Expression Profiling of cardiac fibroblasts

Excessive extracellular matrix accumulation in the myocardium is a poor prognostic factor for reduced left ventricular function. It is known that improvement of hemodynamic loading improves myocardial fibrosis, but in vitro models of the pathogenesis have not been established, and the potential mechanism of fibrosis resolution have not clarified. We reproduced normal myocardium, fibrotic myocardium following hemodynamic loading and myocardium with improved fibrosis following hemodynamic loading reduction in vitro. Fibroblasts were activated to αSMA+ fibroblasts on myocardium following hemodynamic loading. On myocardium following hemodynamic loading reduction, they were deactivated to αSMA- fibroblasts, and their phenotype changed to fibrinolytic cells expressing MMP2 and MMP9. Comprehensive gene expression analysis of fibroblasts in each in vitro model revealed that Selenbp1 is one of the genes responsible for regulation of phenotypic changes in fibroblasts. In vitro, knockdown of Selenbp1 using RNA interference enhanced fibroblast activation and inhibited conversion to the fibrinolytic form. In vivo, knockdown of Selenbp1 caused structural changes in the left ventricle associated with progressive tissue fibrosis and left ventricular diastolic failure. Selenbp1 is involved in the regulation of fibroblast phenotype and was found to be one of the major molecules regulating collagen turnover in cardiac fibrosis.心肌组织内过量细胞外基质（extracellular matrix）蓄积，是左心室功能减退患者预后不良的重要危险因素。现有研究表明，血流动力学负荷改善可缓解心肌纤维化，但目前尚未建立该病发病机制的体外模型，且纤维化消退的潜在分子机制仍未阐明。本研究在体外成功构建三类模型：正常心肌组织、血流动力学负荷诱导的纤维化心肌组织，以及血流动力学负荷减轻后纤维化得到改善的心肌组织。在血流动力学负荷诱导的纤维化心肌组织中，成纤维细胞被激活为α平滑肌肌动蛋白阳性（αSMA+）成纤维细胞；而在血流动力学负荷减轻的心肌组织中，这些成纤维细胞会失活为α平滑肌肌动蛋白阴性（αSMA-）成纤维细胞，其表型转换为表达基质金属蛋白酶2（MMP2）与基质金属蛋白酶9（MMP9）的纤溶细胞。对各体外模型中成纤维细胞的全基因表达谱分析显示，硒结合蛋白1（Selenbp1）是调控成纤维细胞表型转换的关键基因之一。体外实验中，通过RNA干扰（RNA interference）技术敲低Selenbp1的表达，可增强成纤维细胞的激活状态，并抑制其向纤溶细胞表型的转换。体内实验中，敲低Selenbp1可导致左心室结构发生改变，并伴随进行性组织纤维化与左心室舒张功能衰竭。Selenbp1参与调控成纤维细胞表型，是心脏纤维化过程中调控胶原代谢的核心分子之一。