Translational Studies Examining Soluble EPO Receptor and EPO Resistance in Dialys

描述(申请人提供)：促红细胞生成素是一种生长因子，它彻底改变了终末期肾病(ESRD)患者的贫血治疗。在一些患者中仍然存在的一个重大临床挑战是对促红细胞生成素的相对抵抗，这导致使用连续较高的促红细胞生成素剂量和增加不良结果的风险。慢性炎症是促红细胞生成素抵抗的一个重要因素，但调节这种表型的分子途径尚不清楚。促红细胞生成素通过红细胞中的促红细胞生成素受体(EPOR)发挥作用。重要的是，替代的mRNA剪接产生了一种存在于人类血液中的可溶性EPOR(SEpoR)。虽然sEpoR的功能尚不清楚，但sEpoR可能调节促红细胞生成素信号，增加了这种可溶性受体发挥生理作用的可能性。还没有研究系统地检测ESRD的sEpoR水平。使用从终末期肾病患者获得的存档血清样本，我们已经产生了初步数据，表明在他们的血清中可以检测到sEpoR作为一种27 kDa的蛋白质，并且更高的血清sEpoR水平与更高的促红细胞生成素需求相关。此外，我们有初步数据表明，sEpoR抑制EPOR表达细胞系中促红细胞生成素介导的信号转导和转录激活因子5(Stat-5)的磷酸化。我们还证明，在体外研究中，sEpoR水平升高的患者的血清可以阻断这种磷酸化。本应用的目的是证实高水平sEpoR的血清可以通过外源性促红细胞生成素的挽救和免疫吸附sEpoR后的抑制作用，在体外阻断促红细胞生成素介导的细胞内信号转导。我们还将研究sEpoR分泌的调节，以响应已知在ESRD中升高的炎症介质。最后，我们将使用大型透析队列(美国ArMORR；德国4D)的存档样本进行两项临床研究，以检验透析开始时sEpoR水平升高独立预测后续促红细胞生成素剂量的假设。我们相信，这种探索性的R21机制将允许一个由基础科学家和临床研究人员组成的合作团队来解决ESRD患者面临的最常见和最令人烦恼的问题之一。这一应用有可能导致促红细胞生成素抵抗患者的诊断和治疗发生变化。 公共卫生相关性：慢性肾功能衰竭患者的促红细胞生成素抵抗是一个尚不清楚的常见问题。过量的促红细胞生成素与发病率和死亡率的增加有关。我们将检验这样一种假设，即肾功能衰竭患者体内循环的可溶性促红细胞生成素受体可能与该人群中的促红细胞生成素抵抗有关。

DESCRIPTION (provided by applicant): Erythropoietin is a growth factor that has revolutionized the management of anemia in patients with end-stage renal disease (ESRD). A significant clinical challenge that remains in some patients is the relative resistance to erythropoietin, which leads to use of successively higher erythropoietin doses and increased risk of adverse outcomes. Chronic inflammation is an important factor contributing to erythropoietin resistance, yet the molecular pathways mediating this phenotype are unclear. Erythropoietin acts through the erythropoietin receptor (EpoR) present in erythroblasts. Importantly, alternative mRNA splicing produces a soluble form of EpoR (sEpoR) that is present in human blood. While the function of sEpoR is unknown, sEpoR may modulate erythropoietin signaling, raising the possibility of a physiologic role for this soluble receptor. No studies have systematically examined sEpoR levels in ESRD. Using archived serum samples obtained from subjects with ESRD, we have generated preliminary data to show that sEpoR is detectable as a 27kDa protein in their serum, and that higher serum sEpoR levels correlate with increased erythropoietin requirements. In addition we have preliminary data suggesting that sEpoR inhibits erythropoietin mediated signal transducer and activator of transcription 5 (Stat-5) phosphorylation in cell lines expressing EpoR. We also demonstrate that serum from patients with elevated sEpoR levels blocks this phosphorylation in ex vivo studies. The intent of this application is to confirm that serum with high levels of sEpoR can block erythropoietin mediated intracellular signaling in vitro by rescue with exogenous erythropoietin and inhibition of the effect after immunoadsorption of sEpoR from the serum. We will also examine the regulation of sEpoR secretion in response to inflammatory mediators known to be elevated in ESRD. Finally, we will perform two clinical studies using archived samples from large dialysis cohorts (ArMORR, US; 4D, Germany) to test the hypothesis that elevated sEpoR levels at the start of dialysis independently predict subsequent erythropoietin dose. We believe this exploratory R21 mechanism will permit a collaborative team of basic scientists and clinical investigators to address one of the most common and vexing problems faced by ESRD patients. This application has the potential to lead to changes in the diagnosis and management of patients with erythropoietin resistance. PUBLIC HEALTH RELEVANCE: Erythropoietin Resistance in Chronic Renal Failure is a common problem that remains unexplained. Excessive doses of Erythropoietin are linked with increased morbidity and mortality. We will test the hypothesis that Soluble Erythropoietin Receptor circulating in patients with renal failure may contribute to Erythropoietin Resistance in this population.