Inhibition of Intrinsic Interferon-γ Function Prevents Neointima Formation After Balloon Injury
It is still controversial whether intrinsic interferon (IFN)-γ promotes or attenuates vascular remodeling in hyperproliferative vascular disorders, such as neointima formation after balloon injury. Thus, we investigated whether inhibition of intrinsic IFN-γ function prevents neointima formation. For this purpose, naked DNA plasmid encoding a soluble mutant of IFN-γ receptor α-subunit (sIFNγR; an IFN-γ inhibitory protein) or mock plasmid was injected into the thigh muscle of male Wistar rats 2 days before balloon injury (day −2). sIFNγR gene transfer significantly elevated serum levels of sIFNγR protein for 2 weeks. In mock-treated rats, balloon injury induced smooth muscle cell proliferation in the neointima with a peak at day 7 and produced thick neointima at day 14. sIFNγR treatment reduced the number of proliferating intimal smooth muscle cells by 50% at day 7 and attenuated neointima formation with a 45% reduction of the intima/media area ratio at day 14. In mock-treated rats, at day 7, balloon injury induced phosphorylation of signal transducer and activator of transcription-1 and upregulations of IFN regulatory factor-1 (a transcription factor mediating IFN-γ signal). Balloon injury also upregulated the key molecules of neointima formation, such as intercellular adhesion molecule-1 and platelet-derived growth factor β-receptor. These changes were suppressed by sIFNγR treatment. In conclusion, it is suggested that intrinsic IFN-γ promotes neointima formation probably through IFN regulatory factor-1/intercellular adhesion molecule-1–mediated and platelet-derived growth factor–mediated mechanisms. Thus, inhibition of IFN-γ signaling may be a new therapeutic target for prevention of neointima formation of hyperproliferative vascular disorders.
- Received December 22, 2006.
- Revision received January 12, 2007.
- Accepted January 24, 2007.