Butyrate switches the pattern of chemokine secretion by intestinal epithelial cells through histone acetylation.

BACKGROUND Butyrate, a fermentation product of intestinal bacteria, modifies chromatin structure through histone acetylation, thereby altering gene transcription. IL-8 and MCP-1 are chemokines, expressed by intestinal epithelial cells, which attract neutrophils and monocytes, respectively. We hypothesized that butyrate may alter IL-8 and MCP-1 expression by intestinal epithelial cells through histone acetylation. MATERIALS AND METHODS IL-8 and MCP-1 expression was measured by ELISA and RNA transfer blots. Acetylated histones were separated on acetic acid-urea-triton gels. Butyrate was compared to Trichostatin-A, a specific inhibitor of histone deacetylase and to other short chain fatty acids. RESULTS Caco-2 cells constitutively secreted MCP-1 but not IL-8. Butyrate reversibly decreased MCP-1 secretion. In contrast, butyrate increased IL-8 production. The effects of butyrate and Trichostatin-A were greater when cells were stimulated with IL-1beta. Butyrate and Trichostatin-A both increased histone acetylation. Trichostatin-A and other short chain fatty acids altered chemokine secretion according to their effect on histone acetylation. CONCLUSIONS Butyrate reversibly switches chemokine secretion by epithelial cells through histone acetylation. We speculate that butyrate carries information from resident bacteria to epithelial cells. Epithelial cells transduce this signal through histone acetylation, modulating the secretion of chemokines.