RESUMO
Mucosal barrier immunity is essential for the maintenance of the commensal microflora and combating invasive bacterial infection. Although immune and epithelial cells are thought to be the canonical orchestrators of this complex equilibrium, here, we show that the enteric nervous system (ENS) plays an essential and non-redundant role in governing the antimicrobial protein (AMP) response. Using confocal microscopy and single-molecule fluorescence in situ mRNA hybridization (smFISH) studies, we observed that intestinal neurons produce the pleiotropic cytokine IL-18. Strikingly, deletion of IL-18 from the enteric neurons alone, but not immune or epithelial cells, rendered mice susceptible to invasive Salmonella typhimurium (S.t.) infection. Mechanistically, unbiased RNA sequencing and single-cell sequencing revealed that enteric neuronal IL-18 is specifically required for homeostatic goblet cell AMP production. Together, we show that neuron-derived IL-18 signaling controls tissue-wide intestinal immunity and has profound consequences on the mucosal barrier and invasive bacterial killing.
Assuntos
Imunidade nas Mucosas/imunologia , Interleucina-18/imunologia , Mucosa Intestinal/imunologia , Animais , Citocinas/imunologia , Sistema Nervoso Entérico/imunologia , Sistema Nervoso Entérico/metabolismo , Células Epiteliais/imunologia , Feminino , Células Caliciformes/imunologia , Interleucina-18/biossíntese , Mucosa Intestinal/metabolismo , Intestino Delgado/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/imunologia , Ratos , Ratos Sprague-Dawley , Infecções por Salmonella/imunologia , Salmonella typhimurium/imunologia , Transdução de Sinais/imunologiaRESUMO
Gut-innervating nociceptor sensory neurons respond to noxious stimuli by initiating protective responses including pain and inflammation; however, their role in enteric infections is unclear. Here, we find that nociceptor neurons critically mediate host defense against the bacterial pathogen Salmonella enterica serovar Typhimurium (STm). Dorsal root ganglia nociceptors protect against STm colonization, invasion, and dissemination from the gut. Nociceptors regulate the density of microfold (M) cells in ileum Peyer's patch (PP) follicle-associated epithelia (FAE) to limit entry points for STm invasion. Downstream of M cells, nociceptors maintain levels of segmentous filamentous bacteria (SFB), a gut microbe residing on ileum villi and PP FAE that mediates resistance to STm infection. TRPV1+ nociceptors directly respond to STm by releasing calcitonin gene-related peptide (CGRP), a neuropeptide that modulates M cells and SFB levels to protect against Salmonella infection. These findings reveal a major role for nociceptor neurons in sensing and defending against enteric pathogens.
Assuntos
Microbioma Gastrointestinal/fisiologia , Interações entre Hospedeiro e Microrganismos/fisiologia , Nociceptores/fisiologia , Animais , Epitélio/metabolismo , Feminino , Gânglios Espinais/metabolismo , Gânglios Espinais/microbiologia , Mucosa Intestinal/microbiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Nociceptores/metabolismo , Nódulos Linfáticos Agregados/inervação , Nódulos Linfáticos Agregados/metabolismo , Infecções por Salmonella/metabolismo , Salmonella typhimurium/metabolismo , Salmonella typhimurium/patogenicidade , Células Receptoras Sensoriais/metabolismo , Células Receptoras Sensoriais/fisiologiaRESUMO
By developing a high-density murine immunophenotyping platform compatible with high-throughput genetic screening, we have established profound contributions of genetics and structure to immune variation (http://www.immunophenotype.org). Specifically, high-throughput phenotyping of 530 unique mouse gene knockouts identified 140 monogenic 'hits', of which most had no previous immunologic association. Furthermore, hits were collectively enriched in genes for which humans show poor tolerance to loss of function. The immunophenotyping platform also exposed dense correlation networks linking immune parameters with each other and with specific physiologic traits. Such linkages limit freedom of movement for individual immune parameters, thereby imposing genetically regulated 'immunologic structures', the integrity of which was associated with immunocompetence. Hence, we provide an expanded genetic resource and structural perspective for understanding and monitoring immune variation in health and disease.
