Department of Neurology with Institute of Translational Neurology, University Hospital Münster, Germany.
Institute of Molecular and Clinical Immunology, Magdeburg, Germany.
Brain Behav Immun. 2021 Mar;93:322-330. doi: 10.1016/j.bbi.2021.01.011. Epub 2021 Jan 22.
Flow stagnation of peri-ischemic capillaries due to dynamic leukocyte stalls has been described to be a contributor to ongoing penumbral injury in transient brain ischemia, but has not been investigated in permanent experimental stroke so far. Moreover, it is discussed that obstructing neutrophils are involved in this process; however, their contribution has not yet been proven. Here, we characterize the dynamics of neutrophil granulocytes in two models of permanent stroke (photothrombosis and permanent middle cerebral artery occlusion) using intravital two-photon fluorescence microscopy. Different to previous studies on LysM-eGFP cells we additionally apply a transgenic mouse model with tdTomato-expressing neutrophils to avoid interference from additional immune cell subsets. We identify repetitively occurring capillary stalls of varying duration promoted by neutrophils in both models of permanent cerebral ischemia, validating the suitability of our new transgenic mouse model in determining neutrophil occlusion formation in vivo. Flow cytometric analysis of peripheral blood (PB) and brain tissue from mice subjected to photothrombosis reveal an increase in the total proportion of neutrophils, with selective upregulation of endothelial adherence markers in the PB. In conclusion, the dynamic microcirculatory stall phenomenon that is described after transient ischemia followed by reperfusion also occurs after permanent small- or large-vessel stroke and is clearly attributable to neutrophils.
由于白细胞的动态停滞导致缺血半影区毛细血管中的血流停滞，被认为是短暂性脑缺血持续半影损伤的一个原因，但迄今为止，在永久性实验性中风中尚未进行研究。此外，有人认为阻塞中性粒细胞参与了这一过程；然而，它们的贡献尚未得到证实。在这里，我们使用活体双光子荧光显微镜在两种永久性中风模型（光血栓形成和永久性大脑中动脉闭塞）中描述中性粒细胞粒细胞的动力学。与以前关于 LysM-eGFP 细胞的研究不同，我们还应用了一种表达 tdTomato 的中性粒细胞的转基因小鼠模型，以避免来自其他免疫细胞亚群的干扰。我们在两种永久性脑缺血模型中均发现了由中性粒细胞反复引起的、持续时间不同的毛细血管停滞，验证了我们新的转基因小鼠模型在体内确定中性粒细胞阻塞形成的适用性。对接受光血栓形成的小鼠的外周血 (PB) 和脑组织进行流式细胞术分析显示，中性粒细胞的总比例增加，而 PB 中的内皮黏附标志物选择性上调。总之，在短暂性缺血再灌注后描述的动态微循环停滞现象也发生在小血管或大血管永久性中风后，这显然归因于中性粒细胞。
