title: Anti-inflammatory and anti-endotoxin properties of peptides derived from the carboxy-terminal region of a defensin from the tick Ornithodoros savignyi.
abstract: Antimicrobial peptides are small cationic peptides that possess a large spectrum of bioactivities, including antimicrobial, anti-inflammatory and antioxidant activities. Several antimicrobial peptides are known to inhibit lipopolysaccharide (LPS)-induced inflammation in vitro and to protect animals from sepsis. In this study, the cellular anti-inflammatory and anti-endotoxin activities of Os and Os-C, peptides derived from the carboxy-terminal of a tick defensin, were investigated. Both Os and Os-C were found to bind LPS in vitro, albeit to a lesser extent than polymyxin B and melittin, known endotoxin-binding peptides. Binding to LPS was found to reduce the bactericidal activity of Os and Os-C against Escherichia coli confirming the affinity of both peptides for LPS. At a concentration of 25 µM, the nitric oxide (NO) scavenging activity of Os was higher than glutathione, a known NO scavenger. In contrast, Os-C showed no scavenging activity. Os and Os-C inhibited LPS/IFN-γ induced NO and TNF-α production in RAW 264.7 cells in a concentration-dependent manner, with no cellular toxicity even at a concentration of 100 µM. Although inhibition of NO and TNF-α secretion was more pronounced for melittin and polymyxin B, significant cytotoxicity was observed at concentrations of 1.56 µM and 25 µM for melittin and polymyxin B, respectively. In addition, Os, Os-C and glutathione protected RAW 264.7 cells from oxidative damage at concentrations as low as 25 µM. This study identified that besides previously reported antibacterial activity of Os and Os-C, both peptides have in addition anti-inflammatory and anti-endotoxin properties.
authors.affiliation: Department of Biochemistry, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, 0002, South Africa.
authors.forename: Melissa
authors.initials: M
authors.lastname: Malan
authors.affiliation: Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Pretoria, 0002, South Africa.
authors.forename: June C
authors.initials: JC
authors.lastname: Serem
authors.affiliation: Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Pretoria, 0002, South Africa.
authors.forename: Megan J
authors.initials: MJ
authors.lastname: Bester
authors.affiliation: Department of Biochemistry, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, 0002, South Africa.
authors.forename: Albert W H
authors.initials: AW
authors.lastname: Neitz
authors.affiliation: Department of Biochemistry, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, 0002, South Africa.
authors.forename: Anabella R M
authors.initials: AR
authors.lastname: Gaspar
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000138:chemical synthesis / Q000494:pharmacology*; D000893:Anti-Inflammatory Agents / Q000138:chemical synthesis / Q000494:pharmacology*; D002460:Cell Line; D023082:Defensins / Q000737:chemistry* / Q000302:isolation & purification; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development; D016166:Free Radical Scavengers / Q000138:chemical synthesis / Q000494:pharmacology*; D005978:Glutathione / Q000737:chemistry; D007371:Interferon-gamma / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology / Q000187:drug effects; D008555:Melitten / Q000737:chemistry; D051379:Mice; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D026861:Ornithodoros / Q000737:chemistry*; D010455:Peptides / Q000138:chemical synthesis / Q000494:pharmacology*; D011112:Polymyxin B / Q000737:chemistry; D017434:Protein Structure, Tertiary; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000096:biosynthesis
chemical_list: D000900:Anti-Bacterial Agents; D000893:Anti-Inflammatory Agents; D023082:Defensins; D016166:Free Radical Scavengers; D008070:Lipopolysaccharides; D010455:Peptides; D014409:Tumor Necrosis Factor-alpha; D008555:Melitten; D009569:Nitric Oxide; D007371:Interferon-gamma; D005978:Glutathione; D011112:Polymyxin B
keywords: LPS; NO scavenging; anti-endotoxin; anti-inflammatory; antioxidant; defensin; sepsis; tick