RESUMO
BACKGROUND: Effector functions of IgG Abs are regulated by their Fc N-glycosylation pattern. IgG Fc glycans that lack galactose and terminal sialic acid residues correlate with the severity of inflammatory (auto)immune disorders and have also been linked to protection against viral infection and discussed in the context of vaccine-induced protection. In contrast, sialylated IgG Abs have shown immunosuppressive effects. OBJECTIVE: We sought to investigate IgG glycosylation programming during the germinal center (GC) reaction following immunization of mice with a foreign protein antigen and different adjuvants. METHODS: Mice were analyzed for GC T-cell, B-cell, and plasma cell responses, as well as for antigen-specific serum IgG subclass titers and Fc glycosylation patterns. RESULTS: Different adjuvants induce distinct IgG+ GC B-cell responses with specific transcriptomes and expression levels of the α2,6-sialyltransferase responsible for IgG sialylation that correspond to distinct serum IgG Fc glycosylation patterns. Low IgG Fc sialylation programming in GC B cells was overall highly dependent on the Foxp3- follicular helper T (TFH) cell-inducing cytokine IL-6, here in particular induced by water-in-oil adjuvants and Mycobacterium tuberculosis. Furthermore, low IgG Fc sialylation programming was dependent on adjuvants that induced IL-27 receptor-dependent IFN-γ+ TFH1 cells, IL-6/IL-23-dependent IL-17A+ TFH17 cells, and high ratios of TFH cells to Foxp3+ follicular regulatory T cells. Here, the 2 latter were dependent on M tuberculosis and its cord factor. CONCLUSION: This study's findings regarding adjuvant-dependent GC responses and IgG glycosylation programming may aid in the development of novel vaccination strategies to induce IgG Abs with both high affinity and defined Fc glycosylation patterns in the GC.
Assuntos
Adjuvantes Imunológicos/administração & dosagem , Antígenos/administração & dosagem , Centro Germinativo/imunologia , Imunoglobulina G/imunologia , Compostos de Alúmen/administração & dosagem , Animais , Linfócitos B/efeitos dos fármacos , Linfócitos B/imunologia , Citocinas/imunologia , Feminino , Adjuvante de Freund/administração & dosagem , Glicosilação , Lipopolissacarídeos/administração & dosagem , Camundongos Endogâmicos C57BL , Camundongos Knockout , Óleo Mineral/administração & dosagem , Mycobacterium tuberculosis/imunologia , Ovalbumina/administração & dosagem , Polissorbatos/administração & dosagem , Esqualeno/administração & dosagem , Linfócitos T/efeitos dos fármacos , Linfócitos T/imunologia , VacinaçãoRESUMO
During experimental tuberculosis (TB), interleukin (IL)-17A appears to be involved in the formation of lung granulomas, possibly through the attraction of neutrophils to the sites of infection. However, the protective impact of cytokine appears to depend on the degree of its induction. Hence, robust production of IL-17A in mice infected with the hypervirulent isolate Mycobacterium tuberculosis (Mtb) HN878 mediates protection, while the cytokine is dispensable for protective immune responses against low-dose infection with the less virulent strain H37rv. Here, we show that after experimental infection with high doses of Mtb H37rv, IL-17A-deficient (-/-) mice exhibited high susceptibility to the infection, which was mediated by the strong accumulation of neutrophils in the infected lung tissue. Accordingly, we observed nearly unrestricted bacterial replication within the neutrophils, indicating that they may serve as a survival niche for Mtb. By use of IL-17A/IL-17F-double-deficient mice, we demonstrated that the susceptibility in the absence of IL-17A is mediated by a compensatory expression of IL-17F, which, however, appeared not to be dependent on neutrophils. Together, our results illustrate the compensatory potential of the Th17-secreted cytokines IL-17A and IL-17F in the context of experimental TB and once again emphasize the detrimental effect of excessive neutrophil infiltration in response to Mtb.
