Biology subjects

Keegan, A.

Publications and source records attributed to Keegan, A..

5 recordsLinked to original sources

bioRxiv2026

Allergic airway inflammation protects against SARS-CoV-2 and MERS-CoV disease but promotes fatal SARS-CoV-1 immunopathology

Epidemiological, clinical, and experimental data suggest that allergic asthma may have protective effects against severe Coronavirus Disease 2019 (COVID-19) but are often conflicting between different models of infection and epidemiological analyses. Allergic asthma is characterized by type 2 (T2) inflammation, mucus hypersecretion, and airway remodeling. We used a house dust mite (HDM) respiratory exposure model to determine how preexisting allergic inflammation alters the pathogenesis of three highly pathogenic coronaviruses, SARS-CoV-1, SARS-CoV-2, and MERS-CoV. HDM treatment induced canonical features of allergic asthma, including goblet cell hyperplasia, mucin hypersecretion, eosinophil recruitment, M2 macrophage polarization, and induction of IL-13. Across multiple SARS-CoV-2 variants, HDM treated mice exhibited reduced viral titers, less weight loss, diminished lung immunopathology, and improved survival rates. Similar protection was observed in a mouse model of MERS-CoV, with reduced lethality, lower viral burden, and blunted cytokine storm signatures in HDM treated mice. In contrast, allergic airway inflammation exacerbated SARS-CoV-1 pathogenesis, as HDM-treated mice developed fulminant alveolar inflammation, severe weight loss, elevated pro-inflammatory cytokines and chemokines, and increased mortality despite having reduced virus titer. Thus, in mice, allergic airway inflammation exerts opposing virus specific effects on coronavirus pathogenesis. These results reconcile conflicting epidemiological and mechanistic studies across coronavirus epidemics and highlight the need to consider host allergic status as a key variable influencing disease outcome from emerging coronaviruses.

microbiology↗

bioRxiv2025

Next Generation AAV-F Capsid gene therapy rescues disease pathology in a model of Pyruvate Dehydrogenase Complex Deficiency

Pyruvate dehydrogenase complex deficiency (PDHD) is a severe mitochondrial disorder most frequently caused by pathogenic variants in PDHA1, leading to neurodevelopmental delay and early mortality, necessitating brain-targeted interventions. Using a brain-specific Pdha1 knockout mouse model, we compared intracerebroventricular delivery of AAV9 capsid and a recently described synthetic neurotropic AAV-F capsid, both expressing human PDHA1 coding sequence driven by a constitutive CAG promoter. Newborn mice received, titre matched AAV9 or AAV-F or AAV9 at ten-fold higher dose. Low-dose AAV-F and high-dose AAV9 significantly improved survival, and restored PDH enzyme activity, metabolite profiles, and brain histopathology to near wild-type levels. However, treated mice showed reduced locomotion by P100 and impaired motor function. Importantly, AAV-F achieved broad CNS transduction with minimal liver expression, outperforming AAV9 at lower dose. There results support the therapeutic potential of AAV-based gene therapy for PDHD and highlighting AAV-F as a promising capsid for efficient, CNS specific delivery.

neuroscience↗

bioRxiv2025

AAV delivery of RNA editing machinery rescues SUDEP and seizure phenotype in a mouse model of Dravet Syndrome

Dravet syndrome (DS) is a severe childhood genetic epilepsy, caused by de novo heterozygous mutations in SCN1A, resulting in a loss-of-function of the voltage-gated sodium ion channel, Nav1.1. Nav1.1 is expressed in the brain, and at a lower level, in the heart. DS manifests in the first year of life. Patients exhibit tonic-clonic seizures, febrile seizures, cognitive decline, developmental delays, ataxia, and sudden unexpected death from epilepsy (SUDEP). We have developed a novel AAV-F mediated CRISPR-Cas-inspired RNA targeting system (CIRTS) preclinical treatment to increase endogenous Scn1a and ameliorate the disease phenotype in a clinically-relevant heterozygous loss-of-function mouse model of DS. We designed novel guide RNAs (gRNAs) to target the long non-coding RNA, (or natural antisense transcript) of Scn1a to increase the expression of Scn1a mRNA in DS mice. We show that intracerebroventricular and intravenous administration of AAV-F-CIRTS-gRNA9 to target the brain and the heart to neonatal Scn1a+/-mice resulted in a significant increase in survival, and a reduction in SUDEP, febrile seizures and seizure duration. These findings provide proof-of-concept evidence that an AAV-F-CIRTS mediated therapy hold promise as a potential treatment for DS.

