RESUMO
Pattern recognition receptors (PRRs) survey intra- and extracellular spaces for pathogen-associated molecular patterns (PAMPs) within microbial products of infection. Recognition and binding to cognate PAMP ligand by specific PRRs initiates signaling cascades that culminate in a coordinated intracellular innate immune response designed to control infection. In particular, our immune system has evolved specialized PRRs to discriminate viral nucleic acid from host. These are critical sensors of viral RNA to trigger innate immunity in the vertebrate host. Different families of PRRs of virus infection have been defined and reveal a diversity of PAMP specificity for wide viral pathogen coverage to recognize and extinguish virus infection. In this review, we discuss recent insights in pathogen recognition by the RIG-I-like receptors, related RNA helicases, Toll-like receptors, and other RNA sensor PRRs, to present emerging themes in innate immune signaling during virus infection.
Assuntos
Proteína DEAD-box 58/metabolismo , Interações Hospedeiro-Patógeno/genética , Interações Hospedeiro-Patógeno/imunologia , Viroses/etiologia , Viroses/metabolismo , Vírus/imunologia , Animais , RNA Helicases DEAD-box/metabolismo , Humanos , Processamento de Proteína Pós-Traducional , RNA Helicases/metabolismo , RNA Viral/genética , RNA Viral/metabolismo , Receptores Imunológicos , Transdução de Sinais , Receptores Toll-Like/metabolismoRESUMO
Cytosolic innate immune sensors are critical for host defense and form complexes, such as inflammasomes and PANoptosomes, that induce inflammatory cell death. The sensor NLRP12 is associated with infectious and inflammatory diseases, but its activating triggers and roles in cell death and inflammation remain unclear. Here, we discovered that NLRP12 drives inflammasome and PANoptosome activation, cell death, and inflammation in response to heme plus PAMPs or TNF. TLR2/4-mediated signaling through IRF1 induced Nlrp12 expression, which led to inflammasome formation to induce maturation of IL-1ß and IL-18. The inflammasome also served as an integral component of a larger NLRP12-PANoptosome that drove inflammatory cell death through caspase-8/RIPK3. Deletion of Nlrp12 protected mice from acute kidney injury and lethality in a hemolytic model. Overall, we identified NLRP12 as an essential cytosolic sensor for heme plus PAMPs-mediated PANoptosis, inflammation, and pathology, suggesting that NLRP12 and molecules in this pathway are potential drug targets for hemolytic and inflammatory diseases.
Assuntos
Inflamassomos , Moléculas com Motivos Associados a Patógenos , Animais , Camundongos , Inflamassomos/metabolismo , Heme , Inflamação , Piroptose , Peptídeos e Proteínas de Sinalização IntracelularRESUMO
Receptors of the innate immune system detect conserved determinants of microbial and viral origin. Activation of these receptors initiates signaling events that culminate in an effective immune response. Recently, the view that innate immune signaling events rely on and operate within a complex cellular infrastructure has become an important framework for understanding the regulation of innate immunity. Compartmentalization within this infrastructure provides the cell with the ability to assign spatial information to microbial detection and regulate immune responses. Several cell biological processes play a role in the regulation of innate signaling responses; at the same time, innate signaling can engage cellular processes as a form of defense or to promote immunological memory. In this review, we highlight these aspects of cell biology in pattern-recognition receptor signaling by focusing on signals that originate from the cell surface, from endosomal compartments, and from within the cytosol.
Assuntos
Imunidade Inata/fisiologia , Receptores de Reconhecimento de Padrão/metabolismo , Animais , Vias Biossintéticas , Membrana Celular/metabolismo , Endossomos/metabolismo , Humanos , Ligantes , Transdução de SinaisRESUMO
The diverse microbial populations constituting the intestinal microbiota promote immune development and differentiation, but because of their complex metabolic requirements and the consequent difficulty culturing them, they remained, until recently, largely uncharacterized and mysterious. In the last decade, deep nucleic acid sequencing platforms, new computational and bioinformatics tools, and full-genome characterization of several hundred commensal bacterial species facilitated studies of the microbiota and revealed that differences in microbiota composition can be associated with inflammatory, metabolic, and infectious diseases, that each human is colonized by a distinct bacterial flora, and that the microbiota can be manipulated to reduce and even cure some diseases. Different bacterial species induce distinct immune cell populations that can play pro- and anti-inflammatory roles, and thus the composition of the microbiota determines, in part, the level of resistance to infection and susceptibility to inflammatory diseases. This review summarizes recent work characterizing commensal microbes that contribute to the antimicrobial defense/inflammation axis.
