Poster session 2, September 22, 2022, 12:30 PM - 1:30 PM Background Androgenetic alopecia (AGA) is the most common type of hair loss that seriously affects the appearance and psychology of patients. Some studies show that Malassezia seems to participate in the development of AGA, but there is still debate on this because of absent hyphae in the alopecia area. Interestingly, M. hyphae were found in scalp alopecia area of AGA patients. Thus, we speculate that the hyphae form of Malassezia may be not causal in AGA patients, and the M. hyphae may play a possible role in AGA. Objective The present study aims to elucidate the correlation of M. mycelia with hair loss in AGA patients and compare the species distribution of Malassezia in scalp between AGA patients and healthy individuals. Methods We sampled scales from scalp alopecia area from the patients diagnosed with AGA. The specimen was stained with calcofluor white staining (CFW) and observed for Malassezia structure under light microscopy and fluorescence microscopy. In the meanwhile, the scales were used for DNA direct extraction and sequencing. The other part of the specimen was inoculated onto Modified Dixon agar and culture at 37°C for 7 days. The isolates were identified by morphological and molecular sequencing (ITS1 and ITS4). Results The fungal load of Malassezia was significantly increased and short club-shaped mycelia exist in AGA patients, accounting for 48.89%, The fungal load was positively correlated with the skin inflammation of the hair loss area. The skin inflammation on the hair loss scalp was relieved after the treatment with antifungal agents, accompanying the disappearance of M. hyphae and decreasing of fungal load. There is no difference in species distribution of Malassezia in both AGA patients and healthy individuals. M. globosa and M. restricta are the two most common species isolated from the hair loss area. Conclusion Malassezia mycelia exist in patients with mild to moderate AGA, accounting for a certain percentage. The hair loss stopped accompanied with the disappearance of M. hyphae and decreasing of fungal burden. Our data suggest that the presence of M. hyphae may contribute to the pathogenesis of AGA.

Immunoglobulin E (IgE) elevation is a hallmark of allergic conditions such as atopic dermatitis (AD). The pathogenesis of AD is typically associated with high levels of IL-4 and IL-13 produced by activated T helper 2 (Th2) cells. Psoriasis, on the other hand, is an inflammatory skin disease mainly driven by Th17 cells and their related cytokines. Although the immunopathologic reactions and clinical manifestations are often easily distinguished in the two skin conditions, patients with psoriasis may sometimes exhibit AD-like manifestations, such as elevated IgE and persistent pruritic lesions. Given the fact that the effective T cells have great plasticity to re-differentiate in response to innate and environmental factors, this unusual skin condition could be a consequence of a cross-reaction between distinct arms of T-cell and humoral immunity. Here we review the literature concerning the roles of IgE in the development of AD and psoriasis, showing that elevated IgE seems to be an important indicator for this non-typical psoriasis.