Analysis of the cytotoxicity of synthetic antimicrobial peptides on mouse leucocytes: implications for systemic use.
We have analysed the toxicity of highly cationic, artificial alpha-helical antimicrobial peptides on blood cells to assess their suitability for systemic application. Flow cytometric methods, based on the uptake of propidium iodide, were used to obtain a rapid and quantitative estimate of membrane damage to resting and concanavalin A-activated mouse lymphocytes, which was further confirmed by morphological changes as observed by scanning electron microscopy. Membrane permeabilization appeared to correlate with structural characteristics, so that the peptide L-19(9/B), which contains helix-stabilizing aminoisobutyric acid (Aib) residues and is a potent antimicrobial, was also the most lytic towards both mouse lymphocytes and human erythrocytes. Reducing the propensity for helix formation in P19(8) resulted in a marked reduction in in vitro cytotoxicity. Changing the helical sense in D-P19(9/B) also resulted in a significant decrease in cytolytic activity towards both erythrocytes and leucocytes. A limited assessment in BALB/c mice confirmed a lower in vivo toxicity of P19(8) than L-P19(9/B). In a study of the systemic antimycotic activity of P19(8) in a mouse protection model, a modest prolongation in survival of Candida albicans-infected animals after intravenous administration was observed at 5 mg/kg peptide but not at higher doses. The implications of these observations for the systemic use of this type of peptide are discussed.
Department of Biomedical Sciences, University of Trieste, Trieste I-34127, Italy. pacorsab@units.it
Sabrina
S
Pacor
Anna
A
Giangaspero
Marina
M
Bacac
Gianni
G
Sava
Alessandro
A
Tossi
D000818:Animals; D000911:Antibodies, Monoclonal; D000935:Antifungal Agents / Q000737:chemistry / Q000633:toxicity*; D018941:Antigens, CD19 / Q000276:immunology; D023181:Antimicrobial Cationic Peptides / Q000633:toxicity*; D017252:CD3 Complex / Q000276:immunology; D002176:Candida albicans / Q000187:drug effects*; D002177:Candidiasis / Q000382:microbiology; D002463:Cell Membrane Permeability / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003601:Cytotoxicity Tests, Immunologic; D004195:Disease Models, Animal; D005260:Female; D005434:Flow Cytometry; D007275:Injections, Intravenous; D008214:Lymphocytes / Q000187:drug effects* / Q000276:immunology / Q000648:ultrastructure; D051379:Mice; D008807:Mice, Inbred BALB C; D008855:Microscopy, Electron, Scanning; D011419:Propidium / Q000493:pharmacokinetics; D013154:Spleen / Q000166:cytology; D023382:Toxicity Tests, Acute
D000911:Antibodies, Monoclonal; D000935:Antifungal Agents; D018941:Antigens, CD19; D023181:Antimicrobial Cationic Peptides; D017252:CD3 Complex; C473107:P19(8) antimicrobial peptide; C473108:P19(9-B) antimicrobial peptide; D011419:Propidium