RESUMO
Toll-like receptor 11 (TLR11) recognizes T. gondii profilin (TgPRF) and is required for interleukin-12 production and induction of immune responses that limit cyst burden in Toxoplasma gondii-infected mice. However, TLR11 only modestly affects survival of T. gondii-challenged mice. We report that TLR12, a previously uncharacterized TLR, also recognized TgPRF. TLR12 was sufficient for recognition of TgPRF by plasmacytoid dendritic cells (pDCs), whereas TLR11 and TLR12 were both required in macrophages and conventional DCs. In contrast to TLR11, TLR12-deficient mice succumb rapidly to T. gondii infection. TLR12-dependent induction of IL-12 and IFN-α in pDCs led to production of IFN-γ by NK cells. Consistent with this observation, the partial resistance of Tlr11(-/-) mice is lost upon pDC or NK cell depletion. Thus, TLR12 is critical for the innate immune response to T. gondii, and this TLR may promote host resistance by triggering pDC and NK cell function.
Assuntos
Interações Hospedeiro-Patógeno/imunologia , Profilinas/metabolismo , Receptores Toll-Like/metabolismo , Toxoplasma/imunologia , Toxoplasmose Animal/imunologia , Toxoplasmose Animal/metabolismo , Sequência de Aminoácidos , Animais , Células da Medula Óssea/imunologia , Células da Medula Óssea/metabolismo , Células Dendríticas/imunologia , Células Dendríticas/metabolismo , Predisposição Genética para Doença , Imunidade Inata , Interferon-alfa/biossíntese , Interferon gama/biossíntese , Interleucina-12/biossíntese , Células Matadoras Naturais/imunologia , Células Matadoras Naturais/metabolismo , Camundongos , Camundongos Knockout , Dados de Sequência Molecular , NF-kappa B/metabolismo , Profilinas/imunologia , Ligação Proteica , Multimerização Proteica , Alinhamento de Sequência , Receptores Toll-Like/química , Receptores Toll-Like/genética , Receptores Toll-Like/imunologia , Toxoplasmose Animal/genéticaRESUMO
Dendritic cells (DCs), monocytes, and/or macrophages initiate host-protective immune responses to intracellular pathogens in part through interleukin-12 (IL-12) production, although the relative contribution of tissue resident versus recruited cells has been unclear. Here, we showed that after intraperitoneal infection with Toxoplasma gondii cysts, resident mononuclear phagocytes are replaced by circulating monocytes that differentiate in situ into inflammatory DCs (moDCs) and F4/80(+) macrophages. Importantly, NK cell-derived interferon-γ (IFN-γ) was required for both the loss of resident mononuclear phagocytes and the local differentiation of monocytes into macrophages and moDCs. This newly generated moDC population and not the resident DCs (or macrophages) served as the major source of IL-12 at the site of infection. Thus, NK cell-derived IFN-γ is important in both regulating inflammatory cell dynamics and in driving the local differentiation of monocytes into the cells required for initiating the immune response to an important intracellular pathogen.
Assuntos
Células Dendríticas/imunologia , Interferon gama/fisiologia , Células Matadoras Naturais/imunologia , Monócitos/imunologia , Transferência Adotiva , Animais , Antígenos Ly/análise , Diferenciação Celular , Quimiotaxia de Leucócito , Células Dendríticas/patologia , Células Dendríticas/transplante , Genes Reporter , Subunidade p40 da Interleucina-12/biossíntese , Subunidade p40 da Interleucina-12/genética , Células Matadoras Naturais/metabolismo , Macrófagos Peritoneais/imunologia , Macrófagos Peritoneais/transplante , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Monócitos/química , Monócitos/patologia , Monócitos/transplante , Fator 88 de Diferenciação Mieloide/fisiologia , Neutrófilos/imunologia , Peritonite/imunologia , Peritonite/parasitologia , Fagócitos/classificação , Fagócitos/imunologia , Fagócitos/patologia , Receptores de Interferon/deficiência , Receptores de Interferon/fisiologia , Proteínas Recombinantes de Fusão/biossíntese , Proteínas Recombinantes de Fusão/genética , Organismos Livres de Patógenos Específicos , Subpopulações de Linfócitos T/imunologia , Toxoplasmose Animal/imunologia , Receptor de Interferon gamaRESUMO
Mice deficient in the interferon-gamma (IFN-gamma)-inducible, immunity-related GTPase Irgm1 have defective host resistance to a variety of intracellular pathogens. This greater susceptibility to infection is associated with impaired IFN-gamma-dependent macrophage microbicidal activity in vitro. Here we show that Irgm1 also regulated the survival of mature effector CD4(+) T lymphocytes by protecting them from IFN-gamma-induced autophagic cell death. Mice deficient in both IFN-gamma and Irgm1 were 'rescued' from the lymphocyte depletion and greater mortality that occurs in mice singly deficient in Irgm1 after mycobacterial infection. Our studies identify a feedback mechanism in the T helper type 1 response that limits the detrimental effects of IFN-gamma on effector T lymphocyte survival while promoting the antimicrobial functions of IFN-gamma.
