RESUMO
Antibody-producing plasma cells fuel humoral immune responses. They also contribute to autoimmune diseases such as systemic lupus erythematosus or IgA nephropathy. Interleukin-6 and the tumor necrosis factor (TNF) family ligands BAFF (B cell-activating factor) and APRIL (a proliferation-inducing ligand) participate in plasma cell survival. BAFF binds to three receptors, BAFFR (BAFF receptor), TACI (transmembrane activator and CAML interactor), and BCMA (B cell maturation antigen), while APRIL binds to TACI, BCMA, and proteoglycans. However, which ligand-receptor pair(s) are required to maintain plasma cells in different body locations remains unknown. Here, by combining mouse genetic and pharmacological approaches, we found that plasma cells required BCMA and/or TACI but not BAFFR. BCMA responded exclusively to APRIL, while TACI responded to both BAFF and APRIL, identifying three self-sufficient ligand-receptor pairs for plasma cell maintenance: BAFF-TACI, APRIL-TACI, and APRIL-BCMA. Together, these actors accounted for 90% of circulating antibodies. In BAFF-ko mice, the reduction of plasma cells upon APRIL inhibition indicated that APRIL could function in the absence of BAFF-APRIL heteromers. No evidence was found that in the absence of BCMA and TACI, binding of APRIL to proteoglycans would help maintain plasma cells. IL-6, alone or together with BAFF and APRIL, supported mainly splenic plasmablasts and plasma cells and contributed to circulating IgG but not IgA levels. In conclusion, survival factors for plasma cells can vary with body location and with the antibody isotype that plasma cells produce. To efficiently target plasma cells, in particular IgA-producing ones, dual inhibition of BAFF and APRIL is required.
Assuntos
Fator Ativador de Células B , Receptor do Fator Ativador de Células B , Antígeno de Maturação de Linfócitos B , Interleucina-6 , Proteína Transmembrana Ativadora e Interagente do CAML , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral , Animais , Fator Ativador de Células B/imunologia , Fator Ativador de Células B/metabolismo , Fator Ativador de Células B/genética , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral/metabolismo , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral/imunologia , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral/genética , Antígeno de Maturação de Linfócitos B/imunologia , Antígeno de Maturação de Linfócitos B/metabolismo , Proteína Transmembrana Ativadora e Interagente do CAML/metabolismo , Proteína Transmembrana Ativadora e Interagente do CAML/genética , Proteína Transmembrana Ativadora e Interagente do CAML/imunologia , Interleucina-6/metabolismo , Interleucina-6/imunologia , Camundongos , Receptor do Fator Ativador de Células B/metabolismo , Receptor do Fator Ativador de Células B/imunologia , Receptor do Fator Ativador de Células B/genética , Plasmócitos/imunologia , Plasmócitos/metabolismo , Camundongos Knockout , Células Produtoras de Anticorpos/imunologia , Células Produtoras de Anticorpos/metabolismo , Camundongos Endogâmicos C57BLRESUMO
B cell-activating factor (BAFF) binds the three receptors BAFF-R, BCMA, and TACI, predominantly expressed on mature B cells. Almost all B cell cancers are reported to express at least one of these receptors. Here we develop a BAFF ligand-based chimeric antigen receptor (CAR) and generate BAFF CAR-T cells using a non-viral gene delivery method. We show that BAFF CAR-T cells bind specifically to each of the three BAFF receptors and are effective at killing multiple B cell cancers, including mantle cell lymphoma (MCL), multiple myeloma (MM), and acute lymphoblastic leukemia (ALL), in vitro and in vivo using different xenograft models. Co-culture of BAFF CAR-T cells with these tumor cells results in induction of activation marker CD69, degranulation marker CD107a, and multiple proinflammatory cytokines. In summary, we report a ligand-based BAFF CAR-T capable of binding three different receptors, minimizing the potential for antigen escape in the treatment of B cell cancers.
Assuntos
Fator Ativador de Células B/genética , Receptor do Fator Ativador de Células B/genética , Antígeno de Maturação de Linfócitos B/genética , Linfoma de Célula do Manto/terapia , Mieloma Múltiplo/terapia , Leucemia-Linfoma Linfoblástico de Células Precursoras/terapia , Proteína Transmembrana Ativadora e Interagente do CAML/genética , Animais , Antígenos CD/genética , Antígenos CD/imunologia , Antígenos de Diferenciação de Linfócitos T/genética , Antígenos de Diferenciação de Linfócitos T/imunologia , Fator Ativador de Células B/imunologia , Receptor do Fator Ativador de Células B/imunologia , Antígeno de Maturação de Linfócitos B/imunologia , Linfócitos B/imunologia , Linfócitos B/patologia , Linhagem Celular Tumoral , Técnicas de Cocultura , Citotoxicidade Imunológica , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Lectinas Tipo C/genética , Lectinas Tipo C/imunologia , Ativação Linfocitária , Linfoma de Célula do Manto/genética , Linfoma de Célula do Manto/imunologia , Linfoma de Célula do Manto/patologia , Proteína 1 de Membrana Associada ao Lisossomo/genética , Proteína 1 de Membrana Associada ao Lisossomo/imunologia , Masculino , Camundongos , Mieloma Múltiplo/genética , Mieloma Múltiplo/imunologia , Mieloma Múltiplo/patologia , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/imunologia , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologia , Ligação Proteica , Receptores de Antígenos Quiméricos/genética , Receptores de Antígenos Quiméricos/imunologia , Transdução de Sinais , Linfócitos T/imunologia , Linfócitos T/transplante , Proteína Transmembrana Ativadora e Interagente do CAML/imunologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
TACI promotes T-cell independent antibody responses and plasma cell differentiation and counteracts BAFF driven B-cell activation. Mutations in TNFRSF13B (encoding TACI) are associated with common variable immunodeficiency (CVID) but are also found in 1-2% of the general population. Although not diseases causing, certain TNFRSF13B mutations predispose CVID patients to autoimmunity and lymphoproliferation. Recently, studies of TACI-deficient humans and murine models revealed novel aspects of TACI, especially its crosstalk with the TLR pathways, differential expression of TACI isoforms, and its role in the generation of autoreactive B-cells. Vice versa, these studies are instrumental for a better understanding of TACI deficiency in humans and suggest that gene dosage, mutation type, and additional clinical or laboratory abnormalities influence the relevance of TNFRSF13B variants in individual CVID patients. TACI is embedded in a complex and well-balanced system, which is vulnerable to genetic and possibly also environmental hits.
