Effects of Physiological Relevant Bile Salts Combination on Duodenal/Ileum Monolayer: Mucin Secretion and Monolayer Integrity

Bile acids/salts (BAs/BSs) are recognized as a family of stimulators that play essential roles in regulating various functions of physiology within the intestinal tract, like promoting the metabolism of dietary lipids, stimulating mucin secretion, and tuning the commensal bacterial community. However, many of the in vivo results were not able to be reproduced by in vitro models. And most in vitro studies were focused on single BA/BS treatments. Here, we set up a bile salts and phosphatidylcholine complex model (BS/PC) that mimics the human physiological intestinal luminal fluid at fasted state.

In this experiment, 8-9 days old duodenal and ileal monolayers were exposed to BS/PC for 24 hours. After the exposure, the permeabilities of monolayers and the mucin concentrations were measured by the Lucifer Yellow assay and the Alcian Blue (AB) assay, respectively. ZO-1 and MUC2 proteins on the monolayer were stained to characterize the abundance of tight junction and mucus.

According to the confocal imaged and AB assay data, BS/PC exposure altered the morphology of the duodenal monolayer and increased tight junction and mucus production of duodenal/ileal monolayers. The LY assay data showed BS/PC exposure did not affect monolayer permeability significantly, indicating there’s no damage of BS/PC to duodenal and ileal monolayers. The results indicated that the complex bile salts could affect the intestinal mucosa in vitro at a physiologically relevant concentration.