Nrf2基因在紫外线氧化应激与光老化中的作用研究进展

皮肤是直接暴露于日光紫外线照射的人类器官,紫外线的照射可导致皮肤的多种损伤,如光老化以及各种皮肤肿瘤。重复的细胞光损伤是导致皮肤光老化的基础。研究发现,紫外线辐射于人体皮肤发生氧化应激反应,产生的活性氧簇(reactive oxygen species,ROS)是导致细胞光损伤的主要原因。Nrf 2在很多与氧化应激反应相关的病变中均发挥重要的防御保护作用,Nrf2缺失或激活障碍会增加细胞对紫外线辐射的敏感性,而加重细胞的光损伤以及光老化。该文综述了Nrf2基因在光损伤以及光老化中的重要保护作用。     

与紫外线致皮肤损伤相关的部分信号通路研究进展

紫外线照射可使皮肤损伤,导致皮肤光老化或皮肤肿瘤.多个信号通路如Nrf2-Keap1-ARE、核因子κB、丝裂原活化蛋白激酶(MAPK)、磷脂酰肌醇-3激酶-丝氨酸/苏氨酸激酶-西罗莫司靶蛋白(PI3K-AKt-mTOR)信号通路等参与皮肤光老化和(或)皮肤肿瘤的发病.Nrf2信号通路在氧化应激状态下开启,有维持氧化还原平衡和参与细胞新陈代谢等作用.核因子κB信号通路的激活引起基质金属蛋白酶等水平上调,与皮肤老化和非黑素性皮肤癌有关.MAPK信号通路参与皮肤老化和皮肤肿瘤的进展.PI3K-AKt-mTOR信号通路主要与皮肤肿瘤相关.紫外线照射可诱导上述通路的活化,参与皮肤光老化或皮肤肿瘤的发生发展.对上述通路的进一步研究有望为抵御皮肤的光老化和皮肤肿瘤提供新的方法.     

皮肤光损伤与氧化应激研究进展

长期或大量紫外线照射后皮肤发生氧化应激,不仅从分子水平上改变了蛋白质、脂质、DNA等的结构和功能,同时于转录水平上激活丝裂原活化蛋白激酶通路、核转录因子通路、信号转导和转录激活因子通路,抑制核转录因子E2相关因子(Nrf)2通路等信号转导途径,引起皮肤细胞凋亡、细胞外基质降解,最终出现红斑、脱屑、皱纹、甚至肿瘤等光损伤表现。近年来针对氧化应激在光损伤发生及发展过程中的作用机制,以及光损伤的防治亦有较多新进展,该文从氧化应激角度对近年光损伤的发病机制和研究进展进行了回顾和总结,同时对其治疗前景进行展望。     

miRNA在皮肤紫外线光反应中的作用

日光的紫外线照射是一种常见的环境致癌因素.人类皮肤长期暴露于紫外线照射(特别是长波紫外线和中波紫外线)可引起多种伤害,如,红斑、色素沉着、免疫抑制、光老化和皮肤肿瘤等.为了避免这些损伤维持基因完整性,细胞自身具有多种保护机制,包括DNA修复、细胞周期阻滞和诱发凋亡等.研究表明,miRNA在紫外线照射引起的各种细胞反应中发挥了重要作用,与人类一系列的光照后皮肤损伤反应和疾病有关.     

Nrf2激活剂在黄褐斑治疗中的作用机制研究进展

核因子E2相关因子2(Nrf2)激活剂是目前发现的最重要的抗氧化剂之一,在皮肤科领域中,因它对活性氧物质(ROS)强大的拮抗作用,使它能对抗紫外线对皮肤的光老化损害,抑制黑色素的合成,对皮肤炎症及损伤有保护及修复作用,这些作用理论上可以在一定程度上阻遏黄褐斑的形成。目前对黄褐斑的药物及激光治疗,均有可能使皮肤产生物理或化学损伤,考虑到Nrf2信号通路激活对黄褐斑形成的潜在影响,Nrf2激活剂作为黄褐斑的补充及辅助治疗有相当的可行性。     

人角质形成细胞在皮肤光老化中的研究进展

光老化是长期紫外线照射导致的慢性炎性损伤,其中长波紫外线和中波紫外线红外线可诱导皮肤损伤引起光老化,但其发病机制尚未完全明确.人角质形成细胞是表皮中重要的细胞,也是紫外线敏感的靶细胞.近年来研究表明,人角质形成细胞在光老化的发生和发展中起重要作用.其中衰老自由基学说最为热门,抗老化的机制和药物、植物等方面的研究也多从此方面入手.     

