VEGF-C/VEGFR3 AND LYMPHATIC TRANSPORT OF CHOLESTEROL FROM ATHEROSCLEROTIC PLAQUE

描述（由申请人提供）：我们的长期目标是了解如何从斑块中去除巨噬细胞和胆固醇以促进疾病消退。我们最近发现，淋巴管是将胆固醇从动脉壁和其他组织中移除的管道。逆向胆固醇转运（RCT）是指胆固醇从体内通过粪便排出体外的过程。就动脉粥样硬化而言，巨噬细胞动员胆固醇进行清除和排泄是最相关的。多年来，关于胆固醇如何从巨噬细胞中动员并装载到高密度脂蛋白（HDL- c）上的细节出现了许多。然而，人们对高密度脂蛋白胆固醇如何从组织（包括动脉壁的动脉粥样硬化斑块）中出来，在进入排泄途径之前返回血浆所知甚少。在20世纪80年代早期，一些临床或实验观察结果使一些医生提出了淋巴运输受损与动脉粥样硬化之间的联系。然而，除了一项令人信服的研究估计HDL-C通过人体淋巴的净通量很大外，淋巴管在随机对照试验中的定量重要性尚未得到检验。最近，我们利用实验小鼠模型，其中淋巴流动的通畅可以通过手术或遗传方法调节。在皮肤中，我们能够完全消除淋巴流，这使我们能够证明淋巴是巨噬细胞RCT后胆固醇动员到血浆的定量主要途径。在受动脉粥样硬化影响的主动脉壁中，我们也采用手术方法以脉冲追踪的方式追踪斑块中的氘标记胆固醇（[2H] d6 -胆固醇；d6 -胆固醇）。用抗vegfr3单抗阻断或不阻断淋巴血管再吻合后，将主动脉手术移植到受者体内。这种阻断显著地保留了动脉粥样硬化主动脉中的D6-胆固醇，提示其起关键作用

DESCRIPTION (provided by applicant): Our long-term goal is to understand how to remove macrophages and cholesterol from plaques to promote disease regression. We recently discovered that lymphatic vessels serve as the conduits by which cholesterol is removed from the artery wall and other tissues. Reverse cholesterol transport (RCT) is the process by which cholesterol is mobilized from the body for excretion through the feces. With respect to atherosclerosis, the mobilization of cholesterol from macrophages for removal and excretion is most relevant. Over the years, many details emerged regarding how cholesterol is mobilized from macrophages to be loaded onto HDL (HDL-C). However, little was known about how HDL-cholesterol subsequently makes its way out of tissues, including sites like atherosclerotic plaques of the artery wall, to return to plasma before entering pathways for excretion. A handful of clinical or experimental observations led a few physicians in the early 1980's to propose a connection between impaired lymphatic transport and atherosclerosis. However, the quantitative importance of lymphatic vessels in RCT had not been examined, aside from a compelling study that estimated that the net flux of HDL-C through human lymph is substantial. Recently, we utilized experimental mouse models where the patency of lymphatic flow could be modulated by surgical or genetic methods. In skin, we were able to fully abrogate lymphatic flow allowing us to demonstrate that lymphatics are quantitatively the major route for cholesterol mobilization to plasma following macrophage RCT. In atherosclerosis-affected aortic walls, we also used a surgical approach to track deuterium-labeled cholesterol ([2H] D6-cholesterol; D6-cholesterol) from plaques in a pulse-chase manner. Aortas were surgically transplanted into recipients with re-anastomosis of the lymphatic vasculature blocked or not with anti-VEGFR3 mAb. This blockade significantly retained D6- cholesterol in the atherosclerotic aorta, suggesting a key role for lymphatic vessels in cholesterol mobilization from the aorta as observed in skin. In aim 1, we will take a critical next step with refined approaches that will allow us to better quantify the roe of lymphatic vessels in cholesterol removal from the aorta and to assess whether the blockade on lymphatics is truly acting locally at the aortic wall. In preliminary data, we show that treatin apoE-/- mice with VEGF-C, the ligand for VEGFR3, restores impaired lymphatic transport that occurs following hypercholesterolemia, allowing us to test the hypothesis that VEGF-C acts on lymphatic vessels to therapeutically sustain a critical route for cholesterol transport out of plaques after macrophage cholesterol efflux is stimulated. This hypothesis raises a fundamental question not yet addressed in the field: does effective plaque regression truly depend upon cholesterol removal from plaques, only upon cholesterol removal from macrophages, or perhaps neither? Our study design is ideal to address this fundamental issue while simultaneously digging deeply into a new concept that supporting lymphatic vessel function may help resolve inflammation in the atherosclerotic plaque.