Presence of <i>Malassezia</i> Hyphae Is Correlated with Pathogenesis of Seborrheic Dermatitis

Abstract

Seborrheic dermatitis (SD) is a common, chronic, and relapsing skin disease. The roles of <i>Malassezia</i> spp. in the pathogenesis of SD are still not clear due to the lack of direct evidence for the existence of hyphae within affected skin tissues. We set out to elucidate if <i>Malassezia</i> mycelium contributes to the onset and development of SD and if <i>Malassezia</i> mycelium is correlated with the clinical severity of SD patients. We detected <i>Malassezia</i> hyphae in patients with SD using potassium hydroxide (KOH) and calcofluor white (CFW) staining. Fluorescent microscopy was performed for the analysis of fungal cell wall and morphological characteristics of <i>Malassezia</i> under CFW staining. Culture growth in modified Dixon agar was used for DNA extraction and sequencing, and <i>Malassezia</i> species were confirmed by a sequencing data BLAST search against the NCBI database. We demonstrated that <i>Malassezia</i> hyphae were positively correlated with the clinical severity of SD patients (<i>P </i>= 3.1738 × 10^-11). All the patients responded well to antifungal treatment. There is no significant difference for species dominance across the variant groups. However, the exact molecular mechanisms of how <i>Malassezia</i> spp. affect SD need to be further explored. The results show that <i>Malassezia</i> spp. in the hyphal stage are restricted to SD patients compared with healthy controls, suggesting that the presence of <i>Malassezia</i> hyphae contributes to the pathogenesis of SD. The results highlight the importance of the antifungal therapy for the future treatment of SD patients. <b>IMPORTANCE</b> Our results support the proposal that the hyphal form of <i>Malassezia</i> could be one of the pathogenic factors that contribute to SD, which has been previously less well studied. This clinical observation paves the way for further investigations of the molecular mechanisms of <i>Malassezia</i> hyphal pathogenicity in SD.