DNA immunization is associated with increased activity of type I iodothyronine 5'-deiodinase in mouse liver

Inflammatory cytokines in vitro are believed to be involved in the regulation of type I iodothyronine 5'-deiodinase (5'-DI) activity. The present study was undertaken to investigate in vivo effects of DNA immunization of mice on the 5'-DI activity in the liver. A mammalian expression vector encoding the beta-galactosidase (pCMV-betagal) was used for intradermal immunization. Furthermore, immunostimulatory CpG motifs, which induce the expression of IL-6, IL-12, IL-18, TNF-alpha/beta and IFN-gamma were coinjected as oligodeoxynucleotides. From our data we conclude that the activity of 5'-DI in mouse liver when compared to non-immunized animals (100%) was found to be significantly enhanced by DNA immunization 2 weeks (175.7%) or 3 weeks (192.6%) after the plasmid injection. In addition, the activity of the 5'-DI in mouse liver was markedly enhanced 2 weeks (252.4%) or 3 weeks (243.3%) after the injection when CpG motifs were applied together with the plasmid DNA.