RESUMEN
Protective immune responses to viral infection are initiated by innate immune sensors that survey extracellular and intracellular space for foreign nucleic acids. The existence of these sensors raises fundamental questions about self/nonself discrimination because of the abundance of self-DNA and self-RNA that occupy these same compartments. Recent advances have revealed that enzymes that metabolize or modify endogenous nucleic acids are essential for preventing inappropriate activation of the innate antiviral response. In this review, we discuss rare human diseases caused by dysregulated nucleic acid sensing, focusing primarily on intracellular sensors of nucleic acids. We summarize lessons learned from these disorders, we rationalize the existence of these diseases in the context of evolution, and we propose that this framework may also apply to a number of more common autoimmune diseases for which the underlying genetics and mechanisms are not yet fully understood.
Asunto(s)
Enfermedades Autoinmunes del Sistema Nervioso/inmunología , Autoinmunidad , Lupus Eritematoso Sistémico/inmunología , Malformaciones del Sistema Nervioso/inmunología , Ácidos Nucleicos/inmunología , Virosis/inmunología , Animales , Humanos , Inmunidad Innata , Interferón Tipo I/metabolismo , Receptores Toll-Like/metabolismoRESUMEN
Mycobacterium tuberculosis (Mtb) causes 1.6 million deaths annually. Active tuberculosis correlates with a neutrophil-driven type I interferon (IFN) signature, but the cellular mechanisms underlying tuberculosis pathogenesis remain poorly understood. We found that interstitial macrophages (IMs) and plasmacytoid dendritic cells (pDCs) are dominant producers of type I IFN during Mtb infection in mice and non-human primates, and pDCs localize near human Mtb granulomas. Depletion of pDCs reduces Mtb burdens, implicating pDCs in tuberculosis pathogenesis. During IFN-driven disease, we observe abundant DNA-containing neutrophil extracellular traps (NETs) described to activate pDCs. Cell-type-specific disruption of the type I IFN receptor suggests that IFNs act on IMs to inhibit Mtb control. Single-cell RNA sequencing (scRNA-seq) indicates that type I IFN-responsive cells are defective in their response to IFNγ, a cytokine critical for Mtb control. We propose that pDC-derived type I IFNs act on IMs to permit bacterial replication, driving further neutrophil recruitment and active tuberculosis disease.
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Interferón Tipo I , Tuberculosis , Humanos , Ratones , Animales , Macrófagos/microbiología , Citocinas , Neutrófilos , Células DendríticasRESUMEN
Chronic stimulation can cause T cell dysfunction and limit the efficacy of cellular immunotherapies. Improved methods are required to compare large numbers of synthetic knockin (KI) sequences to reprogram cell functions. Here, we developed modular pooled KI screening (ModPoKI), an adaptable platform for modular construction of DNA KI libraries using barcoded multicistronic adaptors. We built two ModPoKI libraries of 100 transcription factors (TFs) and 129 natural and synthetic surface receptors (SRs). Over 30 ModPoKI screens across human TCR- and CAR-T cells in diverse conditions identified a transcription factor AP4 (TFAP4) construct that enhanced fitness of chronically stimulated CAR-T cells and anti-cancer function in vitro and in vivo. ModPoKI's modularity allowed us to generate an â¼10,000-member library of TF combinations. Non-viral KI of a combined BATF-TFAP4 polycistronic construct enhanced fitness. Overexpressed BATF and TFAP4 co-occupy and regulate key gene targets to reprogram T cell function. ModPoKI facilitates the discovery of complex gene constructs to program cellular functions.
