Selective Targeting of T and B Cell Populations by Alemtuzumab in the Treatment of Multiple Sclerosis

Upstream targeting of both T and B cells is a rational therapeutic approach in multiple sclerosis (MS) in view of how both cell types and the interaction between them contribute to MS pathophysiology. This article will discuss this new way of thinking in MS: the targeting of both T and B cells, with a focus on the recently developed therapy, alemtuzumab (Lemtrada®, Genzyme, UK). Alemtuzumab depletes T and B lymphocytes, mainly via complement-dependent cytolysis and antibody-dependent cytolysis; depletion of B cells is not an enduring effect compared with the depletion of T cells. After dosing, CD4+ and CD8+ T cells and CD19 B cells decrease initially but increase over the following 11 months. During repopulation after alemtuzumab treatment, there is a shift in the relative proportions of T cell and B cell subsets whereby proportions of regulatory T cells and memory-phenotype T cells are increased and the proportion of naive T cells is decreased. A switch from a pro- to an anti-inflammatory phenotype and cytokine profile caused by alemtuzumab may underpin the long-lasting suppression of MS activity that has been observed in clinical trials. Alemtuzumab treatment is also associated with a consistently good safety and tolerability profile. Further, alemtuzumab appears to promote neurorehabilitation by improving measures of physical functioning, disability, measures of quality of life, and brain volume loss. Alemtuzumab therefore has the potential to reduce disease burden and improve substantially the prognosis for patients with MS.

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In VitroMeasles Virus Infection of Human Lymphocyte Subsets Demonstrates High Susceptibility and Permissiveness of both Naive and Memory B Cells

Journal of Virology ◽

10.1128/jvi.00131-18 ◽

2018 ◽

Vol 92 (8) ◽

pp. e00131-18 ◽

Cited By ~ 19

Author(s):

Brigitta M. Laksono ◽

Christina Grosserichter-Wagener ◽

Rory D. de Vries ◽

Simone A. G. Langeveld ◽

Maarten D. Brem ◽

...

Keyword(s):

T Cells ◽

B Cells ◽

B Cell ◽

Immune Suppression ◽

Peripheral Blood ◽

Measles Virus ◽

Memory B Cells ◽

T And B Cells ◽

B Cell Subsets

ABSTRACTMeasles is characterized by a transient immune suppression, leading to an increased risk of opportunistic infections. Measles virus (MV) infection of immune cells is mediated by the cellular receptor CD150, expressed by subsets of lymphocytes, dendritic cells, macrophages, and thymocytes. Previous studies showed that human and nonhuman primate memory T cells express higher levels of CD150 than naive cells and are more susceptible to MV infection. However, limited information is available about the CD150 expression and relative susceptibility to MV infection of B-cell subsets. In this study, we assessed the susceptibility and permissiveness of naive and memory T- and B-cell subsets from human peripheral blood or tonsils toin vitroMV infection. Our study demonstrates that naive and memory B cells express CD150, but at lower frequencies than memory T cells. Nevertheless, both naive and memory B cells proved to be highly permissive to MV infection. Furthermore, we assessed the susceptibility and permissiveness of various functionally distinct T and B cells, such as helper T (TH) cell subsets and IgG- and IgA-positive memory B cells, in peripheral blood and tonsils. We demonstrated that TH1TH17 cells and plasma and germinal center B cells were the subsets most susceptible and permissive to MV infection. Our study suggests that both naive and memory B cells, along with several other antigen-experienced lymphocytes, are important target cells of MV infection. Depletion of these cells potentially contributes to the pathogenesis of measles immune suppression.IMPORTANCEMeasles is associated with immune suppression and is often complicated by bacterial pneumonia, otitis media, or gastroenteritis. Measles virus infects antigen-presenting cells and T and B cells, and depletion of these cells may contribute to lymphopenia and immune suppression. Measles has been associated with follicular exhaustion in lymphoid tissues in humans and nonhuman primates, emphasizing the importance of MV infection of B cellsin vivo. However, information on the relative susceptibility of B-cell subsets is scarce. Here, we compared the susceptibility and permissiveness toin vitroMV infection of human naive and memory T- and B-cell subsets isolated from peripheral blood or tonsils. Our results demonstrate that both naive and memory B cells are more permissive to MV infection than T cells. The highest infection levels were detected in plasma cells and germinal center B cells, suggesting that infection and depletion of these populations contribute to reduced host resistance.

