Comparison of gene expression profiles in paired synovial biopsies from rheumatoid arthritis (RA) patients

We explored transcriptomic profiles of paired synovial biopsies from RA patients, in order to assess heterogeneity in synovial tissue at the individual level. Pairwise comparison of transcriptomic profiles showed similar expression of RA-related molecular pathways (TCR signaling, T cell co-stimulation and response to TNF⍺), thereby showing that global molecular alterations in RA synovitis are similar between small and large joints from the same patient. 20 paired biopsies (3 to 5 fragments pooled per biopsy) from 10 RA patients with active disease were analyzed. Synovial biopsies were performed simultaneously in one small and one large joint per patient using needle-arthroscopy for the knee and ultrasound-guided biopsy for the hand or wrist. Synovium from individuals with osteoarthritis was used as controls. Total RNA was hybridized on HGU133 Plus 2.0 arrays.