Peptide-induced suppression of collagen-induced arthritis in HLA-DR1 transgenic mice

To identify peptides capable of altering the immune response to type II collagen (CII) in the context of HLA-DR.

Immunizing mice transgenic for the human HLA-DRB1*0101 immune response gene with CII elicits an arthritis (collagen-induced arthritis [CIA]) that resembles rheumatoid arthritis. We have previously identified an immunodominant determinant of CII, CII (263-270), recognized by T cells in the context of DR1. To produce synthetic peptides with the potential of disrupting the DR1-restricted immune response, synthetic analog peptides were developed that contain site-directed substitutions in critical positions. These peptides were used to treat CIA in DR1 transgenic mice.

An analog peptide, CII (256-276, N(263), D(266)), that inhibited T cell responses in vitro, was identified. When DR1 mice were coimmunized with CII and CII (256-276, N(263), D(266)), the incidence and severity of arthritis were greatly reduced, as was the antibody response to CII. Moreover, CII (256-276, N(263), D(266)) was effective in down-regulating the immune responses to CII and arthritis, even when administered 2 weeks following immunization with CII. Spleen and lymph node cells from CII-immunized mice cultured with CII (256-276, N(263), D(266)) in vitro produced increased amounts of interleukin-4 (IL-4) compared with cells cultured with the wild-type peptide, CII (256-276). Furthermore, CII (256-276, N(263), D(266)) was incapable of preventing arthritis in DR1 IL-4(-/-) mice (genetically deficient in IL-4).

These data establish that CII (256-276, N(263), D(266)) is a potent suppressor of the DR-mediated immune response to CII. Its effect is mediated, at least in part, by IL-4. These experiments represent the first description of an analog peptide of CII recognized by T cells in the context of a human major histocompatibility complex molecule that can suppress autoimmune arthritis.