RESUMEN
The innate responsiveness of the immune system is important not only for quick responses to pathogens but also for the initiation and shaping of the subsequent adaptive immune response. Activation via the cytokine IL-18, a product of inflammasomes, gives rise to a rapid response that includes the production of self-reactive antibodies. As increased concentrations of this cytokine are found in inflammatory diseases, we investigated the origin of the B cell response and its regulation. We identified an accumulation of B cell-helper neutrophils in the spleen that interacted with innate-type invariant natural killer T cells (iNKT cells) to regulate B cell responses. We found that neutrophil-dependent expression of the death-receptor ligand FasL by iNKT cells was needed to restrict autoantibody production. Neutrophils can thus license iNKT cells to regulate potentially harmful autoreactive B cell responses during inflammasome-driven inflammation.
Asunto(s)
Linfocitos B/inmunología , Proteína Ligando Fas/metabolismo , Inflamación/inmunología , Células T Asesinas Naturales/inmunología , Neutrófilos/inmunología , Inmunidad Adaptativa , Animales , Autoanticuerpos/biosíntesis , Células Cultivadas , Proteína Ligando Fas/genética , Inmunidad Innata , Inflamasomas/metabolismo , Interleucina-18/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones NoqueadosRESUMEN
Invariant natural killer T cells (iNKT cells) are lipid-sensing innate T cells that are restricted by the antigen-presenting molecule CD1d and express the transcription factor PLZF. iNKT cells accumulate in adipose tissue, where they are anti-inflammatory, but the factors that contribute to their anti-inflammatory nature, as well as their targets in adipose tissue, are unknown. Here we found that iNKT cells in adipose tissue had a unique transcriptional program and produced interleukin 2 (IL-2) and IL-10. Unlike other iNKT cells, they lacked PLZF but expressed the transcription factor E4BP4, which controlled their IL-10 production. The adipose iNKT cells were a tissue-resident population that induced an anti-inflammatory phenotype in macrophages and, through the production of IL-2, controlled the number, proliferation and suppressor function of regulatory T cells (Treg cells) in adipose tissue. Thus, iNKT cells in adipose tissue are unique regulators of immunological homeostasis in this tissue.
Asunto(s)
Tejido Adiposo/inmunología , Factores de Transcripción de Tipo Kruppel/biosíntesis , Macrófagos/inmunología , Células T Asesinas Naturales/metabolismo , Linfocitos T Reguladores/metabolismo , Tejido Adiposo/citología , Animales , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/genética , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/inmunología , Procesos de Crecimiento Celular/inmunología , Femenino , Citometría de Flujo , Regulación de la Expresión Génica , Homeostasis/inmunología , Interleucina-10/genética , Interleucina-10/inmunología , Interleucina-2/genética , Interleucina-2/inmunología , Factores de Transcripción de Tipo Kruppel/deficiencia , Factores de Transcripción de Tipo Kruppel/genética , Factores de Transcripción de Tipo Kruppel/inmunología , Macrófagos/citología , Masculino , Ratones Endogámicos C57BL , Ratones Noqueados , Células T Asesinas Naturales/citología , Células T Asesinas Naturales/inmunología , Proteína de la Leucemia Promielocítica con Dedos de Zinc , Organismos Libres de Patógenos Específicos , Linfocitos T Reguladores/citología , Linfocitos T Reguladores/inmunologíaRESUMEN
Invariant natural killer T (iNKT) cells mediate rapid immune responses which bridge the gap between innate and adaptive responses to pathogens while also providing key regulation to maintain immune homeostasis. Both types of important iNKT immune responses are mediated through interactions with innate and adaptive B cells. As such, iNKT cells sit at the decision-making fulcrum between regulating inflammatory or autoreactive B cells and supporting protective or regulatory B cell populations. iNKT cells interpret the signals in their environment to set the tone for subsequent adaptive responses, with outcomes ranging from getting licensed to maintain homeostasis as an iNKT regulatory cell (iNKTreg ) or being activated to become an iNKT follicular helper (iNKTFH ) cell supporting pathogen-specific effector B cells. Here we review iNKT and B cell cooperation across the spectrum of immune outcomes, including during allergy and autoimmune disease, tumor surveillance and immunotherapy, or pathogen defense and vaccine responses. Because of their key role as influencers, iNKT cells provide a valuable target for therapeutic interventions. Understanding the nature of the interactions between iNKT and B cells will enable the development of clinical interventions to strategically target regulatory iNKT and B cell populations or inflammatory ones, depending on the circumstance.
