The role of topical retinoids in the treatment of photoaging

Human Hair Follicle Mesenchymal Stem Cell-Derived Exosomes Attenuate UVB-Induced Photoaging via the miR-125b-5p/TGF-β1/Smad Axis

Cutaneous photoaging, induced by chronic exposure to ultraviolet (UV) radiation, typically manifests as alterations in both the physical appearance and functional properties of the skin and may predispose individuals to cancer development. Recent studies have demonstrated the reparative potential of exosomes derived from mesenchymal stem cells in addressing skin damage, while specific reports highlight their efficacy in ameliorating skin photoaging. However, the precise role of exosomes derived from human hair follicle mesenchymal stem cells (HFMSC-Exos) in the context of cutaneous photoaging remains largely unexplored. We successfully isolated HFMSC-Exos using the ultracentrifugation technique. In cellular experiments, we assessed the migration of human dermal fibroblasts (HDFs) through scratch and transwell assays, evaluated the angiogenesis of human umbilical vein endothelial cells through angiogenesis assays, and examined the expression levels of collagen and matrix metalloproteinase 1 (MMP-1) using Western blotting and quantitative reverse transcription polymerase chain reaction. Furthermore, we established a nude mouse model of photoaging to observe wrinkle formation on the dorsal surface of the animals, as well as to assess dermal thickness and collagen fiber generation through histological staining. Ultimately, we performed RNA sequencing on skin tissues from mice before and after treatment to elucidate the relevant underlying mechanisms. Our findings revealed that HFMSC-Exos effectively enhanced the migration and proliferation of HDFs and upregulated the expressions of transforming growth factor-β1 (TGF-β1), p-Smad2/p-Smad3, collagen type 1, and collagen type 3 while concurrently down-regulating MMP-1 levels in HDFs. Additionally, mice in the HFMSC-Exo group showed quicker wrinkle healing and increased collagen production. HFMSC-Exos miR-125b-5p was demonstrated to reduce skin photoaging by increasing profibrotic levels via TGF-β1 expression. UV-irradiated HDFs and photoaged nude mouse skin showed low TGF-β1 expressions, whereas overexpression of TGF-β1 in HDFs increased collagen type 1, collagen type 3, and p-Smad2/p-Smad3 expressions while decreasing MMP-1 expression. HDFs overexpressing TGF-β1 produced more collagen and altered the Smad pathway. This study demonstrated, both in vitro and in vivo, that HFMSC-Exos increased collagen formation, promoted HDF cell proliferation and migration, and reversed the senescence of UV-irradiated HDFs. TGF-β1 was identified as a target of HFMSC-Exos miR-125b-5p, which controls photoaging via regulating the Smad pathway. The antiphotoaging capabilities of HFMSC-Exos may occur via the miR-125b-5p/TGF-β1/Smad axis, suggesting a promising therapeutic approach for treating skin photoaging.

Uncovering key mechanisms and intervention therapies in aging skin

Advancements in understanding skin aging mechanisms, which encompass both external and internal aging processes, have spurred the development of innovative treatments primarily aimed at improving cosmetic appearance. These findings offer the potential for the development of novel therapeutic strategies aimed at achieving long-term, non-therapy-dependent clinical benefits, including the reversal of aging and the mitigation of associated health conditions. Realizing this goal requires further research to establish the safety and efficacy of targeting aging-related skin changes, such as pigmentation, wrinkling, and collagen loss. Systematic investigation is needed to identify the most effective interventions and determine optimal anti-aging treatment strategies. These reviews highlight the features and possible mechanisms of skin aging, as well as the latest progress and future direction of skin aging research, to provide a theoretical basis for new practical anti-skin aging strategies.

Development of dissolving microneedles loaded with fucoidan for enhanced anti-aging activity: An in vivo study in mice animal model

Skin aging occurs naturally as essential skin components gradually decline, leading to issues such as fine lines, wrinkles, and pigmentation. Fucoidan, a natural bioactive compound, holds potential for addressing these age-related concerns. However, its hydrophilic nature and substantial molecular weight hinder its absorption into the skin. In this study, we utilized polyvinyl pyrrolidone K30 (PVP) and polyvinyl alcohol (PVA) as polymers to fabricate dissolving microneedles loaded with fucoidan (DMN-F). The DMN-F formulations were examined for physical characteristics, stability, permeability, toxicity, and efficacy in animal models. These formulations exhibited consistent polymer blends with a conical structure and uniform cone-shaped design. Microneedle structure and penetration capability gradually decreased with increasing fucoidan concentration, with storage recommended at approximately 33 % relative humidity (RH). Ex vivo studies showed that DMN-F efficiently delivered up to 95.03 ± 2.36 % of the total fucoidan concentration into the skin. In vivo investigations revealed that DMN-F effectively reduced wrinkles, improved skin elasticity, maintained moisture levels, and increased epidermal thickness. Histological images provided additional evidence of DMN-F's positive effects on these aging parameters. The results confirm that the DMN-F formulation effectively delivers fucoidan into the skin, allowing it to treat and mitigate signs of aging.

Salvianolic acid B protects against UVB-induced skin aging via activation of NRF2

BACKGROUND

Prolonged exposure to sun radiation may result in harmful skin photoaging. Therefore, discovering novel anti-photoaging treatment modalities is critical. An active component isolated from Salvia miltiorrhiza (SM), Salvianolic acid B (Sal-B), is a robust antioxidant and anti-inflammatory agent. This investigation aimed to discover the therapeutic impact and pathways of salvianolic acid B for UVB-induced skin photoaging, an area that remains unexplored.

