ABSTRACT
Here, we present a rational approach that enhances the membrane selectivity of a prolific pore-forming peptide, melittin, based on experimental observations that the cationic polymer, ε-polylysine, disrupts bacterial membranes with greater affinity over mammalian cells when compared to poly-l-lysine and poly-d-lysine. We systematically replaced three α-lysine residues in melittin with ε-lysine residues and identified key residues that are important for cytotoxicity. We then assessed the antimicrobial properties of the modified peptides which carry two or three ε-lysyl residues. Two modified melittin peptides displayed rapid bactericidal properties against antibiotic-resistant strains, low innate resistance development by pathogenic bacteria, remained nonimmunogenic for T lymphocytes, and increased bioavailability in tear fluids. In proof-of-concept in vivo experiments, one of the peptides was noncytotoxic for ocular surfaces and had comparable antimicrobial efficacy to that of fluoroquinolone antibiotics. The results uncover a simple and potential strategy that can enhance the membrane selectivity of cytolytic peptides by ε-lysylation.
Subject(s)
Anti-Bacterial Agents/pharmacology , Cell Membrane/drug effects , Lysine/chemistry , Melitten/pharmacology , Amino Acid Sequence , Amino Acid Substitution , Animals , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/therapeutic use , Antifungal Agents/chemistry , Antifungal Agents/pharmacology , Antifungal Agents/therapeutic use , Bacteria/drug effects , Bees/chemistry , Candida albicans/drug effects , Cornea/microbiology , Cornea/pathology , Eye Infections, Bacterial/drug therapy , Eye Infections, Bacterial/pathology , Female , Humans , Keratitis/drug therapy , Keratitis/pathology , Melitten/chemistry , Melitten/therapeutic use , Mice, Inbred C57BL , Microbial Sensitivity Tests , Proof of Concept Study , Rabbits , Unilamellar Liposomes/metabolismABSTRACT
Contact lens is a major risk factor for microbial keratitis among contact lens wearers. Chemical strategies that can prevent microbial adhesion and biofilm formation are required to improve a wearer's hygiene and safety. Taking advantage of the material-independent properties of a polydopamine (pDA) coating, we investigated the role of covalent/noncovalent interactions of the antimicrobials and pDA in conferring long-term antimicrobial activities. The developed antimicrobial contact lenses not only retain their antibacterial efficiency against different bacterial strains for 2 weeks but also inhibit microbial adhesion and biofilm formation on the lens surfaces. The designed antimicrobial coatings were found to be safe for ocular cell lines. Moreover, the antimicrobial coatings did not affect the functional and surface properties of coated contact lenses. This methodology can be used to protect the contact lenses from microbial contamination for prolonged periods and has the potential to be extended for designing antimicrobial coatings for other medical devices as well.