Assuntos
Interleucina-17 , Tuberculose , Animais , Citocinas/metabolismo , Interleucina-17/deficiência , Interleucina-17/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mycobacterium tuberculosis/metabolismo , Tuberculose/imunologiaRESUMO
Interleukin (IL)-17A-producing T helper (Th)17 cells are increasingly being acknowledged to be associated with protective immunity to Mycobacterium tuberculosis (Mtb). Subunit vaccines potently promote protective immune responses against Mtb infection that correlate with an expansion of IL-23-dependent Th17 cells. Previous studies revealed that after vaccination, IL-23 is required for protection against challenge with Mtb but the underlying IL-23-dependent-and possibly IL-17A-mediated-mechanisms remain elusive. Therefore, we here analyzed the early outcome of Mtb infection in C57BL/6, IL-23p19-deficient (-/-), and IL-17A-/- mice after vaccination with the subunit vaccine H1-DDA/TDB to investigate the role of the IL-23-Th17 immune axis for the instruction of vaccine-induced protection. While in IL-23p19-/- mice the protective effect was reduced, protection after vaccination was maintained in IL-17A-/- animals for the course of infection of 6 weeks, indicating that after vaccination with H1-DDA/TDB early protection against Mtb is-although dependent on IL-23-not mediated by IL-17A. In contrast, IL-17A deficiency appears to have an impact on maintaining long-term protection. In fact, IL-23 instructed the vaccine-induced memory immunity in the lung, in particular the sustained expansion of tumor necrosis factor (TNF)+IL-2+ multifunctional T cells, independently of IL-17A. Altogether, a targeted induction of IL-23 during vaccination against Mtb might improve the magnitude and quality of vaccine-induced memory immune responses. KEY MESSAGES: After subunit Mtb vaccination with H1-DDA/TDB, IL-23 but not IL-17A contributes to vaccine-induced early protection against infection with Mtb. IL-17F does not compensate for IL-17A deficiency in terms of H1-DDA/TDB-induced protection against Mtb infection. IL 23 promotes the H1-DDA/TDB-induced accumulation of effector memory T cells independently of IL 17A. IL-23 arbitrates the induction of H1-specific IFN-γ-TNF+IL-2+ double-positive multifunctional CD4 T cells after subunit Mtb vaccination in an IL-17A-independent manner.
Assuntos
Antígenos de Bactérias/administração & dosagem , Linfócitos T CD4-Positivos/efeitos dos fármacos , Interleucina-23/imunologia , Vacinas contra a Tuberculose/administração & dosagem , Vacinas de Subunidades Antigênicas/administração & dosagem , Animais , Linfócitos T CD4-Positivos/imunologia , Feminino , Interleucina-17/genética , Interleucina-17/imunologia , Interleucina-23/genética , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mycobacterium tuberculosis/imunologia , Tuberculose/prevenção & controleRESUMO
The immune response to mycobacteria is characterized by granuloma formation, which features multinucleated giant cells as a unique macrophage type. We previously found that multinucleated giant cells result from Toll-like receptor-induced DNA damage and cell autonomous cell cycle modifications. However, the giant cell progenitor identity remained unclear. Here, we show that the giant cell-forming potential is a particular trait of monocyte progenitors. Common monocyte progenitors potently produce cytokines in response to mycobacteria and their immune-active molecules. In addition, common monocyte progenitors accumulate cholesterol and lipids, which are prerequisites for giant cell transformation. Inducible monocyte progenitors are so far undescribed circulating common monocyte progenitor descendants with high giant cell-forming potential. Monocyte progenitors are induced in mycobacterial infections and localize to granulomas. Accordingly, they exhibit important immunological functions in mycobacterial infections. Moreover, their signature trait of high cholesterol metabolism may be piggy-backed by mycobacteria to create a permissive niche.
