Scientists at the National Jewish Medical and Research Center and the University of Colorado Health Sciences Center, in Denver, have discovered that skin cells ward off infection with a protein called human β-defensin-3 (Kisich KO et al. J Invest Dermatol. doi:10.1038/sj.jid.5700861 [published online ahead of print April 26, 2007]).
Because bacteria can cause skin infections and sepsis, the researchers set out to better understand the innate mechanisms employed by normal epidermis to prevent bacterial invasion and infection. Their experiments showed that skin cells secrete a variety of antimicrobial peptides when they come in contact with bacteria, but only human β-defensin-3 is produced at levels sufficient to account for bacterial killing. In addition, blocking human β-defensin-3 inhibited killing of bacteria. The study's findings help explain why infection of healthy skin cells rarely occurs, even though they are constantly exposed to bacteria.
Hampton T. Skin’s Antibacterial Proteins. JAMA. 2007;297(21):2339. doi:10.1001/jama.297.21.2339-b