The Lactobacillus rhamnosus R0011 secretome attenuates TNFα-induced pro-inflammatory gene expression in human HT-29 intestinal epithelial cells

Abstract

Abstract Probiotic lactic acid bacteria have been associated with a wide array of host-immune modulatory effects including modulation of pro-inflammatory gene expression. However, many questions remain about the exact cellular mechanisms through which these bacteria modulate host cell responses following pro-inflammatory challenge. The aim of this study was to elucidate the effects of the Lactobacillus rhamnosus R0011 secretome on TNFα-induced pro-inflammatory gene expression. Previous analysis has shown that the <10kDa fraction of the Lr R0011 secretome attenuates TNFα-induced IL-8 production from HT-29 intestinal epithelial cells (IECs). Whole-genome wide microarray analysis was used to further interrogate the impact of the <10kDa fraction of the Lr R0011 secretome on TNFα-induced gene expression. Contact with the <10kDa secretome fraction alone induced minimal changes in global gene expression by HT-29 IECs, with no increases in pro-inflammatory gene expression. However, the <10kDa fraction of the Lr R0011 secretome attenuated TNFα-induced expression of the pro-inflammatory mediators CCL10, CXCL1, CXCL10, CXCL11, IL-1β, IL-8, IL-17C, IL-23A, IL-32, and PTGS2, when compared to HT-29 IEC treated with TNFα alone. Co-challenge of HT-29 IECs with the <10kDa fraction of the Lr R0011 secretome and TNFα also resulted in an increase in the expression of dual specificity phosphatase 1 (DUSP1), a key regulator of the MAPK pathway, and of activating transcription factor 3 (ATF3), a negative regulator of innate immunity, relative to HT-29 IECs treated with TNFα alone. This provides insight into mechanisms through which these bacteria may influence innate immune activity at the IEC level through soluble mediators.