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A Single-Cell Transcriptome Profiling of Anterior Kidney Leukocytes From Nile Tilapia (Oreochromis niloticus)

Frontiers in Immunology ◽

10.3389/fimmu.2021.783196 ◽

2021 ◽

Vol 12 ◽

Author(s):

Liting Wu ◽

Along Gao ◽

Lan Li ◽

Jianlin Chen ◽

Jun Li ◽

...

Keyword(s):

T Cells ◽

B Cells ◽

B Cell ◽

Single Cell ◽

Nile Tilapia ◽

Immune Cell ◽

Cell Types ◽

Cell Transcriptome ◽

B Cell Subsets ◽

Single Cell Transcriptome

Teleost fish anterior kidney (AK) is an important hematopoietic organ with multifarious immune cells, which have immune functions comparable to mammalian bone marrow. Myeloid and lymphoid cells locate in the AK, but the lack of useful specific gene markers and antibody-based reagents for the cell subsets makes the identification of the different cell types difficult. Single-cell transcriptome sequencing enables single-cell capture and individual library construction, making the study on the immune cell heterogeneity of teleost fish AK possible. In this study, we examined the transcriptional patterns of 11,388 AK leukocytes using 10× Genomics single-cell RNA sequencing (scRNA-seq). A total of 22 clusters corresponding to five distinct immune cell subsets were identified, which included B cells, T cells, granulocytes, macrophages, and dendritic cells (DCs). However, the subsets of myeloid cells (granulocytes, macrophages, and DCs) were not identified in more detail according to the known specific markers, even though significant differences existed among the clusters. Thereafter, we highlighted the B-cell subsets and identified them as pro/pre B cells, immature/mature B cells, activated B/plasmablasts, or plasma cells based on the different expressions of the transcription factors (TFs) and cytokines. Clustering of the differentially modulated genes by pseudo-temporal trajectory analysis of the B-cell subsets showed the distinct kinetics of the responses of TFs to cell conversion. Moreover, we classified the T cells and discovered that CD3+CD4−CD8−, CD3+CD4+CD8+, CD4+CD8−, and CD4−CD8+ T cells existed in AK, but neither CD4+CD8− nor CD4−CD8+ T cells can be further classified into subsets based on the known TFs and cytokines. Pseudotemporal analysis demonstrated that CD4+CD8− and CD4−CD8+ T cells belonged to different states with various TFs that might control their differentiation. The data obtained above provide a valuable and detailed resource for uncovering the leukocyte subsets in Nile tilapia AK, as well as more potential markers for identifying the myeloid and lymphoid cell types.

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Ectopic Lymphoid Follicles in Multiple Sclerosis: Centers for Disease Control?

Frontiers in Neurology ◽

10.3389/fneur.2020.607766 ◽

2020 ◽

Vol 11 ◽

Author(s):

Austin Negron ◽

Olaf Stüve ◽

Thomas G. Forsthuber

Keyword(s):

