A comparative study of the in vitro dermal absorption of radiolabeled benzophenone through human skin.

Octocrylene is a common sun filter ingredient used to protect the skin from damaging UV rays. Benzophenone is an impurity found in formulations containing octocrylene. [14C]-Benzophenone was spiked (0.1 g/L) into 2 commercial sunscreen formulations; Neutrogena® Beach Defense Sunscreen Spray Broad Spectrum SPF 70 Aerosol, Neutrogena® Ultra Sheer Body Mist Sunscreen Broad Spectrum SPF 30 Aerosol, and an acetone vehicle. The formulations were applied (ca 2 µL/cm2) to dermatomed human skin mounted in static diffusion cells in vitro. Receptor fluid was collected up to 24 h post dose. All samples were analyzed by liquid scintillation counting. The dermal delivery of [14C]-Benzophenone was 10.02, 9.04 and 5.19% for the 3 formulations. However, the [14C]-Benzophenone mass balances were low; 81.5, 85.3 and 8.02%, respectively. A volatility test was performed replacing skin with aluminum foil for the sunscreen formulations only. The [14C]-Benzophenone mass balance at dosing was 99% but fell to 56.9 and 60.6% at 24 h post dose, confirming the losses were due to [14C]-Benzophenone volatility. A conservative dermal absorption value of 12.42% was proposed to cover [14C]-Benzophenone containing formulations.

Low-level red plus near infrared lights combination induces expressions of collagen and elastin in human skin in vitro.

OBJECTIVE: Light therapy has attracted medical interests as a safe, alternative treatment for photo-ageing and photo-damaged skin. Recent research suggested the therapeutic activity of red and infrared (IR) lights may be effective at much lower energy levels than those used clinically. This study was to evaluate the efficacy of low-level red plus near IR light emitting diode (LED) combination on collagen and elastin and ATP production. METHODS: Human dermal fibroblasts or skin tissues were irradiated daily by red (640 nm) plus near IR (830 nm) LED lights combination at 0.5 mW/cm2 for 10 minutes (0.3 J/cm2 ). qPCR, ELISAs or histology were used to determine the gene and protein expressions. Fluorescent measurement was used to assess crosslinks of collagen and elastic fibres. ATP production was evaluated by ATP assay. RESULTS: Treatment of human fibroblast cell cultures with low-level red plus near IR lights combination was found to significantly increase LOXL1, ELN and COL1A1 and COL3A1 gene expressions as well as the synthesis of the procollagen type I and elastin proteins. Treating human skin explants with low-level red plus near IR lights combination similarly induced significant increases in the same gene expressions, type III collagen and elastic fibre formation and crosslinks. ATP production was increased in human dermal fibroblasts after red plus near IR lights combination treatment. CONCLUSION: Low-level red plus near IR lights combination stimulated the production of collagen and elastin production associated with anti-ageing benefits. These findings suggest that low-level red plus near IR LED light combination may provide an effective treatment opportunity for people with photo-aged skin.

OBJECTIF: La luminothérapie a suscité des intérêts médicaux en tant que traitement alternatif sûr pour la photo-vieillissement et la peau endommagée. Des recherches récentes ont suggéré que L'activité thérapeutique des feux rouges et infrarouges (IR) pourrait être efficace à des niveaux d'énergie beaucoup plus faibles que ceux utilisés en clinique. Cette étude avait pour but d'évaluer l'efficacité de la combinaison de diodes électroluminescentes (DEL) rouges de faible intensité et de diodes électroluminescentes (IR) sur la production de collagène, d'élastine et d'ATP. MÉTHODES: Les fibroblastes dermiques humains ou les tissus cutanés ont été irradiés quotidiennement par une combinaison de feux rouges (640nm) et de feux à DEL proches de l'IR (830nm) à 0,5mW/cm2 pendant 10minutes (0,3J/cm2). qPCR, ELISA ou histologie ont été utilisés pour déterminer les expressions géniques et protéiques. Des mesures fluorescentes ont été utilisées pour évaluer les liens croisés du collagène et des fibres élastiques. La production d'ATP a été évaluée au moyen d'un essai ATP. RÉSULTATS: Le traitement de cultures de cellules de fibroblastes humaines avec une combinaison rouge de faible intensité et proche des lumières IR a permis d'augmenter significativement les expressions des gènes LOXL1, ELN et COL1A1 et COL3A1, ainsi que la synthèse des protéines de procollagène de type I et d'élastine. Le traitement des explants de peau humaine avec une combinaison rouge de bas niveau et proche des lumières IR a également induit des augmentations significatives dans les mêmes expressions géniques, la formation de collagène de type III et de fibres élastiques et les liaisons croisées. La production d'ATP a augmenté dans les fibroblastes dermiques humains après le traitement combiné rouge et proche des feux IR. CONCLUSION: L'association du rouge de bas niveau et des lumières infrarouges a stimulé la production de collagène et d'élastine associée aux bienfaits de l'antivieillissement. Ces résultats suggèrent que la combinaison de faible intensité de rouge plus proche de la lumière IR LED peut fournir une opportunité de traitement efficace pour les personnes ayant la peau photo-âgée.

