RESUMEN
Antibiotic resistance and evasion are incompletely understood and complicated by the fact that murine interval dosing models do not fully recapitulate antibiotic pharmacokinetics in humans. To better understand how gastrointestinal bacteria respond to antibiotics, we colonized germ-free mice with a pan-susceptible genetically barcoded Escherichia coli clinical isolate and administered the antibiotic cefepime via programmable subcutaneous pumps, allowing closer emulation of human parenteral antibiotic dynamics. E. coli was only recovered from intestinal tissue, where cefepime concentrations were still inhibitory. Strikingly, "some" E. coli isolates were not cefepime resistant but acquired mutations in genes involved in polysaccharide capsular synthesis increasing their invasion and survival within human intestinal cells. Deleting wbaP involved in capsular polysaccharide synthesis mimicked this phenotype, allowing increased invasion of colonocytes where cefepime concentrations were reduced. Additionally, "some" mutant strains exhibited a persister phenotype upon further cefepime exposure. This work uncovers a mechanism allowing "select" gastrointestinal bacteria to evade antibiotic treatment.
Asunto(s)
Antibacterianos , Escherichia coli , Humanos , Animales , Ratones , Cefepima , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Bacterias , Tracto Gastrointestinal/microbiología , Polisacáridos , Pruebas de Sensibilidad Microbiana , MamíferosRESUMEN
The intestinal microbiota regulates mammalian lipid absorption, metabolism, and storage. We report that the microbiota reprograms intestinal lipid metabolism in mice by repressing the expression of long noncoding RNA (lncRNA) Snhg9 (small nucleolar RNA host gene 9) in small intestinal epithelial cells. Snhg9 suppressed the activity of peroxisome proliferator-activated receptor γ (PPARγ)-a central regulator of lipid metabolism-by dissociating the PPARγ inhibitor sirtuin 1 from cell cycle and apoptosis protein 2 (CCAR2). Forced expression of Snhg9 in the intestinal epithelium of conventional mice impaired lipid absorption, reduced body fat, and protected against diet-induced obesity. The microbiota repressed Snhg9 expression through an immune relay encompassing myeloid cells and group 3 innate lymphoid cells. Our findings thus identify an unanticipated role for a lncRNA in microbial control of host metabolism.
Asunto(s)
Microbioma Gastrointestinal , Intestinos , Metabolismo de los Lípidos , PPAR gamma , ARN Largo no Codificante , Sirtuina 1 , Animales , Ratones , Inmunidad Innata , Metabolismo de los Lípidos/genética , Linfocitos/inmunología , PPAR gamma/metabolismo , ARN Largo no Codificante/genética , ARN Largo no Codificante/metabolismo , Sirtuina 1/metabolismo , Proteínas de Ciclo Celular/metabolismo , Proteínas Reguladoras de la Apoptosis/metabolismo , Células Mieloides/inmunología , Intestinos/metabolismo , Intestinos/microbiología , Tejido Adiposo/microbiología , HumanosRESUMEN
In vitro systems have provided great insight into the mechanisms of antibiotic resistance. Yet, in vitro approaches cannot reflect the full complexity of what transpires within a host. As the mammalian gut is host to trillions of resident bacteria and thus a potential breeding ground for antibiotic resistance, we sought to better understand how gut bacteria respond to antibiotic treatment in vivo . Here, we colonized germ-free mice with a genetically barcoded antibiotic pan-susceptible Escherichia coli clinical isolate and then administered the antibiotic cefepime via programmable subcutaneous pumps which allowed for closer emulation of human parenteral antibiotic pharmacokinetics/dynamics. After seven days of antibiotics, we were unable to culture E. coli from feces. We were, however, able to recover barcoded E. coli from harvested gastrointestinal (GI) tissue, despite high GI tract and plasma cefepime concentrations. Strikingly, these E. coli isolates were not resistant to cefepime but had acquired mutations â" most notably in the wbaP gene, which encodes an enzyme required for the initiation of the synthesis of the polysaccharide capsule and lipopolysaccharide O antigen - that increased their ability to invade and survive within intestinal cells, including cultured human colonocytes. Further, these E. coli mutants exhibited a persister phenotype when exposed to cefepime, allowing for greater survival to pulses of cefepime treatment when compared to the wildtype strain. Our findings highlight a mechanism by which bacteria in the gastrointestinal tract can adapt to antibiotic treatment by increasing their ability to persist during antibiotic treatment and invade intestinal epithelial cells where antibiotic concentrations are substantially reduced.
