Effect of bacteria used in food industry on the proliferation and cytokine production of epithelial intestinal cellular lines

The gastrointestinal mucosa, composed mainly of a monolayer of intestinal epithelial cells (IEC) covered by mucus, represents the first contact point of gut and orally ingested bacteria with the host. This bacteria-IEC interaction is important for maintenance of gut homeostasis. Here we assessed the capability of eleven bacteria to interact with two IEC types (Caco2 and HT29). The effect of the microorganisms upon IEC growth and proliferation, as well as on cytokine production, was determined. A high dependence on both the IEC line used and the strain tested was observed. None of the strains modified the growth or proliferation of HT29-cells but some affected that of Caco2. The presence of the bacteria did not affect cytokine production by Caco2-cells, but some strains modulated the cytokine production by HT29-cells. IL-1β and IL-6 production was reduced by all bacteria tested and most, except Bifidobacterium longum 1/10, Bifidobacterium breve 99/E8 and Propionibacterium freudenreichii PJS, reduced the production of IL-8. Lactococcus lactis ARH4 was the bacteria stimulating the highest production of TNFα, whilst Pr. freudenreichii PJS significantly increased IL-10 production and Bifidobacterium animalis Bb12 reducing it. This work evidences that the cellular model used to test bacterial host-cells interaction has a great impact on the results obtained.