IDOL and dyslipidemia in cardiovascular diseases

摘要 尽管通过使用他汀类药物显著减少了主要血管事件， (CVD)仍然是导致死亡的主要原因。应对剩余风险的新策略包括 他汀类药物与依折麦布或PCSK 9抑制剂的联合治疗。最近的临床研究结果表明， 尽管联合治疗可有效地进一步降低LDL-C，但联合治疗不能成比例地降低LDL-C CV事件，可能来自仍然存在的相对较高的血浆甘油三酯。此外，一些患者 不能达到低LDL-C目标水平或药物不耐受，TG治疗困难。这些挑战 强调需要新的干预靶点和新的血脂异常治疗方法。体外 在小鼠模型中，IDOL被鉴定为靶向LDLR、VLDLR和ApoER 2的E3泛素连接酶， 降解和调节血浆脂质稳态独立的PCSK 9。此外，在遗传 流行病学研究IDOL与LDL-C和CVD结局以及功能丧失等位基因高度相关 导致极低的LDL-C和降低CVD风险。不幸的是，IDOL生物学的内在差异 小鼠和灵长类动物之间的差异，需要开发一种更接近人类的动物模型 IDOL生物学，以便将IDOL研究推进到转化竞技场。我们的初步研究表明 兔是一种更好的模型，可以测试IDOL作为临床相关靶点的可行性， 高脂血症和CVD。事实上，与小鼠不同，兔IDOL是在肝脏中响应LXR而诱导的 激动剂，与猴子和人类相同。IDOL基因敲除兔具有降低的LDL-C，并且在高脂肪时 高胆固醇饮食，保持低总胆固醇和低甘油三酯。我们将检验这个假设， 通过基因缺陷或小分子抑制剂降低IDOL蛋白表达水平或活性， 增加血浆脂质清除，降低高胆固醇血症、高胆固醇血症和炎症， 减少动脉粥样硬化。利用IDOL基因敲除、杂合子和野生型兔，我们将建立IDOL 作为目标1中减少动脉粥样硬化的治疗靶点，研究IDOL对肝脏介导的 血浆脂质清除率、饮食诱导的主动脉和冠状动脉粥样硬化以及新的 开发了小分子IDOL抑制剂。在目标2中，我们将深化IDOL KO效应的表征， 脂质处理的生理学和使用原代兔细胞，我们将定义IDOL依赖性机制， 肝细胞的脂质清除和对新型IDOL抑制剂的体外反应。人ipsc衍生 肝细胞和巨噬细胞结合功能的获得和丧失将解决肝细胞和巨噬细胞的保护问题。 跨物种的机制通过利用新的IDOL兔子模型来克服这些目标， 目前阻碍IDOL转化研究的障碍将提供令人信服的证据和新的发现 使IDOL转化研究成为一种新的可行目标，用于制定针对性干预措施， 高脂血症和心血管疾病管理，以进一步减少心血管疾病对全球的总体影响。

ABSTRACT Despite a significant reduction of major vascular events through the use of statins, cardiovascular disease (CVD) continues to be the leading cause of death. New strategies to address the residual risks include combination therapy of statins with ezetimibe or PCSK9 inhibition. Recent clinical findings indicate that, although effective in further reducing LDL-C, combination therapies do not proportionally translate in reduction of CV events, likely from the relatively high plasma triglycerides still present. Furthermore, some patients cannot reach the low LDL-C target levels or are drug intolerant and TG treatment is difficult. These challenges highlight the need for new targets for intervention and novel therapeutic approaches for dyslipidemia. In vitro and in mice models, IDOL was identified as an E3 ubiquitin ligase targeting LDLR, VLDLR and ApoER2 for degradation and regulating plasma lipid homeostasis independently of PCSK9. Furthermore, in genetic epidemiology studies IDOL was highly associated with LDL-C and CVD outcomes and loss-of-function alleles result in extremely low LDL-C and reduced CVD risk. Unfortunately, intrinsic differences in IDOL biology between mice and primates, create the need to develop an animal model that better approximates human IDOL biology in order to advance IDOL research into the translational arena. Our preliminary studies indicate that rabbits constitute a better model to test the feasibility of IDOL as a clinically relevant target for hyperlipidemia and CVD. Indeed, unlike in mice, rabbit IDOL is induced in the liver in response to LXR agonists, same as in monkeys and humans. IDOL knock-out rabbits have decreased LDL-C and upon high fat high cholesterol diet, maintain low total cholesterol and low triglycerides. We will test the hypothesis that reduced IDOL protein expression levels or activity -through gene deficiency or small molecule inhibitors- will increase plasma lipid clearance, reduce hypercholesterolemia, hypertriglyceridemia and inflammation, resulting in reduced atherosclerosis. Using IDOL knock-out, heterozygous and wild type rabbits, we will establish IDOL as a therapeutic target for reducing atherosclerosis in Aim 1, to study IDOL contribution to liver-mediated plasma lipid clearance, diet-induced atherosclerosis in aorta and coronary artery and the effects of newly developed small molecule IDOL inhibitors. In Aim 2, we will deepen the characterization of IDOL KO effects of the physiology of lipid handling and using primary rabbit cells we will define IDOL-dependent mechanisms in hepatocytes underlying lipid clearance and the response in vitro to novel IDOL inhibitors. Human iPSC-derived hepatocytes and macrophages combined with gain- and loss-of-function will address conservation of the mechanisms across species. Completion of these aims by leveraging new IDOL rabbit models to overcome the current barriers to advance IDOL translational research will provide compelling evidences and new findings to enable IDOL translational research as a novel feasible target for development of focused interventions for hyperlipidemia and CVD management in order to further reduce the overall global impact of CVD.