Haematopoietic PI3-kinase delta deficiency profoundly impairs regulatory T-cell biology and thereby protection against atherosclerosis

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
M Zierden ◽  
C Millarg ◽  
E.M Berghausen ◽  
L Feik ◽  
S Baldus ◽  
...  
Keyword(s):  
T Cell ◽  
B Cells ◽  
Lymph Nodes ◽  
B Cell ◽  
Foam Cell ◽  
Cell Formation ◽  
Foam Cell Formation ◽  
Funding Source ◽  
Cell Numbers

Abstract Introduction and purpose Atherosclerosis is a chronic inflammatory disease of arteries, critically involving leukocytes like macrophages as well as T and B lymphocytes. Macrophages are major drivers of disease through the ingestion of lipoproteins, foam cell formation, and secretion of inflammatory mediators. Although macrophages outnumber other leukocytes in atherosclerotic plaques, T and B cells can shape the course of disease by promoting or mitigating inflammatory responses. Leukocytes highly express the phosphoinositide 3-kinase isoform delta (PI3Kd), exerting a key role in the regulation of immune responses including activation, proliferation, differentiation, and effector functions. Therefore, PI3Kd represents a promising target for the modulation of inflammatory diseases. Consequently, we aimed to analyse the role of PI3Kd in leukocytes during atherogenesis. Methods and results To investigate the role of PI3Kd in atherosclerosis, bone marrow from PI3Kd−/− or PI3Kd+/+ mice was transplanted into LDLR−/− mice. After a 6-weeks-challenge by high fat diet, PI3Kd−/− recipient LDLR−/− mice displayed profoundly impaired CD4+ and CD8+ T-cell numbers, CD4+ T-cell activation, CD4+ effector T-cell differentiation, and proatherogenic CD4+ T-helper (Th) 1 responses in para-aortic lymph nodes and spleen compared with PI3Kd+/+ transplanted controls. Surprisingly, the net effect of PI3Kd deficiency was a substantial increase of aortic inflammation and atherosclerosis in LDLR−/− mice. Whereas plaque content and functions of macrophages including foam cell formation, efferocytosis, and cytokine secretion remained unaffected, haematopoietic PI3Kd ablation strongly reduced mature B cells and serum immunoglobulins in LDLR−/− mice. Importantly, PI3Kd deficiency severely impaired numbers and immunosuppressive functions of regulatory CD4+ T cells (Tregs) in spleen, para-aortic lymph nodes, and plaques of LDLR−/− mice. Consequently, adoptive transfer of PI3Kd+/+ Tregs fully constrained the plaque burden in PI3Kd−/− transplanted LDLR−/− mice without affecting B-cell numbers and serum immunoglobulins, whereas adoptively transferred PI3Kd−/− Tregs were unable to relieve atherosclerosis progression. Conclusions Here, we demonstrate that PI3Kd plays a crucial role in Tregs, Th1 cells, and B cells during atherogenesis. Lack of PI3Kd signalling specifically in atheroprotective Treg responses outplays its impact on proatherogenic Th1 and B-cell responses, thus leading to aggravated atherosclerosis. Hence, PI3Kd is a key regulator of Treg biology and thereby protects against atherosclerosis. Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): Marga and Walter Boll Foundation

P4142PI3-kinase delta protects against atherosclerosis progression by governing regulatory T-cell biology

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
M Zierden ◽  
C Millarg ◽  
S Baldus ◽  
S Rosenkranz ◽  
E M Berghausen ◽  
...  
Keyword(s):  
T Cell ◽  
B Lymphocytes ◽  
Foam Cell ◽  
Cell Formation ◽  
Cd4 T Cell ◽  
Foam Cell Formation ◽  
Atherosclerotic Plaques ◽  
Cell Numbers ◽  
Atherosclerosis Progression