A unique gel matrix moisturizer delivers deep hydration resulting in significant clinical improvement in radiance and texture.

Introduction: As skin ages, it loses its ability to retain moisture and becomes rough and dry. This results in a clinically dull appearance with a loss of radiance, firmness, and suppleness. Symptoms can be improved with use of a moisturizer that builds and maintains skin hydration over time; however, most moisturizers that occlude the skin surface are perceived as heavy and greasy and are not consumer preferred. Methods: A unique, consumer-preferred gel matrix formula was developed by combining liquid crystal structures, which mimic skin barrier lipid assembly, with specific emulsifiers that deliver water deep into skin. Ex vivo studies were conducted to investigate the superior hydrating effects of the gel matrix formula. Confocal Raman microscopy studies assessed the spatial distribution of water in ex vivo skin after application of the gel matrix formula. To determine the effects of the gel matrix formula on dry facial skin, a 12-week clinical study was conducted with subjects with self-perceived skin dryness and dullness. Results: The formulation significantly increased the relative water content throughout epidermal regions, which was not observed with the application of a competitive gel formula. Instrumental measurements assessed improvements in skin surface moisturization and barrier function. Clinical grading showed significant improvements in hydration-related endpoints including radiance, clarity, and texture. Subject self-agree assessment demonstrated that subjects observed improvements in the appearance of their facial skin. Conclusion: These studies demonstrated that the gel matrix formula increased skin water content in deeper layers, and resulted in significant clinical improvements in hydration, barrier function, and clinical appearance of radiance.

Propionibacterium acnes susceptibility to low-level 449 nm blue light photobiomodulation.

BACKGROUND AND OBJECTIVE: Recent advances in low-level light devices have opened new treatment options for mild to moderate acne patients. Light therapies have been used to treat a variety of skin conditions over the years but were typically only available as treatments provided by professional clinicians. Clinical application of blue light has proven to be effective for a broader spectral range and at lower fluences than previously utilized. Herein, we tested the hypothesis that sub-milliwatt/cm2 levels of long-wave blue light (449 nm) effectively kills Propionibacterium acnes, a causative agent of acne vulgaris, in vitro. MATERIALS AND METHODS: Two types of LED light boards were designed to facilitate in vitro blue light irradiation to either six-well plates containing fluid culture or a petri plate containing solid medium. P. acnes. Survival was determined by counting colony forming units (CFU) following irradiation. P. acnes was exposed in the presence and absence of oxygen. Coproporphyrin III (CPIII) photoexcitation was spectrophotometrically evaluated at 415 and 440 nm to compare the relative photochemical activities of these wavelengths. RESULTS: 422 and 449 nm blue light killed P. acnes in planktonic culture. Irradiation with 449 nm light also effectively killed P. acnes on a solid agar surface. Variation of time or intensity of light exposure resulted in a fluence-dependent improvement of antimicrobial activity. The presence of oxygen was necessary for killing of P. acnes with 449 nm light. CPIII displayed clear photoexcitation at both 415 and 440 nm, indicating that both wavelengths are capable of initiating CPIII photoexcitation at low incident light intensities (50 uW/cm2 ). CONCLUSION: Herein we demonstrate that sub-milliwatt/cm2 levels of long-wave blue light (449 nm) effectively kill P. acnes. The methods and results presented allow for deeper exploration and design of light therapy treatments. Results from these studies are expanding our understanding of the mode of action and functionality of blue light, allowing for improved options for acne patients. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

Low-level red LED light inhibits hyperkeratinization and inflammation induced by unsaturated fatty acid in an in vitro model mimicking acne.

