Epidermal trans-urocanic acid and the UV-A-induced photoaging of the skin

Non-invasive Microneedle Application Increases Ceramide and Natural Moisturizing Factors in a Reconstructed Human Skin Model

Recently, microneedling as a cosmetic product has attracted attention as one way to improve skin barrier function and moisturizing function to reduce wrinkle formation. However, some cases of erythema and edema have been reported as side effects. In order to develop safer microneedle cosmetics, we investigated whether microneedles can improve skin barrier function and moisturizing function even when applied in a non-invasive manner that does not penetrate the stratum corneum. We established the condition of non-penetrating microneedle application on reconstructed human full-thickness skin models and examined the effect on the skin models when microneedles were applied under this condition. Microneedle application increased the gene expression of serine palmitoyltransferase long chain base subunit (SPTLC) 3, filaggrin, and transglutaminase 1. The amount of ceramide produced by SPTLC was also increased by microneedle application. Gene expression of filaggrin-degrading enzymes and the amount of free amino acids, a product of filaggrin degradation, were also increased by microneedling. These results suggest that non-invasive microneedle application can improve skin barrier function and moisturizing function by increasing the amount of ceramide and natural moisturizing factors.

Impact of acute stress on murine metabolomics and metabolic flux

Plasma metabolite concentrations and labeling enrichments are common measures of organismal metabolism. In mice, blood is often collected by tail snip sampling. Here, we systematically examined the effect of such sampling, relative to gold-standard sampling from an in-dwelling arterial catheter, on plasma metabolomics and stable isotope tracing. We find marked differences between the arterial and tail circulating metabolome, which arise from two major factors: handling stress and sampling site, whose effects were deconvoluted by taking a second arterial sample immediately after tail snip. Pyruvate and lactate were the most stress-sensitive plasma metabolites, rising ~14 and ~5-fold. Both acute handling stress and adrenergic agonists induce extensive, immediate production of lactate, and modest production of many other circulating metabolites, and we provide a reference set of mouse circulatory turnover fluxes with noninvasive arterial sampling to avoid such artifacts. Even in the absence of stress, lactate remains the highest flux circulating metabolite on a molar basis, and most glucose flux into the TCA cycle in fasted mice flows through circulating lactate. Thus, lactate is both a central player in unstressed mammalian metabolism and strongly produced in response to acute stress.

5-Deazaalloxazine as photosensitizer of singlet oxygen and potential redox-sensitive agent

Flavins are a unique class of compounds that combine the features of singlet oxygen generators and redox-dependent fluorophores. From a broad family of flavin derivatives, deazaalloxazines are significantly underdeveloped from the point of view of photophysical properties. Herein, we report photophysics of 5-deazaalloxazine (1a) in water, acetonitrile, and some other solvents. In particular, triplet excited states of 1a in water and in acetonitrile were investigated using ultraviolet-visible (UV-Vis) transient absorption spectroscopy. The measured triplet lifetimes for 1a were all on the microsecond time scale (≈ 60 μs) in deoxygenated solutions. The quantum yield of S₁ → T₁ intersystem crossing for 1a in water was 0.43 based on T₁ energy transfer from 1a to indicaxanthin (5) acting as acceptor and on comparative actinometric measurements using benzophenone (6). 1a was an efficient photosensitizer for singlet oxygen in aerated solutions, with quantum yields of singlet oxygen in methanol of about 0.76, compared to acetonitrile ~ 0.74, dichloromethane ~ 0.64 and 1,2-dichloroethane ~ 0.54. Significantly lower singlet oxygen quantum yields were obtained in water and deuterated water (Ф_Δ ~ 0.42 and 0.44, respectively). Human red blood cells (RBC) were used as a cell model to study the antioxidant capacity in vitro and cytotoxic activity of 1a. Fluorescence-lifetime imaging microscopy (FLIM) data were analyzed by fluorescence lifetime parameters and distribution for different parts of the emission spectrum. Comparison of multidimensional fluorescent properties of RBC under physiological-like and oxidative-stress conditions in the presence and absence of 1a suggests its dual activity as probe and singlet-oxygen generator and opens up a pathway for using FLIM to analyze complex intracellular behavior of flavin-like compounds. These new data on structure-property relationship contribute to the body of information required for a rational design of flavin-based tools for future biological and biochemical applications.

Microbiota, Oxidative Stress, and Skin Cancer: An Unexpected Triangle

Mounting evidence indicates that the microbiota, the unique combination of micro-organisms residing in a specific environment, plays an essential role in the development of a wide range of human diseases, including skin cancer. Moreover, a persistent imbalance of microbial community, named dysbiosis, can also be associated with oxidative stress, a well-known emerging force involved in the pathogenesis of several human diseases, including cutaneous malignancies. Although their interplay has been somewhat suggested, the connection between microbiota, oxidative stress, and skin cancer is a largely unexplored field. In the present review, we discuss the current knowledge on these topics, suggesting potential therapeutic strategies.

The Discovery and Function of Filaggrin

Keratohyalin granules were discovered in the mid-19th century in cells that terminally differentiate to form the outer, cornified layer of the epidermis. The first indications of the composition of these structures emerged in the 1960s from a histochemical stain for histidine, followed by radioautographic evidence of a high incidence of histidine incorporation into newly synthesized proteins in cells containing the granules. Research during the next three decades revealed the structure and function of a major protein in these granules, which was initially called the ‘histidine-rich protein’. Steinert and Dale named the protein ‘filaggrin’ in 1981 because of its ability to aggregate keratin intermediate filaments. The human gene for the precursor, ‘profilaggrin,’ was reported in 1991 to encode 10, 11 or 12 nearly identical repeats. Remarkably, the mouse and rat genes encode up to 20 repeats. The lifetime of filaggrin is the time required for keratinocytes in the granular layer to move into the inner cornified layer. During this transition, filaggrin facilitates the collapse of corneocytes into ‘building blocks’ that become an impermeable surface barrier. The subsequent degradation of filaggrin is as remarkable as its synthesis, and the end-products aid in maintaining moisture in the cornified layer. It was apparent that ichthyosis vulgaris and atopic dermatitis were associated with the absence of this protein. McLean’s team in 2006 identified the cause of these diseases by discovering loss-of-function mutations in the profilaggrin gene, which led to dysfunction of the surface barrier. This story illustrates the complexity in maintaining a healthy, functional epidermis.

