Cell selectivity, mechanism of action and LPS-neutralizing activity of bovine myeloid antimicrobial peptide-18 (BMAP-18) and its analogs

• Published in: Peptides (New York, N.Y. : 1980) Vol. 32; no. 6; pp. 1123 - 1130
• Main Authors: Lee, Eun Kyu, Kim, Yoon-Chang, Nan, Yong Hai, Shin, Song Yub
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.06.2011; Elsevier
• Subjects: Amino Acid Sequence; Analogs; Animals; Anti-Infective Agents - chemical synthesis; Anti-Infective Agents - metabolism; Anti-Infective Agents - pharmacology; anti-infective properties; Antimicrobial Cationic Peptides - chemical synthesis; Antimicrobial Cationic Peptides - metabolism; Antimicrobial Cationic Peptides - pharmacology; antimicrobial peptides; antimicrobials; Bacteria; Biological and medical sciences; Bovine myeloid antimicrobial peptide-18 (BMAP-18); Bovine myeloid antimicrobial peptide-27 (BMAP-27); Cattle; Cell selectivity; Channels; Charge; Fundamental and applied biological sciences. Psychology; Gram-Negative Bacteria - drug effects; Gram-Positive Bacteria - drug effects; hemolysis; Hemolysis - drug effects; Humans; Hydrophobic and Hydrophilic Interactions; Hydrophobicity; ions; Killing mechanism; Lipopolysaccharides - antagonists & inhibitors; Lipopolysaccharides - pharmacology; LPS-neutralizing activity; macrophages; Macrophages - drug effects; mechanism of action; Mice; Microorganisms; Molecular Sequence Data; necrosis; nitric oxide; Nitric Oxide - biosynthesis; Peptide Fragments - chemical synthesis; Peptide Fragments - metabolism; Peptide Fragments - pharmacology; Peptides; Proteins - chemistry; Proteins - metabolism; Proteins - pharmacology; protons; Selectivity; Species Specificity; Staphylococcus aureus; Static Electricity; Structure-Activity Relationship; tumor necrosis factor-alpha; Tumor Necrosis Factor-alpha - analysis; Tumor Necrosis Factor-alpha - biosynthesis; Vertebrates: endocrinology; Cell selectivity; Killing mechanism; Bovine myeloid antimicrobial peptide-27 (BMAP-27); LPS-neutralizing activity; Bovine myeloid antimicrobial peptide-18 (BMAP-18); Bovine; Peptides; Ox; Selectivity; Antimicrobial agent; Vertebrata; Mammalia; Analog; Animal; Lipopolysaccharide; Artiodactyla; Antibacterial agent; Mechanism of action; Ungulata
• ISSN: 0196-9781; 1873-5169
• DOI: 10.1016/j.peptides.2011.03.024

► BMAP-18 and its analogs displayed much higher cell selectivity (about 4–97-fold increased) as compared to BMAP-27. ► BMAP-18 and its analogs exhibit lethality toward microbes due to their ability to form small channels, but not by the membrane-disruption/perturbation mode. ► There was a significant linear correlation between the increase in the hydrophobicity of peptides and LPS-neutralizing activity. ► Other important parameters of antimicrobial peptides may be involved in their LPS-neutralizing activity, as well as positive charge and hydrophobicity. To develop novel antimicrobial peptides (AMPs) with improved cell selectivity and potent LPS-neutralizing activity, we synthesized an 18 N-terminal residues peptide (BAMP-18) of bovine myeloid antimicrobial peptide-27 (BMAP-27) and its analogs (BMAP-18-W, BMAP-18-L, BMAP-18-I and BMAP-18-f). BMAP-18 and its analogs displayed much higher cell selectivity (about 4–97-fold increased) as compared to parental BMAP-27 because of their decreased hemolytic activity and retained antimicrobial activity. BMAP-27 caused near-complete dye leakage from bacterial-membrane-mimicking vesicles even at very low concentration of 0.5 μM, whereas BMAP-18 and its analogs induced very little dye leakage (less than 40%) even at 16 μM. These peptides induced near-complete membrane depolarization of Staphylococcus aureus cells under their MIC (4 μM). These results suggests that BMAP-18 and its analogs exhibit lethality toward microbes due to their ability to form small channels that permit the transit of ions or protons, but not molecules as large as calcein, and not by the membrane-disruption/perturbation mode. BMAP-18 and its analogs significantly inhibited nitric oxide (NO) production or tumor necrosis factor-α (TNF-α) release in LPS-stimulated mouse macrophage RAW264.7 cells at 10 μM. In particular, BMAP-18-W showed LPS-neutralizing activity comparable to that of BMAP-27. There was a significant linear correlation between the increase in the hydrophobicity of peptides and LPS-neutralizing activity. Although BMAP-18-W has lower hydrophobicity than BMAP-18-L, it showed higher LPS-neutralizing activity as compared to BMAP-18-L. This result suggests other important parameters of AMPs may be involved in their LPS-neutralizing activity, as well as positive charge and hydrophobicity.