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1.
Annu Rev Immunol ; 35: 255-284, 2017 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-28142324

RESUMO

We comprehensively review memory B cells (MBCs), covering the definition of MBCs and their identities and subsets, how MBCs are generated, where they are localized, how they are maintained, and how they are reactivated. Whereas naive B cells adopt multiple fates upon stimulation, MBCs are more restricted in their responses. Evolving work reveals that the MBC compartment in mice and humans consists of distinct subpopulations with differing effector functions. We discuss the various approaches to define subsets and subset-specific roles. A major theme is the need to both deliver faster effector function upon reexposure and readapt to antigenically variant pathogens while avoiding burnout, which would be the result if all MBCs generated only terminal effector function. We discuss cell-intrinsic differences in gene expression and signaling that underlie differences in function between MBCs and naive B cells and among MBC subsets and how this leads to memory responses.


Assuntos
Subpopulações de Linfócitos B/imunologia , Linfócitos B/imunologia , Memória Imunológica , Vacinas/imunologia , Animais , Humanos , Imunidade Humoral , Ativação Linfocitária , Camundongos , Transcriptoma
2.
Nat Immunol ; 25(3): 562-575, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38200277

RESUMO

Memory B cells (MBCs) are phenotypically and functionally diverse, but their developmental origins remain undefined. Murine MBCs can be divided into subsets by expression of CD80 and PD-L2. Upon re-immunization, CD80/PD-L2 double-negative (DN) MBCs spawn germinal center B cells (GCBCs), whereas CD80/PD-L2 double-positive (DP) MBCs generate plasmablasts but not GCBCs. Using multiple approaches, including generation of an inducible GCBC-lineage reporter mouse, we demonstrate in a T cell-dependent response that DN cells formed independently of the germinal center (GC), whereas DP cells exhibited either extrafollicular (DPEX) or GCBC (DPGC) origins. Chromatin and transcriptional profiling revealed similarity of DN cells with an early memory precursor. Reciprocally, GCBC-derived DP cells shared distinct genomic features with GCBCs, while DPEX cells had hybrid features. Upon restimulation, DPEX cells were more prone to divide, while DPGC cells differentiated toward IgG1+ plasmablasts. Thus, MBC functional diversity is generated through distinct developmental histories, which imprint characteristic epigenetic patterns onto their progeny, thereby programming them for divergent functional responses.


Assuntos
Subpopulações de Linfócitos B , Animais , Camundongos , Células B de Memória , Epigenômica , Linfócitos B , Epigênese Genética
3.
Nat Immunol ; 23(1): 135-145, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34937918

RESUMO

Memory B cells (MBCs) protect the body from recurring infections. MBCs differ from their naive counterparts (NBCs) in many ways, but functional and surface marker differences are poorly characterized. In addition, although mice are the prevalent model for human immunology, information is limited concerning the nature of homology in B cell compartments. To address this, we undertook an unbiased, large-scale screening of both human and mouse MBCs for their differential expression of surface markers. By correlating the expression of such markers with extensive panels of known markers in high-dimensional flow cytometry, we comprehensively identified numerous surface proteins that are differentially expressed between MBCs and NBCs. The combination of these markers allows for the identification of MBCs in humans and mice and provides insight into their functional differences. These results will greatly enhance understanding of humoral immunity and can be used to improve immune monitoring.


