Background: B cells play an important role in the development and maintenance of rheumatoid arthritis (RA). Although IL-10–producing B cells represent a major subset of regulatory B cells (Bregs) able to suppress autoimmune and inflammatory responses, recent reports showed that B cell-mediated immune suppression may also occur independent of IL-10. For instance, B cells can modulate T cell immune responses through the expression of regulatory molecules such as PD-L1. So far, PD-L1-expressing B cells have not been analyzed in RA patients.Objective: To analyze the frequency of PD-L1-expressing B cells in the peripheral blood of RA patients compared to healthy controls (HC) matched for sex and age, their function on T cell response and their changes in response to therapy.Methods: Fresh peripheral blood B cells from RA patients and HC were characterized by flow cytometry and their functionality assessed in a co-culture system with autologous T cells.Results: The frequencies of CD19+PD-L1+ B cells, CD24hiCD38−PD-L1+ and CD24hiCD38hiPD-L1+ B cells were significantly lower in untreated RA patients than in HC. In a follow-up study, the frequencies of PD-L1+ B cells (CD19+PD-L1+ B cells, CD24hiCD38−PD-L1+ and CD24hiCD38hiPD-L1+ B cells) increased significantly after treatment in good responder patients, although the frequency of total CD24hiCD38hi B cells decreased. CD19+ B cells from untreated RA patients and HC upregulated PD-L1 expression similarly upon stimulation with CpG plus IL-2 and were able to suppress, in vitro, CD8+ T cell proliferation and cytokine production in a PD-L1-dependent manner.Conclusions: Our results show that PD-L1+ B cells exhibiting T cell suppressive capacity are significantly decreased in untreated RA patients but increase in response to successful treatment. PD-L1 expression on B cells from RA patients can be modulated in vitro and PD-L1+ B cells could thus provide new perspectives for future treatment strategies.
Inhibitory receptor expression on T cells from RA patients is inversely correlated with effector T cell function and disease activity and may predict response to treatment. Furthermore, different inhibitory pathways are functional and cooperatively suppress synovial T cells, providing a rationale for new treatment strategies to regulate acute local inflammation.
Objective Most reports on serious infections (SI) in rheumatoid arthritis (RA) patients treated with biological disease-modifying antirheumatic drugs (bDMARDs) are from the USA and Western Europe. Data from other regions are largely missing. We report data from South American countries with different backgrounds and health-care systems but similar registries. Methods We merged 2010-2016 data from two registries, BIOBADABRASIL (Brazil) and BIOBADASAR (Argentina), which share the same protocol, online platform and data monitoring process. Patients with active RA were included when they began the first bDMARD or a conventional synthetic DMARD (csDMARD, control group). The SI incidence rate (IR) per 1000 patient/ years and adjusted IR ratio (aIRR) were estimated for bDMARDs and csDMARDs. Results Data were analysed for 3717 RA patients with an exposure of 13,380 patient/years. The 2591 patients treated with bDMARDs (64% tumour necrosis factor-α inhibitors (TNFi)) had a follow-up of 9300 years, and the 1126 treated with csDMARDs had an exposure of 4081 patient/years. The SI IR was 30.54 (CI 27.18-34.30) for all bDMARDs and 5.15 (CI 3.36-7.89) for csDMARDs. The aIRR between the two groups was 2.03 ([1.05, 3.9] p = 0.034) for the first 6 months of treatment but subsequently increased to 8.26 ([4.32, 15.76] p < 0.001). The SI IR for bDMARDs decreased over time in both registries, dropping from 36.59 (28.41-47.12) in 2012 to 7.27 (4.79-11.05) in 2016. Conclusion While SI remains a major concern in South American patients with RA treated with bDMARDs, a favourable trend toward a reduction was observed in the last years. Key Points • New comprehensive data on biologic drugs safety from international collaboration in South America. • First proposal for national registries data merging in South America. • Serious infections remain a major concern in RA patients treated with biologics. • A significant reduction of serious infections in RA patients exposed to biologics was observed over a 7 years period.
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