The skin commensal yeastMalasseziapromotes tissue homeostasis via the aryl hydrocarbon receptor

As an abundant fungal colonizer of human skin,Malasseziahas long been associated with pathological skin conditions, yet its role in skin homeostasis remain poorly understood. Here, we demonstrate thatMalassezia furfurplays an active role in maintaining epidermal integrity by producing tryptophan-derived metabolites that activate the aryl hydrocarbon receptor (AhR), a key regulator of keratinocyte differentiation and inflammation. Using a fungal mutant defective in indole production, we show thatM. furfur-derived AhR activation is required to restore barrier function and control inflammation in diseased skin. AhR-deficient mice fail to benefit fromM. furfur-mediated barrier protection, underscoring the importance of microbial-derived AhR agonists in skin physiology. These findings establish a previously unrecognized mutualistic role forMalasseziain epidermal homeostasis, challenging its perception as solely a pathogenic fungus and expanding our understanding of the skin microbiota’s influence on barrier function and immune regulation.