Assuntos
Linfócitos B/imunologia , Memória Imunológica/imunologia , Células B de Memória/imunologia , Animais , Linfócitos B/metabolismo , Biomarcadores/metabolismo , Feminino , Citometria de Fluxo/métodos , Humanos , Imunidade Humoral/imunologia , Masculino , Células B de Memória/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Fenótipo
4.
Nat Immunol ; 21(3): 331-342, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32066950

RESUMO

Germinal center B cells (GCBCs) are critical for generating long-lived humoral immunity. How GCBCs meet the energetic challenge of rapid proliferation is poorly understood. Dividing lymphocytes typically rely on aerobic glycolysis over oxidative phosphorylation for energy. Here we report that GCBCs are exceptional among proliferating B and T cells, as they actively oxidize fatty acids (FAs) and conduct minimal glycolysis. In vitro, GCBCs had a very low glycolytic extracellular acidification rate but consumed oxygen in response to FAs. [13C6]-glucose feeding revealed that GCBCs generate significantly less phosphorylated glucose and little lactate. Further, GCBCs did not metabolize glucose into tricarboxylic acid (TCA) cycle intermediates. Conversely, [13C16]-palmitic acid labeling demonstrated that GCBCs generate most of their acetyl-CoA and acetylcarnitine from FAs. FA oxidation was functionally important, as drug-mediated and genetic dampening of FA oxidation resulted in a selective reduction of GCBCs. Hence, GCBCs appear to uncouple rapid proliferation from aerobic glycolysis.


Assuntos
Linfócitos B/metabolismo , Ácidos Graxos/metabolismo , Centro Germinativo/metabolismo , Animais , Linfócitos B/imunologia , Proliferação de Células , Metabolismo Energético , Ácidos Graxos não Esterificados/metabolismo , Expressão Gênica , Centro Germinativo/citologia , Centro Germinativo/imunologia , Glucose/metabolismo , Glicólise/genética , Técnicas In Vitro , Metaboloma , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Knockout , Oxirredução , Fosforilação Oxidativa , Consumo de Oxigênio
5.
Nat Immunol ; 20(6): 736-746, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31011187

RESUMO

B cell antigen receptor (BCR) and CD40 signaling are rewired in germinal center (GC) B cells (GCBCs) to optimize selection for high-affinity B cells. In GCBC, BCR signals are constrained, but the mechanisms are not well understood. Here we describe a GC-specific, AKT-kinase-driven negative feedback loop that attenuates BCR signaling. Mass spectrometry revealed that AKT target activity was altered in GCBCs compared with naive B cells. Retargeting was linked to differential AKT T308 and S473 phosphorylation, in turn controlled by GC-specific upregulation of phosphoinositide-dependent protein kinase PDK1 and the phosphatase PTEN. In GCBCs, AKT preferentially targeted CSK, SHP-1 and HPK1, which are negative regulators of BCR signaling. We found that phosphorylation enhances enzymatic activity of these proteins, creating a negative feedback loop that dampens upstream BCR signaling. AKT inhibition relieved this negative feedback and enhanced activation of BCR-proximal kinase LYN, as well as downstream BCR signaling molecules in GCBCs.


Assuntos
Linfócitos B/imunologia , Linfócitos B/metabolismo , Centro Germinativo/imunologia , PTEN Fosfo-Hidrolase/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptores de Antígenos de Linfócitos B/metabolismo , Transdução de Sinais , Animais , Biomarcadores , Biologia Computacional/métodos , Ativação Enzimática , Técnicas de Inativação de Genes , Humanos , Camundongos Knockout , Fosforilação , Especificidade por Substrato
6.
Immunity ; 51(6): 1088-1101.e5, 2019 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-31732168

RESUMO

The B cell response to Ehrlichia muris is dominated by plasmablasts (PBs), with few-if any-germinal centers (GCs), yet it generates protective immunoglobulin M (IgM) memory B cells (MBCs) that express the transcription factor T-bet and harbor V-region mutations. Because Ehrlichia prominently infects the liver, we investigated the nature of liver B cell response and that of the spleen. B cells within infected livers proliferated and underwent somatic hypermutation (SHM). Vh-region sequencing revealed trafficking of clones between the spleen and liver and often subsequent local clonal expansion and intraparenchymal localization of T-bet+ MBCs. T-bet+ MBCs expressed MBC subset markers CD80 and PD-L2. Many T-bet+ MBCs lacked CD11b or CD11c expression but had marginal zone (MZ) B cell phenotypes and colonized the splenic MZ, revealing T-bet+ MBC plasticity. Hence, liver and spleen are generative sites of B cell responses, and they include V-region mutation and result in liver MBC localization.


