Project Grant F30DK146718

INVESTIGATING THE IMPACT OF INFANT FORMULA CARBOHYDRATES ON GUT MICROBIAL METABOLISM AND EPITHELIAL RESPONSES - PROJECT SUMMARY THE GUT MICROBIOTA PLAYS A CRITICAL ROLE IN SHAPING THE INTESTINAL ENVIRONMENT DURING EARLY LIFE, AND DIET IS ONE OF THE STRONGEST DETERMINANTS OF MICROBIAL COMPOSITION. WHILE THE EFFECTS OF HUMAN MILK AND INFANT FORMULA ON THE COMPOSITION OF THE GUT MICROBIOTA HAVE BEEN WELL DOCUMENTED, THE SPECIFIC IMPACT OF INDIVIDUAL FORMULA COMPONENTS, ESPECIALLY CARBOHYDRATES, REMAINS POORLY UNDERSTOOD. LACTOSE, THE PRIMARY CARBOHYDRATE IN HUMAN BREAST MILK, IS INCLUDED IN MANY INFANT FORMULAS. HOWEVER, ALTERNATIVE CARBOHYDRATES SUCH AS MALTODEXTRIN, A POLYSACCHARIDE DERIVED FROM CORN, ARE INCREASINGLY UTILIZED IN INFANT FORMULAS. CURRENTLY, THE IMPACT OF MALTODEXTRIN ON THE NEONATAL GUT MICROBIOTA AND HOST INTESTINAL RESPONSES HAS NOT BEEN THOROUGHLY CHARACTERIZED. AMONG THE EARLY MICROBIAL COLONIZERS OF THE INFANT GUT, LACTOBACILLUS SPECIES ARE PARTICULARLY IMPORTANT SINCE THEY SUPPORT INTESTINAL HEALTH THROUGH THEIR METABOLITE PRODUCTION. MY PRELIMINARY DATA INDICATES THAT LACTOBACILLUS SPECIES EXHIBIT DISTINCT GROWTH PATTERNS AND METABOLITE PRODUCTION DEPENDING ON THE AVAILABLE DIETARY SUBSTRATE. I ALSO DEMONSTRATE THAT COMPARED TO MALTODEXTRIN, LACTOSE-BASED FORMULAS ROBUSTLY ELEVATE FECAL LACTOBACILLUS LEVELS IN C57BL/6 PUPS. FURTHERMORE, TREATMENT OF INTESTINAL ORGANOIDS WITH LACTOBACILLUS-DERIVED METABOLITES LED TO THE UPREGULATION OF GENES INVOLVED IN GUT HOMEOSTASIS AND DOWNREGULATION OF PRO-INFLAMMATORY PATHWAYS, SUGGESTING THAT MICROBIAL METABOLITES CAN DIRECTLY MODULATE HOST EPITHELIAL RESPONSES. THIS PROJECT AIMS TO DETERMINE HOW LACTOSE AND MALTODEXTRIN SHAPE THE METABOLIC ACTIVITY OF NEONATAL GUT MICROBES AND HOW THESE MICROBIAL METABOLITES, IN TURN, INFLUENCE INTESTINAL EPITHELIAL DEVELOPMENT. MY CENTRAL HYPOTHESIS IS THAT LACTOSE PROMOTES A METABOLICALLY ACTIVE, LACTOBACILLUS-ENRICHED MICROBIOTA THAT GENERATES HOMEOSTATIC METABOLITES, WHEREAS MALTODEXTRIN SUPPORTS A LESS BENEFICIAL METABOLIC PROFILE THAT PROVIDES FEWER CUES TO SUPPORT EPITHELIAL FUNCTION. AIM 1 WILL DEFINE HOW LACTOSE AND MALTODEXTRIN AFFECTS LACTOBACILLUS METABOLITE PRODUCTION AND CHARACTERIZE THE RESULTING EPITHELIAL RESPONSES USING HUMAN INFANT INTESTINAL ORGANOIDS. METABOLITES WILL BE ANALYZED VIA UNTARGETED AND TARGETED METABOLOMICS (LC-MS/MS), AND HOST RESPONSES WILL BE ASSESSED THROUGH TRANSCRIPTOMIC (RNA-SEQ) AND FUNCTIONAL (FITC-DEXTRAN FLUX, ELISA) METHODS. AIM 2 WILL EVALUATE THE EFFECTS OF LACTOSE AND MALTODEXTRIN, WITH OR WITHOUT LACTOBACILLUS SUPPLEMENTATION, ON INTESTINAL DEVELOPMENT AND EPITHELIAL HEALTH IN NEONATAL MICE. FOLLOWING A TEN-DAY DIETARY INTERVENTION, INTESTINAL HEALTH WILL BE ASSESSED BY HISTOLOGY, IMMUNOHISTOCHEMISTRY, AND RNA-SEQ OF INTESTINAL TISSUES. STOOL SAMPLES WILL BE ANALYZED FOR MICROBIAL COMPOSITION (16S RRNA SEQUENCING) AND METABOLITE PROFILES (LC-MS/MS). TOGETHER, THE FINDINGS FROM THESE STUDIES MAY GUIDE THE DEVELOPMENT OF OPTIMIZED INFANT FORMULAS AND PROBIOTIC STRATEGIES TO SUPPORT NEONATAL GUT HEALTH. IMPORTANTLY, THE TRAINING SUPPORTED BY THIS F30 AWARD WILL PROVIDE A STRONG FOUNDATION FOR MY DEVELOPMENT AS AN INDEPENDENT PHYSICIAN-SCIENTIST AND FUTURE LEADER IN NEONATAL MICROBIOME RESEARCH.