BACKGROUND AND OBJECTIVE: Acne vulgaris is a chronic inflammatory disease of the pilosebaceous units (PSU), associated with increased sebum production, abnormal follicular keratinization (hyperkeratinization), follicular overgrowth of Propionibacterium acnes (P. acnes), and increased inflammatory mediator release. Light therapy has attracted medical interests as a safe alternative treatment for acne. Both blue and red light therapies at high doses >10 J/cm2 have demonstrated marked effects on inflammatory acne lesions. However, few studies have investigated the effects of lower doses of light. The aim of this study is to investigate the biological effects of lower doses of red light at 0.2-1.2 J/cm2 for acne using an in vitro model previously developed to mimic the inflammation and hyperkeratinization observed clinically in acne. MATERIALS AND METHODS: Human epidermal equivalents were topically exposed to an unsaturated fatty acid, oleic acid (OA), followed by red light-emitting diode (LED) light treatments (light-plus-OA treatments). Endpoints evaluated included the proinflammatory cytokine IL-1α, epidermal barrier integrity, as measured by transepithelial electrical resistance (TEER), and stratum corneum (SC) thickness to monitor hyperkeratinization. RESULTS: OA-induced IL-1α release was significantly (P < 0.05) reduced following red LED light at 0.2, 0.5, and 1.2 J/cm2 , from 266 ± 11 pg/ml of no-light-plus-OA-treated (OA treatment without light) controls to 216 ± 9, 231 ± 8, and 212 ± 7 pg/ml, respectively. Histological examination showed that SC thickening following OA treatment was reduced from 43% of total epidermis for no-light-plus-OA treatment to 37% and 38% of total epidermis following 0.5 and 1.1 J/cm2 red light plus OA treatment, respectively (P < 0.05). Moreover, 1.1 J/cm2 red-light-plus-OA treatment improved OA-induced TEER changes from 29% of baseline for no-light-plus-OA treatment, to 36% of baseline. CONCLUSION: Low level red LED light therapy could provide beneficial effects of anti-inflammation, normalizing pilosebaceous hyperkeratinization, and improving barrier impairment in Acne vulgaris. Lasers Surg. Med. 50:158-165, 2018. © 2017 Wiley Periodicals, Inc.

In vitro modeling of unsaturated free fatty acid-mediated tissue impairments seen in acne lesions.

Acne vulgaris is a disease of pilosebaceous units with multifactorial pathogenesis, including hyperkeratinization, increased sebum secretion, and inflammation. Recently, it was suggested that acne subjects may have also impaired skin barrier. We hypothesized that excess unsaturated free fatty acids (UFFA) present in the sebum may cause barrier impairment associated with increased follicular stratum corneum (SC) thickening and inflammation seen in acne. Therefore, epidermal and sebaceous lipid profiles from acne and healthy subjects were analyzed and an in vitro epidermal tissue model was developed to validate this hypothesis. Significantly increased levels of free fatty acids (p < 0.05) were observed in skin lipids of human acne vs. healthy subjects. Exposure of human epidermal equivalents (HEEs) to the UFFA oleic acid (OA), also present in sebum, led to barrier impairment associated with increased SC lipid disorder, increased secretion of interleukin-1α (IL-1α), and excessive SC thickening. Furthermore, the expression of genes encoding for inflammatory cytokines and epidermal differentiation proteins was also increased both in acne lesions and in OA-treated HEEs. Taken together, these data are in agreement with the hypothesis that excess UFFAs in sebum of acne subjects may contribute to impaired skin barrier associated with the increased follicular SC thickness and inflammation seen in acne. Moreover, OA induces similar molecular and phenotypic changes in HEEs as those seen in acne lesions and suggests that an UFFA-treated epidermal tissue model can be used to study the UFFA-mediated pathways involved in the pathogenesis of inflammatory acne and for the development of appropriate therapies.

Topical stabilized retinol treatment induces the expression of HAS genes and HA production in human skin in vitro and in vivo.

