Thèse Patrimoine Alimentaire et Protection Bioculturelle Rôle du Maintien des Pratiques Alimentaires Traditionnelles dans l'Écologie Buccale et la Santé Systémique des Populations Migrantes - Étud H/F Doctorat.Gouv.Fr

Établissement : Université de Toulouse École doctorale : BSB - Biologie, Santé, Biotechnologies Laboratoire de recherche : EvolSan - Evolution et Santé Orale Direction de la thèse : Véronica PEREDA CAMPOS ORCID 0000000273656217 Début de la thèse : 2027-09-01 Date limite de candidature : 2026-11-23T23:59:59 Contexte : La migration vers des environnements fortement industrialisés entraîne généralement une 'occidentalisation' du microbiome, avec perte de diversité microbienne. Le microbiome oral, en première ligne de la transition alimentaire, réagit rapidement aux changements de régime et influence la santé immunitaire et métabolique. Contrairement à l'idée reçue d'une acculturation uniformément délétère, les migrants adoptent souvent des comportements alimentaires mixtes, combinant aliments transformés du pays d'accueil et pratiques culinaires traditionnelles. Le projet postule que cette rétention culturelle sélective produit un effet 'tampon bio-culturel' protecteur.
Question de recherche : La conservation de pratiques alimentaires traditionnelles protège-t-elle le microbiome oral des perturbations liées à la migration, et cette résilience microbienne se traduit-elle par une meilleure santé bucco-dentaire et systémique ?
Hypothèses :
H1 : Le passage à un régime occidental déstabilise le microbiome oral et favorise le déclin de santé.
H2 : Le maintien de pratiques alimentaires mexicaines traditionnelles protège les réseaux microbiens clés.
H3 : Une rétention alimentaire plus forte est associée à une plus grande stabilité/résilience microbienne, protégeant contre l'inflammation systémique.
Objectifs : Six objectifs spécifiques structurent le projet - quantifier l'acculturation nutritionnelle et les 'pratiques culturelles clés' ; cartographier l'exposome migratoire (externe et interne) ; caractériser le microbiome oral par métagénomique shotgun (taxonomie et fonctions) ; modéliser statistiquement l'effet tampon bio-culturel ; établir une base comparative transnationale France-Mexique ; et, à terme, co-construire des recommandations de santé publique avec les communautés concernées.
Méthodologie : Design mixte interdisciplinaire combinant épidémiologie nutritionnelle, cartographie de l'exposome, métagénomique orale et recherche participative, structuré en cinq work packages (WP) :
Phénotypage alimentaire - questionnaire épidémiologique co-construit avec les communautés mexicaines en France (s'appuyant sur le pilote MEX-AGE 1), complété par des entretiens qualitatifs.
Écologie microbienne orale - cohorte transversale (Tier A, séquençage haut débit + métagénomique ciblée) et sous-cohorte longitudinale (Tier B, ~15-20%, resuivie après une perturbation alimentaire comme un voyage au Mexique) pour mesurer la résilience réelle.
Exposome et intégration multi-omique - biomarqueurs internes (cotinine salivaire, cytokines) et externes (géolocalisation, stress psychosocial), modélisés via équations structurelles/médiation pour tester la chaîne causale acculturation rétention culturelle résilience microbienne santé.
Base transnationale - partenariat avec une institution mexicaine (ex. UAM) pour harmoniser les données et distinguer les effets propres à la migration des tendances séculaires au Mexique.
Recherche-action participative - ateliers avec les communautés pour co-interpréter les résultats et co-construire des stratégies de santé.
Contributions attendues : Première validation empirique du 'bouclier bio-culturel', cadre intégré exposome-microbiome, modélisation innovante de la résilience longitudinale, base de données génomique/exposomique transnationale, et modèle reproductible de recherche participative en biologie.
