Lrg1 as a therapeutic target in Graft-versus-Host Disease

移植物抗宿主病(GVHD)是异基因造血干细胞移植(allo-HSCT)的主要并发症，导致相当大的死亡率。医学上需要新的治疗方法，因为使用免疫抑制药物的标准GVHD治疗会产生严重的不良影响，包括致命的感染和肿瘤复发。在我们以前的工作中，我们发现血管生成在GVHD过程中引发器官炎症，使治疗性抑制血管生成成为一种有吸引力的新方法，在不严重损害免疫的情况下减轻GVHD期间的炎症反应。然而，这种方法的主要障碍是缺乏合适的分子靶点，这些靶点在病理性血管生成和生理性血管生成过程中差异表达。富含亮氨酸的α-2-糖蛋白1(LRG1)可能是一个合适的靶点，因为它被证明参与了病理性血管生成，而对于生理性血管生成似乎是必不可少的。缺乏LRG1的小鼠发育正常，但病理性血管生成显著减少。LRG1与转化生长因子-β-1(转化生长因子-β-1)辅助受体endoglin结合，促进内皮细胞促血管生成信号转导通路。LRG1抗体阻断可抑制这一促血管生成开关并减弱血管生成。我们的初步研究结果表明：1)在GVHD过程中，LRG1在靶器官中表达上调。2)LRG1缺陷小鼠可减轻实验性GVHD和结肠炎。因此，我们假设LRG1可作为GVHD的治疗靶点。我们建议在小鼠allo-HSCT模型和临床标本中进行研究，具体目的如下：目的1.实验性GVHD中LRG1缺失的遗传和药物作用及其产生机制目的2.不同体外研究中LRG1缺失的功能和机制分析3.LRG1在人GVHD中的表达和细胞、分子和临床变化的分析计划的实验结果将有助于：-更好地理解病理性血管生成在GVHD中的作用和LRG1对其调节的作用。-针对GVHD和可能的其他炎症性疾病的LRG1治疗策略的翻译开发。

Graft-versus-host disease (GVHD) is the main complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT) causing considerable mortality. There is a medical need for novel therapies because standard GVHD treatments with immunosuppressive drugs have severe unwanted effects including fatal infection and tumor relapse. In our previous work, we found that angiogenesis initiates organ inflammation during GVHD, making therapeutic inhibition of angiogenesis an attractive novel approach to reduce inflammation during GVHD without severely impairing immunity. The main obstacle to this approach, however, has been the lack of suitable molecular targets, which are differentially upregulated during pathological angiogenesis and physiological angiogenesis. Leucine-rich alpha-2-glycoprotein 1 (Lrg1) could be such a suitable target, as it has been demonstrated to be involved in pathological angiogenesis, whereas it appears to be dispensable for physiological angiogenesis. Mice lacking Lrg1 develop normally, but exhibit a significant reduction in pathological angiogenesis. Lrg1 binds to transforming growth factor-β1 (TGF-β1) accessory receptor endoglin and promotes the pro-angiogenic Smad1/5/8 signaling pathway in endothelial cells. Lrg1 antibody blockade inhibits this pro-angiogenic switch and attenuates angiogenesis. Results from our preliminary studies suggest that:1) Lrg1 is upregulated in target organs during GVHD. 2) Experimental GVHD and colitis are attenuated in Lrg1-deficient mice.We therefore hypothesize that Lrg1 can be used as a therapeutic target in GVHD.We propose studies in murine allo-HSCT models and in clinical samples with the following specific aims:Aim 1. Genetic as well as pharmacologic Lrg1 depletion in experimental GVHD and mechanisms of Lrg1 production Aim 2. Functional and mechanistic analyses of Lrg1 depletion in different in vitro studiesAim 3. Lrg1 expression in human GVHD and analyses of cellular, molecular and clinical alterationsThe results from the planned experiments will contribute to: - A better understanding of the role of pathological angiogenesis during GVHD and its regulation by Lrg1. - The translational development of therapeutic strategies targeting Lrg1 in GVHD and possibly in other inflammatory diseases.