Serum levels of surfactant proteins in patients with combined pulmonary fibrosis and emphysema (CPFE)

Abstract

Introduction: Emphysema and idiopathic pulmonary fibrosis(IPF) are defined by different clinical, functional, radiological, and pathological criteria that coexist in CPFE. Serum surfactant protein(SP) levels increase in patients with COPD and IPF and correlate to disease severity. We aimed to evaluate SP(A, B, C and D)serum levels in CPFE compared to emphysema, IPF and controls and their associations with disease severity. Methods: Patients with IPF, emphysema, CPFE and controls were included. Subjects underwent PFTs, ABG measurements, 6MWT and HRCT with scoring for the extent of emphysema, fibrosis or their combination. Serum levels of SPs were measured by ELISA Results: 80 subjects(12 controls, 18 emphysema, 35 IPF and 15 CPFE) were included. SPA and D levels(ng/ml) differed significantly between groups:SPA: 128.7±47.2 vs 138.0±61.9 vs 170.9±53.0 vs 198.9±60.2 p=0.008 and SPD: 13.6±12.9 vs 34.1±28.3 vs 242.9±170.3 vs 246.8±191.1 p 1 (p=0.025, r=0.527) and DLCO(p=0.03, r=0.527). In CPFE, SPB levels correlated to FEV 1 (p=0.001,r=0.785) and FVC(p=0.001, r=0.791) whether SPD levels correlated to TLC(p=0.023, r=-0.622) Conclusions: Levels of SPA and D differ in patients with emphysema, IPF and CPFE with CPFE demonstrating the highest values and correlate to the extent of parenchymal damage. The differences in the associations of all SPs except SPC, with functional characteristics could suggest specific pathogenetic roles of SPs in each disease.