Assuntos
Resistência à Doença/imunologia , Gastroenterite/imunologia , Gastroenterite/microbiologia , Microbioma Gastrointestinal/imunologia , Mucosa Intestinal/imunologia , Mucosa Intestinal/microbiologia , Imunidade Adaptativa , Animais , Doenças Autoimunes/imunologia , Doenças Autoimunes/metabolismo , Doenças Autoimunes/microbiologia , Biologia Computacional , Dieta , Suscetibilidade a Doenças , Gastroenterite/metabolismo , Interações Hospedeiro-Patógeno/imunologia , Humanos , Imunidade Inata , Imunidade nas Mucosas , Mucosa Intestinal/metabolismo , Metaboloma , Neoplasias/etiologia , Vitaminas/metabolismoRESUMO
TLR8 is among the highest-expressed pattern-recognition receptors in the human myeloid compartment, yet its mode of action is poorly understood. TLR8 engages two distinct ligand binding sites to sense RNA degradation products, although it remains unclear how these ligands are formed in cellulo in the context of complex RNA molecule sensing. Here, we identified the lysosomal endoribonuclease RNase T2 as a non-redundant upstream component of TLR8-dependent RNA recognition. RNase T2 activity is required for rendering complex single-stranded, exogenous RNA molecules detectable for TLR8. This is due to RNase T2's preferential cleavage of single-stranded RNA molecules between purine and uridine residues, which critically contributes to the supply of catabolic uridine and the generation of purine-2',3'-cyclophosphate-terminated oligoribonucleotides. Thus-generated molecules constitute agonistic ligands for the first and second binding pocket of TLR8. Together, these results establish the identity and origin of the RNA-derived molecular pattern sensed by TLR8.
Assuntos
Endorribonucleases/metabolismo , Proteólise , Receptor 8 Toll-Like/metabolismo , Motivos de Aminoácidos , Sequência de Bases , Linhagem Celular , Endorribonucleases/deficiência , Humanos , Modelos Moleculares , Monócitos/metabolismo , Células Mieloides/metabolismo , Isótopos de Nitrogênio , Oligonucleotídeos/metabolismo , Purinas/metabolismo , RNA/metabolismo , Staphylococcus aureus/metabolismo , Receptor 7 Toll-Like/metabolismo , Receptor 8 Toll-Like/agonistas , Receptor 8 Toll-Like/química , Uridina/metabolismoRESUMO
At mucosal surfaces, epithelial cells provide a structural barrier and an immune defense system. However, dysregulated epithelial responses can contribute to disease states. Here, we demonstrated that epithelial cell-intrinsic production of interleukin-23 (IL-23) triggers an inflammatory loop in the prevalent oral disease periodontitis. Epithelial IL-23 expression localized to areas proximal to the disease-associated microbiome and was evident in experimental models and patients with common and genetic forms of disease. Mechanistically, flagellated microbial species of the periodontitis microbiome triggered epithelial IL-23 induction in a TLR5 receptor-dependent manner. Therefore, unlike other Th17-driven diseases, non-hematopoietic-cell-derived IL-23 served as an initiator of pathogenic inflammation in periodontitis. Beyond periodontitis, analysis of publicly available datasets revealed the expression of epithelial IL-23 in settings of infection, malignancy, and autoimmunity, suggesting a broader role for epithelial-intrinsic IL-23 in human disease. Collectively, this work highlights an important role for the barrier epithelium in the induction of IL-23-mediated inflammation.
