scholarly journals Specific hypomethylation programs underpin B cell activation in early multiple sclerosis

2021 ◽  
Vol 118 (51) ◽  
pp. e2111920118
Author(s):  
Qin Ma ◽  
Stacy J. Caillier ◽  
Shaun Muzic ◽  
Michael R. Wilson ◽  
Roland G. Henry ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
B Cells ◽  
B Cell ◽  
Cell Activation ◽  
Cell Function ◽  
Immune Cell ◽  
Disease Onset ◽  
Cell Types ◽  
B Cell Differentiation ◽  
Dna Hypomethylation

Epigenetic changes have been consistently detected in different cell types in multiple sclerosis (MS). However, their contribution to MS pathogenesis remains poorly understood partly because of sample heterogeneity and limited coverage of array-based methods. To fill this gap, we conducted a comprehensive analysis of genome-wide DNA methylation patterns in four peripheral immune cell populations isolated from 29 MS patients at clinical disease onset and 24 healthy controls. We show that B cells from new-onset untreated MS cases display more significant methylation changes than other disease-implicated immune cell types, consisting of a global DNA hypomethylation signature. Importantly, 4,933 MS-associated differentially methylated regions in B cells were identified, and this epigenetic signature underlies specific genetic programs involved in B cell differentiation and activation. Integration of the methylome to changes in gene expression and susceptibility-associated regions further indicates that hypomethylated regions are significantly associated with the up-regulation of cell activation transcriptional programs. Altogether, these findings implicate aberrant B cell function in MS etiology.

scholarly journals Hyaluronate-CD44 Interactions Can Induce Murine B-Cell Activation

Blood ◽  
1997 ◽  
Vol 89 (8) ◽  
pp. 2901-2908 ◽  
Author(s):  
Asimah Rafi ◽  
Mitzi Nagarkatti ◽  
Prakash S. Nagarkatti
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Cell Activation ◽  
Critical Role ◽  
Surface Glycoprotein ◽  
B Cell Differentiation ◽  
B Cell Activation ◽  
Cell Surface Glycoprotein ◽  
Immunodeficient Mice

Abstract CD44 is a widely distributed cell surface glycoprotein whose principal ligand has been identified as hyaluronic acid (HA), a major component of the extracellular matrix (ECM). Recent studies have demonstrated that activation through CD44 leads to induction of effector function in T cells and macrophages. In the current study, we investigated whether HA or monoclonal antibodies (MoAbs) against CD44 would induce a proliferative response in mouse lymphocytes. Spleen cells from normal and nude, but not severe combined immunodeficient mice, exhibited strong proliferative responsiveness to stimulation with soluble HA or anti-CD44 MoAbs. Furthermore, purified B cells, but not T cells, were found to respond to HA. HA was unable to stimulate T cells even in the presence of antigen presenting cells (APC) and was unable to act as a costimulus in the presence of mitogenic or submitogenic concentrations of anti-CD3 MoAbs. In contrast, stimulation of B cells with HA in vitro, led to B-cell differentiation as measured by production of IgM antibodies in addition to increased expression of CD44 and decreased levels of CD45R. The fact that the B cells were responding directly to HA through its binding to CD44 and not to any contaminants or endotoxins was demonstrated by the fact that F(ab)2 fragments of anti-CD44 MoAbs or soluble CD44 fusion proteins could significantly inhibit the HA-induced proliferation of B cells. Also, HA-induced proliferation of B cells was not affected by the addition of polymixin B, and B cells from lipopolysaccharide (LPS)-unresponsive C3H/HeJ strain responded strongly to stimulation with HA. Furthermore, HA, but not chondroitin-sulfate, another major component of the ECM, induced B-cell activation. It was also noted that injection of HA intraperitoneally, triggered splenic B cell proliferation in vivo. Together, the current study demonstrates that interaction between HA and CD44 can regulate murine B-cell effector functions and that such interactions may play a critical role during normal or autoimmune responsiveness of B cells.

scholarly journals POS1223 RAS GUANYL RELEASING PROTEIN 1 (RASGRP1) IN PERIPHERAL B CELLS LINKS RA TO COVID-19

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 895.2-895
Author(s):  
S. Hannawi ◽  
F. Alqutami ◽  
M. Y. Hachim
Keyword(s):  
Rheumatoid Arthritis ◽  
B Cells ◽  
B Cell ◽  
Cell Activation ◽  
Plasma Cells ◽  
Immune Cell ◽  
In Silico Analysis ◽  
Differentially Expressed ◽  
Transcriptional Enhancer ◽  
Activated T Cells