Assuntos
Imunodeficiência de Variável Comum/imunologia , Proteína Transmembrana Ativadora e Interagente do CAML/imunologia , Imunodeficiência de Variável Comum/genética , Humanos , Proteína Transmembrana Ativadora e Interagente do CAML/deficiência , Proteína Transmembrana Ativadora e Interagente do CAML/genéticaRESUMO
BAFF and APRIL regulate B cell homeostasis by binding to their three receptors BAFFR, BCMA and TACI. The complexity of this system is further increased by shedding of these three receptors; this reduces signaling due to the display of less surface receptors. Further, soluble forms, sBCMA and sTACI, were detected in body fluids and serve as biomarker in malignancies, autoimmune diseases and immunodeficiencies. sBCMA and sTACI function as decoys blocking BAFF and APRIL. BCMA is a promising therapeutic target in multiple myeloma, but sBCMA may reduce therapeutic activity of CAR T cells, bispecific antibodies, and antibody-drug conjugates. Insights into the biochemical mechanism of shedding of BCMA can be harnessed to improve BCMA-directed therapy by blocking its shedding with a γ-secretase inhibitor.
Assuntos
Antígeno de Maturação de Linfócitos B/imunologia , Biomarcadores Tumorais/imunologia , Mieloma Múltiplo/imunologia , Proteína Transmembrana Ativadora e Interagente do CAML/imunologia , Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Secretases da Proteína Precursora do Amiloide/metabolismo , Antineoplásicos/farmacologia , Antígeno de Maturação de Linfócitos B/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Humanos , Mieloma Múltiplo/tratamento farmacológico , Proteína Transmembrana Ativadora e Interagente do CAML/antagonistas & inibidoresRESUMO
Polymorphisms in TACI, a BAFF family cytokine receptor, are linked to diverse human immune disorders including common variable immunodeficiency (CVID) and systemic lupus erythematosus (SLE). Functional studies of individual variants show modest impacts on surface TACI expression and/or downstream signal transduction, indicating that relatively subtle variation in TACI activity can impact human B-cell biology. However, significant complexity underlies TACI biology, including both positive and negative regulation of physiologic and pathogenic B-cell responses. To model these contradictory events, we compared the functional impact of TACI deletion on separate models of murine SLE driven by T cell-independent and -dependent breaks in B-cell tolerance. First, we studied whether reduced surface TACI expression was sufficient to protect against progressive BAFF-mediated systemic autoimmunity. Strikingly, despite a relatively modest impact on surface TACI levels, TACI haploinsufficiency markedly reduced pathogenic RNA-associated autoantibody titers and conferred long-term protection from BAFF-driven lupus nephritis. In contrast, B cell-intrinsic TACI deletion exerted a limited impact of autoantibody generation in murine lupus characterized by spontaneous germinal center formation and T cell-dependent humoral autoimmunity. Together, these combined data provide new insights into TACI biology and highlight how TACI signals must be tightly regulated during protective and pathogenic B-cell responses.
Assuntos
Autoimunidade/genética , Fator Ativador de Células B/imunologia , Nefrite Lúpica/genética , Nefrite Lúpica/imunologia , Proteína Transmembrana Ativadora e Interagente do CAML/genética , Animais , Anticorpos Monoclonais Humanizados/farmacologia , Autoimunidade/imunologia , Fator Ativador de Células B/antagonistas & inibidores , Fator Ativador de Células B/genética , Receptor do Fator Ativador de Células B/genética , Linfócitos B/imunologia , Quimera , Feminino , Haploinsuficiência/genética , Imunossupressores/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Transdução de Sinais/genética , Transdução de Sinais/imunologia , Proteína Transmembrana Ativadora e Interagente do CAML/imunologiaRESUMO
Selective IgA deficiency (SIgAD), characterized by a serum IgA level below 0.07 mg/ml, while displaying normal serum levels of IgM and IgG antibodies, is the most frequently occurring primary immunodeficiency that reveals itself after the first four years after birth. These individuals with SIgAD are for the majority healthy and even when they are identified they are usually not investigated further or followed up. However, recent studies show that newborns and young infants already display clinical manifestations of this condition due to aberrancies in their immune defense. Interestingly, there is a huge heterogeneity in the clinical symptoms of the affected individuals. More than 50% of the affected individuals do not have clinical symptoms, while the individuals that do show clinical symptoms can suffer from mild to severe infections, allergies and autoimmune diseases. However, the reason for this heterogeneity in the manifestation of clinical symptoms of the individuals with SIgAD is unknown. Therefore, this review focusses on the characteristics of innate immune system driving T-cell independent IgA production and providing a mechanism underlying the development of SIgAD. Thereby, we focus on some important genes, including TNFRSF13B (encoding TACI), associated with SIgAD and the involvement of epigenetics, which will cover the methylation degree of TNFRSF13B, and environmental factors, including the gut microbiota, in the development of SIgAD. Currently, no specific treatment for SIgAD exists and novel therapeutic strategies could be developed based on the discussed information.