Abstract Introduction and purpose Atherosclerosis is a chronic inflammatory disease of arteries and represents the main underlying cause of death worldwide. Macrophages are major drivers of atherosclerosis by ingestion of lipoproteins, foam cell formation, and secretion of pro-inflammatory mediators. Although macrophages outnumber other leukocytes in atherosclerotic plaques, T and B lymphocytes can shape the course of disease by promoting or mitigating inflammatory responses. Leukocytes highly express the phosphoinositide 3-kinase isoform delta (PI3Kd), exerting a key role in the regulation of immune responses including the activation, proliferation, differentiation, and effector function of lymphocytes. Since macrophages and lymphocytes are all major effectors of atherosclerosis, we aimed to understand the role of PI3Kd in these leukocytes during atherogenesis. Methods and results To investigate the role of haematopoietic PI3Kd in atherosclerosis, bone marrow from PI3Kd−/− or PI3Kd+/+ mice was transplanted into LDLR−/− mice. After 6 weeks of feeding on an atherogenic diet, PI3Kd−/− recipient LDLR−/− mice displayed significantly impaired CD4+ and CD8+ T-cell numbers, CD4+ T-cell activation, CD4+ effector T cells, and proatherogenic CD4+ T helper (Th) 1 responses in para-aortic lymph nodes and spleen compared with PI3Kd+/+ transplanted controls. Surprisingly, the net effect of PI3Kd deficiency was a substantial increase of aortic inflammation and atherosclerosis in LDLR−/− mice. Moreover, haematopoietic PI3Kd deficiency augmented macrophage accumulation in atherosclerotic plaques of LDLR−/− mice, whereas major macrophage functions including foam cell formation, efferocytosis, and cytokine secretion were unaffected by PI3Kd inactivation in these phagocytes. However, haematopoietic PI3Kd deficiency led to depletion of atheroprotective B-1 cells and reduction of proatherogenic B-2 cells in LDLR−/− mice. Moreover, haematopoietic PI3Kd deficiency caused a significant reduction of regulatory CD4+ T cells (Tregs) in plaques, para-aortic lymph nodes, and spleen of LDLR−/− mice. Furthermore, PI3Kd−/− Tregs exhibited reduced secretion of anti-inflammatory cytokines IL-10 and TGF-b as well as impaired suppression of CD4+ T-cell proliferation. Consequently, adoptive transfer of PI3Kd+/+ Tregs fully constrains the atherosclerotic burden in PI3Kd−/− transplanted LDLR−/− mice without affecting B cell numbers. Conclusions We demonstrate that PI3Kd plays a crucial role in B lymphocytes, Th1 cells, and Tregs during atherogenesis. Lack of PI3Kd signalling in atheroprotective Treg responses outplays its impact on proatherogenic Th1 responses, thus leading to aggravated atherosclerosis. Hence, PI3Kd is a key regulator of Treg biology and thereby protects against atherosclerosis progression. Acknowledgement/Funding Center for Molecular Medicine Cologne (CMMC) and the Marga and Walter Boll-Stiftung

Dynamic Role of Macrophage Sub Types for Development of Atherosclerosis and Potential Use of Herbal Immunomodulators as Imminent Therapeutic Strategy

2020 ◽  
Vol 18 ◽  
Author(s):  
Parimalanandhini Duraisamy ◽  
Sangeetha Ravi ◽  
Mahalakshmi Krishnan ◽  
Catherene M. Livya ◽  
Beulaja Manikandan ◽  
...  
Keyword(s):  
Foam Cell ◽  
Cell Formation ◽  
Atherosclerotic Lesion ◽  
Foam Cell Formation ◽  
Atherosclerosis Progression ◽  
Proinflammatory Mediators ◽  
M1 Macrophage ◽  
Tnf Α ◽  
Inflammatory Site

: Atherosclerosis, a major contributor to cardiovascular disease is a global alarm causing mortality worldwide. Being a progressive disease in the arteries, it mainly causes recruitment of monocytes to the inflammatory sites and subside pathological conditions. Monocyte-derived macrophage mainly acts in foam cell formation by engorging the LDL molecules, oxidizes it into Ox-LDL and leads to plaque deposit development. Macrophages in general differentiate, proliferate and undergo apoptosis at the inflammatory site. Frequently two subtypes of macrophages M1 and M2 has to act crucially in balancing the micro-environmental conditions of endothelial cells in arteries. The productions of proinflammatory mediators like IL-1, IL-6, TNF-α by M1 macrophage has atherogenic properties majorly produced during the early progression of atherosclerotic plaques. To counteract cytokine productions and M1-M2 balance, secondary metabolites (phytochemicals) from plants act as a therapeutic agent in alleviating atherosclerosis progression. This review summarizes the fundamental role of the macrophage in atherosclerotic lesion formation along with its plasticity characteristic as well as recent therapeutic strategies using herbal components and anti-inflammatory cytokines as potential immunomodulators.

