Prevalence of anti-3-nitrotyrosine antibodies in the joint synovial fluid of patients with rheumatoid arthritis, osteoarthritis and systemic lupus erythematosus

Khan, Farzeen; Siddiqui, Akhlaq A.

doi:10.1016/j.cca.2006.01.020

Cited by 75 publications

(51 citation statements)

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“…In mouse models, immunization with class I and class II peptides modified with 3NO 2 Tyr residues elicits stronger immune responses than do the unmodified peptides (16,17). Moreover, the presence of 3NO 2 Tyr-modified proteins has been associated with several autoimmune diseases (10,11,15,(18)(19)(20)(21)(22)(23)(24). Thus, we decided to investigate further the mechanism by which nitration of phenylalanine and Tyr residues can lead to a cross-reactive antibody response to native proteins.…”

mentioning

confidence: 99%

Loss of CD4 T-cell–dependent tolerance to proteins with modified amino acids

Gauba

Grünewald

Gorney

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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The site-specific incorporation of the unnatural amino acid p-nitrophenylalanine (pNO 2 Phe) into autologous proteins overcomes self-tolerance and induces a long-lasting polyclonal IgG antibody response. To determine the molecular mechanism by which such simple modifications to amino acids are able to induce autoantibodies, we incorporated pNO 2 Phe, sulfotyrosine (SO 3 Tyr), and 3-nitrotyrosine (3NO 2 Tyr) at specific sites in murine TNF-α and EGF. A subset of TNF-α and EGF mutants with these nitrated or sulfated residues is highly immunogenic and induces antibodies against the unaltered native protein. Analysis of the immune response to the TNF-α mutants in different strains of mice that are congenic for the H-2 locus indicates that CD4 T-cell recognition is necessary for autoantibody production. IFN-γ ELISPOT analysis of CD4 T cells isolated from vaccinated mice demonstrates that peptides with mutated residues, but not the wild-type residues, are recognized. Immunization of these peptides revealed that a CD4 repertoire exists for the mutated peptides but is lacking for the wild-type peptides and that the mutated residues are processed, loaded, and presented on the I-A b molecule. Overall, our results illustrate that, although autoantibodies are generated against the endogenous protein, CD4 cells are activated through a neo-epitope recognition mechanism. Therefore, tolerance is maintained at a CD4 level but is broken at the level of antibody production. Finally, these results suggest that naturally occurring posttranslational modifications such as nitration may play a role in antibody-mediated autoimmune disorders.loss of tolerance | autologous antibody response | protein nitration P reviously we showed that the site-specific incorporation of the unnatural amino acid p-nitrophenylalanine (pNO 2 Phe) into a protein can induce autoantibodies against the endogenous, unmodified protein (1, 2). The murine proteins TNF-α and retinolbinding protein (RBP4) were modified genetically to incorporate pNO 2 Phe at several surface-exposed positions and were used as immunogens. Vaccination of mice with these altered proteins resulted in an IgG polyclonal antibody response against the endogenous proteins that lasted for at least 40 wk. Experiments involving hybridomas generated from the TNF-α-immunized mice revealed that the IgG antibody response was directed against different regions of the protein and not exclusively against the region containing the pNO 2 Phe residue. The autoantibodies generated by the mutated proteins were tested in an endotoxemia model for their ability to neutralize wild-type TNF-α. Protection from endotoxemia indicated that vaccination with pNO 2 Phemodified self-protein is able to elicit physiologically relevant autoantibody responses. Although these initial studies implicated a role for CD4 T cells in autoantibody production, the exact mechanism by which the site-specific incorporation of pNO 2 Phe breaks immunological self-tolerance remained to be elucidated.Recent studies have indicated that postt...

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confidence: 99%

Loss of CD4 T-cell–dependent tolerance to proteins with modified amino acids

Gauba

Grünewald

Gorney

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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“…Recently, however, there has been increasing evidence regarding the potential immunogenicity of proteins containing a tyrosine-to-nitrotyrosine conversion (19). For example, anti-nitrotyrosine Abs have been identified in the synovial fluid of patients with arthritis (20) and in the serum of patients with systemic lupus erythematosus (20,21) or acute lung injury (22). Previously, we have used an MHC class II-restricted model epitope system (the IE K -restricted epitope of pigeon cytochrome c (PCC)) to investigate whether conversion of tyrosine to 3Ј-nitrotyrosine can have an impact upon epitope recognition by CD4 ϩ T cells (23).…”

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confidence: 99%

Conversion of Tyrosine to the Inflammation-Associated Analog 3′-Nitrotyrosine at Either TCR- or MHC-Contact Positions Can Profoundly Affect Recognition of the MHC Class I-Restricted Epitope of Lymphocytic Choriomeningitis Virus Glycoprotein 33 by CD8 T Cells

Hardy

Wick

Webb

2008

The Journal of Immunology

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Immunohistochemical detection of increased levels of protein-associated nitrotyrosine has become widely used as a surrogate marker of in situ inflammation. However, the potential consequences of protein-associated nitrotyrosine formation in terms of cellular immune recognition has received surprisingly little attention. Using a well-defined I-EK-restricted epitope of pigeon cytochrome c, we previously demonstrated that conversion of a single tyrosine residue to nitrotyrosine can have a profound effect on recognition by CD4 T cells. In this study, we used the MHC class I-restricted epitope of lymphocytic choriomeningitis virus glycoprotein (gp33) to demonstrate that conversion of tyrosine to nitrotyrosine can also profoundly affect recognition of MHC class I-restricted epitopes. Conversion of the Y4 residue of the gp33 epitope to nitrotyrosine completely abrogated recognition by gp33-specific T cells from P14 TCR-transgenic mice. In contrast, CD8+ T cells specific for “nitrated gp33” (NY-gp33) can be readily elicited in C57BL/6 mice after immunization with NY-gp33 peptide. Interestingly, T-T hybridomas specific for NY-gp33 peptide were found to fall into two distinct subsets, being specific for NY-gp33 presented in the context of either H-2Db or H-2Kb. This latter result is surprising in light of previous structural studies showing that Y4 comprises a critical TCR-contact residue when presented by H-2Db but that the same residue points downward into the peptide-binding groove of the MHC when presented by H-2Kb. Together, these results indicate that nitrotyrosine formation can impact T cell recognition both directly, through alteration of TCR-contact residues, or indirectly, through alterations in MHC-contact positions.

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“…Antibodies against 3-nitrotyrosine (3-NT) were found elevated in sera, and synovial fluid of SLE patients. Interestingly, the sera levels were much higher than in synovial fluid (Khan & Siddiqui, 2006).…”

Section: Connective Cells and Tissue As Oxidative Stress Targets In Slementioning

confidence: 84%

“…Nitrated proteins are generated in inflamed tissues by inflammatory cells producing ONOO -, a naturally occurring nitrating agent. A study by Khan & Siddiqui (2006) further investigated the binding characteristics of naturally occurring antibodies to 3-NT present in synovial fluid. Antibodies to 3-NT were found higher in the synovial fluid of RA patients.…”

Section: Ros In Inflammatory Synoviummentioning

confidence: 99%