Skin acts as an interface with the external environment and with this, is the first line of defence to ultraviolet radiation (UVR). In mice, the skin microbiome has proven important in modulating UVR responses. However, understanding of the role of the skin microbiome in mediating human responses to UVR and which commensal members may contribute to this photoprotection remains limited. In this study, we investigated the photoprotective effects of a skin commensal (HS01 – Micrococcus spp.) isolated from a healthy human volunteer on the most abundant cell type in the epidermis, keratinocytes. Normal human epidermal keratinocytes (NHEKs) were exposed to UVR (5 – 30mJ/cm², 313nm) ± HS01 (1x10²-1x10⁴ CFU/ml) and the effects on NHEK viability (trypan blue), microbial adherence, inflammation (enzyme-linked-immunosorbent-assay; ELISA: interleukin-6;IL-6, IL-8, pentraxin-3;PTX-3 and macrophage inflammatory protein-3α; MIP-3α) and proliferation (ELISA; vascular endothelial growth factor; VEGF) were assessed 24h post-irradiation. UVR application resulted in a dose-dependent decrease in cell viability. HS01 (low dose; 1 x 10²CFU/mL) elevated cell viability by 53% following irradiation at 30mJ/cm² relative to the respective control. This was accompanied by a 174% increase in HS01 adherence to NHEKs relative to the non-irradiated control. UVR elevated IL-6, IL-8 and PTX-3 secretion by keratinocytes was exacerbated by high dose (1x10⁴ CFU/ml), but not low dose HS01. Both high and low dose HS01 reduced UVB modulated (30mJ/cm²) secretion of VEGF and MIP-3α. Taken together, these data show UVR promotes HS01 adherence to NHEKs, possibly resulting in manipulation of inflammatory mediators and subsequent photoprotection. These data provide novel insight into the contribution of skin commensals to UVR responses.

LB021 - The Photoprotective Effects of a Skin Commensal on Ultraviolet Radiation Stimulated Epidermal Keratinocytes

The scientific meeting of the European Society for Dermatological Research (ESDR) is held yearly, usually in September. With an international attendance of more than 1000 skin scientists from around the globe, the four-day event includes short oral presentations from peer-reviewed abstracts, keynote lectures from international experts, sponsored symposia, satellite programs, educational events as well as an important focus on posters, networking and building collaborations amongst scientists. For more information about this year’s meeting visit our website.