Assuntos
Linfócitos B/imunologia , Ehrlichia/imunologia , Ehrlichiose/imunologia , Imunoglobulina M/imunologia , Fígado/imunologia , Baço/imunologia , Animais , Antígeno B7-1/biossíntese , Região Variável de Imunoglobulina/genética , Memória Imunológica/imunologia , Fígado/citologia , Camundongos , Camundongos Endogâmicos C57BL , Proteína 2 Ligante de Morte Celular Programada 1/biossíntese , Hipermutação Somática de Imunoglobulina/genética , Baço/citologia , Proteínas com Domínio T/metabolismo
7.
Immunity ; 48(2): 313-326.e5, 2018 02 20.
Artigo em Inglês | MEDLINE | ID: mdl-29396161

RESUMO

Positive selection of germinal center (GC) B cells is driven by B cell receptor (BCR) affinity and requires help from follicular T helper cells. The transcription factors c-Myc and Foxo1 are critical for GC B cell selection and survival. However, how different affinity-related signaling events control these transcription factors in a manner that links to selection is unknown. Here we showed that GC B cells reprogram CD40 and BCR signaling to transduce via NF-κB and Foxo1, respectively, whereas naive B cells propagate both signals downstream of either receptor. Although either BCR or CD40 ligation induced c-Myc in naive B cells, both signals were required to highly induce c-Myc, a critical mediator of GC B cell survival and cell cycle reentry. Thus, GC B cells rewire their signaling to enhance selection stringency via a requirement for both antigen receptor- and T cell-mediated signals to induce mediators of positive selection.


Assuntos
Antígenos CD40/fisiologia , Centro Germinativo/imunologia , Proteínas Proto-Oncogênicas c-myc/biossíntese , Receptores de Antígenos de Linfócitos B/fisiologia , Transdução de Sinais/fisiologia , Animais , Proteína Forkhead Box O1/fisiologia , Sistema de Sinalização das MAP Quinases/fisiologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , NF-kappa B/fisiologia , Fosfatidilinositol 3-Quinases/fisiologia , Proteínas Proto-Oncogênicas c-akt/fisiologia , Quinase Syk/fisiologia
8.
Nat Immunol ; 15(7): 631-7, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24880458

RESUMO

Memory B cells (MBCs) are long-lived sources of rapid, isotype-switched secondary antibody-forming cell (AFC) responses. Whether MBCs homogeneously retain the ability to self-renew and terminally differentiate or if these functions are compartmentalized into MBC subsets has remained unclear. It has been suggested that antibody isotype controls MBC differentiation upon restimulation. Here we demonstrate that subcategorizing MBCs on the basis of their expression of CD80 and PD-L2, independently of isotype, identified MBC subsets with distinct functions upon rechallenge. CD80(+)PD-L2(+) MBCs differentiated rapidly into AFCs but did not generate germinal centers (GCs); conversely, CD80(-)PD-L2(-) MBCs generated few early AFCs but robustly seeded GCs. The gene-expression patterns of the subsets supported both the identity and function of these distinct MBC types. Hence, the differentiation and regeneration of MBCs are compartmentalized.


