PCSK9-A novel target for the treatment of myocardial ischemia

主要表达于肝、肾和小肠，酶前蛋白转化酶枯草杆菌蛋白酶/kexin 9型（PCSK 9）与低密度脂蛋白胆固醇受体（LDLr）结合，并导致降解 的LDL。虽然尚未证实，但已表明这些药物可减少心血管疾病， 事件我们小组最近的工作表明，除了肝脏，肾脏和小肠， 心肌细胞也表达PCSK 9。PCSK 9的分泌在缺血期间增加>10倍。 PCSK 9表达在邻近梗塞区域的区域（边界区）中最大。心肌细胞 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，PCSK 9分泌可能调节炎症和自噬。基于这些 新的发现，我们希望严格审查心肌PCSK 9在缺血中的作用，一个问题， 以前研究过。拨款建议的两个主要目的是： 目的1：研究PCSK 9在确定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] 结扎将在野生型C57 BL/6和PCSK-/-小鼠中进行研究。PCSK 9表达， 炎症（强调组织损伤性CCR 2 + Ly 6C高单核细胞的浸润， 中性粒细胞）和自噬沿着梗死面积和心脏功能（超声心动图）将被 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 在心脏的不同部位进行。确定炎症在PCSK 9释放中的作用 及其作用，将在TNFα-/-小鼠和IL-1β-/-小鼠中进行平行研究。最后，为了确认 PCSK 9在缺血性损伤中的作用，将在具有选择性PCSK 9缺失的小鼠中进行研究， 心脏影响：这些体内研究将阐明PCSK 9在确定梗死面积和预后中的作用。 心脏功能/重塑。此外，这些研究将揭示炎症在诱导中的作用。 PCSK 9分泌的变化。 目的2：研究PCSK 9在缺血期间对心脏作用的潜在机制。方法： 研究缺血期间PCSK 9、炎症和自噬之间的复杂相互作用， 小鼠心肌细胞将暴露于不同时期的缺氧（体外研究）。我们会研究 缺氧诱导PCSK 9释放对白细胞迁移、线粒体ROS生成和 线粒体DNA损伤和自噬信号。PCSK 9的影响（沿着炎症信号） 也将研究对胶原蛋白（在成纤维细胞中）生成的影响。影响：这些研究将揭示 PCSK 9影响炎症和自噬的机制，以及随后的心脏 慢性心肌缺血期间的重构。 创新和意义：通过降低LDL-C抑制PCSK 9可能显著影响 动脉粥样硬化和心血管事件。我们相信，拟议中的研究将测试一部小说， 这是一种假设，即PCSK 9的局部释放调节促炎和自噬信号 和胶原蛋白生成（心脏重塑）。其抑制可调节心肌梗死面积， 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）， PCSK 9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.