Assuntos
Citocinas/imunologia , Células Gigantes/imunologia , Macrófagos/imunologia , Monócitos/imunologia , Células-Tronco/imunologia , Animais , Células Cultivadas , Citocinas/metabolismo , Feminino , Células Gigantes/metabolismo , Células Gigantes/microbiologia , Granuloma/imunologia , Granuloma/metabolismo , Humanos , Macrófagos/metabolismo , Macrófagos/microbiologia , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Monócitos/metabolismo , Monócitos/microbiologia , Mycobacterium/imunologia , Mycobacterium/fisiologia , Células-Tronco/metabolismo , Células-Tronco/microbiologiaRESUMO
In view of emerging drug-resistant tuberculosis (TB), host-directed adjunct therapies are urgently needed to improve treatment outcomes with currently available anti-TB therapies. One approach is to interfere with the formation of lipid-laden "foamy" macrophages in the host, as they provide a nutrient-rich host cell environment for Mycobacterium tuberculosis (Mtb). Here, we provide evidence that Wnt family member 6 (WNT6), a ligand of the evolutionarily conserved Wingless/Integrase 1 (WNT) signaling pathway, promotes foam cell formation by regulating key lipid metabolic genes including acetyl-CoA carboxylase 2 (ACC2) during pulmonary TB. Using genetic and pharmacological approaches, we demonstrated that lack of functional WNT6 or ACC2 significantly reduced intracellular triacylglycerol (TAG) levels and Mtb survival in macrophages. Moreover, treatment of Mtb-infected mice with a combination of a pharmacological ACC2 inhibitor and the anti-TB drug isoniazid (INH) reduced lung TAG and cytokine levels, as well as lung weights, compared with treatment with INH alone. This combination also reduced Mtb bacterial numbers and the size of mononuclear cell infiltrates in livers of infected mice. In summary, our findings demonstrate that Mtb exploits WNT6/ACC2-induced storage of TAGs in macrophages to facilitate its intracellular survival, a finding that opens new perspectives for host-directed adjunctive treatment of pulmonary TB.
Assuntos
Acetil-CoA Carboxilase/metabolismo , Macrófagos/metabolismo , Macrófagos/microbiologia , Mycobacterium tuberculosis/metabolismo , Mycobacterium tuberculosis/patogenicidade , Proteínas Proto-Oncogênicas/metabolismo , Triglicerídeos/metabolismo , Proteínas Wnt/metabolismo , Acetil-CoA Carboxilase/antagonistas & inibidores , Animais , Antituberculosos/administração & dosagem , Inibidores Enzimáticos/administração & dosagem , Células Espumosas/metabolismo , Interações entre Hospedeiro e Microrganismos/efeitos dos fármacos , Interações entre Hospedeiro e Microrganismos/fisiologia , Humanos , Isoniazida/administração & dosagem , Pulmão/efeitos dos fármacos , Pulmão/metabolismo , Pulmão/microbiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mycobacterium tuberculosis/efeitos dos fármacos , Proteínas Proto-Oncogênicas/deficiência , Proteínas Proto-Oncogênicas/genética , Transdução de Sinais/efeitos dos fármacos , Tuberculose Pulmonar/tratamento farmacológico , Tuberculose Pulmonar/metabolismo , Tuberculose Pulmonar/microbiologia , Proteínas Wnt/deficiência , Proteínas Wnt/genéticaRESUMO
Anti-inflammatory treatment of chronic inflammatory diseases often increases susceptibility to infectious diseases such as tuberculosis (TB). Since numerous chronic inflammatory and autoimmune diseases are mediated by interleukin (IL)-6-induced T helper (TH) 17 cells, a TH17-directed anti-inflammatory therapy may be preferable to an IL-12-dependent TH1 inhibition in order to avoid reactivation of latent infections. To assess, however, the risk of inhibition of IL-6-dependent TH17-mediated inflammation, we examined the TH17 immune response and the course of experimental TB in IL-6- and T-cell-specific gp130-deficient mice. Our study revealed that the absence of IL-6 or gp130 on T cells has only a minor effect on the development of antigen-specific TH1 and TH17 cells. Importantly, these gene-deficient mice were as capable as wild type mice to control mycobacterial infection. Together, in contrast to its key function for TH17 development in other inflammatory diseases, IL-6 plays an inferior role for the generation of TH17 immune responses during experimental TB.
