Telomere length analysis in the CALERIE trial

项目摘要 长期的热量限制（CR）是最有效的和充分研究的干预措施之一，以延长这两个 从酵母菌到灵长类动物，各种物种的平均和最大寿命。的最新证据 减少能量摄入长期影响的综合评估（CALERIE）建议CR 减缓人类的生物衰老，这是通过应用于血液化学数据的算法来测量的。的 CR影响健康寿命的机制涉及一系列复杂的分子途径，从 减少炎症和氧化应激，改善线粒体功能，增强自噬， 增强抗压力能力。值得注意的是，上述机制涉及端粒长度 调控然而，CR是否能减缓端粒长度所指示的生物衰老，还没有得到解决， 以及炎症和氧化应激在假设机制中的作用。了解 CR增加健康寿命的分子途径可以为抗衰老疗法找到新的靶点。 在这里，我们将在CALERIE中测定白细胞端粒长度（LTL），以测试CR是否与 与自由采食对照组相比，LTL侵蚀减少。LTL试验将使用T/S 比值和绝对qPCR测定，并根据 端粒研究网络.此外，充分利用跨区域获得的LTL重复测量值， 在试验中，我们将研究在两年的时间跨度内，LTL的差异何时出现（例如，或早或晚）。 利用CALERIE生物储存库，我们将进一步测试是否假设减少CR中的LTL侵蚀 ARM是由炎症和氧化应激水平降低介导的。在目标1a中，意向治疗分析将 测试与随意对照相比，CR是否与24个月内LTL侵蚀减少相关。 目标1b将进行剂量反应分析，并调查干预效果是否由以下因素介导： 体重减轻，并检查在24个月试验的早期或晚期，CR对LTL变化的影响何时出现。 目标2将通过降低以下水平来检验CR是否与24个月内的LTL变化相关： 12和24个月时的炎症（CRP、ICAM 1、IL 1 β、IL 6、IL 8、瘦素、MCP 1和TNF-α的因子分析）， 12和24个月时氧化应激水平降低（F2-异前列腺素-iPF（2α）-III的因子分析， 2，3-dinor-iPF（2 α）-III、iPF（2 α）-VI和8，12-iso-iPF（2α）-VI）。这项创新工作将决定从有史以来第一次 随机试验设计，如果人类热量限制减缓细胞衰老，通过端粒长度测量。 这些发现将有助于在细胞水平上产生有关人类CR机制的新知识。数据 分析完成后，生成的数据将与CALERIE生物储存库共享，供研究者使用。

PROJECT SUMMARY Long-term caloric restriction (CR) is one of the most effective and well-studied intervention to extend both average and maximum life spans in a variety of species, from yeast to primates. Recent evidence from the Comprehensive Assessment of Long term Effects of Reducing Intake of Energy (CALERIE) suggests CR slows biological aging in humans, as measured by an algorithm applied to blood chemistry data. The mechanisms through which CR affects healthy lifespan involve a complex array of molecular pathways, from reduced inflammation and oxidative stress, improved mitochondrial function, enhanced autophagy and increased stress resistance. Notably, the aforementioned mechanisms are implicated in telomere length regulation. Yet, whether CR slows biological aging as indicated by telomere length, has not been addressed, as well as the role of inflammation and oxidative stress in the hypothesized mechanism. Understanding the molecular pathways by which CR increases healthspan could pinpoint new targets for anti-aging therapies. Here we will assay leukocyte telomere length (LTL) in CALERIE to test whether CR is associated with decreased LTL erosion as compared to the ad libitum control. LTL assays will be conducted using both the T/S ratio and the absolute qPCR assay, and communicated based on new qPCR reporting guidelines set by the Telomere Research Network. Further, making full use of the repeated measures of LTL obtained across the trial, we will examine when, during the two-year span, the differences in LTL emerge (e.g., earlier or later). Utilizing CALERIE biorepository, we will further test whether the hypothesized reduced LTL erosion in the CR arm is mediated by reduced level of inflammation and oxidative stress. In Aim 1a, intent-to-treat analysis will test whether CR is associated with reduced LTL erosion over 24 months, compared to the ad libitum control. Aim 1b will conduct dose-response analyses and investigate whether intervention effects are mediated by weight loss, and examine when, earlier or later in the 24-month trial, the CR effects on LTL change emerge. Aim 2 will test whether CR is associated with LTL changes over 24 months through reduced levels of inflammation at 12 and 24 months (factor analysis of CRP, ICAM1, IL1β, IL6, IL8, Leptin, MCP1, and TNF-α), and reduced levels of oxidative stress at 12 and 24 month (factor analysis of F2‐isoprostanes—iPF(2α)‐III, 2,3‐dinor‐iPF(2 α)‐III, iPF(2 α)‐VI, and 8,12‐iso‐iPF(2α)‐VI). This innovative work will determine from a first-ever randomized trial design if human caloric restriction slows cellular aging as measured by telomere length. Findings will help generate new knowledge about CR mechanisms in humans at the cellular level. The data generated will be shared with the CALERIE Biorepository upon completion of assays for investigators use.