Interacting Lactobacillus plantarum and human intestinal epithelial cells: potential effects on host immune response.

FAO and WHO guidelines define as 'probiotics' those microorganisms which confer a health benefit to the host. Most of the currently used probiotics belong to the genera of Lactobacillus and Bifidobacterium. Lactobacillus plantarum (Lp) is a lactic acid bacterium (LAB) which grows on various substrates, including animal and vegetable foods (either as autochthonous contamination or being added as starter culture), soil and mammalian intestine. We have generated Lp WCFS1 mutant strains which are defective for different stress response genes. Preliminary works suggest that some of these strains might present distinctive cell surface physico-chemical and morphological features. Because bacterial cell envelope is primarily implicated in cell-host interaction, with the aim to evaluate their potential probiotic properties, we have compared the effects of wild type and mutant L. plantarum cells on the expression pattern of some immune-related genes in human intestinal epithelial cells. Caco-2 monolayers were incubated with bacterial cells at defined titre; transcriptional profiling of human immune genes was assessed by real time quantitative RT-PCR