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1.
Life Sci Alliance ; 4(11)2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34526379

RESUMO

B cell antigen receptor (BCR) signaling is initiated by protein kinases and limited by counteracting phosphatases that currently are less well studied in their regulation of BCR signaling. Here, we used the B cell line Ramos to identify and quantify human B cell signaling components. Specifically, a protein tyrosine phosphatase profiling revealed a high expression of the protein tyrosine phosphatase 1B (PTP1B) in Ramos and human naïve B cells. The loss of PTP1B leads to increased B cell activation. Through substrate trapping in combination with quantitative mass spectrometry, we identified 22 putative substrates or interactors of PTP1B. We validated Igα, CD22, PLCγ1/2, CBL, BCAP, and APLP2 as specific substrates of PTP1B in Ramos B cells. The tyrosine kinase BTK and the two adaptor proteins GRB2 and VAV1 were identified as direct binding partners and potential substrates of PTP1B. We showed that PTP1B dephosphorylates the inhibitory receptor protein CD22 at phosphotyrosine 807. We conclude that PTP1B negatively modulates BCR signaling by dephosphorylating distinct phosphotyrosines in B cell-specific receptor proteins and various downstream signaling components.


Assuntos
Proteína Tirosina Fosfatase não Receptora Tipo 1/metabolismo , Receptores de Antígenos de Linfócitos B/metabolismo , Linfócitos B/metabolismo , Linhagem Celular , Proteína Adaptadora GRB2/metabolismo , Espectrometria de Massas/métodos , Fosforilação , Ligação Proteica , Proteína Tirosina Fosfatase não Receptora Tipo 1/genética , Proteína Tirosina Fosfatase não Receptora Tipo 1/fisiologia , Proteínas Tirosina Quinases/metabolismo , Proteômica/métodos , Proteínas Proto-Oncogênicas c-vav/metabolismo , Receptores de Antígenos de Linfócitos B/fisiologia , Lectina 2 Semelhante a Ig de Ligação ao Ácido Siálico/metabolismo , Transdução de Sinais/genética
2.
Curr Oncol Rep ; 23(6): 66, 2021 04 14.
Artigo em Inglês | MEDLINE | ID: mdl-33855607

RESUMO

PURPOSE OF REVIEW: Many prognostic and predictive biomarkers have been proposed for chronic lymphocytic leukaemia (CLL). Here, we aim to discuss the evidence showing a prognostic potential for extracellular vesicles (EV) and their associated microRNAs (miRNAs). RECENT FINDINGS: EV are produced by several cells in the body as a physiological event; however, there is evidence suggesting that an elevated EV concentration is present in the circulation of CLL patients. Moreover, some studies have associated EV concentration with advanced Rai stage and unmutated CLL while others have demonstrated its potential as an independent prognostic factor for TTFT and OS. Finally, some studies have shown that CLL EV shared some dysregulated microRNAs with CLL cells and plasma. On the other hand, it was found that CLL EV has a distinctive microRNA expression profile. Until now, EV-associated miR-155 is the most studied miRNA. Despite methodological diversity and limitations in study design, unanimity in CLL EV concentration behaviour and miRNA content has been found.


Assuntos
Vesículas Extracelulares/fisiologia , Leucemia Linfocítica Crônica de Células B/mortalidade , MicroRNAs/fisiologia , Biomarcadores Tumorais , Humanos , Leucemia Linfocítica Crônica de Células B/etiologia , Leucemia Linfocítica Crônica de Células B/genética , MicroRNAs/análise , Prognóstico , Receptores de Antígenos de Linfócitos B/fisiologia
3.
Mol Biol Cell ; 31(25): 2826-2840, 2020 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-33085561

RESUMO

B lymphocytes play a critical role in adaptive immunity. On antigen binding, B cell receptors (BCR) cluster on the plasma membrane and are internalized by endocytosis. In this process, B cells capture diverse antigens in various contexts and concentrations. However, it is unclear whether the mechanism of BCR endocytosis changes in response to these factors. Here, we studied the mechanism of soluble antigen-induced BCR clustering and internalization in a cultured human B cell line using correlative superresolution fluorescence and platinum replica electron microscopy. First, by visualizing nanoscale BCR clusters, we provide direct evidence that BCR cluster size increases with F(ab')2 concentration. Next, we show that the physical mechanism of internalization switches in response to BCR cluster size. At low concentrations of antigen, B cells internalize small BCR clusters by classical clathrin-mediated endocytosis. At high antigen concentrations, when cluster size increases beyond the size of a single clathrin-coated pit, B cells retrieve receptor clusters using large invaginations of the plasma membrane capped with clathrin. At these sites, we observed early and sustained recruitment of actin and an actin polymerizing protein FCHSD2. We further show that actin recruitment is required for the efficient generation of these novel endocytic carriers and for their capture into the cytosol. We propose that in B cells, the mechanism of endocytosis switches to accommodate large receptor clusters formed when cells encounter high concentrations of soluble antigen. This mechanism is regulated by the organization and dynamics of the cortical actin cytoskeleton.


