The Relation of Soluble Klotho with Cardiovascular Disease, Chronic Kidney Disease Progression, and Blood Pressure in the Systolic Blood Pressure Intervention Trial

摘要 可溶性α-klotho(“klotho”)具有维持细胞健康的全身性作用，包括减少氧化 心脏和肾脏的应激和纤维化。肾小管是循环(可溶性)血栓的主要来源 因此，慢性肾脏病(CKD)的发展导致Klotho虚证。克洛索缺乏症 也可能矛盾地促进CKD的进展。Klotho缺乏症啮齿动物模型表现出脆弱性 对肾脏损伤和肾脏疾病进展的影响，而外源性Klotho的应用则是为了减轻肾脏 损害和疾病进展。Klotho缺乏也可能导致过度的心血管疾病 当Klotho基因敲除小鼠显示血管钙化和病理性心脏重构时，CKD的风险 伴有心肌肥大和纤维化。此外，血压(BP)可能会影响临床前的klotho水平。 数据显示，多种高血压模型都会导致Klotho虚证。到目前为止，大多数临床上的 检测可溶性Klotho的研究主要依赖于单一的商业来源的ELISA。确实有 由于临床数据不一致，人们对该分析的性能和重复性感到担忧。 一些研究报告称，可溶性Klotho与肾功能减退没有关系或水平较高， 而其他人则显示出klotho和肾功能的平行下降。这种差异阻碍了 在大规模人体研究中广泛测量klotho，并导致缺乏高质量的数据 研究klotho在人类慢性肾脏病中的作用。同样，没有关于klotho变化的纵向数据 CKD中的时间。在一个试点项目中，我们使用了来自收缩压干预试验(Sprint)的样本 将最广泛使用的商业ELISA与免疫沉淀-免疫印迹(IP-IB)分析进行比较，以及 发现IP-IB法表现出更好的性能。随后，我们希望解决目前的不足 一系列高质量的人体研究检查可溶克洛酮是心血管疾病和慢性肾脏病进展的危险因素。冲刺 是回答这些问题的理想队列，因为试验招募了2646名患有CKD的参与者，并详细说明了 心血管疾病和肾脏预后。这一队列也非常适合于检查特定于患者和特定于疾病的 可能影响可溶性Klotho纵向变化的临床因素包括：强化与标准 血压控制干预，包括成纤维细胞生长因子-23在内的矿物质代谢指标和干预措施 肾小管损伤/健康。我们建议在2646名患者中测量基线的血清和尿中Klotho浓度。 Sprint参与者在基线时有CKD，以及在第一年和第一年在预先指定的1000人子组中 第4年至：1)将IP-IB法与商业Klotho ELISA进行比较；2)确定Klotho的相关性 CVD事件、死亡和CKD进展；以及3)确定影响纵向的临床因素 Klotho的变化包括强化血压控制与标准血压控制、矿物质代谢标志物和/或肾脏 肾小管健康。这些数据可以共同为未来的Klotho介入试验奠定基础，告知临床风险- 分层模型，并为Klotho生物学和治疗学的翻译研究提供了基础。

ABSTRACT Soluble α-klotho (“Klotho”) has systemic effects in maintenance of cell health including reduction of oxidative stress and fibrosis in the heart and kidney. Kidney tubules are the primary source of circulating (soluble) klotho and therefore the development of chronic kidney disease (CKD) results in klotho deficiency. Klotho deficiency may also paradoxically contribute to CKD progression. Rodent models of klotho deficiency display vulnerability to kidney injury and progression of kidney disease, while administration of exogenous klotho attenuates kidney damage and disease progression. Klotho deficiency may also contribute to excess cardiovascular disease (CVD) risk in CKD as klotho knockout mice display vascular calcification and pathological cardiac remodeling with cardiac hypertrophy and fibrosis. Further, blood pressure (BP) may influence klotho levels as preclinical data show that multiple models of hypertension all result in klotho deficiency. Thus far, the majority of clinical studies examining soluble klotho have relied primarily on a single commercial source of ELISA. There are concerns about the performance and reproducibility of this assay as the clinical data have been inconsistent. Some studies have reported no relationship or higher levels of soluble klotho with reduced kidney function, while others have shown a parallel decline in klotho and kidney function. This discrepancy has hindered widespread measurement of klotho in large-scale human studies and has led to a paucity of quality data examining the role of klotho in human CKD. Similarly, there are no longitudinal data on changes in klotho over time in CKD. In a pilot project using samples from the Systolic Blood Pressure Intervention Trial (SPRINT) we compared the most widely used commercial ELISA with an immunoprecipitation-immunoblot (IP-IB) assay, and found that the IP-IB assay exhibited superior performance. Subsequently, we hope to address the current lack of high quality human studies examining soluble klotho as a risk factor for CVD and CKD progression. SPRINT is the ideal cohort to answer these questions as the trial enrolled 2646 participants with CKD and has detailed CVD and kidney outcomes. This cohort is also well-suited to examine the patient-specific and disease-specific clinical factors that may impact longitudinal changes in soluble klotho including: the intensive vs. standard blood pressure control intervention, measures of mineral metabolism including FGF-23, and measures of kidney tubular injury/health. We propose to measure baseline serum and urine klotho concentrations in 2646 SPRINT participants with CKD at baseline as well as in a pre-specified subset of 1000 persons at year 1 and year 4 to: 1) compare the IP-IB assay with the commercial klotho ELISA; 2) determine the association of klotho with CVD events, death, and CKD progression; and 3) identify the clinical factors that influence longitudinal changes in klotho including intensive vs. standard BP control, markers of mineral metabolism and/or kidney tubular health. Such data can collectively set the stage for future klotho interventional trials, inform clinical risk- stratification models and provide a foundation for translational research in klotho biology and therapeutics.