BAFF upregulates CD28/B7 and CD40/CD154 expression and promotes mouse T and B cell interaction in vitro via BAFF receptor

Expression of USP25 associates with fibrosis, inflammation and metabolism changes in IgG4-related disease

IgG4-related disease (IgG4-RD) has complex clinical manifestations ranging from fibrosis and inflammation to deregulated metabolism. The molecular mechanisms underpinning these phenotypes are unclear. In this study, by using IgG4-RD patient peripheral blood mononuclear cells (PBMCs), IgG4-RD cell lines and Usp25 knockout mice, we show that ubiquitin-specific protease 25 (USP25) engages in multiple pathways to regulate fibrotic and inflammatory pathways that are characteristic to IgG4-RD. Reduced USP25 expression in IgG4-RD leads to increased SMAD3 activation, which contributes to fibrosis and induces inflammation through the IL-1β inflammatory axis. Mechanistically, USP25 prevents ubiquitination of RAC1, thus, downregulation of USP25 leads to ubiquitination and degradation of RAC1. Decreased RAC1 levels result in reduced aldolase A release from the actin cytoskeleton, which then lowers glycolysis. The expression of LYN, a component of the B cell receptor signalosome is also reduced in USP25-deficient B cells, which might result in B cell activation deficiency. Altogether, our results indicate a potential anti-inflammatory and anti-fibrotic role for USP25 and make USP25 a promising diagnostic marker and potential therapeutic target in IgG4-RD.

Role of serum B-cell-activating factor and interleukin-17 as biomarkers in the classification of interstitial pneumonia with autoimmune features

Interstitial pneumonia with autoimmune features (IPAF) is a type of interstitial lung disease (ILD) with immune features that do not meet the diagnostic criteria for specific connective tissue diseases (CTDs). This retrospective case-control study investigated the role of serum B-cell-activating factor of the tumor necrosis factor family (BAFF) and interleukin (IL)-17 as biomarkers for IPAF. The differences in serum BAFF, IL-17, and IL-10 were compared among patients with idiopathic pulmonary fibrosis (IPF), IPAF, ILD associated with CTD (CTD-ILD), and healthy controls. The patients were treatment naïve. The correlations of BAFF with IL-10, IL-17, and pulmonary function were analyzed. The classifiable value of BAFF for IPAF was examined. The results showed that the serum levels of BAFF and IL-17 in the IPAF and CTD-ILD groups were higher than in the IPF group. High BAFF levels and high predicted diffusion capacity of the lungs for carbon monoxide (DLCO) were independent predictive factors for IPAF vs IPF. In the IPAF and CTD-ILD groups, serum BAFF levels were negatively correlated with predicted values of forced vital capacity (FVC%) and diffusing capacity of the lungs for carbon monoxide (DLCO%) and positively correlated with serum IL-17 and IL-10 levels. The cutoff value of combined BAFF and IL-17 was 0.704, and the sensitivity and specificity for classifying IPAF were 78.9 and 95.7%, respectively. In conclusion, combining serum BAFF and IL-17 as a biomarker may have classifiable value in differentiating IPAF from other forms of ILD.

BAFF deficiency aggravated optic nerve crush-induced retinal ganglion cells damage by regulating apoptosis and neuroinflammation via NF-κB-IκBα signaling

Loss of retinal ganglion cells (RGCs) is a primary cause of visual impairment in glaucoma, the pathological process is closely related to neuroinflammation and apoptosis. B-cell activating factor (BAFF) is a fundamental survival factor mainly expressed in the B cell lineage. Evidence suggests its neuroprotective effect, but the expression and role in the retina have not yet been investigated. In this study, we adopt optic nerve crush (ONC) as an in vivo model and oxygen-glucose deprivation/reoxygenation (OGD/R) of RGCs as an in vitro model to investigate the expression and function of BAFF. We found that BAFF and its receptors were abundantly expressed in the retina and BAFF inhibition exacerbated the caspase 3-mediated RGCs apoptosis, glial cell activation and pro-inflammatory cytokines expression, which may be caused by the activation of the NF-κB pathway in vivo. In addition, we found that BAFF treatment could alleviate RGCs apoptosis, pro-inflammatory cytokines expression and NF-κB pathway activation, which could be reversed the effect by blockade of the NF-κB pathway in vitro. Meanwhile, we found that microglia induced to overexpress BAFF in the inflammatory microenvironment in a time-dependent manner. Taken together, our results indicated that BAFF deficiency promoted RGCs apoptosis and neuroinflammation through activation of NF-κB pathway in ONC retinas, suggesting that BAFF may serve as a promising therapeutic target for the treatment of glaucoma.