Assuntos
Autofagia , Linfócitos T CD4-Positivos/imunologia , Proteínas de Ligação ao GTP/imunologia , Interferon gama/imunologia , Animais , Autofagia/genética , Linfócitos T CD4-Positivos/efeitos dos fármacos , Linfócitos T CD4-Positivos/ultraestrutura , Proliferação de Células , Sobrevivência Celular , Células Cultivadas , Feminino , Proteínas de Ligação ao GTP/genética , Interferon gama/genética , Interferon gama/farmacologia , Ativação Linfocitária , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mycobacterium avium/imunologia , Receptores de Antígenos de Linfócitos T/imunologia , Transdução de Sinais/imunologia , Toxoplasma/imunologia , Toxoplasmose/imunologia , Tuberculose/imunologiaRESUMO
Interleukin-1 (IL-1) receptor signaling is necessary for control of Mycobacterium tuberculosis (Mtb) infection, yet the role of its two ligands, IL-1α and IL-1ß, and their regulation in vivo are poorly understood. Here, we showed that both IL-1α and IL-1ß are critically required for host resistance and identified two multifunctional inflammatory monocyte-macrophage and DC populations that coexpressed both IL-1 species at the single-cell level in lungs of Mtb-infected mice. Moreover, we demonstrated that interferons (IFNs) played important roles in regulating IL-1 production by these cells in vivo. Type I interferons inhibited IL-1 production by both subsets whereas CD4(+) T cell-derived IFN-γ selectively suppressed monocyte-macrophages. These data provide a cellular basis for both the anti-inflammatory effects of IFNs and probacterial functions of type I IFNs during Mtb infection and reveal differential regulation of IL-1 production by distinct cell populations as an additional layer of complexity in the activity of IL-1 in vivo.
Assuntos
Interferons/metabolismo , Interleucina-1alfa/biossíntese , Interleucina-1beta/biossíntese , Pulmão/imunologia , Mycobacterium tuberculosis/imunologia , Células Mieloides/imunologia , Tuberculose Pulmonar/imunologia , Animais , Antígenos Ly/metabolismo , Antígeno CD11b/metabolismo , Linfócitos T CD4-Positivos/imunologia , Células Dendríticas/imunologia , Humanos , Subunidade p40 da Interleucina-12/biossíntese , Pulmão/metabolismo , Pulmão/microbiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Células Mieloides/metabolismo , Fagócitos/imunologia , Fagócitos/metabolismo , Fagócitos/microbiologia , Transdução de SinaisRESUMO
T follicular helper (Tfh) cells are a subset of CD4+ T lymphocytes that promote the development of humoral immunity. Although the triggers required for the differentiation of the other major Th subsets are well defined, those responsible for Tfh cell responses are still poorly understood. We determined that mice immunized with peptide or protein Ags emulsified in IFA or related water-in-oil adjuvants develop a highly polarized response in which the majority of the Ag-specific CD4+ T cells are germinal center-homing CXCR5+Bcl6+ Tfh cells. Despite the absence of exogenous microbial pathogen-associated molecular patterns, the Tfh cell responses observed were dependent, in part, on MyD88. Importantly, in addition to IL-6, T cell-intrinsic type I IFN signaling is required for optimal Tfh cell polarization. These findings suggest that water-in-oil adjuvants promote Tfh cell-dominated responses by triggering endogenous alarm signals that, in turn, induce type I IFN-dependent differentiation pathway functioning in T cells.
