myelin-oligodendrocyte-glycoprotein-(35-55) and Diabetes-Mellitus--Type-1

The NKG2D activating receptor has been implicated in numerous autoimmune diseases. We tested the role of NKG2D in models of autoimmunity and inflammation using NKG2D knockout mice and antibody blockade experiments. The severity of experimental autoimmune encephalitis (EAE) was decreased in NKG2D-deficient mice when the disease was induced with a limiting antigen dose, but unchanged with an optimal antigen dose. Surprisingly, however, NKG2D deficiency had no detectable effect in several other models, including two models of type 1 diabetes, and a model of intestinal inflammation induced by poly(I:C). NKG2D antibody blockade in normal mice also failed to inhibit disease in the NOD diabetes model or the intestinal inflammation model. Published evidence using NKG2D knockout mice demonstrated a role for NKG2D in mouse models of atherosclerosis and liver inflammation, as well as in chronic obstructive pulmonary disease. Therefore, our results suggest that NKG2D plays selective roles in inflammatory diseases.

Topics: Amino Acid Sequence; Animals; Antibodies, Neutralizing; Diabetes Mellitus, Type 1; Encephalomyelitis, Autoimmune, Experimental; Female; Gene Expression; Inflammatory Bowel Diseases; Killer Cells, Natural; Male; Mice; Mice, Inbred NOD; Mice, Knockout; Molecular Sequence Data; Myelin-Oligodendrocyte Glycoprotein; NK Cell Lectin-Like Receptor Subfamily K; Peptide Fragments; Poly I-C; Severity of Illness Index

Antigen-presenting cell-associated four-domain MHC class II (MHC-II) molecules play a central role in activating autoreactive CD4(+) T cells involved in multiple sclerosis (MS) and type 1 diabetes (T1D). In contrast, two-domain MHC-II structures with the same covalently attached self-peptide (recombinant T-cell receptor ligands (RTLs)) can regulate pathogenic CD4(+) T cells and reverse clinical signs of experimental autoimmune diseases. RTL1000, which is composed of the β1α1 domains of human leukocyte antigen (HLA)-DR2 linked to the encephalitogenic human myelin oligodendrocyte glycoprotein (MOG)-35-55 peptide, was recently shown to be safe and well tolerated in a phase I clinical trial in MS. To evaluate the opposing biological effects of four- versus two-domain MHC-II structures, we screened phage Fab antibodies (Abs) for the neutralizing activity of RTL1000. Five different TCR-like Abs were identified that could distinguish between the two- versus four-domain MHC-peptide complexes while the cognate TCR was unable to make such a distinction. Moreover, Fab detection of native two-domain HLA-DR structures in human plasma implies that there are naturally occurring regulatory MHC-peptide complexes. These results demonstrate for the first time distinct conformational determinants characteristic of activating versus tolerogenic MHC-peptide complexes involved in human autoimmunity.

Topics: Animals; Antigen-Presenting Cells; Autoimmunity; CD4-Positive T-Lymphocytes; Diabetes Mellitus, Type 1; Encephalomyelitis, Autoimmune, Experimental; Enzyme-Linked Immunosorbent Assay; Flow Cytometry; Glycoproteins; Histocompatibility Antigens Class II; HLA-DR2 Antigen; Humans; Immune Tolerance; Immunoglobulin Fab Fragments; Major Histocompatibility Complex; Mice; Mice, Transgenic; Multiple Sclerosis; Myelin-Oligodendrocyte Glycoprotein; Peptide Fragments; Receptors, Antigen, T-Cell; Recombinant Fusion Proteins; Recombinant Proteins