AB1007 SYSTEMIC JUVENILE IDIOPATHIC ARTHRITIS: ARE DIFFERENT CLINICAL PATTERNS ASSOCIATED WITH S100A8/S100A9 SERUM LEVELS?
Authors: M. G. Villarreal, S. Bonaldi, L. Perez, M. Katsikas
Journal: Annals of the Rheumatic Diseases (2020)

Background: Systemic juvenile idiopathic arthritis (SJIA) is a category of Juvenile Idiopathic Arthritis (JIA). Different clinical patterns (articular/systemic/both of them combined) have been recognized, possibly identifying distinct subpopulations. Serum biomarkers that reflect disease activity include S100A8/S100A9 (S100A8/9), however to date patterns of SJIA and their association with S100A8/9 has not been tested. Objectives: To evaluate S100A8/9 levels in a cohort of patients with SJIA. To determinate S100A8/9 inactive vs inactive visits. To distinguish patterns on SJIA and their association with S100A8/9. To compare serum levels of S100A8/9 with other JIA categories and autoinflammatory diseases. Methods: An unicenter, observational, cross sectional study was conduced. Patients with SJIA according ILAR whom S100A8/9 was measured as part of standard care were enrolled. Consecutive visits were included. Variables recorded were: clinical (systemic: fever, serositis, adenopathy, hepatomegaly, splenomegaly and arthritis); biochemical (S100A8/9, hemoglobin, platelet, erythrosedimentation, c-reactive protein, ferritin). Activity measures: Juvenile Arthritis Disease Activity Score (JADAS -10) and physician visual analogue scale (phy VAS).Visits were divided into active/inactive. Active visit was defined as at least one clinical feature.(systemjc and/or arthritis). Inactive visit no clinical symptoms neither JADAS-10&gt; 1 and phy VAS: 0. SJIA patterns were defined as: “articular pattern”: those patients with arthritis without systemic features, “systemic pattern”: any systemic feature without arthritis, “mixed pattern”: both articular and systemic. Levels of S100A8/9 were tested using Calprotectin Elisa Kit. For comparisons others JIA: enthesitis related arthritis (ERA), polyarticular and autoinflammatory diseases who had at least one S100A8/9 determination were included. Descriptive statistics, Mann- Whitney U test and ANOVA were used as appropiate. Results: Forty-two patients with SJIA were included (25 F). Age at evaluation 13 (1-16.5) years. Clinical features at study baseline: arthritis 57 %, rash 19%, fever 15 %, adenopathies 6%, splenomegaly 4%, hepatomegaly 1.5%. Laboratory features (median): hemoglobin 12.2 gr/dl, platelet 314000 cel/mm3, erythrosedimentation 12.5 mm/h, c-reactive protein 0.7 mg/dl, ferritin 235 ng/ml. JADAS -10 ≥ 1: 62%. Number of active patients were 29 (69%). Scheduled Medical visits were 129 (active 65%, inactive 35%). Active visits were divided according patterns into: articular 54%, mixed 35%, systemic 11%. Serum Levels of S100A8/9 according to SJIA’ patterns. SJIA Overall Active Articular Systemic Mixed Inactive Visits 129 84 46 9 29 45 S100A8/9 ng/ml Median (range) 7590 (300-2625) 16788 (300-26250) 10750 (300-26250) 5200 (850-12250) 25000 (3290-2625) 3103 (1140-1010) S100A8/9 analysis revealed significant differences among active vs inactive medical visits (p: 0,00001). ANOVA test among SJIA`patterns showed, F:86.48, (p:0.00001). Mixed pattern was distinctive to others. S100A8/9 (medians ng/ml) in comparable diseases were: ERA: 4320, polyarticular: 4120, autoinflammatory: 6532. SJIA had the higher S100A8/9. SJIA was different than others comparable diseases (F: 11,62,p: 0.00001). Comparisons among SJIA`patternss and others disease found that systemic and articular pattern did not show differences (F.2.78, p:0.067) Conclusion: S100A8/9 was higher in SJIA compared to others diseases. It reflected disease activity. Mixed pattern evidenced to be different to others (systemic/articular). Mixed pattern was the unique that showed significative difference compared to other diseases. SJIA is probably not a single disease, but not only clinical patterns and biomarkers as S100A8/9, if not, genetic variants and their expression would be able to identify homogeneous groups towards tailored treatments. Disclosure of Interests: None declared