Assuntos
Interleucina-23 , Periodontite , Humanos , Células Epiteliais , Inflamação , Receptor 5 Toll-Like/metabolismoRESUMO
Toll-like receptor 7 (TLR7) is essential for recognition of RNA viruses and initiation of antiviral immunity. TLR7 contains two ligand-binding pockets that recognize different RNA degradation products: pocket 1 recognizes guanosine, while pocket 2 coordinates pyrimidine-rich RNA fragments. We found that the endonuclease RNase T2, along with 5' exonucleases PLD3 and PLD4, collaboratively generate the ligands for TLR7. Specifically, RNase T2 generated guanosine 2',3'-cyclic monophosphate-terminated RNA fragments. PLD exonuclease activity further released the terminal 2',3'-cyclic guanosine monophosphate (2',3'-cGMP) to engage pocket 1 and was also needed to generate RNA fragments for pocket 2. Loss-of-function studies in cell lines and primary cells confirmed the critical requirement for PLD activity. Biochemical and structural studies showed that PLD enzymes form homodimers with two ligand-binding sites important for activity. Previously identified disease-associated PLD mutants failed to form stable dimers. Together, our data provide a mechanistic basis for the detection of RNA fragments by TLR7.
Assuntos
Endorribonucleases , Receptor 7 Toll-Like , Receptor 7 Toll-Like/metabolismo , Receptor 7 Toll-Like/genética , Humanos , Endorribonucleases/metabolismo , Ligantes , Fosfolipase D/metabolismo , Fosfolipase D/genética , RNA/metabolismo , Células HEK293 , Lisossomos/metabolismo , Animais , Exonucleases/metabolismo , Camundongos , Sítios de LigaçãoRESUMO
Receptor-interacting serine/threonine-protein kinase 1 (RIPK1) functions as a critical stress sentinel that coordinates cell survival, inflammation, and immunogenic cell death (ICD). Although the catalytic function of RIPK1 is required to trigger cell death, its non-catalytic scaffold function mediates strong pro-survival signaling. Accordingly, cancer cells can hijack RIPK1 to block necroptosis and evade immune detection. We generated a small-molecule proteolysis-targeting chimera (PROTAC) that selectively degraded human and murine RIPK1. PROTAC-mediated depletion of RIPK1 deregulated TNFR1 and TLR3/4 signaling hubs, accentuating the output of NF-κB, MAPK, and IFN signaling. Additionally, RIPK1 degradation simultaneously promoted RIPK3 activation and necroptosis induction. We further demonstrated that RIPK1 degradation enhanced the immunostimulatory effects of radio- and immunotherapy by sensitizing cancer cells to treatment-induced TNF and interferons. This promoted ICD, antitumor immunity, and durable treatment responses. Consequently, targeting RIPK1 by PROTACs emerges as a promising approach to overcome radio- or immunotherapy resistance and enhance anticancer therapies.
Assuntos
Morte Celular Imunogênica , Proteólise , Proteína Serina-Treonina Quinases de Interação com Receptores , Transdução de Sinais , Proteína Serina-Treonina Quinases de Interação com Receptores/metabolismo , Humanos , Animais , Camundongos , Proteólise/efeitos dos fármacos , Linhagem Celular Tumoral , Transdução de Sinais/efeitos dos fármacos , Morte Celular Imunogênica/efeitos dos fármacos , Necroptose/efeitos dos fármacos , Necroptose/imunologia , Neoplasias/imunologia , Neoplasias/tratamento farmacológico , Camundongos Endogâmicos C57BL , Antineoplásicos/farmacologia , Imunoterapia/métodosRESUMO
Macrophages elicit immune responses to pathogens through induction of inflammatory genes. Here, we examined the role of three variants of the SWI/SNF nucleosome remodeling complex-cBAF, ncBAF, and PBAF-in the macrophage response to bacterial endotoxin (lipid A). All three SWI/SNF variants were prebound in macrophages and retargeted to genomic sites undergoing changes in chromatin accessibility following stimulation. Cooperative binding of all three variants associated with de novo chromatin opening and latent enhancer activation. Isolated binding of ncBAF and PBAF, in contrast, associated with activation and repression of active enhancers, respectively. Chemical and genetic perturbations of variant-specific subunits revealed pathway-specific regulation in the activation of lipid A response genes, corresponding to requirement for cBAF and ncBAF in inflammatory and interferon-stimulated gene (ISG) activation, respectively, consistent with differential engagement of SWI/SNF variants by signal-responsive transcription factors. Thus, functional diversity among SWI/SNF variants enables increased regulatory control of innate immune transcriptional programs, with potential for specific therapeutic targeting.