Assuntos
Receptor gp130 de Citocina/imunologia , Interleucina-17/imunologia , Interleucina-6/imunologia , Células Th17/imunologia , Tuberculose/imunologia , Imunidade Adaptativa , Animais , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Células Th17/citologiaRESUMO
Host-modulating therapies have become an important focus in the development of novel concepts for improved management of tuberculosis (TB). Previous in vitro studies revealed that the p38 MAP kinase signaling pathway coordinates several inflammatory and stress responses in Mycobacterium tuberculosis (Mtb)-infected host cells. Here we extend these findings and show that in vivo treatment of Mtb-infected C57BL/6 mice with doramapimod, a p38 MAP-kinase inhibitor, results in reduced inflammation, granuloma formation and lung pathology. Moreover, doramapimod, together with standard antibiotic treatment, significantly reduced lung and spleen mycobacterial loads compared to antibiotic treatment alone. Our in vivo data suggest the opportunity to repurpose p38 MAPK inhibitors for adjunct host directed therapies. We also provide first data on safety of p38 MAPK inhibition which is of relevance for future application of these substances in inflammatory diseases and concomitant TB.
Assuntos
Antituberculosos/farmacologia , Mycobacterium tuberculosis/efeitos dos fármacos , Pneumonia/prevenção & controle , Tuberculose/tratamento farmacológico , Proteínas Quinases p38 Ativadas por Mitógeno/antagonistas & inibidores , Animais , Camundongos , Camundongos Endogâmicos C57BL , Mycobacterium tuberculosis/imunologia , Pneumonia/imunologia , Tuberculose/microbiologiaRESUMO
Macrophage activation can be divided into a classical and an alternative pathway. Interferon-gamma-induced, classically activated macrophages are indispensable for protective effector responses against intracellular pathogens. However, excessive inflammatory immune responses mediated by classical macrophage activation can also be detrimental to the host. In contrast, the IL-4 receptor-alpha-mediated alternative pathway of macrophage activation has been proposed as a mechanism to attenuate excessive inflammation. Indeed, the generation of macrophage/neutrophil-specific IL-4 receptor-alpha-deficient mice (LysMcreIL-4Ralphaalpha-/lox) enables us now to evaluate the importance of this type of macrophage activation in vivo. Thus, the analysis of LysMcreIL-4Ralpha-/lox mice and the phenotypic characterization of macrophage activation during inflammatory immune responses become of major importance for inflammation research, and useful markers have been identified that allow classically and alternatively activated macrophages to be distinguished. Inducible nitric oxide synthase and arginase-1 are not only prototypical markers of classical and alternative macrophage activation, but both enzymes are also strongly involved in regulating macrophage effector mechanisms and inflammatory immune responses. In this chapter, we describe the use of LysMcreIL-4Ralpha-/lox mice and present experimental procedures to determine classical versus alternative macrophage activation by analyzing nitric oxide synthase and arginase-1 in vitro and in vivo in this murine model.
