Cannabinoid-mediated mitigation of graft versus host disease: Roles of CB2 receptors and adenosine signaling

移植物抗宿主病(GVHD)是异基因造血干细胞相关的主要并发症。 细胞移植，其特点是急性期和慢性期都有不同 病理生理机制。尽管使用的药物策略主要是基于 在给予钙调神经磷酸酶类药物方面，急性和慢性移植物抗宿主病仍然是主要的临床应用。 有问题。在初步研究中，我们已经确认了通过大麻素2型的信号 受体(CB2R)可减轻急性移植物抗宿主病(GVHD)的严重程度，并在减轻纤维化方面发挥关键作用 慢性移植物抗宿主病。此外，我们还发现，非精神活性的植物大麻素， 大麻二醇(CBD)也可抑制GVH的反应性并增强腺苷信号转导。基于这些 研究表明，我们的总体假设是，大麻类物质可以减轻急性和非典型肺炎的严重程度。 慢性移植物抗宿主病，这些抗炎作用是机械介导的 通过CB2R和腺苷受体信号通路。特定目标的研究1 将利用一种新的CB2R报告小鼠模型，该模型具有侧翼的lox P位点，将允许我们既 确定表达CB2R的关键免疫细胞群，然后消除这些已识别的 正式测试这些细胞在急性移植物抗宿主病生物学中的功能作用。我们还将雇佣几名 临床相关的药理学方法来确定是否直接和选择性地给药 CB2R激动剂或抑制2-花生四烯基甘油(2-AG)降解的药物，其 是CB2R的主要内源性配体，可以减轻本病的严重程度。具体的研究 目标2将定义CBD在减轻急性移植物抗宿主病严重程度方面的作用 验证CBD调节GVHD假说的药理拮抗剂和遗传策略 通过腺苷2A受体(A2AR)信号通路。我们还将研究CBD是否 通过增强调节性T细胞的重建并稳定这些细胞中Foxp3的表达 腺苷信号。在特定目标3的实验将确定大麻素信号 防止慢性移植物抗宿主病相关纤维化的发展，这是这种疾病的一个标志。 具体地说，我们将定义关键的CB2R表达免疫细胞群体，这些细胞群体存在于 慢性移植物抗宿主病的纤维化期，并使用细胞特异性Cre-lox缺失方法来定义 CB2R在已鉴定细胞中表达的功能意义。我们还将评估是否有 直接CB2R激动剂、抑制2-AG降解的药物的药理给药，以及 CBD可预防慢性移植物抗宿主病相关纤维化。这些研究的总体目标是定义 大麻素调节急性和慢性移植物抗宿主病的机制，并测试临床相关性 旨在减轻异基因造血干细胞并发症的策略 移植受者。

Graft versus host disease (GVHD) is the major complication associated with allogeneic hematopoietic stem cell transplantation, and is characterized by both acute and chronic phases which have different pathophysiological mechanisms. Despite the use of pharmacological strategies which are primarily based on the administration of calcineurin-based agents, both acute and chronic GVHD remain major clinical problems. In preliminary studies, we have identified that signaling through the cannabinoid type 2 receptor (CB2R) mitigates the severity of both acute GVHD and also plays a pivotal role in reducing fibrosis in chronic GVHD. Moreover, we have discovered that that the nonpsychoactive, phytocannabinoid, cannabidiol (CBD) also inhibits GVH reactivity and potentiates adenosine signaling. Based on these studies, our overall hypothesis is that cannabinoids mitigate the severity of both acute and chronic GVHD, and that these anti-inflammatory effects are mechanistically mediated through the CB2R and the adenosine receptor signaling pathways. Studies in Specific Aim 1 will utilize a novel CB2R reporter mouse model that has flanking lox P sites that will allow us to both identify the critical immune cell populations that express the CB2R, and then eliminate these identified cells to formally test a functional role for these cells in acute GVHD biology. We will also employ several clinically relevant pharmacological approaches to determine whether administration of direct and selective CB2R agonists or, alternatively agents that inhibit the degradation of 2-arachidonyl glycerol (2-AG) which is the major endogenous ligand for the CB2R, can reduce the severity of this disease. Studies in Specific Aim 2 will define the role of CBD in mitigating the severity of acute GVHD by using selective pharmacological antagonists and genetic strategies to test the hypothesis that CBD regulates GVHD through the adenosine 2A receptor (A2AR) signaling pathway. We will also examine whether CBD augments the reconstitution of regulatory T cells and stabilizes Foxp3 expression in these cells through adenosine signaling. Experiments in Specific Aim 3 will determine whether cannabinoid signaling prevents the development of chronic GVHD-associated fibrosis which is a hallmark of this disease. Specifically, we will define the critical CB2R expressing immune cell populations which are present during the fibrotic phase of chronic GVHD and use cell-specific Cre-lox deletion approaches to define the functional significance of CB2R expression in identified cells. We will also assess whether either pharmacological administration of direct CB2R agonists, agents that inhibit the degradation of 2-AG, and CBD can prevent chronic GVHD-associated fibrosis. The overall goal of these studies is to define the mechanisms by which cannabinoids modulate both acute and chronic GVHD, and to test clinically relevant strategies that are designed to mitigate these complications in allogeneic hematopoietic stem cell transplant recipients.