title: Expression profile of leukocyte genes activated by anti-neutrophil cytoplasmic autoantibodies (ANCA).
abstract: BACKGROUND
  Anti-neutrophil cytoplasmic autoantibodies (ANCA) induce neutrophil activation in vitro with release of injurious products that can mediate necrotizing vasculitis in vivo. The importance of ANCA IgG F(ab')2-antigen binding versus Fcgamma receptor engagement in this process is controversial. We propose that ANCA-antigen binding affects cell signaling pathways that can result in changes of gene expression.
  
  
  METHODS
  Microarray GeneChip analysis and real-time, quantitative PCR (TaqMan(R)) was used to probe for transcripts in leukocytes from patients (in vivo gene expression study) and in leukocytes treated with ANCA IgG or ANCA-F(ab')2 (in vitro gene expression study).
  
  
  RESULTS
  Microarray gene chip analysis showed that ANCA IgG and ANCA-F(ab')2 stimulate transcription of a distinct subset of genes, some unique to whole IgG, some unique to F(ab')2 fragments, and some common to both. DIF-2, COX-2, and IL-8 were identified as genes responsive to ANCA signaling and were selected for in depth evaluation. In vitro DIF-2 and IL-8 were increased by both ANCA IgG and F(ab')2, but COX-2 only by MPO-ANCA F(ab')2. In vivo DIF-2 levels were increased in leukocytes of ANCA patients, which correlated strongly with disease activity and ANCA titer. DIF-2 was not increased in patients in remission or in disease control patients (systemic lupus erythematosus and IgA nephropathy). COX-2 gene expression was significantly increased in patients with active disease, while IL-8 was increased in remission.
  
  
  CONCLUSIONS
  The data indicate that leukocyte genes are activated in vitro by both ANCA Fc and ANCA F(ab')2 pathways and that in vitro activation mimics changes in circulating leukocytes of patients with ANCA disease. Increased levels of DIF-2 in patient leukocytes strongly correlate with severity of disease in kidney tissue. The observations indicate a previously unrecognized role for DIF-2 in ANCA-mediated inflammation, which raises the possibility that DIF-2 has an important role in other types of inflammation.
authors.affiliation: Division of Nephrology, Department of Medicine, The University of North Carolina, Chapel Hill, North Carolina 27599, USA. jjyang@med.unc.edu
authors.forename: Jia Jin
authors.initials: JJ
authors.lastname: Yang
authors.forename: Gloria A
authors.initials: GA
authors.lastname: Preston
authors.forename: David A
authors.initials: DA
authors.lastname: Alcorta
authors.forename: Iwao
authors.initials: I
authors.lastname: Waga
authors.forename: William E
authors.initials: WE
authors.lastname: Munger
authors.forename: Susan L
authors.initials: SL
authors.lastname: Hogan
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Sekura
authors.forename: Brian D
authors.initials: BD
authors.lastname: Phillips
authors.forename: Robin P
authors.initials: RP
authors.lastname: Thomas
authors.forename: J Charles
authors.initials: JC
authors.lastname: Jennette
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Falk
mesh_terms: D019268:Antibodies, Antineutrophil Cytoplasmic / Q000276:immunology*; D051017:Apoptosis Regulatory Proteins; D015267:Churg-Strauss Syndrome / Q000276:immunology; D015870:Gene Expression / Q000276:immunology*; D014890:Granulomatosis with Polyangiitis / Q000276:immunology; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics; D007140:Immunoglobulin Fab Fragments / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D066298:In Vitro Techniques; D008565:Membrane Proteins; D009363:Neoplasm Proteins / Q000235:genetics; D018375:Neutrophil Activation / Q000276:immunology*; D009504:Neutrophils / Q000276:immunology*; D020411:Oligonucleotide Array Sequence Analysis; D013481:Superoxides / Q000378:metabolism; D015533:Transcriptional Activation / Q000276:immunology
chemical_list: D019268:Antibodies, Antineutrophil Cytoplasmic; D051017:Apoptosis Regulatory Proteins; C099815:IER3 protein, human; D017874:Immediate-Early Proteins; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D013481:Superoxides