Defensive Effects of Human Antimicrobial Peptide α-Defensins against Enterococcus faecalis

• Published in: Journal of Health Science Vol. 56; no. 5; pp. 618 - 622
• Main Authors: Miyoshi, Shin-ichi, Koyama, Kenta, Mizuno, Tamaki, Kashihara, Minoru, Maehara, Yoko, Nakao, Hiroshi
• Format: Journal Article
• Language: English
• Published: The Pharmaceutical Society of Japan 2010
• Subjects: antimicrobial peptide; Enterococcus faecalis; human α-defensin; innate immunity
• ISSN: 1344-9702; 1347-5207
• DOI: 10.1248/jhs.56.618

Cationic and amphiphilic antimicrobial peptides (AMPs) such as α-defensins and cathelicidins are factors related to innate immunity. In the present study, we examined the protective effects of two AMPs, human neutrophil peptide-3 and α-defensin-5, against the opportunistic pathogen Enterococcus faecalis (E. faecalis). The α-defensins had dose-dependent bactericidal activity, whereas they showed no synergistic effect on the antimicrobial actions of antibiotics. Although AMPs often neutralize bacterial bioactive products, neither α-defensin reduced the proteolytic activity of GelE, a toxic protease from E. faecalis. On the other hand, the α-defensins were found to be fairly stable even in the presence of excess amounts of GelE. These results indicate that α-defensins may be defensive factors against E. faecalis in humans.