Assuntos
Endocitose/fisiologia , Receptores de Antígenos de Linfócitos B/metabolismo , Citoesqueleto de Actina/metabolismo , Actinas/metabolismo , Animais , Linfócitos B/metabolismo , Linfócitos B/fisiologia , Proteínas de Transporte/metabolismo , Linhagem Celular , Membrana Celular/metabolismo , Clatrina/metabolismo , Citoesqueleto/metabolismo , Endocitose/imunologia , Humanos , Proteínas de Membrana/metabolismo , Microscopia Eletrônica/métodos , Microscopia de Fluorescência/métodos , Transporte Proteico , Receptores de Antígenos de Linfócitos B/fisiologia , Transdução de Sinais
4.
Inflamm Res ; 69(9): 813-824, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32591922

RESUMO

PURPOSE: It paradoxically seems counter-intuitive to consider treatments that activate the immune systems as a method to treat autoimmune diseases and chronic inflammations when these inflammatory conditions are themselves manifested by dysregulated activations of the immune responses. However, according to Newton's Third-Law of fundamental physics which formally states "For every action, there is an equal and opposite reaction", it can be reasonably argued that "For every activated pro-inflammatory response, there is an opposite and intrinsic anti-inflammatory response to follow." Therefore, harnessing these intrinsic self-regulated negative-feedbacks of anti-inflammatory and tolerogenic responses by activating the immune systems represents a novel therapeutic paradigm. METHODS: This review endeavoured to examine and discuss the current clinical and experimental evidences and therapeutic potentials of activating the innate and adaptive immune systems via their classical cell receptors, namely Toll-like receptors (TLRs), T-cell receptors (TCRs), and B cell receptors (BCRs), to modulate and suppress pathogenic inflammations. RESULTS: The evidence presented in this review illustrated the therapeutic potentials and the caveats of  recent approaches and advances in harnessing this unorthodox therapeutic paradigm in the treatments of autoimmune diseases, allergic and chronic inflammations. It highlighted the promising potentials of targeting BCR-activated tolergenic responses as a new approach in this new therapeutic paradigm.


Assuntos
Doenças Autoimunes/tratamento farmacológico , Inflamação/tratamento farmacológico , Imunidade Adaptativa , Animais , Doenças Autoimunes/imunologia , Homeostase , Humanos , Tolerância Imunológica , Imunidade Inata , Imunoterapia , Inflamação/imunologia , Receptores de Antígenos de Linfócitos B/fisiologia , Receptores de Antígenos de Linfócitos T/fisiologia , Receptor 4 Toll-Like/fisiologia
5.
Front Immunol ; 11: 599, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32373113

RESUMO

Efficient generation of antibodies by B cells is one of the prerequisites of protective immunity. B cell activation by cognate antigens via B cell receptors (BCRs), or pathogen-associated molecules through pattern-recognition receptors, such as Toll-like receptors (TLRs), leads to transcriptional and metabolic changes that ultimately transform B cells into antibody-producing plasma cells or memory cells. BCR signaling and a number of steps downstream of it rely on coordinated action of cellular membranes and the actin cytoskeleton, tightly controlled by concerted action of multiple regulatory proteins, some of them exclusive to B cells. Here, we dissect the role of Missing-In-Metastasis (MIM), or Metastasis suppressor 1 (MTSS1), a cancer-associated membrane and actin cytoskeleton regulating protein, in B cell-mediated immunity by taking advantage of MIM knockout mouse strain. We show undisturbed B cell development and largely normal composition of B cell compartments in the periphery. Interestingly, we found that MIM-/- B cells are defected in BCR signaling in response to surface-bound antigens but, on the other hand, show increased metabolic activity after stimulation with LPS or CpG. In vivo, MIM knockout animals exhibit impaired IgM antibody responses to immunization with T cell-independent antigen. This study provides the first comprehensive characterization of MIM in B cells, demonstrates its regulatory role for B cell-mediated immunity, as well as proposes new functions for MIM in tuning receptor signaling and cellular metabolism, processes, which may also contribute to the poorly understood functions of MIM in cancer.