BAFFR expression in circulating T follicular helper (CD4+CXCR5+PD-1+) and T peripheral helper (CD4+CXCR5-PD-1+) cells in systemic lupus erythematosus

BACKGROUND

Circulating T follicular helper (cTfh) and T peripheral helper (Tph) subpopulations are shown to be higher in systemic lupus erythematosus (SLE) patients and have been involved in promoting extrafollicular B cell responses. However, a possible association with the B cell activating factor (BAFF), a cytokine mainly related to B cell responses and disease activity in SLE, has not been investigated. Therefore, this study aimed to evaluate the association of cTfh and Tph subpopulations with the BAFF system expression and clinical activity in SLE patients.

METHODS

This study included 43 SLE patients and 12 healthy subjects (HS). The identification of cTfh (CD4+CXCR5+PD-1+), Tph (CD4+CXCR5-PD-1+) cells, expression of membrane-bound BAFF (mBAFF), BAFFR, TACI, BCMA, and intracellular IL-21 was performed by flow cytometry. Serum levels of IL-21, CXCL13, and BAFF were analyzed using ELISA. The SLEDAI-2K score was used to evaluate disease activity in SLE patients.

RESULTS

Compared with HS, SLE patients showed a significantly increased percentage of cTfh and Tph cells, higher in patients with clearly active disease. SLE patients had markedly higher IL-21-producing cTfh and Tph cells than HS. Both subpopulations were positively correlated with the disease activity in SLE patients. Tph cells were negatively correlated with CD19+CXCR5+ B cells and positively correlated with CD19+CXCR5- B cells. A low expression of mBAFF and their receptors TACI and BCMA was found on cTfh and Tph cells in SLE patients and HS. However, SLE patients with clearly active disease showed decreased expression of BAFFR on cTfh and Tph subpopulations than patients with mildly active/nonactive disease. Serum IL-21, CXCL13, and BAFF levels were higher in SLE patients than in HS. Levels of CXCL13 were correlated with disease activity. Non-significant correlations were observed among T cell subpopulations and IL-21, CXCL13, and BAFF levels.

CONCLUSIONS

This study emphasizes the importance of cTfh and Tph cells in SLE pathogenesis. Besides the importance of IL-21, our results suggest that BAFFR could play a role in cTfh and Tph subpopulations in the autoimmunity context.

Aberrant B Cell Signaling in Autoimmune Diseases

Aberrant B cell signaling plays a critical in role in various systemic and organ-specific autoimmune diseases. This is supported by genetic evidence by many functional studies in B cells from patients or specific animal models and by the observed efficacy of small-molecule inhibitors. In this review, we first discuss key signal transduction pathways downstream of the B cell receptor (BCR) that ensure that autoreactive B cells are removed from the repertoire or functionally silenced. We provide an overview of aberrant BCR signaling that is associated with inappropriate B cell repertoire selection and activation or survival of peripheral B cell populations and plasma cells, finally leading to autoantibody formation. Next to BCR signaling, abnormalities in other signal transduction pathways have been implicated in autoimmune disease. These include reduced activity of several phosphates that are downstream of co-inhibitory receptors on B cells and increased levels of BAFF and APRIL, which support survival of B cells and plasma cells. Importantly, pathogenic synergy of the BCR and Toll-like receptors (TLR), which can be activated by endogenous ligands, such as self-nucleic acids, has been shown to enhance autoimmunity. Finally, we will briefly discuss therapeutic strategies for autoimmune disease based on interfering with signal transduction in B cells.