Nrf2对体外三维皮肤光损伤模型的作用

目的探讨核转录相关因子E2(NF-E2-related factor 2,Nrf2)对体外三维(threedimensional,3D)皮肤光损伤模型的保护作用,为光损伤发病机制及治疗途径提供实验依据。方法取儿童包皮分离、培养原代角质形成细胞(keratinocytes,KC)和成纤维细胞(fibroblasts,FBs)。以Ⅰ型胶原为基质混合包埋FBs,接种KC以构建正常体外3D皮肤模型。然后将3D皮肤模型分为3组:正常组、实验组和对照组。其中实验组在接种KC前,通过慢病毒转染方式使KC过表达Nrf2,再行3D皮肤模型的构建。除正常组外,实验组和对照组均予以UVA和UVB混合单剂量照射,照射后继续进行培养。24h后观察各组皮肤病理组织学改变、细胞凋亡情况及Nrf2,SOD,MDA等氧化应激相关指标的变化。结果正常3D皮肤呈乳白色皮肤类似物。组织病理学上表皮结构清晰,细胞排列整齐,核大圆深染;真皮为淡紫红色胶原基质,FBs散在分布;凋亡细胞少见。UV照射后,对照组表皮细胞排列紊乱、部分肿胀坏死,核浓缩,真皮胶原降解和FBs减少;凋亡细胞明显增加(P0.05);Nrf2,SOD,GSH和CAT表达水平显著降低(P0.05),而MDA和ROS水平明显升高(P0.05)。但经过表达Nrf2后,实验组细胞整齐清晰,核无明显浓缩,KC轻度肿胀,FBs轻微减少,凋亡细胞显著减少(P0.05);Nrf2,SOD,GSH和CAT水平升高(P0.05),MDA和ROS降低(P0.05)。结论体外构建的3D皮肤光损伤模型接近人皮肤光损伤,可作为一理想的光损伤模型进行推广;KC过表达Nrf2可减轻UV对体外3D皮肤的损伤。     

核因子E2相关因子2信号通路及其在紫外线致皮肤蛋白氧化应激损伤中的作用

紫外线照射产生活性氧及自由基,与皮肤光老化、皮肤癌等皮肤光损伤疾病的发生相关.活性氧及自由基不仅通过攻击氨基酸主侧链等方式氧化蛋白质,而且能够激活丝裂原活化蛋白激酶产生基质金属蛋白酶,降解皮肤结缔组织中的胶原蛋白等蛋白质,使皮肤发生光损伤.核因子E2相关因子2信号通路是细胞氧化应激反应的核心调控机构,在应激条件下,激活核因子E2相关因子2,通过调节抗氧化酶类和Ⅱ相解毒酶基因的表达,清除过多的核因子E2相关因子2和自由基,抑制基质金属蛋白酶的分泌,保护蛋白质,增强机体抗氧化应激的能力,对皮肤起到保护作用.核因子E2相关因子2信号通路及其调控机制与皮肤蛋白氧化应激损伤间关系的深入研究,将有利于寻找蛋白氧化应激损伤导致的相关皮肤光损伤疾病新的有效的治疗防御措施.     

Nrf2激活剂防御紫外线致皮肤氧化应激损伤的研究

核因子E2相关因子2(Nrf2)激活剂作为一种新型的光保护剂,能有效抵御UV照射对皮肤的损伤。天然Nrf2激活剂可提取自茶多酚、姜黄素、莱菔硫烷、白藜芦醇、丹参酮、小白菊等,为以Nrf2信号通路为靶点治疗氧化应激损伤皮肤病提供了广阔前景。     

Nrf2-Keap1系统防御紫外线致皮肤光损伤的研究进展

紫外线照射是致皮肤光损伤的重要因素,与其可诱导产生过量的活性氧族有关。核转录相关因子是调节抗氧化应激反应的重要转录因子,Kelch样ECH联合蛋白1是其特异性受体,在紫外线照射等氧化应激情况下核转录相关因子被激活,并与Kelch样ECH联合蛋白1解离进入胞核,启动抗氧化反应元件调控的Ⅱ相酶及抗氧化酶基因的表达,防御紫外线照射所致皮肤光损伤。多种核转录相关因子激活剂对紫外线照射所致皮肤光损伤有潜在的防御作用。     

