Abstract
Objectives: To evaluate the effect of intense pulsed light (IPL) on Trichophyton rubrum and investigate its mechanism of action.Methods: The viability of fungi treated with IPL alone and with IPL combined with an NADPH oxidase inhibitor (DPI) pretreatment was determined by MTT assays. The reactive oxygen species (ROS) were quantified with a DCFH-DA fluorescent probe. Malondialdehyde (MDA) content and superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were determined by commercial kits. The transcription of the Nox gene was quantified using quantitative real-time PCR (qRT-PCR) analysis, and micromorphology was observed using scanning electron microscopy (SEM). In addition, fungal keratinase activity was detected by measuring dye release from keratin azure.Results: The growth declined with statistical significance after 6 h of treatment (P < 0.001). The ROS and MDA content increased after IPL treatment, whereas the SOD and GSH-Px activity decreased. Nox gene expression was upregulated, and the micromorphology was damaged. Keratinase activity decreased. Fungi that received DPI pretreatment exhibited contrasting outcomes.Conclusion: We found that 420-nm IPL significantly inhibited the growth and pathogenicity of T. rubrum in vitro. A suggested mechanism involves Nox as a factor that mediates 420-nm IPL-induced oxidative damage of T. rubrum.
Highlights
Trichophyton rubrum is one of the most common dermatophytes and causes a range of superficial fungal diseases that infect keratinized tissues such as skin, hair and nails (Aly, 1994; Burmester et al, 2011; Nenoff et al, 2014)
Sabouraud dextrose agar (SDA) plates were separately inoculated with each strain and incubated for 7 days at 28◦C; following the incubation period, spores were collected by brushing the culture surface with 3 ml of phosphate-buffered saline (PBS) using a sterile glass rod
Colonies of both strains were used for this experiment as follows: (I) Two individual aliquots (10 μl each) of the T. rubrum spore suspension were pipetted onto two separate areas of new SDA plates before Intense pulsed light (IPL) irradiation, and (II) the spore suspensions were cultured in 96-well flat-bottomed microdilution plates (100 μL per well, 3 wells per group) for IPL irradiation
Summary
Trichophyton rubrum is one of the most common dermatophytes and causes a range of superficial fungal diseases that infect keratinized tissues such as skin, hair and nails (Aly, 1994; Burmester et al, 2011; Nenoff et al, 2014). The current management strategies for T. rubrum infections include systemic and topical antifungal pharmaceutical treatments (Meis and Verweij, 2001). Treatment methods that are more effective, convenient and safe should be sought because of several factors such as increasing antimicrobial resistance rates, poor patient compliance because of long-term management, various side effects from the systemic use of antifungal medications and the unsuitability of drug treatment for some patients (such as pregnant women). Antimicrobial photodynamic therapy (aPDT), currently considered a treatment for infectious disease such as skin diseases and oral diseases (Cieplik et al, 2014a), has been developed in recent years into an effective treatment of T. rubrum infections (Baltazar et al, 2013, 2015). In type-II reactions, energy transfer excites the PS to a triplet state, resulting in the production of singlet oxygen, which is an extremely powerful oxidant with a very short lifetime that can react with several biomolecules, such as lipids and proteins (Nyman and Hynninen, 2004; Baltazar et al, 2013)
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