Ultraviolet AI exposure of human skin results in Langerhans cell depletion and reduction of epidermal antigen-presenting cell function: partial protection by a broad-spectrum sunscreen

Effect of Lumenato oral supplementation on plasma carotenoid levels and improvement of visual and experiential skin attributes

BACKGROUND

Cellular metabolism and exposure to solar irradiation result in generation of free radicals which are destructive and can lead to premature aging. Antioxidants and free radical scavengers such as carotenoids successfully protect from these free radicals by quenching and neutralizing them thereby strengthening skin barrier which leads to improved skin moisturization, desquamation, and a more youthful look. This study was designed to evaluate the consumer-perceived efficacy of an oral supplement (Lumenato™) containing a mix of tomato carotenoids and oil-soluble vitamins in improving skin appearance after 12 weeks of supplement use.

MATERIALS AND METHODS

Plasma levels of phytoene, phytofluene, zeta-carotene, and lycopene were quantitated before and after 1-, 2-, 3-, and 4-week administration of Lumenato by 24 healthy volunteers. Part II of the study addressed skin visual attributes as assessed by validated tools (questionnaires). A total of 60 females, aged 35 to 55 years, completed part II of the study. The subjects answered questionnaires pertaining to their assessment of skin appearance before and after 12 weeks of taking the supplement.

RESULTS

There was a significant increase (p < 0.001) in plasma levels of phytoene, phytofluene, and zeta-carotene after 1- to 4-week treatment with Lumenato. After 12 weeks of using the supplement, the score of different skin parameters was reported to significantly improve (p < 0.001). Improvement was recorded in skin elasticity, firmness, brightness, skin tone, reduction in dark spots and periorbital dark circles, skin hydration, texture and fine lines and wrinkles. A significant (p < 0.001) improvement in overall skin condition after using the supplement was observed. The subjects noticed statistically significant (p < 0.001) improvement in skin elasticity, firmness, brightness, skin tone, reduction in dark spots and periorbital dark circles, skin hydration, texture and fine lines and wrinkles after 12 weeks of using the supplement. The overall skin condition also exhibited a significant improvement (p < 0.001). Self-assessed improvement of the face was identified at the first time point (4 weeks) and improved significantly (p < 0.001) for the 12 weeks of use. Interestingly, these improvements persisted even after treatment was stopped.

CONCLUSION

Based on the confines and conditions of this study, the use of oral supplement containing a mix of tomato carotenoids significantly increased plasma levels of phytoene, phytofluene, and zeta-carotene, and continuous use resulted in improved facial skin attributes which were palpable by the consumers and continued even after treatment was stopped.

The Damaging Effects of Long UVA (UVA1) Rays: A Major Challenge to Preserve Skin Health and Integrity

Within solar ultraviolet (UV) light, the longest UVA1 wavelengths, with significant and relatively constant levels all year round and large penetration properties, produce effects in all cutaneous layers. Their effects, mediated by numerous endogenous chromophores, primarily involve the generation of reactive oxygen species (ROS). The resulting oxidative stress is the major mode of action of UVA1, responsible for lipid peroxidation, protein carbonylation, DNA lesions and subsequent intracellular signaling cascades. These molecular changes lead to mutations, apoptosis, dermis remodeling, inflammatory reactions and abnormal immune responses. The altered biological functions contribute to clinical consequences such as hyperpigmentation, inflammation, photoimmunosuppression, sun allergies, photoaging and photocancers. Such harmful impacts have also been reported after the use of UVA1 phototherapy or tanning beds. Furthermore, other external aggressors, such as pollutants and visible light (Vis), were shown to induce independent, cumulative and synergistic effects with UVA1 rays. In this review, we synthetize the biological and clinical effects of UVA1 and the complementary effects of UVA1 with pollutants or Vis. The identified deleterious biological impact of UVA1 contributing to clinical consequences, combined with the predominance of UVA1 rays in solar UV radiation, constitute a solid rational for the need for a broad photoprotection, including UVA1 up to 400 nm.

[Herpes zoster and subunit vaccine]

Varicella-zoster virus (VZV) causes varicella (chickenpox) as primary infection, and latently infects neuronal cells in the dorsal root ganglia (DRG). Reactivation of VZV from DRG results in herpes zoster, often decades later. VZV is the only airborne human herpesvirus and the only herpesvirus whose symptoms (both varicella and herpes zoster) can be prevented by vaccination. Herpes zoster is significantly more common in patients with bone marrow transplants, hematological malignancies, oral Jak inhibitors, SLE, and the elderly. The brand new subunit vaccine, ShingrixⓇ, for preventing herpes zoster is a mixture of adjuvant and recombinant VZV glycoprotein gE, which is highly effective in preventing zoster even in elderly people. In this review, the author discuss the onset mechanism of zoster from the clinical findings and summarize the result of clinical trials of the subunit vaccine.

Reducing the Incidence of Skin Cancer through Landscape Architecture Design Education

There is a high and growing incidence of skin cancer associated with overexposure to the sun. Most of a person’s exposure occurs during their first eighteen years of life. While many children are taught to wear hats and sunscreen, studies indicate these are inadequate. There is a pressing need to improve the design of our landscapes to reduce exposure. Landscape architects can play a key role in driving this process, but only if they understand the factors determining sun protection behaviours among children in the landscape, and how to design for these. We introduced a systematic evidence-based teaching approach to landscape architecture students in New Zealand where the incidence of skin cancer is one of the highest in the world. In this paper, we describe the methods we used to integrate scientific information into a creative design process that included four design phases: (1) review, summary and translation of evidential theory into design guidelines; (2) inventory and analysis of existing schoolyard; (3) redesign of schoolyard; and (4) final design evaluation. We found this process was effective in developing student appreciation for the need to improve sun protection through design, for increasing their understanding of the evidential science, in addition to developing their ability to translate, often inaccessible, evidential data into its spatial form implications. Furthermore, the process led to a high degree of confidence and pride among many students as their resulting design solutions were not only supported by evidence but were often highly creative. Such evidence-based design courses are essential for preparing future landscape architects to design landscapes that significantly reduce the incidence and health effects of skin cancer.