Multiple Sclerosis ◽

T Cells ◽

T Cell ◽

B Cells ◽

B Cell ◽

T Cell Responses ◽

Memory B Cells ◽

Lymphoid Follicles ◽

Cell Responses ◽

B Cell Responses

While the contribution of autoreactive CD4+ T cells to the pathogenesis of Multiple Sclerosis (MS) is widely accepted, the advent of B cell-depleting monoclonal antibody (mAb) therapies has shed new light on the complex cellular mechanisms underlying MS pathogenesis. Evidence supports the involvement of B cells in both antibody-dependent and -independent capacities. T cell-dependent B cell responses originate and take shape in germinal centers (GCs), specialized microenvironments that regulate B cell activation and subsequent differentiation into antibody-secreting cells (ASCs) or memory B cells, a process for which CD4+ T cells, namely follicular T helper (TFH) cells, are indispensable. ASCs carry out their effector function primarily via secreted Ig but also through the secretion of both pro- and anti-inflammatory cytokines. Memory B cells, in addition to being capable of rapidly differentiating into ASCs, can function as potent antigen-presenting cells (APCs) to cognate memory CD4+ T cells. Aberrant B cell responses are prevented, at least in part, by follicular regulatory T (TFR) cells, which are key suppressors of GC-derived autoreactive B cell responses through the expression of inhibitory receptors and cytokines, such as CTLA4 and IL-10, respectively. Therefore, GCs represent a critical site of peripheral B cell tolerance, and their dysregulation has been implicated in the pathogenesis of several autoimmune diseases. In MS patients, the presence of GC-like leptomeningeal ectopic lymphoid follicles (eLFs) has prompted their investigation as potential sources of pathogenic B and T cell responses. This hypothesis is supported by elevated levels of CXCL13 and circulating TFH cells in the cerebrospinal fluid (CSF) of MS patients, both of which are required to initiate and maintain GC reactions. Additionally, eLFs in post-mortem MS patient samples are notably devoid of TFR cells. The ability of GCs to generate and perpetuate, but also regulate autoreactive B and T cell responses driving MS pathology makes them an attractive target for therapeutic intervention. In this review, we will summarize the evidence from both humans and animal models supporting B cells as drivers of MS, the role of GC-like eLFs in the pathogenesis of MS, and mechanisms controlling GC-derived autoreactive B cell responses in MS.

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Changes in the T and B- Cell Subsets Following Treatment with a CD25-Antibody in Patients with Steroid Refractory GvHD

Blood ◽

10.1182/blood.v124.21.2497.2497 ◽

2014 ◽

Vol 124 (21) ◽

pp. 2497-2497

Author(s):

Geothy Chakupurakal ◽

Maria Garcia- Marquez ◽

Alexander Shimabukuro- Vornhagen ◽

Hans Anton Schloesser ◽

Udo Holtick ◽

...

Keyword(s):

