TGF-beta1 in bronchoalveolar lavage fluid in diffuse parenchymal lung diseases and high-resolution computed tomography score

In the pathogenesis of diffuse parenchymal lung diseases (DPLDs), growth factors, including transforming growth factor beta1 (TGF-beta1), are responsible for cell proliferation, apoptosis, chemotaxis, and angiogenesis, and also for the production and secretion of some components of the extracellular matrix. The aim of the study was to evaluate correlations in DPLDs between TGF-beta1 levels in bronchoalveolar lavage (BAL) fluid and high-resolution computed tomography (HRCT) score. 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-beta1 measured by an enzyme immunoassay in BAL fluid and video-assisted thoracic surgery lung biopsy from both selected segments. All 31 patients were diagnosed, and based on histopathology, they were classified into 2 groups: idiopathic interstitial pneumonia (usual interstitial pneumonia - 12, nonspecific inter stitial 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-beta1 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 inter stitial pneumonia was observed. The results confirm that TGF-beta1 may be a good but not specific marker of fibrosis in DPLDs. A significant positive correlation between TGF-beta1 levels in BAL fluid and the HRCT score was observed.