Schiekofer S, Franke S, Andrassy M, Chen J, Rudofsky G, Schneider J G, von Eynatten M, Wendt T, Morcos M, Kientsch-Engel R, Stein G, Schleicher E, Nawroth P P, Bierhaus A
Department of Medicine I, University of Heidelberg, Heidelberg, Germany.
Exp Clin Endocrinol Diabetes. 2006 Apr;114(4):160-7. doi: 10.1055/s-2006-924081.
Dietary uptake of Advanced Glycation Endproducts (AGE) is supposed to potentially contribute to inflammatory reactions linked to vascular dysfunction and late diabetic complications. One mechanism by which dietary AGE might exert these effects is by activation of the proinflammatory transcription factor NF-kappa-B. The aim of this study was to analyze the postprandial effects of a casein meal with low or high AGE content on postprandial NF-kappaB activation in peripheral blood mononuclear cells (pBMC) of healthy volunteers.
Casein was heated for 40 h at 50 degrees C in the presence of sorbitol or glucose, resulting in either minimal (Sorbitol [S]-casein) or large (glucose [G]-casein) amounts of AGE-modified casein. Nine healthy volunteers ate 250 g of both types of casein, whereas both meals were separated at least by 2 weeks. Plasma and pBMC were taken before and 2 h after each meal. Thereafter, the defined AGE carboxymethyllysine (CML) was determined by ELISA and Western blot. NF-kappaB activation in pBMC was assayed using Electrophoretic Mobility Shift Assays (EMSA) and Western blot analysis.
S-casein contained only minor amounts of CML and no pentosidine, while G-casein contained large amounts of both. 2 h after ingestion, the S-casein or the G-casein-meal, both, resulted in a non-significant increase in plasma CML and in the intracellular CML-content of pBMC. This was paralleled by a highly significant increase in postprandial mononuclear NF-kappaB-binding activity. Remarkably, neither the extent of NF-kappaB induction (178% for S-casein, 188% for G-casein), nor composition of the NF-kappaB heterodimer (mainly consisting of NF-kappaB p50/p65) were significantly different after intake of S-casein or G-casein. Consistently, Western blots confirmed an increased NF-kappaBp65 nuclear translocation and a decrease of NF-kappaBp65 in the cytoplasm, while no difference in postprandial NF-kappaB nuclear translocation was observed following intake of S-casein or G-casein.
Postprandial mononuclear NF-kappaB activation after a single meal is independent of the AGE-content of the ingested protein.
膳食中晚期糖基化终产物（AGE）的摄入可能会引发与血管功能障碍及糖尿病晚期并发症相关的炎症反应。膳食AGE发挥这些作用的一种机制可能是通过激活促炎转录因子核因子κB（NF-κB）。本研究旨在分析摄入低AGE含量或高AGE含量的酪蛋白餐对健康志愿者外周血单个核细胞（pBMC）餐后NF-κB激活的影响。
酪蛋白在山梨醇或葡萄糖存在的条件下于50℃加热40小时，从而得到AGE修饰程度最低的（山梨醇[S]-酪蛋白）或最高的（葡萄糖[G]-酪蛋白）酪蛋白。9名健康志愿者分别食用250克这两种酪蛋白，两餐之间至少间隔2周。每餐前后采集血浆和pBMC。之后，通过酶联免疫吸附测定（ELISA）和蛋白质印迹法测定特定的AGE羧甲基赖氨酸（CML）。使用电泳迁移率变动分析（EMSA）和蛋白质印迹分析检测pBMC中NF-κB的激活情况。
S-酪蛋白仅含有少量CML且不含戊糖苷，而G-酪蛋白两者含量均高。摄入后2小时，S-酪蛋白餐或G-酪蛋白餐均使血浆CML及pBMC细胞内CML含量出现不显著的增加。与此同时，餐后单核细胞NF-κB结合活性显著升高。值得注意的是，摄入S-酪蛋白或G-酪蛋白后，NF-κB诱导程度（S-酪蛋白为178%，G-酪蛋白为188%）以及NF-κB异二聚体的组成（主要由NF-κB p50/p65组成）均无显著差异。同样，蛋白质印迹证实NF-κBp65核转位增加且细胞质中NF-κBp65减少，而摄入S-酪蛋白或G-酪蛋白后餐后NF-κB核转位未观察到差异。
单次餐后单核细胞NF-κB激活与摄入蛋白质的AGE含量无关。
