Decreased apoptosis of pulmonary PMN in COPD patients with community-acquired pneumonia

Introduction: Chronic obstructive pulmonary disease (COPD) predisposes for the acquisition of community-acquired pneumonia (CAP). Objective/Methods: To assess clinically and scientifically suggested disorders in innate immune response during acute phrase and resolution CAP (T2), we evaluated peripheral and pulmonary polymorphnuclear neutrophils (PMN), recovered by induced sputum, from CAP patients with and without COPD with regard to cell activation, interleukin-8 (CXCL-8) and CXCL-8 receptor expression, and apoptosis rate. Results: At T1, COPD patients displayed significantly lower pulmonary PMN apoptosis rates, while total cell count, the amount of macrophages, and vital and necrotic neutrophils in sputum samples were similar between study groups. At T2, there were no differences between study groups or between pulmonary and peripheral compartment. While under systemic steroid treatment apoptosis rates of peripheral and pulmonary PMN at T1 were slightly decreased, there were no significant differences in intrapulmonary CXCL-8 levels. Regarding cell activation, no significant differences could be seen, neither in comparing study groups nor in pulmonary to peripheral PMN. Conclusion: Elucidating the pathology of suspected disorder in innate immune response, we found decreased apoptosis rates of pulmonary neutrophils in COPD at the peak of CAP indicating an increased inflammatory response, which is independent from anti-apoptotic cytokines such as CXCL-8, severity of disease and isolation of bacteria from sputum cultures.