TNF-α和IL-1对大鼠肝细胞糖皮质激素受体表达及功能的影响

Effects of TNF-α and IL-1 on expression and function of glucocorticoid receptor in rat hepatocytes in vitro

目的 研究TNF α和IL 1对大鼠肝细胞糖皮质激素受体 (GR)的表达和转录激活能力的影响 ,探讨炎性细胞因子诱发糖皮质激素抵抗的内在机制。方法 免疫细胞化学染色分析经TNF α和IL 1刺激培养后BRL 3A大鼠肝细胞株GR的表达和核转位变化 ,应用糖皮质激素反应元件报告质粒pMAMneo CAT分析系统观察GR的转录激活能力改变。结果 BRL 3A细胞经TNF α和IL 1刺激培养 12h后 ,其胞浆和胞核GR蛋白水平的表达明显降低 ,尤以核内GR降低更加显著 ;转染pMAMneo CAT质粒的肝细胞在地塞米松存在情况下 ,经TNF α和IL 1刺激后CAT含量显著下降 ,两者协同效果更加明显。结论 TNF α和IL 1可以通过降低BRL 3细胞GR的表达和核转位而抑制GR的转录激活能力 ,这可能是炎性细胞因子诱发糖皮质激素抵抗的主要机制。

Objective To study the effects of TNF-α and IL-1 on the expression and function of glucocorticoid receptor(GR) in rat hepatocytes in order to investigate the mechanism of glucocoticoid resistance induced by inflammatory cytokines. Methods Immunohistochemical methods were used to detect the expression and translocation of GR from the cytoplasm to nucleuses of liver epithelial cell strain BRL-3A. After BRL-3A cells were transfected with pMAMneo-chloramphenicol acetyltransferase (pMAMneo-CAT) reporter gene, the ability of GR-mediated gene transcription was measured by using glucocorticoid response element (GRE) reporter plasmid pMAMneo-CAT analysis system. Results After the stimulation of TNF-α and IL-1 respectively, the expression of GR in the cytoplasm and nucleuses of BRL-3A cells were both down-regulated, with more notable in the latter than in the former. The production of CAT controlled by GR in BRL-3A cells with pMAMneo-CAT transfection was significantly decreased after the stimulation of TNF-α and IL-1 in present of dexamethasone, and decreased further when TNF-α and IL-1 were combined. Conclusion Both of TNF-α and IL-1 can decrease the expression and translocation of GR from the cytoplasm to the nucleuses of rat hepatocytes, and then inhibit the transcription activation of GR, which may be one of the main reasons of glucocorticoid resistance induced by inflammatory cytokines.