Polylactic acid based Janus membranes with asymmetric wettability for directional moisture transport with enhanced UV protective capabilities

Efficient directional moisture transport can remove excess sweat away from the human body and keep the body dry; fully utilizing this functionality to improve the wearing experience is urgently needed in the area of functional textiles. Herein, a facile strategy is used to design an eco-friendly and biodegradable PLA membrane with enhanced directional moisture transport and UV protection abilities. The PLA-based Janus membrane with asymmetric wettability is fabricated via sol-gel and electrospinning methods. Titanium dioxide nanoparticles (TiO2) were anchored onto the surface of the PLA fabric during the TiO2 sol-gel fabrication process using polydopamine, forming superhydrophilic TiO2@PDA-PLA. Then a thin PLA fibrous membrane layer showing hydrophobicity was electrospun onto this (PLA-E). The Janus PLA-E/TiO2@PDA-PLA membrane was successfully fabricated. Due to the asymmetric wettability and anchored TiO2, the PLA-E/TiO2@PDA-PLA Janus membrane exhibits efficient directional moisture transport and excellent UV protection abilities, and this work may provide a new pathway for fabricating multifunctional personal protective materials and have attractive potential applications in the future.

Theoretical Study of Radical Inactivation, LOX Inhibition, and Iron Chelation: The Role of Ferulic Acid in Skin Protection against UVA Induced Oxidative Stress

Ferulic acid (FA) is used in skin formulations for protection against the damaging actions of the reactive oxygen species (ROS) produced by UVA radiation. Possible underlying protective mechanisms are not fully elucidated. By considering the kinetics of proton-coupled electron transfer (PCET) and radical-radical coupling (RRC) mechanisms, it appears that direct scavenging could be operative, providing that a high local concentration of FA is present at the place of ^•OH generation. The resulting FA phenoxyl radical, after the scavenging of a second ^•OH and keto-enol tautomerization of the intermediate, produces 5-hydroxyferulic acid (5OHFA). Inhibition of the lipoxygenase (LOX) enzyme, one of the enzymes that catalyse free radical production, by FA and 5OHFA were analysed. Results of molecular docking calculations indicate favourable binding interactions of FA and 5OHFA with the LOX active site. The exergonicity of chelation reactions of the catalytic Fe²⁺ ion with FA and 5OHFA indicate the potency of these chelators to prevent the formation of ^•OH radicals via Fenton-like reactions. The inhibition of the prooxidant LOX enzyme could be more relevant mechanism of skin protection against UVA induced oxidative stress than iron chelation and assumed direct scavenging of ROS.

Oxidative stress in the skin: Impact and related protection

Skin, our first interface to the external environment, is subjected to oxidative stress caused by a variety of factors such as solar ultraviolet, infrared and visible light, environmental pollution, including ozone and particulate matters, and psychological stress. Excessive reactive species, including reactive oxygen species and reactive nitrogen species, exacerbate skin pigmentation and aging, which further lead to skin tone unevenness, pigmentary disorder, skin roughness and wrinkles. Besides these, skin microbiota are also a very important factor ensuring the proper functions of skin. While environmental factors such as UV and pollutants impact skin microbiota compositions, skin dysbiosis results in various skin conditions. In this review, we summarize the generation of oxidative stress from exogenous and endogenous sources. We further introduce current knowledge on the possible roles of oxidative stress in skin pigmentation and aging, specifically with emphasis on oxidative stress and skin pigmentation. Meanwhile, we summarize the science and rationale of using three well-known antioxidants, namely vitamin C, resveratrol and ferulic acid, in the treatment of hyperpigmentation. Finally, we discuss the strategy for preventing oxidative stress-induced skin pigmentation and aging.

Ultraviolet B irradiation up-regulates MM1 and induces photoageing of the epidermis

BACKGROUND

ΔNp63α and c-Myc are key transcription factors controlling proliferation and senescence in epithelial cells. We previously reported that the c-Myc modulator MM1 and its E3 ligase, HERC3, together with the transcription factor ΔNp63α, compose a feedback loop, which regulates proliferative senescence in MCF-10A mammary epithelial cells. However, it is unknown whether this loop is involved in skin ageing. On the other hand, ultraviolet B (UVB) rays are assumed to be the main culprits for photoageing of the epidermis, but the underlying mechanisms are obscure.

AIMS

To investigate whether MM1/ΔNp63α axis is involved in UVB-induced photoageing of the epidermis.

MATERIALS AND METHODS

HaCaT human immortalized keratinocytes overexpressed with MM1, knocked down with c-Myc or irradiated with UVB, were subjected to MTT assays to measure cell proliferation, as well as RT-qPCR or immunoblot to detect the members of MM1/ΔNp63α loop and the cellular senescence markers. Meanwhile, primary normal human keratinocytes (NHKs) or mice were irradiated with UVB, followed by immunoblot analysis, SA-β-gal, haematoxylin-eosin or immunohistochemistry staining.

RESULTS

Overexpression of MM1 down-regulated ΔNp63α and induced proliferative senescence in the HaCaT cells. In the HaCaT cells, NHKs and the mouse epidermis, UVB irradiation increased MM1 mRNA level and led to a down-regulation of ΔNp63α, HERC3 and c-Myc, concomitant with cellular senescence or photoageing. Additionally, knock-down of c-Myc induced proliferative senescence in the HaCaT cells and abrogated UVB-induced cellular senescence.

CONCLUSIONS

UVB up-regulates MM1 and consequently modulates ΔNp63α and c-Myc, which may account for the proliferative senescence of keratinocytes and photoageing of the epidermis.

