Enterovirus 71 can induce autophagy and apoptosis of THP-1 macrophages / 南方医科大学学报

ABSTRACT

OBJECTIVE@#To investigate enterovirus 71 (EV71)-induced of autophagy, apoptosis and the related signaling pathways in THP-1 macrophages.@*METHODS@#THP-1 macrophages were infected with EV71 at the multiplicity of infection (MOI) of 0.1 for 2, 8 or 16 h, and the cell proliferation and toxicity were analyzed using CCK-8 kit. The intracellular viral nucleic acid in THP-1 macrophages were detected by fluorescence quantitative PCR, and the ultrastructural changes of the cells were observed using transmission electron microscopy. Cell apoptosis induced by EV71 infection was detected using Hoechst 33342 staining and AnnexinV/PI double staining. Western blotting was performed for analysis of changes in autophagy and apoptosis of the cells and in the expressions of the related proteins. The effect of EV71 infection on apoptosis of THP-1 macrophages incubated with 3-MA and Ac-DEVD-CHO inhibitor for 2 h was assessed using Western blotting.@*RESULTS@#EV71 infection significantly lowered the cell survival rate of THP-1 macrophages at 2, 8 h and 16 h after the infection ( < 0.05). The total copy number of viral nucleic acid in THP-1 macrophages incubated with EV71 increased significantly and progressively over time ( < 0.01). Intracellular autophagosomes and virions could be seen in EV71-infected THP-1 macrophages. The total apoptotic rate of the infected cell also increased significantly over time ( < 0.01). EV71 infection significantly increased LC3 conversion (LC3-Ⅱ/ LC3-I) and the expression of cleaved caspase 3 protein and decreased the protein expressions of p62, Bcl-2 and caspase-3 ( < 0.01) without causing obvious changes in cleaved caspase-8 (>0.05). 3-MA significantly inhibited the EV71-induced autophagy of THP-1 macrophages and reduced LC3 conversion (LC3-Ⅱ/LC3-I) and p62 protein expression at 8 h after EV71 infection ( < 0.01). Compared with DMSO, Ac-DEVD-CHO significantly inhibited EV71-induced apoptosis of THP-1 macrophages (15.5% 7.7%, < 0.01).@*CONCLUSIONS@#EV71 not only can infect and replicate in THP-1 macrophages, but also induces autophagy and cell apoptosis possibly by activating LC3/p62 autophagy pathway and caspase apoptosis pathway.