RESUMEN
A diverse group of antimicrobial proteins (AMPs) helps protect the mammalian intestine from varied microbial challenges. We show that small proline-rich protein 2A (SPRR2A) is an intestinal antibacterial protein that is phylogenetically unrelated to previously discovered mammalian AMPs. In this study, SPRR2A was expressed in Paneth cells and goblet cells and selectively killed Gram-positive bacteria by disrupting their membranes. SPRR2A shaped intestinal microbiota composition, restricted bacterial association with the intestinal surface, and protected against Listeria monocytogenes infection. SPRR2A differed from other intestinal AMPs in that it was induced by type 2 cytokines produced during helminth infection. Moreover, SPRR2A protected against helminth-induced bacterial invasion of intestinal tissue. Thus, SPRR2A is a distinctive AMP triggered by type 2 immunity that protects the intestinal barrier during helminth infection.
Asunto(s)
Proteínas Ricas en Prolina del Estrato Córneo/metabolismo , Microbioma Gastrointestinal , Bacterias Grampositivas/fisiología , Mucosa Intestinal/metabolismo , Intestinos/microbiología , Nematospiroides dubius , Infecciones por Strongylida/inmunología , Animales , Carga Bacteriana , Membrana Celular/metabolismo , Permeabilidad de la Membrana Celular , Proteínas Ricas en Prolina del Estrato Córneo/genética , Citocinas/metabolismo , Susceptibilidad a Enfermedades , Células Caliciformes/metabolismo , Humanos , Inmunidad Innata , Mucosa Intestinal/microbiología , Listeria monocytogenes/fisiología , Listeriosis/microbiología , Ratones , Viabilidad Microbiana , Células de Paneth/metabolismo , Proteínas Citotóxicas Formadoras de Poros/genética , Proteínas Citotóxicas Formadoras de Poros/metabolismo , Infecciones por Strongylida/metabolismo , Infecciones por Strongylida/microbiologíaRESUMEN
Environmental light cycles entrain circadian feeding behaviors in animals that produce rhythms in exposure to foodborne bacteria. Here, we show that the intestinal microbiota generates diurnal rhythms in innate immunity that synchronize with feeding rhythms to anticipate microbial exposure. Rhythmic expression of antimicrobial proteins was driven by daily rhythms in epithelial attachment by segmented filamentous bacteria (SFB), members of the mouse intestinal microbiota. Rhythmic SFB attachment was driven by the circadian clock through control of feeding rhythms. Mechanistically, rhythmic SFB attachment activated an immunological circuit involving group 3 innate lymphoid cells. This circuit triggered oscillations in epithelial STAT3 expression and activation that produced rhythmic antimicrobial protein expression and caused resistance to Salmonella Typhimurium infection to vary across the day-night cycle. Thus, host feeding rhythms synchronize with the microbiota to promote rhythms in intestinal innate immunity that anticipate exogenous microbial exposure.
Asunto(s)
Relojes Circadianos/fisiología , Ritmo Circadiano/fisiología , Microbioma Gastrointestinal , Inmunidad Innata , Animales , Péptidos Catiónicos Antimicrobianos/metabolismo , Adhesión Bacteriana , Adhesión Celular , Células Epiteliales/microbiología , Conducta Alimentaria , Intestino Delgado/microbiología , Intestino Delgado/ultraestructura , Linfocitos/metabolismo , Ratones Endogámicos C57BL , Muramidasa/metabolismo , Proteínas Asociadas a Pancreatitis/metabolismo , Factor de Transcripción STAT3/metabolismo , Salmonelosis Animal/microbiología , Transducción de SeñalRESUMEN
The higher prevalence of inflammatory bowel disease (IBD) in Western countries points to Western diet as a possible IBD risk factor. High sugar, which is linked to many noncommunicable diseases, is a hallmark of the Western diet, but its role in IBD remains unknown. Here, we studied the effects of simple sugars such as glucose and fructose on colitis pathogenesis in wild-type and Il10-/- mice. Wild-type mice fed 10% glucose in drinking water or high-glucose diet developed severe colitis induced by dextran sulfate sodium. High-glucose-fed Il10-/- mice also developed a worsened colitis compared to glucose-untreated Il10-/- mice. Short-term intake of high glucose or fructose did not trigger inflammatory responses in healthy gut but markedly altered gut microbiota composition. In particular, the abundance of the mucus-degrading bacteria Akkermansia muciniphila and Bacteroides fragilis was increased. Consistently, bacteria-derived mucolytic enzymes were enriched leading to erosion of the colonic mucus layer of sugar-fed wild-type and Il10-/- mice. Sugar-induced exacerbation of colitis was not observed when mice were treated with antibiotics or maintained in a germ-free environment, suggesting that altered microbiota played a critical role in sugar-induced colitis pathogenesis. Furthermore, germ-free mice colonized with microbiota from sugar-treated mice showed increased colitis susceptibility. Together, these data suggest that intake of simple sugars predisposes to colitis and enhances its pathogenesis via modulation of gut microbiota in mice.
