Biology subjects

Baruteau, J.

Publications and source records attributed to Baruteau, J..

7 recordsLinked to original sources

bioRxiv2023

The incidence of movement disorders increases with age and contrasts with subtle and limited neuroimaging abnormalities in argininosuccinic aciduria.

Argininosuccinate lyase is integral to the urea cycle detoxifying neurotoxic ammonia and the nitric oxide biosynthesis cycle. Inherited argininosuccinate lyase deficiency causes argininosuccinic aciduria (ASA), a rare disease with hyperammonaemia and nitric oxide deficiency. Patients present with developmental delay, epilepsy and movement disorders, associated with nitric oxide-mediated downregulation of central catecholamine biosynthesis. A neurodegenerative phenotype has been proposed in ASA. To better characterise this neurodegenerative phenotype in ASA, we conducted a retrospective study in six paediatric and adult metabolic centres in the UK in 2022. We identified 60 patients and specifically looked for movement disorders-related symptoms: movement disorders such as ataxia, tremor and dystonia, hypotonia and abnormal behaviour. We analysed neuroimaging with diffusion tensor imaging (DTI) magnetic resonance imaging (MRI) in an ASA patient with movement disorders. We assessed conventional and DTI MRI alongside single photon emission computer tomography (SPECT) with dopamine analogue radionuclide 123I-ioflupane, in Asl-deficient mice treated by hASL mRNA with normalised ureagenesis. Movement disorders in ASA appears in the 2nd and 3rd decades of life, becoming more prevalent with ageing and independent from the age of onset of hyperammonaemia. Neuroimaging can show abnormal DTI features affecting both grey and white matter, preferentially basal ganglia. ASA mouse model with normalised ureagenesis did not recapitulate these DTI findings and showed normal 123I-ioflupane SPECT and cerebral dopamine metabolomics. Altogether these findings support the pathophysiology of a late-onset movement disorders with functional central catecholamine dysregulation but without or limited neurodegeneration of dopaminergic neurons, making these symptoms amenable to targeted therapy. SynopsisMovement disorders-related symptoms in ASA appear in the 2nd and 3rd decades of life, becoming more prevalent with age and shows abnormal neuroimaging features of basal ganglia in ASA patients, not recapitulated in ASA mice.

genetics↗

bioRxiv2023

Macrophage inhibitor clodronate enhances liver transduction of lentiviral but not AAV vectors or mRNA lipid nanoparticles in vivo.

Recently approved adeno-associated viral (AAV) vectors for liver monogenic diseases hemophilia A and B are exemplifying the success of liver-directed viral gene therapy. In parallel, additional strategies are rapidly emerging to overcome some inherent AAV limitations, such as non-persistence of episomal transgene in rapidly growing liver and immune response. Integrating lentiviral vectors and non-viral lipid nanoparticles encapsulating mRNA (LNP-mRNA) are rapidly being developed, currently at preclinical and clinical stages respectively. Macrophages are first effector cells of the innate immune response triggered by gene therapy vectors. Macrophage uptake and activation following administration of viral gene therapy and LNPs has been reported. In this study, we assessed the biodistribution of AAV, lentiviral and LNP-mRNA gene therapy following inhibition of tissue macrophages by clodronate liposomes in neonatal and juvenile mice. Juvenile clodronate-treated mice showed significant increase of lentiviral-transduced hepatocytes, and increasing trend of transduction was shown in neonatally-injected mice. In contrast, AAV- and LNP-mRNA-treated neonatal and juvenile animals did not show significant increase of liver biodistribution following clodronate administration. These findings will have translational application for liver-targeting gene therapy programmes.

molecular biology↗

bioRxiv2023

Ex vivo primary liver sections recapitulate disease phenotype and therapeutic rescue for liver monogenic diseases

In academic research and the pharmaceutical industry, in vitro single cell line cultures and in vivo animal models are considered as gold standards in modelling diseases and assessing therapeutic efficacy. However, both models have limitations, with incomplete reproduction of pathophysiological characteristics and absence of 3-dimensional architecture with cell lines or the use of live animals brings ethical considerations, limiting the experimental scale and design. The use of precision-cut tissue slices can bridge the gap between these mainstream models as this technique combines the advantages of studying all cell sub-types whilst preserving the tissue-matrix architecture, thereby closely mimicking a mini-organ. Here, we describe an optimised and easy-to-implement protocol for the culture of sections from mouse livers. We show that precision-cut liver sections can be a reliable model for recapitulating the biological phenotype of inherited metabolic diseases, exemplified by common urea cycle defects citrullinemia type 1 and argininosuccinic aciduria, caused by argininosuccinic synthase (ASS1) and argininosuccinic lyase (ASL) deficiencies respectively. Therapeutic response to gene therapy such as messenger RNA replacement delivered via lipid nanoparticles can be monitored, demonstrating that precision-cut liver sections can be used as a preclinical screening tool to assess therapeutic response and toxicity in monogenic liver diseases.

cell biology↗

bioRxiv2022

mRNA therapy restores ureagenesis and corrects glutathione metabolism in argininosuccinic aciduria

