Sunscreens and the photodermatoses

Molecular photoprotection of human keratinocytes in vitro by the naturally occurring mycosporine-like amino acid palythine

Background

Solar ultraviolet radiation (UVR) induces molecular and genetic changes in the skin, which result in skin cancer, photoageing and photosensitivity disorders. The use of sunscreens is advocated to prevent such photodamage; however, most formulations contain organic and inorganic UVR filters that are nonbiodegradable and can damage fragile marine ecosystems. Mycosporine‐like amino acids (MAAs) are natural UVR‐absorbing compounds that have evolved in marine species for protection against chronic UVR exposure in shallow‐water habitats.

Objectives

To determine if palythine, a photostable model MAA, could offer protection against a range of UVR‐induced damage biomarkers that are important in skin cancer and photoageing.

Methods

HaCaT human keratinocytes were used to assess the photoprotective potential of palythine using a number of end points including cell viability, DNA damage (nonspecific, cyclobutane pyrimidine dimers and oxidatively generated damage), gene expression changes (linked to inflammation, photoageing and oxidative stress) and oxidative stress. The antioxidant mechanism was investigated using chemical quenching and Nrf2 pathway activation assays.

Results

Palythine offered statistically significant protection (P < 0·005) against all end points tested even at extremely low concentrations (0·3% w/v). Additionally, palythine was found to be a potent antioxidant, reducing oxidatively generated stress, even when added after exposure.

Conclusions

Palythine is an extremely effective multifunctional photoprotective molecule in vitro that has potential to be developed as a natural and biocompatible alternative to currently approved UVR filters.

What's already known about this topic?

Mycosporine‐like amino acids (MAAs) are photoprotective molecules found in marine organisms but there are few data on their ability to protect skin cells from the adverse effects of solar ultraviolet radiation (UVR).

The European Chemicals Agency (ECHA) is concerned about the potential adverse health and ecotoxic effects of eight of 16 commonly used sunscreen filters in Europe. The Environmental Effects Assessment Panel (EEAP) of the United Nations Environment Programme has expressed similar concerns.

What does this study add?

Palythine, an MAA extracted from an edible seaweed, affords photoprotection against a wide range of adverse effects in HaCaT keratinocytes exposed to solar simulating and ultraviolet A radiation. Of note is protection against two types of DNA photolesions; cyclobutane pyrimidine dimers and 8‐oxo‐7,8‐dihydroguanine.

Palythine is also a potent antioxidant that offers protection even when added after UVR exposure.

What is the translational message?

MAAs should be considered for development as natural biocompatible sunscreens that may address the concerns of the ECHA and EEAP.

Linked Comment: https://doi.org/10.1111/bjd.16598.

https://goo.gl/Uqv3dl

Sunscreens: a review of health benefits, regulations, and controversies

Ultraviolet radiation plays a major role in the development of nonmelanoma and melanoma skin cancers. Photoprotection by sunscreens has been shown to prevent the development of actinic keratosis, squamous cell carcinoma, melanoma, and photoaging. However, these benefits are only derived if the users apply sunscreen appropriately and practice other sun protection measures. This review discusses the health benefits provided by sunscreen use, updates the latest regulatory landscape on sunscreen, and addresses the controversies and limitations associated with sunscreen use.

Erythropoietic protoporphyria: spectrum of three cases

BACKGROUND

Erythropoietic protoporphyria is a rare photodermatosis of childhood, and the diagnosis can be delayed. A deficient ferrochelatase enzyme leads to accumulation of protoporphyrins in the dermis, causing phototoxic burning.

OBJECTIVE

To report three cases with great variability in severity of symptoms and age at diagnosis. We discuss clinical and biochemical findings, mutation analysis, and therapeutic options.

METHODS

We report three cases with different degrees of photosensitivity, laboratory results, psychosocial impact, and preventive and therapeutic treatments.

RESULTS

The diagnosis of erythropoietic protoporphyria was confirmed by both typical elevation of plasma porphyrins and the discovery of a mutated FECH gene.

