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Developmental Medicine and Child... Jan 2020Comprehensive reviews of the clinical characteristics and pathogenesis of Aicardi-Goutières syndrome (AGS), particularly its contextualization within a putative type I... (Review)
Review
Comprehensive reviews of the clinical characteristics and pathogenesis of Aicardi-Goutières syndrome (AGS), particularly its contextualization within a putative type I interferonopathy framework, already exist. However, recent reports of attempts at treatment suggest that an assessment of the field from a therapeutic perspective is warranted at this time. Here, we briefly summarize the neurological phenotypes associated with mutations in the seven genes so far associated with AGS, rehearse current knowledge of the pathology as it relates to possible treatment approaches, critically appraise the potential utility of therapies, and discuss the challenges in assessing clinical efficacy. WHAT THIS PAPER ADDS: Progress in understanding AGS disease pathogenesis has led to the first attempts at targeted treatment. Further rational therapies are expected to become available in the short- to medium-term.
Topics: Autoimmune Diseases of the Nervous System; Humans; Nervous System Malformations
PubMed: 31175662
DOI: 10.1111/dmcn.14268 -
Nature Reviews. Molecular Cell Biology Apr 2022Double-stranded RNA (dsRNA) is associated with most viral infections - it either constitutes the viral genome (in the case of dsRNA viruses) or is generated in host... (Review)
Review
Double-stranded RNA (dsRNA) is associated with most viral infections - it either constitutes the viral genome (in the case of dsRNA viruses) or is generated in host cells during viral replication. Hence, nearly all organisms have the capability of recognizing dsRNA and mounting a response, the primary aim of which is to mitigate the potential infection. In vertebrates, a set of innate immune receptors for dsRNA induce a multitude of cell-intrinsic and cell-extrinsic immune responses upon dsRNA recognition. Notably, recent studies showed that vertebrate cells can accumulate self-derived dsRNAs or dsRNA-like species upon dysregulation of several cellular processes, activating the very same immune pathways as in infected cells. On the one hand, such aberrant immune activation in the absence of infection can lead to pathogenesis of immune disorders, such as Aicardi-Goutières syndrome. On the other hand, the same innate immune reaction can be induced in a controlled setting for a therapeutic benefit, as occurs in immunotherapies. In this Review, we describe mechanisms by which immunostimulatory dsRNAs are generated in mammalian cells, either by viruses or by the host cells, and how cells respond to them, with the focus on recent developments regarding the role of cellular dsRNAs in immune modulation.
Topics: Animals; Autoimmune Diseases of the Nervous System; Immunity, Innate; Mammals; Nervous System Malformations; RNA, Double-Stranded; Virus Diseases; Virus Replication
PubMed: 34815573
DOI: 10.1038/s41580-021-00430-1 -
Neurological Sciences : Official... Nov 2019Basal ganglia calcifications could be incidental findings up to 20% of asymptomatic patients undergoing CT or MRI scan. The presence of neuropsychiatric symptoms... (Review)
Review
Basal ganglia calcifications could be incidental findings up to 20% of asymptomatic patients undergoing CT or MRI scan. The presence of neuropsychiatric symptoms associated with bilateral basal ganglia calcifications (which could occur in other peculiar brain structures, such as dentate nuclei) identifies a clinical picture defined as Fahr's Disease. This denomination mainly refers to idiopathic forms in which no metabolic or other underlying causes are identified. Recently, mutations in four different genes (SLC20A2, PDGFRB, PDGFB, and XPR1) were identified, together with novel mutations in the Myogenic Regulating Glycosylase gene, causing the occurrence of movement disorders, cognitive decline, and psychiatric symptoms. On the other hand, secondary forms, also identified as Fahr's syndrome, have been associated with different conditions: endocrine abnormalities of PTH, such as hypoparathyroidism, other genetically determined conditions, brain infections, or toxic exposure. The underlying pathophysiology seems to be related to an abnormal calcium/phosphorus homeostasis and transportation and alteration of the blood-brain barrier.
Topics: Autoimmune Diseases of the Nervous System; Basal Ganglia Diseases; Calcinosis; Cockayne Syndrome; Humans; Hypoparathyroidism; Lupus Vasculitis, Central Nervous System; Mitochondrial Diseases; Nervous System Malformations; Neurodegenerative Diseases; Neurotoxicity Syndromes; Pseudohypoparathyroidism; Xenotropic and Polytropic Retrovirus Receptor
PubMed: 31267306
DOI: 10.1007/s10072-019-03998-x -
Immunity Oct 2022The 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...
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.
