RESUMEN
The disease severity of Entamoeba histolytica infection ranges from asymptomatic to life-threatening. Recent human and animal data implicate the gut microbiome as a modifier of E. histolytica virulence. Here we have explored the association of the microbiome with susceptibility to amebiasis in infants and in the mouse model of amebic colitis. Dysbiosis occurred symptomatic E. histolytica infection in children, as evidenced by a lower Shannon diversity index of the gut microbiota. To test if dysbiosis was a cause of susceptibility, wild type C57BL/6 mice (which are innately resistant to E. histiolytica infection) were treated with antibiotics prior to cecal challenge with E. histolytica. Compared with untreated mice, antibiotic pre-treated mice had more severe colitis and delayed clearance of E. histolytica. Gut IL-25 and mucus protein Muc2, both shown to provide innate immunity in the mouse model of amebic colitis, were lower in antibiotic pre-treated mice. Moreover, dysbiotic mice had fewer cecal neutrophils and myeloperoxidase activity. Paradoxically, the neutrophil chemoattractant chemokines CXCL1 and CXCL2, as well as IL-1ß, were higher in the colon of mice with antibiotic-induced dysbiosis. Neutrophils from antibiotic pre-treated mice had diminished surface expression of the chemokine receptor CXCR2, potentially explaining their inability to migrate to the site of infection. Blockade of CXCR2 increased susceptibility of control non-antibiotic treated mice to amebiasis. In conclusion, dysbiosis increased the severity of amebic colitis due to decreased neutrophil recruitment to the gut, which was due in part to decreased surface expression on neutrophils of CXCR2.
Asunto(s)
Disentería Amebiana/microbiología , Microbiota/inmunología , Infiltración Neutrófila/inmunología , Animales , Preescolar , Modelos Animales de Enfermedad , Disentería Amebiana/inmunología , Entamoeba histolytica , Heces/microbiología , Citometría de Flujo , Humanos , Lactante , Ratones , Ratones Endogámicos C57BL , Reacción en Cadena en Tiempo Real de la Polimerasa , Receptores de Interleucina-8B/inmunologíaRESUMEN
Parasitic protozoan infections represent a major health burden in the developing world and contribute significantly to morbidity and mortality. These infections are often associated with considerable variability in clinical presentation. An emerging body of work suggests that the intestinal microbiota may help to explain some of these differences in disease expression. The objective of this minireview is to synthesize recent progress in this rapidly advancing field. Studies of humans and animals and in vitro studies of the contribution of the intestinal microbiota to infectious disease are discussed. We hope to provide an understanding of the human-protozoal pathogen-microbiome interaction and to speculate on how that might be leveraged for treatment.
Asunto(s)
Microbioma Gastrointestinal , Interacciones Huésped-Parásitos , Parásitos/fisiología , Animales , Humanos , Parásitos/patogenicidad , Infecciones por Protozoos/terapiaRESUMEN
BACKGROUND: As the global polio eradication initiative prepares to cease use of oral polio vaccine (OPV) in 2020, there is increasing interest in understanding if oral vaccination provides non-specific immunity to other infections so that the consequences of this transition can be effectively planned for and mitigated. METHODS: Data were collected from infants in an urban slum in Bangladesh (Mirpur, Dhaka) as part of the performance of rotavirus and oral polio vaccines in developing countries (PROVIDE) study. Following vaccination with trivalent oral polio vaccine (tOPV) at 6, 10, and 14 weeks, infants were randomly assigned to receive tOPV (n = 315) or inactivated polio vaccine (IPV) (n = 299) at 39 weeks. Episodes of diarrhea were documented through clinic visits and twice-weekly house visits through 52 weeks. In sum, 14 pathogens associated with diarrhea were analyzed with TaqMan Array Cards. RESULTS: Although the proportion of children experiencing diarrhea was not different between the tOPV and IPV groups (P = .18), the number of days with diarrhea (P = .0037) and the number of separate diarrheal episodes (P = .054) trended lower in the OPV arm. Etiological analysis revealed that male tOPV recipients were less likely to have diarrhea of bacterial etiology (P = .0099) compared to male IPV recipients but equally likely to experience diarrhea due to viruses (P = .57) or protozoa (P = .14). Among the 6 bacterial enteric pathogens tested, only Campylobacter jejuni/coli detection was significantly reduced in the OPV arm (P = .0048). CONCLUSIONS: Our results suggest that OPV may cause nonspecific reductions in mortality, as has been studied elsewhere, by reducing etiology-specific diarrheal burden. This is likely driven by reductions in bacterial diarrhea. Further study of nonspecific OPV effects before global cessation is supported. CLINICAL TRIALS REGISTRATION: NCT01375647.
