Alterations in the microbiota along the gastrointestinal tract resulting from dietary fiber supplementation

Emerging studies support the association of gut microbiota, the aggregate of microorganisms within the gastrointestinal (GI) tract, with a range of upper airway diseases through a relationship known as the gut microbiota-airway axis. Asthma, an inflammatory airway disease is growing in frequency among low-income and minority communities; likely due to environmental factors such as consumption of a high-fat, low-fiber western diet. Individuals consuming a western diet likely experience shifts in their GI microbiota, thereby increasing asthmatic risk. We hypothesize that GI microbial metabolism of non-digestible dietary fiber produces anti- inflammatory metabolites such as short-chain fatty acids (SCFAs) which reduce allergic or asthmatic inflammation. Further, we hypothesize that dietary fibers differentially alter the gut microbiota in the ileum (a critical site for immune modulation), the cecum (the site for fiber fermentation), and the colon (a secondary site for fiber fermentation). To test these hypotheses, we performed 16S rRNA gene sequencing on 64 ileum, cecum, and fecal samples from mice maintained on a Western Diet or an ingredient-matched Control Diet and supplemented with placebo or soluble fiber. Microbiome bioinformatics was performed using QIIME 2 to evaluate changes in microbial composition or diversity of the GI microbiota. This project primarily focuses on establishing the effects of diet and fiber supplementation on gut microbiota. Additionally, the goal will be to determine how dietary fibers change the microbiota along different GI niches, advancing our understanding of fiber supplementation on the GI microbiota and respiratory illnesses.