Mechanistic Inflammatory Pathways in Graft Versus Host Disease

项目摘要 移植物抗宿主病（GVHD）是同种异体移植的主要并发症， 造血干细胞移植（HSCT）。对皮肤的病理性损伤， 胃肠道和肝脏是这种疾病的标志;然而，GVHD也可以诱导 中枢神经系统（CNS）炎症以及认知和行为改变 在病人身上。我们以前观察到宿主白细胞介素6（IL-6）的产生和相关的 CNS驻留巨噬细胞（小胶质细胞）的扩增似乎在诱导 但是阻断IL-6信号传导并不能完全减轻疾病 严重性。在初步研究中，我们现在已经确定了内源性大麻素信号通过 2型大麻素受体（CB 2 R）和犬尿氨酸代谢途径作为新的IL-6- 炎症在大脑中传播的独立机制。的总目标 这一建议是验证和表征这两个假定的机制途径， GVHD诱导大脑中的炎症，并确定它们如何调节全身性炎症。 这种疾病的表现。我们的总体假设是， GVHD可归因于CNS驻留的巨噬细胞，其诱导炎症 和行为功能障碍通过内源性大麻素信号和 犬尿氨酸代谢途径。具体目标1中的研究将确定CB 2 R的作用 CNS信号传导阻断和GVHD的全身表现。我们会委聘 直接拮抗CB 2 R受体信号传导的药理学和遗传学方法， 抑制CB 2 R的天然内源性大麻素配体2-AG的合成，以解决这一问题 问题具体目标2中的实验将确定CNS上的CB 2 R表达是否 驻留的巨噬细胞对于介导GVHD诱导的炎症至关重要。我们将利用小说 具有侧翼lox p位点的CB 2 Rfl/fl小鼠，其在繁殖时允许细胞特异性缺失 与适当的血统特异性Cre动物。具体目标3中的研究将确定以下方面的作用： 犬尿氨酸途径在中枢神经系统和全身性炎症的病理生理学中， 移植物抗宿主病我们将确定CNS驻留巨噬细胞是否是主要来源， 的神经毒性犬尿氨酸代谢物，并确定是否抑制这一途径使用这两个 遗传和药理学方法可预防大脑和外周的炎症。的 总体目标是定义负责的相关生化和免疫途径 GVHD相关的神经炎症，以促进临床相关的 在患有血癌的同种异体HSCT患者中减轻这种并发症的策略。

PROJECT SUMMARY Graft versus host disease (GVHD) is the major complication associated with allogeneic hematopoietic stem cell transplantation (HSCT). Pathological damage to the skin, gastrointestinal tract, and liver are hallmarks of this disease; however, GVHD can also induce inflammation in the central nervous system (CNS) as well as cognitive and behavioral alterations in patients. We previously observed that host interleukin 6 (IL-6) production and the associated expansion of CNS resident macrophages (microglia) appear to have critical roles in the induction of neuroinflammation, but that blockade of IL-6 signaling does not completely mitigate disease severity. In preliminary studies, we have now identified endocannabinoid signaling through the type 2 cannabinoid receptor (CB2R) and the kynurenine metabolic pathway as novel IL-6- independent mechanisms by which inflammation is propagated in the brain. The overall goal of this proposal is to validate and characterize these two putative mechanistic pathways by which GVHD induces inflammation in the brain and ascertain how they modulate systemic manifestations of this disease. Our overall hypothesis is that inflammation during GVHD is attributable to CNS resident macrophages which induce inflammation and behavioral dysfunction through both the endocannabinoid signaling and kynurenine metabolic pathways. Studies in Specific Aim 1 will define the effect of CB2R signaling blockade on CNS and systemic manifestations of GVHD. We will employ pharmacological and genetic approaches that directly antagonize CB2R receptor signaling or inhibit the synthesis of 2-AG, the natural endocannabinoid ligand of the CB2R, to address this question. Experiments in Specific Aim 2 will determine whether expression of the CB2R on CNS resident macrophages is critical for mediating GVHD-induced inflammation. We will utilize novel CB2Rfl/fl mice which have flanking lox p sites which will allow for cell-specific deletion when bred with appropriate lineage-specific Cre animals. Studies in Specific Aim 3 will define the role of the kynurenine pathway in the pathophysiology of CNS and systemic inflammation that occur during GVHD. We will determine whether CNS resident macrophages are the dominant source of neurotoxic kynurenine metabolites, and define whether inhibition of this pathway using both genetic and pharmacological approaches prevents inflammation in the brain and periphery. The overall goal is to define relevant biochemical and immunological pathways that are responsible for GVHD-associated neuroinflammation in order to foster the development of clinically relevant strategies to mitigate this complication in allogeneic HSCT patients with blood cancers.