Mechanisms of Renoprotection by Soluble Epoxide Hydrolase Inhibition

描述（由申请人提供）：可溶性环氧化物水解酶（sEH）是一种双重功能的II期代谢酶，可催化外源和内源环氧化物的水解。外源性环氧化物的sEH代谢通常导致其解毒和加速消除，而内源性环氧化物的代谢通常与环氧化物生物特性的衰减有关。sEH的内源性底物是不饱和脂肪酸环氧化物，包括环氧二碳三烯酸（EETs），这是细胞色素P450 （CYP）催化花生四烯酸代谢的主要产物，花生四烯酸是一种必需脂肪酸营养素。近年来，sEH将eet水解为相应的二羟基二碳三烯酸已成为控制eet生物效应的关键因素，包括血管活性、抗炎和抗凋亡作用。我们实验室最近的初步数据表明，化学或遗传破坏sEH活性可以防止顺铂治疗引起的急性肾损伤。具体来说，抑制sEH的保护作用与炎症减少和细胞凋亡的显著衰减有关。该提案的重点是了解sEH活动中断所提供的肾保护的机制基础。我们提出了三个具体的目的来验证抑制sEH可以防止急性肾损伤的总体假设。第一个目的是确定急性肾损伤顺铂模型中sEH抑制对肾保护作用的信号通路。NF-？B和PPAR？将检查信号，特别是关于急性肾损伤中sEH抑制的抗炎作用。sEH抑制对线粒体固有凋亡途径的影响也将被研究。为第二个目标提出的研究将把我们在急性肾损伤的顺铂模型中的发现扩展到涉及不同肾脏损伤和信号通路的其他模型。将在单侧输尿管结扎模型和缺血/再灌注模型中研究sEH抑制对肾的保护作用。最后，第三个目标将使用培养的肾上皮细胞直接测试eet对药物或缺血诱导的肾细胞损伤的保护能力。血管与管状形成的脂肪酸环氧化物在肾保护中的相对贡献也将被测试，使用具有组织特异性过表达或CYP环氧合酶和sEH破坏的小鼠品系。通过化学和遗传手段的结合来调节sEH活性和EET的产生，为我们初步观察到与sEH抑制相关的肾保护提供了关键的框架。这些研究的长期目标是为急性肾损伤的预防和治疗制定sEH的治疗调节策略。sEH抑制的抗炎和抗凋亡作用的一般性质将使我们的发现更广泛地与影响其他器官的疾病相关。

DESCRIPTION (provided by applicant): Soluble epoxide hydrolase (sEH) is a dual function Phase II metabolic enzyme that catalyzes the hydrolysis of both xenobiotic and endobiotic epoxides. sEH metabolism of xenobiotic epoxides often results in their detoxification and accelerated elimination, whereas that of endobiotic epoxides is generally associated with attenuation of epoxide biological properties. Endogenous substrates of sEH are unsaturated fatty acid epoxides, including epoxyeicosatrienoic acids (EETs), which are major products of cytochrome P450 (CYP)-catalyzed metabolism of arachidonic acid, an essential fatty acid nutrient. The hydrolysis of EETs to their corresponding dihydroxyeicosatrienoic acids by sEH has recently emerged as a key factor controlling the biological effects of EETs, including vasoactive, anti- inflammatory and anti-apoptotic effects. Recent preliminary data from our laboratory shows that chemical or genetic disruption of sEH activity protects against acute kidney injury induced by cisplatin treatment. Specifically, the protective effects of sEH inhibition are associated with decreased inflammation and a dramatic attenuation of apoptosis. The focus of this proposal is to understand the mechanistic basis for the renoprotection afforded by disruption of sEH activity. Three specific aims are proposed to test the overall hypothesis that inhibition of sEH protects against acute kidney injury. The first aim will identify the signaling pathways involved in the renoprotective effect of sEH inhibition in a cisplatin model of acute kidney injury. The role of NF-?B and PPAR? signaling will be examined, particularly with respect to the anti-inflammatory effects of sEH inhibition in acute kidney injury. The effect of sEH inhibition on the intrinsic mitochondrial apoptotic pathway will also be investigated. Studies proposed for the second aim will extend our findings in a cisplatin model of acute kidney injury to additional models which involve different renal insults and signaling pathways. The renoprotective properties of sEH inhibition will be studied in both a unilateral ureter ligation model and in ischemia/reperfusion. Finally, the third aim will directly test the ability of EETs to protect against drug- or ischemia-induced renal cell injury, using cultured renal epithelial cells. The relative contribution of vascular versus tubular formed fatty acid epoxides in renoprotection will also be tested, using mouse strains with tissue specific overexpression or disruption of CYP epoxygenases and sEH. A combination of chemical and genetic tools to modulate sEH activity and EET production provide the critical framework to advance our preliminary observation of renoprotection associated with sEH inhibition. A long term goal of these studies is to develop strategies for the therapeutic modulation of sEH for the prevention and treatment of acute kidney injury. The general nature of the anti-inflammatory and anti-apoptotic effects of sEH inhibition will make our findings more broadly relevant to diseases affecting other organs as well. PUBLIC HEALTH RELEVANCE: Acute kidney injury is a complex syndrome occurring in 20% to 30% of critically ill patients, and is associated with increased mortality, hospitalization, use of healthcare resources, and costs. Despite decades of research in animal models, effective strategies for prevention of acute kidney injury have yet to make it to the clinic. The studies proposed in this application will explore a novel pathway for protection against acute kidney injury which exploits an abundant renal fatty acid epoxide with established roles in inflammation and apoptosis.