Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, Maryland.
J Neurotrauma. 2019 Apr 1;36(7):1040-1053. doi: 10.1089/neu.2018.6019. Epub 2018 Nov 16.
The inflammatory response to moderate-severe controlled cortical impact (CCI) in adult male mice has been shown to exhibit greater glial activation compared with age-matched female mice. However, the relative contributions of resident microglia and infiltrating peripheral myeloid cells to this sexually dimorphic neuroinflammatory responses remains unclear. Here, 12-week-old male and female C57Bl/6 mice were subjected to sham or CCI, and brain samples were collected at 1, 3, or 7 days post-injury for flow cytometry analysis of cytokines, reactive oxygen species (ROS), and phagocytosis in resident microglia (CD45CD11b+) versus infiltrating myeloid cells (CD45CD11b+). Motor (rotarod, cylinder test), affect (open field), and cognitive (Y-maze) function tests also were performed. We demonstrate that male microglia had increased phagocytic activity and higher ROS levels in the non-injured brain, whereas female microglia had increased production of tumor necrosis factor (TNF) α and interleukin (IL)-1β. Following CCI, males showed a significant influx of peripheral myeloid cells by 1 day post-injury followed by proliferation of resident microglia at 3 days. In contrast, myeloid infiltration and microglial activation responses in female CCI mice were significantly reduced. No sex differences were observed for TNFα, IL-1β, transforming growth factor β, NOX2, ROS production, or phagocytic activity in resident microglia or infiltrating cells at any time. However, across these functions, infiltrating myeloid cells were significantly more reactive than resident microglia. Female CCI mice also had improved motor function at 1 day post-injury compared with male mice. Thus, we conclude that sexually dimorphic responses to moderate-severe CCI result from the rapid activation and infiltration of pro-inflammatory myeloid cells to brain in male, but not female, mice.
在成年雄性小鼠中，中度至重度控制性皮质撞击（CCI）引起的炎症反应表现出比年龄匹配的雌性小鼠更大的神经胶质激活。然而，这种性别二态性神经炎症反应中，常驻小胶质细胞和浸润的外周髓样细胞的相对贡献仍不清楚。在这里，12 周龄的雄性和雌性 C57Bl/6 小鼠接受假手术或 CCI，在损伤后 1、3 或 7 天采集脑样本，用于流式细胞术分析细胞因子、活性氧（ROS）和常驻小胶质细胞（CD45CD11b+）与浸润的髓样细胞（CD45CD11b+）中的吞噬作用。还进行了运动（转棒、圆筒试验）、情感（旷场）和认知（Y 迷宫）功能测试。我们证明，雄性小胶质细胞在未受伤的大脑中具有更高的吞噬活性和更高的 ROS 水平，而雌性小胶质细胞具有更高的肿瘤坏死因子（TNF）α和白细胞介素（IL）-1β的产生。在 CCI 之后，雄性在损伤后 1 天出现明显的外周髓样细胞涌入，随后在 3 天出现常驻小胶质细胞的增殖。相比之下，CCI 后雌性小鼠的髓样细胞浸润和小胶质细胞激活反应明显减少。在任何时间点，常驻小胶质细胞或浸润细胞中的 TNFα、IL-1β、转化生长因子β、NOX2、ROS 产生或吞噬活性均未观察到性别差异。然而，在这些功能中，浸润的髓样细胞比常驻小胶质细胞更具反应性。与雄性小鼠相比，CCI 后的雌性小鼠在 1 天也表现出更好的运动功能。因此，我们得出结论，中度至重度 CCI 的性别二态性反应是由于雄性而非雌性小鼠中促炎髓样细胞的快速激活和浸润导致的。
