Staphylococcal exotoxins are strong inducers of IL-22: A potential role in atopic dermatitis.

BACKGROUND

Patients with atopic dermatitis (AD) and psoriasis are frequently colonized with Staphylococcus aureus that produces staphylococcal enterotoxin B (SEB) and α-toxin. In patients with AD, S aureus colonization is positively correlated with the severity of their eczema. Moreover, IL-22-producing cells have been shown to accumulate in AD skin and to correlate with disease severity.

OBJECTIVE

To assess IL-22 production in response to SEB and sublytic α-toxin stimulation in patients with AD and psoriasis compared with healthy controls.

METHODS

IL-22 induction was investigated in PBMCs, T cells, and autologous cocultures of keratinocytes and T cells on SEB and α-toxin stimulation in a time-dependent and dose-dependent manner at the mRNA and protein (ELISA and flow cytometry) level. Anti-IL-1 receptor or anti-IL-6 antibodies were used in blocking experiments.

RESULTS

Staphylococcal enterotoxin B and sublytic α-toxin concentrations induced IL-22 production in PBMCs and isolated CD4(+) T cells. IL-22 secretion was enhanced by α-toxin stimulation in autologous cocultures of keratinocytes and T cells. In T cells and PBMCs from patients with AD, IL-22 secretion was significantly enhanced on α-toxin stimulation compared with patients with psoriasis and healthy controls.

CONCLUSION

Increased IL-22 secretion induced by staphylococcal exotoxins in the skin partially explains how skin colonization and infection with S aureus can contribute to chronic skin inflammation in AD.