Suppressive oligodeoxynucleotides inhibit Th1 differentiation by blocking IFN-gamma- and IL-12-mediated signaling.

Shirota, H
Gürsel, Mayda
Klinman, DM
Repetitive TTAGGG motifs present at high frequency in mammalian telomeres can suppress Th1-mediated immune responses. Synthetic oligonucleotides (ODN) containing TTAGGG motifs mimic this activity and have proven effective in the prevention/ treatment of certain Th1-dependent autoimmune diseases. This work explores the mechanism by which suppressive ODN block the induction of Th1 immunity. Findings indicate that these ODN inhibit IFN- -induced STAT1 phosphorylation and IL-12- induced STAT3 and STAT4 phosphorylation. As a result, T-bet expression is reduced as is the maturation of naive CD4 cells into Th1 effectors. These changes indirectly support the generation of Th2-dominated immune responses. Suppressive ODN may thus represent a novel approach to influence the Th1:Th2 balance in vivo.