Asunto(s)
Linfocitos B Reguladores , Células T Asesinas Naturales , Inmunidad Innata , Inmunoterapia , Activación de LinfocitosRESUMEN
Mouse invariant natural killer T cells (iNKT cells) provide cognate and noncognate help for lipid and protein-specific B cells, respectively. However, the long-term outcome for B cells after cognate help is provided by iNKT cells is unknown at present. Here we found that cognate iNKT cell help resulted in a B cell differentiation program characterized by extrafollicular plasmablasts, germinal-center formation, affinity maturation and a robust primary immunoglobulin G (IgG) antibody response that was uniquely dependent on iNKT cell-derived interleukin 21 (IL-21). However, cognate help from iNKT cells did not generate an enhanced humoral memory response. Thus, cognate iNKT cell help for lipid-specific B cells induces a unique signature that is a hybrid of classic T cell-dependent and T cell-independent type 2 B cell responses.
Asunto(s)
Antígenos/inmunología , Linfocitos B/inmunología , Interleucinas/fisiología , Lípidos/inmunología , Células T Asesinas Naturales/inmunología , Animales , Centro Germinal/inmunología , Inmunidad Humoral , Memoria Inmunológica , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Receptores de Antígenos de Linfocitos B/inmunología , Transducción de Señal/inmunología , Bazo/inmunologíaRESUMEN
CD4+ T cells enable the critical B cell humoral immune protection afforded by most effective vaccines. We and others have recently identified an alternative source of help for B cells in mice, invariant NK T (iNKT) cells. iNKT cells are innate glycolipid-specific T cells restricted to the nonpolymorphic Ag-presenting molecule CD1d. As such, iNKT cells respond to glycolipids equally well in all people, making them an appealing adjuvant for universal vaccines. We tested the potential for the iNKT glycolipid agonist, α-galactosylceramide (αGC), to serve as an adjuvant for a known human protective epitope by creating a nanoparticle that delivers αGC plus antigenic polysaccharides from Streptococcus pneumoniae αGC-embedded nanoparticles activate murine iNKT cells and B cells in vitro and in vivo, facilitate significant dose sparing, and avoid iNKT anergy. Nanoparticles containing αGC plus S. pneumoniae polysaccharides elicits robust IgM and IgG in vivo and protect mice against lethal systemic S. pneumoniae However, codelivery of αGC via nanoparticles actually eliminated Ab protection elicited by a T-independent S. pneumoniae vaccine. This is consistent with previous studies demonstrating iNKT cell help for B cells following acute activation, but negative regulation of B cells during chronic inflammation. αGC-containing nanoparticles represent a viable platform for broadly efficacious vaccines against deadly human pathogens, but their potential for eliminating B cells under certain conditions suggests further clarity on iNKT cell interactions with B cells is warranted.
Asunto(s)
Linfocitos B/inmunología , Galactosilceramidas/metabolismo , Nanopartículas/metabolismo , Células T Asesinas Naturales/inmunología , Infecciones Neumocócicas/inmunología , Polisacáridos Bacterianos/metabolismo , Vacunas Estreptocócicas/inmunología , Streptococcus pneumoniae/inmunología , Animales , Células Cultivadas , Galactosilceramidas/inmunología , Humanos , Inmunidad Humoral , Inmunoglobulina G/metabolismo , Inmunoglobulina M/metabolismo , Activación de Linfocitos , Ratones , Polisacáridos Bacterianos/inmunología , Linfocitos T/inmunologíaRESUMEN
Invariant natural killer T (iNKT) cells serve as early rapid responders in the innate immune response to self-derived autoantigens and pathogen-derived danger signals and antigens. iNKT cells can serve both as helpers for effector B cells and negatively regulate autoreactive B cells. Specifically, iNKT cells drive B cell proliferation, class switch, and antibody production to induce primary antigen-specific immune responses. On the other hand, inflammasome-mediated activation drives accumulation of neutrophils, which license iNKT cells to negatively regulate autoreactive B cells via Fas ligand (FasL). This positions iNKT cells at an apex to support or inhibit B cell responses in inflammation. However, it is unknown which effector mechanism dominates in the face of cognate glycolipid activation during chronic inflammation, as might result from glycolipid vaccination or infection during chronic autoimmune disease. We stimulated iNKT cells by cognate glycolipid antigen α-galactosylceramide (αGalCer) and measured B cell activation during interleukin 18 (IL-18)-induced chronic inflammation. Moreover, glycolipid-activated iNKT cells increased the serum concentration of autoantibodies, frequency of germinal center (GC) B cells, and antigen-specific plasma cells induced during chronic IL-18-mediated inflammation, as compared with IL-18 alone. Further, activation of iNKT cells via cognate glycolipid during IL-18-mediated inflammation overrides the licensing function of neutrophils, instead inducing iNKT follicular helper (iNKTfh) cells that in turn promote autoimmunity. Thus, our data demonstrate that glycolipids which engage iNKT cells support antigen-specific B cell help during inflammasome-mediated inflammation.
