RT Journal Article SR Electronic T1 Parenchymal trafficking of pleural mesothelial cells in idiopathic pulmonary fibrosis JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP erj01410-2010 DO 10.1183/09031936.00141010 A1 K.K. Mubarak A1 A. Montes-Worboys A1 D. Regev A1 N. Nasreen A1 K.A. Mohammed A1 I. Faruqi A1 E. Hensel A1 M.A. Baz A1 O.A. Akindipe A1 S. Fernandez-Bussy A1 S.D. Nathan A1 V.B. Antony YR 2011 UL http://erj.ersjournals.com/content/early/2011/07/07/09031936.00141010.abstract AB Idiopathic pulmonary fibrosis (IPF) is characterized by myofibroblast proliferation leading to architectural destruction. Neither the origin nor the continued proliferation of myofibroblasts is well understood.Explanted human IPF lungs were stained by immunohistochemistry for calretinin, a marker of pleural mesothelial cells (PMCs). COPD and CF lungs acted as controls. The number of PMCs per 100 nucleated cells and per photomicrograph was estimated along with the Ashcroft score of fibrosis. Mouse PMCs expressing green fluorescent protein (GFP), and those labeled with nanoparticles, were injected into the pleural space of mice given intranasal TGFβ1. Mouse lungs were lavaged and examined for the presence of GFP, α-smooth muscle actin (αSMA), and calretinin.Calretinin-positive PMCs were found throughout IPF lungs, but not in COPD or CF. The number of PMCs correlated with the Ashcroft score. In mice, nanoparticle-laden PMCs were recoverable by bronchoalveolar lavage, depending on TGFβ1 dose. Fluorescent staining showed αSMA expression in GFP-expressing PMCs, with colocalization of GFP and αSMA.PMCs can traffic through the lung and show myofibroblast phenotypic markers. PMCs are present in IPF lungs, and their number correlates with IPF severity. Since IPF presumably begins subpleurally, PMCs could play a pathogenetic role via mesothelial-mesenchymal transition.