title: Neutrophil-Related Gene Expression and Low-Density Granulocytes Associated With Disease Activity and Response to Treatment in Antineutrophil Cytoplasmic Antibody-Associated Vasculitis.
abstract: OBJECTIVE
  To discover biomarkers involved in the pathophysiology of antineutrophil cytoplasmic antibody-associated vasculitis (AAV) and to determine whether low-density granulocytes (LDGs) contribute to gene expression signatures in AAV.
  
  
  METHODS
  The source of clinical data and linked biologic specimens was a randomized controlled treatment trial in AAV. RNA sequencing of whole blood from patients with AAV was performed during active disease at the baseline visit and during remission 6 months later. Gene expression was compared between patients who met versus those who did not meet the primary trial outcome of clinical remission at 6 months (responders versus nonresponders). Measurement of neutrophil-related gene expression was confirmed in peripheral blood mononuclear cells (PBMCs) to validate the findings in whole blood. A negative-selection strategy isolated LDGs from PBMC fractions.
  
  
  RESULTS
  Differential expression between responders (n = 77) and nonresponders (n = 35) was detected in 2,346 transcripts at the baseline visit (P < 0.05). Unsupervised hierarchical clustering demonstrated a cluster of granulocyte-related genes, including myeloperoxidase (MPO) and proteinase 3 (PR3). A granulocyte multigene composite score was significantly higher in nonresponders than in responders (P < 0.01) and during active disease than during remission (P < 0.01). This signature strongly overlapped an LDG signature identified previously in lupus (false discovery rate by gene set enrichment analysis <0.01). Transcription of PR3 measured in PBMCs was associated with active disease and treatment response (P < 0.01). LDGs isolated from patients with AAV spontaneously formed neutrophil extracellular traps containing PR3 and MPO.
  
  
  CONCLUSIONS
  In AAV, increased expression of a granulocyte gene signature is associated with disease activity and decreased response to treatment. The source of this signature is likely LDGs, a potentially pathogenic cell type in AAV.
authors.affiliation: National Institute of Arthritis and Musculoskeletal and Skin Diseases, NIH, Bethesda, Maryland.
authors.forename: Peter C
authors.initials: PC
authors.lastname: Grayson
authors.affiliation: National Institute of Arthritis and Musculoskeletal and Skin Diseases, NIH, Bethesda, Maryland.
authors.forename: Carmelo
authors.initials: C
authors.lastname: Carmona-Rivera
authors.affiliation: Immune Tolerance Network, Bethesda, Maryland.
authors.forename: Lijing
authors.initials: L
authors.lastname: Xu
authors.affiliation: Immune Tolerance Network, Bethesda, Maryland.
authors.forename: Noha
authors.initials: N
authors.lastname: Lim
authors.affiliation: Immune Tolerance Network, Bethesda, Maryland.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Gao
authors.affiliation: Immune Tolerance Network, Bethesda, Maryland.
authors.forename: Adam L
authors.initials: AL
authors.lastname: Asare
authors.affiliation: Mayo Clinic Foundation, Rochester, Minnesota.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Specks
authors.affiliation: Massachusetts General Hospital, Boston.
authors.forename: John H
authors.initials: JH
authors.lastname: Stone
authors.affiliation: Johns Hopkins University, Baltimore, Maryland.
authors.forename: Philip
authors.initials: P
authors.lastname: Seo
authors.affiliation: Hospital for Special Surgery, New York, New York.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Spiera
authors.affiliation: Cleveland Clinic Foundation, Cleveland, Ohio.
authors.forename: Carol A
authors.initials: CA
authors.lastname: Langford
authors.affiliation: Cleveland Clinic Foundation, Cleveland, Ohio.
authors.forename: Gary S
authors.initials: GS
authors.lastname: Hoffman
authors.affiliation: University of Groningen, Groningen, The Netherlands.
authors.forename: Cees G M
authors.initials: CG
authors.lastname: Kallenberg
authors.affiliation: Duke University Medical Center, Durham, North Carolina.
authors.forename: E William
authors.initials: EW
authors.lastname: St Clair
authors.affiliation: Immune Tolerance Network, Bethesda, Maryland.
authors.forename: Nadia K
authors.initials: NK
authors.lastname: Tchao
authors.affiliation: Mayo Clinic Foundation, Rochester, Minnesota.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Ytterberg
authors.affiliation: Immune Tolerance Network, Bethesda, Maryland.
authors.forename: Deborah J
authors.initials: DJ
authors.lastname: Phippard
authors.affiliation: University of Pennsylvania, Philadelphia.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Merkel
authors.affiliation: National Institute of Arthritis and Musculoskeletal and Skin Diseases, NIH, Bethesda, Maryland.
authors.forename: Mariana J
authors.initials: MJ
authors.lastname: Kaplan
authors.affiliation: Boston University School of Medicine, Boston, Massachusetts.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Monach
mesh_terms: D000328:Adult; D000368:Aged; D056648:Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D015415:Biomarkers / Q000378:metabolism; D065206:Extracellular Traps / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D005938:Glucocorticoids / Q000627:therapeutic use; D006098:Granulocytes / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D019272:Leukocyte Elastase / Q000235:genetics / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D053146:Myeloblastin / Q000235:genetics / Q000378:metabolism*; D009195:Peroxidase / Q000235:genetics / Q000378:metabolism*; D016032:Randomized Controlled Trials as Topic; D012720:Severity of Illness Index; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D005938:Glucocorticoids; D009195:Peroxidase; D019272:Leukocyte Elastase; D053146:Myeloblastin