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Respir Res. 2011 Mar 11;12:29. doi: 10.1186/1465-9921-12-29.

Comprehensive characterisation of pulmonary and serum surfactant protein D in COPD.

Author information

1
Department of Clinical Airway Research, Fraunhofer Institute for Toxicology and Experimental Medicine, Hannover, Germany.

Abstract

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.

PMID:
21396106
PMCID:
PMC3061904
DOI:
10.1186/1465-9921-12-29
[Indexed for MEDLINE]
Free PMC Article

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