RESUMO
In lupus, Toll-like receptor 7 (TLR7) and TLR9 mediate loss of tolerance to RNA and DNA, respectively. Yet, TLR7 promotes disease, while TLR9 protects from disease, implying differences in signaling. To dissect this 'TLR paradox', we generated two TLR9 point mutants (lacking either ligand (TLR9K51E) or MyD88 (TLR9P915H) binding) in lupus-prone MRL/lpr mice. Ameliorated disease of Tlr9K51E mice compared to Tlr9-/- controls revealed a TLR9 'scaffold' protective function that is ligand and MyD88 independent. Unexpectedly, Tlr9P915H mice were more protected than both Tlr9K51E and Tlr9WT mice, suggesting that TLR9 also possesses ligand-dependent, but MyD88-independent, regulatory signaling and MyD88-mediated proinflammatory signaling. Triple-mixed bone marrow chimeras showed that TLR9-MyD88-independent regulatory roles were B cell intrinsic and restrained differentiation into pathogenic age-associated B cells and plasmablasts. These studies reveal MyD88-independent regulatory roles of TLR9, shedding light on the biology of endosomal TLRs.
Assuntos
Receptor 7 Toll-Like , Receptor Toll-Like 9 , Animais , DNA , Ligantes , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos MRL lpr , Camundongos Knockout , Fator 88 de Diferenciação Mieloide/genética , Fator 88 de Diferenciação Mieloide/metabolismo , RNA , Receptor 7 Toll-Like/genética , Receptor 7 Toll-Like/metabolismo , Receptor Toll-Like 9/genética , Receptor Toll-Like 9/metabolismoRESUMO
Macrophages enforce antitumor immunity by engulfing and killing tumor cells. Although these functions are determined by a balance of stimulatory and inhibitory signals, the role of macrophage metabolism is unknown. Here, we study the capacity of macrophages to circumvent inhibitory activity mediated by CD47 on cancer cells. We show that stimulation with a CpG oligodeoxynucleotide, a Toll-like receptor 9 agonist, evokes changes in the central carbon metabolism of macrophages that enable antitumor activity, including engulfment of CD47+ cancer cells. CpG activation engenders a metabolic state that requires fatty acid oxidation and shunting of tricarboxylic acid cycle intermediates for de novo lipid biosynthesis. This integration of metabolic inputs is underpinned by carnitine palmitoyltransferase 1A and adenosine tri-phosphate citrate lyase, which, together, impart macrophages with antitumor potential capable of overcoming inhibitory CD47 on cancer cells. Our findings identify central carbon metabolism to be a novel determinant and potential therapeutic target for stimulating antitumor activity by macrophages.
Assuntos
Antígeno CD47/imunologia , Macrófagos/efeitos dos fármacos , Oligodesoxirribonucleotídeos/farmacologia , Fagocitose/efeitos dos fármacos , Animais , Antígeno CD47/metabolismo , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/imunologia , Células Cultivadas , Técnicas de Cocultura , Humanos , Macrófagos/imunologia , Macrófagos/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Neoplasias Pancreáticas/imunologia , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/patologia , Fagocitose/imunologia , Receptor Toll-Like 9/agonistas , Receptor Toll-Like 9/imunologia , Receptor Toll-Like 9/metabolismoRESUMO
Key events in T cell-dependent antibody responses, including affinity maturation, are dependent on the B cell's presentation of antigen to helper T cells at critical checkpoints in germinal-center formation in secondary lymphoid organs. Here we found that signaling via Toll-like receptor 9 (TLR9) blocked the ability of antigen-specific B cells to capture, process and present antigen and to activate antigen-specific helper T cells in vitro. In a mouse model in vivo and in a human clinical trial, the TLR9 agonist CpG enhanced the magnitude of the antibody response to a protein vaccine but failed to promote affinity maturation. Thus, TLR9 signaling might enhance antibody titers at the expense of the ability of B cells to engage in germinal-center events that are highly dependent on B cells' capture and presentation of antigen.