A retrospective review of UVA1 treatment: An Australian experience from a single centre

BACKGROUND

The therapeutic value of ultraviolet A1 (UVA1) phototherapy has been acknowledged for many years. Initially developed predominately for experimental and diagnostic purposes, it was subsequently recognised as a beneficial therapeutic modality in atopic dermatitis and localised scleroderma, and more recently a variety of sclerosing and fibrosing dermatoses, T-lymphocyte mediated disorders, both inflammatory and infiltrative, and several predominately dermal processes previously unresponsive to current therapies.

METHODS

We present a retrospective evaluation of outcomes and treatment tolerability in adult patients using a low dose (30 joules/cm² ), regimen administered in our private dermatologic practice, between 2006 and December 2019.

RESULTS

Major clinical groups represented include atopic dermatitis, localised and systemic sclerodermas, mycosis fungoides, urticarial dermatitis, generalised pruritus and granuloma annulare. Eighty-seven patients are included in this study with 92% of all patients experiencing a beneficial result, 54% having complete and 38% partial relief of presenting signs and/or symptoms. UVA1 therapy was well tolerated, with no patients ceasing treatment due to adverse effects.

CONCLUSIONS

Ultraviolet A1 is an effective and safe treatment option in many hitherto recalcitrant cutaneous conditions.

The efficacy of UVA1 phototherapy in psoriasis: Clinical and histological aspects

BACKGROUND

Although ultraviolet A1 (UVA1) phototherapy is available for nearly 30 years, only few studies have been conducted for plaque-type psoriasis.

OBJECTIVES

To determine the efficacy and safety of UVA1 phototherapy in psoriasis by assessing the clinical and histological outcomes.

METHODS

This open study enrolled 15 patients with moderate to severe plaque-type psoriasis. All of the patients had skin type IV. A whole-body UVA1 device consisting of 24 lamps, was irradiated at a medium dose of 50 J/cm² three-times weekly for 30 sessions. Topical and systemic psoriasis treatments were discontinued before and during treatment; patients could only use emollients and antihistamines until 1-month post-completion. Psoriasis Area and Severity Index (PASI) scores were determined at baseline; at sessions 10th, 20th and 30th; and 1 month after treatment. Four-millimetre punch biopsies were obtained from the same psoriasis lesion at baseline and session 30th. Changes in histopathological gradings and polymorphonuclear, lymphocyte and Langerhans cell numbers were monitored.

RESULTS

Twelve patients completed the study. The mean age was 41.3 years (range: 25-71). The median PASI scores at baseline, session 30th and 1-month post-treatment were 16 (8.2, 43.3), 11 (4.4, 43.3) and 9.2 (2.7, 36.4), respectively. Although the PASI scores had improved significantly by 1-month post-treatment (P = .006), the histological parameters demonstrated minimal changes. All patients tolerated the phototherapy well and the most common side effect was skin tanning.

CONCLUSIONS

While medium-dose UVA1 phototherapy demonstrated some efficacy in moderate to severe plaque-type psoriasis. However, it might not be an excellent choice.

Antioxidant and Anti-Inflammatory Effects of Shungite against Ultraviolet B Irradiation-Induced Skin Damage in Hairless Mice

As fullerene-based compound applications have been rapidly increasing in the health industry, the need of biomedical research is urgently in demand. While shungite is regarded as a natural source of fullerene, it remains poorly documented. Here, we explored the in vivo effects of shungite against ultraviolet B- (UVB-) induced skin damage by investigating the physiological skin parameters, immune-redox profiling, and oxidative stress molecular signaling. Toward this, mice were UVB-irradiated with 0.75 mW/cm² for two consecutive days. Consecutively, shungite was topically applied on the dorsal side of the mice for 7 days. First, we found significant improvements in the skin parameters of the shungite-treated groups revealed by the reduction in roughness, pigmentation, and wrinkle measurement. Second, the immunokine profiling in mouse serum and skin lysates showed a reduction in the proinflammatory response in the shungite-treated groups. Accordingly, the redox profile of shungite-treated groups showed counterbalance of ROS/RNS and superoxide levels in serum and skin lysates. Last, we have confirmed the involvement of Nrf2- and MAPK-mediated oxidative stress pathways in the antioxidant mechanism of shungite. Collectively, the results clearly show that shungite has an antioxidant and anti-inflammatory action against UVB-induced skin damage in hairless mice.

Molecular mechanisms of green tea polyphenols with protective effects against skin photoaging

Whereas green tea has historically been consumed in high quantities in Northeast Asia, its popularity is also increasing in many Western countries. Green tea is an abundant source of plant polyphenols exhibiting numerous effects that are potentially beneficial for human health. Accumulating evidence suggests that green tea polyphenols confer protective effects on the skin against ultraviolet (UV) irradiation-induced acceleration of skin aging, involving antimelanogenic, antiwrinkle, antioxidant, and anti-inflammatory effects as well as prevention of immunosuppression. Melanin pigmentation in the skin is a major defense mechanism against UV irradiation, but pigmentation abnormalities such as melasma, freckles, senile lentigines, and other forms of melanin hyperpigmentation can also cause serious health and aesthetic issues. Furthermore, UV irradiation initiates the degradation of fibrillar collagen and elastic fibers, promoting the process of skin aging through deep wrinkle formation and loss of tissue elasticity. UV irradiation-induced formation of free radicals also contributes to accelerated photoaging. Additionally, immunosuppression caused by UV irradiation plays an important role in photoaging and skin carcinogenesis. In this review, we summarize the current literature regarding the antimelanogenic, antiwrinkle, antioxidant, and immunosuppression preventive mechanisms of green tea polyphenols that have been demonstrated to protect against UV irradiation-stimulated skin photoaging, and gauge the quality of evidence supporting the need for clinical studies using green tea polyphenols as anti-photoaging agents in novel cosmeceuticals.

