Thèse Thérapie Précoce par Intracorps à Médiation Aav Ciblant la Tdp-43 dans le Cerveau et l'Intestin dans la Sla. H/F

Doctorat.Gouv.Fr

Établissement : Université de Tours École doctorale : Santé, Sciences Biologiques et Chimie du Vivant - SSBCV Laboratoire de recherche : Imaging, Brain & Neuropsychiatry Direction de la thèse : Hélène BLASCO ORCID 0000000161070035 Début de la thèse : 2026-10-01 Date limite de candidature : 2026-07-10T23:59:59 La sclérose latérale amyotrophique (SLA) est une maladie neurodégénérative aujourd'hui en impasse thérapeutique. Dans la majorité des cas, elle s'accompagne d'une accumulation anormale de la protéine TDP-43 dans les cellules notamment du cerveau, ce qui contribue à sa toxicité.
Ce projet vise à développer une nouvelle stratégie thérapeutique ciblant directement cette protéine. Nous avons conçu de petits fragments d'anticorps intracellulaires capables de se lier à TDP-43 afin de limiter ses effets toxiques. Ces fragments sont délivrés dans les cellules grâce à des vecteurs de thérapie génique permettant une production durable.
Des résultats préliminaires obtenus dans un modèle murin de SLA montrent déjà une amélioration des performances motrices et de certains biomarqueurs biologiques après traitement.
Des travaux récents suggèrent également un rôle de l'axe intestin-cerveau dans la maladie, avec une implication possible de TDP-43 dans l'intestin. Le projet évaluera donc si une intervention précoce ciblant à la fois le cerveau et l'intestin peut renforcer l'efficacité thérapeutique.
Les effets seront analysés sur la progression de la maladie, les biomarqueurs circulants et les altérations métaboliques, puis confirmés dans un second modèle animal. L'objectif est d'identifier une stratégie innovante capable de ralentir la progression de la SLA en ciblant les sites clés du cerveau et de l'intestin. Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive degeneration of upper and lower motor neurons, leading to paralysis and death from respiratory failure within 3-5 years. Despite extensive research efforts, therapeutic options remain extremely limited and no treatment currently halts disease progression. Developing innovative therapeutic strategies targeting key pathogenic mechanisms therefore represents a major priority. A central pathological hallmark of ALS is the abnormal aggregation and mislocalization of TDP-43 protein, observed in approximately 97% of patients (1). TDP-43 pathology is now recognized as a major driver of neuronal dysfunction and degeneration. Strategies aimed at preventing TDP-43 aggregation or promoting its clearance therefore represent a highly promising therapeutic avenue.
Single-chain variable fragments (scFv) constitute particularly attractive tools for such approaches. These small antibody fragments maintain high antigen specificity and affinity while being compatible with intracellular expression. We have developed two scFv directed against TDP-43 (D7 and B1), currently protected by a patent (EP24305919)(2). These molecules function as intrabodies capable of binding pathological TDP-43 within cells and potentially neutralizing its toxic effects. One of the major challenges in developing biologics targeting neurodegenerative diseases lies in their efficient delivery to the central nervous system (CNS). Adeno-associated viral vectors (AAV) have emerged as highly efficient gene-delivery tools and are increasingly used in neurological gene therapy. AAV-mediated expression of intrabodies therefore represents a promising strategy to achieve sustained intracellular targeting of pathological proteins. Importantly, increasing evidence suggests that ALS pathophysiology involves not only the CNS but also peripheral components such as the gut-brain axis (3). Intestinal dysfunction and altered gut-immune interactions have been described in both patients and animal models. Targeting both central and peripheral compartments (4-6) may therefore represent an innovative strategy to improve therapeutic efficacy. A recent review highlighted the role of TDP-43 aggregation in driving neuroinflammation and gut-brain axis dysfunction in ALS, positioning gut-directed therapies-such as microbiome modulation or anti-TDP43 agents, as promising strategies to disrupt this pathogenic loop and slow disease progression (7). A group showed that TDP-43 pathology disrupts the intestinal endocannabinoidome, lipid mediators, and gut microbiome composition, even in a TDP-43 mouse model of frontotemporal dementia (FTD), where TDP-43 aggregates are also prevalent (8). Finally, some authors demonstrated that intestinal dysfunction and microbial dysbiosis precede neuromuscular symptoms in ALS (9). These results highlight the gut as a critical early therapeutic target, thus justifying the development of anti-TDP43 treatments aimed at restoring gut homeostasis to delay ALS progression. Our preliminary studies demonstrated encouraging therapeutic effects of AAV-mediated scFv delivery (single intravenous injection of AAV.CAP-B10 vectors, 6 × 10¹¹ VG per mouse, at 4 months of age) in the hTDP43A315T mouse model. Even when treatment was initiated too late after the onst of symptom, animals receiving the scFv D7 displayed improved motor performance and biological and metabolic alterations detectable using metabolimics and FDG-PET imaging.These findings strongly support further development of this strategy. However, two key questions remain unresolved: 1- Can early intervention significantly enhance therapeutic efficacy? 2- Which anatomical targeting strategy (central, intestinal, or combined) provides optimal benefit? Addressing these questions constitutes the core objective of the present project. We hypothesize that early AAV-mediated delivery of an anti-TDP-43 intrabody will reduce TDP-43 toxicity and improve disease outcomes, and that combined targeting of central and intestinal compartments may enhance therapeutic benefit.
The project will pursue three main objectives:
Objective 1 - Optimize early AAV-mediated delivery of anti-TDP-43 intrabodies.
We will evaluate three complementary administration strategies: CNS targeting/ intestinal targeting/ combined CNS and intestinal targeting. These approaches will allow identification of the most effective strategy for modulating disease progression.
Objective 2 - Evaluate therapeutic efficacy and biological effets following early intervention.
Treatment will be initiated at the earliest detectable symptoms, in order to determine whether early targeting of TDP-43 toxicity can significantly delay disease progression.
Objective 3 - Validate therapeutic effects in an independent ALS model
Key findings will be validated in a second ALS mouse model by the Montpellier partner. Work Package 1: Optimization of AAV-mediated intrabody delivery
Work Package 2: Therapeutic evaluation following early intervention
Work Package 3: Multi-omics characterization of treatment effects
Work Package 4: Microbiome analysis and gut-brain interactions
Work Package 5 - Integrated analysis
Work Package 6: Independent validation on hTDP43Q331K mouse model