title: Probiotics prevent enterohaemorrhagic Escherichia coli O157:H7-mediated inhibition of interferon-gamma-induced tyrosine phosphorylation of STAT-1.
abstract: Enterohaemorrhagic Escherichia coli (EHEC) O157:H7 inhibits interferon (IFN)-gamma-stimulated tyrosine phosphorylation of signal transducer and activator of transcription (STAT)-1 in epithelial cells. We determined the effects of probiotics on EHEC-mediated disruption of IFN-gamma-stimulated STAT-1 activation in epithelial cell lines. Confluent Intestine 407, HEp-2 and Caco-2 epithelial cells were pre-treated (3 h) with either probiotics or surface-layer proteins derived from Lactobacillus helveticus R0052 prior to infection with EHEC O157:H7 strain CL56 (m.o.i. 100:1, 6 h, 37 degrees C in 5% CO2). Subsequently, cells were washed and stimulated with human recombinant IFN-gamma (50 ng ml(-1), 0.5 h, 37 degrees C) followed by whole-cell protein extraction and immunoblotting for tyrosine-phosphorylated STAT-1. Relative to uninfected cells, STAT-1-activation was reduced after EHEC O157:H7 infection. Pre-incubation with the probiotic L. helveticus R0052 followed by EHEC infection abrogated pathogen-mediated disruption of IFN-gamma-STAT-1 signalling. As determined using Transwell inserts, probiotic-mediated protection was independent of epithelial cell contact. In contrast, pre-incubation with boiled L. helveticus R0052, an equal concentration of viable Lactobacillus rhamnosus R0011, or surface-layer proteins (0.14 mg ml(-1)) did not restore STAT-1 signalling in EHEC-infected cells. The viable probiotic agent L. helveticus R0052 prevented EHEC O157:H7-mediated subversion of epithelial cell signal transduction responses.
authors.affiliation: Research Institute, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
authors.forename: Narveen
authors.initials: N
authors.lastname: Jandu
authors.affiliation: Research Institute, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
authors.forename: Zoë Jingjing
authors.initials: ZJ
authors.lastname: Zeng
authors.affiliation: Research Institute, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
authors.forename: Kathene C
authors.initials: KC
authors.lastname: Johnson-Henry
authors.affiliation: Research Institute, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
authors.forename: Philip M
authors.initials: PM
authors.lastname: Sherman
mesh_terms: D001426:Bacterial Proteins / Q000494:pharmacology; D002460:Cell Line; D015536:Down-Regulation; D004847:Epithelial Cells / Q000378:metabolism / Q000382:microbiology; D004927:Escherichia coli Infections / Q000378:metabolism* / Q000382:microbiology / Q000517:prevention & control; D019453:Escherichia coli O157 / Q000502:physiology*; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism*; D052198:Lactobacillus helveticus / Q000737:chemistry / Q000502:physiology; D010766:Phosphorylation / Q000187:drug effects; D019936:Probiotics / Q000737:chemistry* / Q000494:pharmacology; D050794:STAT1 Transcription Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D014443:Tyrosine / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D050794:STAT1 Transcription Factor; D014443:Tyrosine; D007371:Interferon-gamma