Chemical characterization of sunscreens composition and its related potential adverse health effects

Although the sun is very beneficial and essential for life, exposing ourselves too much to sunlight might lead to detrimental health effects such as skin cancer. Eight percent of the total different electromagnetic radiation that regularly irradiates the earth is classified as ultraviolet (UV) radiation. The ozone layer absorbs the most energetic UV rays; consequently, UV-A and UV-B reach the earth surface. UV-A rays heavily contribute to both premature skin aging and skin cancer, while UV-B rays cause sunburn. Hence, the use of sunscreen is strongly encouraged by many healthcare practitioners in order to minimize or possibly eradicate the harmful effects of UV rays on our skin, keeping in mind, that about 90% of all skin cancers are associated with exposure to the sun's harmful radiation. Unfortunately, inaccurate information is currently roaming the media and the Internet regarding the safety, toxicity, and acute side effects of the active ingredients currently used in sunscreens, therefore discouraging people from using sunscreens. In this review article, it is concluded based on the scientific published literature that the sunscreen ingredients are safe and there are no related potential hazardous health risks associated with their use. In addition, at present, sunscreens are very useful in preventing sunburn and probably skin cancer and photoaging and their regular use can have a positive and a significant impact on public health as means or instruments implemented to reduce exposure to UV radiation.

CD1a+ and CD83+ Langerhans cells are reduced in lower lip squamous cell carcinoma

BACKGROUND

Actinic cheilitis (AC) is a potentially malignant lesion diagnosed in the lip of patients chronically exposed to the sun that may give rise to a fully invasive lower lip squamous cell carcinoma (LLSCC). It is known that ultraviolet radiation causes dendritic cells (DCs) depletion in the epidermis, but the role of this cellular population in lip cancer progression remains uncertain. Therefore, this study investigated the distribution of DCs in normal, dysplastic and neoplastic tissues of the lower lip.

METHODS

Thirteen cases of lower lip mucocele, 42 of ACs and 21 of LLSCC were retrieved and original diagnoses confirmed by two oral pathologists, who further classified ACs as low- and high-risk lesions. Immunoreactions against CD1a and CD83 identified immature and mature DCs, respectively.

RESULTS

Immature CD1a+ Langerhans cells (LCs) were significantly decreased in LLSCC when compared to morphologically normal (P < 0.009) and dysplastic epitheliums (P < 0.003), whereas mature CD83+ LCs were significantly decreased in LLSCC when compared to normal epithelium (P = 0.038). There was no significant difference between low- and high-risk ACs regarding CD1a+ and CD83+ LCs (P > 0.05), but ACs demonstrated a lower concentration of CD1a+ LCs than normal epithelium (P < 0.009). There was no significant difference in the distribution of CD1a+ and CD83+ interstitial dendritic cells (IDCs) in the connective tissue among the studied groups (P > 0.05).

CONCLUSION

These results suggest that depletion of epithelial LCs, but not IDCs in the connective tissue, would represent an important step for lip cancer development.

Characterization of dendritic cells in lip and oral cavity squamous cell carcinoma

BACKGROUND

There may be differences in the antitumor immunity induced by dendritic cells (DCs) during the development of squamous cell carcinoma (SCC) located in the lip rather than in the oral cavity. The aim of this study was to evaluate the number of immature and mature DCs in SCC and potentially malignant disorders of the oral cavity and lip.

METHODS

Immunohistochemistry was used to identify the number (cells/mm(2) ) of immature (CD1a(+) ) or mature (CD83(+) ) DCs in samples of oral cavity SCC (OCSCC) (n = 39), lip SCC (LSCC) (n = 23), leukoplakia (LK) (n = 21), actinic cheilitis (AC) (n = 13), and normal mucosa of the oral cavity (OC control, n = 12) and the lip (lip control, n = 11).

RESULTS

The number of CD1a(+) cells tended to be higher in the OC control samples compared with the LK (P = 0.04) and OCSCC (P = 0.21). Unlike, this cell population was lower in the lip control than in AC or LSCC (P < 0.05). The number of CD83(+) cells was increased in the LSCC samples compared with the AC and lip control (P = 0.0001) and in OCSCC compared with both the LK (P = 0.001) and OC control (P = 0.0001) samples. LSCC showed an elevated number of CD1a(+) and CD83(+) cells compared with OCSCC (P = 0.03). The population of mature DCs was lower than the population of immature DCs in all of the tested groups (P < 0.05).

CONCLUSION

There were a greater number of both mature and immature DC populations in the LSCC samples than in the OCSCC, which could contribute to establishing a more effective immune antitumor response for this neoplasm.

Functional Food und Bioverfügbarkeit im Zielorgan Haut

Reactive free radicals can be produced in the skin by the action of environmental factors, such as sun radiation and toxins. These radicals can damage the DNA, proteins and lipids of the living cells. The consequences can be skin aging, immune suppression and even skin cancer. Humans have developed a protective mechanism against the action of free radicals in the form of antioxidant substances. Several of these antioxidants cannot be produced by humans and have to be acquired via food, such as carotenoids. Optical, non-invasive methods, like resonance Raman spectroscopy, allow a qualitative and quantitative online detection of the kinetics of antioxidants such as carotenoids in the skin. By employing this method it has been shown that the uptake of carotenoids in food can lead to an accumulation in the skin. On the other hand, stress, illness and UV-radiation can reduce the concentration of antioxidant substances in the skin. A high concentration of antioxidant substances is protective and associated with a reduction in skin wrinkling.

