Identification of probiotic lactobacillus with anti-inflammatory activity in the gastrointestinal tract

Abstract

In order to identify probiotic Lactobacillus for potential use as immunoprobiotics for the amelioration or treatment of inflammatory diseases in the gastrointestinal tract such as Helicobacter pylori-induced gastro-duodenal diseases and Clostridium difficile-associated disease (CDAD), we chose to test for the ability of human-derived Lactobacillus to modulate interleukin-8 (IL8) production in gastrointestinal epithelial cells. Eighty-seven gastric biopsy-derived Lactobacillus isolates were tested for their ability to modulate IL-8 production in H.pylori-stimulated AGS cells and 37 feces-derived isolates were tested in HT-29 cells stimulated with toxin A-positive C. difficile. Cell-free conditioned media of 12 Lactobacillus spp. Obtained from gastric biopsy were found to suppress IL-8 production in H. pylori-stimulated AGS cells in three separate experiments. The majority of these isolates (7/12) belongs to L. salivarius which is an indigenous flora of humans, whereas the rest belongs to transient flora such as L. plantarum and L. casei group. Cell-free conditioned media from 11 Lactobacillus spp. Obtained from infant feces significantly inhibited IL-8 production in C. difficile-stimulated HT-29 cells in one experiment. Four of these 11 Lactobacillus spp. Were re-tested and the result confirmed the inhibitory effect of these 4 Lactobacillus spp. These lactobacilli were 3 isolates of L. rhamnosus and one isolate of L. casei. These IL-8 suppressing Lactobacillus will be subjected to molecular typing for strain identity. Selected strains will be tested for their mechanism of action in the modulation of host signaling pathway as proposed in the research proposal. The probiotic candidate strains will also be tested for cytokine profile they elicit in the specific epithelial cells.