Heme oxygenase-1 protects human melanocytes from H2O2-induced oxidative stress via the Nrf2-ARE pathway

Oxidative stress caused by hydrogen peroxide (H(2)O(2)) leads to cell death and has been implicated in the pathogenesis of vitiligo. The nuclear factor E2-related factor 2 (Nrf2)-antioxidant response element (ARE), a major antioxidant pathway, regulates oxidative stress-related cytoprotective genes. We hypothesized that the Nrf2-ARE pathway protects human melanocytes from H(2)O(2)-induced oxidative damage through the induction of downstream antioxidative genes. Thus, we used Nrf2 short interfering RNA (siRNA) and pCMV6-XL5-Nrf2 to downregulate or upregulate Nrf2 expression in immortalized human melanocyte cell line PIG1. The melanocytes were then analyzed under different oxidative stress conditions for cell viability and apoptosis. Our study demonstrated that heme oxygenase-1 (HO-1) was the most induced antioxidant gene in PIG1 cells after treatment with H(2)O(2). Knockdown of Nrf2 or zinc protoporphyrin IX (ZnPP) treatment increased cell death caused by H(2)O(2) in melanocytes, but upregulation of Nrf2 or hemin treatment reduced cell death caused by H(2)O(2) in melanocytes. In addition, the H(2)O(2)-induced Nrf2-ARE/HO-1 pathway was confirmed in primary cultured human melanocytes by examining the expression and translocation of Nrf2 and HO-1. These data suggested that regulation of the Nrf2/HO-1 pathway can reduce H(2)O(2)-induced oxidative damage in human melanocytes. Our data demonstrate that HO-1 protects human melanocytes from oxidative damage via the Nrf2-ARE pathway.     

Irradiation of skin with visible light induces reactive oxygen species and matrix-degrading enzymes

Daily skin exposure to solar radiation causes cells to produce reactive oxygen species (ROS), which are a primary factor in skin damage. Although the contribution of the UV component to skin damage has been established, few studies have examined the effects of non-UV solar radiation on skin physiology. Solar radiation comprises <10% of UV, and thus the purpose of this study was to examine the physiological response of skin to visible light (400-700 nm). Irradiation of human skin equivalents with visible light induced production of ROS, proinflammatory cytokines, and matrix metalloproteinase (MMP)-1 expression. Commercially available sunscreens were found to have minimal effects on reducing visible light-induced ROS, suggesting that UVA/UVB sunscreens do not protect the skin from visible light-induced responses. Using clinical models to assess the generation of free radicals from oxidative stress, higher levels of free radical activity were found after visible light exposure. Pretreatment with a photostable UVA/UVB sunscreen containing an antioxidant combination significantly reduced the production of ROS, cytokines, and MMP expression in vitro, and decreased oxidative stress in human subjects after visible light irradiation. Taken together, these findings suggest that other portions of the solar spectrum aside from UV, particularly visible light, may also contribute to signs of premature photoaging in skin.     

Nrf2激活剂抗皮肤氧化损伤作用的研究进展

紫外线辐射除可引起皮肤急、慢性炎症反应外，也可启动皮肤内的氧化应激反应，增加活性氧水平。Nrf2-Keap1抗氧化系统具有通过调控细胞保护基因表达拮抗活性氧的作用。作为Nrf2激活剂，（-）－表没食子儿茶素-3－没食子酸酯、姜黄素和莱菔硫烷等天然抗氧化剂可通过直接清除自由基或通过间接增加内源性细胞抗氧化剂防御功能来抗氧化。其激活Nrf2的方式主要是通过不同化学结构分别与Nrf2、 Keap1结合，引发构型改变，继而启动抗氧化应激反应，抵御紫外线的氧化损伤。     

Gromwell (Lithospermum erythrorhizon) root extract protects against glycation and related inflammatory and oxidative stress while offering UV absorption capability