Brazilian consensus on photoprotection

Brazil is a country of continental dimensions with a large heterogeneity of climates and massive mixing of the population. Almost the entire national territory is located between the Equator and the Tropic of Capricorn, and the Earth axial tilt to the south certainly makes Brazil one of the countries of the world with greater extent of land in proximity to the sun. The Brazilian coastline, where most of its population lives, is more than 8,500 km long. Due to geographic characteristics and cultural trends, Brazilians are among the peoples with the highest annual exposure to the sun. Epidemiological data show a continuing increase in the incidence of non-melanoma and melanoma skin cancers. Photoprotection can be understood as a set of measures aimed at reducing sun exposure and at preventing the development of acute and chronic actinic damage. Due to the peculiarities of Brazilian territory and culture, it would not be advisable to replicate the concepts of photoprotection from other developed countries, places with completely different climates and populations. Thus the Brazilian Society of Dermatology has developed the Brazilian Consensus on Photoprotection, the first official document on photoprotection developed in Brazil for Brazilians, with recommendations on matters involving photoprotection.

Photoimmunology and Multiple Sclerosis

The ultraviolet (UV) radiation contained in sunlight is a powerful immune suppressant. While exposure to UV is best known for its ability to cause skin cancer, it is also associated with protection against a range of autoimmune diseases, particularly multiple sclerosis (MS). Although the precise mechanism by which sunlight affords protection from MS remains to be determined, some have hypothesised that UV immunosuppression explains the "latitude-gradient effect" associated with MS. By stimulating the release of soluble factors in exposed skin, UV activates immune suppressive pathways that culminate in the induction of regulatory cells in distant tissues. Each and every one of the immune suppressive cells and molecules activated by UV exposure are potential targets for treating and preventing MS. A thorough understanding of the mechanisms involved is therefore required if we are to realise the therapeutic potential of photoimmunology.

Diversity of biological effects induced by longwave UVA rays (UVA1) in reconstructed skin

Despite their preponderance amongst the ultraviolet (UV) range received on Earth, the biological impacts of longwave UVA1 rays (340–400 nm) upon human skin have not been investigated so thoroughly. Nevertheless, recent studies have proven their harmful effects and involvement in carcinogenesis and immunosuppression. In this work, an in vitro reconstructed human skin model was used for exploring the effects of UVA1 at molecular, cellular and tissue levels. A biological impact of UVA1 throughout the whole reconstructed skin structure could be evidenced, from morphology to gene expression analysis. UVA1 induced immediate injuries such as generation of reactive oxygen species and thymine dimers DNA damage, accumulating preferentially in dermal fibroblasts and basal keratinocytes, followed by significant cellular alterations, such as fibroblast apoptosis and lipid peroxidation. The full genome transcriptomic study showed a clear UVA1 molecular signature with the modulation of expression of 461 and 480 genes in epidermal keratinocytes and dermal fibroblasts, respectively (fold change> = 1.5 and adjusted p value<0.001). Functional enrichment analysis using GO, KEGG pathways and bibliographic analysis revealed a real stress with up-regulation of genes encoding heat shock proteins or involved in oxidative stress response. UVA1 also affected a wide panel of pathways and functions including cancer, proliferation, apoptosis and development, extracellular matrix and metabolism of lipids and glucose. Strikingly, one quarter of modulated genes was related to innate immunity: genes involved in inflammation were strongly up-regulated while genes involved in antiviral defense were severely down-regulated. These transcriptomic data were confirmed in dose-response and time course experiments using quantitative PCR and protein quantification. Links between the evidenced UVA1-induced impacts and clinical consequences of UVA1 exposure such as photo-aging, photo-immunosuppression and cancer are discussed. These early molecular events support the contribution of UVA1 to long term harmful consequences of UV exposure and underline the need of an adequate UVA1 photoprotection.

UVA-1 therapy of localized scleroderma and other diseases accompanied by skin sclerosis

The study results confirm the efficacy of the UVA-1 therapy for patients with localized scleroderma, extragenital lichen sclerosus et atrophicus, sclerodermatous chronic graft-versus-host disease and scleredema adultorum. The therapy has an anti-inflammatory and anti^m^ action, arrests progression and reduces the activity of the disease process, and has a good efficacy and safety profile.

Histological study on the effect of electrolyzed reduced water-bathing on UVB radiation-induced skin injury in hairless mice

Electrolyzed reduced water (ERW), functional water, has various beneficial effects via antioxidant mechanism in vivo and in vitro. However there is no study about beneficial effects of ERW bathing. This study aimed to determine the effect of ERW bathing on the UVB-induced skin injury in hairless mice. For this purpose, mice were irradiated with UVB to cause skin injury, followed by individually taken a bath in ERW (ERW-bathing) and tap water (TW-bathing) for 21 d. We examined cytokines profile in acute period, and histological and ultrastructural observation of skin in chronic period. We found that UVB-mediated skin injury of ERW-bathing group was significantly low compared to TW control group in the early stage of experiment. Consistently, epidermal thickening as well as the number of dermal mast cell was significantly lowered in ERW-bathing group. Defection of corneocytes under the scanning electron microscope was less observed in ERW-bathing group than in TW-bathing group. Further, the level of interleukin (IL)-1β, tumor necrosis factor (TNF)-α and IL-12p70 in ERW group decreased whereas those of IL-10 increased. Collectively, our data indicate that ERW-bathing significantly reduces UVB-induced skin damage through influencing pro-/anti-inflammatory cytokine balance in hairless mice. This suggests that ERW-bathing has a positive effect on acute UVB-mediated skin disorders. This is the first report on bathing effects of ERW in UVB-induced skin injury.

Exogenous control of the expression of Group I CD1 molecules competent for presentation of microbial nonpeptide antigens to human T lymphocytes

Group I CD1 (CD1a, CD1b, and CD1c) glycoproteins expressed on immature and mature dendritic cells present nonpeptide antigens (i.e., lipid or glycolipid molecules mainly of microbial origin) to T cells. Cytotoxic CD1-restricted T lymphocytes recognizing mycobacterial lipid antigens were found in tuberculosis patients. However, thanks to a complex interplay between mycobacteria and CD1 system, M. tuberculosis possesses a successful tactic based, at least in part, on CD1 downregulation to evade CD1-dependent immunity. On the ground of these findings, it is reasonable to hypothesize that modulation of CD1 protein expression by chemical, biological, or infectious agents could influence host's immune reactivity against M. tuberculosis-associated lipids, possibly affecting antitubercular resistance. This scenario prompted us to perform a detailed analysis of the literature concerning the effect of external agents on Group I CD1 expression in order to obtain valuable information on the possible strategies to be adopted for driving properly CD1-dependent immune functions in human pathology and in particular, in human tuberculosis.

