title: Alternative stabilities of a proline-rich antibacterial peptide in vitro and in vivo.
abstract: The proline-rich designer antibacterial peptide dimer A3-APO is currently under preclinical development for the treatment of systemic infections caused by antibiotic-resistant Gram-negative bacteria. The peptide showed remarkable stability in 25% mouse serum in vitro, exhibiting a half-life of approximately 100 min as documented by reversed-phase chromatography. Indeed, after a 30-min incubation period in undiluted mouse serum ex vivo, mass spectrometry failed to identify any degradation product. The peptide was still a major peak in full blood ex vivo, however, with degradation products present corresponding to amino-terminal cleavage. When injected into mice intravenously, very little, if any unmodified peptide could be detected after 30 min. Nevertheless, the major early metabolite, a full single-chain fragment, was detectable until 90 min, and this fragment exhibited equal or slightly better activity in the broth microdilution antimicrobial assay against a panel of resistant Enterobactericeae strains. The Chex1-Arg20 metabolite, when administered three times at 20 mg/kg to mice infected with a sublethal dose (over LD(50)) of an extended spectrum beta-lactamase-producing Escherichia coli strain, completely sterilized the mouse blood, similar to imipenem added at a higher dose. The longer and presumably more immunogenic prodrug A3-APO, injected subcutaneously twice over a 3-wk period, did not induce any antibody production, indicating the suitability of this peptide or its active metabolite for clinical development.
authors.affiliation: Sbarro Institute for Cancer Research and Molecular Medicine, Temple University, Philadelphia, Pennsylvania 19122, USA.
authors.forename: Paul Bart
authors.initials: PB
authors.lastname: Noto
authors.forename: Giovanni
authors.initials: G
authors.lastname: Abbadessa
authors.forename: Marco
authors.initials: M
authors.lastname: Cassone
authors.forename: George D
authors.initials: GD
authors.lastname: Mateo
authors.forename: Alexis
authors.initials: A
authors.lastname: Agelan
authors.forename: John D
authors.initials: JD
authors.lastname: Wade
authors.forename: Dora
authors.initials: D
authors.lastname: Szabo
authors.forename: Bela
authors.initials: B
authors.lastname: Kocsis
authors.forename: Karoly
authors.initials: K
authors.lastname: Nagy
authors.forename: Ferenc
authors.initials: F
authors.lastname: Rozgonyi
authors.forename: Laszlo
authors.initials: L
authors.lastname: Otvos
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000097:blood / Q000737:chemistry* / Q000493:pharmacokinetics / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D005260:Female; D066298:In Vitro Techniques; D013058:Mass Spectrometry; D051379:Mice; D008826:Microbial Sensitivity Tests; D010455:Peptides / Q000097:blood / Q000737:chemistry* / Q000493:pharmacokinetics / Q000494:pharmacology; D011392:Proline / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D010455:Peptides; D011392:Proline