RESUMEN
Mycobacterium tuberculosis establishes chronic infection and causes disease through manipulation of the host's innate and adaptive immune response. The bacterial cell wall is highly complex and contains a rich variety of glycosylated compounds that are secreted during infection and have been proposed as immunomodulatory molecules. Amongst the most important of these are the p-hydroxybenzoic acid derivatives (p-HBADs). Here we report the synthesis of this important class of biomolecules and the first in vitro study of the immunomodulatory effects of these compounds in isolation from the host bacterium. The compounds do not have stimulatory properties but, in contrast, can inhibit the production of inflammatory cytokines, particularly interferon-γ (IFN-γ), by T-cells. This study offers a fundamental insight into the effect of these glycans on the immune response.
Asunto(s)
Citocinas/antagonistas & inhibidores , Hidroxibenzoatos/farmacología , Mycobacterium tuberculosis/química , Citocinas/biosíntesis , Citocinas/inmunología , Hidroxibenzoatos/síntesis química , Hidroxibenzoatos/aislamiento & purificación , Estructura MolecularRESUMEN
Escherichia coli heat-labile enterotoxin (LT) is a powerful mucosal adjuvant; however, it is associated with toxic effects when delivered intranasally, and its mechanism of action is poorly understood. In this article, we demonstrate that LT acts as a highly effective adjuvant when administered parenterally, promoting Ag-specific IL-17, as well as IFN-γ, IL-4, and IL-10 production in response to coadministered Ags. We found that the adjuvant activity of LT was mediated in part by inducing dendritic cell (DC) activation; LT promoted CD80 and CD86 expression by DCs and enhanced IL-1α, IL-1ß, and IL-23 production. An LT mutant, LTK63, that lacks enzyme activity was less effective than the wild-type toxin in promoting DC maturation and the development of Ag-specific Th17 cells. LT enhanced IL-23 and IL-1α production from DCs via activation of ERK MAPK and IL-1ß secretion through activation of caspase-1 and the NLRP3 inflammasome. These cytokines played a major role in promoting Th17 responses by LT and LTK63. The induction of Th17 cells in vivo in response to LT and LTK63 as adjuvants was significantly reduced in IL-1RI-deficient mice. Finally, using a murine respiratory infection model, we demonstrated that LT can act as a highly effective adjuvant for a pertussis vaccine, promoting Ag-specific Th17 cells and protection against Bordetella pertussis challenge, which was significantly reduced in IL-17-defective mice. Our findings provide clear evidence that LT can promote protective immune responses in part through induction of innate IL-1 and, consequently, Th17 cells.
Asunto(s)
Toxinas Bacterianas/inmunología , Enterotoxinas/inmunología , Proteínas de Escherichia coli/inmunología , Escherichia coli/inmunología , Interleucina-1/inmunología , Interleucina-23/inmunología , Células Th17/inmunología , Animales , Antígeno B7-1/genética , Antígeno B7-2/genética , Toxinas Bacterianas/administración & dosificación , Toxinas Bacterianas/metabolismo , Bordetella pertussis/inmunología , Linfocitos T CD4-Positivos/inmunología , Proteínas Portadoras/metabolismo , Caspasa 1/metabolismo , Diferenciación Celular/inmunología , Células Dendríticas/inmunología , Células Dendríticas/metabolismo , Enterotoxinas/administración & dosificación , Enterotoxinas/metabolismo , Proteínas de Escherichia coli/administración & dosificación , Proteínas de Escherichia coli/metabolismo , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Interferón gamma/inmunología , Interleucina-1/biosíntesis , Interleucina-10/inmunología , Interleucina-17/genética , Interleucina-17/inmunología , Interleucina-23/biosíntesis , Interleucina-4/inmunología , Interleucina-5/inmunología , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Noqueados , Mutación , Proteína con Dominio Pirina 3 de la Familia NLRRESUMEN
Microbial pathogens can initiate MOMP in host cells and as such, initiate the mitochondrial pathway of apoptosis. Innate immune recognition of cells dying in this way by infection-induced apoptosis would involve recognition of ligands derived from the apoptotic host cell simultaneously with those derived from the infecting pathogen. The resultant signal transduction pathways engaged direct DCs to concomitantly synthesize TGF-ß and IL-6, two cytokines that subsequently favor the differentiation of naïve CD4 T cells into T(h)17 cells. Citrobacter rodentium is one rodent pathogen that targets mitochondria and induces apoptosis, and blockade of apoptosis during enteric Citrobacter infection impairs the characteristic T(h)17 response in the intestinal LP. Here, we review these original findings. We discuss microbial infections other than Citrobacter that have been shown to induce T(h)17 responses, and we examine what is known about the ability of those pathogens to induce apoptosis. We also consider types of cell death other than apoptosis that can be triggered by microbial infection, and we highlight how little we know about the impact of various forms of cell death on the ensuing adaptive immune response.
