Department of Exercise Science, Department of Biology, PERFORM Centre, Concordia University, Montréal, Quebec, Canada.
Department of Neurology and Neurosurgery, Montreal Neurological Institute, and McGill University, Montreal, Quebec, Canada.
Glia. 2019 Apr;67(4):582-593. doi: 10.1002/glia.23503. Epub 2018 Nov 16.
During inflammatory processes of the central nervous system, helper T cells have the capacity to cross the blood-brain barrier and injure or kill neural cells through cytotoxic mechanisms. Glial fibrillary acidic protein (GFAP) is an intermediate filament protein that is part of the astrocyte cytoskeleton that can become fragmented in neuroinflammatory conditions. The mechanism of action by which helper T cells with cytotoxic properties injure astrocytes is not completely understood. Primary human astrocytes were obtained from fetal brain tissue. Human helper (CD4 ) T cells were isolated from peripheral blood mononuclear cells and activated with the superantigen staphylococcal enterotoxin E (SEE). Granzyme B was detected by enzyme linked immunosorbent assay and intracellular flow cytometry. GFAP fragmentation was monitored by western blotting. Cell death was monitored by lactic acid dehydrogenase release and terminal biotin-dUTP nick labeling (TUNEL). Astrocyte migration was monitored by scratch assay. Adult human oligodendrocytes were cultured with sublethally injured astrocytes to determine support function. Helper T cells activated with SEE expressed granzyme B but not perforin. Helper T cells released granzyme B upon contact with astrocytes and caused GFAP fragmentation in a caspase-dependent, MHCII-independent manner. Sublethally injured astrocytes were not apoptotic; however, their processes were thin and elongated, their migration was attenuated, and their ability to support oligodendrocytes was reduced in vitro. Helper T cells can release granzyme B causing sublethal injury to astrocytes, which compromises the supportive functions of astrocytes. Blocking these pathways may lead to improved resolution of neuroinflammatory lesions.
在中枢神经系统的炎症过程中，辅助性 T 细胞具有穿过血脑屏障的能力，并通过细胞毒性机制损伤或杀死神经细胞。胶质纤维酸性蛋白 (GFAP) 是一种中间丝蛋白，是星形胶质细胞细胞骨架的一部分，在神经炎症条件下会发生碎片化。具有细胞毒性的辅助性 T 细胞损伤星形胶质细胞的作用机制尚不完全清楚。原代人星形胶质细胞从胎脑组织中获得。从外周血单核细胞中分离出人辅助性 (CD4) T 细胞，并通过超抗原葡萄球菌肠毒素 E (SEE) 激活。通过酶联免疫吸附试验和细胞内流式细胞术检测颗粒酶 B。通过 Western blot 监测 GFAP 片段化。通过乳酸脱氢酶释放和末端生物素-dUTP 缺口标记 (TUNEL) 监测细胞死亡。通过划痕实验监测星形胶质细胞迁移。用亚致死性损伤的星形胶质细胞培养成年人类少突胶质细胞，以确定支持功能。用 SEE 激活的辅助性 T 细胞表达颗粒酶 B，但不表达穿孔素。辅助性 T 细胞与星形胶质细胞接触时释放颗粒酶 B，并以半胱天冬酶依赖性、MHCII 非依赖性方式导致 GFAP 片段化。亚致死性损伤的星形胶质细胞不会发生凋亡；然而，它们的突起变薄且细长，迁移受到抑制，体外支持少突胶质细胞的能力降低。辅助性 T 细胞可以释放颗粒酶 B，导致星形胶质细胞亚致死性损伤，从而损害星形胶质细胞的支持功能。阻断这些途径可能会导致神经炎症病变的更好解决。
