Cytokine and Ig-production by CG-containing sequences with phosphorodiester backbone and dumbbell-shape

Abstract

Background: Immunostimulatory oligodeoxynucleotides (CpG-ODN) usually contain phosphorothioate (PS) backbones for nucleotide protection, which may result in some nonspecific side-effects like prolongation of coagulation time. Objective: The aim of the present study was to investigate the immunomodulatory potential of DNA molecules without PS backbones. Thus, we designed phosphorodiester (PO) molecules with a dumbbell-like covalently-closed structure (dSLIM-30L1). Methods: We analyzed their effects on peripheral blood mononuclear cells (PBMC) from spontaneous high and low immunoglobulin (Ig)E producer (allergic and nonallergic donors) in comparison with linear CpG-ODN (lin-30L1) with PS backbones, using enzyme-linked immunosorbent assay and flow cytometry. Results: We observed a decrease of spontaneous IgE levels in PBMC from high IgE producer of approximately 27% with both dSLIM-30L1 and lin-30L1. In addition, both molecules enhanced the production of IgA, IgM and IgG1/IgG2, but with a slightly different pattern. Both molecules stimulated the secretion of the TH1-like cytokines interleukin (IL)-2, interferon-γ and IL-12p40 and the pro-inflammatory cytokine IL-6. The immunomodulatory potential of dSLIM-30L1 and lin-30L1 was also effective in PBMC from nonallergic donors, as was confirmed for IL-2, IL-12p40, IgG1/IgG2 and IgM. Conclusion: Our data show an inhibition of IgE production but also enhancement of the inflammatory cytokine response in PBMC from allergic and nonallergic donors by covalently-closed PO-based dSLIM-30L1 with a pattern similar to that of linear PS-based lin-30L1, while avoiding PS-modifications and thus PS-mediated side-effects. Whether such molecules are useful for the treatment of allergic diseases will need further clarification by appropriate in vivo studies. Copyright © Blackwell Munksgaard 2005.