目的 探究化学源硒（硒代胱氨酸,selenocystine,SeCys2）与植物源硒（壶瓶碎米荠硒,Cardamine hupingshanensis-Se,HUP-Se）缓解镉（cadmium,Cd）所致肠损伤及其可能机制。方法 通过水培HUP分别获得单富集镉（HUP-Cd）以及共富集硒镉（HUP-Cd+Se）的植物。C57BL/6小鼠随机分为对照组（Con组）、Cd组、Cd+Se组、HUP-Cd组及HUP-Cd+Se组。Cd组灌胃含CdCl2水溶液[Cd: 1.2mg/kg body weight（BW）];Cd+Se组灌胃含CdCl2与SeCys2的水溶液（Cd: 1.2mg/kg BW;Se: 0.4mg/kg BW）;HUP-Cd组（Cd剂量同Cd组）与HUP-Cd+Se组（Cd与Se的剂量同Se组）灌胃各自的植物粉末所制悬浊液。干预12w后收集粪便,处死动物收集血清与肠组织,组织病理学观察十二指肠病理改变及杯状细胞数量,免疫组织化学分析其隐窝Ki67与Lgr5阳性细胞数量,蛋白印迹法测定环鸟苷酸-腺苷酸合成酶(cyclic GMP-AMP synthase, cGAS)、干扰素基因刺激因子(stimulator of interferon genes, STING)及其下游蛋白磷酸化水平以及紧密连接蛋白Occludin、Claudin1与ZO-1的表达水平,qPCR法测定炎症因子干扰素β、干扰素γ、肿瘤坏死因子α与白细胞介素6 mRNA表达水平。结果 Cd+Se组及HUP-Cd+Se组小鼠血Cd水平分别低于Cd组与HUP-Cd组,但粪便Cd含量高于相应的Cd组。Cd暴露引起明显的肠损伤,Se与HUP-Se干预缓解了肠道氧化应激,改善了十二指肠病理损伤,恢复了小肠细胞增殖再生能力,并上调了十二指肠紧密连接蛋白的表达水平。Cd暴露激活了免疫炎症相关的cGAS/STING信号通路,Se与HUP-Se干预则显著下调了该通路蛋白质的磷酸化,同时下调其下游炎症因子的基因表达水平。结论 化学源与植物源Se通过下调肠道cGAS/STING信号通路及炎症因子缓解Cd诱导小鼠肠损伤。
Abstract
Objective To investigate the protective effects of chemical-based selenium (selenocystine, SeCys2) and plant-based selenium (Cardamine hupingshanensis-Se, HUP) on cadmium (Cd)-induced intestinal injury and the underlying mechanism. Methods Cd-enriched (HUP-Cd) and Se-Cd-coenriched (HUP-Cd+Se) plants were obtained by hydroponics. C57BL/6 mice were randomly divided into the control (Con), Cd, Cd+Se, HUP-Cd, and HUP-Cd+Se groups. The mice in the Cd group were gavaged by CdCl2 solution [Cd: 1.2 mg/kg body weight (BW), and mice in the Cd+Se group were gavaged by CdCl2 and SeCys2 solution (Cd: 1.2 mg/kg BW; Se: 0.4mg/kg BW). The mice in the HUP-Cd and HUP-Cd+Se groups were gavaged by corresponding suspensions containing the same amount of Cd and/or Se used in the Cd and Se groups. After 12 weeks, feces, serum and duodenum were collected. Histopathological observation was performed to examine the pathological changes and the number of goblet cells in the duodenum. Immunohistochemistry was used to analyze Ki67 and Lgr5 positive cells in the crypts. Western blot was conducted to determine the phosphorylation levels of cyclic GMP-AMP synthase (cGAS), stimulator of interferon genes (STING) and their downstream proteins, as well as the expression levels of tight junction proteins Occludin, Claudin1 and ZO-1. qPCR was employed to detect the mRNA expression levels of inflammatory factors (IFN-β、IFN-γ、TNF-α、IL-6). Results Compared with the Cd and HUP-Cd groups, the mice in the Cd+Se and HUP-Cd+Se groups had lower serum levels of Cd with higher amount of Cd in the feces. Cd exposure induced obvious intestinal injury. Se and HUP-Se intervention alleviated oxidative stress, improved intestinal pathological injury, and upregulated the expression of tight junction proteins in the duodenum. Cd exposure activated the cGAS/STING pathway. Se and HUP-Se intervention downregulated the phosphorylation of proteins in this pathway and the mRNA expression levels of downstream inflammatory factors. Conclusion Chemical- and plant-based Se alleviated Cd-induced intestinal injury in mice by downregulating cGAS/STING pathway and inflammatory factors.
关键词
硒代胱氨酸 /
壶瓶碎米荠 /
肠损伤 /
cGAS/STING
Key words
selenocystine /
Cardamine hupingshanensis /
intestinal injury /
cGAS/STING
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基金
西交利物浦大学博士奖学金项目（No.PGRS2006002）; 西交利物浦大学研究发展基金（No.RDF-19-02-02）
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