RESUMO
Systems biological analysis of immunity to the trivalent inactivated influenza vaccine (TIV) in humans revealed a correlation between early expression of TLR5 and the magnitude of the antibody response. Vaccination of Trl5(-/-) mice resulted in reduced antibody titers and lower frequencies of plasma cells, demonstrating a role for TLR5 in immunity to TIV. This was due to a failure to sense host microbiota. Thus, antibody responses in germ-free or antibiotic-treated mice were impaired, but restored by oral reconstitution with a flagellated, but not aflagellated, strain of E. coli. TLR5-mediated sensing of flagellin promoted plasma cell differentiation directly and by stimulating lymph node macrophages to produce plasma cell growth factors. Finally, TLR5-mediated sensing of the microbiota also impacted antibody responses to the inactivated polio vaccine, but not to adjuvanted vaccines or the live-attenuated yellow fever vaccine. These results reveal an unappreciated role for gut microbiota in promoting immunity to vaccination.
Assuntos
Formação de Anticorpos/imunologia , Vacinas contra Influenza/imunologia , Intestinos/microbiologia , Microbiota/imunologia , Receptor 5 Toll-Like/imunologia , Animais , Anticorpos Antivirais/sangue , Linfócitos B/imunologia , Diferenciação Celular/imunologia , Escherichia coli/imunologia , Flagelina/imunologia , Humanos , Memória Imunológica/imunologia , Influenza Humana/prevenção & controle , Intestinos/imunologia , Linfonodos/citologia , Linfonodos/imunologia , Macrófagos/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Plasmócitos/imunologia , Plasmócitos/metabolismo , Vacina Antipólio de Vírus Inativado/imunologia , Transdução de Sinais/imunologia , Receptor 5 Toll-Like/biossíntese , Receptor 5 Toll-Like/genética , Vacina contra Febre Amarela/imunologiaRESUMO
The integrated stress response (ISR) is a homeostatic mechanism by which eukaryotic cells sense and respond to stress-inducing signals, such as amino acid starvation. General controlled non-repressed (GCN2) kinase is a key orchestrator of the ISR, and modulates protein synthesis in response to amino acid starvation. Here we demonstrate in mice that GCN2 controls intestinal inflammation by suppressing inflammasome activation. Enhanced activation of ISR was observed in intestinal antigen presenting cells (APCs) and epithelial cells during amino acid starvation, or intestinal inflammation. Genetic deletion of Gcn2 (also known as Eif2ka4) in CD11c(+) APCs or intestinal epithelial cells resulted in enhanced intestinal inflammation and T helper 17 cell (TH17) responses, owing to enhanced inflammasome activation and interleukin (IL)-1ß production. This was caused by reduced autophagy in Gcn2(-/-) intestinal APCs and epithelial cells, leading to increased reactive oxygen species (ROS), a potent activator of inflammasomes. Thus, conditional ablation of Atg5 or Atg7 in intestinal APCs resulted in enhanced ROS and TH17 responses. Furthermore, in vivo blockade of ROS and IL-1ß resulted in inhibition of TH17 responses and reduced inflammation in Gcn2(-/-) mice. Importantly, acute amino acid starvation suppressed intestinal inflammation via a mechanism dependent on GCN2. These results reveal a mechanism that couples amino acid sensing with control of intestinal inflammation via GCN2.
Assuntos
Aminoácidos/metabolismo , Colite/metabolismo , Inflamassomos/antagonistas & inibidores , Inflamação/metabolismo , Mucosa Intestinal/metabolismo , Intestinos/patologia , Proteínas Serina-Treonina Quinases/metabolismo , Aminoácidos/administração & dosagem , Aminoácidos/deficiência , Aminoácidos/farmacologia , Animais , Células Apresentadoras de Antígenos/imunologia , Células Apresentadoras de Antígenos/metabolismo , Autofagia , Proteína 5 Relacionada à Autofagia , Proteína 7 Relacionada à Autofagia , Colite/etiologia , Colite/patologia , Colite/prevenção & controle , Modelos Animais de Doenças , Células Epiteliais/metabolismo , Feminino , Humanos , Inflamassomos/metabolismo , Inflamação/etiologia , Inflamação/patologia , Inflamação/prevenção & controle , Interleucina-1beta/imunologia , Masculino , Camundongos , Proteínas Associadas aos Microtúbulos/deficiência , Proteínas Associadas aos Microtúbulos/metabolismo , Proteínas Serina-Treonina Quinases/deficiência , Proteínas Serina-Treonina Quinases/genética , Espécies Reativas de Oxigênio/metabolismo , Estresse Fisiológico , Células Th17/imunologia , Enzimas Ativadoras de Ubiquitina/deficiência , Enzimas Ativadoras de Ubiquitina/metabolismoRESUMO
B lymphocytes perform somatic hypermutation and class-switch recombination (CSR) of the immunoglobulin locus to generate an antibody repertoire diverse in both affinity and function. These somatic diversification processes are catalyzed by activation-induced cytidine deaminase (AID), a potent DNA mutator whose expression and function are highly regulated. Here we show that AID was regulated posttranscriptionally by a lymphocyte-specific microRNA, miR-155. We found that miR-155 was upregulated in murine B lymphocytes undergoing CSR and that it targeted a conserved site in the 3'-untranslated region of the mRNA encoding AID. Disruption of this target site in vivo resulted in quantitative and temporal deregulation of AID expression, along with functional consequences for CSR and affinity maturation. Thus, miR-155, which has recently been shown to play important roles in regulating the germinal-center reaction, does so in part by directly downmodulating AID expression.