Assuntos
Subpopulações de Linfócitos B/imunologia , Antígeno B7-1/fisiologia , Isotipos de Imunoglobulinas/fisiologia , Memória Imunológica , Proteína 2 Ligante de Morte Celular Programada 1/fisiologia , Sequência de Aminoácidos , Animais , Células Produtoras de Anticorpos/fisiologia , Centro Germinativo/imunologia , Imunização , Camundongos , Camundongos Endogâmicos BALB C , Dados de Sequência Molecular , Linfócitos T/fisiologia
9.
Immunity ; 44(1): 116-130, 2016 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-26795247

RESUMO

There is little insight into or agreement about the signals that control differentiation of memory B cells (MBCs) and long-lived plasma cells (LLPCs). By performing BrdU pulse-labeling studies, we found that MBC formation preceded the formation of LLPCs in an adoptive transfer immunization system, which allowed for a synchronized Ag-specific response with homogeneous Ag-receptor, yet at natural precursor frequencies. We confirmed these observations in wild-type (WT) mice and extended them with germinal center (GC) disruption experiments and variable region gene sequencing. We thus show that the GC response undergoes a temporal switch in its output as it matures, revealing that the reaction engenders both MBC subsets with different immune effector function and, ultimately, LLPCs at largely separate points in time. These data demonstrate the kinetics of the formation of the cells that provide stable humoral immunity and therefore have implications for autoimmunity, for vaccine development, and for understanding long-term pathogen resistance.


Assuntos
Subpopulações de Linfócitos B/citologia , Linfócitos B/citologia , Diferenciação Celular/imunologia , Centro Germinativo/imunologia , Memória Imunológica/imunologia , Plasmócitos/citologia , Transferência Adotiva , Animais , Subpopulações de Linfócitos B/imunologia , Linfócitos B/imunologia , Separação Celular , ELISPOT , Citometria de Fluxo , Centro Germinativo/citologia , Imunidade Humoral/imunologia , Imuno-Histoquímica , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Transgênicos , Plasmócitos/imunologia , Fatores de Tempo
10.
Immunol Rev ; 288(1): 49-63, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30874353

RESUMO

Germinal centers (GC) are sites of rapid B-cell proliferation in response to certain types of immunization. They arise in about 1 week and can persist for several months. In GCs, B cells differentiate in a unique way and begin to undergo somatic mutation of the Ig V regions at a high rate. GC B cells (GCBC) thus undergo clonal diversification that can affect the affinity of the newly mutant B-cell receptor (BCR) for its driving antigen. Through processes that are still poorly understood, GCBC with higher affinity are selectively expanded while those with mutations that inactivate the BCR are lost. In addition, at various times during the extended GC reaction, some GCBC undergo differentiation into either long-lived memory B cells (MBC) or plasma cells. The cellular and molecular signals that govern these fate decisions are not well-understood, but are an active area of research in multiple laboratories. In this review, we cover both the history of this field and focus on recent work that has helped to elucidate the signals and molecules, such as key transcription factors, that coordinate both positive selection as well as differentiation of GCBC.


Assuntos
Linfócitos B/imunologia , Seleção Clonal Mediada por Antígeno , Receptores de Antígenos de Linfócitos B/metabolismo , Animais , Formação de Anticorpos , Diferenciação Celular , Epitopos , Centro Germinativo/imunologia , Humanos , Memória Imunológica , Ativação Linfocitária , Transdução de Sinais
11.
Eur J Immunol ; 51(7): 1774-1784, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33772778

RESUMO

Optimal vaccines are needed for sustained suppression of SARS-CoV-2 and other novel coronaviruses. Here, we developed a recombinant type 5 adenovirus vector encoding the gene for the SARS-CoV-2 S1 subunit antigen (Ad5.SARS-CoV-2-S1) for COVID-19 immunization and evaluated its immunogenicity in mice. A single immunization with Ad5.SARS-CoV-2-S1 via S.C. injection or I.N delivery induced robust antibody and cellular immune responses. Vaccination elicited significant S1-specific IgG, IgG1, and IgG2a endpoint titers as early as 2 weeks, and the induced antibodies were long lasting. I.N. and S.C. administration of Ad5.SARS-CoV-2-S1 produced S1-specific GC B cells in cervical and axillary LNs, respectively. Moreover, I.N. and S.C. immunization evoked significantly greater antigen-specific T-cell responses compared to unimmunized control groups with indications that S.C. injection was more effective than I.N. delivery in eliciting cellular immune responses. Mice vaccinated by either route demonstrated significantly increased virus-specific neutralization antibodies on weeks 8 and 12 compared to control groups, as well as BM antibody forming cells (AFC), indicative of long-term immunity. Thus, this Ad5-vectored SARS-CoV-2 vaccine candidate showed promising immunogenicity following delivery to mice by S.C. and I.N. routes of administration, supporting the further development of Ad-based vaccines against COVID-19 and other infectious diseases for sustainable global immunization programs.


