Mechanisms Of Chemically Induced Photosensitivity

工作总结：当紫外线或可见光与皮肤和眼睛中的内源性或外源性化学试剂相互作用时，可能导致光敏化。该过程可产生不期望的临床后果，例如光毒性（过度晒伤）、光过敏、光致癌性和/或光致突变性;或者其可具有有益效果，如在肿瘤光动力疗法（PDT）和用于银屑病的煤焦油、蒽林或8-甲氧基补骨脂素（PUVA）疗法中。本研究项目的目的是阐明光（紫外线或可见光）在存在或不存在光敏剂的情况下发挥其毒性作用的光化学机制。我们已经发现，UVA照射导致程序性细胞死亡（细胞凋亡）的皮肤细胞（角质形成细胞）暴露后24小时，如确定的DNA片段电泳和流式细胞术。胡桃醌是黑胡桃中的一种化学物质，是膳食补充剂、染发剂和胡桃油染色剂的一种成分。压碎的黑核桃壳有时被用于皮肤治疗真菌，细菌或病毒感染。胡桃醌目前正在接受国家毒理学计划的研究。我们发现胡桃醌对皮肤细胞（角质形成细胞）有毒，它将其转化为高活性和有毒的自由基。酮洛芬是一种广泛使用的非甾体抗炎药（NSAID），可引起光毒性和光过敏，在UVA照射后，可诱导高铁血红蛋白、氧合血红蛋白、肌红蛋白和红细胞中形成蛋白质自由基。我们已经测试了Tg.AC小鼠检测光致癌物（在光存在下导致皮肤癌的化学物质）的能力，并发现虽然这种转基因小鼠对UV/8-甲氧基补骨脂素有反应，但对UV/洛美沙星不敏感。

Summary of work: Photosensitization can result when UV or visible light interacts with endogenous or exogenous chemical agents in the skin and eyes. This process can produce undesirable clinical consequences, such as phototoxicity (exaggerated sunburn), photoallergy, photocarcinogenicity and/or photomutagenicity ; or it can have beneficial effects as in tumor photodynamic therapy (PDT) and coal tar, anthralin or 8-methoxypsoralen (PUVA) therapy for psoriasis. The objective of this research project is to elucidate the photochemical mechanisms whereby light (UV or visible) in the presence or absence of photosensitizers exerts its toxic effect. We have found that UVA irradiation caused programmed cell death (apoptosis) of skin cells (keratinocytes) 24 hours after exposure as determined by DNA fragmentation electrophoresis and flow cytometry. Juglone, a chemical present in black walnuts, is a component of dietary supplements, hair dyes and walnut oil stains. Crushed black walnut hulls are sometimes applied to the skin to treat fungal, bacterial or viral infections. Juglone is currently undergoing study by the National Toxicology Program. We have found that juglone is toxic to skin cells (keratinocytes), which convert it to highly reactive and toxic free radicals. Ketoprofen, a widely used non-steroidal anti-inflammatory drug (NSAID) that causes both phototoxicity and photoallergy, upon UVA irradiation, induced the formation of protein radicals in methemoglobin, oxyhemoglobin, myoglobin and red blood cells. We have tested the ability of the Tg.AC mouse to detect photocarcinogens (chemicals that cause skin cancer in the presence of light) and found that while this transgenic mouse responds to UV/8-methoxypsoralen, it is not sensitive to UV/lomefloxacin.