Pathophysiology of FSGS

FSGS 的病理生理学

• 批准号: 9191361
• 负责人: STUART E DRYER
• 金额: $ 33.21万
• 依托单位: UNIVERSITY OF HOUSTON
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-12-15 至 2019-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9191361
• 关键词: Albuminuria; Animal Model; Animals; Back; Blood; Case Study; Cell surface; Chemicals; Chronic; Clinical; Clinical Research; Consensus; Data; Disease; Disease remission; Electrophysiology (science); End stage renal failure; Etiology; Focal Segmental Glomerulosclerosis; Functional disorder; Generations; Genetic; Immune; Information Systems; Integrin beta3; Kidney; Kidney Failure; Kidney Transplantation; Knock-out; Knockout Mice; Laboratories; Mechanics; Mediating; Methods; Mind; Modeling; Molecular Weight; Mus; Mutation; NPHS2 protein; Nephrosis; Nephrotic Syndrome; Pathologic; Pathology; Pathway interactions; Patients; Permeability; Pharmacotherapy; Plasma; Rattus; Reactive Oxygen Species; Recurrence; Refractory; Relapse; Research; Role; Sampling; Serum; Signal Transduction; Stimulus; TNF gene; Testing; Therapeutic; Transgenic Mice; Tyrosine Phosphorylation; United States; Urokinase Plasminogen Activator Receptor; Work; base; cohort; drug discovery; experimental study; gain of function mutation; glomerular filtration; glomerular function; graft failure; in vivo; mouse model; new therapeutic target; novel; overexpression; podocyte; programs; public health relevance; response; small molecule; theories; therapeutic target; trafficking

 DESCRIPTION (provided by applicant): Primary focal and segmental glomerulosclerosis (FSGS) is a common cause of end-stage renal disease. Many of these patients are refractory to current treatments and primary FSGS often recurs after kidney transplantation. There is now a consensus that many cases of primary and recurrent FSGS are driven by circulating "permeability factors" that induce leakiness in the glomerular filtration barrier and ultrastructurl changes in podocytes. Some rare non-recurring genetic forms of FSGS are associated with gain-of-function mutations in Ca2+-permeable TRPC6 channels, resulting in chronic Ca2+ overload. Our central hypothesis is that increased podocyte TRPC6 activity drives pathology in FSGS, and this occurs in response to circulating permeability factors in primary FSGS, and possibly in response to hyperfiltration in secondary FSGS. If so, inhibition of TRPC6 could be a broadly useful therapeutic approach for FSGS of several etiologies. We also propose that primary FSGS can be caused by multiple circulating permeability factors with distinct but synergistic modes of action that converge on podocyte TRPC6. This research will focus on two circulating factors, TNF and suPAR, that have been implicated in some clinical studies and case reports. Our preliminary studies indicate that sera from several recurrent FSGS patients cause profound changes in podocyte TRPC6 channels, including markedly increased TRPC6 activation by mechanical stimuli, and increased expression on the podocyte cell surface. These sera also cause loss of podocin, which can explain increased mechanical activation of TRPC6. Some of these sera also evoke increases in β3-integrin. The activity in sera from two recurrent FSGS patients taken during relapse and remission correlates with the patient's clinical status. Similar changes in TRPC6 gating and podocin were seen in glomeruli isolated from chronic PAN-treated rats, a model of secondary FSGS, and in podocytes treated with suPAR. TNF also increases TRPC6 activity in podocytes, but probably through mechanisms distinct and additive with those of suPAR. Here we will characterize modulation of endogenous podocyte TRPC6 channels by a larger sample of recurrent FSGS sera and we will determine if TNF and/or suPAR are required for their effects on podocytes. We present data showing that both of these factors contribute to activity in one of the recurrent FSGS serum samples. We will also examine transduction pathways whereby FSGS sera, suPAR, and TNF modulate TRPC6 channels. We will also examine changes in podocyte TRPC6 gating and maximal currents in in vivo mouse models of FSGS, using novel electrophysiological methods that we developed for our studies of podocin and chronic PAN nephrosis. Finally, we will also determine if TRPC6 knockout protects glomerular function in mice with albuminuria evoked by LPS, and in a transgenic mouse with albuminuria due to elevated circulating low molecular weight suPAR. The results could provide a strong rationale for drug discovery programs based on inhibition of mechanical and/or chemical activation of TRPC6 channels.

 描述（由适用提供）：原发性局灶性和节段性肾小球硬化（FSG）是终末期肾脏疾病的常见原因。这些患者中的许多患者对当前治疗而难治性，而原发性FSG经常在肾脏移植后复发。现在已经达成共识，许多原发性和复发性FSG的病例是由循环“渗透性因子”驱动的，这些因子诱导了肾小球滤过屏障的渗漏，并且足结构术的超结构变化。 FSG的一些罕见的非经常性遗传形式与Ca2+可渗透的TRPC6通道中的功能增益突变有关，从而导致慢性Ca2+过载。我们的中心假设是，增加的足细胞TRPC6活性驱动了FSG中的病理，这是对原发性FSG中循环渗透性因子的响应而发生的，并且可能响应于二级FSG的过滤。如果是这样，抑制TRPC6可能是几种病因的FSG的广泛有用的治疗方法。我们还建议，主要的FSG可能是由多个循环渗透率因子引起的，具有不同但协同的作用模式，这些动作模式会收敛于Podocyte TRPC6。这项研究将重点介绍两个临床研究和病例报告中暗示的两个循环因素，即TNF和SUPAR。我们的初步研究表明，来自几个复发性FSGS患者的血清引起了足细胞TRPC6通道的严重变化，包括通过机械刺激显着增加TRPC6激活，以及在足细胞表面上的表达增加。这些血清还会导致足球素的丧失，这可以解释TRPC6的机械激活增加。这些血清中的一些还引起了β3-整合素的增加。在继电器期间服用的两名复发性FSGS患者的血清活性与患者的临床状况相关。在从慢性泛处理大鼠（次级FSGS的模型）和用SUPAR处理的足细胞中分离出的肾小球中，TRPC6门控和Podocin发生了类似的变化。 TNF还增加了足细胞中的TRPC6活性，但可能通过与Supar的机制不同和添加的机制。在这里，我们将通过更大的复发性FSGS血清样本来表征内源性足细胞TRPC6通道的调节，我们将确定TNF和/或SUPAR是否对它们对足细胞的影响是必需的。我们还将检查FSGS Sera，SuPar和TNF调节TRPC6通道的翻译途径。我们还将使用新型的电生理方法来研究FSG的体内小鼠模型中的足细胞TRPC6门控和最大电流的变化，这些方法是为了研究Podocin和Podocin和慢性PAN肾脏症的研究。最后，我们还将确定TRPC6敲除是否保护LPS引起的蛋白尿的小鼠中的肾小球功能，以及由于循环循环的低分子量Supar而具有蛋白尿的转基因小鼠。基于抑制TRPC6通道的机械和/或化学激活，该结果可以为药物发现计划提供强大的理由。