Assuntos
Vacinas contra COVID-19/imunologia , COVID-19/imunologia , COVID-19/prevenção & controle , SARS-CoV-2/imunologia , Glicoproteína da Espícula de Coronavírus/imunologia , Adenoviridae/genética , Adenoviridae/imunologia , Animais , Anticorpos Neutralizantes/sangue , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/sangue , Anticorpos Antivirais/imunologia , Linfócitos B/imunologia , Imunidade Celular/imunologia , Imunidade Humoral/imunologia , Imunoglobulina G/imunologia , Camundongos , Camundongos Endogâmicos BALB C , SARS-CoV-2/genética , Glicoproteína da Espícula de Coronavírus/genética , Linfócitos T/imunologia , Vacinação
12.
Blood ; 136(24): 2774-2785, 2020 12 10.
Artigo em Inglês | MEDLINE | ID: mdl-32750113

RESUMO

Although human B cells have been extensively studied, most reports have used peripheral blood as a source. Here, we used a unique tissue resource derived from healthy organ donors to deeply characterize human B-cell compartments across multiple tissues and donors. These datasets revealed that B cells in the blood are not in homeostasis with compartments in other tissues. We found striking donor-to-donor variability in the frequencies and isotype of CD27+ memory B cells (MBCs). A comprehensive antibody-based screen revealed markers of MBC and allowed identification of novel MBC subsets with distinct functions defined according to surface expression of CD69 and CD45RB. We defined a tissue-resident MBC phenotype that was predominant in the gut but absent in blood. RNA-sequencing of MBC subsets from multiple tissues revealed a tissue-resident MBC gene signature as well as gut- and spleen-specific signatures. Overall, these studies provide novel insights into the nature and function of human B-cell compartments across multiple tissues.


Assuntos
Antígenos CD/imunologia , Subpopulações de Linfócitos B/imunologia , Memória Imunológica , Mucosa Intestinal/imunologia , Humanos
13.
J Immunol ; 197(4): 1159-68, 2016 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-27357154

RESUMO

Memory B cell responses are more rapid and of greater magnitude than are primary Ab responses. The mechanisms by which these secondary responses are eventually attenuated remain unknown. We demonstrate that the transcription factor ZBTB32 limits the rapidity and duration of Ab recall responses. ZBTB32 is highly expressed by mouse and human memory B cells but not by their naive counterparts. Zbtb32(-/-) mice mount normal primary Ab responses to T-dependent Ags. However, Zbtb32(-/-) memory B cell-mediated recall responses occur more rapidly and persist longer than do control responses. Microarray analyses demonstrate that Zbtb32(-/-) secondary bone marrow plasma cells display elevated expression of genes that promote cell cycle progression and mitochondrial function relative to wild-type controls. BrdU labeling and adoptive transfer experiments confirm more rapid production and a cell-intrinsic survival advantage of Zbtb32(-/-) secondary plasma cells relative to wild-type counterparts. ZBTB32 is therefore a novel negative regulator of Ab recall responses.


