Department of Nutritional and Physiological Chemistry, Faculty of Chemistry, University of Vienna, Vienna, Austria.
Christian Doppler Laboratory for Bioactive Aroma Compounds, Faculty of Chemistry, University of Vienna, Vienna, Austria.
J Cell Biochem. 2018 Mar;119(3):2731-2741. doi: 10.1002/jcb.26439. Epub 2017 Dec 4.
Advanced glycation end products (AGEs), comprising a highly diverse class of Maillard reaction compounds formed in vivo and during heating processes of foods, have been described in the progression of several degenerative conditions such as Alzheimer's disease and diabetes mellitus. N -Carboxymethyllysine (CML) represents a well-characterized AGE, which is frequently encountered in a Western diet and is known to mediate its cellular effects through binding to the receptor for AGEs (RAGE). As very little is known about the impact of exogenous CML and its precursor, glyoxal, on intestinal cells, a genome-wide screening using a customized microarray was conducted in fully differentiated Caco-2 cells. After verification of gene regulation by qPCR, functional assays on fatty acid uptake, glucose uptake, and serotonin release were performed. While only treatment with glyoxal showed a slight impact on fatty acid uptake (P < 0.05), both compounds reduced glucose uptake significantly, leading to values of 81.3% ± 22.8% (500 μM CML, control set to 100%) and 68.3% ± 20.9% (0.3 μM glyoxal). Treatment with 500 μM CML or 0.3 μM glyoxal increased serotonin release (P < 0.05) to 236% ± 111% and 264% ± 66%, respectively. Co-incubation with the RAGE antagonist FPS-ZM1 reduced CML-induced serotonin release by 34%, suggesting a RAGE-mediated mechanism. Similarly, co-incubation with the SGLT-1 inhibitor phloridzin attenuated serotonin release after CML treatment by 32%, hinting at a connection between CML-stimulated serotonin release and glucose uptake. Future studies need to elucidate whether the CML/glyoxal-induced serotonin release in enterocytes might stimulate serotonin-mediated intestinal motility.
糖基化终产物 (AGEs) 是一类由美拉德反应化合物组成的高度多样化的物质，在体内和食物的加热过程中形成，它们与几种退行性疾病的发展有关，如阿尔茨海默病和糖尿病。N-羧甲基赖氨酸 (CML) 是一种特征明确的 AGE，在西方饮食中经常遇到，已知通过与 AGE 受体 (RAGE) 结合来介导其细胞效应。由于对外源 CML 及其前体乙醛酸的影响知之甚少，因此在完全分化的 Caco-2 细胞中使用定制的微阵列进行了全基因组筛选。在用 qPCR 验证基因调控后，进行了脂肪酸摄取、葡萄糖摄取和 5-羟色胺释放的功能测定。虽然只有乙醛酸处理对脂肪酸摄取有轻微影响 (P < 0.05)，但这两种化合物都显著降低了葡萄糖摄取，导致 500μM CML (对照设定为 100%) 和 68.3%±20.9% (0.3μM 乙醛酸) 的摄取值。用 500μM CML 或 0.3μM 乙醛酸处理可增加 5-羟色胺释放 (P < 0.05)，分别达到 236%±111%和 264%±66%。用 RAGE 拮抗剂 FPS-ZM1 共孵育可使 CML 诱导的 5-羟色胺释放减少 34%，表明存在 RAGE 介导的机制。同样，在用 CML 处理后用 SGLT-1 抑制剂根皮苷共孵育可使 5-羟色胺释放减少 32%，提示 CML 刺激的 5-羟色胺释放与葡萄糖摄取之间存在联系。未来的研究需要阐明肠细胞中 CML/乙醛酸诱导的 5-羟色胺释放是否可能刺激 5-羟色胺介导的肠道蠕动。