RESUMO
Serine metabolism is involved in the fate decisions of immune cells; however, whether and how de novo serine synthesis shapes innate immune cell function remain unknown. Here, we first demonstrated that inflammatory macrophages have high expression of phosphoglycerate dehydrogenase (PHGDH, the rate-limiting enzyme of de novo serine synthesis) via nuclear factor κB signaling. Notably, the pharmacological inhibition or genetic modulation of PHGDH limits macrophage interleukin (IL)-1ß production through NAD+ accumulation and subsequent NAD+-dependent SIRT1 and SIRT3 expression and activity. Mechanistically, PHGDH not only sustains IL-1ß expression through H3K9/27 acetylation-mediated transcriptional activation of Toll-like receptor 4 but also supports IL-1ß maturation via NLRP3-K21/22/24/ASC-K21/22/24 acetylation-mediated activation of the NLRP3 inflammasome. Moreover, mice with myeloid-specific depletion of Phgdh show alleviated inflammatory responses in lipopolysaccharide-induced systemic inflammation. This study reveals a network by which a metabolic enzyme, involved in de novo serine synthesis, mediates post-translational modifications and epigenetic regulation to orchestrate IL-1ß production, providing a potential inflammatory disease target.
Assuntos
NAD , Proteína 3 que Contém Domínio de Pirina da Família NLR , Animais , Camundongos , Acetilação , Epigênese Genética , Inflamassomos/metabolismo , Interleucina-1beta/genética , Interleucina-1beta/metabolismo , Macrófagos/metabolismo , NAD/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Processamento de Proteína Pós-Traducional , Serina/metabolismoRESUMO
The risk of chronic diseases caused by aging is reduced by caloric restriction (CR)-induced immunometabolic adaptation. Here, we found that the matricellular protein, secreted protein acidic and rich in cysteine (SPARC), was inhibited by 2 years of 14% sustained CR in humans and elevated by obesity. SPARC converted anti-inflammatory macrophages into a pro-inflammatory phenotype with induction of interferon-stimulated gene (ISG) expression via the transcription factors IRF3/7. Mechanistically, SPARC-induced ISGs were dependent on toll-like receptor-4 (TLR4)-mediated TBK1, IRF3, IFN-ß, and STAT1 signaling without engaging the Myd88 pathway. Metabolically, SPARC dampened mitochondrial respiration, and inhibition of glycolysis abrogated ISG induction by SPARC in macrophages. Furthermore, the N-terminal acidic domain of SPARC was required for ISG induction, while adipocyte-specific deletion of SPARC reduced inflammation and extended health span during aging. Collectively, SPARC, a CR-mimetic adipokine, is an immunometabolic checkpoint of inflammation and interferon response that may be targeted to delay age-related metabolic and functional decline.
Assuntos
Envelhecimento , Interferons , Macrófagos , Osteonectina , Humanos , Inflamação/metabolismo , Interferons/metabolismo , Macrófagos/metabolismo , Osteonectina/genética , Osteonectina/metabolismoRESUMO
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
Human toll-like receptor 8 (TLR8) activation induces a potent T helper-1 (Th1) cell response critical for defense against intracellular pathogens, including protozoa. The receptor harbors two distinct binding sites, uridine and di- and/or trinucleotides, but the RNases upstream of TLR8 remain poorly characterized. We identified two endolysosomal endoribonucleases, RNase T2 and RNase 2, that act synergistically to release uridine from oligoribonucleotides. RNase T2 cleaves preferentially before, and RNase 2 after, uridines. Live bacteria, P. falciparum-infected red blood cells, purified pathogen RNA, and synthetic oligoribonucleotides all required RNase 2 and T2 processing to activate TLR8. Uridine supplementation restored RNA recognition in RNASE2-/- or RNASET2-/- but not RNASE2-/-RNASET2-/- cells. Primary immune cells from RNase T2-hypomorphic patients lacked a response to bacterial RNA but responded robustly to small-molecule TLR8 ligands. Our data identify an essential function of RNase T2 and RNase 2 upstream of TLR8 and provide insight into TLR8 activation.
