Staphylococcal exotoxins induce interleukin 22 in human th22 cells.

BACKGROUND We have shown previously that T cells from atopic dermatitis (AD) patients produce more IL-22 upon staphylococcal exotoxin stimulation compared to psoriasis patients and healthy controls. The role of staphylococcal exotoxins on polarized memory T helper (Th)22 cells which are enriched in inflamed AD skin remains elusive. Our aim was to investigate IL-22 production in response to staphylococcal enterotoxin B (SEB) and α-toxin stimulation in human memory T cells and polarized Th22 cells. METHODS IL-22 induction was investigated in human peripheral blood-derived CD4+CD45RO+CD45RA- T cells and polarized Th22 cells after SEB and sublytic α-toxin stimulation in a time-dependent manner at the mRNA and protein (ELISA) levels. RESULTS Th22 cells secreted more IL-22 compared to freshly isolated peripheral blood-derived memory T cells. SEB and α-toxin induced IL-22 in memory T cells as well as in Th22 cells. More IL-22 was induced by SEB and α-toxin in freshly isolated peripheral blood memory T cells compared to Th22 cells derived from memory T cells in long-term cell culture without polarization and Th22 cells under Th22-promoting conditions with IL-6 and TNF-α. No differences in IL-22 induction by staphylococcal exotoxins were observed between cells from AD compared to psoriasis patients and healthy controls. CONCLUSIONS Increased IL-22 secretion can promptly be induced by staphylococcal exotoxins in skin infiltrating CD4+CD45RO+CD45RA- memory T cells and can potentially amplify chronic skin inflammation in AD in the context of bacterial colonization and infection. This should be investigated further in detail in lesional skin of AD and psoriasis patients.