RESUMO
In response to the 2022 outbreak of mpox driven by unprecedented human-to-human monkeypox virus (MPXV) transmission, we designed BNT166, aiming to create a highly immunogenic, safe, accessible, and scalable next-generation vaccine against MPXV and related orthopoxviruses. To address the multiple viral forms and increase the breadth of immune response, two candidate multivalent mRNA vaccines were evaluated pre-clinically: a quadrivalent vaccine (BNT166a; encoding the MPXV antigens A35, B6, M1, H3) and a trivalent vaccine (BNT166c; without H3). Both candidates induced robust T cell responses and IgG antibodies in mice, including neutralizing antibodies to both MPXV and vaccinia virus. In challenge studies, BNT166a and BNT166c provided complete protection from vaccinia, clade I, and clade IIb MPXV. Furthermore, immunization with BNT166a was 100% effective at preventing death and at suppressing lesions in a lethal clade I MPXV challenge in cynomolgus macaques. These findings support the clinical evaluation of BNT166, now underway (NCT05988203).
Assuntos
Monkeypox virus , Mpox , Vacina Antivariólica , Animais , Humanos , Camundongos , Macaca fascicularis , Monkeypox virus/genética , Mpox/imunologia , Mpox/prevenção & controle , Vacinas Combinadas , Vaccinia virus/genéticaRESUMO
Systemic infections with Gram-negative bacteria are characterized by high mortality rates due to the "sepsis syndrome," a widespread and uncontrolled inflammatory response. Though it is well recognized that the immune response during Gram-negative bacterial infection is initiated after the recognition of endotoxin by Toll-like receptor 4, the molecular mechanisms underlying the detrimental inflammatory response during Gram-negative bacteremia remain poorly defined. Here, we identify a TRIF pathway that licenses NLRP3 inflammasome activation by all Gram-negative bacteria. By engaging TRIF, Gram-negative bacteria activate caspase-11. TRIF activates caspase-11 via type I IFN signaling, an event that is both necessary and sufficient for caspase-11 induction and autoactivation. Caspase-11 subsequently synergizes with the assembled NLRP3 inflammasome to regulate caspase-1 activation and leads to caspase-1-independent cell death. These events occur specifically during infection with Gram-negative, but not Gram-positive, bacteria. The identification of TRIF as a regulator of caspase-11 underscores the importance of TLRs as master regulators of inflammasomes during Gram-negative bacterial infection.
Assuntos
Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Caspases/metabolismo , Citrobacter rodentium/metabolismo , Escherichia coli Êntero-Hemorrágica/metabolismo , Inflamassomos/metabolismo , Interferons/metabolismo , Animais , Proteínas de Transporte/metabolismo , Caspases Iniciadoras , Citrobacter rodentium/imunologia , Escherichia coli Êntero-Hemorrágica/imunologia , Bactérias Gram-Negativas/imunologia , Bactérias Gram-Negativas/metabolismo , Bactérias Gram-Positivas/imunologia , Bactérias Gram-Positivas/metabolismo , Camundongos , Proteína 3 que Contém Domínio de Pirina da Família NLR , Transdução de SinaisRESUMO
Phagocytosis is a fundamental cellular process that is pivotal for immunity as it coordinates microbial killing, innate immune activation and antigen presentation. An essential step in this process is phagosome acidification, which regulates many functions of these organelles that allow phagosomes to participate in processes that are essential to both innate and adaptive immunity. Here we report that acidification of phagosomes containing Gram-positive bacteria is regulated by the NLRP3 inflammasome and caspase-1. Active caspase-1 accumulates on phagosomes and acts locally to control the pH by modulating buffering by the NADPH oxidase NOX2. These data provide insight into a mechanism by which innate immune signals can modify cellular defenses and establish a new function for the NLRP3 inflammasome and caspase-1 in host defense.