Assuntos
Linfócitos B/enzimologia , Citidina Desaminase/genética , Citidina Desaminase/metabolismo , MicroRNAs/metabolismo , Regiões 3' não Traduzidas , Animais , Linfócitos B/imunologia , Linfócitos B/metabolismo , Células Cultivadas , Switching de Imunoglobulina , Lipopolissacarídeos/imunologia , Camundongos , Camundongos Mutantes , Camundongos Transgênicos , MicroRNAs/genética , MicroRNAs/imunologia , Mutação , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Hipermutação Somática de ImunoglobulinaRESUMO
Antigen-presenting cells (APCs) occupy diverse anatomical tissues, but their tissue-restricted homeostasis remains poorly understood. Here, working with mouse models of inflammation, we found that mechanistic target of rapamycin (mTOR)-dependent metabolic adaptation was required at discrete locations. mTOR was dispensable for dendritic cell (DC) homeostasis in secondary lymphoid tissues but necessary to regulate cellular metabolism and accumulation of CD103+ DCs and alveolar macrophages in lung. Moreover, while numbers of mTOR-deficient lung CD11b+ DCs were not changed, they were metabolically reprogrammed to skew allergic inflammation from eosinophilic T helper cell 2 (TH2) to neutrophilic TH17 polarity. The mechanism for this change was independent of translational control but dependent on inflammatory DCs, which produced interleukin-23 and increased fatty acid oxidation. mTOR therefore mediates metabolic adaptation of APCs in distinct tissues, influencing the immunological character of allergic inflammation.
Assuntos
Células Dendríticas/imunologia , Homeostase , Hipersensibilidade/metabolismo , Inflamação/metabolismo , Pulmão/metabolismo , Serina-Treonina Quinases TOR/metabolismo , Animais , Apresentação de Antígeno , Antígenos CD/metabolismo , Antígeno CD11b/genética , Antígeno CD11b/metabolismo , Eosinófilos/imunologia , Ácidos Graxos/metabolismo , Cadeias alfa de Integrinas/metabolismo , Interleucina-23/metabolismo , Pulmão/patologia , Camundongos , Camundongos Endogâmicos C57BL , Neutrófilos/imunologia , Oxirredução , Serina-Treonina Quinases TOR/genética , Células Th17/imunologia , Células Th2/imunologiaRESUMO
Both class switch recombination (CSR) and somatic hypermutation (SHM) require transcription and the trans-acting factor activation-induced cytidine deaminase (AID), and must be up-regulated during antigen-dependent differentiation of B lymphocytes. To test the role of the heavy chain 3' enhancers in both CSR and SHM, we used a BAC transgene of the entire heavy chain constant region locus. Using Cre-loxP recombination to delete a 28-kb region that contains the four known 3' heavy chain enhancers, we isolated lines of BAC transgenic mice with an intact heavy chain locus and paired lines in the same chromosomal insertion site lacking the 3' enhancers. Intact heavy chain transgenes undergo CSR to all heavy chain genes and mutate their transgenic VDJ exon. In paired transgenes lacking the 3' enhancer region, CSR to most heavy chain genes is reduced to approximately 1% of the levels for intact heavy chain loci; SHM is also reduced. Finally, we find that in B cells with a transgene lacking the 3' enhancers, interchromosomal recombination between the transgenic VDJ exon and the endogenous heavy chain C genes is more easily detected than CSR within the transgene.
Assuntos
Regiões 3' não Traduzidas/fisiologia , Linfócitos B/metabolismo , Elementos Facilitadores Genéticos/fisiologia , Cadeias Pesadas de Imunoglobulinas/metabolismo , Recombinação Genética/fisiologia , Hipermutação Somática de Imunoglobulina/fisiologia , Animais , Galinhas , Citidina Desaminase/genética , Citidina Desaminase/metabolismo , Cadeias Pesadas de Imunoglobulinas/genética , Integrases/genética , Integrases/metabolismo , Camundongos , Camundongos Transgênicos , Locos de Características Quantitativas/genética , Deleção de Sequência , Transcrição Gênica/fisiologia , Transgenes/fisiologia , Éxons VDJ/genéticaRESUMO
Mouse mammary tumor virus (MMTV) is acquired by neonates through milk and first infects lymphocytes in Peyer's patches. We show here that newborn mice lacking beta7 integrin or L-selectin were infected with MMTV at wild-type levels in both their lymphoid and mammary tissues. Superantigen-mediated activation and cognate T cell deletion were also unimpaired in both types of null mice. A large proportion of neonatal Peyer's patch lymphocytes in wild-type mice were beta7 and beta1 integrin low and both populations increased in response to MMTV infection. These results suggest that adhesion molecules other than beta7 integrin or L-selectin play a role in lymphocyte homing in the gut, peripheral lymph nodes and mammary gland in response to MMTV infection.