METHODS

We conducted in vitro experiments on human dermal fibroblasts (HDFs) exposed to UVB radiation, assessing cellular senescence, superoxide dismutase (SOD) activity, cell viability, proliferation, migration, levels of reactive oxygen species (ROS), and mitochondrial health. The potential mechanism of Sal-B was analyzed using RNA sequencing, with further validation through Western blotting, PCR, and nuclear factor erythroid 2-related factor 2 (NRF2) silencing methods. In vivo, a model of skin photoaging induced by UVB in nude mice was employed. The collagen fiber levels were assessed utilizing hematoxylin and eosin (H&E), Masson, and Sirus red staining. Additionally, NRF2 and related gene and protein expression levels were identified utilizing PCR and Western blotting.

RESULTS

Sal-B was found to significantly counteract photoaging in UVB-exposed skin fibroblasts, reducing aging-related decline in fibroblast proliferation and an increase in apoptosis. It was observed that Sal-B aids in protecting mitochondria from excessive ROS production by promoting NRF2 nuclear translocation. NRF2 knockdown experiments established its necessity for Sal-B's anti-photoaging effects. The in vivo studies also verified Sal-B's anti-photoaging efficacy, surpassing that of tretinoin (Retino-A). These outcomes offer novel insights into the contribution of Sal-B in developing clinical treatment modalities for UVB-induced photodamage in skin fibroblasts.

CONCLUSION

In this investigation, we identified the Sal-B protective impact on the senescence of dermal fibroblasts and skin photoaging induced by radiation of UVB. The outcomes suggest Sal-B as a potential modulator of the NRF2 signaling pathway.

Research on the anti-aging efficacy of fermented lysate VHProbi® MixA as the functional skincare ingredient

AIMS

This study aimed to investigate the efficacy of a cream containing VHProbi® MixA for improving skin aging.

METHODS AND RESULTS

In vitro studies demonstrated that the lysate produced from Lacticaseibacillus paracasei E12 (E12) exhibited immunoregulatory effects in a 3D skin model, with significant reductions in levels of interleukin (IL)-1α, IL-1β, and IL-8 (P < 0.05) compared with the control group. In addition, the lysate of E12 mitigated the hydrogen peroxide-induced mortality of 3D skin cells and enhanced the transepithelial electrical resistance to show significant differences in comparison with control (P < 0.05), suggesting favorable antioxidant effects. The antioxidant capacity of the lysate of E12 was also confirmed using the Caenorhabditis elegans N2 model. C. elegans N2 fed the E12 strain showed a significantly higher % survival than those fed Escherichia coli OP50 (P < 0.05). Subsequently, VHProbi® MixA was formulated using the fermented lysates of E12, Lactiplantibacillus plantarum E15, and Limosilactobacillus reuteri E18. In a clinical study to ascertain if a cream containing VHProbi® MixA could improve the skin aging trends, participants were asked to use the investigational products for 60 days, and six indicators, transepidermal water loss (TEWL), hydration, elasticity, wrinkles, skin texture (roughness), and pores were measured at baseline and the endpoint of the study. A self-evaluation questionnaire analysis was also provided. TEWL, wrinkles, skin texture, and thickness of pores decreased significantly after treatment with the cream for 60 days (P < 0.01), whereas hydration and elasticity increased significantly (P < 0.01), in comparison to the baseline measurements.

CONCLUSIONS

We hypothesize that the use of the cream containing VHProbi® MixA could be favorable for skin anti-aging management.

Enhanced In Vitro Anti-Photoaging Effect of Degraded Seaweed Polysaccharides by UV/H2O2 Treatment

The high molecular weight and poor solubility of seaweed polysaccharides have limited their function and application. In this study, ultraviolet/hydrogen peroxide (UV/H2O2) treatment was used to prepare low-molecular-weight seaweed polysaccharides from Sargassum fusiforme. The effects of UV/H2O2 treatment on the physicochemical properties and anti-photoaging activity of S. fusiforme polysaccharides were studied. UV/H2O2 treatment effectively degraded polysaccharides from S. fusiforme (DSFPs), reducing their molecular weight from 271 kDa to 26 kDa after 2 h treatment. The treatment did not affect the functional groups in DSFPs but changed their molar percentage of monosaccharide composition and morphology. The effects of the treatment on the anti-photoaging function of S. fusiforme polysaccharides were investigated using human epidermal HaCaT cells in vitro. DFSPs significantly improved the cell viability and hydroxyproline secretion of UVB-irradiated HaCaT cells. In particular, DSFP-45 obtained from UV/H2O2 treatment for 45 min showed the best anti-photoaging effect. Moreover, DSFP-45 significantly increased the content and expression of collagen I and decreased those of pro-inflammatory cytokines, including interleukin-1β, interleukin-6, and tumor necrosis factor-α. Thus, UV/H2O2 treatment could effectively improve the anti-photoaging activity of S. fusiforme polysaccharides. These results provide some insights for developing novel and efficient anti-photoaging drugs or functional foods from seaweed polysaccharides.