Assuntos
Formação de Anticorpos/imunologia , Apresentação de Antígeno/genética , Ativação Linfocitária/imunologia , Receptor Toll-Like 9/imunologia , Animais , Afinidade de Anticorpos , Centro Germinativo/imunologia , Humanos , Vacinas Antimaláricas , Camundongos , Receptor Toll-Like 9/agonistasRESUMO
The transcription factor AhR modulates immunity at multiple levels. Here we report that phagocytes exposed to apoptotic cells exhibited rapid activation of AhR, which drove production of the cytokine IL-10. Activation of AhR was dependent on interactions between apoptotic-cell DNA and the pattern-recognition receptor TLR9 that was required for the prevention of immune responses to DNA and histones in vivo. Moreover, disease progression in mouse systemic lupus erythematosus (SLE) correlated with strength of the AhR signal, and the disease course could be altered by modulation of AhR activity. Deletion of AhR in the myeloid lineage caused systemic autoimmunity in mice, and an enhanced AhR transcriptional signature correlated with disease in patients with SLE. Thus, AhR activity induced by apoptotic cell phagocytes maintains peripheral tolerance.
Assuntos
Apoptose/imunologia , Tolerância Imunológica/imunologia , Lúpus Eritematoso Sistêmico/imunologia , Macrófagos/imunologia , Receptores de Hidrocarboneto Arílico/imunologia , Animais , Humanos , Camundongos , Transdução de Sinais/imunologia , Receptor Toll-Like 9/imunologiaRESUMO
B cells are activated by two temporally distinct signals, the first provided by the binding of antigen to the B cell antigen receptor (BCR), and the second provided by helper T cells. Here we found that B cells responded to antigen by rapidly increasing their metabolic activity, including both oxidative phosphorylation and glycolysis. In the absence of a second signal, B cells progressively lost mitochondrial function and glycolytic capacity, which led to apoptosis. Mitochondrial dysfunction was a result of the gradual accumulation of intracellular calcium through calcium response-activated calcium channels that, for approximately 9 h after the binding of B cell antigens, was preventable by either helper T cells or signaling via the receptor TLR9. Thus, BCR signaling seems to activate a metabolic program that imposes a limited time frame during which B cells either receive a second signal and survive or are eliminated.
Assuntos
Linfócitos B/fisiologia , Mitocôndrias/metabolismo , Receptores de Antígenos de Linfócitos B/metabolismo , Linfócitos T Auxiliares-Indutores/imunologia , Receptor Toll-Like 9/metabolismo , Animais , Apoptose , Cálcio/metabolismo , Canais de Cálcio/metabolismo , Citocinas/metabolismo , Glicólise , Ativação Linfocitária , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Células NIH 3T3 , Fosforilação Oxidativa , Receptores de Antígenos de Linfócitos B/genética , Transdução de Sinais , Receptor Toll-Like 9/genéticaRESUMO
The sensing of microbial genetic material by leukocytes often elicits beneficial pro-inflammatory cytokines, but dysregulated responses can cause severe pathogenesis. Genome-wide association studies have linked the gene encoding phospholipase D3 (PLD3) to Alzheimer's disease and have linked PLD4 to rheumatoid arthritis and systemic sclerosis. PLD3 and PLD4 are endolysosomal proteins whose functions are obscure. Here, PLD4-deficient mice were found to have an inflammatory disease, marked by elevated levels of interferon-γ (IFN-γ) and splenomegaly. These phenotypes were traced to altered responsiveness of PLD4-deficient dendritic cells to ligands of the single-stranded DNA sensor TLR9. Macrophages from PLD3-deficient mice also had exaggerated TLR9 responses. Although PLD4 and PLD3 were presumed to be phospholipases, we found that they are 5' exonucleases, probably identical to spleen phosphodiesterase, that break down TLR9 ligands. Mice deficient in both PLD3 and PLD4 developed lethal liver inflammation in early life, which indicates that both enzymes are needed to regulate inflammatory cytokine responses via the degradation of nucleic acids.
