The main active metabolite of vitamin D, the 1,25-dihydroxyvitamin D (1,25(OH)₂D), and the shed form of the α-Klotho gene (S-Klotho) play an important role in aging-related physiological processes and are currently considered powerful antiaging renal biomarkers. We aimed to investigate the relationship between 1,25(OH)₂D and S-Klotho plasma levels in middle-aged sedentary healthy adults. We also aimed to study the mediation role of body composition, physical activity levels, dietary parameters, and blood markers in the association between 1,25(OH)₂D and S-Klotho plasma levels. A total of 73 middle-aged sedentary adults (53.4% women; 53.7 ± 5.1 years old) were enrolled in this cross-sectional study. The 1,25(OH)₂D plasma levels were measured using a DiaSorin Liaison^® immunochemiluminometric analyzer. S-Klotho plasma levels were measured using a solid-phase sandwich enzyme-linked immunosorbent assay. Body composition analysis was performed using dual-energy X-ray absorptiometry scanner. A tendency toward a negative association was observed between 1,25(OH)₂D and S-Klotho plasma levels (β = −0.222, R² = 0.049, p = 0.059). The association was attenuated after controlling for age and sex and become significant after controlling for fat mass index. In addition, the association between 1,25(OH)₂D and S-Klotho levels was indirectly influenced by bone mineral density (BMD), with a percentage of mediation of 31.40%. Our study shows that 1,25(OH)₂D is negatively associated with S-Klotho plasma levels in middle-aged sedentary adults, which is partially mediated by BMD.

中文翻译：

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1,25-二羟基维生素 D 和 S-Klotho 血浆水平：中年久坐成人骨矿物质密度介导的两种肾脏抗衰老生物标志物之间的关系

维生素 D 的主要活性代谢物 1,25-二羟基维生素 D (1,25(OH) ₂ D) 和脱落形式的 α-Klotho 基因 (S-Klotho) 在衰老相关生理过程中发挥重要作用过程，目前被认为是强大的抗衰老肾脏生物标志物。我们旨在研究中年久坐的健康成年人的1,25(OH) ₂ D 和 S-Klotho 血浆水平之间的关系。我们还旨在研究身体成分、身体活动水平、饮食参数和血液标志物在 1,25(OH) ₂ D 和 S-Klotho 血浆水平之间的关联中的中介作用。共有 73 名中年久坐成人（53.4% 女性；53.7 ± 5.1 岁）参加了这项横断面研究。1,25(OH) ₂D 血浆水平使用 DiaSorin Liaison ^®免疫化学发光分析仪测量。使用固相夹心酶联免疫吸附测定法测量 S-Klotho 血浆水平。使用双能 X 射线吸收仪扫描仪进行身体成分分析。在 1,25(OH) ₂ D 和 S-Klotho 血浆水平之间观察到负相关的趋势（β  = -0.222，R ²  = 0.049，p  = 0.059）。在控制年龄和性别后，这种关联减弱，在控制脂肪质量指数后变得显着。此外，1,25(OH) ₂D 和 S-Klotho 水平受骨矿物质密度 (BMD) 的间接影响，介导百分比为 31.40%。我们的研究表明，1,25(OH) ₂ D 与中年久坐成人的 S-Klotho 血浆水平呈负相关，这部分由 BMD 介导。