BAFF, involved in B cell activation through the NF-κB pathway, is related to disease activity and bone destruction in rheumatoid arthritis

B cell activating factor of TNF family (BAFF) is a member of TNF ligand superfamily and plays a key role in B cell homeostasis, proliferation, maturation, and survival. In this study, we detected BAFF level, the expressions of BAFF receptors and important molecules in NF-κB pathway in rheumatoid arthritis (RA) patients and analyzed the correlation between BAFF level and clinical variables, laboratory parameters or X-ray scores in order to elucidate the roles of BAFF in RA. A total of 50 RA patients and 50 healthy controls (HCs) were enrolled. We showed that the serum BAFF level in RA patients was significantly higher than that of HCs, and the percentages of B cell subsets (CD19⁺ B cells, CD19⁺CD27⁺ B cells, CD19⁺CD20⁺CD27⁺ B cells, and CD19⁺CD20^-CD27⁺ B cells) in the serum of RA patients were significantly increased compared with those of HCs. The percentages of CD19⁺BAFFR⁺ B cells, CD19⁺ BCMA⁺ B cells, and CD19⁺ TACI⁺ B cells in RA patients were significantly increased compared with those in HCs. The expression of important molecules in the NF-κB pathway (MKK3, MKK6, p-P38, p-P65, TRAF2, and p52) was significantly higher in RA patients than in HCs, but p100 level in RA patients was lower than that in HCs. The serum BAFF level was positively correlated with C-reactive protein, rheumatoid factor, disease activity score (in 28 joints), swollen joint counts, tender joint counts, and X-ray scores. When normal B cells were treated with BAFF in vitro, the percentages of the B cell subset and the expression of BAFF receptors were significantly upregulated. BAFF also promoted the expression of MKK3, MKK6, p-P38, p-P65, TRAF2, and p52. In conclusion, this study demonstrates that BAFF level is correlated with the disease activity and bone destruction of RA. BAFF is involved in the differentiation, proliferation, and activation of B cells in RA through NF-κB signaling pathway, suggesting that BAFF might be an ideal therapeutic target for RA.

Targeting Bruton's Tyrosine Kinase in Inflammatory and Autoimmune Pathologies

Bruton's tyrosine kinase (BTK) was discovered due to its importance in B cell development, and it has a critical role in signal transduction downstream of the B cell receptor (BCR). Targeting of BTK with small molecule inhibitors has proven to be efficacious in several B cell malignancies. Interestingly, recent studies reveal increased BTK protein expression in circulating resting B cells of patients with systemic autoimmune disease (AID) compared with healthy controls. Moreover, BTK phosphorylation following BCR stimulation in vitro was enhanced. In addition to its role in BCR signaling, BTK is involved in many other pathways, including pattern recognition, Fc, and chemokine receptor signaling in B cells and myeloid cells. This broad involvement in several immunological pathways provides a rationale for the targeting of BTK in the context of inflammatory and systemic AID. Accordingly, numerous in vitro and in vivo preclinical studies support the potential of BTK targeting in these conditions. Efficacy of BTK inhibitors in various inflammatory and AID has been demonstrated or is currently evaluated in clinical trials. In addition, very recent reports suggest that BTK inhibition may be effective as immunosuppressive therapy to diminish pulmonary hyperinflammation in coronavirus disease 2019 (COVID-19). Here, we review BTK's function in key signaling pathways in B cells and myeloid cells. Further, we discuss recent advances in targeting BTK in inflammatory and autoimmune pathologies.

Permissive selection followed by affinity-based proliferation of GC light zone B cells dictates cell fate and ensures clonal breadth