Assuntos
Células Dendríticas/fisiologia , Endossomos/metabolismo , Exonucleases/metabolismo , Hepatite/genética , Macrófagos/fisiologia , Glicoproteínas de Membrana/metabolismo , Fosfolipase D/metabolismo , Doença de Alzheimer/genética , Animais , Artrite Reumatoide/genética , DNA de Cadeia Simples/imunologia , Exonucleases/genética , Estudo de Associação Genômica Ampla , Humanos , Interferon gama/metabolismo , Glicoproteínas de Membrana/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fosfolipase D/genética , Escleroderma Sistêmico/genética , Transdução de Sinais , Receptor Toll-Like 9/metabolismoRESUMO
As hippocampal neurons respond to diverse types of information1, a subset assembles into microcircuits representing a memory2. Those neurons typically undergo energy-intensive molecular adaptations, occasionally resulting in transient DNA damage3-5. Here we found discrete clusters of excitatory hippocampal CA1 neurons with persistent double-stranded DNA (dsDNA) breaks, nuclear envelope ruptures and perinuclear release of histone and dsDNA fragments hours after learning. Following these early events, some neurons acquired an inflammatory phenotype involving activation of TLR9 signalling and accumulation of centrosomal DNA damage repair complexes6. Neuron-specific knockdown of Tlr9 impaired memory while blunting contextual fear conditioning-induced changes of gene expression in specific clusters of excitatory CA1 neurons. Notably, TLR9 had an essential role in centrosome function, including DNA damage repair, ciliogenesis and build-up of perineuronal nets. We demonstrate a novel cascade of learning-induced molecular events in discrete neuronal clusters undergoing dsDNA damage and TLR9-mediated repair, resulting in their recruitment to memory circuits. With compromised TLR9 function, this fundamental memory mechanism becomes a gateway to genomic instability and cognitive impairments implicated in accelerated senescence, psychiatric disorders and neurodegenerative disorders. Maintaining the integrity of TLR9 inflammatory signalling thus emerges as a promising preventive strategy for neurocognitive deficits.
Assuntos
Região CA1 Hipocampal , Quebras de DNA de Cadeia Dupla , Reparo do DNA , Inflamação , Memória , Receptor Toll-Like 9 , Animais , Feminino , Masculino , Camundongos , Envelhecimento/genética , Envelhecimento/patologia , Região CA1 Hipocampal/fisiologia , Centrossomo/metabolismo , Disfunção Cognitiva/genética , Condicionamento Clássico , Matriz Extracelular/metabolismo , Medo , Instabilidade Genômica/genética , Histonas/metabolismo , Inflamação/genética , Inflamação/imunologia , Inflamação/metabolismo , Inflamação/patologia , Memória/fisiologia , Transtornos Mentais/genética , Doenças Neurodegenerativas/genética , Doenças Neuroinflamatórias/genética , Neurônios/metabolismo , Neurônios/patologia , Membrana Nuclear/patologia , Receptor Toll-Like 9/deficiência , Receptor Toll-Like 9/genética , Receptor Toll-Like 9/imunologia , Receptor Toll-Like 9/metabolismoRESUMO
The retention of intracellular Toll-like receptors (TLRs) in the endoplasmic reticulum prevents their activation under basal conditions. TLR9 is activated by sensing ligands in specific endosomal-lysosomal compartments. Here we identified IRAP+ endosomes as major cellular compartments for the early steps of TLR9 activation in dendritic cells (DCs). Both TLR9 and its ligand, the dinucleotide CpG, were present as cargo in IRAP+ endosomes. In the absence of the aminopeptidase IRAP, the trafficking of CpG and TLR9 to lysosomes and signaling via TLR9 were enhanced in DCs and in mice following bacterial infection. IRAP stabilized CpG-containing endosomes by interacting with the actin-nucleation factor FHOD4, which slowed the trafficking of TLR9 toward lysosomes. Thus, endosomal retention of TLR9 via the interaction of IRAP with the actin cytoskeleton is a mechanism that prevents hyper-activation of TLR9 in DCs.