Assuntos
Adjuvantes Imunológicos/química , Interferon Tipo I/metabolismo , Interleucina-6/metabolismo , Linfócitos T Auxiliares-Indutores/imunologia , Animais , Antígenos/imunologia , Diferenciação Celular , Centro Germinativo/imunologia , Imunidade Humoral , Imunização , Interferon Tipo I/imunologia , Interleucina-6/imunologia , Ativação Linfocitária , Camundongos , Óleos , Peptídeos/imunologia , Receptores CXCR5/metabolismo , Transdução de Sinais , ÁguaRESUMO
As a major natural host for Toxoplasma gondii, the mouse is widely used for the study of the immune response to this medically important protozoan parasite. However, murine innate recognition of toxoplasma depends on the interaction of parasite profilin with TLR11 and TLR12, two receptors that are functionally absent in humans. This raises the question of how human cells detect and respond to T. gondii. In this study, we show that primary monocytes and dendritic cells from peripheral blood of healthy donors produce IL-12 and other proinflammatory cytokines when exposed to toxoplasma tachyzoites. Cell fractionation studies determined that IL-12 and TNF-α secretion is limited to CD16(+) monocytes and the CD1c(+) subset of dendritic cells. In direct contrast to their murine counterparts, human myeloid cells fail to respond to soluble tachyzoite extracts and instead require contact with live parasites. Importantly, we found that tachyzoite phagocytosis, but not host cell invasion, is required for cytokine induction. Together these findings identify CD16(+) monocytes and CD1c(+) dendritic cells as the major myeloid subsets in human blood-producing innate cytokines in response to T. gondii and demonstrate an unappreciated requirement for phagocytosis of live parasites in that process. This form of pathogen sensing is distinct from that used by mice, possibly reflecting a direct involvement of rodents and not humans in the parasite life cycle.
Assuntos
Células Dendríticas/imunologia , Interleucina-12/imunologia , Monócitos/imunologia , Toxoplasma/imunologia , Toxoplasmose/imunologia , Antígenos CD1/metabolismo , Células Cultivadas , Feminino , Proteínas Ligadas por GPI/metabolismo , Glicoproteínas/metabolismo , Humanos , Masculino , Fagocitose/imunologia , Receptores de IgG/metabolismo , Transdução de Sinais/imunologia , Toxoplasmose/parasitologia , Fator de Necrose Tumoral alfa/imunologiaRESUMO
The accumulation of improperly folded proteins within the endoplasmic reticulum (ER) generates perturbations known as ER stress that engage the unfolded protein response. ER stress is involved in many inflammatory pathologies that are also associated with the production of the proinflammatory cytokine IL-1ß. In this study, we demonstrate that macrophages undergoing ER stress are able to drive the production and processing of pro-IL-1ß in response to LPS stimulation in vitro. Interestingly, the classical NLRP3 inflammasome is dispensable, because maturation of pro-IL-1ß occurs normally in the absence of the adaptor protein ASC. In contrast, processing of pro-IL-1ß is fully dependent on caspase-8. Intriguingly, we found that neither the unfolded protein response transcription factors XBP1 and CHOP nor the TLR4 adaptor molecule MyD88 is necessary for caspase-8 activation. Instead, both caspase activation and IL-1ß production require the alternative TLR4 adaptor TRIF. This pathway may contribute to IL-1-driven tissue pathology in certain disease settings.
