Recent studies have shown that the skin microbiota plays a role in epidermal barrier formation. However, it unclear whether the skin microbiota modulates epidermal tight junction (TJ) barrier formation or function. Butyrate is produced from bacterial carbohydrate fermentation and is a known enhancer of the intestinal TJ barrier. We hypothesize that similar mechanisms may apply to the skin. This study set out to examine the ability of selected members of skin microbiota to impact TJ function in primary normal human epidermal keratinocytes (NHEKs) via butyrate production. Skin swabs were collected from five healthy participants and commensal bacteria were isolated and identified by DNA sequencing. Isolated skin commensal bacteria were grown in media containing glycerol as a single carbohydrate source since this has been shown to result in butyrate production. The toxicity of the glycerol-fermented bacterial supernatants to the calcium-switched NHEKs was measured using a tetrazolium reduction (MTT) assay. TJ integrity was determined by measurement of transepithelial electrical resistance (TEER). A total of 155 bacterial isolates were identified, belonging to 8 genera. Several staphylococci fermented glycerol. Five species (S. epidermidis, S. hominis, S. capitis S. lugdunesis, and S. caprae) were selected for further study. The resulting metabolites of these bacteria were not toxic to differentiated NHEKs. There was no difference in TEER between NHEKs treated with supernatants from glycerol fermented bacteria vs untreated NHEKs. A significant increase in TEER was however observed in NHEKs treated with 4 mM sodium butyrate for 48 h compared to untreated cells (N=5, P= 0.0231). However, treatment with lower concentrations (2 mM and 0.5 mM) induced no change in TEER. These data suggest that the epidermal TJs may be modifiable by butyrate. Further studies are needed to investigate whether skin commensal bacteria could produce butyrate at concentrations sufficiently high to induce a physiological effect on TJs.

LB040 - Can the Skin Microbiota Enhance Skin Tight Junction Function by Glycerol Fermentation?

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.