Assuntos
Linfócitos B/metabolismo , Proteínas dos Microfilamentos/fisiologia , Proteínas de Neoplasias/fisiologia , Receptores de Antígenos de Linfócitos B/fisiologia , Linfócitos T/imunologia , Animais , Formação de Anticorpos , Feminino , Sinapses Imunológicas/fisiologia , Lipopolissacarídeos/farmacologia , Ativação Linfocitária , Camundongos , Camundongos Endogâmicos C57BL , Oligodesoxirribonucleotídeos/farmacologia , Transdução de Sinais/fisiologia , Receptores Toll-Like/fisiologia
6.
Front Immunol ; 10: 2575, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31781099

RESUMO

Hyper-inflammation during acute phase and sequential hypo-inflammation during immunosuppressive phase in macrophages/monocytes lead to multiorgan failure syndrome and immune collapse of sepsis, in which toll-like receptor (TLR)-triggered inflammatory responses play a major role. Here, we reported that Siglecg deficiency attenuated TLR4-triggered pro-inflammatory cytokine production and increased anti-inflammatory cytokine [interleukin-10 [IL-10]] production in vivo and in vitro at both acute and immunosuppressive phases. Siglecg deficiency also protected mice from lipopolysaccharide (LPS)-induced sepsis with less inflammation in the lung and less tissue destruction in the spleen. Siglec-G inhibited proto-oncogene tyrosine-protein kinase Src (Src) activation via recruiting and activating tyrosine phosphatase Src homology region 2 domain-containing phosphatase-1 (SHP1) through immunoreceptor tyrosine-based inhibitory motif (ITIM) domain. Src could inhibit TLR4-induced inflammatory cytokines and promote anti-inflammatory cytokine IL-10. Mechanical investigation showed that Src could interact with and phosphorylate STAT3. Src could also promote HIF1α degradation through activating GSK3ß. Our study reveals that Siglec-G orchestrates TLR-induced inflammation, which outlines that blocking Siglec-G or activating Src may be a promising strategy for both acute and chronic inflammatory diseases.


Assuntos
Inflamação/imunologia , Lectinas/deficiência , Receptores de Antígenos de Linfócitos B/deficiência , Sepse/imunologia , Quinases da Família src/metabolismo , Animais , Citocinas/metabolismo , Ativação Enzimática , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Interleucina-10/metabolismo , Lectinas/fisiologia , Macrófagos/imunologia , Camundongos , Camundongos Endogâmicos C57BL , NF-kappa B/metabolismo , Receptores de Antígenos de Linfócitos B/fisiologia , Proteínas Tirosina Fosfatases Contendo o Domínio SH2/metabolismo , Fator de Transcrição STAT3/metabolismo , Lectinas Semelhantes a Imunoglobulina de Ligação ao Ácido Siálico , Transdução de Sinais , Receptores Toll-Like/metabolismo
7.
Arterioscler Thromb Vasc Biol ; 39(9): 1705-1714, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31315439

RESUMO

Atherosclerosis is a lipid-driven chronic inflammatory disease that is modulated by many immune cell subsets, including B cells. Therefore, targeting the inflammatory component of cardiovascular disease represents a promising therapeutic strategy. In the past years, immunotherapy has revolutionized the treatment of autoimmunity and cancer. Many of these clinically used strategies target B cells. Given the multifaceted role of B cells in atherogenesis, it is conceivable that B-cell-directed therapies can modulate disease development. Here, we review clinically available B-cell-targeted therapies and the possible benefits or detrimental effects on cardiovascular disease.


Assuntos
Linfócitos B/efeitos dos fármacos , Doenças Cardiovasculares/tratamento farmacológico , Aneurisma Aórtico/tratamento farmacológico , Aterosclerose/tratamento farmacológico , Receptor do Fator Ativador de Células B/antagonistas & inibidores , Receptor do Fator Ativador de Células B/fisiologia , Linfócitos B/fisiologia , Doenças Cardiovasculares/imunologia , Humanos , Imunização , Depleção Linfocítica , Receptores de Antígenos de Linfócitos B/antagonistas & inibidores , Receptores de Antígenos de Linfócitos B/fisiologia , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral/antagonistas & inibidores , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral/fisiologia
8.
Front Immunol ; 10: 584, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30972075

