THE ROLE OF PTEN IN MICROGLIAL PATHOBIOLOGY AFTER EXPOSURE TO REPETITIVE MILD TBI

重复性轻度创伤性脑损伤(r-mtbi)是发生脑损伤的最大危险因素之一。 神经退行性疾病。到目前为止，还没有开发出任何疾病修改疗法来预防长期的- TBI的长期后果。有必要提高我们目前对细胞机制的理解。 推动脑外伤后的长期神经功能障碍，因为这可能导致新的治疗方法的确定 目标。驻留小胶质细胞介导的神经炎症是人类和动物模型的共同特征 TBI的。控制疾病相关小胶质细胞反应的增殖和持续的因素 脑外伤的慢性后遗症仍然难以捉摸。我们已经建立了一种r-mTBI的小鼠模型，该模型概括了许多 这是人类脑损伤的特征，因此代表了一个翻译相关的临床前平台。从这个模型我们 在损伤后的一系列时间点产生了一个小胶质细胞基因图谱的分子文库，提供了 R-mtbi致小胶质细胞神经炎性反应的独特而详细的时间进程。尤其是，我们 揭示能量生物能量学、细胞因子信号、脂质代谢和促炎信号的缺陷 在慢性时间点的小胶质细胞，这似乎是由磷酸酶和Tensin的激活驱动的 同源蛋白(PTEN)信号转导。PTEN是一种能拮抗磷脂酰肌醇3-激酶的脂质磷酸酶 信号是调节细胞存活、能量生物能量学、自噬和炎症的关键节点。 PTEN在髓系细胞中高表达，其表达失调可引发炎症的激活 回应。多种细胞类型表达PTEN，因此PTEN抑制剂缺乏靶向PTEN所需的特异性 小胶质细胞中的信号。在一项先导性研究中，我们已经证明在1个月后髓系细胞中PTEN的缺失 在我们的模型中，抑制疾病相关的小胶质细胞反应和促炎信号。在这 新的应用，我们计划扩展这些研究，以进一步阐明PTEN在调节小胶质细胞中的作用 在脑损伤背景下的反应，并证明小胶质细胞特异性PTEN缺失是否可以缓解脑损伤 介导的神经炎症/神经变性和慢性功能结局。我们将比较TBI- 存在或不存在PTEN缺失的依赖性反应揭示小胶质细胞特异性靶点 与r-mTBI后的良好结果相关，并代表新的治疗靶点。我们将通过以下方式实现这一目标 利用他莫昔芬诱导的小鼠模型，该模型将特异性地靶向小胶质细胞中的PTEN缺失，而不是 其他髓系细胞(Hexbcre/PTENfl/fl)。我们将使用三个治疗时间窗来诱导PTEN缺失 (即，损伤前、早期和延迟)，并检查功能和病理生物学结果，scRNAseq图谱 伤后6个月小胶质细胞的功能活动。我们的目标是阐明PTEN作为一种负性基因的作用 R-mTBI慢性后遗症的小胶质细胞病理生物学调节因子，并鉴定独特的基因特征 PTEN缺失诱导的小胶质细胞修复机制可作为新的小胶质细胞 脑损伤和其他神经退行性疾病的特定靶点，在这些疾病中，神经炎症是关键因素。

Repetitive mild traumatic brain injury (r-mTBI) is one of the strongest risk factors for developing neurodegenerative diseases. To date, no disease modifying therapies have been developed to prevent the long- term consequences of TBI. There is a need to advance our current understanding of the cellular mechanisms driving the long-term neurological deficits after TBI, as this could lead to the identification of novel therapeutic targets. Neuroinflammation mediated by resident microglia is a common feature of human and animal models of TBI. Factors governing the propagation and persistence of disease associated microglial responses in the chronic sequelae of TBI remain elusive. We have established a mouse model of r-mTBI that recapitulates many features of human TBI and thus represents a translationally relevant preclinical platform. From this model we have generated a molecular library of microglia gene profiles, at a range of timepoints post-injury that provides a unique and detailed time-course of the microglial neuroinflammatory response to r-mTBI. Particularly, we reveal deficits in energy bioenergetics, cytokine signaling, lipid metabolism, and a pro-inflammatory signature of microglia at chronic timepoints, which appear to be driven by the activation of Phosphatase and Tensin Homolog (PTEN) signaling. PTEN is a lipid phosphatase that antagonizes phosphatidylinositol 3-Kinase signaling, a critical node vital for regulating cell survival, energy bioenergetics, autophagy and inflammation. PTEN is highly expressed in myeloid cells, and its dysregulation can trigger the activation of inflammatory responses. Multiple cell types express PTEN, thus PTEN inhibitors lack the specificity needed to target PTEN signaling in microglia. In a pilot study, we have shown that PTEN deletion in myeloid cells after 1 mo dampens disease associated microglial responses and proinflammatory signature in our model. In this new application, we plan to extend these studies to further clarify the role of PTEN in regulating microglia responses in the context of TBI and demonstrate whether microglia specific PTEN deletion can mitigate TBI mediated neuroinflammation/neurodegeneration and chronic functional outcomes. We will compare TBI- dependent responses in the presence or absence of PTEN deletion to reveal microglial specific targets that correlate with favorable outcomes after r-mTBI and represent novel therapeutic targets. We will achieve this by utilizing a tamoxifen inducible mouse model that will specifically target PTEN deletion in microglia and not other myeloid cells (Hexbcre+/PTENfl/fl). We will induce PTEN deletion using three therapeutic time-windows (i.e., pre-injury, early and delayed), and examine functional and pathobiological outcomes, scRNAseq profiles and functional activities of microglia at 6 mo post-injury. Our goal is to clarify the role of PTEN as a negative regulator of microglial pathobiology in the chronic sequelae of r-mTBI, and to identify unique gene signatures and reparative mechanisms in microglia induced by PTEN deletion that can be explored as novel microglial specific targets in TBI and other neurodegenerative diseases where neuroinflammation is a critical contributor.