Background:Changes in the B cell subpopulations is a hallmark of the antiviral response against SARS-CoV-2 and is associated with COVID-19 severity (1). Recently our group showed common derangement observed in rheumatoid arthritis (RA) and COVID-19 (2). In RA, synovium attracts potentially autoreactive—B cells and plasma cells that play a central role in RA pathogenesis (3). We were interested to know the similarity in B cell’s transcriptomic changes specific to RA and COVID-19.Objectives:Identify similar upregulated genes in synovium and B cells in RA and at the same time are differentially expressed in B cells infected with SARS-CoV-2 or from COVID-19 patients.Methods:RNAseq dataset (GSE89408) of (218) samples isolated from joint synovial biopsies from subjects with and without rheumatoid arthritis were retrieved from GEO online database. Differentially expressed genes (DRGs) specific to RA were identified after exclusion of those upregulated in Osteoarthritis or other joint condition samples in the same dataset. The RA specific genes were intersected with DEGs between B cells from healthy versus RA as extracted from (GSE110999) dataset. The shortlisted genes specifically upregulated in B cells of RA were identified and were explored in B cells COVID-19 transcriptome datasets using (https://metascape.org/COVID).Results:60 genes were found to be specifically upregulated in RA synovium and B cells and are changed in B cells infected with SARS-CoV-2 or from COVID-19 patients, Figure (1-A). Those genes were involved in interferon signaling, antiviral and immune cell activation. RASGRP1 was common between B cells of RA and COVID-19 and might play a role in the pathogenesis of both, Figure (1-B). RASGRP1 controls ERK/MAPK kinase cascade needed in B-/T-cell differentiation and development. It is vital to protect against viral infection and the autoimmune associated proliferation of activated T-cells like RA (4). We checked its level in another dataset (GSE152641) of the whole blood RNASeq of 62 COVID-19 patients and 24 healthy controls. RASGRP1 was significantly down in COVID-19 compared to healthy control, Figure (1-C).Conclusion:SARS-CoV-2 impair B and T’s cells’ immune response through its action on RASGRP1 and that can be a novel mechanistic explanation of how the virus decreases immune cells and impair the B cell’s humoral immunity.References:[1]Sosa-Hernández VA, Torres-Ruíz J, Cervantes-Díaz R, Romero-Ramírez S, Páez-Franco JC, Meza-Sánchez DE, et al. B Cell Subsets as Severity-Associated Signatures in COVID-19 Patients. Frontiers in Immunology. 2020;11(3244).[2]Hachim MY, Hachim IY, Naeem KB, Hannawi H, Al Salmi I, Hannawi S. C-C chemokine receptor type 5 links COVID-19, rheumatoid arthritis, and Hydroxychloroquine: in silico analysis. Translational Medicine Communications. 2020;5(1):14.[3]Doorenspleet ME, Klarenbeek PL, de Hair MJ, van Schaik BD, Esveldt RE, van Kampen AH, et al. Rheumatoid arthritis synovial tissue harbours dominant B-cell and plasma-cell clones associated with autoreactivity. Ann Rheum Dis. 2014;73(4):756-62.[4]Molineros JE, Singh B, Terao C, Okada Y, Kaplan J, McDaniel B, et al. Mechanistic Characterization of RASGRP1 Variants Identifies an hnRNP-K-Regulated Transcriptional Enhancer Contributing to SLE Susceptibility. Frontiers in Immunology. 2019;10(1066).Disclosure of Interests:None declared

TAPP2 links phosphoinositide 3-kinase signaling to B-cell adhesion through interaction with the cytoskeletal protein utrophin: expression of a novel cell adhesion-promoting complex in B-cell leukemia

Blood ◽  
2009 ◽  
Vol 114 (21) ◽  
pp. 4703-4712 ◽  
Author(s):  
Jennifer L. Costantini ◽  
Samuel M. S. Cheung ◽  
Sen Hou ◽  
Hongzhao Li ◽  
Sam K. Kung ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
B Cells ◽  
B Cell ◽  
Cell Activation ◽  
Cell Types ◽  
Potential Interaction ◽  
Cytoskeletal Proteins ◽  
Lymphocytic Leukemia ◽  
Pleckstrin Homology Domain ◽  
Ph Domain

