红细胞生成素对人单核细胞前炎症因子的影响及机理

摘要

红细胞生成素(erythropoietin,EPO)是治疗慢性病贫血(anemia of chronic disease,ACD)的主要药物,通过刺激造血、抑制hepcidin和前炎症因子而改善贫血.近来发现单核细胞是hepcidin的另一来源,EPO能降低IL-6诱导的hepcidin,推测EPO可能通过降低IL-6进而抑制hepcidin的间接途径.然而,EPO降低单核细胞IL-6相应的分子生物学机制还不清楚.本研究探讨EPO对单核细胞前炎症因子的作用及其分子学机制.采用实时定量PCR 检测IL-6 mRNA和TNF-α mRNA表达,Western blot方法检测PARP-1信号分子的蛋白水平.采用1μg/ml脂多糖(lipopolysaccharide,LPS)刺激THP-1单核细胞,观察EPO不同浓度(0.5,1,2,5,10 U/ml)和作用时间(0,3,6,12,24小时)对THP-1单核细胞IL-6 mRNA、TNF-α mRNA以及PARP-1蛋白的抑制作用.加用1μg/ml或5μg/ml EPO受体(EPOR)抗体和/或3-氨基苯甲酰胺(3AB,PARP-1抑制剂),观察其对EPO的拮抗作用以及对PARP-1信号分子的影响.结果表明,1μg/ml LPS可以明显促进THP-1单核细胞IL-6和TNF-αmRNA表达.EPO可抑制LPS诱导的IL-6和TNF-αmRNA表达,且呈浓度和时间依赖性:对于IL-6 mRNA,2 U/ml EPO作用6小时的抑制作用最明显;对于TNF-αmRNA,10 U/ml EPO作用3小时的抑制作用最明显.研究发现,LPS诱导IL-6 mRNA表达升高的同时PARP-1蛋白水平也明显增加,EPO抑制IL-6 mRNA表达的同时PARP-1蛋白也下降,且2 U/ml EPO 作用6小时对IL-6和PARP-1蛋白均有明显抑制.3AB是PARP-1的直接抑制剂,EPO受体的抗体与3AB相似,可拮抗EPO对IL-6的抑制作用.结论:EPO能够抑制单核细胞IL-6和TNF-α表达,EPO可能通过降低PARP-1水平抑制IL-6的表达.%Erythropoietin (EPO) is the major means of treating anemia of chronic disease (ACD) through stimulating hematopoiesis, inhibiting hepcidin and decreasing proinflammatory factors. Recently, it has been found that monocytes are another source of hepcidn. EPO can reduce the hepcidin stimulated by IL-6 in monocytes, it is assumed that EPO can reduce hepcidin indirectly by reducing IL-6. However, the specific mechanism of EPO inhibiting the proinflammatory cytokines in monocytes is unclear now. This study was purposed to investigate the effect of EPO on monocyte proinflammatory factors and its molecular mechanism. IL-6 mRNA and TNF-α mRNA were detected by real time PCR,level of signaling molecule PARP-1 protein was detected by Western blot. THP-1 monocytes were stimulated by 1 μg/ml lipopolysaccharide( LPS ) to observe the impact of EPO at different concentrations (0.5,1,2 , 5,10 U/ml ) for different time(0,3,6,12,24 hours) on the expression of IL-6 mRNA,TNF-α mRNA and PARP-1 protein. 1 μg/ml or 5 μg/ml EPO receptor (EPOR) antibody and/or 3-aminobenzamide( 3-AB, PARP-1 inhibitor) were added to observe the antagonistic effect on EPO and the impact on PARP-1. The results showed that LPS could stimulate the THP-1 cells. EPO could decrease the levels of IL-6 and TNF-α stimulated by LPS in a dose- and time-dependent manners. The most significant decrease in IL-6 mRNA expression was observed in 2 U/ml EPO for 6 hours. And down-regulation of TNF-α mRNA expression was pronounced at 10 U/ml EPO for 3 hours. IL-6 mRNA expression could be stimulated by LPS,PARP-1 protein was induced at the same time. EPO inhibited the expression of IL-6 mRNA, while PARP-1 protein also decreased. Down-regulation of IL-6 mRNA and PARP-1 protein level was pronounced at 2 U/ml EPO for 6 hours. 3AB is a direct inhibitor of PARP-1. Similar to 3AB, EPO receptor antibody could antagonize the decline of IL-6 induced by EPO. It is concluded that EPO can inhibit the expression of IL-6 and TNF-α in monocytes, and the inhibition of IL-6 expression may be associated with decrease of PARP level.