CONCLUSION

Erythropoietic protoporphyria should be suspected in any cases of childhood photosensitivity. Systemic complications are unusual. Mutation analysis confirms the diagnosis. Photoprotection is the cornerstone of treatment.

Mucocutaneous manifestations of Epstein-Barr virus infection

This review focuses on Epstein-Barr virus (EBV) infection, diagnosis, and current treatment, with emphasis on EBV-associated mucocutaneous manifestations in primary infections, acute EBV-associated syndromes, chronic infections, lymphoproliferative disorders, and lymphomas. In primary infection, EBV infects B cells and can cause mucocutaneous manifestations in infectious mononucleosis or acute EBV-associated syndromes such as Gianotti-Crosti syndrome and hemophagocytic syndrome. EBV then persists in the majority of humans generally without causing disease. In some cases, however, latent EBV infection may result in diseases such as hydroa vacciniforme, hypersensitivity to mosquito bites, and lymphoproliferative disorders such as plasmablastic lymphoma, oral hairy leukoplakia, and post-transplant lymphoproliferative disorders, particularly in immunocompromised patients. Latent EBV infection has also been implicated in a variety of malignant conditions such as Burkitt lymphoma, Hodgkin lymphoma, nasopharyngeal carcinoma, and Kikuchi histocytic necrotizing lymphadenitis. Since the immune system is critical in preventing the progression of EBV disease, the immunologic status of the patient plays a crucial role in the subsequent development of pathologies.

Sunscreen use in photodermatoses

Photodermatoses are relatively uncommon, but most dermatologists will have to diagnose and treat them at some point. This article highlights several photodermatoses, their common symptoms and possible. Unfortunately, sunscreens marketed in the United States do not presently contain agents that are effective against longer wavelengths. There are agents available in other countries that offer better protection. It is hypothesized that these products will soon be available in the United States. Until such time, clinicians should recommend agents with avobenzones, benzophenones, and the physical blockers titanium oxides. Two other agents, dihydroxyacetone and iron oxide, may also offer benefit in some of these patients.

Management of polymorphous light eruption : clinical course, pathogenesis, diagnosis and intervention

Optimal management of patients with polymorphous light eruption (PLE), the most frequent photodermatosis, requires knowledge of the individual clinical course of the disease and pathogenic factors. As PLE often causes problems during leisure-time activities and holidays, resulting in a substantial loss of quality of life, prophylaxis is the most important therapeutic approach. Management of PLE must, therefore, focus on basic preventative measures and additional therapeutic approaches, depending on the clinical condition. PLE can be classified into four severity groups (mild, moderate-to-severe, severe and therapy-resistant), which are useful for determining appropriate prophylactic measurements. No specific laboratory tests are available for the diagnosis of PLE, therefore, a clinician must rely on the clinical appearance of the disorder (e.g. clinical symptoms, the location of the lesions, the relationship of the occurrence of the lesions with sun exposure and the time course of the lesions) as well as a patient's medical history in order to make a diagnosis. Basic preventative management of PLE consists of adequate sun protection comprising avoidance of sun exposure, the use of textile sun protection and the application of broadband sunscreens with high UVA protection potential. Other supportive measurements have to be managed individually and are dependent on the patient's medical history and the severity of the disease. Topical antioxidants, systemic immunomodulation, photo(chemo)therapy and systemic immunosuppression may be required in some cases of PLE. Topical antioxidants represent a new treatment approach for moderate-to-severe PLE and are an effective and well tolerated option for this patient population. Severe PLE also requires photo(chemo)therapy. Phototherapy can be in the form of 311 nm UVB or UVA1 irradiation. In cases where 311 nm UVB or UVA1 are ineffective, psoralen plus UVA (PUVA) bath therapy may be used. However, PUVA bath therapy must be used with caution because it is associated with acute and long-term adverse effects. In rare exceptions we would consider using oral PUVA therapy. However, in our outpatient department, quality of life of most patients is improved with the treatment regimens that are recommended for patients with moderate-to-severe PLE, without the need for photo(chemo)therapy.