Relevant new insights into the effects of photoprotection in cutaneous lupus erythematosus

Cutaneous lupus erythematosus (CLE) denotes a heterogeneous spectrum of autoimmune diseases that primarily affect the skin. Ultraviolet irradiation (UV) is one of the most important environmental factors that can trigger skin lesions in CLE or even induce systemic organ manifestation. It has been shown that broad‐spectrum sunscreen with high sun protection factors can effectively prevent UV‐induced skin lesions in patients with different subtypes of CLE. In a recent issue of Experimental Dermatology, Zahn and colleagues demonstrate that potent photoprotection blocks disease‐specific skin lesions in CLE patients by reducing lesional tissue damage and interferon‐driven inflammation.     

Photoprotection: a Review of the Current and Future Technologies

Exposure to ultraviolet (UV) radiation is associated with a variety of harmful effects ranging from photoaging to skin cancer. UVB (290 to 320 nm) directly damages the cellular DNA leading to the formation of the 6-4 cyclobutane pyrimidine dimmers, and UVA (320 to 400 nm) indirectly damages the DNA via the production of oxygen radical species. In this review, we focused on the technological and scientific aspects of photoprotection using sunglasses and clothing while attempting to dispel some of the misconceptions. In addition to the basic knowledge relating to sunscreens, we reviewed the current guidelines for testing and labeling UVA protection around the world, controversies associated with nanoparticles, and future sunscreens actives waiting for the Food and Drug Administration approval. Lastly, we reviewed alternative agents, such as antioxidants, that can be used to supplement and augment photoprotection provided by sunscreens.     

Simplified method to substantiate SPF labeling for sunscreen products

BACKGROUND/PURPOSE: Worldwide, sunscreen sun protection factor (SPF) testing is based on 30-year-old technology. At the time the SPF test came into being, the highest SPFs available were in the 6-8 range. The SPF test is reasonably accurate for SPFs up to 15, but is much less reliable for measuring SPFs of 30 and higher. The method we propose addresses two primary reasons for this unreliability: 1) difficulties in applying products uniformly and 2) the subjectivity and variability of perception in evaluating and grading responses to UV doses. METHODS: Our proposed SPF substantiation method differs from the current SPF test in that sunscreen-protected test sites receive the same UV dose in four uniformly spaced sub-sites, which are graded as passing if no response is seen or failing if any response is seen. The response may be tanning, erythema, or a combination of both. To demonstrate the method, two commercial products with labeled SPFs of 30 and 45 and the P2 sunscreen standard were tested at two different laboratories. RESULTS: The SPF 30 product and SPF 15 standard were shown to be correctly labeled. However, it is questionable as to whether the SPF 45 product provides protection against 45 minimal erythema doses. CONCLUSIONS: Our proposed SPF substantiation method is not dependent on subjective evaluation of responses, accounts for non-uniform product application, and provides a conservative estimate of sunscreen protection. The method consists of a systematic repetition of identical tests that are considerably more rigorous than the current methods that are based on single data points per test subject. While the current SPF test remains necessary and valuable as a dose ranging tool, we propose that this SPF substantiation method supersede the old method for final SPF label determination.     

Randomized controlled community trial of the efficacy of a multicomponent stage-matched intervention to increase sun protection among beachgoers

BACKGROUND: Skin cancer is about as common as all other cancers combined and is preventable by sun protection. The most intense sun exposures often occur on the beach, so we chose this setting to test an intervention to affect sun protection behaviors. METHODS: We developed a multicomponent stage-matched intervention for beachgoers and evaluated its efficacy in a randomized trial for influencing stage of change and self-reported behavior. RESULTS: We randomized 2,324 persons ages 16 to 65 on the beach (83% of those approached). The intervention was effective in increasing self-reported sun protective behaviors. Effects were similar across gender and age groups. CONCLUSIONS; The beach is a good site for recruitment and intervention to prevent skin cancer in high-risk populations. Our stage-matched intervention package was effective for increasing sun protective behaviors.     

Modulation of ultraviolet (UV) transmission by emollients: relevance to narrowband UVB phototherapy and psoralen plus UVA photochemotherapy

