CXCR4 Antagonist AMD3100 Protects Blood–Brain Barrier Integrity and Reduces Inflammatory Response After Focal Ischemia in Mice

Abstract

Background and Purpose-Inflammatory response plays a critical role in propagating tissue damage after focal cerebral ischemia. CXCL12 is a key chemokine for leukocyte recruitment. However, the role of CXCL12 and its receptor CXCR4 in ischemia-induced inflammatory response is unclear. Here we use the pharmacological antagonist of CXCR4, AMD3100, to investigate the function of CXCL12/CXCR4 in regulating inflammatory response during acute ischemia. Methods-Adult male CD-1 mice (n=184) underwent permanent suture middle cerebral artery occlusion (MCAO). AMD3100 was injected for 3 days (1 mg/kg/day) after MCAO. Brain water content, infarct volume, neurological score, and myeloperoxidase (MPO) expression and activity were examined at 24, 48, and 72 hours after MCAO. Proinflammatory cytokine RNA and protein levels in brain tissue were measured by RT-PCR and enzyme linked immunosorbent assay. Results-Neurological score was greatly improved in AMD3100-treated mice compared with the control mice 3 days after MCAO (P<0.05). Brain edema-induced change of water content, IgG protein leakage, Evans blue extravasation, occludin, and ZO-1 expression in ipsilateral hemisphere were alleviated by acute treatment of AMD3100. MPO expression and activity revealed that AMD3100 profoundly reduced the number of MPO-positive cells in the ischemic region (P<0.05). It also attenuated proinflammatory cytokines including interleukin 6, tumor necrosis factor α, and interferon γ; their mRNA and protein levels changed accordingly compared with the controls (P<0.05). Conclusions-CXCR4 antagonist AMD3100 significantly suppressed inflammatory response and reduced blood-brain barrier disruption after MCAO. AMD3100 attenuated ischemia-induced acute inflammation by suppressing leukocyte migration and infiltration, in addition to reducing proinflammatory cytokine expression in the ischemic region.

Preconditioning-induced CXCL12 upregulation minimizes leukocyte infiltration after stroke in ischemia-tolerant mice

“…Although the cortical mRNA expression levels of the CXCL12a isoform, as well as CXCR4, were unaffected by RHP, the constitutive upregulation of CXCL12b mRNA in the preconditioned cortex and the increase in CXCL12 protein levels are consistent with a long-term upregulation of CXCL12 protein expression in BBB endothelium. A single post-ischemic dose of AMD3100 attenuates post-stroke Evans blue leak and endothelial ZO-1/occludin disassembly, 18 but we found minimal effect of AMD3100 on BBB disruption in RHP-treated mice, which may be due to the already strengthened BBB in preconditioned mice. CXCL12a increases transendothelial electrical resistance and inhibits vascular permeability through intracellular actin rearrangement, with these phenotypes inhibited by AMD3100.…”

“…Therefore, the use of neurotherapeutics to enhance and/or expand CXCL12 expression by BBB endothelial cells prior to stroke, either via an engineered CXCL12 analog 38 or viral-mediated delivery, 27,39 could eventually be used in lieu of RHP to create a neuroprotective phenotype in individuals at identified risk for stroke, as well as enhance the recruitment of EPCs to promote cortical angiogenesis prior to injury. Considering the potential long-term use of CXCR4 antagonists in clinical populations, 40 and the efficacy of acute post-stroke antagonism of CXCL12 in animal models, [16][17][18] it is imperative to continue to probe how CXCL12 contributes to the maintenance of immune privilege during resting, physiologic conditions, as well as during the progression of injury and recovery following acute and chronic CNS injury. …”

Inhibition of CXCL12 Signaling Attenuates the Postischemic Immune Response and Improves Functional Recovery after Stroke

“…Hence, current data indicate that dependent on the spatiotemporal expression of CXCL12 and CXCR4, this chemokine pathway is involved in early neuroprotection but has adverse effects in the delayed inflammatory response after stroke. 35 Further studies are required to determine the extent to which different CXCL12 isoforms contribute to the mechanisms of neuronal plasticity during reorganization of the ischemic hemisphere. Recently, it was demonstrated that CXCL12 affects the function of GABAergic neurons at the infarct boundary 39 and upregulation of CXCL12 in glial cells promotes differentiation of oligodendrocyte precursor cells, which are important for remyelination in the ischemic hemisphere.…”

Shengmai injection attenuates the cerebral ischemia/reperfusion induced autophagy via modulation of the AMPK, mTOR and JNK pathways

“…In addition, the expression of JNK and its activation were also significantly increased at 24h reperfusion after cerebral ischemia (Huang et al 2013). Thus, we examined three complexes related pathways at 24 h after reperfusion to investigate the effect of SMXZF on cerebral ischemia/reperfusion injury-induced autophagy.…”