Assuntos
Subpopulações de Linfócitos B/imunologia , Linfócitos B/imunologia , Memória Imunológica/imunologia , Proteínas Repressoras/imunologia , Transferência Adotiva , Animais , Subpopulações de Linfócitos B/citologia , Linfócitos B/citologia , Diferenciação Celular/imunologia , Ensaio de Imunoadsorção Enzimática , ELISPOT , Citometria de Fluxo , Humanos , Camundongos , Camundongos Knockout , Análise de Sequência com Séries de Oligonucleotídeos , Plasmócitos/citologia , Plasmócitos/imunologia , Reação em Cadeia da Polimerase
15.
Immunol Rev ; 247(1): 52-63, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22500831

RESUMO

A hallmark of adaptive immune responses is the generation of long-lived protection after primary exposure to a pathogen. In humoral responses, this protection stems from a combination of sustained antibody titers and long-lived memory B cells (MBCs), with the former deriving from long-lived plasma cells (PCs). Both types of cell are thought to primarily derive from the germinal center (GC), a unique structure that forms during the immune response to many types of antigenic stimuli. GCs are seeded by antigen-specific B and T cells that were previously activated in the early stages of the response. The GC does not directly or immediately generate effector function; rather, it is a site of intense B-cell proliferation and cell death. GC B cells undergo both somatic hypermutation and isotype switch, and a Darwinian process very efficiently selects B cells with higher fitness for survival and expansion. GC B cells adopt a unique activation and transcriptional state, and the cells become poised to differentiate to either MBCs or PCs. Despite this general understanding of the events in the GC, the mechanisms that control both affinity selection as well as differentiation have not been well worked out. In this review, we address what is known about what determines whether GC B cells become MBCs or PCs. This is discussed in the broader context of the origins of both cell types, whether from the GC or potentially other sources. We present a model encompassing recent data from several laboratories including our own that suggests that the GC undergoes a temporal switch that alters the nature of its output from MBCs to PCs as the response progresses. We will discuss B-cell receptor signaling in the GC as it relates to potential mechanisms for affinity-based selection during the reaction.


Assuntos
Linfócitos B/citologia , Linfócitos B/imunologia , Diferenciação Celular , Centro Germinativo , Memória Imunológica , Plasmócitos/citologia , Plasmócitos/imunologia , Animais , Centro Germinativo/citologia , Centro Germinativo/imunologia , Humanos , Linfócitos T/citologia , Linfócitos T/imunologia
16.
EMBO J ; 30(13): 2705-18, 2011 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-21623346

RESUMO

The quality and quantity of BCR signals impact on cell fate decisions of B lymphocytes. Here, we describe novel gene-targeted mice, which in the context of normal VDJ recombination show hypomorphic expression of immunoglobulin µ heavy chain (µHC) mRNA levels and hence lower pre-BCR and BCR levels. Hypomorphic expression of µHC leads to augmented selection processes at all stages of B-cell development, noticeably at the expansion of pre-B cells, the positive selection of immature B lymphocytes in the bone marrow and the selection of the follicular (FO), marginal zone (MZ) and B1 B-lymphocyte compartment in peripheral lymphoid organs. Immature as well as mature FO and MZ B lymphocytes in the peripheral lymphoid organs express lower levels of the receptor for B-cell activating factor (BAFF). In addition, hypomorphic expression of the BCR favours receptor editing. Together, our results highlight the critical importance of pre-BCR and BCR receptor levels for the normal development of B-lymphocyte subpopulations in the context of intact VDJ recombination and a diverse antibody repertoire.


Assuntos
Subpopulações de Linfócitos B/fisiologia , Diferenciação Celular/imunologia , Genes de Cadeia Pesada de Imunoglobulina/fisiologia , Receptores de Antígenos de Linfócitos B/imunologia , Receptores de Antígenos de Linfócitos B/metabolismo , Alelos , Animais , Formação de Anticorpos/genética , Formação de Anticorpos/fisiologia , Receptor do Fator Ativador de Células B/metabolismo , Subpopulações de Linfócitos B/metabolismo , Células da Medula Óssea/imunologia , Células da Medula Óssea/metabolismo , Células da Medula Óssea/fisiologia , Diferenciação Celular/genética , Células Cultivadas , Genes de Cadeia Pesada de Imunoglobulina/genética , Cadeias mu de Imunoglobulina/genética , Cadeias mu de Imunoglobulina/metabolismo , Lectinas/genética , Lectinas/imunologia , Lectinas/metabolismo , Camundongos , Camundongos Transgênicos , Células Precursoras de Linfócitos B/imunologia , Células Precursoras de Linfócitos B/metabolismo , Células Precursoras de Linfócitos B/fisiologia , Receptores de Antígenos de Linfócitos B/genética , Lectinas Semelhantes a Imunoglobulina de Ligação ao Ácido Siálico
17.
J Immunol ; 188(6): 2677-86, 2012 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-22327073

