星形胶质细胞源性IL-17A在缺血性脑卒中作用及其cPKCgamma机制

The understanding of neuroprotective mechanism underlying cerebral ischemic/hypoxic preconditioning may provide the therapeutic strategy for ischemic stroke. We have reported that the neuron-specific classical protein kinase C (cPKC) gamma is involved in the development of cerebral hypoxic preconditioning and neuroprotection against ischemic injury. In addition, we recently found that IL-17A significantly increased both in cerebrospinal fluid (CSF) and peripheral blood of mice after ischemic stroke, as well as the appearance of IL-17A in CBF was earlier than peripheral blood; and the astrocytes not neurons or microglia were determined the only resource of IL-I7A in the brain of mice with ischemic stroke. As a pro-inflammatory cytokine, IL-17 may play a crucial role in the post-stroke inflammatory cascade and the delayed neuronal ischemic injuries. In this project, we will systematically explore the role of astrocyte-derived IL-17A in necroptosis, apoptosis and autophagy of neurons, and its cPKCgamma isoform-specific signal transduction mechanism in ischemic stroke. The cPKCgamma gene knockout mice, middle cerebral artery occlusion (MCAO)-induced ischemic stroke in vivo as well as oxygen-glucose deprivation (OGD)-induced ischemic injury in primary cultured cortical astrocytes and neurons in vitro, and the techniques of animal behavioral test, cell biology, biochemistry and molecular biology will be used. Our achievements will expand the knowledge of neuroprotective mechanism underlying cerebral ischemic/hypoxic injury and preconditioning, and may provide the biomarkers and therapeutic targets for ischemic stroke in clinical practice.

脑缺血/低氧预适应(I/HPC)机制研究可为临床防治缺血性脑卒中提供新策略。我们曾报道参与脑HPC形成的神经元特异性蛋白激酶C(cPKC)gamma具有脑保护作用，最近发现缺血性卒中小鼠脑脊液和血液中IL-17A显著增高，且脑脊液中变化先于血液；同时确定IL-17A来源于缺血脑内星形胶质细胞而非神经元或小胶质细胞。作为促炎因子，IL-17A在脑卒中后迟发神经炎症反应和继发神经元损伤中发挥着重要作用。据此，本课题拟利用cPKCgamma基因敲除小鼠、脑中动脉阻塞缺血性脑卒中模型、原代培养星形胶质细胞和神经元氧-糖剥夺缺血模型，借助行为学、细胞生物学、生物化学和分子生物学等学科技术，明确IL-17A加重缺血神经元程序性坏死、凋亡和自噬中作用及其cPKCgamma信号转导机制。研究成果将丰富人们对脑缺血/低氧损伤和适应形成机制的认识，并为缺血性脑卒中防治寻找生物标记物或治疗靶点提供实验依据。

缺血性脑卒中是全球第二大致死和致残疾病，目前仍缺乏有效的治疗手段。研究表明，免疫炎性反应在缺血性卒中的发生发展过程中扮演了重要角色。白细胞介素(Interleukin, IL)-17A 作为缺血性脑卒中急性期重要的促炎因子，在脑卒中后神经炎症反应和继发神经元损伤中发挥重要作用，但其具体分子机制尚不清楚。据此，本课题组利用IL-17A基因敲除小鼠、大脑中动脉栓塞(MCAO)致缺血性脑卒中和原代神经细胞氧-糖剥夺(OGD)致细胞缺血模型，借助行为学、细胞生物学和生物化学与分子生物学等学科研究技术，探讨了IL-17A在缺血性脑卒中发生发展过程中作用及其信号转导机制。研究发现：（1）中枢神经系统中星形胶质细胞是缺血性卒中鼠脑内IL-17A产生的主要来源；（2）缺血性卒中发生后，IL-17A通过IL-17RA和IL-17RC受体介导的Caspase-12依赖性细胞凋亡途径减轻梗死周围区星形胶质细胞的凋亡水平，但加重神经元的缺血性损伤；（3）IL-17A通过Src-PP2B-mTOR途径诱导过度自噬加重卒中后缺血神经元损伤；（4）IL-17A中和抗体可通过减轻缺血性卒中鼠梗死灶周围区星形胶质细胞激活和神经元凋亡及自噬水平，改善缺血性卒中小鼠的神经功能预后。所获成果进一步丰富了人们对缺血性卒中后神经细胞损伤机制的认识，同时为将靶向 IL-17A的治疗手段运用于临床缺血性卒中的治疗提供了科学的实验依据。