Mechanisms of the development of mesangial proliferative glomerulonephritis via constitutive-active expression of IKK2 in juxtaglomerular renin precursor cells

肾小球旁肾素前体细胞中 IKK2 组成型活性表达导致系膜增生性肾小球肾炎发生的机制

• 批准号: 419825615
• 负责人: Professor Dr. Christian Hugo
• 金额: --
• 依托单位: Bereich Nephrologie/Dialyse
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/419825615?language=en
• 关键词: Mechanisms; development; mesangial; proliferative; glomerulonephritis

Extra-/juxtaglomerular renin lineage cells (RLC) are mesangial precursor cells migrating into the glomerulus to replace mesangial cells after glomerular injury. Hereby, the RLC must receive signals from the intraglomerular processes (injury, cell death, inflammation) and react by loss of renin production, immigration, proliferation and mesangial differentiation / myofibroblast activation. It is unclear which extracellular and intracellular signals are essential for this phenotypical change of the RLC and whether this primarily regenerative mechanism can also lead pathogenetically to a mesangial proliferative glomerulonephritis. To solve this question experimentally, in an unbiased approach we differentially characterized the RLC before and during our murine mesangiolytic glomerulonephritis model in vivo before and during the glomerular repair reaction by transcriptome analysis. An early TNF-α and continuing nuclear factor κB (NF-κB) stimulation were shown during immigration. In in vitro studies using the renin lineage cell line As4.1, it was already demonstrated that the TNF-α/NF-κB system shuts down renin production and causes a phenotypical change towards activated mesangial cells/myofibroblasts. By creating a novel transgene mouse line with induction of the constitutive-active expression of the NF-κB activator IKK2 specifically in RLC, not only changes of the juxtaglomerular apparatus, but also activation of macula densa cells and a mesangial proliferative glomerulonephritis were observed. NF-κB represents a ubiquitously distributed family of transcription factors that are activated especially by inflammatory signals from extracellular area in terms of a “sensor system” and particularly change the cell phenotype toward survival, proliferation, invasion/migration and myofibroblast differentiation and activation respectively. With this application, we would like to test the main hypothesis that solely the constitutive-active expression of IKK2 (via NF-κB activation) in RLC is sufficient to cause a mesangial proliferative glomerulonephritis via induction of a phenotypical change from a juxtaglomerular renin producing cell to a renin-negative, migrating, proliferative, myofibroblast-activated and mesangial differentiated intraglomerular cell. By FACS sorting, histological and intravital microscopic cell tracing methods, we will examine whether and how the selectively activated RLC actively immigrate into the glomerulus. Mechanisms and factors will be separately evaluated and cellularly characterized concerning the RLC, the glomerulus as well as the interaction with the neighboring macula densa cells. In parallel, in vitro studies using the murine renin lineage cell line As4.1 will analyze the phenotypical impact of different IKK2 constructs after transfection. In addition, we would like to explore the question whether a TNF-α/NF-κB activation in the juxtaglomerular niche is verifiable with different human renal diseases.

肾小球外/肾小球旁肾素谱系细胞(RLC)是肾小球损伤后向肾小球内迁移以替代系膜细胞的系膜前体细胞。因此，RLC必须接受来自肾小球内过程(损伤、细胞死亡、炎症)的信号，并通过肾素产生、迁移、增殖和系膜分化/肌成纤维细胞激活而做出反应。目前尚不清楚哪些细胞外和细胞内信号对RLC的这种表型变化是必不可少的，以及这种主要的再生机制是否也会导致系膜增生性肾小球肾炎。为了从实验上解决这个问题，我们以一种公正的方法，通过转录组分析，在活体小鼠系膜溶解性肾小球肾炎模型之前和期间，在肾小球修复反应之前和期间，对RLC进行了差异表征。在移居过程中表现出早期的肿瘤坏死因子-α和持续的核因子-κB(NF-κB)刺激。在使用肾素谱系细胞系AS4.1的体外研究中，已经证明肿瘤坏死因子-α/核因子-κB系统关闭肾素的产生，并导致表型向激活的系膜细胞/肌成纤维细胞转变。通过建立一个新的转基因小鼠株系，在RLC中特异性地诱导了NF-κB激活剂IKK2的构件性活性表达，不仅观察到了肾小球旁小球结构的变化，而且观察到致密斑细胞的激活和系膜增生性肾炎。核转录因子-κB是一类广泛分布的转录因子家族，在细胞外区域的炎症信号作用下被激活，并分别改变细胞的存活、增殖、侵袭/迁移和肌成纤维细胞的分化和激活。通过这一应用，我们将检验主要假设，即仅在肾小管上皮细胞中结构性活性表达IKK2(通过激活NF-κB)就足以通过诱导从肾小球旁肾素产生细胞到肾素阴性、迁移、增殖、肌成纤维细胞激活的系膜分化肾小球内细胞的表型变化而导致系膜增生性肾炎。通过FACS分类、组织学和活体内显微细胞示踪方法，我们将检查选择性激活的RLC是否以及如何主动迁移到肾小球。将对RLC、肾小球以及与邻近致密黄斑细胞的相互作用的机制和因素分别进行评估和细胞学特征。同时，使用小鼠肾素谱系细胞系As4.1进行的体外研究将分析不同IKK2结构在转基因后的表型影响。此外，我们想要探讨的问题是，肾小球旁壁龛的肿瘤坏死因子-α/核因子-κB的激活是否可以在不同的人类肾脏疾病中得到验证。