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Trichophyton rubrum is responsible for the majority of dermatophytosis. Current systemic and topical antifungals against dermatophytosis are often tedious and sometimes unsatisfactory. Antimicrobial photodynamic therapy (aPDT) is a non-invasive alternative suitable for the treatment of superficial fungal infections. This work investigated the photodynamic inactivation efficacy and effects of aloe-emodin (AE), a natural photosensitizer (PS) against T. rubrum microconidia in vitro, and evaluated the treatment effects of AE-mediated aPDT for T. rubrum-caused tinea corporis in vivo and tinea unguium ex vivo.The photodynamic antimicrobial efficacy of AE on T. rubrum microconidia was evaluated by MTT assay. The inhibition effect of AE-mediated aPDT on growth of T. rubrum was studied. Intracellular location of AE, damage induced by AE-mediated aPDT on cellular structure and surface of microconidia and generation of intracellular ROS were investigated by microscopy and flow cytometry. The therapeutic effects of AE-mediated aPDT against dermatophytosis were assessed in T. rubrum-caused tinea corporis guinea pig model and tinea unguium ex vivo model. AE-mediated aPDT effectively inactivated T. rubrum microconidia in a light energy dosedependent manner and exhibited strong inhibitory effect on growth of T. rubrum. Microscope images indicated that AE is mainly targeted to the organelles and caused damage to the cytoplasm of microconidia after irradiation through generation of abundant intracellular ROS. AE-mediated aPDT demonstrated effective therapeutic effects for T. rubrum-caused tinea corporis on guinea pig model and tinea unguium in ex vivo model. The results obtained suggest that AE is a potential PS for the photodynamic treatment of dermatophytosis caused by T. rubrum, but its permeability in skin and nails needs to be improved.

No abstract

Infectious dermatological diseases caused by Malassezia furfur are often chronic, recurrent, and recalcitrant. Current therapeutic options are usually tedious, repetitive, and associated with adverse effects. Alternatives that broaden the treatment options and reduce side effects for patients are needed. Antimicrobial photodynamic therapy (aPDT) is an emerging approach that is quite suitable for superficial infections. The aim of this study is to investigate the antimicrobial efficacy and effect of aPDT mediated by haematoporphyrin monomethyl ether (HMME) and aloe emodin (AE) on clinical isolates of M. furfur in vitro. The photodynamic antimicrobial efficacy of HMME and AE against M. furfur was assessed by colony forming unit (CFU) assay. The uptake of HMME and AE by M. furfur cells was investigated by fluorescence microscopy. Reactive oxygen species (ROS) probe and flow cytometry were employed to evaluate the intracellular ROS level. The effect of HMME and AE-mediated aPDT on secreted protease and lipase activity of M. furfur was also investigated. The results showed that HMME and AE in the presence of light effectively inactivated M. furfur cells in a photosensitizer (PS) concentration and light energy dose-dependent manner. AE exhibited higher antimicrobial efficacy against M. furfur than HMME under the same irradiation condition. HMME and AE-mediated aPDT disturbed the fungal cell envelop, significantly increased the intracellular ROS level, and effectively inhibited the activity of secreted protease and lipase of M. furfur cells. The results suggest that HMME and AE have potential to serve as PSs in the photodynamic treatment of dermatological diseases caused by M. furfur, but further ex vivo or in vivo experiments are needed to verify that they can meet the requirements for clinical practice.