Skin Aging manifests primarily with wrinkles, dyspigmentations, texture changes, and loss of elasticity. During the skin aging process, there is a loss of moisture and elasticity in skin resulting in loss of firmness finally leading to skin sagging. The key molecule involved in skin moisture is hyaluronic acid (HA), which has a significant water-binding capacity. HA levels in skin decline with age resulting in decrease in skin moisture, which may contribute to loss of firmness. Clinical trials have shown that topically applied ROL effectively reduces wrinkles and helps retain youthful appearance. In the current study, ROL was shown to induce HA production and stimulates the gene expression of all three forms of hyaluronic acid synthases (HAS) in normal human epidermal keratinocytes monolayer cultures. Moreover, in human skin equivalent tissues and in human skin explants, topical treatment of tissues with a stabilized-ROL formulation significantly induced the gene expression of HAS mRNA concomitant with an increased HA production. Finally, in a vehicle-controlled human clinical study, histochemical analysis confirmed increased HA accumulation in the epidermis in ROL-treated human skin as compared to vehicle. These results show that ROL increases skin expression of HA, a significant contributing factor responsible for wrinkle formation and skin moisture, which decrease during aging. Taken together with the activity to increase collagen, elastin, and cell proliferation, these studies establish that retinol provides multi-functional activity for photodamaged skin.

Daily Use of a Facial Broad Spectrum Sunscreen Over One-Year Significantly Improves Clinical Evaluation of Photoaging.

BACKGROUND: Sunscreens are known to protect from sun damage; however, their effects on the reversal of photodamage have been minimally investigated. OBJECTIVE: The aim of the prospective study was to evaluate the efficacy of a facial sun protection factor (SPF) 30 formulation for the improvement of photodamage during a 1-year use. METHODS: Thirty-two subjects applied a broad spectrum photostable sunscreen (SPF 30) for 52 weeks to the entire face. Assessments were conducted through dermatologist evaluations and subjects' self-assessment at baseline and then at Weeks 12, 24, 36, and 52. RESULTS: Clinical evaluations showed that all photoaging parameters improved significantly from baseline as early as Week 12 and the amelioration continued until Week 52. Skin texture, clarity, and mottled and discrete pigmentation were the most improved parameters by the end of the study (40% to 52% improvement from baseline), with 100% of subjects showing improvement in skin clarity and texture. CONCLUSION: The daily use of a facial broad-spectrum photostable sunscreen may visibly reverse the signs of existing photodamage, in addition to preventing additional sun damage.

Colloidal Oatmeal (Avena Sativa) Improves Skin Barrier Through Multi-Therapy Activity.

Oats (Avena sativa) are a centuries-old topical treatment for a variety of skin barrier conditions, including dry skin, skin rashes, and eczema; however, few studies have investigated the actual mechanism of action for the skin barrier strengthening activity of colloidal oatmeal. Four extracts of colloidal oatmeal were prepared with various solvents and tested in vitro for skin barrier related gene expression and activity. Extracts of colloidal oatmeal were found to induce the expression of genes related to epidermal differentiation, tight junctions and lipid regulation in skin, and provide pH-buffering capacity. Colloidal oatmeal boosted the expression of multiple target genes related to skin barrier, and resulted in recovery of barrier damage in an in vitro model of atopic dermatitis. In addition, an investigator-blinded study was performed with 50 healthy female subjects who exhibited bilateral moderate to severe dry skin on their lower legs. Subjects were treated with a colloidal oatmeal skin protectant lotion. Clinically, the colloidal oatmeal lotion showed significant clinical improvements in skin dryness, moisturization, and barrier. Taken together, these results demonstrate that colloidal oatmeal can provide clinically effective benefits for dry and compromised skin by strengthening skin barrier.

J Drugs Dermatol. 2016;15(6):684-690.

Topically applied ceramide accumulates in skin glyphs.

Ceramides (CERs), structural components of the stratum corneum (SC), impart essential barrier properties to this thin outer layer of the epidermis. Variations in CER species within this layer have been linked to several skin diseases. A recent proliferation of CER-containing topical skin-care products warrants the elucidation of CER penetration profiles in both healthy and diseased skin. In the current study, the spatial distributions of CER concentration profiles, following topical application of two species of CER, were tracked using infrared imaging. Suspensions of single-chain perdeuterated sphingosine and phytosphingosine CER in oleic acid were applied, in separate experiments, to the surface of healthy intact ex vivo human skin using Franz diffusion cells. Following either a 24- or 48-hour incubation period at 34°C, infrared images were acquired from microtomed skin sections. Both CER species accumulated in glyph regions of the skin and penetrated into the SC, to a limited extent, only in these regions. The concentration profiles observed herein were independent of the CER species and incubation time utilized in the study. As a result, a very heterogeneous, sparse, spatial distribution of CERs in the SC was revealed. In contrast, oleic acid was found to be fairly homogeneously distributed throughout the SC and viable epidermis, albeit at lower concentrations in the latter. A more uniform, lateral distribution of CERs in the SC would likely be important for barrier efficacy or enhancement.

