The soluble biomarker calprotectin (an S100 protein) is associated to ultrasonographic synovitis scores and is sensitive to change in patients with rheumatoid arthritis treated with adalimumab.
BACKGROUND
Calprotectin (MRP8/MRP14, S100A8/A9) is associated with disease activity in patients with rheumatoid arthritis (RA). Ultrasonography (US) is a reliable method for evaluation of synovitis (B-mode (BM) and power Doppler (PD)). The present objectives were to explore in RA patients the associations between calprotectin and a comprehensive US examination, as well as the responsiveness of calprotectin compared to other inflammatory markers during anti-TNF treatment.


METHODS
A total of 20 RA patients starting treatment with adalimumab were examined longitudinally by US (BM and PD (semi-quantitative scores 0 to 3) of 78 joints, 36 tendons/tendon groups and 2 bursae) and clinically at baseline and after 1, 3, 6 and 12 months. Associations between the US sum scores and the inflammatory markers calprotectin, serum amyloid A (SAA), CRP and ESR were explored by correlation and linear regression analyses, and the response to treatment was assessed by Standardized Response Mean (SRM).


RESULTS
The inflammatory markers, clinical examinations and US sum scores improved during treatment (P < 0.001). Of the inflammatory markers, calprotectin had the highest correlation coefficients with the total BM and PD sum scores (median (range) 0.59 (0.37 to 0.76) for BM and 0.56 (0.38 to 0.72) for PD). Even higher correlations were found between calprotectin and sum US scores of reduced number of joint counts. Calprotectin made a considerable contribution to total US sum scores in the linear regression analyses (P = 0.001 to 0.031) and among the inflammatory markers, calprotectin had the highest SRM (0.84 at one month).


CONCLUSIONS
Calprotectin was associated with the sum scores from a comprehensive US assessment and was responsive to change during anti-TNF treatment. Thus, examination of this leukocyte protein could be of additional value in the assessment of RA patients on biologic treatment.
Dept of Rheumatology, Diakonhjemmet Hospital, Box 23, 0319 Oslo, Norway. hbham@online.no
Hilde Berner
HB
Hammer
Magne K
MK
Fagerhol
Tale Norbye
TN
Wien
Tore K
TK
Kvien
D000068879:Adalimumab; D000328:Adult; D000368:Aged; D061067:Antibodies, Monoclonal, Humanized / Q000627:therapeutic use*; D018501:Antirheumatic Agents / Q000627:therapeutic use; D001172:Arthritis, Rheumatoid / Q000000981:diagnostic imaging* / Q000276:immunology* / Q000628:therapy; D015415:Biomarkers / Q000378:metabolism; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism* / Q000502:physiology; D039841:Leukocyte L1 Antigen Complex / Q000378:metabolism*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009418:S100 Proteins / Q000378:metabolism*; D012720:Severity of Illness Index; D013585:Synovitis / Q000000981:diagnostic imaging* / Q000276:immunology* / Q000628:therapy; D018608:Ultrasonography, Doppler / Q000379:methods; D055815:Young Adult
D061067:Antibodies, Monoclonal, Humanized; D018501:Antirheumatic Agents; D015415:Biomarkers; D018836:Inflammation Mediators; D039841:Leukocyte L1 Antigen Complex; D009418:S100 Proteins; D000068879:Adalimumab