Comparative study of melasma in patients before and after treatment based on lipomics.

BACKGROUND: Skin barrier alterations play a crucial function in melasma development. Past researches have demonstrated variations in lipid content between the epidermis of melasma lesions and normal tissues, along with the varied expression of lipid-related genes in melasma. This study aimed to analyze the lipidome profiles of skin surface lipids (SSL) in patients with melasma before and after treatment to understand associated abnormalities. METHODS: Melasma was treated with tranexamic acid orally and hydroquinone cream topically. Disease was assessed using the Melasma Area and Severity Index (MASI), and the impact to life was evaluated with Melasma Quality of Life (MELASQoL) score. Epidermal melanin particles were observed using reflection confocal microscopy (RCM), whereas epidermal pigment and blood vessel morphology were observed using dermoscopy, and SSL samples were collected. Specific information regarding alterations in lipid composition was obtained through multivariate analysis of the liquid chromatography-mass spectrometry data. RESULTS: After treatment, patients with melasma exhibited decreased MASI and MELASQoL scores (P < 0.001); RCM revealed reduced melanin content in the lesions, and dermoscopy revealed fewer blood vessels. Fifteen lipid subclasses and 382 lipid molecules were identified using lipidomic assays. The expression levels of total lipids, phosphatidylcholine, and phosphatidylethanolamine in the melasma lesions decreased after treatment (P < 0.05). CONCLUSION: This study revealed alterations in the SSL composition after effective melasma treatment, suggesting a compensatory role for lipids in melasma barrier function. The mechanism involving SSL and the lipid barrier, which influences melasma's occurrence, needs further elucidation.

(S)-(-)-blebbistatin O-benzoate has the potential to improve atopic dermatitis symptoms in NC/Nga mice by upregulating epidermal barrier function and inhibiting type 2 alarmin cytokine induction.

Atopic dermatitis is a multi-pathogenic disease characterized by chronic skin inflammation and barrier dysfunction. Therefore, improving the skin's ability to form an epidermal barrier and suppressing the production of cytokines that induce type 2 inflammatory responses are important for controlling atopic dermatitis symptoms. (-)-Blebbistatin, a non-muscle myosin II inhibitor, has been suggested to improve pulmonary endothelial barrier function and control inflammation by suppressing immune cell migration; however, its efficacy in atopic dermatitis is unknown. In this study, we investigated whether (S)-(-)-blebbistatin O-benzoate, a derivative of (-)-blebbistatin, improves dermatitis symptoms in a mite antigen-induced atopic dermatitis model using NC/Nga mice. The efficacy of the compound was confirmed using dermatitis scores, ear thickness measurements, serum IgE levels, histological analysis of lesions, and filaggrin expression analysis, which is important for barrier function. (S)-(-)-Blebbistatin O-benzoate treatment significantly reduced the dermatitis score and serum IgE levels compared to those in the vehicle group (p < 0.05). Furthermore, the histological analysis revealed enhanced filaggrin production and a decreased number of mast cells (p < 0.05), indicating that (S)-(-)-blebbistatin O-benzoate improved atopic dermatitis symptoms in a pathological model. In vitro analysis using cultured keratinocytes revealed increased expression of filaggrin, loricrin, involucrin, and ceramide production pathway-related genes, suggesting that (S)-(-)-blebbistatin O-benzoate promotes epidermal barrier formation. Furthermore, the effect of (S)-(-)-blebbistatin O-benzoate on type 2 alarmin cytokines, which are secreted from epidermal cells upon scratching or allergen stimulation and are involved in the pathogenesis of atopic dermatitis, was evaluated using antigens derived from mite feces. The results showed that (S)-(-)-blebbistatin O-benzoate inhibited the upregulation of these cytokines. Based on the above, (S)-(-)-blebbistatin O-benzoate has the potential to be developed as an atopic dermatitis treatment option that controls dermatitis symptoms by suppressing inflammation and improving barrier function by acting on multiple aspects of the pathogenesis of atopic dermatitis.

