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International audienceAdvanced glycation end products (AGEs) are considered as biomarkers of ageing and are associated with several degenerative diseases. Besides endogenous formation, significant amounts of AGEs are taken up with food. Although nutritional AGEs are considered as undesirable, proinflammatory agents, they may also enclose potentially beneficial antioxidants. We used rodent cardiac cells to evaluate if food AGEs, present in bread crust, can modify the cellular antioxidant defence. Mice were fed with bread crust containing diet to prove the in-vivo relevance for the heart. In mouse cardiac fibroblasts, bread crust extract induced a moderate elevation of ROS production causing an activation of p42/p44, p38 and NF-κB, followed by increased expression of antioxidative enzymes. Preconditioning studies demonstrated that this was sufficient to protect cardiac fibroblasts and rat adult cardiac myocytes against severe oxidative stress. Furthermore, mice, fed a bread crust containing diet, exhibited a similarly improved cardiac expression of antioxidative defence genes. The consumption of AGEs can therefore contribute to an improved antioxidant status of the heart, thus exhibiting cardioprotective effects in case of severe oxidative stress as in ischemia reperfusion injury. Also, these data show that the exclusive interpretation of circulating AGEs as pathophysiological biomarkers of ageing might be misleading

These data suggest that RAGE is involved in the development of obesity and insulin resistance.

Advanced glycation end products (AGEs) are stable compounds formed from initial Maillard reaction products. They are considered as markers for ageing and often associated with age-related, degenerative diseases. Bread crust represents an established model for nutritional compounds rich in AGEs and is able to induce antioxidative defense genes such as superoxide dismutases and vanins in cardiac cells. The aim of this study was to investigate to what extend the receptor for AGEs (RAGE) contributes to this response. Signal transduction in response to bread crust extract was analysed in cardiac fibroblasts derived from C57/B6-NCrl (RAGE +/+) and the corresponding RAGE-knock out C57/B6-NCrl mouse strain (RAGE -/-). Activation of superoxide dismutases in animals was then analysed upon bread crust feeding in these two mice strains. Cardiac fibroblasts from RAGE -/- mice did not express RAGE, but the expression of AGER-1 and AGER-3 was up-regulated, whereas the expression of SR-B1 was down-regulated. RAGE -/- cells were less sensitive to BCE in terms of MAP-kinase phosphorylation and NF-κB reporter gene activation. Bread crust extract induced mRNA levels of MnSOD and Vnn-1 were also reduced in RAGE -/- cells, whereas Vnn-3 mRNA accumulation seemed to be RAGE receptor independent. In bread crust feeding experiments, RAGE -/- mice did not exhibit an activation of MnSOD-mRNA and -protein accumulation as observed for the RAGE +/+ animals. In conclusion, RAGE was clearly a major factor for the induction of antioxidant defense signals derived from bread crust in cardiac fibroblast and mice. Nevertheless higher doses of bread crust extract could overcome the RAGE dependency in cell cultures, indicating that additional mechanisms are involved in BCE-mediated activation of SOD and vanin expression.

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