Asunto(s)
Diarrea , Vacuna Antipolio Oral/administración & dosificación , Vacuna Antipolio Oral/uso terapéutico , Bangladesh/epidemiología , Protección Cruzada , Diarrea/epidemiología , Diarrea/microbiología , Diarrea/virología , Heces/virología , Femenino , Humanos , Lactante , MasculinoRESUMEN
BACKGROUND: An estimated 1 million children die each year before their fifth birthday from diarrhea. Previous population-based surveys of pediatric diarrheal diseases have identified the protozoan parasite Entamoeba histolytica, the etiological agent of amebiasis, as one of the causes of moderate-to-severe diarrhea in sub-Saharan Africa and South Asia. METHODS: We prospectively studied the natural history of E. histolytica colonization and diarrhea among infants in an urban slum of Dhaka, Bangladesh. RESULTS: Approximately 80% of children were infected with E. histolytica by the age of 2 years. Fecal anti-galactose/N-acetylgalactosamine lectin immunoglobulin A was associated with protection from reinfection, while a high parasite burden and expansion of the Prevotella copri level was associated with diarrhea. CONCLUSIONS: E. histolytica infection was prevalent in this population, with most infections asymptomatic and diarrhea associated with both the amount of parasite and the composition of the microbiota.
Asunto(s)
Anticuerpos Antiprotozoarios/inmunología , Diarrea Infantil/etiología , Entamoeba histolytica/inmunología , Entamebiasis/complicaciones , Microbioma Gastrointestinal , Inmunoglobulina A/inmunología , Animales , Bangladesh/epidemiología , Estudios de Cohortes , Entamebiasis/parasitología , Heces/parasitología , Femenino , Estudios de Seguimiento , Humanos , Lactante , Lectinas/inmunología , Estudios Longitudinales , Masculino , Áreas de Pobreza , Prevalencia , Estudios ProspectivosRESUMEN
Clostridium difficile is a major, life-threatening hospital-acquired pathogen that causes mild to severe colitis in infected individuals. The tissue destruction and inflammation which characterize C. difficile infection (CDI) are primarily due to the Rho-glucosylating toxins A and B. These toxins cause epithelial cell death and induce robust inflammatory signaling by activating the transcription factor NF-κB, leading to chemokine and cytokine secretion. The toxins also activate the inflammasome complex, which leads to secretion of the pyrogenic cytokine IL-1ß. In this study, we utilized glucosylation-deficient toxin A to show that activation of the inflammasome by this toxin is dependent on Rho glucosylation, confirming similar findings reported for toxin B. We also demonstrated that tissue destruction and in vivo inflammatory cytokine production are critically dependent on the enzymatic activity of toxin A, suggesting that inhibiting toxin glucosyltransferase activity may be effective in combating this refractory disease.
Asunto(s)
Toxinas Bacterianas/inmunología , Toxinas Bacterianas/metabolismo , Clostridioides difficile/inmunología , Clostridioides difficile/metabolismo , Infecciones por Clostridium/metabolismo , Infecciones por Clostridium/microbiología , Enterotoxinas/inmunología , Enterotoxinas/metabolismo , Inmunidad Innata , Animales , Toxinas Bacterianas/genética , Biomarcadores , Infecciones por Clostridium/patología , Citocinas/metabolismo , Enterotoxinas/genética , Glicosilación , Mediadores de Inflamación/metabolismo , Masculino , Ratones , FN-kappa B/metabolismoRESUMEN
Intestinal segmented filamentous bacteria (SFB) protect from ameba infection, and protection is transferable with bone marrow dendritic cells (BMDCs). SFB cause an increase in serum amyloid A (SAA), suggesting that SAA might mediate SFB's effects on BMDCs. Here we further explored the role of bone marrow in SFB-mediated protection. Transient gut colonization with SFB or SAA administration alone transiently increased the H3K27 histone demethylase Jmjd3, persistently increased bone marrow Csf2ra expression and granulocyte monocyte precursors (GMPs), and protected from ameba infection. Pharmacologic inhibition of Jmjd3 H3K27 demethylase activity during SAA treatment or blockade of granulocyte-macrophage colony-stimulating factor (GM-CSF) signaling in SFB-colonized mice prevented GMP expansion, decreased gut neutrophils, and blocked protection from ameba infection. These results indicate that alteration of the microbiota and systemic exposure to SAA can influence myelopoiesis and susceptibility to amebiasis via epigenetic mechanisms. Gut microbiota-marrow communication is a previously unrecognized mechanism of innate protection from infection.