Asunto(s)
Colitis , Azúcares de la Dieta , Animales , Colitis/inducido químicamente , Sulfato de Dextran , Dieta , Azúcares de la Dieta/efectos adversos , Modelos Animales de Enfermedad , Ratones , Ratones Endogámicos C57BL , MonosacáridosRESUMEN
During short-lived perturbations, such as inflammation, the gut microbiota exhibits resilience and reverts to its original configuration. Although microbial access to the micronutrient iron is decreased during colitis, pathogens can scavenge iron by using siderophores. How commensal bacteria acquire iron during gut inflammation is incompletely understood. Curiously, the human commensal Bacteroides thetaiotaomicron does not produce siderophores but grows under iron-limiting conditions using enterobacterial siderophores. Using RNA-seq, we identify B. thetaiotaomicron genes that were upregulated during Salmonella-induced gut inflammation and were predicted to be involved in iron uptake. Mutants in the xusABC locus (BT2063-2065) were defective for xenosiderophore-mediated iron uptake in vitro. In the normal mouse gut, the XusABC system was dispensable, while a xusA mutant colonized poorly during colitis. This work identifies xenosiderophore utilization as a critical mechanism for B. thetaiotaomicron to sustain colonization during inflammation and suggests a mechanism of how interphylum iron metabolism contributes to gut microbiota resilience.
Asunto(s)
Bacteroides thetaiotaomicron/metabolismo , Colitis/microbiología , Enterobacteriaceae/genética , Microbioma Gastrointestinal , Hierro/metabolismo , Sideróforos/genética , Animales , Bacteroides thetaiotaomicron/genética , Femenino , Genes Bacterianos , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , RNA-Seq , SimbiosisRESUMEN
Circadian rhythmicity is a defining feature of mammalian metabolism that synchronizes metabolic processes to day-night light cycles. Here, we show that the intestinal microbiota programs diurnal metabolic rhythms in the mouse small intestine through histone deacetylase 3 (HDAC3). The microbiota induced expression of intestinal epithelial HDAC3, which was recruited rhythmically to chromatin, and produced synchronized diurnal oscillations in histone acetylation, metabolic gene expression, and nutrient uptake. HDAC3 also functioned noncanonically to coactivate estrogen-related receptor α, inducing microbiota-dependent rhythmic transcription of the lipid transporter gene Cd36 and promoting lipid absorption and diet-induced obesity. Our findings reveal that HDAC3 integrates microbial and circadian cues for regulation of diurnal metabolic rhythms and pinpoint a key mechanism by which the microbiota controls host metabolism.
Asunto(s)
Ritmo Circadiano , Células Epiteliales/metabolismo , Microbioma Gastrointestinal , Histona Desacetilasas/metabolismo , Intestino Delgado/metabolismo , Acetilación , Animales , Antígenos CD36/metabolismo , Cromatina/metabolismo , Colon , Dieta Alta en Grasa , Vida Libre de Gérmenes , Intestino Delgado/citología , Síndrome Jet Lag , Metabolismo de los Lípidos , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Obesidad/metabolismo , Receptores de Estrógenos/metabolismo , Receptor Relacionado con Estrógeno ERRalfaRESUMEN
Inflammatory diseases of the gastrointestinal tract are frequently associated with dysbiosis, characterized by changes in gut microbial communities that include an expansion of facultative anaerobic bacteria of the Enterobacteriaceae family (phylum Proteobacteria). Here we show that a dysbiotic expansion of Enterobacteriaceae during gut inflammation could be prevented by tungstate treatment, which selectively inhibited molybdenum-cofactor-dependent microbial respiratory pathways that are operational only during episodes of inflammation. By contrast, we found that tungstate treatment caused minimal changes in the microbiota composition under homeostatic conditions. Notably, tungstate-mediated microbiota editing reduced the severity of intestinal inflammation in mouse models of colitis. We conclude that precision editing of the microbiota composition by tungstate treatment ameliorates the adverse effects of dysbiosis in the inflamed gut.
