title: Effect of lactoferrin on release and bioactivity of Shiga toxins from different Escherichia coli O157:H7 strains.
abstract: Prevention of enterohemorrhagic Escherichia coli (EHEC) O157:H7 infections and of their severe clinical sequelae in humans remain to be a current challenge. Administration of bovine lactoferrin (bLF) proved to be effective in clearing EHEC from the bovine intestine, an important EHEC reservoir, suggesting that bLF may also be beneficial in human application against EHEC infections. To estimate the biological safety of this approach, we analyzed the effects of bLF on the main EHEC virulence factor, Shiga toxin (Stx). We quantified the release of Stx 1 and 2 from two O157:H7 EHEC strains (Stx1+Stx2+and Stx2+producing, respectively) cultured in the presence of bLF using ELISA assays and assessed cytotoxic effects of bLF and co-cultured EHEC on Vero cells. Effects of bLF on the stability of Stx2 were investigated using western blotting. ELISA results indicate a bLF concentration-dependent decrease of active, cell-free Stx2, but not Stx1 in EHEC cultures. High concentrations (100 and 50mg/ml) of bLF resulted in significantly reduced (p<0.05) metabolic activity rates of Vero cells, whereas a concentration of 10mg/ml bLF was considered non-toxic for Vero cells. At concentrations of 1 or 0.1mg/ml, bLF mitigated the verocytotoxicity of EHEC strains in a co-culture model up to 48h after inoculation. When only colonizing bacteria were taken into account, cytotoxicity could be significantly reduced by 10 and 1mg/ml bLF during 48h. This effect of bLF at least partly results from degradation of the Stx2 receptor-binding B-subunit.
authors.affiliation: Laboratory of Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium. Electronic address: evelien.kieckens@ugent.be.
authors.forename: E
authors.initials: E
authors.lastname: Kieckens
authors.affiliation: Department of Animal Production, Faculty of Bioscience Engineering, Ghent University, Coupure Links 654, 9000 Gent, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Rybarczyk
authors.affiliation: Friedrich-Loeffler-Institut, Institute of Molecular Pathogenesis, Naumburger Str. 96a, 07743 Jena, Germany.
authors.forename: S A
authors.initials: SA
authors.lastname: Barth
authors.affiliation: Friedrich-Loeffler-Institut, Institute of Molecular Pathogenesis, Naumburger Str. 96a, 07743 Jena, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Menge
authors.affiliation: Laboratory of Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
authors.forename: E
authors.initials: E
authors.lastname: Cox
authors.affiliation: Department of Animal Production, Faculty of Bioscience Engineering, Ghent University, Coupure Links 654, 9000 Gent, Belgium.
authors.forename: D
authors.initials: D
authors.lastname: Vanrompay
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D002522:Chlorocebus aethiops; D019453:Escherichia coli O157 / Q000187:drug effects* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D007781:Lactoferrin / Q000494:pharmacology*; D022621:Shiga Toxin / Q000235:genetics / Q000378:metabolism*; D022622:Shiga Toxin 1 / Q000235:genetics / Q000378:metabolism*; D014709:Vero Cells
chemical_list: D022622:Shiga Toxin 1; D022621:Shiga Toxin; D007781:Lactoferrin
keywords: Bovine lactoferrin; Cytotoxic effect; EHEC; Shiga toxins