Activated Peripheral Blood B Cells in Rheumatoid Arthritis and Their Relationship to Anti-Tumor Necrosis Factor Treatment and Response: A Randomized Clinical Trial of the Effects of Anti-Tumor Necrosis Factor on B Cells

Abstract

Objective: B cells can become activated in germinal center (GC) reactions in secondary lymphoid tissue and in ectopic GCs in rheumatoid arthritis (RA) synovium that may be tumor necrosis factor (TNF) and lymphotoxin (LT) dependent. This study was undertaken to characterize the peripheral B cell compartment longitudinally during anti-TNF therapy in RA.

Methods: Participants were randomized in a 2:1 ratio to receive standard dosing regimens of etanercept (n = 43) or adalimumab (n = 20) for 24 weeks. Eligible participants met the American College of Rheumatology 1987 criteria for RA, had clinically active disease (Disease Activity Score in 28 joints >4.4), and were receiving stable doses of methotrexate. The primary mechanistic end point was the change in switched memory B cell fraction from baseline to week 12 in each treatment group.

Results: B cell subsets remained surprisingly stable over the course of the study regardless of treatment group, with no significant change in memory B cells. Blockade of TNF and LT with etanercept compared to blockade of TNF alone with adalimumab did not translate into significant differences in clinical response. The frequencies of multiple activated B cell populations, including CD21- double-negative memory and activated naive B cells, were higher in RA nonresponders at all time points, and CD95+ activated B cell frequencies were increased in patients receiving anti-TNF treatment in the nonresponder group. In contrast, frequencies of transitional B cells-a putative regulatory subset-were lower in the nonresponders.

Conclusion: Overall, our results support the notion that peripheral blood B cell subsets are remarkably stable in RA and not differentially impacted by dual blockade of TNF and LT with etanercept or single blockade of TNF with adalimumab. Activated B cells do associate with a less robust response.

Trial registration: ClinicalTrials.gov NCT00837434.

© 2021, American College of Rheumatology.

Figures

Figure 1.

Flow chart showing deposition of the study participants

Figure 2.. Clinical response at 12 and 24 weeks.

(A) Mean DAS28 at baseline (Wk0), week 12 (Wk12) and week 24 (Wk24) by treatment group included only per-protocol participants, etanercept (n=29 Wk0, n=31 Wk12, n=29 Wk24), adalimumab (n=17 Wk0, n=18 Wk12, n=18 Wk24). Error bars represent standard error of the mean. (B) Clinical responses at 12 weeks (top) and 24 weeks (bottom) by treatment group (etanercept: n=31 Wk12, n=26 Wk24; adalimumab n=18 Wk12 and 24). GR=good responders, MoR=moderate responders, NR=non-responders. The values on the graph represent the mean.

Figure 3.. Core B cell subsets over time.

(A) Scatter plots of frequencies of switched memory (SM), and double negative (DN) of total CD19+ B cells over time, n=49. (B) Line plot of SM, and DN frequencies over time (mean±SEM) in each treatment group. n=18 adalimumab, n=31 etanercept. (C) Scatter plots represent frequencies of SM, and DN over time for non-responders (NR: n=7 Wk0, n=7 Wk12, n=6 Wk24), good responders (GR: n=24 Wk0, n=23 Wk12, n=24 Wk24) and moderate responders (MoR: n=25 Wk0, n=24 Wk12, n=22 Wk24). Error bars depict mean±SEM. All longitudinal comparisons resulted in p-value > 0.05. In 4D, * denote p

Figure 4.. RA responders have lower frequencies of activated memory B cells and more proliferating B cells.

(A) Frequencies of CD95+ SM at baseline (Wk0, n=49), 12 week (Wk12, n=48) and 24 week (Wk24, n=46) compared to healthy controls (HC, n=14). *p

Figure 5.. Frequency of T1/T2 B cells is higher in RA responders at all time points.

(A) Scatter plot showing frequencies of T1/T2 B cells in all participants (n= 56 Wk0, n=54 Wk12, n=52 Wk24) regardless of treatment over time in comparison to healthy controls (HC, n=20). Frequencies of T3 B cells are shown in the right scatter plot comparing HC (n=20) to all participants (n= 49 Wk0, n=48 Wk12, n=46 Wk24) over time. (B) Scatter plots demonstrate frequencies of T1/T2 B cells time in Good responder (GR: n=24 Wk0, n=24 Wk12, n=23 Wk24), moderate responder (MoR: n=24 Wk0, n=23 Wk12, n=21 Wk24) and non-responders (NR: n=7 Wk0, n=7 Wk12, n=6 Wk24) and T3 B cells over time in Good responder (GR: n=24 Wk0, n=23 Wk12, n=23 Wk24), moderate responder (MoR: n=24 Wk0, n=23 Wk12, n=21 Wk24) and non-responders (NR: n=7 Wk0, n=7 Wk12, n=6 Wk24). Mean±SEM. All comparisons resulted in p-values > 0.05. The values on the graph represent the mean.