title: Vitamin D binding protein isoforms as candidate predictors of disease extension in childhood arthritis.
abstract: BACKGROUND
  Juvenile idiopathic arthritis (JIA) comprises a poorly understood group of chronic autoimmune diseases with variable clinical outcomes. We investigated whether the synovial fluid (SF) proteome could distinguish a subset of patients in whom disease extends to affect a large number of joints.
  
  
  METHODS
  SF samples from 57 patients were obtained around time of initial diagnosis of JIA, labeled with Cy dyes and separated by two-dimensional electrophoresis. Multivariate analyses were used to isolate a panel of proteins which distinguish patient subgroups. Proteins were identified using MALDI-TOF mass spectrometry with expression verified by immunochemical methods. Protein glycosylation status was confirmed by hydrophilic interaction liquid chromatography.
  
  
  RESULTS
  A truncated isoform of vitamin D binding protein (VDBP) is present at significantly reduced levels in the SF of oligoarticular patients at risk of disease extension, relative to other subgroups (p<0.05). Furthermore, sialylated forms of immunopurified synovial VDBP were significantly reduced in extended oligoarticular patients (p<0.005).
  
  
  CONCLUSIONS
  Reduced conversion of VDBP to a macrophage activation factor may be used to stratify patients to determine risk of disease extension in JIA patients.
authors: Arthritis Research Group, Queen's University of Belfast, Centre for Infection and Immunity, Health Sciences Building 97 Lisburn Road, Belfast, BT9 7BL, UK. d.gibson@qub.ac.uk
authors: David S
authors: DS
authors: Gibson
authors: Keri
authors: K
authors: Newell
authors: Alexandra N
authors: AN
authors: Evans
authors: Sorcha
authors: S
authors: Finnegan
authors: Gwen
authors: G
authors: Manning
authors: Caitriona
authors: C
authors: Scaife
authors: Catherine
authors: C
authors: McAllister
authors: Stephen R
authors: SR
authors: Pennington
authors: Mark W
authors: MW
authors: Duncan
authors: Terry L
authors: TL
authors: Moore
authors: Madeleine E
authors: ME
authors: Rooney
mesh_terms: D000293:Adolescent; D000595:Amino Acid Sequence; D001171:Arthritis, Juvenile / Q000175:diagnosis* / Q000378:metabolism; D015415:Biomarkers / Q000032:analysis / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008954:Models, Biological; D008969:Molecular Sequence Data; D011379:Prognosis; D020033:Protein Isoforms / Q000032:analysis / Q000378:metabolism / Q000502:physiology; D020543:Proteome / Q000032:analysis / Q000378:metabolism; D013582:Synovial Fluid / Q000737:chemistry / Q000378:metabolism; D014809:Vitamin D-Binding Protein / Q000032:analysis / Q000378:metabolism / Q000502:physiology*
chemical_list: D015415:Biomarkers; D020033:Protein Isoforms; D020543:Proteome; D014809:Vitamin D-Binding Protein