Comprehensive characterisation of pulmonary and serum surfactant protein D in COPD

Carla Winkler, Elena N. Atochina-Vasserman, Olaf Holz, Michael F. Beers, Veit J. Erpenbeck, Norbert Krug, Stefan Roepcke, Gereon Lauer, Martin Elmlinger, Jens M. Hohlfeld

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81 Citations (Scopus)


Background: Pulmonary surfactant protein D (SP-D) is considered as a candidate biomarker for the functional integrity of the lung and for disease progression, which can be detected in serum. The origin of SP-D in serum and how serum concentrations are related to pulmonary concentrations under inflammatory conditions is still unclear.Methods: In a cross-sectional study comprising non-smokers (n = 10), young - (n = 10), elderly smokers (n = 20), and smokers with COPD (n = 20) we simultaneously analysed pulmonary and serum SP-D levels with regard to pulmonary function, exercise, repeatability and its quaternary structure by native gel electrophoresis. Statistical comparisons were conducted by ANOVA and post-hoc testing for multiple comparisons; repeatability was assessed by Bland-Altman analysis.Results: In COPD, median (IQR) pulmonary SP-D levels were lower (129(68) ng/ml) compared to smokers (young: 299(190), elderly: 296(158) ng/ml; p <0.01) and non-smokers (967(708) ng/ml; p <0.001). The opposite was observed in serum, with higher concentrations in COPD (140(89) ng/ml) as compared to non-smokers (76(47) ng/ml; p <0.01). SP-D levels were reproducible and correlated with the degree of airway obstruction in all smokers. In addition, smoking lead to disruption of the quaternary structure.Conclusions: Pulmonary and serum SP-D levels are stable markers influenced by smoking and related to airflow obstruction and disease state. Smaller subunits of pulmonary SP-D and the rapid increase of serum SP-D levels in COPD due to exercise support the translocation hypothesis and its use as a COPD biomarker.Trial registration: no interventional trial.

Original languageEnglish
Article number29
JournalRespiratory Research
Publication statusPublished - 11 Mar 2011
Externally publishedYes

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine

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