Assuntos
Infecções por Enterobacteriaceae/imunologia , Variação Genética/genética , Ensaios de Triagem em Larga Escala/métodos , Imunofenotipagem/métodos , Infecções por Salmonella/imunologia , Animais , Citrobacter/imunologia , Infecções por Enterobacteriaceae/microbiologia , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Modelos Animais , Salmonella/imunologia , Infecções por Salmonella/microbiologiaRESUMO
Sickness-induced anorexia is a conserved behavior induced during infections. Here, we report that an intestinal pathogen, Salmonella Typhimurium, inhibits anorexia by manipulating the gut-brain axis. Inhibition of inflammasome activation by the S. Typhimurium effector, SlrP, prevented anorexia caused by IL-1ß-mediated signaling to the hypothalamus via the vagus nerve. Rather than compromising host defenses, pathogen-mediated inhibition of anorexia increased host survival. SlrP-mediated inhibition of anorexia prevented invasion and systemic infection by wild-type S. Typhimurium, reducing virulence while increasing transmission to new hosts, suggesting that there are trade-offs between transmission and virulence. These results clarify the complex and contextual role of anorexia in host-pathogen interactions and suggest that microbes have evolved mechanisms to modulate sickness-induced behaviors to promote health of their host and their transmission at the expense of virulence.
Assuntos
Anorexia/microbiologia , Infecções por Salmonella/microbiologia , Infecções por Salmonella/transmissão , Salmonella typhimurium/patogenicidade , Animais , Proteínas de Bactérias/metabolismo , Interações Hospedeiro-Patógeno , Humanos , Inflamassomos/imunologia , Interleucina-1beta/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Vias Neurais , Infecções por Salmonella/imunologia , Salmonella typhimurium/fisiologia , Organismos Livres de Patógenos Específicos , VirulênciaRESUMO
Intestinal intraepithelial lymphocytes (IELs) are located at the critical interface between the intestinal lumen, which is chronically exposed to food and microbes, and the core of the body. Using high-resolution microscopy techniques and intersectional genetic tools, we investigated the nature of IEL responses to luminal microbes. We observed that TCRγδ IELs exhibit unique microbiota-dependent location and movement patterns in the epithelial compartment. This behavioral pattern quickly changes upon exposure to different enteric pathogens, resulting in increased interepithelial cell (EC) scanning, expression of antimicrobial genes, and glycolysis. Both dynamic and metabolic changes to γδ IEL depend on pathogen sensing by ECs. Direct modulation of glycolysis is sufficient to change γδ IEL behavior and susceptibility to early pathogen invasion. Our results uncover a coordinated EC-IEL response to enteric infections that modulates lymphocyte energy utilization and dynamics and supports maintenance of the intestinal epithelial barrier. VIDEO ABSTRACT.
Assuntos
Intestinos/citologia , Intestinos/imunologia , Infecções por Salmonella/imunologia , Linfócitos T/imunologia , Animais , Células Epiteliais/metabolismo , Vigilância Imunológica , Mucosa Intestinal/imunologia , Camundongos , Infecções por Salmonella/microbiologia , Salmonella typhimurium/fisiologiaRESUMO
Proper adaptation to environmental perturbations is essential for tissue homeostasis. In the intestine, diverse environmental cues can be sensed by immune cells, which must balance resistance to microorganisms with tolerance, avoiding excess tissue damage. By applying imaging and transcriptional profiling tools, we interrogated how distinct microenvironments in the gut regulate resident macrophages. We discovered that macrophages exhibit a high degree of gene-expression specialization dependent on their proximity to the gut lumen. Lamina propria macrophages (LpMs) preferentially expressed a pro-inflammatory phenotype when compared to muscularis macrophages (MMs), which displayed a tissue-protective phenotype. Upon luminal bacterial infection, MMs further enhanced tissue-protective programs, and this was attributed to swift activation of extrinsic sympathetic neurons innervating the gut muscularis and norepinephrine signaling to ß2 adrenergic receptors on MMs. Our results reveal unique intra-tissue macrophage specialization and identify neuro-immune communication between enteric neurons and macrophages that induces rapid tissue-protective responses to distal perturbations.