Association of Early Clinical Response to Laser Rejuvenation of Photoaged Skin with Increased Lipid Metabolism and Restoration of Skin Barrier Function

Laser resurfacing treatments for photoaged skin have improved dramatically over the past decades, but few studies have examined the molecular mechanisms underlying differences in clinical response. Seventeen white female participants with moderate-to-severe photoaging received nonablative fractional laser treatment on the face and forearm once monthly for 6 months. Biopsies for microarray analysis were performed at baseline and 7 days after facial treatment and at baseline and 1, 7, 14, and 29 days after forearm treatment in each participant, resulting in 119 total samples. Participants were stratified into fast (n = 11) and slow (n = 6) responders on the basis of the presence of clinical improvement after the first treatment. Microarray analysis revealed the upregulation of genes associated with matrix metalloproteinases, collagen and extracellular components, TGF-β signaling, double-stranded RNA signaling, and retinoic acid synthesis after treatment that did not differ significantly between fast and slow responders. Cluster and enrichment analyses suggested significantly greater activation of lipid metabolism and keratinocyte differentiation in fast responders, who showed greater upregulation of acyltransferases, fatty acid elongases, fatty acid 2-hydroxylase, fatty acid desaturases, and specific keratins that may contribute to epidermal barrier function. These results create, to our knowledge, a previously unreported atlas of molecular changes that correlate with improvements in photoaging after laser therapy.

Delivery and diffusion of retinal in dermis and epidermis through the combination of prodrug nanoparticles and detachable dissolvable microneedles

To minimize chemical degradation of retinal, we graft this aldehyde on chitosan chains to make them self-assemble into pro-retinal nanoparticles (PRNs), which we then load into detachable dissolvable microneedles (DDMNs) made of 1:1 (by weight) hyaluronic acid/maltose. The presence of PRNs in the hyaluronic acid-maltose needle matrix also helps improve the microneedles' mechanical strength. Ex vivo administration of PRN-loaded DDMNs on fresh porcine ear skin shows, as observed by stereomicroscopic and confocal fluorescence microscopic analyses of the cross-sectioned tissue pieces, complete deposition followed by dissolution of the needles and diffusion of the PRNs in epidermis and dermis. Rats administered with a single dose of PRN-loaded DDMNs show significantly increased epidermal thickness as compared to rats administered with control DDMNs (no PRN). Both the PRN-loaded DDMNs and the control DDMNs produce no skin irritation in rats.

Natural Compounds and Products from an Anti-Aging Perspective

Aging is a very complex process that is accompanied by a degenerative impairment in many of the major functions of the human body over time. This inevitable process is influenced by hereditary factors, lifestyle, and environmental influences such as xenobiotic pollution, infectious agents, UV radiation, diet-borne toxins, and so on. Many external and internal signs and symptoms are related with the aging process and senescence, including skin dryness and wrinkles, atherosclerosis, diabetes, neurodegenerative disorders, cancer, etc. Oxidative stress, a consequence of the imbalance between pro- and antioxidants, is one of the main provoking factors causing aging-related damages and concerns, due to the generation of highly reactive byproducts such as reactive oxygen and nitrogen species during the metabolism, which result in cellular damage and apoptosis. Antioxidants can prevent these processes and extend healthy longevity due to the ability to inhibit the formation of free radicals or interrupt their propagation, thereby lowering the level of oxidative stress. This review focuses on supporting the antioxidant system of the organism by balancing the diet through the consumption of the necessary amount of natural ingredients, including vitamins, minerals, polyunsaturated fatty acids (PUFA), essential amino acids, probiotics, plants' fibers, nutritional supplements, polyphenols, some phytoextracts, and drinking water.

Simultaneous HPLC Determination of Clindamycin Phosphate, Tretinoin, and Preservatives in Gel Dosage Form Using a Novel Stability-Indicating Method

The most well-known, effective medicines for acne therapy are clindamycin phosphate and tretinoin. For the first time, we have developed and validated a reversed-phase HPLC stability-indicating technique for the detection of clindamycin phosphate (CLP), tretinoin (TRN), and two preservatives, methylparaben (MP) and imidazolidinyl urea (IU), simultaneously in this work. Most of the chromatographic conditions in the present study were optimized to achieve better separation. The best separation results were obtained using gradient elution on a C-18 (250 × 4.6 mm), 5 µm column, with a mobile phase consisting of solution A (1 mL/L ortho-phosphoric acid in water) and solution B (methanol), at a flow rate of 1.0 mL/min, with UV detection at wavelengths of 200 nm and 353 nm. Standard parameters such as system suitability, precision, accuracy, specificity, robustness, linearity, range, detection limit, quantification limit, and reagent stability were used to validate the developed technique. According to the standards of the International Council for Harmonization, all of the experimental parameters were found to be within allowable bounds (ICH). The simultaneous concentrations of clindamycin phosphate, tretinoin, methylparaben, and imidazolidinyl urea in pharmaceutical formulations were successfully determined using the suggested approach. The proposed RP-HPLC method detected no interfering peaks in the chromatogram. We may conclude from the data that the new RP-HPLC method can be utilized in pharmaceutical laboratories to simultaneously assess clindamycin phosphate, tretinoin, and two preservatives, methylparaben and imidazolidinyl urea, for both qualitative and quantitative analyses.

Protective Effect of Fat-Tissue-Derived Products against Ultraviolet Irradiation-Induced Photoaging in Mouse Skin

BACKGROUND

Exposure to ultraviolet radiation causes erythema, inflammation, and photoaging. Mechanical micronization of adipose tissue can concentrate functional cells and has great potential as an alternative for regenerative medicine. Stromal vascular fraction gel is produced by means of a series of mechanical processes of lipoaspirates and can be injected intradermally. This study aimed to assess the therapeutic effect of stromal vascular fraction gel on photoaging skin.

METHODS

A photoaging model was established in nude mice. Photoaging mice received treatments of stromal vascular fraction gel, fat, tretinoin, or phosphate-buffered saline. Photoaging skin was characterized by histologic and immunohistochemical analyses. Expression of collagen synthesis-related or photoaging-related genes was assessed.

