title: Short-chain fatty acids activate AMP-activated protein kinase and ameliorate ethanol-induced intestinal barrier dysfunction in Caco-2 cell monolayers.
abstract: Short-chain fatty acids (SCFAs) have been shown to promote intestinal barrier function, but their protective effects against ethanol-induced intestinal injury and underlying mechanisms remain essentially unknown. The aim of the study was to analyze the influence of SCFAs on ethanol-induced barrier dysfunction and to examine the role of AMP-activated protein kinase (AMPK) as a possible mechanism using Caco-2 monolayers. The monolayers were treated apically with butyrate (2, 10, or 20 mmol/L), propionate (4, 20, or 40 mmol/L), or acetate (8, 40, or 80 mmol/L) for 1 h before ethanol (40 mmol/L) for 3 h. Barrier function was analyzed by measurement of transepithelial resistance and permeation of fluorescein isothiocyanate-labeled dextran. Distribution of the tight junction (TJ) proteins zona occludens-1, occludin, and filamentous-actin (F-actin) was examined by immunofluorescence. Metabolic stress was determined by measuring oxidative stress, mitochondrial function, and ATP using dichlorofluorescein diacetate, dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide, and bioluminescence assay, respectively. AMPK was knocked down by small interfering RNA (siRNA), and its activity was assessed by a cell-based ELISA. Exposure to ethanol significantly impaired barrier function compared with controls (P < 0.0001), disrupted TJ and F-actin cytoskeleton integrity, and induced metabolic stress. However, pretreatment with 2 mmol/L butyrate, 4 mmol/L propionate, and 8 mmol/L acetate significantly alleviated the ethanol-induced barrier dysfunction, TJ and F-actin disruption, and metabolic stress compared with ethanol-exposed monolayers (P < 0.0001). The promoting effects on barrier function were abolished by inhibiting AMPK using either compound C or siRNA. These observations indicate that SCFAs exhibit protective effects against ethanol-induced barrier disruption via AMPK activation, suggesting a potential for SCFAs as prophylactic and/or therapeutic factors against ethanol-induced gut leakiness.
authors.affiliation: Top Institute Food and Nutrition, Wageningen, The Netherlands.
authors.forename: Elhaseen E
authors.initials: EE
authors.lastname: Elamin
authors.forename: Ad A
authors.initials: AA
authors.lastname: Masclee
authors.forename: Jan
authors.initials: J
authors.lastname: Dekker
authors.forename: Harm-Jan
authors.initials: HJ
authors.lastname: Pieters
authors.forename: Daisy M
authors.initials: DM
authors.lastname: Jonkers
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D018938:Caco-2 Cells; D004789:Enzyme Activation; D000431:Ethanol / Q000494:pharmacology*; D005227:Fatty Acids / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D007413:Intestinal Mucosa / Q000187:drug effects* / Q000201:enzymology
chemical_list: D005227:Fatty Acids; D000431:Ethanol; D055372:AMP-Activated Protein Kinases