The effect of promoter strength in adenoviral vectors in hyperplastic synovium

Objectives To compare the activity of the CytoMegaloVirus promoter (CMV) and the Major Late promoter (MLP) in synoviocytes in vitro and in vivo. To determine the phenotype of infected cells and the induction of inflammation. To investigate the effects of the cytomegalovirus (CMV) or major late (MLP) promoter on adenovirus-mediated reporter gene transduction of synoviocytes in vitro and in vivo. Methods After infection with adenoviral vectors harboring CMV- and MLP-driven luciferase and lacZ genes, gene expression was examined in cultured synoviocytes and in the synovium of rhesus monkeys with collagen-induced arthritis. Immunohistochemical staining for the macrophage-marker CD68 and lacZ expression was performed Inflammation was scored in the synovial membrane of injected and non-injected joints. Results CMV-driven reporter gene expression was found to be 6 to 10 times higher than MLP-driven gene expression in both cultured synoviocytes and monkey synovium. Both CD68 positive and CD68 negative cells were lacZ positive. Inflammation in joints injected with CMV-driven adenoviral vectors was not higher than that in MLP-driven adenoviral vectors- or non-injected joints. Conclusion These experiments show that the CMV promoter induces higher gene expression in synoviocytes than the MLP promoter. Both fibroblast-like and macrophage-like synoviocytes can be infected with adenoviral vectors. No deleterious effects of the CMV-promoter driven adenoviral vectors were observed.