Assuntos
Proteínas Adaptadoras de Transporte Vesicular/imunologia , Caspase 8/metabolismo , Estresse do Retículo Endoplasmático/fisiologia , Interleucina-1beta/imunologia , Macrófagos/imunologia , Receptor 4 Toll-Like/imunologia , Proteínas Adaptadoras de Transporte Vesicular/genética , Animais , Caspase 8/genética , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/imunologia , Ativação Enzimática/genética , Ativação Enzimática/imunologia , Inflamação/genética , Inflamação/imunologia , Interleucina-1beta/genética , Macrófagos/citologia , Camundongos , Camundongos Knockout , Fator 88 de Diferenciação Mieloide/genética , Fator 88 de Diferenciação Mieloide/imunologia , Fatores de Transcrição de Fator Regulador X , Receptor 4 Toll-Like/genética , Fator de Transcrição CHOP/genética , Fator de Transcrição CHOP/imunologia , Fatores de Transcrição/genética , Fatores de Transcrição/imunologia , Resposta a Proteínas não Dobradas/fisiologia , Proteína 1 de Ligação a X-BoxRESUMO
Although adjuvants are critical vaccine components, their modes of action are poorly understood. In this study, we investigated the mechanisms by which the heat-killed mycobacteria in CFA promote Th17 CD4(+) T cell responses. We found that IL-17 secretion by CD4(+) T cells following CFA immunization requires MyD88 and IL-1ß/IL-1R signaling. Through measurement of Ag-specific responses after adoptive transfer of OTII cells, we confirmed that MyD88-dependent signaling controls Th17 differentiation rather than simply production of IL-17. Additional experiments showed that CFA-induced Th17 differentiation involves IL-1ß processing by the inflammasome, as mice lacking caspase-1, ASC, or NLRP3 exhibit partially defective responses after immunization. Biochemical fractionation studies further revealed that peptidoglycan is the major component of heat-killed mycobacteria responsible for inflammasome activation. By assaying Il1b transcripts in the injection site skin of CFA-immunized mice, we found that signaling through the adaptor molecule caspase activation and recruitment domain 9 (CARD9) plays a major role in triggering pro-IL-1ß expression. Moreover, we demonstrated that recognition of the mycobacterial glycolipid trehalose dimycolate (cord factor) by the C-type lectin receptor mincle partially explains this CARD9 requirement. Importantly, purified peptidoglycan and cord factor administered in mineral oil synergized to recapitulate the Th17-promoting activity of CFA, and, as expected, this response was diminished in caspase-1- and CARD9-deficient mice. Taken together, these findings suggest a general strategy for the rational design of Th17-skewing adjuvants by combining agonists of the CARD9 pathway with inflammasome activators.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Fatores Corda/imunologia , Lectinas Tipo C/metabolismo , Proteínas de Membrana/metabolismo , Mycobacterium/imunologia , Peptidoglicano/imunologia , Células Th17/imunologia , Células Th17/metabolismo , Adjuvantes Imunológicos , Animais , Proteínas Adaptadoras de Sinalização CARD , Diferenciação Celular/imunologia , Inflamassomos/metabolismo , Interleucina-1beta/metabolismo , Camundongos , Camundongos Knockout , Mycobacterium/química , Fator 88 de Diferenciação Mieloide/metabolismo , Receptores de Interleucina-1/metabolismo , Receptores de Interleucina-18/metabolismo , Transdução de Sinais , Células Th17/citologia , Receptores Toll-Like/metabolismoRESUMO
Following antiretroviral therapy, a significant proportion of HIV(+) patients with mycobacterial coinfections develop a paradoxical, poorly understood inflammatory disease termed immune reconstitution inflammatory syndrome (IRIS). Here, we show that Mycobacterium avium-infected T cell-deficient mice injected with CD4 T cells also develop an immune reconstitution disease (IRD) manifesting as weight loss, impaired lung function, and rapid mortality. This form of IRD requires Ag recognition and interferonγ production by the donor CD4 T cells and correlates with marked alterations in blood and tissue CD11b(+) myeloid cells. Interestingly, disease is associated with impaired, rather than augmented, T-cell expansion and function and is not strictly dependent on lymphopenia-induced T-cell proliferation. Instead, our findings suggest that mycobacterial-associated IRIS results from a heightened sensitivity of infected lymphopenic hosts to the detrimental effects of Ag-driven CD4 T-cell responses.
