bromochloroacetic-acid and Uveitis

Peptides derived from amino acid sequence 60-80 of HLA-B27 (B27PA, aa 60-72 and B2702PA, aa 60-80) mimic cytokeratin and are able to induce in vitro proliferation of human peripheral blood lymphocytes as well as arthritis in Lewis rats. Here we show that the pathogenic epitope recognized by autoaggressive rat T cells is located at the N-terminus of the sequence, between aa 60 and 72. A C-terminally elongated 25mer peptide (B2702.60-84) showed increased pathogenicity, indicating either a second arthritogenic epitope or an immunomodulatory region within this peptide. B2702.60-84 has been described to inhibit murine and human CD8 + cytotoxic T cells (CTL) and was even successfully used for the treatment of allograft rejection. In addition to pathogenicity we have investigated the immunomodulatory effect of peptide B2702.60-84 in our rat model of experimental autoimmune uveitis (EAU), induced with retinal S-Antigen peptide PDSAg. We found that disease exacerbated following coimmunization of PDSAg with B2702.60-84. In vitro, the B27-peptide enhanced the proliferation of CD4+ T cell lines specific for retinal autoantigen peptides during coincubation of B2702.60-84 with the respective antigen. Oral tolerance induction, an effective mechanism to prevent uveitis in Lewis rats, is abrogated by cofeeding peptide B2702.60-84 with the tolerogen PDSAg. In rat EAU, naturally occurring regulatory T cells and orally induced gamma deltaTCR+ suppressor cells are CD8+ which might be impeded by peptide B2702.60-84. As a consequence of their abrogated suppressive capacity disease was exacerbated. We propose a similar role of HLA-B27 in man: disturbing the mechanisms down-regulating self-responses might lead to autoimmune diseases. This could explain the high association of HLA-B27 with a variety of autoimmune diseases targeting different organs or tissues.

Topics: Amino Acid Sequence; Animals; Arthritis; Autoimmune Diseases; Cell Proliferation; Disease Models, Animal; Female; HLA-B27 Antigen; Immune Tolerance; Keratins; Male; Molecular Sequence Data; Peptide Fragments; Rats; Rats, Inbred Lew; T-Lymphocytes; Uveitis

Previously we have described the role of two 14mer peptides in autoimmune uveitis, PDSAg from the retinal autoantigen S-antigen (S-Ag) and B27PD from the sequence of disease-associated HLA-B molecules, which show antigenic mimicry. The retinal peptide gave rise to severe uveitis in the Lewis rat model of experimental autoimmune uveitis (EAU) and was effective in inducing oral tolerance, while the HLA peptide B27PD caused only mild disease, but it was at least equally effective in preventing uveitis by oral tolerance. Here, we further defined the major T cell epitopes on both peptides responsible for the different functions. For this purpose we tested C- and N-terminal truncations, and chimeras consisting of amino acid sequences of both peptides in vitro and in vivo. We were able to determine the motif for binding to Lewis rat MHC class II as well as those amino acids important for recognition by T cells specific for the retinal peptide. The minimal MHC-binding nonamer peptide of PDSAg was not recognized by TCR, and we also found striking differences of T cell recognition in vitro and in vivo. The ability to induce oral tolerance was not closely correlated with uveitogenicity or with strong binding to MHC class II molecules. Our data furthermore demonstrate the importance of specific and exact trimming of peptides to be presented on MHC class II, suggesting that the presentation of cryptic epitopes is favored or prevented by existence of multiple MHC-binding motifs within a certain amino acid sequence, which can result in different or altered T cell reactions.

Topics: Administration, Oral; Amino Acid Sequence; Animals; Arrestin; Autoantigens; Binding, Competitive; Cells, Cultured; Epitopes, T-Lymphocyte; Female; Histocompatibility Antigens; Immune Tolerance; Keratins; Lymph Nodes; Lymphocyte Activation; Male; Molecular Mimicry; Oligopeptides; Rats; Rats, Inbred Lew; Receptors, Antigen, T-Cell; Sequence Alignment; T-Lymphocytes; Uveitis

Ankylosing spondylitis (AS) is highly associated with HLA-B27. We have previously shown that peripheral blood lymphocytes from AS patients respond to stimulation with a peptide from the sequence of HLA-B27. Here we report on molecular mimicry of peptides from HLA-B27 and cytokeratin, the latter being specifically expressed in synovial membranes and eyes, the main targets of the autoaggressive immune response in AS patients. Immunization of rats with these peptides induced an inflammatory response in joints, spine and eyes, resembling the symptoms in AS. Furthermore, both HLA-B27- and cytokeratin-derived peptides, are effective oral tolerogens: feeding these peptides ameliorated arthritis and uveitis induced with the cytokeratin peptide. Our model might elucidate the role of peptides from the sequence of HLA-B27 as an antigen of the immune response in AS, introducing a new aspect of antigenic mimicry between HLA-B27 and tissue-specific antigens. We propose this as a mechanism directing a systemic autoimmune response to specific target organs by antigenic mimicry of T cell epitopes.