RESUMO

Oligodeoxynucleotides (ODN) containing unmethylated CpG motifs have been widely postulated as vaccine adjuvants both in mammals and teleost fish. However, to date, the effects that CpGs provoke on cells of the adaptive immune system remain mostly unexplored in fish. Given that rainbow trout (Oncorhynchus mykiss) IgM+ B cells from spleen and blood transcribe high levels of toll like receptor 9 (TLR9), the receptor responsible for CpG detection in mammals, in the current work, we have investigated the effects of CpGs on both spleen and blood IgM+ B cells from this species. CpGs were shown to exert strong proliferative effects on both spleen and blood IgM+ B cells, also increasing their survival. The fact that CpGs increase the size of IgM+ B cells, reduce the expression of surface IgM and IgD and up-regulate the number of IgM-secreting cells strongly suggest that IgM+ B cells differentiate to plasmablasts/plasma cells in response to CpG stimulation. Additionally, CpGs were shown to modulate the antigen presenting capacities of trout IgM+ B cells through an increased surface MHC II expression and transcriptional up-regulation of co-stimulatory molecules, although in this case, significant differences were observed between the effects exerted on spleen and blood cells. Similarly, differences were observed between spleen and blood IgM+ B cells when CpG stimulation was combined with B cell receptor (BCR) cross-linking. Finally, CpGs were also shown to affect innate functions of teleost IgM+ B cells such as their phagocytic capacity. These results demonstrate that CpGs regulate many adaptive and innate functions of teleost B cells, supporting their inclusion as adjuvants in novel vaccine formulations.


Assuntos
Imunidade Adaptativa/efeitos dos fármacos , Linfócitos B/efeitos dos fármacos , Imunidade Inata/efeitos dos fármacos , Imunoglobulina M/análise , Oligodesoxirribonucleotídeos/farmacologia , Animais , Linfócitos B/imunologia , Feminino , Antígenos de Histocompatibilidade Classe II/análise , Imunoglobulina M/metabolismo , Ativação Linfocitária/efeitos dos fármacos , Oncorhynchus mykiss , Fagocitose/efeitos dos fármacos , Receptores de Antígenos de Linfócitos B/fisiologia
9.
Nan Fang Yi Ke Da Xue Xue Bao ; 39(2): 253-256, 2019 02 28.
Artigo em Chinês | MEDLINE | ID: mdl-30890517

RESUMO

B cell linker (BLNK) is a key linker protein of B cell receptor (BCR) signaling pathway. BLNK participates in the regulation of PLC-γactivity and the activation of Ras pathway through its typical structure and interaction network with other proteins, and is thus widely involved in the regulation of B cell proliferation, differentiation, apoptosis and signal transduction. Furthermore, it is closely related to anaphylactic diseases, multiple sclerosis, chromosomal aneuploidy, aneuglobulinemia, B lymphocytic leukemia and lymphoma. Herein we review the structure and biological function of BLNK and its role in B cell-related diseases. BLNK can cooperate with a series of effective proteins to activate BCR signaling pathway, thereby regulating the development, maturation and function of B cells. The functional mutation of BLNK can destroy the homeostasis of B cells and affect the development and maturation of B cells, which leads to the occurrence of B cell related diseases. A comprehensive understanding of the biological functions of BLNK not only provides insights into the pathogenesis of B cell-related diseases, but also inspires new ideas and helps to find breakthroughs for the treatment of these diseases with BLNK as the therapeutic target.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/química , Proteínas Adaptadoras de Transdução de Sinal/fisiologia , Linfócitos B/fisiologia , Receptores de Antígenos de Linfócitos B/química , Receptores de Antígenos de Linfócitos B/fisiologia , Proteínas Adaptadoras de Transdução de Sinal/genética , Apoptose , Linfócitos B/citologia , Diferenciação Celular , Proliferação de Células , Humanos , Mutação , Transdução de Sinais , Relação Estrutura-Atividade
10.
Front Immunol ; 10: 225, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30873155

