RESUMEN
Environmental allergens, including fungi, insects and mites, trigger type 2 immunity; however, the innate sensing mechanisms and initial signaling events remain unclear. Herein, we demonstrate that allergens trigger RIPK1-caspase 8 ripoptosome activation in epithelial cells. The active caspase 8 subsequently engages caspases 3 and 7, which directly mediate intracellular maturation and release of IL-33, a pro-atopy, innate immunity, alarmin cytokine. Mature IL-33 maintained functional interaction with the cognate ST2 receptor and elicited potent pro-atopy inflammatory activity in vitro and in vivo. Inhibiting caspase 8 pharmacologically and deleting murine Il33 and Casp8 each attenuated allergic inflammation in vivo. Clinical data substantiated ripoptosome activation and IL-33 maturation as likely contributors to human allergic inflammation. Our findings reveal an epithelial barrier, allergen-sensing mechanism that converges on the ripoptosome as an intracellular molecular signaling platform, triggering type 2 innate immune responses. These findings have significant implications for understanding and treating human allergic diseases.
Asunto(s)
Alérgenos/inmunología , Inmunidad Innata/inmunología , Inflamación/inmunología , Adolescente , Animales , Caspasa 8/inmunología , Línea Celular , Línea Celular Tumoral , Niño , Preescolar , Citocinas/inmunología , Células Epiteliales/inmunología , Femenino , Células HEK293 , Humanos , Hipersensibilidad/inmunología , Interleucina-33/inmunología , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Transducción de Señal/inmunologíaRESUMEN
One of the most significant conceptual advances in immunology in recent history is the recognition that signals from the innate immune system are required for induction of adaptive immune responses. Two breakthroughs were critical in establishing this paradigm: the identification of dendritic cells (DCs) as the cellular link between innate and adaptive immunity and the discovery of pattern recognition receptors (PRRs) as a molecular link that controls innate immune activation as well as DC function. Here, we recount the key events leading to these discoveries and discuss our current understanding of how PRRs shape adaptive immune responses, both indirectly through control of DC function and directly through control of lymphocyte function. In this context, we provide a conceptual framework for how variation in the signals generated by PRR activation, in DCs or other cell types, can influence T cell differentiation and shape the ensuing adaptive immune response.
Asunto(s)
Células Dendríticas , Inmunidad Innata , Inmunidad Adaptativa , Receptores de Reconocimiento de Patrones/metabolismo , Activación de LinfocitosRESUMEN
The cytokine interleukin (IL)-1ß is a key mediator of antimicrobial immunity as well as autoimmune inflammation. Production of IL-1ß requires transcription by innate immune receptor signaling and maturational cleavage by inflammasomes. Whether this mechanism applies to IL-1ß production seen in T cell-driven autoimmune diseases remains unclear. Here, we describe an inflammasome-independent pathway of IL-1ß production that was triggered upon cognate interactions between effector CD4+ T cells and mononuclear phagocytes (MPs). The cytokine TNF produced by activated CD4+ T cells engaged its receptor TNFR on MPs, leading to pro-IL-1ß synthesis. Membrane-bound FasL, expressed by CD4+ T cells, activated death receptor Fas signaling in MPs, resulting in caspase-8-dependent pro-IL-1ß cleavage. The T cell-instructed IL-1ß resulted in systemic inflammation, whereas absence of TNFR or Fas signaling protected mice from CD4+ T cell-driven autoimmunity. The TNFR-Fas-caspase-8-dependent pathway provides a mechanistic explanation for IL-1ß production and its consequences in CD4+ T cell-driven autoimmune pathology.
