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

The study investigated the impact of the bacterial metabolite butyrate, prominently secreted by S. epidermidis, a major constituent of the human hair follicle (HF) microbiome, on key HF physiology. Healthy scalp HFs were organ-cultured in the presence of 1mM sodium butyrate for 6-8 days. The results showed that butyrate significantly delayed the onset of catagen (the phase of hair cycle when hair stops growing), promoted autophagy (as indicated by increased LC3b protein expression), enhanced mitochondrial activity (evidenced by increased MTCO1 protein expression), and stimulated early stages of melanogenesis (as shown by up-regulation of the pre-melanosomal marker, gp100). However, it did not alter melanin production. Butyrate also increased the production of the antimicrobial peptide, dermcidin. These findings suggest that bacterial metabolites may be used to promote human HF growth, metabolism, pigmentation, and antimicrobial defenses, similar to their effects in the gut environment.