RESULTS

Stromal vascular fraction gel, fat, and tretinoin reversed photoaging, whereas stromal vascular fraction gel demonstrated the greatest therapeutic effect. Treatment with stromal vascular fraction gel restored intradermal fat tissue content and increased dermal collagen density. Injection of stromal vascular fraction gel had the strongest effect on stimulating fibroblasts and increasing the expression of transforming growth factor β1 (TGF-β1), propeptide of type-I procollagen, and Smad 2, decreasing the expression of Smad 3, compared with fat and tretinoin. Expression of photoaging-related genes was significantly reduced, whereas expression of fibulin-5 was significantly increased after stromal vascular fraction gel treatment.

CONCLUSIONS

Stromal vascular fraction gel demonstrated remarkable therapeutic effects in reversing photoaging skin. Stromal vascular fraction gel can be injected intradermally and survive within dermal layer after grafting. This product increased TGF-β1expression and activated fibroblasts to produce propeptide of type I procollagen, thus increasing the amount of collagen I, leading to thickening of the dermis of photoaging skin.

Synthesis of Retinol-Loaded Lipid Nanocarrier via Vacuum Emulsification to Improve Topical Skin Delivery

Retinol has been widely used as an anti-wrinkle active ingredient in cosmetic fields. However, the oxidation of retinol by air was one of the critical problems for application in the skincare field. In this study, Retinol-loaded lipid nanocarriers were prepared via the vacuum emulsification method to increase the stability of retinol vulnerable to air and optimized encapsulation conditions and to increase the penetration efficiency into skin. Optimizing the components of lipid nanocarriers, gradients of carbon chain C8-22 using various lipid species which made the amorphous structure and enough spaces to load retinol inside the capsules were estimated from the lower enthalpy change and peak shift in DSC analysis. The vacuum-assisted lipid nanocarriers (VLN) could help suppress oxidation, which could have advantages to increase the thermal stability of retinol. The retinol-loaded VLN (VLN-ROL) had narrow size distribution under 0.3 PDI value, under 200 nm scaled particle size, and fully negative surface charge of about -50 mV for the electrostatic repulsion to avoid aggregation phenomenon among the lipid nanoparticles. It maintained 90% or more retinol concentration after 4 weeks of storage at 25, 40 and 50 °C and kept stable. The VLN-ROL-containing cream showed improved penetration efficiency applied to porcine skins compared to the commercial retinol 10S from BASF. The total amount of retinol into the skin of VLN-ROL (0.1% of retinol) was enhanced by about 2.2-fold (2.86 ± 0.23 μg) higher than that in 0.1% of bare retinol (about 1.29 ± 0.09 μg). In addition, applied on a 3D Human skin model, the epidermal thickness and the relative percentage of dermal collagen area effectively increased compared to the control and retinol, respectively. Additionally, the level of secreted IL-1α was lower and epidermal damage was weaker than commercial product A. This retinol-loaded lipid nanocarrier could be a potentially superior material for cosmetics and biomedical research.

RETINOIDS IN DERMATOLOGY:FUNCTIONAL ACTIVITY AND PROSPECTS OF SYNTHETIC ANALOGUES

The aim of the work was to analyze and summarize information on the functional activity of known retinoids, as well as to determine the directions of their modification and prospects for the use of their synthetic analogues in dermatology. The literature on retinoids metabolism stages in the human body, the mechanisms of their action and the properties that determine their use in various medical fields was considered and analyzed. Information on dermatological diseases treatment with natural retinoids and their synthetic analogues was summarized. The modern classification of retinoids based on the peculiarities of their chemical structure and functional activity is given, the relationship between these characteristics and the direction of use of such drugs in dermatology and cosmetology is shown. Prospects for the practical application of synthetic retinoids represented mainly by polyaromatic compounds are due to their higher stability and efficiency, as well as reduced irritant effect due to selectivity for nuclear receptors.

Molecular Mechanism of Epidermal Barrier Dysfunction as Primary Abnormalities

Epidermal barrier integrity could be influenced by various factors involved in epidermal cell differentiation and proliferation, cell–cell adhesion, and skin lipids. Dysfunction of this barrier can cause skin disorders, including eczema. Inversely, eczema can also damage the epidermal barrier. These interactions through vicious cycles make the mechanism complicated in connection with other mechanisms, particularly immunologic responses. In this article, the molecular mechanisms concerning epidermal barrier abnormalities are reviewed in terms of the following categories: epidermal calcium gradients, filaggrin, cornified envelopes, desquamation, and skin lipids. Mechanisms linked to ichthyoses, atopic dermatitis without exacerbation or lesion, and early time of experimental irritation were included. On the other hand, the mechanism associated with epidermal barrier abnormalities resulting from preceding skin disorders was excluded. The molecular mechanism involved in epidermal barrier dysfunction has been mostly episodic. Some mechanisms have been identified in cultured cells or animal models. Nonetheless, research into the relationship between the causative molecules has been gradually increasing. Further evidence-based systematic data of target molecules and their interactions would probably be helpful for a better understanding of the molecular mechanism underlying the dysfunction of the epidermal barrier.

