Abstract: Xu Yuting, Zheng Wenqian, Gao Lujuan, Sun Yi, Li Linyun, Li Ming, Zeng Tongxiang The Second Clinical Medical College, Yangtze University, Jingzhou 434100, Hubei, China （Xu YT, Zheng WQ）; Department of Dermatology, Zhongshan Hospital, Fudan University, Shanghai 200032, China （Gao LJ, Li M）; Department of Dermatology, Jingzhou Central Hospital, the Second Clinical Medical College, Yangtze University, Jingzhou 434100, Hubei, China （Sun Y, Zeng TX）; Clinical Laboratory, Jingzhou Central Hospital, the Second Clinical Medical College, Yangtze University, Jingzhou 434100, Hubei, China （Li LY） Corresponding authors: Gao Lujuan, Email: gao_lujuan@163.com; Sun Yi, Email: jzzxyysy@163.com 【Abstract】 Objective To evaluate the in vitro effects of photodynamic therapy alone or in combination with antifungal agents on the apoptosis of planktonic and biofilm cells of Exophiala dermatitidis （E. dermatitidis）. Methods The planktonic suspensions of E. dermatitidis were prepared, and the biofilms of E. dermatitidis were prepared via a modified 96-well plate-based methods. Planktonic and biofilm cells of E. dermatitidis were separately divided into several groups: antifungal agent groups treated with antifungal agents alone, photodynamic therapy group receiving photodynamic therapy alone, combination groups receiving photodynamic therapy followed by the treatment with antifungal agents, and blank control group receiving no treatment. These antifungal agents included amphotericin B, posaconazole, voriconazole and itraconazole. The concentrations of these antifungal agents were all 1 mg/L, and the treatment with antifungal agents lasted 2 hours. Terminal deoxynucleotidyl transferase dUTP nick end labeling （TUNEL） assay was performed to detect the apoptosis of planktonic and biofilm cells of E. dermatitidis in all the groups. Results The antifungal agents and photodynamic therapy both affected the apoptosis of planktonic （both P < 0.001） and biofilm cells （both P < 0.05） of E. dermatitidis. The apoptosis rates of E. dermatitidis planktonic cells in the control group, amphotericin B group, posaconazole group, voriconazole group and itraconazole group were 11.67% ± 0.21%, 13.30% ± 1.78%, 14.30% ± 3.61%, 14.51% ± 1.91% and 36.17% ± 4.00% respectively. The apoptosis rate of E. dermatitidis planktonic cells was significantly higher in the itraconazole group than in the control group（P < 0.05）, but no significant differences were observed between the other 3 antifungal agent groups and control group （all P > 0.05）. The photodynamic therapy group also showed a significantly higher apoptosis rate of E. dermatitidis planktonic cells （41.37% ± 7.80%） compared with the control group （P < 0.05）. After the treatment with photodynamic therapy combined with amphotericin B, posaconazole, voriconazole or itraconazole, the apoptosis rates of E. dermatitidis planktonic cells were 29.23% ± 6.71%, 37.23% ± 10.86%, 43.57% ± 6.42% and 69.87% ± 3.53% respectively. Moreover, the photodynamic therapy + voriconazole group and photodynamic therapy + itraconazole group both showed significantly higher apoptosis rates compared with the voriconazole group and itraconazole group respectively（both P < 0.05）. The apoptosis rate of E. dermatitidis biofilm cells was significantly higher in the photodynamic therapy group than in the control group（32.00% ± 0.43% vs. 25.30% ± 1.31%, P < 0.05）, as well as in the photodynamic therapy + amphotericin B than in the amphotericin B group （P < 0.05）. Conclusion Photodynamic therapy combined with antifungal agents can markedly promote the apoptosis of planktonic and biofilm cells of E. dermatitidis.

Key words: Phialophora, Apoptosis, Photochemotherapy, Antifungal agents, Biofilms, Exophiala dermatitidis