Asunto(s)
Células de la Médula Ósea/citología , Entamoeba histolytica/fisiología , Entamebiasis/fisiopatología , Tracto Gastrointestinal/microbiología , Factor Estimulante de Colonias de Granulocitos y Macrófagos/fisiología , Proteína Amiloide A Sérica/fisiología , Animales , Bacterias , Médula Ósea/metabolismo , Células de la Médula Ósea/fisiología , Células Dendríticas/metabolismo , Modelos Animales de Enfermedad , Células Progenitoras de Granulocitos y Macrófagos , Histona Demetilasas con Dominio de Jumonji/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Receptores de Factor Estimulante de Colonias de Granulocitos y Macrófagos/metabolismoRESUMEN
Amixicile shows efficacy in the treatment of Clostridium difficile infections (CDI) in a mouse model, with no recurrence of CDI. Since amixicile selectively inhibits the action of a B vitamin (thiamine pyrophosphate) cofactor of pyruvate:ferredoxin oxidoreductase (PFOR), it may both escape mutation-based drug resistance and spare beneficial probiotic gut bacteria that do not express this enzyme. Amixicile is a water-soluble derivative of nitazoxanide (NTZ), an antiparasitic therapeutic that also shows efficacy against CDI in humans. In comparative studies, amixicile showed no toxicity to hepatocytes at 200 µM (NTZ was toxic above 10 µM); was not metabolized by human, dog, or rat liver microsomes; showed equivalence or superiority to NTZ in cytochrome P450 assays; and did not activate efflux pumps (breast cancer resistance protein, P glycoprotein). A maximum dose (300 mg/kg) of amixicile given by the oral or intraperitoneal route was well tolerated by mice and rats. Plasma exposure (rats) based on the area under the plasma concentration-time curve was 79.3 h · µg/ml (30 mg/kg dose) to 328 h · µg/ml (100 mg/kg dose), the maximum concentration of the drug in serum was 20 µg/ml, the time to the maximum concentration of the drug in serum was 0.5 to 1 h, and the half-life was 5.6 h. Amixicile did not concentrate in mouse feces or adversely affect gut populations of Bacteroides species, Firmicutes, segmented filamentous bacteria, or Lactobacillus species. Systemic bioavailability was demonstrated through eradication of Helicobacter pylori in a mouse infection model. In summary, the efficacy of amixicile in treating CDI and other infections, together with low toxicity, an absence of mutation-based drug resistance, and excellent drug metabolism and pharmacokinetic metrics, suggests a potential for broad application in the treatment of infections caused by PFOR-expressing microbial pathogens in addition to CDI.