Assuntos
Proteínas de Transporte/imunologia , Caspase 1/imunologia , Inflamassomos/imunologia , Glicoproteínas de Membrana/imunologia , NADPH Oxidases/imunologia , Fagossomos/imunologia , Animais , Proteínas de Transporte/metabolismo , Caspase 1/metabolismo , Células Cultivadas , Ativação Enzimática/imunologia , Citometria de Fluxo , Células HEK293 , Interações Hospedeiro-Patógeno/imunologia , Humanos , Concentração de Íons de Hidrogênio , Immunoblotting , Inflamassomos/metabolismo , Macrófagos/imunologia , Macrófagos/metabolismo , Macrófagos/microbiologia , Glicoproteínas de Membrana/metabolismo , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Microscopia Confocal , Microscopia Eletrônica , NADPH Oxidase 2 , NADPH Oxidases/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR , Fagocitose/imunologia , Fagossomos/metabolismo , Fagossomos/microbiologia , Fagossomos/ultraestrutura , Espécies Reativas de Oxigênio/imunologia , Espécies Reativas de Oxigênio/metabolismo , Staphylococcus aureus/imunologia , Staphylococcus aureus/fisiologiaRESUMO
Particulate ligands, including cholesterol crystals and amyloid fibrils, induce production of interleukin 1ß (IL-1ß) dependent on the cytoplasmic sensor NLRP3 in atherosclerosis, Alzheimer's disease and diabetes. Soluble endogenous ligands, including oxidized low-density lipoprotein (LDL), amyloid-ß and amylin peptides, accumulate in such diseases. Here we identify an endocytic pathway mediated by the pattern-recognition receptor CD36 that coordinated the intracellular conversion of those soluble ligands into crystals or fibrils, which resulted in lysosomal disruption and activation of the NLRP3 inflammasome. Consequently, macrophages that lacked CD36 failed to elicit IL-1ß production in response to those ligands, and targeting CD36 in atherosclerotic mice resulted in lower serum concentrations of IL-1ß and accumulation of cholesterol crystals in plaques. Collectively, our findings highlight the importance of CD36 in the accrual and nucleation of NLRP3 ligands from within the macrophage and position CD36 as a central regulator of inflammasome activation in sterile inflammation.
Assuntos
Doença de Alzheimer/imunologia , Aterosclerose/imunologia , Antígenos CD36/imunologia , Proteínas de Transporte/imunologia , Diabetes Mellitus Tipo 2/imunologia , Inflamação/imunologia , Animais , Antígenos CD36/genética , Proteínas de Transporte/genética , Inflamassomos/imunologia , Interleucina-1beta/imunologia , Lipoproteínas LDL/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microscopia Confocal , Microscopia de Fluorescência , Proteína 3 que Contém Domínio de Pirina da Família NLR , RNA/química , RNA/genética , Reação em Cadeia da Polimerase em Tempo RealRESUMO
Atherosclerotic plaque formation is fueled by the persistence of lipid-laden macrophages in the artery wall. The mechanisms by which these cells become trapped, thereby establishing chronic inflammation, remain unknown. Here we found that netrin-1, a neuroimmune guidance cue, was secreted by macrophages in human and mouse atheroma, where it inactivated the migration of macrophages toward chemokines linked to their egress from plaques. Acting via its receptor, UNC5b, netrin-1 inhibited the migration of macrophages directed by the chemokines CCL2 and CCL19, activation of the actin-remodeling GTPase Rac1 and actin polymerization. Targeted deletion of netrin-1 in macrophages resulted in much less atherosclerosis in mice deficient in the receptor for low-density lipoprotein and promoted the emigration of macrophages from plaques. Thus, netrin-1 promoted atherosclerosis by retaining macrophages in the artery wall. Our results establish a causative role for negative regulators of leukocyte migration in chronic inflammation.