Assuntos
Deficiência de IgA/imunologia , Imunidade Inata/imunologia , Imunoglobulina A/imunologia , Proteína Transmembrana Ativadora e Interagente do CAML/imunologia , Epigênese Genética/genética , Epigênese Genética/imunologia , Microbioma Gastrointestinal/imunologia , Humanos , Deficiência de IgA/genética , Deficiência de IgA/metabolismo , Imunidade Inata/genética , Imunoglobulina A/sangue , Lactente , Recém-Nascido , Linfócitos T/imunologia , Linfócitos T/metabolismo , Proteína Transmembrana Ativadora e Interagente do CAML/genética , Proteína Transmembrana Ativadora e Interagente do CAML/metabolismoRESUMO
Antibodies that target a clinically relevant group of receptors within the tumor necrosis factor receptor superfamily (TNFRSF), including CD40 and CD95 (Fas/Apo-1), also require binding to Fc gamma receptors (FcγRs) to elicit a strong agonistic activity. This FcγR dependency largely relies on the mere cellular anchoring through the antibody's Fc domain and does not involve the engagement of FcγR signaling. The aim of this study was to elicit agonistic activity from αCD40 and αCD95 antibodies in a myeloma cell anchoring-controlled FcγR-independent manner. For this purpose, various antibody variants (IgG1, IgG1N297A, Fab2) against the TNFRSF members CD40 and CD95 were genetically fused to a single-chain-encoded B-cell activating factor (scBaff) trimer as a C-terminal myeloma-specific anchoring domain substituting for Fc domain-mediated FcγR binding. The antibody-scBaff fusion proteins were evaluated in binding studies and functional assays using tumor cell lines expressing one or more of the three receptors of Baff: BaffR, transmembrane activator and CAML interactor (TACI) and B-cell maturation antigen (BCMA). Cellular binding studies showed that the binding properties of the different domains within the fusion proteins remained fully intact in the antibody-scBaff fusion proteins. In co-culture assays of CD40- and CD95-responsive cells with BaffR, BCMA or TACI expressing anchoring cells, the antibody fusion proteins displayed strong agonism while only minor receptor stimulation was observed in co-cultures with cells without expression of Baff-interacting receptors. Thus, our CD40 and CD95 antibody fusion proteins display myeloma cell-dependent activity and promise reduced systemic side effects compared to conventional CD40 and CD95 agonists.
Assuntos
Anticorpos Monoclonais/imunologia , Fator Ativador de Células B/imunologia , Receptor do Fator Ativador de Células B/agonistas , Antígeno de Maturação de Linfócitos B/agonistas , Antígenos CD40/imunologia , Fragmentos Fab das Imunoglobulinas/imunologia , Proteínas Recombinantes de Fusão/imunologia , Proteína Transmembrana Ativadora e Interagente do CAML/agonistas , Receptor fas/imunologia , Anticorpos Monoclonais/genética , Fator Ativador de Células B/genética , Receptor do Fator Ativador de Células B/genética , Receptor do Fator Ativador de Células B/imunologia , Antígeno de Maturação de Linfócitos B/genética , Antígeno de Maturação de Linfócitos B/imunologia , Células HEK293 , Humanos , Fragmentos Fab das Imunoglobulinas/genética , Células Jurkat , Proteínas Recombinantes de Fusão/genética , Proteína Transmembrana Ativadora e Interagente do CAML/genética , Proteína Transmembrana Ativadora e Interagente do CAML/imunologiaRESUMO
The gut mounts secretory immunoglobulin A (SIgA) responses to commensal bacteria through nonredundant T cell-dependent (TD) and T cell-independent (TI) pathways that promote the establishment of mutualistic host-microbiota interactions. SIgAs from the TD pathway target penetrant bacteria, and their induction requires engagement of CD40 on B cells by CD40 ligand on T follicular helper cells. In contrast, SIgAs from the TI pathway bind a larger spectrum of bacteria, but the mechanism underpinning their production remains elusive. Here, we show that the intestinal TI pathway required CD40-independent B cell-activating signals from TACI, a receptor for the innate CD40 ligand-like factors BAFF and APRIL. TACI-induced SIgA responses targeted a fraction of the gut microbiota without shaping its overall composition. Of note, TACI was dispensable for TD induction of IgA in gut-associated lymphoid organs. Thus, BAFF/APRIL signals acting on TACI orchestrate commensal bacteria-specific SIgA responses through an intestinal TI program.
