Influence of HCMV infection on autophagy in THP-1 derived macrophage

Abstract

Objective To study the autophagy in THP-1 derived macrophage after HCMV infection. Methods The cell model of HCMV-infected THP-1 derived macrophage was established. The experiment groups were HCMV infection group (HCMV group), heat inactivated HCMV infection group (Heat-HCMV group), mock control group (M group) and positive control group (autophagy induced by 400 nmol rapamycin, RAPA group). The multiplicity of infection was 1. Western blot assay was used to detect the dynamic changes of the autophagy-related protein (beclin1) and LC3 transformation (LC3-II/LC3-I) at 1 h, 3 h, 6 h, 12 h, 24 h and 48 h after HCMV infection. The numbers of autophagic vacuoles formed in cytoplasm were observed by transmission electron microscope at 6 h, 12 h and 24 h after infection. Results For HCMV group, beclin1 increased significantly at 1 h after infection and was higher than that in M group. LC3 transformation increased dramatically at 6 h after infection and was higher than that in M group. However, the expression of beclin1 and LC3 transformation decreased obviously compared to the RAPA group at 24 h and 48 h after infection. For Heat-HCMV group, the expression of beclin1 increased significantly at 1 h after infection and was higher than that in the mock control group. LC3 transformation increased dramatically at 6 h after infection and was higher than that in M group. The number of autophagic vacuoles increased at 6 h after infection; however, it decreased significantly at 24 h after infection. For Heat-HCMV group, the numbers of autophagic vacuoles continued to increase at 48 h after infection. Conclusions At early stage of infection, HCMV can stimulate autophagy in THP-1 derived macrophages, which may not depend on the replication of HCMV. At the late phase of infection, the inhibition of autophagy in THP-1 derived macrophages may be related to the factors such as viral replication, but further experiments are needed to confirm it. Key words: Cytomegalovirus; Macrophages; Autophagy; THP-1 derived macrophage