Asunto(s)
Antibacterianos/farmacocinética , Benzamidas/farmacocinética , Infecciones por Helicobacter/tratamiento farmacológico , Helicobacter pylori/efectos de los fármacos , Tiazoles/farmacocinética , Animales , Antibacterianos/sangre , Antibacterianos/farmacología , Área Bajo la Curva , Benzamidas/sangre , Benzamidas/farmacología , Disponibilidad Biológica , Línea Celular , Supervivencia Celular/efectos de los fármacos , Perros , Evaluación Preclínica de Medicamentos , Semivida , Infecciones por Helicobacter/sangre , Infecciones por Helicobacter/microbiología , Helicobacter pylori/crecimiento & desarrollo , Helicobacter pylori/metabolismo , Hepatocitos/citología , Hepatocitos/efectos de los fármacos , Hepatocitos/metabolismo , Humanos , Masculino , Pruebas de Sensibilidad Microbiana , Microbiota/efectos de los fármacos , Microbiota/fisiología , Microsomas Hepáticos/efectos de los fármacos , Piruvato-Sintasa/metabolismo , Ratas , Tiamina Pirofosfato/metabolismo , Tiazoles/sangre , Tiazoles/farmacologíaRESUMEN
Diarrheal diseases with infectious etiology remain a major cause of death globally, particularly in low-income countries. Entamoeba histolytica is a pathogenic protozoan parasite that is the causative agent of amebiasis. Amebiasis has a wide presentation in clinical severity with many factors, including the bacterial microbiota, contributing to this variation. The innate immune response also plays a critical role in regulating the severity of E. histolytica infection, with neutrophils reported to have a protective role. Despite this, the precise mechanism of how neutrophils mediate amebic killing is poorly understood. Thus, modern platforms that allow for inquiry of granulocyte-ameba interactions will increase our understanding of this disease. Herein, we describe an assay for neutrophil killing of E. histolytica by utilizing high-dimensional spectral flow cytometry. Neutrophils were isolated from wild-type 5-week-old C57BL/6 mice and co-cultured with E. histolytica at various multiplicity of infections (MOIs). After co-culture, neutrophils and E. histolytica were stained for spectral flow cytometry. Cell populations were identified using surface markers and fluorescence minus one (FMO) controls. We have previously shown that animals colonized with a component of the human microbiota, Clostridium scindens, were protected from E. histolytica. This protection was associated with elevated neutrophil count. Here, we explored amebic killing capacity and observed that neutrophils from animals with C. scindens possessed heightened amebic killing compared with controls. Thus, this study establishes a novel platform that can provide an in-depth analysis of granulocyte-parasite interactions in various contexts, including during alteration of the intestinal microbiota.IMPORTANCEThe tools for studying host immune cell-E. histolytica interactions are limited. Factors, such as parasite heterogeneity, infectivity, and difficulties with culture systems and animal models, make interrogation of these interactions challenging. Thus, Entamoeba researchers can benefit from next-generation models that allow for the analysis of both host and parasite cells. Here, we demonstrate the use of a novel platform that allows for the determination of parasite-host cell interactions and customizable high-dimensional phenotyping of both populations. Indeed, spectral flow cytometry can approach >40 markers on a single panel and can be paired with custom-developed parasite antibodies that can be conjugated to fluorochromes via commercially available kits. This platform affords researchers the capability to test highly precise hypotheses regarding host-parasite interactions.
Asunto(s)
Entamoeba histolytica , Citometría de Flujo , Ratones Endogámicos C57BL , Neutrófilos , Animales , Neutrófilos/inmunología , Ratones , Entamoeba histolytica/inmunología , Interacciones Huésped-Parásitos/inmunología , Humanos , Entamebiasis/inmunología , Entamebiasis/parasitologíaRESUMEN
Metabolic products of the microbiota can alter hematopoiesis. However, the contribution and site of action of bile acids is poorly understood. Here, we demonstrate that the secondary bile acids, deoxycholic acid (DCA) and lithocholic acid (LCA), increase bone marrow myelopoiesis. Treatment of bone marrow cells with DCA and LCA preferentially expanded immunophenotypic and functional colony-forming unit-granulocyte and macrophage (CFU-GM) granulocyte-monocyte progenitors (GMPs). DCA treatment of sorted hematopoietic stem and progenitor cells (HSPCs) increased CFU-GMs, indicating that direct exposure of HSPCs to DCA sufficed to increase GMPs. The vitamin D receptor (VDR) was required for the DCA-induced increase in CFU-GMs and GMPs. Single-cell RNA sequencing revealed that DCA significantly upregulated genes associated with myeloid differentiation and proliferation in GMPs. The action of DCA on HSPCs to expand GMPs in a VDR-dependent manner suggests microbiome-host interactions could directly affect bone marrow hematopoiesis and potentially the severity of infectious and inflammatory disease.
