Mechanisms for Sex Differences in CVD Pathology and Development of a Targeted Therapeutic

摘要： 心血管疾病(CVD)仍然是全球主要的死亡原因，与多种心血管疾病有关。 疾病包括2型糖尿病(T2 DM)和肥胖。我们团队在过去20年中的工作 而另一些人则发现血管紧张素II 2型受体(AT2R)在血管紧张素转换酶的发生和发展中起关键作用。 心脏和血管结构损伤的发病机制。临床上，在男性中，Agtr2表达缺失是 与动脉僵硬、肾功能受损和脉压升高有关。文学 表明女性特有的AT2R表达增加可以保护雌性小鼠模型免受血管损伤。 健康雌性(ZL-F)大鼠心脏X-连锁Agtr2的表达高于雄性(ZL-M)大鼠； 但T2 DM仅抑制ZDF-F(雌性)心脏Agtr2的表达，而不抑制ZDF-M(雄性)的Agtr2表达。我们假设 增加ZDF-F大鼠心脏Agtr2的表达将保护心肌细胞免受损失和瘢痕形成 这种治疗将对患有心血管疾病的妇女特别有益。然而，目前还没有AT2R激动剂 这可以增加Agtr2的表达。我们观察到一种新的AT2R多肽激动剂NP-6A4可以 增加大鼠和人血管内皮细胞Agtr2表达，减轻心肌肥大、纤维化和毛细血管病变 雄性Zucker肥胖大鼠的稀疏性。我们的概念新颖的中心假说是基于这些 观察和声明NP-6A4-AT2R信号提供了一种缓解性行为的新的治疗方法 增加Agtr2基因表达在CVD中的差异。我们发现了两个由NP引发的新的交叉对话- 6A4-AT2R；第一是激活ALK2-ALK1途径，减轻毛细血管疏松；第二是 抑制参与病理性心血管重塑的盐皮质激素受体(MR)。在目标1中，我们将 验证NP-6A4改善大鼠心脏和血管结构和功能参数的假设 通过增加Agtr2的表达和信号转导建立T2 DM慢性CVD模型。我们将使用我们的新产品 通过斑点跟踪检测亚临床损伤和随后的保护性重构的方法 超声心动图(STE)与组织病理学和广泛的分子信号途径相结合。在……里面 目的2，我们将研究NP-6A4是否减轻急性心肌梗死所致的心脏和血管结构损伤。 机械性和药物性损伤。我们还将调查a)NP-6A4-AT2R之间的串扰作用 和激活素样激酶(ALK2-ALK1通路)在提高毛细血管密度中的作用，以及b) NP-6A4-AT2R和MR在减轻病理性心血管重构中的相互作用。总而言之， 这项研究的阳性结果将具有很高的临床意义，因为它们验证了a)NP-6A4作为 一种治疗急性和慢性心血管疾病的新疗法，并缓解心血管疾病的性别差异，以及b) 基于STE的T2 DM亚临床心血管损害进展和缓解的诊断。

Summary: Cardiovascular Disease (CVD) remains the leading cause of death worldwide and is linked to a variety of co- morbidities including Type 2 Diabetes Mellitus (T2DM), and Obesity. Work over the last 20 years by our group and others have identified the Angiotensin II Type 2 Receptor (AT2R) as a key player in the development and pathogenesis of cardiac and vascular structural damage. Clinically, in men, loss of Agtr2 expression is associated with increased arterial stiffness, impaired kidney function, and increased pulse pressure. Literature shows that female-specific increase in AT2R expression protects murine female models from vascular injury. Healthy female (ZL-F) rats have higher cardiac expression of the X-linked Agtr2 compared to male (ZL-M) rats; but T2DM suppressed cardiac Agtr2 expression only in ZDF-F (female), not in ZDF-M (male). We posit that increasing Agtr2 expression in ZDF-F rat heart will render protection from cardiomyocyte loss and scarring and this treatment will be of particular benefit to women suffering from CVD. However, there are no AT2R agonists that can increase Agtr2 expression. We observed that NP-6A4, a novel peptide agonist of AT2R, could increase Agtr2 expression in rat and human CV cells and mitigate cardiac hypertrophy, fibrosis and capillary rarefaction in male Zucker obese rats. Our conceptually novel central hypothesis is based on these observations and states that NP-6A4-AT2R-signaling offers a new therapeutic approach to mitigate sex differences in CVD by increasing Agtr2 gene expression. We discovered two new cross-talks induced by NP- 6A4-AT2R; first is activation of ALK2-ALK1 pathway that mitigates capillary rarefaction, and the second is suppression of the mineralocorticoid receptor (MR) involved in pathological CV remodeling. In Aim 1, we will validate our hypothesis that NP-6A4 improves structural and functional cardiac and vascular parameters in rat models with chronic CVD induced by T2DM via increasing Agtr2 expression and signaling. We will use our new methods of detecting subclinical damage and subsequent protective remodeling via speckle tracking echocardiography (STE) in combination with histopathology, and extensive molecular signaling approaches. In Aim 2, we will investigate if NP-6A4 mitigates cardiac and vascular structural damage caused by acute mechanical- and drug-induced injury. We will also investigate a) the role of cross-talk between NP-6A4-AT2R and the Activin-like kinases (ALK2-ALK1 pathway) in improving capillary density, and b) the significance of the cross-talk between NP-6A4-AT2R and MR in mitigating pathological cardiovascular remodeling. Collectively, positive results of this study will have high clinical relevance since they validate a) the efficacy of NP-6A4 as a novel therapeutic for acute and chronic CVD, and for mitigating sex differences in CVD, and b) the efficacy of STE-based diagnosis of the progression and mitigation of T2DM-induced subclinical cardiovascular damage.