Characterizing immunomodulatory activity of lactic acid bacteria on cell types involved in innate immunity: analysis of the effects of Lactobacillus rhamnosus R0011-derived milk ferments on macrophage polarization and of secretome effects on intestinal epithelial cell cytokine production

Abstract

Probiotic lactic acid bacteria have been associated with a wide array of host-immune modulatory effects including down-regulation of pro-inflammatory gene transcription and expression following pro-inflammatory challenge, through direct and indirect contact with host immune cells. However, it is still unknown how many of these microorganisms convey these beneficial immune effects to the host. Lactobacillus rhamnosus R0011 and Lactobacillus helveticus R0389 were examined for their immunomodulatory activity on challenged human HT-29 and rat IEC-6 intestinal epithelial cells (IEC). Secreted products from both strains demonstrated the ability to down-regulate IL-8 production from challenged HT-29 with differential effects on CINC-1 production from challenged IEC-6 cells. Further, L. rhamnosus R0011-derived milk ferments were tested for their ability to modulate pro-atherogenic cytokine production from challenged human THP-1 and U937 monocytes and macrophages. Culturing THP-1 and U937 macrophages with milk ferments resulted in the up-regulation of regulatory cytokine production in response to challenge with lipopolysaccharide indicating possible polarization into the regulatory M2b macrophage phenotype. Taken together, L. rhamnosus R0011 has been shown to have immunomodulatory activity on a variety of cells involved in innate immunity.