新城疫病毒对人NK细胞表达TRAIL的促进作用

Newcastle disease virus promotes expression of TNF-related apoptosis-inducing ligand in human NK cells

目的:研究新城疫病毒(Newcastle disease virus,NDV)刺激自然杀伤(natural killer,NK)细胞产生肿瘤坏死因子相关凋亡诱导配体(TNF-related apoptosis-inducing ligand,TRAIL)的作用机制。方法:采用免疫磁珠分选(magnetic activated cell sorting,MACS)法,分离得到高纯度的NK细胞;乳酸脱氢酶释放法检测NDV激活的NK细胞对人肝癌HepG2细胞的杀伤作用;实时荧光定量-PCR(real-time fluorogenic quantitative-PCR,RFQ-PCR)检测NDV刺激NK细胞4h后对TRAILmRNA表达水平的影响;FCM检测NDV刺激NK细胞16h时TRAIL蛋白的表达情况;ELISA法检测NDV刺激NK细胞后对其分泌干扰素γ(interferon-γ,IFN-γ)的影响;最后采用抗IFN-γ抗体中和IFN-γ后,再采用FCM检测NDV刺激的NK细胞中TRAIL蛋白的表达情况。结果:FCM检测结果显示,分离得到的NK细胞的纯度达(90.60±1.15)%;NDV刺激NK细胞16h后,明显增强NK细胞的杀伤肿瘤作用,NDV效价为204.8HU刺激组的杀伤率达到(22.28±0.84)%;RFQ-PCR及FCM检测结果显示,不同效价的NDV刺激NK细胞后,NK细胞中TRAILmRNA及蛋白表达水平均明显升高;ELISA检测结果显示,NDV刺激NK细胞后IFN-γ的分泌水平明显增加,在NDV效价为25.6HU刺激16h时达到峰值(796.47±37.87)pg/mL;采用抗IFN-γ抗体中和IFN-γ后,NK细胞中TRAIL蛋白表达水平明显下降。结论:NDV刺激NK细胞后可增强IFN-γ的分泌水平,进而通过IFN-γ上调TRAIL的表达,此途径为NDV刺激NK细胞表达TRAIL的机制之一。此外,NDV直接刺激NK细胞表达TRAIL是另一条重要的途径。

Objective： The purpose of this study is to investigate the mechanism for the TRAIL （TNF-related apoptosis-inducing ligand） expression in NK （natural killer） cells stimulated by NDV （Newcastle disease virus）. Methods： Pure NK cells were isolated by using MACS （magnetic activated cell sorting）. The cytotoxicity of NK cells stimulated by NDV was detected by LDH releasing assay. TRAIL transcription levels in NK cells stimulated by NDV were detected through RFQ-PCR （real-time fluorogenic quantitative-PCR）. TRAIL expression on NK cell membrane stimulated with NDV for 16 h was analyzed by FCM （flow cytometry）. The level of IFN （interferon） -γ was determined by ELISA after NK cells were stimulated by NDV. TRAIL expression on NK cell membrane was analyzed by FCM after applying the anti-human IFN-γ while NDV was added into NK cell medium. Results： The purity of NK cells detected by FCM was （90.60±1.15）%. NDV can enhance the cytotoxicity of NK cells after stimulation for 16 h, and the cytotoxicity of NK cells reached （22.28±0.84）% after stimulation with 204.8HU NDV. TRAIL mRNA expression levels were increased after stimulation with various concentrations of NDV for 4 h. TRAIL expression on NK cell membrane was significantly increased after stimulation with NDV for 16 h. IFN-γ level was significantly increased after NK cells were stimulated by NDV, consistent with the concentration of NDV and it was time-dependent. IFN-γ level reached a peak of 796.47±37.87 pg/mL after stimulation with 25.6 HU NDV for 16 h. TRAIL expression was significantly decreased after IFN-γ was neutralized. Conclusion： NDV can enhance the expression of IFN-γ in NK cells, and IFN-γ can up-regulate the TRAIL expression. This is one of the mechanisms for TRAIL expression on NK cells stimulated by NDV. Besides this mechanism, there exists another mechanism for TRAIL expression on NK cells directly stimulated by NDV.