Assuntos
Intestino Delgado/fisiologia , Macrófagos/imunologia , Neurônios/citologia , Animais , Linhagem Celular , Mucosa Intestinal/citologia , Mucosa Intestinal/fisiologia , Intestino Delgado/citologia , Intestino Delgado/imunologia , Macrófagos/citologia , Camundongos , Mucosa/citologia , Mucosa/fisiologia , Neuroimunomodulação , Neurônios/fisiologia , Receptores Adrenérgicos beta 2/metabolismo , Infecções por Salmonella/imunologia , Salmonella typhimurium/fisiologia , Organismos Livres de Patógenos EspecíficosRESUMO
While conventional pathogenic protists have been extensively studied, there is an underappreciated constitutive protist microbiota that is an integral part of the vertebrate microbiome. The impact of these species on the host and their potential contributions to mucosal immune homeostasis remain poorly studied. Here, we show that the protozoan Tritrichomonas musculis activates the host epithelial inflammasome to induce IL-18 release. Epithelial-derived IL-18 promotes dendritic cell-driven Th1 and Th17 immunity and confers dramatic protection from mucosal bacterial infections. Along with its role as a "protistic" antibiotic, colonization with T. musculis exacerbates the development of T-cell-driven colitis and sporadic colorectal tumors. Our findings demonstrate a novel mutualistic host-protozoan interaction that increases mucosal host defenses at the cost of an increased risk of inflammatory disease.
Assuntos
Colite/imunologia , Colite/parasitologia , Interações Hospedeiro-Parasita , Inflamassomos/imunologia , Mucosa Intestinal/parasitologia , Microbiota/imunologia , Tricomoníase/imunologia , Trichomonas/imunologia , Animais , Colite/microbiologia , Dientamoeba/imunologia , Imunidade nas Mucosas , Interleucina-18/imunologia , Mucosa Intestinal/imunologia , Mucosa Intestinal/microbiologia , Camundongos , Camundongos Endogâmicos C57BL , Infecções por Salmonella/imunologia , Salmonella typhimurium/imunologia , Simbiose , Células Th1/imunologia , Células Th17/imunologiaRESUMO
Interactions between intracellular bacteria and mononuclear phagocytes give rise to diverse cellular phenotypes that may determine the outcome of infection. Recent advances in single-cell RNA sequencing (scRNA-seq) have identified multiple subsets within the mononuclear population, but implications to their function during infection are limited. Here, we surveyed the mononuclear niche of intracellular Salmonella Typhimurium (S.Tm) during early systemic infection in mice. We described eclipse-like growth kinetics in the spleen, with a first phase of bacterial control mediated by tissue-resident red-pulp macrophages. A second phase involved extensive bacterial replication within a macrophage population characterized by CD9 expression. We demonstrated that CD9+ macrophages induced pathways for detoxificating oxidized lipids, that may be utilized by intracellular S.Tm. We established that CD9+ macrophages originated from non-classical monocytes (NCM), and NCM-depleted mice were more resistant to S.Tm infection. Our study defines macrophage subset-specific host-pathogen interactions that determine early infection dynamics and infection outcome of the entire organism.
Assuntos
Macrófagos/imunologia , Infecções por Salmonella/imunologia , Salmonella typhimurium/fisiologia , Baço/imunologia , Animais , Interações Hospedeiro-Patógeno , Humanos , Espaço Intracelular , Metabolismo dos Lipídeos , Macrófagos/microbiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Oxirredução , Análise de Célula Única , Baço/microbiologia , Tetraspanina 29/metabolismoRESUMO
Encounters between immune cells and invading bacteria ultimately determine the course of infection. These interactions are usually measured in populations of cells, masking cell-to-cell variation that may be important for infection outcome. To characterize the gene expression variation that underlies distinct infection outcomes and monitor infection phenotypes, we developed an experimental system that combines single-cell RNA-seq with fluorescent markers. Probing the responses of individual macrophages to invading Salmonella, we find that variation between individual infected host cells is determined by the heterogeneous activity of bacterial factors in individual infecting bacteria. We illustrate how variable PhoPQ activity in the population of invading bacteria drives variable host type I IFN responses by modifying LPS in a subset of bacteria. This work demonstrates a causative link between host and bacterial variability, with cell-to-cell variation between different bacteria being sufficient to drive radically different host immune responses. This co-variation has implications for host-pathogen dynamics in vivo.
Assuntos
Interações Hospedeiro-Patógeno , Macrófagos/imunologia , Salmonella typhimurium/fisiologia , Animais , Interferon Tipo I/imunologia , Lipopolissacarídeos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Infecções por Salmonella/imunologia , Infecções por Salmonella/microbiologia , Organismos Livres de Patógenos EspecíficosRESUMO
Although programmed cell death can control intracellular bacterial replication, the role of cell death during systemic Salmonella infection remained elusive. In this issue of Immunity, Doerflinger et al. discover a critical but overlapping role for cell death associated caspases during Salmonella infection.
