Abstract 464: Chemokine Receptor CCR6 Expression on B Cells Augments Local IgM Production and Atheroprotection

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Prasad Srikakulapu ◽  
Chantel McSkimming ◽  
Coleen McNamara
Keyword(s):  
B Cells ◽  
B Cell ◽  
Adoptive Transfer ◽  
Chemokine Receptors ◽  
Immune Cell ◽  
Dependent Manner ◽  
Perivascular Adipose Tissue ◽  
Cell Recruitment ◽  
Cell Numbers ◽  
Atherosclerosis Development

Background: CCR6 mediates immune cell recruitment to inflammatory sites and has cell type-specific effects on diet-induced atherosclerosis in mice. Recent studies implicate the local immune responses in the adventitia/perivascular adipose tissue (PVAT) in atherosclerosis development. We have previously demonstrated that adoptive transfer of CD43 - splenocytes (B cells) into B cell deficient μMT -/- ApoE -/- mice results in reduced diet-induced atherosclerosis in a CCR6-dependent manner. Notably, there were significantly greater numbers of B cells in the aorta including PVAT of μMT -/- ApoE -/- mice which received splenic B cells from CCR6 +/+ mice compared to CCR6 -/- mice, despite no difference in B cell numbers in blood, spleen and peritoneal cavity, suggesting that CCR6 expression on B cells is important in B cell aortic homing. Production of IgM antibodies is thought to be a major mechanism whereby B cells limit atherosclerosis development. Yet whether B cells produce IgM locally in the PVAT and whether this is regulated by chemokine receptors such as CCR6 is unknown. Methods and Results: FACS experiments demonstrated high numbers of B cells available in the PVAT than aorta of young ApoE -/- (49121±11190 and 80±11; p<0.001, n=7) mice. ELISPOT experiments demonstrated significantly fewer IgM secreting cells were in the PVAT of ApoE -/- CCR6 -/- mice compared to ApoE -/- CCR6 +/+ mice (100±25 vs 850±150, p<0.05, n=5), despite no differences in IgM secreting cell numbers in spleen and bone marrow. Adoptive transfer of CD43 - splenic B cells from ApoE -/- CCR6 -/- and ApoE -/- CCR6 +/+ mice into secretory IgM deficient ApoE -/- sIgM -/- mice demonstrated significantly reduced atherosclerosis in mice that received B cells from ApoE -/- CCR6 +/+ mice compared to those that received B cells from ApoE -/- CCR6 -/- mice. Moreover, the B cells from ApoE -/- CCR6 +/+ mice attenuated atherosclerosis only when they were capable of secreting IgM. FACS data from human blood demonstrated that circulating B and T cells but not monocytes express CCR6, suggesting potential human relevance to our murine findings. Conclusion: Results provide evidence that CCR6 expression on B cells mediates B cell recruitment into aorta and/or PVAT to provide atheroprotection via IgM secretion.

scholarly journals Chemokine Receptor-6 Promotes B-1 Cell Trafficking to Perivascular Adipose Tissue, Local IgM Production and Atheroprotection

2021 ◽  
Vol 12 ◽  
Author(s):  
Prasad Srikakulapu ◽  
Aditi Upadhye ◽  
Fabrizio Drago ◽  
Heather M. Perry ◽  
Sai Vineela Bontha ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
B Cells ◽  
B Cell ◽  
Chemokine Receptor ◽  
Immune Cell ◽  
Cell Number ◽  
Cell Trafficking ◽  
Perivascular Adipose Tissue ◽  
Major Mechanism ◽  
High Level

