Rheumatoid arthritis synovial tissue harbours dominant B-cell and plasma-cell clones associated with autoreactivity
- M E Doorenspleet1,2,
- P L Klarenbeek1,2,
- M J H de Hair1,
- B D C van Schaik3,
- R E E Esveldt1,2,
- A H C van Kampen3,4,
- D M Gerlag1,
- A Musters1,
- F Baas5,
- P P Tak1,
- N de Vries1,2
- 1Department of Clinical Immunology & Rheumatology, Academic Medical Center of the University of Amsterdam, Amsterdam, The Netherlands
- 2Department of Experimental Immunology, Academic Medical Center of the University of Amsterdam, Amsterdam, The Netherlands
- 3Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Academic Medical Center of the University of Amsterdam, Amsterdam, The Netherlands
- 4Department of Biosystems Data Analysis, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
- 5Department of Genome Analysis, Academic Medical Center of the University of Amsterdam, Amsterdam, The Netherlands
- Correspondence to Dr N de Vries, Department of Clinical Immunology and Rheumatology, Academic Medical Center/University of Amsterdam, Meibergdreef 9, Room F4-105, Amsterdam 1105 AZ, The Netherlands;
- Received 22 October 2012
- Revised 22 February 2013
- Accepted 29 March 2013
- Published Online First 20 April 2013
Objective To identify potential autoreactive B-cell and plasma-cell clones by quantitatively analysing the complete human B-cell receptor (BCR) repertoire in synovium and peripheral blood in early and established rheumatoid arthritis (RA).
Methods The BCR repertoire was screened in synovium and blood of six patients with early RA (ERA) (<6 months) and six with established RA (ESRA) (>20 months). In two patients, the repertoires in different joints were compared. Repertoires were analysed by next-generation sequencing from mRNA, generating >10 000 BCR heavy-chain sequence reads per sample. For each clone, the degree of expansion was calculated as the percentage of the total number of reads encoding the specific clonal sequence. Clones with a frequency ≥0.5% were considered dominant.
Results Multiple dominant clones were found in inflamed synovium but hardly any in blood. Within an individual patient, the same dominant clones were detected in different joints. The majority of the synovial clones were class-switched; however, the fraction of clones that expressed IgM was higher in ESRA than ERA patients. Dominant synovial clones showed autoreactive features: in ERA in particular the clones were enriched for immunoglobulin heavy chain gene segment V4–34 (IGHV4–34) and showed longer CDR3 lengths. Dominant synovial clones that did not encode IGHV4–34 also had longer CDR3s than peripheral blood.
Conclusions In RA, the synovium forms a niche where expanded—potentially autoreactive—B cells and plasma cells reside. The inflamed target tissue, especially in the earliest phase of disease, seems to be the most promising compartment for studying autoreactive cells.