IL-1 Receptor Antagonist Reduced Chemical-Induced Keratinocyte Apoptosis through Antagonism to IL-1α/IL-1β

Extracellular interleukin 1 alpha (IL-1α) released from keratinocytes is one of the endpoints for in vitro assessments of skin irritancy. Although cells dying via primary skin irritation undergo apoptosis as well as necrosis, IL-1α is not released in apoptotic cells. On the other hand, active secretion has been identified in interleukin-1 receptor antagonist (IL-1ra), which was discovered to be a common, upregulated, differentially-expressed gene in a microarray analysis performed with keratinocytes treated using cytotoxic doses of chemicals. This study examined whether and how IL-1ra, particularly extracellularly released IL-1ra, was involved in chemically-induced keratinocyte cytotoxicity and skin irritation. Primary cultured normal adult skin keratinocytes were treated with cytotoxic doses of chemicals (hydroquinone, retinoic acid, sodium lauryl sulfate, or urshiol) with or without recombinant IL-1ra treatment. Mouse skin was administered irritant concentrations of hydroquinone or retinoic acid. IL-1ra (mRNA and/or intracellular/extracellularly released protein) levels increased in the chemically treated cultured keratinocytes with IL-1α and IL-1β mRNAs and in the chemically exposed epidermis of the mouse skin. Recombinant IL-1ra treatment significantly reduced the chemically-induced apoptotic death and intracellular/extracellularly released IL-1α and IL-1β in keratinocytes. Collectively, extracellular IL-1ra released from keratinocytes could be a compensatory mechanism to reduce the chemically-induced keratinocyte apoptosis by antagonism to IL-1α and IL-1β, suggesting potential applications to predict skin irritation.

Increased Skin Irritation by Hydroquinone and Rsetinoic Acid Used in Combination

Background

Hydroquinone (HQ) is frequently combined with retinoic acid (RA) to enhance lightening efficacy, which may also affect skin irritancy. Although skin irritation leads to postinflammatory hyperpigmentation, little research has been performed to compare skin irritancy between each component and the combination.

Objective

This study was done to examine whether HQ-RA combination increased skin irritation induced by HQ or RA alone.

Methods

Patch testing was performed using maximum therapeutic and higher concentrations of HQ and RA in 10 volunteers, and then, it was performed using their popular therapeutic concentrations and combination in the other 20 volunteers. In vitro irritation was also assessed in primary cultured normal human keratinocytes treated with 80% and 50% cell survival doses of HQ, 80% cell survival dose of RA, and their combination.

Results

The combination in patch testing induced stronger erythema than the corresponding concentrations of HQ and RA, which was remarkable with use of combination of higher concentrations. In cultured keratinocytes, the RA combination significantly decreased cell viability, but increased cytotoxicity and extracellular interleukin 1 alpha release with corresponding doses of HQ.

Conclusion

The results of patch tests and in vitro irritation assessment tests suggested that HQ and RA increased skin irritation when used in combination.

Tretinoin-based formulations - influence of concentration and vehicles on skin penetration

Tretinoin is used in the management of acne and it is part of a gold standard treatment for photoaging. It has also been reported as an agent for superficial chemical peeling in highly concentrated formulations with few considerations about skin penetration. The aim of this study was to evaluate the influence of drug concentration and vehicles currently used on skin penetration of tretinoin. In vitro permeation tests were carried out using Franz diffusion cells fitted with porcine ear skin and 10% aqueous methanol in the receptor compartment. Formulations studied, cream or hydroalcoholic dispersion, containing 0.25%, 1% and 5% of tretinoin were placed in the donor compartment for six hours. Tretinoin concentration in skin layers was measured by high performance liquid chromatography. The largest amount of tretinoin from both vehicles was detected in stratum corneum with significant differences among the three concentrations. The hydroalcoholic dispersion was the best vehicle. Significant amounts of tretinoin were found even in deep layers of epidermis. The formulation with 0.25% tretinoin showed better results when considered the amount of tretinoin on skin in terms of percentage. Finally, skin penetration of tretinoin was influenced by vehicle and concentration of this drug used in formulation.

Retinoic acid and hydroquinone induce inverse expression patterns on cornified envelope-associated proteins: implication in skin irritation

BACKGROUND

Hydroquinone (HQ) with or without retinoic acid (RA) is routinely used for the treatment of hyperpigmented conditions. Skin irritation is a major problem with popular depigmenting agents, resulting in postinflammatory hyperpigmentation.

OBJECTIVE

To examine the molecular mechanism associated with skin irritation by RA or HQ.

METHODS

A genome-wide transcriptional profiling analysis was performed using monolayer cultures of human keratinocytes treated with or without irritant doses of RA, HQ, or sodium lauryl sulfate (SLS), a representative irritant. Differentially expressed genes (DEGs) were mapped on human chromosomes using a Manhattan plot. For the validation of candidate DEGs, the chemicals with different concentrations of varying irritation intensities were applied in vitro and in vivo and analyzed using real time-PCR and Western blotting.

RESULTS

DEGs mapped to the 1q21 locus, which is composed of a cluster of genes encoding the cornified envelope precursors, showed an inverse expression pattern in response to HQ and RA. Concentrations of RA and HQ that induced a broad range of irritant responses in cultured cells or mice skin also induced inverse effects on the expression of cornified envelope-associated proteins.

CONCLUSIONS

Genetic modulation on cornified envelope-associated proteins by RA-induced irritation, which may be involved in physiological skin barrier disturbance, could be inverse to that by HQ- or SLS-induced irritation.

Topical retinoids in skin ageing: a focused update with reference to sun-induced epidermal vitamin A deficiency

Vitamin A is an important constituent of the epidermis, where it plays a crucial role in epidermal turnover. A deficiency of epidermal vitamin A may be the consequence of nutritional vitamin A deficiency, exposure to sunlight or any UV source, oxidative stress or chronological ageing. As a consequence, any treatment aiming at increasing epidermal vitamin A would exert a protective effect against these deleterious conditions. Retinoids may counteract some deleterious actions of UV radiation by physical and biological mechanisms. Topical natural retinoic acid precursors such as retinaldehyde or retinol are less irritant than acidic retinoids and may prevent epidermal vitamin A deficiency due to nutritional deficiency, exposure to sunlight or any condition leading to free radical production. Retinoids may be combined with other compounds with complementary actions against ageing, nutritional deficiency and cancer, such as antioxidants, to potentiate their beneficial effects in the skin.