Visible Light Induces Melanogenesis in Human Skin through a Photoadaptive Response.

Visible light (400-700 nm) lies outside of the spectral range of what photobiologists define as deleterious radiation and as a result few studies have studied the effects of visible light range of wavelengths on skin. This oversight is important considering that during outdoors activities skin is exposed to the full solar spectrum, including visible light, and to multiple exposures at different times and doses. Although the contribution of the UV component of sunlight to skin damage has been established, few studies have examined the effects of non-UV solar radiation on skin physiology in terms of inflammation, and limited information is available regarding the role of visible light on pigmentation. The purpose of this study was to determine the effect of visible light on the pro-pigmentation pathways and melanin formation in skin. Exposure to visible light in ex-vivo and clinical studies demonstrated an induction of pigmentation in skin by visible light. Results showed that a single exposure to visible light induced very little pigmentation whereas multiple exposures with visible light resulted in darker and sustained pigmentation. These findings have potential implications on the management of photo-aggravated pigmentary disorders, the proper use of sunscreens, and the treatment of depigmented lesions.

One-year topical stabilized retinol treatment improves photodamaged skin in a double-blind, vehicle-controlled trial.

BACKGROUND: Retinol, a precursor of retinoic acid, has great potentials as a topical anti-aging molecule; however, only a handful of clinical investigations have been published to date. OBJECTIVE: This study aimed to assess the efficacy and safety of 0.1% stabilized retinol on photodamaged skin during a one-year treatment. METHODS: The investigation included two 52-week, double-blind, vehicle-controlled studies. In the main study, 62 subjects applied either a stabilized retinol formulation or its vehicle to the full face. A second exploratory study evaluated histological/histochemical markers in 12 subjects after 52 weeks of either retinol or vehicle use on contralateral dorsal forearms. RESULTS: The retinol group showed significant photodamage improvement over vehicle at all timepoints during the study. After 52 weeks, retinol had improved crow's feet fine lines by 44%, and mottled pigmentation by 84%, with over 50% of subjects showing +2 grades of improvement in many parameters. Additionally, at week 52, histochemical data confirmed the clinical results, showing increased expression of type I procollagen, hyaluronan, and Ki67 as compared to vehicle. CONCLUSION: This study confirms that a stabilized retinol (0.1%) formulation can significantly improve the signs of photoaging, and improvements in photodamage continue with prolonged use.

p38 MAP Kinase Inhibition Reduces Propionibacterium acnes-Induced Inflammation in Vitro.

INTRODUCTION: Propionibacterium acnes, a ubiquitous skin bacterium, stimulates keratinocytes to produce a number of proinflammatory cytokines and may contribute to inflammatory acne. The aim of the study was to investigate whether P. acnes-induced proinflammatory cytokine release is mediated by P. acnes-induced activation of p38 mitogen-activated protein kinase (p38 MAPK or p38) in human keratinocytes. METHODS: Immunohistochemistry was used to evaluate p38 phosphorylation in human skin samples with or without acne. Primary human keratinocytes and epidermal skin equivalents were exposed to viable P. acnes. Phosphorylation of MAPKs without or with p38 inhibitors was examined by Western blot and cytokine secretion was detected by Enzyme-Linked Immunosorbent Assay (ELISA). RESULTS: Increased levels of phospho-p38 were observed in human acne lesions, predominantly in follicular and perifollicular keratinocytes. Exposure of cultured human keratinocytes to viable P. acnes resulted in phosphorylation of multiple members of the MAPK family, including rapid and transient activation of p38 and extracellular signal-related kinase (ERK1/2) and relatively slow but sustained activation of c-Jun N-terminal kinases (JNK1/2). Viable P. acnes induced the secretion of interleukin-1α (IL-1α), tumor necrosis factor-α (TNF-α), and IL-8 from human keratinocytes. The phosphorylation of p38 (phospho-p38) and the secretion of cytokines induced by P. acnes in cultured keratinocytes were inhibited by SB203580, a p38α/ß inhibitor. Furthermore, SCIO-469, a selective inhibitor of p38α, showed similar effects in cultured keratinocytes. Topical treatment of SCIO-469 inhibited the P. acnes-induced phospho-p38 and cytokine secretion in human epidermal equivalents. CONCLUSION: The data demonstrate that P. acnes induces p38-dependent inflammatory responses in keratinocytes, and suggest that p38 may play an important role in the pathogenesis of inflammatory acne. FUNDING: Johnson & Johnson.