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Tratamiento Basado en Trasplante de Células y Tejidos , Ejercicio Físico , Humanos , Biblioteca de Genes , Inmunoterapia , InvestigaciónRESUMEN
Monoclonal antibodies (mAbs) are a focus in vaccine and therapeutic design to counteract severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its variants. Here, we combined B cell sorting with single-cell VDJ and RNA sequencing (RNA-seq) and mAb structures to characterize B cell responses against SARS-CoV-2. We show that the SARS-CoV-2-specific B cell repertoire consists of transcriptionally distinct B cell populations with cells producing potently neutralizing antibodies (nAbs) localized in two clusters that resemble memory and activated B cells. Cryo-electron microscopy structures of selected nAbs from these two clusters complexed with SARS-CoV-2 spike trimers show recognition of various receptor-binding domain (RBD) epitopes. One of these mAbs, BG10-19, locks the spike trimer in a closed conformation to potently neutralize SARS-CoV-2, the recently arising mutants B.1.1.7 and B.1.351, and SARS-CoV and cross-reacts with heterologous RBDs. Together, our results characterize transcriptional differences among SARS-CoV-2-specific B cells and uncover cross-neutralizing Ab targets that will inform immunogen and therapeutic design against coronaviruses.
Asunto(s)
Anticuerpos Neutralizantes/inmunología , Linfocitos B/metabolismo , SARS-CoV-2/inmunología , Glicoproteína de la Espiga del Coronavirus/inmunología , Anticuerpos Monoclonales/química , Anticuerpos Monoclonales/inmunología , Anticuerpos Neutralizantes/sangre , Anticuerpos Neutralizantes/química , Anticuerpos Antivirales/sangre , Anticuerpos Antivirales/química , Anticuerpos Antivirales/inmunología , Complejo Antígeno-Anticuerpo/química , Complejo Antígeno-Anticuerpo/metabolismo , Reacciones Antígeno-Anticuerpo , Linfocitos B/citología , Linfocitos B/virología , COVID-19/patología , COVID-19/virología , Microscopía por Crioelectrón , Cristalografía por Rayos X , Perfilación de la Expresión Génica , Humanos , Inmunoglobulina A/inmunología , Región Variable de Inmunoglobulina/química , Región Variable de Inmunoglobulina/genética , Dominios Proteicos/inmunología , Multimerización de Proteína , Estructura Cuaternaria de Proteína , SARS-CoV-2/aislamiento & purificación , SARS-CoV-2/metabolismo , Análisis de Secuencia de ARN , Glicoproteína de la Espiga del Coronavirus/química , Glicoproteína de la Espiga del Coronavirus/genética , Glicoproteína de la Espiga del Coronavirus/metabolismoRESUMEN
Tissue homeostasis requires maintenance of functional integrity under stress. A central source of stress is mechanical force that acts on cells, their nuclei, and chromatin, but how the genome is protected against mechanical stress is unclear. We show that mechanical stretch deforms the nucleus, which cells initially counteract via a calcium-dependent nuclear softening driven by loss of H3K9me3-marked heterochromatin. The resulting changes in chromatin rheology and architecture are required to insulate genetic material from mechanical force. Failure to mount this nuclear mechanoresponse results in DNA damage. Persistent, high-amplitude stretch induces supracellular alignment of tissue to redistribute mechanical energy before it reaches the nucleus. This tissue-scale mechanoadaptation functions through a separate pathway mediated by cell-cell contacts and allows cells/tissues to switch off nuclear mechanotransduction to restore initial chromatin state. Our work identifies an unconventional role of chromatin in altering its own mechanical state to maintain genome integrity in response to deformation.
Asunto(s)
Núcleo Celular/fisiología , Heterocromatina/fisiología , Mecanotransducción Celular/fisiología , Animales , Línea Celular , Núcleo Celular/metabolismo , Cromatina/metabolismo , Cromatina/fisiología , Heterocromatina/metabolismo , Humanos , Masculino , Mecanorreceptores/fisiología , Células Madre Mesenquimatosas , Ratones , Estrés MecánicoRESUMEN
Obesity is a major modifiable risk factor for pancreatic ductal adenocarcinoma (PDAC), yet how and when obesity contributes to PDAC progression is not well understood. Leveraging an autochthonous mouse model, we demonstrate a causal and reversible role for obesity in early PDAC progression, showing that obesity markedly enhances tumorigenesis, while genetic or dietary induction of weight loss intercepts cancer development. Molecular analyses of human and murine samples define microenvironmental consequences of obesity that foster tumorigenesis rather than new driver gene mutations, including significant pancreatic islet cell adaptation in obesity-associated tumors. Specifically, we identify aberrant beta cell expression of the peptide hormone cholecystokinin (Cck) in response to obesity and show that islet Cck promotes oncogenic Kras-driven pancreatic ductal tumorigenesis. Our studies argue that PDAC progression is driven by local obesity-associated changes in the tumor microenvironment and implicate endocrine-exocrine signaling beyond insulin in PDAC development.