RESUMO

Engagement of the B cell receptor (BCR) with surface-tethered antigens leads to the formation of an immune synapse (IS), where cell signaling and antigen uptake are tightly coordinated. Centrosome re-orientation to the immune synapse has emerged as a critical regulatory step to guide the local recruitment and secretion of lysosomes, which can facilitate the extraction of immobilized antigens. This process is coupled to actin remodeling at the centrosome and at the immune synapse, which is crucial to promote cell polarity. How B cells balance both pools of actin cytoskeleton to achieve a polarized phenotype during the formation of an immune synapse is not fully understood. Here, we reveal that B cells rely on proteasome activity to achieve this task. The proteasome is a multi-catalytic protease that degrades cytosolic and nuclear proteins and its dysfunction is associated with diseases, such as cancer and autoimmunity. Our results show that resting B cells contain an active proteasome pool at the centrosome, which is required for efficient actin clearance at this level. As a result of proteasome inhibition, activated B cells do not deplete actin at the centrosome and are unable to separate the centrosome from the nucleus and thus display impaired polarity. Consequently, lysosome recruitment to the immune synapse, antigen extraction and presentation are severely compromised in B cells with diminished proteasome activity. Additionally, we found that proteasome inhibition leads to impaired actin remodeling at the immune synapse, where B cells display defective spreading responses and distribution of key signaling molecules at the synaptic membrane. Overall, our results reveal a new role for the proteasome in regulating the immune synapse of B cells, where the intracellular compartmentalization of proteasome activity controls cytoskeleton remodeling between the centrosome and synapse, with functional repercussions in antigen extraction and presentation.


Assuntos
Actinas/metabolismo , Antígenos/metabolismo , Linfócitos B/fisiologia , Sinapses Imunológicas/imunologia , Complexo de Endopeptidases do Proteassoma/fisiologia , Animais , Polaridade Celular , Centrossomo/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Receptores de Antígenos de Linfócitos B/fisiologia , Transdução de Sinais/fisiologia , Quinase Syk/fisiologia
11.
PLoS Pathog ; 15(1): e1007535, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30615681

RESUMO

MicroRNAs (miRNAs) are post-transcriptional regulatory RNAs that can modulate cell signaling and play key roles in cell state transitions. Epstein-Barr virus (EBV) expresses >40 viral miRNAs that manipulate both viral and cellular gene expression patterns and contribute to reprogramming of the host environment during infection. Here, we identified a subset of EBV miRNAs that desensitize cells to B cell receptor (BCR) stimuli, and attenuate the downstream activation of NF-kappaB or AP1-dependent transcription. Bioinformatics and pathway analysis of Ago PAR-CLIP datasets identified multiple EBV miRNA targets related to BCR signal transduction, including GRB2, SOS1, MALT1, RAC1, and INPP5D, which we validated in reporter assays. BCR signaling is critical for B cell activation, proliferation, and differentiation, and for EBV, is linked to reactivation. In functional assays, we demonstrate that EBV miR-BHRF1-2-5p contributes to the growth of latently infected B cells through GRB2 regulation. We further determined that activities of EBV miR-BHRF1-2-5p, EBV miR-BART2-5p, and a cellular miRNA, miR-17-5p, directly regulate virus reactivation triggered by BCR engagement. Our findings provide mechanistic insight into some of the key miRNA interactions impacting the proliferation of latently infected B cells and importantly, governing the latent to lytic switch.


Assuntos
Proteína Adaptadora GRB2/metabolismo , Herpesvirus Humano 4/genética , Receptores de Antígenos de Linfócitos B/fisiologia , Linfócitos B/virologia , Linhagem Celular , Infecções por Vírus Epstein-Barr/virologia , Proteína Adaptadora GRB2/fisiologia , Regulação Viral da Expressão Gênica/genética , Células HEK293 , Herpesvirus Humano 4/imunologia , Humanos , MicroRNAs/genética , NF-kappa B/metabolismo , Receptores de Antígenos de Linfócitos B/genética , Transdução de Sinais , Proteínas Virais/metabolismo , Latência Viral/genética
12.
Br J Haematol ; 183(5): 747-754, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30407619

RESUMO

Chronic lymphocytic leukaemia (CLL) is characterized by expression of CD5 on clonal B cells, and is partly driven by activated B-cell receptor (BCR) signalling. While CD5 is known to be a negative regulator of BCR signalling, it is unknown if variability in CD5 expression exists among patients and whether CLL cell CD5 expression affects CLL clinical outcomes. We assessed the extent to which CD5 expression is correlated with clinical outcomes, and whether this information adds to currently used prognostic markers. We evaluated CD5 expression from 1275 blood samples, established prognostic markers and time to event data from 423 CLL patients followed at the Duke University and Durham VA Medical Centers. CD5 median fluorescence intensity (MFI) was largely stable over time in individual patients, but ranged between 0·5 and 760 in the entire cohort. Lower CD5 MFI was significantly associated with a shorter time to first therapy. CD5 MFI, combined with established clinical and molecular prognostic markers, significantly improved risk-stratification. CD5 may affect disease outcomes by suppressing signalling through the BCR. Thus, a strategy to modulate CLL cell CD5 expression or function could be a therapeutic approach in CLL.