Assuntos
Cistinil Aminopeptidase/metabolismo , Citoesqueleto/metabolismo , Células Dendríticas/fisiologia , Endossomos/metabolismo , Infecções por Pseudomonas/imunologia , Pseudomonas aeruginosa/imunologia , Receptor Toll-Like 9/metabolismo , Animais , Células Cultivadas , Ilhas de CpG/genética , Cistinil Aminopeptidase/genética , Células Dendríticas/microbiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mutação/genética , Oligodesoxirribonucleotídeos/imunologia , Ligação Proteica , Transdução de SinaisRESUMO
The immune system monitors the health of cells and is stimulated by necrosis. Here we examined the receptors and ligands driving this response. In a targeted screen of C-type lectin receptors, a Clec2d reporter responded to lysates from necrotic cells. Biochemical purification identified histones, both free and bound to nucleosomes or neutrophil extracellular traps, as Clec2d ligands. Clec2d recognized poly-basic sequences in histone tails and this recognition was sensitive to post-translational modifications of these sequences. As compared with WT mice, Clec2d-/- mice exhibited reduced proinflammatory responses to injected histones, and less tissue damage and improved survival in a hepatotoxic injury model. In macrophages, Clec2d localized to the plasma membrane and endosomes. Histone binding to Clec2d did not stimulate kinase activation or cytokine production. Rather, histone-bound DNA stimulated endosomal Tlr9-dependent responses in a Clec2d-dependent manner. Thus, Clec2d binds to histones released upon necrotic cell death, with functional consequences to inflammation and tissue damage.
Assuntos
Histonas/metabolismo , Lectinas Tipo C/imunologia , Lectinas Tipo C/metabolismo , Fígado/lesões , Necrose/patologia , Receptores de Superfície Celular/imunologia , Receptores de Superfície Celular/metabolismo , Animais , Apoptose/imunologia , Endossomos/metabolismo , Células HEK293 , Humanos , Células Jurkat , Lectinas Tipo C/genética , Macrófagos/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neutrófilos/imunologia , Receptores de Superfície Celular/genética , Receptor Toll-Like 9/imunologiaRESUMO
Class-switched antibodies to double-stranded DNA (dsDNA) are prevalent and pathogenic in systemic lupus erythematosus (SLE), yet mechanisms of their development remain poorly understood. Humans and mice lacking secreted DNase DNASE1L3 develop rapid anti-dsDNA antibody responses and SLE-like disease. We report that anti-DNA responses in Dnase1l3-/- mice require CD40L-mediated T cell help, but proceed independently of germinal center formation via short-lived antibody-forming cells (AFCs) localized to extrafollicular regions. Type I interferon (IFN-I) signaling and IFN-I-producing plasmacytoid dendritic cells (pDCs) facilitate the differentiation of DNA-reactive AFCs in vivo and in vitro and are required for downstream manifestations of autoimmunity. Moreover, the endosomal DNA sensor TLR9 promotes anti-dsDNA responses and SLE-like disease in Dnase1l3-/- mice redundantly with another nucleic acid-sensing receptor, TLR7. These results establish extrafollicular B cell differentiation into short-lived AFCs as a key mechanism of anti-DNA autoreactivity and reveal a major contribution of pDCs, endosomal Toll-like receptors (TLRs), and IFN-I to this pathway.