Asunto(s)
Ácidos y Sales Biliares , Mielopoyesis , Receptores de Calcitriol , Ácidos y Sales Biliares/metabolismo , Células Progenitoras Mieloides , Receptores de Calcitriol/genética , Receptores de Calcitriol/metabolismoRESUMEN
Entamoeba histolytica is a pathogenic protozoan parasite that causes intestinal colitis, diarrhea, and in some cases, liver abscess. Through transcriptomics analysis, we observed that E. histolytica infection was associated with increased expression of IL-33 mRNA in both the human and murine colon. IL-33, the IL-1 family cytokine, is released after cell injury to alert the immune system of tissue damage. Treatment with recombinant IL-33 protected mice from amebic infection and intestinal tissue damage; moreover, blocking IL-33 signaling made mice more susceptible to amebiasis. IL-33 limited the recruitment of inflammatory immune cells and decreased the pro-inflammatory cytokine IL-6 in the cecum. Type 2 immune responses were upregulated by IL-33 treatment during amebic infection. Interestingly, administration of IL-33 protected RAG2-/- mice but not RAG2-/-γc-/- mice, demonstrating that IL-33-mediated protection required the presence of innate lymphoid cells (ILCs). IL-33 induced recruitment of ILC2 but not ILC1 and ILC3 in RAG2-/- mice. At baseline and after amebic infection, there was a significantly higher IL13+ILC2s in C57BL/J mice, which are naturally resistant to amebiasis, than CBA/J mice. Adoptive transfer of ILC2s to RAG2-/-γc-/- mice restored IL-33-mediated protection. These data reveal that the IL-33-ILC2 pathway is an important host defense mechanism against amebic colitis.
Asunto(s)
Colon/fisiología , Disentería Amebiana/inmunología , Entamoeba histolytica/fisiología , Entamebiasis/inmunología , Interleucina-33/genética , Linfocitos/inmunología , ARN Mensajero/genética , Animales , Movimiento Celular , Colon/parasitología , Proteínas de Unión al ADN/genética , Resistencia a la Enfermedad , Perfilación de la Expresión Génica , Antecedentes Genéticos , Humanos , Inmunidad Innata , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos CBA , Transducción de Señal , Células TH1/inmunología , Células Th2/inmunologíaRESUMEN
Amebiasis is a neglected tropical disease caused by Entamoeba histolytica. Although the disease burden varies geographically, amebiasis is estimated to account for some 55,000 deaths and millions of infections globally per year. Children and travelers are among the groups with the greatest risk of infection. There are currently no licensed vaccines for prevention of amebiasis, although key immune correlates for protection have been proposed from observational studies in humans. We previously described the development of a liposomal adjuvant formulation containing two synthetic TLR ligands (GLA and 3M-052) that enhanced antigen-specific fecal IgA, serum IgG2a, a mixed IFNγ and IL-17A cytokine profile from splenocytes, and protective efficacy following intranasal administration with the LecA antigen. By applying a statistical design of experiments (DOE) and desirability function approach, we now describe the optimization of the dose of each vaccine formulation component (LecA, GLA, 3M-052, and liposome) as well as the excipient composition (acyl chain length and saturation; PEGylated lipid:phospholipid ratio; and presence of antioxidant, tonicity, or viscosity agents) to maximize desired immunogenicity characteristics while maintaining physicochemical stability. This DOE/desirability index approach led to the identification of a lead candidate composition that demonstrated immune response durability and protective efficacy in the mouse model, as well as an assessment of the impact of each active vaccine formulation component on protection. Thus, we demonstrate that both GLA and 3M-052 are required for statistically significant protective efficacy. We also show that immunogenicity and efficacy results differ in female vs male mice, and the differences appear to be at least partly associated with adjuvant formulation composition.
Asunto(s)
Antígenos de Protozoos/inmunología , Entamoeba histolytica/inmunología , Entamebiasis/inmunología , Entamebiasis/prevención & control , Vacunas Antiprotozoos/inmunología , Adyuvantes Inmunológicos/química , Administración Intranasal , Animales , Anticuerpos Antiprotozoarios/sangre , Anticuerpos Antiprotozoarios/inmunología , Fenómenos Químicos , Citocinas/metabolismo , Composición de Medicamentos , Entamebiasis/parasitología , Ensayo de Inmunoadsorción Enzimática , Humanos , Inmunogenicidad Vacunal , Inmunoglobulina G/inmunología , Liposomas , Ratones , Vacunas Antiprotozoos/administración & dosificación , Vacunas Antiprotozoos/química , VacunaciónRESUMEN
Immune dysregulation is characteristic of the more severe stages of SARS-CoV-2 infection. Understanding the mechanisms by which the immune system contributes to COVID-19 severity may open new avenues to treatment. Here, we report that elevated IL-13 was associated with the need for mechanical ventilation in 2 independent patient cohorts. In addition, patients who acquired COVID-19 while prescribed Dupilumab, a mAb that blocks IL-13 and IL-4 signaling, had less severe disease. In SARS-CoV-2-infected mice, IL-13 neutralization reduced death and disease severity without affecting viral load, demonstrating an immunopathogenic role for this cytokine. Following anti-IL-13 treatment in infected mice, hyaluronan synthase 1 (Has1) was the most downregulated gene, and accumulation of the hyaluronan (HA) polysaccharide was decreased in the lung. In patients with COVID-19, HA was increased in the lungs and plasma. Blockade of the HA receptor, CD44, reduced mortality in infected mice, supporting the importance of HA as a pathogenic mediator. Finally, HA was directly induced in the lungs of mice by administration of IL-13, indicating a new role for IL-13 in lung disease. Understanding the role of IL-13 and HA has important implications for therapy of COVID-19 and, potentially, other pulmonary diseases. IL-13 levels were elevated in patients with severe COVID-19. In a mouse model of the disease, IL-13 neutralization reduced the disease and decreased lung HA deposition. Administration of IL-13-induced HA in the lung. Blockade of the HA receptor CD44 prevented mortality, highlighting a potentially novel mechanism for IL-13-mediated HA synthesis in pulmonary pathology.