Tretinoin cyclodextrin complex (RA/CyD) causes less irritation with an equal antiwrinkle effect compared with conventional tretinoin: clinical and histologic studies of photoaged skin

BACKGROUND

Topical tretinoin [all-trans-retinoic acid (RA)] currently is widely used to treat photoaged skin. However, undesirable side effects such as erythema, irritation, and scaling are unavoidable and limit the use of tretinoin. To address these issues, the authors developed the tretinoin cyclodextrin complex (RA/CyD), which is tretinoin encapsulated by cyclodextrin. Cyclodextrins are cyclic oligosaccharides commonly used in food additives and fabric fresheners. This study aimed to evaluate the antiwrinkle effect of RA/CyD and alleviation of the side effects compared with RA treatment alone.

METHODS

In this study, 12 photoaged patients completed an 8 week study using RA and RA/CyD in a double-blind manner. Before and after the treatment, the patients' evaluations, wrinkle scores, skin elasticity, and wrinkle area measurement using skin replica were evaluated. Three men were recruited for histologic analysis.

RESULTS

The patients reported that undesirable irritant reactions were more moderate with RA/CyD than with RA. In the assessment of wrinkle scores, skin elasticity, and wrinkle area measurement, RA/CyD demonstrated an antiwrinkle effect statistically equal to that of RA. In histology, both RA/CyD and RA demonstrated epidermal hyperplasia. In immunohistochemistry, inflammation induced by RA/CyD was more moderate than that induced by RA.

CONCLUSION

The findings show that RA and RA/CyD result in the equivalent clinical improvement for patients with photoaging. The use of RA/CyD overcomes the drawbacks of RA while possessing equal effect. It is expected that CyD will broaden tretinoin treatment.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors at www.springer.com/00266.

Topical retinoids in the management of photodamaged skin: from theory to evidence-based practical approach

Skin, being exposed directly to the environment, represents a unique model for demonstrating the synergistic effects of intrinsic and extrinsic factors on the ageing process. Ultraviolet radiation (UVR) is the major factor among exogenous stressors responsible for premature skin ageing. The problem of skin ageing has captured public attention and has an important social impact. Different therapeutic approaches have been developed to treat cutaneous ageing and to diminish or prevent the negative effects of UVR. Topical retinoids represent an important and powerful class of molecules in the dermatologist's hands for the treatment of photodamaged skin. Since their introduction more than 20 years ago, topical retinoids have shown beneficial efficacy and good safety profiles in the management of photodamaged skin, and as therapeutic anti-ageing agents. This review provides a brief retrospective of the development of topical retinoids in the treatment of photodamaged skin, elucidates their mechanism of action, delineates their use and addresses clinical, pharmaceutical and regulatory issues in connection with their intended use.

Cosmeceuticals vitamins

The term cosmeceutical was created over 25 years ago to define products with active substances that cannot be considered cosmetics or drugs. Cosmeceuticals are increasingly popular, with sales representing one of the largest growing segments of the skin care market. These products are found in many forms, including vitamins, peptides, growth factors, and botanical extracts. Cosmeceuticals that contain topically applied vitamins have an increasing role in skin care.

Profilometric and morphometric response of murine skin to cosmeceutical agents

OBJECTIVE

To investigate whether topical antiaging compounds can reduce wrinkle depth as noted at replica profilometry with comparable changes in histologic findings in hairless mice.

METHODS

Commercial retinoic acid cream, a peptide lotion, and a soy cream were applied to the dorsal skin for 4 weeks. Silicone-negative replicas of treated and untreated skin surface were photographed and evaluated for traditional features of surface roughness. Skin samples were processed using histomorphometry and immunohistochemistry of proliferating cell nuclear antigen. Quantitative light microscopic data were acquired for estimating replication of epidermal keratinocytes, epidermal thickness, and depth of dermal collagen bundles.

RESULTS

Data were analyzed by comparing means with 1-way analysis of variance, and significant changes in all measurements were noted. Augmented keratinocyte proliferation and thickening of viable epidermis were observed with all 3 compounds, although a greater effect was found in the retinoic acid and peptide treatment groups. A similar trend was noted with respect to widening of the collagen layer. Epidermal surface roughness manifested maximum smoothing after treatment with the peptide compound.

CONCLUSION

The pronounced effects noted with all 3 compounds indicate that topical agents other than retinoic acid may have comparative stimulating effects on the skin in nonirradiated mice.

Facial aesthetics: Achieving the natural, relaxed look

When patients undergoing nonsurgical facial rejuvenation procedures are asked to state their expectations in terms of outcomes, the achievement of a "natural, relaxed look" usually emerges as the paramount goal. The importance to clinicians of delivering on this patient desire is becoming increasingly clear. After all, patient satisfaction is the ultimate treatment goal. This article explores aspects of what defines the natural, relaxed look and what patients are seeking when they undergo nonsurgical facial rejuvenation procedures and is based on the clinical experience of the authors. The article also offers suggestions intended to help clinicians provide each patient with appropriate outcomes and satisfaction.

LED photoprevention: reduced MED response following multiple LED exposures

BACKGROUND AND OBJECTIVES

As photoprotection with traditional sunscreen presents some limitations, the use of non-traditional treatments to increase skin resistance to ultraviolet (UV) induced damage would prove particularly appealing. The purpose of this pilot study was to test the potential of non-thermal pulsed light-emitting diode (LED) treatments (660 nm) prior to UV exposure in the induction of a state of cellular resistance against UV-induced erythema.