Analytical tools for urocanic acid determination in human samples: A review

Urocanic acid is a chromophore found in the skin that has been identified as an important immunosuppressant and carcinogenesis mediator through its photoisomerization from trans to cis form induced by ultraviolet radiation. Research on analytical methods that explore urocanic acid isomerization is indispensable to fully understand the deleterious effects mediated by this biomarker. In this context, the current relevant analytical methods for determination of these isomers in human samples are summarized in this review. The methods presented here are applicable to human samples collected by noninvasive methods (or minimally invasive), encompassing an array of analytical techniques, including high-performance capillary electrophoresis, confocal Raman spectroscopy, gas chromatography, high-performance liquid chromatography, and mass spectrometry, among others. Developed high-performance liquid chromatography methods have proven to be advantageous, allowing noninvasive collections for in vivo analysis and the confocal Raman, specially, for real-time analysis. Among all these methods, high-performance liquid chromatography is the most investigated one with mass spectrometry or ultraviolet detector, and the mass spectrometry detector being the most studied in the last years, demonstrating high sensitivity, very low detection limits, and accurate identification, especially for clinical investigations.

Alpha-neoendorphin can reduce UVB-induced skin photoaging by activating cellular autophagy

Skin aging is influenced by several genetic, physiological, and environmental factors. In particular, ultraviolet (UV) exposure is an important factor involved in inducing skin photoaging. Autophagy controlling homeostatic balance between the synthesis, degradation, and recycling of cellular organelles and proteins plays important regulatory roles in several biological processes, including aging. The opioid neuropeptide α-neoendorphin (named NEP) is an endogenous decapeptide (N-YGGFLRKYPK-C) that activates the kappa opioid receptor and exhibits certain anti-aging and anti-wrinkling effects on skin cells; however, its action mechanism has not yet been elucidated. Therefore, the aim of this study was to determine the effects of NEP on anti-skin aging and autophagy activation in human dermal fibroblast cells. Western blot results showed that NEP down-regulates the production of phospho-mammalian target of rapamycin (p-mTOR), whereas increases the expression of key autophagy-related molecules such as Beclin-1, Atg5-Atg12, and LC3-II. The immunocytochemical analysis performed with anti-LC3-II antibody also showed that the autophagic indicators, autophagosomes are formed by NEP. These results suggest that NEP can activate cellular autophagy through mTOR-Beclin-1-mediated signaling pathway. It was also revealed by CM-H₂DCF-DA assay and Western blottings that NEP can reduce the production of ultraviolet B (UVB)-induced reactive oxygen species (ROS) like with N-acetylcysteine (NAC), resulting in decreasing the expression levels of skin aging-related proteins, such as phospho-ERK (p-ERK), phospho-p38 (p-p38), and phospho-JNK (p-JNK). Furthermore, NEP could increase the type I procollagen production, while decreasing MMP-1, MMP-2, and MMP-9 activities. Taken together, the results demonstrate that NEP can reduce UVB-induced photoaging by activating autophagy.

Melatonin attenuates the detrimental effects of UVA irradiation in human dermal fibroblasts by suppressing oxidative damage and MAPK/AP-1 signal pathway in vitro

BACKGROUND

People living in Mediterranean countries are mostly exposed to solar ultraviolet (UV) radiation that damages skin and results in photoaging which involves activation of epidermal growth factor receptor (EGFR) and downstream signal transduction through mitogen-activated protein kinases (MAPKs) in fibroblasts. Generation of reactive oxygen/nitrogen species by UV radiation is also critical for EGFR and MAPKs activation. MAPKs are responsible for activation of AP-1 subunits in the nucleus which induce matrix metalloproteinases. Melatonin, along with its metabolites, are known to be the most effective free radical scavenger and protective agent due to its ability to react with various radicals, lipophilic/hydrophilic structures.

OBJECTIVES

In this study, we investigated the effects of melatonin on UVA-irradiated primary human dermal fibroblasts (HDFs) by following the alteration of molecules from cell membrane to the nucleus and oxidative/nitrosative damage status of the cells in a time-dependent manner which have not been clearly elucidated yet.

METHODS

To mimic UVA dosage in Mediterranean countries, HDFs were exposed to UVA with sub-cytotoxic dosage (20 J/cm² ) after pretreatment with melatonin (1 μmol/L) for 1 hour. Changes in the activation of the molecules and oxidative/nitrosative stress damage were analyzed at different time points.

RESULTS

Our results clearly show that melatonin decreases UVA-induced oxidative/nitrosative stress damage in HDFs. It also suppresses phosphorylation of EGFR, activation of MAPK/AP-1 signal transduction pathway and production of matrix metalloproteinases in a time-dependent manner.

CONCLUSION

Melatonin can be used as a protective agent for skin damage against intracellular detrimental effects of relatively high dosage of UVA irradiation.

Differential behavior of sodium laurylsulfate micelles in the presence of nonionic polymers

HYPOTHESIS

Theory and practice have proven that the cleansing properties and irritation potential of surfactants can be controlled with the addition of co-surfactants or polymers. The size of the surfactant-polymer nanoassembly, which differs from the pure surfactant micelle, has been postulated to be the cause of the differences in a surfactant system's ability to disrupt the skin barrier. However, a firm structure-function relationship connecting polymer and surfactant under a consumer relevant condition is yet to be established. It is therefore hypothesized that apart from the size, the shape and the chemical nature of the polymer might play crucial roles.

EXPERIMENTS

We used combined small-angle neutron scattering, nuclear magnetic resonance spectroscopy, tensiometry, and dye solubilization methods to investigate the shape, size, and intermolecular interactions involved in sodium laurylsulfate-based systems in the presence of two industrially important and chemically distinct polymers, polyethylene glycol and polyvinyl alcohol, adopting a consumer relevant protocol.

FINDINGS

Apart from size, shape and inter-micellar interactions fine-tuned by the presence of the polymers are found to be the important factors. Secondly, the physicochemical property of the polymer including chemical structure, conformation, hydrophilicity, presence of side groups, all can have crucial influence on polymer-surfactant interaction, micelle formation, and micelle stability.