Assuntos
Linfócitos B/imunologia , Linfócitos B/metabolismo , Comunicação Celular , DNA/imunologia , Células Dendríticas/imunologia , Células Dendríticas/metabolismo , Interferon Tipo I/metabolismo , Animais , Anticorpos Antinucleares/imunologia , Autoantígenos/imunologia , Autoimunidade , Biomarcadores , Ligante de CD40/deficiência , Comunicação Celular/genética , Comunicação Celular/imunologia , Modelos Animais de Doenças , Suscetibilidade a Doenças , Endodesoxirribonucleases/deficiência , Imunofluorescência , Centro Germinativo/imunologia , Centro Germinativo/metabolismo , Centro Germinativo/patologia , Lúpus Eritematoso Sistêmico/etiologia , Lúpus Eritematoso Sistêmico/metabolismo , Camundongos , Camundongos Knockout , Receptor 7 Toll-Like/metabolismo , Receptor Toll-Like 9/metabolismoRESUMO
Glycosylation processes are under high natural selection pressure, presumably because these can modulate resistance to infection. Here, we asked whether inactivation of the UDP-galactose:ß-galactoside-α1-3-galactosyltransferase (α1,3GT) gene, which ablated the expression of the Galα1-3Galß1-4GlcNAc-R (α-gal) glycan and allowed for the production of anti-α-gal antibodies (Abs) in humans, confers protection against Plasmodium spp. infection, the causative agent of malaria and a major driving force in human evolution. We demonstrate that both Plasmodium spp. and the human gut pathobiont E. coli O86:B7 express α-gal and that anti-α-gal Abs are associated with protection against malaria transmission in humans as well as in α1,3GT-deficient mice, which produce protective anti-α-gal Abs when colonized by E. coli O86:B7. Anti-α-gal Abs target Plasmodium sporozoites for complement-mediated cytotoxicity in the skin, immediately after inoculation by Anopheles mosquitoes. Vaccination against α-gal confers sterile protection against malaria in mice, suggesting that a similar approach may reduce malaria transmission in humans.
Assuntos
Escherichia coli/fisiologia , Imunoglobulina M/imunologia , Malária Falciparum/imunologia , Malária Falciparum/transmissão , Plasmodium/fisiologia , Polissacarídeos/imunologia , Adulto , Animais , Anopheles/parasitologia , Anticorpos Antibacterianos/sangue , Anticorpos Antibacterianos/imunologia , Anticorpos Antiprotozoários/sangue , Anticorpos Antiprotozoários/imunologia , Autoantígenos/imunologia , Linhagem Celular Tumoral , Criança , Escherichia coli/classificação , Escherichia coli/imunologia , Feminino , Galactosiltransferases/genética , Galactosiltransferases/metabolismo , Trato Gastrointestinal/microbiologia , Vida Livre de Germes , Humanos , Imunoglobulina M/sangue , Malária Falciparum/microbiologia , Malária Falciparum/parasitologia , Camundongos , Plasmodium/classificação , Plasmodium/crescimento & desenvolvimento , Plasmodium/imunologia , Plasmodium falciparum/imunologia , Plasmodium falciparum/fisiologia , Esporozoítos/imunologia , Receptor Toll-Like 9/agonistasRESUMO
Canonically, immunoglobulin E (IgE) mediates allergic immune responses by triggering mast cells and basophils to release histamine and type 2 helper cytokines. Here we found that in human systemic lupus erythematosus (SLE), IgE antibodies specific for double-stranded DNA (dsDNA) activated plasmacytoid dendritic cells (pDCs), a type of cell of the immune system linked to viral defense, which led to the secretion of substantial amounts of interferon-α (IFN-α). The concentration of dsDNA-specific IgE found in patient serum correlated with disease severity and greatly potentiated pDC function by triggering phagocytosis via the high-affinity FcÉRI receptor for IgE, followed by Toll-like receptor 9 (TLR9)-mediated sensing of DNA in phagosomes. Our findings expand the known pathogenic mechanisms of IgE-mediated inflammation beyond those found in allergy and demonstrate that IgE can trigger interferon responses capable of exacerbating self-destructive autoimmune responses.