Unraveling the Mechanisms Involved in the Beneficial Effects of Magnesium Treatment on Skin Wound Healing.

The skin wound healing process consists of hemostatic, inflammatory, proliferative, and maturation phases, with a complex cellular response by multiple cell types in the epidermis, dermis, and immune system. Magnesium is a mineral essential for life, and although magnesium treatment promotes cutaneous wound healing, the molecular mechanism and timing of action of the healing process are unknown. This study, using human epidermal-derived HaCaT cells and human normal epidermal keratinocyte cells, was performed to investigate the mechanism involved in the effect of magnesium on wound healing. The expression levels of epidermal differentiation-promoting factors were reduced by MgCl2, suggesting an inhibitory effect on epidermal differentiation in the remodeling stage of the late wound healing process. On the other hand, MgCl2 treatment increased the expression of matrix metalloproteinase-7 (MMP7), a cell migration-promoting factor, and enhanced cell migration via the MEK/ERK pathway activation. The enhancement of cell migration by MgCl2 was inhibited by MMP7 knockdown, suggesting that MgCl2 enhances cell migration which is mediated by increased MMP7 expression. Our results revealed that MgCl2 inhibits epidermal differentiation but promotes cell migration, suggesting that applying magnesium to the early wound healing process could be beneficial.

JAK/STAT Inhibition Normalizes Lipid Composition in 3D Human Epidermal Equivalents Challenged with Th2 Cytokines.

Derangement of the epidermal barrier lipids and dysregulated immune responses are key pathogenic features of atopic dermatitis (AD). The Th2-type cytokines interleukin IL-4 and IL-13 play a prominent role in AD by activating the Janus Kinase/Signal Transduction and Activator of Transcription (JAK/STAT) intracellular signaling axis. This study aimed to investigate the role of JAK/STAT in the lipid perturbations induced by Th2 signaling in 3D epidermal equivalents. Tofacitinib, a low-molecular-mass JAK inhibitor, was used to screen for JAK/STAT-mediated deregulation of lipid metabolism. Th2 cytokines decreased the expression of elongases 1, 3, and 4 and serine-palmitoyl-transferase and increased that of sphingolipid delta(4)-desaturase and carbonic anhydrase 2. Th2 cytokines inhibited the synthesis of palmitoleic acid and caused depletion of triglycerides, in association with altered phosphatidylcholine profiles and fatty acid (FA) metabolism. Overall, the ceramide profiles were minimally affected. Except for most sphingolipids and very-long-chain FAs, the effects of Th2 on lipid pathways were reversed by co-treatment with tofacitinib. An increase in the mRNA levels of CPT1A and ACAT1, reduced by tofacitinib, suggests that Th2 cytokines promote FA beta-oxidation. In conclusion, pharmacological inhibition of JAK/STAT activation prevents the lipid disruption caused by the halted homeostasis of FA metabolism.

Comparative Analysis of Olive-Derived Phenolic Compounds' Pro-Melanogenesis Effects on B16F10 Cells and Epidermal Human Melanocytes.

Olive leaf contains plenty of phenolic compounds, among which oleuropein (OP) is the main component and belongs to the group of secoiridoids. Additionally, phenolic compounds such as oleocanthal (OL) and oleacein (OC), which share a structural similarity with OP and two aldehyde groups, are also present in olive leaves. These compounds have been studied for several health benefits, such as anti-cancer and antioxidant effects. However, their impact on the skin remains unknown. Therefore, this study aims to compare the effects of these three compounds on melanogenesis using B16F10 cells and human epidermal cells. Thousands of gene expressions were measured by global gene expression profiling with B16F10 cells. We found that glutaraldehyde compounds derived from olive leaves have a potential effect on the activation of the melanogenesis pathway and inducing differentiation in B16F10 cells. Accordingly, the pro-melanogenesis effect was investigated by means of melanin quantification, mRNA, and protein expression using human epidermal melanocytes (HEM). This study suggests that secoiridoid and its derivates have an impact on skin protection by promoting melanin production in both human and mouse cell lines.