Assuntos
Infecções por Salmonella , Apoptose , Caspases , Morte Celular , Humanos , SalmonellaRESUMO
Programmed cell death contributes to host defense against pathogens. To investigate the relative importance of pyroptosis, necroptosis, and apoptosis during Salmonella infection, we infected mice and macrophages deficient for diverse combinations of caspases-1, -11, -12, and -8 and receptor interacting serine/threonine kinase 3 (RIPK3). Loss of pyroptosis, caspase-8-driven apoptosis, or necroptosis had minor impact on Salmonella control. However, combined deficiency of these cell death pathways caused loss of bacterial control in mice and their macrophages, demonstrating that host defense can employ varying components of several cell death pathways to limit intracellular infections. This flexible use of distinct cell death pathways involved extensive cross-talk between initiators and effectors of pyroptosis and apoptosis, where initiator caspases-1 and -8 also functioned as executioners when all known effectors of cell death were absent. These findings uncover a highly coordinated and flexible cell death system with in-built fail-safe processes that protect the host from intracellular infections.
Assuntos
Apoptose/imunologia , Macrófagos/imunologia , Necroptose/imunologia , Piroptose/imunologia , Infecções por Salmonella/imunologia , Salmonella/imunologia , Animais , Caspase 1/deficiência , Caspase 1/genética , Caspase 12/deficiência , Caspase 12/genética , Caspase 8/genética , Caspases Iniciadoras/deficiência , Caspases Iniciadoras/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína Serina-Treonina Quinases de Interação com Receptores/deficiência , Proteína Serina-Treonina Quinases de Interação com Receptores/genéticaRESUMO
Epithelial tissues continually undergo apoptosis. Commensal organisms that inhabit the epithelium influence tissue homeostasis, in which regulatory T cells (Treg cells) have a central role. However, the physiological importance of epithelial cell apoptosis and how the number of Treg cells is regulated are both incompletely understood. Here we found that apoptotic epithelial cells negatively regulated the commensal-stimulated proliferation of Treg cells. Gut commensals stimulated CX3CR1(+)CD103(-)CD11b(+) dendritic cells (DCs) to produce interferon-ß (IFN-ß), which augmented the proliferation of Treg cells in the intestine. Conversely, phosphatidylserine exposed on apoptotic epithelial cells suppressed IFN-ß production by the DCs via inhibitory signaling mediated by the cell-surface glycoprotein CD300a and thus suppressed Treg cell proliferation. Our findings reveal a regulatory role for apoptotic epithelial cells in maintaining the number of Treg cell and tissue homeostasis.
Assuntos
Apoptose/imunologia , Epiderme/imunologia , Células Epiteliais/imunologia , Microbioma Gastrointestinal/imunologia , Interferon beta/imunologia , Mucosa Intestinal/imunologia , Mucosa Respiratória/imunologia , Linfócitos T Reguladores/imunologia , Alérgenos/toxicidade , Animais , Colite/induzido quimicamente , Colite/imunologia , Colite/patologia , Colo/citologia , Colo/imunologia , Células Dendríticas/imunologia , Dermatite Alérgica de Contato/etiologia , Dermatite Alérgica de Contato/imunologia , Dermatite Alérgica de Contato/patologia , Sulfato de Dextrana/toxicidade , Células Epidérmicas , Citometria de Fluxo , Imuno-Histoquímica , Mucosa Intestinal/citologia , Células de Langerhans/imunologia , Pulmão/citologia , Pulmão/imunologia , Camundongos , Camundongos Knockout , Ovalbumina/toxicidade , Reação em Cadeia da Polimerase em Tempo Real , Receptores Imunológicos/genética , Mucosa Respiratória/citologia , Infecções por Salmonella/imunologia , Salmonella typhimuriumRESUMO
Fever is an evolutionarily conserved response that confers survival benefits during infection. However, the underlying mechanism remains obscure. Here, we report that fever promoted T lymphocyte trafficking through heat shock protein 90 (Hsp90)-induced α4 integrin activation and signaling in T cells. By inducing selective binding of Hsp90 to α4 integrins, but not ß2 integrins, fever increased α4-integrin-mediated T cell adhesion and transmigration. Mechanistically, Hsp90 bound to the α4 tail and activated α4 integrins via inside-out signaling. Moreover, the N and C termini of one Hsp90 molecule simultaneously bound to two α4 tails, leading to dimerization and clustering of α4 integrins on the cell membrane and subsequent activation of the FAK-RhoA pathway. Abolishment of Hsp90-α4 interaction inhibited fever-induced T cell trafficking to draining lymph nodes and impaired the clearance of bacterial infection. Our findings identify the Hsp90-α4-integrin axis as a thermal sensory pathway that promotes T lymphocyte trafficking and enhances immune surveillance during infection.
