Mechanisms, Prevention and Treatment of Chronic GVHD

描述（由申请人提供）：我们的目标是开发慢性GVHD （cGVHD）的新疗法。我们建立了一种新的多器官系统损伤的cGVHD模型，并通过在组织中IgG沉积引起cGVHD的重要观察，推动了该领域的发展。生发中心（GCs）是B细胞产生分泌免疫球蛋白（Ig）的浆细胞（pc）的地方。GC的形成由滤泡辅助细胞（TFH）和TH17细胞支持，并由滤泡调节细胞（TFR）抑制。我们的中心假设是cGVHD是由GC促进和抑制细胞之间的平衡调节的，这可能是由PD-1和CD28信号调节的。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（cGVHD的靶点）上表达。RGMb在肺间质apc和支气管上皮细胞上表达。阻断RGMb/PD-L2通路可阻断呼吸耐受；其在cGVHD中的作用尚不清楚。虽然PD-1阻断会加重急性GVHD，但它在治疗cGVHD方面非常有效，这可能是因为PD-1阻断释放了对TFR抑制功能（Pr1）的抑制。cGVHD导致高tfr和低tfr。PD-1阻断可改变CD28信号转导、稳定性和功能，调节调节性T细胞（Tregs）、B细胞和pc。条件性靶向CD28影响TFHs、TH17s、TFRs和gc。CD28在这一平衡中的作用尚不清楚，但在cGVHD试验之前确定这一点很重要。通过磷脂酰肌醇3-激酶（PI3K）途径传递的TCR/CD28和IL-2R信号对于T细胞激活及其转录编程至关重要，影响T细胞代谢静息和激活的tnai、Teffs、Tmemory和Tregs使用不同的能量途径。阻断PI3K激活的PD-1连接可阻断cd28介导的糖代谢上调。在确定cGVHD的代谢途径后，我们将继续研究有利于TFRs、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紧张素同源物）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表达升高是否会增强cGVHD。相反，我们将测试p110d和pan-PI3K抑制剂，以确定靶向GC B细胞和cGVHD引起T细胞的PI3K是否可用于预防或治疗cGVHD。我们将验证PD1通路成员（aim 1A）和新型PD-L2受体（RGMb） （1B）独特地改变GC形成和cGVHD发病机制的假设。我们将验证CD28信号和激活PI3K的受体通过TFH/TFR平衡调节cGVHD的假设（2A）。我们将验证在cGVHD小鼠中支持脂质氧化（而不是糖酵解）将恢复TFH/TFR平衡的假设（2B）。该应用程序代表了4个实验室之间的全面合作：Blazar博士，Arlene Sharpe， Gordon Freeman和Larry Turka共同努力，以了解途径共刺激和共抑制途径在调节cGVHD中的作用，并为如何开发操纵这些途径治疗cGVHD的新策略提供见解。

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.