Water-filtered infrared A irradiation exerts antifungal effects on the skin fungus Malassezia.

ABSTRACT

Many common skin diseases are associated with changes in the microbiota. This applies for the commensal yeast Malassezia, which is linked to a wide range of skin disorders ranging from mild dandruff to severe seborrheic and atopic dermatitis, all of which have a detrimental impact on the individuals' quality of life. While antifungal medications offer relief in many cases, the challenges of disease recurrence and the emergence of resistance to the limited range of available antifungal drugs poses a pressing need for innovative therapeutic options. Here we examined the activity of water-filtered infrared A (wIRA) irradiation against Malassezia. wIRA's antimicrobial and wound healing properties make it an attractive option for localized, non-invasive, and contact-free treatment of superficial skin infections. Irradiation of Malassezia furfur with wIRA (570-1400 nm) resulted in a reduction of the yeast's metabolic activity. When put in contact with immune cells, wIRA-irradiated M. furfur was recovered at lower counts than non-irradiated M. furfur. Likewise, wIRA irradiation of M. furfur put in contact with keratinocytes, the primary host interface of the fungus in the skin, reduced the fungal counts, while the keratinocytes were not affected by the irradiation. The combination of wIRA with the photosensitizer methyl aminolevulinate exerted an additional antifungal effect on M. furfur, irrespective of the presence or absence of keratinocytes, suggesting an enhancement of the treatment effect when used in combination. These findings suggest that wIRA holds promise as a potential therapy for skin disorders associated with Malassezia.