A Critical Role for Leukotriene B4 in Lymphedema

项目总结/摘要 淋巴水肿是一种慢性和使人衰弱的疾病，目前没有批准的药物治疗。最近 研究表明炎症在这种疾病中起着中心作用。我们发现白三烯B4（LTB 4）， 一种重要的炎症脂质介质，促进淋巴管内皮细胞（LEC）发芽和生长， 浓度（10 nM），并在高浓度（200 nM）下通过差异性影响两个 重要的淋巴存活途径，VEGFR 3和Notch。在临床前水肿进展期间， 淋巴液LTB 4浓度从最初的促淋巴管生成浓度上升到抗淋巴管生成浓度。 可能诱发病理的淋巴管生成范围。抗LTB 4治疗逆转临床前水肿。 这一发现是2期临床试验（ULTRA）的科学基础，该试验目前正在测试 LTB 4靶向治疗水肿。一项独立的概念验证临床试验的新结果是积极的， 这是第一个有效的药物治疗这种情况。即使抗LTB 4治疗可能是 虽然对水肿有帮助，但可能没有疗效，需要更多的信息来了解如何治疗 炎症途径促进疾病。补助金中提出的研究旨在解决基本的 关于LTB 4如何损害毛细淋巴管并促进促炎性细胞因子的机制问题 微环境我们的总体假设是，淋巴损伤后，LTB 4的增加加剧了 通过抑制关键的淋巴生长途径，干扰（血液）微血管循环， 转化LEC并重新定向免疫微环境。 为了解决这些问题，本提案分为以下三个具体目标。目的1是研究 LTB 4改变促淋巴管生成信号通路的机制，导致血管重塑 并改变LEC细胞的身份。目的2将研究LTB 4如何影响免疫微环境， 通过影响促炎性树突状细胞和T淋巴细胞的活化和表型来减轻水肿 以及通过改变淋巴免疫调节功能。最后，Aim 3将使用组学技术来评估 ULTRA试验收集的临床水肿样本，用于评估围绕LTB 4构建的遗传网络 生物学中的水肿。 这些研究的目的是了解修复性淋巴管生成的分子机制， LEC识别的可塑性和水肿免疫调节的动力学。通过仔细评估 免疫微环境和全球转录组在水肿，它应该有可能进化得更好， 药物治疗这种普遍存在的，否则，不懈的条件。

PROJECT SUMMARY / ABSTRACT Lymphedema is a chronic and debilitating condition currently without approved medical therapies. Recent investigations suggest a central role for inflammation in this disease. We discovered that leukotriene B4 (LTB4), a critical lipid mediator of inflammation, promotes lymphatic endothelial cell (LEC) sprouting and growth at low concentrations (10nM), and causes LEC injury at high concentrations (200nM) by differentially affecting two essential lymphatic survival pathways, VEGFR3 and Notch. During pre-clinical lymphedema progression, lymphatic fluid LTB4 concentrations rise from initial pro-lymphangiogenic concentrations, into an anti- lymphangiogenic range which may induce pathology. Anti-LTB4 therapy reverses pre-clinical lymphedema. This finding is the scientific basis for a Phase 2 clinical trial (ULTRA), which is currently testing the efficacy of LTB4-targeted therapy for lymphedema. New results from a separate proof-of-concept clinical trial are positive, making this the first effective medicinal therapy for this condition. Even though anti-LTB4 therapy may be helpful for lymphedema, it is likely not curative, and more information is needed to understand how inflammatory pathways promote disease. Studies proposed in the grant are designed to address fundamental mechanistic questions about how LTB4 damages lymphatic capillaries and promotes a proinflammatory microenvironment. Our global hypothesis is that after lymphatic injury, increased LTB4 exacerbates lymphedema by inhibiting key lymphatic growth pathways, interfering with the (blood) microvascular circulation, transforming LECs and redirecting the immune microenvironment. To address these issues, this proposal is divided into three Specific Aims as follows. Aim 1 is to study the mechanisms by which LTB4 alters pro-lymphangiogenic signaling pathways, causes blood vascular remodeling and changes LEC cellular identity. Aim 2 will investigate how LTB4 impacts the immune microenvironment in lymphedema by influencing the activation and phenotype of proinflammatory dendritic cells and T lymphocytes and by changing lymphatic immunoregulatory functions. Finally, Aim 3 will use omic technologies to evaluate clinical lymphedema samples collected by the ULTRA trial to assess the genetic networks built around LTB4 biology in lymphedema. The goals of these studies are to understand the molecular mechanisms of reparative lymphangiogenesis, the plasticity of LEC identify and the dynamics of immune regulation in lymphedema. By carefully assessing the immune microenvironment and the global transcriptome in lymphedema, it should be possible to evolve better drug therapies for this pervasive and, otherwise, unremitting condition.