STUDY DESIGN/MATERIALS AND METHODS

Thirteen healthy subjects and two patients with polymorphous light eruption (PLE) were exposed to 5, 6, or 10 LED treatments (660 nm) on an EXPERIMENTAL anterior thigh region. Individual baseline minimal erythema doses (MED) were then determined. UV radiation was thereafter performed on the LED EXPERIMENTAL and CONTROL anterior thigh areas. Finally, 24 hours post-UV irradiation, LED pre-treated MED responses were compared to the non-treated sites.

RESULTS

Reduction of erythema was considered significant when erythema was reduced by >50% on the LED-treated side as opposed to CONTROL side. A significant LED treatment reduction in UV-B induced erythema reaction was observed in at least one occasion in 85% of subjects, including patients suffering from PLE. Moreover, there was evidence of a dose-related pattern in results. Finally, a sun protection factor SPF-15-like effect and a reduction in post-inflammatory hyperpigmentation were observed on the LED pre-treated side.

CONCLUSIONS

Results suggest that LED based therapy prior to UV exposure provided significant protection against UV-B induced erythema. The induction of cellular resistance to UV insults may possibly be explained by the induction of a state a natural resistance to the skin via specific cell signaling pathways and without the drawbacks and limitations of traditional sunscreens. These results represent an encouraging step towards expanding the potential applications of LED therapy and could be useful in the treatment of patients with anomalous reactions to sunlight.

Randomised, placebo-controlled, double-blind, split-face study on the clinical efficacy of Tricutan on skin firmness

Tricutan is a combination product of herbal extracts traditionally used for treatment of skin conditions, together with dimethylaminoethanol. The effectiveness of Tricutan in improving skin firmness and elasticity in photoaged facial skin was examined in a randomised, placebo-controlled, double-blind, split-face study in 28 women, 34-67 years old. Treatment with Tricutan and placebo was given for 4 weeks. Skin firmness and elasticity was evaluated using the speed of propagation of ultrasound shear waves in the skin as end point (Reviscometer RVM 600). The study was completed by 25 women. The Tricutan treatment resulted in a significantly reduced propagation speed indicating increased firmness. There was no immediate effect by Tricutan application on propagation speed. At self evaluation the women evaluated the treatment effect of Tricutan to be significantly better than the treatment effect of placebo. The clinical evaluation also showed Tricutan to give a significantly better treatment result than placebo. Tolerance to Tricutan was generally good. However, three women did not complete the study because of mild irritative contact dermatitis. The results show that Tricutan can increase skin firmness both objectively and subjectively. Further studies are warranted, especially to investigate if Tricutan can delay the need for surgical face-lift procedures.

Retinoid therapy of pigmentary disorders

Topical retinoids such as all-trans-retinoic acid (RA), 13-cis-retinoic acid (isotretinoin), retinol, retinaldehyde, tazarotene, and adapalene have been shown to improve dyspigmentation of photodamaged skin including mottling and actinic lentigines. RA monotherapy has also been demonstrated to improve melasma and postinflammatory hypermelanosis. Furthermore, RA in combination with hydroquinone or 4-hydroxyanisole, or azelaic acid increases the potency of depigmenting agents for the treatment of melasma, actinic lentigines, and postinflammatory hypermelanosis. The basic mechanisms underlying these effects are not completely identified. Topical retinoids stimulate the cell turn-over of epidermal keratinocytes and promote a decrease in melanosome transfer and a rapid loss of melanins via epidermopoiesis. Topical retinoids are also involved in the control of cell differentiation. Retinoid-induced changes in the stratum corneum and the permeability barrier may also facilitate the penetration of depigmenting agents in the epidermis and increase their bioavailability, leading to increased depigmentation. In addition, several in vitro studies demonstrate that cis and trans-retinoic acid inhibit UV-B stimulated melanogenesis in term of tyrosinase activity and melanin synthesis. It is likely that topical retinoids modulate epidermal melanin count via a direct action on melanocytes and epidermal keratinocytes.

Characterization of antioxidants using a fluidic chip in aqueous/organic media

Application of antioxidants in the cosmetic industry demands control of the efficiency of ROS-scavenging within the cream matrix. Our goal was to construct a system for the simultaneous detection of superoxide and hydrogen peroxide and their possible scavengers. DMSO is a good solvent for many cosmetic products, and thus the system should work in mixed aqueous-organic media. The fluidic chip developed consists of an ROS-generation chamber, a mixing section and a compartment for the biosensor chip. This electrode chip had two sensors: one sensor for each species. Cytochrome c was used as the sensing protein. Both the superoxide and the hydrogen peroxide sensors demonstrated sufficient sensitivity in DMSO-buffer mixtures within the concentration range 0.4 nM-1.2 nM (superoxide) and 50 microM-1000 microM (hydrogen peroxide). The influence of the flow conditions on the generation of ROS was investigated and the optimal parameters for the antioxidant detection were evaluated. The efficiency of ROS-scavenging was tested with typical antioxidants of enzymatic and non-enzymatic origin, as well as complex cosmetic creams.

Imiquimod as an antiaging agent

BACKGROUND

Topical imiquimod therapy has proven to be effective for a variety of infectious, neoplastic, and inflammatory dermatologic diseases. Several published reports have validated the benefit of imiquimod therapy for actinic keratoses and superficial melanoma and nonmelanoma skin cancers. There is, however, limited evidence demonstrating the use of topical imiquimod application as an antiaging treatment.

OBJECTIVES

We examined the effectiveness of imiquimod 5% cream in the treatment of photoaging by evaluating pretreatment and posttreatment biopsy specimens and documenting the histologic changes.

