伤寒沙门菌激活TRAIL信号通路促进巨噬细胞凋亡

Salmonella Typhi induces macrophage apoptosis by activating TRAIL signaling pathway

为探究伤寒沙门菌对巨噬细胞凋亡及肿瘤坏死因子相关凋亡诱导配体(tumor necrosis factor-related apoptosis inducing ligand,TRAIL)信号通路的影响,对伤寒沙门菌感染THP-1细胞早期和后期提取细胞RNA进行转录组测序(RNA-seq).通过定量PCR(qPCR)技术检测凋亡相关基因的转录水平,对RNA-seq结果进行验证,流式细胞术和蛋白质免疫印迹法检测THP-1细胞的凋亡和凋亡相关蛋白;加入TRAIL抗体结合TRAIL蛋白后,流式细胞术和蛋白质免疫印迹法检测感染早期THP-1细胞凋亡的变化.结果显示,伤寒沙门菌感染THP-1细胞后,凋亡相关基因caspase-3、caspase-8、caspase-9在感染后期转录水平显著增加,Tnfsf10、Tnfrsf10b、Tnf、Fas在感染早期和后期转录均增加,细胞凋亡率明显增加,caspase-3、caspase-8、caspase-9蛋白活化增加,TRAIL、DR5蛋白表达增加;与PBS对照组相比,加入TRAIL抗体后caspase-3蛋白活化明显减弱,细胞凋亡率明显下降.综上,伤寒沙门菌通过部分激活TRAIL信号通路来诱导巨噬细胞凋亡.

The aim of this research was to explore the effects of Salmonella enterica serovar Typhi(S.Typhi)on macrophage apoptosis and tumor necrosis factor-related apoptosis inducing ligand(TRAIL)signaling pathway.Total RNAs at early and late stages of S.Typhi infection were extracted from THP-1 cells for transcriptome sequencing(RNA-seq).Quantitative PCR(qPCR)was used to detect the transcriptional levels of apoptosis-related genes and verify the results of RNA-seq.Flow cytometry and western blot were used to determine the levels of THP-1 apoptosis and apoptosis-related proteins.After neutralizing TRAIL antibody was added to the medium,the changes in apoptosis were detected by flow cytometry and western blot in the early stage of S.Typhi infection.The results demonstrated that,the transcriptional levels of caspase-3,caspase-8 and caspase-9 in THP-1 cells were significantly up-regulated in the late stage of S.Typhi infection.In the early and late stages of S.Typhi infection,the transcriptional levels of Tnfsf10,Tnfrsf10b,Tnf and Fas were up-regulated.The rate of apoptosis was significantly increased.The activation of caspase-3,caspase-8 and caspase-9 and the expression of TRAIL and DR5 in S.Typhi infected cells were higher than that in uninfected cells.Compared with the control group,the activation of caspase-3 and the apoptosis rate were significantly reduced in TRAIL antibody treated group.It was concluded that S.Typhi induces macrophage apoptosis partly by activating TRAIL signaling pathway.