RESUMO
Iron deficiency is the number one nutritional problem worldwide. Iron uptake is regulated at the intestine and is highly influenced by the gut microbiome. Blood from the intestines drains directly into the liver, informing iron status and gut microbiota status. Changes in either iron or the microbiome are tightly correlated with the development of metabolic dysfunction-associated steatotic liver disease (MASLD). To investigate the underlying mechanisms of the development of MASLD that connect altered iron metabolism and gut microbiota, we compared specific pathogen free (SPF) or germ-free (GF) mice, fed a normal or low-iron diet. SPF mice on a low-iron diet showed reduced serum triglycerides and MASLD. In contrast, GF low-iron diet-fed mice showed increased serum triglycerides and did not develop hepatic steatosis. SPF mice showed significant changes in liver lipid metabolism and increased insulin resistance that was dependent upon the presence of the gut microbiota. We report that total body loss of mitochondrial iron importer Mitoferrin2 (Mfrn2-/-) exacerbated the development of MASLD on a low-iron diet with significant lipid metabolism alterations. Our study demonstrates a clear contribution of the gut microbiome, dietary iron, and Mfrn2 in the development of MASLD and metabolic syndrome.
Assuntos
Microbioma Gastrointestinal , Fígado , Animais , Feminino , Masculino , Camundongos , Fígado Gorduroso/etiologia , Resistência à Insulina , Ferro/metabolismo , Deficiências de Ferro , Ferro da Dieta/administração & dosagem , Metabolismo dos Lipídeos , Fígado/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mitocôndrias/metabolismo , Proteínas Mitocondriais/metabolismo , Triglicerídeos/sangueRESUMO
Multiple neurological disorders are associated with gastrointestinal (GI) symptoms, including autism spectrum disorder (ASD). However, it is unclear whether GI distress itself can modify aspects of behavior. Here, we show that mice that experience repeated colitis have impaired active social engagement, as measured by interactions with a foreign mouse, even though signs of colitis were no longer present. We then tested the hypothesis that individuals with ASD harbor a microbiota that might differentially influence GI health by performing microbiota transplantation studies into male germfree animals, followed by induction of colitis. Animals that harbor a microbiota from ASD individuals have worsened gut phenotypes when compared to animals colonized with microbiotas from familial neurotypical (NT) controls. We identify the enrichment of Blautia species in all familial NT controls and observe an association between elevated abundance of Bacteroides uniformis and reductions in intestinal injury. Oral treatment with either of these microbes reduces colon injury in mice. Finally, provision of a Blautia isolate from a NT control ameliorates gut injury-associated active social engagement in mice. Collectively, our data demonstrate that past intestinal distress is associated with changes in active social behavior in mice that can be ameliorated by supplementation of members of the human microbiota.
Assuntos
Transtorno do Espectro Autista , Colite , Gastroenteropatias , Microbiota , Humanos , Masculino , Camundongos , Animais , Transtorno do Espectro Autista/terapia , Participação Social , Colite/terapia , Suplementos NutricionaisRESUMO
Regulation of the microbiota is critical to intestinal health yet the mechanisms employed by innate immunity remain unclear. Here we show that mice deficient in the C-Type-lectin receptor, Clec12a developed severe colitis, which was dependent on the microbiota. Fecal-microbiota-transplantation (FMT) studies into germfree mice revealed a colitogenic microbiota formed within Clec12a -/- mice that was marked by expansion of the gram-positive organism, Faecalibaculum rodentium . Treatment with F. rodentium was sufficient to worsen colitis in wild-type mice. Macrophages within the gut express the highest levels of Clec12a. Cytokine and sequencing analysis in Clec12a -/- macrophages revealed heighten inflammation but marked reduction in genes associated with phagocytosis. Indeed, Clec12a -/- macrophages are impaired in their ability to uptake F. rodentium. Purified Clec12a had higher binding to gram-positive organisms such as F. rodentium . Thus, our data identifies Clec12a as an innate immune surveillance mechanism to control expansion of potentially harmful commensals without overt inflammation.
RESUMO
Microbiome dysbiosis is a feature of diabetes, but how microbial products influence insulin production is poorly understood. We report the mechanism of BefA, a microbiome-derived protein that increases proliferation of insulin-producing ß cells during development in gnotobiotic zebrafish and mice. BefA disseminates systemically by multiple anatomic routes to act directly on pancreatic islets. We detail BefA's atomic structure, containing a lipid-binding SYLF domain, and demonstrate that it permeabilizes synthetic liposomes and bacterial membranes. A BefA mutant impaired in membrane disruption fails to expand ß cells, whereas the pore-forming host defense protein, Reg3, stimulates ß cell proliferation. Our work demonstrates that membrane permeabilization by microbiome-derived and host defense proteins is necessary and sufficient for ß cell expansion during pancreas development, potentially connecting microbiome composition with diabetes risk.
