Methicillin-resistant Staphylococcus aureus (MRSA) has become the most important drug-resistant microbial pathogen in countries throughout the world. Morbidity and mortality due to MRSA infections continue to increase despite efforts to improve infection control measures and to develop new antibiotics. Therefore alternative antimicrobial strategies that do not give rise to development of resistance are urgently required. A group of therapeutic interventions has been developed in the field of photomedicine with the common theme that they rely on electromagnetic radiation with wavelengths between 200 and 1000 nm broadly called"light". These techniques all use simple absorption of photons by specific chromophores to deliver the killing blow to microbial cells while leaving the surrounding host mammalian cells relatively unharmed. Photodynamic inactivation uses dyes called photosensitizers (PS) that bind specifically to MRSA cells and not host cells, and generate reactive oxygen species including singlet oxygen and singlet oxygen upon illumination. Sophisticated molecular strategies to target the PS to MRSA cells have been designed. Ultraviolet C radiation can damage microbial DNA without unduly harming host DNA. Blue light can excite endogenous porphyrins and flavins in MRSA cells that are not present in host cells. Near-infrared lasers can interfere with microbial membrane potentials without raising the temperature of the tissue. Taken together these innovative approaches towards harnessing the power of light suggest that the ongoing threat of MRSA may eventually be defeated.

Methicillin-resistant Staphylococcus aureus (MRSA) has become the most important drug-resistant microbial pathogen in countries throughout the world. Morbidity and mortality due to MRSA infections continue to increase despite efforts to improve infection control measures and to develop new antibiotics. Therefore alternative antimicrobial strategies that do not give rise to development of resistance are urgently required. A group of therapeutic interventions has been developed in the field of photomedicine with the common theme that they rely on electromagnetic radiation with wavelengths between 200 and 1000 nm broadly called"light". These techniques all use simple absorption of photons by specific chromophores to deliver the killing blow to microbial cells while leaving the surrounding host mammalian cells relatively unharmed. Photodynamic inactivation uses dyes called photosensitizers (PS) that bind specifically to MRSA cells and not host cells, and generate reactive oxygen species including singlet oxygen and singlet oxygen upon illumination. Sophisticated molecular strategies to target the PS to MRSA cells have been designed. Ultraviolet C radiation can damage microbial DNA without unduly harming host DNA. Blue light can excite endogenous porphyrins and flavins in MRSA cells that are not present in host cells. Near-infrared lasers can interfere with microbial membrane potentials without raising the temperature of the tissue. Taken together these innovative approaches towards harnessing the power of light suggest that the ongoing threat of MRSA may eventually be defeated.

Hematoporphyrin monomethyl ether (HMME) is a novel and promising porphyrin-related photosensitizer for photodynamic therapy (PDT). This study aimed to investigate the efficacy and potential mechanism of HMME-PDT under irradiation of green light-emitting diode (LED) with wavelength of 530 ± 20 nm in treating human tongue squamous cell carcinoma Tca8113 cells in vitro. The HMME concentrations were 1.25, 2.5, and 5 μg/ml while the energy densities were 0.6, 1.2, 1.8, 2.4, and 3.0 J/cm(2). MTT assay demonstrated that HMME-PDT significantly inhibited the proliferation of Tca8113 cells, and the cytotoxicity was improved with increased HMME concentration and light intensity. The amount of cells decreased significantly and the morphology of cells changed drastically after HMME-PDT. Flow cytometry analysis revealed that HMME-PDT induced both apoptosis and necrosis, but apoptosis was the main form of cell death. Apoptotic morphology was confirmed by Hoechst 33342 staining. Laser scanning confocal microscopy observation showed that HMME was mainly localized in mitochondria. The production of intracellular reactive oxygen species increased remarkably after PDT treatment, and both sodium azide (the singlet oxygen quencher) and D-mannitol (the hydroxyl radical scavenger) could protect Tca8113 cells from death induced by HMME-PDT. Additionally, the activity of caspase-3 also increased markedly in treated groups, and the cell death could be rescued by a reversible inhibitor (Ac-DEVD-CHO) of caspase-3. These results demonstrated that HMME combined with green LED significantly induced apoptosis of Tca8113 cells, suggesting that HMME-PDT using green LED might be a potential therapeutic strategy for human tongue squamous cell carcinoma.

