Interferon regulator factor 1/retinoic inducible gene I (IRF1/RIG-I) axis mediates 25-hydroxycholesterol-induced interleukin-8 production in atherosclerosis

Abstract

In this study, the role of retinoic inducible gene I (RIG-I)-mediated signalling in the inflammation of atherosclerosis was investigated to explain the pathology of atherosclerosis. Human and mouse primary cells were exposed to 25-hydroxycholesterol followed by examination of gene expression and activation of the signal pathway with biochemical and molecular biological techniques. A mouse atherosclerotic model was also used. We found that RIG-I was induced in macrophages and endothelium by 25-hydroxycholesterol. Interferon regulatory factor 1 is a key transcription factor for the induction of RIG-I by 25-hydroxycholesterol. The induction of interleukin-8 and growth-regulated protein α, the mouse interleukin-8 homologue, by 25-hydroxycholesterol is mediated by RIG-I signalling. RIG-I transduces the signal to downstream molecules, mitochondrial antiviral-signalling protein, transforming growth factor-β-activated kinase 1, and mitogen-activated protein kinase, leading to the activation of nuclear factor κB, activator protein-1, and nuclear factor interleukin-6, all of which are required for the expression of interleukin-8. Finally, we observed that RIG-I is highly expressed in atherosclerotic lesions. Our data demonstrate that RIG-I signalling mediates atherosclerotic inflammation. Targeting RIG-I signalling should provide a way to inhibit atherosclerotic inflammation, which holds potential for the therapy of atherosclerosis.