Assuntos
Síndrome Inflamatória da Reconstituição Imune/imunologia , Síndrome Inflamatória da Reconstituição Imune/microbiologia , Mycobacterium avium/imunologia , Células Th1/imunologia , Tuberculose/complicações , Animais , Antígenos de Bactérias/imunologia , Linfócitos T CD4-Positivos/citologia , Linfócitos T CD4-Positivos/imunologia , Citocinas/imunologia , Humanos , Síndrome Inflamatória da Reconstituição Imune/etiologia , Síndrome Inflamatória da Reconstituição Imune/fisiopatologia , Pulmão/fisiopatologia , Ativação Linfocitária , Depleção Linfocítica , Camundongos , Camundongos Endogâmicos C57BL , Mycobacterium avium/isolamento & purificação , Células Th1/citologia , Redução de PesoRESUMO
To investigate the respective contributions of TLR versus IL-1R mediated signals in MyD88 dependent control of Mycobacterium tuberculosis, we compared the outcome of M. tuberculosis infection in MyD88, TRIF/MyD88, IL-1R1, and IL-1beta-deficient mice. All four strains displayed acute mortality with highly increased pulmonary bacterial burden suggesting a major role for IL-1beta signaling in determining the MyD88 dependent phenotype. Unexpectedly, the infected MyD88 and TRIF/MyD88-deficient mice, rather than being defective in IL-1beta expression, displayed increased cytokine levels relative to wild-type animals. Similarly, infected mice deficient in caspase-1 and ASC, which have critical functions in inflammasome-mediated IL-1beta maturation, showed unimpaired IL-1beta production and importantly, were considerably less susceptible to infection than IL-1beta deficient mice. Together our findings reveal a major role for IL-1beta in host resistance to M. tuberculosis and indicate that during this infection the cytokine can be generated by a mechanism that does not require TLR signaling or caspase-1.
Assuntos
Caspase 1/imunologia , Interleucina-1beta/biossíntese , Transdução de Sinais/imunologia , Receptores Toll-Like/imunologia , Tuberculose Pulmonar/imunologia , Proteínas Adaptadoras de Transporte Vesicular , Animais , Western Blotting , Ensaio de Imunoadsorção Enzimática , Feminino , Interleucina-1beta/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Mycobacterium tuberculosis/imunologia , Fator 88 de Diferenciação Mieloide/imunologia , Receptores de Interleucina-1/imunologia , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Mycobacterium tuberculosis (Mtb) infection induces pulmonary expression of the heme-degrading enzyme heme oxygenase-1 (HO-1). We have previously shown that pharmacological inhibition of HO-1 activity in experimental tuberculosis results in decreased bacterial loads and unexpectedly that this outcome depends on the presence of T lymphocytes. Here, we extend these findings by demonstrating that IFNγ production by T lymphocytes and NOS2 expression underlie this T-cell requirement and that HO-1 inhibition potentiates IFNγ-induced NOS2-dependent control of Mtb by macrophages in vitro. Among the products of heme degradation by HO-1 (biliverdin, carbon monoxide, and iron), only iron supplementation reverted the HO-1 inhibition-induced enhancement of bacterial control and this reversal was associated with decreased NOS2 expression and NO production. In addition, we found that HO-1 inhibition results in decreased labile iron levels in Mtb-infected macrophages in vitro and diminished iron accumulation in Mtb-infected lungs in vivo. Together these results suggest that the T-lymphocyte dependence of the therapeutic outcome of HO-1 inhibition on Mtb infection reflects the role of the enzyme in generating iron that suppresses T-cell-mediated IFNγ/NOS2-dependent bacterial control. In broader terms, our findings highlight the importance of the crosstalk between iron metabolism and adaptive immunity in determining the outcome of infection.
Assuntos
Heme Oxigenase-1/antagonistas & inibidores , Interações Hospedeiro-Patógeno , Interferon gama/metabolismo , Mycobacterium tuberculosis , Óxido Nítrico Sintase Tipo II/metabolismo , Tuberculose/metabolismo , Tuberculose/microbiologia , Animais , Carga Bacteriana , Interações Hospedeiro-Patógeno/imunologia , Ferro/metabolismo , Macrófagos/imunologia , Macrófagos/metabolismo , Camundongos , Modelos Biológicos , Mycobacterium tuberculosis/imunologia , Óxido Nítrico/metabolismo , Linfócitos T/imunologia , Linfócitos T/metabolismo , Tuberculose/imunologiaRESUMO
TLRs are thought to play a critical role in self/non-self discrimination by sensing microbial infections and initiating both innate and adaptive immunity. In this study, we demonstrate that in the absence of TLR11, a major TLR involved in recognition of Toxoplasma gondii, infection with this protozoan parasite induces an abnormal immunopathological response consisting of pancreatic tissue destruction, fat necrosis, and systemic elevations in inflammatory reactants. We further show that this immunopathology is the result of non-TLR dependent activation of IFN-gamma secretion by NK cells in response to the infection. These findings reveal that in addition to triggering host resistance to infection, TLR recognition can be critical for the prevention of pathogen-induced immune destruction of self tissue.