KoCVAM-led development of phototoxicity alternative test method using reconstructed human epidermis model (KeraSkin™).

Phototoxicity is an acute toxic reaction induced by topical skin exposure to photoreactive chemicals followed by exposure to environmental light and thus chemicals that absorb UV are recommended to be evaluated for phototoxic potential. There are currently three internationally harmonized alternative test methods for phototoxicity. One of them is the in vitro Phototoxicity: RhE Phototoxicity test method (OECD TG498). Korean center for the Validation of Alternative Methods (KoCVAM) developed an in vitro phototoxicity test method using a KeraSkin™ reconstructed human epidermis model (KeraSkin™ Phototoxicity Assay) as a 'me-too' test method of OECD TG498. For the development and optimization of KeraSkin™ Phototoxicity Assay, the following test chemicals were used: 6 proficiency chemicals in OECD TG498 (3 phototoxic and 3 non-phototoxic), 6 reference chemicals in OECD Performance Standard No. 356 (excluding the proficiency test chemicals, 3 phototoxic and 3 non-phototoxic) and 13 additional chemicals (7 phototoxic and 6 non-phototoxic). Based on the test results generated from the test chemicals above, the overall predictive capacity of KeraSkin™ Phototoxicity Assay was calculated. In particular, the assay exhibited 100 % accuracy, 100 % sensitivity, and 100 % specificity. Therefore, it fulfills the requirements to be included as a 'me-too' test method in OECD TG498.

The water extracts from the oil cakes of Prinsepia utilis repair the epidermal barrier via up-regulating Corneocyte Envelope-proteins, lipid synthases, and tight junction proteins.

ETHNOPHARMACOLOGICAL RELEVANCE: Prinsepia utilis Royle, native to the Himalayan region, has a long history of use in traditional medicine for its heat-clearing, detoxification, anti-inflammatory, and analgesic properties. Oils extracted from P. utilis seeds are also used in cooking and cosmetics. With the increasing market demand, this extraction process generates substantial industrial biowastes. Recent studies have found many health benefits with using aqueous extracts of these biowastes, which are also rich in polysaccharides. However, there is limited research related to the reparative effects of the water extracts of P. utilis oil cakes (WEPUOC) on disruptions of the skin barrier function. AIM OF THE STUDY: This study aimed to evaluate the reparative efficacy of WEPUOC in both acute and chronic epidermal permeability barrier disruptions. Furthermore, the study sought to explore the underlying mechanisms involved in repairing the epidermal permeability barrier. MATERIALS AND METHODS: Mouse models with induced epidermal disruptions, employing tape-stripping (TS) and acetone wiping (AC) methods, were used. The subsequent application of WEPUOC (100 mg/mL) was evaluated through various assessments, with a focus on the upregulation of mRNA and protein expression of Corneocyte Envelope (CE) related proteins, lipid synthase-associated proteins, and tight junction proteins. RESULTS: The polysaccharide was the major phytochemicals of WEPUOC and its content was determined as 32.2% by the anthranone-sulfuric acid colorimetric method. WEPUOC significantly reduced transepidermal water loss (TEWL) and improved the damaged epidermal barrier in the model group. Mechanistically, these effects were associated with heightened expression levels of key proteins such as FLG (filaggrin), INV (involucrin), LOR (loricrin), SPT, FASN, HMGCR, Claudins-1, Claudins-5, and ZO-1. CONCLUSIONS: WEPUOC, obtained from the oil cakes of P. utilis, is rich in polysaccharides and exhibits pronounced efficacy in repairing disrupted epidermal barriers through increased expression of critical proteins involved in barrier integrity. Our findings underscore the potential of P. utilis wastes in developing natural cosmetic prototypes for the treatment of diseases characterized by damaged skin barriers, including atopic dermatitis and psoriasis.

Vitamin A resolves lineage plasticity to orchestrate stem cell lineage choices.