Abstract Tandem pleckstrin homology domain proteins (TAPPs) are recruited to the plasma membrane via binding to phosphoinositides produced by phosphoinositide 3-kinases (PI3Ks). Whereas PI3Ks are critical for B-cell activation, the functions of TAPP proteins in B cells are unknown. We have identified 40 potential interaction partners of TAPP2 in B cells, including proteins involved in cytoskeletal rearrangement, signal transduction and endocytic trafficking. The association of TAPP2 with the cytoskeletal proteins utrophin and syntrophin was confirmed by Western blotting. We found that TAPP2, syntrophin, and utrophin are coexpressed in normal human B cells and B-chronic lymphocytic leukemia (B-CLL) cells. TAPP2 and syntrophin expression in B-CLL was variable from patient to patient, with significantly higher expression in the more aggressive disease subset identified by zeta-chain–associated protein kinase of 70 kDa (ZAP70) expression and unmutated immunoglobulin heavy chain (IgH) genes. We examined whether TAPP can regulate cell adhesion, a known function of utrophin/syntrophin in other cell types. Expression of membrane-targeted TAPP2 enhanced B-cell adhesion to fibronectin and laminin, whereas PH domain–mutant TAPP2 inhibited adhesion. siRNA knockdown of TAPP2 or utrophin, or treatment with PI3K inhibitors, significantly inhibited adhesion. These findings identify TAPP2 as a novel link between PI3K signaling and the cytoskeleton with potential relevance for leukemia progression.

scholarly journals Administration of cardiac mesenchymal cells modulates innate immunity in the acute phase of myocardial infarction in mice

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yi Kang ◽  
Marjan Nasr ◽  
Yiru Guo ◽  
Shizuka Uchida ◽  
Tyler Weirick ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Innate Immunity ◽  
Mechanism Of Action ◽  
Cell Activation ◽  
Cell Function ◽  
Immune Cell ◽  
Mesenchymal Cell ◽  
Cell Types

Abstract Although cardiac mesenchymal cell (CMC) therapy mitigates post-infarct cardiac dysfunction, the underlying mechanisms remain unidentified. It is acknowledged that donor cells are neither appreciably retained nor meaningfully contribute to tissue regeneration—suggesting a paracrine-mediated mechanism of action. As the immune system is inextricably linked to wound healing/remodeling in the ischemically injured heart, the reparative actions of CMCs may be attributed to their immunoregulatory properties. The current study evaluated the consequences of CMC administration on post myocardial infarction (MI) immune responses in vivo and paracrine-mediated immune cell function in vitro. CMC administration preferentially elicited the recruitment of cell types associated with innate immunity (e.g., monocytes/macrophages and neutrophils). CMC paracrine signaling assays revealed enhancement in innate immune cell chemoattraction, survival, and phagocytosis, and diminished pro-inflammatory immune cell activation; data that identifies and catalogues fundamental immunomodulatory properties of CMCs, which have broad implications regarding the mechanism of action of CMCs in cardiac repair.

Human mesenchymal stem cells modulate B-cell functions

Blood ◽  
2006 ◽  
Vol 107 (1) ◽  
pp. 367-372 ◽  
Author(s):  
Anna Corcione ◽  
Federica Benvenuto ◽  
Elisa Ferretti ◽  
Debora Giunti ◽  
Valentina Cappiello ◽  
...  
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
B Cells ◽  
B Cell ◽  
Cell Function ◽  
Costimulatory Molecule ◽  
Human Mesenchymal Stem Cells ◽  
B Cell Differentiation ◽  
Major Mechanism ◽  
Cell Functions

Abstract Human mesenchymal stem cells (hMSCs) suppress T-cell and dendritic-cell function and represent a promising strategy for cell therapy of autoimmune diseases. Nevertheless, no information is currently available on the effects of hMSCs on B cells, which may have a large impact on the clinical use of these cells. hMSCs isolated from the bone marrow and B cells purified from the peripheral blood of healthy donors were cocultured with different B-cell tropic stimuli. B-cell proliferation was inhibited by hMSCs through an arrest in the G0/G1 phase of the cell cycle and not through the induction of apoptosis. A major mechanism of B-cell suppression was hMSC production of soluble factors, as indicated by transwell experiments. hMSCs inhibited B-cell differentiation because IgM, IgG, and IgA production was significantly impaired. CXCR4, CXCR5, and CCR7 B-cell expression, as well as chemotaxis to CXCL12, the CXCR4 ligand, and CXCL13, the CXCR5 ligand, were significantly down-regulated by hMSCs, suggesting that these cells affect chemotactic properties of B cells. B-cell costimulatory molecule expression and cytokine production were unaffected by hMSCs. These results further support the potential therapeutic use of hMSCs in immune-mediated disorders, including those in which B cells play a major role.