Topics: Adenosine Triphosphate; Animals; DNA; Humans; Interferons; Membrane Transport Proteins; Mice; Multidrug Resistance-Associated Proteins; Nucleotides, Cyclic; Nucleotidyltransferases
PubMed: 36070769
DOI: 10.1016/j.immuni.2022.08.006 -
Wiley Interdisciplinary Reviews. RNA Jan 2022Adenosine deaminase acting on RNA (ADAR) catalyzes the posttranscriptional conversion of adenosine to inosine in double-stranded RNA (dsRNA), which can lead to the... (Review)
Review
Adenosine deaminase acting on RNA (ADAR) catalyzes the posttranscriptional conversion of adenosine to inosine in double-stranded RNA (dsRNA), which can lead to the creation of missense mutations in coding sequences. Recent studies show that editing-dependent functions of ADAR1 protect dsRNA from dsRNA-sensing molecules and inhibit innate immunity and the interferon-mediated response. Deficiency in these ADAR1 functions underlie the pathogenesis of autoinflammatory diseases such as the type I interferonopathies Aicardi-Goutieres syndrome and dyschromatosis symmetrica hereditaria. ADAR1-mediated editing of endogenous coding and noncoding RNA as well as ADAR1 editing-independent interactions with DICER can also have oncogenic or tumor suppressive effects that affect tumor proliferation, invasion, and response to immunotherapy. The combination of proviral and antiviral roles played by ADAR1 in repressing the interferon response and editing viral RNAs alters viral morphogenesis and cell susceptibility to infection. This review analyzes the structure and function of ADAR1 with a focus on its position in human disease pathways and the mechanisms of its disease-associated effects. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Processing > RNA Editing and Modification RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
Topics: Adenosine Deaminase; Autoimmune Diseases of the Nervous System; Humans; Inosine; Nervous System Malformations; RNA Editing; RNA, Double-Stranded; RNA-Binding Proteins
PubMed: 34105255
DOI: 10.1002/wrna.1665 -
CNS Drugs Mar 2021Cannabidiol (CBD), which is one major constituent of the Cannabis sativa plant, has anti-seizure properties and does not produce euphoric or intrusive side effects. A...
BACKGROUND
Cannabidiol (CBD), which is one major constituent of the Cannabis sativa plant, has anti-seizure properties and does not produce euphoric or intrusive side effects. A plant-derived, highly purified CBD formulation with a known and constant composition has been approved by the US Food and Drug Administration for the treatment of seizures associated with Dravet syndrome, Lennox-Gastaut syndrome, and tuberous sclerosis complex. In the European Union, the drug has been authorized by the European Medicines Agency for the treatment of seizures associated with Dravet syndrome and Lennox-Gastaut syndrome, in conjunction with clobazam, and is under regulatory review for the treatment of seizures in patients with tuberous sclerosis complex.
OBJECTIVES
This systematic review aimed to summarize the currently available body of knowledge about the use of this US Food and Drug Administration/European Medicines Agency-approved oral formulation of pharmaceutical-grade CBD in patients with epileptic conditions, especially developmental and epileptic encephalopathies other than Dravet syndrome and Lennox-Gastaut syndrome.
METHODS
The relevant studies were identified through MEDLINE and the US National Institutes of Health Clinical Trials Registry in October 2020. There were no date limitations or language restrictions. The following types of studies were included: clinical trials, cohorts, case-control, cross-sectional, clinical series, and case reports. Participants had to meet the following criteria: any sex, any ethnicity, any age, diagnosis of epilepsy, receiving plant-derived, highly purified (> 98% w/w) CBD in a sesame oil-based oral solution for the treatment of seizures. Data extracted from selected records included efficacy, tolerability, and safety outcomes.
RESULTS
Five hundred and seventy records were identified by database and trial register searching. Fifty-seven studies were retrieved for detailed assessment, of which 42 were eventually included for the review. The participants of the studies included patients of both pediatric and adult age. Across the trials, purified CBD was administered at dosages up to 50 mg/kg/day. In a randomized double-blind controlled trial in patients with tuberous sclerosis complex, CBD was associated with a significantly greater percent reduction in seizure frequency than placebo over the treatment period. Open-label studies suggested the effectiveness of CBD in the treatment of children and adults presenting with other epilepsy syndromes than those addressed by regulatory trials, including CDKL5 deficiency disorder and Aicardi, Dup15q, and Doose syndromes, SYNGAP1 encephalopathy, and epilepsy with myoclonic absences. The most common adverse events observed during treatment with CBD included somnolence, decreased appetite, diarrhea, and increased serum aminotransferases.
CONCLUSIONS
The currently available data suggest that response to treatment with a highly purified, plant-derived CBD oil-based solution can be seen in patients across a broad range of epilepsy disorders and etiologies. The existing evidence can provide preliminary support for additional research.
Topics: Anticonvulsants; Cannabidiol; Case-Control Studies; Cross-Sectional Studies; Double-Blind Method; Epilepsies, Myoclonic; Epilepsy; Epileptic Syndromes; Humans; Lennox Gastaut Syndrome; Seizures
PubMed: 33754312
DOI: 10.1007/s40263-021-00807-y -
Cell Feb 2018Type I interferon (IFN) is produced when host sensors detect foreign nucleic acids, but how sensors differentiate self from nonself nucleic acids, such...
