Role of apolipoprotein M in acute kidney injury

描述（由申请人提供）： 我们的研究将集中于确定肾源性载脂蛋白M（ApoM）在急性肾损伤（阿基）期间脂质蓄积和近端小管细胞死亡中的作用。血清中的ApoM主要存在于高密度脂蛋白（HDL）中，然而，ApoM也在肝和肾组织中表达。我们的初步研究表明，肾源性ApoM主要在近端小管中表达，并且其表达在阿基期间减少。我们还发现在暴露于顺铂的野生型小鼠以及人ApoM转基因小鼠中，在血液尿素氮和血清肌酐变化之前，尿ApoM的脱落增加。由于最近的研究支持ApoM作为抗炎和抗动脉粥样硬化脂蛋白的作用，我们计划使用野生型小鼠，人ApoM转基因小鼠和ApoM敲除小鼠（可从哥本哈根大学Lars Bo Nielsen博士的实验室获得）来比较顺铂和缺血再灌注损伤对肾功能的影响。我们将确定肾脏ApoM表达增加对缺血再灌注和顺铂介导的阿基期间发生的炎性细胞流入的影响。此外，我们将确定在人ApoM转基因小鼠中，是否由近端小管中ApoM表达减少介导的肾中性脂质蓄积增加导致近端小管细胞死亡和ARF。我们期望看到与野生型小鼠相比，人ApoM转基因小鼠的肾功能得到改善。最后，我们将使用从人ApoM转基因小鼠或TKPTS细胞获得的原代培养物（永生化近曲小管细胞系）感染腺ApoM，以确定1）ApoM表达增加具有细胞保护性的机制，以及ApoM增加的细胞保护性应答是否与中性脂质积累减少，凋亡/坏死细胞死亡减少，当这些近端小管暴露于顺铂或缺氧/复氧损伤时。我们的初步研究还表明，使用PPARalpha配体如贝特类药物可预防顺铂诱导的肾源性ApoM的尿脱落，并改善肾功能。我们计划检查是否表达，分泌和功能的载脂蛋白M在近端肾小管细胞在培养物中是不同的近端肾小管分离自PPARalpha转基因小鼠相比，近端肾小管分离自野生型小鼠。总体而言，我们的研究将有助于更好地了解肾源性载脂蛋白M的代谢作用，将确定其作为阿基早期生物标志物的作用，并将阐明近端小管中增加PPARalpha功能和活性的保护机制。 公共卫生相关性： 对退伍军人医疗保健的潜在影响：急性肾损伤是一种严重的并发症，不仅见于战斗中，也见于我们住院的退伍军人患者，导致发病率、死亡率和住院时间增加。我们拟定的研究将检查载脂蛋白M作为阿基期间观察到的肾组织中性脂质蓄积的潜在贡献者的作用。PPARalpha配体如贝特类的使用提供了一种新的治疗工具，以减少肾组织损伤，并降低与阿基发展相关的高发病率和死亡率

DESCRIPTION (provided by applicant): PROJECT SUMMARY/ABSTRACT Our studies will focus on defining the role that kidney-derived Apolipoprotein M (ApoM) plays in lipid accumulation and proximal tubule cell death during Acute Kidney Injury (AKI). ApoM in the serum is mainly present in High Density Lipoproteins (HDL), however, ApoM is also expressed in liver and kidney tissue. Our preliminary studies show that kidney-derived ApoM is mainly expressed in the proximal tubule, and that its expression is reduced during AKI. We find also increased shedding of urinary ApoM that precedes changes in blood urea nitrogen and serum creatinine in wild type mice as well as human ApoM transgenic mice exposed to cisplatin. Since recent studies support the role of ApoM as an anti-inflammatory and anti-atherogenic lipoprotein, we plan to use wild type mice, human ApoM transgenic mice and ApoM knockout mice (available to us from the laboratory of Dr Lars Bo Nielsen, University of Copenhagen) to compare the effects of cisplatin and ischemia reperfusion injury on renal function . We will determine the effect(s) of increased expression of kidney ApoM on the influx of inflammatory cells that occurs during ischemia reperfusion and cisplatin-mediated AKI. In addition, we will determine in human ApoM transgenic mice, whether increased accumulation of kidney neutral lipids mediated by reduced expression of ApoM in the proximal tubule leads to proximal tubule cell death and ARF. We expect to see amelioration of kidney function in human ApoM transgenic mice when compared to wild type mice. Finally, we will use primary cultures obtained from human ApoM transgenic mice, or TKPTS cells (immortalized proximal tubule cell line) infected with adeno ApoM, to determine 1) the mechanisms by which increased expression of ApoM is cytoprotective, and whether the cytoprotective response of increased ApoM relates to reduced accumulation of neutral lipids, reduced apoptotic/necrotic cell death, when these proximal tubules are exposed to either cisplatin or hypoxia/ reoxygenation injury. Our preliminary studies also show that the use of PPARalpha ligand like fibrates prevent cisplatin-induced urinary shedding of kidney-derived ApoM and ameliorate kidney function. We plan to examine whether the expression, secretion and function of ApoM in proximal tubular cells in culture are different in proximal tubules isolated from PPARalpha transgenic mice when compared to proximal tubules isolated from wild type mice. Overall, our studies will contribute to a better understanding of the metabolic effects of kidney-derived apolipoprotein M, will define its role as an early biomarker of AKI, and will elucidate the protective mechanisms of increasing PPARalpha function and activity in the proximal tubule. PUBLIC HEALTH RELEVANCE: Potential Impact to Veterans Health Care: Acute kidney injury is a serious complication seen not only in combat but also in our hospitalized veteran patients, resulting in increased morbidity, mortality, and length of hospital stay. Our proposed studies will examine the role of apolipoprotein M as potential contributor to the observed accumulation of neutral lipids in kidney tissue during AKI. The use of PPARalpha ligand like fibrates offers a novel therapeutic tool to reduce kidney tissue damage, and to reduce the high morbidity and mortality associated with the development of AKI