Objective: To investigate the expressions of caveolin-1, collagen-I, α-smooth muscle actin (α-SMA) and Smad in lung tissues of patients with idiopathic pulmonary fibrosis (IPF) and therefore to explore their potential roles in the pathogenesis of the disease.
Methods: Six patients with IPF confirmed pathologically by open lung biopsy in Department of Pulmonary Medicine, Affiliated Drum Tower Hospital of Nanjing University from January 2005 to December 2008 were studied. Diagnosis of IPF was made in accordance with the American Thoracic Society/European Respiratory Society Consensus Statement. At the same period, 6 normal lung samples were also obtained from patients with lung cancer by surgical resections as the control group. The level of caveolin-1 mRNA and protein, collagen-I, α-SMA and Smads in lung tissues were detected by RT-PCR, Western blot and immunohistochemistry.
Results: Compared with the control group, significantly reduced levels of caveolin-1 mRNA and protein (0.66 ± 0.19 vs 0.05 ± 0.02; 0.81 ± 0.11 vs 0.16 ± 0.05, P < 0.05) were observed in the lungs of patients with IPF. However, collagen-I (0.85 ± 0.11 vs 0.16 ± 0.04) and α-SMA (0.78 ± 0.08 vs 0.14 ± 0.05) proteins in the lung tissues of IPF patients were significantly increased as compared to the controls (P < 0.05). The expressions of p-Smad2 and p-Smad3 proteins were significantly increased (0.78 ± 0.08 vs 0.17 ± 0.04; 0.86 ± 0.07 vs 0.14 ± 0.04, respectively, P < 0.05), while that of Smad7 protein decreased (0.22 ± 0.05 vs 0.78 ± 0.08, P < 0.05) in the lungs of patients with IPF as compared with the control groups.
Conclusion: The reduced expression of caveolin-1 in lung tissues of IPF may be related to the development and progress of pulmonary fibrosis.