Butyrate Enhances the Intestinal Barrier by Facilitating Tight Junction Assembly via Activation of AMP-Activated Protein Kinase in Caco-2 Cell Monolayers

Abstract

Butyrate, one of the SCFA, promotes the development of the intestinal barrier. However, the molecular mechanisms underlying the butyrate regulation of the intestinal barrier are unknown. To test the hypothesis that the effect of butyrate on the intestinal barrier is mediated by the regulation of the assembly of tight junctions involving the activation of the AMP-activated protein kinase (AMPK), we determined the effect of butyrate on the intestinal barrier by measuring the transepithelial electrical resistance (TER) and inulin permeability in a Caco-2 cell monolayer model. We further used a calcium switch assay to study the assembly of epithelial tight junctions and determined the effect of butyrate on the assembly of epithelial tight junctions and AMPK activity. We demonstrated that the butyrate treatment increased AMPK activity and accelerated the assembly of tight junctions as shown by the reorganization of tight junction proteins, as well as the development of TER. AMPK activity was also upregulated by butyrate during calcium switch-induced tight junction assembly. Compound C, a specific AMPK inhibitor, inhibited the butyrate-induced activation of AMPK. The facilitating effect of butyrate on the increases in TER in standard culture media, as well as after calcium switch, was abolished by compound C. We conclude that butyrate enhances the intestinal barrier by regulating the assembly of tight junctions. This dynamic process is mediated by the activation of AMPK. These results suggest an intriguing link between SCFA and the intracellular energy sensor for the development of the intestinal barrier.

Streptozotocin-induced type-1-diabetes disease onset in Sprague–Dawley rats is associated with an altered intestinal microbiota composition and decreased diversity

“…Lactic acid producers such as Lactobacillus, Lactococcus, Bifidobacterium and Streptococcus were higher in the faeces of children pre-diagnosed with autoimmune diabetes (Brown et al, 2011). The fate of lactate is crucial in determining intestinal health as conversion to butyrate results in mucin synthesis (Barcelo et al, 2000;Burger-van Paassen et al, 2009;Finnie et al, 1995;Shimotoyodome et al, 2000) and tighter junctions (Peng et al, 2007(Peng et al, , 2009, while conversion to other SCFA, such as propionate and acetate does not induce mucin synthesis (Brown et al, 2011). Mucin is a glycoprotein made by the host that maintains the integrity of intestinal epithelium (Brown et al, 2011).…”

From the gut to the peripheral tissues: the multiple effects of butyrate

“…The authors suggested that LOX activated by butyrate may induce cellular differentiation and in addition it could control tight-junction permeability. A recent paper showed that one possible mechanism of action of butyrate on tight junctions involves the AMP-activated protein kinase, but how this kinase is activated by butyrate remains unclear (174) . One hypothesis could be that butyrate enhances the energetic state of the cell (increase of cellular ATP content).…”

“…In vitro, butyrate increases expression of the MUC gene (173) but the effect seems to be dose dependent (164) . In Caco-2 cells, a decrease in butyrate increases intestinal permeability (174) and butyrate up-regulates lipoxygenase 5-LOX, 12-LOX and 15-LOX mRNA expression (175) . The authors suggested that LOX activated by butyrate may induce cellular differentiation and in addition it could control tight-junction permeability.…”

Protection against Gluten-mediated Tight Junction Injury with a Novel Lignite Extract Supplement

“…Some of these substances include the bioflavonoid quercetin and indole, butyrate, nicotine, the amino acid L-glutamine, the mineral zinc, the pharmaceutical compound and zonulin-inhibitor larazotide, and now the novel lignite extract studied here [19][20][21][22][23][24][25][26][27][28][29][30]. The lignite extract supplement has unique biologic effects among these reported compounds in both the speed of response in the TEER functional analysis of the tight junction, which occurred within 60 min from introduction to the membranes, and the extent of the response in regard to tight junction protein expression as seen by immunofluorescence.…”