Chemokine receptor-6 (CCR6) mediates immune cell recruitment to inflammatory sites and has cell type-specific effects on diet-induced atherosclerosis in mice. Previously we showed that loss of CCR6 in B cells resulted in loss of B cell-mediated atheroprotection, although the B cell subtype mediating this effect was unknown. Perivascular adipose tissue (PVAT) harbors high numbers of B cells including atheroprotective IgM secreting B-1 cells. Production of IgM antibodies is a major mechanism whereby B-1 cells limit atherosclerosis development. Yet whether CCR6 regulates B-1 cell number and production of IgM in the PVAT is unknown. In this present study, flow cytometry experiments demonstrated that both B-1 and B-2 cells express CCR6, albeit at a higher frequency in B-2 cells in both humans and mice. Nevertheless, B-2 cell numbers in peritoneal cavity (PerC), spleen, bone marrow and PVAT were no different in ApoE−/−CCR6−/− compared to ApoE−/−CCR6+/+ mice. In contrast, the numbers of atheroprotective IgM secreting B-1 cells were significantly lower in the PVAT of ApoE−/−CCR6−/− compared to ApoE−/−CCR6+/+ mice. Surprisingly, adoptive transfer (AT) of CD43− splenic B cells into B cell-deficient μMT−/−ApoE−/− mice repopulated the PerC with B-1 and B-2 cells and reduced atherosclerosis when transferred into ApoE−/−CCR6+/+sIgM−/− mice only when those cells expressed both CCR6 and sIgM. CCR6 expression on circulating human B cells in subjects with a high level of atherosclerosis in their coronary arteries was lower only in the putative human B-1 cells. These results provide evidence that B-1 cell CCR6 expression enhances B-1 cell number and IgM secretion in PVAT to provide atheroprotection in mice and suggest potential human relevance to our murine findings.

scholarly journals OP0136 RITUXIMAB PREVENTS THE PROGRESSION OF B-CELL DRIVEN INFLAMMATORY INFILTRATE IN THE MINOR SALIVARY GLANDS OF PRIMARY SJOGREN’S SYNDROME BY DOWNREGULATING IMMUNOLOGICAL PATHWAYS KEY IN ECTOPIC GERMINAL CENTRE ORGANIZATION: RESULTS FROM THE TRACTISS TRIAL

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 79-80
Author(s):  
E. Pontarini ◽  
F. Chowdhury ◽  
E. Sciacca ◽  
S. Grigoriadou ◽  
F. Rivellese ◽  
...  
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Histological Analysis ◽  
Immune Cell ◽  
Salivary Flow ◽  
Memory B Cells ◽  
Cell Recruitment ◽  
Immune Cell Recruitment

