TGF-β1 in bronchoalveolar lavage fluid in diffuse parenchymal lung diseases and high-resolution computed tomography score

INTRODUCTION: In the pathogenesis of diffuse parenchymal lung diseases (DPLDs), growth factors, including transforming growth factor β1 (TGF-β1), are responsible for cell proliferation, apoptosis, chemotaxis, and angiogenesis, and also for the production and secretion of some components of the extracellular matrix. OBJECTIVES: The aim of the study was to evaluate correlations in DPLDs between TGF-β1 levels in bronchoalveolar lavage (BAL) fluid and high-resolution computed tomography (HRCT) score. PATIENTS AND METHODS: The study was performed in 31 DPLD patients in whom a selection of lung segments with high and low intensity of abnormalities was estimated by HRCT score. All patients underwent BAL with TGF-β1 measured by an enzyme immunoassay in BAL fluid and video-assisted thoracic surgery lung biopsy from both selected segments. RESULTS: All 31 patients were diagnosed, and based on histopathology, they were classified into 2 groups: idiopathic interstitial pneumonia (usual interstitial pneumonia – 12, nonspecific interstitial pneumonia – 2, cryptogenic organizing pneumonia – 2, and desquamative interstitial pneumonia – 1) and granulomatous disease (sarcoidosis – 7, extrinsic allergic alveolitis – 5, and histiocytosis X – 2). The final analysis was performed in 28 patients who showed nonhomogenous distribution on HRCT. TGF-β1 levels in BAL fluid were significantly higher in the areas with high intensity of abnormalities assessed by HRCT score (P = 0.018, analysis of variance). These levels were not different between the groups, but a trend towards higher levels in idiopathic interstitial pneumonia was observed. CONCLUSIONS: The results confirm that TGF-β1 may be a good but not specific marker of fibrosis in DPLDs. A significant positive correlation between TGF-β1 levels in BAL fluid and the HRCT score was observed.