Affinity maturation depends on how efficiently germinal centers (GCs) positively select B cells in the light zone (LZ). Positively selected GC B cells recirculate between LZs and dark zones (DZs) and ultimately differentiate into plasmablasts (PBs) and memory B cells (MBCs). Current understanding of the GC reaction presumes that cMyc-dependent positive selection of LZ B cells is a competitive affinity-dependent process; however, this cannot explain the production of GC-derived lower-affinity MBCs or retention of GC B cells with varied affinities. Here, by combining single-cell/bulk RNA sequencing and flow cytometry, we identified and characterized temporally and functionally distinct positively selected cMyc⁺ GC B cell subpopulations. cMyc⁺ LZ B cell subpopulations enriched with either higher- or lower-affinity cells diverged soon after permissive positive selection. The former subpopulation contained PB precursors, whereas the latter comprised less proliferative MBC precursors and future DZ entrants. The overall affinity of future DZ entrants was enhanced in the LZ through preferential proliferation of higher-affinity cells. Concurrently, lower-affinity cells were retained in GCs and protected from apoptosis. These findings redefine positive selection as a dynamic process generating three distinct B cell fates and elucidate how positive selection ensures clonal diversity for broad protection.

Positive Selection in the Light Zone of Germinal Centers

Germinal centers (GCs) are essential sites for the production of high-affinity antibody secreting plasma cells (PCs) and memory-B cells (MBCs), which form the framework of vaccination. Affinity maturation and permissive selection in GCs are key for the production of PCs and MBCs, respectively. For these purposes, GCs positively select “fit” cells in the light zone of the GC and instructs them for one of three known B cell fates: PCs, MBCs and persistent GC-B cells as dark zone entrants. In this review, we provide an overview of the positive selection process and discuss its mechanisms and how B cell fates are instructed.

Innate Lymphoid Cells and Adaptive Immune Cells Cross-Talk: A Secret Talk Revealed in Immune Homeostasis and Different Inflammatory Conditions

The inflammatory immune response has evolved to protect the host from different pathogens, allergens, and endogenous death or damage-associated molecular patterns. Both innate and adaptive immune components are crucial in inducing an inflammatory immune response depending on the stimulus type and its duration of exposure or the activation of the primary innate immune response. As the source of inflammation is removed, the aggravated immune response comes to its homeostatic level. However, the failure of the inflammatory immune response to subside to its normal level generates chronic inflammatory conditions, including autoimmune diseases and cancer. Innate lymphoid cells (ILCs) are newly discovered innate immune cells, which are present in abundance at mucosal surfaces, including lungs, gastrointestinal tract, and reproductive tract. Also, they are present in peripheral blood circulation, skin, and lymph nodes. They play a crucial role in generating the pro-inflammatory immune response during diverse conditions. On the other hand, adaptive immune cells, including different types of T and B cells are major players in the pathogenesis of autoimmune diseases (type 1 diabetes mellitus, rheumatoid arthritis, psoriasis, and systemic lupus erythematosus, etc.) and cancers. Thus the article is designed to discuss the immunological role of different ILCs and their interaction with adaptive immune cells in maintaining the immune homeostasis, and during inflammatory autoimmune diseases along with other inflammatory conditions (excluding pathogen-induced inflammation), including cancer, graft-versus-host diseases, and human pregnancy.

Tolerogenic Dendritic Cells Generated by BAFF Silencing Ameliorate Collagen-Induced Arthritis by Modulating the Th17/Regulatory T Cell Balance

Tolerogenic dendritic cells (tolDCs) have received much attention because of their capacity to restore immune homeostasis. RNA interference techniques have been used in several studies to generate tolDCs by inactivating certain molecules that regulate DC maturation and immunologic function. BAFF is a key B cell survival factor that is not only essential for B cell function but also T cell costimulation, and DCs are the major source of BAFF. In this study, we determined whether BAFF gene silencing in mature DCs could lead to a tolerogenic phenotype as well as the potential therapeutic effect of BAFF-silenced DCs on collagen-induced arthritis (CIA) in mice. Meanwhile, CRISPR/Cas9-mediated BAFF^-/- DC2.4 cells were generated to verify the role of BAFF in DC maturation and functionality. BAFF-silenced DCs and BAFF^-/- DC2.4 cells exhibited an immature phenotype and functional state. Further, the transplantation of BAFF-silenced DCs significantly alleviated CIA severity in mice, which correlated with a reduction in Th17 populations and increased regulatory T cells. In vitro, BAFF-silenced DCs promoted Foxp3 mRNA and IL-10 expression but inhibited ROR-γt mRNA and IL-17A expression in CD4⁺ T cells. Together, BAFF-silenced DCs can alleviate CIA, partly by inducing Foxp3⁺ regulatory T cells and suppressing Th17 subsets. Collectively, BAFF plays an important role in interactions between DCs and T cells, which might be a promising genetic target to generate tolDCs for autoimmune arthritis treatment.