Assuntos
Autoanticorpos/imunologia , Autoimunidade , Imunoglobulina E/imunologia , Interferons/metabolismo , Anticorpos Antinucleares/imunologia , Complexo Antígeno-Anticorpo/imunologia , Complexo Antígeno-Anticorpo/metabolismo , Linfócitos B/imunologia , Linfócitos B/metabolismo , Citocinas/sangue , Citocinas/metabolismo , Células Dendríticas/imunologia , Células Dendríticas/metabolismo , Feminino , Humanos , Imunoglobulina E/sangue , Imunoglobulina G/sangue , Imunoglobulina G/imunologia , Leucócitos Mononucleares/imunologia , Leucócitos Mononucleares/metabolismo , Lúpus Eritematoso Sistêmico/sangue , Lúpus Eritematoso Sistêmico/imunologia , Lúpus Eritematoso Sistêmico/metabolismo , Nefrite Lúpica/imunologia , Nefrite Lúpica/patologia , Masculino , Fagocitose/imunologia , Fagossomos/metabolismo , Plasmócitos/imunologia , Plasmócitos/metabolismo , Receptor Toll-Like 9/metabolismoRESUMO
Interleukin 17-producing helper T cells (T(H)17 cells) have a major role in protection against infections and in mediating autoimmune diseases, yet the mechanisms involved are incompletely understood. We found that interleukin 26 (IL-26), a human T(H)17 cell-derived cytokine, is a cationic amphipathic protein that kills extracellular bacteria via membrane-pore formation. Furthermore, T(H)17 cell-derived IL-26 formed complexes with bacterial DNA and self-DNA released by dying bacteria and host cells. The resulting IL-26-DNA complexes triggered the production of type I interferon by plasmacytoid dendritic cells via activation of Toll-like receptor 9, but independently of the IL-26 receptor. These findings provide insights into the potent antimicrobial and proinflammatory function of T(H)17 cells by showing that IL-26 is a natural human antimicrobial that promotes immune sensing of bacterial and host cell death.
Assuntos
DNA Bacteriano/imunologia , DNA/imunologia , Imunidade Inata/imunologia , Interleucinas/imunologia , Células Th17/imunologia , Receptor Toll-Like 9/imunologia , Animais , Células Dendríticas/imunologia , Células Dendríticas/metabolismo , Humanos , Interferon Tipo I/imunologia , Interferon Tipo I/metabolismo , Camundongos , Psoríase/imunologia , Receptores de Interleucina/imunologia , Receptores de Interleucina/metabolismoRESUMO
Toll-like receptor 9 (TLR9) recognizes DNA containing CpG motifs derived from bacteria and viruses and activates the innate immune response to eliminate them. TLR9 is known to bind to CpG DNA, and here, we identified another DNA binding site in TLR9 that binds DNA containing cytosine at the second position from the 5' end (5'-xCx DNA). 5'-xCx DNAs bound to TLR9 in the presence of CpG DNA and cooperatively promoted dimerization and activation of TLR9. Binding at both sites was important for efficient activation of TLR9. The 5'-xCx DNA bound the site corresponding to the nucleoside binding site in TLR7 and TLR8 as revealed by the structural analysis. This study revealed that TLR9 recognizes two types of DNA through its two binding sites for efficient activation. This information may contribute to the development of drugs that control the activity of TLR9.
