Polyphenolic Extracts from Olea europea L. Protect Against Cytokine-Induced β-Cell Damage Through Maintenance of Redox Homeostasis
Polyphenolic Extracts from Olea europea L. Protect Against Cytokine-Induced β-Cell Damage Through Maintenance of Redox Homeostasis
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DOI：
10.1089/rej.2010.1111
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发表时间：
2011-06-01
影响因子：
2.6
通讯作者：
Karasu, Cimen
中科院分区：
文献类型：
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作者：
Cumaoglu, Ahmet;Ari, Nuray;Karasu, Cimen
已知包括细胞因子在内的各种胰腺β细胞应激源可诱导氧化应激，导致细胞凋亡/坏死性死亡和胰岛素分泌抑制。传统上，橄榄叶或橄榄果用于治疗糖尿病，但其作用的细胞机制(S)尚不清楚。我们研究了橄榄叶和果提取物及其成分橄榄苷对细胞因子诱导的β细胞毒性的影响。INS-1是一种胰岛素分泌的β细胞系，在增加或不增加橄榄叶或水果提取物或橄榄仁预孵育24小时后，再暴露于含有0.15 ng/mLIL-1β、1 ng/mL干扰素-γ和1 ng/mL肿瘤坏死因子-α的细胞因子鸡尾酒中6h。3-(4，5-二甲基噻唑-2-基)-2，5-二苯基四氮唑溴化法测定细胞毒性。荧光显微镜下检测吖啶橙/溴化乙锭染色凝集细胞核，定量检测细胞凋亡率。暴露于细胞因子的细胞凋亡率较高，细胞存活率降低，caspase3/7活性升高。细胞因子作用后，提取物和橄榄仁苷均能部分提高活细胞比例，提高细胞存活率。提取物对活细胞活性的保护作用是通过抑制caspase3/7活性实现的。胡萝卜素不能同时减少凋亡和坏死细胞的数量，而提取物显著保护细胞免受细胞因子诱导的死亡。细胞因子导致INS-1细胞内ROS生成增加，并抑制谷胱甘肽水平、超氧化物歧化酶活性和胰岛素分泌。叶片提取物几乎完全保护胰岛素的分泌，但果实提取物或橄榄仁苷对胰岛素分泌有部分影响。细胞因子和橄榄衍生物对细胞色素c的释放和过氧化氢酶活性均无显著影响。此外，在细胞因子诱导的ROS产生和改善异常的抗氧化防御方面，每种提取物或橄榄苷孵育的细胞显示出显著的减少。橄榄多酚抑制细胞因子介导的β细胞毒性的分子机制似乎与维持氧化还原稳态有关。
Various pancreatic beta-cell stressors, including cytokines, are known to induce oxidative stress, resulting in apoptotic/necrotic cell death and inhibition of insulin secretion. Traditionally, olive leaves or fruits are used for treating diabetes, but the cellular mechanism(s) of their effects are not known. We examined the effects of Olea europea L. (olive) leaf and fruit extracts and their component oleuropein on cytokine-induced beta-cell toxicity. INS-1, an insulin-producing beta-cell line, was preincubated with or without increasing concentrations of olive leaf or fruit extract or oleuropein for 24 hr followed by exposure to a cytokine cocktail containing 0.15 ng/mL interleukin-1 beta (IL-1 beta), 1 ng/mL interferon-gamma (IFN-gamma), and 1 ng/mL tumor necrosis factor-alpha (TNF-alpha) for 6 hr. The cytotoxicity was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) testing. Apoptosis was quantified by detecting acridine orange/ethidium bromide-stained condensed nuclei under a fluorescent microscope. The cells exposed to cytokines had a higher apoptotic rate, a decreased viability (MTT), and an increased caspase 3/7 activity. Both extracts and oleuropein partially increased the proportion of living cells and improved the viability of cells after cytokines. The protective effects of extracts on live cell viability were mediated through the suppression of caspase 3/7 activity. Oleuropein did not decrease the amount of both apoptotic and necrotic cells, whereas extracts significantly protected cells against cytokine-induced death. Cytokines led to an increase in reactive oxygen species (ROS) generation and inhibited glutathione level, superoxide dismutase activity, and insulin secretion in INS-1. Insulin secretion was almost completely protected by leaf extract, but was partially affected by fruit extract or oleuropein. Neither cytokines nor olive derivatives had a significant effect on cellular cytochrome c release and catalase activity. Moreover, the cells incubated with each extract or oleuropein showed a significant reduction in cytokine-induced ROS production and ameliorated abnormal antioxidant defense. The molecular mechanism by which olive polyphenols inhibit cytokine-mediated beta-cell toxicity appears to be involving the maintenance of redox homeostasis.