Lineage plasticity-a state of dual fate expression-is required to release stem cells from their niche constraints and redirect them to tissue compartments where they are most needed. In this work, we found that without resolving lineage plasticity, skin stem cells cannot effectively generate each lineage in vitro nor regrow hair and repair wounded epidermis in vivo. A small-molecule screen unearthed retinoic acid as a critical regulator. Combining high-throughput approaches, cell culture, and in vivo mouse genetics, we dissected its roles in tissue regeneration. We found that retinoic acid is made locally in hair follicle stem cell niches, where its levels determine identity and usage. Our findings have therapeutic implications for hair growth as well as chronic wounds and cancers, where lineage plasticity is unresolved.

Influence of cosmetic foundation cream on skin condition during treadmill exercise.

BACKGROUND: There is a growing trend of individuals wearing cosmetics while participating in physical activities. Nonetheless, there remains a need for further understanding regarding the effects of makeup on the facial epidermis during exercise, given the existing knowledge gaps. PURPOSE: This study aimed to evaluate the effects of a cosmetic foundation cream on skin conditions during physical activity. METHODS: Forty-three healthy college students, 20 males (26.3 ± 1.5 years) and 23 females (23.1 ± 1.0 years), were enrolled in this study. Foundation cream was applied to participants on half of the face in two different areas (MT: makeup T zone and MU: makeup U zone). The other half of the face served as internal control (T: non-makeup T zone and U: non-makeup U zones). Skin levels of moisture, elasticity, pore, sebum, and oil were measured using a skin analysis device (Aramhuvis, Gyeonggi, Republic of Korea) before and after a 20-min treadmill exercise. Paired t-test and independent t-test were performed for skin condition measurements at pre- and postexercise. RESULTS: The skin moisture levels in both the T and MT significantly increased after exercise (p < 0.05) (pre-T: 24.5 ± 1.3, post-T: 38.5 ± 3.5 and pre-MT: 18.7 ± 0.7, post-MT: 40.4 ± 4.8). Elasticity also significantly improved in both the T and MT (p < 0.05) (pre-T: 25.6 ± 1.3, post-T: 41.5 ± 3.5 and pre-MT: 20.0 ± 0.9, post-MT: 41.7 ± 3.7). The size of the pores in the T zone observed a significant increase after exercise (p < 0.05) (pre-T: 41.7 ± 2.1, post-T: 47.8 ± 2.4). The sebum levels in the T zone exhibited a reduction following physical activity, whereas there was a notable increase in sebum levels in the makeup zones (p < 0.05) (pre-MT: 2.4 ± 0.7, post-MT:4.2 ± 0.8 and pre MU 1.8 ± 0.34, post MU 4.9 ± 0.9). The oil level was increased in the non-makeup zones (pre-T: 6.1 ± 1.4, post-T: 11.8 ± 2.0 and pre-U: 7.3 ± 1.5, post-U: 11.9 ± 1.9; p < 0.05) and decreased in the makeup zones (pre-MT: 13.3 ± 1.9, post-MT: 7.4 ± 2.3 and pre-MU: 22.1 ± 2.4, post-MU: 3.2 ± 1.0; p < 0.05). CONCLUSIONS: The findings suggest that using foundation cream during aerobic exercise can reduce skin oil, causing dryness. Additionally, makeup can clog pores and increase sebum production. Therefore, wearing makeup may not be recommended for people with dry skin conditions based on the results of the current study. This research offers important insights to the public, encouraging them to consider the possible consequences of using makeup while exercising.

Calcitriol modulates epidermal tight junction barrier function in human keratinocytes.