Asunto(s)
Anticuerpos Antinucleares/inmunología , Autoinmunidad , Galactosilceramidas/inmunología , Inflamación/inmunología , Células T Asesinas Naturales/inmunología , Animales , Anticuerpos Antinucleares/sangre , Linfocitos B/inmunología , Enfermedad Crónica , Modelos Animales de Enfermedad , Femenino , Humanos , Inflamación/sangre , Inyecciones Intraperitoneales , Interleucina-18/administración & dosificación , Interleucina-18/inmunología , Masculino , Ratones , Ratones Transgénicos , Proteínas Recombinantes/administración & dosificación , Proteínas Recombinantes/inmunologíaRESUMEN
BACKGROUND: The risk of severe coronavirus disease 2019 (COVID-19) varies significantly among persons of similar age and is higher in males. Age-independent, sex-biased differences in susceptibility to severe COVID-19 may be ascribable to deficits in a sexually dimorphic protective attribute that we termed immunologic resilience (IR). OBJECTIVE: We sought to examine whether deficits in IR that antedate or are induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection independently predict COVID-19 mortality. METHODS: IR levels were quantified with 2 novel metrics: immune health grades (IHG-I [best] to IHG-IV) to gauge CD8+ and CD4+ T-cell count equilibrium, and blood gene expression signatures. IR metrics were examined in a prospective COVID-19 cohort (n = 522); primary outcome was 30-day mortality. Associations of IR metrics with outcomes in non-COVID-19 cohorts (n = 13,461) provided the framework for linking pre-COVID-19 IR status to IR during COVID-19, as well as to COVID-19 outcomes. RESULTS: IHG-I, tracking high-grade equilibrium between CD8+ and CD4+ T-cell counts, was the most common grade (73%) among healthy adults, particularly in females. SARS-CoV-2 infection was associated with underrepresentation of IHG-I (21%) versus overrepresentation (77%) of IHG-II or IHG-IV, especially in males versus females (P < .01). Presentation with IHG-I was associated with 88% lower mortality, after controlling for age and sex; reduced risk of hospitalization and respiratory failure; lower plasma IL-6 levels; rapid clearance of nasopharyngeal SARS-CoV-2 burden; and gene expression signatures correlating with survival that signify immunocompetence and controlled inflammation. In non-COVID-19 cohorts, IR-preserving metrics were associated with resistance to progressive influenza or HIV infection, as well as lower 9-year mortality in the Framingham Heart Study, especially in females. CONCLUSIONS: Preservation of immunocompetence with controlled inflammation during antigenic challenges is a hallmark of IR and associates with longevity and AIDS resistance. Independent of age, a male-biased proclivity to degrade IR before and/or during SARS-CoV-2 infection predisposes to severe COVID-19.
Asunto(s)
COVID-19/inmunología , Infecciones por VIH/epidemiología , VIH-1/fisiología , Insuficiencia Respiratoria/epidemiología , SARS-CoV-2/fisiología , Factores Sexuales , Linfocitos T/inmunología , Adulto , Anciano , COVID-19/epidemiología , COVID-19/mortalidad , Estudios de Cohortes , Resistencia a la Enfermedad , Femenino , Humanos , Inmunocompetencia , Interleucina-6/sangre , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Índice de Severidad de la Enfermedad , Análisis de Supervivencia , Transcriptoma/inmunología , Estados Unidos/epidemiología , Carga ViralRESUMEN
Successful induction of B-cell activation and memory depends on help from CD4+ T cells. Invariant natural killer T (iNKT) cells (glycolipid-specific, CD1d-restricted innate lymphocytes) provide both cognate (direct) and noncognate (indirect) helper signals to enhance B-cell responses. Both forms of iNKT-cell help induce primary humoral immune responses, but only noncognate iNKT-cell help drives humoral memory and plasma cells. Here, we show that iNKT cognate help for B cells is fundamentally different from the help provided by conventional CD4+ T cells. Cognate iNKT-cell help drives an early, unsustained germinal center B-cell expansion, less reduction of T follicular regulatory cells, an expansion of marginal zone B cells, and early increases in regulatory IL-10-producing B-cell numbers compared with noncognate activation. These results are consistent with a mechanism whereby iNKT cells preferentially provide an innate form of help that does not generate humoral memory and has important implications for the application of glycolipid molecules as vaccine adjuvants.