B-Cell Activating Factor Predicts Acute Rejection Risk in Kidney Transplant Recipients: A 6-Month Follow-Up Study

B cell activating factor (BAFF) belonging to TNF family is a cytokine that enhances B-cell proliferation and differentiation. Recently, It has been suggested that BAFF might be a potential therapeutic target for treating autoimmune disease. However, the relationship between BAFF and allograft rejection is controversial, and the clinical significance of BAFF in predicting allograft rejection need to be further explored. We conducted 6-month follow-up study to confirm the hypothesis that BAFF might be a risk factor for predicting acute rejection in kidney transplant recipients. At the end of the study, a total of 155 kidney transplant recipients were recruited from October 2015 to October 2017, and classified into acute rejection group (n = 34) and stable renal function group (n = 121) according to their clinical course. We demonstrate that the serum BAFF levels when acute rejection occurred was significantly higher than that in the stable renal function group (2426.19 ± 892.19 vs. 988.17 ± 485.63 pg/mL, P < 0.05). BAFF expression was significantly enhanced in the membrane and cytoplasm of renal tubule epithelial cells in the transplant kidney tissue with acute rejection, and a positive correlation between BAFF and C4d expression was also observed (r = 0.880, P = 0.001). ROC analyses highlight the superiority of serum BAFF level before transplant over those on other post-transplant days in prediction of acute rejection episodes. The sensitivity, specificity and AUC (area under curve) were 83.3, 89.5, and 0.886%, respectively. Kaplan-Meier survival analysis showed that recipients with higher pretransplant BAFF levels had higher acute rejection incidence (P = 0.003). In conclusion, we have identified that BAFF levels are associated with the acute rejection and could be a promising biomarker to predict kidney transplant rejection risks.

BAFF promotes T cell activation through the BAFF-BAFF-R-PI3K-Akt signaling pathway

B-cell activating factor from the tumor necrosis factor family (BAFF) has revealed its critical role in B cell proliferation and survival, as well as the pathogenesis of T-cell mediated autoimmune disease. However, the effect and molecular mechanisms of BAFF on T cell physiological function have not been fully elucidated. In this study it was seen that BAFF can promote the vitality of purified T cells, increase the proportion of CD3⁺CD4⁺, CD4⁺CD25⁺, CD4⁺CD154⁺, and CD4⁺CD69⁺ subgroups and reduce the proportion of CD4⁺CD62L⁺ subgroups. Negating BAFF activity with Atacicept (TACI-Fc) reverses vitality and activation of T cells. Furthermore, immunofluorescence detection revealed that BAFF promotes the expression of BAFF receptor (BAFF-R) and transmembrane activator and CAML interactor (TACI) in T cells. Flow cytometry displayed that BAFF/BAFF-R activates the PI3K-Akt signaling pathway while the application of PI3K inhibitor (wortmannin) illuminated that BAFF induces T cell vitality and activation through the PI3K-Akt signaling pathway. We conclude that BAFF is involved in not only the physiology of B cells, but also that of T cells. BAFF affects physiological T-cell activation through BAFF-R-mediated activation of the PI3K-Akt signaling pathway which mirrors one of the pathological mechanisms of T cell-mediated autoimmune diseases.

BAFF-R and TACI expression on CD3+ T cells: Interplay among BAFF, APRIL and T helper cytokines profile in systemic lupus erythematosus

BACKGROUND

Systemic lupus erythematosus (SLE) is the prototype of systemic autoimmune disease, characterized by loss of immune tolerance against self-antigens where autoantibody production is the hallmark of disease. B-cell-activating factor (BAFF) and A proliferation-inducing ligand (APRIL) are cytokines that promote autoreactive cell survival, immunoglobulin-class switching and autoantibody responses in human and mouse SLE models. BAFF and APRIL exert their functions through interactions with their receptors BAFF-R and TACI that are differentially expressed in B lymphocyte subsets, monocytes, dendritic cells and T lymphocytes. BAFF stimulation favors T lymphocyte activation and cytokine production through BAFF-R, which could contribute to the Th1, Th17 and/or Th2 response dysregulation observed in SLE patients.

