Tissue Kallikrein, Oxidative Stress and Renal Fibrosis

描述（由申请人提供）：本提案的目的是研究钾化钾激肽系统（KKS）预防盐性肾硬化的作用和信号机制。长期目标是开发新的治疗靶点，以治疗和预防慢性肾脏疾病和终末期肾功能衰竭。在肾脏疾病的人和动物模型中，肾钾激肽水平显著降低。通过连锁分析，我们发现人体组织激肽激酶基因中的启动子多态性等位基因与盐诱导的高血压和终末期肾衰竭以及饮食钠限制变化对血压的反应存在关联。这些发现暗示了KKS在盐敏感性高血压和肾功能中的重要作用。事实上，我们的初步研究表明，在钾likrein基因转移后，升高的钾likrein/激肽水平可抑制Dahl盐敏感（DS）大鼠盐诱导的炎症细胞浸润、肾小球增大、细胞凋亡、细胞增殖和胶原含量。这些保护作用伴随着一氧化氮（NO）水平的增加和氧化应激和tgf - β表达的降低。基于这些发现，我们假设通过NO形成的KKS通过抑制氧化应激诱导的信号通路来预防和逆转盐诱导的肾硬化。以下具体目标将被用于确定介导KKS在以下方面的保护作用的信号机制：1)间质炎症，2)细胞凋亡，3)增殖和肥大以及4)导致纤维化的细胞外基质积累。信号传导机制可能涉及MCP-1、VCAM-1、ICAM-1、NF-kappaB、tgf - β、MAPK、PA/MMP、pi3激酶/Akt和p21/p27kip1。

DESCRIPTION (provided by applicant): The objective of this proposal is to study the role and signaling mechanisms by which the kallikreinkinin system (KKS) protects against salt-induced nephrosclerosis. The long-term goal is to develop novel therapeutic targets in the treatment and prevention of chronic renal disease and end-stage renal failure. Renal kallikrein levels are markedly reduced in humans and animal models with renal disease. By linkage analysis, we showed an association of a promoter polymorphic allele in the human tissue kallikrein gene with salt-induced hypertension and end-stage renal failure, as well as with blood pressure responses to changes in dietary sodium restriction. These findings implicate an important role of the KKS in salt-sensitive hypertension and renal function. Indeed, our preliminary studies show that elevated kallikrein/kinin levels (following kallikrein gene transfer) results in suppression of salt-induced inflammatory cell infiltration, glomerular enlargement, apoptosis, cell proliferation and collagen content in Dahl salt-sensitive (DS) rats. These protective effects were accompanied by increased nitric oxide (NO) levels and reduced oxidative stress and TGF-beta expression. Based on these findings, we hypothesize that the KKS through NO formation prevents and reverses salt-induced nephrosclerosis through inhibition of oxidative stress-induced signaling pathways. The following Specific Aims will be pursued to determine the signaling mechanisms that mediate the protective effects of the KKS in: 1) interstitial inflammation, 2) apoptosis, 3) proliferation and hypertrophy and 4) extracellular matrix accumulation leading to fibrosis. The signaling mechanisms may involve MCP-1, VCAM-1, ICAM-1, NF-kappaB, TGF-beta, MAPK, PA/MMP, PI3-kinase/Akt and p21/p27kip1. Enhanced kallikrein levels will be achieved by kallikrein gene delivery and kallikrein protein infusion into a salt-dependent hypertensive rat model. Cellular signaling pathways will be dissected in cultured endothelial and renal cells using specific inhibitors, neutralizing antibodies, dominant-negative DNA constructs, and small interference RNA. These studies should provide novel and in-depth information regarding the role of kallikrein/kinin in prevention and reversal of inflammation, apoptosis, proliferation, hypertrophy, and fibrosis that contribute to salt-induced nephrosclerosis.