Impact sociétal : Le projet propose un changement de paradigme, passant d'une vision des migrants comme populations vulnérables à une reconnaissance de leur patrimoine culturel comme ressource de résilience biologique, avec des retombées en matière de réduction des inégalités de santé bucco-dentaire et systémique.
Dimensions : Interdisciplinarité (anthropologie biologique, dentisterie clinique/multi-omique, épidémiologie environnementale) alignée sur le programme BEST de l'Université de Toulouse ; codirection internationale avec une institution mexicaine incluant une mobilité doctorale au Mexique. Migration to highly industrialized environments typically drives a 'Westernization' of the human microbiome, characterized by a profound loss of microbial diversity and functional shifts [1]. It is well-established that dietary acculturation is the primary driver of these ecological changes. In parallel to the gut microbiota, the oral microbiome sits at the frontline of this nutritional transition. As the gateway to the gastrointestinal tract and a highly vascularized niche, it responds rapidly to external perturbations (diet, smoking, stress) while actively mediating systemic immune and metabolic responses [2].
Existing literature largely frames acculturation as a purely deleterious process. However, migrant populations rarely abandon their traditional diets entirely; instead, they exhibit complex dietary behaviours, selectively integrating host-country processed foods while retaining specific traditional culinary practices (e.g., complex food matrices, ancestral cooking methods, specific bioactive spices) [3]. We propose that this selective cultural retention may exert a 'bio-cultural buffering' effect. Integrated within an exposome framework, MEX-AGE 2.0 leverages the Mexican population in Occitanie (in dialogue with Mexican partners) as a natural laboratory to investigate how cultural resilience shapes microbial ecology and mitigates migration-associated health risks.
General objective To determine how and if the retention of dietary heritage acts as a 'bio-cultural shield' against acculturation-driven dysbiosis, and to model the mechanistic interplay between the migration exposome, oral microbiome resilience, and systemic health outcomes using a comparative France-Mexico framework.
Specific objectives To achieve this, the project is structured around the following hypothesis-driven objectives:
- SO1. Quantify the dynamics of nutritional acculturation and dietary retention: Compute precise indices of traditional food retention versus host-country processed food adoption among Mexican migrants in Occitanie, and identify specific 'cultural keystone practices' (e.g., complex matrices, spices, traditional cooking methods).
- SO2. Map the migration-driven exposome: Capture cumulative environmental exposures through a dual approach: external exposome mapping (geospatial, socioeconomic, and lifestyle stressors) and internal exposome profiling (targeted biomarker panels for systemic inflammation and metabolic health).
- SO3. Profile oral microbial ecology at high resolution: Apply shotgun metagenomics (note: j'ai corrigé 'metagenomic' en 'shotgun metagenomics') to identify not only taxonomic shifts but also the functional metabolic pathways and keystone microbial networks vulnerable to dietary transition.
- SO4. Model the 'Bio-Cultural Buffering' effect: Employ multivariate statistical models to formally test whether the retention of dietary heritage statistically mediates the relationship between acculturation stress, microbiome stability, and clinical health indicators.
- SO5. Establish a transnational baseline: Leverage the comparative France-Mexico framework to disentangle true migration-induced microbiome and exposome shifts from secular, population-level trends occurring in the Mexican source population.
- SO6. (Long-term goal) Translate findings via community-based participatory research: Co-construct culturally adapted public health and nutritional guidelines with community stakeholders, ensuring that biological insights yield tangible, ethically grounded health-promotion strategies.
Methodology and Study Design
The project employs an interdisciplinary, hypothesis-driven mixed-methods design, integrating nutritional epidemiology, exposome mapping, oral metagenomics, and community-based participatory research. The core architecture relies on a cross-sectional baseline (Tier A), complemented by a nested, longitudinal sub-cohort (Tier B) to dynamically evaluate microbial resilience against dietary perturbations within the three-year timeframe.