scholarly journals Foam Cells as Therapeutic Targets in Atherosclerosis with a Focus on the Regulatory Roles of Non-Coding RNAs

2021 ◽  
Vol 22 (5) ◽  
pp. 2529
Author(s):  
Amin Javadifar ◽  
Sahar Rastgoo ◽  
Maciej Banach ◽  
Tannaz Jamialahmadi ◽  
Thomas P. Johnston ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Foam Cell ◽  
Cell Formation ◽  
Foam Cells ◽  
Foam Cell Formation ◽  
Special Focus ◽  
Lipid Uptake ◽  
Therapeutic Goals ◽  
Expression Of Genes

Atherosclerosis is a major cause of human cardiovascular disease, which is the leading cause of mortality around the world. Various physiological and pathological processes are involved, including chronic inflammation, dysregulation of lipid metabolism, development of an environment characterized by oxidative stress and improper immune responses. Accordingly, the expansion of novel targets for the treatment of atherosclerosis is necessary. In this study, we focus on the role of foam cells in the development of atherosclerosis. The specific therapeutic goals associated with each stage in the formation of foam cells and the development of atherosclerosis will be considered. Processing and metabolism of cholesterol in the macrophage is one of the main steps in foam cell formation. Cholesterol processing involves lipid uptake, cholesterol esterification and cholesterol efflux, which ultimately leads to cholesterol equilibrium in the macrophage. Recently, many preclinical studies have appeared concerning the role of non-encoding RNAs in the formation of atherosclerotic lesions. Non-encoding RNAs, especially microRNAs, are considered regulators of lipid metabolism by affecting the expression of genes involved in the uptake (e.g., CD36 and LOX1) esterification (ACAT1) and efflux (ABCA1, ABCG1) of cholesterol. They are also able to regulate inflammatory pathways, produce cytokines and mediate foam cell apoptosis. We have reviewed important preclinical evidence of their therapeutic targeting in atherosclerosis, with a special focus on foam cell formation.

Abstract 3691: Deletion of Suppressor Of Cytokine Signaling-1 in a Murine Model of Atherosclerosis Results in a Lethal Systemic Inflammation

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Christina Grothusen ◽  
Harald Schuett ◽  
Stefan Lumpe ◽  
Andre Bleich ◽  
Silke Glage ◽  
...  
Keyword(s):  
Foam Cell ◽  
Low Density Lipoprotein ◽  
Cell Formation ◽  
Density Lipoprotein ◽  
Foam Cell Formation ◽  
Cytokine Signaling ◽  
Suppressor Of Cytokine Signaling ◽  
The Impact

Introduction: Atherosclerosis is a chronic inflammatory disease of the cardiovascular system which may result in myocardial infarction and sudden cardiac death. While the role of pro-inflammatory signaling pathways in atherogenesis has been well characterized, the impact of their negative regulators, e.g. suppressor of cytokine signaling (SOCS)-1 remains to be elucidated. Deficiency of SOCS-1 leads to death 3 weeks post-partum due to an overwhelming inflammation caused by an uncontrolled signalling of interferon-gamma (IFNγ). This phenotype can be rescued by generating recombination activating gene (rag)-2, SOCS-1 double knock out (KO) mice lacking mature lymphocytes, the major source of IFNγ. Since the role of SOCS-1 during atherogenesis is unknown, we investigated the impact of a systemic SOCS-1 deficiency in the low-density lipoprotein receptor (ldlr) KO model of atherosclerosis. Material and Methods: socs-1 −/− /rag-2 −/− deficient mice were crossed with ldlr-KO animals. Mice were kept under sterile conditions on a normal chow diet. For in-vitro analyses, murine socs-1 −/− macrophages were stimulated with native low density lipoprotein (nLDL) or oxidized (ox)LDL. SOCS-1 expression was determined by quantitative PCR and western blot. Foam cell formation was determined by Oil red O staining. Results: socs-1 −/− /rag-2 −/− /ldlr −/− mice were born according to mendelian law. Tripel-KO mice showed a reduced weight and size, were more sensitive to bacterial infections and died within 120 days (N=17). Histological analyses revealed a systemic, necrotic, inflammation in Tripel-KO mice. All other genotypes developed no phenotype. In-vitro observations revealed that SOCS-1 mRNA and protein is upregulated in response to stimulation with oxLDL but not with nLDL. Foam cell formation of socs-1 −/− macrophages was increased compared to controls. Conclusion: SOCS-1 seemingly controls critical steps of atherogenesis by modulating foam cell formation in response to stimulation with oxLDL. SOCS-1 deficiency in the ldlr-KO mouse leads to a lethal inflammation. These observations suggest a critical role for SOCS-1 in the regulation of early inflammatory responses in atherogenesis.

