Hypoxia and inflammation are central characteristics of the abdominal aortic aneurysm (AAA), but the mechanisms for their relationship and actual role remain far from full understood. Here, we showed MCP-1 (monocyte chemotactic protein-1) induced by hypoxia in primary human Aortic Smooth Muscle Cells (hASMCs) increased the chemotaxis of THP-1 macrophages and MCP-1 induced IL-6 expression in THP-1 cells via downregulating miR-98 which directly targets IL-6. In addition, IL-6 positively feedback regulated MCP-1 expression in hASMCs via p38 signal that is independent on hypoxia, and inhibition of p38 signal blocked the effect of IL-6 on MCP-1 expression regulation. Moreover, IL-6 exposure time-dependently induces phASMCs apoptosis via Stat1 activation. Collectively, our data provide compelling evidence on the association between hypoxia and inflammation triggered by hypoxia and then mediated by MCP-1/miR-98/IL-6/p38 regulatory loop, which leads to hASMCs apoptosis via Stat1 activation to contribute to AAA formation and progression.
Keywords: Abdominal aortic aneurysm; IL-6; MCP-1; hypoxia; macrophage.