UV‐induced immune suppression and sunscreen

Abstract

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 T he sun emits a wide range of ultraviolet (UV) radiation. All of the harmful UVC (200-280 nm) and most of UVB (280-320 nm) is absorbed by the stratospheric ozone layer. Stratospheric ozone does not affect UVA (320-400 nm) transmission. As the stratospheric ozone layer is depleted (1) the amount of harmful shortwave UV reaching the earth's surface will increase. On the other hand, chances of UV exposure by increased outdoor activity and imprudent use of sun tanning machines increased the risks of unwanted UV effects, such as sunburn, photoaging, skin cancer induction and immune suppression (2). Solar UV is the most prominent cause of skin cancer, a cancer that is the most common cancer found in Caucasian populations. During photocarcinogenesis, UV works as both an initiator by directly damaging DNA and as a promotor by suppressing immunologic rejection (3).Sunscreen use has been promoted as one way to prevent these harmful consequences of UV exposure. The ability of a sunscreen to protect against erythema, the so-called SPF, although well characterized may not be an adequate measure of a sunscreen's ability to protect against other biological endpoints, particularly immune suppression (4). Although there are many examples in the scientific literature regarding sunscreen protection against UV-in-101 may be better to use a couple of different assays to measure sunscreen protection more objectively. Sunscreen use protects against most UV-induced nonmelanoma 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.

In vivo evaluation of the protective capacity of sunscreen by monitoring urocanic acid isomer in the stratum corneum using Raman spectroscopy

“…A variety of approaches have confirmed that UCA isomerization can be considered as an initiator of the complex pathway leading to immune suppression (1–3). Isomers of UCA in the skin have been determined by high‐performance liquid chromatography (HPLC) using the suction blister fluid (17), epidermal alkaline extract (18–22), or SC collected from adhesive tape (5, 20, 23).…”

“…The most frequent photoproducts are cycrobutane pyrimidine dimers and photoproducts. These DNA damages may induce cytokine dysregulation and immune suppression through the release of immune suppressive cytokines (1)(2)(3). UCA is another chromophore in the stratum corneum (SC).…”

“…Since this study, a variety of approaches have confirmed this hypothesis. Evidences showed that cis-UCA can mediate some of the immunosuppressive effects of UV irradiation on the immune system, but the mechanism of action of cis-UCA remains unclear, and whether it initiates events at the site of isomerization in the skin or more systemically is still unknown (1)(2)(3). We are interested in studying the t-UCA to cis-UCA transition as it plays important roles in UV-induced immune suppression.…”

Zeolite Encapsulation Decreases TiO2-photosensitized ROS Generation in Cultured Human Skin Fibroblasts†

“…UVR‐induced skin effects include acute responses such as sunburn, pigmentation, hyperplasia, immunosuppression and vitamin D synthesis, and chronic effects, primarily photocarcinogenesis and photoaging (3–6). UVA wavelengths penetrate more deeply into the skin and are, therefore, more responsible than UVB for photoaging, wrinkling of the skin, and the formation of skin cancer.…”

Sunscreen: A catch-22

“…[1] The high-energy UV radiation that reaches us can ultimately cause visible sunburn of Nanotechnology the skin, erythema, photoaging, immunosupression, and photocarcinogenesis, among other adverse effects. [2] To prevent these adverse effects, sunscreens contain light-absorbing organic filters as well as lightreflecting and light-scattering inorganic nanoparticle filters. A combination of these two types of UV filters is necessary for broad-spectrum protection over the UVB and UVA ranges.…”