Self epitopes shared between human skeletal myosin and Streptococcus pyogenes M5 protein are targets of immune responses in active juvenile dermatomyositis

Abstract

Objective. To identify self T cell epitopes associated with proinflammatory immune responses and clinically active juvenile dermatomyositis (juvenile DM). The target of our search for relevant epitopes was represented by amino acid sequences shared between human skeletal myosin and Streptococcus pyogenes M5 protein. The long-term objective of the project is to identify suitable targets for immunotherapy of the disease.Methods. We used computerized algorithms to identify putative agretopes on both the human myosin and Streptococcus M5 proteins. Direct binding assays for homolog peptides were used to confirm such predictions. Antigenicity and functional cross-reactivity were evaluated by cytotoxicity assays and by measurement of cytokine levels. Specific T cells were isolated by T cell capture, and T cell receptor (TCR) V ␤ gene usage was identified by reverse transcriptase-polymerase chain reaction.Results. We identified peptides that are targets of disease-specific cytotoxic T cell responses. T cell reactivity against the self peptides correlates with clinical signs of early, active myositis. Such reactivity is accompanied by production of proinflammatory cytokines, which may contribute to the damage. T cell crossrecognition of bacterial and human homologs was shown functionally as well as by sorting peptide-specific T cells and identifying oligoclonal and largely overlapping TCR V ␤ gene usage.Conclusion. These findings represent the first identification of a self epitope in juvenile DM, providing a potential candidate for antigen-specific immune therapy.

Epitope-specific immunotherapy induces immune deviation of proinflammatory T cells in rheumatoid arthritis

“…2). Thus, as in the other models tested before, TCC provided a very effective tool to enumerate and characterize dnaJP-specific T cells in PBMCs from patients with RA (22,25,27).…”

“…To address this question directly, we enumerated dnaJP1-specific T cells by TCC, a recently described method, based on aAPCs. We and others (22,(25)(26)(27) showed that these aAPCs can effectively bind low-affinity polyclonal MHC class II-restricted CD3ϩ T cells, thus providing an excellent tool to characterize antigen-specific CD4 ϩ T cells. This task is very difficult to achieve by using state-of-the-art MHC tetramer technology.…”

History of infection before the onset of juvenile dermatomyositis: Results from the National Institute of Arthritis and Musculoskeletal and Skin Diseases Research Registry

“…A streptococcal M protein peptide (aa 367-375) and its myosin homolog (aa 114-122) selectively stimulated JDM lymphocytes (cytotoxic response, increased lymphocyte proliferation, and tumor necrosis factor ␣ production) when JDM peripheral blood mononuclear cells were compared with controls (6); stimulation that is compatible with immune activation (37). In addition, these streptococcal peptides also elicited limited T cell receptor V␤ usage (12,15,18) using a T cell capture analysis (6). Further evidence for an activated immune response compatible with a preceding infection in JDM is obtained from gene expression profiles of muscle of untreated children with JDM, which show an increase in IFN-␣/␤ inducible immune genes (9).…”

Clustering of T Cell Ligands on Artificial APC Membranes Influences T Cell Activation and Protein Kinase C θ Translocation to the T Cell Plasma Membrane

“…Previously, we described artificial APC (aAPC) in which MHCpeptide complexes were randomly distributed within the aAPC membrane (16,17). These aAPC were prepared by inserting affinity-purified MHC molecules containing their transmembrane domain in highly fluid lipid bilayers.…”