Asunto(s)
Apoptosis , Bacterias/inmunología , Infecciones Bacterianas/inmunología , Células Th17/inmunología , Animales , HumanosRESUMEN
Two of the critical cytokines required for the differentiation of T helper 17 (T(H)17) cells from naive CD4 T cells are transforming growth factor-beta (TGF-ß) and interleukin-6 (IL-6). Innate recognition of apoptotic cells in the presence of Toll-like receptor engagement directs the simultaneous synthesis of these cytokines by antigen-presenting cells (APCs), and as such provides a cytokine milieu that favors T(H)17 cell induction. In this situation, APCs are activated in response to ligands derived from apoptotic cells, but also to those from the infecting pathogen. Induction of a T(H)17 response against Citrobacter rodentium infection was dependent on the ability of Citrobacter to induce apoptosis of intestinal epithelial cells. In this review, we will discuss how simultaneous activation of inflammatory and noninflammatory pattern recognition receptors on APCs impacts T helper cell differentiation, and what relevance this effect has on the immune response generated against bacterial infections that cause host cell apoptosis.
Asunto(s)
Apoptosis , Linfocitos T Colaboradores-Inductores/inmunología , Diferenciación Celular , Línea Celular , Citrobacter rodentium/inmunología , Humanos , Inmunidad Innata , Fagocitosis , Transducción de Señal , Linfocitos T Colaboradores-Inductores/citologíaRESUMEN
Th17 cells, CD4(+) T cells that secrete interleukin-17 (IL-17), are pathogenic in autoimmune diseases and their development and expansion is driven by the cytokines IL-6, TGF-beta, IL-21, IL-1, and IL-23. However, there are also innate sources of IL-17. Here, we show that gammadelta T cells express IL-23R and the transcription factor RORgammat and produce IL-17, IL-21, and IL-22 in response to IL-1beta and IL-23, without T cell receptor engagement. IL-17-producing gammadelta T cells were found at high frequency in the brain of mice with experimental autoimmune encephalomyelitis (EAE). gammadelta T cells activated by IL-1beta and IL-23 promoted IL-17 production by CD4(+) T cells and increased susceptibility to EAE, suggesting that gammadelta T cells act in an amplification loop for IL-17 production by Th17 cells. Our findings demonstrate that gammadelta T cells activated by IL-1beta and IL-23 are an important source of innate IL-17 and IL-21 and provide an alternative mechanism whereby IL-1 and IL-23 may mediate autoimmune inflammation.
Asunto(s)
Células Dendríticas/inmunología , Encefalomielitis Autoinmune Experimental/inmunología , Interleucina-17/inmunología , Receptores de Antígenos de Linfocitos T gamma-delta/inmunología , Receptores de Interleucina-17/metabolismo , Subgrupos de Linfocitos T/inmunología , Linfocitos T Colaboradores-Inductores/inmunología , Animales , Autoinmunidad , Complejo CD3/inmunología , Complejo CD3/metabolismo , Células Dendríticas/efectos de los fármacos , Células Dendríticas/metabolismo , Encefalomielitis Autoinmune Experimental/metabolismo , Interleucina-17/biosíntesis , Interleucina-1beta/inmunología , Interleucina-1beta/metabolismo , Interleucina-1beta/farmacología , Interleucina-23/inmunología , Interleucina-23/metabolismo , Interleucina-23/farmacología , Interleucinas/inmunología , Interleucinas/metabolismo , Lipopolisacáridos/inmunología , Ratones , Ratones Endogámicos C57BL , Mycobacterium tuberculosis/inmunología , Miembro 3 del Grupo F de la Subfamilia 1 de Receptores Nucleares , Receptores de Antígenos de Linfocitos T gamma-delta/metabolismo , Receptores de Interleucina/inmunología , Receptores de Interleucina/metabolismo , Receptores de Interleucina-1/genética , Receptores de Interleucina-1/inmunología , Receptores de Interleucina-1/metabolismo , Receptores de Interleucina-17/inmunología , Receptores de Ácido Retinoico/inmunología , Receptores de Ácido Retinoico/metabolismo , Receptores de Hormona Tiroidea/inmunología , Receptores de Hormona Tiroidea/metabolismo , Subgrupos de Linfocitos T/efectos de los fármacos , Subgrupos de Linfocitos T/metabolismo , Linfocitos T Colaboradores-Inductores/efectos de los fármacos , Linfocitos T Colaboradores-Inductores/metabolismo , Interleucina-22RESUMEN
