Abstract
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 FEV1/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.
Highlights
Chronic obstructive pulmonary disease (COPD) “is a preventable and treatable disease with some significant extrapulmonary effects that may contribute to the severity in individual patients” [1]
Because lungs become more permeable with injury and infection, causing increased translocation of lung-derived proteins across the lung-blood barrier, we hypothesized that patients with exacerbations would have increased serum Surfactant protein D (SP-D) levels compared with patients with stable disease
Sin et al [6] showed that serum SP-D levels were inversely correlated to FEV1 in patients with advanced chronic obstructive pulmonary disease (COPD), which are consistent with the present findings where we found a significant inverse relationship between serum SP-D and various lung functions
Summary
Chronic obstructive pulmonary disease (COPD) “is a preventable and treatable disease with some significant extrapulmonary effects that may contribute to the severity in individual patients” [1]. Serum SP-D levels associate with lung function and with health status of patients with severe COPD [6]. Surfactant protein D (SP-D) is a pulmonary collectin regulating the innate immunity of the lung and its serum expression is perturbed in COPD. It is not known whether serum levels change during exacerbations. 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. 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
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