The Role of the Microbiome in Scalp Hair Follicle Biology and Disease

The document from May 15, 2019, explored the role of the microbiome in scalp hair follicle biology and disease. It revealed that a single square centimeter of human skin can host up to one billion microorganisms, forming the skin microbiome. The composition of this microbiome, which varies across different skin regions, plays a role in inflammatory processes related to multiple hair diseases, including alopecia areata and lichen planopilaris. The study also highlighted the importance of T regulatory cells in maintaining immune homeostasis and hair cycle regulation. The presence of cutaneous microbes was found to stimulate the expression of chemokine Ccl20 within the infundibulum of developing hair follicles, attracting Tregs. Disruption of this process could potentially lead to an inflammatory response. The document concluded that the microbiome plays a significant role in scalp hair follicle biology and disease, and further research is needed to fully understand these complex interactions. It also suggested a possible connection between the colonization of the scalp by Alternaria spp. and alopecia areata development, with fungi of this genus found in 20% of patients compared to 13.3% of controls.