UVA and UVB Photoprotective Capabilities of Topical Formulations Containing Mycosporine-like Amino Acids (MAAs) through Different Biological Effective Protection Factors (BEPFs)

The safety and stability of synthetic UV-filters and the procedures for evaluating the photoprotective capability of commercial sunscreens are under continuous review. The influence of pH and temperature stressors on the stability of certain Mycosporine-like amino acids (MAAs) isolated at high purity levels was examined. MAAs were highly stable at room temperature during 24 h at pH 4.5–8.5. At 50 °C, MAAs showed instability at pH 10.5 while at 85 °C, progressive disappearances were observed for MAAs through the studied pH range. In alkaline conditions, their degradation was much faster. Mycosporine-serinol and porphyra-334 (+shinorine) were the most stable MAAs under the conditions tested. They were included in four cosmetically stable topical sunscreens, of which the Sun Protection Factor (SPF) and other Biological Effective Protection Factors (BEPFs) were calculated. The formulation containing these MAAs showed similar SPF and UVB-BEPFs values as those of the reference sunscreen, composed of synthetic UV absorbing filters in similar percentages, while UVA-BEPFs values were slightly lower. Current in vitro data strongly suggest that MAAs, as natural and safe UV-absorbing and antioxidant compounds, have high potential for protection against the diverse harmful effects of solar UV radiation. In addition, novel complementary in vitro tests for evaluation of commercial sunscreens efficacy are proposed.

Inhibitory Effect of Lupeol on MMPs Expression using Aged Fibroblast through Repeated UVA Irradiation

In this study, the aged dermal fibroblast model was constructed by repeated irradiation with UV light and the effect of lupeol, a triterpenoid, on anti-aging was confirmed. SA-β-galactosidase (SA-β-gal) stained aged cells increased by about 40% and expression of p-p53, p21, p16 and MMPs (MMP-1, -2, -3) increased in aged fibroblast. As an efficacy result, the treatment of lupeol on aged fibroblast induced by UVA repeated irradiation showed a dose-dependent reduction of SA-β-gal stained aged cells, the expression of p-p53, p21, p16 and inhibition of MMPs. Interestingly, lupeol increased dephosphorylation of p-ERK in repeated UV irradiated conditions. Additionally, lupeol compensated MMPs expression when p-ERK phosphorylation was inhibited by p-ERK inhibitor PD98059. Thus, these results showed that lupeol has a possible effect on MMPs expression using inhibition of the p-ERK pathway. Taken together, we confirmed that lupeol inhibits senescence through inhibiting MMP-1, -2, -3 as well as p-p53, p21 and p16 expression and SA-β-gal activity in repeated UVA-irradiated senescent FB models, therefore suggesting that lupeol may be useful as an anti-aging agent.

Implications of tryptophan photoproduct FICZ in oxidative stress and terminal differentiation of keratinocytes

Ultraviolet B (UVB) irradiation activates aryl hydrocarbon receptor (AHR), generates reactive oxygen species (ROS) and mediates photocarcinogenesis and photoaging. 6-Formylindolo[3,2-b]carbazole (FICZ) is a tryptophan photoproduct generated by UVB exposure. FICZ exhibits similar biological effects to UVB, including AHR ligation and ROS production. FICZ also acts as a potent photosensitizer for UVA and the production of ROS is synergistically augmented in the simultaneous presence of FICZ and UVA. In contrast, FICZ upregulates the expression of terminal differentiation molecules such as filaggrin and loricrin via AHR. In parallel with this, the administration of FICZ inhibits skin inflammation in a murine psoriasis and dermatitis model. In this article, we summarize the harmful and beneficial aspects of FICZ in skin pathology.

Age-Associated Differences in Infection of Human Skin in the SCID Mouse Model of Varicella-Zoster Virus Pathogenesis

Varicella-zoster virus (VZV) is the skin-tropic human alphaherpesvirus responsible for both varicella-zoster and herpes zoster. Varicella-zoster and herpes zoster skin lesions have similar morphologies, but herpes zoster occurs disproportionally in older individuals and is often associated with a more extensive local rash and severe zoster-related neuralgia. We hypothesized that skin aging could also influence the outcome of the anterograde axonal transport of VZV to skin. We utilized human skin xenografts maintained in immunodeficient (SCID) mice to study VZV-induced skin pathology in vivo in fetal and adult skin xenografts. Here we found that VZV replication is enhanced in skin from older compared to younger adults, correlating with clinical observations. In addition to measures of VZV infection, we examined the expression of type I interferon (IFN) pathway components in adult skin and investigated elements of the cutaneous proliferative and inflammatory response to VZV infection in vivo Our results demonstrated that VZV infection of adult skin triggers intrinsic IFN-mediated responses such as we have described in VZV-infected fetal skin xenografts, including MxA as well as promyelocytic leukemia protein (PML), in skin cells surrounding lesions. Further, we observed that VZV elicited altered cell signaling and proliferative and inflammatory responses that are involved in wound healing, driven by follicular stem cells. These cellular changes are consistent with VZV-induced activation of STAT3 and suggest that VZV exploits the wound healing process to ensure efficient delivery of the virus to keratinocytes. Adult skin xenografts offer an approach to further investigate VZV-induced skin pathologies in vivoIMPORTANCE Varicella-zoster virus (VZV) is the agent responsible for both varicella-zoster and herpes zoster. Herpes zoster occurs disproportionally in older individuals and is often associated with a more extensive local rash and severe zoster-related neuralgia. To examine the effect of skin aging on VZV skin lesions, we utilized fetal and adult human skin xenografts maintained in immunodeficient (SCID) mice. We measured VZV-induced skin pathology, examined the expression of type I interferon (IFN) pathway components in adult skin, and investigated elements of the cutaneous proliferative and inflammatory response to VZV infection in vivo Our results demonstrate that characteristics of aging skin are preserved in xenografts; that VZV replication is enhanced in skin from older compared to younger adults, correlating with clinical observations; and that VZV infection elicits altered cell signaling and inflammatory responses. Adult skin xenografts offer an approach to further investigate VZV-induced skin pathologies in vivo.