Assuntos
Endorribonucleases/metabolismo , Monócitos/imunologia , Neutrófilos/imunologia , RNA Bacteriano/metabolismo , RNA de Protozoário/metabolismo , Receptor 8 Toll-Like/metabolismo , Sistemas CRISPR-Cas , Linhagem Celular , Endorribonucleases/imunologia , Eritrócitos/imunologia , Eritrócitos/parasitologia , Escherichia coli/química , Escherichia coli/imunologia , Edição de Genes/métodos , Humanos , Listeria monocytogenes/química , Listeria monocytogenes/imunologia , Monócitos/microbiologia , Monócitos/parasitologia , Neutrófilos/microbiologia , Neutrófilos/parasitologia , Plasmodium falciparum/química , Plasmodium falciparum/imunologia , Cultura Primária de Células , Estabilidade de RNA , RNA Bacteriano/imunologia , RNA de Protozoário/imunologia , Serratia marcescens/química , Serratia marcescens/imunologia , Staphylococcus aureus/química , Staphylococcus aureus/imunologia , Streptococcus/química , Streptococcus/imunologia , Células THP-1 , Receptor 8 Toll-Like/imunologiaRESUMO
The development and functional potential of metazoan cells is dependent on combinatorial roles of transcriptional enhancers and promoters. Macrophages provide exceptionally powerful model systems for investigation of mechanisms underlying the activation of cell-specific enhancers that drive transitions in cell fate and cell state. Here, we review recent advances that have expanded appreciation of the diversity of macrophage phenotypes in health and disease, emphasizing studies of liver, adipose tissue, and brain macrophages as paradigms for other tissue macrophages and cell types. Studies of normal tissue-resident macrophages and macrophages associated with cirrhosis, obese adipose tissue, and neurodegenerative disease illustrate the major roles of tissue environment in remodeling enhancer landscapes to specify the development and functions of distinct macrophage phenotypes. We discuss the utility of quantitative analysis of environment-dependent changes in enhancer activity states as an approach to discovery of regulatory transcription factors and upstream signaling pathways.
Assuntos
Elementos Facilitadores Genéticos , Macrófagos/metabolismo , Microglia/metabolismo , Regiões Promotoras Genéticas , Fatores de Transcrição/genética , Ativação Transcricional , Animais , Linhagem da Célula , Microambiente Celular , Humanos , Macrófagos/patologia , Microglia/patologia , Fenótipo , Transdução de Sinais , Fatores de Transcrição/metabolismoRESUMO
Toll-like receptor (TLR) activation induces inflammatory responses in macrophages by activating temporally defined transcriptional cascades. Whether concurrent changes in the cellular metabolism that occur upon TLR activation influence the quality of the transcriptional responses remains unknown. Here, we investigated how macrophages adopt their metabolism early after activation to regulate TLR-inducible gene induction. Shortly after TLR4 activation, macrophages increased glycolysis and tricarboxylic acid (TCA) cycle volume. Metabolic tracing studies revealed that TLR signaling redirected metabolic fluxes to generate acetyl-Coenzyme A (CoA) from glucose resulting in augmented histone acetylation. Signaling through the adaptor proteins MyD88 and TRIF resulted in activation of ATP-citrate lyase, which in turn facilitated the induction of distinct LPS-inducible gene sets. We postulate that metabolic licensing of histone acetylation provides another layer of control that serves to fine-tune transcriptional responses downstream of TLR activation. Our work highlights the potential of targeting the metabolic-epigenetic axis in inflammatory settings.
