Supplementary Material for: Prediction of Circulating Adipokine Levels Based on Body Fat Compartments and Adipose Tissue Gene Expression

Background: Adipokines are hormones secreted from adipose tissue (AT), and a number of them have been established as risk factors for chronic diseases. However, it is not clear whether and to what extent adiposity, gene expression, and other factors determine their circulating levels. Objectives: To assess to what extent adiposity, as measured by the amount of subcutaneous AT (SAT) and visceral AT (VAT) using magnetic resonance imaging, and gene expression levels in SAT determine plasma concentrations of the adipokines adiponectin, leptin, soluble leptin receptor, resistin, interleukin 6, and fatty acid-binding protein 4 (FABP4). Methods: We performed a cross-sectional analysis of 156 participants from the EPIC Potsdam cohort study and analyzed multiple regression models and partial correlation coefficients. Results: For leptin and FABP4 concentrations, 81 and 45% variance were explained by SAT mass, VAT mass, and gene expression in SAT in multivariable regression models. For the remaining adipokines, AT mass and gene expression explained r = 0.81, 95% confidence interval 0.75–0.86, vs. r = 0.58, 95% confidence interval 0.46–0.67), while differences between AT compartments were small for the other adipokines. Conclusions: While plasma levels of leptin and FABP4 can be explained in a large and medium part by the amount of AT and SAT gene expression, surprisingly, these predictors explained only little variance for all other investigated adipokines.研究背景：脂肪因子（adipokine）是由脂肪组织（adipose tissue, AT）分泌的激素，其中多种已被证实为慢性疾病的危险因素。然而目前尚不明确，肥胖、基因表达及其他因素是否会影响脂肪因子的循环水平，以及其具体影响程度。 研究目标：通过磁共振成像（magnetic resonance imaging）测量皮下脂肪组织（subcutaneous AT, SAT）与内脏脂肪组织（visceral AT, VAT）的含量以评估肥胖程度，并结合皮下脂肪组织的基因表达水平，探究上述因素对脂联素（adiponectin）、瘦素（leptin）、可溶性瘦素受体（soluble leptin receptor）、抵抗素（resistin）、白细胞介素6（interleukin 6）以及脂肪酸结合蛋白4（FABP4）血浆浓度的影响程度。 研究方法：对来自欧洲癌症与营养前瞻性研究波茨坦队列（EPIC Potsdam）的156名参与者开展横断面分析，并对多元回归模型与偏相关系数进行分析。 研究结果：在多元回归模型中，皮下脂肪组织重量、内脏脂肪组织重量以及皮下脂肪组织的基因表达水平可分别解释瘦素与脂肪酸结合蛋白4血浆浓度81%和45%的变异度。针对其余脂肪因子，脂肪组织质量与基因表达的相关系数为r=0.81（95%置信区间：0.75~0.86），与之相比为r=0.58（95%置信区间：0.46~0.67）；而对于其余脂肪因子而言，不同脂肪组织分区之间的差异较小。 研究结论：瘦素与脂肪酸结合蛋白4的血浆水平可在较大程度与中等程度上通过脂肪组织总量及皮下脂肪组织的基因表达水平进行解释，但令人意外的是，上述预测因素仅能解释其余所有被研究脂肪因子的极小部分变异度。