Assuntos
Linfócitos B/imunologia , Microbioma Gastrointestinal , Trato Gastrointestinal/imunologia , Trato Gastrointestinal/microbiologia , Imunoglobulina A/imunologia , Proteína Transmembrana Ativadora e Interagente do CAML/imunologia , Animais , Bactérias/genética , Imunidade nas Mucosas , Imunoglobulina A/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , RNA Ribossômico 16S/genética , Linfócitos TRESUMO
IgA nephropathy (IgAN) is a tonsil-related disease. We previously showed that oligodeoxynucleotides with CpG (CpG-ODN) and B-cell activation factor (BAFF) are involved in hyperproduction of IgA from tonsillar mononuclear cells of patients with IgAN (IgAN-TMCs). In this study, we focused on a proliferation-inducing ligand (APRIL), homologous to BAFF. IgAN-TMCs produced more APRIL than non IgAN-TMCs in the presence of both CpG-ODN and control-ODN. TLR9 expression was higher in B-cells of IgAN-TMCs, and treatment with CpG-ODN enhanced transmembrane activator and CAML interactor (TACI) expression. IgA production from IgAN-TMCs was inhibited by APRIL neutralization antibody or TACI blocking antibody, and enhanced by co-treatment of APRIL and CpG-ODN. Serum APRIL levels were higher in patients with IgAN, and decreased after tonsillectomy. These findings suggest that APRIL is involved in the hyperproduction of IgA from IgAN-TMCs, and that CpG-ODN enhanced APRIL-induced IgA production by increasing TACI expression on B-cells of IgAN-TMCs.
Assuntos
Linfócitos B/imunologia , Glomerulonefrite por IGA/genética , Tonsila Palatina/imunologia , Proteína Transmembrana Ativadora e Interagente do CAML/genética , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral/genética , Adolescente , Adulto , Idoso , Anticorpos Neutralizantes/farmacologia , Fator Ativador de Células B/genética , Fator Ativador de Células B/imunologia , Linfócitos B/efeitos dos fármacos , Linfócitos B/patologia , Regulação da Expressão Gênica , Glomerulonefrite por IGA/imunologia , Glomerulonefrite por IGA/patologia , Glomerulonefrite por IGA/cirurgia , Humanos , Leucócitos Mononucleares/efeitos dos fármacos , Leucócitos Mononucleares/imunologia , Leucócitos Mononucleares/patologia , Masculino , Pessoa de Meia-Idade , Oligodesoxirribonucleotídeos/farmacologia , Tonsila Palatina/patologia , Tonsila Palatina/cirurgia , Transdução de Sinais , Receptor Toll-Like 9/genética , Receptor Toll-Like 9/imunologia , Tonsilectomia , Proteína Transmembrana Ativadora e Interagente do CAML/antagonistas & inibidores , Proteína Transmembrana Ativadora e Interagente do CAML/imunologia , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral/antagonistas & inibidores , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral/imunologiaRESUMO
Impaired classical NF-κB pathway signaling causes reduced antibody responses to T-independent (TI) antigens. We investigated the potential reasons for defective TI responses in mice lacking the atypical inhibitory kappa B (IκB) protein of the NF-κB pathway, IκBNS. Analyses of the plasma cell compartment in vitro and in vivo after challenge with lipopolysaccharide (LPS) showed significant decreases in the frequencies of plasma cells in the absence of IκBNS. In vitro activation of B cells via the B cell receptor or via Toll-like receptor 4 revealed that early activation events were unaffected in IκBNS-deficient B cells, while proliferation was reduced compared to in similarly stimulated wildtype (wt) B cells. IκBNS-deficient B cells also displayed impaired upregulation of the transmembrane activator and calcium modulator cyclophilin ligand interactor (TACI), which is essential for TI responses, and decreased sensitivity to TACI ligands upon stimulation. Furthermore, IκBNS-deficient B cells, in contrast to wt B cells, displayed altered expression of IRF4, Blimp-1 and Pax5 upon LPS-induced differentiation, indicating impaired transcriptional regulation of plasma cell generation.
Assuntos
Diferenciação Celular , Regulação da Expressão Gênica/imunologia , Proteínas I-kappa B/deficiência , Plasmócitos/imunologia , Proteína Transmembrana Ativadora e Interagente do CAML/imunologia , Animais , Diferenciação Celular/genética , Diferenciação Celular/imunologia , Proteínas I-kappa B/imunologia , Camundongos , Camundongos Knockout , Plasmócitos/citologia , Receptor 4 Toll-Like/genética , Receptor 4 Toll-Like/imunologia , Proteína Transmembrana Ativadora e Interagente do CAML/genéticaRESUMO
Background: B-1a B cells and gut secretory IgA (SIgA) are absent in asplenic mice. Human immunoglobulin M (IgM) memory B cells, which are functionally equivalent to mouse B-1a B cells, are reduced after splenectomy. Objective: To demonstrate whether IgM memory B cells are necessary for generating IgA-secreting plasma cells in the human gut. Methods: We studied intestinal SIgA in two disorders sharing the IgM memory B cell defect, namely asplenia, and common variable immune deficiency (CVID). Results: Splenectomy was associated with reduced circulating IgM memory B cells and disappearance of intestinal IgA-secreting plasma cells. CVID patients with reduced circulating IgM memory B cells had a reduced frequency of gut IgA+ plasma cells and a disrupted film of SIgA on epithelial cells. Toll-like receptor 9 (TLR9) and transmembrane activator and calcium-modulator and cyclophilin ligand interactor (TACI) induced IgM memory B cell differentiation into IgA+ plasma cells in vitro. In the human gut, TACI-expressing IgM memory B cells were localized under the epithelial cell layer where the TACI ligand a proliferation inducing ligand (APRIL) was extremely abundant. Conclusions: Circulating IgM memory B cell depletion was associated with a defect of intestinal IgA-secreting plasma cells in asplenia and CVID. The observation that IgM memory B cells have a distinctive role in mucosal protection suggests the existence of a functional gut-spleen axis.
