Suppressive action of acetate on interleukin-8 production via tubulin-α acetylation.

Acetate is the major short-chain fatty acid produced by commensal bacteria in the gut and is known as a nutrient source for epithelial cells of the mucosa. Acetate also suppresses interleukin (IL)-2 production in T cells by inhibiting nuclear factor of activated T cells (NFAT) nuclear translocation via tubulin-α acetylation. Using acetylation of tubulin-α as a biomarker, we have examined the influence of acetate in the large intestine. Because of high concentrations of acetate in fecal material, tubulin-α acetylation is dominant in the proximal large intestine relative to other sections of the large intestine and is induced in epithelial cells of the colonic mucosa. Flagellin stimulation induces IL-8 production in epithelial cells and acetate suppresses this IL-8 production via tubulin-α acetylation. Flagellin stimulation activates nuclear factor-κB, CREB and AP-1, but not NFAT. Of these transcription factors, acetate specifically inhibits AP-1 activation. Acetate impairs flagellin-induced activation of the Rap1-MEK-ERK-Elk-1 pathway with acetylation of tubulin-α that is bound to Rap1, resulting in reduced expression of c-Fos, a subunit of AP-1. These findings reveal a novel action of acetate via tubulin-α acetylation in epithelial cells of the colonic mucosa.