Postprandial mononuclear NF-κB activation is independent of the AGE-content of a single meal

Objective: 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-κB activation in peripheral blood mononuclear cells (pBMC) of healthy volunteers. Research Design and Methods: Casein was heated for 40 h at 50 °C in the presence of sorbitol or glucose, resulting in either minimal (Sorbitol [Si-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-κB activation in pBMC was assayed using Electrophoretic Mobility Shift Assays (EMSA) and Western blot analysis. Results: 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-κB-binding activity. Remarkably, neither the extent of NF-κB induction (178% for S-casein, 188% for G-casein), nor the composition of the NF-κB heterodimer (mainly consisting of NF-κB p50/p65) were significantly different after intake of S-casein or G-casein. Consistently, Western blots confirmed an increased NF-κBp65 nuclear translocation and a decrease of NF-κBp65 in the cytoplasm, while no difference in postprandial NF-κB nuclear translocation was observed following intake of S-casein or G-casein. Conclusion: Postprandial mononuclear NF-κB activation after a single meal is independent of the AGE-content of the ingested protein.