specific chemical mediators, including D-series resolvins. In this study, we determined the impact of resolvin D1 (RvD1) and aspirin-triggered RvD1 (AT-RvD1) on the development of allergic airway responses and their resolution. Mice were allergen sensitized, and RvD1, AT-RvD1 (1, 10, or 100 ng), or vehicle was administered at select intervals before or after aerosol allergen challenge. RvD1 markedly decreased airway eosinophilia and mucus metaplasia, in part by decreasing IL-5 and IκBα degradation. For the resolution of established allergic airway responses, AT-RvD1 was even more efficacious than RvD1, leading to a marked decrease in the resolution interval for lung eosinophilia, decrements in select inflammatory peptide and lipid mediators, and more rapid resolution of airway hyperreactivity to methacholine. Relative to RvD1, AT-RvD1 resisted metabolic inactivation by macrophages, and AT-RvD1 significantly enhanced macrophage phagocytosis of IgG-OVA-coated beads in vitro and in vivo, a new proresolving mechanism for the clearance of allergen from the airways. In conclusion, RvD1 and AT-RvD1 can serve as important modulators of allergic airway responses by decreasing eosinophils and proinflammatory mediators and promoting macrophage clearance of allergen. Together, these findings identify D-series resolvins as potential proresolving therapeutic agents for allergic responses.