scholarly journals AIM2 deficiency in B cells ameliorates systemic lupus erythematosus by regulating Blimp-1–Bcl-6 axis-mediated B-cell differentiation

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Ming Yang ◽  
Di Long ◽  
Longyuan Hu ◽  
Zhidan Zhao ◽  
Qianwen Li ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
B Cells ◽  
B Cell ◽  
Lupus Erythematosus ◽  
Plasma Cells ◽  
Skin Lesions ◽  
Dna Demethylation ◽  
Conditional Knockout ◽  
B Cell Differentiation ◽  
Human Tonsil

AbstractAbsent in melanoma 2 (AIM2) has been reported to be a component of inflammasomes in innate immune cells. Surprisingly, AIM2 is expressed by B cells, and higher AIM2 expression is observed in the B cells from lupus patients. To date, the inflammasome-independent function of AIM2 in B cells remains unclear. Here, we report increased expression of AIM2 in human tonsil memory and germinal center (GC) B cells and in memory B cells and plasma cells from the circulation and skin lesions of lupus patients. Conditional knockout of AIM2 in B cells reduces the CD19+ B-cell frequency in lymph nodes and spleens, and dampens KLH-induced IgG1-antibody production. In a pristane-induced mouse model of lupus, AIM2 deficiency in B cells attenuates lupus symptoms and reduces the frequency of GC B cells, T follicular helper (Tfh) cells, plasmablast cells, and plasma cells. Furthermore, the loss of AIM2 in human B cells leads to the increased expression of Blimp-1 and reduces the expression of Bcl-6. However, the silencing of Blimp-1 and Bcl-6 has no significant effect on AIM2 expression, indicating that AIM2 might be the upstream regulator for Blimp-1 and Bcl-6. In addition, IL-10 is found to upregulate AIM2 expression via DNA demethylation. Together, our findings reveal that AIM2 is highly expressed in the B cells of lupus patients and promotes B-cell differentiation by modulating the Bcl-6–Blimp-1 axis, providing a novel target for SLE treatment.

scholarly journals Optimized Protocols for in Vitro T Cell-Dependent and T Cell-Independent Activation for B Cell Differentiation Studies Using Limited Cells

2021 ◽  
Author(s):  
Casper Marsman ◽  
Dorit Verhoeven
Keyword(s):  
Cell Differentiation ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Plasma Cells ◽  
Cell Formation ◽  
B Cell Differentiation ◽  
Differentiation Potential ◽  
Human B Cell

Background/methods: For mechanistic studies, in vitro human B cell differentiation and generation of plasma cells are invaluable techniques. However, the heterogeneity of both T cell-dependent (TD) and T cell-independent (TI) stimuli and the disparity of culture conditions used in existing protocols makes interpretation of results challenging. The aim of the present study was to achieve the most optimal B cell differentiation conditions using isolated CD19+ B cells and PBMC cultures. We addressed multiple seeding densities, different durations of culturing and various combinations of TD stimuli and TI stimuli including B cell receptor (BCR) triggering. B cell expansion, proliferation and differentiation was analyzed after 6 and 9 days by measuring B cell proliferation and expansion, plasmablast and plasma cell formation and immunoglobulin (Ig) secretion. In addition, these conditions were extrapolated using cryopreserved cells and differentiation potential was compared. Results: This study demonstrates improved differentiation efficiency after 9 days of culturing for both B cell and PBMC cultures using CD40L and IL-21 as TD stimuli and 6 days for CpG and IL-2 as TI stimuli. We arrived at optimized protocols requiring 2500 and 25.000 B cells per culture well for TD and TI assays, respectively. The results of the PBMC cultures were highly comparable to the B cell cultures, which allows dismissal of additional B cell isolation steps prior to culturing. In these optimized TD conditions, the addition of anti-BCR showed little effect on phenotypic B cell differentiation, however it interferes with Ig secretion measurements. Addition of IL-4 to the TD stimuli showed significantly lower Ig secretion. The addition of BAFF to optimized TI conditions showed enhanced B cell differentiation and Ig secretion in B cell but not in PBMC cultures. With this approach, efficient B cell differentiation and Ig secretion was accomplished when starting from fresh or cryopreserved samples. Conclusion: Our methodology demonstrates optimized TD and TI stimulation protocols for more indepth analysis of B cell differentiation in primary human B cell and PBMC cultures while requiring low amounts of B cells, making them ideally suited for future clinical and research studies on B cell differentiation of patient samples from different cohorts of B cell-mediated diseases.

