CX3CL1 inhibits NLRP3 inflammasome-induced microglial pyroptosis and improves neuronal function in mice with experimentally-induced ischemic stroke

Stroke represents the second cause of mortality across the globe and develops following the interruption of cerebral blood circulation. The chemokine CX3CL1 and its receptor CX3CR1 play a fundamental role in the pathophysiology of ischemic stroke. In this study, we investigated the protective effect of CX3CL1 against cerebral ischemia both in vitro and in vivo.We employed an in vivo mice model of middle cerebral artery occlusion(MCAO)/reperfusion and in vitro BV2 cells model of oxygen-glucose deprivation/re‑oxygenation (OGD/R). Exogenous recombinant CX3CL1 (rCX3CL1) was administered into the lateral ventricle 1, 3 and 5 day(s) after reperfusion or in cell supernatant following OGD/R. Immunostaining, immunoblotting, and ELISA were performed to assess the NLRP3 inflammasome-induced pyroptosis both in vivo and in vitro. In addition, neurological deficits and infarct volume in mice were evaluated after MCAO.The expression of CX3CL1 was downregulated after MCAO. Exogenous rCX3CL1 significantly reduced neurological deficits and infarct lesion in mice after MCAO. Moreover, exogenous rCX3CL1 inhibited GSDMD-dependent pyroptosis in microglia. Those effects further diminished NLRP3 inflammasome and NF-κB signaling activation, and also inhibited IL-1β and IL-18 expression both in vitro and in vivo.These results demonstrated that exogenous rCX3CL1 administration after the ischemic insult exerted a long-term neuroprotective effect on post-ischemic stroke. And exogenous rCX3CL1 could inhibit NLRP3 inflammasome-induced microglial pyroptosis under ischemic conditions. Collectively, our findings showed that CX3CL1 signaling pathway can serve as a therapeutic target for promoting the functional recovery after stroke.