CX3CR1调节小胶质细胞极化加重脑缺血/再灌注损伤OA

Objective To investigate the role and mechanism of CX3C chemokine receptor 1(CX3CR1)in regu-lating microglial polarization via the MFGE8/Janus kinase 2(JAK2)/signal transducer and activator of transcrip-tion 3(STAT3)signaling pathway in cerebral ischemia/reperfusion injury(CI/RI).Methods A transient middle cerebral artery occlusion(tMCAO)model was established in mice,which were randomly divided into the follow-ing groups:sham operation,tMCAO,shNC,shCX3CR1,and shCX3CR1+shMFGE8.Infarct volume was as-sessed by TTC staining;neurological deficits were evaluated using the Longa scoring system;and histopathological changes in brain tissue were observed via HE staining and Nissl staining.Western blot and RT-qPCR were used to detect the expression of proteins related to the MFGE8/JAK2/STAT3 pathway and marker genes of microglial polarization.The levels of inflammatory cytokines(TNF-α,IL-6,IL-1β,etc.)in brain tissue were measured by ELISA.Results Compared with the sham group,the tMCAO group showed significantly in-creased infarct volume and neurological scores,accompanied by increased neuronal necrosis,nuclear pyknosis,and structural disruption,as well as elevated pro-inflammatory cytokine levels.The mRNA and protein levels of Cx3cr1 were up-regulated,while those of Mfge8 were down-regulated(P＜0.05).Compared with the shNC group,the shCX3CR1 group exhibited reduced infarct volume and neurological scores,decreased neuronal necro-sis,and lower pro-inflammatory cytokine levels.Additionally,the expression of M2-type microglial marker genes(Arg1,Cd206,YM1/2)was increased,whereas M1-type marker genes(Nos2,Tnf,Il1b)were decreased.MFGE8 protein levels were elevated,while total JAK2 and STAT3 protein levels remained unchanged,with re-duced phosphorylation levels of p-JAK2 and p-STAT3(P＜0.05).Compared with the shCX3CR1 group,the shCX3CR1+shMFGE8 group showed opposite trends in the above indicators(P＜0.05).Conclusions CX3CR1 may aggravate neuronal necrosis and CI/RI by inhibiting MFGE8 to activate the JAK2/STAT3 signaling pathway,thereby promoting M1-type microglial polarization.