Type I interferon (IFN) is produced when host sensors detect foreign nucleic acids, but how sensors differentiate self from nonself nucleic acids, such as double-stranded RNA (dsRNA), is incompletely understood. Mutations in ADAR1, an adenosine-to-inosine editing enzyme of dsRNA, cause Aicardi-Goutières syndrome, an autoinflammatory disorder associated with spontaneous interferon production and neurologic sequelae. We generated ADAR1 knockout human cells to explore ADAR1 substrates and function. ADAR1 primarily edited Alu elements in RNA polymerase II (pol II)-transcribed mRNAs, but not putative pol III-transcribed Alus. During the IFN response, ADAR1 blocked translational shutdown by inhibiting hyperactivation of PKR, a dsRNA sensor. ADAR1 dsRNA binding and catalytic activities were required to fully prevent endogenous RNA from activating PKR. Remarkably, ADAR1 knockout neuronal progenitor cells exhibited MDA5 (dsRNA sensor)-dependent spontaneous interferon production, PKR activation, and cell death. Thus, human ADAR1 regulates sensing of self versus nonself RNA, allowing pathogen detection while avoiding autoinflammation.
Topics: Adenosine Deaminase; Alu Elements; Autoimmune Diseases of the Nervous System; Cell Death; Gene Knockout Techniques; HEK293 Cells; Humans; Inflammation; Interferon-Induced Helicase, IFIH1; Nervous System Malformations; Neural Stem Cells; Protein Biosynthesis; RNA Polymerase II; RNA, Double-Stranded; RNA-Binding Proteins; eIF-2 Kinase
PubMed: 29395325
DOI: 10.1016/j.cell.2017.12.038 -
Human Mutation Apr 2020IFIH1 gain-of-function has been reported as a cause of a type I interferonopathy encompassing a spectrum of autoinflammatory phenotypes including Aicardi-Goutières...
IFIH1 gain-of-function has been reported as a cause of a type I interferonopathy encompassing a spectrum of autoinflammatory phenotypes including Aicardi-Goutières syndrome and Singleton Merten syndrome. Ascertaining patients through a European and North American collaboration, we set out to describe the molecular, clinical and interferon status of a cohort of individuals with pathogenic heterozygous mutations in IFIH1. We identified 74 individuals from 51 families segregating a total of 27 likely pathogenic mutations in IFIH1. Ten adult individuals, 13.5% of all mutation carriers, were clinically asymptomatic (with seven of these aged over 50 years). All mutations were associated with enhanced type I interferon signaling, including six variants (22%) which were predicted as benign according to multiple in silico pathogenicity programs. The identified mutations cluster close to the ATP binding region of the protein. These data confirm variable expression and nonpenetrance as important characteristics of the IFIH1 genotype, a consistent association with enhanced type I interferon signaling, and a common mutational mechanism involving increased RNA binding affinity or decreased efficiency of ATP hydrolysis and filament disassembly rate.
Topics: Alleles; Autoimmune Diseases of the Nervous System; DNA Mutational Analysis; Female; Gain of Function Mutation; Genetic Association Studies; Genotype; High-Throughput Nucleotide Sequencing; Humans; Interferon-Induced Helicase, IFIH1; Male; Models, Molecular; Nervous System Malformations; Phenotype; Protein Conformation; Structure-Activity Relationship
PubMed: 31898846
DOI: 10.1002/humu.23975 -
Proceedings of the National Academy of... Jun 2021Cytosolic DNA activates cGAS (cytosolic DNA sensor cyclic AMP-GMP synthase)-STING (stimulator of interferon genes) signaling, which triggers interferon and inflammatory...
Cytosolic DNA activates cGAS (cytosolic DNA sensor cyclic AMP-GMP synthase)-STING (stimulator of interferon genes) signaling, which triggers interferon and inflammatory responses that help defend against microbial infection and cancer. However, aberrant cytosolic self-DNA in Aicardi-Goutière's syndrome and constituently active gain-of-function mutations in STING in STING-associated vasculopathy with onset in infancy (SAVI) patients lead to excessive type I interferons and proinflammatory cytokines, which cause difficult-to-treat and sometimes fatal autoimmune disease. Here, in silico docking identified a potent STING antagonist SN-011 that binds with higher affinity to the cyclic dinucleotide (CDN)-binding pocket of STING than endogenous 2'3'-cGAMP. SN-011 locks STING in an open inactive conformation, which inhibits interferon and inflammatory cytokine induction activated by 2'3'-cGAMP, herpes simplex virus type 1 infection, deficiency, overexpression of cGAS-STING, or SAVI STING mutants. In mice, SN-011 was well tolerated, strongly inhibited hallmarks of inflammation and autoimmunity disease, and prevented death. Thus, a specific STING inhibitor that binds to the STING CDN-binding pocket is a promising lead compound for STING-driven disease.
Topics: Animals; Binding Sites; Biotinylation; Cell Death; Exodeoxyribonucleases; Humans; Inflammation; Membrane Proteins; Mice; Molecular Docking Simulation; Mutation; Nucleotides, Cyclic; Phosphoproteins; Protein Domains; Signal Transduction
PubMed: 34099558
DOI: 10.1073/pnas.2105465118