Assuntos
Receptores Toll-Like/metabolismo , Toxoplasma/imunologia , Toxoplasmose/patologia , Toxoplasmose/prevenção & controle , Doença Aguda , Animais , Necrose Gordurosa/genética , Necrose Gordurosa/imunologia , Necrose Gordurosa/patologia , Interferon gama/metabolismo , Células Matadoras Naturais/imunologia , Células Matadoras Naturais/metabolismo , Células Matadoras Naturais/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Mutantes , Pancreatite/genética , Pancreatite/imunologia , Pancreatite/patologia , Receptores Toll-Like/deficiência , Receptores Toll-Like/genética , Toxoplasma/metabolismo , Toxoplasmose/genética , Toxoplasmose/imunologiaRESUMO
Critical events of HIV-1 pathogenesis occur in lymphoid tissues where HIV-1 is typically accompanied by infections with other pathogens (HIV co-pathogens). Co-pathogens greatly affect the clinical course of the disease and the transmission of HIV. The apicomplexan parasite Toxoplasma gondii is a common HIV co-pathogen associated with AIDS development. Here, we examined the interaction of T. gondii and HIV in coinfected human lymphoid tissue ex vivo. Both pathogens readily replicate in ex vivo infected blocks of human tonsillar tissue. Surprisingly, we found that live T. gondii preferentially inhibits R5 HIV-1 replication in coinfected tissues. This effect is reproduced by treatment of the tissue blocks with recombinant C-18, a T. gondii-encoded cyclophilin that binds to CCR5. These ex vivo findings raise the possibility that, in addition to being a co-factor in HIV disease, T. gondii may influence the outcome of viral infection by preferentially suppressing R5 variants.
Assuntos
HIV-1/fisiologia , Tonsila Palatina , Receptores CCR5/metabolismo , Toxoplasma/patogenicidade , Replicação Viral/efeitos dos fármacos , Animais , Ciclofilinas/genética , Ciclofilinas/metabolismo , Ciclofilinas/farmacologia , Infecções por HIV/complicações , Infecções por HIV/virologia , HIV-1/metabolismo , HIV-1/patogenicidade , Humanos , Tecido Linfoide/parasitologia , Tecido Linfoide/virologia , Tonsila Palatina/parasitologia , Tonsila Palatina/virologia , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Proteínas de Protozoários/farmacologia , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/farmacologia , Toxoplasma/classificação , Toxoplasma/metabolismo , Toxoplasma/fisiologia , Toxoplasmose/complicações , Toxoplasmose/virologiaRESUMO
Although Toll-like Receptors (TLRs) play a major function in innate recognition of pathogens, their role in antigen processing and presentation in vivo is poorly understood. Here we establish that Toxoplasma gondii profilin, a TLR11 ligand present in the parasite, is an immunodominant antigen in the CD4(+) T cell response to the pathogen. The immunogenicity of profilin was entirely dependent on both TLR11 recognition and signaling through the adaptor myeloid differentiation factor 88 (MyD88). Selective responsiveness to this parasite protein was regulated at the level of antigen presentation by dendritic cells (DC) and required both TLR signaling and major histocompatibility complex (MHC) class II recognition acting in cis. These findings support a major influence of TLR recognition in antigen presentation by DC in vivo and establish a mechanism by which TLR ligand association regulates the immunogenicity of microbial antigens.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Antígenos de Protozoários/imunologia , Linfócitos T CD4-Positivos/imunologia , Profilinas/imunologia , Receptores Toll-Like/metabolismo , Toxoplasma/imunologia , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Apresentação de Antígeno , Antígenos CD8/análise , Células Dendríticas/imunologia , Antígenos de Histocompatibilidade Classe II/metabolismo , Ligantes , Camundongos , Camundongos Mutantes , Fator 88 de Diferenciação Mieloide , Transdução de Sinais , Subpopulações de Linfócitos T/imunologia , Receptores Toll-Like/genéticaRESUMO
Although it is known that IFN-gamma-secreting T cells are critical for control of Mycobacterium tuberculosis infection, the contribution of IFN-gamma produced by NK cells to host resistance to the pathogen is less well understood. By using T cell-deficient RAG(-/-) mice, we showed that M. tuberculosis stimulates NK cell-dependent IFN-gamma production in naive splenic cultures and in lungs of infected animals. More importantly, common cytokine receptor gamma-chain(-/-)RAG(-/-) animals deficient in NK cells, p40(-/-)RAG(-/-), or anti-IFN-gamma mAb-treated RAG(-/-) mice displayed significantly increased susceptibility to M. tuberculosis infection compared with untreated NK-sufficient RAG(-/-) controls. Studies comparing