最近的研究表明,铁过载患者胰岛素抵抗或糖尿病的风险增加。铁凋亡是一种主要由铁依赖性氧化损伤引起的新型细胞死亡。在本研究中,我们通过体内和体外实验研究了铁过载诱导肝脏铁死亡和胰岛素抵抗的潜在机制。在体内,采用右旋糖酐铁腹腔注射建立小鼠铁超负荷模型。体重的变化,测定血清铁蛋白和血糖。用苏木精-伊红(HE)和Perl染色观察小鼠肝脏的病理变化和铁沉积。体外,用柠檬酸铁铵(FAC,9mmol/L,24h)树立铁过载的细胞模子。不稳定的铁池,细胞活力,测定葡萄糖消耗和糖原含量。用透射电镜(TEM)观察线粒体超微结构。采用丙二醛(MDA)和谷胱甘肽(GSH)试剂盒检测小鼠肝组织和HepG2细胞的脂质过氧化。RT-PCR和Westernblot检测铁凋亡因子和JAK2/STAT3信号通路的mRNA和蛋白表达水平。在这项研究中,我们在小鼠和HepG2细胞中使用了铁螯合剂地拉罗司。铁过载导致体重减轻,血清铁蛋白升高,空腹血糖,空腹胰岛素,HOMA-IR,糖耐量受损,和降低小鼠的胰岛素敏感性。HE染色和Perls染色显示铁过载小鼠肝脏中的铁沉积团块。铁过载可以减少葡萄糖的消耗,增加HepG2细胞的MDA含量,同时降低小鼠肝组织和HepG2细胞中糖原和GSH含量。透射电镜显示铁过载HepG2细胞线粒体脊缺失和外膜破裂。铁螯合剂可以显著改善上述指标,这可能与JAK2/STAT3/SLC7A11信号通路的激活和肝脏铁凋亡有关。铁过载可通过抑制JAK2/STAT3/SLC7A11信号通路诱导肝脏铁凋亡和胰岛素抵抗,铁螯合剂地拉罗司可能改善铁过载引起的肝胰岛素抵抗。
Recent studies showed that patients with iron overload had increased risk of insulin resistance or diabetes. Ferroptosis is a new type of cell death mainly caused by iron-dependent oxidative damage. In the present study, we investigated potential mechanisms of iron overload induced hepatic ferroptosis and insulin resistance through in vivo and in vitro experiments. In vivo, the mice models of iron overload were established by intraperitoneal injection of iron dextran. The changes of body weight, serum ferritin and blood glucose were measured. Hematoxylin-eosin (HE) and Perl\'s stainings were used to observe the pathological changes and iron deposition in the liver of mice. In vitro, HepG2 cells were treated with ferric ammonium citrate (FAC, 9 mmol/L, 24 h) to establish the cell models of iron overload. The labile iron pool, cell viability, glucose consumption and glycogen contents were measured. The ultrastructure of mitochondria was observed by transmission electron microscope (TEM). The malondialdehyde (MDA) and glutathione (GSH) kits were used to detect lipid peroxidation in liver tissues of mice and HepG2 cells. RT-PCR and Western blot were used to detect the mRNA and protein expression levels of ferroptosis factors and JAK2/STAT3 signaling pathway. In this study, we used the iron chelator
deferasirox in mice and HepG2 cells. Iron overload caused weight loss, elevated serum ferritin, fasting blood glucose, fasting insulin, HOMA-IR, impaired glucose tolerance, and decreased insulin sensitivity in mice. HE staining and Perls staining showed clumps of iron deposition in the liver of iron overload mice. Iron overload could reduce the glucose consumption, increase MDA contents of HepG2 cells, while reduce glycogen and GSH contents in liver tissues of mice and HepG2 cells. TEM showed deletion of mitochondrial ridge and rupture of outer membrane in HepG2 cells with iron overload. Iron chelator
deferasirox could significantly improve the above indicators, which might be related to the activation of JAK2/STAT3/SLC7A11 signaling pathway and hepatic ferroptosis. Iron overload could induce hepatic ferroptosis and insulin resistance by inhibiting the JAK2/STAT3/SLC7A11 signaling pathway, and the iron chelator
deferasirox might improve hepatic insulin resistance induced by iron overload.