title: Differential effects of alpha-helical and beta-hairpin antimicrobial peptides against Acanthamoeba castellanii.
abstract: In this work we evaluated the ability of different types of antimicrobial peptides to promote permeabilization and growth inhibition of Acanthamoeba castellanii trophozoites, which cause eye keratitis. We used cationic alpha-helical peptides P5 and P6, corresponding to the N-terminus of the pore-forming protein from Triatoma infestans, a blood-sucking insect, and a beta-hairpin amphipathic molecule (gomesin), of the spider Acanthoscurria gomesiana haemocytes. A. castellanii permeabilization was obtained after 1 h incubation with micromolar concentrations of both types of peptides. While permeabilization induced by gomesin increased with longer incubations, P5 permeabilization did not increase with time and occurred at doses that are more toxic for SIRC cells. P5, however, at doses below the critical dose used to kill rabbit corneal cells was quite effective in promoting growth inhibition. Similarly, P5 was more effective when serine protease inhibitor was added simultaneously to the permeabilization assay. High performance chromatography followed by mass spectrometry analysis confirmed that, in contrast to gomesin, P5 is hydrolysed by A. castellanii culture supernatants. We conclude that the use of antimicrobial peptides to treat A. castellanii infections requires the search of more specific peptides that are resistant to proteolysis.
authors.affiliation: Departamento de Oftalmologia, Universidade Federal de São Paulo, SP, Brazil.
authors.forename: R S
authors.initials: RS
authors.lastname: Sacramento
authors.forename: R M
authors.initials: RM
authors.lastname: Martins
authors.forename: A
authors.initials: A
authors.lastname: Miranda
authors.forename: A S S
authors.initials: AS
authors.lastname: Dobroff
authors.forename: S
authors.initials: S
authors.lastname: Daffre
authors.forename: A S
authors.initials: AS
authors.lastname: Foronda
authors.forename: D
authors.initials: D
authors.lastname: De Freitas
authors.forename: S
authors.initials: S
authors.lastname: Schenkman
mesh_terms: D015823:Acanthamoeba Keratitis / Q000188:drug therapy; D048248:Acanthamoeba castellanii / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000138:chemical synthesis / Q000494:pharmacology*; D001097:Arachnida / Q000737:chemistry; D002460:Cell Line; D002463:Cell Membrane Permeability / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006434:Hemocytes / Q000737:chemistry; D017433:Protein Structure, Secondary; D011817:Rabbits; D012471:Salivary Proteins and Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D014224:Triatoma / Q000737:chemistry; D053058:Trophozoites / Q000187:drug effects / Q000378:metabolism
chemical_list: D023181:Antimicrobial Cationic Peptides; D012471:Salivary Proteins and Peptides; D015842:Serine Proteinase Inhibitors; C415987:gomesin; C509988:trialysin protein, Triatoma infestans