Assuntos
Ativação de Macrófagos/imunologia , Macrófagos/imunologia , Biologia Molecular/métodos , Neutrófilos/imunologia , Receptores de Superfície Celular/deficiência , Animais , Arginase , Arginina/metabolismo , Sítios de Ligação , Cruzamento , Genótipo , Macrófagos/citologia , Macrófagos/enzimologia , Camundongos , Neutrófilos/citologia , Neutrófilos/enzimologia , Óxido Nítrico/biossíntese , Óxido Nítrico Sintase Tipo II/metabolismo , Fenótipo , Ureia/metabolismoRESUMO
gp130 cytokines are differentially involved in regulating the T helper (H) 17-driven pathogenesis of experimental autoimmune encephalomyelitis (EAE), the animal model of human multiple sclerosis. Interleukin (IL)-6 directly promotes the development of TH17 cells through the gp130/IL-6R complex. By contrast, IL-27 has been shown to suppress a TH17 immune response by gp130/IL-27R-alpha (α) receptor ligation. The IL-27-dependent regulation of a TH17 development could be mediated on the level of CD4 T cells. However, because IL-27 also suppresses the secretion of the TH17-driving cytokines IL-6 and IL-12/23p40 in accessory cells, TH17 immune responses may also be controlled by IL-27 on the level of macrophages and/or neutrophils. To analyze these opposing effects of gp130 engagement on the pathogenesis of EAE, we immunized CD4+ T cell-specific gp130-deficient (CD4creposgp130loxP/loxP) and macrophage/neutrophil-specific gp130-deficient (LysMcreposgp130loxP/loxP) mice with the myelin-oligodendrocyte-glycoprotein peptide MOG35-55. Whereas inflammatory immune responses, TH17 differentiation, and pathology in CD4creposgp130loxP/loxP mice were mitigated, disease progression was eventually enhanced in LysMcreposgp130loxP/loxP mice. Exacerbated disease in MOG35-55-immunized LysMcreposgp130loxP/loxP mice was associated with an elevated development of TH17 cells and increased infiltration of the central nervous system with leukocytes indicating a suppressive role of macrophage/neutrophil-gp130. To further prove IL-6 to be responsible for the control of inflammation during EAE through gp130 on macrophages/neutrophils, we immunized LysMcreposIL-6RloxP/loxP mice. In contrast to LysMcreposgp130loxP/loxP mice, neuropathology in MOG35-55-immunized macrophage/neutrophil-specific IL-6R-deficient mice was not enhanced indicating that the alleviation of EAE through macrophage/neutrophil-gp130 is mediated independently of IL-6. Together, this different pathology in macrophage/neutrophil- and CD4 T cell-specific gp130-deficient mice suggests that gp130 cytokines modulate TH17 inflammation differentially by targeting distinct cell types.
Assuntos
Receptor gp130 de Citocina/genética , Encefalomielite Autoimune Experimental/imunologia , Macrófagos/imunologia , Neutrófilos/imunologia , Células Th17/imunologia , Animais , Diferenciação Celular , Sistema Nervoso Central/imunologia , Receptor gp130 de Citocina/deficiência , Citocinas/imunologia , Modelos Animais de Doenças , Progressão da Doença , Encefalomielite Autoimune Experimental/patologia , Inflamação , Camundongos , Glicoproteína Mielina-Oligodendrócito/administração & dosagem , Células Th1/imunologiaRESUMO
During Mycobacterium tuberculosis (Mtb) infection, mice lacking the IL-27R exhibit lower bacterial burdens but develop an immunopathological sequelae in comparison to wild-type mice. We here show that this phenotype correlates with an enhanced recruitment of antigen-specific CCR6+ CD4+ T cells and an increased frequency of IL-17A-producing CD4+ T cells. By comparing the outcome of Mtb infection in C57BL/6, IL-27R-deficient and IL-27R/IL-17A-double deficient mice, we observed that both the increased protection and elevated immunopathology are supported by IL-17A. Whereas IL-17A neither impacts the development of Tr1 cells nor the expression of PD1 and KLRG1 on T cells in IL-27R-deficient mice during infection, it regulates the presence of multifunctional T-cells in the lungs, co-expressing IFN-γ, IL-2 and TNF. Eventually, IL-17A supports Cxcl9, Cxcl10 and Cxcl13 expression and the granulomatous response in the lungs of infected IL-27R-deficient mice. Taken together, IL-17A contributes to protection in Mtb-infected IL-27R-deficient mice probably through a chemokine-mediated recruitment and strategic positioning of multifunctional T cells in granulomas. As IL-27 limits optimal antimycobacterial protection by inhibiting IL-17A production, blocking of IL-27R-mediated signaling may represent a strategy for improving vaccination and host-directed therapy in tuberculosis. However, because IL-27 also prevents IL-17A-mediated immunopathology, such intervention has to be tightly controlled.
