利用诱导多能干细胞研究抑制PPARγ对于ARVC病症发展的影响

Arrhythmogenic right ventricular cardiomyopathy (ARVC), primary heart muscle disorder, is a leading cause of sudden death. ARVC, with prevalence approximately 1:5000, is clinically characterized by right ventricular arrhythmias, heart failure and sudden death, whereas the pathology is associated with progressive dystrophy of the right ventricular myocardium by fibro-fatty infiltration or replacement. The fact, that ARVC claims about 20% of sudden death in the young and the athlete, pointes out the importance of the investigation of ARVC early stage mechanism and the development of proper targeting drugs. Previous reports in ARVC transgenic animal models and patient biospy show PPARγ, which plays a central role in adipocyte differentiation, over-activates in the affected right ventricular myocardia. At the moment, PPARγ agonist and antagonist have been mainly used in glucose and lipid metabolism disorders. However, the knowledge of the effect of PPARγ on ARVC is considerably limited. In the present research, we aim to investigate whether inhibition of PPARγ could improve the disease condition by using ARVC patient specific induced pluripotent stem cells (iPS) model. The lipogenesis index, ion channel remodeling, action potential, apoptosis index and ultra-structure of ARVC iPS-derived cardiaomyocytes will be examined to evaluate the effect of PPARγ inhibition on ARVC development.

致心律失常性右室心肌病（ARVC）是临床上常见的可致猝死的原发性心肌病(1/5000)，以反复性发作的右心室起源的心律失常、心力衰竭以及心源性猝死为主要表现，显著病理特征是右室游离壁心肌组织部分进行性地脂肪替代。ARVC在年青人群和运动员中的高猝死率(20%)迫切需要对其发病早期深入研究，以找到新的干预靶点。转基因动物以及患者活检的研究表明：与脂肪分化密切相关的转录因子PPARγ在早期的ARVC病人中处于超激活状态。目前，PPARγ激活剂/抑制剂主要应用于糖脂代谢疾病，而其在ARVC中的应用研究报道匮乏。本项目拟建立ARVC病人特异性、诱导多能干细胞模型，而后进行定向心肌细胞分化，通过对心肌细胞的脂肪滴积累、离子通道重建、动作电位、 细胞凋亡、超微结构等指标的检测，评价抑制PPARγ表达对ARVC发展的影响，以期探讨早期防治ARVC发病的可行性。

致心律失常性右室心肌病（ARVC）是临床上常见的可致猝死的原发性心肌病(1/5000)，以反复性发作的右心室起源的心律失常、心力衰竭以及心源性猝死为主要表现，显著病理特征是右室游离壁心肌组织部分进行性地脂肪替代。ARVC在年青人群和运动员中的高猝死率(20%)迫切需要对其发病早期深入研究，以找到新的干预靶点。转基因动物以及患者活检的研究表明：与脂肪分化密切相关的转录因子PPARγ在早期的ARVC病人中处于超激活状态。目前，PPARγ激活剂/抑制剂主要应用于糖脂代谢疾病，而其在ARVC中的应用研究报道匮乏。本项目中，我们从ARVC病人身上取表皮成纤维细胞并将其转变为诱导干细胞（iPSCs），进而分化为心肌细胞（CMs）。荧光定量PCR显示与人胚胎干细胞分化的心肌细胞或正常对照的人iPSCs-CMs相比，ARVC-iPSCs-CMs中 PPARγ表达升高而Wnt信号通路基因表达降低。Bax/Bcl-2的升高和γH2A.X信号增强表明ARVC-iPSCs-CMs凋亡增高，而Wnt激活剂CHIR可以抑制细胞凋亡。我们还发现ARVC-iPSCs-CMs中胞内ROS水平升高，并且线粒体的分布异常。总之，我们成功得到ARVC-iPSCs并将其分化为心肌细胞。我们的结果表明PPARγ激活抑制Wnt信号通路，这可能导致ROS集聚和线粒体失活，从而引起ARVC发病过程中细胞凋亡升高。我们的研究为了解ARVC发病机理提供了科学依据。