Quantitative comparison of the expression of antimicrobial peptides in the oral mucosa and extraoral skin

Antimicrobial peptides (AMP) defend epithelial surfaces against pathological micro-organisms. We know of no comparison of their expression between the oral mucosa and extraoral epithelium, but knowledge of differences in their quantities is of interest, possibly as a starting point for new treatments. Expression of AMP human beta-defensin (hBD)-1/-2/-3 and psoriasin in the oral mucosa and extraoral epithelium of the head and neck were measured by real-time polymerase chain reaction (RT-PCR) (n = 14), immunohistochemistry (n = 6), and western blot (n = 8). RT-PCR showed that all the genes investigated were expressed significantly more in the oral mucosa than in the skin (hBD-1: p = 0.002; hBD-2: p = 0.006; hBD-3: p = 0.035; psoriasin: p = 0.02). Immunohistochemistry and western blot showed differential concentrations of proteins: hBD-2 (p = 0.021) and hBD-3 (p = 0.043) were pronounced in the oral mucosa, whereas psoriasin was raised in the extraoral skin (p = 0.021). There was no difference in protein concentrations for hBD-1 (p = 0.08). The observed differences in the expression of AMP may be important for new treatments such as topical application of AMP derivatives.