BACKGROUND: The aberrant expression of tight junction (TJ) proteins play an important role in several diseases with impaired skin barriers, including atopic dermatitis, psoriasis, and chronic wounds. The evidence provided thus far suggests an important role of calcitriol in skin homeostasis. However, it is not known whether calcitriol improves the impaired skin barrier. OBJECTIVE: To investigate the effect of calcitriol on TJ barrier function in human primary keratinocytes. METHODS: Normal human primary keratinocytes were stimulated with calcitriol, and the expression of TJ-related proteins was measured by real-time PCR and Western blotting. Immunofluorescence was used to examine the intercellular distribution of TJ-related proteins. TJ barrier function was assessed by the transepithelial electrical resistance (TER) assay. RESULTS: We demonstrated that calcitriol increased the expression levels of TJ-related proteins, including claudin-4, claudin-7, occludin, and zonula occludens (ZO)- 1. Calcitriol enhanced the distribution of TJ-related proteins at cellcell borders and induced the phosphorylation of pathways involved in the regulation of TJ barrier function, such as atypical protein kinase C (aPKC), Ras-related C3 botulinum toxin substrate 1 (Rac1), phosphoinositide 3-kinase (PI3K), and protein kinase B (Akt), as evidenced by the effects of specific inhibitors on the above pathways. Indeed, we confirmed that calcitriol enhanced TER in keratinocyte monolayers. CONCLUSION: These findings showed that calcitriol could modify the expression of keratinocyte TJ proteins, contributing to the maintenance of homeostatic barrier function.

Development of a novel human stratum corneum mimetic phospholipid -vesicle-based permeation assay models for in vitro permeation studies.

OBJECTIVES: To develop and evaluate a novel human stratum corneum (SC) mimetic phospholipid vesicle-based permeation assay (PVPASC) model for in vitro permeation studies. SIGNIFICANCE: Due to the increasing restrictions on the use of human and animal skins, artificial skin models have attracted substantial interest in pharmaceuticals and cosmetic industries. In this study, a modified PVPASC model containing both SC lipids and proteins was developed. METHODS: The PVPASC model was optimized by altering the lipid composition and adding keratin in the formulation of large liposomes. The barrier properties were monitored by measuring the electrical resistance (ER) and permeability of Rhodamine B (RB). The modified PVPASC model was characterized in terms of the surface topography, solvent influence and storage stability. The permeation studies of the active components in Compound Nanxing Zhitong Plaster (CNZP) were performed to examine the capability of PVPASC in the application of skin penetration. RESULTS: The ER and Papp values of RB obtained from the optimized PVPASC model indicated a similar barrier property to porcine ear skin. Scanning electron microscope analysis demonstrated a mimic 'brick-and-mortar' structure. The PVPASC model can be stored for three weeks at -20 °C, and withstand the presence of different receptor medium for 24 h. The permeation studies of the active components demonstrated a good correlation (r2 = 0.9136) of Papp values between the drugs' permeation through the PVPASC model and porcine ear skin. CONCLUSION: Keratin contained composite phospholipid vesicle-based permeation assay models have been proven to be potential skin tools in topical/transdermal permeation studies.

Efficacy and tolerability of a depigmenting gel serum comprising tranexamic acid, niacinamide, 4-butylresorcinol, phytic acid, and a mixture of hydroxy acids that targets the biological processes regulating skin melanogenesis.

