A new Chinese herb-derived selective Toll-like receptor antagonist (Project 1)

摘要： 动脉粥样硬化是心脏病发作和中风的直接原因，分别是美国的第一和第三大杀手。它是脂质沉积和慢性血管炎症的结果。Toll样受体（TLR）是先天免疫的关键成分，在动脉粥样硬化的每个阶段都起着有害的作用，其中TLR 2和TLR 4被最好地记录下来。在参与抵御入侵病原体的第一道防线的同时，TLR 2和TLR 4介导的信号传导被认为是动脉粥样硬化形成的驱动力。因此，TLR 2和TLR 4信号传导的阻断是动脉粥样硬化的一种有趣的治疗方法。然而，目前没有TLR 2或TLR 4拮抗剂被批准用于临床使用。近年来，我们从常用的中药三棱中分离得到一个新化合物，命名为Sparstolonin B（SsnB），并对其结构进行了研究。我们的初步研究表明：1）SsnB通过选择性阻断TLR 2和TLR 4信号传导对巨噬细胞具有有效的抗炎作用; 2）SsnB降低活化的内皮细胞吸引单核细胞粘附的能力，并减少动脉平滑肌细胞迁移; 3）SsnB有效抑制小鼠对脂多糖（LPS）的炎症反应。基于这些初步数据，我们假设SsnB可以通过其对TLR 2和TLR 4信号传导的选择性抑制作用而被开发为抗炎和抗动脉粥样硬化剂。为了验证这一假设，我们提出了三个具体目标。SA 1.阐明SsnB阻断TLR 2和TLR 4信号转导的分子机制。我们将表达和纯化TLR的Toll/IL-1受体（TIR）结构域、接头蛋白TIRAP/Mal和MyD 88，并检测SsnB与这些蛋白的结合。SA 2.检测SsnB对驻留血管细胞的影响。我们将检验SsnB通过阻断TLR 2和TLR 4信号传导抑制动脉内皮细胞和平滑肌细胞中的炎症表型的假设。SA 3.检验SsnB减弱小鼠动脉粥样硬化形成的假设。LDL受体（LDLR）缺陷小鼠将被喂食高脂肪饮食以诱导高胆固醇血症和动脉粥样硬化。将施用SsnB以测试其是否减弱这些小鼠中的动脉粥样硬化形成。总之，本研究将测试我们最近分离和表征的一种新的天然化合物的抗炎和抗动脉粥样硬化作用。SsnB通过阻断巨噬细胞和驻留血管细胞中的TLR 2和TLR 4信号传导而具有抗炎和抗动脉粥样硬化优点的假设的证实将引导该化合物开发成抗动脉粥样硬化剂。这项研究也将提供一个新的例子，补充和替代医学与现代药理学的桥梁。

Abstract: Atherosclerosis is the direct cause of heart attack and stroke, the No. 1 and No. 3 killers in the United States, respectively. It is the result of both lipid deposition and chronic vascular inflammation. Toll-like receptors (TLRs), the key components of innate immunity, play detrimental roles in every stage of atherosclerosis, with TLR2 and TLR4 being best documented. While participating in the first line of defense against invading pathogens, TLR2- and TLR4-mediated signaling is considered to be a driving force in atherogenesis. Thus, blockade of TLR2 and TLR4 signaling is an intriguing therapeutic approach for atherosclerosis. However, no TLR2 or TLR4 antagonists are currently approved for clinic use. Recently, in an effort to isolate and characterize single compounds from Sparganium stoloniferum tubers, a commonly used Traditional Chinese Medicine herb, we obtained a novel compound, designated Sparstolonin B (SsnB), and made exciting discoveries. Our preliminary studies show that 1) SsnB has potent anti-inflammatory effects on macrophages by selectively blocking TLR2 and TLR4 signaling; 2) SsnB diminishes the ability of activated endothelial cells to attract monocytes for adhesion, and decreases arterial smooth muscle cell migration; and 3) SsnB effectively suppresses inflammatory response to lipopolysaccharide (LPS) in mice. On the basis of these preliminary data, we hypothesize that SsnB can be developed as an anti-inflammatory and anti-atherogenic agent by virtue of its selective inhibitory effects on TLR2 and TLR4 signaling. To test this hypothesis, we propose three specific aims. SA1. To elucidate the molecular mechanism by which SsnB blocks TLR2 and TLR4 signaling. We will express and purify the Toll/IL-1 receptor (TIR) domains of TLRs, the adaptor proteins TIRAP/Mal and MyD88, and examine the binding of SsnB to these proteins. SA2. To examine the effects of SsnB on resident vascular cells. We will test the hypothesis that SsnB suppresses the inflammatory phenotype in arterial endothelial and smooth muscle cells by blocking TLR2 and TLR4 signaling. SA3. To test the hypothesis that SsnB attenuates atherogenesis in mice. LDL receptor (LDLR) deficient mice will be fed high fat diet to induce hypercholesterolemia and atherosclerosis. SsnB will be administrated to test if it attenuates atherogenesis in these mice. In summary, this study will test the anti-inflammatory and anti-atherogenic effects of a new natural compound recently isolated and characterized by us. The confirmation of the hypothesis that SsnB has anti-inflammatory and anti-atherogenic merit by blocking TLR2 and TLR4 signaling in macrophages and resident vascular cells will usher the development of this compound into an anti-atherogenic agent. This study will also provide a new example of complementary and alternative medicine bridging with modern pharmacology.