Asunto(s)
Linfocitos B Reguladores/inmunología , Interleucina-10/inmunología , Células T Asesinas Naturales/inmunología , Transducción de Señal/inmunología , Animales , Antígenos CD1d/inmunología , Antígenos CD1d/metabolismo , Linfocitos B Reguladores/metabolismo , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD4-Positivos/metabolismo , Proliferación Celular , Citometría de Flujo , Centro Germinal/citología , Centro Germinal/inmunología , Centro Germinal/metabolismo , Glucolípidos/inmunología , Glucolípidos/metabolismo , Inmunidad Innata/inmunología , Interleucina-10/metabolismo , Activación de Linfocitos/inmunología , Ratones de la Cepa 129 , Ratones Endogámicos C57BL , Ratones Noqueados , Células T Asesinas Naturales/metabolismo , Bazo/citología , Bazo/inmunologíaRESUMEN
Invariant NKT (iNKT) cells are glycolipid-specific innate lymphocytes emerging as critical players in the immune response to diverse infections and disease. iNKT cells are activated through cognate interactions with lipid-loaded APCs, by Ag-independent cytokine-mediated signaling pathways, or a combination of both. Although each of these modes of iNKT cell activation plays an important role in directing the humoral and cell-mediated immune response, the spatio-temporal nature of these interactions and the cellular requirements for activation are largely undefined. Combining novel in situ confocal imaging of αGalactosylceramide-loaded CD1d tetramer labeling to localize the endogenous iNKT cell population with cytokine reporter mice, we reveal the choreography of early murine splenic iNKT cell activation across diverse settings of glycolipid immunization and systemic infection with Streptococcus pneumoniae. We find that iNKT cells consolidate in the marginal zone and require dendritic cells lining the splenic marginal zone for activation following administration of cognate glycolipids and during systemic infection but not following exogenous cytokine administration. Although further establishing the importance of cognate iNKT cell interactions with APCs, we also show that noncognate iNKT-dependent mechanisms are sufficient to mediate effector outcomes, such as STAT signaling and dendritic cell licensing throughout the splenic parenchyma. Collectively, these data provide new insight into how iNKT cells may serve as a natural adjuvant in facilitating adaptive immune responses, irrespective of their tissue localization.
Asunto(s)
Activación de Linfocitos , Células T Asesinas Naturales/inmunología , Bazo/inmunología , Streptococcus pneumoniae/inmunología , Inmunidad Adaptativa , Animales , Células Presentadoras de Antígenos/inmunología , Antígenos CD1d/inmunología , Comunicación Celular , Citocinas/biosíntesis , Citocinas/inmunología , Células Dendríticas/inmunología , Células Dendríticas/metabolismo , Galactosilceramidas , Ratones , Ratones Endogámicos BALB C , Ratones Noqueados , Infecciones Neumocócicas/inmunología , Transducción de Señal/inmunologíaRESUMEN
BACKGROUND/AIMS: Inflammation is a major and critical component of the lung pathology in the hereditary disease cystic fibrosis. The molecular mechanisms of chronic inflammation in cystic fibrosis require definition. METHODS: We used several genetic mouse models to test a role of iNKT cells and ceramide in pulmonary inflammation of cystic fibrosis mice. Inflammation was determined by the pulmonary cytokine profil and the abundance of inflammatory cells in the lung. RESULTS: Here we provide a new concept how inflammation in the lung of individuals with cystic fibrosis is initiated. We show that in cystic fibrosis mice the mutation in the Cftr gene provokes a significant up-regulation of iNKT cells in the lung. Accumulation of iNKT cells serves to control autoimmune disease, which is triggered by a ceramide-mediated induction of cell death in CF organs. Autoimmunity becomes in particular overt in cystic fibrosis mice lacking iNKT cells and although suppression of the autoimmune response by iNKT cells is beneficial, IL-17(+) iNKT cells attract macrophages and neutrophils to CF lungs resulting in chronic inflammation. Genetic deletion of iNKT cells in cystic fibrosis mice prevents inflammation in CF lungs. CONCLUSION: Our data demonstrate an important function of iNKT cells in the chronic inflammation affecting cystic fibrosis lungs. iNKT cells suppress the auto-immune response induced by ceramide-mediated death of epithelial cells in CF lungs, but also induce a chronic pulmonary inflammation.
