Expression of retinoic acid-inducible gene-I (RIG-I) in macrophages: Possible involvement of RIG-I in atherosclerosis

Abstract

Aim: Retinoic acid-inducible gene-I (RIG-I) is one of the genes induced by interferon (IFN)-γ which plays an important role in atherosclerosis. The aim of this study is to examine if RIG-I is involved in atherosclerosis. Methods: The expression of RIG-I in atherosclerotic lesions in human aorta was examined by immunohistochemical analysis. The expression of RIG-I in THP-1 monocytic cell line or human monocyte-derived macrophages was studied by western blot and RT-PCR analyses. Results: Intense immunoreactivity for RIG-I was detected in intimal macrophages in atherosclerotic lesions. IFN-γ slightly enhanced the RIG-I expression in THP-I cells. Treatment of the cells with phorbol 12-myristate 13-acetate, which induces the differentiation of the cells into macrophage-like cells, significantly enhanced the IFN-γ-induced RIG-I expression. IFN-γ also stimulated the expression of RIG-I in monocyte-derived macrophages. Conclusion: These results suggest that RIG-I may be involved in differentiation and activation of macrophages, playing a role in atherosclerosis.