Short‐Chain Fatty Acid Induces Intestinal Mucosal Injury in Newborn Rats and Down‐Regulates Intestinal Trefoil Factor Gene Expression In Vivo and In Vitro

Abstract

Luminal administration of short-chain fatty acids (SCFAs) induces dose-dependent intestinal mucosal injury in newborn rats. However, the mechanism underlying the injurious effects of SCFAs on intestinal mucosa in neonates is unclear. Intestinal trefoil factor (ITF) is a factor important for the maintenance and repair of the intestinal mucosal barrier. Regulation of ITF gene expression by SCFAs may be involved as one of the mechanisms. To examine the effect of butyrate-induced colonic injury on ITF gene expression in vivo and to determine the molecular mechanisms underlying the butyrate regulation of ITF gene expression in vitro. Whole-section colonic tissues from 9- to 10-day-old Sprague-Dawley rats that have received butyric acid at two different concentrations (150 mmol/L and 300 mmol/L) and for different time periods were processed for total RNA extraction and Northern blot analysis. Littermates that received normal saline or lactic acid at 300 mmol/L served as controls. The effect of butyrate on ITF gene expression was also examined in vitro with human colonic epithelial LS 174T cells. To further define ITF gene regulation by butyrate, transient transfection assays were performed on a 930 bp human ITF promoter-luciferase reporter gene plasmid in LS174T cells with or without the presence of butyrate. Concurrent with mucosal injury, butyric acid inhibited ITF gene expression in colonic tissues of newborn rats as well as in intestinal epithelial cells in a dose- and time-dependent manner. Furthermore, butyrate reduced ITF promoter report gene activity in transfected LS174T cell, suggesting that butyric acid regulation of ITF gene is by way of a specific ITF promoter. Butyric acid induced-intestinal mucosal injury in newborn rats is associated with down-regulation of ITF gene expression. The changes in ITF gene expression in vivo may play a role in the pathogenesis of SCFA-induced intestinal mucosal injury.