Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA 94305-5327, USA.
Neuroscience. 2013 Jul 23;243:149-57. doi: 10.1016/j.neuroscience.2013.03.062. Epub 2013 Apr 13.
Ischemic postconditioning (IPostC) has been shown to attenuate brain injury in rat stroke models, but a mouse model has not been reported. This study establishes an IPostC model in mice and investigates how IPostC affects infiltration of leukocytes in the ischemic brain and lymphopenia associated with stroke-induced immunodepression.
A total of 125 mice were used. IPostC was performed by a repeated series of brief occlusions of the middle cerebral artery (MCA) after reperfusion, in a focal ischemia model in mice. Infarct sizes, neurological scores, inflammatory brain cells and immune cell populations in lymph nodes, spleen and bone marrow were analyzed with fluorescence-activated cell sorting (FACS).
IPostC performed immediately, 2 min and 3 h after reperfusion significantly reduced infarct sizes and attenuated neurological scores as measured up to 3 days post-stroke. In the group with strongest protection, infarct sizes were reduced from 49.6±2.8% (n=16) to 27.9±2.9% (n=10, P<.001). The spared infarct areas were seen in the ischemic penumbra or ischemic margins, i.e., the border zones between the cortical territories of the anterior cerebral artery and those of the MCA, as well as in the ventromedial and dorsolateral striata. FACS analyses showed that IPostC significantly blocked increases in the numbers of microglia (CD45intCD11b+), macrophages (CD45hiCD68+), CD4 T cells (CD45+CD4+) and CD8 T cells (CD45+CD8+) as well as B lymphocytes (CD45+CD19+) in the ischemic brain (n=5/group). Reduced-immune cell numbers in the peripheral blood and spleen were increased by IPostC while immune cell populations in the bone marrow were not altered by IPostC.
IPostC reduced brain infarction and mitigated neurological deficits in mice, likely by blocking infiltration of both innate and adaptive immune cells in the ischemic brain. In addition, IPostC robustly attenuated peripheral lymphopenia and thus improved systemic immunodepression.
缺血后处理(IPostC)已被证明可减轻大鼠中风模型中的脑损伤,但尚未在小鼠模型中报道。本研究建立了一种在小鼠中进行 IPostC 的模型,并研究了 IPostC 如何影响缺血性脑内白细胞浸润以及与中风引起的免疫抑制相关的淋巴细胞减少。
共使用了 125 只小鼠。在小鼠局灶性缺血模型中,通过再灌注后反复短暂阻断大脑中动脉(MCA)来实现 IPostC。通过流式细胞术(FACS)分析梗塞大小、神经评分、炎症性脑细胞以及淋巴结、脾脏和骨髓中的免疫细胞群体。
再灌注后立即、2 分钟和 3 小时进行 IPostC 可显著减少梗塞大小,并在中风后 3 天内减轻神经评分。在保护最强的组中,梗塞大小从 49.6±2.8%(n=16)减少到 27.9±2.9%(n=10,P<.001)。在缺血半影区或缺血边界区(即大脑前动脉皮质区和 MCA皮质区之间的交界区)以及腹侧和背外侧纹状体中可以看到未梗塞的区域。FACS 分析表明,IPostC 显著阻止了缺血性脑内小胶质细胞(CD45intCD11b+)、巨噬细胞(CD45hiCD68+)、CD4 T 细胞(CD45+CD4+)和 CD8 T 细胞(CD45+CD8+)以及 B 淋巴细胞(CD45+CD19+)数量的增加(n=5/组)。外周血和脾脏中的免疫细胞数量减少,但骨髓中的免疫细胞群体不受 IPostC 影响。
IPostC 减少了小鼠的脑梗塞并减轻了神经功能缺损,可能是通过阻止缺血性脑内固有和适应性免疫细胞的浸润来实现的。此外,IPostC 还显著减弱了外周性淋巴细胞减少,从而改善了全身免疫抑制。