Assuntos
Linfócitos B/imunologia , Imunodeficiência de Variável Comum/imunologia , Imunoglobulina A Secretora/imunologia , Memória Imunológica/imunologia , Baço/imunologia , Adulto , Idoso , Células Epiteliais/imunologia , Feminino , Microbioma Gastrointestinal/imunologia , Humanos , Imunoglobulina M/imunologia , Ativação Linfocitária/imunologia , Masculino , Pessoa de Meia-Idade , Plasmócitos/imunologia , Receptor Toll-Like 9/imunologia , Proteína Transmembrana Ativadora e Interagente do CAML/imunologia , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral/imunologiaRESUMO
The delay in parasite-specific B cell development leaves people in malaria endemic areas vulnerable to repeated Plasmodium infections. Here, we investigated the role of transmembrane activator and calcium-modulator and cyclophilin ligand interactor (TACI), a molecule involved in the generation of antigen-specific antibody secreting cells, in host response to non-lethal Plasmodium yoelii infection. We found that TACI deficiency not only resulted in higher peak parasitemia levels in P. yoelii challenged mice, but also led to a delay in parasite clearance and anti-P. yoelii Merozoite Surface Protein 1(C-terminal 19-kDa fragment [rMSP-119]) protein and anti-rMSP-119 and anti-P. yoelii IgG antibody development. There was also a delay in the generation of splenic high affinity antibody secreting cells that recognize rMSP-119 protein as compared to wild-type mice. Interestingly, coinciding with the delay in parasite clearance there was a delay in the resolution of T follicular helper (TFH) cell and germinal center (GC) B cell responses in TACI -/- mice. The persistence of TFH and GC B cells is likely a result of enhanced interaction between TFH and GC B cells because inducible costimulator ligand (ICOSL) expression was significantly higher on TACI -/- GC B cells than wild-type cells. The difference in the kinetics of GC reaction appeared to also impact the emergence of plasma cells (PC) because there was a delay in the generation of TACI -/- mice PC. Nevertheless, following the recovery from P. yoelii infection, TACI -/- and wild-type mice were both protected from a rechallenge infection. Establishment of protective B cell response was responsible for the resolution of parasitemia because B cells purified from recovered TACI -/- or wild-type mice were equally protective when introduced to naïve wild-type mice prior to P. yoelii challenge. Thus, despite the increased susceptibility of TACI -/- mice to P. yoelii infection and a delay in the development of protective antibody levels, TACI -/- mice are able to clear the infection and resist rechallenge infection.
Assuntos
Centro Germinativo/imunologia , Plasmodium yoelii/imunologia , Linfócitos T Auxiliares-Indutores/imunologia , Proteína Transmembrana Ativadora e Interagente do CAML/imunologia , Animais , Linfócitos B/imunologia , Ligante Coestimulador de Linfócitos T Induzíveis/imunologia , Malária/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Plasmócitos/imunologiaRESUMO
TACI signals activate B cell proliferation, isotype switch and antibody production in both normal immunity and autoimmune states. In contrast to murine TACI, the human TACI gene undergoes alternative splicing to produce short and long isoforms (TACI-S and TACI-L). In previous studies, we showed that transduction of the short, but not long isoform, into murine B cells or human pre-B cells lacking TACI, caused them to become transcriptional and morphologically identical to plasma cells. These data suggest that the expression of different isoforms in humans provides unique controls on B cell maturation. In these studies we show that TACI-S and TACI-L form complexes in a ligand-independent manner, not dependent on a single extracellular domain. Both TACI isoforms are detectable in the endosomal cellular compartment where they co-localize with MyD88, TRAF6, and the activated 65 kDa form of TLR9, depending on a conserved intracellular TACI sequence. In contrast to TACI-L expressing cells, or cells bearing both isoforms, TACI-S binds ligands BAFF and APRIL with substantially greater affinity and promotes enhanced NF-kB activation. Using isoform-specific monoclonal antibodies, we show that while TACI-L is predominant as a surface receptor surface on human B cells, significantly more TACI-S is noted in the intracellular compartment and also in marginal zone, isotype switched and plasmablast in resting B cells. TACI-S is increased in tonsillar B cells and also in the intracellular compartment of activated peripheral B cells. These data shows that alternative splicing of the human TACI gene leads to two isoforms both of which intersect with MyD88 and TRAF6 and form complexes with TLR9, but the two isoforms have different ligand binding capacities, subcellular locations and activation capabilities.