OBJECTIVE

To evaluate the expression of the cytokines BAFF and APRIL and their association with the receptors BAFF-R and TACI on CD3+ T cells and to evaluate Th1/Th2/Th17 cytokine profile in patients with SLE.

METHODS

Fifteen healthy controls (HC) and 36 SLE patients were included, and their demographic and clinical data were assessed. The disease activity index (Mex-SLEDAI) and damage index (SLICC) were applied to the SLE patients. BAFF-R and TACI expression on CD3+ T cells were evaluated by flow cytometry. Serum BAFF and APRIL concentrations were measured by enzyme-linked immunosorbent assays (ELISA). Cytokine levels of Th1 (IL-12, IL-2, IFN-γ, TNF-α), Th2 (IL-4, IL-6, IL-10, IL-13) and Th17 (IL-1β e IL-17) were quantified with a multiplex assay (MAGPIX). Statistical analysis was performed using PASW Statistics v.20 and GraphPad Prism v.6 software.

RESULTS

No differences in BAFF-R or TACI expression on the CD3+ T cells of SLE and HC were observed. BAFF-R expression correlates inversely with disease activity (r = -0.538, p < 0.01), while TACI correlates with disease activity (r = 0.530, p < 0.05). Serum BAFF and APRIL levels were high in SLE patients and correlated with the disease activity index Mex-SLEDAI (r = 0.621, p < 0.01 and r = 0.416, p < 0.05). SLE patients were found to have significantly higher levels of IL-12, IFN-γ, TNF-α, IL-6, IL-10, IL-13, IL-1β and IL-17 compared to HC (p < 0.05). Cytokines IL-17 (r = 0.526) and TNF-α (r = 0.410) correlate with disease activity (p < 0.05), while APRIL (r = 0.477), IL-10 (r = 0.426) and IFN-γ (r = 0.440) levels were associated with organ damage (p < 0.01). Serum BAFF expression levels correlate with IL-4 (r = 0.424; p < 0.05), IL-6 (r = 0.420; p < 0.05) and IL-10 (r = 0.459; p < 0.01), whereas APRIL levels correlate with IL-2 (r = 0.666; p < 0.01), IL-12 (r = 0.611; p < 0.01) and TNF-α (r = 0.471; p < 0.05) cytokines. A subgroup of SLE patients with high serum BAFF levels (>2 ng/mL) also showed increased APRIL, IL-2, IL-6 and IL-10 levels (p < 0.05). Finally, BAFF, IL-4 and TNF-α serum levels were associated with high titers of antinuclear antibodies.

CONCLUSIONS

The study demonstrates an imbalance in the Th1/Th2 cytokine profile, with increased proinflammatory cytokines, as well as BAFF and APRIL serum levels. Associations of BAFF with Th2 profile cytokines and disease activity, as well as APRIL with Th1 profile cytokines and organ damage, suggest that BAFF and APRIL generated in the autoimmunity context could through still unknown mechanisms, modulate the microenvironment, and perpetuate the inflammatory response, autoantibody production and organ damage observed in SLE patients.

Association between gene polymorphisms and clinical features in idiopathic thrombocytopenic purpura patients

: Immune thrombocytopenic purpura (ITP) is an autoimmune disease in which increased platelet destruction and thrombocytopenia are diagnostic features. In fact, the exact pathogenesis of this disease is still unknown, but genetic changes can be a potential factor in the development of ITP. In this study, the relationship between polymorphisms with platelet destruction has been studied, which leads to decreased platelet count. Relevant literature was identified by a PubMed search (2000-2016) of English language papers using the terms 'ITP', 'polymorphism,' and 'immune system'. The majority of genetic changes (polymorphisms) occur in immune system genes, including interferon (IFN)-γ gene. These changes lead to the dysfunction of immune system and production of pathogenic antibodies against platelet surface glycoproteins such as glycoprotein IIb/IIIa, which eventually result in the destruction of platelets and increasing disease severity. In addition, IFN-γ as well as factors and cytokines involved in megakaryopoiesis, including stem cell factor and interleukin-3 (IL-3), leads to the differentiation of megakaryocytes and platelet release. Considering the fact that IFN-γ is a factor of inflammation and thrombocytopenia, coexistence of this cytokine with thrombopoietin, stem cell factor, and IL-3 results in megakaryocytes differentiation and platelet production, which can be effective to reduce disease severity and increase the platelet counts.