IL-17-producing CD4(+) T (Th17) cells are pathogenic in many autoimmune diseases. The induction and expansion of Th17 cells is directed by cytokines, including IL-23 and IL-1beta, produced by innate immune cells through activation of pathogen recognition receptors. The NF-kappaB and IFN regulatory factor families of transcriptional factors mediate IL-12 production; however, distinct signaling pathways appear to be required for IL-23 production. In this study, we show that inhibition of ERK MAPK suppressed IL-23 and IL-1beta production by dendritic cells stimulated with TLR or dectin-1 agonists but did not affect IL-12p70 production. Furthermore, an ERK inhibitor suppressed the ability of Ag-pulsed TLR-activated dendritic cells to induce Ag-specific Th17 cells in vivo, but interestingly also inhibited the induction of Th1 cells. Treatment with an ERK inhibitor attenuated experimental autoimmune encephalomyelitis (EAE), when administered either at the induction phase of acute EAE or during remission in the relapsing-remitting EAE model. This was associated with significant suppression of autoantigen-specific Th17 and Th1 responses. The suppressive effect of the ERK inhibitor on attenuation of EAE was reversed by administration of IL-1beta and IL-23. Our findings suggest that ERK MAPK plays a critical and hitherto undescribed role in activating innate production of IL-23 and IL-1beta, which promote pathogenic T cell responses, and therefore represents an important target for therapeutic intervention against autoimmune diseases.
Asunto(s)
Enfermedades Autoinmunes/inmunología , Quinasas MAP Reguladas por Señal Extracelular/fisiología , Interleucina-17/biosíntesis , Interleucina-1beta/inmunología , Interleucina-23/inmunología , Animales , Células Cultivadas , Células Dendríticas/metabolismo , Quinasas MAP Reguladas por Señal Extracelular/antagonistas & inhibidores , Interleucina-1beta/biosíntesis , Interleucina-23/biosíntesis , Ratones , Linfocitos T/inmunología , Células TH1 , Receptores Toll-LikeRESUMEN
Adenylate cyclase toxin (CyaA) of Bordetella pertussis binds to CD11b/CD18 on macrophages and dendritic cells (DC) and confers virulence to the bacteria by subverting innate immune responses of the host. We have previously demonstrated that CyaA promotes the induction of IL-10-secreting regulatory T cells in vivo by modulating DC activation. Here, we examine the mechanism of immune subversion, specifically, the modulation of TLR signaling pathways in DC. We found that CyaA synergized with LPS to induce IL-10 mRNA and protein expression in DC but significantly inhibited IL-12p70 production. CyaA enhanced LPS-induced phosphorylation of p38 MAPK and ERK in DC, and inhibitors of p38 MAPK, MEK, or NF-kappaB suppressed IL-10 production in response to LPS and CyaA. However, inhibition of p38 MAPK, MEK, and NF-kappaB did not reverse the inhibitory effect of CyaA on TLR agonist-induced IL-12 production. Furthermore, CyaA suppression of IL-12 was independent of IL-10. In contrast, CyaA suppressed LPS- and IFN-gamma-induced IFN-regulatory factor-1 (IRF-1) and IRF-8 expression in DC. The modulatory effects of CyaA were dependent on adenylate cyclase activity and induction of intracellular cAMP, as an enzyme-inactive mutant of CyaA failed to modulate TLR-induced signaling in DC, whereas the effects of the wild-type toxin were mimicked by stimulation of the DC with PGE2. Our findings demonstrate that CyaA modulates TLR agonist-induced IL-10 and IL-12p70 production in DC by, respectively, enhancing MAPK phosphorylation and inhibiting IRF-1 and IRF-8 expression and that this is mediated by elevation of intercellular cAMP concentrations.
