Conclusions
These clinical and immunological data suggest the use of CpG as a potent adjuvant for mucosal peptide-specific immune therapy in arthritis.
Methods
The peptide used is a heat shock protein 60 epitope (p1) that elicits tolerogenic peptide-specific immune responses in human arthritis patients and was recently shown to have protective capacity as a bystander antigen in the rat adjuvant arthritis model. Rats were treated with three nasal doses of p1, CpG or a combination of p1 and CpG. Antigen-presenting cells were studied in nose-draining lymph nodes (mandibular lymph nodes; MLN) after nasal treatment, and T-cell responses were analysed in joint-draining lymph nodes after arthritis induction.
Results
Nasal co-administration of p1/CpG significantly augmented the arthritis-protective effect of p1, while CpG treatment alone did not. Co-treatment of p1/CpG increased both the number and activation status of pDC in draining MLN, which was accompanied by amplified p1-specific T-cell proliferation and interleukin (IL)-10 production. During early arthritis, p1-specific IL-10 production was identified at the site of inflammation. P1 and p1/CpG-treated rats showed a greater amount of CD4+FoxP3+ regulatory T cells in the joint-draining lymph nodes, which correlated with lower arthritis scores. Conclusions: These clinical and immunological data suggest the use of CpG as a potent adjuvant for mucosal peptide-specific immune therapy in arthritis.