Characteristics of regulatory B10 cells in patients with rheumatoid arthritis with different disease status

Regulatory B Cells Involvement in Autoimmune Phenomena Occurring in Pediatric Graves' Disease Patients

Graves’s disease is the most common type of autoimmune hyperthyroidism. Numerous studies indicate different factors contributing to the onset of the disease. Despite years of research, the exact pathomechanism of Graves’ disease still remains unresolved, especially in the context of immune response. B cells can play a dual role in autoimmune reactions, on the one hand, as a source of autoantibody mainly targeted in the thyroid hormone receptor (TSHR) and, on the other, by suppressing the activity of proinflammatory cells (as regulatory B cells). To date, data on the contribution of Bregs in Graves’ pathomechanism, especially in children, are scarce. Here, we investigated the frequencies of Bregs before and during a methimazole therapy approach. We reported higher Foxp3+ and IL-10+ Breg levels with CD38- phenotype and reduced numbers of CD38 + Foxp3 + IL-10+ in pediatric Graves’ patients. In addition, selected Breg subsets were found to correlate with TSH and TRAb levels significantly. Noteworthy, certain subpopulations of Bregs were demonstrated as prognostic factors for methimazole therapy outcome. Our data demonstrate the crucial role of Bregs and their potential use as a biomarker in Graves’ disease management.

#CXCR5/CXCL13 pathway, a key driver for migration of regulatory B10 cells, is defective in patients with rheumatoid arthritis

OBJECTIVES

Chemokines (CKs) are key players of immune-cell homing and differentiation. CK receptors (CKRs) can be used to define T-cell functional subsets. We aimed to characterize the CKR profile of the regulatory B-cell subset B10+ cells and investigate the CKs involved in their migration and differentiation in healthy donors (CTLs) and patients with rheumatoid arthritis (RA).

METHODS

RNA sequencing and cytometry were used to compare CKR expression between B10+ and B10neg cells. Migration of B10+ and B10neg cells and interleukin 10 (IL-10) secretion of B cells in response to recombinant CKs or synovial fluid (SF) were assessed.

RESULTS

CXCR5 was expressed at a higher level on the B10+ cell surface as compared with other B cells (referred to as B10neg cells). In line with this, its ligand CXCL13 preferentially attracted B10+ cells over B10neg cells. Interestingly, synovial fluid from RA patients contained high levels of CXCL13 and induced strong and preferential migration of B10+ cells. Besides its role in attracting B10+ cells, CXCL13 also promoted IL-10 secretion by B cells. In RA patients, the level of CXCR5 on B cell surface was reduced. The preferential migration of RA B10+ cells toward CXCL13-rich SF was lost and CXCL13 stimulation triggered less IL-10 secretion than in healthy donors.

CONCLUSION

Our results identify that the CXCR5/CXCL13 axis is essential for B10+ cell biology but is defective in RA. Restoring the preferential migration of B10+ within the affected joints to better control inflammation may be part of therapeutic approach for RA.

Circulating CD19+CD24hiCD38hi regulatory B cells as biomarkers of response to methotrexate in early rheumatoid arthritis

OBJECTIVE

The protagonism of regulatory B cells seems to vary along the course of the disease in murine models of inflammatory conditions. Decreased numbers of circulating regulatory CD19+CD24hiCD38hi transitional (cTr) B cells have been described in patients with long-standing RA, thus our objective was to examine the frequency and evolution of cTr B cells in the peripheral blood of early RA (ERA) patients.

METHODS

Freshly isolated peripheral blood mononuclear cells from 48 steroid- and DMARD-naïve ERA patients with a disease duration of <24 weeks and 48 healthy controls (HCs) were examined by flow cytometry. Co-cultures of isolated memory B cells were established with autologous T cells in the absence or presence of Tr B cells.

RESULTS

As compared with HCs, ERA patients demonstrated an increased frequency of cTr B cells. cTr B cells of ERA patients and HCs displayed an anti-inflammatory cytokine profile and were able to downregulate T cell IFN-γ and IL-21 production, together with ACPA secretion in autologous B/T cell co-cultures. Basal frequencies of cTr B cells above the median value observed in HCs were associated with a good EULAR response to MTX at 12 months [relative risk 2.91 (95% CI 1.37, 6.47)]. A significant reduction of cTr B cells was observed 12 months after initiating MTX, when the cTr B cell frequency was no longer elevated but decreased, and this was independent of the degree of clinical response or the intake of prednisone.

CONCLUSION

An increased frequency of regulatory cTr B cells is apparent in untreated ERA and the baseline cTr B cell frequency is associated with the clinical response to MTX at 12 months.