Asunto(s)
Toxina de Adenilato Ciclasa/farmacología , Citocinas/metabolismo , Células Dendríticas/enzimología , Factor 1 Regulador del Interferón/metabolismo , Factores Reguladores del Interferón/metabolismo , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Receptores Toll-Like/metabolismo , Animales , Bordetella pertussis/metabolismo , Células Dendríticas/efectos de los fármacos , Dinoprostona/farmacología , Activación Enzimática/efectos de los fármacos , Femenino , Regulación de la Expresión Génica/efectos de los fármacos , Interferón gamma/farmacología , Interleucina-10/genética , Interleucina-10/metabolismo , Interleucina-12/antagonistas & inhibidores , Interleucina-12/biosíntesis , Lipopolisacáridos/farmacología , Ratones , Ratones Endogámicos C57BL , FN-kappa B/metabolismo , Fosforilación/efectos de los fármacos , ARN Mensajero/genética , ARN Mensajero/metabolismo , Receptores Toll-Like/agonistasRESUMEN
TLR ligands are potent adjuvants and promote Th1 responses to coadministered Ags by inducing innate IL-12 production. We found that TLR ligands also promote the induction of IL-10-secreting regulatory T (Treg) cells through p38 MAPK-induced IL-10 production by dendritic cells (DC). Inhibition of p38 suppressed TLR-induced IL-10 and PGE(2) and enhanced IL-12 production in DC. Incubation of Ag-pulsed CpG-stimulated DC with a p38 inhibitor suppressed their ability to generate Treg cells, while enhancing induction of Th1 cells. In addition, inhibition of p38 enhanced the antitumor therapeutic efficacy of DC pulsed with Ag and CpG and this was associated with an enhanced frequency of IFN-gamma-secreting T cells and a reduction of Foxp3(+) Treg cells infiltrating the tumors. Furthermore, addition of a p38 inhibitor to a pertussis vaccine formulated with CpG enhanced its protective efficacy in a murine respiratory challenge model. These data demonstrate that the adjuvant activity of TLR agonists is compromised by coinduction of Treg cells, but this can be overcome by inhibiting p38 signaling in DC. Our findings suggest that p38 is an important therapeutic target and provides a mechanism to enhance the efficacy of TLR agonists as vaccine adjuvants and cancer immunotherapeutics.
Asunto(s)
Adyuvantes Inmunológicos/uso terapéutico , Vacunas contra el Cáncer/uso terapéutico , Células Dendríticas/trasplante , Activación de Linfocitos/inmunología , Sistema de Señalización de MAP Quinasas/inmunología , Melanoma Experimental/terapia , Linfocitos T Reguladores/inmunología , Receptores Toll-Like/agonistas , Proteínas Quinasas p38 Activadas por Mitógenos/antagonistas & inhibidores , Adyuvantes Inmunológicos/administración & dosificación , Animales , Vacunas contra el Cáncer/administración & dosificación , Línea Celular Tumoral , Células Cultivadas , Células Dendríticas/enzimología , Células Dendríticas/metabolismo , Inmunoterapia Adoptiva , Ligandos , Melanoma Experimental/enzimología , Melanoma Experimental/inmunología , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Transgénicos , Linfocitos T Reguladores/metabolismo , Células TH1/inmunología , Receptores Toll-Like/metabolismo , Proteínas Quinasas p38 Activadas por Mitógenos/fisiologíaRESUMEN
It was recently demonstrated that interleukin (IL)-23-driven IL-17-producing (ThIL-17) T cells mediate inflammatory pathology in certain autoimmune diseases. We show that the induction of antigen-specific ThIL-17 cells, but not T helper (Th)1 or Th2 cells, by immunization with antigens and adjuvants is abrogated in IL-1 receptor type I-deficient (IL-1RI(-/-)) mice. Furthermore, the incidence of experimental autoimmune encephalomyelitis (EAE) was significantly lower in IL-1RI(-/-) compared with wild-type mice, and this correlated with a failure to induce autoantigen-specific ThIL-17 cells, whereas induction of Th1 and Th2 responses was not substantially different. However, EAE was induced in IL-1RI(-/-) mice by adoptive transfer of autoantigen-specific cells from wild-type mice with EAE. IL-23 alone did not induce IL-17 production by T cells from IL-1RI(-/-) mice, and IL-23-induced IL-17 production was substantially enhanced by IL-1alpha or IL-1beta, even in the absence of T cell receptor stimulation. We demonstrate essential roles for phosphatidylinositol 3-kinase, nuclear factor kappaB, and novel protein kinase C isoforms in IL-1- and IL-23-mediated IL-17 production. Tumor necrosis factor alpha also synergized with IL-23 to enhance IL-17 production, and this was IL-1 dependent. Our findings demonstrate that IL-1 functions upstream of IL-17 to promote pathogenic ThIL-17 cells in EAE.