BACKGROUND: The diverse causes of hyperpigmentation and complex nature of melanogenesis make it a challenge to manage. Current approaches either fail to deliver effective pigmentation control or have undesirable safety profiles that preclude their long-term use. AIMS: To evaluate the capacity of a cosmetic gel serum comprising tranexamic acid, niacinamide, 4-butylresorcinol, phytic acid, and a mixture of hydroxy acids that was designed to target the biological processes regulating skin melanogenesis to attenuate melanin production in vitro and reduce hyperpigmentation clinically. METHODS: Capacity to reduce melanin production in vitro was determined in melanocyte-containing reconstructed human epidermis (RHEm). Clinical efficacy and skin tolerability following twice daily application were assessed in 35 subjects with slight to moderate facial hyperpigmentation by instrumental (VISIA®-CR, Mexameter®) and clinical (mMASI, clinical score, IGA for hyperpigmentation) evaluation on D14, D28, D56, and D84. Maintenance of pigmentation control was followed up 1 month after cessation of treatment on D112. RESULTS: In RHEm in vitro, melanin production was reduced by 50.0% from baseline (D0) on D14 (p < 0.001) and by 67.0% on D21 (p < 0.001). Clinical reductions from baseline in brown spots count (-9.0%; p < 0.05), brown spots area (-16.7%; p < 0.001), and the melanin index (-11.4%; p < 0.001) were observed within 14 days of use. Statistically significant improvements in all clinical parameters were achieved by D28. By the end of treatment on D84, the number and surface area of brown spots were reduced by 28.4% and 40.3% compared to D0, respectively (p < 0.001, both), the melanin index was reduced by 31.1% (p < 0.001), mMASI was reduced by 63.0% (p < 0.001), and skin luminosity was increased by 79.0% (p < 0.001). IGA was reduced from 2.3 on D0 to 1.3 on D84 (p < 0.001). Improvements to all these parameters were maintained until D112, 1 month after termination of treatment. The product also demonstrated very good skin tolerability. CONCLUSION: A gel serum comprising tranexamic acid, niacinamide, 4-butylresorcinol, and hydroxy acids, designed to target the biological processes regulating skin melanogenesis, demonstrates rapid, robust, and sustained pigmentation control in this cohort.

Arc-poration improves transdermal delivery of biomolecules.

BACKGROUND: To increase skin permeability, various transdermal delivery techniques have been developed. However, due to the stratum corneum as a skin barrier, transdermal delivery remains limited. AIMS: In this study, we evaluated efficacy and safety of arc-poration as a novel technique disrupting the stratum corneum. RESULTS: Optical images and histological analysis using reconstituted human skin and porcine skin showed that the treatment of arc-poration created micropores with an average diameter of approximately 100 µm only to the depth of the stratum corneum, but not viable epidermis. In addition, the Franz diffusion cell experiment using reconstituted human skin showed a remarkable increase in permeability following pretreatment with arc-poration. Clinical results clearly demonstrated the enhancement of the skin-improving effect of cosmetics by pretreatment of arc-poration in terms of gloss, hydration, flakiness, texture, tone, tone evenness, and pigmentation of skin, without causing abnormal skin responses. The concentration of ozone and nitrogen oxides generated by arc-poration was below the permissible value for the human body. CONCLUSIONS: Arc-poration can increase skin permeability by creating stratum corneum-specific micropores, which can enhance the skin-improving effect of cosmetics without adverse responses.

Oat ß-glucan repairs the epidermal barrier by upregulating the levels of epidermal differentiation, cell-cell junctions and lipids via Dectin-1.

BACKGROUND AND PURPOSE: Oat ß-glucan could ameliorate epidermal hyperplasia and accelerate epidermal barrier repair. Dectin-1 is one of the receptors of ß-glucan and many biological functions of ß-glucan are mediated by Dectin-1. Dectin-1 promotes wound healing through regulating the proliferation and migration of skin cells. Thus, this study aimed to investigate the role of oat ß-glucan and Dectin-1 in epidermal barrier repair. EXPERIMENTAL APPROACH: To investigate the role of Dectin-1 in the epidermal barrier, indicators associated with the recovery of a damaged epidermal barrier, including histopathological changes, keratinization, proliferation, apoptosis, differentiation, cell-cell junctions and lipid content were compared between WT and Dectin-1-/- mice. Further, the effect of oat ß-glucan on the disruption of the epidermal barrier was also compared between WT and Dectin-1-/- mice. KEY RESULTS: Dectin-1 deficiency resulted in delayed recovery and marked keratinization, as well as abnormal levels of keratinocyte differentiation, cell-cell junctions and lipid synthesis during the restoration of the epidermal barrier. Oat ß-glucan significantly reduces epidermal hyperplasia, promotes epidermal differentiation, increases cell-cell junction expression, promotes lipid synthesis and ultimately accelerates the recovery of damaged epidermal barriers via Dectin-1. Oat ß-glucan could promote CaS receptor expression and activate the PPAR-γ signalling pathway via Dectin-1. CONCLUSION AND IMPLICATIONS: Oat ß-glucan promote the recovery of damaged epidermal barriers through promoting epidermal differentiation, increasing the expression of cell-cell junctions and lipid synthesis through Dectin-1. Dectin-1 deficiency delay the recovery of epidermal barriers, which indicated that Dectin-1 may be a potential target in epidermal barrier repair.

