title: A conformationally-constrained MHC class II I-Ag7-derived peptide protects NOD mice from the development of diabetes.
abstract: Allele-specific peptide vaccination against disease-associated MHC class II molecules is a promising new strategy for modulating self-antigen presentation to autoreactive T cells in autoimmune diseases. To evaluate the potential of this approach for treatment of insulin-dependent diabetes mellitus (IDDM), we have designed a cyclic peptide vaccine, DiavaX, from the third hypervariable region of the beta-chain of the NOD mouse MHC class II I-Ag7. NOD mice were treated at 5 and 9 weeks of age with 100 microg DiavaX emulsified in alum, a control peptide in alum, or alum alone. At the end of the study, 87% of alum treated mice had developed diabetes, compared with only 28% of DiavaX-treated mice. None of the control peptides, including a linear I-Ag7, a scrambled cyclic I-Ag7, or an analogous cyclic I-Aspeptide, reduced the incidence of diabetes, demonstrating that the protective effect of DiavaX is conformationally dependent and both allele- and sequence-specific. DiavaX treatment did not cause any general immune suppression, but did induce peptide-specific antibodies and memory T cells. DiavaX-induced protection from diabetes was associated with the maintenance of a non-destructive islet-associated autoimmune response. These data indicate that a conformationally constrained peptide from the disease-associated MHC represents a potential vaccine candidate for the prevention of clinical IDDM.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000097:blood; D003922:Diabetes Mellitus, Type 1 / Q000517:prevention & control*; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D051379:Mice; D016688:Mice, Inbred NOD; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology*; D010456:Peptides, Cyclic / Q000276:immunology*; D011487:Protein Conformation; D014611:Vaccination; D014612:Vaccines / Q000276:immunology*