Role of PPARalpha in acute kidney injury

描述（由申请方提供）：我们建议检查底物氧化、脂毒性和近端小管细胞死亡之间的关系。我们已经表明，使用配体激活PPARalpha，或通过使用转基因小鼠增加近端小管中PPARalpha的表达来改善缺血再灌注损伤（IRI）和顺铂肾毒性模型中的肾功能。我们的初步研究表明，与野生型小鼠相比，在经历单侧缺血和单侧输尿管梗阻（UUO）的PPARalpha Tg小鼠中，近端小管细胞死亡显著减少，间质纤维化减少。我们的中心假设预测，近端小管和周细胞PPARalpha表达和活性的增加阻断了肾小管间质炎症和肾纤维化，这是肾纤维化的标志。 从急性到慢性肾病（CKD）的进展。 具体目标1。确定近端小管（PT）-PPARalpha增加是否阻断肾小管间质纤维化。我们推测近端小管PPARalpha表达增加可减轻肾纤维化。我们将使用野生型、基因缺陷型PPARalpha小鼠、PPARalpha转基因小鼠和两种肾纤维化动物模型来确定增加的脂肪酸氧化、脂蛋白 脂肪酶活性和增加的自噬有助于降低脂毒性并防止肾纤维化模型中的近端小管细胞死亡。 具体目标2。研究近端小管（PT）-PPARalpha增加减少肾纤维化的机制。我们将讨论几种PPARalpha表达可减少肾纤维化的独立机制：1）通过改变UUO小鼠中的巨噬细胞表型，2）通过增加UUO逆转后的结构修复和3）通过减少肾间质中的肌成纤维细胞增殖。 具体目标3。确定PPARalpha减少小鼠肾周细胞中肾纤维化的细胞机制。我们的初步研究表明，PPARalpha的表达以及脂肪酸氧化基因的表达显着减少从UUO小鼠分离的周细胞。我们提出从野生型小鼠中分离和培养小鼠肾周细胞1）以确定体外PPARalpha过表达对周细胞向肌成纤维细胞转变的影响，2）以确定体外PPARalpha介导的脂肪酸氧化增加、中性脂质积累减少和脂肪生成变化是否有助于周细胞向肌成纤维细胞的转变，3）确定增加的细胞自噬对周细胞向肌成纤维细胞转变的作用，和4）确定PPARalpha缺乏对初级周细胞向肌成纤维细胞转变的作用。 总之，这些研究将进一步推进我们的周细胞代谢和功能的知识，并应提供额外的治疗目标，以管理慢性肾脏疾病。

DESCRIPTION (provided by applicant): We propose to examine the relationship between substrate oxidation, lipotoxicity and proximal tubule cell death. We have shown that activation of PPARalpha using a ligand, or by increased expression of PPARalpha in the proximal tubule using transgenic mice ameliorates kidney function in the ischemia reperfusion injury (IRI), and cisplatin model of nephrotoxicity. Our preliminary studies demonstrate a significant reduction in proximal tubule cell death and reduced interstitial fibrosis in PPARalpha Tg mice subjected to both unilateral ischemia and Unilateral Ureteral Obstruction (UUO), when compared to wild type mice. Our central hypothesis predicts that increased expression and activity of proximal tubule and pericyte PPARalpha interdict tubulo-interstitial inflammation and renal fibrosis, a hallmark of the progression from Acute to Chronic Kidney Disease (CKD). Specific Aim 1. To determine whether increased proximal tubule (PT)-PPARalpha interdicts with tubulo-interstitial fibrosis. We hypothesize that increased expression of proximal tubule PPARalpha attenuates renal fibrosis. We will use wild type, genetically deficient PPARalpha mice, and PPARalpha transgenic mice and two animal models of renal fibrosis to determine if increased fatty acid oxidation, lipoprotein lipase activity, and increased autophagy contribute to reduced lipotoxicity and prevent proximal tubule cell death in models of renal fibrosis. Specific Aim 2. To examine the mechanisms by which increased proximal tubule (PT)-PPARalpha reduces renal fibrosis. We will address several independent mechanisms by which PPARalpha expression could reduce renal fibrosis: 1) by changing macrophage phenotype in UUO mice 2) by increasing structural repair after reversal of UUO and 3) by reducing myofibroblast proliferation in renal interstitium. Specific Aim 3. To determine cellular mechanisms by which PPARalpha reduces renal fibrosis in mouse kidney pericytes. Our preliminary studies show that PPARalpha expression as well as expression of fatty acid oxidation genes are significantly reduced in pericytes isolated from UUO mice. We propose to isolate and culture mouse kidney pericytes from wild type mice 1) to determine the effects of PPARalpha overexpression on pericyte to myofibroblasts transition in vitro, 2) to determine whether PPARalpha mediated increase in fatty acid oxidation, reduced neutral lipid accumulation, and changes on adipogenesis contribute to the transition from pericytes to myofibroblasts in vitro, 3) to determine the role of increased cellular autophagy on pericyte to myofibroblasts transition, and 4) to determine the role of PPARalpha deficiency on primary pericytes transition to myofibroblasts. Altogether these studies will further advance our knowledge of pericyte metabolism and function and should provide additional therapeutic targets to manage chronic kidney disease.