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Carcinoma Ductal Pancreático/etiología , Carcinoma Ductal Pancreático/metabolismo , Obesidad/metabolismo , Animales , Carcinogénesis/genética , Carcinoma Ductal Pancreático/patología , Línea Celular , Línea Celular Tumoral , Transformación Celular Neoplásica/genética , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Células Endocrinas/metabolismo , Glándulas Exocrinas/metabolismo , Femenino , Regulación Neoplásica de la Expresión Génica/genética , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Mutación/genética , Obesidad/genética , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/patología , Transducción de Señal/genética , Microambiente Tumoral/fisiología , Neoplasias PancreáticasRESUMEN
Extracellular acidification occurs in inflamed tissue and the tumor microenvironment; however, a systematic study on how pH sensing contributes to tissue homeostasis is lacking. In the present study, we examine cell type-specific roles of the pH sensor G protein-coupled receptor 65 (GPR65) and its inflammatory disease-associated Ile231Leu-coding variant in inflammation control. GPR65 Ile231Leu knock-in mice are highly susceptible to both bacterial infection-induced and T cell-driven colitis. Mechanistically, GPR65 Ile231Leu elicits a cytokine imbalance through impaired helper type 17 T cell (TH17 cell) and TH22 cell differentiation and interleukin (IL)-22 production in association with altered cellular metabolism controlled through the cAMP-CREB-DGAT1 axis. In dendritic cells, GPR65 Ile231Leu elevates IL-12 and IL-23 release at acidic pH and alters endo-lysosomal fusion and degradation capacity, resulting in enhanced antigen presentation. The present study highlights GPR65 Ile231Leu as a multistep risk factor in intestinal inflammation and illuminates a mechanism by which pH sensing controls inflammatory circuits and tissue homeostasis.
Asunto(s)
Colitis , Receptores Acoplados a Proteínas G , Animales , Colitis/metabolismo , Concentración de Iones de Hidrógeno , Inflamación/metabolismo , Lisosomas/metabolismo , Ratones , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/metabolismo , Células Th17/metabolismoRESUMEN
A proportion of patients surviving acute coronavirus disease 2019 (COVID-19) infection develop post-acute COVID syndrome (long COVID (LC)) lasting longer than 12 weeks. Here, we studied individuals with LC compared to age- and gender-matched recovered individuals without LC, unexposed donors and individuals infected with other coronaviruses. Patients with LC had highly activated innate immune cells, lacked naive T and B cells and showed elevated expression of type I IFN (IFN-ß) and type III IFN (IFN-λ1) that remained persistently high at 8 months after infection. Using a log-linear classification model, we defined an optimal set of analytes that had the strongest association with LC among the 28 analytes measured. Combinations of the inflammatory mediators IFN-ß, PTX3, IFN-γ, IFN-λ2/3 and IL-6 associated with LC with 78.5-81.6% accuracy. This work defines immunological parameters associated with LC and suggests future opportunities for prevention and treatment.
