Raila J, Henze A, Spranger J, Möhlig M, Pfeiffer A F H, Schweigert F J
Institute of Nutritional Science, University of Potsdam, Potsdam, Germany.
Kidney Int. 2007 Aug;72(4):505-11. doi: 10.1038/sj.ki.5002372. Epub 2007 Jun 13.
Plasma retinol-binding protein 4 (RBP4) may be a new adipokine linked to obesity-induced insulin resistance and type 2 diabetes. The impact of diabetic nephropathy on plasma RBP4 levels, however, is not known. We tested the hypothesis that microalbuminuria is associated with elevated plasma concentrations of RBP4 in type 2 diabetic subjects. Retinol, its binding protein and transthyretin (TTR) were measured in the plasma and urine of 62 type 2 diabetic subjects, 26 of whom had microalbuminuria. The results were compared to 35 healthy control subjects. Despite no differences in plasma retinol, concentrations of the RBP4 were significantly elevated in plasma of diabetic patients and significantly higher in those with microalbuminuria. The higher plasma levels of the binding protein in subjects with microalbuminuria were accompanied by both significantly elevated plasma TTR and increased urinary levels of RBP4. There were no correlations of plasma-binding protein levels and parameters of insulin resistance. Our study suggests that plasma RBP4 levels in type 2 diabetic patients are affected by incipient nephropathy. Therefore, further studies evaluating RBP4 as a regulator of systemic insulin resistance and type 2 diabetes will need to take renal function into consideration.
血浆视黄醇结合蛋白4（RBP4）可能是一种与肥胖诱导的胰岛素抵抗和2型糖尿病相关的新型脂肪因子。然而，糖尿病肾病对血浆RBP4水平的影响尚不清楚。我们检验了2型糖尿病患者微量白蛋白尿与血浆RBP4浓度升高相关的假设。在62名2型糖尿病患者（其中26名有微量白蛋白尿）的血浆和尿液中检测了视黄醇、其结合蛋白和甲状腺素转运蛋白（TTR）。将结果与35名健康对照者进行比较。尽管血浆视黄醇无差异，但糖尿病患者血浆中RBP4浓度显著升高，微量白蛋白尿患者中更高。微量白蛋白尿患者血浆中结合蛋白水平较高，同时伴有血浆TTR显著升高和尿中RBP4水平升高。血浆结合蛋白水平与胰岛素抵抗参数无相关性。我们的研究表明，2型糖尿病患者的血浆RBP4水平受早期肾病影响。因此，进一步评估RBP4作为全身胰岛素抵抗和2型糖尿病调节因子的研究需要考虑肾功能。