Asunto(s)
Autoinmunidad/inmunología , Linfocitos T CD4-Positivos/inmunología , Inflamación/patología , Interleucina-1beta/metabolismo , Células Mieloides/metabolismo , Animales , Caspasa 1/genética , Caspasa 8/metabolismo , Células Cultivadas , Células Dendríticas/inmunología , Proteína Ligando Fas/metabolismo , Inmunidad Innata/inmunología , Inflamasomas/inmunología , Inflamación/inmunología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Mycobacterium tuberculosis/inmunología , Receptores Tipo I de Factores de Necrosis Tumoral/metabolismo , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
Alloreactive memory T cells have been implicated as central drivers of transplant rejection. Perplexingly, innate cytokines, such as IL-6, IL-1ß, and IL-12, are also associated with rejection of organ transplants. However, the pathways of innate immune activation in allogeneic transplantation are unclear. While the role of microbial and cell death products has been previously described, we identified alloreactive memory CD4 T cells as the primary triggers of innate inflammation. Memory CD4 T cells engaged MHC II-mismatched dendritic cells (DCs), leading to the production of innate inflammatory cytokines. This innate inflammation was independent of several pattern recognition receptors and was primarily driven by TNF superfamily ligands expressed by alloreactive memory CD4 T cells. Blocking of CD40L and TNFα resulted in dampened inflammation, and mice genetically deficient in these molecules exhibited prolonged survival of cardiac allografts. Furthermore, myeloid cell and CD8 T cell infiltration into cardiac transplants was compromised in both CD40L- and TNFα-deficient recipients. Strikingly, we found that priming of naive alloreactive CD8 T cells was dependent on licensing of DCs by memory CD4 T cells. This study unravels the key mechanisms by which alloreactive memory CD4 T cells contribute to destructive pathology and transplant rejection.
Asunto(s)
Linfocitos T CD4-Positivos , Linfocitos T CD8-positivos , Células Dendríticas , Rechazo de Injerto , Trasplante de Corazón , Inmunidad Innata , Inflamación , Animales , Rechazo de Injerto/inmunología , Ratones , Células Dendríticas/inmunología , Linfocitos T CD8-positivos/inmunología , Linfocitos T CD4-Positivos/inmunología , Inflamación/inmunología , Inmunidad Innata/inmunología , Ratones Endogámicos C57BL , Ligando de CD40/inmunología , Ligando de CD40/metabolismo , Células T de Memoria/inmunología , Ratones Noqueados , Factor de Necrosis Tumoral alfa/metabolismo , Factor de Necrosis Tumoral alfa/inmunología , Citocinas/metabolismo , Citocinas/inmunologíaRESUMEN
Toll-like receptors (TLRs) and other pattern-recognition receptors (PRRs) sense microbial ligands and initiate signaling to induce inflammatory responses. Although the quality of inflammatory responses is influenced by internalization of TLRs, the role of endosomal maturation in clearing receptors and terminating inflammatory responses is not well understood. Here, we report that Drosophila and mammalian Vps33B proteins play critical roles in the maturation of phagosomes and endosomes following microbial recognition. Vps33B was necessary for clearance of endosomes containing internalized PRRs, failure of which resulted in enhanced signaling and expression of inflammatory mediators. Lack of Vps33B had no effect on trafficking of endosomes containing non-microbial cargo. These findings indicate that Vps33B function is critical for determining the fate of signaling endosomes formed following PRR activation. Exaggerated inflammatory responses dictated by persistence of receptors in aberrant endosomal compartments could therefore contribute to symptoms of ARC syndrome, a disease linked to loss of Vps33B.
