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

Abstract

Aims: 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.

Main methods: 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.

Key findings: 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.

Significance: 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.

Keywords: CX3CL1; Ischemic stroke; NLRP3 inflammasome; Neuroinflammation; Pyroptosis.