Kaser S, Tatarczyk T, Stadlmayr A, Ciardi C, Ress C, Tschoner A, Sandhofer A, Paulweber B, Ebenbichler C F, Patsch J R
Medical University Innsbruck, Department of Medicine, Clinical Division of General Internal Medicine, Austria.
Eur J Clin Invest. 2008 Nov;38(11):827-34. doi: 10.1111/j.1365-2362.2008.02028.x.
Adiponectin is an insulin-sensitizing, antiatherogenic and anti-inflammatory adipocytokine that circulates in three isoforms: a trimer [low-molecular weight (LMW)], a hexamer (trimer-dimer) of medium molecular weight (MMW) and a multimeric high molecular weight (HMW) isoform. Evidence is accumulating that HMW adiponectin is the active isoform of the adipocytokine. We investigated the impact of adipose tissue and insulin sensitivity on adiponectin isoform distribution.
One hundred and eighty-seven normolipidaemic, non-diabetic lean or obese subjects with or without insulin resistance participating in the Salzburg Atherosclerosis Prevention program in subjects at High Individual Risk (SAPHIR) were included in the study. Insulin sensitivity was determined by the short insulin tolerance test and the homeostasis model assessment (HOMA) index. Serum adiponectin isoform distribution was determined by an enzyme immunoassay.
Total adiponectin as well as HMW/total adiponectin ratio was significantly increased in female subjects. Circulating total adiponectin levels were lowest in obese patients due to reduced concentrations of HMW adiponectin. As determined by stepwise regression analysis, besides age and high density lipoprotein (HDL) cholesterol, visceral fat area and waist-to-hip ratio predicted concentrations of HMW adiponectin, while insulin sensitivity had no influence on either total adiponectin or its isoforms.
Our results underline that determination of adiponectin isoforms are more useful than measurement of total adiponectin in clinical settings. Our data suggest that adiponectin concentrations are strongly associated with visceral fat area but not with insulin sensitivity. Thus, we hypothesize that insulin resistance is a consequence rather than the cause of hypoadiponectinaemia in obese subjects.
脂联素是一种具有胰岛素增敏、抗动脉粥样硬化和抗炎作用的脂肪细胞因子，以三种异构体形式循环：三聚体[低分子量（LMW）]、中等分子量（MMW）的六聚体（三聚体 - 二聚体）和多聚体高分子量（HMW）异构体。越来越多的证据表明，HMW脂联素是该脂肪细胞因子的活性异构体。我们研究了脂肪组织和胰岛素敏感性对脂联素异构体分布的影响。
187名参与萨尔茨堡高危个体动脉粥样硬化预防项目（SAPHIR）的血脂正常、非糖尿病的瘦或肥胖受试者，有或无胰岛素抵抗，被纳入研究。通过短胰岛素耐量试验和稳态模型评估（HOMA）指数测定胰岛素敏感性。采用酶免疫测定法测定血清脂联素异构体分布。
女性受试者的总脂联素以及HMW/总脂联素比值显著升高。由于HMW脂联素浓度降低，肥胖患者的循环总脂联素水平最低。通过逐步回归分析确定，除年龄和高密度脂蛋白（HDL）胆固醇外，内脏脂肪面积和腰臀比可预测HMW脂联素的浓度，而胰岛素敏感性对总脂联素及其异构体均无影响。
我们的结果强调，在临床环境中，测定脂联素异构体比测量总脂联素更有用。我们的数据表明，脂联素浓度与内脏脂肪面积密切相关，但与胰岛素敏感性无关。因此，我们推测胰岛素抵抗是肥胖受试者低脂联素血症的结果而非原因。
