Mechanisms of free fatty acid receptor 4 signaling in the ischemic myocardium

项目摘要/摘要 冠心病(CHD)是导致发病率和死亡率的重要因素。两者之间的联系 炎症增加和冠心病的发病机制现在已经得到了很好的证实。炎症途径是所有 冠心病的主要致病因素包括动脉粥样硬化、斑块破裂、心肌缺血、再灌注损伤、 白细胞渗出，组织纤维化。然而，对更多候选疗法的需求仍未得到满足 降低冠心病死亡率。游离脂肪酸受体4(Ffar4)是一种G蛋白偶联受体，可被Long激活 链脂肪酸，包括ω3-多不饱和脂肪酸、二十碳五烯酸和二十二碳六烯酸 酸。Ffar4首先被鉴定为一种营养感受器，集中参与葡萄糖代谢的调节。 和脂肪生成。Ffar4也有抗炎和抗纤维化的作用：它表达在巨噬细胞上，以及 其刺激导致白细胞介素1β、白介素6、肿瘤坏死因子α的产生减少，并抑制内毒素-TLR4途径。 道路。最后，Ffar4在心脏成纤维细胞上表达，它的刺激导致转化生长因子-β1信号的减少 和胶原蛋白的产生。虽然Ffar4也在心肌细胞中表达，但它在心脏中的作用仍然存在 不清楚。我们先前的研究表明，EPA介导的纤维化和收缩功能障碍的减少 横动脉收缩引起的压力超负荷可能涉及EPA通过Ffar4的信号转导。怎么- 在系统性Ffar4缺失(Ffar4KO)的小鼠中，我们的初步数据显示，小鼠患有横断性主动脉瓣狭窄。 狭窄导致过度肥厚，更大的收缩和舒张期功能障碍，但没有夸大。 纤维化症。后者提示，不良适应反应是由心肌组织中Ffar4的缺失所致。 细胞。尽管有这些有趣的发现，但心肌细胞Ffar4在缺血再灌注损伤中的作用尚不清楚。 为人所知。因为许多炎症途径在压力超负荷后协调心脏重塑 与缺血再灌注(I/R)损伤后的通路重叠，因此我们假设，在心脏... 细胞，Ffar4可防止细胞死亡，并诱导有益的炎症反应，防止病理性重建- I/R损伤所致的Eling。为了测试这一点，我们将确定心肌细胞Ffar4的表达是否是必要的 防止I/R损伤。我们将产生心肌细胞特异性缺失Ffar4的小鼠，使它们 I/R损伤，并测量梗塞范围、心功能和纤维化。我们还将定义Ffar4信令网络 并确定该信号网络如何促进对心脏有益的免疫反应。 通过检测Ffar4对心肌细胞死亡、细胞因子和趋化因子产生的影响以及OX-4对心肌损伤的影响，来研究Ffar4对心肌细胞损伤的影响。 Ylipin产品。总之，Ffar4在调节心脏以外的炎症方面具有既定的作用；这 研究将确定它在心脏中的作用。它将推进多不饱和脂肪酸刺激的新范式 GPCRs作为信号分子发挥作用，维持心脏内环境的稳定。这项研究可以建立一个可以- Ffar4作为冠心病消炎新药靶点的研究

Project Summary/Abstract Coronary heart disease (CHD) is a significant contributor to morbidity and mortality. The association between increased inflammation and CHD pathogenesis is now well-established. Inflammatory pathways underlie all the major contributors to CHD, including atherogenesis, plaque rupture, myocardial ischemia, reperfusion injury, leukocyte infiltration, and tissue fibrosis. However, an unmet need remains for additional candidate therapies to reduce CHD mortality. Free fatty acid receptor 4 (Ffar4) is a G-protein coupled receptor that is activated by long chain fatty acids, including the ω3-polyunsatured fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid. Ffar4 was characterized first as a nutrient sensor, centrally involved in regulation of glucose metabolism and lipogenesis. Ffar4 also has anti-inflammatory and anti-fibrotic effects: it is expressed on macrophages, and its stimulation results in decreased production of interleukin-1β, IL6, TNFα, and inhibition of the LPS-TLR4 path- way. Finally, Ffar4 is expressed on cardiac fibroblasts, and its stimulation results in decreased TGF-β1 signaling and collagen production. Although Ffar4 also is expressed in cardiac myocytes, its role in the heart remains unclear. Our prior studies indicated that EPA-mediated reduction of fibrosis and contractile dysfunction following induction of pressure overload by transverse aortic constriction may involve EPA signaling through Ffar4. How- ever, our preliminary data in mice with systemic Ffar4 deletion (Ffar4KO) subjected to transverse aortic con- striction resulted in exaggerated hypertrophy, greater systolic and diastolic dysfunction, but without exaggerated fibrosis. The latter suggests that the maladaptive response was driven by the absence of Ffar4 in cardiac myo- cytes. Despite these interesting findings, the role of cardiac myocyte Ffar4 in ischemia reperfusion injury is un- known. Because many of the inflammatory pathways orchestrating cardiac remodeling after pressure overload overlap with pathways after ischemia and reperfusion (I/R) injury, we therefore hypothesize, that in cardiac my- ocytes, Ffar4 prevents cell death and induces a salutary inflammatory response that prevents pathologic remod- eling induced by I/R injury. To test this, we will determine if cardiac myocyte Ffar4 expression is necessary to protect against I/R injury. We will generate mice with cardiac myocyte-specific deletion of Ffar4, subject them to I/R injury, and measure infarct size, cardiac function, and fibrosis. We will also define the Ffar4 signaling network in cardiac myocytes, and determine how this signaling network promotes a salutary immune response to cardiac injury by measuring the influence of Ffar4 on myocyte cell death, cytokine and chemokine production, and ox- ylipin production. In summary, Ffar4 has an established role in regulating inflammation outside the heart; this study will define its role in the heart. It will advance a novel paradigm that polyunsaturated fatty acids stimulate GPCRs and function as signaling molecules to maintain cardiac homeostasis. This study can establish the can- didacy of Ffar4 as a new drug target for attenuation of inflammation in CHD.