载脂蛋白A-I模拟肽对肥胖及肥胖并心肌梗死后心功能的影响及可能机制

Our previous studies revealed that ApoA-I mimetic peptide (L-4F) can reduce the body weight and improve the heart function of diabetic mice via upregulation of heme oxygenase 1 (HO-1) and adiponectin. We hypothesis that downregulated HO-1 and adiponectin levels is one of the key factors which caused the development of obesity and obesity combined with post-infarcted heart failure. Overexpression of HO-1 and adiponectin may prevent the poor prognosis of obesity through anti-inflammation, anti-oxidation, anti-apoptosis, improving vascular endothelial function and so on, but the signaling pathway is not clear. To test the effect of L-4F, an HO-1 inducer, on the extent of obesity, the cardiac function and left ventricular remodeling,an obese and obese combined with myocardial infarction model will be made. And the regular methods such as echocardiography, hemodynamic testing, pathological examination will be performed in this study. Expression of HO-1/2, adiponectin, PPARγ (peroxisome proliferator activated receptor γ), C /EBPα (CCAAT / enhancer binding protein α), Wnt10b(one of wingless-type MMTV integration site family members), and Sonic Hedgehog (Shh), which may involve in obesity and myocardial remodeling, will be valued via methods of Western blot or RT-PCR. Also the vascular endothelial function, levels of cytokines, inflammatory factors, oxidative stress in serium or myocardial tissues will be measured. Furthermore, to test the effect of L-4F on adipocyte and myocardial cells, besides the animal model, cell culture will also be performed in this study. ..Via the above comparative experiments, we try to explain the valuable effects of L-4F and the possible mechanisms, thus we can do something helpful for the prevetion of obesity, myocardial infarction and heart failure by the development of gene therapy or new medication.

我们的前期研究证实载脂蛋白A-I模拟肽(L-4F)能上调血红素氧合酶1（HO-1）和脂联素、并减轻糖尿病鼠体重及一定程度改善其心功能。我们推测HO-1和脂联素的下调可能是肥胖及肥胖并心肌梗死后心力衰竭发生发展的关键因素之一，上调HO-1和脂联素可能通过抗氧化应激、抗炎症反应、抗凋亡和改善血管内皮功能等途径拮抗肥胖并改善其预后，但可能的分子机制尚不清楚。本课题采用Jons法将肥胖大鼠制备成心肌梗死模型，应用心脏超声、有创血流动力学检测以及病理学等方法观察L-4F（HO-1诱导剂）及HO-1抑制剂锡中卟啉对肥胖及肥胖鼠梗死后心室重构及心功能相关指标的影响。同时检测相关的炎性因子、细胞因子、氧化应激水平以及血管内皮功能，并采用Western Blot、RT-PCR法检测相关蛋白基因的表达，从动物模型到细胞水平等不同层面深入探讨相关的信号转导通路，以期对肥胖、心肌梗死和心衰防治新靶点提供新的依据。

研究背景：前期研究证实L-4F能够减轻糖尿病大鼠体重及一定程度改善其心功能；我们推测L-4F能够通过上调HO-1及脂联素的水平发挥抗氧化、抗炎症、抗凋亡等作用，从而改善肥胖和肥胖合并心肌梗死后的心功能。. 研究内容(分为四部分)：第一部分以7w龄雄性SD大鼠为研究对象，探讨L-4F对肥胖大鼠心功能的影响及可能机制。第二部分在肥胖大鼠模型基础上采用Jons法建立肥胖合并心肌梗死的大鼠模型，探讨L-4F对肥胖及肥胖并心肌梗死大鼠心功能的影响及可能机制。第三部分以脂肪细胞为研究对象,探讨L-4F对脂肪细胞炎症反应的影响机制。第四部分以心肌细胞为研究对象，探讨L-4F对心肌细胞缺氧复氧后功能的影响及可能机制。. 重要结果：①与对照组相比，L-4F干预组大鼠的体重、血压、血糖和胰岛素显著降低，腹部脂肪明显减少；心功能明显好转；炎症反应、氧化应激和血管内皮功能得到显著改善；心肌组织的内质网应激水平显著下降。②应用HO-1抑制剂SnMP明显阻断了L-4F上调HO-1后对心功能的改善作用，使炎症反应、氧化应激水平和血管内皮功能均进一步恶化，内质网应激也更加明显；③与对照组及SnMP抑制剂使用组相比较，L-4F干预组HO-1和APN在心肌组织的表达不同程度升高，Wnt10b、β-catenin和Shh表达也升高，PPARγ、C/EBPα和Peg1/mest表达降低。④与对照组相比，L-4F干预组脂肪细胞的炎症反应明显减轻；⑤心肌细胞缺氧复氧后，与对照组相比，L-4F干预组的细胞凋亡率明显减低，细胞活性明显增高，氧化应激明显减轻。. 重要结论： ①L-4F能够上调肥胖及肥胖合并心肌梗死大鼠的HO-1和APN表达，降低体重和腹部脂肪含量，减轻胰岛素抵抗，并通过降低炎症反应、改善氧化应激状态和血管内皮功能，抑制心肌重构，进而使肥胖和肥胖合并心肌梗死大鼠的心功能得到改善。②L-4F能够改善脂肪细胞的炎症反应，减少脂肪细胞的堆积，改善心肌细胞缺氧复氧后的功能，减少心肌细胞的凋亡。③发挥作用的通路可能为L-4F-HO-1-APN-Wnt10b-PPARγ-C/EBPα和内质网应激相关的信号通路。. 因此，本研究为肥胖及肥胖并心肌梗死后心衰防治新靶点提供了较为可靠的依据。