Autocrine and paracrine podocyte signals decrease glomerular function/health in aged kidneys

项目摘要/摘要 这个问题的总体范围是，随着美国人寿命的延长，肾脏疾病变得更加严重 很丰富。特别是，老年患者面临更糟糕的疾病结局，他们现在是 接受第一次透析。这项提议的目标是证明老化的足细胞是许多 肾小球随着年龄的增长而变化。足细胞的变化和丢失仍然是与年龄相关的最佳预测因子 肾小球硬化，肾小球滤过率降低。尚未满足的主要需求是了解足细胞的机制 衰老和衰老的足细胞与邻近的壁上皮细胞(PECs)之间的串扰。结案 这些知识差距，我们进行了转录组分析，比较了老年人和年轻人的足细胞 老鼠。令我们惊讶的是，免疫反应过程的转录本，如炎症小体成分， 炎症因子(如肿瘤坏死因子α、干扰素、白介素类和趋化因子)和SASP显著 富足了。重要的是，在人类肾脏活检中也证实了类似的变化。 基于这些初步数据，我们提出了一种新的模式，即衰老的足细胞分泌炎症 自分泌环路中的信号和SASP直接影响足细胞本身。具体目标#1将证明 这种新发现的炎症性老化足细胞表型直接缩短了足细胞的寿命 并缩短了他们的健康寿命。我们将在衰老的足细胞中检验以下假设：(1)炎症体诱导 从头开始的细胞内炎症减少了足细胞的寿命；(2)PD1信号通路作用于下游 NLRP3炎症体；(3)分泌的炎症介质的一个特定亚群加速了 足细胞通过自分泌环路老化表型。 我们还提出了第二种新的范式，在该范式中，衰老的足细胞在加速过程中起旁分泌作用 佩克老化。这是基于以下事实：(I)足细胞老化在时间上先于PEC老化；(Ii)PEC老化是 通常只存在于足细胞呈现衰老表型的单个肾小球中；(Iii)抑制 衰老足细胞中的炎症体或PD1通路可减少PEC的老化。在具体目标2中，我们建议 衰老足细胞来源的SASP和炎性细胞因子通过以下途径加速PEC的衰老表型 旁分泌循环。我们将检验以下假设：(1)老年小鼠的炎性足细胞表型 预防和加速PEC老化。(2)源自以下来源的SASP和炎性细胞因子的独特子集 老化足细胞加速了PEC的衰老表型。 这些研究基于许多创新的实验方法，包括转基因衰老研究。 小鼠，原代人类足细胞和PECs，实验设计方法学和新的共培养模型。 最后，我们研究的重点是通过交叉我们的鼠标来产生短期的翻译影响 关于老年人肾脏的大量转录数据集及其对发育的长期影响 将对抗年龄相关性肾功能衰退的治疗策略。

PROJECT SUMMARY/ABSTRACT The overall scope of the problem is that as the US population lives longer, kidney disease becomes more abundant. In particular, elderly patients face worse disease outcomes, and they are now the largest group to undergo first-time dialysis. The goal of this proposal is to prove that aged podocytes are central to the many glomerular changes with aging. Changes to and loss of podocytes remain the best predictors of age-related glomerulosclerosis and reduced GFR. Major unmet needs are understanding the mechanisms of podocyte aging and the crosstalk between aged podocytes and neighboring parietal epithelial cells (PECs). To close these knowledge gaps, we performed a transcriptome analysis comparing podocytes from aged vs. young mice. Much to our surprise, transcripts for immune response processes such as inflammasome components, inflammatory factors (e.g. TNFα, interferons, interleukins and chemokines) and SASPs were significantly enriched. Importantly, similar changes were confirmed in human kidney biopsies. Based on these preliminary data, we propose a novel paradigm that aged podocytes secrete inflammatory signals and SASPs that in autocrine loops directly impact podocytes themselves. Specific Aim #1 will prove that this newly discovered inflammatory aged podocyte phenotype directly shortens the podocyte's lifespan and reduces their health-span. We will test the hypotheses that in aged podocytes: (1) Inflammasome-induced de novo intracellular inflammation reduces podocyte lifespan; (2) The PD1 signaling pathway acts downstream of the NLRP3 inflammasome; (3) A specific subset of secreted inflammatory mediators accelerates the podocyte aging phenotype through autocrine loops. We also propose a second novel paradigm in which aged podocytes play a paracrine role in accelerating PEC aging. This is based on the facts that (i) podocyte aging temporally precedes PEC aging; (ii) PEC aging is typically only present in individual glomeruli in which podocytes exhibit an aged phenotype; (iii) inhibition of the inflammasome or PD1 pathways in aged podocytes reduces PEC aging. In Specific Aim #2 we propose that SASPs and inflammatory cytokines derived from aged podocytes accelerate the PEC aging phenotype through paracrine loops. We will test the hypotheses that: (1) The inflammatory podocyte phenotypes in aged mice precedes and accelerates PEC aging. (2) A distinct subset of SASPs and inflammatory cytokines derived from aged podocytes accelerates the PEC aging phenotype. These studies are based on many innovative experimental approaches including aging studies in transgenic mice, primary human podocytes and PECs, Design-of-Experiment methodology and novel co-culture models. Finally, the focus of our study is significant for its short-term translational impact by intersecting our mouse data with a large transcriptomic data set on aged human kidneys and its long-term impact in developing therapeutic strategies that will counter the age-dependent demise of kidney function.