Asunto(s)
Células Asesinas Naturales/inmunología , Animales , Autoanticuerpos/metabolismo , Autoinmunidad , Linfocitos B/inmunología , Linfocitos B/metabolismo , Fibrosis Quística/metabolismo , Fibrosis Quística/patología , Regulador de Conductancia de Transmembrana de Fibrosis Quística/deficiencia , Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Regulador de Conductancia de Transmembrana de Fibrosis Quística/metabolismo , Modelos Animales de Enfermedad , Interleucina-17/metabolismo , Células Asesinas Naturales/metabolismo , Pulmón/inmunología , Pulmón/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos CFTR , Neumonía/metabolismo , Neumonía/patologíaRESUMEN
One of the manifestations of X-linked lymphoproliferative disease (XLP) is progressive agammaglobulinemia, caused by the absence of a functional signaling lymphocyte activation molecule (SLAM)-associated protein (SAP) in T, invariant natural killer T (NKT) cells and NK cells. Here we report that α-galactosylceramide (αGalCer) activated NKT cells positively regulate antibody responses to haptenated protein antigens at multiple checkpoints, including germinal center formation and affinity maturation. Whereas NKT cell-dependent B cell responses were absent in SAP(-/-).B6 mice that completely lack NKT cells, the small number of SAP-deficient NKT cells in SAP(-/-).BALB/c mice adjuvated antibody production, but not the germinal center reaction. To test the hypothesis that SAP-deficient NKT cells can facilitate humoral immunity, SAP was deleted after development in SAP(fl/fl).tgCreERT2.B6 mice. We find that NKT cell intrinsic expression of SAP is dispensable for noncognate helper functions, but is critical for providing cognate help to antigen-specific B cells. These results demonstrate that SLAM-family receptor-regulated cell-cell interactions are not limited to T-B cell conjugates. We conclude that in the absence of SAP, several routes of NKT cell-mediated antibody production are still accessible. The latter suggests that residual NKT cells in XLP patients might contribute to variations in dysgammaglobulinemia.
Asunto(s)
Linfocitos B/inmunología , Péptidos y Proteínas de Señalización Intracelular/genética , Péptidos y Proteínas de Señalización Intracelular/inmunología , Células Asesinas Naturales/inmunología , Trastornos Linfoproliferativos/inmunología , Animales , Antineoplásicos Hormonales/farmacología , Linfocitos B/citología , Comunicación Celular/efectos de los fármacos , Comunicación Celular/inmunología , Femenino , Galactosilceramidas/metabolismo , Galactosilceramidas/farmacología , Expresión Génica/inmunología , Centro Germinal/inmunología , Haptenos/inmunología , Haptenos/metabolismo , Células Asesinas Naturales/citología , Activación de Linfocitos/efectos de los fármacos , Activación de Linfocitos/inmunología , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Proteína Asociada a la Molécula de Señalización de la Activación Linfocitaria , Tamoxifeno/farmacologíaRESUMEN
Receptor Interacting Protein Kinase 1 (RIPK1) and caspase-8 (Casp8) jointly orchestrate apoptosis, a key mechanism for eliminating developing T cells which have autoreactive or improperly arranged T cell receptors. Mutations in the scaffolding domain of Ripk1 gene have been identified in humans with autoinflammatory diseases like Cleavage Resistant RIPK1 Induced Autoinflammatory (CRIA) and Inflammatory Bowel Disease. RIPK1 protein also contributes to conventional T cell differentiation and peripheral T cell homeostasis through its scaffolding domain in a cell death independent context. Ripk1 deficient mice do not survive beyond birth, so we have studied the function of this kinase in vivo against a backdrop Ripk3 and Casp8 deficiency which allows the mice to survive to adulthood. These studies reveal a key role for RIPK1 in mediating NK1.1 expression, including on thymic iNKT cells, which is a key requirement for thymic stage 2 to stage 3 transition as well as iNKT cell precursor development. These results are consistent with RIPK1 mediating responses to TcR engagement, which influence NK1.1 expression and iNKT cell thymic development. We also used in vivo and in vitro stimulation assays to confirm a role for both Casp8 and RIPK1 in mediating iNKT cytokine effector responses. Finally, we also noted expanded and hyperactivated iNKT follicular helper (iNKTFH) cells in both DKO (Casp8-, Ripk3- deficient) and TKO mice (Ripk1-, Casp8-, Ripk3- deficient). Thus, while RIPK1 and Casp8 jointly facilitate iNKT effector function, RIPK1 uniquely influenced thymic iNKT cell development most likely by regulating molecular responses to T cell receptor engagement. iNKT developmental and functional aberrances were not evident in mice expressing a kinase-dead version of RIPK1 (RIPK1kd), indicating that the scaffolding function of this protein exerts the critical regulation of iNKT cells. Our findings suggest that small molecule inhibitors of RIPK1 could be used to regulate iNKT cell development and effector function to alleviate autoinflammatory conditions in humans.