T Cells ◽

B Cells ◽

B Cell ◽

Interleukin 2 ◽

Unrelated Donors ◽

B Cell Subsets ◽

Regulatory Type ◽

Steroid Refractory

Abstract Allogeneic stem cell transplantation is the therapeutic option for a variety of malignant and non-malignant haematological diseases. Graft versus Host Disease (GvHD) is a common post transplant complication. In 40% of these patients, GvHD is steroid refractory and associated with a mortality of around 60%. Basiliximab is a chimeric murine –human antibody also selective for interleukin -2 receptor (IL-2R) with a half life of 7 days. It is routinely used as part of the induction therapy in renal transplant recipients to prevent acute rejection following successful phase III studies. Phase 2 studies have demonstrated its superior efficacy in treating patients with steroid refractory GvHD (1). We administered Basiliximab in 14 patients with steroid refractory GvHD with a median age of 41 (range 20-69). M: F 7:7. All patients but one 13/14 received PBSC from unrelated donors and 6/13 had mismatched unrelated donors. Overall response was in the order of 12/14 (85%). One patient could not be assessed. 7/14 (50%) achieved a complete response to treatment. We aimed to study the in vivo T- and B-cell changes following Basiliximab administration as this would be an ideal platform to monitor the alterations in the regulatory T and B-cell compartment. PBMCs were obtained from all donors after informed consent, Immucan (Nr 11-116) approved by our local ethics committee, prior to and after weekly administration of Basiliximab 40mg for 4 weeks. Control samples were obtained from patients with steroid responsive acute GvHD. The total number of CD3+ as well as CD4+ and CD8+ T-cells remained constant during treatment and no change was observed on comparison with the controls. Gagliani et al (2) demonstrated that regulatory type 1 T-cells can be identified by the co-expression of CD49b and Lag3. No difference was observed between the % CD49d+, Lag3+ T-cells in the control cohort and the treatment cohort prior to therapy, ie day 0. The % CD49d+, Lag3+ T-cells decreased during the treatment period (statistically significant) in comparison to the control cohort. Despite the use of the CD25-antibody, a small population of CD25+, CD127+ cells could be detected and this population correlated to the % CD49d+, Lag3+ T-cells. Figure 1 Figure 1. Figure 2 Figure 2. The % CD19+, CD20+ B-cells were similar prior to treatment in the treatment group and control. Following the first administration a rise was observed followed by a decline over the next 3 weeks. No changes were seen in the activated (CD20+, CD86+) and anergic B-cell subsets (CD20+, CD21-) during the observation period. The % of CD24high, CD27+ regulatory B-cells were found to be twice that seen in the controls. With treatment a decrease was seen in this population. The CD24high, CD38high transitional B-cells were also found to be higher than that seen in the controls. No change was observed in this subset with treatment. Figure 3 Figure 3. This is the first attempt to study the in-vivo changes induced by a CD25 antibody in patients with steroid refractory GvHD. We conclude that this antibody not only depletes the alloreactive CD25+ T and B-cell population but also alters the regulatory T and B-cell subsets in comparison to patients with steroid responsive GvHD. Our clinical data supports the efficacy of this drug in patients with steroid refractory GvHD. Contrary to the current knowledge that regulatory T-cells are required for GvHD suppression our data suggests that Basiliximab facilitates regulatory T-cell depletion. The reduction of the regulatory T-cell subset observed in patients responding to anti CD25 treatment suggests a complex regulation and potential dichotomous role of these cells in acute GvHD. Schmidt-Hieber M, Fietz T, Knauf W, Uharek L, Hopfenmuller W, Thiel E, et al. Efficacy of the interleukin-2 receptor antagonist basiliximab in steroid-refractory acute graft-versus-host disease. Br J Haematol. 2005 Aug;130(4):568-74.Gagliani N, Magnani CF, Huber S, Gianolini ME, Pala M, Licona-Limon P, et al.Coexpression of CD49b and LAG-3 identifies human and mouse T regulatory type 1 cells. Nat Med. 2013 Jun;19(6):739-46 Disclosures No relevant conflicts of interest to declare.

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Defining Fundamental B Cell-Subset Dysfunction in Myeloma

Blood ◽

10.1182/blood.v128.22.2085.2085 ◽

2016 ◽

Vol 128 (22) ◽

pp. 2085-2085

Author(s):

Rao H Prabhala ◽

Srikanth Talluri ◽

Megan Stekla ◽

Andreea Negroiu ◽

Michael Buonopane ◽

...

Keyword(s):

