Differential modulation of inflammatory markers in plasma and skin after single exposures to UVA or UVB radiation in vivo

Abstract

Background. Solar light generates inflammatory responses in exposed skin. These effects are generally attributed to UVB light. However, skin is exposed to a huge quantum of UVA photons as UVA is a predominant part of sunlight and the radiation used in tanning beds. We examined the effects of a single exposure to UVA and UVB wavebands on cytokine levels in skin and plasma, myeloperoxidase (MPO) activity, expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) in skin. Methods. Hairless mice were irradiated with either UVA (10 or 20 J/cm 2 ) or UVB (200 or 800 mJ/cm 2 ). The effects were assessed after 4/24 h. Plasma cytokine levels were evaluated using a Bio-Plex cytokine assay. Cytokine, iNOS and COX-2 levels in skin were determined by Western blot. Skin MPO activity was monitored spectrophotometrically. Results. UVB induced up-regulation of interleukin-1β (IL-1β) and interleukin-6 (IL-6) and decrease in interleukin-10 (IL-10) mainly after 4 h. In contrast, UVA caused increase in levels of tumor necrosis factor-alpha (TNF-α) and IL-6 after 4 h and up-regulated IL-10 and interleukin-12 (IL-12) after 24 h. The increase in MPO activity from infiltrated leucocytes was observed only in UVB irradiated animals. iNOS was up-regulated 4 h after UVA and UVB treatment. No significant effect on COX-2 expression was detected. Conclusions. UVA and UVB light affected several inflammatory markers. For individual waveband, changes in plasma parameters did not correlate with those in skin. Thus evaluation of plasma samples cannot simply be replaced by determination in skin specimens and vice versa.

Photosensitivity of murine skin greatly depends on the genetic background: clinically relevant dose as a new measure to replace minimal erythema dose in mouse studies

“…This may explain the high level of IL‐1 β in our setting. Proinflammatory cytokines reach their near‐maximum levels between 24 and 48 h. Our findings confirmed what others reported, a similar changes of cytokine expressions levels were found, yet no firm conclusion may be drawn because of the diversity of irradiation and assessment methods used previously . We observed a significant elevation of IL‐1 β in each genotype and IL‐6 in C57BL/6 mice at higher UVB doses that proves their fundamental role in acute UVB‐mediated inflammation.…”

“…After a single UV irradiation, an inflammatory cascade is initiated that includes oxidative stress, sunburn cell formation and activation of keratinocytes, fibroblasts, mast cells and neutrophils. At subcellular level a variety of proinflammatory mediators, cytokines, prostaglandins, nitric oxide, eicosanoids, COX‐2 are upregulated . This wide range of molecular and cellular damages in the epidermis and dermis are initiated even before the erythema becomes visible.…”

Effects of Long-Term Storage Time and Original Sampling Month on Biobank Plasma Protein Concentrations

“…The lack of significant associations with monthly sun hours could be attributed to a number of factors. Although UV-radiation have previously been shown to directly affect the circulating levels of plasma proteins (Vostalova et al, 2013, Reichert et al, 2015), the sun hours are likely to be viewed as a proxy variable to other seasonal changes such as blooming or pollen levels which in turn triggers the immune system, or various forms of changes in lifestyle such as seasonal intakes of food and changes in habits of physical activity. The number of sun-hours per month available from the SMIHI is also an average over the past 30 years and the actual sun-hours at the individual sampling dates could differ from the used number.…”

“…UV-radiation causes inflammatory responses in the skin and several cytokines are affected by UV-radiation. Specifically, production of C-X-C motif chemokine ligand 5 (CXCL5) have been shown to be up-regulated in human skin (Reichert et al, 2015) in response to UV-radiation and changes in plasma levels of several interleukins have been shown in vivo in mouse models (Vostalova et al, 2013), suggesting that seasonal variation is likely to be measurable in human plasma. In order to investigate the effect of storage time in freezer, chronologic age at sampling, sampling month, and season (sunlight), we determined the abundance level of 122 plasma proteins using the Protein Extension Assay (PEA) in 106 women sampled at 380 occasions spanning from 1988 to 2014.…”

Caffeic Acid Inhibits UVB‐induced Inflammation and Photocarcinogenesis Through Activation of Peroxisome Proliferator‐activated Receptor‐γ in Mouse Skin

“…A variety of phytochemicals, mostly dietary phenolic substances, have been reported to possess UV absorbing sunscreen properties as well as anti‐inflammatory and chemopreventive activities at the molecular level, which are important for suppression of the adverse biological effects of solar photons . Caffeic and ferulic acids are two hydroxycinnamic acids largely present in plants and also in vegetable foods, such as olives and olive oil.…”