Critical Role for CD81 in B Cell Activation.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1342-1342
Author(s):  
Mrinmoy Sanyal ◽  
Rosemary Fernandez ◽  
Shoshana Levy
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Activation ◽  
Cell Function ◽  
Calcium Influx ◽  
Critical Role ◽  
B Cell Lymphoma ◽  
Free Calcium ◽  
B Cell Activation ◽  
Deficient Mice

Abstract CD81 is a component of the CD19/CD21 signaling complex in B cells. CD81 was originally discovered as target of an anti-proliferative antibody in a human B cell lymphoma. However, the exact role of CD81 in B cell function is not known. Here we studied B cells from CD81 knockout mice. We demonstrate that upon BCR induction these B cells flux higher intracellular free calcium ion; increase the phosphorylation of BCR-related proximal and distal substrates and increase their proliferation. Similarly, polyclonal activation of CD81-deficient B cells with LPS induced increased proliferation and antibody secretion. Consistent with these intrinsic B cell capabilities, CD81-deficient mice mounted significantly higher immune response upon antigenic stimulation. In addition, bone marrow perisinusoidal B cells (IgM+IgD+) capable of mounting T-independent immune responses against blood-borne pathogens were over represented in CD81-deficient mice. These cells also displayed increased calcium influx kinetics as splenic B cells and produced higher amounts of antibody after polyclonal stimulation. Taken together, these results suggest that CD81 is involved in suppressing B cell activation.

Rituximab for the Treatment of Graves’ Orbitopathy

2011 ◽  
Vol 07 (02) ◽  
pp. 130
Author(s):  
Mario Salvi ◽  
Guia Vannucchi ◽  
Paolo Beck-Peccoz ◽  
◽  
◽  
...  
Keyword(s):  
T Cell ◽  
B Cells ◽  
B Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Plasma Cells ◽  
Cell Function ◽  
Therapeutic Option ◽  
Therapeutic Benefit ◽  
Graves Orbitopathy

The contribution of B-cells to human autoimmune disease has recently been underscored because of the therapeutic benefit of B-cell depleting therapies. B-cells are involved in the production of autoantibodies, and in CD4+ T-cell activation, control of T-cell function, and inflammation through cytokine production. B-cells are also important antigen-presenting cells. Rituximab (RTX) has been used off-label in various autoimmune disorders and has been shown to effectively deplete mature and memory CD20+ B-cells, but not long-lived plasma cells. The rationale behind the use of RTX in Graves’ disease (GD) and Graves’ orbitopathy (GO) relies on its putative effect on pathogenic autoantibodies causing hyperthyroidism. RTX in patients with active GO has been shown to have a significant effect on the inflammatory activity and severity of GO. However, caution is suggested before proposing RTX as a novel therapeutic tool in this disease until randomized controlled trials are available. Should preliminary observations be confirmed, an optimal strategy for controlling the progression of GO would be to pursue B-cell depletion shortly after diagnosis, rather than only as an alternative therapeutic option when standard immunosuppression has failed.

scholarly journals KLF4 suppresses transformation of pre-B cells by ABL oncogenes

Blood ◽  
2006 ◽  
Vol 109 (2) ◽  
pp. 747-755 ◽  
Author(s):  
Michael G. Kharas ◽  
Isharat Yusuf ◽  
Vanessa M. Scarfone ◽  
Vincent W. Yang ◽  
Julia A. Segre ◽  
...  
Keyword(s):  
Cell Cycle ◽  
B Cells ◽  
Tumor Suppressor ◽  
B Cell ◽  
Cell Activation ◽  
Cell Transformation ◽  
Cell Lineage ◽  
Cell Types ◽  
B Cell Malignancies

