Cell-specific gene expression in patients with usual interstitial pneumonia

Rationale: Usual interstitial pneumonia (UIP) is characterized by extracellular matrix deposition and the development of pulmonary fibrosis. Fibroblastic foci found in the lung are believed to represent an early stage in the evolution of this disease. Objectives: To compare gene expression profiles in different components of lung tissue (fibroblastic foci, adjacent epithelium, and areas of type 2 pneumocyte hyperplasia) from patients with UIP, and contrast these profiles to distal, uninvolved (control) alveolar tissue from patients undergoing lung resection for cancer. Methods: Lung resection tissue (UIP, n = 11; controls, n = 11) was snap-frozen for subsequent laser capture microdissection, followed by mRNA extraction, linear amplification, and quantitative realtime polymerase chain reaction. Results: In patients with UIP, tissue inhibitor of matrix metalloprotease-1 and matrix metalloprotease (MMP)-2 gene expression was up-regulated within the fibroblastic foci compared with the overlying epithelium (p = 0.03, p = 0.02), and to control alveoli (p = 0.001, p = 0.04), respectively. MMP-9 and MMP-7, as well as osteopontin, were up-regulated in fibroblastic foci (p = 0.01, p = 0.08, p 0.08), the adjacent epithelium (p = 0.001, p 0.001, p = 0.03), and the hyperplastic type 2 pneumocytes (p 0.02, p = 0.001, p = 0.08), respectively, compared with control alveoli. Conclusion: Altered gene expression of important profibrotic mediators in the different cellular lung compartments in patients with UIP likely plays an important role in pathogenesis of the deranged extracellular matrix deposition and subsequent fibrosis in this condition.