Fatty acid shifts the cellular composition of small intestinal organoids towards a secretory cell lineage.

Intestinal epithelial cells are highly sensitive to nutritional cues within the gut lumen. Although numerous studies have linked high-fat diets (HFD) to intestinal dysfunction, the mechanisms by which these diets alter epithelial cell composition to contribute to metabolic disease remain poorly understood. We used intestinal organoids to examine how exposure to a high-fat environment alters epithelial cell composition by quantifying the relative abundance of different epithelial cell types. We generated intestinal organoids using crypts isolated from C57BL/6 mouse small intestine. The organoids were exposed to free fatty acid, oleic acid (OA), for up to 7 days, and a multi-colour flow cytometry panel was used to assess changes in the density of different epithelial cell types. Changes in organoid morphology was assessed by measuring crypt depth and total organoid area. Exposure to OA significantly increased organoid size and crypt depth after 24 h. After 72 h, OA increased the proportion of transit amplifying cells and secretory progenitors, while reducing the density of absorptive cells and absorptive progenitors. The proportion of enteroendocrine and tuft cells also increased 3- and 7-days post OA treatment. Fatty acid exposure increases transit amplifying cell proliferation, which promotes organoid growth and crypt elongation. OA exposure shifted the differentiation trajectory of epithelial cells towards enteroendocrine and tuft cell fates. Given that enteroendocrine cell hormones regulate energy balance, understanding how dietary components alter the density of enteroendocrine cells could underscore the potential for diet-based therapies for the treatment of metabolic disease.