Asunto(s)
Artrogriposis/inmunología , Colestasis/inmunología , Proteínas de Drosophila/metabolismo , Endosomas/metabolismo , Infecciones por Escherichia coli/inmunología , Inflamación/inmunología , Macrófagos/fisiología , Insuficiencia Renal/inmunología , Proteínas de Transporte Vesicular/metabolismo , Animales , Animales Modificados Genéticamente , Artrogriposis/genética , Células Cultivadas , Colestasis/genética , Drosophila , Proteínas de Drosophila/genética , Técnicas de Inactivación de Genes , Ratones , Transporte de Proteínas , ARN Interferente Pequeño/genética , Insuficiencia Renal/genética , Transducción de Señal , Receptor Toll-Like 4/metabolismo , Proteínas de Transporte Vesicular/genéticaRESUMEN
Macrophages respond to microbial ligands and various noxious cues by initiating an inflammatory response aimed at eliminating the original pathogenic insult. Transition of macrophages from a proinflammatory state to a reparative state, however, is vital for resolution of inflammation and return to homeostasis. The molecular players governing this transition remain poorly defined. Here, we find that the reparative macrophage transition is dictated by B-cell adapter for PI3K (BCAP). Mice harboring a macrophage-specific deletion of BCAP fail to recover from and succumb to dextran sulfate sodium-induced colitis due to prolonged intestinal inflammation and impaired tissue repair. Following microbial stimulation, gene expression in WT macrophages switches from an early inflammatory signature to a late reparative signature, a process that is hampered in BCAP-deficient macrophages. We find that absence of BCAP hinders inactivation of FOXO1 and GSK3ß, which contributes to their enhanced inflammatory state. BCAP deficiency also results in defective aerobic glycolysis and reduced lactate production. This translates into reduced histone lactylation and decreased expression of reparative macrophage genes. Thus, our results reveal BCAP to be a critical cell-intrinsic switch that regulates transition of inflammatory macrophages to reparative macrophages by imprinting epigenetic changes.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/metabolismo , Histonas/metabolismo , Macrófagos/metabolismo , Transducción de Señal , Receptores Toll-Like/metabolismo , Animales , Ratones , Procesamiento Proteico-PostraduccionalRESUMEN
Loss of the arthrogryposis-renal dysfunction-cholestasis (ARC) syndrome-linked Vps33B protein results in exaggerated inflammatory responses upon activation of receptors of the innate immune system in both vertebrates and flies. However, little is known about the signaling elements downstream of these receptors that are critical for the hypersensitivity of Vps33B mutants. Here, we show that p38b MAP kinase contributes to the enhanced inflammatory responses in flies lacking Vps33B. Loss of p38b mitogen-activated protein kinase (MAPK) reduces enhanced inflammatory responses and prolongs the survival of infected Vps33B deficient flies. The function of p38 MAPK is not limited to its proinflammatory effects downstream of the PGRP-LC receptor as p38 also modulates endosomal trafficking of PGRP-LC and phagocytosis of bacteria. Expression of constitutively active p38b MAPK, but not dominant negative p38b MAPK enhances accumulation of endocytosed PGRP-LC receptors or phagocytosed bacteria within cells. Moreover, p38 MAPK is required for induction of macropinocytosis, an alternate pathway for the downregulation of immune receptors. Together, our data indicate that p38 MAPK activates multiple pathways that can contribute to the dysregulation of innate immune signaling in ARC syndrome.
Asunto(s)
Artrogriposis , Colestasis , Dípteros , Animales , Dípteros/metabolismo , Sistema de Señalización de MAP Quinasas , Proteínas Quinasas Activadas por Mitógenos , Transporte de Proteínas , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismoRESUMEN
Preterm birth (PTB) is a major cause of neonatal mortality and morbidity, often triggered by chorioamnionitis or intrauterine inflammation (IUI) with or without infection. Recently, there has been a strong association of IL-1 with PTB. We hypothesized that IL-1R-associated kinase 1 (IRAK1), a key signaling mediator in the TLR/IL-1 pathway, plays a critical role in PTB. In human fetal membranes (FM) collected immediately after birth from women delivering preterm, p-IRAK1 was significantly increased in all the layers of FM with chorioamnionitis, compared with no-chorioamnionitis subjects. In a preterm rhesus macaque model of IUI given intra-amniotic LPS, induction of p-IRAK1 and downstream proinflammatory signaling mediators were seen in the FM. In a C57BL/6J wild-type PTB mouse model of IUI given intrauterine LPS, an IRAK1 inhibitor significantly decreased PTB and increased live birth in a dose-dependent manner. Furthermore, IRAK1 knockout mice were protected from LPS-induced PTB, which was seen in wild-type controls. Activation of IRAK1 was maintained by K63-mediated ubiquitination in preterm FM of humans with chorioamnionitis and rhesus and mouse IUI models. Mechanistically, IRAK1 induced PTB in the mouse model of IUI by upregulating expression of COX-2. Thus, our data from human, rhesus, and mouse demonstrates a critical role IRAK1 in IUI and inflammation-associated PTB and suggest it as potential therapeutic target in IUI-induced PTB.