Background:The pathogenic role of B-cells in primary Sjögren’s Syndrome (pSS) is well established and B cell abnormalities. Because of the substantial role of B-cells, rituximab (RTX), a chimeric anti-CD20 monoclonal antibody, has been considered as a potential biologic disease modifying drug to reduce disease activity in pSS. To date, the TRial for Anti-B-Cell Therapy In patients with pSS (TRACTISS) is the largest multi-centre, placebo-controlled trial with RTX. Despite the unmet primary endpoints (30% reduction in fatigue or oral dryness, measured by visual analogue scale), RTX treated patients showed an improvement in unstimulated whole salivary flow (Bowman et al. Arthritis Rheumatol 2017;69:1440–1450).Objectives:To provide the first longitudinal transcriptomic and histological analysis at 3 time points over 48 weeks of labial SGs of pSS patients treated with RTX, in comparison to placebo, from the TRACTISS cohort.Methods:26 pSS patients randomised to RTX or placebo arm consented for labial SG biopsies at baseline, weeks 16 and 48. Patients received two 1000mg cycles of RTX or placebo at baseline and week 24. SG focus score, inflammatory aggregate area fraction, B-cells (CD20+), T-cells (CD3+), follicular dendritic cells (FDCs) (CD21+) and plasma cells (CD138+) density were assessed by H&E and immunofluorescence staining. The histological analysis was performed by digital imaging using QuPath software. RNA was extracted from matched labial SG lobules and sequenced with Illumina platform. A Principal Component Analysis (PCA) and features driving the PCA were investigated along with the most influential gene loadings. The limma-voom R pipeline was used to extract Differential Expressed Genes (DEGs) between placebo and RTX group at week 48, and gene ontology (GO) enrichment analysis performed through EnrichR to derive GO terms and pathways associated with DEGs.Results:Placebo-treated labial SGs showed a worsening of inflammation highlighted by the increment of B-cell density, development of new FDC networks, and a higher ectopic GC prevalence at week 48, compared to RTX-treated patients. No difference in total T-cells and plasma cell infiltration was observed. RTX downregulated genes involved in immune cell recruitment and inflammatory aggregate organisation (e.g. CCR7, CCL19, CD52, and PDCD1) and gene signature-based analysis of 64 immune cell types highlighted how RTX preferentially blocked class-switched- and memory-B-cells infiltration in SGs at week 48. Pathway analyses confirmed the downregulation of leukocyte migration, MHC class II antigen presentation, and T-cell co-stimulation immunological pathways, such as the CD40 receptor complex pathway. The analysis of placebo SGs transcriptomic at week 48 showed a higher expression of genes linked to ectopic GC organisation, such as CXCL13, CCL19, LTβ, in female compared to male subjects. Gender was confirmed as a key co-variate responsible for most of the variation in the PCA, together with the SG focus score and the foci area fraction.Conclusion:Treatment with RTX showed beneficial effects on labial SG inflammatory infiltration in pSS, by downregulating genes involved in immune cell recruitment, activation and organisation in ectopic GCs. Class-switched-B-cells, memory-B-cells and FDC network development were primarily affected appearing to be responsible for the lack of progression in SG B cell infiltration in the RTX compared to the placebo arm in which clear worsening of SG immunopathology over 48 weeks was detected in female patients. Although a clear association with the clinical improvement in unstimulated salivary flow observed at week 48 in RTX-treated patients could not be established given the low number of patients consenting to 3 longitudinal biopsies it is conceivable that RTX is responsible for preserving exocrine function.Acknowledgements:SJB receives a salary contribution from the NIHR Birmingham Biomedical Research Centre.Disclosure of Interests:Elena Pontarini: None declared, Farzana Chowdhury: None declared, Elisabetta Sciacca: None declared, Sofia Grigoriadou: None declared, Felice Rivellese: None declared, Davide Lucchesi: None declared, Katriona Goldmann: None declared, Liliane Fossati-Jimack: None declared, Paul Emery: None declared, Wan Fai Ng: None declared, Nurhan Sutcliffe: None declared, Colin Everett: None declared, Catherine Fernandez: None declared, Anwar Tappuni: None declared, Myles Lewis: None declared, Costantino Pitzalis: None declared, Simon J. Bowman Consultant of: SJB In 2020 I have received consultancy fees from Novartis, Abbvie and Galapagos., Michele Bombardieri: None declared

CCL19 Induced Responses Are Differentially Regulated by Atypical Chemokine Receptor CRAM and Its Classical Chemokine Receptor CCR7 in B-CLL Cells

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 4896-4896 ◽  
Author(s):  
Nathalie Burger ◽  
Andrea Haerzschel ◽  
Marion Leick ◽  
Tanja Nicole Hartmann ◽  
Julie Catusse ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Chemokine Receptor ◽  
Chemokine Receptors ◽  
Conflicts Of Interest ◽  
Maturation Stage ◽  
Lymphoid Tissues ◽  
Dependent Manner ◽  
Chemokine Ligand ◽  
Cell Layers