Carotenoids in human skin

The interaction of free radicals with antioxidants is a topic of increasing interest in the development of prevention strategies against skin ageing. Carotenoids can serve as marker substances for the complete antioxidative network of human skin. Recently, it has become possible to measure the carotenoids non-invasively and online using resonance Raman spectroscopy. This method has been used in various studies to investigate the interaction of carotenoid antioxidants and free radicals in human skin. In this review, the results of the selected studies are summarized and compared. It could be demonstrated that the carotenoid concentration of the skin reflects the lifestyle of individuals. A high level of carotenoids can be achieved with a healthy diet rich, for instance, in fruit and vegetables. Stress factors such as illness, UV and IR radiation of the sun, and smoking and alcohol consumption reduce the concentration of the carotenoids in the skin. It could be demonstrated that premature skin ageing was less in people with a high level of antioxidants in their tissue. Consequently, the furrows and wrinkles were not so deep and dense as in the skin of individuals with a low antioxidant level. The measurements are highly suited for the development of anti-ageing strategies and can be efficiently used in the medical diagnostics and therapy control.

The UV response of the skin: a review of the MAPK, NFkappaB and TNFalpha signal transduction pathways

The sun emits different types of ultraviolet (UV) light. Our skin is a natural target of UV radiation which is involved in vitamin D3 production in our body. UV radiation at high doses is an environmental carcinogen which can elicit skin damage as well as inducing skin cancer. It can mediate inflammatory and immunological reactions through activation of receptors, DNA/RNA damage and production of reactive oxygen species. It is also involved in the release of pro-inflammatory cytokines, of which TNFalpha has been implicated in tumorigenic activities. In order to mediate its effects, UV radiation is known to activate multiple signalling cascades such as the p38 MAPK, Jun N-terminal kinase, extracellular signal-regulated kinase 1/2 and NFkappaB pathways in skin cells. The role each of these pathways plays in mediating the release of cytokines such as TNFalpha remains to be fully characterized. Once the function of these pathways is known, this information may provide for the formulation of therapy which will prevent the release of immunosuppressive cytokines resulting in a reduction in skin cancer formation.

Topical application of green and white tea extracts provides protection from solar-simulated ultraviolet light in human skin

BACKGROUND

Tea polyphenols have been found to exert beneficial effects on the skin via their antioxidant properties.

AIMS

We sought to determine whether topical application of green tea or white tea extracts would prevent simulated solar radiation-induced oxidative damages to DNA and Langerhans cells that may lead to immune suppression and carcinogenesis.

METHODS

Skin samples were analysed from volunteers or skin explants treated with white tea or green tea after UV irradiation. In another group of patients, the in vivo immune protective effects of green and white tea were evaluated using contact hypersensitivity to dinitrochlorobenzene.

RESULTS

Topical application of green and white tea offered protection against detrimental effects of UV on cutaneous immunity. Such protection is not because of direct UV absorption or sunscreen effects as both products showed a sun protection factor of 1. There was no significant difference in the levels of protection afforded by the two agents. Hence, both green tea and white tea are potential photoprotective agents that may be used in conjunction with established methods of sun protection.

Radiation Sources Providing Increased UVA/UVB Ratios Attenuate the Apoptotic Effects of the UVB Waveband UVA-Dose-Dependently in Hairless Mouse Skin

UV radiation-induced epidermal apoptotic sunburn cells provide a mechanism for eliminating cells with irreparable DNA damage. The UVB (290-320 nm) waveband is mainly responsible, but the role of UVA (320-400 nm) is less clear, and possible waveband interactions have not been examined. Recent studies in mice reveal a protective role for UVA against UVB-induced inflammation and immunosuppression, mediated via cutaneous heme oxygenase (HO). As HO has antiapoptotic properties in other tissues, this study examines the effect of UVA/UVB waveband interaction on apoptosis in the Skh:hr-1 hairless mouse epidermis. Apoptosis was assessed by sunburn cell number, caspase-3-positive cell number, and degree of DNA fragmentation, in mice exposed to radiation sources providing a constant UVB dose with increasing proportions of UVA. The results indicated that as the UVA/UVB ratio was increased, both the sunburn cell and caspase-3-positive cell number decreased, and the degree of DNA fragmentation was reduced. Treatment of mice with the HO inhibitor, tin protoporphyrin-IX, markedly reduced the UVA antiapoptotic effect, confirming a major role for HO. The observations suggest that UVA reduces UVB-induced DNA damage, and may therefore have anti-photocarcinogenic properties that could be harnessed for better photoprotection in humans.

Decreased human epidermal antigen-presenting cell activity after ultraviolet A exposure: dose–response effects and protection by sunscreens

BACKGROUND

Ultraviolet (UV) exposure of human skin causes immunosuppression that contributes to the growth of skin cancer. The contribution of UVA in these processes is still a matter of debate.

OBJECTIVES

The purpose of our study was first to find a dose-response effect of UVA exposure on human epidermal antigen-presenting cell (APC) activity and to evaluate the protective capacity of two sunscreen formulations against a high level of acute UVA exposure. We also tried to evaluate the protective capacity afforded by the same sunscreens against UVA-induced clinical changes such as redness and pigmentation.

METHODS

The functional assessment of the alloantigen-presenting capacity of epidermal cells prepared from skin keratotome samples 3 days after UVA exposure was measured with a mixed epidermal cell-lymphocyte reaction (MECLR) in each healthy volunteer (n = 16). Redness and pigmentation were assessed by chromametry 24 h after exposure to a single UVA dose.