Assuntos
ATP Citrato (pro-S)-Liase/metabolismo , Acetilcoenzima A/metabolismo , Histonas/metabolismo , Macrófagos/metabolismo , Receptor 4 Toll-Like/metabolismo , Acetilação , Proteínas Adaptadoras de Transporte Vesicular/genética , Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Animais , Ciclo do Ácido Cítrico/fisiologia , Glicólise/fisiologia , Humanos , Lipopolissacarídeos/metabolismo , Macrófagos/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fator 88 de Diferenciação Mieloide/genética , Fator 88 de Diferenciação Mieloide/metabolismo , Transdução de Sinais , Transcrição Gênica/genéticaRESUMO
Sepsis is a bi-phasic inflammatory disease that threatens approximately 30 million lives and claims over 14 million annually, yet little is known regarding the molecular switches and pathways that regulate this disease. Here, we have described ABCF1, an ATP-Binding Cassette (ABC) family member protein, which possesses an E2 ubiquitin enzyme activity, through which it controls the Lipopolysaccharide (LPS)- Toll-like Receptor-4 (TLR4) mediated gram-negative insult by targeting key proteins for K63-polyubiquitination. Ubiquitination by ABCF1 shifts the inflammatory profile from an early phase MyD88-dependent to a late phase TRIF-dependent signaling pathway, thereby regulating TLR4 endocytosis and modulating macrophage polarization from M1 to M2 phase. Physiologically, ABCF1 regulates the shift from the inflammatory phase of sepsis to the endotoxin tolerance phase, and modulates cytokine storm and interferon-ß (IFN-ß)-dependent production by the immunotherapeutic mediator, SIRT1. Consequently, ABCF1 controls sepsis induced mortality by repressing hypotension-induced renal circulatory dysfunction.
Assuntos
Transportadores de Cassetes de Ligação de ATP/imunologia , Macrófagos/imunologia , Sepse/imunologia , Choque Séptico/imunologia , Enzimas de Conjugação de Ubiquitina/imunologia , Transportadores de Cassetes de Ligação de ATP/genética , Transportadores de Cassetes de Ligação de ATP/metabolismo , Trifosfato de Adenosina/imunologia , Trifosfato de Adenosina/metabolismo , Animais , Citocinas/imunologia , Citocinas/metabolismo , Feminino , Interferon beta/imunologia , Interferon beta/metabolismo , Lipopolissacarídeos/administração & dosagem , Lipopolissacarídeos/imunologia , Ativação de Macrófagos/efeitos dos fármacos , Ativação de Macrófagos/genética , Ativação de Macrófagos/imunologia , Macrófagos/classificação , Macrófagos/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Interferência de RNA , Sepse/genética , Sepse/metabolismo , Choque Séptico/genética , Choque Séptico/metabolismo , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Transdução de Sinais/imunologia , Receptor 4 Toll-Like/imunologia , Receptor 4 Toll-Like/metabolismo , Enzimas de Conjugação de Ubiquitina/genética , Enzimas de Conjugação de Ubiquitina/metabolismo , Ubiquitinação/imunologiaRESUMO
Moraxella catarrhalis is an important human respiratory pathogen and a major causative agent of otitis media and chronic obstructive pulmonary disease. Toll-like receptors contribute to, but cannot fully account for, the complexity of the immune response seen in M. catarrhalis infection. Using primary mouse bone marrow-derived macrophages to examine the host response to M. catarrhalis infection, our global transcriptomic and targeted cytokine analyses revealed activation of immune signalling pathways by both membrane-bound and cytosolic pattern-recognition receptors. We show that M. catarrhalis and its outer membrane vesicles or lipooligosaccharide (LOS) can activate the cytosolic innate immune sensor caspase-4/11, gasdermin-D-dependent pyroptosis, and the NLRP3 inflammasome in human and mouse macrophages. This pathway is initiated by type I interferon signalling and guanylate-binding proteins (GBPs). We also show that inflammasomes and GBPs, particularly GBP2, are required for the host defence against M. catarrhalis in mice. Overall, our results reveal an essential role for the interferon-inflammasome axis in cytosolic recognition and immunity against M. catarrhalis, providing new molecular targets that may be used to mitigate pathological inflammation triggered by this pathogen.