CP-25, a Novel Anti-inflammatory and Immunomodulatory Drug, Inhibits the Functions of Activated Human B Cells through Regulating BAFF and TNF-alpha Signaling and Comparative Efficacy with Biological Agents

Paeoniflorin-6′-O-benzene sulfonate (code: CP-25) was the chemistry structural modifications of Paeoniflorin (Pae). CP-25 inhibited B cells proliferation stimulated by B cell activating factor belonging to the TNF family (BAFF) or Tumor necrosis factor alpha (TNF-alpha). CP-25, Rituximab and Etanercept reduced the percentage and numbers of CD19⁺ B cells, CD19⁺CD20⁺ B cells, CD19⁺CD27⁺ B cells and CD19⁺CD20⁺CD27⁺ B cells induced by BAFF or TNF-alpha. There was significant difference between CP-25 and Rituximab or CP-25 and Etanercept. CP-25 down-regulated the high expression of BAFFR, BCMA, and TACI stimulated by BAFF or TNF-alpha. The effects of Rituximab and Etanercept on BAFFR or BCMA were stronger than that of CP-25. CP-25, Rituximab and Etanercept down-regulated significantly the expression of TNFR1 and TNFR2 on B cell stimulated by BAFF or TNF-alpha. CP-25, Rituximab and Etanercept down-regulated the expression of MKK3, P-p38, P-p65, TRAF2, and p52 in B cells stimulated by BAFF and the expression of TRAF2 and P-p65 in B cells stimulated by TNF-alpha. These results suggest that CP-25 regulated moderately activated B cells function by regulating the classical and alternative NF-κB signaling pathway mediated by BAFF and TNF-alpha-TRAF2-NF-κB signaling pathway. This study suggests that CP-25 may be a promising anti-inflammatory immune and soft regulation drug.

Alteration of B cell subsets and the receptor for B cell activating factor (BAFF) in paediatric patients with type 1 diabetes

BACKGROUND

Lately, mounting evidence has shown that B cells play an important role in the pathogenesis of type 1 diabetes (T1D). Here, we present alterations in B cell subsets including BAFF receptor (BAFFR) expression in cohorts of patients with type 1 diabetes (T1D) and their relatives.

PATIENTS AND METHODS

B cells were studied in 438 patients with T1D (158 at disease onset and 280 with long-term disease), 136 first-degree relatives and 53 healthy controls. The B cell panel included transitional, naïve, MZ-like, switched memory B cells and plasmablasts. We also measured serum BAFF levels as well as BAFFR expression on both B and T cells. Moreover, the effect of BAFF on T and B lymphocytes was analysed in vitro.

RESULTS

We observed a significant decrease in the proportion of transitional B cells in the patients with T1D, accompanied by an increased proportion of plasmablasts, especially in recent-onset patients and their relatives. While the BAFF serum levels did not differ in the patients with T1D, BAFFR-expressing B and especially T cell numbers were reduced in the T1D cohort, with the exception of patients with recent-onset disease who exhibited a significant increase in the number of BAFFR-expressing T cells. T cell activation and B cell proliferation were more pronounced after activation with BAFF in the T1D cohort compared to controls.

CONCLUSION

The B cell panel in patients with T1D is characterized by significantly reduced populations of B cells in their early stages of development with a shift towards plasma cells. The dynamics of BAFFR-expressing B and T cells and the more pronounced responsiveness of the T1D T cells to BAFF point to the role of BAFF and T and B cell cooperation in the development of T1D.