T Cells ◽

B Cells ◽

B Cell ◽

Cell Function ◽

Memory T Cells ◽

Cell Subset ◽

Cell Dysfunction ◽

B Cell Function ◽

Ifn Γ ◽

B Cell Subsets

Abstract One of the most prominent features of multiple myeloma (MM) has been immune deficiency which predisposes patients to infectious complications and suppresses development of anti-MM immune responses. We and others have previously described the T cell dysfunction in Th1, Treg and Th17 cells, plasmacytoid dendritic cells and myeloid-derived suppressor cells (MDSC). However, the most fundamental and long identified deficiency is in the humoral immune response. Suppression of uninvolved immunoglobulins (UIgs) have been well described (i.e. suppression of serum IgA and IgM in IgG myeloma); and antibody responses to vaccination have been inadequate. However, very limited information is available regarding B cell function and how UIgs are suppressed in myeloma. We have now evaluated six different B cell subsets (B1a, B1b, B2, Breg, IRA-B, and MZ) in peripheral blood (PBMC) and bone marrow (BM) to understand alterations in B cell immune function in MM. We have observed significantly lower ratio of B2 (normal B cell-subset) and B1a (natural antibody-producing cells) subsets (10±4 vs 57±17; p < 0.05) and B2 and Breg (regulatory B cell-subset) subsets (14±4 vs 45±13; p< 0.05) in PBMC from MM patients (N=19) compared with healthy donor (N=33) respectively. Similar results were observed in BM samples from MM patients (N=18) compared with healthy donors (N=12); B2/B1a subset (2.4±0.6 vs 8±1.3; p < 0.05) and B2/Breg subset (8±1.4 vs 43.7±8.4; p< 0.05) respectively. To understand whether MM cells directly or indirectly alter B cell-subsets, we incubated myeloma cells (N=4) with healthy donor PBMCs, and analyzed B cell subsets after 3 days. We observed significant elevation in B1 subset (2.5 fold of control) and reduced B2 subset (89±3% of control). When we incubated PBMCs with IL-17A over-expressing MM cells (N=3), we observed further significant reduction in B2 subset (74% of control). When normal PBMCs are cultured in IL-17A (N=4) we observed significantly increased IL-10-producing Breg subset (28% of control). Similarly, co-culture of healthy B cells with MDSC led to significant increase (3.8 times) in Breg cell- population (N=3) compared with control group. To study the impact of B cell dysfunction on T cell function in MM, we activated normal PBMC via anti-CD3 antibody, in the presence or absence of B cells, and measured intra-cellular IFN-γ levels in CD69+ cells. We observed that the absence of B cells significantly inhibited interferon-producing T cells compared to control (by 43%; p<0.05). Importantly, following removal of CD25+ cells (Tregs and activated memory T cells), with or without B cells, we did not observe any difference in the inhibition of IFN-γ, indicating that B cells influence memory T cells rather than naïve T cells for the production of IFN-γ. To evaluate impact of lenalidomide on this interaction, we stimulated purified normal donor CD45RO memory T cells with Th1 polarizing cocktail in the presence or absence of purified normal B cells or B cells from MM patient (MM-B) in presence of lenalidomide and observed thatlenalidomide significantly improved MM-B cell-mediated IFN-γ-producing Th1 responses (by 32%, p<0.05) compared to normal B cell-mediated Th1 responses. In an effort to evaluate whether any therapy may improve the B cell function, we cultured normal PBMCs in the presence of lenalidomide (N=9) and observed reduction in Breg subset by 40% of control. To evaluate the effect of therapy on B cell-subsets in MM, we analyzed B cell subsets in PBMC from newly-diagnosed and lenalidomide-treated MM patients and observed that lenalidomide-treated group showed significant (p<0.05) improvement in B cell subsets (increased B2 and lower B1 cells) even before clinical response. These results suggest that immunomodulatory agents may be able to re-program humoral immunity in these patients. In summary, we report that the myeloma cell driven skewed B cell subset distribution with consequent B cell dysfunction drives the observed abnormalities in humoral/cell mediated immunity. The current therapeutic interventions, besides providing deep clinical responses, may also improve B cell function with impact on long term outcome. Disclosures No relevant conflicts of interest to declare.

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CD154 Blockade Prevents Allosensitization through Inhibiting Both T- and B-Cell Activation and Decreasing Expression of IFN-γ and IL-10 in T-Cells.

Blood ◽

10.1182/blood.v110.11.1346.1346 ◽

2007 ◽

Vol 110 (11) ◽

pp. 1346-1346

Author(s):

Hong Xu ◽

Jun Yan ◽

Yiming Huang ◽

Paula M. Chilton ◽

Michael K. Tanner ◽

...

Keyword(s):