IL-12 p40- and p35-deficient RAG(-/-) mice indicated that IL-12 plays a more critical role in the induction of IFN-gamma-mediated antimycobacterial effector functions than IL-23 or other p40-containing IL-12 family members. The increased susceptibility of IL-12-deficient or anti-IFN-gamma mAb-treated RAG(-/-) mice was associated not only with elevated bacterial loads, but also with the development of granulocyte-enriched foci in lungs. This tissue response correlated with increased expression of the granulocyte chemotactic chemokines KC and MIP-2 in NK as well as other leukocyte populations. Interestingly, depletion of granulocytes further increased bacterial burdens and exacerbated pulmonary pathology in these animals, revealing a compensatory function for neutrophils in the absence of IFN-gamma. The above observations indicate that NK cell-derived IFN-gamma differentially regulates T-independent resistance and granulocyte function in M. tuberculosis infection and suggest that this response could serve as an important barrier in AIDS patients or other individuals with compromised CD4+ T cell function.
Assuntos
Interferon gama/fisiologia , Células Matadoras Naturais/imunologia , Linfopenia/imunologia , Mycobacterium tuberculosis/imunologia , Neutrófilos/imunologia , Tuberculose Pulmonar/imunologia , Animais , Granulócitos/imunologia , Granulócitos/patologia , Proteínas de Homeodomínio/genética , Imunidade Inata/genética , Interferon gama/biossíntese , Interleucina-12/fisiologia , Interleucina-23/fisiologia , Células Matadoras Naturais/metabolismo , Pulmão/imunologia , Pulmão/metabolismo , Pulmão/patologia , Linfopenia/mortalidade , Linfopenia/patologia , Ativação de Macrófagos/genética , Ativação de Macrófagos/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neutrófilos/microbiologia , Tuberculose Pulmonar/mortalidade , Tuberculose Pulmonar/patologiaRESUMO
The mechanisms that prevent reactivation of latent Mycobacterium tuberculosis infection in asymptomatic individuals are poorly understood. Although IL-12 is critical for the induction of IFN-gamma-dependent host control of M. tuberculosis, the requirement for the cytokine in the maintenance of host resistance and pulmonary Th1 effector function has not yet been formally examined. In this study, we reconstituted IL-12p40-deficient mice with IL-12 during the first 4 wk of infection and then assessed the effects of cytokine withdrawal. Although IL-12 administration initially resulted in restricted mycobacterial growth and prolonged survival, the reconstituted animals eventually succumbed to infection. This breakdown in bacterial control was accompanied by a marked reduction in the numbers of IFN-gamma-producing CD4(+) T cells in lungs. Moreover, whereas CD4(+) T cells isolated from chronically infected wild-type mice expanded and transferred long-term protection to M. tuberculosis-challenged RAG(-/-) mice, they failed to do so in IL-12p40-deficient RAG(-/-) recipients and were clearly reduced in frequency within pulmonary granulomas in the latter animals. These studies establish that continuous IL-12 production is necessary for maintenance of the pulmonary Th1 cells required for host control of persistent M. tuberculosis infection and suggest that breakdown of this mechanism could be a contributing factor in reactivated disease.
Assuntos
Interleucina-12/biossíntese , Interleucina-12/imunologia , Subunidades Proteicas/biossíntese , Subunidades Proteicas/imunologia , Células Th1/imunologia , Tuberculose/imunologia , Transferência Adotiva , Animais , Contagem de Linfócito CD4 , Linfócitos T CD4-Positivos/metabolismo , Doença Crônica , Interferon gama/biossíntese , Subunidade p40 da Interleucina-12 , Pulmão/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Mycobacterium tuberculosis/imunologia , Recidiva , Células Th1/citologiaRESUMO
Mammalian Toll-like receptors (TLRs) play an important role in the innate recognition of pathogens by dendritic cells (DCs). Although TLRs are clearly involved in the detection of bacteria and viruses, relatively little is known about their function in the innate response to eukaryotic microorganisms. Here we identify a profilin-like molecule from the protozoan parasite Toxoplasma gondii that generates a potent interleukin-12 (IL-12) response in murine DCs that is dependent on myeloid differentiation factor 88. T. gondii profilin activates DCs through TLR11 and is the first chemically defined ligand for this TLR. Moreover, TLR11 is required in vivo for parasite-induced IL-12 production and optimal resistance to infection, thereby establishing a role for the receptor in host recognition of protozoan pathogens.
