title: A synthetic cyclic peptide derived from Limulus anti-lipopolysaccharide factor neutralizes endotoxin in vitro and in vivo.
abstract: Endotoxin, also known as lipopolysaccharide (LPS), is the major mediator of septic shock due to Gram-negative bacterial infections. Recently, much attention has been focused on cationic peptides which possess the potential to detoxify LPS. Limulus anti-LPS factor (LALF), a protein found in the horseshoe crab (Limulus polyphemus), has been proved with striking anti-LPS effects. We synthesized a cyclic peptide (CLP-19), and then investigated its bioactivity both in vitro and in vivo. The ability of CLP-19 to neutralize LPS in vitro was tested using a Limulus amebocyte lysate (LAL) assay and the LPS-binding affinity was measured with an affinity biosensor method. The synthetic peptide LALF31-52 (residues 31 to 52 of LALF) was used as the positive control peptide in this study. It was found that CLP-19 exhibited the significant activity to antagonize LPS without observable cytotoxicity effect on mouse macrophages. CLP-19 directly bound to LPS, and neutralized it in a dose-dependent manner in the LAL assay. Moreover, CLP-19 also showed the remarkable ability to protect mice from lethal LPS attack and to inhibit the LPS-induced tumor necrosis factor alpha (TNF-alpha) release by decreasing serum LPS in vivo. Our work suggests that this peptide is worthy of further investigation as a potential anti-LPS agent in the treatment of septic shock.
authors.affiliation: Department of Pharmacy, Southwest Hospital, Third Military Medical University, Chongqing 400038, China.
authors.forename: Jian-Dong
authors.initials: JD
authors.lastname: Ren
authors.forename: Jin-Song
authors.initials: JS
authors.lastname: Gu
authors.forename: Hong-Fu
authors.initials: HF
authors.lastname: Gao
authors.forename: Pei-Yuan
authors.initials: PY
authors.lastname: Xia
authors.forename: Guang-Xia
authors.initials: GX
authors.lastname: Xiao
mesh_terms: D000818:Animals; D023181:Antimicrobial Cationic Peptides; D060829:Arthropod Proteins; D002460:Cell Line; D004195:Disease Models, Animal; D019446:Endotoxemia / Q000517:prevention & control*; D006737:Horseshoe Crabs / Q000378:metabolism; D007447:Invertebrate Hormones / Q000737:chemistry*; D008033:Limulus Test; D008070:Lipopolysaccharides / Q000378:metabolism*; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008815:Mice, Inbred Strains; D010456:Peptides, Cyclic / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000097:blood / Q000378:metabolism*
chemical_list: D023181:Antimicrobial Cationic Peptides; D060829:Arthropod Proteins; D007447:Invertebrate Hormones; D008070:Lipopolysaccharides; D010456:Peptides, Cyclic; D014409:Tumor Necrosis Factor-alpha; C034705:antilipopolysaccharide factor (Limulus)