Assuntos
Antígenos CD5/metabolismo , Leucemia Linfocítica Crônica de Células B/terapia , Receptores de Antígenos de Linfócitos B/fisiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Linfócitos B/metabolismo , Biomarcadores Tumorais/metabolismo , Feminino , Humanos , Leucemia Linfocítica Crônica de Células B/sangue , Leucemia Linfocítica Crônica de Células B/mortalidade , Masculino , Pessoa de Meia-Idade , Prognóstico , Transdução de Sinais/fisiologia , Virginia/epidemiologia
13.
Rheumatol Int ; 38(7): 1225-1234, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29869007

RESUMO

The objective of the study was to explore the phenotype and intracellular signaling events of B cells in patients with systemic sclerosis (SSc). Peripheral blood B cell surface markers CD19 and CD22 were evaluated by flow cytometry in 23 patients with SSc and seven healthy individuals. Levels of intracellular kinases Lyn, Syk and P-Y 348 Syk along with phosphatase SHP-1 were examined with Western immunoblotting in selected patients. P-Y 822 CD22 was subsequently evaluated flow cytometrically in antigen receptor stimulated B cells. A statistically significant decrease in CD22 B cell surface expression was found in the diffuse subset of patients (median CD22 MFI ± SD was 5.90 ± 2.35 vs 10.20 ± 1.88 for patients vs healthy controls respectively; p = 0.021), while no statistically significant change was found regarding CD19. CD22 underexpression was more pronounced when interstitial lung disease (ILD) was present (median CD22 MFI ± SD was 5.90 ± 2.25 vs 10.20 ± 1.88 for patients with ILD vs healthy controls respectively; p = 0.011). CD22 phosphorylation following B cell receptor (BCR) stimulation was also found to be impaired in patients with diffuse SSc (median change in MFI ± SD was 0.28 ± 0.09 vs 0.38 ± 0.08 for patients vs healthy controls respectively; p = 0.034). Low CD22 expression was arithmetically correlated with kinase Lyn underexpression (Pearson coefficient 0.926; p = ns) in B cells from a small sample of patients. These results suggest that CD22 underexpression and impaired phosphorylation along with implications for Lyn kinase aberrations could contribute to the activated B cell phenotype in SSc.


Assuntos
Linfócitos B/metabolismo , Escleroderma Sistêmico/metabolismo , Lectina 2 Semelhante a Ig de Ligação ao Ácido Siálico/metabolismo , Transdução de Sinais , Adulto , Idoso , Idoso de 80 Anos ou mais , Antígenos CD19 , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fosforilação , Receptores de Antígenos de Linfócitos B/genética , Receptores de Antígenos de Linfócitos B/fisiologia , Escleroderma Sistêmico/genética
14.
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
15.
Cell Biol Toxicol ; 34(6): 441-457, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-29484527

RESUMO

The diversity of T and B cells in terms of their receptor sequences is huge in the vertebrate's immune system and provides broad protection against the vast diversity of pathogens. Immune repertoire is defined as the sum of T cell receptors and B cell receptors (also named immunoglobulin) that makes the organism's adaptive immune system. Before the emergence of high-throughput sequencing, the studies on immune repertoire were limited by the underdeveloped methodologies, since it was impossible to capture the whole picture by the low-throughput tools. The massive paralleled sequencing technology suits perfectly the researches on immune repertoire. In this article, we review the history of immune repertoire studies, in terms of technologies and research applications. Particularly, we discuss several aspects of challenges in this field and highlight the efforts to develop potential solutions, in the era of high-throughput sequencing of the immune repertoire.


