脑缺血-再灌注损伤后S100A8的表达及意义

The significance of S100A8 expression to cerebral ischemia reperfusion injury

目的探讨脑缺血-再灌注（I／R）损伤后S100A8的表达变化及其与Toll样受体4（TLR4）的关系。方法TLR4基因突变型小鼠C3H／HeJ（n=30）随机（随机数字法）分力模型组（n=18）和健康组（n=12），TLR4野生型小鼠C3H／HeN（n=30）随机分为模型组（n=18）和健康健康组组（n=12），采用线栓法制造局灶性脑缺血-再灌注损伤模型，再灌注12h后进行神经功能缺损评分，通过TTC染色和HE染色评价各组脑组织损伤程度，实时定量PCR技术和免疫荧光成像检测各组S100A8 mRNA和蛋白的表达。结果与C3H／HeN模型组比较，脑缺血-再灌注损伤12h后，C3H／HeJ模型组神经缺损评分明显减小（P〈0．01），脑梗死体积和神经细胞损伤程度也明显减轻（P〈0．01）。与健康组比较，C3H／HeJ和C3H／HeN模型组梗死侧脑组织中S100A8mRNA和蛋白表达显著上调，且C3H／HeN模型组脑组织中S100A8表达量较C3H／HeJ模型组增加更为明显（P〈0．01），提示S100A8表达与TLR4关系密切。结论S100A8很有可能通过与TLR4相互作用在脑I／R炎症损伤早期过程中发挥重要作用。

Objective To study the expression of S100A8 and the relationship between S100A8 and Toll-like receptor 4 （TLR4） in focal cerebral ischemia reperfusion （I/R） injury. Methods C3H/HeJ mice with TLR4 gene mutation （n =30） and C3H/HeN with normal TLR4 gene mice （n =30） were divided into 4 groups at random （random number） , namely C3H/HeJ model group （n = 18）, C3H/HeJ control group （n = 12）, and C3H/HeN model group （n = 18）. C3H/HeN control group （n = 12）. Middle cerebral artery was occluded to make I/R model in mice by using thread embolism method. Brain tissues were collected after ischemia for one hour and reperfusion for 12 hours. Stroke outcome was evaluated by determination of infarct volume of brain tissue and assessment of neurological scores. And brain injury after cerebral I/R was observed by optical microscope after TTC and HE staining. The immunofluorescence technique and RT-PCR were used to determine the protein level and expression of S100A8 mRNA in damaged brain tissues. Results Compared with C3H/HeN model mice, TLR4-deficient model mice （ C3H/ He J） had lower infarct volumes and better outcomes of neurological function after resuscitation for 12 hours. Compared with control groups, the expression of S100A8 mRNA and level of S100A8 protein increased greatly in damaged brain tissues of model mice after I/R injury. In addition, model mice with lacked TLR4 （C3H/HeJ） had lower expression of I/R-induced S100A8 mRNA than C3H/HeN mice in model group, indicating that the close relationship between the levels of S100A8 and TLR4. Conclusions S100A8 interaction with TLR4 might be involved in brain damage and in inflammation triggered by I/R injury.