RESULTS

In vivo UVA exposure to 15, 30 and 60 J cm(-2) resulted in a dose-dependent decrease in purified allogeneic T cell (CD4+ T cells) proliferation induced by UVA-irradiated epidermal cells. The epidermal APC function was significantly decreased with a suberythemal exposure corresponding to 15 J cm(-2). The decrease, partial and not statistically different between 30 and 60 J cm(-2), exhibits a plateau-response effect. There was no correlation between the decrease of the epidermal APC function and the intensity of erythema and persistent pigment darkening. Both sunscreen formulations strongly inhibited the UVA-induced reduction of MECLR at 90 J cm(-2).

CONCLUSION

Our results clearly demonstrate that UVA impairs the APC activity of the epidermal cells and thus may contribute to UV-induced immunosuppression in humans. They also indicate that erythema and immunosuppression have different dose-response curves in the UVA range. The two sunscreen formulations afforded a significant protection against the decrease in epidermal APC activity induced by exposure to a high UVA dose (90 J cm(-2)).

Deficient inflammatory response to UV radiation in neonatal mice

Mechanisms of juvenile susceptibility to cancer are not well understood. The immune response in neonates favors nonresponsiveness or T(H)2-dominant responses, raising the question of a role for neonatal immunity in this susceptibility. We have investigated the postulate that the inflammatory response differs in neonatal and adult skin. We found no inflammatory infiltrate into neonatal mouse skin in response to UV irradiation as a function of time, dose, or wavelength, although UV-induced DNA damage was readily detected. In contrast, UV irradiation of adult mice initiated a dose- and time-dependent influx of inflammatory cells, chiefly CD11b(+)Ly6G(+) neutrophils, into the skin, detected by immunohistochemistry and quantitated by FACS analysis. This inflammatory response was initiated by UVB (290-320 nm) but not by UVA (320-400 nm). Further, in neonates, in contrast to adults, neither topical trinitrochlorobenzene (TNCB) nor i.p. thioglycollate initiated an inflammatory infiltrate. Conversely, topical TNCB applied to neonates was tolerogenic, resulting in a subsequent antigen-specific decrease of the contact-hypersensitivity response in adults. Neonatal blood contained abundant neutrophils, which exhibited impaired chemotaxis to the chemokine growth-related oncogene-alpha but efficient chemotaxis to the bacterial product fMLP, concomitant with decreased expression of CXCR2 but normal levels of CD11b. We propose this neonatal deficiency in the inflammatory response is a significant, previously unrecognized factor in neonatal immune tolerance and may contribute to neonatal susceptibility to cancer, including melanoma and other UV-induced cancers.

No adaptation to UV-induced immunosuppression and DNA damage following exposure of mice to chronic UV-exposure

It is well known that ultraviolet (UV) radiation induces erythema, immunosuppression and carcinogenesis. We hypothesized that chronic exposure to solar UV radiation induces adaptation that eventually prevents the suppression of acquired immunity. We studied adaptation for UV-induced immunosuppression after chronic exposure of mice to a suberythemal dose of solar simulated radiation (SSR) with Cleo Natural lamps, and subsequent exposure to an immunosuppressive dose of solar or UVB radiation (TL12). After UV dosing, the mice were sensitized and challenged with either diphenylcyclopropenone (DPCP) or picryl chloride (PCl). To assess the adaptation induced by solar simulated radiation, we measured the proliferative response and cytokine production of skin-draining lymph node cells after immunization to DPCP, the contact hypersensitivity (CHS) response to PCl, and thymine-thymine (T-T) cyclobutane dimers in the skin of mice. After induction of immunosuppression by SSR or by TL12 lamps, the proliferative response of draining lymph node cells after challenge with DPCP, or the CHS after challenge with PCl, showed significant suppression of the immune response. Chronic irradiation from SSR preceding the immunosuppressive dose of UV failed to restore the suppressed immune response. Reduced lipopolysaccharide-triggered cytokine production (of IL-12p40, IFN-gamma, IL-6 and TNF-alpha) by draining lymph node cells of mice sensitized and challenged with DPCP indicated that no adaptation is induced. In addition, the mice were not protected from T-T dimer DNA damage after chronic solar irradiation. Our studies reveal no evidence that chronic exposure to low doses of SSR induces adaptation to UV-induced suppression of acquired immunity.

Photoimmunoprotection by UVA (320-400 nm) radiation is determined by UVA dose and is associated with cutaneous cyclic guanosine monophosphate

The immunomodulating properties of UVA radiation remain controversial. Here, we demonstrate in female inbred Skh:hr-1 mice that single subinflammatory UVA exposures between 1.61 and 580.5 kJ/m(2) are not immunosuppressive. Furthermore, UVA exposures between 16.13 and 580.5 kJ/m(2) provided dose-related immunoprotection against UVB-induced immunosuppression. Higher UVA exposures (870.8-1,161 kJ/m(2)) became inflammatory and immunosuppressive alone, and lost the photoimmunoprotective capacity. We previously reported that UVA photoimmunoprotection depends on the induction of cutaneous heme oxygenase-1, particularly its enzymatic product, carbon monoxide (CO). CO was suggested to activate cutaneous guanylyl cyclase (GC), as the specific GC inhibitor, 1H-(1,2,4)oxadiazolo-(4,3-a)quinoxalin-1-one (ODQ), abrogated CO photoimmunoprotection in the mouse. This study shows that cutaneous cyclic guanosine monophosphate (cGMP) concentration increased only following immunoprotective UVA doses, or immunoprotective topical CO treatment, and cGMP production was inhibited by ODQ. Conversely, cGMP concentration was increased by inhibition of its degradative phosphodiesterase (PDE) with topical sildenafil. The PDE-5 isoform was identified in normal mouse skin. Subsequently, a moderate concentration of sildenafil was shown to simulate the effect of UVA in protecting against photoimmunosuppression by solar-simulated UV radiation or its mediator cis-urocanic acid. Thus, cutaneous cGMP, controlled by its synthesis via CO-activated GC and its degradation by PDE-5, is strongly associated with UVA photoimmunoprotection.

