Juliana Cabrini Carmello

Introduction the use of light emitting diodes (LED) in domestic and public vias have increased in the last 20 years. In addition, the LED light has been used as a light source for medical applications. Objective since humans are increasingly exposed to LEDs, there is an urgency to investigate the possible biological effects on tissues caused by this exposure. So, researchers have been focused their investigations in the application of this light in the health field. Material and method in this review, a search in important databases was performed on the biological effects caused after application of different LED light protocols in in vitro and in vivo studies. Result although most published papers have shown positive results, some of them reported negative biological effects of light LEDs technology on humans’ cells/tissues. Conclusion therefore, the comprehension of the biological effects caused by light LEDs will provide a better assessment of the risks involved using this technology.

Objectives: The present study evaluated the action of LED light sources at different wavelengths on cell viability, lipid peroxidation, and Top I and II gene expression of Candida albicans and Staphylococcus aureus. Methods: Planktonic cultures were subjected of illumination, and the post- irradiation cell proliferation was assessed by quantification of metabolic mitochondrial activity. Next, the response of the microorganisms to the treatments was assessed. Results: Cell viability (CFU/mL) reduction occurred only for the fungus by 0.5 and 0.6 log10 using yellow LED 0.1 and 10 J/cm2, respectively. For S. aureus, none of the evaluated wavelengths reduced cell viability versus the control. Production of intracellular ROS occurred in all tested light doses and wavelengths, except for 0.1 J/cm2 of yellow LED for both microorganisms. Lipid peroxidation occurred only for C. albicans after exposure to 10 J/cm2 of yellow LED, 15 and 50 J/cm2 of blue LED, and 300 and 500 lux of white LED. The two doses of blue light and red light decreased the expression of TOP II of C. albicans and TOP I of S. aureus. The two doses of yellow and white lights promoted an increase in the expression of the genes that encode TOP II and TOP I for both species. Conclusion: The results demonstrated that the mechanisms of action of white LEDs and at blue (455 nm), red (660 nm) and yellow (590 nm) wavelengths seem to be related to the production of ROS, lipid peroxidation, and DNA damage.

Microorganisms that compose the oral microbiota maintain complex interactions with each other, especially pathogens related to periodontal disease. It is possible to characterize the etiology of this multifactorial and polymicrobial disease by the accumulation of biofilms formed in the supra- and subgingival environments associated to the immunological response and the susceptibility of the host, being responsible for a large part of the dental loss especially in the adult phase. Periodontal treatment has been carried out mainly by scaling and root planing. This therapy is limited due to the difficult access in some areas of the teeth, impairing the removal of biofilms. So, this chapter will focus on the composition and formation of the biofilm as well as the host’s immune response to periodontopathogenic microorganisms. Additionally, the therapeutic challenges and the treatments that are currently being studied in order to eliminate this biofilm, such as antimicrobial phototherapy, will be discussed.

Background: It has been demonstrated that azole-resistant strains of Candida albicans have a greater resistance to antimicrobial photodynamic therapy (aPDT) when compared to their more susceptible counterparts. For this reason, the present study evaluated the efficacy of aPDT, together with nystatin (NYS), in the treatment of oral candidiasis in vivo. Methods: Mice were infected with fluconazole-resistant C. albicans (ATCC 96901). To perform the combined therapy, aPDT, mediated by Photodithazine (PDZ) and LED light, was used together with NYS. The efficacy of the treatments was evaluated by microbiological, macroscopic, histopathological and Confocal Scanning Laser Microscopy analyses of the lesions. The expression of p21 and p53, proteins associated with cell death, from the tongues of mice, was also performed. Results: The combined therapy reduced the fungal viability by around 2.6 log₁₀ and decreased the oral lesions and the inflammatory reaction. Additionally, it stimulated the production of p53 and p21. Conclusions: The combined therapy is a promising alternative treatment for oral candidiasis induced by C. albicans resistant to fluconazole.

This study evaluated the efficacy of antimicrobial Photodynamic Therapy (aPDT) against fluconazole-resistant Candida albicans in a murine model of oral candidosis. Mice were inoculated with two clinical isolates (R10, R15) and one reference strain (ATCC) of resistant C. albicans to produce oral candidosis. After inoculation, aPDT mediated by Photodithazine® (PDZ) and LED light was performed. The use of PDZ or light only was also investigated. Additional animals were treated with Nystatin (NYS). Untreated or healthy mice were also evaluated. Microbiological evaluation was performed by recovering C. albicans from the tongue via colony-forming units. Animals were killed 24 hours after treatments, and the tongues were removed for histological analysis. Data were analyzed by one-way ANOVA and Tukey test (P < .05). The results demonstrated that all strains showed the same behavior after aPDT and NYS treatment. A significant reduction in C. albicans viability was achieved after both treatments for R15 and ATCC. No significant reduction was verified for C. albicans R10 submitted to aPDT or NYS. The histological analysis revealed that aPDT did not cause side effects on tissues. aPDT was effective for inactivation of two fluconazole-resistant C. albicans of the three strains evaluated.

Antimicrobial photodynamic therapy (aPDT) has been proposed as an alternative method for oral candidiasis (OC), while nanocarriers have been used to improve the water solubility of curcumin (CUR). The aim of this study is to encapsulate CUR in polymeric nanoparticles (NPs) and to evaluate its photodynamic effects on a murine model of OC. Anionic and cationic CUR-NP is synthesized using poly-lactic acid and dextran sulfate and then characterized. Female mice are immunosuppressed and inoculated with Candida albicans (Ca) to induce OC. aPDT is performed by applying CUR-NP or free CUR on the dorsum of the tongue, followed by blue light irradiation for five consecutive days. Nystatin is used as positive control. Afterward, Ca are recovered and cultivated. Animals are euthanized for histological, immunohistochemical, and DNA damage evaluation. Encapsulation in NP improves the water solubility of CUR. Nystatin shows the highest reduction of Ca, followed by aPDT mediated by free CUR, which results in immunolabelling of cytokeratins closer to those observed for healthy animals. Anionic CUR-NP does not show antifungal effect, and cationic CUR-NP reduces Ca even in the absence of light. DNA damage is associated with Ca infection. Consecutive aPDT application is a safe treatment for OC.

Correction for ‘In vivo evaluation of photodynamic inactivation using Photodithazine® against Candida albicans’ by J. C. Carmello, et al., Photochem. Photobiol. Sci., 2015, 14, 1319–1328.