Abstract Abstract 4896 Introduction: Chemokines are known to play an important role in the migration and survival of B-CLL cells. The non-signalling chemokine receptors, including DARC, D6 and CCX-CKR, have recently been shown to be involved in chemokine clearance and activity regulation. The human chemokine receptor CRAM is the most recently identified member of this atypical group. CRAM is expressed on B cells in a maturation-stage dependent manner, and to variable degrees on B-CLL cells. We have recently shown that it competitively binds CCL19 and that this binding is not followed by classical chemokine responses. CCL19 and its signalling receptor CCR7 are centrally involved in B cell localisation and maturation within the secondary lymphoid tissues. CCR7 is also highly expressed on B cells from CLL patients and mediates migration towards its ligands CCL19 and CCL21 which have been shown to be present at higher concentrations in serum of patients with lymphadenopathia compared to patients without. In this study we investigate the influence of CRAM on the CCL19 dependent responses of B-CLL cells and potential correlations to clinical data with a specific focus on lymphadenopathia. Results: We demonstrate that B cells from patients with B-CLL present high, but variable degrees of CCR7 and CRAM expression. Patients with compared to patients without lymphadenopathia show a higher CRAM expression level whereas the CCR7 expression is not significantly different. In single samples showing extremly high CRAM expression the migration towards CCL19 is reduced compared to patients with lower CRAM expression. These observations confirm results in the B-CLL cell line MEC-1 showing increased migration toward CCL19 when CRAM expression is reduced using CRAM-siRNA. On the other hand, CRAM seems to be a chemokine presenter as we can show that it does not degrade its chemokine ligand but presents it on the surface of polarised cell layers. Thus, we assume that CRAM plays a role for cell migration, possibly transmigration and cell localisation within lymph nodes of B-CLL cells. Conclusions: We show that CRAM can act as an integrator of different recruitment and activation factors. It is associated to CCR7 driven recruitment of B cells by regulating CCL19 availability. Expression of CRAM differs in B cell malignancies for which CCL19 and CCL21 have already been shown to be implicated in lymphadenopathia. We therefore suggest that CRAM is an additional player in the localisation and differentiation/maturation processes of malignant B cells of B-CLL patients. Disclosures: No relevant conflicts of interest to declare.

The Atypical Chemokine Receptor CRAM Mediates CCL19 Transcytosis through Endothelial Cells and Modulates CCL19 Activation of Non-Hodgkin Lymphoma B Cells.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2672-2672
Author(s):  
Marion Leick ◽  
Julie Catusse ◽  
Meike Burger
Keyword(s):  
Endothelial Cells ◽  
B Cells ◽  
B Cell ◽  
Chemokine Receptor ◽  
Chemokine Receptors ◽  
Receptor Expression ◽  
Dependent Manner ◽  
B Cell Malignancies ◽  
Cellular Recruitment

Abstract Abstract 2672 Poster Board II-648 Introduction: Chemokines work as cellular recruitment molecules. Specific combinations of chemokines, receptors, and adhesion molecules determine which subgroups of leukocytes migrate and what their destinations are. Chemokine receptor expression and activation on malignant cells may be involved in the growth, survival and migration of cancer cells as well as in the tumor vascularisation. CCR7, by binding the chemokines CCL19 and CCL21, is centrally involved in B cell localisation to the secondary lymphoid organs and therefore implicated in lymphadenopathy of various non-hodgkin lymphomas (NHL). In addition to chemokine receptors that have been cloned and described, various orphan receptors with a chemokine receptor-like structure are still not characterized. Atypical, non-signaling chemokine receptors are members of a newly described class of receptors and have been implicated with chemokine clearance and influencing of other signalling receptors. They are consequently considered as potent immuno-modulators and as anti-inflammatory factors and are implicated in progression of cancer. Among these receptors, we are investigating the role of the orphan chemokine (C-C motif) receptor-like 2 (CCRL2), also known as CRAM, a receptor expressed on endothelial cells and B cells in a maturation stage dependent manner, but for which functions and ligands are poorly characterized so far. In an effort to elucidate the role of CRAM and its implication in neoplasias, we have focussed research on identification of ligands and the implication of CRAM in regulating B cell migration in samples from healthy donors and from non-Hodgkin lymphomas. Methods: We characterised the receptor's expression profile by flow cytometry in peripheral blood, bone marrow and lymph node sections of different B cell NHL and correlated it to expression levels of CCR7 and CXCR4. In addition, a screening for ligands was performed using radiolabelled binding assays. The role of CRAM was elucidated using various functional assays, internalisation and transcytosis experiments. Results: We show that CRAM is an alternative, but non-signaling receptor for the CCR7-activating chemokine CCL19. CRAM is constitutively recycling to and from the cell surface and internalizing the chemokine without degrading it. We found that the receptor is responsible for transcytosis of CCL19 through endothelial cell layers and subsequent presentation, a crucial step in homing of leukocytes to the lymph nodes. On the other hand, when expressed on B cells, CRAM interferes in CCL19 binding to CCR7. We thereby show that CRAM can act as an integrator of different signals, by binding different chemokines and controlling their activity toward surrounding ligands. Chemotaxis experiments demonstrate that CRAM is a negative modulator of CCL19 B cell recruitment. In addition, we have found increased expression in activated B cells, dendritic cells, and also in the B cell malignancies chronic lymphocytic leukemia (B-CLL) and pre-B cell acute lymphoblastic leukemia (pre-B ALL), and are currently evaluating CRAM as a possible prognostic marker in various B-NHLs. Conclusions: CRAM is a newly identified member of the silent or atypical chemokine receptor group, already known for modulating chemokine availability, together with D6, DARC and CCX-CKR. We have shown here that it contributes to lymphocyte recruitment into peripheral lymphoid tissue by presenting CCL19 on endothelium. It is also involved in CCR7 driven recruitment of B cells by regulating CCL19 availability. Expression of CRAM differs in B cell malignancies for which both CCR7 ligands, CCL19 and CCL21, have already been shown to be implicated in the development of lymphadenopathies. We therefore suggest that CRAM is an additional player and potential biomarker in determining outcome and development of disease. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Teriflunomide treatment reduces B cells in patients with MS