Asunto(s)
Membranas Extraembrionarias/metabolismo , Quinasas Asociadas a Receptores de Interleucina-1/metabolismo , Nacimiento Prematuro/metabolismo , Útero/inmunología , Adulto , Animales , Corioamnionitis , Modelos Animales de Enfermedad , Membranas Extraembrionarias/patología , Femenino , Humanos , Quinasas Asociadas a Receptores de Interleucina-1/genética , Lipopolisacáridos/inmunología , Macaca mulatta , Masculino , Ratones , Ratones Endogámicos C57BL , Embarazo , Nacimiento Prematuro/inmunología , Adulto JovenRESUMEN
Activation of pattern recognition receptors on dendritic cells (DCs) and macrophages leads to secretion of cytokines that control differentiation of CD4(+) T cells. The current understanding is that interleukin-6 (IL-6) in combination with transforming growth factor-ß (TGF-ß) leads to generation of T helper 17 (Th17) lineage cells. Here, we have discovered that the cytokine requirements for Th17 cell polarization depend on the site of priming. Although IL-6 played a critical role in Th17 cell lineage priming in the skin and mucosal tissues, it was not required for Th17 cell priming in the spleen. In contrast, IL-1 played an irreplaceable role for priming of Th17 lineage cells in all tissues. Importantly, we have demonstrated that IL-6-independent and -dependent pathways of Th17 cell differentiation are guided by DCs residing in various tissues. These results reveal fundamental differences by which the systemic, mucosal, and cutaneous immune systems guide Th17 cell lineage commitment.
Asunto(s)
Diferenciación Celular/inmunología , Citocinas/fisiología , Células Th17/citología , Células Th17/inmunología , Animales , Antígenos/inmunología , Antígenos CD/metabolismo , Linaje de la Célula , Células Dendríticas/inmunología , Cadenas alfa de Integrinas/metabolismo , Interleucina-6/genética , Interleucina-6/metabolismo , Tejido Linfoide/inmunología , Tejido Linfoide/metabolismo , Glicoproteínas de Membrana/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Transgénicos , Factor 88 de Diferenciación Mieloide/genética , Factor 88 de Diferenciación Mieloide/metabolismo , Receptores de Interleucina-1/metabolismo , Transducción de SeñalRESUMEN
Activation of cells in the adaptive immune system is a highly orchestrated process dictated by multiples cues from the innate immune system. Although the fundamental principles of innate control of adaptive immunity are well established, it is not fully understood how innate cells integrate qualitative pathogenic information to generate tailored protective adaptive immune responses. In this review, we discuss complexities involved in the innate control of adaptive immunity that extend beyond TCR engagement, costimulation, and priming cytokine production but are critical for the generation of protective T cell immunity.
Asunto(s)
Inmunidad Adaptativa , Inmunidad Innata , Transducción de Señal , Linfocitos T/inmunología , Animales , Citocinas/inmunología , Humanos , Ratones , Receptores de Antígenos de Linfocitos T/inmunología , Receptores de Antígenos de Linfocitos T/metabolismoRESUMEN
Inflammatory responses are controlled by signaling mediators that are regulated by various posttranslational modifications. Recently, transcription-independent functions for glucocorticoids (GC) in restraining inflammation have emerged, but the underlying mechanisms are unknown. In this study, we report that GC receptor (GR)-mediated actions of GC acutely suppress TLR9-induced inflammation via inhibition of IL-1R-associated kinase 1 (IRAK1) ubiquitination. ß-TrCP-IRAK1 interaction is required for K48-linked ubiquitination of IRAK1 at Lys134 and subsequent membrane-to-cytoplasm trafficking of IRAK1 interacting partners TNFR-associated factor 6 and TAK1 that facilitates NF-κB and MAPK activation. Upon costimulation of macrophages with GC and TLR9-engaging ligand, GR physically interacts with IRAK1 and interferes with protein-protein interactions between ß-TrCP and IRAK1. Ablation of GR in macrophages prevents GC-dependent suppression of ß-TrCP-IRAK1 interactions. This GC-mediated suppression of IRAK1 activation is unique to TLR9, as GC treatment impairs TLR9 but not TLR4 ligand-induced K48-linked IRAK1 ubiquitination and trafficking of IRAK1 interacting partners. Furthermore, mutations in IRAK1 at Lys134 prevent TLR9 ligand-induced activation of inflammatory signaling mediators and synthesis of proinflammatory cytokines to an extent comparable to GC-mediated inhibition. Collectively, these findings identify a transcription-independent, rapid, and nongenomic GC suppression of TLR9 ligand-mediated IRAK1 ubiquitination as a novel mechanism for restraining acute inflammatory reactions.
