Brahma相关基因1在脂多糖诱导的急性肝炎中的作用

Effect of BRG1 in acute hepatitis induced by lipopolysaccharides

摘要:

目的  观察Brahma相关基因1（BRG1）在脂多糖（LPS）诱导的急性肝炎中的表达变化，并观察干预BRG1表达对炎症因子分泌的影响。方法  体内实验，腹腔注射LPS（2.5 mg/kg）构建小鼠肝炎模型，通过免疫组织化学及蛋白免疫印迹法（Western blot）检测BRG1的表达变化；体外实验，在人肝细胞HepG2及HepaRG培养基中加入LPS（100 ng/ml），Western blot检测BRG1的表达变化，转染BRG1质粒或特异性siRNA，通过ELISA检测白细胞介素1（IL-1）、白细胞介素6（IL-6）及肿瘤坏死因子α（TNF-α）等促炎因子的分泌。结果  体内实验，腹腔注射LPS（2.5 mg/kg）可以显著诱导小鼠的肝细胞坏死，肝细胞核浓聚，肝小叶组织结构破坏及ALT、AST的水平明显升高；同时LPS处理后肝细胞中的BRG1表达上升，BRG1在细胞核中浓聚。体外实验，LPS（100 ng/ml）处理后的HepG2及HepaRG细胞中BRG1的表达升高。同时BRG1过表达可显著促进促炎因子IL-1、IL-6及TNF-α的释放，相反BRG1沉默后可显著抑制促炎因子IL-1、IL-6及TNF-α的释放。结论  LPS可促进小鼠肝脏中及体外培养肝细胞的BRG1蛋白表达，干预BRG1表达可影响细胞释放IL-1、IL-6及TNF-α的能力。

Abstract:

Objective To observe the expression of Brahma-related gene 1 (BRG1) in acute hepatitis induced by lipopolysaccharide (LPS) and the effect of intervention of BRG1 expression on secretion of inflammatory factors. Methods For in vivo experiments, a hepatitis mouse model was constructed by intraperitoneal injection of LPS (2.5 mg/kg), then the expression of BRG1 was detected though immunohistochemical staining and Western blot. For in vitro experiments, LPS (100 ng/ml) was added in human liver cell line HepG2 and HepaRG culture media, and then, the expression of BRG1 was detected through Western blot. Meanwhile, BRG1 plasmid or specific siRNA was transfected into HepG2 and HepaRG cells, enzyme linked immunosorbent assay (ELISA) was performed to detect the IL-1, IL-6 and TNF-α secretion. Results in vivo, intraperitoneal injection of LPS could obviously induce necrosis of hepatic cells and lobules, together with condensation of nuclei in mice. Meanwhile, the expression of BRG1 was enhanced in mouse hepatic cells after procession by LPS, and accumulated in nuclei. In vitro experiments showed the expression of BRG1 in HepG2 and HepaRG cells increased after treatment by LPS (100 ng/ml). At the same time, the overexpression of BRG1 significantly promoted the release of pro-inflammatory cytokines IL-1, IL-6 and TNF-α; the silence of BRG1 inhibited the release of IL-1, IL-6 and TNF-α. Conclusions LPS could promote the expression of BRG1 protein both in vivo and in mouse liver cell lines, and intervention of BRG1 expression might affect the secretion of IL-1, IL-6 and TNF-α.