gasseri strains. Our work indicated the existence of strain-specific effects of L. gasseri. This modulatory activity was found to be associated with

the production of bacterial metabolites distinctively impacting both the immune and anti-oxidant properties of IECs and DCs. Methods Bacterial strains PXD101 mouse and culture conditions Lactobacillus gasseri OLLL2809 (from human intestine; deposited in the Patent Microorganisms Depositary, National Institute of Technology and Evaluation, Japan, Accession n. NITE BP-72) and L13-Ia (from raw bovine milk, deposited in the Microbial Culture Collection, Institute of Sciences of Food Production, Italy, Accession n. 13541) were studied. Strain OLL2809 is considered to be a probiotic strain [22], while potential probiotic features of strain L13-Ia,

able to resist to simulated Torin 2 gastric and pancreatic digestion, as well as to bovine and porcine bile salts were previously demonstrated [23]. Working cultures were grown in deMan Rogosa Sharpe (MRS) broth (Difco, Detroit, Michigan, USA) for 24 h at 37°C under aerobic conditions without shaking, and these cultures were subcultured twice before use in experiments. The cell concentration of individual strains was evaluated by measuring the optical density at 600 nm and converting this value to the corresponding CFU ml-1 value. Before eukaryotic cell challenge, bacterial strains were irradiated with 2800 Gy (Gray) γ-irradiation (MDS Nordion γ-cell 1000) to prevent their proliferation. Antimicrobial activity The antimicrobial activity was assessed by using the inhibition halo test. The pathogenic Bacillus cereus (DSM 4313 and DSM 4384), Escherichia coli (DSM 8579) and Pseudomonas aeruginosa species were

used as tester strains. The two strains of Lactobacillus gasseri were grown in MRS broth at 37°C to 1 × 106 CFU ml-1. Methane monooxygenase Cells were centrifuged at 5000 × g for 15 min at 4°C and collected supernatant was filtered through a 0.22 μm filter before use for the test. Different volumes of supernatants were spotted onto sterile filter disks with a diameter of 5 mm that were plated onto TY (Tryptone Yeast extract, Difco) agar plates previously inoculated with the pathogen tester strains. The TY agar plates were then incubated at 37°C for 24–48 hours. DMSO was used as negative control; gentamycin (8 μg/disc) and tetracycline (7 μg/disc) were used as click here positive controls. The test was performed in triplicate. IEC cell line MODE-K cells (H-2 k), a murine small intestinal epithelial cell line [24], were kindly provided by Dr. D Kaiserlian (INSERM, Paris, France). These cells were maintained as adherent cells at 37°C in a humidified atmosphere of 5% CO2 in air in RPMI medium (Sigma, St. Louis, MO) containing 25 mM HEPES, 1% nonessential amino acids, 0.055% sodium pyruvate, 10% FCS, and 4 mM L-glutamine (complete RPMI medium). Cells were detached before analysis using a solution of 0.25% trypsin in 0.