Session Information
Session Type: Abstract Submissions (ACR)
Background/Purpose: Autoreactive B lymphocytes are thought to play an important role in rheumatoid arthritis (RA). B-cell depletion therapy by rituximab (RTX) has shown that targeting B-cells can result in clinical improvement. Unfortunately, the depletion is transient and might result in disease relapse. Hence, analysis of the B-cell/plasma cell compartment in synovium (ST) in patients undergoing RTX therapy might help to identify autoreactive cells responsible for disease persistence and relapse.
Objective: To compare the B-cell/plasma cell repertoire in ST at baseline, 4 weeks and 16 weeks after RTX treatment using a newly developed high-throughput sequencing protocol.
Methods: Eleven RA patients were included and treated with two intravenous infusions of 1000mg RTX without additional methylprednisolone. At baseline, all patients fulfilled ACR criteria for RA, were ACPA+ and had a DAS28score >3.2. At week 24, nine patients demonstrated moderate to good EULAR responses, two patients were marked as non-responders. Immunohistochemistry stainings were performed on formalin-fixed paraffin embedded sections using antibodies against CD22 and CD138. mRNA was isolated from consecutive samples and full-repertoire analysis of the B-cell receptor (BCR) heavy-chain was performed with primers for all V(ariable)-genes. All amplified products encode the CDR3, a unique sequence that defines a unique clone. The number of sequences reflects the amount of BCRs produced by that clone and can be used as a measure for ‘dominance’ of that particular clone. >40,000 bead-bound sequences were analyzed using a Genome Sequencer FLX (Roche/454). Clones with a frequency of >0,5% were arbitrarily considered as dominant clones.
Results: Clones were detected in equal numbers at baseline and 4 weeks after RTX in all patients. However, after 16 weeks the number of dominant clones significantly increased compared to baseline (mean +55,3%, p=0.04). In line, there was a significant decrease in the number of non-dominant clones compared to baseline (mean -47.7%, p=0.03). This mirrored the regression of clinical symptoms measured by the DAS28 score as well as subsequent declines in the number of CD138+ plasma cells in the synovium 16 weeks after the infusion. In 5 patients, 17.9% of the dominant clones at baseline was still detectable after 16 weeks (mean, SD 8.0%), half of these were dominant at both time points (mean 8.8%, SD 4.6%). In the remaining 6 patients dominant clones at baseline were not at all retrieved 16 weeks after RTX. Interestingly, the latter group showed better treatment responses determined by the ΔDAS28score (-0.76 (SD 0.37) and -2.2 (SD 0.79) DAS28 points resp., p=0.005, r2=0.58).
Conclusion: Our observations suggest a disruption of dominant clones and a repopulation of distinctly different clones 16 weeks after rituximab. The persistence of dominant clones was associated with decreased treatment response. Further analysis of clones persistence, amongst others during disease relapse, might help to characterize disease-associated B-cells and/or plasma cells, and identify novel biomarkers for treatment response.
Disclosure:
M. E. Doorenspleet,
None;
P. L. Klarenbeek,
None;
M. J. Boumans,
None;
R. M. Thurlings,
None;
R. E. Esveldt,
None;
B. D. van Schaik,
None;
A. H. van Kampen,
None;
D. M. Gerlag,
None;
F. Baas,
None;
P. P. Tak,
GlaxoSmithKline,
3;
R. M. Plenge,
None;
N. de Vries,
None.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/disruption-of-dominant-b-cell-and-plasma-cell-clones-in-rheumatoid-arthritis-synovium-by-rituximab-correlates-with-treatment-response/