Assuntos
Granuloma/imunologia , Interleucina-17/metabolismo , Pulmão/imunologia , Mycobacterium tuberculosis/fisiologia , Receptores de Citocinas/metabolismo , Tuberculose/imunologia , Animais , Proliferação de Células , Citocinas/metabolismo , Imunidade Inata , Mediadores da Inflamação/metabolismo , Interleucina-17/genética , Pulmão/microbiologia , Ativação Linfocitária , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores de Citocinas/genética , Receptores de InterleucinaRESUMO
Mycobacterium tuberculosis (Mtb), the causative agent of human tuberculosis, is able to efficiently manipulate the host immune system establishing chronic infection, yet the underlying mechanisms of immune evasion are not fully understood. Evidence suggests that this pathogen interferes with host cell lipid metabolism to ensure its persistence. Fatty acid metabolism is regulated by acetyl-CoA carboxylase (ACC) 1 and 2; both isoforms catalyze the conversion of acetyl-CoA into malonyl-CoA, but have distinct roles. ACC1 is located in the cytosol, where it regulates de novo fatty acid synthesis (FAS), while ACC2 is associated with the outer mitochondrial membrane, regulating fatty acid oxidation (FAO). In macrophages, mycobacteria induce metabolic changes that lead to the cytosolic accumulation of lipids. This reprogramming impairs macrophage activation and contributes to chronic infection. In dendritic cells (DCs), FAS has been suggested to underlie optimal cytokine production and antigen presentation, but little is known about the metabolic changes occurring in DCs upon mycobacterial infection and how they affect the outcome of the immune response. We therefore determined the role of fatty acid metabolism in myeloid cells and T cells during Mycobacterium bovis BCG or Mtb infection, using novel genetic mouse models that allow cell-specific deletion of ACC1 and ACC2 in DCs, macrophages, or T cells. Our results demonstrate that de novo FAS is induced in DCs and macrophages upon M. bovis BCG infection. However, ACC1 expression in DCs and macrophages is not required to control mycobacteria. Similarly, absence of ACC2 did not influence the ability of DCs and macrophages to cope with infection. Furthermore, deletion of ACC1 in DCs or macrophages had no effect on systemic pro-inflammatory cytokine production or T cell priming, suggesting that FAS is dispensable for an intact innate response against mycobacteria. In contrast, mice with a deletion of ACC1 specifically in T cells fail to generate efficient T helper 1 responses and succumb early to Mtb infection. In summary, our results reveal ACC1-dependent FAS as a crucial mechanism in T cells, but not DCs or macrophages, to fight against mycobacterial infection.
Assuntos
Células Dendríticas/imunologia , Ácidos Graxos/imunologia , Imunidade Inata , Macrófagos/imunologia , Mycobacterium tuberculosis/imunologia , Células Th1/imunologia , Tuberculose/imunologia , Acetil-CoA Carboxilase/genética , Acetil-CoA Carboxilase/imunologia , Animais , Células Dendríticas/microbiologia , Células Dendríticas/patologia , Ácidos Graxos/genética , Macrófagos/microbiologia , Macrófagos/patologia , Camundongos , Camundongos Knockout , Mycobacterium bovis/imunologia , Mycobacterium tuberculosis/genética , Células Th1/microbiologia , Células Th1/patologia , Tuberculose/genética , Tuberculose/patologiaRESUMO
The role of Toll-like receptors (TLR) and MyD88 for immune responses to Mycobacterium tuberculosis (Mtb) infection remains controversial. To address the impact of TLR-mediated pathogen recognition and MyD88-dependent signaling events on anti-mycobacterial host responses, we analyzed the outcome of Mtb infection in TLR2/4/9 triple- and MyD88-deficient mice. After aerosol infection, both TLR2/4/9-deficient and wild-type mice expressed pro-inflammatory cytokines promoting antigen-specific T cells and the production of IFN-gamma to similar extents. Moreover, TLR2/4/9-deficient mice expressed IFN-gamma-dependent inducible nitric oxide synthase and LRG-47 in infected lungs. MyD88-deficient mice expressed pro-inflammatory cytokines and were shown to expand IFN-gamma-producing antigen-specific T cells, albeit in a delayed fashion. Only mice that were deficient for MyD88 rapidly succumbed to unrestrained mycobacterial growth, whereas TLR2/4/9-deficient mice controlled Mtb replication. IFN-gamma-dependent restriction of mycobacterial growth was severely impaired only in Mtb-infected MyD88, but not in TLR2/4/9-deficient bone marrow-derived macrophages. Our results demonstrate that after Mtb infection neither TLR2, -4, and -9, nor MyD88 are required for the induction of adaptive T cell responses. Rather, MyD88, but not TLR2, TLR4 and TLR9, is critical for triggering macrophage effector mechanisms central to anti-mycobacterial defense.