Asunto(s)
Colitis/tratamiento farmacológico , Colitis/microbiología , Microbioma Gastrointestinal/efectos de los fármacos , Intestinos/efectos de los fármacos , Intestinos/microbiología , Anaerobiosis/efectos de los fármacos , Animales , Respiración de la Célula/efectos de los fármacos , Disbiosis/tratamiento farmacológico , Disbiosis/microbiología , Enterobacteriaceae/efectos de los fármacos , Enterobacteriaceae/crecimiento & desarrollo , Enterobacteriaceae/metabolismo , Femenino , Inflamación/tratamiento farmacológico , Inflamación/microbiología , Inflamación/patología , Mucosa Intestinal/efectos de los fármacos , Mucosa Intestinal/microbiología , Mucosa Intestinal/patología , Intestinos/patología , Masculino , Ratones , Ratones Endogámicos C57BL , Molibdeno/metabolismo , Compuestos de Tungsteno/farmacología , Compuestos de Tungsteno/uso terapéuticoRESUMEN
During Salmonella-induced gastroenteritis, mucosal inflammation creates a niche that favors the expansion of the pathogen population over the microbiota. Here, we show that Salmonella Typhimurium infection was accompanied by dysbiosis, decreased butyrate levels, and substantially elevated lactate levels in the gut lumen. Administration of a lactate dehydrogenase inhibitor blunted lactate production in germ-free mice, suggesting that lactate was predominantly of host origin. Depletion of butyrate-producing Clostridia, either through oral antibiotic treatment or as part of the pathogen-induced dysbiosis, triggered a switch in host cells from oxidative metabolism to lactate fermentation, increasing both lactate levels and Salmonella lactate utilization. Administration of tributyrin or a PPARγ agonist diminished host lactate production and abrogated the fitness advantage conferred on Salmonella by lactate utilization. We conclude that alterations of the gut microbiota, specifically a depletion of Clostridia, reprogram host metabolism to perform lactate fermentation, thus supporting Salmonella infection.
Asunto(s)
Clostridium/crecimiento & desarrollo , Disbiosis/microbiología , Gastroenteritis/microbiología , Microbioma Gastrointestinal/efectos de los fármacos , Mucosa Intestinal/microbiología , Ácido Láctico/metabolismo , Salmonella typhimurium/metabolismo , Animales , Antibacterianos/farmacología , Ácido Butírico/metabolismo , Femenino , Fermentación , Gastroenteritis/patología , L-Lactato Deshidrogenasa/antagonistas & inhibidores , Masculino , Ratones , Ratones Endogámicos C57BL , PPAR gamma/agonistas , Infecciones por Salmonella/patología , Salmonella typhimurium/crecimiento & desarrollo , Triglicéridos/farmacologíaRESUMEN
The mucosal inflammatory response induced by Salmonella serovar Typhimurium creates a favorable niche for this gut pathogen. Conventional wisdom holds that S. Typhimurium undergoes an incomplete tricarboxylic acid (TCA) cycle in the anaerobic mammalian gut. One change during S. Typhimurium-induced inflammation is the production of oxidized compounds by infiltrating neutrophils. We show that inflammation-derived electron acceptors induce a complete, oxidative TCA cycle in S. Typhimurium, allowing the bacteria to compete with the microbiota for colonization. A complete TCA cycle facilitates utilization of the microbiota-derived fermentation product succinate as a carbon source. S. Typhimurium succinate utilization genes contribute to efficient colonization in conventionally raised mice, but provide no growth advantage in germ-free mice. Mono-association of gnotobiotic mice with Bacteroides, a major succinate producer, restores succinate utilization in S. Typhimurium. Thus, oxidative central metabolism enables S. Typhimurium to utilize a variety of carbon sources, including microbiota-derived succinate.
