Department of Pharmacology, Monash University, Clayton, Victoria 3800, Australia.
Brain Res. 2011 Feb 4;1372:169-79. doi: 10.1016/j.brainres.2010.11.087. Epub 2010 Dec 4.
This study sought to identify potential targets for acute stroke therapy that can be exploited pharmacologically beyond the current 4.5h time limit for clinical administration of recombinant tissue-plasminogen activator. We used PCR arrays to initially screen the temporal expression profiles of several chemokine-related genes in the brain at 4, 24 and 72h after stroke. We identified large increases (>10-fold) in mRNA at 24 or 72h for the neutrophil CXCR2 receptor, and for CXCL1 and CXCL2-two chemokine ligands expressed by monocytes and neutrophils with strong neutrophil chemoattractant activity via CXCR2. We then tested the efficacy of a CXCR2 antagonist as a therapeutic. Mice were treated with vehicle (1% DMSO) or SB225002 (2mg/kg per day, ip) commencing at reperfusion, and we evaluated chemokine gene expression, neutrophil infiltration and functional and histological endpoints of stroke outcome. Expression levels of CXCL1, CXCL2 and CXCR2 after 24h were markedly reduced to near normal levels in SB225002-treated mice. Myeloperoxidase-positive cell infiltration was significantly reduced in SB225002-treated mice compared with vehicle-treated mice, and was similar to levels in sham-operated mice. However, although SB225002 evidently antagonised the interaction between CXCR2 and its chemokine ligands in the ischemic brain, mice treated with either SB225002 or vehicle had similar motor impairment and infarct volume at 72h. Thus, the reduced expression of CXC chemokine subfamily genes and neutrophil-related infiltration following SB225002 administration did not improve outcome after cerebral ischemia-reperfusion. CXCR2 antagonists are therefore unlikely to be a potential therapy for ischemic stroke.
这项研究旨在寻找急性中风治疗的潜在靶点，这些靶点可以在目前重组组织纤溶酶原激活物临床给药的 4.5 小时时限之外通过药理学手段加以利用。我们使用 PCR 阵列初步筛选了中风后 4、24 和 72 小时大脑中几种趋化因子相关基因的时间表达谱。我们发现，中性粒细胞 CXCR2 受体的 mRNA 在 24 小时或 72 小时时大量增加（>10 倍），而趋化因子配体 CXCL1 和 CXCL2 在单核细胞和中性粒细胞中表达，通过 CXCR2 具有强烈的中性粒细胞趋化活性。然后，我们测试了 CXCR2 拮抗剂作为治疗药物的疗效。从再灌注开始，用载体（1%DMSO）或 SB225002（2mg/kg/天，ip）治疗小鼠，并评估趋化因子基因表达、中性粒细胞浸润以及中风结局的功能和组织学终点。在 SB225002 治疗的小鼠中，24 小时后的 CXCL1、CXCL2 和 CXCR2 表达水平明显降低到接近正常水平。与载体治疗的小鼠相比，SB225002 治疗的小鼠中髓过氧化物酶阳性细胞浸润明显减少，与假手术组小鼠相似。然而，尽管 SB225002 明显拮抗了缺血性脑内 CXCR2 与其趋化因子配体之间的相互作用，但用 SB225002 或载体治疗的小鼠在 72 小时时的运动障碍和梗塞体积相似。因此，SB225002 给药后 CXC 趋化因子亚家族基因和中性粒细胞相关浸润的表达减少并没有改善脑缺血再灌注后的结局。因此，CXCR2 拮抗剂不太可能成为缺血性中风的潜在治疗方法。