Asunto(s)
Glucocorticoides/metabolismo , Inflamación/inmunología , Quinasas Asociadas a Receptores de Interleucina-1/metabolismo , Macrófagos/inmunología , Proteínas con Repetición de beta-Transducina/metabolismo , Animales , Células Cultivadas , Citocinas/metabolismo , Mediadores de Inflamación/metabolismo , Quinasas Asociadas a Receptores de Interleucina-1/genética , Masculino , Ratones , Ratones de la Cepa 129 , Ratones Endogámicos C57BL , FN-kappa B/metabolismo , Unión Proteica , Transporte de Proteínas , Receptor Toll-Like 9/metabolismo , UbiquitinaciónRESUMEN
Activation of CD4 T cells by dendritic cells leads to their differentiation into various effector lineages. The nature of the effector lineage is determined by the innate cues provided by dendritic cells to newly primed T cells. Although the cytokines necessary for several effector lineages have been identified, the innate cues that drive T follicular helper (Tfh) lineage cell development remain unclear. Here we found that following priming, CD4 T cells undergoing clonal expansion acquire a transient Tfh-like phenotype before differentiating into other effector lineages. In addition, we found that T cell-intrinsic myeloid differentiation antigen 88 (MyD88) signaling, which occurs downstream of interleukin-1 (IL-1) and IL-18 receptors, is critical for the primed CD4 T cells to transition out of the temporary Tfh lineage. Mice with T cell-specific deletion of MyD88 have a higher proportion of Tfh cells and germinal center (GC) B cells. These exaggerated Tfh cell and GC B cell responses, however, do not lead to protective immunity against infections. We demonstrate that T cell-intrinsic MyD88 is critical for effector lineage differentiation as well as production of the cytokines that are necessary for class switching. Overall, our study establishes that following priming and clonal expansion, CD4 T cells undergo a transitional Tfh-like phase and that further differentiation into effector lineages is dictated by T cell-intrinsic MyD88-dependent cues.
Asunto(s)
Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD4-Positivos/fisiología , Factor 88 de Diferenciación Mieloide/inmunología , Factor 88 de Diferenciación Mieloide/fisiología , Folículo Ovárico/inmunología , Linfocitos T Colaboradores-Inductores/inmunología , Linfocitos T Colaboradores-Inductores/fisiología , Diferenciación Celular/inmunología , Diferenciación Celular/fisiología , Femenino , Humanos , Folículo Ovárico/fisiologíaRESUMEN
BACKGROUND: Genetic background influences allergic immune responses to environmental stimuli. Non-obese diabetic (NOD) mice are highly susceptible to environmental stimuli. Little is known about the interaction of autoimmune genetic factors with innate immunity in allergies, especially skin hypersensitivity. OBJECTIVES: To study the interplay of innate immunity and autoimmune genetic factors in contact hypersensitivity (CHS) by using various innate immunity-deficient NOD mice. METHODS: Toll-like receptor (TLR) 2-deficient, TLR9-deficient and MyD88-deficient NOD mice were used to investigate CHS. The cellular mechanism was determined by flow cytometry in vitro and adoptive cell transfer in vivo. To investigate the role of MyD88 in dendritic cells (DCs) in CHS, we also used CD11cMyD88+ MyD88-/- NOD mice, in which MyD88 is expressed only in CD11c+ cells. RESULTS: We found that innate immunity negatively regulates CHS, as innate immunity-deficient NOD mice developed exacerbated CHS accompanied by increased numbers of skin-migrating CD11c+ DCs expressing higher levels of major histocompatibility complex II and CD80. Moreover, MyD88-/- NOD mice had increased numbers of CD11c+ CD207- CD103+ DCs and activated T effector cells in the skin-draining lymph nodes. Strikingly, re-expression of MyD88 in CD11c+ DCs (CD11cMyD88+ MyD88-/- NOD mice) restored hyper-CHS to a normal level in MyD88-/- NOD mice. CONCLUSION: Our results suggest that the autoimmune-prone NOD genetic background aggravates CHS regulated by innate immunity, through DCs and T effector cells.
