Acute bed rest places older adults at risk for health complications by disrupting homeostasis in many organ systems, including the cardiovascular system. Circulating ceramides are emerging biomarkers predictive of cardiovascular and metabolic health and have recently been shown to be sensitive indices of cardiovascular (CV) risk. Therefore, the purpose of this study was to characterize the time course of changes in circulating ceramides in healthy younger and older adults after 5 days of bed rest and to determine whether short-term bed rest alters CV-related circulating ceramides. We hypothesized that circulating ceramides predictive of poor cardiometabolic outcomes would increase following 5 days of bed rest. Thirty-five healthy younger and older men and women (young: n = 13, old: n = 22) underwent 5 days of controlled bed rest. Fasting blood samples collected daily during the course of bed rest were used to measure circulating ceramides, lipoproteins, adiponectin, and fibroblast growth factor 21 (FGF21) levels. The primary findings were that circulating ceramides decreased while ceramide ratios and the cardiac event risk test 1 score were increased primarily in older adults, and these findings were independent of changes in circulating lipoprotein levels. Additionally, we found that changes in circulating adiponectin, FGF21 and the 6-minute walk test (6MW) inversely correlated with CV-related circulating ceramides after bed rest. The results of this study highlight the sensitivity of circulating ceramides to detect potential CV dysfunction that may occur with acute physical disuse in aging.

中文翻译：

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神经酰胺生物标志物对卧床休息后健康老年人心血管疾病风险增加的预测。

急性卧床会破坏包括心血管系统在内的许多器官系统的稳态，从而使老年人面临健康并发症的风险。循环神经酰胺是预测心血管和代谢健康的新兴生物标志物，最近已被证明是心血管 (CV) 风险的敏感指标。因此，本研究的目的是表征健康的年轻人和老年人在卧床 5 天后循环神经酰胺变化的时间过程，并确定短期卧床是否会改变 CV 相关的循环神经酰胺。我们假设，在卧床休息 5 天后，预测心脏代谢不良结果的循环神经酰胺会增加。三十五名健康的年轻和年长男性和女性（年轻：n = 13，老年：n= 22) 进行了 5 天的受控卧床休息。每天在卧床休息期间收集的空腹血样用于测量循环神经酰胺、脂蛋白、脂联素和成纤维细胞生长因子 21 (FGF21) 水平。主要发现是循环神经酰胺减少，而神经酰胺比率和心脏事件风险测试 1 评分主要在老年人中增加，并且这些发现与循环脂蛋白水平的变化无关。此外，我们发现循环脂联素、FGF21 和 6 分钟步行试验 (6MW) 的变化与卧床休息后与 CV 相关的循环神经酰胺呈负相关。这项研究的结果强调了循环神经酰胺对检测潜在的 CV 功能障碍的敏感性，这些功能障碍可能随着衰老的急性身体废用而发生。