High Degree of Inter-patient Heterogeneity in Synoviocyte Hyperplasia and Immune Cells Infiltration in the Synovium of Juvenile Idiopathic Arthritis Patients

Clément TRIAILLE¹, Cécile BOULANGER², Tatiana SOKOLOVA¹, Laurent MERIC de BELLEFON³, Adrien NZEUSSEU TOUKAP⁴, Christine GALANT⁵, Nisha LIMAYE⁶, Bernard LAUWERYS⁷ and Patrick DUREZ⁸, ¹Pôle de pathologies rhumatismales systémiques et inflammatoires, Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain, Brussels, Belgium, ²Service d’Hématologie, Oncologie et Rhumatologie pédiatrique, Cliniques Universitaires Saint-Luc, Brussels, Belgium, ³Service de Rhumatologie, Cliniques Universitaires Saint-Luc, Brussels, Belgium, ⁴Rheumatology department, Cliniques Universitaires Saint-Luc, Institut de Recherche Expérimentale et Clinique (IREC), Université catholique de Louvain, Brussels, Belgium, ⁵Service d’Anatomie Pathologique, Cliniques Universitaires Saint-Luc, Brussels, Belgium, ⁶Genetics of Autoimmune Diseases and Cancer, de Duve Institute, Université catholique de Louvain, Brussels, Belgium, ⁷UCB Pharma, Brussels, Belgium, ⁸Pôle de Recherche en Rhumatologie, Institut de Recherche Expérimentale et Clinique, Brussels, Belgium

Meeting: ACR Convergence 2021

Keywords: immunology, Juvenile idiopathic arthritis

Session Information

Date: Saturday, November 6, 2021

Session Title: Pediatric Rheumatology – Clinical Poster I: JIA (0241–0265)

Session Type: Poster Session A

Session Time: 8:30AM-10:30AM

Background/Purpose: Increasing evidence indicates that synovial tissue analysis can deliver pathophysiological insights but also individual clinically-relevant information in adult-onset inflammatory arthritides. Little is known about synovial pathology in juvenile idiopathic arthritis, especially regarding inter-patient variability of histopathological features.

To assess the heterogeneity of main synovial features (synoviocyte hyperplasia and immune cells infiltration) in juvenile idiopathic arthritis (JIA) patients and a cohort of young adults (< 30 years old) with early rheumatoid arthritis (RA).

Methods: Synovial biopsies were sampled using needle arthroscopy or ultra-sound (US) guided biopsy during intra-articular joint injection. Tissue was embedded in paraffin then sections were stained with hematoxylin and eosin. Synoviocyte hyperplasia (SH) and immune cells infiltration (ICI) was assessed by an experienced pathologist on a 0 – 3 scale where 0 represents the absence of the feature and 3 the highest level.

Results: 34 JIA patients (age (median ±SD): 15.5±6.47 years, oligo-articular JIA n=28/34, polyarticular JIA n=6/34, ANA-RF-ACPA positivity=56%-10%-3%) and 22 RA (age (median ±SD): 24.3±2.6 years, ANA-RF-ACPA positivity=10%-36%-32%) patients were included. Synovial tissue was obtained from knee (n=49/56), wrist (n=4/56) or metacarpophalangeal/intercarpophalangeal joints (n=3/56), using US guided biopsy in 27% of patients and needle arthroscopy in 73%.

Individual scores of SH and ICI were correlated in both JIA (Spearman’s r=0.503, p value=0.0024) and RA (Spearman’s r=0.636, p value=0.0015). There was no significant difference in SH and ICI scores between the 2 groups (SH score (Q25-Q50-Q75) in JIA= 0.5-1.125-2 and in RA = 0.75-2-2 ; ICI score (Q25-Q50-Q75) in JIA= 1-2-2 and in RA = 0.75-2-2.25). Intra-group variability of the two assessed features was comparable between the 2 groups (SH coefficient of variation: 72.2% for JIA and 68.2% for RA ; ICI coefficient of variation: 52.2% for JIA and 71.2% for RA). Within JIA patients, there was no significant difference in SH/ICI scores between groups based on ANA positivity, oligo or polyarticular involvement nor ongoing treatment.

Conclusion: Studying main histological features of synovitis, we found no difference between JIA and young RA patients. Furthermore, we report a similar degree of inter-patient heterogeneity in synovial pathological features of JIA and RA patients. These variations were not explained by common clinical characteristics. Whether they relate to different molecular signatures as suggested in adult RA will be further investigated using bulk tissue RNA sequencing.

Disclosures: C. TRIAILLE, None; C. BOULANGER, None; T. SOKOLOVA, None; L. MERIC de BELLEFON, None; A. NZEUSSEU TOUKAP, Abbvie, 1, 5, Eli Lilly, 1, 5, Janssen, 1, 5, UCB, 1, 5, Celgene, 1, 5, Pfizer, 1, 5; C. GALANT, None; N. LIMAYE, None; B. LAUWERYS, UCB Pharma, 3; P. DUREZ, Bristol-Myers Squibb, 6, Sanofi, 6, Eli Lilly, 6, Celltrion, 6.

To cite this abstract in AMA style:

TRIAILLE C, BOULANGER C, SOKOLOVA T, MERIC de BELLEFON L, NZEUSSEU TOUKAP A, GALANT C, LIMAYE N, LAUWERYS B, DUREZ P. High Degree of Inter-patient Heterogeneity in Synoviocyte Hyperplasia and Immune Cells Infiltration in the Synovium of Juvenile Idiopathic Arthritis Patients [abstract]. Arthritis Rheumatol. 2021; 73 (suppl 9). https://acrabstracts.org/abstract/high-degree-of-inter-patient-heterogeneity-in-synoviocyte-hyperplasia-and-immune-cells-infiltration-in-the-synovium-of-juvenile-idiopathic-arthritis-patients/. Accessed January 27, 2023.

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