Asunto(s)
Dermatitis por Contacto/genética , Inmunidad Innata/genética , Traslado Adoptivo , Animales , Antígeno B7-1/metabolismo , Movimiento Celular , Citocinas/inmunología , Citocinas/metabolismo , Células Dendríticas/citología , Células Dendríticas/inmunología , Células Dendríticas/metabolismo , Dermatitis por Contacto/etiología , Dermatitis por Contacto/inmunología , Antígenos de Histocompatibilidad Clase II/metabolismo , Inmunidad Innata/inmunología , Ganglios Linfáticos/citología , Ganglios Linfáticos/inmunología , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos NOD , Ratones Noqueados , Factor 88 de Diferenciación Mieloide/genética , Factor 88 de Diferenciación Mieloide/inmunología , Cloruro de Picrilo/efectos adversos , ARN Mensajero/metabolismo , Piel/citología , Piel/inmunología , Piel/metabolismo , Linfocitos T Reguladores/citología , Linfocitos T Reguladores/inmunología , Receptor Toll-Like 2/genética , Receptor Toll-Like 2/inmunología , Receptor Toll-Like 9/genética , Receptor Toll-Like 9/inmunologíaRESUMEN
Recognition of pathogen-associated molecular patterns by Toll-like receptors (TLRs) on dendritic cells (DCs) leads to DC maturation, a process involving up-regulation of MHC and costimulatory molecules and secretion of proinflammatory cytokines. All TLRs except TLR3 achieve these outcomes by using the signaling adaptor myeloid differentiation factor 88. TLR4 and TLR3 can both use the Toll-IL-1 receptor domain-containing adaptor inducing IFN-ß (TRIF)-dependent signaling pathway leading to IFN regulatory factor 3 (IRF3) activation and induction of IFN-ß and -α4. The TRIF signaling pathway, downstream of both of these TLRs, also leads to DC maturation, and it has been proposed that the type I IFNs act in cis to induce DC maturation and subsequent effects on adaptive immunity. The present study was designed to understand the molecular mechanisms of TRIF-mediated DC maturation. We have discovered that TLR4-TRIF-induced DC maturation was independent of both IRF3 and type I IFNs. In contrast, TLR3-mediated DC maturation was completely dependent on type I IFN feedback. We found that differential activation of mitogen-activated protein kinases by the TLR4- and TLR3-TRIF axes determined the type I IFN dependency for DC maturation. In addition, we found that the adjuvanticity of LPS to induce T-cell activation is completely independent of type I IFNs. The important distinction between the TRIF-mediated signaling pathways of TLR4 and TLR3 discovered here could have a major impact in the design of future adjuvants that target this pathway.
Asunto(s)
Proteínas Adaptadoras del Transporte Vesicular/metabolismo , Células Dendríticas/inmunología , Regulación de la Expresión Génica/inmunología , Transducción de Señal/fisiología , Receptor Toll-Like 3/metabolismo , Receptor Toll-Like 4/metabolismo , Animales , Secuencia de Bases , Western Blotting , Linfocitos T CD4-Positivos/metabolismo , Proliferación Celular/fisiología , Células Dendríticas/citología , Citometría de Flujo , Lipopolisacáridos , Ratones , Ratones Noqueados , Datos de Secuencia Molecular , Análisis de Secuencia de ARNRESUMEN
Pathogenic infections and tissue injuries trigger the assembly of inflammasomes, cytosolic protein complexes that activate caspase-1, leading to cleavage of pro-IL-1ß and pro-IL-18 and to pyroptosis, a proinflammatory cell death program. Although microbial recognition by Toll-like receptors (TLRs) is known to induce the synthesis of the major caspase-1 substrate pro-IL-1ß, the role of TLRs has been considered limited to up-regulation of the inflammasome components. During infection with a virulent microbe, TLRs and nucleotide-binding oligomerization domain-like receptors (NLRs) are likely activated simultaneously. To examine the requirements and outcomes of combined activation, we stimulated TLRs and a specific NLR, nucleotide binding and oligomerization, leucine-rich repeat, pyrin domain-containing 3 (NLRP3), simultaneously and discovered that such activation triggers rapid caspase-1 cleavage, leading to secretion of presynthesized inflammatory molecules and pyroptosis. This acute caspase-1 activation is independent of new protein synthesis and depends on the TLR-signaling molecule IL-1 receptor-associated kinase (IRAK-1) and its kinase activity. Importantly, Listeria monocytogenes induces NLRP3-dependent rapid caspase-1 activation and pyroptosis, both of which are compromised in IRAK-1-deficient macrophages. Our results reveal that simultaneous sensing of microbial ligands and virulence factors by TLRs and NLRP3, respectively, leads to a rapid TLR- and IRAK-1-dependent assembly of the NLRP3 inflammasome complex, and that such activation is important for release of alarmins, pyroptosis, and early IFN-γ production by memory CD8 T cells, all of which could be critical for early host defense.
