Downregulation of intestinal epithelial innate response by probiotic yeast from kefir

RUMBO M; ROMANIN D E; SERRADELL M A; GONZÁLEZ MACIEL D; GARROTE G L

Río de Janeiro. Brasil

Congreso; 13th International Congress of Immunology; 2007

International Union of Immunological Societies, Asociación Latinoamericana de Inmunología, Sociedade Brasilera de Inmunologia,

There is evidence that commensal and probiotic bacteria can modulate innate response on intestinal epithelial cells. Knowledge on the activity of yeasts on intestinal epithelium is scarce. The aim of this study was to select yeast strains with the capacity to downregulate innate response in epithelial cell lines and determine the mechanisms responsible of this activity. Kefir grains are a complex symbiotic association of yeasts and lactic acid bacteria and were used as source of potentially probiotic yeasts. A panel of 30 yeast strains was screened using Caco-2 cell line stably transfected with a luciferase reporter construction under the control of CCL20 promotor. Several Saccharomyces and Kluyveromyces strains were found to inhibit more than 90% the activation of the reporter activity elicited by flagellin (1 mg/mL). The strain CIDCA 8154 of K marxianus that presented the highest inhibitory activity was selected for further studies. This strain inhibited completely the induction of CCL20, CXCL2 and IL-8 at the mRNA level upon flagellin (1mg/mL), TNFa (50 ng/mL) or IL-1b (10 ng/mL) stimulation. This activity was completely dependent on yeast viability and was not related to changes in pH of the culture medium along the experiment. Pre-treatment of epithelial cells with the selected strain downregulate NF-kB-dependent transcription in Caco-2 cells transiently transfected with a NF-kB reporter construction. This study shows that yeast strains from different genus are able to inhibit the intestinal epithelial innate response by downregulation of NF-kB activity, being putative candidates to be used for modulation of intestinal inflammatory conditions.