Periostin and closing volume in combined pulmonary fibrosis and emphysema

Abstract Background Combined pulmonary fibrosis and emphysema (CPFE) is an entity characterized by the presence of emphysema in upper lobes and fibrosis in lower lobes. Due to the presence of the two diseases concomitantly, it may be difficult to diagnose. This study aims at a better understanding of this entity and proposes biological markers (functional and biochemical) that help in this characterization. Methods A prospective, observational, cross-sectional study was carried out at a reference center. Pulmonary function tests (spirometry, CO-diffusion capacity, plethysmography and single-maneuver nitrogen washout test - SBWN 2 ) and biochemical markers (periostin, mucin-16, PDGF-BB and TGF-β 1 ) were measured in groups of patients: idiopathic pulmonary fibrosis, CPFE and chronic obstructive pulmonary disease (COPD). Results Variables derived from SBWN 2 - closing volume (CV) / vital capacity (VC) (%) and closing capacity (CC) / total lung capacity (TLC) (%) - were found to be higher in the CPFE group compared to the Idiopathic pulmonary fibrosis (IPF) group (CV/VC%: 0.25 (0.12 – 11.01) and 13.05 (0.21 – 20.73); p = 0.005; CC/TLC%: 30.1 (22.4 – 37.47) and 33.69 (32.05 – 41.98); p = 0.03, respectively). Periostin was higher in the CPFE group than in the other groups [CPFE: 66.74 (45.21 – 90.5), IPF: 43.81 (31.97 – 56.18), COPD: 40.08 (20.66 – 50.81); p = 0.0002], and mucin-16 was higher in the IPF group than in the CPFE group [CPFE: 13.59 (4.16 – 28.16); IPF: 71.94 (40.46 - 164); COPD: 25.85 (9.27 – 30.29); p = 0.02]. Conclusions Findings show that CPFE presents different functional and biochemical characteristics than IPF, including higher CV/VC%, CC/TLC% and periostin, whereas mucin-16 was higher in the IPF.