scholarly journals Modulation of spontaneous B-cell differentiation in macroglobulinemia by retinoic acid

Blood ◽  
1994 ◽  
Vol 83 (8) ◽  
pp. 2206-2210 ◽  
Author(s):  
Y Levy ◽  
S Labaume ◽  
MC Gendron ◽  
JC Brouet
Keyword(s):  
Retinoic Acid ◽  
Cell Differentiation ◽  
B Cells ◽  
B Cell ◽  
Plasma Cells ◽  
B Cell Differentiation ◽  
Trans Retinoic Acid ◽  
All Trans Retinoic Acid ◽  
Culture Supernatants

Abstract We previously showed that clonal blood B cells from patients with macroglobulinemia spontaneously differentiate in vitro to plasma cells. This process is dependent on an interleukin (IL)-6 autocrine pathway. We investigate here whether all-trans-retinoic acid (RA) interferes with B-cell differentiation either in patients with IgM gammapathy of undetermined significance (MGUS) or Waldenstrom's macroglobulinemia (WM). RA at a concentration of 10(-5) to 10(-8) mol/L inhibited by 50% to 80% the in vitro differentiation of purified B cells from four of five patients with MGUS and from one of five patients with WM as assessed by the IgM content of day 7 culture supernatants. We next determined whether this effect could be related to an inhibition of IL- 6 secretion by cultured B cells and/or a downregulation of the IL-6 receptor (IL-6R), which was constitutively expressed on patients' blood B cells. A 50% to 100% (mean, 80%) inhibition of IL-6 production was found in seven of 10 patients (five with MGUS and two with WM). The IL- 6R was no more detectable on cells from patients with MGUS after 2 days of treatment with RA and slightly downregulated in patients with WM. It was of interest that B cells susceptible to the action of RA belonged mostly to patients with IgM MGUS, which reinforces our previous data showing distinct requirements for IL-6-dependent differentiation of blood B cells from patients with VM or IgM MGUS.

scholarly journals Tissue-specific DNA demethylation is required for proper B-cell differentiation and function

2016 ◽  
Vol 113 (18) ◽  
pp. 5018-5023 ◽  
Author(s):  
Shari Orlanski ◽  
Verena Labi ◽  
Yitzhak Reizel ◽  
Adam Spiro ◽  
Michal Lichtenstein ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
B Cell ◽  
Somatic Cell ◽  
Cell Development ◽  
Dna Demethylation ◽  
Conditional Knockout ◽  
B Cell Differentiation ◽  
Ample Evidence ◽  
Tissue Specific ◽  
And Function

There is ample evidence that somatic cell differentiation during development is accompanied by extensive DNA demethylation of specific sites that vary between cell types. Although the mechanism of this process has not yet been elucidated, it is likely to involve the conversion of 5mC to 5hmC by Tet enzymes. We show that a Tet2/Tet3 conditional knockout at early stages of B-cell development largely prevents lineage-specific programmed demethylation events. This lack of demethylation affects the expression of nearby B-cell lineage genes by impairing enhancer activity, thus causing defects in B-cell differentiation and function. Thus, tissue-specific DNA demethylation appears to be necessary for proper somatic cell development in vivo.

scholarly journals The BTB-ZF transcription factor Zbtb20 is driven by Irf4 to promote plasma cell differentiation and longevity

