Characterization of a New Epitope of IRBP That Induces Moderate to Severe Uveoretinitis in Mice With H-2b Haplotype.
OBJECTIVE
Experimental autoimmune uveitis (EAU) induced in mice using the retinal antigen interphotoreceptor retinoid binding protein (IRBP) is an animal model for posterior uveitis in humans. However, EAU induced by native IRBP protein or its widely used epitope amino acid residues 1 to 20 of human IRBP (hIRBP1-20) is inconsistent, often showing low scores and incidence. We found an urgent need to identify a better pathogenic epitope for the C57BL/6 strain.


METHODS
Mice were immunized with uveitogenic peptides or with native bovine IRBP. Clinical and histological disease and associated immunological responses were evaluated. Truncated and substituted peptides, as well as bioinformatic analyses, were used to identify critical major histocompatibility complex (MHC)/T cell receptor (TCR) contact residues and the minimal core epitope.


RESULTS
The new uveitogenic epitope of IRBP, amino acid residues 651 to 670 of human IRBP (LAQGAYRTAVDLESLASQLT [hIRBP651-670]) is uveitogenic for mice of the H-2b haplotype and elicits EAU with a higher severity and incidence in C57BL/6 mice than the previously characterized hIRBP1-20 epitope. Using truncated and substituted peptides, as well as bioinformatic analysis, we identified the critical contact residues with MHC/TCR and defined the minimal core epitope. This made it possible to design MHC tetramers and use them to detect epitope-specific T cells in the uveitic eye and in lymphoid organs of hIRBP651-670-immunized mice.


CONCLUSIONS
Data suggest that hIRBP651-670 is an epitope naturally processed from a conserved region of native IRBP, potentially explaining its relatively high uveitogenicity. This epitope should be useful for basic and preclinical studies of uveitis in the C57BL/6 model and gives access to genetically engineered mice available on this background.
Laboratory of Immunology National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States.
Mary J
MJ
Mattapallil
Laboratory of Immunology National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States.
Phyllis B
PB
Silver
Laboratory of Immunology National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States.
Lizette M
LM
Cortes
Laboratory of Immunology National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States.
Anthony J
AJ
St Leger
Laboratory of Immunology National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States.
Yingyos
Y
Jittayasothorn
Laboratory of Immunology National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States.
Jennifer L
JL
Kielczewski
Center for Immunology and Inflammatory Diseases and Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States.
James J
JJ
Moon
Laboratory of Immunology National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States.
Chi-Chao
CC
Chan
Laboratory of Immunology National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States.
Rachel R
RR
Caspi
D000818:Animals; D001327:Autoimmune Diseases / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D002417:Cattle; D002478:Cells, Cultured; D004195:Disease Models, Animal; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D005136:Eye Proteins / Q000276:immunology* / Q000378:metabolism; D006239:Haplotypes; D000949:Histocompatibility Antigens Class II / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007111:Immunity, Cellular; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D012173:Retinitis / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D012177:Retinol-Binding Proteins / Q000276:immunology* / Q000378:metabolism; D012720:Severity of Illness Index; D013601:T-Lymphocytes / Q000276:immunology*; D015866:Uveitis, Posterior / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D000099214:Retinol-Binding Proteins, Interstitial
D018984:Epitopes, T-Lymphocyte; D005136:Eye Proteins; D000949:Histocompatibility Antigens Class II; D012177:Retinol-Binding Proteins; D000099214:Retinol-Binding Proteins, Interstitial; C489629:H-2A(b) antigen, mouse