Serum surfactant protein D is steroid sensitive and associated with exacerbations of COPD

¹ Dept of Medicine, University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Hills Road, Cambridge, UK
² The Channing Laboratory and Pulmonary and Critical Care Division, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
³ GlaxoSmithKline, USA

^* To whom correspondence should be addressed. E-mail: dal16{at}cam.ac.uk.

	Abstract

Surfactant protein-D (SP-D) is a lung derived protein that has been proposed as a biomarker for inflammatory lung disease.

We have evaluated serum SP-D as a biomarker for components of COPD in the ECLIPSE cohort and have assessed its response to the administration of the anti-inflammatory agent prednisolone.

The median level of serum SP-D was significantly elevated in 1888 individuals with COPD when compared to 296 current and former smokers without airflow obstruction (121.1 and 114.3 ng·mL^-1 respectively; p=0.021) and 201 non-smokers (82.2 ng·ml^-1; p<0.001). There was no correlation with the severity of COPD. Individuals with COPD who had a serum SP-D that was greater than the 95th percentile of non-smokers (175.4 ng·mL^-1) had an increased risk of exacerbations over the following 12 months (adjusted odds ratio 1.30, C.I. 1.03, 1.63). Treatment with 20 mg·day^-1 prednisolone for four weeks resulted in a fall in serum SP-D (126.0 to 82.1 ng·mL^-1; p<0.001) but no statistically significant change in post-bronchodilator FEV₁.

Serum SP-D is raised in smokers and may be useful in identifying individuals who are at increased risk of exacerbations of COPD. It may represent an intermediate measure for the development of novel anti-inflammatory agents.