Assuntos
Diabetes Mellitus , Microbiota , Camundongos , Animais , Peixe-Zebra , Pâncreas/metabolismo , Insulina/metabolismo , Diabetes Mellitus/metabolismo , Proteínas/metabolismoRESUMO
Intestinal epithelial cells (IECs) have long been understood to express high levels of major histocompatibility complex class II (MHC class II) molecules but are not considered canonical antigen-presenting cells, and the impact of IEC-MHC class II signaling on gut homeostasis remains enigmatic. As IECs serve as the primary barrier between underlying host immune cells, we reasoned that IEC-intrinsic antigen presentation may play a role in responses toward the microbiota. Mice with an IEC-intrinsic deletion of MHC class II (IECΔMHC class II) are healthy but have fewer microbial-bound IgA, regulatory T cells (Tregs), and immune repertoire selection. This was associated with increased interindividual microbiota variation and altered proportions of two taxa in the ileum where MHC class II on IECs is highest. Intestinal mononuclear phagocytes (MNPs) have similar MHC class II transcription but less surface MHC class II and are capable of acquiring MHC class II from IECs. Thus, epithelial-myeloid interactions mediate development of adaptive responses to microbial antigens within the gastrointestinal tract.
Assuntos
Imunidade Adaptativa , Bactérias/imunologia , Células Epiteliais/imunologia , Microbioma Gastrointestinal , Antígenos de Histocompatibilidade Classe II/imunologia , Íleo/microbiologia , Imunidade nas Mucosas , Sistema Fagocitário Mononuclear/imunologia , Células Mieloides/imunologia , Animais , Antígenos de Bactérias/imunologia , Antígenos de Bactérias/metabolismo , Bactérias/crescimento & desenvolvimento , Bactérias/metabolismo , Linhagem Celular , Colite/imunologia , Colite/metabolismo , Colite/microbiologia , Modelos Animais de Doenças , Células Epiteliais/metabolismo , Células Epiteliais/microbiologia , Feminino , Antígenos de Histocompatibilidade Classe II/metabolismo , Interações Hospedeiro-Patógeno , Íleo/imunologia , Íleo/metabolismo , Imunoglobulina A/imunologia , Imunoglobulina A/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Sistema Fagocitário Mononuclear/metabolismo , Sistema Fagocitário Mononuclear/microbiologia , Células Mieloides/metabolismo , Células Mieloides/microbiologia , Transdução de Sinais , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismoRESUMO
Pathogenic fungi reside in the intestinal microbiota but rarely cause disease. Little is known about the interactions between fungi and the immune system that promote commensalism. Here we investigate the role of adaptive immunity in promoting mutual interactions between fungi and host. We find that potentially pathogenic Candida species induce and are targeted by intestinal immunoglobulin A (IgA) responses. Focused studies on Candida albicans reveal that the pathogenic hyphal morphotype, which is specialized for adhesion and invasion, is preferentially targeted and suppressed by intestinal IgA responses. IgA from mice and humans directly targets hyphal-enriched cell-surface adhesins. Although typically required for pathogenesis, C. albicans hyphae are less fit for gut colonization1,2 and we show that immune selection against hyphae improves the competitive fitness of C. albicans. C. albicans exacerbates intestinal colitis3 and we demonstrate that hyphae and an IgA-targeted adhesin exacerbate intestinal damage. Finally, using a clinically relevant vaccine to induce an adhesin-specific immune response protects mice from C. albicans-associated damage during colitis. Together, our findings show that adaptive immunity suppresses harmful fungal effectors, with benefits to both C. albicans and its host. Thus, IgA uniquely uncouples colonization from pathogenesis in commensal fungi to promote homeostasis.