2017 ◽  
Vol 4 (6) ◽  
pp. e403 ◽  
Author(s):  
Ilaria Gandoglia ◽  
Federico Ivaldi ◽  
Alice Laroni ◽  
Federica Benvenuto ◽  
Claudio Solaro ◽  
...  
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Immune Cell ◽  
Nk Cell ◽  
Detectable Effect ◽  
Open Label ◽  
Regulatory B Cell ◽  
Cell Numbers ◽  
B Cell Subsets

Objective:To study the immunomodulatory effect of teriflunomide on innate and adaptive immune cell populations through a pilot, open-label, observational study in a cohort of patients with relapsing-remitting MS.Methods:Blood lymphocytes were isolated from 10 patients with MS before and after 3 or 12 months of treatment. Adaptive and innate immune cell subsets were analyzed by flow cytometry as follows: B cells (memory, regulatory, and mature subsets), T cells (effector and regulatory subsets), and natural killer (NK) cells (CD56dim and CD56bright subsets).Results:Our results show that teriflunomide significantly reduces absolute counts of total CD19+ B cells and mature and regulatory B-cell subsets. T cells were affected to a lesser extent, with a trend in reduction of absolute counts for both T effector CD4+ cells (Th1, Th17 and Th1/17) and T regulatory CD8+ and CD4+ cells. Teriflunomide had no detectable effect on NK-cell numbers.Conclusions:In our small cohort, teriflunomide treatment affects mainly and significantly on B-cell numbers, while having a milder effect on T-cell numbers. Larger cohorts are necessary to confirm these findings and understand the effect of teriflunomide on the functionality of these 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

Antibody Production Remains Intact Despite Loss of Bone Marrow B cells in Murine Norovirus Infected Stat1−/− Mice

2021 ◽  
Author(s):  
Daniel E Eldridge ◽  
Charlie C Hsu
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
B Cell ◽  
Cell Loss ◽  
Dependent Manner ◽  
Intestinal Epithelial ◽  
Murine Norovirus ◽  
Laboratory Mice ◽  
T And B Cells ◽  
Humoral Immune

Murine norovirus (MNV), which can be used as a model system to study human noroviruses, can infect macrophages/monocytes, neutrophils, dendritic, intestinal epithelial, T and B cells, and is highly prevalent in laboratory mice. We previouslyshowed that MNV infection significantly reduces bone marrow B cell populations in a Stat1-dependent manner. We show here that while MNV-infected Stat1−/− mice have significant losses of bone marrow B cells, splenic B cells capable of mounting an antibody response to novel antigens retain the ability to expand. We also investigated whether increased granulopoiesis after MNV infection was causing B cell loss. We found that administration of anti-G-CSF antibody inhibits the pronounced bone marrow granulopoiesis induced by MNV infection of Stat1−/− mice, but this inhibition did not rescue bone marrow B cell losses. Therefore, MNV-infected Stat1−/− mice can still mount a robust humoral immune response despite decreased bone marrow B cells. This suggests that further investigation will be needed to identify other indirect factors or mechanisms that are responsible for the bone marrow B cell losses seen after MNV infection. In addition, this work contributes to our understanding of the potential physiologic effects of Stat1-related disruptions in research mouse colonies that may be endemically infected with MNV.