Relevance of Sunscreen Application Method, Visible Light and Sunlight Intensity to Free-radical Protection: A Study of ex vivo Human Skin

With the continued rise in skin cancers worldwide there is a need for effective skin protection against sunlight damage. It was shown previously that sunscreens, which claimed UVA protection (SPF 20+), provided limited protection against UV-induced ascorbate radicals in human skin. Here the results of an electron spin resonance (ESR) investigation to irradiate ex vivo human skin with solar-simulated light are reported. The ascorbate radical signal in the majority of skin samples was directly proportional to the irradiance over relevant sunlight intensities (0.9-2.9 mW cm(-2)). Radical production (substratum-corneum) by UV (wavelengths < 400 nm) and visible components (> 400 nm) was approximately 67% and 33% respectively. Ascorbate radicals were in steady state concentration at low irradiance (approximately 1 mW cm(-2) equivalent to UK sunlight), but at higher irradiance (approximately 3 mW cm(-2)) decreased with time, suggesting ascorbate depletion. Radical protection by a four star-rated sunscreen (with UVA protection) was optimal when applied as a thin film (40-60% at 2 mg cm(-2)) but less so when rubbed into the skin (37% at 4 mg cm(-2) and no significant protection at 2 mg cm(-2)), possibly due to cream filling crevices, which reduced film thickness. This study validates ESR determinations of the ascorbate radical for quantitative protection measurements. Visible light contribution to radical production, and loss of protection when sunscreen is rubbed into skin, has implications for sunscreen design and use for the prevention of free-radical damage.

Ultraviolet Immunosuppression: Mechanisms and Consequences

It is well recognized that exposure to solar radiation has several detrimental consequences, both acute and chronic. The suppression of immune functions remains one of the most intriguing phenomena brought about by ultraviolet (UV) radiation. This concept has challenged experts from various disciplines including dermatology, immunology, and photobiology. Although controversies exist regarding the mechanisms involved, the consensus is that UV immune suppression contributes significantly to the growth of cutaneous malignancies--both melanoma and nonmelanoma skin cancer. It is therefore a critical issue to be addressed in the context of developing and using sun protection strategies.

[Ultraviolet radiation--immune response]

Ultraviolet (UV) radiation can exert a variety of biological effects, including induction of skin cancer, premature skin ageing and inhibition of the immune system. The immunosuppressive properties of UV radiation are of major biological and clinical relevance since suppression of the immune system by UV radiation also contributes to the induction of skin cancer. Hence, understanding of the mechanisms by which UV radiation compromises the immune system is of primary importance. UV radiation suppresses the immune system in multiple ways. It inhibits antigen presentation, stimulates the release of immunosuppressive cytokines and induces the generation of lymphocytes of the regulatory subtype. The major molecular target for UV-induced immunosuppression is UV-induced DNA damage. Further elucidation of the mechanisms underlying UV-induced immunosuppression will not only lead to a better understanding of the physiologic and pathologic effects of UV radiation but also contribute to the development of new protective strategies.

[UV-induced skin cancers]

In this review the epidemiology and pathogenetic aspects of UV-induced malignant skin tumours (basal cell carcinoma, squamous cell carcinoma and melanoma) are discussed with regard to current literature. Whereas present knowledge, in particular, gained from experimental data, permits substantial conclusions about the development of squamous cell carcinoma, the situation for basal cell carcinoma and melanoma does not appear to be unequivocally clear. One reason for this can be explained by the fact that there exist no adequate animal models for these tumours that could exactly reflect the biological behaviour in man. Although there is no doubt about a causal role of sun exposure, this relationship is based on mere epidemiological facts.

Near-critical carbon dioxide extraction and liquid chromatography determination of UV filters in solid cosmetic samples: A green analytical procedure

Near-critical carbon dioxide extraction of four UV filters used as sunscreens in lipsticks and makeup formulations is reported. Extraction parameters were optimized. Efficient recoveries were obtained after 15 min of dynamic extraction with a 80:20 CO2/ethanol mixture at 300 atm and 54 degrees C, using a 1.8 mL/min flow rate. Extracts were collected in ethanol, and appropriately diluted with ethanol and 1% acetic acid to obtain a 70:30 v/v ethanol/1% acetic acid solution. The four UV filters were determined by LC with gradient elution using ethanol/1% acetic acid as mobile phase. The accuracy of the analytical procedure was estimated by comparing the results with those obtained by methods based on classical extraction. The proposed method only requires the use of CO2, ethanol and acetic acid avoiding the use of more toxic organic solvents, thus it could be considered as both operator and environment friendly.

UVA Radiation Impairs Phenotypic and Functional Maturation of Human Dermal Dendritic Cells

There is now strong evidence that the ultraviolet A (UVA) part of the solar spectrum contributes to the development of skin cancers. Its effect on the skin immune system, however, has not been fully investigated. Here, we analyzed the effects of UVA radiation on dermal dendritic cells (DDC), which, in addition, provided further characterization of these cells. Dermal sheets were obtained from normal human skin and irradiated, or not, with UVA at 2 or 12 J per cm2. After a 2 d incubation, the phenotype of emigrant cells was analyzed by double immunostaining and flow cytometry. Results showed that migratory DDC were best characterized by CD1c expression and that only few cells co-expressed the Langerhans cell marker Langerin. Whereas the DC extracted from the dermis displayed an immature phenotype, emigrant DDC showed increased expression of HLA-DR and acquired co-stimulation and maturation markers. We showed here that UVA significantly decreased the number of viable emigrant DDC, a process related to increased apoptosis. Furthermore, UVA irradiation impaired the phenotypic and functional maturation of migrating DDC into potent antigen-presenting cells, in a concentration-dependent manner. The results provide further evidence that UVA are immunosuppressive and suggest an additional mechanism by which solar radiation impairs immune response.