Asunto(s)
Células T Asesinas Naturales , Animales , Humanos , Ratones , Apoptosis/fisiología , Muerte Celular , Proteína Serina-Treonina Quinasas de Interacción con Receptores/genética , TimoRESUMEN
Obesity is accompanied by inflammation in adipose tissue, impaired glucose tolerance, and changes in adipose leukocyte populations. These studies of adipose tissue from humans and mice revealed that increased frequencies of T-bet+ B cells in adipose tissue depend on invariant NKT cells and correlate with weight gain during obesity. Transfer of B cells enriched for T-bet+ cells exacerbates metabolic disorder in obesity, while ablation of Tbx21 specifically in B cells reduces serum IgG2c levels, inflammatory cytokines, and inflammatory macrophages in adipose tissue, ameliorating metabolic symptoms. Furthermore, transfer of serum or purified IgG from HFD mice restores metabolic disease in T-bet+ B cell-deficient mice, confirming T-bet+ B cell-derived IgG as a key mediator of inflammation during obesity. Together, these findings reveal an important pathological role for T-bet+ B cells that should inform future immunotherapy design in type 2 diabetes and other inflammatory conditions.
Asunto(s)
Diabetes Mellitus Tipo 2 , Resistencia a la Insulina , Enfermedades Metabólicas , Tejido Adiposo/metabolismo , Animales , Diabetes Mellitus Tipo 2/metabolismo , Dieta Alta en Grasa , Humanos , Inmunoglobulina G , Inflamación/metabolismo , Enfermedades Metabólicas/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Obesidad/metabolismoRESUMEN
Peptide antigens are presented to T cells by major histocompatibility complex (MHC) molecules, with endogenous peptides presented by MHC class I and exogenous peptides presented by MHC class II. In contrast to the MHC system, CD1 molecules bind lipid antigens that are presented at the antigen-presenting cell (APC) surface to lipid antigen-reactive T cells. Because CD1 molecules survey endocytic compartments, it is self-evident that they encounter antigens from extracellular sources. However, the mechanisms of exogenous lipid antigen delivery to CD1-antigen-loading compartments are not known. Serum apolipoproteins are mediators of extracellular lipid transport for metabolic needs. Here we define the pathways mediating markedly efficient exogenous lipid antigen delivery by apolipoproteins to achieve T-cell activation. Apolipoprotein E binds lipid antigens and delivers them by receptor-mediated uptake into endosomal compartments containing CD1 in APCs. Apolipoprotein E mediates the presentation of serum-borne lipid antigens and can be secreted by APCs as a mechanism to survey the local environment to capture antigens or to transfer microbial lipids from infected cells to bystander APCs. Thus, the immune system has co-opted a component of lipid metabolism to develop immunological responses to lipid antigens.
Asunto(s)
Presentación de Antígeno , Células Presentadoras de Antígenos/inmunología , Apolipoproteínas E/metabolismo , Lípidos/inmunología , Animales , Células Presentadoras de Antígenos/metabolismo , Antígenos CD1/inmunología , Antígenos CD1/metabolismo , Apolipoproteínas E/deficiencia , Apolipoproteínas E/genética , Células Dendríticas/inmunología , Células Dendríticas/metabolismo , Endosomas/metabolismo , Humanos , Metabolismo de los Lípidos , Lípidos/sangre , Activación de Linfocitos , Ratones , Receptores de LDL/metabolismo , Linfocitos T/inmunología , Linfocitos T/metabolismoRESUMEN
The mechanisms of T cell help for production of antilipid antibodies are largely unknown. This study shows that invariant NK T cells (iNK T cells) and B cells cooperate in a model of antilipid antigen-specific antibody responses. We use a model haptenated lipid molecule, 4-hydroxy-3-nitrophenyl-alphaGalactosylCeramide (NP-alphaGalCer), to demonstrate that iNK T cells provide cognate help to lipid-antigen-presenting B cells. B cells proliferate and IgG anti-NP is produced from in vivo-immunized mice and in vitro cocultures of B and NK T cells after exposure to NP-alphaGalCer, but not closely related control glycolipids. This B cell response is absent in CD1d(-/-) and Jalpha18(-/-) mice but not CD4(-/-) mice. The antibody response to NP-alphaGalCer is dominated by the IgM, IgG3, and IgG2c isotypes, and marginal zone B cells stimulate better in vitro lipid antigen-driven proliferation than follicular B cells, suggesting an important role for this B cell subset. iNK T cell help for B cells is shown to involve cognate help from CD1d-instructed lipid-specific iNK T cells, with help provided via CD40L, B7-1/B7-2, and IFN-gamma, but not IL-4. This model provides evidence of iNK T cell help for antilipid antibody production, an important aspect of infections, autoimmune diseases, and vaccine development. Our findings also now allow prediction of those microbial antigens that would be expected to elicit cognate iNKT cell help for antibody production, namely those that can stimulate iNKT cells and at the same time have a polar moiety that can be recognized by antibodies.