An endogenous tryptophan photo-product, FICZ, is potentially involved in photo-aging by reducing TGF-β-regulated collagen homeostasis

BACKGROUND

Persistent ultraviolet (UV) radiation in the form of sunlight causes photo-aging of the skin by reducing the production of type I collagen, the major constituent of the extracellular matrix of the dermis. Transforming growth factor (TGF)-β transforms dermal fibroblasts into α2-smooth muscle actin (ACTA2)-expressing myofibroblasts. Myofibroblasts produce a precursor form of type I collagen, type I procollagen (collagen I), consisting of pro-alpha1 (produced by the COL1A1 gene) and pro-alpha2 chains (produced by the COL1A2 gene). Smad2/3 is a key downstream molecule of TGF-β signaling. The mechanisms through which UV inhibits collagen I synthesis are not fully understood. 6-Formylindolo[3,2-b]carbazole (FICZ) is an endogenous tryptophan photo-metabolite generated by UV irradiation. FICZ is well known as a high-affinity ligand for aryl hydrocarbon receptor (AHR). However, the physiological roles of FICZ in photo-aging have yet to be addressed.

OBJECTIVE

To evaluate the effects of FICZ on the TGF-β-mediated ACTA2 and collagen I expression in normal human dermal fibroblasts (NHDFs).

METHODS

Quantitative real-time polymerase chain reaction and western blot analysis were performed to determine the expression of ACTA2, COL1A1, and COL1A2 in NHDFs with or without FICZ and TGF-β. The phosphorylated Smad2/3 (pSmad2/3) protein levels in cytoplasmic or nuclear portions were investigated by western blot analysis. Immunofluorescence staining was conducted to evaluate pSmad2/3 localization, and F-actin staining with phalloidin was performed to visualize actin polymerization in myofibroblasts. The actions of FICZ on the TGF-β-mediated collagen I expression and nuclear translocation of pSmad2/3 were analyzed in the presence of selective AHR antagonists or in AHR-knockdown NHDFs.

RESULTS

We found that FICZ significantly inhibited the TGF-β-induced upregulation of mRNA and protein levels of ACTA2 and collagen I and actin polymerization in myofibroblasts. FICZ did not disturb the phosphorylation of Smad2/3. Notably, FICZ reduced the expression of pSmad2/3 in the nucleus, while it increased that in the cytoplasm, suggesting that it inhibits the nuclear translocation of pSmad2/3 induced by TGF-β. The inhibitory actions of FICZ on the TGF-β-mediated collagen I expression and nuclear translocation of pSmad2/3 were independent of AHR signaling. Another endogenous AHR agonist, kynurenine, also inhibited the TGF-β-mediated ACTA2 and collagen I upregulation in NHDFs in an AHR-independent manner; however, its effects were insignificant in comparison with those of FICZ.

CONCLUSIONS

These findings suggest that the endogenous photo-product FICZ may be a key chromophore that involves in photo-aging. Downregulation of FICZ signaling is thus a potential strategy to protect against photo-aging.

Topical Vitamin C and the Skin: Mechanisms of Action and Clinical Applications

OBJECTIVE: This review article details the main mechanisms of action and clinical applications of topical vitamin C on the skin, including its antioxidative, photoprotective, antiaging, and antipigmentary effects. DESIGN: A PubMed search for the relevant articles on vitamin C and the skin was conducted using the following key words: "vitamin C," "ascorbic acid," "ascorbyl-6-palmitate,"and "magnesium ascorbyl phosphate." RESULTS: As one of the most powerful antioxidants in the skin, vitamin C has been shown to protect against photoaging, ultraviolet-induced immunosuppression, and photocarcinogenesis. It also has an antiaging effect by increasing collagen synthesis, stabilizing collagen fibers, and decreasing collagen degradation. It decreases melanin formation, thereby reducing pigmentation. Vitamin C is the primary replenisher of vitamin E and works synergistically with vitamin E in the protection against oxidative damage. CONCLUSION: Topical vitamin C has a wide range of clinical applications, from antiaging and antipigmentary to photoprotective. Currently, clinical studies on the efficacy of topical formulations of vitamin C remain limited, and the challenge lies in finding the most stable and permeable formulation in achieving the optimal results.

Luteolin decreases the UVA‑induced autophagy of human skin fibroblasts by scavenging ROS

Luteolin (LUT) is a flavone, which is universally present as a constituent of traditional Chinese herbs, and certain vegetables and spices, and has been demonstrated to exhibit potent radical scavenging and cytoprotective properties. Although LUT has various beneficial effects on health, the effects of LUT on the protection of skin remain to be fully elucidated. The present study investigated whether LUT can protect human skin fibroblasts (HSFs) from ultraviolet (UV) A irradiation. It was found that, following exposure to different doses of UVA irradiation, the HSFs exhibited autophagy, as observed by fluorescence and transmission electron microscopy, and reactive oxygen species (ROS) bursts, analyzed by flow cytometry, to differing degrees. Following incubation with micromolar concentrations of LUT, ROS production decreased and autophagy gradually declined. In addition, the expression of hypoxia-inducible factor-1α and the classical autophagy-associated proteins, LC3 and Beclin 1 were observed by western blotting. Western blot analysis showed that the expression levels of HIF-1α, LC3-II and Beclin 1 gradually decreased in the UVA-irradiated HSFs following treatment with LUT. These data indicated that UVA-induced autophagy was mediated by ROS, suggesting the possibility of resistance against UV by certain natural antioxidants, including LUT.

Natural and sun-induced aging of human skin

With worldwide expansion of the aging population, research on age-related pathologies is receiving growing interest. In this review, we discuss current knowledge regarding the decline of skin structure and function induced by the passage of time (chronological aging) and chronic exposure to solar UV irradiation (photoaging). Nearly every aspect of skin biology is affected by aging. The self-renewing capability of the epidermis, which provides vital barrier function, is diminished with age. Vital thermoregulation function of eccrine sweat glands is also altered with age. The dermal collagenous extracellular matrix, which comprises the bulk of skin and confers strength and resiliency, undergoes gradual fragmentation, which deleteriously impacts skin mechanical properties and dermal cell functions. Aging also affects wound repair, pigmentation, innervation, immunity, vasculature, and subcutaneous fat homeostasis. Altogether, age-related alterations of skin lead to age-related skin fragility and diseases.

Anti-aging cosmetics: facts and controversies

The authors review ageing in its extrinsic and intrinsic mechanisms, as well as the therapies available for improving its effects, and present some of the facts and controversies related to anti-aging cosmetics.

