Randomized controlled trial of oral omega-3 PUFA in solar-simulated radiation-induced suppression of human cutaneous immune responses
From Dermatological Sciences, Institute of Inflammation and Repair, School of Translational Medicine, University of Manchester, Manchester Academic Health Science Centre, Salford Royal National Health Service Foundation Hospital, Manchester, United Kingdom. American Journal of Clinical Nutrition
(Impact Factor: 6.77).
01/2013; 97(3). DOI: 10.3945/ajcn.112.049494
BACKGROUND: Skin cancer is a major public health concern, and the majority of cases are caused by solar ultraviolet radiation (UVR) exposure, which suppresses skin immunity. Omega-3 (n-3) PUFAs protect against photoimmunosuppression and skin cancer in mice, but the impact in humans is unknown. OBJECTIVES: We hypothesized that EPA-rich n-3 PUFA would abrogate photoimmunosuppression in humans. Therefore, a nutritional study was performed to assess the effect on UVR suppression of cutaneous cell-mediated immunity (CMI) reflected by nickel contact hypersensitivity (CHS). DESIGN: In a double-blind, randomized controlled study, 79 volunteers (nickel-allergic women, 22-60 y old, with phototype I or II) took 5 g n-3 PUFA-containing lipid (70% EPA plus 10% DHA) or a control lipid daily for 3 mo. After supplementation, nickel was applied to 3 skin sites preexposed on 3 consecutive days to 1.9, 3.8, or 7.6 J/cm(2) of solar-simulated radiation (SSR) and to 3 unexposed control sites. Nickel CHS responses were quantified after 72 h and the percentage of immunosuppression by SSR was calculated. Erythrocyte [red blood cell (RBC)] EPA was measured by using gas chromatography. RESULTS: SSR dose-related suppression of the nickel CHS response was observed in both groups. Photoimmunosuppression appeared less in the n-3 PUFA group than in the control group (not statistically significant [mean difference (95% CI): 6.9% (-2.1%, 15.9%)]). The difference was greatest at 3.8 J/cm(2) SSR [mean difference: 11% (95% CI: 0.5%, 21.4%)]. Postsupplementation RBC EPA was 4-fold higher in the n-3 PUFA group than in the control group (mean difference: 2.69% (95% CI: 2.23%, 3.14%), which confirmed the EPA bioavailability. CONCLUSION: Oral n-3 PUFAs appear to abrogate photoimmunosuppression in human skin, providing additional support for their chemopreventive role; verification of study findings is required. This trial was registered at clinicaltrials.gov as NCT01032343.
Available from: Peter S Friedmann
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ABSTRACT: Skin cancer is a major public health concern and the primary aetiological factor in the majority of skin cancers is UVR exposure. Ultraviolet radiation not only induces potentially mutagenic DNA damage, but also suppresses cell mediated immunity (CMI), allowing cancerous cells to escape destruction and progress to tumours. A considerable proportion of an individual's annual sun exposure is obtained outside the vacation period when topical and physical measures for photoprotection are irregularly used. Certain nutrients could provide an adjunctive protective role and evidence is accruing from experimental studies to support their use in abrogation of photoimmunosuppression. Moreover, developments in clinical research methods to evaluate impact of solar simulated radiation on cutaneous CMI allow the immune protective potential of nutritional agents to be examined in humans in vivo. This article summarises the mediation of CMI and its suppression by UVR, evaluates the methodology for quantitative assessment in vivo, reviews the human studies reported on nutritional abrogation of photoimmunosuppression including recent randomised controlled trials, and discusses the mechanisms of photoprotection by the nutrients. This includes, in addition to antioxidants, novel studies of omega-3 polyunsaturated fatty acids and nicotinamide.
Available from: onlinelibrary.wiley.com
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ABSTRACT: Photoprotection can be provided not only by UV blockers, but also by oral substances. Epidemiologically identified associations between foods and skin cancer and experimental intervention experiments have discovered mechanisms of UV skin damage. These approaches have identified oral substances that are photoprotective in humans. UV inhibits ATP production causing an energy crisis, which prevents optimal skin immunity and DNA repair. Enhancing ATP production with oral nicotinamide protects from UV immunosuppression, enhances DNA repair, and reduces skin cancer in humans. Reactive oxygen species also contribute to photodamage. Nontoxic substances consumed in the diet, or available as oral supplements, can protect the skin by multiple potential mechanisms. These substances include polyphenols in fruit, vegetables, wine, tea and caffeine containing foods. UV-induced prostaglandin E2 (PGE2 ) contributes to photodamage. Non-steroidal anti-inflammatory drugs and food substances reduce production of this lipid mediator. Fish oils are photoprotective, at least partially by reducing PGE2 . Orally consumed substances, either in the diet, or as supplements, can influence cutaneous responses to UV. A current research goal is to develop an oral supplement that could be used in conjunction with other sun protective strategies in order to provide improved protection from sunlight.
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ABSTRACT: Eicosapentaenoic acid (EPA), abundant in oily fish, is reported to reduce skin inflammation and provide photoprotection, potential mechanisms include competition with arachidonic acid (AA) for metabolism by cyclooxygenases/lipoxygenases to less pro-inflammatory mediators. We thus examine impact of EPA intake on levels of AA, EPA and their resulting eicosanoids in human skin with or without ultraviolet radiation (UVR) challenge.
In a double-blind randomised controlled study, 79 females took 5 g EPA-rich or control lipid for 12 wk. Pre- and post-supplementation, red blood cell and skin polyunsaturated fatty acids were assessed by GC, and eicosanoids from unexposed and UVR-exposed skin by LC-MS/MS. Active supplementation increased red blood cell and dermal EPA versus control (both p < 0.001), lowering relative AA:EPA content (4:1 versus 15:1 and 5:1 versus 11:1, respectively; both p < 0.001). Pre-supplementation, UVR increased PGE2 , 12-hydroxyeicosatetraenoic acids, 12-HEPE (all p < 0.001) and PGE3 (p < 0.05). Post-EPA, PGE2 was reduced in unchallenged skin (p < 0.05) while EPA-derived PGE3 (non-sign) and 12-HEPE (p < 0.01) were elevated post-UVR. Thus, post-EPA, PGE2 :PGE3 was lower in unchallenged (12:1 versus 28:1; p < 0.05) and UVR exposed (12:1 versus 54:1; p < 0.01) skin; 12-hydroxyeicosatetraenoic acids:12-HEPE was lower in UVR-exposed skin (3:1 versus 11:1; p < 0.001).
Dietary EPA augments skin EPA:AA content, shifting eicosanoid synthesis towards less pro-inflammatory species, and promoting a regulatory milieu under basal conditions and in response to inflammatory insult.
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