No abstract

Immunomodulatory effects of lactic acid bacteria vary with strain and may vary with growth phase and medium. The ability of different lactobacilli strains (Lactobacillus helveticus R0052, L. rhamnosus R0011, L. rhamnosus GG) at different growth phases to modulate macrophage and intestinal epithelial cell cytokine production following a proinflammatory challenge was examined. Soy and milk ferments were also prepared with strains shown to grow well in soy milk (Bifidobacteria longum R0175 and Lactobacillus helveticus R0052). Modulation of cytokine production by human macrophage cell lines (U937 and THP-1) and intestinal epithelial cells (HT-29) induced by Tumor Necrosis Factor αwas assayed by ELISA for interleukin-8 (IL-8) production. Strain-dependent differences were observed in the ability of spent MRS broths from log versus stationary growth phase, and of soy and milk ferments to down-regulate IL-8 production by challenged U937 cells. Overall, variation in immunomodulatory activity of these lactic acid bacteria reflects not only strain variation but potentially also differences in growth phase and substrate. Funded by NSERC, Lallemand Inc. and the Canadian Space Agency.