T Cells ◽

B Cells ◽

B Cell ◽

Cell Activation ◽

Skin Grafting ◽

Cell Populations ◽

B Cell Activation ◽

T And B Cells ◽

Time Points ◽

Ifn Γ

Abstract Recipient sensitization to MHC antigens from transfusion therapy and prior graft rejection is among the most critical of problems in clinical transplantation. Sensitized patients reject vascularized organ or bone marrow transplants within minutes to hours as a result of preformed anti-donor Abs. Preventing allosensitization at the time recipients are exposed to donor alloantigens would be of obvious clinical benefit. B cell activation and the generation of memory B cells depends upon T cell responses via signaling from the co-stimulatory molecule CD154 (on activated T cells) to CD40 (on B cells). We have demonstrated in an allogeneic mouse model [BALB/c (H2Kd) to B6 (H2Kb)] that blockade of T and B cell interactions with anti-CD154 induces B cell tolerance, as defined by complete abrogation of the generation of donor-specific Ab after skin grafting. Furthermore, anti-CD154 treatment promotes successful subsequent bone marrow transplantation in these recipients, confirming that sensitization was prevented. In this study, we evaluated the effect of anti-CD154 mAb on T- and B-cell populations, activation state, and cytokine expression by T cells. B6 recipients were treated with anti-CD154 (day 0 and +3) or isotype hamster IgG control around the time receiving BALB/c skin grafts (day 0), and the number of T-cells (CD4+ and CD8+), total B-cells (CD19+), immature B-cells (CD19+CD24highCD23low), and follicular B-cells (CD19+CD24lowCD23high) in the spleen was enumerated by 4 color flow cytometry at day 7, 15 and 25 after skin grafting. No significant difference in absolute number of T- and B-cell subpopulations was seen between anti-CD154 and control IgG treated groups at the time points tested. By measuring the percentage CD71+ cells in the CD8+ or CD4+ gate or CD69+ in the CD19+ gate, activated T and B cell populations were evaluated. In vivo blockade of CD154 resulted in a significantly reduced activation of alloreactive T- and B-cells: the percentage of CD8+/CD71+ T cells was significantly lower at day 7 and the percentage of CD4+/CD71+ T cells was significantly lower at all time points compared with control mice (P < 0.05). The percentage of CD19+/CD69+ B cells at day 7 and 25 was significantly lower compared with control IgG treated mice (P < 0.05). To determine the effect of anti-CD154 treatment on Th1 and Th2 cytokine production, intracellular IFN-γ and IL-10 expression was analyzed. The IFN-γ expression in both CD8 and CD4 T-cells was inhibited at day 7 and reached significance (P < 0.01) by day 15 compared with control IgG treated group. IL-10, a cytokine which promotes B-cell activation and differentiation expression, was similar at day 7 between the two groups, but significantly decreased in both CD8 and CD4 T-cells at day 15 in mice treated with anti-CD154. Therefore, these data suggest that blockade of CD154 during initial antigen exposure mechanistically interferes with activation of both allo antigen-specific T and B-cells and inhibits the generation of allogeneic Ab (allosensitization). These effects are associated with suppression of IFN-γ and IL-10 cytokine secretion. Figure Figure

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Mutual Activation and Expansion of Donor CD4 + T Cells and B Cells in Transplants Play a Critical Role in the Initiation of Chronic Graft-Versus-Host Disease.

Blood ◽

10.1182/blood.v114.22.1342.1342 ◽

2009 ◽

Vol 114 (22) ◽

pp. 1342-1342

Author(s):

James Sundblom Young ◽

Dongchang Zhao ◽

Tangsheng Yi ◽

Hongjun Liu ◽

Defu Zeng

Keyword(s):