METHODS

This study represents an extension of an earlier project in our department in which patients with biopsy-proven lesions of lentigo maligna (LM) were recruited from a university dermatology service, a hospital, and referrals from private practitioners for an open-labeled efficacy trial with daily topical application of 5% imiquimod for 3 months. Biopsy of clinically affected skin was carried out on all patients before and after treatment. Using a semiquantitative method, biopsy specimens were analyzed for changes in the dermal collagen table (solar elastosis vs papillary dermal fibroplasia). Additional parameters analyzed included epidermal changes (atrophy vs acanthosis, melanin content, and hypergranulosis) and inflammatory effects (epidermal and dermal cell populations along with presence of pigment incontinence). Variables were compared using paired Wilcoxan rank sums.

RESULTS

Of 26 evaluable patients who completed 3 months of daily application, 24 (>92.3%) showed a significant increase in papillary dermal fibroplasia (P < .0001) with associated reduction in solar elastosis (P = .0036). Other noteworthy findings were restoration of normal epidermal thickness (P = .0073) and melanization (P < .0001).

LIMITATIONS

This study only evaluates the effect of imiquimod in the lesional skin of LM. It is not known whether the results are applicable to nonlesional, photoaged skin.

CONCLUSION

Topical imiquimod appears to induce reparative changes to the epidermis and the dermal collagen table in chronically sun-damaged skin associated with LM, indicating its potential use as an antiaging treatment. These findings need to be confirmed in photodamaged skin not associated with LM.

Retinoids in cosmeceuticals

Retinoids are natural and synthetic vitamin A derivatives. They are lipophilic molecules and easily penetrate the epidermis. Their biologically active forms can modulate the expression of genes involved in cellular differentiation and proliferation. Retinoic acid (tretinoin), its 13-cis isomer isotretinoin, as well as various synthetic retinoids are used for therapeutic purposes, whereas retinaldehyde, retinol, and retinyl esters, because of their controlled conversion to retinoic acid or their direct receptor-independent biologic action, can be used as cosmeceuticals. These natural retinoic acid precursors are thus expected to be helpful in (i) renewing epidermal cells, (ii) acting as UV filters, (iii) preventing oxidative stress, (iv) controlling cutaneous bacterial flora, and (v) improving skin aging and photoaging. Retinol and retinyl esters are not irritant, whereas demonstrating only a modest clinical efficiency. On the other hand, retinaldehyde, which is fairly well tolerated, seems to be the most efficient cosmeceutical retinoid; it has significant efficiency toward oxidative stress, cutaneous bacterial flora, epidermis renewing, and photoaging.

Topical ER36009, a RARgamma-selective retinoid, decreases abdominal white adipose tissue and elicits changes in expression of genes related to adiposity and thermogenesis

Chronic topical treatment of rats with a new RARgamma-selective retinoid, ER36009, resulted in a significant reduction of epididymal white adipose tissue and a significant increase of interscapular brown adipose tissue without affecting food intake. ER36009 markedly decreased PPARgamma, 11beta-HSD1, and Bcl-2 mRNA levels, and increased Bax mRNA in white adipose tissue, while it upregulated UCP1 and UCP3 mRNAs in brown adipose tissue and UCP3 mRNA in gastrocnemial muscle. These results suggest that ER36009 has multiple effects on adipose tissue biology and the energy balance. Topically applied ER36009 may have potential for the treatment of obesity.

Prevention and treatment of skin aging

Skin aging is a complex biological process that is a consequence of both intrinsic or genetically programmed aging that occurs with time, and extrinsic aging caused by environmental factors. The dramatic increase in the aging population and the psychosocial impact of skin aging has created a demand for effective interventions. The advances that have been made in the past 25 years in our understanding of the clinical, biochemical, and molecular changes associated with aging have led to the development of many different approaches to reduce, postpone, and in some cases, repair the untoward effects of intrinsic programmed aging and extrinsic environmental injury.

All-trans retinoic acid antagonizes UV-induced VEGF production and angiogenesis via the inhibition of ERK activation in human skin keratinocytes

Incident UV radiation leads to the upregulation of vascular endothelial growth factor (VEGF), a potent angiogenic factor, in human skin. However, the molecular basis of UV-induced angiogenesis in skin remains to be elucidated. In this study, we investigated the roles of UV exposure on cutaneous angiogenesis, its associated signaling mechanisms, and the effect of all-trans retinoic acid (tRA) on UV-induced vascularization, and VEGF expression. Using a human epidermal cell line, HaCaT, we found that UV induces VEGF mRNA and protein expression via the MAPK/ERK kinase-ERK1/2 (extracellular signal-regulated kinase 1/2) pathway but not via the phosphatidylinositol 3-kinase (PI3K)/Akt pathway, and that tRA pretreatment significantly inhibits UV-induced VEGF overexpression and ERK1/2 activation. In human skin in vivo, we confirmed that skin vascularization significantly increased after a single exposure to UV, as was evidenced by a prominent increase in vessel size, vascular density, and in the cutaneous area occupied by vessels, and we found that these events are associated with VEGF upregulation. Topical pretreatment with tRA under occlusion inhibited not only UV-induced VEGF upregulation and angiogenesis with a significant reduction of vessel density but also UV-induced ERK1/2 activation in human skin. Collectively, our data demonstrate that tRA inhibits the UV-induced angiogenic switch via downmodulation of ERK1/2 activation and consecutive VEGF overexpression. These findings may help us understand the molecular mechanisms that regulate skin angiogenesis due to UV exposure, and provide evidence of the potential of tRA in terms of preventing angiogenesis-associated skin damage following exposure to UV irradiation.