Microglial process convergence following brain injury

项目摘要 创伤性脑损伤（TBI）产生显著的病理学，包括损伤后炎症（特别是炎症反应）。 丘脑内），这可能导致长期发病。小胶质细胞，大脑的先天免疫细胞， 神经炎症的关键介质，可具有神经毒性或神经营养作用。进展 研究TBI诱导的啮齿动物神经免疫反应和治疗显示出巨大的 承诺已经转移到临床试验，但未能转化为有益的干预措施，为人类的痛苦 创伤性脑损伤然而，靶向在高等哺乳动物中发生的具有免疫应答的过程的疗法， 细胞结构和代谢率类似于人类，如猪，将更有可能转化为 诊所成功然而，猪脑损伤后的神经炎症进展并不理想- 明白我们的初步数据表明，小胶质细胞的过程收敛到受伤的轴突， 在微型猪的丘脑中的小胶质细胞过程会聚（MPC），在大鼠中不重现， 但似乎确实发生在人类身上。对小鼠的研究表明， 收敛（MPC）需要功能P2 Y12 R，然而，MPC背后的机制在更高的顺序， 哺乳动物是目前未知的。我们的初步数据和以前的研究都表明，MPC可能是一个 改善过程，促进损伤后急性轴突生长。因此，本研究的目的是 在弥漫性TBI猪模型中评估小胶质细胞变化对病理进展的作用。 研究表明，与男性相比，男性有更大的促炎反应和更少的轴突生长。 女性然而，没有已知的研究评估性别作为MPC的生物学变量。因此 目前的研究将致力于以下具体目标：1）评估炎症和 P2 Y12 R对损伤后MPC、神经元存活和轴突生长/回缩的调节，以及2） 评估弥漫性TBI和其他CNS损伤后人脑组织中MPC的患病率 伤害/疾病。为了实现这些目标，我们将完成对多路复用的3D定量评估。 在体外和猪中用于小胶质细胞-轴突相互作用的免疫组织学样品，以确定 MPC与轴突生长/收缩变化、P2 Y12 R表达和性别相关变异性有关。为 在人类人群中脑损伤后MPC的患病率目前尚不清楚，我们还将探索 MPC对受损轴突的影响程度，神经元存活，轴突生长/收缩，以及空间 在一组独特的死后脑组织中解析了RNA图谱。这项研究意义重大，因为 了解高阶物种和人类的小胶质细胞-神经元相互作用和修复机制， 两性都将转化为治疗TBI的治疗策略。

Project Abstract Traumatic brain injury (TBI) produces significant pathology, including post-injury inflammation (particularly within the thalamus), that can lead to long-term morbidities. Microglia, the innate immune cells of the brain, are critical mediators of neuroinflammation that can have either neurotoxic or neurotrophic effects. Progress has been made investigating TBI-induced neuroimmune responses in rodents and therapies showing great promise have moved to clinical trials but failed to translate into beneficial interventions for humans suffering TBI. However, therapies targeting processes that occur in higher order mammals, with immune responses, cytoarchitecture, and metabolic rates similar to humans, such as pigs, would be more likely to translate to the clinic successfully. The neuroinflammatory progression following brain injury in pigs, however, is not well- understood. Our preliminary data demonstrated that microglial processes converge onto injured axonal swellings (microglial process convergence; MPC) in the thalamus of micro pigs, that is not recapitulated in rats, following diffuse TBI but does appear to occur in humans. Studies in mice indicate that this microglial process convergence (MPC) requires functional P2Y12R, however, the mechanisms behind MPC in higher order mammals is currently unknown. Both our preliminary data and previous studies indicate that MPC may be an ameliorative process, promoting axonal outgrowth acutely post-injury. Therefore, the goal of this study is to assess the roles of microglial changes on pathological progression in a pig model of diffuse TBI. Studies indicate that males have greater pro-inflammatory responses and less axonal outgrowth compared to females. However, there are no known studies evaluating sex as a biological variable in MPC. Accordingly, the current study will address the following specific aims 1) to evaluate the effects of inflammatory and P2Y12R modulation on MPC, neuronal survival and axonal outgrowth/retraction following injury and 2) to assess the prevalence of MPC in human brain tissue following diffuse TBI and other CNS injuries/diseases. To address these aims we will complete quantitative 3D assessments of multiplexed immunohistological samples for microglial-axonal interactions in vitro and in pigs to determine the degree of MPC in relation to axonal outgrowth/retraction changes, P2Y12R expression, and sex-related variability. As the prevalence of MPC following brain injury in the human population is currently unknown, we will also probe for the degree of MPC onto injured axonal swellings, neuronal survival, axonal outgrowth/retraction, and spatially resolved RNA profiles in a unique cohort of postmortem brain tissue. This study is significant because understanding microglial-neuronal interactions and repair mechanisms in higher order species and humans of both sexes will translate into therapeutics strategies for the treatment of TBI.