Human hair follicles (HFs) display an unusually rich microbiome, which is dominated by Cutibacterium, Streptococcus, Staphylococcus, Corynebacterium and Malassezia species that interact with the host immune system. Yet, while dysbiosis of the HF microbiome is associated with several HF diseases, it is largely unknown how these commensals impact on human HF physiology. Since S. epidermidis, a major human HF microbiome constituent, prominently secretes butyrate, we evaluated whether this bacterial metabolite impacts on key HF physiology read-outs. When healthy scalp HFs were organ-cultured in the presence of 1mM sodium butyrate for 6-8 days, this significantly delayed catagen onset, independent of hair matrix keratinocyte proliferation, (note that the epithelium of human anagen HFs establishes a complex tight junction barrier) and significantly promoted autophagy (LC3b protein expression), mitochondrial activity (MTCO1 protein expression), early stages of melanogenesis (up-regulation of the pre-melanosomal marker, gp100), while not altering melanin production, and HF production of the antimicrobial peptide, dermcidin (mRNA and protein expression). These findings correspond well to bacterial metabolite-induced changes in the intestinal epithelium, where butyrate also promotes mitochondrial function, increases autophagic flux, and enhances epithelial barrier function. Our data strongly suggest that, similar to gut environment, HF commensals can alter clinically relevant elements of human HF physiology that invites therapeutic targeting. Further, that defined bacterial metabolites may be exploited to promote human HF growth, metabolism, pigmentation and/or antimicrobial defences.

ESDR558 - The Bacterial Metabolite, Butyrate, Prolongs Anagen and Promotes Autophagy, Mitochondrial Activity, Melanogenesis and Antimicrobial Peptide Production in Human Scalp Hair Follicles

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.