Metabolic signature of sun exposed skin suggests catabolic pathway overweighs anabolic pathway

Skin chronically exposed to sun results in phenotypic changes referred as photoaging. This aspect of aging has been studied extensively through genomic and proteomic tools. Metabolites, the end product are generated as a result of biochemical reactions are often studied as a culmination of complex interplay of gene and protein expression. In this study, we focused exclusively on the metabolome to study effects from sun-exposed and sun-protected skin sites from 25 human subjects. We generated a highly accurate metabolomic signature for the skin that is exposed to sun. Biochemical pathway analysis from this data set showed that sun-exposed skin resides under high oxidative stress and the chains of reactions to produce these metabolites are inclined toward catabolism rather than anabolism. These catabolic activities persuade the skin cells to generate metabolites through the salvage pathway instead of de novo synthesis pathways. Metabolomic profile suggests catabolic pathways and reactive oxygen species operate in a feed forward fashion to alter the biology of sun exposed skin.

Flash photolysis and pulse radiolysis studies on elastin hydrolysates

The formation of reactive species and free radicals in water soluble elastin hydrolysates have been investigated by pulse radiolysis and flash photolysis. Elastin hydrolysates were obtained by hydrolysis of elastin extracted from aorta. An investigation of the photochemical properties of elastin hydrolysates in water was carried out using nanosecond laser irradiation. The transient spectra of elastin hydrolysates solution excited at 266 nm showed two bands. One of them with maximum at 295 nm and the second one with maximum at 400 nm. The reactions of hydrated electrons and ˙OH radicals with elastin have been studied by pulse radiolysis. In the absorption spectra of products resulting from the reaction of elastin with e(aq)(-) small maximum absorption in UV and visible light was observed. In the absorption spectra of products resulting from the reaction of the hydroxyl radicals with elastin two bands were observed. The first one at 320 nm and the second one at 410 nm. Reaction of OH radicals with elastin hydrolysates lead to formation of Tyr phenoxyl radicals with absorption at 410 nm. The influence of the addition of sodium azide NaN3 on the formation of the transients was evaluated.

Interaction and reactivity of urocanic acid towards peroxyl radicals

The capacity of urocanic acid to interact with peroxyl radicals has been evaluated in several systems: oxidation in the presence of a free radical source (2,2'-azobis(2-amidinopropane; AAPH), protection of phycocyanin bleaching elicited by peroxyl radicals, and Cu(II)- and AAPH-promoted LDL oxidation. The results indicate that both isomers (cis and trans) are mild peroxyl radical scavengers. For example, trans-urocanic acid is nearly 400 times less efficient than Trolox in the protection of the peroxyl radical promoted bleaching of phycocyanin. Regarding the removal of urocanic acid by peroxyl radicals, nearly 100 muM trans-urocanic acid is required to trap half of the produced radicals under the employed conditions (10 mM AAPH, 37 degrees C). Competitive experiments show that the cis-isomer traps peroxyl radicals 30% less efficiently than the trans-isomer. Given the high concentrations that trans-urocanic acid reaches in skin, its capacity to trap peroxyl radicals could contribute to the protection of the tissue towards ROS-mediated processes. Furthermore, both isomers, and particularly the cis-isomer, protect LDL from Cu(II)-induced oxidation.

Middle infrared radiation induces G2/M cell cycle arrest in A549 lung cancer cells

There were studies investigating the effects of broadband infrared radiation (IR) on cancer cell, while the influences of middle-infrared radiation (MIR) are still unknown. In this study, a MIR emitter with emission wavelength band in the 3-5 µm region was developed to irradiate A549 lung adenocarcinoma cells. It was found that MIR exposure inhibited cell proliferation and induced morphological changes by altering the cellular distribution of cytoskeletal components. Using quantitative PCR, we found that MIR promoted the expression levels of ATM (ataxia telangiectasia mutated), ATR (ataxia-telangiectasia and Rad3-related and Rad3-related), TP53 (tumor protein p53), p21 (CDKN1A, cyclin-dependent kinase inhibitor 1A) and GADD45 (growth arrest and DNA-damage inducible), but decreased the expression levels of cyclin B coding genes, CCNB1 and CCNB2, as well as CDK1 (Cyclin-dependent kinase 1). The reduction of protein expression levels of CDC25C, cyclin B1 and the phosphorylation of CDK1 at Thr-161 altogether suggest G(2)/M arrest occurred in A549 cells by MIR. DNA repair foci formation of DNA double-strand breaks (DSB) marker γ-H2AX and sensor 53BP1 was induced by MIR treatment, it implies the MIR induced G(2)/M cell cycle arrest resulted from DSB. This study illustrates a potential role for the use of MIR in lung cancer therapy by initiating DSB and blocking cell cycle progression.

Ultraweak photon emission induced by visible light and ultraviolet A radiation via photoactivated skin chromophores: in vivo charge coupled device imaging

Solar radiation that reaches Earth's surface can have severe negative consequences for organisms. Both visible light and ultraviolet A (UVA) radiation are known to initiate the formation of reactive oxygen species (ROS) in human skin by photosensitization reactions (types I and II). In the present study, we investigated the role of visible light and UVA radiation in the generation of ROS on the dorsal and the palmar side of a hand. The ROS are known to oxidize biomolecules such as lipids, proteins, and nucleic acids to form electronically excited species, finally leading to ultraweak photon emission. We have employed a highly sensitive charge coupled device camera and a low-noise photomultiplier tube for detection of two-dimensional and one-dimensional ultraweak photon emission, respectively. Our experimental results show that oxidative stress is generated by the exposure of human skin to visible light and UVA radiation. The oxidative stress generated by UVA radiation is claimed to be significantly higher than that by visible light. Two-dimensional photon imaging can serve as a potential tool for monitoring the oxidative stress in the human skin induced by various stress factors irrespective of its physical or chemical nature.