T Cells ◽

Cell Differentiation ◽

B Cells ◽

B Cell ◽

Graft Versus Host Disease ◽

Cd4 T Cells ◽

Chronic Gvhd ◽

B Cell Differentiation ◽

T And B Cells ◽

Graft Versus Host

Abstract Abstract 1342 Poster Board I-364 Chronic graft versus host disease (GVHD) is an autoimmune-like disease, in which both donor CD4+ T and B cells play important roles in the pathogenesis. However, it is unclear how donor CD4+ T and B cells interact in the context of chronic GVHD. In our current studies, we found that, in a new chronic GVHD model of MHC-matched DBA/2 donor to BALB/c host, depletion of donor CD4+ T cells in transplants prevented donor B220+ B cell upregulation of co-stimulatory molecules (i.e. B7.1, B7.2, and MHC II), prevented donor B cell differentiation into syndecan+ IgG anti-dsDNA autoantibody-producing plasma cells, and prevented the induction of chronic GVHD. In addition, we found that donor CD4+ T cells were able to drive both marginal zone B (AA4.1−B220+CD1dhiCD23lo) and follicular B (AA4.1−B220+CD23hiCD1dlo) cells to become IgG autoantibody-producing cells. On the other hand, depletion of donor B220+ B cells in transplants prevented expansion of donor-type CD4+ T cells that proliferated in response to donor DC stimulation, prevented the skewing of TCR CDR3-length of the donor CD4+ T cells as revealed by TCR spectratyping, and prevented induction of chronic GVHD. These results indicate that donor CD4+ T and B cells mutually activate each other in the chronic GVHD recipients; alloreactive donor CD4+ T cells activate and drive donor B cell differentiation into IgG autoantibody producing cells, in turn, donor B cells mediate the expansion and TCR-spreading of autoreactive donor CD4+ T cells. Therefore, donor CD4+ T and B cells in transplants orchestrate the development of chronic GVHD. This work is supported by NIH R01 AI066008. Disclosures No relevant conflicts of interest to declare.

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Frequencies of the separate human B cell subsets activatable to Ig secretion by Epstein-Barr virus and pokeweed mitogen.

Journal of Experimental Medicine ◽

10.1084/jem.157.6.1808 ◽

1983 ◽

Vol 157 (6) ◽

pp. 1808-1814 ◽

Cited By ~ 42

Author(s):

O Martínez-Maza ◽

S Britton

Keyword(s):

T Cells ◽

B Cells ◽

B Cell ◽

Epstein Barr Virus ◽

Human Peripheral Blood ◽

Pokeweed Mitogen ◽

Barr Virus ◽

Human B Cells ◽

Epstein Barr ◽

B Cell Subsets

We have developed a microculture system suitable for limiting dilution analysis of Epstein-Barr virus (EBV)- and pokeweed mitogen (PWM)-induced activation of immunoglobulin secretion by human B cells. It was found that exogenous filler cells were not required to obtain optimal EBV-induced B cell precursor frequency (PF) estimates, although filler T cells were required for optimal PWM activation. In fact, when autologous T cells were used as filler cells, a marked decrease in the EBV-induced IgM PF was noted. Treatment of the T cells with cyclosporin A partially eliminated, and irradiation of the T cells completely eliminated, this decrease. The calculated PF of B cells activated by EBV was from 1/290 to 1/3,700 for IgM, and from 1/920 to 1/3,250 for IgG secretion. PWM activated from 1/140 to 1/3,200 B cells to IgM secretion. The results of experiments in which EBV and PWM were mixed, indicated that these two polyclonal activators operated on different B cell subpopulations. Therefore, both these agents seem to activate small, discrete subpopulations of human peripheral blood B cells to Ig secretion.

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3285 Toxicity of Released B Cell Products in Multiple Sclerosis: Effects on Neurons and Oligodendrocytes

Journal of Clinical and Translational Science ◽

10.1017/cts.2019.265 ◽

2019 ◽

Vol 3 (s1) ◽

pp. 116-116

Author(s):

Leah Zuroff ◽

Hanane Touil ◽

Micah Romer ◽

Liljana Nedelkoska ◽

Joyce A. Benjamins ◽

...

Keyword(s):

