Effects of an LL-37-derived antimicrobial peptide in an animal model of biofilm Pseudomonas sinusitis.
BACKGROUND
LL-37, an innate immunity protein expressed within sinonasal mucosa, has in vitro antibacterial and antifungal properties as well as efficacy against preformed Pseudomonas aeruginosa biofilms. We hypothesize that a 24 amino acid peptide derivative of LL-37 will show efficacy against biofilm-forming P. aeruginosa in an established animal model of sinusitis.


METHODS
Five groups of six New Zealand rabbits were each infected with P. aeruginosa (PAO-1) and fitted with irrigating catheters 7 days later. Each group was instilled with either one of three different concentrations of peptide, a positive control of topical tobramycin, or the carrier solution without the peptide once a day for 10 days. Nasal diluent was collected throughout the irrigation period to assess for persistence or resolution of infection by determining colony-forming units (CFU). At study end, sinus mucosa was harvested for histological assessment of inflammation and SEM evaluation for ciliary integrity and presence of biofilms.


RESULTS
Topical tobramycin at 400x minimum inhibitory concentration and 2.5 mg/mL of peptide were effective in significantly lowering CFUs after 10 days of irrigation. Histological evaluation showed increased signs of inflammation in a dose-dependent manner within mucosa and bone of the groups receiving the peptide. SEM analysis showed ciliary loss in a dose-dependent manner. Biofilms were present in all groups except for the highest concentration of peptide and tobramycin.


CONCLUSIONS
High concentrations of LL-37-derived peptide showed in vivo ability to eradicate Pseudomonas biofilms and decrease bacterial counts. However, increasing concentrations of peptide showed proinflammatory and ciliotoxic effects on sinus mucosa.
Chennupati
Sri Kiran
SK
Department of Otorhinolaryngology-Head and Neck Surgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Chiu
Alexander G
AG
Tamashiro
Edwin
E
Banks
Caroline A
CA
Cohen
Michael B
MB
Bleier
Benjamin S
BS
Kofonow
Jennifer M
JM
Tam
Eric
E
Cohen
Noam A
NA
D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000008:administration & dosage*; D018441:Biofilms; D015169:Colony Count, Microbial; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005260:Female; D008070:Lipopolysaccharides; D015523:Maxillary Sinusitis / Q000188:drug therapy* / Q000382:microbiology / Q000473:pathology; D055556:Nasal Lavage; D011552:Pseudomonas Infections / Q000188:drug therapy* / Q000382:microbiology / Q000473:pathology; D011550:Pseudomonas aeruginosa / Q000502:physiology*; D011817:Rabbits; D016896:Treatment Outcome; D054804:Cathelicidins
D023181:Antimicrobial Cationic Peptides; D008070:Lipopolysaccharides; D054804:Cathelicidins