CD14 and Salt-Sensitive Hypertension

摘要 高血压是心血管、脑血管和肾脏疾病的主要可改变的危险因素，并且 是世界上导致疾病和死亡的最大个体因素。盐敏感型高血压 占高血压人口30%-50%的个体比有盐分的受试者死亡率更高。 顽固性高血压并表现出肾脏终末器官损害。我们最近发现了一种新的抗高血压药物 分化簇14(CD14)介导的机制在女性中相对增强 男性。CD14是Toll样受体4(TLR4)的联合受体。有趣的是，CD14在卵巢癌中的表达 心血管疾病和高血压患者外周血白细胞和血浆CD14蛋白水平升高 人类。我们认为肾脏巨噬细胞中的CD14信号与TLR4和Leads的作用相反 抑制自由基和促炎细胞因子IL-1β的释放，钝化T细胞的激活，以及 减轻盐敏感型高血压。 这个项目是基于我们独特的(有些令人惊讶的)观察到的CD14的基因缺失， 该基因在喂食高盐的Dahl盐敏感(SS)大鼠肾脏的巨噬细胞中上调，导致 促炎症细胞因子IL-1、β和活性氧的释放增加。值得注意的是，我们观察到 缺乏CD14(SSCD14-/-)的雌性Dahl SS大鼠表现出放大的盐敏感型高血压和肾脏损害 与野生型窝种相比。进一步的研究表明，CD14缺失的影响是依赖的 在造血细胞上，在雌性中扩增，在缺乏吞噬NADPH氧化酶2(NOX2)的大鼠中消除。 这些令人兴奋的数据表明，CD14在盐敏感的发育过程中发挥了意想不到的性别依赖性作用。 高血压和肾脏损伤。这项提议将检验这样一种假设，即维生素A的降压作用 肾脏巨噬细胞中的CD14导致肾脏T细胞活性降低，减弱对盐的敏感性 高血压，并减少肾终末器官损害。这一假设将在三个具体目标中得到解决。 目标1将阐述CD14对盐敏感型高血压和 相关的肾脏损伤包括抑制巨噬细胞中TLR4介导的信号转导。目标2将解决 巨噬细胞中NOX2升高调节高盐喂养Dahl SS大鼠血压升高的假说， 这种效应在女性中被CD14减弱，在男性中被TLR4放大。目标3将解决以下假设 TLR4的降压作用和CD14的降压作用是由相应的 自由基依赖过程中压力、利钠-利尿和肾内血流动力学的变化 在巨噬细胞和T细胞中由NOX2释放。该提案采用了体外和体内方法来 使用为这笔赠款开发的独特的、基因工程的大鼠品系来解决这个假说，新的免疫 细胞移植方法，以及评估清醒大鼠血流动力学变量的最新方法学。

SUMMARY Hypertension is a primary modifiable risk factor for cardiovascular, cerebrovascular, and renal disease, and is the largest individual contributing factor to disease and mortality in the world. Salt-sensitive hypertensive individuals, who comprise 30-50% of the hypertensive population, have greater mortality than subjects with salt- resistant hypertension and exhibit renal end-organ damage. We recently discovered a novel anti-hypertensive mechanism that is mediated by Cluster of Differentiation 14 (CD14) and enhanced in females relative to males. CD14 is a co-receptor with Toll Like Receptor 4 (TLR4). Interestingly, the expression of CD14 in leukocytes and level of plasma CD14 protein are increased in cardiovascular disease and hypertension in humans. We propose that CD14 signaling in macrophages in the kidney opposes the effects of TLR4 and leads to the attenuated release of free radicals and the proinflammatory cytokine Il-1β, blunted T cell activation, and attenuated salt-sensitive hypertension. This project is based upon our unique (and somewhat surprising) observation that genetic deletion of CD14, which is upregulated in macrophages in the kidney of Dahl Salt-Sensitive (SS) rats fed high salt, leads to increased release of the proinflammatory cytokine Il-1β and reactive oxygen species. Remarkably, we observed that female Dahl SS rats lacking CD14 (SSCD14-/-) exhibit amplified salt-sensitive hypertension and renal damage compared to wild type littermates. Further study demonstrated that the effects of CD14 deletion are dependent on hematopoietic cells, amplified in females, and eliminated in rats lacking phagocytic NADPH oxidase 2 (NOX2). These exciting data indicate an unexpected, sex-dependent role of CD14 in the development of salt-sensitive hypertension and renal damage. This proposal will test the hypothesis that the anti-hypertensive effects of CD14 in macrophages in the kidney lead to decreased activation of T cells in the kidney, attenuated salt-sensitive hypertension, and decreased renal end-organ damage. The hypothesis will be addressed in three specific aims. Aim 1 will address the hypothesis that the protective effects of CD14 against salt-sensitive hypertension and associated renal damage involve inhibition of TLR4-mediated signaling in macrophages. Aim 2 will address the hypothesis that elevated NOX2 in macrophages mediate elevated blood pressure in Dahl SS rats fed high salt, an effect attenuated in females by CD14 and amplified in males by TLR4. Aim 3 will address the hypothesis that the pro-hypertensive effects of TLR4 and the anti-hypertensive effects of CD14 are mediated by corresponding changes in pressure natriuresis-diuresis and intrarenal hemodynamics in a process dependent upon free radicals released from NOX2 in macrophages and T cells. The proposal employs in vitro and in vivo approaches to address the hypothesis using unique, genetically-engineered rat strains developed for this grant, novel immune cell transfer approaches, and state-of-the art methodology to assess hemodynamic variables in conscious rats.