Assuntos
Imunidade Adaptativa , Candida albicans/imunologia , Candida albicans/fisiologia , Interações Hospedeiro-Patógeno/imunologia , Simbiose/imunologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Antígenos de Fungos/imunologia , Candida albicans/patogenicidade , Colite/imunologia , Colite/microbiologia , Colite/patologia , Feminino , Vacinas Fúngicas/imunologia , Microbioma Gastrointestinal/imunologia , Humanos , Hifas/imunologia , Imunoglobulina A/imunologia , Masculino , Camundongos , Pessoa de Meia-Idade , Adulto JovemRESUMO
Humans and their microbiota have coevolved a mutually beneficial relationship in which the human host provides a hospitable environment for the microorganisms and the microbiota provides many advantages for the host, including nutritional benefits and protection from pathogen infection1. Maintaining this relationship requires a careful immune balance to contain commensal microorganisms within the lumen while limiting inflammatory anti-commensal responses1,2. Antigen-specific recognition of intestinal microorganisms by T cells has previously been described3,4. Although the local environment shapes the differentiation of effector cells3-5 it is unclear how microbiota-specific T cells are educated in the thymus. Here we show that intestinal colonization in early life leads to the trafficking of microbial antigens from the intestine to the thymus by intestinal dendritic cells, which then induce the expansion of microbiota-specific T cells. Once in the periphery, microbiota-specific T cells have pathogenic potential or can protect against related pathogens. In this way, the developing microbiota shapes and expands the thymic and peripheral T cell repertoire, allowing for enhanced recognition of intestinal microorganisms and pathogens.
Assuntos
Células Dendríticas/imunologia , Microbioma Gastrointestinal/imunologia , Linfócitos T/citologia , Linfócitos T/imunologia , Timo/citologia , Timo/imunologia , Envelhecimento/imunologia , Animais , Antígenos de Bactérias/imunologia , Antígenos de Bactérias/metabolismo , Receptor 1 de Quimiocina CX3C/metabolismo , DNA Bacteriano/análise , Células Dendríticas/metabolismo , Escherichia coli/imunologia , Feminino , Masculino , Camundongos , Especificidade de Órgãos , Salmonella/imunologia , Simbiose/imunologia , Timo/metabolismoRESUMO
BACKGROUND: Multiple sclerosis (MS) is an inflammatory demyelinating disease that affects 2.5 million people worldwide. Growing evidence suggests that perturbation of the gut microbiota, the dense collection of microorganisms that colonize the gastrointestinal tract, plays a functional role in MS. Indeed, specific gut-resident bacteria are altered in patients with MS compared to healthy individuals, and colonization of gnotobiotic mice with MS-associated microbiota exacerbates preclinical models of MS. However, defining the molecular mechanisms by which gut commensals can remotely affect the neuroinflammatory process remains a critical gap in the field. METHODS: We utilized monophasic experimental autoimmune encephalomyelitis (EAE) in C57BL/6J mice and relapse-remitting EAE in SJL/J mice to test the effects of the products from a human gut-derived commensal strain of Lactobacillus paracasei (Lb). RESULTS: We report that Lb can ameliorate preclinical murine models of MS with both prophylactic and therapeutic administrations. Lb ameliorates disease through a Toll-like receptor 2-dependent mechanism via its microbe-associated molecular patterns that can be detected in the systemic circulation, are sufficient to downregulate chemokine production, and can reduce immune cell infiltration into the central nervous system (CNS). In addition, alterations in the gut microbiota mediated by Lb-associated molecular patterns are sufficient to provide partial protection against neuroinflammatory diseases. CONCLUSIONS: Local Lb modulation of the gut microbiota and the shedding of Lb-associated molecular patterns into the circulation may be important physiological signals to prevent aberrant peripheral immune cell infiltration into the CNS and have relevance to the development of new therapeutic strategies for MS.
Assuntos
Sistema Nervoso Central/imunologia , Microbioma Gastrointestinal/imunologia , Lacticaseibacillus paracasei/imunologia , Leucócitos/imunologia , Animais , Sistema Nervoso Central/patologia , Feminino , Humanos , Leucócitos/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos KnockoutRESUMO
The microbiota influences obesity, yet organisms that protect from disease remain unknown. During studies interrogating host-microbiota interactions, we observed the development of age-associated metabolic syndrome (MetS). Expansion of Desulfovibrio and loss of Clostridia were key features associated with obesity in this model and are present in humans with MetS. T cell-dependent events were required to prevent disease, and replacement of Clostridia rescued obesity. Inappropriate immunoglobulin A targeting of Clostridia and increased Desulfovibrio antagonized the colonization of beneficial Clostridia. Transcriptional and metabolic analysis revealed enhanced lipid absorption in the obese host. Colonization of germ-free mice with Clostridia, but not Desulfovibrio, down-regulated genes that control lipid absorption and reduced adiposity. Thus, immune control of the microbiota maintains beneficial microbial populations that constrain lipid metabolism to prevent MetS.
