Mechanisms, Prevention and Treatment of Chronic GVHD

描述(由申请人提供)：我们的目标是开发治疗慢性移植物抗宿主病(CGVHD)的新疗法。我们建立了一个新的多器官系统损伤的cGVHD模型，并通过重要的观察到组织中的免疫球蛋白沉积导致了cGVHD，从而推动了该领域的发展。生发中心(GC)是B细胞产生浆细胞(PC)分泌免疫球蛋白(Ig)的场所。TFH和TH17细胞支持GC的形成，而TFR细胞则抑制GC的形成。我们的中心假设是，cGVHD受GC促进细胞和抑制细胞之间的平衡调节，这可能受PD-1和CD28信号的调节。弗里曼博士发现，PD-1配体PD-L1与B7-1结合，而PD-L2与排斥引导分子b(RGMb)结合。PD-L2在Th2、Th0和支气管上皮细胞上表达，是cGVHD的靶标。RGMb表达于肺间质APC和支气管上皮细胞。阻断RGMb/PD-L2通路可阻止呼吸耐受；其在cGVHD中的作用尚不清楚。PD-1阻断可加重急性移植物抗宿主病，但对慢性移植物抗宿主病的治疗效果显著，这可能是因为PD-1阻断解除了对TFR抑制功能(PR1)的抑制。慢性移植物抗宿主病导致高TFHs和低TFR。PD-1阻断可改变CD28信号、稳定性和功能，调节调节性T细胞(Tregs)、B细胞和PC。有条件地针对受CD28影响的TFH、TH17、TFR和GC。CD28在这一平衡中的作用尚不清楚，但在cGVHD试验之前了解这一点很重要。TCR/CD28和IL-2R信号途径通过磷脂酰肌醇3-激酶(PI3K)途径对T细胞的激活是必不可少的，它们的转录编程影响T细胞的静息和激活的Tnaive、Tffs、TMemory和Tregs使用不同的能量途径。PD-1的结扎可以阻止PI3K的激活，从而阻断CD28介导的葡萄糖代谢上调。在确定cGVHD的代谢途径后，我们将寻求有利于TFR与TFHs和GC B细胞的扰动。脂质磷酸酶PTEN(10号染色体上的磷酸酶和张力蛋白同源物)是主要的PI3K抑制剂。我们将在GC B细胞中测试PTEN缺乏的小鼠，以确定PI3K表达增强是否会增加cGVHD。相反，我们将测试p110d和PAN-PI3K抑制剂，以确定靶向GC B细胞中的PI3K和导致T细胞的cGVHD是否可以用于预防或治疗cGVHD。我们将检验以下假设：PD1通路成员(Aim 1A)和新的PD-L2受体(RGMb)(1B)独特地改变GC的形成和cGVHD的发病。我们将测试来自CD28和激活PI3K的受体的信号通过TFH/TFR平衡来调节cGVHD的假设(2A)。我们将验证这一假设，即有利于cGVHD小鼠的脂质氧化(相对于糖酵解)将恢复TFH/TFR平衡(2B)。这项应用代表了Blazar博士、Arlene Sharpe、Gordon Freeman和Larry Turka四个实验室之间的全面合作，共同努力使人们能够理解通路共刺激和共抑制通路在调节cGVHD中的作用，并为如何开发操作这些通路的新策略来治疗cGVHD提供见解。

DESCRIPTION (provided by applicant): Our goal is to develop new therapies for chronic GVHD (cGVHD). We developed a new cGVHD model of multi-organ system injury and advanced the field by making the important observation that IgG deposition in tissues causes cGVHD. Germinal centers (GCs) are sites where B cells produce plasma cells (PCs) that secrete immunoglobulin (Ig). GC formation is supported by Tfollicular helper (TFH) and TH17 cells, and suppressed by Tfollicular regulatory (TFR) cells. Our central hypothesis is that cGVHD is modulated by the balance between GC facilitating and suppressing cells, which may be regulated by PD-1 and CD28 signals. Dr. Freeman discovered the PD-1 ligand, PD-L1, binds to B7-1 while PD-L2 binds to repulsion guidance molecule b (RGMb). PD-L2 is expressed on Th2, Th0 and bronchial epithelial cells, a cGVHD target. RGMb is expressed on lung interstitial APCs and bronchial epithelial cells. Blocking the RGMb/PD-L2 pathway precludes respiratory tolerance; its role in cGVHD is unknown. While the PD-1 blockade worsens acute GVHD, strikingly, it is highly effective in treating cGVHD, perhaps because PD-1 blockade releases the restraint on TFR suppressor function (Pr1). cGVHD results in high TFHs and low TFRs. PD-1 blockade can alter CD28 signaling, stability and function, modulating regulatory T cells (Tregs), B cells and PCs. Conditionally targeting CD28 affected TFHs, TH17s, TFRs and GCs. The role of CD28 on this balance and is unknown but important to discern prior to cGVHD trials. TCR/CD28 and IL-2R signaling via the phosphatidylinositol 3-kinase (PI3K) pathway are essential for T cell activation, and their transcriptional programming, affecting T cell metabolism Resting and activated Tnaive, Teffectors (Teffs), Tmemory and Tregs use distinct energy pathways. PD-1 ligation, which prevents PI3K activation, blocks CD28-mediated upregulation of glucose metabolism. After determining metabolism pathways in cGVHD, we will pursue perturbations favoring TFRs vs TFHs and GC B cells. The lipid phosphatase PTEN (phosphatase and tensin homolog on chromosome 10) is the primary PI3K inhibitor. We will test mice with PTEN deficiency in GC B cells to determine whether heightened PI3K expression augments cGVHD. Conversely, we will test p110d and pan-PI3K inhibitors to determine whether targeting PI3K in GC B cells and cGVHD causing T cells can be used to prevent or treat cGVHD. We will test the hypotheses that the PD1 pathway members (aim 1A) and the novel PD-L2 receptor (RGMb) (1B) uniquely alter GC formation and cGVHD pathogenesis. We will test the hypotheses that signals from CD28 and receptors that activate PI3K modulate cGVHD via TFH/TFR balance (2A). We will test the hypothesis that favoring lipid oxidation (vs glycolysis) in cGVHD mice will restore TFH/TFR balance (2B). This application represents a full collaboration between 4 laboratories: Dr. Blazar, Arlene Sharpe, Gordon Freeman and Larry Turka to work together to enable understanding of the roles of pathways costimulatory and coinhibitory pathways in regulating cGVHD and provide insights into how to develop novel strategies for manipulating these pathways to treat cGVHD.