A human enteroid model to study the effect of short‐chain fatty acids on the intestinal epithelium

Abstract

Short‐chainfatty acids (SCFA) are dietary fiber derived bacterial metabolites thought to be beneficial to thehost. Of high interest is butyrate (BUT) which is the main fuel source for absorptivecells in the colon; as well as acetate (ACET) and propionate (PROP). Effects of BUT on intestinal physiology have been studied in several in vitro models, however, data in primary cells, includingintestinal stem cells (ISCs) and their distinct progenies is still not fullycharacterized. Recent advances inenteroid models have allowed these mechanisms to be studied in a more physiologically relevant human model. Therefore, our objective was to examine effects of BUT, ACET, and PROP on biomarkers of ISC activity, differentiation, barrier function and epithelial defense in the intestine using human 2‐dimensional (2D) and 3‐dimensional (3D) enteroid models. Duodenal 2D and 3D enteroids were treated with 10 mM BUT, ACET, or PROP for 24 h. Gene expression of stem cell marker Lgr5 was increased more than2‐fold in 3D enteroids treated with ACET. Conversely, enteroids treated with BUT and PROP had a greater than 10‐fold decrease in Lgr5 compared to controls (CON). Enterocyte biomarker alkaline phosphatase (Alpi) was increased due to all SCFA treatments (P<0.05). Gene expression of goblet cell marker mucin‐2 (Muc2) was increased 2 and 5‐fold due to ACET and BUT treatments respectively, but not due to PROP treatment. Paneth cell marker lysozyme (Lyz) increased due to BUT treatment and enteroendocrine cell marker chromogranin‐A (Chga) was increased 170‐fold in BUT treated enteroidsalone. Tuft cell marker Dclk1 was elevated due to ACET (7‐fold) and BUT (14‐fold) treatment compared to CON (P<0.05). Anti‐microbial molecule gene expression of Reg3b and Reg3g were not increased due to ACET treatment, however, were increased due to BUT (2.5‐fold and3‐fold, respectively) treatment. Defb1 gene expression increased 66‐fold and 75‐fold respectively in BUT and PROP treated enteroids (P<0.05). Tight junction marker expression of Ocln was only elevated in ACET treated organoids (4‐fold; P<0.05). However, Cldn3 and Tjp1 were increased due to both ACET and BUT treatments (P<0.05). 2Denteroid monolayers treated with BUT had a 2.4‐fold increase in relative transepithelial electrical resistance (TEER) compared to CON (P<0.05). PROP treatment also increased TEER (P < 0.05), while ACET had no effect. Protein expression of Interleukin‐8 in the media was induced by exposure to BUT (1.8‐fold increase) and PROP (1.5‐fold increase), but not ACET(P<0.05). Similarly, Interleukin‐18expression was increased by BUT (1.7‐fold increase) and PROP(1.3‐fold increase), while ACET was not different from CON. Intestinal Trefoil factor 3 expression in the media was increased1.3‐fold due to BUT treatment only (P<0.05). In conclusion, we determined that human enteroids are valuable and physiologically relevant models to study the effects of bacterial metabolites based upon the responses we examined. This work will be useful for future microbiomeand nutritional work using enteroid models.Support or Funding InformationFunding was provided by the Department of Defense Combat Feeding Research and Engineering Program through project “Gut Microbiomeand Performance Nutrition (TB 15–19).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.