The following is a summary of “Spatial Distribution and Functional Impact of Human Scalp Hair Follicle Microbiota,” published in the  June 2024 issue of Dermatology by Lousada, et al.

Human hair follicles (HFs) harbor a distinct microbiota ecosystem, distinct from the skin surface, yet their microbial composition and functions still need to be explored due to limitations in traditional sampling methods. In this study, we employed laser-capture microdissection, metagenomic shotgun sequencing, and fluorescence in situ hybridization (FISH) techniques to investigate the microbiota inhabiting different anatomical compartments of the human scalp HF. For a study, researchers unveiled significant variations in microbiota composition influenced by HF compartment, tissue lineage, and donor age. Notably, viruses, archaea, Staphylococcus epidermidis, Cutibacterium acnes, and Malassezia restricta exhibited the greatest abundance variations among HF compartments, with the latter two emerging as the most prevalent viable HF colonizers, particularly enriched in the HF mesenchyme.

Furthermore, the study revealed functional implications of the HF microbiota on host physiology. Transfection of organ-cultured human scalp HFs with lytic bacteriophages specific to S. epidermidis, a prevalent HF microbe, resulted in the downregulation of genes associated with HF growth, development, metabolism, and melanogenesis. It suggested that microbial products from specific HF inhabitants may influence HF functions. Consistently, treatment of HFs with butyrate, a metabolite produced by S. epidermidis and other HF microbiota, elicited effects such as delayed catagen, enhanced autophagy, increased mitochondrial activity, and upregulated expression of key proteins gp100 and dermcidin ex vivo.

In summary, the findings highlighted spatial variations in the abundance and functional impact of the human HF microbiota. Understanding these interactions opens avenues for therapeutic interventions targeting the HF microbiota to modulate host physiology.

Reference: sciencedirect.com/science/article/abs/pii/S0022202X23031196