Assuntos
Aterosclerose/imunologia , Movimento Celular/imunologia , Macrófagos/imunologia , Fatores de Crescimento Neural/metabolismo , Placa Aterosclerótica/imunologia , Proteínas Supressoras de Tumor/metabolismo , Actinas/metabolismo , Animais , Células Cultivadas , Quimiocina CCL19/metabolismo , Quimiocina CCL2/metabolismo , Quimera/metabolismo , Deleção de Genes , Humanos , Camundongos , Fatores de Crescimento Neural/genética , Receptores de Netrina , Netrina-1 , Neuropeptídeos/metabolismo , Polimerização , Receptores de Superfície Celular/metabolismo , Proteínas Supressoras de Tumor/genética , Proteínas rac de Ligação ao GTP/metabolismo , Proteínas rac1 de Ligação ao GTP/metabolismoRESUMO
Animal host defense against infection requires the expression of defense genes at the right place and the right time. Understanding such tight control of host defense requires the elucidation of the transcription factors involved. By using an unbiased approach in the model Caenorhabditis elegans, we discovered that HLH-30 (known as TFEB in mammals) is a key transcription factor for host defense. HLH-30 was activated shortly after Staphylococcus aureus infection, and drove the expression of close to 80% of the host response, including antimicrobial and autophagy genes that were essential for host tolerance of infection. TFEB was also rapidly activated in murine macrophages upon S. aureus infection and was required for proper transcriptional induction of several proinflammatory cytokines and chemokines. Thus, our data suggest that TFEB is a previously unappreciated, evolutionarily ancient transcription factor in the host response to infection.
Assuntos
Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/imunologia , Fatores de Transcrição Hélice-Alça-Hélice Básicos/imunologia , Proteínas de Caenorhabditis elegans/imunologia , Caenorhabditis elegans/imunologia , Caenorhabditis elegans/microbiologia , Infecções Estafilocócicas/imunologia , Animais , Autofagia/genética , Autofagia/imunologia , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Proteínas de Caenorhabditis elegans/genética , Enterococcus faecalis/imunologia , Imunidade Inata , Macrófagos/imunologia , Camundongos , Infecções por Pseudomonas/imunologia , Pseudomonas aeruginosa/imunologia , Interferência de RNA , RNA Interferente Pequeno , Infecções por Salmonella/imunologia , Salmonella enterica/imunologia , Transdução de Sinais/imunologia , Staphylococcus aureus/imunologia , Ativação Transcricional/genética , Ativação Transcricional/imunologiaRESUMO
In atherosclerosis and Alzheimer's disease, deposition of the altered self components oxidized low-density lipoprotein (LDL) and amyloid-beta triggers a protracted sterile inflammatory response. Although chronic stimulation of the innate immune system is believed to underlie the pathology of these diseases, the molecular mechanisms of activation remain unclear. Here we show that oxidized LDL and amyloid-beta trigger inflammatory signaling through a heterodimer of Toll-like receptors 4 and 6. Assembly of this newly identified heterodimer is regulated by signals from the scavenger receptor CD36, a common receptor for these disparate ligands. Our results identify CD36-TLR4-TLR6 activation as a common molecular mechanism by which atherogenic lipids and amyloid-beta stimulate sterile inflammation and suggest a new model of TLR heterodimerization triggered by coreceptor signaling events.
Assuntos
Antígenos CD36/imunologia , Inflamação/imunologia , Transdução de Sinais/imunologia , Receptor 4 Toll-Like/imunologia , Receptor 6 Toll-Like/imunologia , Peptídeos beta-Amiloides/imunologia , Animais , Aterosclerose/imunologia , Aterosclerose/metabolismo , Western Blotting , Antígenos CD36/metabolismo , Linhagem Celular , Quimiocinas/biossíntese , Quimiocinas/imunologia , Expressão Gênica , Humanos , Imunoprecipitação , Inflamação/metabolismo , Lipoproteínas LDL/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microglia/imunologia , Microglia/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Receptor 4 Toll-Like/metabolismo , Receptor 6 Toll-Like/metabolismoRESUMO
Systemic lupus erythematosus (SLE) is defined by loss of B cell tolerance, resulting in production of autoantibodies against nucleic acids and other cellular Ags. Aberrant activation of TLRs by self-derived RNA and DNA is strongly associated with SLE in patients and in mouse models, but the mechanism by which TLR signaling to self-ligands is regulated remains poorly understood. In this study, we show that αv integrin plays a critical role in regulating B cell TLR signaling to self-antigens in mice. We show that deletion of αv from B cells accelerates autoantibody production and autoimmune kidney disease in the Tlr7.1 transgenic mouse model of SLE. Increased autoimmunity was associated with specific expansion of transitional B cells, extrafollicular IgG2c-producing plasma cells, and activation of CD4 and CD8 T cells. Our data show that αv-mediated regulation of TLR signaling in B cells is critical for preventing autoimmunity and indicate that loss of αv promotes escape from tolerance. Thus, we identify a new regulatory pathway in autoimmunity and elucidate upstream signals that adjust B cell activation to prevent development of autoimmunity in a mouse model.