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 Germinal center B cell development has distinctly regulated stages completed by disengagement from T cell help

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Ting-ting Zhang ◽  
David G Gonzalez ◽  
Christine M Cote ◽  
Steven M Kerfoot ◽  
Shaoli Deng ◽  
...  
Keyword(s):  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
B Cell Differentiation ◽  
B Cell Maturation ◽  
Germinal Center B Cell ◽  
T Cell Help ◽  
Dose Dependent

To reconcile conflicting reports on the role of CD40 signaling in germinal center (GC) formation, we examined the earliest stages of murine GC B cell differentiation. Peri-follicular GC precursors first expressed intermediate levels of BCL6 while co-expressing the transcription factors RelB and IRF4, the latter known to repress Bcl6 transcription. Transition of GC precursors to the BCL6hi follicular state was associated with cell division, although the number of required cell divisions was immunogen dose dependent. Potentiating T cell help or CD40 signaling in these GC precursors actively repressed GC B cell maturation and diverted their fate towards plasmablast differentiation, whereas depletion of CD4+ T cells promoted this initial transition. Thus while CD40 signaling in B cells is necessary to generate the immediate precursors of GC B cells, transition to the BCL6hi follicular state is promoted by a regional and transient diminution of T cell help.

Core 2 branching β1,6-N-acetylglucosaminyltransferase and high endothelial cell N-acetylglucosamine-6-sulfotransferase exert differential control over B- and T-lymphocyte homing to peripheral lymph nodes

Blood ◽  
2004 ◽  
Vol 104 (13) ◽  
pp. 4104-4112 ◽  
Author(s):  
Jean-Marc Gauguet ◽  
Steven D. Rosen ◽  
Jamey D. Marth ◽  
Ulrich H. von Andrian
Keyword(s):  
T Cells ◽  
Endothelial Cell ◽  
T Cell ◽  
B Cells ◽  
Lymph Nodes ◽  
B Cell ◽  
Lymphocyte Homing ◽  
High Endothelial Venules ◽  
Rolling Velocity ◽  
Peripheral Lymph

Abstract Blood-borne lymphocyte trafficking to peripheral lymph nodes (PLNs) depends on the successful initiation of rolling interactions mediated by L-selectin binding to sialomucin ligands in high endothelial venules (HEVs). Biochemical analysis of purified L-selectin ligands has identified posttranslational modifications mediated by Core2GlcNAcT-I and high endothelial cell GlcNAc-6-sulfotransferase (HECGlcNAc6ST). Consequently, lymphocyte migration to PLNs of C2GlcNAcT-I-/- and HEC-GlcNAc6ST-/- mice was reduced; however, B-cell homing was more severely compromised than T-cell migration. Accordingly, intravital microscopy (IVM) of PLN HEVs revealed a defect in B-cell tethering and increased rolling velocity (Vroll) in C2GlcNAcT-I-/- mice that was more pronounced than it was for T cells. By contrast, B- and T-cell tethering was normal in HEC-GlcNAc6ST-/- HEVs, but Vroll was accelerated, especially for B cells. The increased sensitivity of B cells to glycan deficiencies was caused by lower expression levels of L-selectin; L-selectin+/- T cells expressing L-selectin levels equivalent to those of B cells exhibited intravascular behavior similar to that of B cells. These results demonstrate distinct functions for C2GlcNAcT-I and HEC-GlcNAc6ST in the differential elaboration of HEV glycoproteins that set a threshold for the amount of L-selectin needed for lymphocyte homing. (Blood. 2004;104:4104-4112)

scholarly journals Antiviral Protection and Germinal Center Formation, But Impaired B Cell Memory in the Absence of CD19

