CD4+,CD25+ T regulatory cells (Treg) control the immune response to a variety of antigens, including self antigens, and may offer opportunities to intervene in the course of autoimmune diseases. Several models support the idea of the peripheral generation of CD4+,CD25+ Treg from CD4+,CD25- T cells, but little is known about the endogenous factors and mechanisms controlling the peripheral expansion of CD4+,CD25+ Treg. We undertook this study to investigate the capacity of the vasoactive intestinal peptide (VIP), an immunosuppressive antiarthritic neuropeptide, to induce functional Treg in vivo during the development of collagen-induced arthritis (CIA).
We measured the number of CD4+,CD25+ Treg following VIP administration to CIA mice, and we characterized their phenotype and their ability to suppress activation of autoreactive T cells. We determined the capacity of VIP to induce Treg in vitro as well as the use of Treg in the treatment of CIA, measuring the clinical evolution and the inflammatory and autoimmune components of the disease.
The administration of VIP to arthritic mice resulted in the expansion of CD4+,CD25+,Foxp3+ Treg in the periphery and joints, which inhibited autoreactive T cell activation/expansion. VIP induced more efficient suppressors on a per-cell basis. The VIP-generated CD4+,CD25+ Treg transfer suppressed and significantly ameliorated the progression of the disease.
These results demonstrate the involvement of the generation of Treg in the therapeutic effect of VIP on CIA. The generation of highly efficient Treg by VIP ex vivo could be used as an attractive therapeutic tool in the future, avoiding the administration of the peptide to patients with rheumatoid arthritis.