Assessment of gene transcription demonstrates connection with the clinical course of idiopathic interstitial pneumonia

Background: Mediators of preferably mesenchymal repair such as transforming growth factor beta(1) (TGF-beta(1)) and mediators of polarized cellular immunity such as interleukin (IL)-13 are thought to be of key importance for progression of lung fibrosis. Nonetheless, a correlation between these mediators and the clinical development of fibrosis has not been performed thus far. Objectives: We correlated the transcription of TGF-beta(1), connective tissue growth factor (CTGF), IL-4, IL-13 and interferon-gamma (IFN-gamma) with lung function development in progressive fibrosis in idiopathic interstitial pneumonia. Methods: One hundred seventy nine sets of RT-PCR measurements were analyzed in 49 patients with usual interstitial pneumonia, nonspecific interstitial pneumonia or both. Specimens were taken by surgical and transbronchial lung biopsy. Lung function was measured at the time of biopsy and 1 year later. All patients received conventional treatment. Thirteen individuals were used as controls. Results: Transcription of TGF-beta(1), CTGF and IL-13 was significantly higher in pulmonary fibrosis compared to control, whereas transcription of IFN-gamma and IL-4 was virtually absent in both normal and fibrotic lungs. When comparing gene transcription with development of lung function, a significant correlation was observed between the decrease in both vital capacity and total lung capacity and increased transcription levels of TGF-beta(1) and IL-13. A reduced pulmonary diffusion capacity correlated with increased levels of TGF-beta(1) and CTGF. Transcription pattern in transbronchial and surgical samples was similar. Conclusions: We found a significant correlation between gene transcription and decrease in lung function that was more pronounced for TGF-beta(1) than for CTGF or IL-13. Our results suggest that transcription analysis may be used in clinical assessment of pulmonary fibrosis. Copyright (C) 2008 S. Karger AG, Basel.