Multiple Sclerosis ◽

B Cells ◽

B Cell ◽

Chronic Inflammatory Disease ◽

Conditioned Media ◽

Pathogenic Potential ◽

Cytotoxic Factor ◽

B Cell Subsets ◽

Normal Controls ◽

Age And Sex

OBJECTIVES/SPECIFIC AIMS: We previously demonstrated that products released by cultured B cells from patients with Multiple Sclerosis (MS) are cytotoxic to neurons and oligodendrocytes, while minimal toxicity was observed in response to B cell secretory products from age- and sex-matched normal controls. The goal of this proposal is to identify the range of brain cells susceptible to MS B cell-mediated cytotoxicity, to define the cytotoxic factor(s) released by MS B cells, and to determine whether particular subset(s) of MS B cells harbor the greatest pathogenic potential. METHODS/STUDY POPULATION: The toxicity of B cell products will be demonstrated by incubating primary rat cultures of neurons, oligodendrocytes, and oligodendrocyte progenitor cells (OPCs) with B cell supernatants. B cells will be isolated from the peripheral circulation of untreated relapse-remitting MS (RRMS) patients and age- and sex-matched normal controls. The identification of specific toxic factor(s) in MS B cell supernatants will be achieved through a combination of exosome-depletion/enrichment of conditioned media, proteomics, next generation sequencing, and lipidomics. Determining pathogenic B cell subsets will be achieved by cell sorting into memory and naïve B cell subsets prior to collection of supernatants. RESULTS/ANTICIPATED RESULTS: We hypothesize that the toxicity of MS B cell products is mediated, at least in part, by extracellular vesicles, such as exosomes. We expect depletion of these exosomes from the B cell conditioned media or inhibition of their biogenesis will mitigate the observed toxicity. Furthermore, differences in B cell-derived exosomal content, such as proteins, (mi)RNAs, or lipids, likely explain the differences in observed toxicity. Lastly, we hypothesize that memory B cells, which are enriched in the CNS of MS patients and demonstrate a more pro-inflammatory profile than naïve B cells, are responsible for the toxicity observed in supernatants of total B cells. DISCUSSION/SIGNIFICANCE OF IMPACT: MS is the most prevalent chronic inflammatory disease of the CNS, affecting more than 2 million people worldwide. Although over a dozen disease-modifying therapies are approved for the treatment of RRMS, none are meaningfully effective at limiting disease progression. This proposal will provide new insight into immune-CNS interactions in progressive MS and provide much-needed novel targets for therapeutic intervention, either via blocking identified toxic molecule(s) or by selectively depleting pathogenic B cell subsets.

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Thymosin-α1 expands deficient IL-10-producing regulatory B cell subsets in relapsing–remitting multiple sclerosis patients

Multiple Sclerosis Journal ◽

10.1177/1352458517695892 ◽

2017 ◽

Vol 24 (2) ◽

pp. 127-139 ◽

Cited By ~ 8

Author(s):

Elena Giacomini ◽

Fabiana Rizzo ◽

Marilena P Etna ◽

Melania Cruciani ◽

Rosella Mechelli ◽

...

Keyword(s):

Multiple Sclerosis ◽

B Cells ◽

B Cell ◽

Cell Response ◽

Thymosin Α1 ◽

Regulatory B Cell ◽

Relapsing Remitting ◽

Remitting Multiple Sclerosis ◽

B Cell Subsets ◽

Relapsing Remitting Multiple Sclerosis

Background: B cells are key pathogenic effectors in multiple sclerosis (MS) and several therapies have been designed to restrain B cell abnormalities by directly targeting this lymphocyte population. Objectives: Moving from our data showing a Toll-like receptor (TLR)7-driven dysregulation of B cell response in relapsing–remitting multiple sclerosis (RRMS) and having found a low serum level of Thymosin-α1 (Tα1) in patients, we investigated whether the addition of this molecule to peripheral blood mononuclear cells (PBMCs) would influence the expansion of regulatory B cell subsets, known to dampen autoimmune inflammation. Methods: Serum Tα1 level was measured by enzyme immunoassay. Cytokine expression was evaluated by Cytometric Bead Array (CBA), enzyme-linked immunosorbent assay (ELISA), and real-time reverse transcription polymerase chain reaction (RT-PCR). B cell subsets were analyzed by flow cytometry. Results: Tα1 pre-treatment induces an anti-inflammatory status in TLR7-stimulated RRMS PBMC cultures, reducing the secretion of pro-inflammatory interleukin (IL)-6, IL-8, and IL-1β while significantly increasing the regulatory IL-10 and IL-35. Indeed, Tα1 treatment enhanced expansion of CD19+CD24+CD38hi transitional-immature and CD24low/negCD38hi plasmablast-like regulatory B cell subsets, which likely inhibit both interferon (IFN)-γ and IL-17 production. Conclusion:: Our study reveals a deficient ability of B cells from MS patients to differentiate into regulatory subsets and unveils a novel anti-inflammatory and repurposing potential for Tα1 in MS targeting B cell response.

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