• Probiotics
• bifidobacteria
• dendritic cells
• regulatory T cells
• 2,4,6-trinitrobenzene sulphonic acid
• probiotics
• lactobacillus
• inflammatory bowel disease
• immunoregulation

The mammalian gastrointestinal tract harbours a vast number of bacterial residents, recently referred to as the microbiota, which are instrumental in supporting energy metabolism and immune function of the host. A large number of studies have highlighted the fact that certain (pathogenic) micro-organisms can be harmful to the health of their host, while more recently an increasing number of papers have attributed direct beneficial health effects to the gut microbial community. As these bacteria encode 100 times more genes than present in the human genome, the partnership of the host with its microbiota constitute a ‘superorganism’.1 Homoeostasis in this superorganism is sustained through an optimal cohabitation of the host with this microbiota, keeping the balance between commensals and pathogens, but also between proinflammatory and regulatory responses. The composition of the gut microbiota has indeed been shown to be an important determinant of Th17:Treg balance and may thus influence intestinal immunity and tolerance.2 Disturbing alterations in the composition of the microbiota (a process known as dysbiosis) will compromise such homoeostasis and promote the development of various inflammatory disorders, such as inflammatory bowel disease. An in-depth understanding of the mechanisms underlying host–symbiont relationships will be pivotal for the development of new therapeutic or prophylactic interventions targeting the intestinal microbiota.

One such approach is the use of probiotics, mainly lactobacilli and bifidobacteria, to impact on …