AB0174 T REGULATORY CELLS LEVEL IN PERIPHERAL BLOOD OF PATIENTS WITH JUVENILE IDIOPATHIC ARTHRITIS AND ITS RELATION WITH DISEASE ACTIVITY
Authors: N. Quilis Marti, P. Mesa del Castillo, M. Andres, O. Juanola, P. Boix, R. Frances
Journal: Annals of the Rheumatic Diseases (2020)

Background: The most important T-cell subtype in maintenance of immune tolerance is T regulatory cells (Treg). These are characterized by CD4 and CD25 receptors on surface, and by showing FoxP3 regulatory factor, which is necessary for maintaining the suppressive activity of Treg cells in peripheral blood (PB). Previous studies have studied Treg cells in PB and synovial fluid in patients with Juvenile Idiopathic Arthritis (JIA). However, there was insufficient evidence to draw robust conclusions about Treg implication in JIA, due to small simple size and variable results across studies. A deeper understanding of regulatory mechanism in JIA may increase comprehension on variability among JIA subtypes and may help to stablish prognosis on the follow up. Objectives: To analyze Treg cells level in PB of JIA patients and its relation with disease activity. Methods: Descriptive, cross-sectional, observational study conducted in a regional reference centre for Pediatric Rheumatology. We included consecutive patients with JIA diagnosed by ILAR criteria. The primary variable was the Treg percentage in PB measured by flow cytometry. To assess JIA activity, we used disease activity indexes (JADAS10, 27, 71 – CRP/ESR and cJADAS), Wallace remission criteria, VAS disease activity by patient/parents and physicians, morning stiffness, multidimensional evaluation (JAMAR) and acute phase reactants (CRP and ESR). Assessment of long-term damage was evaluated with JADI. Association analyses among study variables and Treg levels were performed by Pearson’s correlation coefficient and Mann Whitney’s U test. Results: Ongoing study, we present a preliminary analysis with first 50 JIA patients. Mean age (SD) was 11.3 yr (4.6), being females 60%. Most common JIA subtype was persistent oligoarticular (42%) followed by RFneg polyarticular (24%). 42% patients were treated by csDMARD and 46% by biological agents. Mean levels of CRP and ESR were 0.18 mg/dl (0.3) and 6.3 mm/hr (5.4), respectively. At the time of the study, 84% of patients were in remission (Wallace criteria). Mean of JADAS 27-VSG, JADAS 27-PCR and cJADAS were 3.6 (5.1), 3.7 (5.1), and 3.7 (5.5), respectively. Mean long-term damage scores were 0.48 (1.1) for JADI-A and 0 for JADI-E. Mean levels of Treg cells in PB were 2.11% (1.1). The table shows the association between clinical variables and % of Treg. We can observe a significant, inverse and moderate correlation between Treg levels and disease activity by patient/parents, disability and quality of life (global and the physical component). Close to statistical significance, we found inverse and moderate correlation between Treg cells and all JADAS scores, cJADAS, disease activity by physician and morning stiffness. There was no association between Treg and acute phase reactants. Furthermore, there were no differences in Treg cells in Wallace remission (p=0.692) and regarding use of conventional or biological DMARD (p=0.984 and p=0.386, respectively). Conclusion: According to our preliminary data, higher levels of Treg cells in PB of patients with JIA could be related with lesser disease activity and better quality of life. Larger studies are needed to confirm whether this Treg-mediated regulatory mechanism can have prognostic implication JIA. Variables r p value CRP (mg/dl) -0.24 0.099 ESR (mm/hour) -0.15 0.314 VAS-disease activity (patient / parents) -0.28 0.049 VAS-disease activity (physician) -0.25 0.081 JADAS10 (VSG) -0.27 0.064 JADAS27 (VSG) -0.27 0.064 JADAS71 (VSG) -0.27 0.064 JADAS10 (PCR) -0.28 0.054 JADAS27 (PCR) -0.28 0.054 JADAS71 (PCR) -0.28 0.054 c JADAS10 -0.26 0.065 Disability (JAFS – JAMAR) -0.34 0.021 Quality of lyfe (PRQL – JAMAR) -0.39 0.007 Quality of life physical (PRQLPh – JAMAR) -0.46 0.001 Quality of life psychosocial (PRQLPs-JAMAR) -0.21 0.156 Morning Stiffness -0.27 0.066 Disclosure of Interests: None declared