Assuntos
Linfócitos B/fisiologia , Integrina alfaV/metabolismo , Lúpus Eritematoso Sistêmico/imunologia , Glicoproteínas de Membrana/metabolismo , Receptor 7 Toll-Like/metabolismo , Animais , Autoanticorpos/metabolismo , Autoimunidade , Células Cultivadas , Modelos Animais de Doenças , Humanos , Imunoglobulina G/metabolismo , Imunomodulação , Integrina alfaV/genética , Ativação Linfocitária , Glicoproteínas de Membrana/genética , Camundongos , Camundongos Transgênicos , Receptor 7 Toll-Like/genéticaRESUMO
In this issue of Immunity, Irving et al. (2012) show that protein kinase R (PKR) regulates the cytoskeleton via an interaction with gelsolin. This alternative role for PKR prevents penetration of virions into the cell.
RESUMO
Although infections with virulent pathogens often induce a strong inflammatory reaction, what drives the increased immune response to pathogens compared to nonpathogenic microbes is poorly understood. One possibility is that the immune system senses the level of threat from a microorganism and augments the response accordingly. Here, focusing on cytotoxic necrotizing factor 1 (CNF1), an Escherichia coli-derived effector molecule, we showed the host indirectly sensed the pathogen by monitoring for the effector that modified RhoGTPases. CNF1 modified Rac2, which then interacted with the innate immune adaptors IMD and Rip1-Rip2 in flies and mammalian cells, respectively, to drive an immune response. This response was protective and increased the ability of the host to restrict pathogen growth, thus defining a mechanism of effector-triggered immunity that contributes to how metazoans defend against microbes with pathogenic potential.
Assuntos
Transdução de Sinais , Proteínas rac de Ligação ao GTP/imunologia , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Ativação Enzimática , Células HEK293 , Humanos , Proteína Serina-Treonina Quinases de Interação com Receptores/metabolismo , Proteínas rac de Ligação ao GTP/metabolismo , Proteína RAC2 de Ligação ao GTPRESUMO
The road to a more efficacious vaccine that could be a truly transformative tool for decreasing tuberculosis morbidity and mortality, along with Mycobacterium tuberculosis transmission, is quite daunting. Despite this, there are reasons for optimism. Abetted by better conceptual clarity, clear acknowledgment of the degree of our current immunobiological ignorance, the availability of powerful new tools for dissecting the immunopathogenesis of human tuberculosis, the generation of more creative diversity in tuberculosis vaccine concepts, the development of better fit-for-purpose animal models, and the potential of more pragmatic approaches to the clinical testing of vaccine candidates, the field has promise for delivering novel tools for dealing with this worldwide scourge of poverty.
