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Cerebral creatine deficiency syndromes: New in vivo AAV approaches to treat SLC6A8 deficiency

English title Cerebral creatine deficiency syndromes: New in vivo AAV approaches to treat SLC6A8 deficiency
Applicant Braissant Olivier
Number 175778
Funding scheme Project funding
Research institution Service de chimie clinique Dpt. médecine de laboratoire et pathologie CHUV et Université de Lausanne
Institution of higher education University of Lausanne - LA
Main discipline Pathophysiology
Start/End 01.11.2017 - 30.09.2022
Approved amount 543'293.00
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All Disciplines (2)

Discipline
Pathophysiology
Embryology, Developmental Biology

Keywords (10)

Development; GAMT; AGAT; Creatine; 3D organotypic brain cell cultures; KI rats; SLC6A8; Guanidinoacetate; In vivo models; Brain

Lay Summary (French)

Lead
La créatine (Cr) est synthétisée par deux enzymes, arginine:glycine amidinotransférase (AGAT) et guanidinoacétate méthyltransférase (GAMT). Les cellules importent la Cr au moyen du transporteur SLC6A8. Les syndromes de déficience en Cr (CDS), dus à une déficience génétique en AGAT, GAMT ou SLC6A8, affectent le cerveau et causent des retards sévères de son développement. Les CDS sont caractérisés par l’absence de Cr cérébrale. Les patients déficients en AGAT et GAMT sont traitables par Cr. La déficience en SLC6A8, la plus fréquente des CDS, n’est pas traitable à ce jour en raison de l’absence de transporteur de Cr SLC6A8 fonctionnel sur la barrière hémato-encéphalique (BHE), et ses patients développent une dégradation neurologique irréversible.
Lay summary

Nous avons conçu des vecteurs viraux AAV (adeno-associated viruses) capable de transduire tous les types de cellules nerveuses. Ces vecteurs étant de plus en plus acceptés comme outils thérapeutiques prometteurs pour différentes pathologies humaines, nous pensons que des vecteurs AAV rétablissant un transporteur SLC6A8 fonctionnel sur la barrière hémato-encéphalique et dans le système nerveux central permettraient le rétablissement de la créatine cérébrale chez les patients SLC6A8 et l’amélioration de leur développement neurologique. Nous proposons de développer un nouveau modèle in vivo de traitement de la déficience en SLC6A8 chez le rat au moyen de vecteurs AAV, complété par un traitement par créatine.

Nous pensons que notre approche in vivo chez le rat pourra ensuite être utilisée pour des essais cliniques chez les patients atteints de déficience en SLC6A8 (le plus fréquent des syndromes de déficiences en créatine), pour lesquels toute tentative de traitement a échoué jusqu'à ce jour. Une fois validée, cette stratégie pourra aussi s’appliquer à toute autre déficience génétique causant un défaut dans un système de transport affectant le développement ou la fonction du cerveau.

Direct link to Lay Summary Last update: 03.10.2017

Responsible applicant and co-applicants

Employees

Project partner

Publications

Publication
Creatine disorders
Stöckler Sylvia, Braissant Olivier, Schulze Andreas (2022), Creatine disorders, in Ferrreira CR, van Karnebeek CDM, Blau N, Vianney-Saban C, Dionisi-Vici M (ed.), Springer-Verlag, Berlin, Heidelberg, New York, 1-21.
Creatine transporter deficient rat model shows motor dysfunction, cerebellar alterations and muscle creatine deficiency without muscle atrophy
Duran-Trio Lara, Fernandes-Pires Gabriella, Grosse Jocelyn, Soro-Arnaiz Ines, Roux-Petronelli Clothilde, Binz Pierre-Alain, De Bock Katrien, Cudalbu Cristina, Sandi Carmen, Braissant Olivier (2021), Creatine transporter deficient rat model shows motor dysfunction, cerebellar alterations and muscle creatine deficiency without muscle atrophy, in Journal of Inherited Metabolic Disease, 1-14.
Current and potential new treatment strategies for creatine deficiency syndromes
Fernandes-Pires Gabriella, Braissant Olivier (2021), Current and potential new treatment strategies for creatine deficiency syndromes, in Molecular Genetics and Metabolism, 1-12.
A new rat model of creatine transporter deficiency reveals behavioral disorder and altered brain metabolism
Duran-Trio Lara, Fernandes-Pires Gabriella, Simicic Dunja, Grosse Jocelyn, Roux Clothilde, Binz Pierre-Alain, Sandi Carmen, Cudalbu Cristina, Braissant Olivier (2021), A new rat model of creatine transporter deficiency reveals behavioral disorder and altered brain metabolism, in Scientific Reports, 11(1), 1636.
Argininosuccinate neurotoxicity and prevention by creatine in argininosuccinate lyase deficiency: An in vitro study in rat three‐dimensional organotypic brain cell cultures
Diez-Fernandez Carmen, Hertig Damian, Loup Marc, Diserens Gaelle, Henry Hugues, Vermathen Peter, Nuoffer Jean-Marc, Häberle Johannes, Braissant Olivier (2019), Argininosuccinate neurotoxicity and prevention by creatine in argininosuccinate lyase deficiency: An in vitro study in rat three‐dimensional organotypic brain cell cultures, in Journal of Inherited Metabolic Disease, 42(6), 1077-1087.
Creatine in the central nervous system: From magnetic resonance spectroscopy to creatine deficiencies
Rackayova Veronika, Cudalbu Cristina, Pouwels Petra J.W., Braissant Olivier (2017), Creatine in the central nervous system: From magnetic resonance spectroscopy to creatine deficiencies, in Analytical Biochemistry, 529, 144-157.
Creatine deficiency syndromes
SchulzeAndreas, BraissantOlivier (2017), Creatine deficiency syndromes, in Sarafoglou K, Hoffmann G, Roth K (ed.), McGraw-Hill, New York, 181-190.