Hematoporphyrin monomethyl ether (HMME) is a novel and promising porphyrin-related photosensitizer for photodynamic therapy (PDT). This study aimed to investigate the efficacy and potential mechanism of HMME-PDT under irradiation of green light-emitting diode (LED) with wavelength of 530 ± 20 nm in treating human tongue squamous cell carcinoma Tca8113 cells in vitro. The HMME concentrations were 1.25, 2.5, and 5 μg/ml while the energy densities were 0.6, 1.2, 1.8, 2.4, and 3.0 J/cm(2). MTT assay demonstrated that HMME-PDT significantly inhibited the proliferation of Tca8113 cells, and the cytotoxicity was improved with increased HMME concentration and light intensity. The amount of cells decreased significantly and the morphology of cells changed drastically after HMME-PDT. Flow cytometry analysis revealed that HMME-PDT induced both apoptosis and necrosis, but apoptosis was the main form of cell death. Apoptotic morphology was confirmed by Hoechst 33342 staining. Laser scanning confocal microscopy observation showed that HMME was mainly localized in mitochondria. The production of intracellular reactive oxygen species increased remarkably after PDT treatment, and both sodium azide (the singlet oxygen quencher) and D-mannitol (the hydroxyl radical scavenger) could protect Tca8113 cells from death induced by HMME-PDT. Additionally, the activity of caspase-3 also increased markedly in treated groups, and the cell death could be rescued by a reversible inhibitor (Ac-DEVD-CHO) of caspase-3. These results demonstrated that HMME combined with green LED significantly induced apoptosis of Tca8113 cells, suggesting that HMME-PDT using green LED might be a potential therapeutic strategy for human tongue squamous cell carcinoma.

We describe the first local use of hypericin as photosensitizer for photodynamic therapy in a patient with recurrent malignant mesothelioma. Hypericin is a polycyclic quinone, which has been shown to possess in vivo and in vitro antiretroviral and photosensitizing activity; moreover, it is used in depressive disorders. The semiquinone radical, singlet oxygen, and superoxide anion radical are reported to be the toxic agents in hypericin phototherapy. Our first experience with locally applied hypericin in a superficial tumor-plate was performed 8 weeks after the systemic administration of hematoporphyrin derivatives. For tumor light illumination we used an argon pumped dye laser tuned to 632 nm. Owing to satisfactory results, we repeated the same therapy 4 weeks later- and no therapeutic effect was noted. Following this, we proved the interstitial application of HPD and the combination of interstitial HDP and superficially applied hypericin. The subsequent light illumination 6 hours later had no efficacy in the HDP-photosensitized area but there was tumor destruction in the field with both administered photosensitizers. Our first experience suggests a potentiation of two photosensitizers: hematoporphyrin derivatives and hypericin.

Photodynamic therapy (PDT) involves the administration of a photosensitizer followed by light irradiation with a specific wavelength, giving rise to irreversible tissue destruction. Hypericin, a herbal extract derived from Hypericum perforatum or St. John's Wort, has minimal toxicity but exhibits potent photo-damaging effects in the presence of light. Hypericin is known to generate a high yield of singlet oxygen and other reactive oxygen species that are associated with photo-oxidative cellular damage. The application of PDT with hypericin for the treatment of cancers such as recurrent mesothelioma and skin cancer has been validated in clinical trials. This mini-review focuses on the investigative studies of hypericin as a potential photodynamic agent in the treatment of nasopharyngeal cancer (NPC) in in vitro and in vivo models. NPC is an enigmatic tumor with a multifactorial etiology and a high incidence in the populations of Southern China.