Topics: Amino Acid Sequence; Animals; Arthritis; Cross Reactions; Female; HLA-B27 Antigen; Immune Tolerance; Keratins; Male; Molecular Mimicry; Molecular Sequence Data; Peptides; Rats; Rats, Inbred Lew; T-Lymphocytes; Uveitis

Topics: Adenocarcinoma; Aged; Aqueous Humor; Biomarkers, Tumor; Carcinoembryonic Antigen; Cytological Techniques; Eye Neoplasms; Humans; Immunoenzyme Techniques; Immunophenotyping; Keratins; Lung Neoplasms; Male; Syndrome; Tomography, X-Ray Computed; Uveitis; Vitreous Body

To determine whether syngeneic retinal cells injected in the vitreous cavity of the rat are able to initiate a proliferative process and whether the ocular inflammation induced in rats by lipopolysaccharide (LPS) promotes this proliferative vitreoretinopathy (PVR).. Primary cultured differentiated retinal Müller glial (RMG) and retinal pigmented epithelial (RPE) cells isolated from 8 to 12 postnatal Lewis rats were injected into the vitreous cavity of 8- to 10-week-old Lewis rats (10(5) cells/eye in 2 microlieter sterile saline), with or without the systemic injection of 150 microgram LPS to cause endotoxin-induced uveitis (EIU). Control groups received an intravitreal injection of 2 microliter saline. At 5, 15, and 28 days after cell injections, PVR was clinically quantified, and immunohistochemistry for OX42, ED1, vimentin (VIM), glial fibrillary acidic protein (GFAP), and cytokeratin was performed.. The injection of RMG cells, alone or in combination with RPE cells, induced the preretinal proliferation of a GFAP-positive tissue, that was enhanced by the systemic injection of LPS. Indeed, when EIU was induced at the time of RMG cell injection into the vitreous cavity, the proliferation led to retinal folds and localized tractional detachments. In contrast, PVR enhanced the infiltration of inflammatory cells in the anterior segment of the eye.. In the rat, syngeneic retinal cells of glial origin induce PVR that is enhanced by the coinduction of EIU. In return, vitreoretinal glial proliferation enhanced the intensity and duration of EIU.

Topics: Animals; Cell Transplantation; Cells, Cultured; Fluorescent Antibody Technique, Indirect; Glial Fibrillary Acidic Protein; Injections; Keratins; Lipopolysaccharides; Neuroglia; Pigment Epithelium of Eye; Rats; Rats, Inbred Lew; Receptors, Complement 3b; Retina; Retinal Detachment; Salmonella typhimurium; Transplantation, Isogeneic; Uveitis; Vimentin; Vitreoretinopathy, Proliferative; Vitreous Body

During vitreoretinal surgery, 23 epiretinal membranes from eyes treated with silicone oil were removed. They were examined by immunohistochemical methods and compared with 15 membranes from eyes affected by proliferative vitreoretinopathy (PVR) and not treated with silicone oil and with 4 membranes from eyes with intermediate uveitis. PVR membranes from eyes treated with silicone oil showed a high level of macrophages and a strong expression of HLA-DR. Additionally, lymphocytes were found in PVR membranes, a finding that has not been described before. Similar changes were seen in proliferations removed from eyes affected by uveitis, but these membranes were found to have smaller amounts of extracellular substance. In contrast to this, most cells in the PVR membranes from eyes not treated with silicone oil react with vimentin, GFAP and cytokeratin. In none of these membranes were we able to find T-lymphocytes. It is not possible to say whether or not the different findings are attributable ot the silicone oil.

Topics: Extracellular Matrix; Follow-Up Studies; Glial Fibrillary Acidic Protein; HLA-DR Antigens; Humans; Immunoenzyme Techniques; Keratins; Macrophages; Pigment Epithelium of Eye; Retina; Retinal Detachment; Retinal Neovascularization; Silicone Oils; T-Lymphocytes; Uveitis; Vimentin; Vitrectomy