Assuntos
Proteínas Contráteis/imunologia , Células Dendríticas/imunologia , Proteínas dos Microfilamentos/imunologia , Proteínas de Protozoários/imunologia , Receptores de Superfície Celular/metabolismo , Toxoplasma/imunologia , Toxoplasmose Animal/imunologia , Proteínas Adaptadoras de Transdução de Sinal , Motivos de Aminoácidos , Sequência de Aminoácidos , Animais , Antígenos de Diferenciação/genética , Antígenos de Diferenciação/metabolismo , Proteínas Contráteis/química , Proteínas Contráteis/isolamento & purificação , Proteínas Contráteis/metabolismo , Genes de Protozoários , Imunidade Inata , Interleucina-12/biossíntese , Interleucina-12/sangue , Ligantes , Glicoproteínas de Membrana/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Proteínas dos Microfilamentos/química , Proteínas dos Microfilamentos/isolamento & purificação , Proteínas dos Microfilamentos/metabolismo , Dados de Sequência Molecular , Fator 88 de Diferenciação Mieloide , NF-kappa B/metabolismo , Profilinas , Proteínas de Protozoários/química , Proteínas de Protozoários/isolamento & purificação , Proteínas de Protozoários/metabolismo , Receptores Imunológicos/genética , Receptores Imunológicos/metabolismo , Proteínas Recombinantes/imunologia , Transdução de Sinais , Receptores Toll-Like , Toxoplasma/genética , TransfecçãoRESUMO
IL-12-deficient mice exposed to nonlethal infections with intracellular pathogens or repeatedly immunized with a pathogen extract developed lowered but nevertheless substantial numbers of IFN-gamma(+) CD4(+) T cells compared to those observed in wild-type animals. Moreover, the CD4(+) responses in these knockout animals failed to default to a Th2 pattern. The protective efficacy of the Th1 cells developing in an IL-12-deficient setting was found to be limited by IL-10 since mice doubly deficient in IL-10 and IL-12 survived, while animals deficient in IL-12 alone succumbed to pathogen challenge. In contrast to IL-12 knockout mice, MyD88-deficient animals exposed to a Th1 microbial stimulus developed a pure Th2 response, arguing that this signaling element plays a more critical function than IL-12 in determining pathogen-induced CD4 polarization.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Imunidade Inata , Interleucina-10/imunologia , Interleucina-12/imunologia , Células Th1/imunologia , Células Th2/imunologia , Proteínas Adaptadoras de Transdução de Sinal , Animais , Antígenos de Diferenciação/genética , Antígenos de Diferenciação/imunologia , Interleucina-10/genética , Interleucina-12/genética , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fator 88 de Diferenciação Mieloide , Receptores Imunológicos/genética , Receptores Imunológicos/imunologia , Transdução de Sinais/imunologiaRESUMO
Mycobacterial infection has been implicated as a possible factor in AIDS progression in populations where HIV-1 and Mycobacterium tuberculosis are coendemic. In support of this concept, we have previously shown that HIV-1-transgenic (Tg) mice infected with mycobacteria display enhanced viral gene and protein expression. In this study, we demonstrate that the induction of HIV-1 observed in this model is dependent on Toll-like receptor 2 (TLR2), a pattern recognition receptor known to be involved in mycobacteria-host interaction. Spleen cells from HIV-1-Tg mice deficient in TLR2 (Tg/TLR2(-/-)) were found to be completely defective in p24 production induced in response to live M. tuberculosis or Mycobacterium avium as well as certain mycobacterial products. Importantly, following in vivo mycobacterial infection, Tg/TLR2(-/-) mice failed to display the enhanced HIV-1 gag/env mRNA and p24 protein synthesis exhibited by wild-type Tg animals. Together, these results argue that TLR2 plays a crucial role in the activation of HIV-1 expression by mycobacterial coinfections.