scholarly journals TP53INP1 deficiency maintains murine B lymphopoiesis in aged bone marrow through redox-controlled IL-7R/STAT5 signaling

2018 ◽  
Vol 116 (1) ◽  
pp. 211-216 ◽  
Author(s):  
Bochra Zidi ◽  
Christelle Vincent-Fabert ◽  
Laurent Pouyet ◽  
Marion Seillier ◽  
Amelle Vandevelde ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Bone Marrow ◽  
B Cells ◽  
B Cell ◽  
Immune Cell ◽  
B Lymphopoiesis ◽  
Hematopoietic Stem ◽  
Chronic Oxidative Stress ◽  
The Impact ◽  
Deficient Mice

Bone marrow (BM) produces all blood and immune cells deriving from hematopoietic stem cells (HSCs). The decrease of immune cell production during aging is one of the features of immunosenescence. The impact of redox dysregulation in BM aging is still poorly understood. Here we use TP53INP1-deficient (KO) mice endowed with chronic oxidative stress to assess the influence of aging-associated redox alterations in BM homeostasis. We show that TP53INP1 deletion has no impact on aging-related accumulation of HSCs. In contrast, the aging-related contraction of the lymphoid compartment is mitigated in TP53INP1 KO mice. B cells that accumulate in old KO BM are differentiating cells that can mature into functional B cells. Importantly, this phenotype results from B cell-intrinsic events associated with defective redox control. Finally, we show that oxidative stress in aged TP53INP1-deficient mice maintains STAT5 expression and activation in early B cells, driving high Pax5 expression, which provides a molecular mechanism for maintenance of B cell development upon aging.

scholarly journals Phospholipid flippases enable precursor B cells to flee engulfment by macrophages

2018 ◽  
Vol 115 (48) ◽  
pp. 12212-12217 ◽  
Author(s):  
Katsumori Segawa ◽  
Yuichi Yanagihashi ◽  
Kyoko Yamada ◽  
Chigure Suzuki ◽  
Yasuo Uchiyama ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
B Cells ◽  
B Cell ◽  
Developmental Stages ◽  
Peritoneal Macrophages ◽  
Dependent Manner ◽  
Wild Type ◽  
Immature B Cells ◽  
T Lymphoma ◽  
Precursor B Cells

ATP11A and ATP11C, members of the P4-ATPases, are flippases that translocate phosphatidylserine (PtdSer) from the outer to inner leaflet of the plasma membrane. Using the W3 T lymphoma cell line, we found that Ca2+ ionophore-induced phospholipid scrambling caused prolonged PtdSer exposure in cells lacking both the ATP11A and ATP11C genes. ATP11C-null (ATP11C−/y) mutant mice exhibit severe B-cell deficiency. In wild-type mice, ATP11C was expressed at all B-cell developmental stages, while ATP11A was not expressed after pro−B-cell stages, indicating that ATP11C−/y early B-cell progenitors lacked plasma membrane flippases. The receptor kinases MerTK and Axl are known to be essential for the PtdSer-mediated engulfment of apoptotic cells by macrophages. MerTK−/− and Axl−/− double deficiency fully rescued the lymphopenia in the ATP11C−/y bone marrow. Many of the rescued ATP11C−/y pre-B and immature B cells exposed PtdSer, and these cells were engulfed alive by wild-type peritoneal macrophages, in a PtdSer-dependent manner. These results indicate that ATP11A and ATP11C in precursor B cells are essential for rapidly internalizing PtdSer from the cell surface to prevent the cells’ engulfment by macrophages.

scholarly journals Suppressing Synthesis of the Long Isoform of the Prolactin Receptor Is a Targeted Strategy to Prevent and Treat B Cell Malignancies