Asunto(s)
Proteínas Portadoras/inmunología , Activación Enzimática/inmunología , Inflamasomas/inmunología , Quinasas Asociadas a Receptores de Interleucina-1/metabolismo , Receptores Toll-Like/inmunología , Animales , Caspasa 1/metabolismo , Citocinas/sangre , Inmunoprecipitación , Macrófagos , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Microscopía Fluorescente , Proteína con Dominio Pirina 3 de la Familia NLRRESUMEN
TLR activation on dendritic cells (DCs) induces DC maturation and secretion of proinflammatory cytokines, both of which are important for activation and differentiation of CD4 T cells. The importance of TLR activation on DCs for CD8 T cell responses is less clear. In this study, we tested the ability of different TLRs to regulate CD8 T cell responses to pathogens. We found that although all TLRs are able to induce CD8 T cell activation in vitro, there are profound differences in their ability to activate CD8 T cells in vivo. The nucleic acid recognizing endosomal TLRs, TLR3 and TLR9, had a potent ability to induce CD8 T cell activation. However, the surface TLRs, TLR2 and TLR4, that recognize bacterial ligands were not only incapable of inducing CD8 T cell priming, but they had a dominant effect of inhibiting CD8 T cell expansion induced by activation of endosomal TLRs. We found that TLR2 and TLR4, acting in a MyD88-dependent manner, influenced CD8 T cell priming by altering the composition of DCs in the draining lymph nodes. Our results have important implications for combined bacterial and viral infections and suggest that bacterial infections could constrain the ability of the host to mount effective antiviral CD8 T cell immunity.
Asunto(s)
Linfocitos T CD8-positivos/inmunología , Activación de Linfocitos/inmunología , Receptores Toll-Like/inmunología , Animales , Linfocitos T CD8-positivos/citología , Diferenciación Celular/inmunología , Membrana Celular/inmunología , Membrana Celular/metabolismo , Células Dendríticas/citología , Células Dendríticas/inmunología , Endosomas/inmunología , Endosomas/metabolismo , Citometría de Flujo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Receptores Toll-Like/metabolismoRESUMEN
Toll like receptors (TLRs) use Toll-IL-1 receptor (TIR) domain-containing adapters, such as myeloid differentiation primary response gene 88 (MyD88) and TIR domain-containing adapter inducing IFN-ß (TRIF), to induce activation of transcription factors, including NF-κB, MAP kinases, and IFN regulatory factors. TLR signaling also leads to activation of PI3K, but the molecular mechanism is not understood. Here we have discovered a unique role for B-cell adapter for PI3K (BCAP) in the TLR-signaling pathway. We find that BCAP has a functional N-terminal TIR homology domain and links TLR signaling to activation of PI3K. In addition, BCAP negatively regulates proinflammatory cytokine secretion upon TLR stimulation. In vivo, the absence of BCAP leads to exaggerated recruitment of inflammatory myeloid cells following infections and enhanced susceptibility to dextran sulfate sodium-induced colitis. Our results demonstrate that BCAP is a unique TIR domain-containing TLR signaling adapter crucial for linking TLRs to PI3K activation and regulating the inflammatory response.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/metabolismo , Linfocitos B/enzimología , Fosfatidilinositol 3-Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Transducción de Señal , Receptores Toll-Like/metabolismo , Proteínas Adaptadoras Transductoras de Señales/química , Secuencia de Aminoácidos , Animales , Activación Enzimática , Células HEK293 , Humanos , Inflamación/metabolismo , Inflamación/patología , Macrófagos/metabolismo , Macrófagos/patología , Glicoproteínas de Membrana/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Datos de Secuencia Molecular , Factor 88 de Diferenciación Mieloide/metabolismo , Estructura Terciaria de ProteínaRESUMEN