OBJECTIVE:To evaluate the photodynamic therapy (PDT) against multi-antibiotic-resistant Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S.epidermidis) obtained from patients with chronic rhinosinusitis(CRS).

METHODS:Forty-five CRS patients who had been given medical treatment but still needed endoscopic surgery were included in this study. The mucus from middle meatus was collected from these patients during surgery, followed by separation of S. aureus and S. epidermidis and drug sensitive test. The strains which could form biofilm were selected. Light emitting diode (LED) array with a major wavelength of (633±10)nm was used as light source and 5-Aminolevulinic acid (ALA) was used as photosensitizer in this PDT experiment. The safe range of LED dose and ALA concentration which were not toxic to bacteria by themselves were confirmed, and then did PDT experiment on S. aureus and S. epidermidis. The data of bacterial colony forming unit were transformed to lgCFU before statistical analysis.The Graph Pad Prism 5 software was used to analyzed the data.

RESULTS:Thirteen S. aureus and 16 S. epidermidis were included in this experiment(from 45 patients), all of them were multi-antibiotic-resistant bacteria, and four of S. aureus and five of S. epidermidis could form biofilm in each group. In planktonic S. aureus experiment, the mean lgCFU was 8.32±0.31 in control group whereas the experiment group was 6.47±0.67 (t=9.01, P<0.01), and in planktonic S. epidermidis experiment the final data was 8.34±0.20 (control group) and 6.97±0.59 (experiment group) (t=8.84, P<0.01). In biofilm S. aureus experiment, the mean lgCFU was 8.68±0.05 (control group), 6.90±0.96(experiment group)(t=3.68, P<0.05); and in biofilm S. epidermidis experiment the data was 8.67±0.05(control group), 7.29±0.61(experiment group, t=5.07, P<0.01).

CONCLUSION:Our results demonstrated that ALA-mediated PDT on multi-antibiotic-resistant S. aureus and S. epidermidis from CRS patients was effective in vitro. Additional work defining if the PDT treatment would damage the nasal mucosa and further checking the effectiveness of PDT in vivo is still needed.

BACKGROUND/AIMS: Photodynamic therapy (PDT) has been adapted to the endoscopic treatment of digestive cancer, but its indications and efficacy remain uncertain. The aim of this study was to assess its feasibility in the curative treatment of small esophageal tumors. METHODS: From 1983 to 1991, PDT was used to treat 123 patients with esophageal cancer who were recommended for nonsurgical treatment of squamous cell carcinoma (n = 104) and adenocarcinoma (n = 19). Endoscopic ultrasonography (EUS) was performed in 88 patients; 61 were staged uT1 and 27 were staged uT2. A hematoporphyrin derivative was injected 72 hours before laser irradiation with a 630-nm dye laser. PDT was applied alone in 56 patients and as part of a multimodal protocol in the 67 others. RESULTS: The complete response rate at 6 months was 87%. The 5-year survival rate was 25% +/- 6%, and the 5-year disease-specific survival rate was 74% +/- 5%. The complete response rate and survival rate were not different (1) between the PDT alone and the PDT multimodal treatment groups, (2) between the adenocarcinoma and squamous cell carcinoma groups, and (3) between the uT1 and uT2 EUS groups. PDT-related complications were esophageal stenosis (n = 43) and cutaneous photosensitization (n = 16). CONCLUSIONS: In patients with small esophageal tumors who pose high surgical risk, photodynamic therapy is an effective treatment.

BACKGROUND:Diabetic foot ulcers (DFU) represent a significant complication of diabetes mellitus (DM). DFU affect one in four patients with DM and treatments of DFU are limited and challenging. The management of DFU remains a significant healthcare and socioeconomic burden ($245 billion). There is a wide range of advanced therapies for DFU, but these are costly and have demonstrated only minimal efficacy in limited published studies. An emerging treatment modality to improve DFU and optimize wound healing is the use of low-level light therapy (LLLT). LLLT involves the use of light in the form of low-level or low-power laser or light emitting diodes to alter biochemical pathways, which may result in changes to cell shape, cell migration, and cell signaling.