Asunto(s)
COVID-19/inmunología , Interleucina-13/inmunología , SARS-CoV-2/inmunología , Animales , COVID-19/sangre , COVID-19/patología , COVID-19/terapia , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Femenino , Humanos , Interleucina-13/sangre , Pulmón/inmunología , Pulmón/patología , Masculino , Ratones , Ratones Endogámicos C57BL , Índice de Severidad de la EnfermedadRESUMEN
Immune dysregulation is characteristic of the more severe stages of SARS-CoV-2 infection. Understanding the mechanisms by which the immune system contributes to COVID-19 severity may open new avenues to treatment. Here we report that elevated interleukin-13 (IL-13) was associated with the need for mechanical ventilation in two independent patient cohorts. In addition, patients who acquired COVID-19 while prescribed Dupilumab had less severe disease. In SARS-CoV-2 infected mice, IL-13 neutralization reduced death and disease severity without affecting viral load, demonstrating an immunopathogenic role for this cytokine. Following anti-IL-13 treatment in infected mice, in the lung, hyaluronan synthase 1 (Has1) was the most downregulated gene and hyaluronan accumulation was decreased. Blockade of the hyaluronan receptor, CD44, reduced mortality in infected mice, supporting the importance of hyaluronan as a pathogenic mediator, and indicating a new role for IL-13 in lung disease. Understanding the role of IL-13 and hyaluronan has important implications for therapy of COVID-19 and potentially other pulmonary diseases.
RESUMEN
Murine models of SARS-CoV-2 infection are critical for elucidating the biological pathways underlying COVID-19. Because human angiotensin-converting enzyme 2 (ACE2) is the receptor for SARS-CoV-2, mice expressing the human ACE2 gene have shown promise as a potential model for COVID-19. Five mice from the transgenic mouse strain K18-hACE2 were intranasally inoculated with SARS-CoV-2 Hong Kong/VM20001061/2020. Mice were followed twice daily for 5 days and scored for weight loss and clinical symptoms. Infected mice did not exhibit any signs of infection until day 4, when no other obvious clinical symptoms other than weight loss were observed. By day 5, all infected mice had lost around 10% of their original body weight but exhibited variable clinical symptoms. All infected mice showed high viral titers in the lungs as well as altered lung histology associated with proteinaceous debris in the alveolar space, interstitial inflammatory cell infiltration, and alveolar septal thickening. Overall, these results show that the K18-hACE2 transgenic background can be used to establish symptomatic SARS-CoV-2 infection and can be a useful mouse model for COVID-19.
