Clin Chem Lab Med. 2014 Jan 1;52(1):151-60. doi: 10.1515/cclm-2012-0826.
Advanced glycation end products (AGEs), the final products of the Maillard reaction, have been shown to impair endothelial proliferation and function, thus contributing to endothelial cell injury present in diabetes, inflammatory and cardiovascular diseases. Endoplasmic reticulum (ER) stress triggered under hyperglycemic, hypoxic and oxidative conditions has been implicated in endothelial dysfunction through activation of the unfolded protein response (UPR). The present study investigates the role of AGEs in ER stress induction in human aortic endothelial cells exposed to variable AGE treatments.
Human aortic endothelial cells (HAEC) were treated with increasing concentrations (100, 200 μg/mL) of AGE-bovine serum albumin (AGE-BSA) at different time-points (24, 48, 72 h). The induction of ER stress and the involved UPR components were investigated on mRNA and protein levels. Apoptosis was quantitatively determined by flow cytometry detecting propidium iodide expression and annexin V binding simultaneously.
AGEs administration significantly reduced HAEC proliferation in a time- and dose-dependent manner. An immediate induction of the ER chaperones GRP78, GRP94 and the transcriptional activator, XBP-1 was observed at 24 h and 48 h. A later induction of the phospho-elF2α and proapoptotic transcription factor CHOP was observed at 48 h and 72 h, being correlated with elevated early apoptotic cell numbers at the same time-points.
The present study demonstrates that AGEs directly induce ER stress in human aortic endothelial cells, playing an important role in endothelial cell apoptosis. Targeting AGEs signaling pathways in order to alleviate ER stress may prove of therapeutic potential to endothelial dysfunction-related disorders.
晚期糖基化终产物（AGEs）是美拉德反应的最终产物，已被证明会损害内皮细胞的增殖和功能，从而导致糖尿病、炎症和心血管疾病中存在的内皮细胞损伤。在高血糖、缺氧和氧化条件下触发的内质网（ER）应激已被牵连通过未折叠蛋白反应（UPR）的激活导致内皮功能障碍。本研究探讨了在暴露于不同 AGE 处理的人主动脉内皮细胞（HAEC）中，AGEs 在 ER 应激诱导中的作用。
用递增浓度（100、200μg/ml）的 AGE-牛血清白蛋白（AGE-BSA）在不同时间点（24、48、72h）处理人主动脉内皮细胞（HAEC）。在 mRNA 和蛋白水平上研究 ER 应激的诱导和涉及的 UPR 成分。通过流式细胞术同时检测碘化丙啶表达和膜联蛋白 V 结合来定量测定细胞凋亡。
AGEs 处理以时间和剂量依赖的方式显著降低 HAEC 的增殖。在 24h 和 48h 时观察到 ER 伴侣 GRP78、GRP94 和转录激活剂 XBP-1 的即刻诱导。在 48h 和 72h 时观察到磷酸化 elF2α和促凋亡转录因子 CHOP 的后期诱导，与同一时间点早期凋亡细胞数量的增加相关。
本研究表明 AGEs 直接诱导人主动脉内皮细胞 ER 应激，在内皮细胞凋亡中起重要作用。针对 AGEs 信号通路以减轻 ER 应激可能对与内皮功能障碍相关的疾病具有治疗潜力。
