Structural Characterization of the Inhibitory DNA Motif for the Type A (D)-CpG–Induced Cytokine Secretion and NK-Cell Lytic Activity in Mouse Spleen Cells

Abstract

Oligodeoxynucleotides (ODN) with the CpG motif have been shown to be potent stimulators of innate immunity. A theoretical concern is that uncontrolled stimulation of the innate immune system through the TLR-9 receptor could induce, or worsen, some autoimmune diseases such as adjuvant arthritis or systemic lupus erythematosus. Safe therapeutic use of such ODN could be enhanced if one could regulate some of their stimulatory activities. We have designed a group of synthetic ODNs, which were able to inhibit the induction of NK lytic activity, IL-12p40 and IFN-gamma cytokine secretion by type A (D)-CpG-ODNs. Inhibition occurred in both DNA-sequence and dose-dependent fashion. Fifty percent inhibition was achieved with ~10-nM concentration of the most potent inhibitory ODNs. Delayed addition of these ODNs for up to 2 h was still able to profoundly affect CpG-induced IL-12p40 production at 18 h. Inhibitory DNA motif consists of two nucleotide triplets, a proximal pyrimidine-rich CCT sequence and a more distal GGG triplet. Optimal distance between these blocks is between three to five nucleotides. The linker sequence between the CCT and GGG blocks can additionally modify the activity of inhibitory ODNs, in both a positive and in negative way. When the order of CCT and GGG blocks is reversed, inhibition is completely lost. These findings suggest that CpG regulation of innate immunity can itself be regulated by particular motifs, which could be of therapeutic benefit in autoimmune diseases.

Nasolacrimal Duct Closure Modulates Ocular Mucosal and Systemic CD4+T-Cell Responses Induced following Topical Ocular or Intranasal Immunization

“…on May 10, 2018 by guest http://cvi.asm.org/ the CpG adjuvant requires engagement of Toll-like receptor 9 (TLR-9) on APCs, which induces intracellular signaling and subsequently triggers a predominantly Th1-type immune response (1,25,33). Interestingly, in this study, we demonstrated that TLR-9 is highly expressed in the rabbit conjunctiva resident CD11b ϩ cells.…”

The effect of CpG-oligodeoxynucleotides with different backbone structures and 3' hexameric deoxyriboguanosine run conjugation on the treatment of asthma in mice*1

“…The inhibitory motif is a synthetic form of PS but not PE backbone, which is especially short, 11-15 base long oligonucleotides with pyrimidin-rich triplets followed by a GGG sequence, e.g. CCTN3-5GGG sequence (18)(19)(20). There are two forms; trans and cis-form.…”

Regulation of Nucleic Acid Sensing Toll-Like Receptors in Systemic Lupus Erythematosus

“…Three are stimulatory, and one is inhibitory (Gursel, et al 2003;Verthelyi, et al 2001). Inhibitory DNAs do not require a CpG motif and the mechanism of inhibition has not been clearly defined (Gursel, et al 2003;Krieg, et al 1998;Lenert, et al 2003). Type A CpG DNAs (also called D) induce robust type I interferon production, while type B CpG DNAs (also called K) induce B cell proliferation and proinflammatory cytokine production (Verthelyi, et al 2001).…”