Work Package 1 - Dietary Phenotyping and Acculturation Kinetics To quantify the 'bio-cultural shield,' this WP moves beyond standard dietary recall by capitalizing on the ongoing, TIRIS-funded MEX-AGE 1 pilot project. Through active co-construction with Mexican community groups in France, this WP seamlessly bridges qualitative community insights with robust quantitative epidemiology.
Instrument Operationalization (From Dialogue to Data): Leveraging the foundational community discussions and focus groups already initiated under MEX-AGE 1, we will translate these qualitative narratives into a standardized, culturally validated epidemiological questionnaire. This co-design step ensures the survey instrument accurately captures the nuanced realities of migrant food practices.
Quantitative Metrics: Using this validated instrument, we will compute composite indices of nutritional acculturation. This will quantitatively contrast the adoption of host-country ultra-processed foods against the retention of specific traditional Mexican dietary practices (e.g., complex food matrices, ancestral preparation methods).
Qualitative Mechanistic Context: Complementing the surveys, targeted semi-structured interviews will contextualize the quantitative findings, capturing migration trajectories, acculturation stressors, and the precise sociocultural mechanisms driving selective food retention or abandonment that biological sensors cannot detect.
Work Package 2 - Oral Microbial Ecology and Bio-Cultural Resilience Participants will undergo standardized clinical oral-health assessments and biological sampling (saliva/plaque). To capture both compositional stability and ecological resilience, we employ a two-tiered analytical pipeline:
- Tier A (Cross-Sectional Stability): In the full cohort, microbiome profiles will be characterized using high-throughput sequencing (based on 4x metagenomics for functional pathway analysis in targeted subsets). We will compute a composite Stability Index incorporating within-group beta-dispersion, co-occurrence network robustness, and distance to a defined eubiotic centroid.
- Tier B (Longitudinal Resilience): A nested sub-cohort (~15-20% of participants) anticipating a discrete dietary/behavioural perturbation (e.g., a planned visit to Mexico, a major cultural holiday) will be resampled 3-6 months post-perturbation. This allows for the empirical modelling of microbial recovery trajectories (true resilience) as a function of their baseline cultural retention.
Work Package 3 - Exposome Mapping and Multi-Omics Integration This WP serves as the analytical core to formally test the mediating effect of the bio-cultural shield.
- The External Exposome: Documented via validated questionnaires and geocoded data, capturing residential history, environmental quality, and acculturation-related psychosocial stressors.
- The Internal Exposome: Assessed via a targeted biomarker panel on matched biofluids (e.g., salivary cotinine, inflammatory cytokines). A scalable pipeline is budgeted to include high-resolution dietary-exposure metabolites depending on final funding allocations.
- Integrative Modelling: We will deploy multivariate statistical frameworks (e.g., structural equation modelling, mediation analysis) to formally test the causal pathway: Acculturation Stress Bio-Cultural Buffering (Dietary Retention) Microbiome Resilience Health Outcomes, rigorously adjusting for confounders (age, sex, admixture, oral hygiene).
Work Package 4 - Transnational Baseline and Genomic Control To disentangle true migration-induced dysbiosis from secular trends, this WP establishes a comparative France-Mexico framework.
- Federated Data Harmonization: Rather than relying on primary data collection by the doctoral candidate in Mexico, the project leverages a secured data-sharing agreement with the Mexican partner institution.
- Ethical Data Stewardship: All biological sampling and sequencing will be executed under the institutional ethics approval in France and Mexico. The Occitanie team will integrate harmonized metadata and de-identified sequence data. A robust contingency plan guarantees access to established, published Mexican reference microbiomes should novel sampling be delayed.
Work Package 5 - Participatory Action Research and Translation The research will be conducted with, rather than simply on, the community. Through iterative participatory workshops with cultural partners in MEX-AGE 2.0, we will co-interpret preliminary findings within their sociocultural context. This ensures the co-design of culturally congruent health-promotion strategies, effectively translating our biological insights into tangible public health deliverables.