<i>Staphylococcus aureus</i> proteases trigger eosinophil-mediated skin inflammation.

Abstract

<i>Staphylococcus aureus</i> skin colonization and eosinophil infiltration are associated with many inflammatory skin disorders, including atopic dermatitis, bullous pemphigoid, Netherton's syndrome, and prurigo nodularis. However, whether there is a relationship between <i>S. aureus</i> and eosinophils and how this interaction influences skin inflammation is largely undefined. We show in a preclinical mouse model that <i>S. aureus</i> epicutaneous exposure induced eosinophil-recruiting chemokines and eosinophil infiltration into the skin. Remarkably, we found that eosinophils had a comparable contribution to the skin inflammation as T cells, in a manner dependent on eosinophil-derived IL-17A and IL-17F production. Importantly, IL-36R signaling induced CCL7-mediated eosinophil recruitment to the inflamed skin. Last, <i>S. aureus</i> proteases induced IL-36α expression in keratinocytes, which promoted infiltration of IL-17-producing eosinophils. Collectively, we uncovered a mechanism for <i>S. aureus</i> proteases to trigger eosinophil-mediated skin inflammation, which has implications in the pathogenesis of inflammatory skin diseases.