Proteins were separated by SDS-PAGE and transferred to a PVDF membrane (Immobilon™-P, Millipore) by electroblotting. The blot was then conjugated with appropriate primary antibodies (anti-FliC rabbit Ab or anti-cSipC mouse Ab) and Alexa Fluor™ 488 goat anti-rabbit (or anti-mouse) IgG (Molecular Probes) and analyzed using a Molecular Imager FX (Bio-Rad). For FACS analysis, intact bacterial cells were stained with a rabbit anti-FliC (or anti-cSipC) antibody and Alexa Fluor™ 488 goat anti-rabbit (or anti-mouse) IgG in PBS supplemented with 1% BSA and 0.05% Tween-20. The labeled bacterial cells were then analyzed using a FACSCalibur flow cytometer and CELLQuest software (BD). Bacterial cells for stimulation
were prepared as follows. Prewarmed LCM supplemented with erythromycin learn more was inoculated with a 5% volume of overnight culture of the respective bacterial strains and incubated for 5 h. The bacterial
cells were collected and washed twice with PBS and once with distilled water. The bacterial suspensions in distilled water were then lyophilized. Caco-2 cells, established from epithelial cells of human colon adenocarcinoma, were purchased from American Type Culture Collection (ATCC) and maintained in a complete medium of Dulbecco’s modified Eagle’s medium (DMEM) supplemented with 0.1% (v/v) non-essential amino acid, 10% fetal bovine serum (FBS), 100 U/ml penicillin, and 100 mg/ml streptomycin. Every culture of Caco-2 cells was incubated at 37 °C in 5% CO2. Semi-confluent cultures of Caco-2 cells were collected and suspended in complete medium and seeded into a 96-well flat-bottom Oxymatrine microplate (1 × 104 cells/0.2 ml/well). After 24 h incubation, the medium was replaced selleck with fresh medium including bacteria or purified proteins. The culture supernatant was collected after 4 h and stored at −20 °C until analysis. Female 8-week-old C3H/HeJ mice (Japan SLC) were immunized i.p. with recombinant lactobacilli, purified cSipC, and/or flagellin (5 mice/group). On the days of immunization, prewarmed LCM supplemented with erythromycin was inoculated with a 5% volume
of overnight culture of the respective bacterial strains and incubated for 5 h. The bacterial cells were then collected and washed with PBS. The bacterial cell suspensions for administration were adjusted to 1 × 107 cfu in 0.1 ml PBS per dose. The mice received three injections with 2-week intervals between each dose. Two weeks after the last booster, blood and the spleen were collected. Sera were prepared from the blood samples by centrifugation and stored at −20 °C until use. The care and use of experimental animals complied with local Animal Welfare Laws and Guidelines. Human interleukin 8 (IL-8) released into the culture supernatants was detected using IL-8 OptEIA ELISA sets (BD Biosciences, San Diego, CA, USA). Appropriately diluted culture supernatants were assayed in accordance with the manufacturer’s instructions. Concentrations of the cytokines were calculated using a standard curve.