Lactobacilli stimulate the innate immune response and modulate the TLR expression of HT29 intestinal epithelial cells in vitro

VIZOSO PINTO, M. G.; ROFRIGUEZ GÓMEZ, M.; SEIFERT, S.; WATZL, B.; HOLZAPFEL, W. H.; FRANZ, C. M. A. P.

INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY

ELSEVIER SCIENCE BV

Año: 2009 vol. 133 p. 86 - 93

0168-1605

The potentially probiotic strain Lactobacillus plantarum BFE 1685 isolated from a child´s faeces and the probiotic strain Lactobacillus rhamnosus GG were investigated for their capability to influence the innate immune response of HT29 intestinal epithelial cells towards Salmonella enterica serovar Typhimurium. Furthermore, their capacity to modulate toll-like receptor expression of HT29 cells was  investigated at the mRNA and protein levels. TNF-α was used in cell culture with HT29 cells to  mimic an inflammatory background, and in the presence of this chemokine HT29 cells were  sensitised to respond to the Lactobacillus strains as evidenced by an increased response in IL-8  production. In addition, when HT29 cells were first treated with lactobacilli and then infected  with S. Typhimurium, the IL-8 levels in response to S. Typhimurium were significantly higher,  indicating that HT29 cells were sensitised by lactobacilli. Neither of the lactobacilli was able to  stimulate TLR4 production at the mRNA level, however, TLR2 and TLR9 transcription levels  measured by quantitative PCR were up-regulated when HT29 cells were incubated with lactobacilli, but not with S. Typhimurium. Up-regulation of TLR9 expression was higher for L.  rhamnosus GG than for L. plantarum BFE 1685. Expression levels of TLR2 and TLR5 were  enhanced also at the protein level as determined by flow cytometry after staining with the  respective antibodies. In contrast, TLR9 expression was not significantly up-regulated, which  may be explained by protein degradation, or possible down-stream regulatory effects. These  findings show that stimulation of specific signaling pathways occurs in the crosstalk between  probiotic bacteria and gut epithelium cells, which can help to explain the adjuvant properties of probiotic lactobacilli.