Interferon alfa and gamma inhibit proliferation and collagen synthesis of human ito cells in culture

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Abstract

During the course of ongoing liver fibrogenesis, Ito cells acquire myofibroblastic features, proliferate, and synthesize increased amounts of extracellular matrix components. Interferon (IFN) alfa and IFN gamma have been shown to elicit antiproliferative and/or antifibrogenic effects in various cell cultures of mesenchymal origin. The aim of this study was to investigate the effects of IFN-α and IFN-γ on cultured human myofibroblastic Ito cells (MFBIC) proliferation and collagen synthesis and secretion. Serum-stimulated incorporation of [3H]-thymidine into DNA of MFBIC was dose-dependently decreased by both cytokines. IFN-α (104 U/mL) and IFN-γ (103 U/mL) decreased DNA synthesis by 69% and 66%, respectively. Inhibition of cell proliferation was confirmed by cell counting. Similar results were observed when cell growth was stimulated with platelet-derived growth factor (PDGF-BB, PDGF-AA) or transforming growth factor (TGF)-β1. Collagen secretion per cell was inhibited by both cytokines, as assessed by [3H]-hydroxyproline incorporation. After a 6-day treatment, IFN-γ showed a greater potency than IFN-α in inhibiting secretion of newly synthetized collagen (41% and 48% of control in the presence of 102 U/mL of IFN-γ and 104 U/ mL of IFN-α, respectively). Both IFN-α and IFN-γ concurrently decreased steady-state expression of type I and type III procollagen messenger RNAs (mRNAs) in quiescent MFBIC. Viability assays ruled out cytotoxic effects of the two molecules. Finally, both IFNs decreased smooth muscle α-actin (SMα-actin) expression, whether assayed by immunobloting or by Northern blot analysis. We conclude that IFN-α and IFN-γ inhibit proliferation as well as collagen synthesis in human MFBIC. (HEPATOLOGY 1995; 21:1003–1010.)

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