Fig. 5

Over-expression of SOCS1 reverses the anti-viral effects of luteolin. a A549 cells were pre-treated with 50 μM luteolin for 24 h before infected with RSV at MOI = 0.05. At the indicated hours post infection, proteins were extracted for western blotting to detect the SOCS1, CIS, SOCS2, SOCS3, SOCS6, SHP-1 and SHP-2 expressions. b MEFs were pre-treated with 50 μM luteolin for 24 h before infected with RSV at MOI = 0.05. At 24 hpi, proteins were extracted for western blotting to detect the SOCS1 expression. A549 cells were transfected with SOCS1 plasmid or control plasmid. 24 h later, cells were stimulated with luteolin for 24 h before infected with RSV. c At the indicated hours post infection, virus titer or RSV-F mRNA expression was determined by plaque assay or RT-qPCR, respectively. d At the indicated hours post infection, cells were collected for RNA extraction and RT-qPCR was performed to detect the MX1, OAS1 and ISG15 expressions. e A549 cells were co-transfected with ISRE-luc and SOCS1 plasmid or control plasmid. 24 h later, cells were stimulated with luteolin for 24 h before infected with RSV. At 12 or 24 h post infection, cells were collected, and luciferase activities were determined. Data shown are means ± SEM. Statistical significance was examined by Students’ t-test. P < 0.05 was considered statistically significant. *P < 0.05, **P < 0.01, ***P < 0.001. SOCS suppressor of cytokine, RSV respiratory syncytial virus, CIS cytokine-induced STAT inhibitor, SHP protein-tyrosine phosphatase, MOI multiplicity of infection