铁过载加剧高糖环境中血管内皮细胞损伤及机制研究

In light of (previous work from ours and others-if you already published) previous reports and our own work, we hypothesize: ROS resulting from sub-damage dose of iron and glucose synergistically inhibit activity of DDAH， inactivate ADMA and reduce NO production. By "NOS uncoupling", viscious ROS production, RIRR activation, mPTP excessive opening, all together lead to failure of endothelial cell function, which can be attenuated by Taurine and its derivatives . In this grant poposal, we aim to further assess the synergistic damaging effect of iron and glucose on endothelial function, and in parallel to analyze the abovementioned "NO uncoupling" parameters. Toward this purpose, we will construct adenovirus encoding recombinant DDAHⅡ, infect it into HUVECs，and examine the effect of DDAHII overexpression on the damage imposed by addition of both sub-damage dose of iron and glucose. Simultaneously, we will assess if this protective effect can be recapitulated by Taurine. Finally, we will establish diabetic animal model with STZ to test if the synergistic effect occurs and if iron at a sub-damage dose will aggavate diabetic manisfestations. In this assay, we will isolate large/small/micro vessels, and examine vascular function, endothelial cell damage, and the effect of taurine intervention. Hopefully, our study will demonstrate a synergistic effect of iron and glucose on the etiology of diabetes and damage to vascular endothelial cell as well as identify the underlying molecular mechanisms. Therefore, the proposed study will help to provide an appropriate diet recipe for diabetic patients and population with a high risk to diabetes, and to identify new molecular targets for vascular lesions, and to develop new ideas for therapeutic drugs.

在总结前人与自身工作基础上，我们假设：亚损伤浓度铁与糖生成的ROS协同抑制DDAHⅡ活性，ADMA灭活与NO生成减少，且经"NOS脱偶联"机制，ROS恶性生成，RIRR激活，mPTP过度开放，导致内皮细胞功能衰竭；牛磺酸等可对抗之。拟在HUVECs上确认亚损伤浓度铁与糖协同损伤，测定细胞ADMA含量及eNOS表达/活性、ROS含量、线粒体膜电位（Δψ）、mPTP开放、细胞凋亡等；构建DDAHⅡ重组腺病毒并转染HUVECs，或用牛磺酸等干预，重复上述实验；最后建立STZ亚糖尿病大鼠模型，评估亚损伤浓度铁与糖协同加重糖尿病相关状况，取模型大鼠大、小、微血管检测血管功能及内皮细胞损害情况，以及牛磺酸干预之疗效。本研究可望探讨、阐明亚损伤浓度的铁与糖协同诱发糖尿病、协同损伤血管内皮细胞之分子生物学机制，为改善人们，特别是糖尿病高危人群的膳食结构，寻找相关血管病变分子靶点，开发相关药物拓展新的思路。

紧扣“ROS”之关键，以“铁、糖均可引起ROS过量形成，进而抑制DDAHⅡ，使ADMA灭活与NO生成减少，激活RIRR机制，诱发ROS爆发，mPTP过度开放，导致内皮细胞功能衰竭”为主线，本项目完成了腺病毒载体pAD/DDAHⅡ构建及转染细胞相应蛋白测定；确认HUVECs亚损伤糖/铁浓度分别为5 mM/1.875μM，最佳比例为0.5/0.5；二者协同作用可使细胞存活率显著降低，ROS生成增加，SOD/GSH-Px/Catalas及GSH活性/含量降低，MDA/GSSG含量增加，线粒体膜电位减少，mPTP开放、最终细胞凋亡；其机制与糖/铁协同作用造成ROS恶性生成，DDAHⅡ/ADMA/eNOS/NO通路紊乱， RIRR机制激活，诱发线粒体功能衰竭有关。. 本项目完成了整体大鼠验证实验：给予亚损伤剂量的10 mg/kgSTZ和12.5 mg/kg右旋糖苷铁8周：大鼠胸主动脉/肠系膜动脉/大脑基底动脉的血管内皮依赖性舒张功能均有不同程度损伤，损伤程度依次为大脑基底动脉>肠系膜动脉>胸主动脉；同样可见大鼠ROS/ADMA /DDAHⅡ/eNOS通路功能之紊乱。外源性上调DDAHⅡ表达，或外源性补充ADMA生理性拮抗L-Arg、或外源性应用mPTP关闭剂CsA、或外源性应用抗氧化剂牛磺酸或阿魏酸可对抗上述糖/铁协同造成血管内皮细胞之损伤。. 本项目首次发现、证实槲皮素、葛根素等中药有效成分可显著上调HUVECs细胞之DDAHⅡ表达，调整ROS/DDAHⅡ/ADMA/eNOS通路，改善线粒体能量供应，维护线粒体功能，进而缓解、对抗上述糖/铁协同损伤。本研究阐明了亚损伤糖/铁协同损伤内皮细胞之分子机制，丰富了相关高危人群防治的相关理论基础，为发现新的药物作用靶点奠定良好的理论与实验基础。. 本课题全面完成研究计划，发表学术论文5篇（标注资助），并培养博士生2名，硕士生4名。