2014 ◽  
Vol 211 (5) ◽  
pp. 827-840 ◽  
Author(s):  
Stéphane Chevrier ◽  
Dianne Emslie ◽  
Wei Shi ◽  
Tobias Kratina ◽  
Cameron Wellard ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
B Cells ◽  
B Cell ◽  
Plasma Cell ◽  
Cell Cycle Progression ◽  
Plasma Cells ◽  
Cell Lineage ◽  
B Cell Differentiation ◽  
Antibody Secreting Cell ◽  
Important Player

The transcriptional network regulating antibody-secreting cell (ASC) differentiation has been extensively studied, but our current understanding is limited. The mechanisms of action of known “master” regulators are still unclear, while the participation of new factors is being revealed. Here, we identify Zbtb20, a Bcl6 homologue, as a novel regulator of late B cell development. Within the B cell lineage, Zbtb20 is specifically expressed in B1 and germinal center B cells and peaks in long-lived bone marrow (BM) ASCs. Unlike Bcl6, an inhibitor of ASC differentiation, ectopic Zbtb20 expression in primary B cells facilitates terminal B cell differentiation to ASCs. In plasma cell lines, Zbtb20 induces cell survival and blocks cell cycle progression. Immunized Zbtb20-deficient mice exhibit curtailed humoral responses and accelerated loss of antigen-specific plasma cells, specifically from the BM pool. Strikingly, Zbtb20 induction does not require Blimp1 but depends directly on Irf4, acting at a newly identified Zbtb20 promoter in ASCs. These results identify Zbtb20 as an important player in late B cell differentiation and provide new insights into this complex process.

scholarly journals The suppression of Brd4 inhibits peripheral plasma cell differentiation and exhibits therapeutic potential for systemic lupus erythematosus

2021 ◽  
Author(s):  
Shan Zeng ◽  
Qian Qiu ◽  
Yi Zhou ◽  
Youjun Xiao ◽  
Jingnan Wang ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
B Cells ◽  
B Cell ◽  
Plasma Cell ◽  
Lupus Erythematosus ◽  
Plasma Cells ◽  
Therapeutic Potential ◽  
Systemic Lupus ◽  
Plasma Cell Differentiation ◽  
Brd4 Inhibition

Background and purpose: To investigate the role of bromodomain-containing protein 4 (Brd4) in regulating B cell differentiation and its therapeutic potential for B cell-mediated autoimmune diseases such as systemic lupus erythematosus (SLE). Experimental Approach: Human and murine B cells were purified and cultured with different stimuli. B cell surface markers, proliferation and apoptosis were estimated by flow cytometry. Gene expression was measured by quantitative real-time PCR. Brd4 binding sites were analysed by the luciferase reporter assay and the chromatin immunoprecipitation (ChIP) assay. PFI-1 or JQ1 was used to inhibit Brd4. Mice with B cell-specific deletion of the Brd4 gene (Brd4flox/floxCD19-Cre+/-) and MRL/lpr mice were used to perform the in vivo experiments. Key Results: Brd4 inhibition suppressed plasmablast-mediated plasma cell differentiation but did not influence proliferation or apoptosis in healthy human and murine CD19+ B cells. PFI-1 treatment reduced the secretion of IgG and IgM in the supernatants of costimulation-induced B cells. Mechanistically, Brd4 regulates the terminal differentiation of B cells into plasma cells by targeting BLIMP1 by directly binding and activating the endogenous BLIMP1 promoter. Interestingly, PFI-1 treatment decreased the percentages of plasmablasts and plasma cells from patients with SLE. PFI-1 administration reduced the percentages of plasma cells, hypergammaglobulinemia and attenuated nephritis in MRL/lpr mice. Pristane-injected Brd4flox/floxCD19-Cre+/- mice exhibited improved nephritis and reduced percentages of plasma cells. Conclusions and Implications: Brd4 is an essential factor in regulating plasma cell differentiation. Brd4 inhibition may be a potential new strategy for the treatment of B cell-associated autoimmune disorders, including SLE.