Assuntos
Clostridium/imunologia , Desulfovibrio/imunologia , Microbiota/imunologia , Obesidade/imunologia , Obesidade/microbiologia , Linfócitos T Reguladores/imunologia , Animais , Antibiose , Interações entre Hospedeiro e Microrganismos , Absorção Intestinal , Metabolismo dos Lipídeos , Síndrome Metabólica/imunologia , Síndrome Metabólica/microbiologia , Camundongos , Camundongos Mutantes , Fator 88 de Diferenciação Mieloide/genéticaRESUMO
Symbiotic microbes impact the function and development of the central nervous system (CNS); however, little is known about the contribution of the microbiota during viral-induced neurologic damage. We identify that commensals aid in host defense following infection with a neurotropic virus through enhancing microglia function. Germfree mice or animals that receive antibiotics are unable to control viral replication within the brain leading to increased paralysis. Microglia derived from germfree or antibiotic-treated animals cannot stimulate viral-specific immunity and microglia depletion leads to worsened demyelination. Oral administration of toll-like receptor (TLR) ligands to virally infected germfree mice limits neurologic damage. Homeostatic activation of microglia is dependent on intrinsic signaling through TLR4, as disruption of TLR4 within microglia, but not the entire CNS (excluding microglia), leads to increased viral-induced clinical disease. This work demonstrates that gut immune-stimulatory products can influence microglia function to prevent CNS damage following viral infection.
Assuntos
Encefalite Viral/patologia , Encefalite Viral/prevenção & controle , Microbioma Gastrointestinal/imunologia , Microglia/imunologia , Transdução de Sinais , Simbiose , Receptores Toll-Like/metabolismo , Animais , Modelos Animais de Doenças , Vida Livre de Germes , CamundongosRESUMO
Bacteriophages are the most abundant members of the microbiota and have the potential to shape gut bacterial communities. Changes to bacteriophage composition are associated with disease, but how phages impact mammalian health remains unclear. We noted an induction of host immunity when experimentally treating bacterially driven cancer, leading us to test whether bacteriophages alter immune responses. Treating germ-free mice with bacteriophages leads to immune cell expansion in the gut. Lactobacillus, Escherichia, and Bacteroides bacteriophages and phage DNA stimulated IFN-γ via the nucleotide-sensing receptor TLR9. The resultant immune responses were both phage and bacteria specific. Additionally, increasing bacteriophage levels exacerbated colitis via TLR9 and IFN-γ. Similarly, ulcerative colitis (UC) patients responsive to fecal microbiota transplantation (FMT) have reduced phages compared to non-responders, and mucosal IFN-γ positively correlates with bacteriophage levels. Bacteriophages from active UC patients induced more IFN-γ compared to healthy individuals. Collectively, these results indicate that bacteriophages can alter mucosal immunity to impact mammalian health.
Assuntos
Bactérias/virologia , Bacteriófagos , Colite Ulcerativa/imunologia , Colite Ulcerativa/microbiologia , Neoplasias Colorretais/imunologia , Neoplasias Colorretais/microbiologia , Microbioma Gastrointestinal , Mucosa Intestinal/imunologia , Mucosa Intestinal/microbiologia , Animais , Linfócitos T CD4-Positivos/metabolismo , Colite Ulcerativa/patologia , Neoplasias Colorretais/patologia , Modelos Animais de Doenças , Transplante de Microbiota Fecal , Humanos , Interferon gama/metabolismo , Mucosa Intestinal/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Projetos Piloto , Estudos Prospectivos , Organismos Livres de Patógenos EspecíficosRESUMO
Although socially controlled sex transformation in fishes is well established, the underlying mechanisms are not well understood. Particularly enigmatic is behavioural transformation, in which fish can rapidly switch from exhibiting female to male-typical courtship behaviours following removal of 'supermales'. Bluehead wrasses are a model system for investigating environmental control of sex determination, particularly the social control of sex transformation. Here, we show that the onset of this behavioural transformation was delayed in females that occupied low-ranking positions in the female dominance hierarchy. We also establish that expression of male-typical courtship behaviours in competent initial-phase (IP) females is facultative and gated by the presence of terminal-phase (TP) males. Dominant females displayed reliable TP male-typical courtship behaviours within approximately 2 days of the removal of a TP male; immediately following reintroduction of the TP male, however, females reverted back to female-typical behaviours. These results demonstrate a remarkable plasticity of sexual behaviour and support a 'priming/gating' hypothesis for the control of behavioural transformation in bluehead wrasses.