Assuntos
Fator Ativador de Células B/imunologia , Plasmócitos/imunologia , Proteína Transmembrana Ativadora e Interagente do CAML/imunologia , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral/imunologia , Animais , Fator Ativador de Células B/genética , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Camundongos , Fator 88 de Diferenciação Mieloide/genética , Fator 88 de Diferenciação Mieloide/imunologia , Plasmócitos/citologia , Isoformas de Proteínas/genética , Isoformas de Proteínas/imunologia , Fator 6 Associado a Receptor de TNF/genética , Fator 6 Associado a Receptor de TNF/imunologia , Receptor Toll-Like 9/genética , Receptor Toll-Like 9/imunologia , Proteína Transmembrana Ativadora e Interagente do CAML/genética , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral/genéticaRESUMO
BACKGROUND: Members of TNFα superfamily, A proliferation inducing ligand (APRIL), B-cell activating factor (BAFF) and Transmembrane activator and calcium cyclophylin interactor (TACI) are main regulators of B-cell function. The aim of this study was to evaluate concentrations of APRIL, BAFF and soluble TACI (sTACI) receptor in septic patients compared to healthy controls and compare concentrations of these biomarkers depending on sepsis severity and outcome. MATERIALS AND METHODS: A total of 115 septic patients and 30 healthy volunteers were included and concentrations of APRIL, BAFF and sTACI were determined in all subjects at the admission (ELISA R&D Systems tests). Concentrations of these biomarkers in function of sepsis severity (sepsis nâ¯=â¯94 and septic shock nâ¯=â¯21) and outcome (lethal nâ¯=â¯40, recovery nâ¯=â¯75) were tested, as well as correlations with APACHE II and SOFA scores, immunoglobulins, complement, PCT and CRP concentrations. RESULTS: Concentrations of all three biomarkers were significantly increased in septic patients compared to controls (AUCAPRILâ¯=â¯0.982, AUCBAFFâ¯=â¯0.873, AUCsTACIâ¯=â¯0.683). Higher concentrations of APRIL and sTACI (pâ¯=â¯0.033, pâ¯=â¯0.037), and lower concentrations of BAFF (pâ¯=â¯0.005) were observed in patients with septic shock compared to sepsis. BAFF concentrations correlated positively with IgM, C3 and C4 levels. sTACI and APRIL were shown to be predictors of lethal outcome (pâ¯=â¯0.003, pâ¯=â¯0.049). CONCLUSIONS: Concentrations of observedTNFα superfamily members are significantly increased in septic patients, confirming their role in sepsis pathogenesis.Higher concentrations of anti-inflammatory sTACI receptor correlated with severity of sepsis and poorer prognosis, thus potentially indicating domination of anti-inflammatory response in septic patients with worse outcome.
Assuntos
Fator Ativador de Células B , Sepse , Proteína Transmembrana Ativadora e Interagente do CAML , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Fator Ativador de Células B/sangue , Fator Ativador de Células B/imunologia , Biomarcadores/sangue , Complemento C3/imunologia , Complemento C3/metabolismo , Complemento C4/imunologia , Complemento C4/metabolismo , Feminino , Humanos , Imunoglobulina M/sangue , Imunoglobulina M/imunologia , Masculino , Pessoa de Meia-Idade , Sepse/sangue , Sepse/imunologia , Sepse/mortalidade , Proteína Transmembrana Ativadora e Interagente do CAML/sangue , Proteína Transmembrana Ativadora e Interagente do CAML/imunologia , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral/sangue , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral/imunologia , Fator de Necrose Tumoral alfa/sangue , Fator de Necrose Tumoral alfa/imunologiaRESUMO
BACKGROUND: The B cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL) are tumor necrosis factor family members that regulate B cell maturation, proliferation, survival and function. We have previously shown that blood-stage Plasmodium falciparum hemozoin (HZ) can act as a T-independent antigen (TI Ag) that induces the production of specific IgG to soluble crude P. falciparum Ag through the BAFF pathway. However, we have not yet clarified whether HZ need APRIL signaling in the TI response. Here, we aimed to clarify whether both BAFF and APRIL signaling pathways play roles in HZ induction of specific antibody production without T-cell help. METHODS: Normal monocytes alone or co-cultured with naïve B cells were stimulated by HZ (10⯵M) in vitro. Naïve B cell cultures, with HZ alone or with exogenous recombinant BAFF (rBAFF) and recombinant APRIL (rAPRIL) plus recombinant IL-4 (rIL-4) for 6 and 10â¯days were used as controls to investigate activation of B cells. At various times, the levels of sBAFF, sAPRIL, and HZ-specific IgG in the culture supernatants were assessed by enzyme-linked immunosorbent assay. The BAFF and APRIL expression levels on the HZ-stimulated monocytes and their specific receptors on activated B cells, including the BAFF receptor (BAFF-R), the transmembrane activator and calcium-modulator and cyclophilin ligand interactor (TACI) and the B cell maturation antigen (BCMA), were determined by flow cytometry. mRNA expression levels for the receptors were validated using Real-Time quantitative PCR. RESULTS: HZ-activated monocytes released sBAFF and sAPRIL during the 72â¯h stimulation period. Increased mRNA encoding of their cognate receptors, BAFF-R, TACI, and BCMA, and increased HZ-specific IgG levels were also observed in HZ induction within the monocyte and B cell co-culture. The experiments under control conditions revealed that HZ alone could induce B cell culture to produce a small amount of the specific IgG compared with those in medium alone or rBAFFâ¯+â¯rAPRILâ¯+â¯rIL-4. CONCLUSION: Taken together, we suggest that in the TI response HZ stimulates monocyte and B cell co-culture to produce specific IgG through BAFF, APRIL and other independent complimentary signaling pathways.