The role of B regulatory (B10) cells in inflammatory disorders and their potential as therapeutic targets

Over the past decade, studies have identified subset of B cells, which play suppressive functions in additions to the conventional functions of B cells: antigen processing and presentation, activation of T cells and antibody productions. Because of their regulatory function, they were named as B regulatory cells (Bregs). Bregs restrict the severity of autoimmune disorders in animal disease models such as experimental autoimmune myocarditis (EAM), experimental autoimmune encephalitis (EAE), and collagen-induced arthritis (CIA) but can contribute to the development of infection and cancer. In humans, the roles of B regulatory cells in autoimmune diseases have not been clearly established because of the inconsistent findings from many researchers. This is believed to arise from the speculated fact that Bregs lack specific marker, which can be used to identify and characterize them in human diseases. The CD19⁺CD24^hiCD38^hiCD1d^hiB cells have been associated with the regulatory function. Available evidences highlight the relevance of increasing IL-10-producing B cells in autoimmune diseases and the possibility of serving as new therapeutic targets in inflammatory disorders. This review empanels the functions of Bregs in autoimmune diseases in both human and animal models, and further evaluates the possibility of Bregs as therapeutic targets in inflammatory disorders. Consequently, this might help identify possible research gaps, which need to be clarified as researchers speculate the possibility of targeting some subsets of Bregs in the treatment of inflammatory disorders.

Proportion of the CD19-Positive and CD19-Negative Lymphocytes and Monocytes within the Peripheral Blood Mononuclear Cell Set is Characteristic for Rheumatoid Arthritis

Background and objectives: Composition of the peripheral blood (PB) cell populations and their activation state reflect the immune status of a patient. Rheumatoid arthritis (RA) is characterized by abnormal B- and T-cell functions. The objective of this study was to assess the profiles of the PB mononuclear cell (PBMC) populations in patients with rheumatoid and osteoarthritis (OA) in comparison with healthy control (HC) subjects in order to evaluate the PBMC profiles as a potential diagnostic characteristic in RA. The second aim was to assess the CCR1 and CCR2 expression on PB lymphocytes and correlate it with the plasma levels of matrix metallopeptidase 9 (MMP-9), IL-17F, TNF-α, IL-6, and IL-10. Materials and Methods: The frequency and phenotype, including CCR1 and CCR2, of the PBMC populations (monocytes, CD19⁺B cells, and T/NK lymphocytes) in RA (n = 15) and OA (n = 10) patients and HC (n = 12) were analyzed by five-color flow cytometry. DNA of the viruses, HHV-6, HHV-7, and B19, in the whole blood and cell-free plasma, were assessed by nested-polymerase chain reaction (PCR). Results: Active persistent or acute infections, caused by HHV-6, HHV-7, or B19, were not detected in patients of this study. Both CCR1 and CCR2 were determined on the PB B and T/NK lymphocytes in several RA and OA patients and HCs. However, in patients, the frequency of the CCR1-positive T/NK lymphocytes showed a weak negative correlation with the IL-10 level, while the frequency of the CCR2-positive B cells correlated positively with the level of IL-6. Statistically significant differences in the proportions of the CD19-positive and CD19-negative lymphocyte and monocyte subsets within the PBMC set were determined between RA and OA patients and HC adults. Conclusions: We have shown in our pilot study with rather small cohorts of patients that the PBMC-population profiles were very consistent, and statistically significantly differed between RA and OA patients and HC subjects.

Regulatory B cells: New players in inflammatory and autoimmune rheumatic diseases

OBJECTIVE

Regulatory B cells (Bregs) are a new subset of B cells with immunoregulatory functions, mainly through IL-10 production. Bregs suppress inflammatory Th1 and Th17 differentiation and induce Tregs suppressing autoimmune diseases. The aim of the study was to review the literature related to Bregs in autoimmune rheumatic diseases (ARDs).

METHODS

A literature review of publications in PUBMED published in English was performed using the relevant combinations of terms.

RESULTS

All relevant publications are discussed. Overall, recent studies in rheumatic diseases found Bregs to be decreased in ANCA-associated vasculitides (AAV) and in systemic sclerosis (SSc), particularly in SSc-associated lung fibrosis. In AAV Bregs levels are negatively correlated with autoantibody levels whereas in SSc this association is less clear but there is an inverse association with Th1 and Th17 cells. In rheumatoid arthritis (RA), Bregs were decreased, particularly in RA-associated lung fibrosis. In psoriatic arthritis IL-10 + Bregs are decreased and inversely associated with Th1 and Th17 cells. In systemic lupus erythematosus (SLE), the role of Bregs is unclear. In experimental diseases, when Bregs were expanded ex-vivo, they ameliorated established disease.

CONCLUSION

Bregs appear to be a new player in the pathogenesis of ARDs, and may offer a new strategy for therapeutic intervention.