Keratinocyte differentiation and upregulation of ceramide synthesis induced by an oat lipid extract via the activation of PPAR pathways.

Activation of peroxisome proliferator-activated receptors (PPARs) has been shown to have an important role in skin barrier function by regulating differentiation and lipid synthesis in keratinocytes. Oat (Avena sativa) has long been used as a soothing agent to relieve skin irritations, and the clinical benefits of topical oat formulations have been proven; however, the mechanistic understanding of oat's mode of action remains unknown. We investigated whether an oat lipid extract could activate PPARs and subsequently increase epidermal lipid synthesis and differentiation markers. Primary human epidermal keratinocytes and transformed cell lines were treated with PPAR agonists and oat lipid extracts to investigate the PPAR agonism. PPAR target genes and epidermal differentiation markers were analysed using quantitative real-time PCR and HPTLC analysis. Oat lipid extract demonstrated robust dual agonism for PPARα and PPARß/δ, and increased direct PPAR target gene induction in primary human keratinocytes. In addition, oat oil treatment increased both receptor expression and, consistent with the literature on PPARs, oat oil treatment resulted in a significant upregulation of differentiation genes (involucrin, SPRRs and transglutaminase 1) and ceramide processing genes (ß-glucocerebrosidase, sphingomyelinases 3 and ABCA12). Further, oat oil treatment in keratinocytes significantly increased ceramide levels (70%), suggesting a functional translation of PPAR activation by oat oil in keratinocytes. Taken together, these results demonstrate that oat lipids possess robust dual agonistic activities for PPARα and PPARß/δ, increase their gene expression and induce differentiation and ceramide synthesis in keratinocytes, which can collectively improve skin barrier function.

Anti-inflammatory activities of colloidal oatmeal (Avena sativa) contribute to the effectiveness of oats in treatment of itch associated with dry, irritated skin.

BACKGROUND: Oat (Avena sativa) in colloidal form is a centuries-old topical treatment for a variety of skin conditions, including skin rashes, erythema, burns, itch, and eczema; however, few studies have investigated the exact mechanism of action for the anti-inflammatory activity of colloidal oatmeal. METHODS: Four extracts of colloidal oatmeal were made with various solvents and tested in anti-inflammatory and antioxidant assays. In addition, an investigator blind study was performed with twenty-nine healthy female subjects who exhibited bilateral mild to moderate itch with moderate to severe dry skin on their lower legs. Subjects were treated with a colloidal oatmeal skin protectant lotion. RESULTS: Extracts of colloidal oatmeal diminished pro-inflammatory cytokines in vitro and the colloidal oat skin protectant lotion showed significant clinical improvements in skin dryness, scaling, roughness, and itch intensity. CONCLUSIONS: These results demonstrate that colloidal oat extracts exhibit direct anti-oxidant and anti-inflammatory activities, which may provide the mechanisms for observed dermatological benefits while using the colloidal oatmeal skin protectant lotion.

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.

Clinical efficacy and safety of 4-hexyl-1,3-phenylenediol for improving skin hyperpigmentation.