Assuntos
Fator Ativador de Células B/imunologia , Hemeproteínas/imunologia , Plasmodium falciparum/imunologia , Linfócitos T/imunologia , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral/imunologia , Adolescente , Adulto , Linfócitos B/imunologia , Técnicas de Cocultura/métodos , Humanos , Imunoglobulina G/imunologia , Interleucina-4/imunologia , Ativação Linfocitária/imunologia , Pessoa de Meia-Idade , Monócitos/imunologia , RNA Mensageiro/imunologia , Transdução de Sinais/imunologia , Proteína Transmembrana Ativadora e Interagente do CAML/imunologia , Adulto JovemRESUMO
INTRODUCTION: A proliferation-inducing ligand (APRIL) and B cell activation factor (BAFF) are known to play a significant role in the pathogenesis of several diseases, including BAFF in malaria. The aim of this study was to investigate whether APRIL and BAFF plasma concentrations could be part of inflammatory responses associated with P. vivax and P. falciparum malaria in patients from the Brazilian Amazon. METHODS: Blood samples were obtained from P. vivax and P. falciparum malaria patients (n = 52) resident in Porto Velho before and 15 days after the beginning of treatment and from uninfected individuals (n = 12). We investigated APRIL and BAFF circulating levels and their association with parasitaemia, WBC counts, and cytokine/chemokine plasma levels. The expression levels of transmembrane activator and calcium-modulating cyclophilin ligand interactor (TACI) on PBMC from a subset of 5 P. vivax-infected patients were analyzed by flow cytometry. RESULTS: APRIL plasma levels were transiently increased during acute P. vivax and P. falciparum infections whereas BAFF levels were only increased during acute P. falciparum malaria. Although P. vivax and P. falciparum malaria patients have similar cytokine profiles during infection, in P. vivax acute phase malaria, APRIL but not BAFF levels correlated positively with IL-1, IL-2, IL-4, IL-6, and IL-13 levels. We did not find any association between P. vivax parasitaemia and APRIL levels, while an inverse correlation was found between P. falciparum parasitaemia and APRIL levels. The percentage of TACI positive CD4+ and CD8+ T cells were increased in the acute phase P. vivax malaria. CONCLUSION: These findings suggest that the APRIL and BAFF inductions reflect different host strategies for controlling infection with each malaria species.
Assuntos
Fator Ativador de Células B/sangue , Malária Falciparum/sangue , Malária Vivax/sangue , Malária/sangue , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral/sangue , Adulto , Antimaláricos/uso terapêutico , Fator Ativador de Células B/imunologia , Brasil , Estudos de Casos e Controles , Quimioterapia Combinada/métodos , Feminino , Voluntários Saudáveis , Interações Hospedeiro-Parasita/imunologia , Humanos , Interleucinas/sangue , Interleucinas/imunologia , Contagem de Leucócitos , Leucócitos Mononucleares/imunologia , Leucócitos Mononucleares/metabolismo , Malária/tratamento farmacológico , Malária/parasitologia , Malária Falciparum/tratamento farmacológico , Malária Falciparum/parasitologia , Malária Vivax/tratamento farmacológico , Malária Vivax/parasitologia , Masculino , Parasitemia/imunologia , Parasitemia/parasitologia , Plasmodium falciparum/imunologia , Plasmodium vivax/imunologia , Proteína Transmembrana Ativadora e Interagente do CAML/imunologia , Proteína Transmembrana Ativadora e Interagente do CAML/metabolismo , Membro 13 da Superfamília de Ligantes de Fatores de Necrose Tumoral/imunologia , Adulto JovemRESUMO
Patients with multiple sclerosis (MS) who are treated with fingolimod have an increased proportion of transitional B cells in the circulation, but the underlying mechanism is not known. We hypothesized that B cell-activating factor of the tumor necrosis factor family (BAFF) is involved in the process. Compared with healthy controls and untreated MS patients, fingolimod-treated MS patients had significantly higher serum concentrations of BAFF, which positively correlated with the proportions and the absolute numbers of transitional B cells in blood. Despite the elevated concentrations of BAFF in fingolimod-treated MS patients, serum levels of soluble transmembrane activator and calcium-modulating cyclophilin ligand interactor, and B cell maturation antigen were not elevated. Our results show that fingolimod induces BAFF in the circulation and expands transitional B cells, but does not activate memory B cells or plasma cells in MS, which is favorable for the treatment of this disease.
