组蛋白去乙酰化酶HDAC3介导的冠脉微循环障碍在心肌致密化不全中的发病机制及对策研究

Noncompaction cardiomyopathy (NCCM) is a rare cardiomyopathy which characterized by prominent trabecular meshwork and deep inter-trabecular recesses communicating with the left ventricular (LV) cavity due to arrest of the normal embryogenesis of the myocardium. Progressive heart failure, thrombosis and embolism and sudden death are main clinical manifestations of NCCM. NCCM is a disease of unknown origin with poor prognosis and without effective treatment. Even though some studies consider NCCM is related to gene mutations or cardiomyocytes hyperproliferation, but none of these mechanisms can explain the whole picture of NCCM. After following up hundreds of NCCM patients for nearly ten years as well as some basic researches results, our group adds some new findings to the mechanism and treatment of NCCM. First of all, we prove that 30% offspring of type 1 diabetics gestation mice have NCCM phenotype, and we also prove that the non-compaction parts of NCCM heart do not have mature cardiac tissues. Combined with the MRI evidences from NCCM patients, we consider NCCM is a coronary microcirculation disease due to the dysfunction of subepicardial endothelial cells which form the coronary vessels. Secondly, we found the histone deacetylase3 (HDAC3) might be involved in the pathophysiological process because the upstream signal pathway VEGF-Notch1-Nrg1-AKT of HDAC3 is downregulated in noncompaction tissue. And the activity of HDAC3 is essential for the stem cells to develop to endothelial cells. Thirdly, we found long time physical exercise is very benefit for recovery of NCCM patients’ heart function. Therefore in this study, we will combine cell/animal model and clinical data to prove that reduced HDAC3 activity via VEGF-Notch1-HDAC-eNOS pathway in subepicardial endothelial cells in pathologic pregnancy is the mechanism of NCCM, and physical exercise can partly recovery the HDAC3 activity to improve the heart function of NCCM. This study can offer new mechanism and treatment strategy to this difficult and deadly disease.

心肌致密化不全（NCCM）是胚胎期心肌从幼稚到成熟发育障碍导致正常致密心肌被大量无功能的肌小梁替代的心肌病，表现为进行性心衰、血栓栓塞和猝死，尚无特效治疗方法。多数观点认为该病与遗传和心肌过度增殖有关，但难以解释全貌。我们随诊百余名NCCM患者近十年及前期研究，有如下新发现。首次发现30%的1型糖尿病小鼠子代出现NCCM，非致密化心肌无成熟组织，结合核磁等临床资料，认为NCCM是微血管病，与形成冠脉微循环的心外膜下内皮细胞功能障碍有关。继而发现促干细胞向内皮细胞分化的表观遗传因子组蛋白去乙酰化酶(HDAC3)的上游通路VEGF/VEGFR2-Notch1-Neugulin-AKT在非致密心肌表达下降。此外运动可有效恢复患者心功能。本研究将结合细胞、动物和临床资料，探讨HDAC3介导的微血管内皮功能障碍在NCCM中的发病机制及运动的治疗作用。该研究将为NCCM发病机制和治疗提供新视角。

心肌致密化不全（Noncompaction cardiomyopathy (NCCM)），是胚胎期心肌发育过程出现障碍，导致心脏内残留大量粗大肌小梁及深陷隐窝,形成功能不良的心脏结构的疾病，患者会出现进展性心力衰竭、血栓栓塞和猝死事件。NCCM病因不明确，疾病进展机制不明，临床表现差异大，治疗棘手。基于多年临床工作及先期实验室工作基础，我们认为NCCM是不良妊娠导致胎儿形成冠脉的心外膜下内皮细胞（EDPCs）功能缺陷，可能涉及的机制是组蛋白去乙酰化酶HDAC3活性缺乏，造成胎儿冠脉微循环发育不良，影响心肌致密化过程，积极运动可能会提高HDAC3活性，促进微循环的修复，改善心脏功能。本研究中我们通过三个方面的研究证实该猜想。首先我们证实NCCM存在微循环障碍。临床方面，在射血分数减低的NCCM患者中，心脏核磁证实存在心肌微循环灌注减低，与血管分布无显著相关；在两种不良妊娠（高血糖和维甲酸妊娠）的动物子代模型中，通过双光子电子显微和对心肌的免疫组化研究证实，在NCCM中存在微循环血管密度减低。其次，我们通过动物和细胞学研究证实，在NCCM的子代大鼠心肌中存在EDPCs功能不良，表现在分泌功能、促进血管形成功能不良，而调控HDAC3活性，可以改善EDPCs促进血管形成的能力；同时通过与EDPCs与胎鼠心肌共培养的方法，我们证实NCCM组EDPCs不能很好的促进胎鼠心肌增殖，调控HDAC3活性，可以改变与EDPCs共培养的胎鼠心肌细胞的增殖、心脏特异性蛋白的表达和线粒体功能，可能涉及的信号通路为VEGF-Notch1-AKT-HDACs。最后我们探索运动对于NCCM的影响。在临床患者随访中，我们证实规律运动的NCCM患者在标准治疗基础上可以更好地维持心脏功能；在动物运动研究中，我们证实运动组HDAC3显著升高，双光子电子显微镜和免疫组化研究也证实运动组微循环密度及容积增加，微循环对于去甲肾上腺素的反应增强。综上，.我们证实了NCCM存在微循环障碍，其发病机制与病理妊娠导致的EDPCs功能不良有关，运动可在一定程度上改善NCCM的冠脉微循环障碍。该研究从临床、动物模型及细胞学层面较为完善地验证了科学问题，为后续更有效治疗NCCM提供了新的视点。