Hyperpigmentation disorders are of social and cosmetic concerns to many individuals due to their prevalent locations on highly visible parts of the body. Topical formulation containing hydroquinone is the most widely used remedy for the treatment of hyperpigmentation disorders. However, reports of side effects in long-term usage have raised concerns for its use in cosmetic products. Thus, it is highly desirable to develop a safe and effective alternative to treat hyperpigmentation disorders. The objective of the current study is to investigate the de-pigmenting efficacy of 4-hexyl-1,3-phenylenediol in various in vitro models and in a randomized controlled clinical study. We showed that 4-hexyl-1,3-phenylenediol significantly reduced melanogenesis in primary human melanocytes, murine melanoma cells, and pigmented human epidermal equivalents. It was determined that the reduction in melanogenesis is mediated through inhibition of tyrosinase enzyme activity and protein expression. Further investigation revealed that the inhibition of melanogenesis is reversible and is not associated with cellular toxicity in melanocytes. In addition, significant improvements in key clinical parameters such as overall skin lightening, appearance of spots on the cheeks, overall contrast between spots and surrounding skin, and overall pigmentation size were detected in a double-blinded, randomized controlled clinical study. In conclusion, our findings clearly demonstrated the potency of 4-hexyl-1,3-phenylenediol in modulating skin pigmentation, and it is safe and well tolerated after 12-week topical application.

Galvanic microparticles increase migration of human dermal fibroblasts in a wound-healing model via reactive oxygen species pathway.

Electrical signals have been implied in many biological mechanisms, including wound healing, which has been associated with transient electrical currents not present in intact skin. One method to generate electrical signals similar to those naturally occurring in wounds is by supplementation of galvanic particles dispersed in a cream or gel. We constructed a three-layered model of skin consisting of human dermal fibroblasts in hydrogel (mimic of dermis), a hydrogel barrier layer (mimic of epidermis) and galvanic microparticles in hydrogel (mimic of a cream containing galvanic particles applied to skin). Using this model, we investigated the effects of the properties and amounts of Cu/Zn galvanic particles on adult human dermal fibroblasts in terms of the speed of wound closing and gene expression. The collected data suggest that the effects on wound closing are due to the ROS-mediated enhancement of fibroblast migration, which is in turn mediated by the BMP/SMAD signaling pathway. These results imply that topical low-grade electric currents via microparticles could enhance wound healing.

A purified feverfew extract protects from oxidative damage by inducing DNA repair in skin cells via a PI3-kinase-dependent Nrf2/ARE pathway.

BACKGROUND: Environmental factors such as solar ultraviolet (UV) radiation and other external aggressors provide an oxidative challenge that is detrimental to skin health. The levels of endogenous antioxidants decrease with age, thus resulting in less protection and a greater potential for skin damage. The NF-E2-related factor-2 (Nrf2) - antioxidant response element (ARE) pathway is a primary defense mechanism against oxidative stress, and induces the expression of antioxidant, detoxification and repair genes. Activation of ARE-Nrf2 can help restore oxidative homeostasis of the skin and play a role in inflammatory response and DNA repair mechanisms. OBJECTIVE: To evaluate the role of a purified parthenolide-depleted Feverfew (PD-Feverfew) extract on the ARE-Nrf2 pathway and DNA repair in skin cells. METHODS: These studies were undertaken in primary human keratinocytes or KB cells using Luciferase Promoter assay, siRNA transfection studies, Western blot analyses, Immunofluorescence microscopy, comet assay and quantitative real-time PCR. RESULTS: PD-Feverfew was found to induce Nrf2 nuclear translocation and to increase ARE activity in a dose dependent manner. Furthermore, knockdown of Nrf2 resulted in suppression of PD-Feverfew-induced ARE activity. PD-Feverfew was also found to induce phosphorylation of Akt, a kinase downstream of PI3K. Inhibition of PI3K via pre-treatment with the selective pharmacological inhibitor, LY294002, abolished PD-Feverfew-induced Nrf2/ARE activation. PD-Feverfew also reduced UV-induced DNA damage in a PI3K and Nrf2-dependent manner. CONCLUSIONS: Therefore, by increasing endogenous defense mechanisms and aid in DNA repair of damaged skin cells via activation of a PI3K-dependent Nrf2/ARE pathway, PD-Feverfew may help protect the skin from numerous environmental aggressors.

Metabolomic analysis of sun exposed skin.

It is very well known that exposure of skin to sun chronically accelerates the mechanism of aging as well as making it more susceptible toward skin cancer. This aspect of aging has been studied very well through genomics and proteomics tools. In this study we have used a metabolomic approach for the first time to determine the differences in the metabolome from full thickness skin biopsies from sun exposed and sun protected sites. We have primarily investigated the energy metabolism and the oxidative pathway in sun exposed skin. Biochemical pathway analysis revealed that energy metabolism in photoexposed skin is predominantly anaerobic. The study also validated the increased oxidative stress in skin.