Assuntos
Fator Ativador de Células B/imunologia , Linfócitos B/imunologia , Cloridrato de Fingolimode/uso terapêutico , Memória Imunológica/imunologia , Imunossupressores/uso terapêutico , Esclerose Múltipla/tratamento farmacológico , Adulto , Antígeno de Maturação de Linfócitos B/imunologia , Estudos de Casos e Controles , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Esclerose Múltipla/imunologia , Plasmócitos/imunologia , Células Precursoras de Linfócitos B/imunologia , Proteína Transmembrana Ativadora e Interagente do CAML/imunologia , Adulto JovemRESUMO
Mechanistic target of rapamycin (mTOR) enhances immunity in addition to orchestrating metabolism. Here we show that mTOR coordinates immunometabolic reconfiguration of marginal zone (MZ) B cells, a pre-activated lymphocyte subset that mounts antibody responses to T-cell-independent antigens through a Toll-like receptor (TLR)-amplified pathway involving transmembrane activator and CAML interactor (TACI). This receptor interacts with mTOR via the TLR adapter MyD88. The resulting mTOR activation instigates MZ B-cell proliferation, immunoglobulin G (IgG) class switching, and plasmablast differentiation through a rapamycin-sensitive pathway that integrates metabolic and antibody-inducing transcription programs, including NF-κB. Disruption of TACI-mTOR interaction by rapamycin, truncation of the MyD88-binding domain of TACI, or B-cell-conditional mTOR deficiency interrupts TACI signaling via NF-κB and cooperation with TLRs, thereby hampering IgG production to T-cell-independent antigens but not B-cell survival. Thus, mTOR drives innate-like antibody responses by linking proximal TACI signaling events with distal immunometabolic transcription programs.
Assuntos
Linfócitos B/imunologia , Imunoglobulina G/imunologia , Alvo Mecanístico do Complexo 1 de Rapamicina/imunologia , Fator 88 de Diferenciação Mieloide/metabolismo , Serina-Treonina Quinases TOR/imunologia , Proteína Transmembrana Ativadora e Interagente do CAML/imunologia , Animais , Linhagem Celular , Proliferação de Células , Ativação Enzimática , Perfilação da Expressão Gênica , Células HEK293 , Humanos , Switching de Imunoglobulina/genética , Switching de Imunoglobulina/imunologia , Imunoglobulina G/biossíntese , Ativação Linfocitária/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , NF-kappa B/metabolismo , Transdução de Sinais/imunologia , Sirolimo/farmacologiaRESUMO
Serum levels of B cell-activating factor (BAFF) rise following rituximab (RTX) therapy in patients with rheumatoid arthritis (RA). Initiation of naive B cell return to the periphery and autoreactive B cell expansion leading to relapse after RTX may therefore be linked to interactions between BAFF and BAFF-binding receptors (BBR). Relationships between serum BAFF and BBR expression [(BAFFR, calcium signal modulating cyclophilic ligand interactor (TACI) and B cell maturation antigen (BCMA)] were determined on B cell subsets, defined using immunoglobulin (Ig)D/CD38. Twenty pre-RTX and 18 RA patients relapsing after B cell depletion were included. Results were analysed with respect to timing of relapse up to 7 months after peripheral B cell return (≥ 5 B cells/µl) and to serum BAFF levels. After B cell return, B cell populations from relapsing patients had significantly lower BAFFR+ expression compared to HC and pre-RTX patients. The percentage of BAFFR+ B cells increased with time after B cell return and was correlated inversely with serum BAFF levels. BAFFR expression remained reduced. The percentage of TACI+ memory B cells were lower in RA patients after RTX compared with healthy controls (HC). BCMA expression (% and expression) did not differ between patients and HC. Relapse following B cell return appeared largely independent of the percentage of BAFFR+ or percentage of BCMA+ B cells or serum BAFF levels. The lower percentage of TACI+ memory B cells may reduce inhibitory signalling for B cell differentiation. In patients relapsing at longer periods after B cell return, recovery of the B cell pool was more complete, suggesting that selection or expansion of autoreactive B cells may be needed to precipitate relapse.
Assuntos
Artrite Reumatoide , Receptor do Fator Ativador de Células B , Subpopulações de Linfócitos B , Regulação da Expressão Gênica , Memória Imunológica , Rituximab/administração & dosagem , Artrite Reumatoide/sangue , Artrite Reumatoide/tratamento farmacológico , Artrite Reumatoide/imunologia , Artrite Reumatoide/patologia , Fator Ativador de Células B/sangue , Fator Ativador de Células B/imunologia , Receptor do Fator Ativador de Células B/sangue , Receptor do Fator Ativador de Células B/imunologia , Antígeno de Maturação de Linfócitos B/sangue , Antígeno de Maturação de Linfócitos B/imunologia , Subpopulações de Linfócitos B/imunologia , Subpopulações de Linfócitos B/metabolismo , Subpopulações de Linfócitos B/patologia , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/imunologia , Memória Imunológica/efeitos dos fármacos , Memória Imunológica/imunologia , Proteína Transmembrana Ativadora e Interagente do CAML/sangue , Proteína Transmembrana Ativadora e Interagente do CAML/imunologiaRESUMO
Analysis of B cell activating factor (BAFF) receptors before and after B cell depletion therapy (BCDT) might offer a clue to the understanding of whether some B cell subsets may represent useful biomarkers of biological and clinical responses. Among the BAFF receptors in a cohort of rheumatoid arthritis (RA) patients, the AA have shown, by fluorescence activated cell sorter (FACS) analysis of median fluorescence intensity (MFI), that transmembrane activator and calcium-modulating cyclophilin ligand interactor (TACI) and B cell maturation antigen (BCMA) do not change, whereas the most important, BAFF receptor 3 (BR3), appears to be decreased before as well as after BCDT in all B cell subsets but not in plasmablasts, the most important subset, depleted by BCDT.