Asunto(s)
Linfocitos B/inmunología , COVID-19/complicaciones , Inmunidad Innata , SARS-CoV-2/inmunología , Linfocitos T/inmunología , Adulto , Anciano , Linfocitos B/metabolismo , Linfocitos B/virología , Biomarcadores/sangre , COVID-19/sangre , COVID-19/inmunología , COVID-19/virología , Estudios de Casos y Controles , Citocinas/sangre , Femenino , Interacciones Huésped-Patógeno , Humanos , Mediadores de Inflamación/sangre , Masculino , Persona de Mediana Edad , Pronóstico , SARS-CoV-2/patogenicidad , Índice de Severidad de la Enfermedad , Linfocitos T/metabolismo , Linfocitos T/virología , Factores de Tiempo , Síndrome Post Agudo de COVID-19RESUMEN
The current understanding of inflammatory bowel disease (IBD) pathogenesis implicates a complex interaction between host genetics, host immunity, microbiome, and environmental exposures. Mechanisms gleaned from genetics and molecular pathogenesis offer clues to the critical triggers of mucosal inflammation and guide the development of therapeutic interventions. A complex network of interactions between host genetic factors, microbes, and microbial metabolites governs intestinal homeostasis, making classification and mechanistic dissection of involved pathways challenging. In this Review, we discuss these challenges, areas of active translation, and opportunities for development of next-generation therapies.
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Enfermedades Inflamatorias del Intestino/patología , Microbiota , Inmunidad Adaptativa , Animales , Bacterias/genética , Bacterias/metabolismo , Productos Biológicos/farmacología , Citocinas/genética , Citocinas/metabolismo , Humanos , Enfermedades Inflamatorias del Intestino/genética , Enfermedades Inflamatorias del Intestino/microbiología , Intestinos/inmunología , Intestinos/microbiología , Microbiota/efectos de los fármacos , Linfocitos T/inmunología , Linfocitos T/metabolismoRESUMEN
Group II introns are a class of retroelements that invade DNA through a copy-and-paste mechanism known as retrotransposition. Their coordinated activities occur within a complex that includes a maturase protein, which promotes splicing through an unknown mechanism. The mechanism of splice site exchange within the RNA active site during catalysis also remains unclear. We determined two cryo-EM structures at 3.6-Å resolution of a group II intron reverse splicing into DNA. These structures reveal that the branch-site domain VI helix swings 90°, enabling substrate exchange during DNA integration. The maturase assists catalysis through a transient RNA-protein contact with domain VI that positions the branch-site adenosine for lariat formation during forward splicing. These findings provide the first direct evidence of the role the maturase plays during group II intron catalysis. The domain VI dynamics closely parallel spliceosomal branch-site helix movement and provide strong evidence for a retroelement origin of the spliceosome.
Asunto(s)
Empalme del ARN , ADN Polimerasa Dirigida por ARN/química , ARN/química , Dominio Catalítico , Microscopía por Crioelectrón , Escherichia coli/genética , Escherichia coli/metabolismo , Conformación de Ácido Nucleico , Estructura Terciaria de Proteína , ARN/metabolismo , ADN Polimerasa Dirigida por ARN/metabolismo , Retroelementos , Empalmosomas/químicaRESUMEN
Genome-wide association studies (GWAS) have revealed risk alleles for ulcerative colitis (UC). To understand their cell type specificities and pathways of action, we generate an atlas of 366,650 cells from the colon mucosa of 18 UC patients and 12 healthy individuals, revealing 51 epithelial, stromal, and immune cell subsets, including BEST4+ enterocytes, microfold-like cells, and IL13RA2+IL11+ inflammatory fibroblasts, which we associate with resistance to anti-TNF treatment. Inflammatory fibroblasts, inflammatory monocytes, microfold-like cells, and T cells that co-express CD8 and IL-17 expand with disease, forming intercellular interaction hubs. Many UC risk genes are cell type specific and co-regulated within relatively few gene modules, suggesting convergence onto limited sets of cell types and pathways. Using this observation, we nominate and infer functions for specific risk genes across GWAS loci. Our work provides a framework for interrogating complex human diseases and mapping risk variants to cell types and pathways.
