Keratinocytes produce IL-6 in response to desmoglein 1 cleavage by Staphylococcus aureus exfoliative toxin A

Many skin infections are caused by Staphylococcus aureus, a bacterial pathogen that produces virulence factors associated with these conditions such as exfoliative toxins A and B (ETA, ETB) and the leukotoxin Panton-Valentine leukocidin (PVL). Herein, we examine the potential of skin-infecting S. aureus to produce virulence factors and their impact on the local immune response. Toxin gene profiles were generated from 188 S. aureus isolated as single infecting organisms from skin lesions and demonstrated a higher potential to express ETA, ETB, and PVL than community isolates (p < 0.001). Within the study isolate group, the prevalence of genes encoding PVL was higher among methicillin-resistant S. aureus (MRSA; n = 49), while genes encoding ETs were more prevalent in methicillin-susceptible S. aureus (MSSA; n = 139). When lesion-associated white blood cell (WBC) counts were dichotomized into high- or low-WBC-count-associated bacteria, the gene for ETA was found to be associated with a low WBC count among MSSA (p = 0.001). The ETA-induced mouse model of staphylococcal scalded skin syndrome was used to investigate the link between ETA and cytokine production. Elevated IL-6 levels in the serum and increased expression of IL-6 mRNA in the skin were detected in response to ETA exposure. These findings were recapitulated in vitro using primary human keratinocytes. Thus, S. aureus may influence the local immune response via ETA cleavage of desmoglein 1 and the induction of cutaneous IL-6 expression.