Sunscreens and vitamin E provide some protection to the skin immune system from solar-simulated UV radiation

Previous studies have indicated that sunscreens designed to protect from erythema do not adequately prevent immunosuppression. Mice were irradiated with suberythemal doses of solar-simulated ultraviolet radiation (ssUVR) to assess the immunoprotective ability of sunscreens. Whereas C3H/HeJ and BALB/c mice had similar sensitivities to ssUVR-induced inflammation, C3H/HeJ mice were more sensitive to ssUVR-induced immunosuppression. Octyl dimethyl- p -aminobenzoic acid did not protect from immunosuppression and, thus, had an immune protection factor (IPF) of 1. 2-Ethylhexyl- p -methoxycinnamate and microfine titanium dioxide provided limited protection, both having IPF values of 1.127. Immune protection by the sunscreens appeared to be dependent upon absorption of UVA as well as UVB, and was much less than predicted from the sun protection factor. Vitamin E, and inhibitor of lipid peroxidation, also protected the immune system, with an IPF of 1.2, indicating that oxidation of lipids is involved in UVR-induced immunosuppression, and that it should be possible to develop sunscreens which protect the immune system.     

The green tea polyphenol (-)-epigallocatechin gallate and green tea can protect human cellular DNA from ultraviolet and visible radiation-induced damage

BACKGROUND: Antioxidant compounds in green tea may be able to protect against skin carcinogenesis and it is of interest to investigate the mechanisms involved. A study was therefore conducted to determine whether the isolated green tea polyphenol (-)-epigallocatechin gallate (EGCG) could prevent ultraviolet radiation (UVR)-induced DNA damage in cultured human cells. This work was then extended to investigate whether drinking green tea could afford any UVR protection to human peripheral blood cells collected after tea ingestion. METHODS: The alkaline comet assay was used to compare the DNA damage induced by UVR in cultured human cells with and without the presence of EGCG. The same assay technique was then employed to assess UVR-induced DNA damage in peripheral leucocytes isolated from 10 adult human volunteers before and after drinking 540 ml of green tea. RESULTS: Initial trials found that EGCG afforded concentration-dependent photoprotection to cultured human cells with a maximal activity at a culture concentration of 250 microM. The cells types tested (lung fibroblasts, skin fibroblasts and epidermal keratinocytes) demonstrated varying susceptibility to the UVR insult provided. The in vivo trials of green tea also demonstrated a photoprotective effect, with samples of peripheral blood cells taken after green tea consumption showing lower levels of DNA damage than those taken prior to ingestion when exposed to 12 min ultraviolet A (UVA) radiation. CONCLUSION: The studies showed that green tea and/or some constituents can offer some protection against UV-induced DNA damage in human cell cultures and also in human peripheral blood samples taken post-tea ingestion.     

Consumption of functional fermented milk containing borage oil, green tea and vitamin E enhances skin barrier function

Abstract:  As emerging studies show that skin functioning can be improved with orally imbibed ingredients, we decided to investigate a mixture of borage oil, catechins, vitamin E and probiotics, all known for their reported effects on epidermal function, in a fermented dairy product, for the first time. Gamma-linolenic acid (GLA) and catechins bioavailability and their effects on skin functionality have not been previously investigated from a fermented dairy product. Firstly, we assessed the bioavailability of GLA and catechins mixed in a fermented dairy matrix by measuring their levels in chylomicrons and plasma samples respectively. For the GLA contained in the dairy matrix, the area under the curve and time for maximal absorption were significantly different to the same kinetic parameters compared with absorption from the free oil indicating improved oral bioavailability. However, the overall absorption of catechins over the 6-h period was identical for both product forms. These results were sufficiently promising to warrant a 24 week skin nutrition intervention study in female volunteers having dry and sensitive skin. The product improved stratum corneum barrier function compared with a control product as early as 6 weeks after the consumption which continued throughout the rest of the study. The reduction in transepidermal water loss relative to control was maintained throughout the trial despite seasonal changes. Moreover, as a result of the enhanced bioavailability, a much greater effect on skin barrier function occurred than reported previously for the individual ingredients. Nevertheless, body mass index significantly influenced various outcome measurements of this study.     

