The majority of skin cancers are caused by over exposure to ultraviolet (UV) radiation. The effects of UV radiation on the expression of drug transporters expressed in human skin has never been studied. In this the effects of UVA and UVB irradiation on the expression of ATP-binding cassette (ABC) transporters and Solute carrier (SLC) transporters was evaluated in normal human epidermal keratinocytes (NHEK) and normal human dermal fibroblasts (NHDF) in primary culture. First experiments were intended to validate the inflammatory reaction in response to stimulation by lipopolysaccharide (LPS) in NHEK, NHDF and 3D-reconstructed human epidermis (3D-RHE) model. LPS treatment has shown to increase the expression of IL-8 and TNF-alpha in all three in vitro models. Expression of the most expressed ABC and SLC transporters was then measured in NHEK and NHDF after UVA (30 J/m²) and UVB (40 mJ/m²) irradiation. The most striking result was a significant 29-fold increase of the expression of SLCO4A1 in normal human dermal fibroblasts. In summary, this study shows for the first time a significant regulation of the expression of SLCO4A1 in human dermal fibroblasts induced by UVA irradiation. This finding is of particular interest as most of skin cancers are caused by over exposure to ultraviolet radiation and need to be considered in pharmacokinetic evaluation of topical drugs.

Ferulic acid (FA) is known for its excellent antioxidant properties that can provide a lot of health benefits. One of its drawbacks is being unstable under UVA light that limits its potency. In this study, new peptides LW2 (QNKRFYFRKNQ) and CW2 (a cyclic form of LW2) have been designed based on bovine serum albumin site ⅡA conformation. UVA irradiation experiment was performed to investigate the protective ability of these peptides towards FA against UVA damage. The percentage of FA remaining under UV irradiation by the protection of CW2 and LW2 was 83%, 76% respectively. The results showed the importance of the cationic residues and hydrophobic residues included in the peptide sequences. Moreover, the cyclic rigid structure showed more protecting ability over that of the linear counterpart.

UVA radiation inducing oxidative stress is harmful for the skin cells. The most sensitive are dermal fibroblasts. Exposure of the cells to prolonged UVA radiation induces apoptosis. Although, skin cells have a number of defense mechanisms that protect them against UV-induced oxidative stress, they are insufficient during long-lasting UV exposure. Therefore, there is a need for effective skin protection compounds with cytoprotective and antioxidant properties. One of their sources is Amaranthus cruentus L. seed oil, rich in unsaturated fatty acids, squalene, vitamin E derivatives, and phytosterols. The aim of this study was to evaluate whether Amaranthus cruentus seed oil evokes protective effect on the apoptosis stimulated by UVA radiation in human skin fibroblasts. UVA radiation at an applied dose of 10 J/cm2 caused a significant reduction in the survival of human skin fibroblasts and directed them into apoptosis pathway. Increased expression of p53, caspase 3, and caspase 9 and PARP proteins in UVA-treated fibroblasts suggests the intrinsic mechanism of apoptosis. The application of Amaranthus cruentus seed oil at 0.1% and 0.15% concentrations to UVA-treated cells decreased the expression of these proteins, which was accompanied by increased cell survival. Similarly, the UVA-dependent decrease in expression of p-Akt and mTOR proteins was restored, under the effect of studied oil. The molecular mechanism of this phenomenon is related to the stimulation of antioxidant processes through activation of Nrf2. This suggests that Amaranthus cruentus seed oil stimulate the antioxidant system in fibroblast cells and prevent the effects of UVA-induced oxidative stress and may find application in pharmacy and cosmetology as a sun- protective substance.

The effect of Amaranthus cruentus L. seed oil (AmO) on collagen biosynthesis and wound healing was studied in cultured human dermal fibroblasts exposed to UVA radiation. It has been found that UVA radiation inhibited collagen biosynthesis, prolidase activity, expression of β1-integrin receptor, phosphorylated ERK1/2 and TGF-β, while increased the expression of p38 kinase. The AmO at 0.05-0.15% counteracted the above effects induced by UVA radiation in fibroblasts. UVA radiation also induced the expression and nuclear translocation of pro-inflammatory NF-κB fac-tor and enhanced the COX-2 expression. AmO effectively suppressed the expression of these pro-inflammatory factors induced by UVA radiation. Expressions of β1 integrin and IGF-I re-ceptors were decreased in the fibroblasts exposed to UVA radiation, while AmO counteracted the effects. Furthermore, AmO stimulated fibroblast’s migration in a wound healing model, thus facilitating the repair process following exposure of fibroblasts to UVA radiation. This data suggest the potential of AmO to counteract UVA-induced skin damage.

Background: Skin is exposed to ultraviolet radiation (UV) and air pollution and recent works demonstrated these factors have additive effects in the disturbance of skin homeostasis. Nuclear factor erythroid 2-related factor 2 (Nrf2) and aryl hydrocarbon receptor (AHR) appears appropriate targets in the management of combined environmental stressors. The protective effects of Silymarin (SM), an antioxidant and anti-inflammatory complex of flavonoids, were evaluated. Methods: Reactive oxygen species (ROS) and interleukin 1-alpha (IL-1a) were quantified in UV+urban dust stressed reconstructed human epidermis (RHE) treated with SM. Gene expression study was conducted on targets related to AHR and Nrf2. SM agonistic activity on cannabinoid receptor type 2 (CB2R) was evaluated on mast cells. Clinical study quantified the performance of SM and cannabidiol (CBD), in skin exposed to solar radiation and air pollution. Results: SM decreased morphological alterations, ROS and IL-1a in UV+urban dust stressed RHE. AHR and Nrf2 related genes were upregulated that control antioxidant effector and barrier function. Interleukin 8 gene expression was decreased. Clinical study confirmed SM to improve homogeneity and perceived well-being of urban skins exposed to UV, outperforming CBD. SM activated CB2R and release of β-endorphin from mast cells. Conclusions: SM provides protection of skin from oxidative stress and inflammation caused by two major factors of exposome and appears mediated by AHR-Nrf2. SM activation of CB2R opens a new understanding of SM anti-inflammatory properties.

The Absorbing/scattering nature of aerosols affects the total radiative forcing and this absorption to total extinction ratio is quantified by single scattering albedo (SSA). Effect of SSA in the Ultraviolet (UV) irradiance is less studied and limited measurements are available. SSA retrieved at Athens, Greece during 2009-2014 from Ultraviolet Multifilter Radiometer (UVMFR) at 332 and 368 nm, were used to calculate incoming UV irradiance, alongside with ones from AERONET at visible wavelengths, from OMI satellite at 342.5 nm and from AEROCOM climatological database at 300 nm. UVA and UVB irradiances were estimated using a Radiative Transfer Model and we found that relative differences could be as high as 20%, while average relative differences varied from 2% to 8.7 % for the whole experimental period. Both UVA and UVB drop by a rate of ~12% for 0.05 aerosol absorption optical depth compared to ones estimated using SSA at visible range. Brewer irradiance measurements at 324nm were used to validate simulated irradiances and a better agreement was found when UVMFR SSAs were used with an average difference of 0.86%, while when using visible or climatological input, relative differences were estimated +4.91 and +4.15% accordingly.