Feng Biao, Chen Shali, Gordon Andrew Devon, Chakrabarti Subrata
Department of Pathology and Laboratory Medicine, Western University, London, ON, Canada.
Department of Pathology and Laboratory Medicine, Western University, London, ON, Canada.
J Mol Cell Cardiol. 2017 Apr;105:70-76. doi: 10.1016/j.yjmcc.2017.03.002. Epub 2017 Mar 6.
Hyperglycemia induced endothelial injury is a key pathogenetic factor in diabetic cardiomyopathy. In diabetes, changes in pro-inflammatory cytokines are a key mechanism leading to cardiac fibrosis. We have previously demonstrated alteration of miR-146a in chronic diabetic complications. Here, we investigated the role of endothelial miR-146a in mediating inflammation and fibrosis in diabetic cardiomyopathy. To examine the effects of miR-146a on the inflammatory mediators, an endothelial specific miR-146a overexpressing transgenic mice (TG) using tie-2 promoter, was generated. We examined these mice and wild type littermate controls with or without STZ induced diabetes. Transthoracic echocardiography was performed. Cardiac tissues were examined for inflammatory cytokine mRNAs and proteins by real time RT-PCR or ELISA. Cardiac fibrosis was examined by histology staining. Human cardiac microvascular endothelial cells (HCMECs) and primary endothelial cells isolated from mice were used following incubation with various levels of glucose with or without miR-146a mimics or antagomir transfection. In hearts of wild type mice with diabetes, increased expression of inflammatory markers and extracellular matrix proteins (IL6, TNFα, IL-1β, MCP-1, NF-κB, Col1α1, Col4α1) were seen compared to wild type controls. These changes were prevented in the diabetic TG mice. In addition, WT diabetic mice showed cardiac functional abnormalities, which were improved in the diabetic TG mice. In vitro studies showed glucose induced increase the expressions of the above inflammatory cytokines and specific NF-κB regulators (IRAK1 &TRAF6). Such changes were corrected in the HCMECs following miR-146a mimic transfection. These data indicate that in diabetes, increased inflammatory cytokine and extracellular matrix protein productions and associated cardiac functional alterations are regulated by endothelial miR-146a. Identification of such mechanisms may potentially lead to the development of novel RNA based therapeutics.
高血糖诱导的内皮损伤是糖尿病心肌病的关键致病因素。在糖尿病中，促炎细胞因子的变化是导致心脏纤维化的关键机制。我们之前已经证明了miR-146a在慢性糖尿病并发症中的改变。在此，我们研究了内皮miR-146a在介导糖尿病心肌病炎症和纤维化中的作用。为了检测miR-146a对炎症介质的影响，构建了使用tie-2启动子的内皮特异性miR-146a过表达转基因小鼠（TG）。我们检测了这些小鼠以及野生型同窝对照小鼠，有无链脲佐菌素诱导的糖尿病。进行了经胸超声心动图检查。通过实时RT-PCR或ELISA检测心脏组织中的炎性细胞因子mRNA和蛋白质。通过组织学染色检查心脏纤维化。在用人心脏微血管内皮细胞（HCMECs）和从小鼠分离的原代内皮细胞与不同水平的葡萄糖孵育后，进行有无miR-146a模拟物或拮抗剂转染。与野生型对照相比，患有糖尿病的野生型小鼠心脏中炎性标志物和细胞外基质蛋白（IL6、TNFα、IL-1β、MCP-1、NF-κB、Col1α1、Col4α1）的表达增加。这些变化在糖尿病TG小鼠中得到了预防。此外，野生型糖尿病小鼠表现出心脏功能异常，而在糖尿病TG小鼠中得到改善。体外研究表明，葡萄糖诱导上述炎性细胞因子和特定NF-κB调节因子（IRAK1和TRAF6）的表达增加。在miR-146a模拟物转染后的HCMECs中，这些变化得到了纠正。这些数据表明，在糖尿病中，炎性细胞因子和细胞外基质蛋白产生的增加以及相关的心脏功能改变受内皮miR-146a调节。确定此类机制可能会潜在地导致基于RNA的新型治疗方法的开发。
