Modelling mechanisms of progressive chronic kidney disease in APOL1 high-risk live-donors using BAC-Transgenic mice

技术摘要 非洲裔美国人(AA)占美国人口的12%-15%，但占美国人口的 35%的ESKD。这种差异部分归因于APOL1中携带外显子变体(G1， G2等位基因)，而所有祖先都携带主要等位基因(G0)。只有10%-15%的风险- 基因分型可发展为进行性慢性肾脏病，提示需要“二次打击”。在肾中 在活体移植中，活体供者发生进展性慢性肾脏病的风险是一个至关重要的问题。相比较 对于白色腰椎病，AA-LDS患CKD/ESKD的风险更高，同时高血压风险增加 和炎症性肾小球肾炎。自从鉴定出APOL1-G1/G2风险基因型以来， AA-LDS的风险基因型是否以及如何导致观察到的术后升高 AAS中的捐赠ESKD风险仍然是一个核心问题。在人类LDS中，显著长于 将需要后续时间来了解APOL1变种的实际捐赠归因性风险。 根据这些数据，勾勒出将改变LDS疾病风险的“第二或第三次命中” 对于APOL1风险基因型，需要使用合适的模型系统进行检查。在这里，我们带着 我们的人BAC转基因小鼠(BAC-TG)表达APOL1生理水平的优势 G0、G1或G2，我们认为这是对观察到的人类免疫学和肾脏的概括 表型包括CKD。我们进行单侧肾切除来模拟活体捐献， 具体研究两种假定的二次打击现象。在AIM-1中，我们将检验假设 肾切除后的G1-和G2-BAC-TG可发展为高血压相关的CKD进展。至 在我们的小鼠中诱导高血压，我们将使用饮食盐负荷的模型，并测试钠 限制作为一种治疗策略。详细的血流动力学和组织形态计量学研究 在这个目标上提供机械性的洞察力。基于我们最近确定的一种免疫学作用 对于APOL1-G1和G2变体，在AIM-2中，我们将模拟系统免疫激活 肾切除BAC-TG系。我们在这里的目标是定义IFNG诱导的作用和机制 新型多西环素对APOL1BAC转基因小鼠肾切除后肾小球病变的影响 诱导表达IFNG的BAC-TG细胞系。新型Podocin RTTA陷阱小鼠将被用于 寻找差异表达基因以确定APOL1-发病机制 诱导FSGS，同时比较单肾和双肾小鼠的足细胞。 此建议结合了一系列不同的技能集和独特的工具，以解决关键问题 移植中的重要机制和流行病学问题，有可能揭示 APOL1的新疗法--一个严重未得到满足的需求。

Technical Abstract Americans with African ancestry (AAs) make up 12-15% of the US population, but account for 35% of ESKD. This disparity is partly attributed to the carriage of exonic variants in APOL1 (G1, G2 risk alleles) within AAs, while all ancestries carry the major allele (G0). Only 10-15% with risk- genotype develop progressive CKD, suggesting “second hits” are needed. In kidney transplantation, the risk of progressive CKD in living donors (LDs) is a vital concern. Compared to white LDs, AA-LDs have a higher risk of CKD/ESKD along with increased risks of hypertension and inflammatory glomerulonephritis. Since the identification of APOL1-G1/G2 risk-genotypes, whether and how risk-genotype among AA-LDs contributes to the observed increased post- donation ESKD risk in AAs has remained a central question. In human LDs, significantly long follow-up times will be needed to understand actual donation-attributable risk with APOL1-variants. In light of these data, delineating the “second or third hits” that would modify disease risk in LDs with APOL1 risk-genotype, needs examination using a suitable model system. Here, we take advantage of our human BAC transgenic mice (BAC-Tg) expressing physiologic levels of APOL1 G0, G1, or G2 which we identify as recapitulating observed human immunologic and kidney phenotypes including CKD. We perform unilateral nephrectomy to model live donation, and specifically examine two putative second hit phenomena. In aim-1, we will test the hypothesis that nephrectomized G1- and G2- BAC-Tg develop hypertension-related progression of CKD. To induce hypertension in our mice, we will use models of dietary salt-loading, and also test sodium restriction as a therapeutic strategy. Detailed hemodynamic and histo-morphometric studies will provide mechanistic insight in this aim. Based on our recent identification of an immunologic role for APOL1-G1 and G2 variants, in Aim-2 we will mimic systemic immune activation in nephrectomized BAC-tg lines. Our goal here is to define the role and mechanism of Ifng-induced glomerulopathy in APOL1 BAC transgenic mice post-nephrectomy using novel doxycycline- inducible IFNG-expressing BAC-Tg lines. Novel Podocin rtTA TRAP mice will be utilized to identify differentially expressed genes to identify mechanisms in the pathogenesis of APOL1- induced FSGS, simultaneously comparing podocytes from uninephric and binephric mice. This proposal combines an array of different skill sets and unique tools to address critically important mechanistic and epidemiologic questions in transplantation, with the potential to reveal novel therapeutics for APOL1 - a profoundly unmet need.