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目的探讨激活素A(Activin A)抑制脂多糖(Lipopolysaccharides,LPS)活化巨噬细胞的作用机制。方法取小鼠巨噬细胞系RAW264.7细胞,分别添加Activin A(5 ng/ml)、LPS(1μg/ml)和Activin A(5 ng/ml)+LPS(1μg/ml),同时设以含单纯2.5%胎牛血清的DMEM培养液培养的细胞作为对照孔,培养24 h后,采用还原酶法检测细胞分泌一氧化氮(Nitric oxide,NO)的水平,流式细胞术分析TLR2和TLR4蛋白的表达水平,RT-PCR分析细胞ActRⅡA和ActRⅡB基因mRNA的转录水平。结果 Activin A和LPS单独作用均促进RAW264.7细胞分泌NO,但二者联合使用时,Activin A可抑制LPS刺激RAW264.7细胞的NO分泌;Activin A能抑制LPS上调RAW264.7细胞TLR4蛋白的表达,但对TLR2蛋白的表达无影响;LPS可促进RAW264.7细胞ActRⅡA基因mRNA的转录水平,但对ActRⅡB基因mRNA的转录水平无影响。结论 Activin A通过调控TLR4途径抑制LPS的作用,LPS可能通过促进ActRⅡA的表达进一步增强Activin A的负反馈调节作用。
Objective To investigate the mechanism of Activin A inhibiting the activation of macrophages by lipopolysaccharides (LPS). Methods Mouse macrophage cell line RAW264.7 cells were treated with Activin A (5 ng / ml), LPS (1 μg / ml) and Activin A (5 ng / ml) + LPS The cells cultured in DMEM culture medium containing 2.5% fetal bovine serum alone served as control wells. After cultured for 24 h, the levels of nitric oxide (NO) secreted by cells were measured by reductase method. The expressions of TLR2 and TLR4 The expression of ActRⅡA and ActRⅡB mRNA was detected by RT-PCR. Results Both Activin A and LPS promoted the secretion of NO in RAW264.7 cells, but when used in combination, Activin A inhibited LPS-stimulated NO secretion in RAW264.7 cells. Activin A inhibited LPS up-regulation of TLR4 protein in RAW264.7 cells LPS could promote the transcription of ActRⅡA gene mRNA in RAW264.7 cells, but had no effect on the transcription level of ActRⅡB mRNA. Conclusion Activin A can inhibit the LPS by regulating the TLR4 pathway. LPS may further enhance the negative feedback regulation of Activin A by promoting the expression of ActRⅡA.