颅脑创伤中谷氨酸型中性粒细胞亚群（NGlu）的形成及促炎机制研究

Over-inflammation plays an important role in the secondary injury of traumatic brain injury (TBI),such as brain edema, cerebral infarction, and neurogenic acute lung injury. However, it is hard to assay, predict and block its progression in clinic. Neutrophil is one of the majory participants in the initiation and development of inflammaion afterTBI. Therefore, it has great significance to elucidate the molecular mechanism of neutrophil effect in over-inflammation post TBI. Previously, we have found and identified a new neutrophil subtybe --- glutamate-associated neutrophil subtype (NGlu) in severe TBI patients and confirmed it in the mouse model of severe TBI. NGlu is marked with multiple intracellular glutamate (Glu), specific expression of glutamate transportor 1 (GLT1) which is not expressed on normal neutrophils, and delayed apoptosis and has powerful pro-inflammatory effect. More important, it is closely associated with the incidence of secondary injury after TBI. Further investigation suggests that high concentration of Glu in plasma after TBI and its receptor, metabotropic glutamate receptor 5 (mGluR5) are invovled in the formation and function of NGlu subtype neutrophil. Combination with literatures and our results, we speculate that surrounding Glu activating “mGluR5-protein kinase C(PKC) independent”pathway may induce the phenotype of NGlu subtype neutrophil, while intracellular Glu causing energy reprogramming and triggering “intracellular mGluR5- PKC dependent”mechanism may be invovled in its pro-inflammatory function.Accordingly, in this study, we plan to demonstrate this hypothesis via gene expression regluation techniques, signal pathway detections and metabonomics methods both in vitro and in vivo, which may give deep insight of inflammation progression after TBI. In addition, we will identify the relativity of NGlu proportion and degree of inflammatory injuries after TBI through clinic data analysis, which has the potential to provide a novel index for early warning of over-inflammatory injury after TBI and may give some new essential clues for more efficient and effective TBI therapy.

过度炎症反应是引起颅脑创伤（TBI）后脑及外周器官继发性组织损伤的重要因素，但目前对其发生发展尚无有效的监测、预警和干预手段。我们前期初步发现了一种与TBI后继发性损伤高度相关的谷氨酸型中性粒细胞亚群（NGlu），其表型特点为：胞内富含谷氨酸且特异表达谷氨酸转运体GLT1、功能特点为：凋亡滞后且促炎能力增强。进一步研究提示TBI后血浆中增高的谷氨酸活化“mGluR5-非PKC依赖途径”与其表型特点密切相关、而摄入胞内的谷氨酸诱导能量代谢重编程及“胞内mGluR5-PKC依赖途径”则密切参与其功能特点的形成。因此，拟借助基因表达调控技术、信号通路分析、能量代谢组学监测等在细胞及动物模型中阐明NGlu中性粒细胞亚群的形成及促炎机制，并结合临床分析探索干预策略，研究确立基于NGlu的过度炎症预警指标和组织损伤预防措施。旨在深入认知TBI后过度炎症发生及调控机理并为提升临床诊疗效果提供新的切入点。

创伤性颅脑损伤(Traumatic Brain injury, TBI)是神经外科的常见病且多发病，其致残率和致死率居所有外伤的第一位，严重危害了人类的健康和生活，造成的社会经济损失无法估量。颅脑创伤的损害分为原发性损伤和继发性损伤，前者无法逆转，而后者却是可逆并对预后具有绝对性作用。其中，过度炎症反应是颅脑创伤在继发性机械损害后造成机体二次伤害的主要因素之一，而中性粒细胞是颅脑创伤后最早入侵组织参与脑组织参与炎症反应的外周血白细胞。基于我们前期研究发现了颅脑创伤中一个新的中性粒细胞亚群（谷氨酸型中性粒细胞，Glutamate-associated Neutrophil subtype, NGlu）,该亚群胞内富含谷氨酸且特异表达在正常中性粒细胞中几乎不表达的谷氨酸转运体1（Glutamate transporotor 1, GLT1）；本项目的研究旨在（1）阐明颅脑创伤中该新的中性粒细胞亚群的形成和促炎机制，为颅脑创伤后过度炎症的发生发展机理提出新的认知；（2）明确NGlu 中性粒细胞亚群对颅脑创伤后过度炎症反应、组织损伤的监测和预警意义。. 通过该项目的资助，我们按计划完成研究内容，借助基因表达调控技术、信号通路分析、能量代谢监测等在细胞及动物模型中阐明了关键科学问题。1、NGlu中性粒细胞亚群的形成及促炎作用，并结合临床分析探索基于NGlu的过度炎症所致继发组织损伤预警提示，为深入认知颅脑创伤后过度炎症发生及调控机理提供新视角并为提升临床诊疗效果提供新的切入点。 ..