Background &Aims: Most Crohn’s disease (CD) patients show seroreactivity against Mycobacterium avium paratuberculosis (MAP), suggesting a pathogenic role for this organism. Our aim was to seek amino acid similari...Background &Aims: Most Crohn’s disease (CD) patients show seroreactivity against Mycobacterium avium paratuberculosis (MAP), suggesting a pathogenic role for this organism. Our aim was to seek amino acid similarities between MAP and intestinal proteins that, through molecular mimicry,could serve as targets for cross-reactive immunity in CD.Methods: Fifty-three peptides comprising 23 sets of MAP/human intestinal peptidyl mimics chosen for maximal homology were constructed and tested for immunologic cross-reactivity by enzyme-linked immunosorbent assay in 50 patients with CD, 50 with ulcerative colitis, and 38 healthy controls. Results: Antibody reactivity was present in only 7 of 23 peptide sets. MAP/self-reactivity in at least 1 of the 7 reactive sets was present in 21 (42%) CD patients but was virtually absent in the controls. Significant double-reactivity was found against MAP glycosyl transferase d (gsd)230-244/human gastrointestinal glutathione peroxidase (GPg)111-125 homologues in 15 of 50 (30%) CD patients; MAP alkyl-ohydroperoxidase C (ahpC)20-34/human tumor overexpressed protein (TOG)637-651 double-reactivity was present in 10 (20%) CD patients, but in none of the controls. Inhibition studies confirmed that simultaneous reactivity to mimics was caused by cross-reactivity. Three-dimensional modeling predicts GPg111-125 will be exposed in a solvent-accessible surface region of the protein compatible with antibody recognition. Antibody affinity was greater for the MAP mimics than for the self-sequences, suggesting that reactivity to the mycobacterial sequences precedes that against self-sequences. Conclusions: We describe MAP/self-mimics as targets of cross-reactive antibody responses characterizing patients with CD. Our findings indicate gastrointestinal glutathione peroxidase as a novel autoantigen in CD.展开更多
Background/Aims CD4+ lymphocytes constitutively expressing the IL-2-receptor α-chain (CD25) regulate the activation of CD4 and CD8 autoreactive T-cells by suppressing their proliferation and effector function. The ai...Background/Aims CD4+ lymphocytes constitutively expressing the IL-2-receptor α-chain (CD25) regulate the activation of CD4 and CD8 autoreactive T-cells by suppressing their proliferation and effector function. The aim of this study is to:(1) measure the percentage of CD4+ CD25+ T-cells (T-regs)in patients with autoimmune liver disease at presentation and during remission, (2) correlate their frequency with disease activity, (3) determine their ability to expand and (4) to inhibit interferon-gamma (IFNγ ) production by CD4+ CD25-T-cells.Methods 41 patients were studied. Percentage of T-regs was determined on peripheral blood mononuclear cells (PBMCs) by triple-colour flow cytometry; their ability to expand by exposing PBMCs to a T-cell expander (CD3/CD28 Dynabeads); their immunoregulatory function by measuring their ability to suppress IFNγ production by CD4+ CD25-T-cells. Results T-regs were significantly less in patients than in controls, and at diagnosis than during remission. Their percentage was inversely correlated with titres of anti-liver kidney microsomal and soluble liver antigen autoantibodies. T-regs ability to expand was significantly lower in patients than in controls, but that to suppress IFNγ production by CD4+ CD25-T-cells was maintained. Conclusions Decreased T-regs numbers and ability to expand may favour the emergence of liver-targeted autoimmunity, despite preserved suppressor function. Treatment should aim at increasing T-regs number.展开更多
文摘Background &Aims: Most Crohn’s disease (CD) patients show seroreactivity against Mycobacterium avium paratuberculosis (MAP), suggesting a pathogenic role for this organism. Our aim was to seek amino acid similarities between MAP and intestinal proteins that, through molecular mimicry,could serve as targets for cross-reactive immunity in CD.Methods: Fifty-three peptides comprising 23 sets of MAP/human intestinal peptidyl mimics chosen for maximal homology were constructed and tested for immunologic cross-reactivity by enzyme-linked immunosorbent assay in 50 patients with CD, 50 with ulcerative colitis, and 38 healthy controls. Results: Antibody reactivity was present in only 7 of 23 peptide sets. MAP/self-reactivity in at least 1 of the 7 reactive sets was present in 21 (42%) CD patients but was virtually absent in the controls. Significant double-reactivity was found against MAP glycosyl transferase d (gsd)230-244/human gastrointestinal glutathione peroxidase (GPg)111-125 homologues in 15 of 50 (30%) CD patients; MAP alkyl-ohydroperoxidase C (ahpC)20-34/human tumor overexpressed protein (TOG)637-651 double-reactivity was present in 10 (20%) CD patients, but in none of the controls. Inhibition studies confirmed that simultaneous reactivity to mimics was caused by cross-reactivity. Three-dimensional modeling predicts GPg111-125 will be exposed in a solvent-accessible surface region of the protein compatible with antibody recognition. Antibody affinity was greater for the MAP mimics than for the self-sequences, suggesting that reactivity to the mycobacterial sequences precedes that against self-sequences. Conclusions: We describe MAP/self-mimics as targets of cross-reactive antibody responses characterizing patients with CD. Our findings indicate gastrointestinal glutathione peroxidase as a novel autoantigen in CD.
文摘Background/Aims CD4+ lymphocytes constitutively expressing the IL-2-receptor α-chain (CD25) regulate the activation of CD4 and CD8 autoreactive T-cells by suppressing their proliferation and effector function. The aim of this study is to:(1) measure the percentage of CD4+ CD25+ T-cells (T-regs)in patients with autoimmune liver disease at presentation and during remission, (2) correlate their frequency with disease activity, (3) determine their ability to expand and (4) to inhibit interferon-gamma (IFNγ ) production by CD4+ CD25-T-cells.Methods 41 patients were studied. Percentage of T-regs was determined on peripheral blood mononuclear cells (PBMCs) by triple-colour flow cytometry; their ability to expand by exposing PBMCs to a T-cell expander (CD3/CD28 Dynabeads); their immunoregulatory function by measuring their ability to suppress IFNγ production by CD4+ CD25-T-cells. Results T-regs were significantly less in patients than in controls, and at diagnosis than during remission. Their percentage was inversely correlated with titres of anti-liver kidney microsomal and soluble liver antigen autoantibodies. T-regs ability to expand was significantly lower in patients than in controls, but that to suppress IFNγ production by CD4+ CD25-T-cells was maintained. Conclusions Decreased T-regs numbers and ability to expand may favour the emergence of liver-targeted autoimmunity, despite preserved suppressor function. Treatment should aim at increasing T-regs number.
