Generation of New Mouse Models of Low Nephron Numbers to Understand Pathogenesis of AKI and CKD in Humans Born Preterm

生成新的低肾单位数小鼠模型，以了解早产人类 AKI 和 CKD 的发病机制

• 批准号: 10066348
• 负责人: FANGMING LIN
• 金额: $ 42.43万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-02-15 至 2022-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10066348
• 关键词: Acute Renal Failure with Renal Papillary Necrosis; Address; Adult; Alleles; Amino Acids; Animal Model; Autophagocytosis; Biology; Biopsy Specimen; Blood Pressure; Caring; Cells; Chemicals; Chronic; Chronic Kidney Failure; Clinical; Consumption; Data; Development; Dose; Dropout; Endowment; Engineering; Ensure; Environment; Female; Financial compensation; Future; General Population; Generations; Gentamicins; Goals; Human; Hypertension; Hypertrophy; Hypoxia; Incidence; Injury; Injury to Kidney; Investigation; Kidney; Kidney Diseases; Knowledge; Lead; Life; LoxP-flanked allele; Measurable; Measures; Medical; Metabolic; Metabolic stress; Metanephric Diverticulum; Modeling; Molecular; Mus; Mutate; Neonatal; Nephrectomy; Nephrons; Newborn Infant; Pathogenesis; Pathologic; Pharmaceutical Preparations; Phenotype; Physiological; Play; Population; Predisposition; Pregnancy; Premature Infant; Protein Tyrosine Kinase; Proteins; Quality Control; RET gene; Rattus; Recording of previous events; Recovery; Renal Hypertension; Renal tubule structure; Reperfusion Injury; Risk; Role; Severities; Stress; Structure; System; Testing; Tetanus Helper Peptide; Virulence Factors; absorption; biological adaptation to stress; chemical genetics; clinically relevant; cohort; design; genetic approach; high risk; inhibitor/antagonist; injury and repair; kidney biopsy; mouse model; mutant; nephrogenesis; nephrotoxicity; novel; offspring; operation; prevent; renal hypoxia; response; severe injury; small molecule inhibitor; success

Abstract The population of humans born preterm (~24-37 w gestation) is growing rapidly as a result of advanced medical care. Unfortunately, humans born before 36 w gestation have incomplete kidney development and low nephron numbers, which has been hypothesized to cause increased risk of chronic kidney disease (CKD) and hypertension later in life. Premature infants also have a high incidence of acute kidney injury (AKI). Due to limited animal models and few kidney biopsy samples, the pathogenesis of AKI and CKD as well as the cellular response to kidney injury and repair in this population is poorly understood. We have developed new mouse models of congenital low nephron numbers (50-70% of controls) by inhibiting Ret tyrosine kinase during kidney development. Preliminary studies showed that kidneys with low nephron numbers had an accelerated AKI to CKD transition following ischemia-reperfusion injury (IRI). Since low nephron numbers is known to cause glomerular hyperfiltration and higher metabolic demands for absorption of high filter load of Na+ at the single nephron level, we examined kidneys for stress response with autophagy. We found that kidneys with low nephron numbers were more hypoxic and had higher autophagic response 4 w post-IRI. Therefore, we have planned studies to test the following hypotheses: 1) Low renal reserve in underdeveloped kidneys contributes to high risk of CKD, and 2) High metabolic stress may exceed autophagic compensation and lead to CKD development. Aim 1 will generate and validate new mouse models with a range of low nephron numbers (25-70% of control) that resemble human underdeveloped kidneys. We will take novel chemical and genetic approaches using mice harboring a floxed and mutant Ret allele that renders it susceptibility to a small molecule inhibitor. We plan to inhibit the engineered Ret activity with the chemical inhibitor or delete Ret gene specifically in the ureteric bud during mid-late gestation. Kidney development and renal structure and function will be characterized. Aim 2 We will use these new mouse models to address the questions of whether kidneys with low nephron numbers: 1) are more susceptible to AKI with more severe injury and incomplete recovery, and 2) have increased risk of CKD in the absence of prior history of AKI or more rapid CKD development after AKI exposure. We will also study clinically relevant models of neonatal AKI using newborn mice with low nephron number to test the impact of AKI on the developing kidneys. Aim 3 will characterize autophagy as a stress response to hypoxia and metabolic perturbations in underdeveloped kidneys by examining the role of autophagy in cell quality control as well as during the AKI to CKD transition. Studies are designed to test whether a decline in autophagic capacity and flux in response to physiologic and pathologic stress contributes to CKD development, and whether reducing metabolic stress delays CKD development. The overall goal is to obtain much needed knowledge that could be used in the future to prevent and treat kidney disease in the growing population of humans born preterm.

抽象的 由于先进的技术，早产儿（妊娠 24-37 周）的人口正在迅速增长。 医疗保健。不幸的是，妊娠 36 周之前出生的人类肾脏发育不完整， 肾单位数量低，被认为会导致慢性肾脏病 (CKD) 的风险增加 以及晚年的高血压。早产儿急性肾损伤（AKI）的发生率也很高。到期的 由于动物模型和肾脏活检样本有限，AKI 和 CKD 的发病机制以及 对于该人群中肾损伤和修复的细胞反应知之甚少。我们开发了新的 通过抑制 Ret 酪氨酸激酶建立先天性低肾单位数小鼠模型（对照的 50-70%） 在肾脏发育过程中。初步研究表明，肾单位数量较少的肾脏具有 缺血再灌注损伤（IRI）后加速 AKI 向 CKD 的转变。由于肾单位数量低 已知会导致肾小球过度滤过和吸收高过滤负荷的更高的代谢需求 Na+ 在单个肾单位水平上，我们检查了肾脏的自噬应激反应。我们发现 IRI 后 4 周，肾单位数量较少的肾脏缺氧程度更高，自噬反应也更高。 因此，我们计划进行研究来检验以下假设：1）不发达地区的肾储备较低 肾脏导致 CKD 的高风险，并且 2) 高代谢应激可能超过自噬补偿 并导致CKD的发展。目标 1 将生成并验证具有一系列低 肾单位数量（对照的 25-70%）类似于人类发育不全的肾脏。我们将采取小说 使用含有 floxed 和突变 Ret 等位基因的小鼠进行化学和遗传方法，使其呈现出 对小分子抑制剂的敏感性。我们计划用化学物质抑制工程化的 Ret 活性 妊娠中晚期输尿管芽中特异抑制或删除Ret基因。肾脏发育和 将表征肾脏的结构和功能。目标 2 我们将使用这些新的鼠标模型来解决 肾单位数量低的肾脏是否更容易出现更严重的 AKI 问题： 损伤和不完全恢复，以及 2) 在没有 AKI 既往病史的情况下，罹患 CKD 的风险增加或 AKI 暴露后 CKD 发展更快。我们还将研究新生儿的临床相关模型 AKI 使用肾单位数量较低的新生小鼠来测试 AKI 对发育中肾脏的影响。目的 3 将自噬描述为欠发达地区对缺氧和代谢扰动的应激反应 通过检查自噬在细胞质量控制以及 AKI 向 CKD 转变过程中的作用来研究肾脏。 研究旨在测试自噬能力和通量的下降是否会响应生理和 病理应激有助于 CKD 的发展，以及减少代谢应激是否会延迟 CKD 发展。总体目标是获得未来可用于预防的急需知识 并治疗不断增长的早产人群的肾脏疾病。