Assuntos
Febre/imunologia , Proteínas de Choque Térmico HSP90/metabolismo , Integrina alfa4/metabolismo , Infecções por Salmonella/imunologia , Salmonella typhimurium/imunologia , Linfócitos T/imunologia , Animais , Carga Bacteriana , Adesão Celular , Movimento Celular , Dimerização , Quinase 1 de Adesão Focal/metabolismo , Vigilância Imunológica , Integrina alfa4/genética , Ativação Linfocitária , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Ligação Proteica , Transdução de Sinais , Proteína rhoA de Ligação ao GTP/metabolismoRESUMO
Long noncoding RNAs (lncRNAs) are increasingly appreciated as regulators of cell-specific gene expression. Here, an enhancer-like lncRNA termed NeST (nettoie Salmonella pas Theiler's [cleanup Salmonella not Theiler's]) is shown to be causal for all phenotypes conferred by murine viral susceptibility locus Tmevp3. This locus was defined by crosses between SJL/J and B10.S mice and contains several candidate genes, including NeST. The SJL/J-derived locus confers higher lncRNA expression, increased interferon-γ (IFN-γ) abundance in activated CD8(+) T cells, increased Theiler's virus persistence, and decreased Salmonella enterica pathogenesis. Transgenic expression of NeST lncRNA alone was sufficient to confer all phenotypes of the SJL/J locus. NeST RNA was found to bind WDR5, a component of the histone H3 lysine 4 methyltransferase complex, and to alter histone 3 methylation at the IFN-γ locus. Thus, this lncRNA regulates epigenetic marking of IFN-γ-encoding chromatin, expression of IFN-γ, and susceptibility to a viral and a bacterial pathogen.
Assuntos
Suscetibilidade a Doenças , Epigênese Genética , Interferon gama/genética , RNA Longo não Codificante/genética , Animais , Linfócitos T CD8-Positivos/imunologia , Infecções por Cardiovirus/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Infecções por Salmonella/imunologia , Salmonella typhimurium/imunologia , Theilovirus/imunologiaRESUMO
Several intracellular pathogens, including Salmonella enterica and Mycobacterium tuberculosis, require the virulence protein MgtC to survive within macrophages and to cause a lethal infection in mice. We now report that, unlike secreted virulence factors that target the host vacuolar ATPase to withstand phagosomal acidity, the MgtC protein acts on Salmonella's own F1Fo ATP synthase. This complex couples proton translocation to ATP synthesis/hydrolysis and is required for virulence. We establish that MgtC interacts with the a subunit of the F1Fo ATP synthase, hindering ATP-driven proton translocation and NADH-driven ATP synthesis in inverted vesicles. An mgtC null mutant displays heightened ATP levels and an acidic cytoplasm, whereas mgtC overexpression decreases ATP levels. A single amino acid substitution in MgtC that prevents binding to the F1Fo ATP synthase abolishes control of ATP levels and attenuates pathogenicity. MgtC provides a singular example of a virulence protein that promotes pathogenicity by interfering with another virulence protein.
