Apelin对肥厚型心肌病心肌细胞肥大和心肌纤维化的作用和机制研究

Hypertrophic Cardiomyopathy (HCM) was proved to be one kind of disease due to genetic mutation. Treatments for HCM are limited to symptom release by drugs, percutaneous cardiac intervention or surgery and there are no effective therapy for the genetic mutation. Angiotension II was found to play an important role in the development of cardiac hypertrophy, and its receptor blocker can reverse the myocardial fibrosis of HCM transgenic animal. But the clinical effect of ARB is not so good as predicted. Apelin is a factor found in 1998 which has kind of homology with AngII. Research for cardiac hypertrophy revealed that apelin can reduce the development of hypertrophy, We are going to explore the effect and mechanism of apelin in the development of cardiac hypertrophy. Firstly, a clinical observation will be performed to find whether the serum level of apelin is associated with the phenotype of HCM which include ventricular hypertrophy, obstruction, left ventricular outflow tract pressure gradient(LVOTG) and so on. Then a cellular experiment will be held to explore whether apelin could ameliorate the hypertrophy of cardiac cells, and its mechanism of cell signal transduction will be tested. Finally, we will conduct a series of tests on TNTQ92 transgenic mice of HCM to find the effect of apelin for the transgenic mice and its mechanism of cell signal transduction as well. This research is designed to prove that apelin can restrain the cardiac hypertrophy and fibrosis of HCM as the natural antagonist of AngII, and it will be a great discovery for the treatment of HCM.

肥厚性心肌病是遗传基因突变导致，目前没有针对病因的治疗方法。研究发现血管紧张素II在HCM心肌肥厚的发展过程中起促进作用，但其受体拮抗剂ARB治疗效果不佳。Apelin是一种与AngII同源的因子，能抑制心肌肥厚。本研究旨在探讨Apelin在HCM的心肌肥厚及心肌纤维化中的作用及机制。首先通过临床观察探讨Apelin是否与HCM的表型（肥厚程度、梗阻程度、左室流出道压力阶差等）有关，然后从细胞水平研究Apelin能否抑制AngII诱导的心肌细胞肥大，以及其细胞信号机制；接着从转基因动物水平探讨Apelin是否能改善人肥厚性心肌病TNTQ92转基因小鼠的心肌肥厚及心肌纤维化，以及其细胞信号转导机制。通过本研究拟发现Apelin可以抑制心肌细胞肥大，改善或逆转HCM心肌肥厚及纤维化，以及这些作用的机制，为HCM的药物治疗提供新靶点。

研究背景：.本课题从临床、细胞实验、转基因动物试验三个角度探讨了apelin对人肥厚型心肌病心肌肥厚及心肌纤维化的作用，并探索了其可能的作用机制。.研究方法及研究结果：.临床部分对151名HCM患者的血清apelin水平进行了分析，发现在HCM尚未发展为心力衰竭的病人中，Apelin水平下降。Apelin水平与心肌肥厚程度、梗阻程度及左室流出道压力阶差呈负相关。梗阻性HCM患者室间隔消融术后的血清Apelin较术前升高，与梗阻改善程度呈正相关。.细胞实验部分探讨了apelin对AngII诱导的心肌细胞肥大的作用及其机制。发现AngII可以使心肌细胞表面积增加、心肌细胞亮氨酸掺入量增加，总蛋白表达量增加，BNP和β-MHC的蛋白表达水平明显上调， apelin与AngII共同作用后，上述指标与AngII组相比呈剂量依赖性减少。AngII可使心肌细胞内静息游离Ca2+水平明显升高，上调calcineurin磷酸化程度，同时提高心肌细胞NFATc3的蛋白表达水平和CAMK II蛋白表达水平，同时上调CAMK II磷酸化水平。这一作用可被apelin抑制，并呈剂量依赖性。.动物实验部分探讨了apelin对cTNTQ92转基因小鼠心肌纤维化及心脏舒张功能的影响及其机制。结果发现与对照组相比，cTNTQ92转基因小鼠射血时间、等容舒张时间明显延长，提示转基因小鼠左室舒张功能受损。Apelin处理12周后，cTNTQ92转基因小鼠二尖瓣ET及IVRT较apelin处理前明显缩短，与安慰剂组相比也有明显缩短，表示apelin处理后的转基因小鼠舒张功能有明显改善。cTNTQ92转基因小鼠的心肌组织胶原体积分数及心肌细胞排列紊乱的比例较非转基因小鼠明显升高，apelin处理后，转基因小鼠的CVF及心肌细胞排列紊乱的比例较安慰剂组明显下降。与对照组相比，cTNTQ92转基因小鼠心肌组织内心肌纤维化的分子标志物col1α1，TGF-β和smad2，3的表达量明显增加。Apelin处理12周后，cTNTQ92转基因小鼠心肌组织内col1α1，TGF-β和smad2，3的表达量较安慰剂组减少。而smad7的表达则表现出相反变化趋势。.结论：.Apelin与HCM心肌肥厚程度、梗阻程度及左室流出道压力阶差呈负相关。Apelin通过下调Ga+/钙调蛋白依赖的钙调神经磷酸酶以及钙调蛋白激酶II信号通