Novel mechanisms suppressing pro-resolving innate immunity following traumatic brain injury

摘要 神经炎症已经成为继发性损伤和疾病进展的关键组成部分， 脑外伤最近的临床前研究揭示了外周先天免疫的神经毒性作用。 我们的初步发现表明这种过度反应可能是由EphA 4/mTOR信号传导介导的， 负调节外周来源的单核细胞/巨噬细胞（PDM）的抗炎状态。的 本申请的研究目的是表征细胞和分子机制， 先天免疫和PDM极化状态在组织损伤和功能恢复的调节中的作用 创伤性脑损伤我们的建议是建立在广泛的初步和已发表的数据基础上的，这些数据表明， 使用嵌合小鼠，在不存在外周EphA 4的情况下， 皮质撞击（CCI）损伤。有趣的是，源自EphA 4缺失小鼠的PDM直接赋予神经保护作用， 在单核细胞耗竭和替代模型中的血脑屏障保存。此外，我们发现， PDM特异性EphA 4抑制参与mTOR通路的关键蛋白的磷酸化，这是一种新的 调解人的前解决状态的PDM。我们假设EphA 4介导促炎性先天性炎症反应， 通过抑制mTOR信号传导，诱导PDM浸润、极化和表型分化， 导致脑外伤后神经血管功能障碍的行为。我们将采用细胞特异性耗竭， 替代以及新的转基因鼠模型。这些方法将包括严格的行为， 组织学和创新的低输入全基因组表观基因组学和转录组学评估的相关性 和PDM行为的机制。我们还将提供一个框架， 反应，以加速恢复和抑制促炎过程后TBI。

ABSTRACT Neuroinflammation has emerged as a critical component of secondary injury and disease progression following brain trauma. Recent pre-clinical studies have shed light on the neurotoxic effects of peripheral innate immunity. Our preliminary findings suggest this overzealous response may be mediated by EphA4/mTOR signaling which negatively regulates the anti-inflammatory state of peripheral-derived monocyte/macrophages (PDMs). The research objective of this application is to characterize the cellular and molecular mechanism(s) underlying innate immunity and PDM polarization status in the regulation of tissue damage and functional recovery following TBI. Our proposal builds upon extensive preliminary and published data demonstrating a distinct protective and reduced pro-inflammatory response in the absence of peripheral EphA4 using chimeric mice following controlled cortical impact (CCI) injury. Interestingly, PDMs-derived from EphA4null mice directly confer neuroprotection and blood brain-barrier preservation in a model of monocyte depletion and replacement. Moreover, we discovered that PDM-specific EphA4 suppresses phosphorylation of key proteins involved in the mTOR pathway, a novel mediator of the pro-resolving state of PDMs. We hypothesize that EphA4 mediates the pro-inflammatory innate immune response by suppressing mTOR signaling, which induces PDM infiltration, polarization and phenotypic behaviors that drive neurovascular dysfunction following TBI. We will employ cell-specific depletions, and PDM replacement as well as novel transgenic murine models. These approaches will include rigorous behavioral, histological and innovative low-input genome-wide epigenomic and transcriptomic assessment of the relevance and mechanism(s) of PDM behaviors. We will also provide a framework for retooling the neuroinflammatory response to accelerate recovery and dampen pro-inflammatory processes after TBI.