Neuroscience Program, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd., Bethesda, MD, 20814, USA.
Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, Bethesda, MD, USA.
Mol Neurobiol. 2021 Jul;58(7):3545-3560. doi: 10.1007/s12035-021-02362-5. Epub 2021 Mar 24.
Mechanical stretch-injury is a prominent force involved in the etiology of traumatic brain injury (TBI). It is known to directly cause damage and dysfunction in neurons, astrocytes, and endothelial cells. However, the deleterious effects of stretch-injury on microglia, the brain's primary immunocompetent cell, are currently unknown. The Cell Injury Controller II (CICII), a validated cellular neurotrauma model, was used to induce a mechanical stretch-injury in primary rat microglia. Statistical analysis utilized Student's t test and one- and two-way ANOVAs with Tukey's and Sidak's multiple comparisons, respectively. Cells exposed to stretch-injury showed no signs of membrane permeability, necrosis, or apoptosis, as measured by media-derived lactate dehydrogenase (LDH) and cleaved-caspase 3 immunocytochemistry, respectively. Interestingly, injured cells displayed a functional deficit in nitric oxide production (NO), identified by media assay and immunocytochemistry, at 6, 12, 18, and 48 h post-injury. Furthermore, gene expression analysis revealed the expression of inflammatory cytokines IL-6 and IL-10, and enzyme arginase-1 was significantly downregulated at 12 h post-injury. Time course evaluation of migration, using a cell exclusion zone assay, showed stretch-injured cells display decreased migration into the exclusion zone at 48- and 72-h post-stretch. Lastly, coinciding with the functional immune deficits was a significant change in morphology, with process length decreasing and cell diameter increasing following an injury at 12 h. Taken together, the data demonstrate that stretch-injury produces significant alterations in microglial function, which may have a marked impact on their response to injury or their interaction with other cells.
机械拉伸损伤是外伤性脑损伤 (TBI) 发病机制中的一个重要因素。它已知会直接导致神经元、星形胶质细胞和内皮细胞的损伤和功能障碍。然而，拉伸损伤对小胶质细胞（大脑主要的免疫活性细胞）的有害影响目前尚不清楚。细胞损伤控制器 II (CICII) 是一种经过验证的细胞神经损伤模型，用于在原代大鼠小胶质细胞中诱导机械拉伸损伤。统计分析分别使用了学生 t 检验和单因素及双因素方差分析，以及 Tukey 和 Sidak 的多重比较。通过测量培养基中乳酸脱氢酶 (LDH) 和裂解型 caspase-3 的免疫细胞化学染色，未发现暴露于拉伸损伤的细胞有膜通透性、坏死或凋亡的迹象。有趣的是，受伤细胞的一氧化氮 (NO) 产生功能缺陷，通过培养基测定和免疫细胞化学染色鉴定，在损伤后 6、12、18 和 48 小时时显现。此外，基因表达分析显示，炎症细胞因子 IL-6 和 IL-10 的表达以及酶精氨酸酶-1 在损伤后 12 小时显著下调。使用细胞排斥区测定法对迁移进行时间过程评估显示，拉伸损伤细胞在拉伸后 48 小时和 72 小时迁移到排斥区的能力降低。最后，与功能免疫缺陷相一致的是形态发生了显著变化，在损伤后 12 小时，细胞的突起长度变短，细胞直径增大。总之，这些数据表明拉伸损伤会导致小胶质细胞功能发生显著改变，这可能对它们对损伤的反应或与其他细胞的相互作用产生重大影响。