Asunto(s)
Colitis Ulcerosa/patología , Colon/metabolismo , Adulto , Anciano , Anticuerpos Monoclonales/uso terapéutico , Bestrofinas/metabolismo , Antígenos CD8/metabolismo , Estudios de Casos y Controles , Colitis Ulcerosa/tratamiento farmacológico , Colitis Ulcerosa/metabolismo , Colon/patología , Enterocitos/citología , Enterocitos/metabolismo , Femenino , Sitios Genéticos , Estudio de Asociación del Genoma Completo , Humanos , Interleucina-17/metabolismo , Masculino , Persona de Mediana Edad , Factores de Riesgo , Linfocitos T/citología , Linfocitos T/metabolismo , Trombospondinas/metabolismo , Factor de Necrosis Tumoral alfa/inmunología , Factor de Necrosis Tumoral alfa/metabolismo , Adulto JovenRESUMEN
The cGAS-STING intracellular DNA-sensing pathway has emerged as a key element of innate antiviral immunity and a promising therapeutic target. The existence of an innate immune sensor that can be activated by any double-stranded DNA (dsDNA) of any origin raises fundamental questions about how cGAS is regulated and how it responds to "foreign" DNA while maintaining tolerance to ubiquitous self-DNA. In this review, we summarize recent evidence implicating important roles for cGAS in the detection of foreign and self-DNA. We describe two recent and surprising insights into cGAS-STING biology: that cGAS is tightly tethered to the nucleosome and that the cGAMP product of cGAS is an immunotransmitter acting at a distance to control innate immunity. We consider how these advances influence our understanding of the emerging roles of cGAS in the DNA damage response (DDR), senescence, aging, and cancer biology. Finally, we describe emerging approaches to harness cGAS-STING biology for therapeutic benefit.
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Nucleotidiltransferasas , Transducción de Señal , Nucleotidiltransferasas/metabolismo , Inmunidad Innata , ADNRESUMEN
In the small intestine, a niche of accessory cell types supports the generation of mature epithelial cell types from intestinal stem cells (ISCs). It is unclear, however, if and how immune cells in the niche affect ISC fate or the balance between self-renewal and differentiation. Here, we use single-cell RNA sequencing (scRNA-seq) to identify MHC class II (MHCII) machinery enrichment in two subsets of Lgr5+ ISCs. We show that MHCII+ Lgr5+ ISCs are non-conventional antigen-presenting cells in co-cultures with CD4+ T helper (Th) cells. Stimulation of intestinal organoids with key Th cytokines affects Lgr5+ ISC renewal and differentiation in opposing ways: pro-inflammatory signals promote differentiation, while regulatory cells and cytokines reduce it. In vivo genetic perturbation of Th cells or MHCII expression on Lgr5+ ISCs impacts epithelial cell differentiation and IEC fate during infection. These interactions between Th cells and Lgr5+ ISCs, thus, orchestrate tissue-wide responses to external signals.
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Diferenciación Celular , Autorrenovación de las Células , Interleucina-10/metabolismo , Células Madre/citología , Linfocitos T Colaboradores-Inductores/metabolismo , Animales , Diferenciación Celular/efectos de los fármacos , Autorrenovación de las Células/efectos de los fármacos , Citocinas/farmacología , Células Epiteliales/citología , Células Epiteliales/metabolismo , Femenino , Antígenos de Histocompatibilidad Clase II/metabolismo , Sistema Inmunológico/metabolismo , Intestinos/citología , Intestinos/microbiología , Masculino , Ratones , Ratones Endogámicos C57BL , Organoides/citología , Organoides/efectos de los fármacos , Organoides/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Salmonella enterica/patogenicidad , Células Madre/metabolismo , Linfocitos T Colaboradores-Inductores/citologíaRESUMEN
Crohn's disease (CD) is a chronic gastrointestinal disease that is increasing in prevalence worldwide. CD is multifactorial, involving the complex interplay of genetic, immune, and environmental factors, necessitating a system-level understanding of its etiology. To characterize cell-type-specific transcriptional heterogeneity in active CD, we profiled 720,633 cells from the terminal ileum and colon of 71 donors with varying inflammation status. Our integrated datasets revealed organ- and compartment-specific responses to acute and chronic inflammation; most immune changes were in cell composition, whereas transcriptional changes dominated among epithelial and stromal cells. These changes correlated with endoscopic inflammation, but small and large intestines exhibited distinct responses, which were particularly apparent when focusing on IBD risk genes. Finally, we mapped markers of disease-associated myofibroblast activation and identified CHMP1A, TBX3, and RNF168 as regulators of fibrotic complications. Altogether, our results provide a roadmap for understanding cell-type- and organ-specific differences in CD and potential directions for therapeutic development.