Assuntos
Mycobacterium tuberculosis/imunologia , Fator 88 de Diferenciação Mieloide/fisiologia , Receptor 2 Toll-Like/fisiologia , Receptor 4 Toll-Like/fisiologia , Receptor Toll-Like 9/fisiologia , Tuberculose/imunologia , Estruturas Animais/microbiologia , Animais , Citocinas/genética , Citocinas/metabolismo , Proteínas de Ligação ao GTP/genética , Proteínas de Ligação ao GTP/metabolismo , Expressão Gênica/efeitos dos fármacos , Imunidade Celular/genética , Imunidade Celular/imunologia , Imunidade Inata/genética , Imunidade Inata/imunologia , Interferon gama/metabolismo , Interferon gama/farmacologia , Lipopolissacarídeos/farmacologia , Pulmão/imunologia , Pulmão/metabolismo , Pulmão/microbiologia , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Macrófagos/microbiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fator 88 de Diferenciação Mieloide/agonistas , Fator 88 de Diferenciação Mieloide/genética , Óxido Nítrico Sintase Tipo II/genética , Óxido Nítrico Sintase Tipo II/metabolismo , Oligodesoxirribonucleotídeos/farmacologia , Linfócitos T/imunologia , Linfócitos T/metabolismo , Receptor 2 Toll-Like/agonistas , Receptor 2 Toll-Like/genética , Receptor 4 Toll-Like/agonistas , Receptor 4 Toll-Like/genética , Receptor Toll-Like 9/agonistas , Receptor Toll-Like 9/genética , Tuberculose/genética , Tuberculose/microbiologia , Fator de Necrose Tumoral alfa/metabolismo , Fator de Necrose Tumoral alfa/farmacologiaRESUMO
CD8+ T cells are involved in protection against Mycobacterium tuberculosis infection and represent a promising target for new vaccine strategies. Because IL-15 is important for the homeostasis of CD8+ T cells, we studied the immune response in IL-15-deficient mice during tuberculosis. In the absence of IL-15, CD8+ T cells failed to efficiently accumulate in draining lymph nodes and at the site of infection. The expression of antigen-specific effector functions, such as the production of interferon-gamma and cytotoxicity, were impaired in CD8+ T cells, but not CD4+ T cells, from IL-15-deficient mice. This defect was associated with an increased mortality of IL-15-deficient mice during the chronic phase of infection. The lectin-like stimulatory receptor natural killer group 2D (NKG2D) was up-regulated on CD8+ T cells only from wild-type mice, but not from IL-15-deficient mice. Mechanistically, blocking NKG2D function with an mAb inhibited M. tuberculosis-directed CD8+ T cell responses in vitro. We conclude that in addition to regulating the expansion of CD8+ T cells, IL-15 is also necessary for inducing effector mechanisms in CD8+ T cells that depend on NKG2D expression. Hence, our results implicate IL-15 and NKG2D as promising targets for modulating CD8+ T cell-mediated protection against tuberculosis.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Interleucina-15/fisiologia , Receptores Imunológicos/fisiologia , Tuberculose/imunologia , Animais , Feminino , Interferon gama/biossíntese , Camundongos , Camundongos Endogâmicos C57BL , Subfamília K de Receptores Semelhantes a Lectina de Células NK , Receptores de Células Matadoras NaturaisRESUMO
