Alteration of immunoregulatory genes expression in mesenchymal stromal cells upon priming with B18R as an interferon binding protein

OBJECTIVE(S): The B18R protein encoded by the Vaccinia virus decoys Type 1 interferons and inhibits the activity of several type I IFN members. In vitro transcription protocols benefit from this molecule’s involvement in enhancing cell viability by inhibiting interferon signal transduction. As a result of their immunomodulatory properties and potential to regenerate, mesenchymal stromal cells (MSCs) are increasingly considered an alternative treatment for a wide range of immune disorders. In this study, we investigated the modification of expression of several genes involved in immune-related pathways after preconditioning MSCs with two immune stimuli, including poly(I:C) and LPS. MATERIALS AND METHODS: ASCs were isolated and primed with B18R, and after exposure to poly(I:C) and LPS, the expression of the same sets of genes as in the previous experiment was evaluated. Following total RNA isolation from primed cells and cDNA preparation, real-time quantitative PCR was performed for several immunomodulatory and immune-related genes, including IDO1, TDO2, COX-2, TGF-β1, TNF-α, IL-1β, IL-6, TLR3, TLR4, and MCP-1. RESULTS: Pretreatment of MSCs with poly(I:C) and LPS significantly increased the expression of all mentioned genes, while upon the B18R challenge followed by poly(I:C) and LPS treatment, they were down-regulated. Finally, it was observed that the relative expression level of IFN-β has significantly decreased in MSCs+B18R+poly(I:C) and LPS in comparison with these groups without B18R. CONCLUSION: The data indicated that the presence of B18R prevents the overexpression of several immune-related genes, which are overexpressed in the in vitro inflammatory environment.