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 1135-1135
Author(s):  
Adeleh Taghi Khani ◽  
Anil Kumar ◽  
Kelly Radecki ◽  
Sung June Lee ◽  
Mary Lorenson ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Nk Cells ◽  
Malignant Transformation ◽  
Nk Cell ◽  
B Cell Lymphoma ◽  
B Cell Malignancies ◽  
Autoreactive B Cells ◽  
Cell Numbers ◽  
Bcl2 Expression

Abstract Rationale B cell malignancies, including leukemia and lymphoma, are high-risk lymphoid neoplasms. B cell malignancies predispose to autoimmune diseases including systemic lupus erythematosus (SLE) which increase the risk of developing these malignancies by &gt;5-fold. Increased prolactin (PRL) expression is known to exacerbate SLE and promote the survival of autoreactive B cells. Furthermore, PRL induces expression of the protooncogenes, MYC and BCL2, in lymphoid tissues. However, whether PRL drives the initiation and maintenance of B cell malignancies was not known. Results We first tested our hypothesis that PRL, specifically signaling through the pro-proliferative and anti-apoptotic long isoform (LF) of the PRL receptor (PRLR), drives the progression of SLE to B cell malignancies. To this end, we knocked down the LF PRLR in MRL-lpr mice predisposed to developing SLE using a splice-modulating oligomer (SMO) that blocks splicing to produce the LF PRLR without affecting the short isoforms. LF PRLR knockdown reduced splenic and circulating B cell numbers in MRL-lpr SLE mice (Fig.1a). Consistent with reduced B cell numbers, BCL2 expression in B cells of SLE mice was suppressed after LF PRLR knockdown, although MYC was unaltered (Fig.1b). By sequencing the immunoglobulin heavy chains (IGH), we compared the composition of the splenic B cell repertoire between control- and LF PRLR SMO-treated SLE mice. Control oligomer treated SLE mice accumulated splenic B cells with long complementary determining region 3 (CDR3) and B cells with non-functional IGH, characteristics of autoreactive B cells. Treatment with the LF PRLR SMO reduced both. We then measured the expression of enzymes known to induce malignant transformation of B cells, namely recombination activating genes 1/2 (RAG1/2) and activation-induced cytidine deaminase (AID), in B cells of SLE mice in controls versus LF PRLR knockdown. Importantly, LF PRLR knockdown significantly reduced RAG1 (Fig.1c) and AID expression in splenic B cells of SLE mice (Fig.1d,e). Our findings thus underscore a causal role for LF PRLR signaling in promoting of malignant transformation of B cells in SLE. Because PRL induces the expression of BCL2 and MYC in lymphocytes, we next determined whether LF PRLR promotes the survival of overt B cell malignancies that overexpress MYC and BCL2, including diffuse large B cell lymphoma (DLBCL) and B-cell acute lymphoblastic leukemia (B-ALL). We observed that B-lymphoblasts expressed significantly higher levels of PRL and the LF PRLR as compared to normal B cells (Fig.1f). We also found that higher expression of PRL at diagnosis predicts poor clinical outcome in DLBCL patients (P=0.0244), and that patients with MYC/BCL2-overexpressing ALLs with a poor prognosis had significantly higher expression of the LF PRLR compared to their MYC lowBCL2 low counterparts (P&lt;0.0001). These observations suggested that LF PRLR may modulate MYC and BCL2 expression. Knockdown of the LF PRLR using the LF PRLR SMO in MYC/BCL2-driven human B cell malignancies killed lymphoblasts and reduced MYC and BCL2 protein levels (Fig.1g). Because we previously showed that MYC-driven lymphoid malignancies are sensitive to natural killer (NK) cell-mediated immune clearance, we also examined whether LF PRLR knockdown synergized with NK cells in killing DLBCL. We found that LF PRLR knockdown enhanced NK cell-mediated killing of B-lymphoblasts (Fig.1h). Of note, no reductions were observed in NK cell viability or MYC levels within NK cells upon LF PRLR knockdown, suggesting that LF PRLR selectively kills B-lymphoblasts without negatively impacting NK homeostasis. Conclusion Our studies identify the specific knockdown of LF PRLR as a potentially safe and targeted strategy to prevent the onset of B cell malignancies in SLE patients and to treat flagrant DLBCL and B-ALL. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

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