Phenotype of Langerhans cells in human afferent skin lymph derived from allergic contact dermatitis

Abstract By means of microsurgical lymph cannulation human skin lymph derived from the late phase of an elicitation reaction to diphenylcyclopropenone was sampled. Cells were isolated by centrifugation and then treated with mouse anti-CDl a mnonoclonal antibodies and sheep antimouse antibody-coated Dynabeads. Ultrastructural and immunocytochemical analyses revlaled anti-CDl a/Dynabead-rosetted CDl a- and protein S-100-positive cells which did not express monocyte surface markers, but surface antigens such as HLA-DR, ICAM-I and, in part, LFA-3. In comparison to freshly prepared human epidermal Langerhns cells (LC), a large fraction of these cells contained no or markedly fewer Birbeck granules and exhibited extensive ruffling of the surface. These data suggest that the phenotype of LC in skin lymph derived from the elicitation phase of allergic contact dermatitis is similar to LC cultured in vitro. In the functional concept or LC or our time, these cells correspond to the dendritic cells designated as “veiled”.     

Effects of solar-simulated radiation dose fractionation on CD1a+ Langerhans cells and CD11b+ macrophages in human skin

BACKGROUND: There are few human studies investigating the immunosuppressive effects of exposure to solar-simulated radiation (SSR) and its relationship with sunburn/erythema, and few comparative data on the importance of SSR exposure regimens. OBJECTIVES: To evaluate whether SSR-induced erythema is a reliable end-point for assessing damage to antigen-presenting cells (APCs) in human skin. METHODS: We compared the relationship between SSR-induced erythema and alterations in epidermal CD1a+ Langerhans cells (LCs) and CD11b+ macrophages in human volunteers after single exposures to 0, 0.5, 1, 2 or 3 minimal erythema doses (MED). We also investigated whether SSR exposure leads to an accumulation or accommodation of the same end-points by comparing the effects of a relatively low cumulative SSR dose (3 MED) given in varying daily dose fractions (4 x 0.75 MED, 2 x 1.5 MED and 1 x 3 MED). RESULTS: Single SSR exposures induced a dose-dependent increase in erythema. CD1a+ LCs remaining in the irradiated epidermis showed a dose-dependent increase in cell size and altered morphology. Significant depletion of CD1a+ LCs and presence of CD11b+ macrophages only occurred in sites irradiated with 2 MED and 3 MED. Dose fractionation had no effect on the final erythemal response but the 4 x 0.75 MED and 1 x 3 MED protocols were better tolerated than 2 x 1.5 MED for alterations in CD1a+ LC and CD11b+ cell numbers. In contrast, dose fractionation protected against alterations in CD1a+ LC morphology or cell size. CONCLUSIONS: We found that erythema is a poor indicator of alterations in epidermal APCs and that dose fractionation is an important parameter in the immunological effects of ultraviolet radiation.     

表没食子儿茶酚没食子酸酯对紫外线辐射诱导角质形成细胞产生IL-6和NF-κB的影响

目的研究绿茶中的主要活性成分表没食子儿茶酚没食子酸酯(EGCG)对中、长波紫外线辐射诱导角质形成细胞产生IL-6和NF-κB的影响。方法用ELISA法测定角质形成细胞培养上清液中IL-6水平,免疫组化和WesternBlot法检测细胞中NF-κBp65的变化。结果UVB20、30mJ/cm2和UVA10、20J/cm2可以显著促进角质形成细胞分泌IL-6(P<0.05),且细胞内NF-κB的产生明显增加(P<0.05)。0.15mmol/L和0.3mmol/L的EGCG对紫外线诱导的IL-6分泌起到了抑制作用(P<0.05),其中0.3mmol/L的EGCG作用更为明显,对紫外线辐射诱导的角质形成细胞NF-κB产生有着显著的抑制作用(P<0.05)。结论中、长波紫外线辐射可以促进IL-6的分泌。EGCG能够抑制NF-κB易位入核,从而抑制IL-6的分泌。     

Green tea extract reduces induction of p53 and apoptosis in UVB-irradiated human skin independent of transcriptional controls