Assuntos
Ilhas de CpG/genética , Proteínas de Ligação a DNA/metabolismo , DNA/metabolismo , Motivos de Nucleotídeos/genética , Receptor Toll-Like 9/genética , Receptor Toll-Like 9/metabolismo , Animais , Sítios de Ligação/genética , Linhagem Celular , DNA/genética , Dimerização , Drosophila , Ativação Enzimática , Células HEK293 , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptor 7 Toll-Like/genética , Receptor 7 Toll-Like/metabolismo , Receptor 8 Toll-Like/genética , Receptor 8 Toll-Like/metabolismoRESUMO
Plasmacytoid dendritic cells (pDCs) produce type I interferons (IFNs) after sensing viral/bacterial RNA or DNA by toll-like receptor (TLR) 7 or TLR9, respectively. However, aberrant pDCs activation can cause adverse effects on the host and contributes to the pathogenesis of type I IFN-related autoimmune diseases. Here, we show that heparin interacts with the human pDCs-specific blood dendritic cell antigen 2 (BDCA-2) but not with related lectins such as DCIR or dectin-2. Importantly, BDCA-2-heparin interaction depends on heparin sulfation and receptor glycosylation and results in inhibition of TLR9-driven type I IFN production in primary human pDCs and the pDC-like cell line CAL-1. This inhibition is mediated by unfractionated and low-molecular-weight heparin, as well as endogenous heparin from plasma, suggesting that the local blood environment controls the production of IFN-α in pDCs. Additionally, we identified an activation-dependent soluble form of BDCA-2 (solBDCA-2) in human plasma that functions as heparin antagonist and thereby increases TLR9-driven IFN-α production in pDCs. Of importance, solBDCA-2 levels in the serum were increased in patients with scrub typhus (an acute infectious disease caused by Orientia tsutsugamushi) compared to healthy control subjects and correlated with anti-dsDNA antibodies titers. In contrast, solBDCA-2 levels in plasma from patients with bullous pemphigoid or psoriasis were reduced. In summary, this work identifies a regulatory network consisting of heparin, membrane-bound and solBDCA-2 modulating TLR9-driven IFN-α production in pDCs. This insight into pDCs function and regulation may have implications for the treatment of pDCs-related autoimmune diseases.
Assuntos
Doenças Autoimunes , Interferon Tipo I , Humanos , Interferon Tipo I/metabolismo , Heparina/metabolismo , Receptor Toll-Like 9/metabolismo , Células Dendríticas , Doenças Autoimunes/metabolismoRESUMO
miR-126 is a microRNA expressed predominately by endothelial cells and controls angiogenesis. We found miR-126 was required for the innate response to pathogen-associated nucleic acids and that miR-126-deficient mice had greater susceptibility to infection with pseudotyped HIV. Profiling of miRNA indicated that miR-126 had high and specific expression by plasmacytoid dendritic cells (pDCs). Moreover, miR-126 controlled the survival and function of pDCs and regulated the expression of genes encoding molecules involved in the innate response, including Tlr7, Tlr9 and Nfkb1, as well as Kdr, which encodes the growth factor receptor VEGFR2. Deletion of Kdr in DCs resulted in reduced production of type I interferon, which supports the proposal of a role for VEGFR2 in miR-126 regulation of pDCs. Our studies identify the miR-126-VEGFR2 axis as an important regulator of the innate response that operates through multiscale control of pDCs.
Assuntos
Células Dendríticas/imunologia , Imunidade Inata/imunologia , MicroRNAs/imunologia , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/imunologia , Animais , Células Dendríticas/metabolismo , Citometria de Fluxo , Infecções por HIV/imunologia , Infecções por HIV/virologia , Humanos , Imunidade Inata/genética , Immunoblotting , Interferon-alfa/sangue , Interferon-alfa/imunologia , Interferon-alfa/metabolismo , Camundongos , Camundongos Knockout , Camundongos Transgênicos , MicroRNAs/genética , MicroRNAs/metabolismo , Subunidade p50 de NF-kappa B/genética , Subunidade p50 de NF-kappa B/imunologia , Subunidade p50 de NF-kappa B/metabolismo , Ácidos Nucleicos/imunologia , Ácidos Nucleicos/metabolismo , Oligodesoxirribonucleotídeos/genética , Oligodesoxirribonucleotídeos/imunologia , Análise de Sequência com Séries de Oligonucleotídeos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Receptor 7 Toll-Like/genética , Receptor 7 Toll-Like/imunologia , Receptor 7 Toll-Like/metabolismo , Receptor Toll-Like 9/genética , Receptor Toll-Like 9/imunologia , Receptor Toll-Like 9/metabolismo , Transcriptoma/imunologia , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/genética , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/metabolismoRESUMO
Double-stranded DNA (dsDNA) in the cytoplasm triggers the production of interleukin 1ß (IL-1ß) as an antiviral host response, and deregulation of the pathways involved can promote inflammatory disease. Here we report a direct cytosolic interaction between the DNA-damage sensor Rad50 and the innate immune system adaptor CARD9. Transfection of dendritic cells with dsDNA or infection of dendritic cells with a DNA virus induced the formation of dsDNA-Rad50-CARD9 signaling complexes for activation of the transcription factor NF-κB and the generation of pro-IL-1ß. Primary cells conditionally deficient in Rad50 or lacking CARD9 consequently exhibited defective DNA-induced production of IL-1ß, and Card9(-/-) mice had impaired inflammatory responses after infection with a DNA virus in vivo. Our results define a cytosolic DNA-recognition pathway for inflammation and a physical and functional connection between a conserved DNA-damage sensor and the innate immune response to pathogens.