Immunity to Mycobacterium tuberculosis infection is critically dependent on the timely priming of T effector lymphocytes and their efficient recruitment to the site of mycobacterial implantation in the lung. E-, P-, and L-selectin counterreceptors control lymphocyte homing to lymph nodes and leukocyte trafficking to peripheral sites of acute inflammation, their adhesive function depending on fucosylation by fucosyltransferases (FucT) IV and VII. To address the relative importance of differentially glycosylated selectin counterreceptors for priming of T cell effector functions in a model of mycobacteria-induced granulomatous pulmonary inflammation, we used aerosol-borne M. tuberculosis to infect FucT-IV-/-, FucT-VII-/-, FucT-IV-/-/FucT-VII-/-, or wild-type control mice. In lymph nodes, infected FucT-IV-/-/FucT-VII-/- and, to a lesser extent, FucT-VII-/- mice had severely reduced numbers of T cells and reduced Ag-specific effector responses. By contrast, recruitment of activated T cells into the lungs was similar in all four groups of mice during infection and expression of T cell, and macrophage effector functions were only delayed in lungs of FucT-IV-/-/FucT-VII-/- mice. Importantly, lungs from all groups expressed CXCL13, CCL21, and CCL19 and displayed organized follicular neolymphoid structures after infection with M. tuberculosis, which suggests that the lung served as a selectin ligand-independent priming site for immune responses to mycobacterial infection. All FucT-deficient strains were fully capable of restricting M. tuberculosis growth in infected organs until at least 150 days postinfection. Our observations indicate that leukocyte recruitment functions dictated by FucT-IV and FucT-VII-dependent selectin ligand activities are not critical for inducing or maintaining T cell effector responses at levels necessary to control pulmonary tuberculosis.
Assuntos
Selectinas/metabolismo , Linfócitos T/imunologia , Tuberculose Pulmonar/imunologia , Tuberculose Pulmonar/metabolismo , Animais , Quimiocinas/genética , Citocinas/metabolismo , Fucosiltransferases/deficiência , Fucosiltransferases/genética , Expressão Gênica/efeitos dos fármacos , Hipersensibilidade Tardia , Interferon gama/farmacologia , Ligantes , Pulmão/imunologia , Pulmão/metabolismo , Pulmão/patologia , Linfonodos/imunologia , Linfonodos/patologia , Ativação Linfocitária , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mycobacterium tuberculosis/imunologia , Mycobacterium tuberculosis/isolamento & purificação , Receptores de Retorno de Linfócitos/metabolismo , Proteínas Recombinantes , Células Th1/imunologia , Células Th1/patologia , Tuberculose Pulmonar/genética , Tuberculose Pulmonar/patologiaRESUMO
IL-12 is a potent inducer of IFN-gamma production and promotes a protective cell-mediated immune response after Mycobacterium tuberculosis infection. Recently, the IL-12-related cytokine IL-27 was discovered, and WSX-1 was identified as one component of the IL-27R complex. To determine the functional significance of IL-27/WSX-1 during tuberculosis, we analyzed the course of infection and the immune response in WSX-1-KO mice after aerosol infection with M. tuberculosis. In the absence of WSX-1, an increased production of the proinflammatory cytokines TNF and IL-12p40 resulted in elevated CD4+ T cell activation and IFN-gamma production, which enhanced macrophage effector functions and reduced bacterial loads. This is the first occasion of a selectively gene-deficient mouse strain showing higher levels of protective immunity against M. tuberculosis infection than wild-type mice. However, a concomitantly increased chronic inflammatory response also accelerated death of infected WSX-1-KO mice. In vitro, IL-27 induced STAT3 phosphorylation and inhibited TNF and IL-12 production in activated peritoneal macrophages, indicating a novel feedback mechanism by which IL-27 can modulate excessive inflammation. In conclusion, IL-27 both prevents optimal antimycobacterial protection and limits the pathological sequelae of chronic inflammation.