scholarly journals TLR-mediated activation of Waldenström macroglobulinemia B cells reveals an uncoupling from plasma cell differentiation

2020 ◽  
Vol 4 (12) ◽  
pp. 2821-2836
Author(s):  
Jennifer Shrimpton ◽  
Matthew A. Care ◽  
Jonathan Carmichael ◽  
Kieran Walker ◽  
Paul Evans ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
B Cells ◽  
B Cell ◽  
Plasma Cell ◽  
Plasma Cells ◽  
Immunoglobulin M ◽  
B Cell Differentiation ◽  
Waldenström Macroglobulinemia ◽  
Plasma Cell Differentiation ◽  
Waldenstrom Macroglobulinemia

Abstract Waldenström macroglobulinemia (WM) is a rare malignancy in which clonal B cells infiltrate the bone marrow and give rise to a smaller compartment of neoplastic plasma cells that secrete monoclonal immunoglobulin M paraprotein. Recent studies into underlying mutations in WM have enabled a much greater insight into the pathogenesis of this lymphoma. However, there is considerably less characterization of the way in which WM B cells differentiate and how they respond to immune stimuli. In this study, we assess WM B-cell differentiation using an established in vitro model system. Using T-cell–dependent conditions, we obtained CD138+ plasma cells from WM samples with a frequency similar to experiments performed with B cells from normal donors. Unexpectedly, a proportion of the WM B cells failed to upregulate CD38, a surface marker that is normally associated with plasmablast transition and maintained as the cells proceed with differentiation. In normal B cells, concomitant Toll-like receptor 7 (TLR7) activation and B-cell receptor cross-linking drives proliferation, followed by differentiation at similar efficiency to CD40-mediated stimulation. In contrast, we found that, upon stimulation with TLR7 agonist R848, WM B cells failed to execute the appropriate changes in transcriptional regulators, identifying an uncoupling of TLR signaling from the plasma cell differentiation program. Provision of CD40L was sufficient to overcome this defect. Thus, the limited clonotypic WM plasma cell differentiation observed in vivo may result from a strict requirement for integrated activation.

scholarly journals Effects of targeting the transcription factors Ikaros and Aiolos on B cell activation and differentiation in systemic lupus erythematosus

2021 ◽  
Vol 8 (1) ◽  
pp. e000445
Author(s):  
Felice Rivellese ◽  
Sotiria Manou-Stathopoulou ◽  
Daniele Mauro ◽  
Katriona Goldmann ◽  
Debasish Pyne ◽  
...  
Keyword(s):  
Systemic Lupus Erythematosus ◽  
B Cells ◽  
B Cell ◽  
Lupus Erythematosus ◽  
Cell Activation ◽  
Plasma Cells ◽  
B Cell Differentiation ◽  
B Cell Activation ◽  
Systemic Lupus

ObjectiveTo evaluate the effects of targeting Ikaros and Aiolos by cereblon modulator iberdomide on the activation and differentiation of B-cells from patients with systemic lupus erythematosus (SLE).MethodsCD19+ B-cells isolated from the peripheral blood of patients with SLE (n=41) were cultured with TLR7 ligand resiquimod ±IFNα together with iberdomide or control from day 0 (n=16). Additionally, in vitro B-cell differentiation was induced by stimulation with IL-2/IL-10/IL-15/CD40L/resiquimod with iberdomide or control, given at day 0 or at day 4. At day 5, immunoglobulins were measured by ELISA and cells analysed by flow cytometry. RNA-Seq was performed on fluorescence-activated cell-sorted CD27-IgD+ naïve-B-cells and CD20lowCD27+CD38+ plasmablasts to investigate the transcriptional consequences of iberdomide.ResultsIberdomide significantly inhibited the TLR7 and IFNα-mediated production of immunoglobulins from SLE B-cells and the production of antinuclear antibodies as well as significantly reducing the number of CD27+CD38+ plasmablasts (0.3±0.18, vehicle 1.01±0.56, p=0.011) and CD138+ plasma cells (0.12±0.06, vehicle 0.28±0.02, p=0.03). Additionally, treatment with iberdomide from day 0 significantly inhibited the differentiation of SLE B-cells into plasmablasts (6.4±13.5 vs vehicle 34.9±20.1, p=0.013) and antibody production. When given at later stages of differentiation, iberdomide did not affect the numbers of plasmablasts or the production of antibodies; however, it induced a significant modulation of gene expression involving IKZF1 and IKZF3 transcriptional programmes in both naïve B-cells and plasmablasts (400 and 461 differentially modulated genes, respectively, false discovery rate<0.05).ConclusionThese results demonstrate the relevance of Ikaros and Aiolos as therapeutic targets in SLE due to their ability to modulate B cell activation and differentiation downstream of TLR7.

