Staphylococcus aureus strains isolated from keratinocyte skin cancers. Staphylococcus aureus

Squamous cell carcinoma (SCC) is a common type of skin cancer that typically arises from premalignant lesions termed actinic keratoses (AK). Certain secreted products from S. aureus are known to promote cutaneous pro-inflammatory responses, however, not all S. aureus strains produce these. As inflammation plays a key role in SCC development, we investigated the pro-inflammatory potential and toxin secretion profiles of skin-cancer associated S. aureus. Sterile culture supernatants ('secretomes') of S. aureus clinical strains isolated from AK and SCC were applied to human keratinocytes in vitro. Some S. aureus secretomes induced keratinocytes to overexpress inflammatory mediators that have been linked to skin carcinogenesis, including IL-6, IL-8, and TNF-alpha. A large phenotypic variation between the tested clinical strains was observed. Strains that are highly pro-inflammatory in vitro also caused more pronounced skin inflammation in mice. This study is the first to describe the toxin secretion profiles of AK and SCC-associated S. aureus, and their potential to induce a pro-inflammatory environment in the skin.