RESUMO

Jun activation domain-binding protein 1 (JAB1) regulates ubiquitin-dependent protein degradation by deneddylation of cullin-based ubiquitin ligases and, therefore, plays a central role in regulating proliferation and apoptosis. Because these processes are decisive for B cell development, we investigated JAB1 functions in B cells by establishing a mouse strain with a B cell-specific JAB1 deletion. We show that JAB1 is essential for early B cell development, because the ablation of JAB1 expression blocks B cell development between the pro-B and pre-B cell stages. Furthermore, JAB1 deletion leads to aberrant expression of the apoptosis-triggering protein Fas ligand in pro-B cells. Concomitant B cell-specific overexpression of the antiapoptotic protein Bcl2 partially reverses the block in B cell development; rescued JAB1-deficient B cells reach the periphery and produce protective class-switched Abs after Borrelia burgdorferi infection. Interestingly, B cell-rescued mice exhibit no germinal centers but a striking extrafollicular plasma cell accumulation. In addition, JAB1 is essential for Bcl6 expression, a transcriptional repressor required for germinal center formation. These findings identify JAB1 as an important factor in checkpoint control during early B cell development, as well as in fate decisions in mature Ag-primed B cells.


Assuntos
Linfócitos B/citologia , Diferenciação Celular/imunologia , Proteínas de Ligação a DNA/biossíntese , Proteína Ligante Fas/biossíntese , Centro Germinativo/imunologia , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Peptídeo Hidrolases/metabolismo , Animais , Linfócitos B/imunologia , Complexo do Signalossomo COP9 , Separação Celular , Proteínas de Ligação a DNA/imunologia , Ensaio de Imunoadsorção Enzimática , Proteína Ligante Fas/imunologia , Citometria de Fluxo , Centro Germinativo/citologia , Immunoblotting , Peptídeos e Proteínas de Sinalização Intracelular/imunologia , Ativação Linfocitária/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Peptídeo Hidrolases/imunologia , Células Precursoras de Linfócitos B/imunologia , Células Precursoras de Linfócitos B/metabolismo , Proteínas Proto-Oncogênicas c-bcl-6 , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa
18.
PLoS Pathog ; 7(8): e1002172, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21852946

RESUMO

Human cytomegalovirus (HCMV), a herpesvirus, is a ubiquitously distributed pathogen that causes severe disease in immunosuppressed patients and infected newborns. Efforts are underway to prepare effective subunit vaccines and therapies including antiviral antibodies. However, current vaccine efforts are hampered by the lack of information on protective immune responses against HCMV. Characterizing the B-cell response in healthy infected individuals could aid in the design of optimal vaccines and therapeutic antibodies. To address this problem, we determined, for the first time, the B-cell repertoire against glycoprotein B (gB) of HCMV in different healthy HCMV seropositive individuals in an unbiased fashion. HCMV gB represents a dominant viral antigenic determinant for induction of neutralizing antibodies during infection and is also a component in several experimental HCMV vaccines currently being tested in humans. Our findings have revealed that the vast majority (>90%) of gB-specific antibodies secreted from B-cell clones do not have virus neutralizing activity. Most neutralizing antibodies were found to bind to epitopes not located within the previously characterized antigenic domains (AD) of gB. To map the target structures of these neutralizing antibodies, we generated a 3D model of HCMV gB and used it to identify surface exposed protein domains. Two protein domains were found to be targeted by the majority of neutralizing antibodies. Domain I, located between amino acids (aa) 133-343 of gB and domain II, a discontinuous domain, built from residues 121-132 and 344-438. Analysis of a larger panel of human sera from HCMV seropositive individuals revealed positivity rates of >50% against domain I and >90% against domain II, respectively. In accordance with previous nomenclature the domains were designated AD-4 (Dom II) and AD-5 (Dom I), respectively. Collectively, these data will contribute to optimal vaccine design and development of antibodies effective in passive immunization.


