BACKGROUND: Pulmonary surfactant protein A (SP-A) is a lectin, with multiple functions that contribute to innate host defense and the regulation of the inflammatory process in the lung. In normal conditions, SP-A seems to protect against the effects of smoking. However, studies in smokers with or without COPD are limited. METHODS: Western blots on lung tissue specimens from 60 male subjects (32 patients with COPD, 18 smokers without COPD, and 10 control nonsmokers) for SP-A and the housekeeping protein actin were carried out. Additionally, the SP-A expression pattern was evaluated by immunohistochemistry in formalin-fixed, paraffin-embedded lung tissue sections from the same subjects. RESULTS: Western blots revealed significantly higher SP-A levels in control nonsmokers (4.8 +/- 0.05) when compared with patients with COPD (0.6 +/- 0.7) and smokers without COPD (2.4 +/- 0.9), (P < .05). However, differences that were not statistically significant were observed in SP-A levels among the patients with COPD and the smokers without COPD (P = .12). The immunohistochemical examinations showed an increase in the overall number of type II pneumocytes per high-power field in patients with COPD, but a decreased ratio of SP-A positive type II pneumocytes to total type II pneumocytes, compared with smokers without COPD (P = .001). This ratio was also correlated with FEV(1) (percent predicted [% pred]), (r = 0.490, P = .001). The overall number of alveolar macrophages per high-power field was significantly higher in patients with COPD compared with smokers without COPD (P = .001). The ratio of SP-A positive alveolar macrophages was increased in patients with COPD when compared with smokers without COPD (P = .002), while this was correlated with airway obstruction (FEV(1), % pred) (r = 0.281, P = .04). CONCLUSIONS: Our results indicate that altered SP-A expression could be another link to COPD pathogenesis and highlights the need for further studies on surfactant markers in COPD.
BACKGROUND:Pulmonary surfactant protein A (SP-A) is a lectin, with multiple functions that contribute to innate host defense and the regulation of the inflammatory process in the lung. In normal conditions, SP-A seems to protect against the effects of smoking. However, studies in smokers with or without COPD are limited. METHODS: Western blots on lung tissue specimens from 60 male subjects (32 patients with COPD, 18 smokers without COPD, and 10 control nonsmokers) for SP-A and the housekeeping protein actin were carried out. Additionally, the SP-A expression pattern was evaluated by immunohistochemistry in formalin-fixed, paraffin-embedded lung tissue sections from the same subjects. RESULTS: Western blots revealed significantly higher SP-A levels in control nonsmokers (4.8 +/- 0.05) when compared with patients with COPD (0.6 +/- 0.7) and smokers without COPD (2.4 +/- 0.9), (P < .05). However, differences that were not statistically significant were observed in SP-A levels among the patients with COPD and the smokers without COPD (P = .12). The immunohistochemical examinations showed an increase in the overall number of type II pneumocytes per high-power field in patients with COPD, but a decreased ratio of SP-A positive type II pneumocytes to total type II pneumocytes, compared with smokers without COPD (P = .001). This ratio was also correlated with FEV(1) (percent predicted [% pred]), (r = 0.490, P = .001). The overall number of alveolar macrophages per high-power field was significantly higher in patients with COPD compared with smokers without COPD (P = .001). The ratio of SP-A positive alveolar macrophages was increased in patients with COPD when compared with smokers without COPD (P = .002), while this was correlated with airway obstruction (FEV(1), % pred) (r = 0.281, P = .04). CONCLUSIONS: Our results indicate that altered SP-A expression could be another link to COPD pathogenesis and highlights the need for further studies on surfactant markers in COPD.
Authors: Kerstin Höhne; Stephan J Schliessmann; Andreas Kirschbaum; Till Plönes; Joachim Müller-Quernheim; Hermann Tenor; Gernot Zissel Journal: PLoS One Date: 2012-07-16 Impact factor: 3.240