VIENNA — Levels of some of the skin's key innate antimicrobial peptides are abnormally low in patients with atopic dermatitis, perhaps accounting for the high rate of bacterial and viral superinfections in this population, Jurgen Harder, M.D., said at the annual meeting of the European Society for Dermatological Research.
The explanation for the low skin levels of antimicrobial peptides may lie in the high levels of Th2 cytokines typically present in atopic skin. These cytokines appear to sharply inhibit secretion of the antimicrobial peptides by keratinocytes, added Dr. Harder of the University of Kiel (Germany).
He presented evidence from in vitro studies done in Kiel showing that high concentrations of the Th2 cytokines interleukin-4 (IL-4), IL-10, and IL-13 greatly dampen the normally robust induction of an important antimicrobial peptide in normal skin, human β-defensin-2, by Pseudomonas aeruginosa.
These findings are consistent with the hypothesis that bacterially mediated induction of inducible antimicrobial proteins is disrupted in atopic dermatitis patients and that the culprit is high levels of the Th2 cytokines.
Decreasing elevated Th2 cytokine levels may be a novel strategy to prevent cutaneous superinfections in patients with atopic dermatis, Dr. Harder said.