Cellular Cholesterol and Podocyte function in Diabetic Kidney Disease

 描述（由申请人提供）：糖尿病肾病（DKD）是美国终末期肾病的最常见原因，足细胞损伤是DKD的重要特征。然而，DKD中足细胞减少的机制知之甚少。在暴露于T1 D或T2 D和DKD患者血清的永生化人足细胞中观察到足细胞凋亡和RhoA活化，并伴有胆固醇蓄积，并且可以通过环糊精（CD）（一种从细胞中去除胆固醇并保护糖尿病小鼠免受蛋白尿发展的寡糖）预防。在临床和实验性DKD中已经描述了过度的肾小球胆固醇沉积，其与受损的胆固醇流出相关，如通过ATP结合盒转运蛋白（ABCA 1）表达的下调所表明的，并且可以由TNF α诱导。游离胆固醇和高胆固醇对足细胞损伤的相对作用尚不清楚。我们的长期目标是开发针对DKD足细胞胆固醇蓄积的治疗策略。我们假设：1）TNFa介导的足细胞中ABCA 1的下调导致胆固醇的积累; 2）在早期DKD中酯化胆固醇的积累导致足细胞肥大，而在晚期DKD中游离胆固醇导致足细胞凋亡; 3）减少细胞内胆固醇积累的治疗策略保护DKD中的足细胞。为了检验这些假设，我们将利用遗传修饰的小鼠模型、NIH批准的DKD模型和人足细胞中的体外实验，目的是：1-确定足细胞中的ABCA 1缺乏是否导致DKD中的足细胞损伤和蛋白尿。2-确定游离胆固醇和酯化胆固醇对足细胞损伤的相对贡献。3-确定是否存在足细胞减少症 DKD可以通过CD和/或ABCA 1诱导剂消耗足细胞游离胆固醇来预防。这一建议是创新的，因为细胞内游离和酯化胆固醇在DKD足细胞损伤发病机制中的作用从未被探索过。为了将创新与足够的专业知识相匹配，我们组建了一个独特的研究团队，其中包括足细胞生物学家，脂质生物学家，病理学家，肾病学家和内分泌学家。我们的目标是通过发现适合治疗干预的新疾病机制来推进与DKD相关的知识。

 DESCRIPTION (provided by applicant): Diabetic kidney disease (DKD) is the most common cause of end-stage kidney disease in the US, and podocyte injury is an important feature of DKD. However, mechanisms of podocytopenia in DKD are poorly understood. Podocyte apoptosis and activation of RhoA are observed in immortalized human podocytes exposed to the sera of patients with T1D or T2D and DKD in conjunction with cholesterol accumulation and can be prevented by cyclodextrin (CD), an oligosaccharide that removes cholesterol from cells and that protects diabetic mice from the development of proteinuria. Excessive glomerular cholesterol deposition has been described in clinical and experimental DKD, is associated with impaired cholesterol efflux as suggested by the down-regulation of ATP-binding cassette transporter (ABCA1) expression, and can be induced by TNFa. The relative contribution of free and esterifed cholesterol to podocyte injury is unknown. Our long-term goal is to develop therapeutic strategies that target podocyte cholesterol accumulation in DKD. We hypothesize that: 1) TNFa-mediated downregulation of ABCA1 in podocytes results in accumulation of cholesterol; 2) accumulation of esterified cholesterol in early DKD causes podocyte hypertrophy while free cholesterol in late DKD causes podocyte apoptosis; 3) therapeutic strategies that reduce intracellular cholesterol accumulation protect podocytes in DKD. In order to test these hypotheses, we will utilize genetically modified mouse models, NIH approved models of DKD and in vitro experiment in human podocytes with the aim to: 1-Determine if ABCA1 deficiency in podocytes worsens podocyte injury and proteinuria in DKD. 2-Determine the relative contribution of free and esterified cholesterol to podocyte injury. 3-Determine if podocytopenia in DKD can be prevented by podocyte depletion of free cholesterol with CD and/or ABCA1 inducers. This proposal is innovative as the role of intracellular free and esterified cholesterol n the pathogenesis of podocyte injury in DKD has never been explored. In order to match innovation with adequate expertise, we have assembled a unique team of investigators that includes podocyte biologists, lipid biologists, pathologists, nephrologists and endocrinologists. We aim to advance the knowledge related to DKD by uncovering novel disease mechanisms amenable to therapeutic intervention.