Glycation and advanced glycation end products (AGE) damage skin which is compounded by AGE‐induced oxidative stress and inflammation. Lip and facial skin could be susceptible to glycation damage as they are chronically stressed. As Gromwell (Lithospermum erythrorhizon) root (GR) has an extensive traditional medicine history that includes providing multiple skin benefits, our objective was to determine whether GR extract and its base naphthoquinone, shikonin, might protect skin by inhibiting glycation, increasing oxidative defenses, suppressing inflammatory responses and offering ultraviolet (UV) absorptive potential in lip and facial cosmetic matrices. We show GR extract and shikonin dose‐dependently inhibited glycation and enhanced oxidative defenses through nuclear factor erythroid 2‐related factor 2 (Nrf2)/antioxidant response element activation. Inflammatory targets, nuclear factor kappa‐light‐chain‐enhancer of activated B cells (NFκB) and tumor necrosis factor alpha, were suppressed by GR extract and shikonin. Glyoxalase 1 (GLO1) and glutathione synthesis genes were significantly upregulated by GR extract and shikonin. GR extract boosted higher wavelength UV absorption in select cosmetic matrices. Rationale for the use of GR extract and shikonin are supported by our research. By inhibiting glycation, modulating oxidative stress, suppressing inflammation and UV‐absorptive properties, GR extract and shikonin potentially offer multiple skin benefits.     

Melanocyte‐protective effect of afzelin is mediated by the Nrf2‐ARE signalling pathway via GSK‐3β inactivation

Vitiligo is an acquired condition characterized by depigmented, cutaneous lesions that result from the death of pigment‐producing cells, melanocytes. The occurrence of oxidative stress has been proposed as a pathogenetic mechanism for melanocyte degeneration in vitiligo. Therefore, in this study, we investigated the cytoprotective effects of afzelin against oxidative stress and its mechanism of action in human epidermal melanocytes. We found that afzelin significantly inhibited hydrogen peroxide‐induced cell death, cellular reactive oxygen species production and lipid peroxidation in melanocytes. In an antioxidant response element (ARE)‐luciferase reporter assay, afzelin increased ARE‐luciferase reporter activity in a concentration‐dependent manner. Consistently, the expression of antioxidant genes, including NF‐E2‐related factor 2 (Nrf2), haem oxygenase‐1 (HO‐1) and catalase, was enhanced by afzelin treatment. Nuclear translocation of Nrf2 also increased in response to afzelin treatment. In addition, the phosphorylation of glycogen synthase kinase‐3β (GSK‐3β) was induced by afzelin treatment. The enhancement of HO‐1 gene expression by afzelin treatment was reduced by Nrf2‐siRNA expression. Furthermore, we found that the expression of Nrf2‐siRNA significantly attenuated the cytoprotective effect of afzelin against hydrogen peroxide. These data suggest that the cytoprotective effects of afzelin against hydrogen peroxide may be mediated by Nrf2‐ARE signalling via GSK‐3β inactivation. Our data suggest the novel use of afzelin for the prevention of oxidative stress‐induced damage in melanocytes and its potential as a therapeutic agent for vitiligo.     

Flavonolignans from Silybum marianum moderate UVA-induced oxidative damage to HaCaT keratinocytes

BACKGROUND: UV radiation from sunlight is a very potent environmental risk factor in the pathogenesis of skin cancer. Exposure to UV light, especially the UVA part, provokes the generation of reactive oxygen species (ROS), which induce oxidative stress in exposed cells. Topical application of antioxidants is a successful strategy for protecting the skin against UV-caused oxidative damage. OBJECTIVE: In this study, silybin (SB) and 2,3-dehydrosilybin (DS) (1-50 micromol/l), flavonolignan components of Silybum marianum, were tested for their ability to moderate UVA-induced damage. METHODS: Human keratinocytes HaCaT were used as an appropriate experimental in vitro model, to monitor the effects of SB and DS on cell viability, proliferation, intracellular ATP and GSH level, ROS generation, membrane lipid peroxidation, caspase-3 activation and DNA damage. RESULTS: Application of the flavonolignans (1-50 micromol/l) led to an increase in cell viability of irradiated (20 J/cm(2)) HaCaT keratinocytes. SB and DS also suppressed intracellular ATP and GSH depletion, ROS production and peroxidation of membrane lipids. UVA-induced caspases-3 activity/activation was suppressed by treatment with SB and DS. Lower concentrations of both compounds (10 micromol/l) significantly reduced cellular DNA single strand break formation. CONCLUSION: Taken together, the results suggest that these flavonolignans suppress UVA-caused oxidative stress and may be useful in the treatment of UVA-induced skin damage.