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.

摘要 早产（妊娠期约24-37周）的人口由于晚期妊娠而迅速增长。 医疗等不幸的是，在妊娠36周之前出生的人肾脏发育不完全， 肾单位数量减少，这被假设会导致慢性肾病（CKD）风险增加 和高血压的风险。早产儿急性肾损伤（阿基）的发病率也很高。由于 由于有限的动物模型和很少的肾活检样本，阿基和CKD的发病机制以及 对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 通过抑制Ret酪氨酸激酶建立先天性低肾单位数小鼠模型（对照组的50-70%） 在肾脏发育过程中。初步研究表明，肾单位数量少的肾脏， 加速缺血再灌注损伤（IRI）后阿基向CKD转变。由于低肾单位数 已知引起肾小球超滤和对高滤过负荷的 在单个肾单位水平的Na+，我们检查了肾脏的自噬应激反应。我们发现 IRI后4周，低肾单位数的肾脏缺氧程度更高，自噬反应更强。 因此，我们计划进行研究，以验证以下假设：1）不发达国家的肾储备低 肾脏导致CKD的高风险，2）高代谢应激可能超过自噬补偿 并导致CKD的发展。Aim 1将生成和验证具有一系列低 肾单位数量（对照的25-70%）类似于人类发育不全的肾脏。我们将采取新的 化学和遗传学方法，使用携带floxed和突变Ret等位基因的小鼠， 对小分子抑制剂的敏感性。我们计划用化学物质来抑制Ret的活性 特异性抑制或缺失妊娠中晚期输尿管芽中的Ret基因。肾脏发育和 将表征肾结构和功能。目标2我们将使用这些新的小鼠模型来解决 肾单位数量低的肾脏是否更容易发生AKI的问题：1）更严重的AKI 损伤和不完全恢复，和2）在无阿基既往史的情况下CKD风险增加，或 阿基暴露后CKD发展更快。我们还将研究新生儿的临床相关模型， 使用具有低肾单位数的新生小鼠来测试阿基对发育中的肾脏的影响。目的 3将描述自噬作为一种应激反应，缺氧和代谢紊乱，在不发达的 通过检查自噬在细胞质量控制中以及在阿基向CKD转变期间的作用来研究肾脏。 研究旨在测试自噬能力和流量的下降是否响应于生理和 病理性应激有助于CKD的发展，降低代谢应激是否会延缓CKD 发展总的目标是获得急需的知识，以便在未来用于预防 并治疗不断增长的早产儿群体的肾脏疾病。