OBJECTIVE:To review published clinical experiences (case series and case reports) using LLLT for treatment of DFU, and provide evidence-based recommendations and future directions on the potential of LLLT as a therapeutic modality for DFU.

METHODS AND MATERIALS:On January 16, 2016 we searched the published literature using databases: PubMed, EMBASE, CINAHL, and Web of Science with key terms:"diabetic foot"AND ("low level laser therapy"OR"low level light therapy"OR"LLLT"OR"light emitting diode"OR"phototherapy"OR"laser").

RESULTS:After screening of titles, abstracts and/or full-text, 7 original articles were suitable in our review. Our review contains 5 case series and 2 case reports that evaluated LLLT for treatment of DFU, and all reviewed studies have shown positive improvement of DFU using LLLT with no adverse events, albeit with limitations that may be minimized with future RCTs.

CONCLUSIONS:LLLT is an emerging and promising treatment modality to current alternatives that are costly and have shown limited success. Based upon the published evidence, we envision additional research may allow for stronger recommendation with LLLT for treatment of DFU.

J Drugs Dermatol.2016;15(7):843-848.

METHODS:RESULTS:CONCLUSIONS:

Systemic inflammation is closely related to the development of insulin resistance and type-2 diabetes, since the activation of pro-inflammatory pathways leads to inhibition of insulin signaling. Although photobiomodulation (PBM) has proven beneficial effects on the treatment of inflammatory disorders, the phototherapeutic approach to manage the chronic inflammatory component of obesity and hyperglycemia had never been explored. In this work, obese and hyperglycemic mice are treated with PBM, and their body mass, glycemia and inflammatory infiltrate of abdominal adipose tissue are evaluated. During four weeks, irradiated animals are exposed to six irradiation sessions using an 843 nm LED (5.7 J cm(-2) at 19 mW cm(-2) per session). Non-irradiated control animals display inflammatory areas almost five times greater than the treated group (p < 0.001). This result on inflammatory infiltrate may have caused impacts on the significant lower blood glucose level from irradiated animals (p = 0.04), twenty-four hours after the last irradiation session. PBM on obese and hyperglycemic mice reduced five times the areas of inflammatory infiltrate within abdominal adipose tissue (a, b), whereas dense inflammatory regions were a common finding amidst non-irradiated animals (c). The asterisks on (c) correspond to the inflammatory infiltrate permeating adipocytes.

Systemic inflammation is closely related to the development of insulin resistance and type-2 diabetes, since the activation of pro-inflammatory pathways leads to inhibition of insulin signaling. Although photobiomodulation (PBM) has proven beneficial effects on the treatment of inflammatory disorders, the phototherapeutic approach to manage the chronic inflammatory component of obesity and hyperglycemia had never been explored. In this work, obese and hyperglycemic mice are treated with PBM, and their body mass, glycemia and inflammatory infiltrate of abdominal adipose tissue are evaluated. During four weeks, irradiated animals are exposed to six irradiation sessions using an 843 nm LED (5.7 J cm(-2) at 19 mW cm(-2) per session). Non-irradiated control animals display inflammatory areas almost five times greater than the treated group (p < 0.001). This result on inflammatory infiltrate may have caused impacts on the significant lower blood glucose level from irradiated animals (p = 0.04), twenty-four hours after the last irradiation session. PBM on obese and hyperglycemic mice reduced five times the areas of inflammatory infiltrate within abdominal adipose tissue (a, b), whereas dense inflammatory regions were a common finding amidst non-irradiated animals (c). The asterisks on (c) correspond to the inflammatory infiltrate permeating adipocytes.

INTRODUCTION:Oral premalignant lesions are conditions having high potential tendency for transformation into malignancy. The use of a conservative and effective treatment modality is one of the best strategies for cancer prevention. Photodynamic therapy (PDT) is a non-invasive method for topical and selective treatment of oral precancerous lesions. The present study was taken up to determine the efficacy of PDT in oral precancerous lesions.