Assuntos
Corte , Perciformes/fisiologia , Comportamento Sexual Animal/fisiologia , Animais , Feminino , Masculino , Processos de Determinação Sexual/fisiologia , Predomínio Social , Gravação em VídeoRESUMO
Symbiotic microbes impact the severity of a variety of diseases through regulation of T-cell development. However, little is known regarding the molecular mechanisms by which this is accomplished. Here we report that a secreted factor, Erdr1, is regulated by the microbiota to control T-cell apoptosis. Erdr1 expression was identified by transcriptome analysis to be elevated in splenic T cells from germfree and antibiotic-treated mice. Suppression of Erdr1 depends on detection of circulating microbial products by Toll-like receptors on T cells, and this regulation is conserved in human T cells. Erdr1 was found to function as an autocrine factor to induce apoptosis through caspase 3. Consistent with elevated levels of Erdr1, germfree mice have increased splenic T-cell apoptosis. RNA sequencing of Erdr1-overexpressing cells identified the up-regulation of genes involved in Fas-mediated cell death, and Erdr1 fails to induce apoptosis in Fas-deficient cells. Importantly, forced changes in Erdr1 expression levels dictate the survival of auto-reactive T cells and the clinical outcome of neuro-inflammatory autoimmune disease. Cellular survival is a fundamental feature regulating appropriate immune responses. We have identified a mechanism whereby the host integrates signals from the microbiota to control T-cell apoptosis, making regulation of Erdr1 a potential therapeutic target for autoimmune disease.
Assuntos
Apoptose , Proteínas de Membrana/fisiologia , Microbiota , Linfócitos T/fisiologia , Proteínas Supressoras de Tumor/fisiologia , Animais , Encefalomielite Autoimune Experimental/metabolismo , Homeostase , Humanos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Cultura Primária de Células , Receptor fas/metabolismoRESUMO
The commensal microbiota has an important impact on host health, which is only beginning to be elucidated. Despite the presence of fungal, archaeal, and viral members, most studies have focused solely on the bacterial microbiota. Antibodies against the yeast Saccharomyces cerevisiae are found in some patients with Crohn's disease (CD), suggesting that the mycobiota may contribute to disease severity. We report that S. cerevisiae exacerbated intestinal disease in a mouse model of colitis and increased gut barrier permeability. Transcriptome analysis of colon tissue from germ-free mice inoculated with S. cerevisiae or another fungus, Rhodotorula aurantiaca, revealed that S. cerevisiae colonization affected the intestinal barrier and host metabolism. A fecal metabolomics screen of germ-free animals demonstrated that S. cerevisiae colonization enhanced host purine metabolism, leading to an increase in uric acid production. Treatment with uric acid alone worsened disease and increased gut permeability. Allopurinol, a clinical drug used to reduce uric acid, ameliorated colitis induced by S. cerevisiae in mice. In addition, we found a positive correlation between elevated uric acid and anti-yeast antibodies in human sera. Thus, yeast in the gut may be able to potentiate metabolite production that negatively affects the course of inflammatory bowel disease.
Assuntos
Colite/microbiologia , Colite/patologia , Progressão da Doença , Microbioma Gastrointestinal , Interações Hospedeiro-Patógeno , Purinas/metabolismo , Animais , Anticorpos Antifúngicos/sangue , Colite/imunologia , Contagem de Colônia Microbiana , Modelos Animais de Doenças , Feminino , Interações Hospedeiro-Patógeno/imunologia , Humanos , Mucosa Intestinal/microbiologia , Masculino , Camundongos Endogâmicos C57BL , Rhodotorula , Saccharomyces cerevisiae/crescimento & desenvolvimento , Saccharomyces cerevisiae/imunologia , Simbiose , Ácido Úrico/sangueRESUMO
The presentation of protein antigens on the cell surface by major histocompatibility complex (MHC) molecules coordinates vertebrate adaptive immune responses, thereby mediating susceptibility to a variety of autoimmune and infectious diseases. The composition of symbiotic microbial communities (the microbiota) is influenced by host immunity and can have a profound impact on host physiology. Here we use an MHC congenic mouse model to test the hypothesis that genetic variation at MHC genes among individuals mediates susceptibility to disease by controlling microbiota composition. We find that MHC genotype significantly influences antibody responses against commensals in the gut, and that these responses are correlated with the establishment of unique microbial communities. Transplantation experiments in germfree mice indicate that MHC-mediated differences in microbiota composition are sufficient to explain susceptibility to enteric infection. Our findings indicate that MHC polymorphisms contribute to defining an individual's unique microbial fingerprint that influences health.