# Postauricular Skin Mycobiome Profiles in Atopic Dermatitis Treated With Dupilumab or Cyclosporine A: A Descriptive Case Series

## TL;DR

This study explores how two AD treatments, dupilumab and cyclosporine, affect the fungal makeup of the skin, particularly the Malassezia species.

## Contribution

The study provides new insights into how systemic AD therapies alter the skin mycobiome, specifically Malassezia species.

## Key findings

- Both treatments increased the abundance of Malassezia in the skin mycobiome.
- There was a shift from M. globosa to M. restricta after treatment.
- Patients with initially low Malassezia saw significant increases after treatment.

## Abstract

Atopic dermatitis (AD) essentially exhibits dysbiosis of skin fungal microbiome, mycobiome, characterized by depletion of Malassezia. The effects of recent systemic therapies for AD on skin mycobiome were not understood enough. We examined changes of skin mycobiome before and after systemic treatments with anti‐IL‐4Rα antibody (dupilumab: DUP) and calcineurin inhibitor (cyclosporine, CyA). Swab samples from postauricular areas in 19 AD patients treated with dupilumab (n = 13) and cyclosporine (n = 6) were collected before and 4–8 weeks after starting each treatment. Fungal DNA was amplified from the samples and sequenced with ITS1 metagenomic analysis, and taxonomic classification was performed. Fungi belonging to total 89 genera were detected. The share of the fungus was most occupied by Malassezia (81.3%), followed by Aspergillus (3.7%), and Trametes (1.1%) before DUP and CyA treatment, and occupied by Malassezia (87.3%), followed by Aspergillus (1.9%), and Candida (1.7%) after treatment. Three AD patients whose ratio of Malassezia in the skin mycobiome was under 50%, showed an exploratory increase of Malassezia after treatments (before 17.3%, after 67%). Analysis of the Malassezia species revealed an increase in M. restricta (before 70.5%, after 79.5%) and a decrease in
M. globosa
(before 23.9%, after 16.1%). No consistent patterns distinguishing DUP and CyA were observed. Systemic treatment with DUP and CyA was associated with shifts toward higher Malassezia abundance and modulation between M. restricta and
M. globosa. These findings are exploratory and require validation in larger controlled studies.