Identification of the radicals formed in the reactions of some endogenous photosensitizers with oleic acid under the UVA irradiation

Electron spin resonance measurements were performed for the reactions of some endogenous photosensitizers (flavin mononucleotide or flavin adenine dinucleotide or folic acid or β-nicotinamide adenine dinucleotide or β-nicotinamide adenine dinucleotide phosphate or pyridoxal-5'-phosphate or urocanic acid) with oleic acid under the ultraviolet light A irradiation using α-(4-pyridyl-1-oxide)-N-tert-butylnitrone as a spin trap reagent. Of the endogenous photosensitizers, prominent electron spin resonance signals (α^N = 1.58 mT and α^Hβ = 0.26 mT) were observed for the reaction mixture of flavin mononucleotide (or flavin adenine dinucleotide or folic acid), suggesting that radical species form in the reaction mixtures. Singlet oxygen seems to participate in the formation of the radicals because the electron spin resonance peak heights increased for the reactions in D₂O to a great extent. A high performance liquid chromatography-electron spin resonance-mass spectrometry was employed to identify the radicals formed in the reactions of the endogenous photosensitizers (flavin mononucleotide or flavin adenine dinucleotide or folic acid) with oleic acid under the ultraviolet light A irradiation. The high performance liquid chromatography-electron spin resonance-mass spectrometry analyses showed that 7-carboxyheptyl and 1-(3-carboxypropyl)-4-hydroxybutyl radicals form in the reaction mixture of flavin mononucleotide (or flavin adenine dinucleotide or folic acid).

A Class I UV-blocking (senofilcon A) soft contact lens prevents UVA-induced yellow fluorescence and NADH loss in the rabbit lens nucleus in vivo

It is known that fluorescence, much of it caused by UVA light excitation, increases in the aging human lens, resulting in loss of sharp vision. This study used an in vivo animal model to investigate UVA-excited fluorescence in the rabbit lens, which contains a high level of the UVA chromophore NADH, existing both free and bound to λ-crystallin. Also, the ability of a Class I (senofilcon A) soft contact lens to protect against UVA-induced effects on the rabbit lens was tested. Rabbit eyes were irradiated with UVA light in vivo (100 mW/cm(2) on the cornea) for 1 h using monochromatic 365 nm light. Irradiation was conducted in the presence of either a senofilcon A contact lens, a minimally UV-absorbing lotrafilcon A contact lens, or no contact lens at all. Eyes irradiated without a contact lens showed blue 365 nm-excited fluorescence initially, but this changed to intense yellow fluorescence after 1 h. Isolated, previously irradiated lenses exhibited yellow fluorescence originating from the lens nucleus when viewed under 365 nm light, but showed normal blue fluorescence arising from the cortex. Previously irradiated lenses also exhibited a faint yellow color when observed under visible light. The senofilcon A contact lens protected completely against the UVA-induced effects on fluorescence and lens yellowing, whereas the lotrafilcon A lens showed no protection. The UVA-exposure also produced a 53% loss of total NADH (free plus bound) in the lens nucleus, with only a 13% drop in the anterior cortex. NADH loss in the nucleus was completely prevented with use of a senofilcon A contact lens, but no significant protection was observed with a lotrafilcon A lens. Overall, the senofilcon A lens provided an average of 67% protection against UVA-induced loss of four pyridine nucleotides in four different regions of the lens. HPLC analysis with fluorescence detection indicated a nearly six-fold increase in 365 nm-excited yellow fluorescence arising from lens nuclear λ-crystallin after the in vivo UVA exposure. It is concluded that UVA-induced loss of free NADH (which fluoresces blue) may have allowed the natural yellow fluorescence of λ-crystallin and other proteins in the lens nucleus to become visible. Increased fluorescence exhibited by UVA-exposed λ-crystallin may have been the result of a UVA-induced change in the conformation of the protein occurring during the initial UVA-exposure in vivo. The results demonstrate the greater susceptibility of the lens nucleus to UVA-induced stress, and may relate to the formation of human nuclear cataract. The senofilcon A contact lens was shown to be beneficial in protecting the rabbit lens against effects of UVA light, including changes in fluorescence, increased yellowing and loss of pyridine nucleotides.

Associations between environmental factors and incidence of cutaneous melanoma. Review

BACKGROUND

Cutaneous melanoma is one of the most serious skin cancers. It is caused by neural crest-derived melanocytes - pigmented cells normally present in the epidermis and, sometimes, in the dermis.

METHODS

We performed a review of current knowledge on the risk factors of cutaneous melanoma. Relevant studies were identified using the PubMed, Science Direct, Medline, Scopus, Scholar Google and ISI Web of Knowledge databases.

RESULTS

Melanoma incurs a considerable public health burden owing to the worldwide dramatic rise in incidence since the mid-1960s. Ultraviolet radiation exposure is the predominant environmental risk factor. The role of geographical (latitude) and individual factors such as skin type, life style, vitamin D levels and antioxidant protection, sunburn, and exposure to other environmental factors possibly contributing to melanoma risk (such as cosmetics including sunscreen, photosensitising drugs, and exogenous hormones) are reviewed in this article. Recently, both rare high risk susceptibility genes and common polymorphic genes contributing to melanoma risk have been identified.

CONCLUSIONS

Cutaneous melanoma is a complex cancer with heterogeneous aetiology that continues to increase in incidence. Introduction of new biomarkers may help to elucidate the mechanism of pathogenesis and individual susceptibility to the disease, and make both prevention and treatment more effective.

UV radiation-induced skin aging in hairless mice is effectively prevented by oral intake of sea buckthorn (Hippophae rhamnoides L.) fruit blend for 6 weeks through MMP suppression and increase of SOD activity

Oxidative stress and oxidative photodamage induced by UV radiation can cause serious skin damage that is characterized by wrinkling, roughness, laxity and pigmentation. The effects of a sea buckthorn (Hippophae rhamnoides L.) fruit blend (SFB) containing sea buckthorn fruit extract, blueberry extract and collagen on UV-induced skin aging were examined by treating hairless mice for 6 weeks with UV irradiation and SFB administered orally. The effects of SFB were measured in the skin of these mice by phenotypical and histological analysis and western blotting. According to wrinkle formation analysis, the oral intake of SFB induced a decrease in wrinkle formation in the damaged skin of UV-irradiated mice. The thickness of the epidermis and dermis in the vitamin extracts (Vit)- and SFB-treated group was lower than that in the vehicle-treated group, but the group treated with SFB50 was the most effective group. The mice treated with the Vit- or SFB solution maintained a normal moisture content through the inhibition of transdermal water loss (TEWL) and an increase in skin moisture content. Furthermore, the levels of matrix metalloproteinase (MMP) and collagen protein expression were assessed in five groups to examine the mechanisms underlying the effects of SFB oral intake. The application of SFB induced a decrease in MMP-1 and -9 expression to the levels observed in the vehicle-treated group, but MMP-9 expression showed a much larger decrease than MMP-1. Furthermore, the expression of collagen-1 in the skin corresponded to MMP expression except for the SFB30-treated group, whereas the superoxide dismutase (SOD) activity was increased dramatically in the SFB50-treated group. These results suggest that SFB has potential as a protective and therapeutic drug candidate against skin aging that functions by regulating the moisture content, MMP expression levels and SOD activity.

