title: Measurement of biomarkers in juvenile idiopathic arthritis patients and their significant association with disease severity: a comparative study.
abstract: OBJECTIVE
  To evaluate in juvenile idiopathic arthritis (JIA) patients a biomarker panel of anti-cyclic citrullinated peptide (anti-CCP) antibodies, cartilage oligomeric matrix protein (COMP), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), IgM rheumatoid factor (RF), IgG RF, and IgA RF and compare to the presence of joint erosions (JE), joint space narrowing (JSN), and synovitis in order to evaluate aggressive disease.
  
  
  METHODS
  Sixty-eight JIA patients (19 RF positive polyarthritis, 23 RF negative polyarthritis, 17 persistent oligoarthritis, and 9 systemic-onset) were evaluated using the biomarker panel and compared to 18 healthy controls. All RF isotypes, anti-CCP antibodies, and COMP were measured by enzyme-linked immunosorbent assays (ELISA). Statistically significant differences and associations were assessed for each biomarker in relation to JE, JSN, and synovitis. Multiple regression analysis was used to find the variables associated with joint damage and synovitis.
  
  
  RESULTS
  Patients with JE and JSN had significantly elevated levels of IgA RF, IgM RF, and anti-CCP antibodies. COMP levels were higher in early disease, but also later in disease in patients with no JE or JSN. ESR, CRP, and IgA RF were significantly elevated in patients with active synovitis. Regression analysis showed IgM RF and disease duration to be associated with JE and JSN. Anti-CCP antibodies and COMP were also associated with JSN. CRP and IgA RF were associated with synovitis.
  
  
  CONCLUSIONS
  Our findings demonstrate the importance of measuring IgM RF and IgA RF by ELISA and anti-CCP antibodies by ELISA, in addition to COMP in the assessment of JIA patients to determine severity of disease.
authors.affiliation: Division of Adult and Pediatric Rheumatology, Department of Internal Medicine and Pediatrics, Saint Louis University School of Medicine, Saint Louis, MO, USA.
authors.forename: B E
authors.initials: BE
authors.lastname: Gilliam
authors.forename: A K
authors.initials: AK
authors.lastname: Chauhan
authors.forename: J M
authors.initials: JM
authors.lastname: Low
authors.forename: T L
authors.initials: TL
authors.lastname: Moore
mesh_terms: D000293:Adolescent; D000328:Adult; D000888:Antibodies, Anti-Idiotypic / Q000097:blood*; D001171:Arthritis, Juvenile / Q000097:blood* / Q000473:pathology; D015415:Biomarkers / Q000097:blood; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000378:metabolism*; D064236:Cartilage Oligomeric Matrix Protein; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D016326:Extracellular Matrix Proteins / Q000097:blood*; D005260:Female; D006023:Glycoproteins / Q000097:blood*; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D008297:Male; D064235:Matrilin Proteins; D010456:Peptides, Cyclic / Q000276:immunology*; D012044:Regression Analysis; D012217:Rheumatoid Factor / Q000097:blood*; D012720:Severity of Illness Index; D013585:Synovitis / Q000097:blood / Q000473:pathology
chemical_list: D000888:Antibodies, Anti-Idiotypic; D015415:Biomarkers; D064236:Cartilage Oligomeric Matrix Protein; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D007070:Immunoglobulin A; D007075:Immunoglobulin M; D064235:Matrilin Proteins; D010456:Peptides, Cyclic; C577553:TSP5 protein, human; C487763:cyclic citrullinated peptide; D002097:C-Reactive Protein; D012217:Rheumatoid Factor