Assuntos
Caspases , Inflamassomos , Camundongos , Humanos , Animais , Caspases/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Moraxella catarrhalis/metabolismo , Proteínas de Transporte , Imunidade InataRESUMO
Tight regulation of Toll-like receptor (TLR)-mediated inflammatory responses is important for innate immunity. Here, we show that T-cell death-associated gene 51 (TDAG51/PHLDA1) is a novel regulator of the transcription factor FoxO1, regulating inflammatory mediator production in the lipopolysaccharide (LPS)-induced inflammatory response. TDAG51 induction by LPS stimulation was mediated by the TLR2/4 signaling pathway in bone marrow-derived macrophages (BMMs). LPS-induced inflammatory mediator production was significantly decreased in TDAG51-deficient BMMs. In TDAG51-deficient mice, LPS- or pathogenic Escherichia coli infection-induced lethal shock was reduced by decreasing serum proinflammatory cytokine levels. The recruitment of 14-3-3ζ to FoxO1 was competitively inhibited by the TDAG51-FoxO1 interaction, leading to blockade of FoxO1 cytoplasmic translocation and thereby strengthening FoxO1 nuclear accumulation. TDAG51/FoxO1 double-deficient BMMs showed significantly reduced inflammatory mediator production compared with TDAG51- or FoxO1-deficient BMMs. TDAG51/FoxO1 double deficiency protected mice against LPS- or pathogenic E. coli infection-induced lethal shock by weakening the systemic inflammatory response. Thus, these results indicate that TDAG51 acts as a regulator of the transcription factor FoxO1, leading to strengthened FoxO1 activity in the LPS-induced inflammatory response.
Assuntos
Escherichia coli , Lipopolissacarídeos , Camundongos , Animais , Proteínas 14-3-3 , Fatores de Transcrição/genética , Mediadores da InflamaçãoRESUMO
Unc-93 homolog B1 (UNC93B1) is a key regulator of nucleic acid (NA)-sensing Toll-like receptors (TLRs). Loss of NA-sensing TLR responses in UNC93B1-deficient patients facilitates Herpes simplex virus type 1 (HSV-1) encephalitis. UNC93B1 is thought to guide NA-sensing TLRs from the endoplasmic reticulum (ER) to their respective endosomal signaling compartments and to guide the flagellin receptor TLR5 to the cell surface, raising the question of how UNC93B1 mediates differential TLR trafficking. Here, we report that UNC93B1 regulates a step upstream of the differential TLR trafficking process. We discovered that UNC93B1 deficiency resulted in near-complete loss of TLR3 and TLR7 proteins in primary splenic mouse dendritic cells and macrophages, showing that UNC93B1 is critical for maintaining TLR expression. Notably, expression of an ER-retained UNC93B1 version was sufficient to stabilize TLRs and largely restore endosomal TLR trafficking and activity. These data are critical for an understanding of how UNC93B1 can regulate the function of a broad subset of TLRs.
Assuntos
Endossomos/imunologia , Proteínas de Membrana Transportadoras/imunologia , Chaperonas Moleculares/imunologia , Receptores Toll-Like/imunologia , Animais , Células Dendríticas/imunologia , Células Dendríticas/metabolismo , Retículo Endoplasmático/imunologia , Retículo Endoplasmático/metabolismo , Endossomos/metabolismo , Células HEK293 , Humanos , Macrófagos/imunologia , Macrófagos/metabolismo , Proteínas de Membrana Transportadoras/genética , Proteínas de Membrana Transportadoras/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Estabilidade Proteica , Transporte Proteico/imunologia , Transdução de Sinais/genética , Transdução de Sinais/imunologia , Células THP-1 , Receptores Toll-Like/genética , Receptores Toll-Like/metabolismoRESUMO
Signaling by Toll-like receptors (TLRs) on intestinal epithelial cells (IECs) is critical for intestinal homeostasis. To visualize epithelial expression of individual TLRs in vivo, we generated five strains of reporter mice. These mice revealed that TLR expression varied dramatically along the length of the intestine. Indeed, small intestine (SI) IECs expressed low levels of multiple TLRs that were highly expressed by colonic IECs. TLR5 expression was restricted to Paneth cells in the SI epithelium. Intestinal organoid experiments revealed that TLR signaling in Paneth cells or colonic IECs induced a core set of host defense genes, but this set did not include antimicrobial peptides, which instead were induced indirectly by inflammatory cytokines. This comprehensive blueprint of TLR expression and function in IECs reveals unexpected diversity in the responsiveness of IECs to microbial stimuli, and together with the associated reporter strains, provides a resource for further study of innate immunity.