Subject(s)
Anesthetics, Local/administration & dosage , Lidocaine/administration & dosage , Pain/prevention & control , Adolescent , Adult , Aged , Anesthetics, Local/adverse effects , Child , Cross-Over Studies , Female , Humans , Injections/methods , Lidocaine/adverse effects , Male , Middle Aged , Pain/chemically induced , Single-Blind Method , Young AdultABSTRACT
The high prevalence of drug resistance necessitates the development of novel antifungal agents against infections caused by opportunistic fungal pathogens, such as Candida albicans. Elucidation of apoptosis in yeast-like fungi may provide a basis for future therapies. In mammalian cells, photodynamic therapy (PDT) has been demonstrated to generate reactive oxygen species, leading to immediate oxidative modifications of biological molecules and resulting in apoptotic cell death. In this report, we assess the in vitro cytotoxicity and mechanism of PDT, using the photosensitizer Pc 4, in planktonic C. albicans. Confocal image analysis confirmed that Pc 4 localizes to cytosolic organelles, including mitochondria. A colony formation assay showed that 1.0 µM Pc 4 followed by light at 2.0 J cm(-2) reduced cell survival by 4 logs. XTT (2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxyanilide) assay revealed that Pc 4-PDT impaired fungal metabolic activity, which was confirmed using the FUN-1 (2-chloro-4-[2,3-dihydro-3-methyl-(benzo-1,3-thiazol-2-yl)-methylidene]-1-phenylquinolinium iodide) fluorescence probe. Furthermore, we observed changes in nuclear morphology characteristic of apoptosis, which were substantiated by increased externalization of phosphatidylserine and DNA fragmentation following Pc 4-PDT. These data indicate that Pc 4-PDT can induce apoptosis in C. albicans. Therefore, a better understanding of the process will be helpful, as PDT may become a useful treatment option for candidiasis.
Subject(s)
Antifungal Agents/pharmacology , Candida albicans/drug effects , Candida albicans/radiation effects , Candidiasis/drug therapy , Indoles/pharmacology , Organosilicon Compounds/pharmacology , Photochemotherapy/methods , Photosensitizing Agents/pharmacology , Antifungal Agents/chemistry , Apoptosis/drug effects , Apoptosis/radiation effects , Candida albicans/growth & development , Candidiasis/microbiology , Colony Count, Microbial , DNA Fragmentation/drug effects , DNA Fragmentation/radiation effects , Dose-Response Relationship, Drug , Fluorescence , Humans , Indoles/chemistry , Light , Microscopy, Confocal , Mitochondria/drug effects , Mitochondria/metabolism , Mitochondria/radiation effects , Organosilicon Compounds/chemistry , Phosphatidylserines/metabolism , Photosensitizing Agents/chemistry , Plankton/drug effects , Plankton/growth & development , Plankton/radiation effects , Reactive Oxygen Species/metabolism , Tetrazolium Salts/analysisABSTRACT
BACKGROUND: Photodynamic therapy (PDT) is a non-invasive treatment for non-melanoma skin cancer. However, PDT systems currently used clinically have limitations such as pain and superficial tissue penetration. The silicon phthalocyanine Pc 4 is a second-generation photosensitizer with peak absorption in the far red at 675 nm. OBJECTIVE: To assess the safety and tolerability of topically applied Pc 4 followed by red light (Pc 4-PDT) in treating cutaneous neoplasms. STUDY DESIGN/MATERIALS AND METHODS: Forty three adults with a diagnosis of neoplasms including actinic keratoses, Bowen's disease, squamous cell carcinoma, basal cell carcinoma, or mycosis fungoides were treated with a single administration of Pc 4-PDT and followed for 14 days. The study utilized a light and Pc 4 dose escalation design in sequential groups of three subjects each. RESULTS: Pc 4-PDT was well tolerated with no significant local toxicity or increased photosensitivity. It has promising biologic effects, particularly in mycosis fungoides where 14 of 35 subjects demonstrated a clinical response, which correlates with Pc 4-PDT-induced apoptosis, as measured by increased active caspase-3 in the treated skin lesions. CONCLUSIONS: Pc 4-PDT is a safe and tolerable treatment modality that effectively triggers apoptosis in cutaneous neoplasms such as mycosis fungoides.