Argininosuccinate lyase (ASL) is a key enzyme integral to the hepatic urea cycle which is required for ammonia detoxification, and the citrulline-nitric oxide (NO) cycle for NO production. ASL deficient patients present with argininosuccinic aciduria (ASA), an inherited metabolic disease with hyperammonaemia and a chronic systemic phenotype with neurocognitive impairment and chronic liver disease. ASL deficiency as an inherited model of systemic NO deficiency, shows enhanced nitrosative and oxidative stress. Here, we describe the dysregulation of glutathione biosynthesis and upstream cysteine utilization in ASL-deficient patients and mice using targeted metabolomics and in vivo positron emission tomography (PET) imaging using (S)-4-(3-18F-fluoropropyl)-L-glutamate ([18F]FSPG). Upregulation of cysteine metabolism contrasted with glutathione depletion and down-regulated antioxidant pathways. hASL mRNA encapsulated in lipid nanoparticles corrected and rescued the neonatal and adult Asl-deficient mouse phenotypes, respectively, enhancing ureagenesis and glutathione metabolism and ameliorating chronic liver disease. We further present [18F]FSPG PET as a novel non-invasive diagnostic tool to assess liver disease and therapeutic efficacy in ASA. These findings support clinical translation of mRNA therapy for ASA.

genetics↗

bioRxiv2022

Assessment of pre-clinical liver models based on their ability to predict the liver-tropism of AAV vectors

The liver is a prime target for in vivo gene therapies using recombinant adeno-associated viral vectors (rAAV). Multiple clinical trials have been undertaken for this target in the past 15 years, however we are still to see market approval of the first liver-targeted AAV-based gene therapy. Inefficient expression of the therapeutic transgene, vector-induced liver toxicity and capsid, and/or transgene-mediated immune responses reported at high vector doses are the main challenges to date. One of the contributing factors to the insufficient clinical outcomes, despite highly encouraging preclinical data, is the lack of robust, biologically- and clinically-predictive preclinical models. To this end, this study reports findings of a functional evaluation of six AAV vectors in twelve preclinical models of the human liver, with the aim to uncover which model is the most relevant for the selection of AAV capsid variant for safe and efficient transgene delivery to primary human hepatocytes. The results, generated by studies in models ranging from immortalized cells, iPSC-derived and primary hepatocytes, and primary human hepatic organoids to in vivo models, increased our understanding of the strengths and weaknesses of each system. This should allow the development of novel gene therapies targeting the human liver.

bioengineering↗

bioRxiv2020

Beclin-1-mediated activation of autophagy improves proximal and distal urea cycle disorders.

Urea cycle disorders (UCD) are inherited defects in clearance of waste nitrogen with high morbidity and mortality. Novel and more effective therapies for UCD are needed. Studies in mice with constitutive activation of autophagy unraveled Beclin-1 as druggable candidate for therapy of hyperammonemia. Next, we investigated efficacy of cell penetrating autophagy inducing Tat-Beclin-1 (TB-1) peptide for therapy of the two most common UCD, namely ornithine transcarbamylase (OTC) and argininosuccinate lyase (ASL) deficiencies. TB-1 reduced urinary orotic acid and hyperammonemia, and improved survival under protein-rich diet in spf-ash mice, a model of OTC deficiency (proximal UCD). In AslNeo/Neo mice, a model of ASL deficiency (distal UCD), TB-1 increased ureagenesis, reduced argininosuccinate, and improved survival. Moreover, it alleviated hepatocellular injury and decreased both cytoplasmic and nuclear glycogen accumulation in AslNeo/Neo mice. In conclusion, Beclin-1-dependent activation of autophagy improved biochemical and clinical phenotypes of proximal and distal defects of the urea cycle.

genetics↗

bioRxiv2018

Gene therapy in argininosuccinic aciduria

Argininosuccinate lyase (ASL) belongs to the liver-based urea cycle detoxifying ammonia, and the citrulline-nitric oxide cycle synthesising nitric oxide (NO). ASL-deficient patients present argininosuccinic aciduria characterised by hyperammonaemia and a multi-organ disease with neurocognitive impairment. Current therapeutic guidelines aim to control ammonaemia without considering the systemic NO imbalance. Here, we observed a neuronal disease with oxidative/nitrosative stress in ASL-deficient mouse brains. A single systemic injection of gene therapy mediated by an adeno-associated viral vector serotype 8 (AAV8) in adult or neonatal mice demonstrated the long-term correction of the urea cycle and the citrulline-NO cycle in the brain, respectively. The neuronal disease persisted if ammonaemia only was normalised but was dramatically reduced after correction of both ammonaemia and neuronal ASL activity. This was correlated with behavioural improvement and a decrease of the cortical cell death rate. Thus, the cerebral disease in argininosuccinic aciduria involves neuronal oxidative/nitrosative stress not mediated by hyperammonaemia, which is reversed by AAV gene transfer targeting the brain and the liver, acting on two different metabolic pathways via a single vector delivered systemically. This approach provides new hope for hepatocerebral metabolic diseases.

genetics↗