Gut microbiota, specifically gut bacteria, are critical for effective immune checkpoint blockade therapy (ICT) for cancer. The mechanisms by which gut microbiota augment extraintestinal anticancer immune responses, however, are largely unknown. Here, we find that ICT induces the translocation of specific endogenous gut bacteria into secondary lymphoid organs and subcutaneous melanoma tumors. Mechanistically, ICT induces lymph node remodeling and dendritic cell (DC) activation, which facilitates the translocation of a selective subset of gut bacteria to extraintestinal tissues to promote optimal antitumor T cell responses in both the tumor-draining lymph nodes (TDLNs) and the primary tumor. Antibiotic treatment results in decreased gut microbiota translocation into mesenteric lymph nodes (MLNs) and TDLNs, diminished DC and effector CD8+ T cell responses, and attenuated responses to ICT. Our findings illuminate a key mechanism by which gut microbiota promote extraintestinal anticancer immunity.
Asunto(s)
Microbioma Gastrointestinal , Melanoma , Humanos , Inhibidores de Puntos de Control Inmunológico , Linfocitos T CD8-positivos , Ganglios LinfáticosRESUMEN
Intestinal epithelial cells (IECs) constitute a critical first line of defense against microbes. While IECs are known to respond to various microbial signals, the precise upstream cues regulating diverse IEC responses are not clear. Here, we discover a dual role for IEC-intrinsic interleukin-1 receptor (IL-1R) signaling in regulating intestinal homeostasis and inflammation. Absence of IL-1R in epithelial cells abrogates a homeostatic antimicrobial program including production of antimicrobial peptides (AMPs). Mice deficient for IEC-intrinsic IL-1R are unable to clear Citrobacter rodentium (C. rodentium) but are protected from DSS-induced colitis. Mechanistically, IL-1R signaling enhances IL-22R-induced signal transducer and activator of transcription 3 (STAT3) phosphorylation in IECs leading to elevated production of AMPs. IL-1R signaling in IECs also directly induces expression of chemokines as well as genes involved in the production of reactive oxygen species. Our findings establish a protective role for IEC-intrinsic IL-1R signaling in combating infections but a detrimental role during colitis induced by epithelial damage.
Asunto(s)
Colitis , Receptores de Interleucina-1 , Ratones , Animales , Receptores de Interleucina-1/genética , Receptores de Interleucina-1/metabolismo , Intestinos , Colitis/metabolismo , Inflamación/metabolismo , Células Epiteliales/metabolismo , Homeostasis , Mucosa Intestinal/metabolismoRESUMEN
Cognate interaction between CD4+ effector memory T (TEM) cells and dendritic cells (DCs) induces innate inflammatory cytokine production, resulting in detrimental autoimmune pathology and cytokine storms. While TEM cells use tumor necrosis factor (TNF) superfamily ligands to activate DCs, whether TEM cells prompt other DC-intrinsic changes that influence the innate inflammatory response has never been investigated. We report the surprising discovery that TEM cells trigger double-strand DNA breaks via mitochondrial reactive oxygen species (ROS) production in interacting DCs. Initiation of the DNA damage response in DCs induces activation of a cyclic guanosine monophosphate (GMP)-AMP synthase (cGAS)-independent, non-canonical stimulator of interferon genes (STING)-TNF receptor-associated factor 6 (TRAF6)-nuclear factor κB (NF-κB) signaling axis. Consequently, STING-deficient DCs display reduced NF-κB activation and subsequent defects in transcriptional induction and functional production of interleukin-1ß (IL-1ß) and IL-6 following their interaction with TEM cells. The discovery of TEM cell-induced innate inflammation through DNA damage and a non-canonical STING-NF-κB pathway presents this pathway as a potential target to alleviate T cell-driven inflammation in autoimmunity and cytokine storms.