Ultraviolet (UV) irradiation plays a pivotal role in human skin carcinongenesis. Preclinically, systemically and topically applied green tea extract (GTE) has shown reduction of UV-induced (i) erythema, (ii) DNA damage, (iii) formation of radical oxygen species and (iv) downregulation of numerous factors related to apoptosis, inflammation, differentiation and carcinogenesis. In humans, topical GTE has so far only been tested in limited studies, with usually very high GTE concentrations and over short periods of time. Both chemical stability of GTE and staining properties of highly concentrated green tea polyphenols limit the usability of highly concentrated green tea extracts in cosmetic products. The present study tested the utility of stabilized low-dose GTE as photochemopreventive agents under everyday conditions. We irradiated with up to 100 mJ/cm(2) of UVB light skin patches which were pretreated with either OM24-containing lotion or a placebo lotion. Biopsies were taken from both irradiated and un-irradiated skin for both immunohistochemistry and DNA microarray analysis. We found that while OM24 treatment did not significantly affect UV-induced erythema and thymidine dimer formation, OM24 treatment significantly reduced UV-induced p53 expression in keratinocytes. We also found that OM24 treatment significantly reduced the number of apoptotic keratinocytes (sunburn cells and TUNEL-positive cells). Carefully controlled DNA microarray analyses showed that OM24 treatment does not induce off-target changes in gene expression, reducing the likelihood of unwanted side-effects. Topical GTE (OM24) reduces UVB-mediated epithelial damage already at low, cosmetically usable concentrations, without tachyphylaxis over 5 weeks, suggesting GTE as suitable everyday photochemopreventive agents.     

Immunocytochemical detection of the carbohydrate antigen, Sialyl Lewisx, in normal human skin and during irritant contact dermatitis

Abstract Sialys Lewis^x (SLex) is a ligand for the E-selectin and the interaction of E-selectin on the endothelium and SLe^x on T cells may be important for T-cell migration into the skin. We investigated the expression of SLe^x on Langerhans cells (LC) in normal skin and on LC repopulating epidermis deprived of LC due to a preceding irritant contact dermatitis. SLe^x was visualized by fluorescence and light microscopic immunocytochemistry using the monoclonal antibody. CSLEX-1. The results showed that about 40% of LC in normal epidermis express SLe^x. In the repopulation phase, most of the epidermal cells were CDla⁺/SLe^x+. We suggest that SLe^x is present on epidermal LC that have recently immigrated from the dermis.     

温热对HPV感染皮肤朗格汉斯细胞磷酸肌醇3-激酶活性的影响

目的 探讨不同局部温热条件对HPV感染皮损游走朗格汉斯细胞(LC)磷酸肌醇3激酶(P13-K)活性的影响.方法 利用37℃,42℃,45℃的温热处理培养液中的离体正常皮肤组织和尖锐湿疣皮损,采用荧光实时定量PCR法检测游走至培养液巾纯化的CD1a~+ LC P13-K p85α、p110α mRNA的表达水平.结果 正常人皮肤组织和尖锐湿疣组织游走纯化的CD1a~+ LC中P13-K p85a、p110α mRNA的表达量均随局部温度升高而逐渐减少.正常皮肤组织游走纯化的CD1a~+LC 中P13-K p85a mRNA的相对表达量37℃为1.00±0.00,42℃为0.78±0.13,45℃为0.54±0.17;P13-K p110α mRNA在不同温度的相对表达量分别为1.00±0.00,0.80±0.11,0.61±0.12;不同温度间比较,差异均有统计学意义(P＜0.01).而尖锐湿疣组织游走纯化的CD1a~+ LC中P13-K p85a mRNA的相对表达量37℃为1.00±0.00,42℃为0.20±0.11,45℃为0.1±0.08;P13-K p110α mRNA的相对表达量分别为1.00±0.00,0.49±0.21,0.09±0.03;不同温度间比较,差异均有统计学意义(P＜0.01).温热对尖锐湿疣组织游走LC中P13-K活性影响显著高于正常皮肤组织.结论 局部温热可能通过抑制LC P13-K的活性,提高机体免疫应答反应能力,消除HPV感染.