| [Purpose] CXCL12/CXCR4signal inhibitor AMD3100plays a vital role in inflammatory cell migration into the central nervous system (CNS) after ischemic stroke. Microglia/macrophages play a critical role in cerebral ischemia, and the effect of their polarization on inflammatory responses has received extensive discussions. We determine whether and how acute AMD3100treatment modulates polarized microglia/macrophages via CXCL12/CXCR4signaling to affect inflammation after ischemic stroke.[Methods] Adult male Sprague-Dawley (SD) rats underwent permanent middle cerebral artery occlusion (pMCAO) and AMD3100was injected at1hour and next12hours after pMCAO for five times. Infarct volume were assessed after pMCAO. Immunofluorescence was utilized to determine the action of AMD3100on the polarized microglia/macrophages in brain tissue after pMCAO. Oxygen-glucose deprivation (OGD) model was used to imitate the ischemic condition in vitro and the role of CXCL12/CXCR4signaling on migration of different polarized microglia was evaluated using a transwell system. Real-time PCR was used to detect mRNA expressions of cytokines secreted in the ischemic area. MTT colorimetric assay and quantitative MAP-2Enzyme-linked immunosorbent assay (ELISA) were used to evaluate the effects of microglia/macrophage phenotype on the fate of ischemic neurons.[Results] In vivo, acute AMD3100administration attenuated infarct volume and improved neurological outcome after pMCAO. AMD3100treatment in acute ischemia significantly attenuates the number of activated microglia/macrophages rather than impacting their activated state.Ischemic insults activates almost all microglia/macrophages in the attectea area and induces increase in M1and M2polarization. Also, in vivo, M1phenotype constitutes the majority of activated microglia/macrophages and AMD3100treatment significantly attenuates migration of M1phenotype into the ischemic border zone (IBZ), and declines the gene levels of pro-inflammatory cytokines including TNF-a, iNOS in ischemic region after pMCAO. In addition, ischemic injury largely up-regulates the expression of CXCR4in microglia/macrophages and CXCR4is primarily expressed in microglia/macrophages. While under OGD condition, AMD3100significantly suppresses the migration of both M1and M2microglia through inhibition of CXCL12/CXCR4signaling under ischemic condition. Ml microglia inhibited neuronal survival under pathological conditions via soluble factors.[Conclusions] Treatment with AMD3100in acute phase of ischemic stroke suppresses M1microglia/macrophages migration to ischemic tissue through inhibition of CXCL12/CXCR4signaling, and, attenuates inflammation, improves neurological outcome after ischemic stroke. Balancing M1and M2microglia/macrophages recruited to ischemic region may provide potential therapies after ischemic injury. [Purpose] To study whether prolonged CXCR4antagonist AMD3100treatment in acute phase of stroke could improve the outcome after injury.[Methods] Male SD rats were used to establish the permanent middle cerebral artery occlusion (pMCAO) models and specific markers were utilized to identify EPCs. CXCR4antagonist AMD3100was administrated for consecutive seven days just after pMCAO and then its role in the recruitment of endogenous EPCs was evaluated. Capillary density was determined with FITC-dextran staining, and neurobehavioral function was assessed by neurological function.[Results] After AMD3100treatment for seven consecutive days, the number of endogenous EPCs and capillary density in ischemic boundary zone (Ischemic boundary zone, IBZ) of rats after pMCAO were both significantly reduced, and neurobehavioral function recovery was worse than the saline group.[Conclusions] Our study suggested that after pMCAO, endogenous EPCs were recruited to the IBZ via CXCL12/CXCR4axis. And prolonged administration of AMD3100at acute phase could inhibit angiogenesis in the IBZ and rather aggravate the outcome after stroke. |
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