Interaction of antimicrobial peptide temporin L with lipopolysaccharide in vitro and in experimental rat models of septic shock caused by gram-negative bacteria.
Sepsis remains a major cause of morbidity and mortality in hospitalized patients, despite intense efforts to improve survival. The primary lead for septic shock results from activation of host effector cells by endotoxin, the lipopolysaccharide (LPS) associated with cell membranes of gram-negative bacteria. For these reasons, the quest for compounds with antiendotoxin properties is actively pursued. We investigated the efficacy of the amphibian skin antimicrobial peptide temporin L in binding Escherichia coli LPS in vitro and counteracting its effects in vivo. Temporin L strongly bound to purified E. coli LPS and lipid A in vitro, as proven by fluorescent displacement assay, and readily penetrated into E. coli LPS monolayers. Furthermore, the killing activity of temporin L against E. coli was progressively inhibited by increasing concentrations of LPS added to the medium, further confirming the peptide's affinity for endotoxin. Antimicrobial assays showed that temporin L interacted synergistically with the clinically used beta-lactam antibiotics piperacillin and imipenem. Therefore, we characterized the activity of temporin L when combined with imipenem and piperacillin in the prevention of lethality in two rat models of septic shock, measuring bacterial growth in blood and intra-abdominal fluid, endotoxin and tumor necrosis factor alpha (TNF-alpha) concentrations in plasma, and lethality. With respect to controls and single-drug treatments, the simultaneous administration of temporin L and beta-lactams produced the highest antimicrobial activities and the strongest reduction in plasma endotoxin and TNF-alpha levels, resulting in the highest survival rates.
Giacometti
Andrea
A
Institute of Infectious Diseases and Public Health, University of Ancona, Ancona, Italy.
Cirioni
Oscar
O
Ghiselli
Roberto
R
Mocchegiani
Federico
F
Orlando
Fiorenza
F
Silvestri
Carmela
C
Bozzi
Argante
A
Di Giulio
Antonio
A
Luzi
Carla
C
Mangoni
Maria Luisa
ML
Barra
Donatella
D
Saba
Vittorio
V
Scalise
Giorgio
G
Rinaldi
Andrea C
AC
D000818:Animals; D000890:Anti-Infective Agents / Q000378:metabolism / Q000627:therapeutic use*; D023181:Antimicrobial Cationic Peptides; D004195:Disease Models, Animal; D004359:Drug Therapy, Combination; D006090:Gram-Negative Bacteria / Q000187:drug effects*; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy / Q000382:microbiology / Q000401:mortality; D006801:Humans; D015378:Imipenem / Q000627:therapeutic use; D008070:Lipopolysaccharides / Q000378:metabolism*; D008297:Male; D008826:Microbial Sensitivity Tests; D010538:Peritonitis / Q000188:drug therapy / Q000382:microbiology; D010878:Piperacillin / Q000627:therapeutic use; D011506:Proteins / Q000378:metabolism* / Q000627:therapeutic use*; D051381:Rats; D017208:Rats, Wistar; D012772:Shock, Septic / Q000188:drug therapy* / Q000382:microbiology / Q000401:mortality; D047090:beta-Lactams / Q000627:therapeutic use
D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D008070:Lipopolysaccharides; D011506:Proteins; D047090:beta-Lactams; C104501:temporin; D015378:Imipenem; D010878:Piperacillin