Surfactant Protein D, Soluble Intercellular Adhesion Molecule-1 and High-Sensitivity C-Reactive Protein as Biomarkers of Chronic Obstructive Pulmonary Disease

Abstract

Objective: The aim of this study was to estimate the serum levels of surfactant protein D (SP-D), soluble intercellular adhesion molecule-1 (sICAM-1), and high-sensitivity C-reactive protein (hs-CRP) in patients with chronic obstructive pulmonary disease (COPD) and to assess the correlation of these indices with COPD severity. Subjects and Methods: This analytic cross-sectional study was carried out on 64 COPD male patients, and 26 apparently healthy age-matched males as a control. Chest X-ray, spirometry and arterial blood gases were done for only COPD patients. Serum levels of SP-D, sICAM-1 and hs-CRP were determined by enzyme-linked immunosorbent assay in both patient and control groups. Results: The serum levels of SP-D, sICAM-1 and hs-CRP were significantly higher in COPD patients than controls (p < 0.001 for each). Also, these biomarkers were significantly higher in stages III and IV compared to either stage I or II (p < 0.01 for each). SP-D was significantly positively correlated with sICAM-1 and hs-CRP (r = 515, p < 0.001; r = 501, p < 0.001, respectively) and negatively correlated with PaO₂ (r = -0.651, p < 0.001) and all parameters of spirometry.Conclusion: SP-D, sICAM and hs-CRP were significantly higher in COPD patients in comparison with controls. Moreover, SP-D, sICAM-1, and hs-CRP were significantly negatively correlated with FEV₁%. Accordingly, estimation of these biochemical indices may be used as biomarkers for assessment of COPD severity.