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Enfermedad de Crohn , Humanos , Transcriptoma , Colon , Íleon , Inflamación/genética , Ubiquitina-Proteína Ligasas/genéticaRESUMEN
CD4+ T cell responses are exquisitely antigen specific and directed toward peptide epitopes displayed by human leukocyte antigen class II (HLA-II) on antigen-presenting cells. Underrepresentation of diverse alleles in ligand databases and an incomplete understanding of factors affecting antigen presentation in vivo have limited progress in defining principles of peptide immunogenicity. Here, we employed monoallelic immunopeptidomics to identify 358,024 HLA-II binders, with a particular focus on HLA-DQ and HLA-DP. We uncovered peptide-binding patterns across a spectrum of binding affinities and enrichment of structural antigen features. These aspects underpinned the development of context-aware predictor of T cell antigens (CAPTAn), a deep learning model that predicts peptide antigens based on their affinity to HLA-II and full sequence of their source proteins. CAPTAn was instrumental in discovering prevalent T cell epitopes from bacteria in the human microbiome and a pan-variant epitope from SARS-CoV-2. Together CAPTAn and associated datasets present a resource for antigen discovery and the unraveling genetic associations of HLA alleles with immunopathologies.
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COVID-19 , Aprendizaje Profundo , Humanos , Captano , SARS-CoV-2 , Antígenos HLA , Epítopos de Linfocito T , PéptidosRESUMEN
The DNA sensor cyclic GMP-AMP synthase (cGAS) is important for antiviral and anti-tumor immunity. cGAS generates cyclic GMP-AMP (cGAMP), a diffusible cyclic dinucleotide that activates the antiviral response through the adaptor protein stimulator of interferon genes (STING). cGAMP cannot passively cross cell membranes, but recent advances have established a role for extracellular cGAMP as an "immunotransmitter" that can be imported into cells. However, the mechanism by which cGAMP exits cells remains unknown. Here, we identifed ABCC1 as a direct, ATP-dependent cGAMP exporter in mouse and human cells. We show that ABCC1 overexpression enhanced cGAMP export and limited STING signaling and that loss of ABCC1 reduced cGAMP export and potentiated STING signaling. We demonstrate that ABCC1 deficiency exacerbated cGAS-dependent autoimmunity in the Trex1-/- mouse model of Aicardi-Goutières syndrome. Thus, ABCC1-mediated cGAMP export is a key regulatory mechanism that limits cell-intrinsic activation of STING and ameliorates STING-dependent autoimmune disease.