Assuntos
Mycobacterium tuberculosis/imunologia , Vacinas contra a Tuberculose/imunologia , Tuberculose/imunologia , Tuberculose/prevenção & controle , Animais , Modelos Animais de Doenças , Humanos , Vacinas contra a Tuberculose/administração & dosagem , Vacinas contra a Tuberculose/efeitos adversos , Vacinas de Subunidades AntigênicasRESUMO
Activation of TGF-ß by dendritic cells (DCs) expressing αvß8 integrin is essential for the generation of intestinal regulatory T cells (Tregs) that in turn promote tolerance to intestinal Ags. We have recently shown that αvß8 integrin is preferentially expressed by CD103(+) DCs and confers their ability to activate TGF-ß and generate Tregs. However, how these DCs become specialized for this vital function is unknown. In this study, we show that ß8 expression is controlled by a combination of factors that include DC lineage and signals derived from the tissue microenvironment and microbiota. Specifically, our data demonstrate that TGF-ß itself, along with retinoic acid and TLR signaling, drives expression of αvß8 in DCs. However, these signals only result in high levels of ß8 expression in cells of the cDC1 lineage, CD8α(+), or CD103(+)CD11b(-) DCs, and this is associated with epigenetic changes in the Itgb8 locus. Together, these data provide a key illustrative example of how microenvironmental factors and cell lineage drive the generation of regulatory αvß8-expressing DCs specialized for activation of TGF-ß to facilitate Treg generation.
Assuntos
Linhagem da Célula , Microambiente Celular , Células Dendríticas/imunologia , Cadeias beta de Integrinas/metabolismo , Intestinos/citologia , Fator de Crescimento Transformador beta/metabolismo , Animais , Antígenos CD/genética , Antígenos CD/imunologia , Diferenciação Celular , Células Dendríticas/fisiologia , Cadeias alfa de Integrinas/genética , Cadeias alfa de Integrinas/imunologia , Cadeias beta de Integrinas/genética , Cadeias beta de Integrinas/imunologia , Intestinos/imunologia , Camundongos , Linfócitos T Reguladores/fisiologia , Receptores Toll-Like/imunologia , Receptores Toll-Like/metabolismo , Fator de Crescimento Transformador beta/genética , Fator de Crescimento Transformador beta/imunologia , Tretinoína/metabolismoRESUMO
The detection of the activities of pathogen-encoded virulence factors by the innate immune system has emerged as a new paradigm of pathogen recognition. Much remains to be determined with regard to the molecular and cellular components contributing to this defense mechanism in mammals and importance during infection. Here, we reveal the central role of the IL-1ß signaling axis and Gr1+ cells in controlling the Escherichia coli burden in the blood in response to the sensing of the Rho GTPase-activating toxin CNF1. Consistently, this innate immune response is abrogated in caspase-1/11-impaired mice or following the treatment of infected mice with an IL-1ß antagonist. In vitro experiments further revealed the synergistic effects of CNF1 and LPS in promoting the maturation/secretion of IL-1ß and establishing the roles of Rac, ASC and caspase-1 in this pathway. Furthermore, we found that the α-hemolysin toxin inhibits IL-1ß secretion without affecting the recruitment of Gr1+ cells. Here, we report the first example of anti-virulence-triggered immunity counteracted by a pore-forming toxin during bacteremia.
Assuntos
Toxinas Bacterianas/imunologia , Infecções por Escherichia coli/imunologia , Proteínas de Escherichia coli/imunologia , Proteínas Hemolisinas/imunologia , Imunidade Inata/imunologia , Transdução de Sinais/imunologia , Animais , Bacteriemia/imunologia , Modelos Animais de Doenças , Escherichia coli/imunologia , Escherichia coli/patogenicidade , Feminino , Interações Hospedeiro-Patógeno/imunologia , Interleucina-1beta/biossíntese , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Knockout , Virulência , Fatores de Virulência/imunologiaRESUMO
The Gram-negative bacteria Yersinia pestis, causative agent of plague, is extremely virulent. One mechanism contributing to Y. pestis virulence is the presence of a type-three secretion system, which injects effector proteins, Yops, directly into immune cells of the infected host. One of these Yop proteins, YopJ, is proapoptotic and inhibits mammalian NF-κB and MAP-kinase signal transduction pathways. Although the molecular mechanism remained elusive for some time, recent work has shown that YopJ acts as a serine/threonine acetyl-transferase targeting MAP2 kinases. Using Drosophila as a model system, we find that YopJ inhibits one innate immune NF-κB signaling pathway (IMD) but not the other (Toll). In fact, we show YopJ mediated serine/threonine acetylation and inhibition of dTAK1, the critical MAP3 kinase in the IMD pathway. Acetylation of critical serine/threonine residues in the activation loop of Drosophila TAK1 blocks phosphorylation of the protein and subsequent kinase activation. In addition, studies in mammalian cells show similar modification and inhibition of hTAK1. These data present evidence that TAK1 is a target for YopJ-mediated inhibition.
