Evidence for a disease-promoting effect of Staphylococcus aureus-derived exotoxins in atopic dermatitis

Background: The skin of patients with atopic dermatitis (AD) exhibits a striking susceptibility to colonization with Staphylococcus aureus. Some strains of S aureus secrete exotoxins with T-cell superantigen activity (toxigenic strains), and abnormal T-cell functions are known to play a critical role in AD. Objective: Our purpose was to examine the impact of superantigen production hy skin-colonizing S aureus on disease severity. Methods: In a cross-sectional study of 74 children with AD, the presence and density of toxigenic and nontoxigenic strains of S aureus was correlated with disease severity. In a subgroup of patients the T-cell receptor V beta repertoire of peripheral blood and lesional T cells was investigated and correlated with individual superantigen activity of skin-colonizing S aureus. Results: Fifty-three percent of children with AD were colonized with toxigenic strains of S aureus producing staphylococcal enterotoxin C, staphylococcal enterotoxin A, toxic shock syndrome toxin-1, staphylococcal enterotoxin B, and staphylococcal enterotoxin D in decreasing frequency. Children colonized with toxigenic S aureus strains had higher disease severity compared,vith the nontoxigenic and S aureus-negative groups. Patients colonized with toxigenic S aureus exhibited shifts in the intradermal T-cell receptor V beta repertoire that correspond to the respective superantigen-responsive T-cell subsets. Conclusion: The data demonstrate that S aureus-released exotoxins can modulate disease severity and dermal T-cell infiltration.