PURPOSE: Idiopathic pulmonary fibrosis (IPF) is a chronic, fibrosing disorder with a median survival of 2-5 years after diagnosis. Recent evidence suggests that the cytokine-like protein Osteopontin (OPN) has pro-fibrotic properties and is highly up-regulated in the lungs of IPF patients. We therefore wanted to investigate whether pirfenidone (PFD), which targets the mitogen-activated protein kinase, p38, and interferon gamma-1b (IFN-γ 1b), which inhibits fibrosis through the SMAD pathway, could inhibit OPN-mediated pro-fibrotic activity. Although no FDA-approved therapies for IPF exist, clinical trials are ongoing to investigate the efficacy of PFD and IFN-γ 1b. The present study was undertaken to further elucidate the underlying biological mediators that may be targeted by these drugs.
METHODS: The human fibroblast cell line, HFL-1 and the human epithelial cell line, A549, were co-cultured with OPN, PFD and IFN-γ 1b to examine collagen expression (by Sircol colorimetric analysis), chemotaxis (using Transwell chambers) and matrix metalloproteinase-7 (MMP-7) expression (by ELISA).
RESULTS: OPN (5 μg/mL) induced collagen expression in fibroblasts by 2-fold. In contrast, fibroblasts co-cultured with OPN and either PFD (185 μg/mL) or IFN-γ 1b (300 pg/mL) showed statistically significant reductions in collagen synthesis, while the combination of PFD and IFN-γ 1b had an additive inhibitory effect, reducing collagen expression by 45% (p = 0.025). Furthermore, OPN-induced fibroblast chemotaxis was inhibited by 20% (p = 0.003) by PFD and IFN-γ 1b. Finally, OPN-induced expression of MMP-7 in epithelial cells was strongly inhibited by PFD.
CONCLUSION: PFD and IFN-γ 1b alone or in combination significantly inhibit the pro-fibrotic activity of OPN. PFD and IFN-γ 1b have been shown to inhibit a plethora of fibrotic cytokines, including TGF-β, IL-4, IL-13, and now OPN. Furthermore, the combination of PFD and IFN-γ 1b may be more effective in inhibiting fibrosis than either drug alone.
CLINICAL IMPLICATIONS: Pending positive clinical trials evaluating the efficacy and safety of both drugs individually, further study to elucidate the effect of combining these agents in the treatment of IPF may be warranted.
DISCLOSURE: Osman Ozes, University grant monies No; Grant monies (from sources other than industry) No; Grant monies (from industry related sources) No; Shareholder R. Phillips, L. Blatt, O. Ozes: InterMune shareholders; Employee R. Phillips, 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.