Assuntos
Proteínas de Bactérias/metabolismo , Imunidade Inata , MAP Quinase Quinase Quinases/metabolismo , Sistema de Sinalização das MAP Quinases , Serina O-Acetiltransferase/metabolismo , Yersinia pestis/enzimologia , Acetilação , Animais , Proteínas de Bactérias/imunologia , Drosophila melanogaster , Células HEK293 , Humanos , MAP Quinase Quinase Quinases/imunologia , NF-kappa B/imunologia , NF-kappa B/metabolismo , Peste/imunologia , Peste/metabolismo , Serina O-Acetiltransferase/imunologia , Yersinia pestis/imunologia , Yersinia pestis/patogenicidadeRESUMO
Autophagy has been postulated to play role in mammalian host defense against fungal pathogens, although the molecular details remain unclear. Here, we show that primary macrophages deficient in the autophagic factor LC3 demonstrate diminished fungicidal activity but increased cytokine production in response to Candida albicans stimulation. LC3 recruitment to fungal phagosomes requires activation of the fungal pattern receptor dectin-1. LC3 recruitment to the phagosome also requires Syk signaling but is independent of all activity by Toll-like receptors and does not require the presence of the adaptor protein Card9. We further demonstrate that reactive oxygen species generation by NADPH oxidase is required for LC3 recruitment to the fungal phagosome. These observations directly link LC3 to the inflammatory pathway against C. albicans in macrophages.
Assuntos
Fungos/imunologia , Lectinas Tipo C/genética , Lectinas Tipo C/metabolismo , Macrófagos/metabolismo , Macrófagos/microbiologia , Proteínas Associadas aos Microtúbulos/metabolismo , Fagossomos/metabolismo , Animais , Proteínas Adaptadoras de Sinalização CARD/metabolismo , Candida albicans/imunologia , Linhagem Celular , Interleucina-1beta/biossíntese , Interleucina-6/biossíntese , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Macrófagos/imunologia , Camundongos , Proteínas Associadas aos Microtúbulos/genética , Modelos Biológicos , NADPH Oxidases/metabolismo , Fagossomos/imunologia , Fagossomos/microbiologia , Fosforilação , Proteínas Tirosina Quinases/metabolismo , Proteoglicanas , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais , Quinase Syk , Fator de Necrose Tumoral alfa/biossíntese , beta-Glucanas/metabolismoRESUMO
Elimination of fungal pathogens by phagocytes requires phagosome maturation, a process that involves the recruitment and fusion of intracellular proteins. The role of Dectin-1, a ß-1,3-glucan receptor, critical for fungal recognition and triggering of Th17 responses, to phagosomal maturation has not been defined. We show that GFP-Dectin-1 translocates to the fungal phagosome, but its signal decays after 2 h. Inhibition of acidification results in retention of GFP-Dectin-1 to phagosome membranes highlighting the requirement for an acidic pH. Following ß-1,3-glucan recognition, GFP-Dectin-1 undergoes tyrosine phosphorylation by Src kinases with subsequent Syk activation. Our results demonstrate that Syk is activated independently of intraphagosomal pH. Inhibition of Src or Syk results in prolonged retention of GFP-Dectin-1 to the phagosome signifying a link between Syk and intraphagosomal pH. ß-1,3-glucan phagosomes expressing a signaling incompetent Dectin-1 failed to mature as demonstrated by prolonged Dectin-1 retention, presence of Rab5B, failure to acquire LAMP-1 and inability to acidify. Phagosomes containing Candida albicans also require Dectin-1-dependent Syk activation for phagosomal maturation. Taken together, these results support a model where Dectin-1 not only controls internalization of ß-1,3-glucan containing cargo and triggers proinflammatory cytokines, but also acts as a master regulator for subsequent phagolysosomal maturation through Syk activation.