Asunto(s)
Formación de Anticuerpos , Linfocitos B/inmunología , Linfocitos T CD4-Positivos/inmunología , Galactosilceramidas/inmunología , Células Asesinas Naturales/inmunología , Subgrupos de Linfocitos T/inmunología , Animales , Presentación de Antígeno , Células Presentadoras de Antígenos/inmunología , Antígenos/inmunología , Galactosilceramidas/química , Haptenos/química , Haptenos/inmunología , Inmunoglobulina G/biosíntesis , Inmunoglobulina G/inmunología , Inmunoglobulina M/biosíntesis , Inmunoglobulina M/inmunología , Activación de Linfocitos , Ratones , Ratones Endogámicos C57BLRESUMEN
Rapid immune responses regulated by invariant Natural Killer T (iNKT) cells bridge the gap between innate and adaptive responses to pathogens, while also providing key regulation to maintain immune homeostasis. iNKT immune protection and immune regulation are both mediated through interactions with innate and adaptive B cell populations that express CD1d. Recent studies have expanded our understanding of the position of iNKT cells at the fulcrum between regulating inflammatory and autoreactive B cells. Environmental signals influence iNKT cells to set the tone for subsequent adaptive responses, ranging from maintaining homeostasis as an iNKT regulatory cell (iNKTreg) or supporting pathogen-specific effector B cells as an iNKT follicular helper (iNKTFH). Here we review recent advances in iNKT and B cell cooperation during autoimmunity and sterile inflammation. Understanding the nature of the interactions between iNKT and B cells will enable the development of clinical interventions to strategically target regulatory iNKT and B cell populations or inflammatory ones, across a range of indications.
Asunto(s)
Linfocitos B/inmunología , Activación de Linfocitos , Células T Asesinas Naturales/fisiología , Animales , Autoinmunidad/inmunología , Humanos , Inmunidad Innata/fisiología , Inflamación/etiología , Inflamación/inmunología , Activación de Linfocitos/inmunologíaRESUMEN
Mutations in the scaffolding domain of Receptor Interacting Protein kinases (RIP) underlie the recently described human autoimmune syndrome, CRIA, characterized by lymphadenopathy, splenomegaly, and autoantibody production. While disease mechanisms for CRIA remain undescribed, RIP kinases work together with caspase-8 to regulate cell death, which is critical for normal differentiation of many cell types. Here, we describe a key role for RIP1 in facilitating innate B cell differentiation and subsequent activation. By comparing RIP1, RIP3, and caspase-8 triple deficient and RIP3, caspase-8 double deficient mice, we identified selective contributions of RIP1 to an accumulation of murine splenic Marginal Zone (MZ) B cells and B1-b cells. We used mixed bone-marrow chimeras to determine that innate B cell commitment required B cell-intrinsic RIP1, RIP3, and caspase-8 sufficiency. RIP1 regulated MZ B cell development rather than differentiation and RIP1 mediates its innate immune effects independent of the RIP1 kinase domain. NP-KLH/alum and NP-Ficoll vaccination of mice doubly deficient in both caspase-8 and RIP3 or deficient in all three proteins (RIP3, caspase-8, and RIP1) revealed uniquely delayed T-dependent and T-independent IgG responses, abnormal splenic germinal center architecture, and reduced extrafollicular plasmablast formation compared to WT mice. Thus, RIP kinases and caspase-8 jointly orchestrate B cell fate and delayed effector function through a B cell-intrinsic mechanism.