Assuntos
Proteínas de Bactérias/metabolismo , Proteínas de Transporte de Cátions/metabolismo , ATPases Translocadoras de Prótons/antagonistas & inibidores , Infecções por Salmonella/microbiologia , Salmonella typhimurium/citologia , Salmonella typhimurium/patogenicidade , Fatores de Virulência/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Feminino , Concentração de Íons de Hidrogênio , Macrófagos/microbiologia , Potenciais da Membrana , Camundongos , Camundongos Endogâmicos C3H , Subunidades Proteicas/antagonistas & inibidores , Salmonella typhimurium/enzimologia , VirulênciaRESUMO
Salmonella enterica (Se) bacteria cause persistent intracellular infections while stimulating a robust interferon-γ-producing CD4+ T (Th1) cell response. We addressed this paradox of concomitant infection and immunity by tracking fluorescent Se organisms in mice. Se bacteria persisted in nitric oxide synthase (iNOS)-producing resident and recruited macrophages while inducing genes related to protection from nitric oxide. Se-infected cells occupied iNOS+ splenic granulomas that excluded T cells but were surrounded by mononuclear phagocytes producing the chemokines CXCL9 and CXCL10, and Se epitope-specific Th1 cells expressing CXCR3, the receptor for these chemokines. Blockade of CXCR3 inhibited Th1 occupancy of CXCL9/10-dense regions, reduced activation of the Th1 cells, and led to increased Se growth. Thus, intracellular Se bacteria survive in their hosts by counteracting toxic products of the innate immune response and by residing in T cell-sparse granulomas, away from abundant Th1 cells positioned via CXCR3 in a bordering region that act to limit infection.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Granuloma/imunologia , Receptores CXCR3/imunologia , Infecções por Salmonella/imunologia , Salmonella enterica/imunologia , Células Th1/imunologia , Animais , Linfócitos T CD4-Positivos/metabolismo , Linfócitos T CD4-Positivos/microbiologia , Quimiocina CXCL10/imunologia , Quimiocina CXCL10/metabolismo , Quimiocina CXCL9/imunologia , Quimiocina CXCL9/metabolismo , Granuloma/metabolismo , Granuloma/microbiologia , Interações Hospedeiro-Patógeno/imunologia , Ligantes , Ativação de Macrófagos/imunologia , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores CXCR3/metabolismo , Infecções por Salmonella/metabolismo , Infecções por Salmonella/microbiologia , Salmonella enterica/fisiologia , Células Th1/metabolismo , Células Th1/microbiologiaRESUMO
Acute gastrointestinal infection with intracellular pathogens like Salmonella Typhimurium triggers the release of the proinflammatory cytokine interleukin 1ß (IL-1ß). However, the role of IL-1ß in intestinal defense against Salmonella remains unclear. Here, we show that IL-1ß production is detrimental during Salmonella infection. Mice lacking IL-1ß (IL-1ß -/-) failed to recruit neutrophils to the gut during infection, which reduced tissue damage and prevented depletion of short-chain fatty acid (SCFA)-producing commensals. Changes in epithelial cell metabolism that typically support pathogen expansion, such as switching energy production from fatty acid oxidation to fermentation, were absent in infected IL-1ß -/- mice which inhibited Salmonella expansion. Additionally, we found that IL-1ß induces expression of complement anaphylatoxins and suppresses the complement-inactivator carboxypeptidase N (CPN1). Disrupting this process via IL-1ß loss prevented mortality in Salmonella-infected IL-1ß -/- mice. Finally, we found that IL-1ß expression correlates with expression of the complement receptor in patients suffering from sepsis, but not uninfected patients and healthy individuals. Thus, Salmonella exploits IL-1ß signaling to outcompete commensal microbes and establish gut colonization. Moreover, our findings identify the intersection of IL-1ß signaling and the complement system as key host factors involved in controlling mortality during invasive Salmonellosis.
Assuntos
Interleucina-1beta , Infecções por Salmonella , Animais , Humanos , Camundongos , Interleucina-1beta/genética , Interleucina-1beta/metabolismo , Neutrófilos/metabolismo , Infecções por Salmonella/metabolismo , Salmonella typhimurium/metabolismo , VirulênciaRESUMO
Bacterial pathogens utilize the factors of their hosts to infect them, but which factors they exploit remain poorly defined. Here, we show that a pathogenic Salmonella enterica serovar Typhimurium (STm) exploits host polyamines for the functional expression of virulence factors. An STm mutant strain lacking principal genes required for polyamine synthesis and transport exhibited impaired infectivity in mice. A polyamine uptake-impaired strain of STm was unable to inject effectors of the type 3 secretion system into host cells due to a failure of needle assembly. STm infection stimulated host polyamine production by increasing arginase expression. The decline in polyamine levels caused by difluoromethylornithine, which inhibits host polyamine production, attenuated STm colonization, whereas polyamine supplementation augmented STm pathogenesis. Our work reveals that host polyamines are a key factor promoting STm infection, and therefore a promising therapeutic target for bacterial infection.
