[i]Streptococcus thermophilus[/i] strains reduce expression of NF-κB in human intestinal epithelial cells
Résumé
The increase of inflammatory bowel diseases (IBD) is a major health concern in western countries. 11 Some commensal or ingested bacteria, such as some species of Lactobacillus and Bifidobacterium, are 12 known to reduce gut inflammation. In this context, species from the salivarius group have been shown 13 to reduce the immune response by inhibiting the inflammatory pathways. 14
The salivarius group harbours three species: Streptococcus salivarius, Streptococcus thermophilus and 15 Streptococcus vestibularis. S. salivarius, one of the earliest colonizers of the oral cavity and digestive 16 tract, exhibits in vitro and in vivo anti-inflammatory effects. We have demonstrated that S. salivarius 17 strains can significantly reduce the IL-8 secretion and the activation of the NF-κB pathway in several 18 intestinal epithelial cells (1). NF-kB is a transcriptional factor playing a central role in human 19 inflammatory response, and especially in IBD. Immuno-modulation properties are linked to active 20 compounds released during the growth of S. salivarius. This anti-inflammatory potential was 21 confirmed by an inhibition of inflammation in mouse models of colitis (2). 22
In this work, we investigated the immuno-modulatory effects of S. thermophilus, another species of 23 the salivarius group. This species is widely used in dairy production. Some studies have already 24 described positive effects of commercial S. thermophilus strains on inflammatory response. We 25 analyzed the effect of commercial strains and strains isolated from traditional dairy products on the 26 NF-κB expression in human cells. Immuno-modulation properties of cell free supernatants and live 27 S. thermophilus strains were assessed on TNFα-induced NF-κB activation in HT-29 cells. The step of 28 the NF-κB pathway modulated by S. thermophilus strains in the HT-29 cell model was analyzed by 29 Western-blot. The anti-inflammatory properties and its GRAS (Generally Recognized As Safe) status 30 enable S. thermophilus strains to be considered as potential probiotics.