METHODS:The study consisted 13 patients with 24 oral leukoplakia (OL) lesions and 8 with 20 oral lichen planus (OLP) lesions, divided into control and study groups. These lesions were affecting various intraoral sites, the buccal mucosa being the most common site followed by tongue and gingiva. The treatment regimen of PDT included 98% 5-aminolevulinic acid (5-ALA) which is topical applied and irradiated with light emitting diode (LED) of 420 nm wavelengths at several sessions.

RESULTS:In OL 16.6% of cases showed complete response, 66.6% partial response and 16.6% no response of the lesions to the treatment. In OLP 80% and 20% of the lesions showed partial and no response respectively. The differences with control groups for OL + OLP were found to be significant (P<0.001).

CONCLUSION:Based on the results of the present study, we can conclude that PDT appears to be a feasible alternative to conventional therapy for oral premalignant lesions.

INTRODUCTION:Oral premalignant lesions are conditions having high potential tendency for transformation into malignancy. The use of a conservative and effective treatment modality is one of the best strategies for cancer prevention. Photodynamic therapy (PDT) is a non-invasive method for topical and selective treatment of oral precancerous lesions. The present study was taken up to determine the efficacy of PDT in oral precancerous lesions.

METHODS:The study consisted 13 patients with 24 oral leukoplakia (OL) lesions and 8 with 20 oral lichen planus (OLP) lesions, divided into control and study groups. These lesions were affecting various intraoral sites, the buccal mucosa being the most common site followed by tongue and gingiva. The treatment regimen of PDT included 98% 5-aminolevulinic acid (5-ALA) which is topical applied and irradiated with light emitting diode (LED) of 420 nm wavelengths at several sessions.

RESULTS:In OL 16.6% of cases showed complete response, 66.6% partial response and 16.6% no response of the lesions to the treatment. In OLP 80% and 20% of the lesions showed partial and no response respectively. The differences with control groups for OL + OLP were found to be significant (P<0.001).

CONCLUSION:Based on the results of the present study, we can conclude that PDT appears to be a feasible alternative to conventional therapy for oral premalignant lesions.

OBJECTIVE:Photodynamic therapy (PDT) has been used for superficial neoplasms and its usage has been recently extended to deeper lesions. The purpose of this study was to observe whether or not PDT can cure breast cancer in the solid tumor model, and to define the critical point of laser amount for killing the cancer cells.

METHODS:Twenty four BALB/c mouse models with subcutaneous EMT6 mammary carcinomas were prepared. Mice were divided into eight groups depending on the amount of illumination, and the tumor size was between 8 mm and 10 mm. We began by peritoneal infiltration with a photosensitizer 48 hours prior to applying the laser light, and then we applied a non-thermal laser light. The energy was from 350 J/cm(2) to 30 J/cm(2) to the cancer.

RESULTS:Regardless of the tumor size from 8 mm to 10 mm, all mice apparently showed positive results via PDT. We also did not find any recurrence over 90 J/cm(2). In all models, the color of the breast cancer lesions began to vary to dark on 2 days post PDT and the tumor regression began simultaneously. Also, we confirmed the complete regression of the breast cancer 21 days after PDT.

CONCLUSION:We confirmed that PDT may treat breast cancers that are sized less 10 mm in mouse models. The moderate energy to destruct the breast cancer cells may be 90 J/cm(2). Therefore, we can expcect that PDT may be utilized to treat breast cancer, but we need more experience, skills and processing for clinical trials.

