Liu Yong, Wu Xiao-Mei, Luo Qian-Qian, Huang Suna, Yang Qing-Wu Qian, Wang Fa-Xiang, Ke Ya, Qian Zhong-Ming
Department of Neurology, Xinqiao Hospital, The Third Military Medical University, Chongqing, China.
Department of Neurobiology, Institute for Nautical Medicine, Nantong University, Nantong, China.
J Cereb Blood Flow Metab. 2015 Oct;35(10):1623-31. doi: 10.1038/jcbfm.2015.97. Epub 2015 May 13.
The exact roles of activated microglia and fractalkine (CX3CL1)/fractalkine receptor (CX3CR1) signaling are not fully understood in brain ischemic injury and the findings reported are controversial. Here, we investigated the effects of CX3CR1 siRNA on the expression of CX3CR1, p38 mitogen-activated protein kinase (p38MAPK), Protein Kinase C (PKC) and inflammatory cytokines, microglia activation, white matter lesions, and cognitive function in mice treated with bilateral common carotid artery stenosis (BCAS) in vivo as well as effects of exogenous CX3CL1, CX3CR1 siRNA, and SB2035080 on expression of inflammatory cytokines in BV2 microglia treated with oxygen-glucose deprivation (OGD) in vitro. We showed that CX3CR1 siRNA significantly inhibited the increased expression of CX3CR1, p38MAPK, PKC as well as tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6, and also attenuated microglia activation, white matter lesions, and cognitive deficits induced by BCAS in mice brain. We also showed that exogenous CX3CL1 could induce a further enhancement in TNF-α and IL-1β expression, which could be suppressed by CX3CR1 siRNA or by the p38MAPK inhibitor in OGD-treated BV2 microglial cells in vitro. Our findings indicated that CX3CL1/CX3CR1-mediated microglial activation plays a detrimental role in ischemic brain via p38MAPK/PKC signaling and also suggested that CX3CL1/CX3CR1 axis might be a putative therapeutic target to disrupt the cascade of deleterious events that lead to brain ischemic injury.
在脑缺血损伤中，活化的小胶质细胞以及趋化因子（CX3CL1）/趋化因子受体（CX3CR1）信号的确切作用尚未完全明确，且已报道的研究结果存在争议。在此，我们研究了CX3CR1小干扰RNA（siRNA）对双侧颈总动脉狭窄（BCAS）处理的小鼠体内CX3CR1、p38丝裂原活化蛋白激酶（p38MAPK）、蛋白激酶C（PKC）和炎性细胞因子的表达、小胶质细胞活化、白质损伤及认知功能的影响，以及外源性CX3CL1、CX3CR1 siRNA和SB2035080对体外氧糖剥夺（OGD）处理的BV2小胶质细胞中炎性细胞因子表达的影响。我们发现，CX3CR1 siRNA显著抑制了CX3CR1、p38MAPK、PKC以及肿瘤坏死因子-α（TNF-α）、白细胞介素（IL）-1β和IL-６表达的增加，还减轻了BCAS诱导的小鼠脑内小胶质细胞活化、白质损伤及认知缺陷。我们还发现，外源性CX3CL1可诱导TNF-α和IL-1β表达进一步增强，而在体外OGD处理的BV2小胶质细胞中，CX3CR1 siRNA或p38MAPK抑制剂可抑制这种增强。我们的研究结果表明，CX3CL1/CX3CR1介导的小胶质细胞活化通过p38MAPK/PKC信号通路在缺血性脑损伤中起有害作用，也提示CX3CL1/CX3CR1轴可能是一个潜在的治疗靶点，可阻断导致脑缺血损伤的一系列有害事件。