neuroscience↗

bioRxiv2024

AAV9-mediated targeting of natural antisense transcript as a novel treatment for Dravet Syndrome

Dravet syndrome (DS) is a severe childhood onset developmental and epileptic encephalopathy which leads to life-long disability. Symptoms usually manifest in the first year of life and include prolonged severe seizures, developmental delay and severe intellectual disability. DS patients have an increased mortality rate, including sudden unexpected death in epilepsy (SUDEP). Approximately 90% of patients carry a heterozygous loss-of-function mutation in the SCN1A gene, which encodes a voltage-gated sodium ion channel, NaV1.1. The NaV1.1 channel is expressed in the brain and at a lower level, in the heart. Previous studies have identified a long non-coding RNA (lncRNA) which specifically downregulates SCN1A gene expression. This natural antisense transcript (NAT) can be modulated by AntagoNATs, small synthetic oligonucleotides developed to inhibit NAT function. In a DS mouse model, AntagoNATs were shown to modulate Scn1a expression by targeting the Scn1a NAT, improving seizure frequency after repeated administration. Here, we have developed novel AntagoNATs and incorporated these into a clinically relevant adeno-associated virus serotype 9 (AAV9) gene therapy vector, to test in a DS mouse model (Scn1a+/-) and provide a one-off treatment approach. Eighteen AntagoNATs were tested in vitro; from the best performing candidates, we selected two AntagoNAT sequences (K & H) for in vivo testing as they had the highest homology (90%) to human SCN1A NAT. We administered both vectors to newborn Scn1a+/- mice via intracerebroventricular (ICV) and intravenous (IV) injection to target the brain and heart. AAV9-AntagoNAT-H significantly increased survival, decreased febrile seizures and reduced spontaneous seizure frequency compared to the PBS control group. When administered at P14 by ICV and IV injection, AAV9-AntagoNAT-H increased survival. In this proof-of-concept study, we have demonstrated for the first time the delivery of AntagoNAT technology via an AAV9 vector and thus offering the possibility of a one-time treatment for DS patients.

molecular biology↗

bioRxiv2023

Spinal cord pathology in a Dravet Syndrome mouse model

SummaryO_ST_ABSObjectivesC_ST_ABSDravet syndrome is a severe epileptic encephalopathy that begins in early childhood. More than 80% of patients with Dravet syndrome exhibit a haploinsufficiency in SCN1A, which encodes the voltage-gated sodium ion channel NaV1.1. The epilepsy is believed be caused by specific deficit of SCN1A in inhibitory interneurons of the hippocampus. However, the aetiology of other symptoms including gait disturbances, ataxia, cardiac issues and dysautonomia is less clear. MethodsIn an Scn1a knock-out (Scn1a-/-) mouse model which recapitulates clinical phenotypes, we assessed NaV1.1 and neuroinflammation throughout the central nervous system. ResultsConsistent with current understanding, wild-type expression of NaV1.1 transcript and protein were absent in knock-out mice in the prefrontal cortex, striatum, hippocampus, thalamus, and cerebellum. Increased GFAP was detected in the brain only in the hippocampus. Transcript and protein were detected in wild-type cervical, thoracic and lumbar spinal cord but not in knock-out mice. Unexpectedly, GFAP was increased in all three spinal regions. Therefore, we proceeded to perform transcriptomic analysis of cortex, hippocampus and spinal cord. Pathways associated with monooxygenase activity, fatty acid ligases and lactate transporters were highly dysregulated in the spinal cord. ConclusionThe existence and relevance of pathology of the spinal cord in Dravet syndrome has received scant attention. Our findings are consistent with some systemic symptoms of Dravet syndrome, with the benefits of treatments which may modulate the astrocyte-neuron lactate shuttle such as Stiripentol and ketogenic dietary regimes, and with the efficacy of intrathecal delivery of therapeutics. Key PointsO_LIDecrease of endogenous Scn1a and NaV1.1 expression in Scn1a-/- mice has a widespread impact on the gene expression profile in the spinal cord. C_LIO_LIIncreased GFAP expression observed in the spinal cord of Scn1a-/- mice. C_LIO_LIDifferentially expressed genes related to monooxygenase activity, fatty acid ligases and lactate transporters in cervical spinal cord of Scn1a-/- mice. C_LI

molecular biology↗