Abstract Genes that are strongly repressed after B-cell activation are candidates for being inactivated, mutated, or repressed in B-cell malignancies. Krüppel-like factor 4 (Klf4), a gene down-regulated in activated murine B cells, is expressed at low levels in several types of human B-cell lineage lymphomas and leukemias. The human KLF4 gene has been identified as a tumor suppressor gene in colon and gastric cancer; in concordance with this, overexpression of KLF4 can suppress proliferation in several epithelial cell types. Here we investigate the effects of KLF4 on pro/pre–B-cell transformation by v-Abl and BCR-ABL, oncogenes that cause leukemia in mice and humans. We show that overexpression of KLF4 induces arrest and apoptosis in the G1 phase of the cell cycle. KLF4-mediated death, but not cell-cycle arrest, can be rescued by Bcl-XL overexpression. Transformed pro/pre-B cells expressing KLF4 display increased expression of p21CIP and decreased expression of c-Myc and cyclin D2. Tetracycline-inducible expression of KLF4 in B-cell progenitors of transgenic mice blocks transformation by BCR-ABL and depletes leukemic pre-B cells in vivo. Collectively, our work identifies KLF4 as a putative tumor suppressor in B-cell malignancies.

scholarly journals Helper T cell-dependent human B cell differentiation mediated by a mycoplasmal superantigen bridge.

1990 ◽  
Vol 171 (6) ◽  
pp. 2153-2158 ◽  
Author(s):  
J R Tumang ◽  
D N Posnett ◽  
B C Cole ◽  
M K Crow ◽  
S M Friedman
Keyword(s):  
B Cells ◽  
B Cell ◽  
Mhc Class Ii ◽  
Cell Activation ◽  
Cell Interaction ◽  
Class Ii ◽  
B Cell Differentiation ◽  
Th Cells ◽  
Human B Cells ◽  
Th Cell

Experimentally induced murine graft-vs.-host disease may be characterized by hypergammaglobulinemia, autoantibody formation, and immune complex-mediated organ system damage that mimics SLE. These autoimmune phenomena are mediated by abnormal Th-B cell cooperation, across MHC disparities, in which donor-derived allospecific Th cells recognize and interact with MHC class II antigens on the surface of recipient B cells. Microbial toxins, termed superantigens, which bind to MHC class II molecules and activate selected T cells based on TCR variable gene usage, may induce a similar form of Th-B cell interaction. In the present study, we generated and characterized human Th cell lines reactive with the Mycoplasma arthritidis superantigen (MAM). The essential observation is that resting human B cells bind MAM and present it to superantigen-reactive autologous or allogeneic Th cells, resulting in both Th cell activation and a consequent polyclonal Ig response by the superantigen-bearing B cells.

scholarly journals An IRF4-MYC-mTORC1 integrated pathway controls cell growth and the proliferative capacity of activated B cells during B cell differentiation in vivo

2021 ◽  
Author(s):  
Dillon G Patterson ◽  
Anna K Kania ◽  
Madeline J Price ◽  
James R Rose ◽  
Christopher D Scharer ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Differentiation ◽  
B Cells ◽  
Cell Growth ◽  
B Cell ◽  
Proliferative Response ◽  
Cell Activation ◽  
B Cell Differentiation ◽  
B Cell Activation

Cell division is an essential component of B cell differentiation to antibody-secreting plasma cells, with critical reprogramming occurring during the initial stages of B cell activation. However, a complete understanding of the factors that coordinate early reprogramming events in vivo remain to be determined. In this study, we examined the initial reprogramming by IRF4 in activated B cells using an adoptive transfer system and mice with a B cell-specific deletion of IRF4. IRF4-deficient B cells responding to influenza, NP-Ficoll and LPS divided, but stalled during the proliferative response. Gene expression profiling of IRF4-deficient B cells at discrete divisions revealed IRF4 was critical for inducing MYC target genes, oxidative phosphorylation, and glycolysis. Moreover, IRF4-deficient B cells maintained an inflammatory gene expression signature. Complementary chromatin accessibility analyses established a hierarchy of IRF4 activity and identified networks of dysregulated transcription factor families in IRF4-deficient B cells, including E-box binding bHLH family members. Indeed, B cells lacking IRF4 failed to fully induce Myc after stimulation and displayed aberrant cell cycle distribution. Furthermore, IRF4-deficient B cells showed reduced mTORC1 activity and failed to initiate the B cell-activation unfolded protein response and grow in cell size. Myc overexpression in IRF4-deficient was sufficient to overcome the cell growth defect. Together, these data reveal an IRF4-MYC-mTORC1 relationship critical for controlling cell growth and the proliferative response during B cell differentiation.

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