Melanoma is the most aggressive and lethal form of skin cancer, responsible for>80% of deaths. Standard treatments for late-stage melanoma usually present poor results, leading to life-threatening side effects and low overall survival. Thus, it is necessary to rethink treatment strategies and design new tools for the treatment of this disease. On that ground, we hereby report the use of acai oil in nanoemulsion (NanoA) as a novel photosensitizer for photodynamic therapy (PDT) used to treat melanoma in in vitro and in vivo experimental models. NIH/3T3 normal cells and B16F10 melanoma cell lines were treated with PDT and presented 85% cell death for melanoma cells, while maintaining high viability in normal cells. Flow cytometry indicated that cell death occurred by late apoptosis/necrosis. Tumor bearing C57BL/6 mice treated five times with PDT using acai oil in nanoemulsion showed tumor volume reduction of 82% in comparison to control/tumor group. Necrotic tissue per tumor area reached its highest value in PDT-treated mice, supporting PDT efficacy. Overall, acai oil in nanoemulsion was an effective photosensitizer, representing a promising source of new photosensitizing molecules for PDT treatment of melanoma, a tumor with an inherent tendency to be refractory for this type of therapy.

Species of the fungal genus Candida, can cause oral candidiasis especially in immunosuppressed patients. Many studies have investigated the use of photodynamic therapy (PDT) to kill fungi in vitro, but this approach has seldom been reported in animal models of infection. This study investigated the effects of PDT on Candida albicans as biofilms grown in vitro and also in an immunosuppressed mouse model of oral candidiasis infection. We used a luciferase-expressing strain that allowed non-invasive monitoring of the infection by bioluminescence imaging. The phenothiazinium salts, methylene blue (MB) and new methylene blue (NMB) were used as photosensitizers (PS), combined or not with potassium iodide (KI), and red laser (660nm) at four different light doses (10J, 20J, 40J and 60J). The best in vitro log reduction of CFU/ml on biofilm grown cells was: MB plus KI with 40J (2.31 log; p<0.001); and NMB without KI with 60J (1.77 log; p<0.001). These conditions were chosen for treating the in vivo model of oral Candida infection. After 5days of treatment the disease was practically eradicated, especially using MB plus KI with 40J. This study suggests that KI can potentiate PDT of fungal infection using MB (but not NMB) and could be a promising new approach for the treatment of oral candidiasis.

BACKGROUND/AIM:Curcumin (CUM) is a promising agent in complementary oncology. The present study analyzed the photoactive properties of curcumin on pediatric epithelial liver tumor cell lines.

MATERIALS AND METHODS:Hepatoblastoma cell lines (HuH6, HepT1) and hepatocellular carcinoma cell lines (HepG2, HC-AFW1) were treated with curcumin and exposed to blue light (phototherapy, 480 nm, 300 W). Cell viability (MTT tests), cellular oxidative stress (production of reactive oxygen species (ROS)) and cellular uptake/degradation of curcumin were analyzed.

RESULTS:Significant loss of viability resulted from 24-48 h incubation with curcumin. With photodynamic therapy (PDT), even short time incubation (1 h) with curcumin resulted in significantly lower half maximal inhibitory concentration (IC50) (p<0.001, two-way ANOVA). Significant ROS production was observed with PDT and curcumin.

CONCLUSION:Phototherapy strongly enhances the anticancer properties of curcumin in pediatric solid liver tumors in vitro.

BACKGROUND/AIM:Curcumin (CUM) is a promising agent in complementary oncology. The present study analyzed the photoactive properties of curcumin on pediatric epithelial liver tumor cell lines.

MATERIALS AND METHODS:Hepatoblastoma cell lines (HuH6, HepT1) and hepatocellular carcinoma cell lines (HepG2, HC-AFW1) were treated with curcumin and exposed to blue light (phototherapy, 480 nm, 300 W). Cell viability (MTT tests), cellular oxidative stress (production of reactive oxygen species (ROS)) and cellular uptake/degradation of curcumin were analyzed.

RESULTS:Significant loss of viability resulted from 24-48 h incubation with curcumin. With photodynamic therapy (PDT), even short time incubation (1 h) with curcumin resulted in significantly lower half maximal inhibitory concentration (IC50) (p<0.001, two-way ANOVA). Significant ROS production was observed with PDT and curcumin.

CONCLUSION:Phototherapy strongly enhances the anticancer properties of curcumin in pediatric solid liver tumors in vitro.