title: Neutralization of endotoxin in vitro and in vivo by Bac7(1-35), a proline-rich antibacterial peptide.
abstract: Lipopolysaccharides (LPS), or endotoxins, are structural components of gram-negative bacteria implicated in the pathogenesis of septic shock. In this study the antiendotoxin activity of Bac7(1-35), a synthetic peptide based on the sequence of a proline-rich antibacterial peptide from bovine neutrophils, was investigated in vitro and in an experimental rat model of gram-negative septic shock. The ability of Bac7(1-35) to bind LPS from Escherichia coli O111:B4 was determined using a sensitive Limulus chromogenic assay. In the in vivo study, adult male Wistar rats were given an intraperitoneal injection of 1 x 10(9) colony-forming units of E. coli ATCC 25922. All animals were randomized to receive intraperitoneally 1 mg/kg Bac7(1-35), or isotonic sodium chloride solution (control group C1), 60 mg/kg of piperacillin and 1 mg/kg polymyxin B, 1 mg/kg of polymyxin B plus 60 mg/kg of piperacillin, and 1 mg/kg of Bac7(1-35) plus 60 mg/kg of piperacillin. Each group included 15 animals. Bac7(1-35) was found to completely inhibit the LPS procoagulant activity at approximately 10 microM peptide concentration, as determined by in vitro LAL chromogenic assay. Treatment with Bac7(1-35) resulted in significant decrease in plasma endotoxin levels and lethality rates compared with saline injected control animals. No statistically significant differences were noted between Bac7(1-35) and polymyxin B in reducing all variables measured. These results provide evidence for the ability of Bac7(1-35) to effectively bind LPS and protect animals from lethal effects of this molecule, and point to its potential use for the treatment of endotoxin-induced septic shock.
authors.affiliation: Department of General Surgery, Istituto Nazionale Riposo e Cura Anziani, University of Ancona, Ancona, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Ghiselli
authors.forename: Andrea
authors.initials: A
authors.lastname: Giacometti
authors.forename: Oscar
authors.initials: O
authors.lastname: Cirioni
authors.forename: Raffaella
authors.initials: R
authors.lastname: Circo
authors.forename: Federico
authors.initials: F
authors.lastname: Mocchegiani
authors.forename: Barbara
authors.initials: B
authors.lastname: Skerlavaj
authors.forename: Giuseppina
authors.initials: G
authors.lastname: D'Amato
authors.forename: Giorgio
authors.initials: G
authors.lastname: Scalise
authors.forename: Margherita
authors.initials: M
authors.lastname: Zanetti
authors.forename: Vittorio
authors.initials: V
authors.lastname: Saba
mesh_terms: D000595:Amino Acid Sequence; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology*; D004731:Endotoxins / Q000037:antagonists & inhibitors*; D004926:Escherichia coli / Q000187:drug effects; D006090:Gram-Negative Bacteria / Q000187:drug effects; D007700:Kinetics; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010455:Peptides / Q000494:pharmacology*
chemical_list: D023181:Antimicrobial Cationic Peptides; C481640:Bac7(1-35) peptide; D004731:Endotoxins; D008070:Lipopolysaccharides; D010455:Peptides