Asunto(s)
Betacoronavirus , Infecciones por Coronavirus/etiología , Modelos Animales de Enfermedad , Queratina-18/genética , Peptidil-Dipeptidasa A/genética , Neumonía Viral/etiología , Enzima Convertidora de Angiotensina 2 , Animales , COVID-19 , Humanos , Masculino , Ratones , Ratones Transgénicos , Pandemias , SARS-CoV-2RESUMEN
The microbiome provides resistance to infection. However, the underlying mechanisms are poorly understood. We demonstrate that colonization with the intestinal bacterium Clostridium scindens protects from Entamoeba histolytica colitis via innate immunity. Introduction of C. scindens into the gut microbiota epigenetically altered and expanded bone marrow granulocyte-monocyte progenitors (GMPs) and resulted in increased intestinal neutrophils with subsequent challenge with E. histolytica. Introduction of C. scindens alone was sufficient to expand GMPs in gnotobiotic mice. Adoptive transfer of bone marrow from C. scindens-colonized mice into naive mice protected against amebic colitis and increased intestinal neutrophils. Children without E. histolytica diarrhea also had a higher abundance of Lachnoclostridia. Lachnoclostridia C. scindens can metabolize the bile salt cholate, so we measured deoxycholate and discovered that it was increased in the sera of C. scindens-colonized specific pathogen-free and gnotobiotic mice, as well as in children protected from amebiasis. Administration of deoxycholate alone increased GMPs and provided protection from amebiasis. We elucidated a mechanism by which C. scindens and the microbially metabolized bile salt deoxycholic acid alter hematopoietic precursors and provide innate protection from later infection with E. histolytica.
Asunto(s)
Médula Ósea/inmunología , Clostridiales/inmunología , Disentería Amebiana/inmunología , Entamoeba histolytica/inmunología , Microbioma Gastrointestinal/inmunología , Animales , Médula Ósea/patología , Modelos Animales de Enfermedad , Susceptibilidad a Enfermedades/inmunología , Susceptibilidad a Enfermedades/microbiología , Disentería Amebiana/microbiología , Disentería Amebiana/patología , Humanos , Intestinos/inmunología , Intestinos/microbiología , Intestinos/patología , RatonesRESUMEN
Giardia lamblia is a common intestinal parasitic infection that although often acutely asymptomatic, is associated with debilitating chronic intestinal and extra-intestinal sequelae. In previously healthy adults, a primary sporadic Giardia infection can lead to gut dysfunction and fatigue. These symptoms correlate with markers of inflammation that persist well after the infection is cleared. In contrast, in endemic settings, first exposure occurs in children who are frequently malnourished and also co-infected with other enteropathogens. In these children, Giardia rarely causes symptoms and associates with several decreased markers of inflammation. Mechanisms underlying these disparate and potentially enduring outcomes following Giardia infection are not presently well understood. A body of work suggests that the outcome of experimental Giardia infection is influenced by the nutritional status of the host. Here, we explore the consequences of experimental Giardia infection under conditions of protein sufficiency or deficiency on cytokine responses of ex vivo bone marrow derived dendritic cells (BMDCs) to endotoxin stimulation. We show that BMDCs from Giardia- challenged mice on a protein sufficient diet produce more IL-23 when compared to uninfected controls whereas BMDCs from Giardia challenged mice fed a protein deficient diet do not. Further, in vivo co-infection with Giardia attenuates robust IL-23 responses in endotoxin-stimulated BMDCs from protein deficient mice harboring enteroaggregative Escherichia coli. These results suggest that intestinal Giardia infection may have extra-intestinal effects on BMDC inflammatory cytokine production in a diet dependent manner, and that Giardia may influence the severity of the innate immune response to other enteropathogens. This work supports recent findings that intestinal microbial exposure may have lasting influences on systemic inflammatory responses, and may provide better understanding of potential mechanisms of post-infectious sequelae and clinical variation during Giardia and enteropathogen co-infection.
Asunto(s)
Citocinas/inmunología , Células Dendríticas/inmunología , Dieta , Endotoxinas/farmacología , Giardiasis/inmunología , Animales , Células de la Médula Ósea/inmunología , Escherichia coli/inmunología , Giardia , Inmunidad Innata , Interleucina-23/inmunología , Mucosa Intestinal/inmunología , Mucosa Intestinal/parasitología , Masculino , Ratones , Ratones Endogámicos C57BL , Deficiencia de Proteína/inmunologíaRESUMEN
The parasite Entamoeba histolytica is a cause of diarrhea in infants in low-income countries. Previously, it was shown that tumor necrosis factor alpha (TNF-α) production was associated with increased risk of E. histolytica diarrhea in children. Interleukin-25 (IL-25) is a cytokine that is produced by intestinal epithelial cells that has a role in maintenance of gut barrier function and inhibition of TNF-α production. IL-25 expression was decreased in humans and in the mouse model of amebic colitis. Repletion of IL-25 blocked E. histolytica infection and barrier disruption in mice, increased gut eosinophils, and suppressed colonic TNF-α. Depletion of eosinophils with anti-Siglec-F antibody prevented IL-25-mediated protection. In contrast, depletion of TNF-α resulted in resistance to amebic infection. We concluded that IL-25 provides protection from amebiasis, which is dependent upon intestinal eosinophils and suppression of TNF-α.IMPORTANCE The intestinal epithelial barrier is important for protection from intestinal amebiasis. We discovered that the intestinal epithelial cytokine IL-25 was suppressed during amebic colitis in humans and that protection could be restored in the mouse model by IL-25 administration. IL-25 acted via eosinophils and suppressed TNF-α. This work illustrates a previously unrecognized pathway of innate mucosal immune response.