Solar-simulated ultraviolet radiation induces abnormal maturation and defective chemotaxis of dendritic cells

Exposure to ultraviolet (UV) light induces immunosuppression. Different evidences indicate that this phenomenon is mainly a consequence of the effect of UV light on skin dendritic cells (DC). To investigate the cellular and molecular basis of this type of immunosuppression, we assessed in vitro the effect of solar-simulated UV radiation on the phenotypic and functional characteristics of human monocyte-derived DC and Langerhans-like DC. UV radiation induced a decreased expression of molecules involved in antigen capture as DC-SIGN and the mannose receptor. This effect was accompanied by a diminished endocytic capacity, an enhanced expression of molecules involved in antigen presentation such as major histocompatibility complex-II and CD86, and a significant increase in their capability to stimulate T cells. Furthermore, irradiated DC failed to acquire a full mature phenotype upon treatment with lipopolysaccharide. On the other hand, solar-simulated radiation induced the secretion of tumor necrosis factor-alpha and interleukin (IL)-10 by DC, but no IL-12. Interestingly, solar-simulated UV radiation also caused an altered migratory phenotype, with an increased expression of CXCR4, and a lack of induction of CCR7, thus correlating with a high chemotactic response to stromal cell-derived factor 1(SDF-1) (CXCL12), but not to secondary lymphoid tissue chemokine (SLC) (CCL21). These data indicate that solar-simulated UV radiation induces a defective maturation and an anomalous migratory phenotype of DC.

Reactivity of Langerhans cells in human reconstructed epidermis to known allergens and UV radiation

Epidermal Langerhans cells are the outmost guards of our immune defence system. These cells are directly involved in phenomena such as contact hypersensitivity and UV-induced immunosuppression. Some years ago we succeeded in introducing CD34(+)-derived Langerhans cells into a reconstructed human epidermis. Here we describe their reactivity after topical exposure of the reconstructed epidermis to known allergens, allergen-inducible cytokines, irritants and UV irradiation. Exposure to allergens for 24 h resulted in an activated appearance of the Langerhans cells and in some cases a decrease in their number. Concomitantly, IL-1beta and CD86 mRNA over-expressions were detected in the reconstructed epidermis. A topical treatment with TNF-alpha or IL-1beta revealed that both cytokines induced an activated appearance of the Langerhans cells as early as 4 h following application. Irritants had no effect on the integrated Langerhans cells. Exposure of the reconstructed epidermis to Solar Simulated Radiation caused a dramatic decrease in the number of Langerhans cells and a loss of dendricity in the remaining cells 24 h after irradiation. The topical application of a large spectrum UVA/B filter before irradiation prevented these UV-induced alterations. In our hands, this model provides a promising tool to evaluate the sensitization potential of new compounds and to validate the efficacy of sunscreens to prevent UV-induced immunosuppression.

Ultraviolet A (320–400 nm) Modulation of Ultraviolet B (290–320 nm)-Induced Immune Suppression Is Mediated by Carbon Monoxide

Accumulating evidence suggests that suberythemogenic ultraviolet A (UVA) (320-400 nm) exposure protects against the immunosuppressive effect of ultraviolet B (290-320 nm) radiation or its epidermal photoproduct, cis-urocanic acid (cis-UCA). In skin, UVA photoimmunoprotection is mediated by the inducible antioxidant stress enzyme, heme oxygenase-1 (HO-1), which degrades heme into carbon monoxide (CO), iron, and biliverdin (reduced to bilirubin), and is important for cell survival under conditions of oxidative stress. The identity of the HO enzymatic product(s) that provide the immunoprotection is unknown. Here we examine the potential of CO to fulfill this role in hairless mouse skin, utilizing a novel CO-releasing molecule (CO-RM) to deliver CO to the skin topically. The CO-RM released CO gradually from the lotion vehicle during 3 h following its preparation, and between 50 and 500 microM, concentration-dependently protected mice against the suppression of contact hypersensitivity by either solar-simulated UV radiation (SSUVR) or cis-UCA, whereas aged CO-depleted CO-RM was inactive. Thus, the CO-RM treatment mimicked UVA-photoimmunoprotection, and identified HO-released CO as the protective mediator, providing evidence that the murine cutaneous immune system is modulated by this gaseous messenger. Preliminary evidence for involvement of guanylyl cyclase was obtained by treatment of the mouse with its specific inhibitor 1H-(1,2,4)oxadiazolo-(4,3-1)quinoxaline-1-one, which abrogated UVA photoimmunoprotection.

Sunscreen application at the beach

BACKGROUND

The sun protection factor (SPF) of sunscreens is determined after application of a standard amount. The European Cosmetic Toiletry and Perfumery Association (COLIPA) standard amount is 2 mg/cm(2). Real-life application of sunscreen is probably less than this.

AIM

To determine the amount of sunscreen present on the skin of people at the beach.

METHODS

Volunteers at the beach were selected randomly and were not aware of being tested for the adequacy of their sunscreen application. All volunteers had applied sunscreen. Application had been more than 30 min before testing (sometimes up to 4 h earlier). The amounts of sunscreen applied to different body sites were determined quantitatively by tape stripping. Actual amounts of sunscreen applied were compared with the COLIPA standard. Also, sunscreen containing a fluorescent dye was applied to the skin of volunteers in a laboratory setting. The distribution of sunscreen application was visualized by UVA photography in a darkened room.

RESULTS

Sixty volunteers, 33 males and 27 females, aged 17-68 years (median 32 years), were recruited at the beach. Sunscreen coverage was inadequate at all body sites. Coverage at various body sites differed greatly. Most volunteers had applied 10% or less of the COLIPA standard amount to all body sites assessed. The best protected areas were the upper arm and décolleté but, even in these areas, most volunteers had only applied 10% of the COLIPA standard amount. The worst protected areas were the ears and top of the feet. The back was typically badly protected if treated by the volunteers themselves. The back was better protected if another person had applied the sunscreen. In the laboratory, the fluorescent dye-containing sunscreen showed the same pattern of sunscreen application as at the beach.

CONCLUSIONS

In real life, at the beach, very little sunscreen remains present on the skin.