SP-D polymorphisms and the risk of COPD.

INTRODUCTION: There are limited data linking serum levels of surfactant protein D, its genetic polymorphisms to the risk of Chronic Obstructive Pulmonary Disease (COPD). OBJECTIVES: We sought to investigate these relationships using a case control study design. METHODS: Post bronchodilator values of FEV1/FVC < 0.7 were used to diagnose COPD patients (n=115). Controls were healthy subjects with normal spirometry (n=106) Single nucleotide polymorphisms (rs721917, rs2243639, rs3088308) were genotyped using polymerase chain reaction (PCR) and restriction analysis. Serum SP-D levels were measured using a specific immunoassay. RESULTS: Allele 'A' at rs3088308 (p < 0.00, B= -0.41) and 'C' allele at rs721917 (p=0.03; B= -0.30) were associated with reduced serum SP-D levels. Genotype 'T/T' at rs721917 was significantly associated with risk of COPD (p=0.01). Patients with repeat exacerbations had significantly higher serum SP-D even after adjusting for genetic factors. CONCLUSIONS: We report for the first time that rs3088308 is an important factor influencing systemic SP-D levels and confirm the previous association of rs721917 to the risk of COPD and serum SP-D levels.

Serum surfactant protein D during acute exacerbations of chronic obstructive pulmonary disease.

BACKGROUND: There is a paucity of lung specific biomarkers to diagnose exacerbations of chronic obstructive pulmonary disease (COPD) and to track their progression. Surfactant protein D (SP-D) is a pulmonary collectin regulating the innate immunity of the lung and its serum expression is perturbed in COPD. However, it is not known whether serum levels change during exacerbations. We sought to determine whether serum SP-D levels are raised in COPD exacerbations. OBJECTIVES: To determine whether or not patients with exacerbations have elevated serum SP-D levels compared with asymptomatic controls, stable disease. STUDY DESIGN: case control study. METHODS: We measured serum SP-D levels from patients with stable COPD (n= 14), patients experiencing acute exacerbations (n=13) and in control subjects (n=54) using a specific immunoassay and compared the levels using analysis of variance. RESULTS: Serum SP-D levels were significantly increased in patients who experienced an acute exacerbation (227 +/- 120 ng/mL) compared to patients with stable disease (151 +/- 83 ng/mL) or control subjects (128 +/- 65 ng/mL; p=0.003). Serum SP-D levels were also found to be inversely related to various lung function parameters including FEV_{1}/FVC% predicted. CONCLUSIONS: Our study suggests that serum SP-D levels are increased in patients during exacerbations and may be a potential diagnostic biomarker for COPD exacerbations.