Asunto(s)
Bacterias/metabolismo , Bacteroides/metabolismo , Colitis/microbiología , Microbioma Gastrointestinal , Infecciones por Salmonella/microbiología , Salmonella typhimurium/metabolismo , Ácido Succínico/metabolismo , Animales , Bacterias/genética , Bacterias/aislamiento & purificación , Bacteroides/genética , Bacteroides/aislamiento & purificación , Ciclo del Ácido Cítrico , Colitis/metabolismo , Humanos , Mucosa Intestinal/metabolismo , Intestinos/microbiología , Ratones , Ratones Endogámicos CBA , Estrés Oxidativo , Infecciones por Salmonella/metabolismo , Salmonella typhimurium/genéticaRESUMEN
Intestinal inflammation is frequently associated with an alteration of the gut microbiota, termed dysbiosis, which is characterized by a reduced abundance of obligate anaerobic bacteria and an expansion of facultative Proteobacteria such as commensal E. coli. The mechanisms enabling the outgrowth of Proteobacteria during inflammation are incompletely understood. Metagenomic sequencing revealed bacterial formate oxidation and aerobic respiration to be overrepresented metabolic pathways in a chemically induced murine model of colitis. Dysbiosis was accompanied by increased formate levels in the gut lumen. Formate was of microbial origin since no formate was detected in germ-free mice. Complementary studies using commensal E. coli strains as model organisms indicated that formate dehydrogenase and terminal oxidase genes provided a fitness advantage in murine models of colitis. In vivo, formate served as electron donor in conjunction with oxygen as the terminal electron acceptor. This work identifies bacterial formate oxidation and oxygen respiration as metabolic signatures for inflammation-associated dysbiosis.
Asunto(s)
Disbiosis/microbiología , Escherichia coli/metabolismo , Formiatos/metabolismo , Inflamación/microbiología , Animales , Colitis/microbiología , Modelos Animales de Enfermedad , Femenino , Microbioma Gastrointestinal , Intestinos/microbiología , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Proteobacteria/metabolismoRESUMEN
Class-switch recombination (CSR) alters the Ig isotype to diversify antibody effector functions. IgD CSR is a rare event, and its regulation is poorly understood. We report that deficiency of 53BP1, a DNA damage-response protein, caused age-dependent overproduction of secreted IgD resulting from increased IgD CSR exclusively within B cells of mucosa-associated lymphoid tissues. IgD overproduction was dependent on activation-induced cytidine deaminase, hematopoietic MyD88 expression, and an intact microbiome, against which circulating IgD, but not IgM, was reactive. IgD CSR occurred via both alternative nonhomologous end-joining and homologous recombination pathways. Microbiota-dependent IgD CSR also was detected in nasal-associated lymphoid tissue of WT mice. These results identify a pathway, present in WT mice and hyperactivated in 53BP1-deficient mice, by which microbiota signal via Toll-like receptors to elicit IgD CSR.
Asunto(s)
Cambio de Clase de Inmunoglobulina , Inmunoglobulina D/inmunología , Tejido Linfoide/inmunología , Microbiota/inmunología , Membrana Mucosa/inmunología , Animales , Citidina Desaminasa/genética , Citidina Desaminasa/inmunología , Citidina Desaminasa/metabolismo , Reparación del ADN por Unión de Extremidades , Femenino , Inmunoglobulina D/genética , Inmunoglobulina D/metabolismo , Tejido Linfoide/metabolismo , Masculino , Ratones Endogámicos C57BL , Ratones Noqueados , Microbiota/genética , Membrana Mucosa/metabolismo , Factor 88 de Diferenciación Mieloide/genética , Factor 88 de Diferenciación Mieloide/inmunología , Factor 88 de Diferenciación Mieloide/metabolismo , Recombinación Genética , Proteína 1 de Unión al Supresor Tumoral P53/deficiencia , Proteína 1 de Unión al Supresor Tumoral P53/genética , Proteína 1 de Unión al Supresor Tumoral P53/inmunologíaRESUMEN
For all newborn mammals, mother's milk is the perfect nourishment, crucial for their postnatal development. Here we report that, unexpectedly, maternal western diet consumption in mice causes the production of toxic milk that contains excessive long chain and saturated fatty acids, which triggers ceramide accumulation and inflammation in the nursing neonates, manifested as alopecia. This neonatal toxicity requires Toll-like-receptors (TLR), but not gut microbiota, because TLR2/4 deletion or TLR4 inhibition confers resistance, whereas germ-free mice remain sensitive. These findings unravel maternal western diet-induced inflammatory milk secretion as a novel aspect of the metabolic syndrome at the maternal offspring interface.