Assuntos
Candida albicans/metabolismo , Lectinas Tipo C/metabolismo , Fagossomos/metabolismo , beta-Glucanas/metabolismo , Animais , Linhagem Celular , Citocinas/genética , Citocinas/metabolismo , Ativação Enzimática/genética , Mediadores da Inflamação/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/genética , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Lectinas Tipo C/genética , Camundongos , Fagossomos/genética , Fagossomos/microbiologia , Proteínas Tirosina Quinases/genética , Proteínas Tirosina Quinases/metabolismo , Quinase Syk , Proteínas rab5 de Ligação ao GTP/genética , Proteínas rab5 de Ligação ao GTP/metabolismoRESUMO
Understanding host defense against microbes is key to developing new and more effective therapies for infection and inflammatory disease. However, how animals integrate multiple environmental signals and discriminate between different pathogens to mount specific and tailored responses remains poorly understood. Using the genetically tractable model host Caenorhabditis elegans and pathogenic bacterium Staphylococcus aureus, we describe an important role for hypoxia-inducible factor (HIF) in defining the specificity of the host response in the intestine. We demonstrate that loss of egl-9, a negative regulator of HIF, confers HIF-dependent enhanced susceptibility to S. aureus while increasing resistance to Pseudomonas aeruginosa. In our attempt to understand how HIF could have these apparently dichotomous roles in host defense, we find that distinct pathways separately regulate two opposing functions of HIF: the canonical pathway is important for blocking expression of a set of HIF-induced defense genes, whereas a less well understood noncanonical pathway appears to be important for allowing the expression of another distinct set of HIF-repressed defense genes. Thus, HIF can function either as a gene-specific inducer or repressor of host defense, providing a molecular mechanism by which HIF can have apparently opposing roles in defense and inflammation. Together, our observations show that HIF can set the balance between alternative pathogen-specific host responses, potentially acting as an evolutionarily conserved specificity switch in the host innate immune response.
Assuntos
Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/imunologia , Pseudomonas aeruginosa/imunologia , Staphylococcus aureus/imunologia , Fatores de Transcrição/metabolismo , Animais , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Proteínas Culina/genética , Proteínas Culina/metabolismo , Especificidade de Hospedeiro , Imunidade Inata , Mucosa Intestinal/imunologia , Mucosa Intestinal/parasitologia , Interferência de RNA , RNA Interferente Pequeno , Fatores de Transcrição/genéticaRESUMO
Pore-forming toxins (PFTs) are the largest class of bacterial toxins and contribute to virulence by triggering host cell death. Vertebrates also express endogenous pore-forming proteins that induce cell death as part of host defense. To mitigate damage and promote survival, cells mobilize membrane repair mechanisms to neutralize and counteract pores, but how these pathways are activated is poorly understood. Here, we use a transposon-based gene activation screen to discover pathways that counteract the cytotoxicity of the archetypal PFT Staphylococcus aureus α-toxin. We identify the endolysosomal protein LITAF as a mediator of cellular resistance to PFT-induced cell death that is active against both bacterial toxins and the endogenous pore, gasdermin D, a terminal effector of pyroptosis. Activation of the ubiquitin ligase NEDD4 by potassium efflux mobilizes LITAF to recruit the endosomal sorting complexes required for transport (ESCRT) machinery to repair damaged membrane. Cells lacking LITAF, or carrying naturally occurring disease-associated mutations of LITAF, are highly susceptible to pore-induced death. Notably, LITAF-mediated repair occurs at endosomal membranes, resulting in expulsion of damaged membranes as exosomes, rather than through direct excision of pores from the surface plasma membrane. These results identify LITAF as a key effector that links sensing of cellular damage to repair.