Regulatory Mechanisms of Oxidative Stress in Hypertensive Heart Disease

描述(由申请人提供)：高血压性心脏病(HHD)的病理生理起源是由修复性纤维化或疤痕形成的，它取代了坏死的心肌细胞。了解心肌细胞坏死背后的病理生物学将有助于预防HHD，而从外周血单个核细胞(PBMC)非侵入性获得的预测坏死的生物标志物的可用性将有助于识别风险。在解决这些目标时，我们使用我们已建立的由醛固酮/盐治疗(ALDOST)引起的HHD模型，并利用其临床前(WK 1)和病理(WK 4)阶段。中心假说：在HHD中，WK4的纤维化是由于氧化应激诱导的心肌细胞坏死，其中细胞的氧化还原状态的改变植根于甲状旁腺激素(PTH)介导的细胞内钙超载，包括心肌细胞、线粒体和PBMC，其中活性氧物种(ROS)的产生速度超过了其内源性抗氧化防御的解毒速度。这种2C+依赖的氧化应激诱导促进线粒体通透性转换孔(MPTP)的开放，最终导致坏死。作为抗氧化剂的胞浆和线粒体2Z+n的同时升高可以抵消这种氧化促进剂状态。我们推测，促氧化剂和抗氧化剂之间的失衡与钙和锌离子耦合的动态平衡失调密不可分。线粒体是ROS的主要来源。目的#1：确定细胞内C2+a超载引起氧化应激的细胞和分子起源，以及线粒体内钙蓄积、氧化应激和MPTP开放在导致坏死的信号转导通路中的作用，并比较心脏组织及其心肌细胞和线粒体与PBMCW。使用线粒体靶向试剂：阻断2+Cau转运体；t作为抗氧化剂；以及抑制MPTP。通过增加[Zn2+]i，诱导其感受器、金属反应转录因子(MTF)-1及其调节的抗氧化剂基因，可防止坏死。这种“解偶联疗法”包括：锌盐补充剂；PDTC，一种锌离子载体；或硫酸锌加莫氯地平。目的#2：探讨细胞内[Zn~(2+)]i升高所激活的信号转导抗氧化途径，以及硫酸锌、PDTC或锌与氨氯地平合用促进的抗氧化途径，以及MTF-1调节的抗氧化防御在心肌细胞中最终形成抗氧化、抗炎表型的作用，并比较心脏组织及其心肌细胞和线粒体与PBMC的作用。在ALDOST过程中，PBMC与心肌细胞和线粒体具有共同的病理生理反应和上调的基因网络。我们在AIMS#1和AIMS#2中收集PBMC，以寻找新的风险、损伤和干预反应的替代生物标志物。目的：1)鉴定PBMC转录组和蛋白质组中与促炎性心脏表型具有分子模拟的主要成分，包括其线粒体蛋白质组；2)阐明可作为临床前和病理阶段预测HHD风险的非侵入性生物标志物的特定途径候选。 公共卫生相关性：心力衰竭是一个主要的健康问题。高血压性心脏病(HHD)是导致心脏作为肌泵衰竭的一个主要因素，它涉及与纤维化相关的不利的心肌结构重构。我们的目的是更好地了解导致纤维化的机制，从而识别HHD的风险和预防。

DESCRIPTION (provided by applicant): Hypertensive heart disease (HHD) has its pathophysiologic origins arising from the reparative fibrosis, or scarring, that replaces necrotic cardiomyocytes. Understanding the pathobiology behind cardiomyocyte necrosis will lead to the prevention of HHD while the availability of biomarkers predictive of necrosis and obtained noninvasively from peripheral blood mononuclear cells (PBMC) will aid in identification of risk. In addressing these objectives we use our established model of HHD provoked by aldosterone/salt treatment (ALDOST) and exploit its preclinical (wk 1) and pathologic (wk 4) stages. Central hypothesis: in HHD, fibrosis at wk 4 is due to oxidative stress- induced cardiomyocyte necrosis, where the cell's altered redox state is rooted in parathyroid hormone (PTH)- mediated intracellular Ca2+ overloading, including cardiac myocytes and mitochondria and PBMC, and where the rate of reactive oxygen species (ROS) generation overwhelms the rate of their detoxification by endogenous antioxidant defenses. This 2C+-adependent induction of oxidative stress promotes the opening of the mitochondrial permeability transition pore (mPTP) to culminate i n necrosis. This prooxidant state can be counterbalanced by the contemporaneous rise in cytosolic and mitochondrial 2Z+nserving as antioxidant. We hypothesize the dysequilibrium between pro- and antioxidant is inextricably linked to the coupled dyshomeostasis of Ca2+ and Zn2+. Mitochondria are the major source of ROS. Aim #1: to determine the cellular and molecular origins of oxidative stress arising from intracellular C2+a overloading and the role of intra mitochondrial Ca2+ accumulation, oxidative stress and mPTP opening in the signal-transduction pathway leading to necrosis and to compare heart tissue and its cardiac myocytes and mitochondria with PBMCW.e use mitochondria-targeted reagents: to b lock the 2+Cau niporter; t o serve as antioxidant; and to inhibit mPTP. Necrosis is prevented by increased [Zn2+]i, which induces its sensor, metal-responsive transcription factor (MTF)-1 and the antioxidant genes it regulates. Such "uncoupling therapy" includes: Zn4SOsupplement; PDTC, a Zn2+ ionophore; or ZnSO4 plus a mlodipine. Aim # 2: to explore the signal-transduction antioxidant pathway invoked by increased intracellular [Zn2+]i and promoted by ZnSO4, PDTC, or ZnSO4 with amlodipine, along with the role of MTF-1 regulated antioxidant defenses that eventuate in an antioxidant, anti-inflammatory phenotype in cardiac myocytes and to compare heart tissue and its cardiomyocytes and mitochondria with PBMC. PBMC share common pathophysiologic responses and upregulated gene networks with cardiac myocytes and mitochondria during ALDOST. We harvest PBMC throughout Aims #1 and 2 in search of novel surrogate biomarkers of risk, injury and response to intervention. Aim #3: i) to identify major components of the PBMC transcriptome and proteome having molecular mimicry with the pro inflammatory cardiac phenotype, including its mitochondrial proteome, and ii) to elucidate specific pathway candidates that could serve as noninvasive biomarkers predictive of risk during preclinical and pathologic stages of HHD. PUBLIC HEALTH RELEVANCE: Heart failure is a major health problem. Hypertensive heart disease (HHD), a major factor contributing to the heart's failure as a muscular pump, involves an adverse structural remodeling of myocardium related to fibrosis. Our aim is to better understand mechanisms contributing to the appearance of fibrosis and to thereby identify risk and prevention of HHD.