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Social inequalities in the gut microbiome: individual participants meta-analyse of population-level data

English title Social inequalities in the gut microbiome: individual participants meta-analyse of population-level data
Applicant Cullati Stéphane
Number 190293
Funding scheme Spark
Research institution Institut de recherches sociologiques Faculté des Sciences de la Société Université de Genève
Institution of higher education University of Geneva - GE
Main discipline Health
Start/End 01.01.2020 - 31.12.2020
Approved amount 79'642.00
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All Disciplines (3)

Public Health and Health Services

Keywords (3)

Health; Inequalities; Microbiom

Lay Summary (German)

Soziales Leben und Darmmikrobiom
Lay summary

Obwohl sich die Gesundheit der Bevölkerung in den letzten fünf Jahrzehnten erheblich verbessert hat, bleiben die gesundheitlichen Ungleichheiten zeitlich und räumlich zumindest stabil oder nehmen sogar zu. Wenn der Zusammenhang zwischen sozialen Merkmalen und Gesundheit gut etabliert ist, sind die biologischen Wege zwischen sozialer Exposition und Gesundheit weniger klar. Epigenetische Faktoren und das Stressmodell (McEwen 1998) zogen die meisten empirischen Belege für biologische Pfade an. Jüngste Fortschritte in der Grundlagenforschung und in der klinischen Forschung haben die wichtige Rolle des Darm-Mikrobioms für die Gesundheit unterstrichen. Wir gehen davon aus, dass das Darm-Mikrobiom ein weiterer biologischer Weg sein könnte, der die soziale Exposition und den Gesundheitszusammenhang vermittelt.

Direct link to Lay Summary Last update: 07.01.2020

Lay Summary (French)

Conditions de vie et microbiome intestinal
Lay summary

Malgré une amélioration substantielle de la santé de la population au cours des cinq dernières décennies, les inégalités en matière de santé restent stables et constantes dans le temps et dans l’espace, voire s’accentuent. Si le lien entre caractéristiques sociales et santé est bien établi, les voies biologiques entre expositions sociales et santé sont moins claires. Les facteurs épigénétiques et de stress ont attiré la plupart des preuves empiriques sur les voies biologiques. Les progrès récents de la recherche fondamentale et clinique ont mis en évidence le rôle important du microbiome intestinal pour la santé. Notre hypothèse est que le microbiome intestinal pourrait être une autre voie biologique médiatisant le lien entre conditions sociales de vie et santé.

Direct link to Lay Summary Last update: 07.01.2020

Responsible applicant and co-applicants



Background: Despite substantial improvement in population health in the past five decades, health inequalities remain stable and consistent across time and space, if not increasing. If the link between social characteristics and health is well-established, the biological pathways between social exposures and health are less clear. Epigenetic factors and the stress model (McEwen 1998) attracted most of the empirical evidence on biological pathways. Recent advances in basic and clinical researches have highlighted the important role of the gut micro-biome for health. We hypothesis that the gut micro-biome could be another biological pathway mediating the social exposures and health link. Objective: To examine the associations between social variables and gut micro-biome biomarkers signatures. Method: individual participants meta-analyse of general population-level gut microbiome. Studies will be included if 1) participants are healthy patients or from the general population, 2) they collected data on the gut microbiome and 3) social information (social status and socioeconomic) on participants. Studies will be identified through literature review of studies on healthy participants, repositories of gut microbiome data (Human Microbiome Project Data Portal, European Genome-phenome Archive), and citizen science microbiome projects (e.g., Microsetta Initiative). Studies’ principal investigators (PI) will be contacted and screened for possible inclusion in the meta-analyse. First, analyses will be performed in each study, separately. Association between socioeconomic (primary objective) and social status (secondary objective) variables and gut biomarkers signatures will be estimated by generating odds ratios and 95% confidence intervals estimated with logistic regression analysis. Dichotomisation of biomarkers will be made following clinical guidelines, corrected for sex and age strata when appropriate, and checked by an expert in microbiology collaborating with our team. When appropriate, the analyses will be stratified by sex. When gut biomarkers will be measured repeatedly, the difference between baseline and follow-up will be estimated, and attrition will be included in the estimation. Second, estimates will be pooled in a meta-analysis. Fixed or random effect models will be determined depending on studies heterogeneity. Heterogeneity between studies will be computed with I2 and t2 statistics and 95% prediction intervals for odds ratios will be used to account for t2. Funnel plots will be assessed to identify if biases are operating in the findings. Robustness and sensitivity analyses will be conducted (molecular techniques bias, selection bias).Expected results: we expect cross-sectional associations between socioeconomic status and gut micro-biome signatures, suggesting a social gradient in the gut micro-biome of the general population. Limitations: the gut micro-biome is expected to be a potential, new, biological mediator between social exposures and health, however further researches collecting longitudinally data of gut micro-biome, dietary habits, anthropometrics measures, lifestyles and diseases information, social and life course information, will be needed to confirm this hypothesis.