Rheumatoid Arthritis Synovial Tissue Biopsy Study

In this proof-of-concept study, the investigators intend to collect synovial biopsies from MTX-resistant RA patients prior to and 12 weeks after initiation of TNF-blocking therapy (period 1). In addition to conventional histological and immunohistochemistry characterization of the samples, single cell RNASeq studies will be performed, with a particular focus on synovial T cells and fibroblasts. Clinical response to TNF blocking therapies will be assessed using validated measurements, which will result in the identification of novel mechanisms and markers of resistance to TNF inhibition in MTX-resistant RA patients.