scholarly journals Altered Germinal-Center Metabolism in B Cells in Autoimmunity

Metabolites ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 40
Author(s):  
Ashton K. Shiraz ◽  
Eric J. Panther ◽  
Christopher M. Reilly
Keyword(s):  
B Cells ◽  
B Cell ◽  
Lupus Erythematosus ◽  
Germinal Center ◽  
Plasma Cells ◽  
Somatic Hypermutation ◽  
Cell Metabolism ◽  
Affinity Maturation ◽  
B Cell Differentiation ◽  
Contributing Factors

B lymphocytes play an important role in the pathophysiology of many autoimmune disorders by producing autoantibodies, secreting cytokines, and presenting antigens. B cells undergo extreme physiological changes as they develop and differentiate. Aberrant function in tolerogenic checkpoints and the metabolic state of B cells might be the contributing factors to the dysfunctionality of autoimmune B cells. Understanding B-cell metabolism in autoimmunity is important as it can give rise to new treatments. Recent investigations have revealed that alterations in metabolism occur in the activation of B cells. Several reports have suggested that germinal center (GC) B cells of individuals with systemic lupus erythematosus (SLE) have altered metabolic function. GCs are unique microenvironments in which the delicate and complex process of B-cell affinity maturation occurs through somatic hypermutation (SHM) and class switching recombination (CSR) and where Bcl6 tightly regulates B-cell differentiation into memory B-cells or plasma cells. GC B cells rely heavily on glucose, fatty acids, and oxidative phosphorylation (OXPHOS) for their energy requirements. However, the complicated association between GC B cells and their metabolism is still not clearly understood. Here, we review several studies of B-cell metabolism, highlighting the significant transformations that occur in GC progression, and suggest possible approaches that may be investigated to more precisely target aberrant B-cell metabolism in SLE.

Involvement of Ets Factor Spi-B, E Protein E2-2, and Id2 in Waldenström's Macroglobulinemia.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2946-2946
Author(s):  
Yangsheng Zhou ◽  
Xia Liu ◽  
Lian Xu ◽  
Zachary Hunter ◽  
Jenny Sun ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
B Cells ◽  
B Cell ◽  
Plasma Cells ◽  
Conflicts Of Interest ◽  
B Cell Differentiation ◽  
Protein Activity ◽  
E Proteins ◽  
E Protein ◽  
Nuclear Extracts