Assuntos
Anticorpos Neutralizantes/imunologia , Linfócitos B/imunologia , Citomegalovirus/imunologia , Proteínas do Envelope Viral/imunologia , Anticorpos Monoclonais , Sítios de Ligação de Anticorpos/imunologia , Infecções por Citomegalovirus/imunologia , Vacinas contra Citomegalovirus/imunologia , Epitopos/imunologia , Humanos , Estrutura Terciária de Proteína
19.
Sci Immunol ; 8(80): eadd1823, 2023 02 24.
Artigo em Inglês | MEDLINE | ID: mdl-36800413

RESUMO

Both B cell receptor (BCR) and CD40 signaling are rewired in germinal center (GC) B cells (GCBCs) to synergistically induce c-MYC and phosphorylated S6 ribosomal protein (p-S6), markers of positive selection. How interleukin-21 (IL-21), a key T follicular helper (TFH)-derived cytokine, affects GCBCs is unclear. Like BCR and CD40 signals, IL-21 receptor (IL-21R) plus CD40 signals also synergize to induce c-MYC and p-S6 in GCBCs. However, IL-21R plus CD40 stimulation differentially affects GCBC fate compared with BCR plus CD40 ligation-engaging unique molecular mechanisms-as revealed by bulk RNA sequencing (RNA-seq), single-cell RNA-seq, and flow cytometry of GCBCs in vitro and in vivo. Whereas both signal pairs induced BLIMP1 in some GCBCs, only the IL-21R/CD40 combination induced IRF4hi/CD138+ cells, indicative of plasma cell differentiation, along with CCR6+/CD38+ memory B cell precursors. These findings reveal a second positive selection pathway in GCBCs, document rewired IL-21R signaling in GCBCs, and link specific TFH- and Ag-derived signals to GCBC differentiation.


Assuntos
Linfócitos B , Centro Germinativo , Receptores de Interleucina-21 , Linfócitos B/metabolismo , Antígenos CD40 , Centro Germinativo/metabolismo , Receptores de Antígenos de Linfócitos B/metabolismo , Transdução de Sinais , Receptores de Interleucina-21/metabolismo
20.
bioRxiv ; 2023 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-37873436

RESUMO

Parkinson's disease (PD) targets some dopamine (DA) neurons more than others. Sex differences offer insights, with females more protected from DA neurodegeneration. The mammalian vesicular glutamate transporter VGLUT2 and Drosophila ortholog dVGLUT have been implicated as modulators of DA neuron resilience. However, the mechanisms by which VGLUT2/dVGLUT protects DA neurons remain unknown. We discovered DA neuron dVGLUT knockdown increased mitochondrial reactive oxygen species in a sexually dimorphic manner in response to depolarization or paraquat-induced stress, males being especially affected. DA neuron dVGLUT also reduced ATP biosynthetic burden during depolarization. RNA sequencing of VGLUT+ DA neurons in mice and flies identified candidate genes that we functionally screened to further dissect VGLUT-mediated DA neuron resilience across PD models. We discovered transcription factors modulating dVGLUT-dependent DA neuroprotection and identified dj-1ß as a regulator of sex-specific DA neuron dVGLUT expression. Overall, VGLUT protects DA neurons from PD-associated degeneration by maintaining mitochondrial health.

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