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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 investigate the effects of TNFα and IL-1 on the expression and transcriptional activation of glucocorticoid receptor (GR) in rat hepatocytes and to explore the underlying mechanism of inflammatory cytokines induced glucocorticoid resistance. Methods Immunocytochemical staining was used to analyze the GR expression and nuclear translocation in cultured BRL 3A rat hepatocytes stimulated with TNFα and IL 1. The changes of transcriptional activation of GR were observed by using the pMAMneo CAT analysis system of glucocorticoid responsive element reporter plasmid . Results The expression of GR protein in the cytoplasm and nucleus of BRL 3A cells was significantly decreased after cultured with TNFα and IL-1 for 12 hours, especially in the nucleus. The expression of GR in nuclei was significantly decreased. The cells transfected with pMAMneo CAT plasmid were cultured in dexamethasone In the presence of TNFα and IL 1 stimulated CAT content decreased significantly, the synergistic effect between the two more obvious. Conclusions TNFα and IL-1 can inhibit the transcriptional activation of GR by decreasing GR expression and nuclear translocation in BRL 3 cells, which may be the main mechanism of inflammatory cytokine-induced glucocorticoid resistance.