Asunto(s)
Disentería Amebiana/inmunología , Entamoeba histolytica/inmunología , Eosinófilos/inmunología , Interleucina-17/metabolismo , Factor de Necrosis Tumoral alfa/metabolismo , Animales , Modelos Animales de Enfermedad , Humanos , Interleucinas/metabolismo , RatonesRESUMEN
Entamoeba histolytica, the etiological agent of amebiasis, is a significant cause of pediatric diarrhea in South Asia and sub-Saharan Africa. The clinical outcome of an E. histolytica exposure varies enormously and can present as diarrhea, dysentery, or amebic liver abscess. Host and parasite factors likely contribute to the outcome of infection with the parasite, but do not explain the wide variation in presentation of disease. This suggests that other environmental factors affect disease. An emerging body of work suggests that the host intestinal bacterial microbiome may have a significant influence on the development and outcome of amebiasis.
RESUMEN
The intestinal surface is directly exposed to both commensal microorganisms as well as pathogens with a single layer of epithelium separating luminal microorganisms from internal tissues. Antimicrobial peptides play a crucial role in allowing epithelial cells to contain in the lumen beneficial and pathogenic microorganisms. The commensal dependent, epithelial produced, Th2 cytokine IL-25 can induce IL-13 and potentially the antimicrobial peptide angiogenin-4. Here we show that IL-13 downstream of IL-25 is required to induce angiogenin-4. IL-25 mediated induction of angiogenin-4 is furthermore not dependent on IL-22 or IL-17.
Asunto(s)
Células Epiteliales/metabolismo , Regulación de la Expresión Génica/efectos de los fármacos , Interleucina-13/metabolismo , Interleucinas/farmacología , Mucosa Intestinal/metabolismo , Ribonucleasa Pancreática/metabolismo , Animales , Western Blotting , Células Cultivadas , Células Epiteliales/citología , Células Epiteliales/efectos de los fármacos , Técnicas para Inmunoenzimas , Interleucina-13/genética , Mucosa Intestinal/citología , Mucosa Intestinal/efectos de los fármacos , Masculino , Ratones , Ratones Endogámicos CBA , ARN Mensajero/genética , Reacción en Cadena en Tiempo Real de la Polimerasa , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Ribonucleasa Pancreática/genéticaRESUMEN
BACKGROUND: Environmental factors that influence wheezing in early childhood in the developing world are not well understood and may be useful in predicting respiratory outcomes. Therefore, our objective was to determine the factors that can predict wheezing. METHODS: Children from Dhaka, Bangladesh were recruited at birth and episodes of wheezing were measured alongside nutritional, immunological and socioeconomic factors over a one-year period. Poisson Regression with variable selection was utilized to determine what factors were associated with wheezing. RESULTS: Elevated serum IL-10 (rate ratio (RR) = 1.51, 95% confidence interval (CI): 1.22-1.87), IL-1ß (RR = 1.55, 95% CI: 1.26-1.93) C-reactive protein (CRP) (RR = 1.41, 95% CI: 1.03-1.93) in early life, and male gender (RR = 1.52, 95% CI: 1.27-1.82) predicted increased wheezing episodes. Conversely, increased fecal alpha-1-antitrypsin (RR = 0.87, 95% CI: 0.76-1.00) and family income (RR = 0.98, 95% CI: 0.97-0.99) were associated with a decreased number of episodes of wheezing. CONCLUSIONS: Systemic inflammation early in life, poverty, and male sex placed infants at risk of more episodes of wheezing during their first year of life. These results support the hypothesis that there is a link between inflammation in infancy and the development of respiratory illness later in life and provide specific biomarkers that can predict wheezing in a low-income country.