Asunto(s)
Dieta/efectos adversos , Inflamación/patología , Leche/toxicidad , Madres , Receptor Toll-Like 2/metabolismo , Receptor Toll-Like 4/metabolismo , Mundo Occidental , Animales , Animales Recién Nacidos , Ceramidas/metabolismo , Ácidos Grasos/metabolismo , Femenino , Eliminación de Gen , Vida Libre de Gérmenes/efectos de los fármacos , Lactancia/efectos de los fármacos , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Leche/metabolismo , Embarazo , Receptor Toll-Like 4/antagonistas & inhibidoresRESUMEN
RIG-I-like receptors (RLRs) activate host innate immune responses against virus infection through recruiting the mitochondrial adaptor protein MAVS (also known as IPS1, VISA, or CARDIF). Here we show that MAVS also plays a pivotal role in maintaining intestinal homeostasis. We found that MAVS knockout mice developed more severe mortality and morbidity than WT animals in an experimental model of colitis. Bone marrow transplantation experiments revealed that MAVS in cells of nonhematopoietic origin plays a dominant role in the protection against colitis. Importantly, RNA species derived from intestinal commensal bacteria activate the RIG-I-MAVS pathway to induce the production of multiple cytokines and antimicrobial peptides, including IFN-ß and RegIIIγ. These results unveil a previously unexplored role of MAVS in monitoring intestinal commensal bacteria and maintaining tissue homeostasis.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/inmunología , Colitis/inmunología , Colitis/prevención & control , Proteínas Adaptadoras Transductoras de Señales/deficiencia , Proteínas Adaptadoras Transductoras de Señales/genética , Animales , Trasplante de Médula Ósea/inmunología , Colitis/inducido químicamente , Proteína 58 DEAD Box , ARN Helicasas DEAD-box/inmunología , Sulfato de Dextran/toxicidad , Modelos Animales de Enfermedad , Femenino , Inmunidad Innata , Intestinos/inmunología , Intestinos/microbiología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Factor 88 de Diferenciación Mieloide/deficiencia , Factor 88 de Diferenciación Mieloide/genética , Factor 88 de Diferenciación Mieloide/inmunología , ARN Bacteriano/inmunologíaRESUMEN
The mammalian gastrointestinal tract harbors thousands of bacterial species that include symbionts as well as potential pathogens. The immune responses that limit access of these bacteria to underlying tissue remain poorly defined. Here we show that γδ intraepithelial lymphocytes (γδ IEL) of the small intestine produce innate antimicrobial factors in response to resident bacterial "pathobionts" that penetrate the intestinal epithelium. γδ IEL activation was dependent on epithelial cell-intrinsic MyD88, suggesting that epithelial cells supply microbe-dependent cues to γδ IEL. Finally, γδ T cells protect against invasion of intestinal tissues by resident bacteria specifically during the first few hours after bacterial encounter, indicating that γδ IEL occupy a unique temporal niche among intestinal immune defenses. Thus, γδ IEL detect the presence of invading bacteria through cross-talk with neighboring epithelial cells and are an essential component of the hierarchy of immune defenses that maintain homeostasis with the intestinal microbiota.
Asunto(s)
Homeostasis/inmunología , Interacciones Huésped-Patógeno/inmunología , Mucosa Intestinal/inmunología , Linfocitos/inmunología , Receptores de Antígenos de Linfocitos T gamma-delta/fisiología , Animales , Bacterias/inmunología , Comunicación Celular/inmunología , Células Epiteliales , Inmunidad Innata , Metagenoma/inmunología , Ratones , Ratones NoqueadosRESUMEN
Toxoplasma gondii is a universally distributed pathogen that infects over one billion people worldwide. Host resistance to this protozoan parasite depends on a Th1 immune response with potent production of the cytokines interleukin-12 and interferon gamma. Although Toll-like receptor 11 (TLR11) plays a major role in controlling Th1 immunity to this pathogen in mice, this innate immune receptor is nonfunctional in humans, and the mechanisms of TLR11-independent sensing of T. gondii remain elusive. Here, we show that oral infection by T. gondii triggers a TLR11-independent but MyD88-dependent Th1 response that is impaired in TLR2xTLR4 double knockout and TLR9 single knockout mice. These mucosal innate and adaptive immune responses to T. gondii rely on the indirect stimulation of dendritic cells by normal gut microflora. Thus, our results reveal that gut commensal bacteria can serve as molecular adjuvants during parasitic infection, providing indirect immunostimulation that protects against T. gondii in the absence of TLR11.
