Nucleic Acids Modulate Autoimmunity Through Nucleic-Acid-Specific Toll-Like Receptors

Using Poly I:C as an adjuvant does not induce or exacerbate models of systemic lupus erythematosus

Subunit vaccines are typically poorly immunogenic when administered alone, and require adjuvants for robust responses. Triggering TLRs to boost antigen-specific adaptive immunity is an attractive approach to increase the potency and quality of vaccines. However, recent reports suggest that alterations in TLR expression are associated with the pathogenesis of inflammatory and autoimmune diseases. To compare genetic studies with adjuvant studies, we examined whether stimulation through a TLR agonist induces or increases the autoimmune phenotype of healthy or autoimmune mice. C57BL/6, MRL/lpr, and Fcγr2b-deficient mice were dosed i.p. with Poly I:C every other day for 3 weeks, and monitored for signs of autoimmunity over 3 months. A separate group of mice was vaccinated three times i.m. with rPA anthrax antigen with or without Poly I:C with 2 weeks between doses. Immunized groups exhibited robust responses to vaccine and C57BL/6 and MRL/lpr mice showed a statistically significant increase in anti-rPA IgG responses in the presence of Poly I:C. Interestingly, Fcγr2b-/- mice showed increases with the base rPA vaccine, which was not significantly increased when Poly I:C was used as an adjuvant. In the chronically dosed groups, we also observed subtle alterations in levels of total antibody and some autoantibodies. However, there were no statistically significant differences in autoimmune syndrome, as measured by proteinurea, kidney pathology, weight loss, and mortality, with Poly I:C administration in chronic or vaccination mode. Taken together, these results suggest that administration of TLR3 agonists in chronic or vaccination mode does not induce or exacerbate models of systemic lupus erythematosus.