Assuntos
Imunidade/genética , Imunidade/fisiologia , Imunoterapia/tendências , Animais , Linfócitos B , Sequenciamento de Nucleotídeos em Larga Escala/métodos , História do Século XX , História do Século XXI , Humanos , Imunoterapia/história , Receptores de Antígenos de Linfócitos B/fisiologia , Receptores de Antígenos de Linfócitos T/fisiologia , Linfócitos T
16.
J Exp Med ; 214(10): 3067-3083, 2017 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-28878001

RESUMO

Although B cell development requires expression of the B cell antigen receptor (BCR), it remains unclear whether engagement of self-antigen provides a positive impact for most B cells. Here, we show that BCR engagement by self-ligand during development in vivo results in up-regulation of the Nod-like receptor member Nod1, which recognizes the products of intestinal commensal bacteria. In anti-thymocyte/Thy-1 autoreactive BCR knock-in mice lacking self-Thy-1 ligand, immunoglobulin light chain editing occurred, generating B cells with up-regulated Nod1, including follicular and marginal zone B cells with natural autoreactivity. This BCR editing with increased Nod1 resulted in preferential survival. In normal adult mice, most mature B cells are enriched for Nod1 up-regulated cells, and signaling through Nod1 promotes competitive survival of mature B cells. These findings demonstrate a role for microbial products in promoting survival of mature B cells through up-regulated Nod1, providing a positive effect of BCR engagement on development of most B cells.


Assuntos
Linfócitos B/fisiologia , Proteínas NLR/fisiologia , Proteína Adaptadora de Sinalização NOD1/fisiologia , Receptores de Antígenos de Linfócitos B/fisiologia , Envelhecimento/fisiologia , Animais , Linfócitos B/metabolismo , Técnicas de Introdução de Genes , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Transdução de Sinais/fisiologia , Regulação para Cima
17.
J Exp Med ; 214(4): 931-941, 2017 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-28341640

RESUMO

Transient suppression of B cell function often accompanies acute viral infection. However, the molecular signaling circuitry that enforces this hyporesponsiveness is undefined. In this study, experiments identify up-regulation of the inositol phosphatase PTEN (phosphatase and tensin homolog) as primarily responsible for defects in B lymphocyte migration and antibody responses that accompany acute viral infection. B cells from mice acutely infected with gammaherpesvirus 68 are defective in BCR- and CXCR4-mediated activation of the PI3K pathway, and this, we show, is associated with increased PTEN expression. This viral infection-induced PTEN overexpression appears responsible for the suppression of antibody responses observed in infected mice because PTEN deficiency or expression of a constitutively active PI3K rescued function of B cells in infected mice. Conversely, induced overexpression of PTEN in B cells in uninfected mice led to suppression of antibody responses. Finally, we demonstrate that PTEN up-regulation is a common mechanism by which infection induces suppression of antibody responses. Collectively, these findings identify a novel role for PTEN during infection and identify regulation of the PI3K pathway, a mechanism previously shown to silence autoreactive B cells, as a key physiological target to control antibody responses.


Assuntos
Linfócitos B/imunologia , PTEN Fosfo-Hidrolase/fisiologia , Inibidores de Fosfoinositídeo-3 Quinase , Transdução de Sinais/fisiologia , Viroses/imunologia , Animais , Formação de Anticorpos , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fosfatidilinositol-3,4,5-Trifosfato 5-Fosfatases/fisiologia , Receptores de Antígenos de Linfócitos B/fisiologia , Receptores CXCR4/fisiologia
18.
J Exp Med ; 214(5): 1269-1280, 2017 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-28356391

RESUMO

Toll-like receptors (TLRs) play an important role in immune responses to pathogens by transducing signals in innate immune cells in response to microbial products. TLRs are also expressed on B cells, and TLR signaling in B cells contributes to antibody-mediated immunity and autoimmunity. The SYK tyrosine kinase is essential for signaling from the B cell antigen receptor (BCR), and thus for antibody responses. Surprisingly, we find that it is also required for B cell survival, proliferation, and cytokine secretion in response to signaling through several TLRs. We show that treatment of B cells with lipopolysaccharide, the ligand for TLR4, results in SYK activation and that this is dependent on the BCR. Furthermore, we show that B cells lacking the BCR are also defective in TLR-induced B cell activation. Our results demonstrate that TLR4 signals through two distinct pathways, one via the BCR leading to activation of SYK, ERK, and AKT and the other through MYD88 leading to activation of NF-κB.