1998 ◽  
Vol 188 (1) ◽  
pp. 145-155 ◽  
Author(s):  
Thomas Fehr ◽  
Robert C. Rickert ◽  
Bernhard Odermatt ◽  
Jürgen Roes ◽  
Klaus Rajewsky ◽  
...  
Keyword(s):  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cell Activation ◽  
Antibody Responses ◽  
B Cell Activation ◽  
Protein Antigens ◽  
Cell Memory ◽  
B Cell Memory

Coligation of CD19, a molecule expressed during all stages of B cell development except plasmacytes, lowers the threshold for B cell activation with anti-IgM by a factor of 100. The cytoplasmic tail of CD19 contains nine tyrosine residues as possible phosphorylation sites and is postulated to function as the signal transducing element for complement receptor (CR)2. Generation and analysis of CD19 gene–targeted mice revealed that T cell–dependent (TD) antibody responses to proteinaceous antigens were impaired, whereas those to T cell–independent (TI) type 2 antigens were normal or even augmented. These results are compatible with earlier complement depletion studies and the postulated function of CD19. To analyze the role of CD19 in antiviral antibody responses, we immunized CD19−/− mice with viral antigens of TI-1, TI-2, and TD type. The effect of CD19 on TI responses was more dependent on antigen dose and replicative capacity than on antigen type. CR blocking experiments confirmed the role of CD19 as B cell signal transducer for complement. In contrast to immunization with protein antigens, infection of CD19−/− mice with replicating virus led to generation of specific germinal centers, which persisted for >100 d, whereas maintenance of memory antibody titers as well as circulating memory B cells was fully dependent on CD19. Thus, our study confirms a costimulatory role of CD19 on B cells under limiting antigen conditions and indicates an important role for B cell memory.

scholarly journals Potential anti-EBV effects associated with elevated interleukin-21 levels: a case report

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Kristian Assing ◽  
Christian Nielsen ◽  
Marianne Jakobsen ◽  
Charlotte B. Andersen ◽  
Kristin Skogstrand ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Plasma Cell ◽  
Germinal Center ◽  
Plasma Cells ◽  
Cell Formation ◽  
Memory B Cells ◽  
Memory B Cell

Abstract Background Germinal center derived memory B cells and plasma cells constitute, in health and during EBV reactivation, the largest functional EBV reservoir. Hence, by reducing germinal center derived formation of memory B cells and plasma cells, EBV loads may be reduced. Animal and in-vitro models have shown that IL-21 can support memory B and plasma cell formation and thereby potentially contribute to EBV persistence. However, IL-21 also displays anti-viral effects, as mice models have shown that CD4+ T cell produced IL-21 is critical for the differentiation, function and survival of anti-viral CD8+ T cells able to contain chronic virus infections. Case presentation We present immunological work-up (flow-cytometry, ELISA and genetics) related to a patient suffering from a condition resembling B cell chronic active EBV infection, albeit with moderately elevated EBV copy numbers. No mutations in genes associated with EBV disease, common variable immunodeficiency or pertaining to the IL-21 signaling pathway (including hypermorphic IL-21 mutations) were found. Increased (> 5-fold increase 7 days post-vaccination) CD4+ T cell produced (p < 0.01) and extracellular IL-21 levels characterized our patient and coexisted with: CD8+ lymphopenia, B lymphopenia, hypogammaglobulinemia, compromised memory B cell differentiation, absent induction of B-cell lymphoma 6 protein (Bcl-6) dependent peripheral follicular helper T cells (pTFH, p = 0.01), reduced frequencies of peripheral CD4+ Bcl-6+ T cells (p = 0.05), compromised plasmablast differentiation (reduced protein vaccine responses (p < 0.001) as well as reduced Treg frequencies. Supporting IL-21 mediated suppression of pTFH formation, pTFH and CD4+ IL-21+ frequencies were strongly inversely correlated, prior to and after vaccination, in the patient and in controls, Spearman’s rho: − 0.86, p < 0.001. Conclusions To the best of our knowledge, this is the first report of elevated CD4+ IL-21+ T cell frequencies in human EBV disease. IL-21 overproduction may, apart from driving T cell mediated anti-EBV responses, disrupt germinal center derived memory B cell and plasma cell formation, and thereby contribute to EBV disease control.

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