CONICET | Buscador de Institutos y Recursos Humanos

Short chain fatty acids (SCFA), acetate, propionate and butyrate are the main fermentation products of intestinal microbiota. Beyond in situ generation, they can also be found, as well as lactic acid, in fermented food products. These molecules have been identified as targets of G-protein coupled receptors and are putative mediators of host immune response modulation. The aim of this work was to analyze the capacity of SCFA to modulate intestinal epithelial innate response. We used reporter cell line Caco2-CCL20:luc, that is a human intestinal epithelial line stably transfected with luciferase under the control of CCL20 promoter. We used dose response pretreatment with neutralized filtrated solutions of acetate, propionate, lactate and butyrate (1 to 100 mM). 30 minutes pretreatment with the different SCFA downregulated in a dose response manner the luciferase activity induced by stimulation with either flagellin of S. typhimurium (FliC, 1 µg/ml) or IL-1β (10 ng/ml) as well (p˂0.05). Similar results were observed at the mRNA level using RTqPCR. Maximal inhibition of FliC-induced CCL20 expression was observed upon pretretment with 100 mM of SCFA (p˂0.05). In all cases, butyrate and propionate showed higher capacity to modulate activation than lactate and acetate. SCFA pretreatment does not affect basal expression of CCL20, neither of different housekeeping epithelial cell genes. Using transient transfection with a NFkB driven reporter system we observed that lactate pretreatment downregulates this signaling pathway in Caco-2 cells. Although SCFA pretreatment affects intracellular levels of AMPc, we could not observed inhibition of SCFA activity upon pretreatment of cells with Bordetella pertussis toxin. Our results showed that SCFA, at concentrations that can be found within the colonic lumen or in fermented food products can modulate epithelial innate response in vitro