Asunto(s)
Linfocitos B/inmunología , Caspasa 8/inmunología , Proteínas Activadoras de GTPasa/inmunología , Inmunidad Innata/inmunología , Proteína Serina-Treonina Quinasas de Interacción con Receptores/inmunología , Animales , Caspasa 8/genética , Proteínas Activadoras de GTPasa/deficiencia , Proteínas Activadoras de GTPasa/genética , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Mutación , Proteína Serina-Treonina Quinasas de Interacción con Receptores/deficiencia , Proteína Serina-Treonina Quinasas de Interacción con Receptores/genéticaRESUMEN
Lymphotoxin beta receptor (LTßR) is a promising therapeutic target in autoimmune and infectious diseases as well as cancer. Mice with genetic inactivation of LTßR display multiple defects in development and organization of lymphoid organs, mucosal immune responses, IgA production and an autoimmune phenotype. As these defects are imprinted in embryogenesis and neonate stages, the impact of LTßR signaling in adulthood remains unclear. Here, to overcome developmental defects, we generated mice with inducible ubiquitous genetic inactivation of LTßR in adult mice (iLTßRΔ/Δ mice) and redefined the role of LTßR signaling in organization of lymphoid organs, immune response to mucosal bacterial pathogen, IgA production and autoimmunity. In spleen, postnatal LTßR signaling is required for development of B cell follicles, follicular dendritic cells (FDCs), recruitment of neutrophils and maintenance of the marginal zone. Lymph nodes of iLTßRΔ/Δ mice were reduced in size, lacked FDCs, and had disorganized subcapsular sinus macrophages. Peyer`s patches were smaller in size and numbers, and displayed reduced FDCs. The number of isolated lymphoid follicles in small intestine and colon were also reduced. In contrast to LTßR-/- mice, iLTßRΔ/Δ mice displayed normal thymus structure and did not develop signs of systemic inflammation and autoimmunity. Further, our results suggest that LTßR signaling in adulthood is required for homeostasis of neutrophils, NK, and iNKT cells, but is dispensable for the maintenance of polyclonal IgA production. However, iLTßRΔ/Δ mice exhibited an increased sensitivity to C. rodentium infection and failed to develop pathogen-specific IgA responses. Collectively, our study uncovers new insights of LTßR signaling in adulthood for the maintenance of lymphoid organs, neutrophils, NK and iNKT cells, and IgA production in response to mucosal bacterial pathogen.
Asunto(s)
Envejecimiento/inmunología , Tejido Linfoide/inmunología , Receptor beta de Linfotoxina/fisiología , Animales , Anticuerpos Antibacterianos/biosíntesis , Anticuerpos Antibacterianos/inmunología , Autoinmunidad , Moléculas de Adhesión Celular/metabolismo , Quimiocinas/metabolismo , Citrobacter rodentium/inmunología , Cruzamientos Genéticos , Regulación del Desarrollo de la Expresión Génica , Homeostasis/inmunología , Inmunoglobulina A/biosíntesis , Inmunoglobulina A/inmunología , Inflamación , Células Asesinas Naturales/inmunología , Tejido Linfoide/citología , Receptor beta de Linfotoxina/biosíntesis , Receptor beta de Linfotoxina/deficiencia , Receptor beta de Linfotoxina/genética , Ratones , Ratones Endogámicos MRL lpr , Ratones Transgénicos , Neutrófilos/inmunología , Eliminación de Secuencia , Organismos Libres de Patógenos Específicos , Esplenomegalia/inmunologíaRESUMEN
A new haptenated derivative of alpha-galactosyl ceramide (alpha-GalCer) has been synthesized to assist in the study of the mechanism of T cell help for the production of B cell antibodies. Our synthetic route provides access to an amine intermediate which can easily be extended to generate an array of compounds, useful in various ongoing studies. Herein, we also describe the biological evaluation of the nitrophenyl (NP) haptenated alpha-GalCer and demonstrate its importance in such mechanistic studies. For instance, in vitro studies showed that NP-alpha-GalCer stimulates both T and B cell proliferation while in vivo studies in immunized mice showed the production of IgG anti-NP antibodies after exposure to NP-alpha-GalCer. The interpretation of these results helps toward a better understanding of T cell help for the production of antibodies.
Asunto(s)
Anticuerpos/inmunología , Antígenos/inmunología , Galactosilceramidas/síntesis química , Galactosilceramidas/inmunología , Lípidos/inmunología , Células T Asesinas Naturales/inmunología , Animales , Anticuerpos/química , Antígenos/química , Antígenos/farmacología , Linfocitos B/inmunología , Proliferación Celular/efectos de los fármacos , Galactosilceramidas/farmacología , Inmunoglobulina G/inmunología , Lípidos/síntesis química , Lípidos/farmacología , Ratones , Estructura Molecular , Células T Asesinas Naturales/efectos de los fármacos , Relación Estructura-ActividadRESUMEN
Alpha-galactosylceramide (αGalCer) is a glycolipid derived from a marine sponge that is a potent activator of both mouse and human invariant natural killer T (iNKT) cells. For that reason, αGalCer is a promising vaccine adjuvant that has been shown to improve both humoral and cellular immunity when co-administered with various vaccines, including candidate vaccines for biodefense. In the current study, we tested the effectiveness of αGalCer as an adjuvant for the clinically-relevant ricin toxin subunit vaccine, RiVax. αGalCer had a potent adjuvant effect, as shown by a rapid onset of anti-ricin IgG titers, accelerated development of serum toxin-neutralizing activity, and enhanced protection from lethal ricin challenge in a mouse model. These results underscore the potential of αGalCer to augment the protective immune response to a vaccine designed to counteract ricin toxin, a fast-acting biothreat agent.