Synovial cellular and molecular signatures stratify clinical response to csDMARD therapy and predict radiographic progression in early rheumatoid arthritis patients.

OBJECTIVES: To unravel the hierarchy of cellular/molecular pathways in the disease tissue of early, treatment-naïve rheumatoid arthritis (RA) patients and determine their relationship with clinical phenotypes and treatment response/outcomes longitudinally. METHODS: 144 consecutive treatment-naïve early RA patients (<12 months symptoms duration) underwent ultrasound-guided synovial biopsy before and 6 months after disease-modifying antirheumatic drug (DMARD) initiation. Synovial biopsies were analysed for cellular (immunohistology) and molecular (NanoString) characteristics and results compared with clinical and imaging outcomes. Differential gene expression analysis and logistic regression were applied to define variables correlating with treatment response and predicting radiographic progression. RESULTS: Cellular and molecular analyses of synovial tissue demonstrated for the first time in early RA the presence of three pathology groups: (1) lympho-myeloid dominated by the presence of B cells in addition to myeloid cells; (2) diffuse-myeloid with myeloid lineage predominance but poor in B cells nd (3) pauci-immune characterised by scanty immune cells and prevalent stromal cells. Longitudinal correlation of molecular signatures demonstrated that elevation of myeloid- and lymphoid-associated gene expression strongly correlated with disease activity, acute phase reactants and DMARD response at 6 months. Furthermore, elevation of synovial lymphoid-associated genes correlated with autoantibody positivity and elevation of osteoclast-targeting genes predicting radiographic joint damage progression at 12 months. Patients with predominant pauci-immune pathology showed less severe disease activity and radiographic progression. CONCLUSIONS: We demonstrate at disease presentation, prior to pathology modulation by therapy, the presence of specific cellular/molecular synovial signatures that delineate disease severity/progression and therapeutic response and may pave the way to more precise definition of RA taxonomy, therapeutic targeting and improved outcomes.

A Multicenter Retrospective Analysis Evaluating Performance of Synovial Biopsy Techniques in Patients With Inflammatory Arthritis: Arthroscopic Versus Ultrasound-Guided Versus Blind Needle Biopsy.

OBJECTIVE: To evaluate whether the choice of synovial biopsy technique (arthroscopy, blind needle [BN] biopsy, ultrasound [US]-guided portal and forceps [P&F], or US-guided needle biopsy [NB]) translates to significant variation in synovial tissue quality and quantity, with the aim of informing recommendations for the choice of synovial sampling technique within clinical trials. METHODS: In total, 159 procedures from 5 academic rheumatology centers were evaluated. Hematoxylin and eosin-stained, paraffin-embedded synovial tissue sections from patients with inflammatory arthritis were assessed in order to determine the proportion of graded synovial fragments, total area of graded synovial tissue, and synovitis score per procedure. RNA quantity (µg of RNA) and quality (RNA integrity number) per procedure were also assessed in the synovial samples. RESULTS: In this study, 84 of the 159 procedures performed on large joints at baseline (25 arthroscopic, 35 US-P&F, 11 US-NB, and 13 BN biopsies), 41 of the 159 procedures performed on small joints at baseline (11 US-P&F, 20 US-NB, and 10 BN biopsies), and 34 sequential biopsy procedures were evaluated. Compared to all other techniques evaluated in the small and large joints, fewer small joint BN biopsies and a significantly lower proportion of large joint BN biopsies yielded graded synovial tissue. No significant difference in either the proportion of graded tissue samples or total graded synovial tissue area between the US-NB and arthroscopic large joint procedures was demonstrated. Among the sequential biopsy procedures evaluated (small joint US-NB, large joint arthroscopy, US-P&F biopsy, and BN biopsy), no significant difference in the proportion of graded synovial tissue or total graded synovial tissue area was demonstrated. All procedures yielded RNA of significant quality and quantity for subsequent transcriptomic analysis. CONCLUSION: These data support the integration of US-guided methods along with arthroscopic biopsy for clinical trial protocols in which sequential sampling of synovium from the large and small joints is needed for both histologic and molecular analysis. BN biopsy may be considered if graded synovial tissue is not required for subsequent analyses.

Use of ultrasound-guided small joint biopsy to evaluate the histopathologic response to rheumatoid arthritis therapy: recommendations for application to clinical trials.

OBJECTIVE: To examine in a cohort of rheumatoid arthritis (RA) patients undergoing serial ultrasound (US)-guided biopsies of small joints in the context of clinical trials whether sufficient synovial tissue could be obtained at both baseline and second biopsy to: 1) accurately evaluate the synovial immune phenotype, 2) permit adequate RNA extraction to determine molecular signatures, and 3) sensitively detect change in the number of synovial sublining macrophages (CD68+) following effective therapy. METHODS: Synovial samples from RA patients undergoing US-guided biopsy of small joints as part of 2 clinical trials (Barts Early Arthritis Cohort [n = 18] and the Clinical and Pathological Response to Certolizumab Pegol (CLIP-Cert) study [n = 17]) were examined, and the quality and quantity of histologic samples and RNA extracted per joint were determined and compared to synovial thickness and power Doppler scores determined by US before biopsy. Modulation of the number of CD68+ sublining macrophages was correlated with clinical response to treatment. RESULTS: Good quality synovial tissue that accurately reflected the synovial immune phenotype of the total joint was obtained in 80% of US-guided procedures when synovial thickness (higher than grade 2) was documented before biopsy. In 100% of the procedures, sufficient RNA was extracted to permit molecular analysis. There was a significant correlation between change in CD68+ sublining macrophage number and clinical response to treatment. CONCLUSION: This study provides minimum standards for sample retrieval for small joint biopsy. Furthermore, our findings confirm the clinical utility of the procedure in the largest reported cohort of US-guided small joint biopsies. The demonstration that small joint synovial tissue can be readily accessed by a technically simple, minimally invasive procedure is likely to facilitate critical advancements in the knowledge of RA pathobiology and personalized health care.