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A5.30 Systemic Inflammation and B-Cells in Rheumatoid Arthritis
  1. M Blits1,
  2. S Vosslamber1,
  3. J Lubbers1,
  4. S de Ridder1,
  5. AE Oostlander1,
  6. GJ Wolbink3,
  7. D van Schaardenburg3,
  8. MT Nurmohamed2,3,
  9. DM Pegtel1,
  10. CL Verweij1,2
  1. 1Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands
  2. 2Department of Rheumatology, VU University Medical Center, Amsterdam, The Netherlands
  3. 3Department of Rheumatology, Jan van Breemen Research Institute | Reade, Amsterdam, The Netherlands

Abstract

Background and Objectives Rheumatoid arthritis (RA) is heterogeneous in clinical symptoms, clinical parameters, pathogenesis and gene expression levels. Previously, we demonstrated variation in B-cell related gene expression between RA patients. The aim was to explore the relation of B-cell related gene expression to clinical parameters of disease severity in early arthritis (EA) and established RA (esRA).

Methods B-cell related gene expression (B-cell score) was determined in peripheral blood cells of 26 EA and 180 esRA patients, using multiplex real-time PCR. For the EA cohort, B-cell counts were also measured using flow cytometry. The esRA cohort was (randomly) divided into test and validation group of each 90 RA patients, with a mean DAS28 of 5.0 and 5.2, respectively. Associations were assessed between B-cell scores and the clinical disease parameters DAS28, CRP, RF, anti-CCP, nodules and erosions in all cohorts and B-cell counts only in EA cohort. Statistical testing was executed according to a bootstrap method which randomises the esRA group a 1000 times into two equally sized groups.

Results We demonstrated that the B-cell score reflected the peripheral blood B-cell count (p < 0.0001, r = 0.7463). In EA, the B-cell score revealed a significant negative correlation with CRP levels (p = 0.0175; r = –0.4618). In the esRA group we also observed a negative correlation between the B-cell score and CRP levels (p = 0.0006, r = –0.3542; p = 0.0096 after Benjamini-Hochberg multiple testing correction). This result was confirmed in the independent validation group (p = 0.0356; r = –0.2218). Additionally, we performed a randomisation with the bootstrap method, which showed the same significant correlations in almost all cases. However, no correlations were found between B-cell score and DAS28, RF, anti-CCP, nodules or erosions.

Conclusions The B-cell score reflects the B-cell count in RA and a low B-cell count is associated with an increased marker of systemic inflammation in RA.

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