Collaboration

Group / person Country
Types of collaboration
Prof Sonja Sucic, Medical University of Vienna Austria (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Prof Sylvia Stöckler, Pediatrics, University of British Columbia, Vancouver Canada (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
CCDS 2020 Virtual Conference (International Conference on Cerebral Creatine Deficiency Syndromes) Individual talk The Slc6a8Y389C/y creatine transporter-deficient rat : From characterization to strategies of treatment 07.08.2020 Los Angeles (mais conférence online), United States of America Fernandes Pires Gabriella Patrizia; Braissant Olivier; Duran-Trio Lara Amaya;
Journée CHUV de la recherche des départements de médecine et de médecine de laboratoire et de pathologie Talk given at a conference Brain creatine deficiency, increased grooming and structural cerebellar changes in a new KI rat model of creatine transporter deficiency. 27.02.2020 Lausanne, Switzerland Duran-Trio Lara Amaya; Fernandes Pires Gabriella Patrizia; Braissant Olivier;
Frontiers in Metabolism 2019 Talk given at a conference Brain creatine deficiency, increased grooming and structural cerebellar changes in a new KI rat model of creatine transporter deficiency. 16.09.2019 Madison, United States of America Duran-Trio Lara Amaya;
CCDS 2019 (International Workshop on Cerebral Creatine Deficiency Syndromes) Individual talk A new knock-in rat model of creatine transporter deficiency 06.09.2019 Rotterdam, Netherlands Duran-Trio Lara Amaya; Fernandes Pires Gabriella Patrizia; Braissant Olivier;
SSIEM 2019 (Annual meeting of the Society for the Study of Inborn Errors of Metabolism) Poster Brain creatine deficiency, increased grooming and structural cerebellar changes in a new KI rat model of creatine transporter deficiency. 03.09.2019 Rotterdam, Netherlands Braissant Olivier; Fernandes Pires Gabriella Patrizia; Duran-Trio Lara Amaya;
LIMNA 2019 Symposium (Lausanne Integrative Metbolism and Nutrition Alliance) Poster Brain creatine deficiency, increased grooming and structural cerebellar changes in a new KI rat model of creatine transporter deficiency. 12.04.2019 Lausanne, Switzerland Duran-Trio Lara Amaya; Fernandes Pires Gabriella Patrizia; Braissant Olivier;
SFNP 2019 (Société Française de Neuropédiatrie) Talk given at a conference Déficience cérébrale en créatine et frein d’acquisition pondérale dans un nouveau modèle de rat KI déficient en transporteur de créatine. 18.01.2019 Strasbourg, France Duran-Trio Lara Amaya; Braissant Olivier;
LIMNA 2018 Symposium (Lausanne Integrative Metbolism and Nutrition Alliance) Poster Cerebral creatine deficiency and lower weight gain in a new KI rat model of creatine transporter deficiency. 08.11.2018 Lausanne, Switzerland Duran-Trio Lara Amaya; Braissant Olivier; Fernandes Pires Gabriella Patrizia;
SSIEM 2018 (Annual meeting of the Society for the Study of Inborn Errors of Metabolism) Talk given at a conference Cerebral creatine deficiency and lower weight gain in a new KI rat model of creatine transporter deficiency. 04.09.2018 Athens, Greece Fernandes Pires Gabriella Patrizia; Braissant Olivier; Duran-Trio Lara Amaya;


Knowledge transfer events

Active participation

Title Type of contribution Date Place Persons involved


Awards

Title Year
"GTA Award (Gene Therapy Advancement Award)" July 2021 : 10’000 USD from the American Association for Creatine Deficiencies (ACD) to O.Braissant. 2021
Bourse de voyage pour assister au congrès Frontiers in Metabolism 2019, Madison, USA, Septembre 2019. => Présentation orale des premiers résultats de caractérisation du rat Slc6a8/Y389C. Octroyée par le LIMNA (Lausanne Integrative Metabolic Nutrition Alliance). 2019

