title: Bacterial DNA motifs trigger ANCA production in ANCA-associated vasculitis in remission.
abstract: OBJECTIVE
  CpG motifs, which are highly prevalent in bacterial DNA, have been shown to trigger the production of ANCA in vitro by B lymphocytes from patients with active ANCA-associated vasculitis (AAV). Staphylococcus aureus is associated with relapses in AAV, and CpG motifs from staphylococcal DNA may trigger ANCA production in AAV patients in remission. We investigated the presence of ANCA-producing B lymphocytes during quiescent disease and tested the capacity of these cells to produce ANCA in response to CpG.
  
  
  METHODS
  Expression of Toll-like receptor 9 (TLR9) by B lymphocytes from AAV patients and controls was assessed. Peripheral blood mononuclear cells were isolated from 23 PR3-ANCA and 15 MPO-ANCA patients (33 quiescent, 5 active disease) and 14 healthy controls, and cultured for 12 days in the presence of cytosine-phosphate-guanine oligodeoxynucleotide (CpG-ODN) and IL-2. B-lymphocyte activation, differentiation, immunoglobulin production and in vitro ANCA production were studied.
  
  
  RESULTS
  TLR9 expression by B lymphocytes was comparable in AAV patients and controls. B lymphocytes were activated and differentiated towards a plasma cell phenotype in response to CpG-ODN and IL-2. ANCA were produced in vitro by 13 out of 23 PR3-ANCA patients and 3 out of 15 MPO-ANCA patients.
  
  
  CONCLUSIONS
  We conclude that ANCA-producing B lymphocytes can be present in the peripheral blood of AAV patients during remission. These autoreactive B lymphocytes are triggered by CpG-ODN and IL-2 to produce ANCA in vitro. CpG motifs may trigger the production of ANCA in vivo, contributing to the development of relapses in AAV.
authors.affiliation: Department of Rheumatology and Clinical Immunology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. h.tadema@int.umcg.nl
authors.forename: Henko
authors.initials: H
authors.lastname: Tadema
authors.forename: Wayel H
authors.initials: WH
authors.lastname: Abdulahad
authors.forename: Nikola
authors.initials: N
authors.lastname: Lepse
authors.forename: Coen A
authors.initials: CA
authors.lastname: Stegeman
authors.forename: Cees G M
authors.initials: CG
authors.lastname: Kallenberg
authors.forename: Peter
authors.initials: P
authors.lastname: Heeringa
mesh_terms: D000328:Adult; D000368:Aged; D056648:Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000378:metabolism*; D001402:B-Lymphocytes / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D016022:Case-Control Studies; D002478:Cells, Cultured; D004269:DNA, Bacterial / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D018655:Lymphocyte Count; D008297:Male; D008875:Middle Aged; D009838:Oligodeoxyribonucleotides / Q000494:pharmacology*; D010641:Phenotype; D012008:Recurrence; D012075:Remission, Spontaneous; D013211:Staphylococcus aureus / Q000235:genetics; D051217:Toll-Like Receptor 9 / Q000378:metabolism
chemical_list: D019268:Antibodies, Antineutrophil Cytoplasmic; C408982:CPG-oligonucleotide; D004269:DNA, Bacterial; D007376:Interleukin-2; D009838:Oligodeoxyribonucleotides; D051217:Toll-Like Receptor 9