ABSTRACT
OBJECTIVE: To identify epitopes on Escherichia coli heat-shock protein (HSP) dnaJ or on homologous human HSP dnaJ involved in the induction/modulation of autoimmune inflammation in patients with oligoarticular juvenile idiopathic arthritis (JIA). METHODS: We used a proliferation assay and cytokine production to evaluate the immune responses of synovial fluid mononuclear cells (SFMCs) to pan-HLA-DR binder peptides derived from either homologous or nonhomologous regions on bacterial and human HSP dnaJ. Cytofluorometric analysis was performed in order to phenotype and sort Treg cells. Sorted cells were then analyzed for the expression of the forkhead box P3 (FoxP3) transcription factor, and their regulatory capacity was tested in coculture assays. RESULTS: T cell responses to E coli HSP dnaJ-derived peptides were eminently proinflammatory. Conversely, peptides derived from human HSP dnaJ induced interleukin-10 (IL-10) production from SFMCs of patients with oligoarticular JIA. A positive correlation was found between disease with a better prognosis (persistent oligoarticular JIA) and recognition of 3 human HSP dnaJ-derived peptides. The recognition of the human peptide H134-148 also induced a significantly greater amount of IL-10 in patients with persistent oligoarticular JIA than in those with extended oligoarticular JIA (P = 0.0012). Incubation of SFMCs from patients with persistent oligoarticular JIA with this human epitope increased the percentage of Treg cells and FoxP3 expression. It also induced the recovery of suppressor activity by Treg cells. CONCLUSION: This is the first description of a self-regulating immune modulator circuit active during autoimmune inflammation through recognition of HSP epitopes with different functional properties. These epitopes induce T cells with regulatory function. Such induction correlates with disease severity and prognosis.
Subject(s)
Arthritis, Juvenile/immunology , Epitopes/immunology , HSP40 Heat-Shock Proteins/immunology , Inflammation/immunology , Molecular Chaperones/immunology , T-Lymphocytes, Regulatory/immunology , Adolescent , Adult , Amino Acid Sequence , Arthritis, Juvenile/pathology , Case-Control Studies , Cells, Cultured , Child , Child, Preschool , Escherichia coli Proteins/analysis , Escherichia coli Proteins/immunology , Forkhead Transcription Factors/metabolism , HSP40 Heat-Shock Proteins/analysis , Humans , Inflammation/pathology , Interleukin-10/metabolism , Molecular Chaperones/analysis , Molecular Sequence Data , Prognosis , Severity of Illness Index , Synovial Fluid/cytology , Synovial Fluid/immunology , T-Lymphocytes, Regulatory/pathologyABSTRACT
OBJECTIVE: To evaluate whether abnormal T cell recognition may be generated by exposure to exogenous antigens presenting sequence homology with epitopes contained in self HLA alleles, and if such recognition may be part of the mechanisms that fuel inflammation in autoimmune diseases associated with certain HLA alleles. METHODS: Cytotoxic responses of peripheral blood mononuclear cells to 9-mer peptides derived from HLA molecules (DRB1*1101, DRB1*0801, or DPB1*0201) associated with oligoarticular juvenile idiopathic arthritis (JIA) or homologous peptides derived from Epstein-Barr virus (EBV) proteins (Bolf1 or Balf2) were analyzed in patients with oligoarticular JIA and in healthy controls matched for HLA-DRB1*1101, DRB1*0801, or DPB1*0201. Production of proinflammatory cytokines in culture supernatants was determined by enzyme-linked immunosorbent assay. RESULTS: T cell cytotoxic responses and production of proinflammatory cytokines in response to stimulation with self HLA-derived peptides were found only in patients with oligoarticular JIA, and not in controls. Patients with oligoarticular JIA, but none of the healthy controls, had EBV-self HLA cross-reactive T cells. CONCLUSION: Our data suggest a disease- and allele-specific mechanism of autoimmunity in oligoarticular JIA. This mechanism may be part of the pathogenesis of the disease, and could be the basis of one of the likely multiple candidates for antigen-specific immunotherapy approaches in the future.
