PCSK9-A novel target for the treatment of myocardial ischemia

主要表达于肝、肾和小肠，酶原蛋白转换酶枯草杆菌/可信 9型(PCSK9)与低密度脂蛋白-胆固醇受体(LDLR)结合，导致降解 低密度脂蛋白。尽管没有得到证实，但已有研究表明，这些药物可能会减少心血管疾病 事件。我们课题组最近的研究表明，除了肝、肾和小肠外， 心肌细胞也表达PCSK9。PCSK9的分泌在缺血期间增加了10倍。 PCSK9在梗死区(交界区)附近表达最强。心肌细胞 在边境地区也表现出强烈的炎症和自噬。我们最近的其他工作 实验室表明，PCSK9的分泌可能调节炎症和自噬。基于这些 新的发现，我们希望批判性地检查心肌PCSK9在缺血中的作用，这一问题不是 以前研究过的。拨款建议的两个主要目的是： 目的1：探讨PCSK9在测定心肌梗死面积和心功能中的作用。 方法：这些研究将在永久性左冠状动脉(LCA)的小鼠模型中进行。] 结扎术。研究将在野生型C57BL/6和PCSK-/-小鼠身上进行。PCSK9表达， 炎症(重点是组织损伤性CCR2 Ly6、Chigh单核细胞和 中性粒细胞)和自噬以及梗死面积和心功能(超声心动图) 在不同的时间点测量。分子生物学研究、组织学和免疫组织化学将 在心脏的不同区域进行。确定炎症在PCSK9释放中的作用 和它的作用，将在肿瘤坏死因子α-/-小鼠和IL-1β-/-小鼠中进行平行研究。最后，为了确认 PCSK9在缺血性损伤中的作用，将在选择性缺失PCSK9的小鼠身上进行研究 心脏。影响：这些体内研究将阐明PCSK9在确定梗死面积和 心功能/重构。此外，这些研究将揭示炎症在诱导中的作用。 慢性缺血时PCSK9分泌的变化。 目的2：研究青蒿素对心肌缺血时S作用的机制。方法： 研究PCSK9、炎症和自噬在缺血过程中的复杂相互作用 小鼠心肌细胞将暴露于不同时期的低氧(体外研究)。我们会研究 低氧诱导PCSK9释放对白细胞迁移、线粒体ROS生成和细胞周期的影响 线粒体DNA损伤和自噬信号。PCSK9的影响(与炎症信号一起) 对胶原蛋白(在成纤维细胞中)的生成也将进行研究。影响：这些研究将揭示 PCSK9影响炎症和自噬，进而影响心脏的机制 慢性心肌缺血时的重塑。 创新和意义：通过降低低密度脂蛋白抑制PCSK9可能显著影响 动脉粥样硬化形成和心血管事件。我们相信，拟议中的研究将检验一部小说 假设是PCSK9的局部释放调节了促炎和自噬信号 和胶原生成(心脏重塑)。它的抑制可能调节心肌梗死的大小和 随后的心脏建模。这些创新研究的结果可能会影响数百万人的生活 患有慢性心肌缺血的患者(和老年退伍军人)可能会接受 PCSK9抑制剂。

Mainly expressed in liver, kidney and small intestine, the enzyme proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to the low-density lipoprotein-cholesterol receptor (LDLr), and causes degradation of LDLs. Although not proven, it has been suggested that these agents may reduce cardiovascular events. Recent work from our group shows that besides the liver, kidney and small intestine, cardiomyocytes also express PCSK9. The secretion of PCSK9 increases during ischemia by >10 fold. PCSK9 expression is maximal in the region adjacent to the infarcted area (border zone). Cardiomyocytes in the border zone also exhibit intense inflammation and autophagy. Other recent work in our laboratory suggests that PCSK9 secretion may regulate inflammation and autophagy. Based on these new findings, we wish to critically examine the role of myocardial PCSK9 in ischemia, an issue not previously studied. The 2 major aims of the grant proposal are: Aim 1: To examine the role of PCSK9 in the determination of infarct size and cardiac function. Approach: These studies will be done in a mouse model of permanent left coronary artery (LCA)] ligation. Studies will be performed in wild-type C57BL/6 and PCSK-/- mice. PCSK9 expression, inflammation (with emphasis on infiltration of tissue injurious CCR2+Ly6Chigh monocytes and neutrophils) and autophagy along with infarct size and cardiac function (echocardiography) will be measured at different time points. Molecular biology studies, histology and immunohistochemistry will be performed in different regions of the heart. To determine the role of inflammation in PCSK9 release and its effects, parallel studies will be performed in TNFα-/- mice and IL-1β-/- mice. Lastly, to confirm the role of PCSK9 in ischemic injury, studies will be performed in mice with selective PCSK9 deletion in the heart. Impact: These in vivo studies will clarify the role of PCSK9 in determination of infarct size and cardiac function/remodeling. Further, these studies will reveal the role of inflammation in the induction of PCSK9 secretion during chronic ischemia. Aim 2: To examine mechanisms underlying PCSK9’s effects on the heart during ischemia. Approach: To study the complex interaction between PCSK9, inflammation and autophagy during ischemia, primary mouse cardiomyocytes will be exposed to varying periods of hypoxia (in vitro studies). We will study the impact of hypoxia-induced PCSK9 release on leukocyte migration, mitochondrial ROS generation and mitochondrial DNA damage and autophagy signals. Impact of PCSK9 (along with inflammatory signals) on the generation of collagen (in fibroblasts) will also be studied. Impact: These studies will reveal the mechanisms by which PCSK9 influences inflammation and autophagy, and subsequently cardiac remodeling during chronic myocardial ischemia. Innovation and Significance: PCSK9 inhibition by lowering LDL-C may significantly influences atherogenesis and cardiovascular events. We believe that the proposed studies will test a novel hypothesis that it is the local release of PCSK9 that regulates pro-inflammatory and autophagy signals and collagen generation (cardiac remodeling). Its inhibition may modulate myocardial infarct size and subsequent cardiac modeling. The results of these innovative studies may impact the lives of millions of patients (and elderly veterans) who suffer from chronic myocardial ischemia and may be treated with PCSK9 inhibitors.