Rapid, simultaneous and nanomolar determination of pyroglutamic acid and cis-/trans-urocanic acid in human stratum corneum by hydrophilic interaction liquid chromatography (HILIC)-electrospray ionization tandem mass spectrometry

A rapid, sensitive and specific hydrophilic interaction liquid chromatography coupled to tandem mass spectrometric (HILIC-MS/MS) method for the simultaneous determination of pyroglutamic acid, cis- and trans-urocanic acid in human skin stratum corneum (SC) were developed and validated. This method was carried out without derivatization or addition of ion-pair additives in mobile phase. The analytes were extracted by PBS buffer solution and analyzed using an electrospray positive ionization mass spectrometry in the multiple reaction monitoring (MRM) mode. Chromatographic separation was performed on an AQUITY UPLC amide column using gradient elution with the mobile phase of water and acetonitrile. The standard curves were linear over the concentration range of 1.0-250 ng/mL with a correlation coefficient higher than 0.999 with an LLOQ of 0.5 ng/mL. The lower limits of detection (LLOD) of these analytes were lower than 0.2 ng/mL. The intra- and inter-day precisions were measured to be below 7.7% and accuracies were within the range of 94.3-102.6%. The validated method was successfully applied to determine the level of pyroglutamic acid and cis-/trans-urocanic acid in the SC samples from forearm and forehead region of 19 human volunteers.

Increased sensitivity of histidinemic mice to UVB radiation suggests a crucial role of endogenous urocanic acid in photoprotection

Urocanic acid (UCA) is produced by the enzyme histidase and accumulates in the stratum corneum of the epidermis. In this study, we investigated the photoprotective role of endogenous UCA in the murine skin using histidinemic mice, in which the gene encoding histidase is mutated. Histidase was detected by immunohistochemistry in the stratum granulosum and stratum corneum of the normal murine skin but not in the histidinemic skin. The UCA content of the stratum corneum and the UVB absorption capacity of aqueous extracts from the stratum corneum were significantly reduced in histidinemic mice as compared with wild-type mice. When the shaved back skin of adult mice was irradiated with 250 mJ cm(-2) UVB, histidinemic mice accumulated significantly more DNA damage in the form of cyclobutane pyrimidine dimers than did wild-type mice. Furthermore, UVB irradiation induced significantly higher levels of markers of apoptosis in the epidermis of histidinemic mice. Topical application of UCA reversed the UVB-photosensitive phenotype of histidinemic mice and increased UVB photoprotection of wild-type mice. Taken together, these results provide strong evidence for an important contribution of endogenous UCA to the protection of the epidermis against the damaging effects of UVB radiation.

Squalene as a target molecule in skin hyperpigmentation caused by singlet oxygen

Based on our previous finding (Biochem. Biophys. Res. Commun., 223, 578-582, 1996) of singlet oxygen generation from coproporphyrin excreted on the skin surface from Propionibacterium acnes, we hypothesized that singlet oxygen formed in this way under UV exposure would promote peroxidation of skin surface lipids. We found that squalene was oxidized efficiently by singlet oxygen derived from coproporphyrin under UV exposure, and that the rate constant of squalene peroxidation by singlet oxygen was ten-fold higher than that of other skin surface lipids examined. The reaction was promoted more efficiently by UVA than by UVB. Furthermore, we found that topical application of squalene peroxide induced skin hyperpigmentation through increasing prostaglandin E(2) release from keratinocytes in guinea pigs. These results suggest that squalene peroxide formation by singlet oxygen plays a key role in photo-induced skin damage.

Scombroid poisoning: a review

Scombroid poisoning, also called histamine fish poisoning, is an allergy-like form of food poisoning that continues to be a major problem in seafood safety. The exact role of histamine in scombroid poisoning is not straightforward. Deviations from the expected dose-response have led to the advancement of various possible mechanisms of toxicity, none of them proven. Histamine action levels are used in regulation until more is known about the mechanism of scombroid poisoning. Scombroid poisoning and histamine are correlated but complicated. Victims of scombroid poisoning respond well to antihistamines, and chemical analyses of fish implicated in scombroid poisoning generally reveal elevated levels of histamine. Scombroid poisoning is unique among the seafood toxins since it results from product mishandling rather than contamination from other trophic levels. Inadequate cooling following harvest promotes bacterial histamine production, and can result in outbreaks of scombroid poisoning. Fish with high levels of free histidine, the enzyme substrate converted to histamine by bacterial histidine decarboxylase, are those most often implicated in scombroid poisoning. Laboratory methods and screening methods for detecting histamine are available in abundance, but need to be compared and validated to harmonize testing. Successful field testing, including dockside or on-board testing needed to augment HACCP efforts will have to integrate rapid and simplified detection methods with simplified and rapid sampling and extraction. Otherwise, time-consuming sample preparation reduces the impact of gains in detection speed on the overall analysis time.

Male skin care needs

Male skin care has undergone significant development over the past decade, with many companies now marketing skin care products directly to the male consumer. Despite the claims of many of these companies, few over-the-counter products have data to support their efficacy at a clinical level. A basic, effective regimen for preventive male skin care should include twice-daily facial cleansing and twice-daily moisturizer application, which should include sunscreen during the day. This article focuses on topical therapies directed at the maintenance and repair of photoaged male skin. The future holds promise for new developments in skin care. However, in the absence of significant scientific breakthroughs, the most cost-effective intervention will continue to be prevention.