Adhesion and immunomodulatory effects of Bifidobacterium lactis HN019 on intestinal epithelial cells INT-407

To elucidate the adherence and immunomodulatory properties of a probiotic strain Bifidobacterium lactis (B. lactis) HN019.

Adhesion assays of B. lactis HN019 and Salmonella typhimurium (S. typhimurium) ATCC 14028 to INT-407 cells were carried out by detecting copies of species-specific genes with real-time polymerase chain reaction. Morphological study was further conducted by transmission electron microscopy. Interleukin-1beta (IL-1beta), interleukin-8, and tumor necrosis factor-alpha (TNF-alpha) gene expression were assessed while enzyme linked immunosorbent assay was used to detect IL-8 protein secretion.

The attachment of S. typhimurium ATCC 14028 to INT407 intestinal epithelial cells was inhibited significantly by B. lactis HN019. B. lactis HN019 could be internalized into the INT-407 cells and attenuated IL-8 mRNA level at both baseline and S. typhimurium-induced pro-inflammatory responses. IL-8 secretion was reduced while IL-1beta and TNF-alpha mRNA expression level remained unchanged at baseline after treated with B. lactis HN019.

B. lactis HN019 does not up-regulate the intestinal epithelium expressed pro-inflammatory cytokine, it showed the potential to protect enterocytes from an acute inflammatory response induced by enteropathogen.