Modulation of signaling from damage-associated molecular patterns to improve radiation-induced thymic dysfunction

项目总结 胸腺是T细胞产生的主要部位，对侮辱极其敏感，但也有一种 具有显著的内源性修复能力。即使可能有持续的胸腺退化和 在应对压力和感染等日常侮辱时再生，造成严重的胸腺损伤 辐射损伤会导致T细胞淋巴细胞减少时间延长。因此，确定可以提高T的治疗方法 在一定剂量的辐射后，受者的细胞重建显然是当务之急。 我们之前已经确定了两条不同的内源性胸腺再生途径，集中在 天然淋巴样细胞(ILCs)产生再生因子IL-22，内皮细胞(ECs)产生BMP4； 两者都通过靶向胸腺上皮细胞来调节其再生效果。最近我们发现 这些不同再生途径的触发取决于细胞死亡形式之间的平衡， 免疫沉默的凋亡(在稳定状态下胸腺细胞中大量存在)抑制了 再生程序。另一方面，在辐射损伤造成胸腺损伤后，我们发现了一个开关 导致免疫原性细胞死亡，导致损伤相关分子模式(DAMP)的释放 足以促进再生。具体地说，我们确定了辐射后细胞内锌的释放。 损伤，它可以通过G蛋白偶联受体39(GPR39)发出信号来刺激BMP4的产生 以及IL-23，IL-22产生的关键上游调节因子。另外，我们还发现， 典型的DAMP，ATP，能够通过嘌呤能(P2)受体直接在胸腺上皮细胞上发出信号 并促进其表达Foxn1，这是T细胞发育的关键微环境驱动因素。重要的是，我们的 初步数据还表明，这些途径中的每一条都可以作为改善胸腺的治疗靶点。 幼鼠受到辐射损伤后的恢复。根据我们的初步数据，我们假设 调节与这些阻尼剂相关的通路可以作为提高免疫力的对策 在辐射损伤后，通过刺激胸腺中新T细胞的产生来发挥作用。具体地说，我们的建议 其目的如下：(1)验证和优化GPR39或P2受体的靶向性，以改善 辐射损伤后新T细胞的产生和免疫功能；(2)检测胸腺对 对小鼠寿命和性别的再生信号做出反应；以及(3)综合评估 靶向GPR39或P2受体改善辐射损伤后小鼠胸腺功能的可能性 寿命和性生活。 这项提案中概述的研究不仅有可能确定 组织再生跨越寿命，但也可能导致创新的方法，以提高T细胞恢复 在辐射损伤之后。

PROJECT SUMMARY The thymus, which is the primary site of T cell generation, is extremely sensitive to insult, but also has a remarkable capacity for endogenous repair. Even though there is likely continual thymic involution and regeneration in response to everyday insults like stress and infection, profound thymic damage caused by radiation injury leads to prolonged T cell lymphopenia. Consequently, identification of therapies that can boost T cell reconstitution in recipients after a dose of radiation is a clear priority. We have previously identified two distinct pathways of endogenous thymic regeneration, centered on the production of the regeneration factors IL-22 by innate lymphoid cells (ILCs), and BMP4 by endothelial cells (ECs); both of which mediate their regenerative effects by targeting thymic epithelial cells. More recently we have found that the trigger for these distinct regenerative pathways hinge on the balance between forms of cell death, with immunologically silent apoptosis (which is abundant in thymocytes during steady-state) suppressive to the regenerative program. On the other hand, after thymic damage caused by radiation injury, we found a switch toward immunogenic cell death, with the resulting release of damage-associated molecular patterns (DAMPs) sufficient to promote regeneration. Specifically, we identified that intracellular Zn was released after radiation injury, where it could signal through the G-protein coupled receptor 39 (GPR39) to stimulate production of BMP4 and IL-23, a key upstream regulator of IL-22 production. Separately, we also found that the release of the prototypical DAMP, ATP, was able to signal directly on thymic epithelial cells through purinergic (P2) receptors and promote their expression of Foxn1, key microenvironmental drivers of T cell development. Importantly, our preliminary data also suggests that each of these pathways can be therapeutically targeted to improve thymic recovery following radiation damage in young mice. Based on our preliminary data, we hypothesize that modulation of pathways associated with these DAMPs can be used as a countermeasure to improve immune function after radiation injury by stimulating the generation of new T cells in the thymus. Specifically, our proposal has the following aims: (1) To validate and optimize the targeting of GPR39 or P2 receptors to improve the production of new T cells and immune function after radiation injury; (2) to examine the ability of the thymus to respond to regenerative signals across mouse lifespan and sex; and (3) to comprehensively evaluate the potential for targeting GPR39 or P2 receptors to improve thymic function after radiation damage across mouse lifespan and sex. The studies outlined in this proposal not only have the potential to define important pathways underlying tissue regeneration across lifespan but could also result in innovative approaches to enhance T cell recovery after radiation damage.