Asunto(s)
Proteínas de Transporte de Membrana , Proteínas Asociadas a Resistencia a Múltiples Medicamentos , Nucleótidos Cíclicos , Adenosina Trifosfato , Animales , ADN/metabolismo , Humanos , Interferones/metabolismo , Proteínas de Transporte de Membrana/genética , Proteínas de Transporte de Membrana/metabolismo , Ratones , Proteínas Asociadas a Resistencia a Múltiples Medicamentos/genética , Proteínas Asociadas a Resistencia a Múltiples Medicamentos/metabolismo , Nucleótidos Cíclicos/metabolismo , Nucleotidiltransferasas/genética , Nucleotidiltransferasas/metabolismoRESUMEN
Reciprocal interactions between host T helper cells and gut microbiota enforce local immunological tolerance and modulate extra-intestinal immunity. However, our understanding of antigen-specific tolerance to the microbiome is limited. Here, we developed a systematic approach to predict HLA class-II-specific epitopes using the humanized bacteria-originated T cell antigen (hBOTA) algorithm. We identified a diverse set of microbiome epitopes spanning all major taxa that are compatible with presentation by multiple HLA-II alleles. In particular, we uncovered an immunodominant epitope from the TonB-dependent receptor SusC that was universally recognized and ubiquitous among Bacteroidales. In healthy human subjects, SusC-reactive T cell responses were characterized by IL-10-dominant cytokine profiles, whereas in patients with active Crohn's disease, responses were associated with elevated IL-17A. Our results highlight the potential of targeted antigen discovery within the microbiome to reveal principles of tolerance and functional transitions during inflammation.
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Enfermedad de Crohn , Epítopos Inmunodominantes , Linfocitos T CD4-Positivos , Epítopos de Linfocito T , Humanos , Interleucina-10 , Interleucina-17RESUMEN
Chung et al. recently presented the structure of a primitive group IIC intron with its DNA target, which reveals the structural requirements that this class of intron uses to recognize a transcription terminator stem loop at the DNA level for insertion during retrotransposition.
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ADN , Transcripción Genética , Intrones/genética , Secuencia de Bases , ADN Bacteriano/genética , Regiones Terminadoras Genéticas/genéticaRESUMEN
The RNA deaminase ADAR1 is an essential negative regulator of the RNA sensor MDA5, and loss of ADAR1 function triggers inappropriate activation of MDA5 by self-RNAs. Mutations in ADAR, the gene that encodes ADAR1, cause human immune diseases, including Aicardi-Goutières syndrome (AGS). However, the mechanisms of MDA5-dependent disease pathogenesis in vivo remain unknown. Here we generated mice with a single amino acid change in ADAR1 that models the most common human ADAR AGS mutation. These Adar mutant mice developed lethal disease that required MDA5, the RIG-I-like receptor LGP2, type I interferons, and the eIF2α kinase PKR. A small-molecule inhibitor of the integrated stress response (ISR) that acts downstream of eIF2α phosphorylation prevented immunopathology and rescued the mice from mortality. These findings place PKR and the ISR as central components of immunopathology in vivo and identify therapeutic targets for treatment of human diseases associated with the ADAR1-MDA5 axis.
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Adenosina Desaminasa/metabolismo , Enfermedades Autoinmunes del Sistema Nervioso/patología , Malformaciones del Sistema Nervioso/patología , Estrés Fisiológico/fisiología , eIF-2 Quinasa/metabolismo , Células A549 , Animales , Enfermedades Autoinmunes del Sistema Nervioso/genética , Enfermedades Autoinmunes del Sistema Nervioso/metabolismo , Modelos Animales de Enfermedad , Células HEK293 , Humanos , Ratones , Ratones Mutantes , Mutación , Malformaciones del Sistema Nervioso/genética , Malformaciones del Sistema Nervioso/metabolismoRESUMEN
Cellular lipid requirements are achieved through a combination of biosynthesis and import programs. Using isotope tracer analysis, we show that type I interferon (IFN) signaling shifts the balance of these programs by decreasing synthesis and increasing import of cholesterol and long chain fatty acids. Genetically enforcing this metabolic shift in macrophages is sufficient to render mice resistant to viral challenge, demonstrating the importance of reprogramming the balance of these two metabolic pathways in vivo. Unexpectedly, mechanistic studies reveal that limiting flux through the cholesterol biosynthetic pathway spontaneously engages a type I IFN response in a STING-dependent manner. The upregulation of type I IFNs was traced to a decrease in the pool size of synthesized cholesterol and could be inhibited by replenishing cells with free cholesterol. Taken together, these studies delineate a metabolic-inflammatory circuit that links perturbations in cholesterol biosynthesis with activation of innate immunity.