Gene expression analysis of lung biopsies from patients with two different forms of pulmonary sarcoidosis

Approximately 60-70% of patients with pulmonary sarcoidosis have a good outcome, with disease that resolves spontaneously. It is unclear why some patients progress to fibrotic disease, and there is currently no marker that differentiates these patients from those with self-limiting lung disease. Using the Affymetrix Human Gene 1.0 ST Array, we examined gene expression in lung tissue samples obtained using bronchoscopic transbronchial biopsy from 8 patients with active but self-limiting pulmonary sarcoidosis and 7 with active, progressive, fibrotic pulmonary disease. Analyses were performed to identify differentially expressed genes between the two groups, and to test for enrichment of sets of genes associated with defined biological processes from the Gene Ontology Consortium, as well as with gene sets derived from published data for idiopathic pulmonary fibrosis (IPF) and hypersensitivity pneumonitis (HP). Expression levels were examined in lung biopsy samples from 8 patients with nodular, self-limiting pulmonary sarcoidosis and 7 patients with progressive, fibrotic pulmonary sarcoidosis.