Linking Spatial Variations in Shear Stress with Oxidation Stress

描述(申请人提供)：流体剪切力对血管内皮细胞功能既有代谢作用又有机械作用。切应力的空间(D/x)和时间(D/t)分量在很大程度上决定了血管氧化应激的局部性质，从而导致促炎状态。前一批赠款的重点是研究方法从静态模型之一(氧化生物学)向结合了具有病理生理学意义的生物物理和生化方法的动态模型(血管氧化应激)的范式转变。我们证明，D/x和D/t的变化对内皮细胞产生O2.-和NO有不同的调节作用，导致低密度脂蛋白(LDL)氧化修饰与动脉粥样硬化病变的启动相关。我们开发了微型机电系统(MEMS)传感器来实时测量高胆固醇饮食下新西兰白兔(NZW)的血管内切应力，并将我们的血管内方法应用于猪模型。我们对动脉粥样硬化保护血流动力学增加线粒体膜电位(M)，同时通过上调Mn-SOD活性而减少线粒体O2.-产生的机制有了新的认识。相反，动脉粥样硬化的血流动力学和氧化的低密度脂蛋白诱导线粒体产生O2-，通过c-Jun NH2末端激酶(JNK)诱导的Mn-SOD泛素化和蛋白质降解导致细胞凋亡。我们的发现导致了一项新的观察，即血管壁中活跃的脂质和巨噬细胞引起电化学修饰，这可以通过电化学阻抗谱(EIS)来测量。在这种情况下，我们假设剪切力调节线粒体的氧化还原状态，调节血管氧化应激，从而在非梗阻性尽管是炎症性病变的区域引起电化学阻抗的明显变化。在新的目标1中，我们将提供一种EIS的体外模型；具体地说，我们将提供人动脉和NZW兔主动脉同心双极微电极与腔内表面之间的频率依赖的电和介电特性。在目标2中，我们将使用脂肪喂养的NZW兔建立EIS测量的体内模型；具体地说，微制造和部署用于血管内EIS测量的电极。在目标3中，我们将提供分子和遗传模型来证明氧化还原信号是导致电化学修饰变化的一个必要因素。下一个资助期的重点将整合电化学、氧化还原信号和遗传方法，以建立特定的EIS，这些EIS在血管造影术期间因局部促炎状态而发生，并有可能识别不稳定的斑块。总之，我们实验室在上一个资助周期的发表记录(30名通讯作者)证明了我们在机械生物学和血管氧化应激研究方面的承诺和生产率。

DESCRIPTION (provided by applicant): Fluid shear stress imparts both metabolic and mechanical effects on vascular endothelial function. The spatial ( D/ x) and temporal ( D/ t) components of shear stress largely determine the focal nature of vascular oxidative stress, leading to pro-inflammatory states. The focus of the previous grant period was a paradigm shift in the approach from one of the static models (oxidative biology) to the dynamic models of investigation (vascular oxidative stress) that combined biophysical and biochemical approaches of pathophysiological significance. We demonstrated that variations in D/ x and D/ t differentially regulated the endothelial production of O2.- and .NO, leading to low density lipoprotein (LDL) oxidative modifications relevant for the initiation of atherosclerotic lesions. We developed microelectromechanical systems (MEMS) sensors to measure in real-time intravascular shear stress in the New Zealand White (NZW) rabbits on a hypercholesterolemic diet, and applied our intravascular methodology to the swine model. We gained new insights into the mechanisms whereby atheroprotective hemodynamics increased mitochondrial membrane potential ( (m) accompanied by a decrease in mitochondrial O2.- production via an up-regulation in Mn-SOD activities. In contrast, atherogenic hemodynamics and oxidized LDL induced mitochondrial O2.- production, leading to apoptosis via c-Jun NH2 terminal kinase (JNK)-induced Mn-SOD ubiquitination and protein degradation. Our finding led to a novel observation that active lipid and macrophages in the vessel wall cause electrochemical modifications that can be measured by electrochemical impedance spectroscopy (EIS). In this context, we hypothesize that shear stress regulates mitochondrial redox status, modulating vascular oxidative stress to cause distinct changes in electrochemical impedance in regions of non-obstructive, albeit inflammatory lesions. In the new Aim 1, we will provide an ex vivo model of EIS; specifically, the frequency-dependent electrical and dielectrical properties between concentric bipolar microelectrodes and endoluminal surface of explants of human arteries and NZW rabbit aortas. In Aim 2, we will establish an in vivo model of EIS measurements using fat-fed NZW rabbits; specifically, microfabrication and deployment of the electrodes for intravascular EIS measurements. In Aim 3, we will provide molecular and genetic models to demonstrate redox signaling as a requite factor underlying changes in electrochemical modifications. The focus in the next grant period will integrate electrochemical, redox signaling, and genetic approaches to establish specific EIS that occur in response to local pro- inflammatory states during angiograms with the possibility of identifying unstable plaque. In summary, the publication record (30 corresponding authors) of our laboratory in the previous funding cycle is a testimony of our commitment and productivity in mechanobiology and vascular oxidative stress research.