Department of Occupational and Environmental Health, School of Public Health, Jilin University, Changchun, China.
Department of Emergency, China-Japan Union Hospital, Jilin University, Changchun, China.
Ecotoxicol Environ Saf. 2019 Nov 30;184:109611. doi: 10.1016/j.ecoenv.2019.109611. Epub 2019 Sep 3.
Mono-2-ethylhexyl phthalate (MEHP), as the major metabolite of Di-(2-ethylhexyl) phthalate (DEHP), can induce lipid accumulation in hepatocytes and further leads to non-alcoholic fatty liver disease (NAFLD), while the underlying mechanism is unclear. We aim to clarify the effects of JAK2/STAT5 pathway on lipid accumulation induced by MEHP and the role of oxidation stress in NAFLD. BRL-3A hepatocytes were exposed to MEHP (0, 10, 50, 100 and 200 μM) for 24 h and 48 h. Then the lipid droplets in cells were observed by Oil-Red-O staining and quantified by isopropyl alcohol. The levels of TG, SOD, TBARS, AST and ALT were all detected by commercial kits. RT-PCR was used to detect mRNA expression, and western blotting was used to detect the expression of proteins encoded by JAK2/STAT5 pathway genes and lipid metabolism-related genes. As a result, MEHP promoted the lipid synthesis and accumulation in BRL-3A cells. MEHP down-regulated the expression and inhibited the activation of JAK2/STAT5. Moreover, the lipid metabolism-related kinases levels were elevated after MEHP exposure. In addition, the SOD levels were gradually decreased and the TBARS levels were increased in MEHP-treated groups. The lipid metabolism-related proteins levels were correlated with the oxidation stress levels. Furthermore, the ALT and AST levels were elevated after MEHP exposure. Therefore, we concluded that MEHP led to lipid accumulation through inhibiting JAK2/STAT5 pathway, resulted in damaging liver parenchyma and NAFLD by aggravating oxidation stress.
单-2-乙基己基邻苯二甲酸酯（MEHP）作为邻苯二甲酸二（2-乙基己基）酯（DEHP）的主要代谢物，可诱导肝细胞内脂质堆积，进而导致非酒精性脂肪性肝病（NAFLD），但其具体机制尚不清楚。本研究旨在阐明 JAK2/STAT5 通路在 MEHP 诱导的脂质堆积中的作用，以及氧化应激在 NAFLD 中的作用。用不同浓度 MEHP（0、10、50、100 和 200μM）处理 BRL-3A 肝细胞 24h 和 48h，油红 O 染色观察细胞内脂滴，异丙醇比色法检测细胞内三酰甘油（TG）水平。试剂盒检测超氧化物歧化酶（SOD）、丙二醛（TBARS）、天门冬氨酸氨基转移酶（AST）和丙氨酸氨基转移酶（ALT）的含量。采用 RT-PCR 检测 JAK2/STAT5 通路及脂质代谢相关基因的 mRNA 表达水平，Western blot 检测 JAK2/STAT5 通路及脂质代谢相关基因的蛋白表达水平。结果显示，MEHP 促进了 BRL-3A 细胞内的脂质合成和积累，下调了 JAK2/STAT5 的表达和活性，同时上调了脂质代谢相关激酶的水平。此外，MEHP 处理组的 SOD 水平逐渐降低，TBARS 水平升高，且脂质代谢相关蛋白的表达水平与氧化应激水平呈正相关。MEHP 处理组的 ALT 和 AST 水平也升高。综上所述，MEHP 通过抑制 JAK2/STAT5 通路导致脂质堆积，通过加重氧化应激损伤肝实质而导致 NAFLD。
