PURPOSE: Idiopathic pulmonary fibrosis (IPF) is a lung disease with an estimated survival comparable to that of non-small cell lung cancer. A key distinguishing feature of IPF is the presence of fibroblastic foci, which are thought to be sites of active fibrogenesis resulting from the aberrant expression of profibrotic cytokines. These areas are characterized by fibroproliferation, failed re-epithelialization, and enhanced extracellular matrix (ECM) deposition. Osteopontin (OPN) is a key molecule that has been found to be highly up-regulated in IPF lungs. Recent evidence suggests that OPN mediates fibrogenesis in the IPF lung by regulating cell migration and proliferation, tissue repair, and remodeling.
METHODS: We used human alveolar epithelial cells (A549) and lung fibroblasts (HFL-1) to analyze the individual and combined effects of pirfenidone (PFD) (185 mg/L) and interferon gamma-1b (IFN-γ 1b) (300 pg/mL) against OPN-mediated proliferation and mitogen-activated protein kinase signaling.
RESULTS: Treatment of A549 cells for 2-7 days with OPN (1μg/mL) caused a 4-20% increase in cellular proliferation, which was reduced by 6-19% (p=0.022) following exposure to PFD. HFL-1 cells treated with OPN over the same time period showed a similar increase (8-38%) in cellular proliferation, which was likewise attenuated by the addition of PFD (4-22% reduction, p=0.04). The combination of PFD and IFN-γ 1b reduced proliferation by 11-28% (p=0.017) and 12-51% (p=0.038) in A549 and HFL-1 cells, respectively. In HFL-1 cells, PFD inhibited OPN-induced phosphorylation of AKT and JNK by 20-36% (p=0.013) and 42% (p=0.04), respectively. OPN-induced phosphorylation of AKT, HSP27, and p-70-S6K in A549 cells was likewise abrogated by PFD, while the combination of PFD and IFN-γ 1b had a further inhibitory effect on AKT phosphorylation (75% reduction, p=0.03).
CONCLUSION: Pirfenidone and IFN-γ 1b, either alone or in combination, inhibit OPN-induced cellular proliferation and signaling.
CLINICAL IMPLICATIONS: Inhibition of OPN-mediated cellular proliferation and signaling by pirfenidone and IFN-γ 1b may represent a viable therapeutic strategy in IPF patients.
DISCLOSURE: Sarah Stevens, University grant monies No; Grant monies (from sources other than industry) No; Grant monies (from industry related sources) No; Shareholder S. Stevens, L. Blatt, O. Ozes: InterMune shareholders; Employee S. Stevens, L. Blatt, O. Ozes: InterMune employees; Fiduciary position (of any organization, association, society, etc, other than ACCP No; Consultant fee, speaker bureau, advisory committee, etc. No; Other No; Product/procedure/technique that is considered research and is NOT yet approved for any purpose, All.