Human iPSC colon organoid function is improved by exposure to fecal fermentates

Authors: Pearce, Sarah; WEBER, GREGORY - Us Army Combat Capabilities Development Command (CCDC) Army; DOHERTY, LAUREL - Us Army Combat Capabilities Development Command (CCDC) Army; SOARES, JASON - Us Army Combat Capabilities Development Command (CCDC) Army

Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/18/2022
Publication Date: 4/12/2022
Citation: Pearce, S.C., Weber, G.J., Doherty, L.A., Soares, J.W. 2022. Human iPSC colon organoid function is improved by exposure to fecal fermentates. Journal of Federation of American Societies for Experimental Biology. 4(7):468-484. https://doi.org/10.1096/fba.2021-00166.
DOI: https://doi.org/10.1096/fba.2021-00166

Interpretive Summary: Trillions of bacteria reside in the gastrointestinal tract and regularly interact with our cells. This interaction results in many positive benefits to us including helping to digest and absorb food from the diet. Studying these interactions is difficult due to available models. The current paper shows how to combine two separate models (one used to study bacteria and one used to study the human intestine) to show how by-products from bacteria can provide a positive benefit to the human intestine. The result is a robust model that acts very similarly to what is shown in animal and human models. This research provides new information to investigators in public and private organizations interested in manipulating the gut microbiome/bacterial function to improve nutrition and intestinal health of humans and animals.

Technical Abstract: The host-microbe interaction is critical for intestinal homeostasis. By-products from microbial metabolism of unabsorbed dietary components have been studied increasingly as potential contributors to health and disease. In vitro fermentation systems provide a way to simulate microbial activity and by-product production of the colon using human fecal samples. Objectives of the study were to determine how clarified supernatants from two different fermentation conditions affect markers of cell proliferation, differentiation, barrier function, and immune function in a human induced pluripotent (iPSC) colon organoid model. Short-chain and branch-chain fatty acid concentrations of the supernatants were analyzed and were similar to known in vivo concentrations. Molecular results showed that 10 and 25% of the clarified supernatant from batch fermentation led to a more physiological intestinal phenotype including increased markers of differentiation (alkaline phosphatase, chromogranin-A), SCFA transport (monocarboxylate transporter-1), and mucin production (mucin-2, mucin-4) as well as increased tight junction expression (claudin-3) and a dose-response increase in barrier function. In addition, this is the first known study to utilize scanning electron microscopy in iPSC organoids. To further investigate host effects, clarified supernatants from a continuous multi-stage fermentation representing the ascending (AC), transverse (TC), and descending (DC) colonic domains were utilized and some regional differences were observed including increased markers of inflammation and pyroptosis (CASP1) in DC treated samples only. Overall, clarified supernatants represent a valuable model to examine effects of microbial by-products on host intestinal development and function and future efforts will be designed to further understand microbial communities and metabolites, along with additional host response measures.