Assuntos
Proteínas Adaptadoras de Sinalização CARD/imunologia , Enzimas Reparadoras do DNA/imunologia , DNA Viral/imunologia , Proteínas de Ligação a DNA/imunologia , Interleucina-1beta/biossíntese , Vaccinia virus/imunologia , Hidrolases Anidrido Ácido , Proteínas Adaptadoras de Transdução de Sinal/imunologia , Animais , Proteína 10 de Linfoma CCL de Células B , Proteínas Adaptadoras de Sinalização CARD/genética , Linhagem Celular , Citosol/imunologia , Enzimas Reparadoras do DNA/genética , Proteínas de Ligação a DNA/genética , Células Dendríticas/imunologia , Ativação Enzimática , Humanos , Proteínas de Membrana/genética , Proteínas de Membrana/imunologia , Camundongos , Camundongos Knockout , NF-kappa B/imunologia , Transdução de Sinais , Receptor 4 Toll-Like/biossíntese , Receptor Toll-Like 9/biossíntese , Vaccinia virus/genéticaRESUMO
Activation of Toll-like receptor 7 (TLR7) can induce lupus in mice, whereas activation of TLR9 can prevent it, even though both receptors interact with myeloid differentiation primary response gene 88 (MyD88) for downstream signaling. How TLR9 triggers anti-inflammatory responses in autoimmunity is unclear. Leibler et al. recently reported that TLR9 initiates anti-inflammatory signaling and inhibits lupus pathogenesis in a MyD88-independent but ligand-dependent manner.
Assuntos
Fator 88 de Diferenciação Mieloide , Receptor Toll-Like 9 , Camundongos , Animais , Receptor Toll-Like 9/metabolismo , Fator 88 de Diferenciação Mieloide/genética , Fator 88 de Diferenciação Mieloide/metabolismo , Camundongos Knockout , Transdução de Sinais , Proteínas Adaptadoras de Transdução de Sinal , Receptor 7 Toll-Like/genética , Receptor 7 Toll-Like/metabolismo , Anti-InflamatóriosRESUMO
Although apoptotic cells (ACs) contain nucleic acids that can be recognized by Toll-like receptors (TLRs), engulfment of ACs does not initiate inflammation in healthy organisms. Here we identified macrophage populations that continually engulf ACs in distinct tissues and found that these macrophages share characteristics compatible with immunologically silent clearance of ACs; such characteristics include high expression of AC recognition receptors, low expression of TLR9, and reduced TLR responsiveness to nucleic acids. Removal of the macrophages from tissues resulted in loss of many of these characteristics and the ability to generate inflammatory responses to AC-derived nucleic acids, suggesting that cues from the tissue microenvironment program macrophages for silent AC clearance. The transcription factors KLF2 and KLF4 control the expression of many genes within this AC clearance program. The coordinated expression of AC receptors with genes that limit responses to nucleic acids might ensure maintenance of homeostasis and thus represent a central feature of tissue macrophages.