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L. B. Nicholson, T. Khera, J. Boldison, D. A. Copland, A. D. Dick; This Is Peptide Synergy in EAU Exacerbates Disease. Invest. Ophthalmol. Vis. Sci. 2009;50(13):2652.
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© ARVO (1962-2015); The Authors (2016-present)
Ocular inflammation (uveitis) is a chronic disease, with an incidence of 0.2% of the UK population. Severe visual impairment develops in approximately 40% of suffers. Experimental autoimmune uveitis (EAU) is a model of some types of human uveitic diseases, i.e. ocular sarcoidosis and Behcet’s disease, and an example of organ-specific autoimmunity mediated by CD4+ T cells. In mice, retinol binding protein (RBP)-3 plays a critical role in establishing tolerance to retinal antigens. Also, immunisation of susceptible animals with peptides derived from RBP-3 induces autoimmune inflammation in the retina. The intensity of this EAU varies in different mouse strains. In this study we set out to determine whether co-immunisation with multiple peptides derived from the same autoantigen would modify the course of disease in C57BL/6 mice.
To identify novel immunogenic peptides within RBP-3, we used an IAb-specific binding algorithm to scan through the RBP-3 molecule. This algorithm generates a score for each peptide determined by the fit of individual amino acids at each of the 9 core positions. A high score suggests that the peptide is likely to bind to IAb. Based on these scores, we tested three peptides from subunits 1 and 3 and two peptides from subunits 2 and 4. We assessed the ability of these peptides to immunise and cause uveitis by proliferartion assay, cell infiltration (flow cytometry) and disease quantification (TEFI and histology). Using ELISA we also determined which cytokines were produced.
Approximately half of peptides tested were able elicit a response from C57BL/6 mice, causing T cell proliferation after immunisation and recall. Individual peptides from each subunit were able to initiate clinical disease and/or CD4+ infiltration of the retina, however none of the peptides induced disease that was significantly greater than RBP-3 1-16. We then tested whether using combinations of different peptides would modify the course of disease. We found that the disease induced with a mixture of peptides led to a more severe course of EAU compared with disease induced by a single epitope. We detected both IFNγ and IL-17 in the supernatants taken from activated splenocytes, indicating that, as expected, disease had a mixed Th1 and Th17 phenotype.
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