Associated projects

Number Title Start Funding scheme
130278 Inborn errors of metabolism: Investigating creatine deficiency syndromes in the developing nervous system by gene knock-down. 01.06.2010 Project funding
116859 Inborn errors of metabolism: investigating creatine deficiency syndromes in the developing nervous system by gene knock-down 01.04.2007 Project funding
201218 Enhanced MR Spectroscopic mapping of brain regional changes in type C hepatic encephalopathy of juvenile rats to develop novel combinatorial treatments 01.10.2021 Project funding
173222 Translational Non-Invasive Metabolic Studies towards Novel Treatments of Chronic Hepatic Encephalopathy in Developing Brain, from 3D Organotypic Brain Cell Cultures to the In vivo Rat and Human Brain 01.04.2017 Project funding

Abstract

Cerebral creatine deficiency syndromes: New in vivo AAV approaches to treat SLC6A8 deficiency.Applicant: PD Dr Olivier Braissant, PhD / Co-applicant : Dr Cristina Cudalbu, PhD1:Summary of the research plan1.1:BackgroundCreatine (Cr) is synthesized by a 2-step pathway involving arginine:glycine amidinotransferase (AGAT) and guanidinoacetate methyltransferase (GAMT). Cells take up Cr by a specific Cr transporter, SLC6A8. Cr deficiency syndromes (CDS), due to AGAT, GAMT or SLC6A8 deficiencies, are inborn errors of metabolism (IEM) affecting the brain, causing severe neurodevelopmental delays and intellectual disability. CDS are characterized by absence of brain Cr when measured by MRS. AGAT and GAMT deficiencies can be treated with Cr, improving their neurological outcome. SLC6A8 deficiency cannot be treated so far, and patients show an irreversible neurological degradation.1.2:Working hypothesisAttempts to treat SLC6A8 deficiency, the most frequent of CDS, was not successful so far due to the absence of functional Cr transporter SLC6A8 on blood brain barrier (BBB). We recently designed adeno-associated viruses (AAV) that are able to transduce every brain cell type in models of CDS by RNAi. As AAV are more and more accepted as promising tools for human gene therapy including in CNS, we hypothesize that AAV vectors re-establishing a functional Cr transporter on BBB and in CNS would allow restoring brain Cr in SLC6A8-deficient patients and improving their neurological status. We propose here to develop a new AAV-driven in vivo model of treatment for the so far untreatableSLC6A8 deficiency in the rat. 1.3:Specific aims- To develop and produce AAV vectors transducing the functional SLC6A8-eGFP fusion Cr transporter in BBB and brain cells.- To demonstrate the feasibility of SLC6A8 deficiency treatment in vivo, through systemic injection of AAV/SLC6A8-eGFP vectors in a newly developed Slc6a8Y389C/y KI rat, coupled to Cr supplementation to improve CNS Cr restoration.- To demonstrate CNS Cr restoration and improvement of neurological status in AAV/SLC6A8-eGFP-injected Slc6a8Y389C/y KI rats, as well as faster replenishment of their brain Cr upon Cr co-treatment.1.4:Experimental design and methodsAAV1, 2 and 9 vectors (selected for high tropisms for BBB and brain cells) will be developed to transduce the functional SLC6A8-eGFP fusion protein in BBB and surrounding parenchymal brain cells. AAV/SLC6A8-eGFP vectors will first be tested in vitro, by expression in rat 3D organotypic brain cell cultures, as well as by restoring Cr uptake in human SLC6A8-deficient fibroblasts. AAV/SLC6A8-eGFP vectors will then be tested in vivo, first in wild type (WT), second in Slc6a8Y389C/y KI rats. Facilitation (WT) or restoration (Slc6a8Y389C/y) of Cr uptake and synthesis by CNS will be evaluated. Expression of SLC6A8-eGFP at BBB and within brain parenchyma will be characterized, together with the detailed analysis of their CNS involvement (development and cell differentiation, morphology, cell death). SLC6A8 deficiency treatment will be evaluated, combining injection of AAV/SLC6A8-eGFP vectors with Cr co-treatment. Restoration of brain Cr is expected, which will be followed longitudinally in vivo on a long term range (up to 1 year post-AAV injection) by high resolution 9.4T 1H- and 31P-MRS, as well as by LC/MS-MS on brain extracts. The treatments outcome (neurological improvement) will be evaluated through behavioral tests.1.5:Expected value of the projectWe believe that our innovative in vivo AAV-driven approach to restore the functional Cr transporter SLC6A8 (at BBB and in brain parenchyma), coupled to Cr co-treatment, will become available for clinical testing in humans, helping to find new therapeutic strategies for the so far untreatable SLC6A8 deficiency. This approach, by facilitating Cr transfer to CNS, will also become available to improve the treatment of AGAT and GAMT deficiencies, including the potential reduction of brain GAA intoxication found in GAMT deficiency as we have shown recently in 3D organotypic brain cell cultures. Finally, this strategy would then also become applicable to any other IEM showing a specific defect in a transport system affecting CNS development and function.
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