I Nagaoka1, K Kuwahara-Arai, H Tamura, K Hiramatsu, M Hirata. 1. Department of Host Defense and Biochemical Research, School of Medicine, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan. nagaokai@med.juntendo.ac.jp
Abstract
OBJECTIVE: Mammalian myeloid and epithelial cells express various peptide antibiotics (such as defensins and cathelicidins) that contribute to the innate host defense against invading micro-organisms. Among these, human cathelicidin CAP18/LL-37 (L1-S37) possesses potent antibacterial activities against Gram-positive and Gram-negative bacteria. In this study, to develop peptide derivatives with improved bactericidal actions, we utilized the amphipathic 18-mer peptide (K15-V32) of LL-37 as a template, and evaluated the activities of modified peptides. METHODS: Antibacterial activities of the peptides (0.022 approximately 4.4 microM corresponding to 0.1 approximately 10 microg/ml) were assessed by alamarBlue assay using Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus pyogenes, Escherichia coli and Pseudomonas aeruginosa as target organisms. Furthermore, the membrane-permeabilization activities of the peptides were examined by using E. coli ML-35p as a target. RESULTS: By substituting E16 and K25 with two L residues, the hydrophobicity of the peptide (18-mer LL) was increased, and by further substituting Q22, D26 and N30 with three K residues, the cationicity of the peptide (18-mer LLKKK) was enhanced. Among peptide derivatives, 18-mer LLKKK exhibited the most potent antibacterial actions against S. aureus (methicillin-resistant and -sensitive), S. pneumoniae, S. pyogenes, E. coli and P. aeruginosa, and possessed the most powerful membrane-permeabilizing activities against E. coli ML-35p at the effective concentrations (p <0.05, 18-mer LLKKK vs. 18-mer LL, 18-mer K15-V32 and LL-37). CONCLUSIONS: Bactericidal activities of the amphipathic human CAP18/LL-37-derived 18-mer peptide can be augmented by modifying its hydrophobicity and cationicity, and 18-mer LLKKK is the most potent among peptide derivatives with therapeutic potential for Gram-positive and Gram-negative bacterial infections.
OBJECTIVE:Mammalian myeloid and epithelial cells express various peptide antibiotics (such as defensins and cathelicidins) that contribute to the innate host defense against invading micro-organisms. Among these, human cathelicidin CAP18/LL-37 (L1-S37) possesses potent antibacterial activities against Gram-positive and Gram-negative bacteria. In this study, to develop peptide derivatives with improved bactericidal actions, we utilized the amphipathic 18-mer peptide (K15-V32) of LL-37 as a template, and evaluated the activities of modified peptides. METHODS: Antibacterial activities of the peptides (0.022 approximately 4.4 microM corresponding to 0.1 approximately 10 microg/ml) were assessed by alamarBlue assay using Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus pyogenes, Escherichia coli and Pseudomonas aeruginosa as target organisms. Furthermore, the membrane-permeabilization activities of the peptides were examined by using E. coli ML-35p as a target. RESULTS: By substituting E16 and K25 with two L residues, the hydrophobicity of the peptide (18-mer LL) was increased, and by further substituting Q22, D26 and N30 with three K residues, the cationicity of the peptide (18-mer LLKKK) was enhanced. Among peptide derivatives, 18-mer LLKKK exhibited the most potent antibacterial actions against S. aureus (methicillin-resistant and -sensitive), S. pneumoniae, S. pyogenes, E. coli and P. aeruginosa, and possessed the most powerful membrane-permeabilizing activities against E. coli ML-35p at the effective concentrations (p <0.05, 18-mer LLKKK vs. 18-mer LL, 18-mer K15-V32 and LL-37). CONCLUSIONS: Bactericidal activities of the amphipathic humanCAP18/LL-37-derived 18-mer peptide can be augmented by modifying its hydrophobicity and cationicity, and 18-mer LLKKK is the most potent among peptide derivatives with therapeutic potential for Gram-positive and Gram-negative bacterial infections.
Authors: Barney M Bishop; Melanie L Juba; Megan C Devine; Stephanie M Barksdale; Carlos Alberto Rodriguez; Myung C Chung; Paul S Russo; Kent A Vliet; Joel M Schnur; Monique L van Hoek Journal: PLoS One Date: 2015-02-11 Impact factor: 3.240