title: S-calprotectin (S100A8/S100A9): a potential marker of inflammation in patients with psoriatic arthritis.
abstract: OBJECTIVE
  To analyse levels of S100A8/S100A9 (calprotectin) and selected cytokines, in blood, in patients with psoriatic arthritis (PsA).
  
  
  METHODS
  Sixty-five patients with PsA were examined for clinical manifestations and laboratory measurements of S-calprotectin, ESR, hs-CRP, and selected cytokines. Thirty-two patients had mono-/oligoarthritis and 33 had polyarthritis. S-calprotectin, hs-CRP, and cytokines were measured using ELISA, immunoturbidimetry, and multiplex technology (Bio-Plex). Patients with PsA were compared with 31 healthy controls.
  
  
  RESULTS
  S-calprotectin and hs-CRP levels were significantly higher in patients with PsA compared with controls (P<0.001 and P<0.001, resp.). Patients suffering a polyarthritic disease pattern presented with significantly higher levels of S-calprotectin compared with controls and patients with mono-/oligoarthritis (P<0.001 and P=0.017, resp.). The levels of S-calprotectin correlated with hs-CRP (P<0.001; rs=0.441), swollen joint count (P=0.002, rs=0.397), and CXCL10 (P=0.046, rs=0.678) but not with any of the other cytokines evaluated. In multiple logistic regression analysis, S-calprotectin was the only variable significantly associated with psoriatic arthritis (P=0.002, OR=1.006, 95% CI=1.002-1.010).
  
  
  CONCLUSIONS
  S-calprotectin and hs-CRP levels were significantly higher in patients with PsA. A polyarthritic disease pattern showed higher levels of S-calprotectin than mono-/oligoarthritis. S-calprotectin is considered a potential marker of disease activity in patients with PsA.
authors: Department of Public Health and Clinical Medicine/Rheumatology, Umeå University, 901 87 Umeå, Sweden.
authors: Claes
authors: 0000-0001-5953-3213
authors: C
authors: Hansson
authors: Department of Clinical Microbiology/Clinical Immunology, Umeå University, 901 87 Umeå, Sweden.
authors: Catharina
authors: C
authors: Eriksson
authors: Department of Public Health and Clinical Medicine/Rheumatology, Umeå University, 901 87 Umeå, Sweden.
authors: Gerd-Marie
authors: GM
authors: Alenius
mesh_terms: D000328:Adult; D000368:Aged; D015535:Arthritis, Psoriatic / Q000097:blood* / Q000175:diagnosis / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000378:metabolism; D040501:Calgranulin A / Q000097:blood*; D040502:Calgranulin B / Q000097:blood*; D016022:Case-Control Studies; D054357:Chemokine CXCL10 / Q000097:blood; D005260:Female; D006801:Humans; D007249:Inflammation / Q000097:blood / Q000175:diagnosis / Q000276:immunology; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index
chemical_list: D015415:Biomarkers; C114753:CXCL10 protein, human; D040501:Calgranulin A; D040502:Calgranulin B; D054357:Chemokine CXCL10; D002097:C-Reactive Protein