Human Skin Microbiome Landscape... Lessons from Dandruff Scalp
Our body’s largest organ, skin, is covered with various microorganisms, including fungi, bacteria, archaea and viruses, with bacteria out numbering the others. Several studies have revealed that healthy skin microbiome is determined by ecological zones of the skin as well as various host-related factors such as age, diet and gender and environmental factors, such as pollution and geographic location.
Skin microbiome has positive impact on several aspects of human health, such as innate immune response modulation and protection against pathogens. Microorganisms interact with host keratinocytes and innate immune system, stimulating the secretion of antimicrobial peptides, free fatty acids, cytokines and chemokines, which might lead to adaptive immune responses. The skin microbiota contribute also to reinforce the skin barrier function (tight junctions, elicitation of antimicrobial peptides). Thus it is essential to understand how its disequilibrium contributes to skin disorders such as dandruff condition.
Dandruff is one of the most common skin conditions, affecting approximately half of adult population worldwide. This inflammatory chronic disorder is related to skin barrier disruption, epidermal cellular proliferation and differentiation, as well as shifts in sebum composition. It has been frequently associated with yeasts from Malassezia genus, which are also members of the healthy cutaneous microbiome. However, the microbial role has not been elucidated yet, and the etiology of the disorder remains incompletely understood. We used sanger and next-generation sequencing (NGS) to analyze bacterial and fungal microbiota associated with skin from normal and dandruff subjects.
Microbial shift in both bacterial and fungal communities were observed in lesional and in non-lesional sites from dandruff subjects, suggesting that dandruff is related to a systemic process that is not restricted to the site exhibiting clinical symptoms.
Our recent studies on dandruff scalp microbiota provides new perspectives for the understanding of this skin disorder, establishing steps toward a broader view of dandruff etiology and the role of the different microbiome players in the symptom development.