title: Synthesis, characterization, antimicrobial activity and LPS-interaction properties of SB041, a novel dendrimeric peptide with antimicrobial properties.
abstract: Multimeric peptides offer several advantages with respect to their monomeric counterparts, as increased activity and greater stability to peptidases and proteases. SB041 is a novel antimicrobial peptide with dendrimeric structure; it is a tetramer of pyrEKKIRVRLSA linked by a lysine core, with an amino valeric acid chain. Here, we report on its synthesis, NMR characterization, antimicrobial activity, and LPS-interaction properties. The peptide was especially active against Gram-negative strains, with a potency comparable (on molar basis) to that of lipopeptides colistin and polymixin B, but it also displayed some activity against selected Gram-positive strains. Following these indications, we investigated the efficacy of SB041 in binding Escherichia coli and Pseudomonas aeruginosa LPS in vitro and counteracting its biological effects in RAW-Blue cells, derived from RAW 264.7 macrophages. SB041 strongly bound purified LPS, especially that of E. coli, as proved by fluorescent displacement assay, and readily penetrated into LPS monolayers. However, the killing activity of SB041 against E. coli was not inhibited by increasing concentrations of LPS added to the medium. Checking the SB041 effect on LPS-induced activation of pattern recognition receptors (PRRs) in Raw-Blue cells revealed that while the peptide gave a statistically significant decrease in PRRs stimulation when RAW-Blue cells were challenged with P. aeruginosa LPS, the same was not seen when E. coli LPS was used to activate innate immune defense-like responses. Thus, as previously seen for other antimicrobial peptides, also for SB041 binding to LPS did not translate necessarily into LPS-neutralizing activity, suggesting that SB041-LPS interactions must be of complex nature.
authors.affiliation: Research & Development Unit, Spider Biotech S.r.l., I-10010 Colleretto Giacosa (TO), Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Bruschi
authors.forename: Giovanna
authors.initials: G
authors.lastname: Pirri
authors.forename: Andrea
authors.initials: A
authors.lastname: Giuliani
authors.forename: Silvia Fabiole
authors.initials: SF
authors.lastname: Nicoletto
authors.forename: Izabela
authors.initials: I
authors.lastname: Baster
authors.forename: Mariano Andrea
authors.initials: MA
authors.lastname: Scorciapino
authors.forename: Mariano
authors.initials: M
authors.lastname: Casu
authors.forename: Andrea C
authors.initials: AC
authors.lastname: Rinaldi
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D002175:Candida / Q000187:drug effects; D002460:Cell Line; D050091:Dendrimers / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004306:Dose-Response Relationship, Immunologic; D015195:Drug Design; D004926:Escherichia coli / Q000378:metabolism; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D007113:Immunity, Innate; D007700:Kinetics; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism*; D008264:Macrophages / Q000187:drug effects / Q000276:immunology; D051379:Mice; D018716:Molecular Mimicry; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000276:immunology* / Q000494:pharmacology; D011487:Protein Conformation; D011550:Pseudomonas aeruginosa / Q000378:metabolism; D051192:Receptors, Pattern Recognition / Q000378:metabolism
chemical_list: D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D050091:Dendrimers; D008070:Lipopolysaccharides; D010455:Peptides; D051192:Receptors, Pattern Recognition; C553588:SB 041