Assuntos
Poliaminas , Salmonella typhimurium , Sistemas de Secreção Tipo III , Fatores de Virulência , Salmonella typhimurium/metabolismo , Salmonella typhimurium/patogenicidade , Salmonella typhimurium/genética , Animais , Poliaminas/metabolismo , Camundongos , Sistemas de Secreção Tipo III/metabolismo , Sistemas de Secreção Tipo III/genética , Fatores de Virulência/metabolismo , Fatores de Virulência/genética , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Interações Hospedeiro-Patógeno , Humanos , Infecções por Salmonella/metabolismo , Infecções por Salmonella/microbiologia , FemininoRESUMO
Intestinal epithelial cells (IECs) play pivotal roles in nutrient uptake and in the protection against gut microorganisms. However, certain enteric pathogens, such as Salmonella enterica serovar Typhimurium (S. Tm), can invade IECs by employing flagella and type III secretion systems (T3SSs) with cognate effector proteins and exploit IECs as a replicative niche. Detection of flagella or T3SS proteins by IECs results in rapid host cell responses, i.e., the activation of inflammasomes. Here, we introduce a single-cell manipulation technology based on fluidic force microscopy (FluidFM) that enables direct bacteria delivery into the cytosol of single IECs within a murine enteroid monolayer. This approach allows to specifically study pathogen-host cell interactions in the cytosol uncoupled from preceding events such as docking, initiation of uptake, or vacuole escape. Consistent with current understanding, we show using a live-cell inflammasome reporter that exposure of the IEC cytosol to S. Tm induces NAIP/NLRC4 inflammasomes via its known ligands flagellin and T3SS rod and needle. Injected S. Tm mutants devoid of these invasion-relevant ligands were able to grow in the cytosol of IECs despite the absence of T3SS functions, suggesting that, in the absence of NAIP/NLRC4 inflammasome activation and the ensuing cell death, no effector-mediated host cell manipulation is required to render the epithelial cytosol growth-permissive for S. Tm. Overall, the experimental system to introduce S. Tm into single enteroid cells enables investigations into the molecular basis governing host-pathogen interactions in the cytosol with high spatiotemporal resolution.
Assuntos
Proteínas de Ligação ao Cálcio , Citosol , Flagelina , Interações Hospedeiro-Patógeno , Inflamassomos , Salmonella typhimurium , Sistemas de Secreção Tipo III , Citosol/metabolismo , Citosol/microbiologia , Animais , Salmonella typhimurium/patogenicidade , Salmonella typhimurium/metabolismo , Sistemas de Secreção Tipo III/metabolismo , Inflamassomos/metabolismo , Camundongos , Flagelina/metabolismo , Proteína Inibidora de Apoptose Neuronal/metabolismo , Proteína Inibidora de Apoptose Neuronal/genética , Células Epiteliais/microbiologia , Células Epiteliais/metabolismo , Proteínas Reguladoras de Apoptose/metabolismo , Proteínas Reguladoras de Apoptose/genética , Camundongos Endogâmicos C57BL , Proteínas Adaptadoras de Sinalização CARD/metabolismo , Proteínas Adaptadoras de Sinalização CARD/genética , Análise de Célula Única/métodos , Infecções por Salmonella/microbiologia , Infecções por Salmonella/metabolismo , Infecções por Salmonella/imunologia , Mucosa Intestinal/microbiologia , Mucosa Intestinal/metabolismoRESUMO
Understanding the dynamic evolution of Salmonella is vital for effective bacterial infection management. This study explores the role of the flexible genome, organised in regions of genomic plasticity (RGP), in shaping the pathogenicity of Salmonella lineages. Through comprehensive genomic analysis of 12,244 Salmonella spp. genomes covering 2 species, 6 subspecies, and 46 serovars, we uncover distinct integration patterns of pathogenicity-related gene clusters into RGP, challenging traditional views of gene distribution. These RGP exhibit distinct preferences for specific genomic spots, and the presence or absence of such spots across Salmonella lineages profoundly shapes strain pathogenicity. RGP preferences are guided by conserved flanking genes surrounding integration spots, implicating their involvement in regulatory networks and functional synergies with integrated gene clusters. Additionally, we emphasise the multifaceted contributions of plasmids and prophages to the pathogenicity of diverse Salmonella lineages. Overall, this study provides a comprehensive blueprint of the pathogenicity potential of Salmonella. This unique insight identifies genomic spots in nonpathogenic lineages that hold the potential for harbouring pathogenicity genes, providing a foundation for predicting future adaptations and developing targeted strategies against emerging human pathogenic strains.