Asunto(s)
Bacterias/inmunología , Células Dendríticas/inmunología , Tracto Gastrointestinal/microbiología , Toxoplasma/inmunología , Toxoplasmosis Animal/inmunología , Animales , Citocinas/biosíntesis , Humanos , Leucocitos Mononucleares/inmunología , Ratones , Ratones Noqueados , Factor 88 de Diferenciación Mieloide/deficiencia , Factor 88 de Diferenciación Mieloide/inmunología , Receptor Toll-Like 2/deficiencia , Receptor Toll-Like 2/inmunología , Receptor Toll-Like 4/deficiencia , Receptor Toll-Like 4/inmunología , Receptor Toll-Like 9/deficiencia , Receptor Toll-Like 9/inmunología , Toxoplasmosis Animal/parasitología , Toxoplasmosis Animal/patologíaRESUMEN
The intestinal mucosal surface is in direct contact with a vast beneficial microbiota. The symbiotic nature of this relationship is threatened when the surface epithelium is injured, yet little is known about how mucosal surfaces maintain homeostasis with commensal microbes following damage. Gammadelta intraepithelial lymphocytes (gammadelta IEL) reside at the gut epithelial surface, where they stimulate mucosal healing following acute injury. A genome-wide analysis of the gammadelta IEL response to dextran sulfate sodium-induced colonic damage revealed induction of a complex transcriptional program, including coordinate regulation of cytoprotective, immunomodulatory, and antibacterial factors. Studies in germfree mice demonstrated that commensal microbiota regulate key components of this transcriptional program, thus revealing a dialogue between commensal bacteria and gammadelta IEL in injured epithelia. Analysis of TCRdelta-deficient mice indicated that gammadelta T cells are essential for controlling mucosal penetration of commensal bacteria immediately following dextran sulfate sodium-induced damage, suggesting that a key function of gammadelta IEL is to maintain host-microbial homeostasis following acute mucosal injury. Taken together, these findings disclose a reciprocal relationship between gammadelta T cells and intestinal microbiota that promotes beneficial host-microbial relationships in the intestine.
Asunto(s)
Comunicación Celular/inmunología , Mucosa Intestinal/inmunología , Mucosa Intestinal/microbiología , Subgrupos Linfocitarios/inmunología , Subgrupos Linfocitarios/microbiología , Receptores de Antígenos de Linfocitos T gamma-delta/biosíntesis , Animales , Colon/efectos de los fármacos , Colon/inmunología , Colon/microbiología , Colon/patología , Sulfato de Dextran/toxicidad , Células Epiteliales/efectos de los fármacos , Células Epiteliales/inmunología , Células Epiteliales/microbiología , Células Epiteliales/patología , Homeostasis/efectos de los fármacos , Homeostasis/inmunología , Mucosa Intestinal/efectos de los fármacos , Mucosa Intestinal/patología , Subgrupos Linfocitarios/efectos de los fármacos , Subgrupos Linfocitarios/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Análisis de Secuencia por Matrices de Oligonucleótidos , Receptores de Antígenos de Linfocitos T gamma-delta/deficiencia , Receptores de Antígenos de Linfocitos T gamma-delta/genéticaRESUMEN
The intestinal epithelium is in direct contact with a vast microbiota, yet little is known about how epithelial cells defend the host against the heavy bacterial load. To address this question we studied Paneth cells, a key small intestinal epithelial lineage. We found that Paneth cells directly sense enteric bacteria through cell-autonomous MyD88-dependent toll-like receptor (TLR) activation, triggering expression of multiple antimicrobial factors. Paneth cells were essential for controlling intestinal barrier penetration by commensal and pathogenic bacteria. Furthermore, Paneth cell-intrinsic MyD88 signaling limited bacterial penetration of host tissues, revealing a role for epithelial MyD88 in maintaining intestinal homeostasis. Our findings establish that gut epithelia actively sense enteric bacteria and play an essential role in maintaining host-microbial homeostasis at the mucosal interface.