Abstract Abstract 2946 Poster Board II-922 Waldenström's macroglobulinemia (WM) is an incurable B cell disorder with a lymphoplasmacytic infiltrate in the bone marrow (BM) and IgM monoclonal gammopathy. WM tumor cells show variable differentiation, ranging from mature B-cells to plasma cells, which likely results from failure to fully undergo differentiation. In this study, we analyzed the expression of several genes involved in B cell differentiation by real time RT-PCR, such as Ets factors, the basic helix-loop-helix (bHLH) E proteins, as well as the inhibitors of DNA binding (Id) proteins which antagonize E protein activity. Comparison of BM CD19+ B cells obtained from 13 WM patients with 6 age-matched healthy donors showed that expression of the Ets factor Spi-B was increased four-fold, while Id2 was decreased three-fold. However, transcript levels of E proteins were similar between the two groups. Transduction of Spi-B in BCWM.1 WM cells resulted in two-fold higher levels of Id2 and five-fold lower levels of E2-2 compared with control. Id2 transduced BCWM.1 cells expressed two-fold lower levels of E2-2 and Spi-B. Taken together, these results implicate that increased expression of Spi-B alone cannot suppress Id2 transcription in the absence of E2-2 activity. Interestingly, overexpressing Spi-B while concomitantly knocking down Id2 increased the expression of the XBP-1 splicing isoform 2.5-fold without changing levels of Blimp-1 and IRF4. Moreover, inhibition of Spi-B expression by RNA interference or forced expression of Id2 in transduced BCWM.1 cells induced a significant decrease of anti-apoptotic Bcl-2. Importantly, we also showed that Spi-B co-immunoprecipated with Blimp-1 in nuclear extracts. Collectively, these data suggest that the regulatory network of the Spi-B, E2-2, and Id2 plays an essential role in B cell differentiation as well as the pathogenesis of WM, and suggests that Spi-B overexpression may block WM cell differentiation by sequestration of Blimp-1 while promoting tumor cell survival though up-regulation of Bcl-2. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Human pre-B cells differentiate into Ig-secreting plasma cells in the presence of interleukin-4 and activated CD4+ T cells or their membranes

Blood ◽  
1993 ◽  
Vol 82 (9) ◽  
pp. 2781-2789 ◽  
Author(s):  
J Punnonen ◽  
G Aversa ◽  
JE de Vries
Keyword(s):  
T Cells ◽  
Cell Differentiation ◽  
B Cells ◽  
B Cell ◽  
Cell Cultures ◽  
Cd4 T Cells ◽  
Plasma Cells ◽  
Interleukin 4 ◽  
B Cell Differentiation ◽  
Ig Synthesis

Abstract Studies on human B-cell development have been hampered by the lack of reproducible culture techniques to induce pre-B cells to differentiate into Ig-secreting plasma cells. Here, we describe that highly purified surface (s) mu-, cytoplasmic (c) mu+, CD10+, CD19+ human pre-B cells derived from fetal bone marrow (BM) differentiate with high frequencies into Ig-secreting plasma cells, when cocultured with activated, cloned CD4+ T cells and with interleukin-4 (IL-4). Production of IgM, total IgG, IgG4, and IgE in pre-B-cell cultures was detected, indicating that the cells also underwent Ig isotype switching. Pre-B-cell differentiation occurred in the absence of BM stromal cells, IL-7, and stem cell factor (SCF). However, IL-7 significantly enhanced the levels of Ig produced, whereas SCF was ineffective. Neutralizing anti-IL-4 monoclonal antibodies (MoAbs) completely inhibited pre-B-cell differentiation showing the specificity of the reaction. Intact CD4+ T- cell clones could be replaced by membrane preparations of these cells, indicating that the costimulatory signals provided by the activated CD4+ T cells are contact-mediated. In contrast, anti-CD40 MoAbs failed to provide the costimulatory signal required for pre-B-cell differentiation, which may be related to the very low expression of CD40 on fetal BM B cells. Activated CD4+ T cells and IL-4 also induced s mu expression and Ig synthesis in cultures initiated with pre-B cells that had been preincubated in medium for 2 days, and from which spontaneously emerging s mu+ B cells were removed by using a fluorescence-activated cell sorter. These results support the notion that the Ig synthesis observed in pre-B-cell cultures was not caused by outgrowth and differentiation of cells that spontaneously matured into s mu+ B cells. In addition, IL-4 and CD4+ T cells strongly enhanced CD40 and HLA-DR expression on the majority of cultured pre-B cells, further indicating that CD4+ T cells and IL-4 activate bona fide pre-B cells. Taken together, these data indicate that activated CD4+ T cells and IL-4 can provide all the necessary signals required for human pre-B cells to differentiate into Ig-secreting plasma cells.

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