Ischemia‒Reperfusion accelerates neointimal hyperplasia via IL-1β-mediated pyroptosis after balloon injury in the rat carotid artery

BACKGROUND: Ischemia‒reperfusion (IR) is a pathological process that causes secondary damage to blood vessels. However, whether IR can further worsen neointima formation after balloon injury and the detailed mechanism are unclear. METHODS: An in vivo model of balloon injury to the rat carotid artery was established to study the effect of IR following balloon injury on neointima formation. Smooth muscle cells (SMCs) were isolated from rat aortas and exposed to hypoxia-reoxygenation to mimic the IR process in vitro. The in vitro cell model was used to investigate the mechanism of IR-mediated neointima formation after balloon injury, which was further confirmed in an in vivo rat model. RESULTS: IR aggravated neointima formation in the rat carotid artery 2 weeks after balloon injury compared with that observed in the absence of balloon injury (P < 0.001). Compared with that of normal SMCs in the rat carotid artery, the expression of IL-1β, a key proinflammatory cytokine associated with pyroptosis, was increased more than 3-fold in the IR-induced neointima (P < 0.0001) and contributed to the proliferation and migration of rat primary aortic SMCs (P < 0.0001). This process was alleviated by the antioxidant acetylcysteine (NAC), suggesting its partial dependence on intracellular ROS. In the rat model of IR following balloon injury in the carotid artery, the carotid artery that was locally transfected with AAV carrying sh-IL-1β or sh-caspase-1, which alleviated neointima formation, as indicated by a reduction in intima-media thickness in the rat carotid artery (P < 0.0001). CONCLUSION: Our results suggested that IR could promote IL-1β production in SMCs in the carotid artery after balloon injury and aggravate neointimal hyperplasia, which was alleviated by silencing caspase-1/IL-1β signaling in SMCs in the carotid artery. These results suggest that IL-1β may be an effective target to combat IR-related neointima formation.