Assuntos
Linfócitos B/fisiologia , Receptores de Antígenos de Linfócitos B/fisiologia , Quinase Syk/fisiologia , Receptor 4 Toll-Like/fisiologia , Animais , Feminino , Lipopolissacarídeos/metabolismo , Ativação Linfocitária/fisiologia , Sistema de Sinalização das MAP Quinases/fisiologia , Camundongos , NF-kappa B/fisiologia , Proteínas Proto-Oncogênicas c-akt/fisiologia , Transdução de Sinais/fisiologia
19.
Cancer Cell ; 31(1): 64-78, 2017 01 09.
Artigo em Inglês | MEDLINE | ID: mdl-28073005

RESUMO

Compared with follicular lymphoma, high PI3Kα expression was more prevalent in diffuse large B cell lymphoma (DLBCL), although both tumor types expressed substantial PI3Kδ. Simultaneous inhibition of PI3Kα and PI3Kδ dramatically enhanced the anti-tumor profile in ABC-DLBCL models compared with selective inhibition of PI3Kδ, PI3Kα, or BTK. The anti-tumor activity was associated with suppression of p-AKT and a mechanism of blocking nuclear factor-κB activation driven by CD79mut, CARD11mut, TNFAIP3mut, or MYD88mut. Inhibition of PI3Kα/δ resulted in tumor regression in an ibrutinib-resistant CD79BWT/MYD88mut patient-derived ABC-DLBCL model. Furthermore, rebound activation of BTK and AKT was identified as a mechanism limiting CD79Bmut-ABC-DLBCL to show a robust response to PI3K and BTK inhibitor monotherapies. A combination of ibrutinib with the PI3Kα/δ inhibitor copanlisib produced a sustained complete response in vivo in CD79Bmut/MYD88mut ABC-DLBCL models.


Assuntos
Classe I de Fosfatidilinositol 3-Quinases/antagonistas & inibidores , Linfoma Difuso de Grandes Células B/tratamento farmacológico , NF-kappa B/fisiologia , Inibidores de Fosfoinositídeo-3 Quinase , Proteínas Proto-Oncogênicas c-akt/fisiologia , Receptores de Antígenos de Linfócitos B/fisiologia , Adenina/análogos & derivados , Adulto , Tirosina Quinase da Agamaglobulinemia , Idoso , Animais , Linhagem Celular Tumoral , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Humanos , Linfoma Difuso de Grandes Células B/mortalidade , Linfoma Difuso de Grandes Células B/patologia , Camundongos , Camundongos Endogâmicos BALB C , Pessoa de Meia-Idade , Piperidinas , Proteínas Tirosina Quinases/antagonistas & inibidores , Pirazóis/farmacologia , Pirimidinas/farmacologia , Quinazolinas/farmacologia
20.
Hematol Oncol ; 35(2): 187-197, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26799990

RESUMO

Post-transplant lymphoproliferative disorders (PTLD) are a major problem in transplant medicine. So far, the insights into pathogenesis and potentially druggable pathways in PTLD remain scarce. We investigated a cohort of PTLD patients, consisting of both polymorphic (n = 3) and monomorphic (n = 19) B-cell lymphoproliferations. Several signalling pathways, cell of origin of PTLD and their relation to viruses were analysed by immunohistochemistry and in situ hybridization. Most PTLD were of activated B-cell origin. Two-thirds of cases showed an Epstein-Barr virus (EBV) infection of the neoplastic cells. NF-κB signalling components were present in the majority of cases, except for EBV-infected cases with latency type III lacking CD19 and upstream B-cell signalling constituents. Proteins involved in B-cell receptor signalling like Bruton tyrosine kinase were only present in a minority of cases. Phosphoinositide 3-kinase (PI3K) was expressed in 94% of cases and the druggable PI3K class 1 catalytic subunit p110 in 76%, while proteins of other signalling transduction pathways were expressed only in single cases. Unsupervised cluster analysis revealed three distinct subgroups: (i) related to EBV infection, mainly latency type III and mostly lacking CD19, upstream B-cell signalling and NF-κB constituents; (ii) mostly related to EBV infection with expression of the alternative NF-κB pathway compound RelB, CD10, and FOXP1 or MUM1; and finally, (iii) mostly unrelated to virus infection with expression of the classic NF-κB pathway compound p65. EBV and NF-κB are important drivers in PTLD in contrast to B-cell receptor signalling. The main signal transduction pathway is related to PI3K. This links PTLD to other subgroups of EBV-related lymphomas, highlighting also new potential treatment approaches. Copyright © 2016 John Wiley & Sons, Ltd.


Assuntos
Infecções por Vírus Epstein-Barr/complicações , Transtornos Linfoproliferativos/etiologia , NF-kappa B/fisiologia , Transplante de Órgãos/efeitos adversos , Receptores de Antígenos de Linfócitos B/fisiologia , Transdução de Sinais/fisiologia , Adolescente , Adulto , Criança , Análise por Conglomerados , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fenótipo , Linfócitos T Reguladores/imunologia
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