BACKGROUND: Patients with psoriasis undergoing or about to undergo ultraviolet (UV) phototherapy and photochemotherapy often have thick scale on their plaques which can prevent the penetration of UV radiation. Emollients are used to moisturize the skin and to prevent or reduce some of the milder side-effects ('dryness', itching) sometimes experienced during UV therapy. However, emollients can alter the UV transmission of skin and thus may alter the clinical effects of phototherapy and photochemotherapy. OBJECTIVES: We tested 30 of the topical emollients in the British National Formulary (BNF) using a standard in vitro technique used to test sunscreens. We also surveyed U.K. phototherapy units to establish routine practice for emollient use in phototherapy and photochemotherapy. METHODS: We used a standard in vitro technique to measure the monochromatic protection factors (MPFs) of 30 non-bath emollients from the BNF. An application rate of 2 mg cm-2 was used. For the assessment of effects during narrowband UVB (TL-01) phototherapy, the mean of the protection factors at 310 and 315 nm was calculated; for psoralen plus UVA photochemotherapy the mean UVA protection factor was used. A questionnaire survey was used to assess routine practice concerning emollient use prior to phototherapies in phototherapy units throughout the U.K. RESULTS: In the UVA range, 17 of the 30 emollients gave protection factors of 1.2 or above. In the UVB range, 23 of 30 had an MPF of 1.2 or above. Yellow soft paraffin had the highest protection factor in the UVB range. Of 78 centres surveyed, 57 returned completed questionnaires (73%). Seventeen of 57 (30%) centres routinely used emollients immediately prior to administering phototherapy treatments. The remaining 40 of 57 (70%) did not. Forty-five (79%) responding centres recommended the use of emollients after phototherapy. CONCLUSIONS: This study has revealed considerable variability in the practice of emollient use before phototherapy treatments. Although the majority of centres included in this study did not routinely use emollients, almost one third did. Our in vitro measurement of 30 emollients revealed marked variation in UV transmission, with many emollients blocking sufficient UV to affect the response to therapy.     

In Vitro Human Epidermal and Polyethylene Membrane Penetration and Retention of the Sunscreen Benzophenone-3 from a Range of Solvents

Purpose. To study epidermal and polyethylene membrane penetration and retention of the sunscreen benzophenone-3 (BP) from a range of single solvent vehicles and evaluate solvent effects on permeability parameters. Methods. The solubility of BP was measured in a number of solvents. Penetration of BP across human epidermis and high density polyethylene (HDPE) membranes was studied from 50% saturated solutions in each solvent. Results. Maximal BP fluxes from the solvents across the two membranes varied widely. Highest fluxes were observed from 90% ethanol (EtOH) for epidermis and from isopropyl myristate (IPM) and C_12–15 benzoate alcohols (C_12–15 BA) for HDPE membrane. Both the flux and estimated permeability coefficient and skin-vehicle partitioning of BP appeared to be related to the vehicle solubility parameter (_v). The major effects of solvents on BP flux appear to be via changes in BP diffusivity through the membranes. Conclusions. Minimal penetration of sunscreens such as BP is best achieved by choosing vehicles with a _v substantially different to the solubility parameter of the membrane.     

UV-induced immune suppression and sunscreen

Sun protection factor (SPF) that measures sunscreen protection against erythema and edema may not be enough to measure a sunscreen's activity against many other biologic reactions induced by ultraviolet radiation (UV). It may be better to evaluate sunscreen efficacy using various tools including immune protection factor (IPF), mutation protection factor (MPF) and protection against photocarcinogenesis. In terms of immune protection, sunscreens protected against UV-induced immune suppression significantly. But protection in some cases was partial and often the IPF of sunscreens were less than the SPF. IPF may differ with various immunological endpoints, and it may be better to use a couple of different assays to measure sunscreen protection more objectively. Sunscreen use protects against most UV-induced non-melanoma skin cancers and actinic keratoses but its activity against melanoma is not clear. More studies with broad-spectrum stable sunscreens and better models for the investigation of malignant melanoma are required.     

镰形棘豆防晒霜对海训官兵日晒伤防护研究

目的观察镰形棘豆防晒霜对海训官兵日晒伤防治效果。方法采取整群抽样方法,分别对海上游泳和沙滩训练官兵进行防晒比较观察。海上游泳观察组于下海训练前将防晒霜涂抹短裤遮盖外的全部暴露部位,游泳2 h上岸休息时追加涂抹1次;沙滩训练观察组于训练前将防晒霜涂抹在体能服遮盖外的全部暴露部位。对照组未进行防护干预。比较训练期内观察组和对照组日晒伤的患病率及其晒伤程度。结果采集海上游泳观察组323例,对照组311例,观察组累积发生日晒伤78例(24.1%),对照组共发生日晒伤148例(41.1%),两组比较差异具有统计学意义(P<0.01)。沙滩训练观察组414例,对照组428例,观察组累积发生日晒伤80例(19.3%),对照组共发生日晒伤230例(53.7%),两组比较差异具有统计学意义(P<0.01)。日晒伤严重程度比较,海上游泳观察组Ⅰ度晒伤77例(23.8%)、Ⅱ度1例(0.3%),对照组Ⅰ度晒伤122例(39.2%)、Ⅱ度6例(1.9%),两组比较差异具有统计学意义(P<0.01)。沙滩训练观察组Ⅰ度晒伤79例(19.1%)、Ⅱ度1例(0.2%),对照组Ⅰ度晒伤213例(49.8%)、Ⅱ度17例(4.0%),两组比较差异具有统计学意义(P<0.01)。结论镰形棘豆防晒霜具有防水、防晒及减轻晒伤程度的作用。