Neurog1-Derived Peptides RMNE1 and DualPep-Shine Penetrate the Skin and Inhibit Melanin Synthesis by Regulating MITF Transcription.

Anti-pigmentation peptides have been developed as alternative skin-lightening agents to replace conventional chemicals that have adverse effects on the skin. However, the maximum size of these peptides is often limited by their low skin and cell penetration. To address this issue, we used our intra-dermal delivery technology (IDDT) platform to identify peptides with hypo-pigmenting and high cell-penetrating activity. Using our cell-penetrating peptides (CPPs) from the IDDT platform, we identified RMNE1 and its derivative RMNE3, "DualPep-Shine", which showed levels of α-Melanocyte stimulating hormone (α-MSH)-induced melanin inhibition comparable to the conventional tyrosinase inhibitor, Kojic acid. In addition, DualPep-Shine was delivered into the nucleus and regulated the gene expression levels of melanogenic enzymes by inhibiting the promoter activity of microphthalmia-associated transcription factor-M (MITF-M). Using a 3D human skin model, we found that DualPep-Shine penetrated the lower region of the epidermis and reduced the melanin content in a dose-dependent manner. Furthermore, DualPep-Shine showed high safety with little immunogenicity, indicating its potential as a novel cosmeceutical ingredient and anti-pigmentation therapeutic agent.

Cannabidiol mediates epidermal terminal differentiation and redox homeostasis through aryl hydrocarbon receptor (AhR)-dependent signaling.

BACKGROUND: Cannabidiol, a non-psychoactive phytocannabinoid, has antioxidant and anti-inflammatory activity in keratinocytes. However, the signaling pathway through which cannabidiol exerts its effect on keratinocytes or whether it can modulate keratinocyte differentiation has not been fully elucidated yet. OBJECTIVE: We investigated whether cannabidiol modulates epidermal differentiation and scavenges reactive oxygen species through the aryl hydrocarbon receptor (AhR) in keratinocytes and epidermal equivalents. METHODS: We investigated the cannabidiol-induced activation of AhR using AhR luciferase reporter assay, qRT-PCR, western blot, and immunofluorescence assays. We also analyzed whether keratinocyte differentiation and antioxidant activity are regulated by cannabidiol-induced AhR activation. RESULTS: In both keratinocytes and epidermal equivalents, cannabidiol increased both the mRNA and protein expression of filaggrin, involucrin, NRF2, and NQO1 and the mRNA expression of the AhR target genes, including CYP1A1 and aryl hydrocarbon receptor repressor. Additionally, cannabidiol showed antioxidant activity that was attenuated by AhR knockdown or co-administration with an AhR antagonist. Moreover, cannabidiol increased the ratio of OVOL1/OVOL2 mRNA expression, which is a downstream regulator of AhR that mediates epidermal differentiation. In addition to increased expression of barrier-related proteins, cannabidiol-treated epidermal equivalent showed a more prominent granular layer than the control epidermis. The increased granular layer by cannabidiol was suppressed by the AhR antagonist. CONCLUSION: Cannabidiol can be a modulator of the AhR-OVOL1-filaggrin axis and AhR-NRF2-NQO1 signaling, thus indicating a potential use of cannabidiol in skin barrier enhancement and reducing oxidative stress.

Application of mevalonolactone prevents deterioration of epidermal barrier function by accelerating the lamellar granule lipid transport system.

BACKGROUND: Fatty acids increase ATP-binding cassette ABC transporter A12 (ABCA12) levels via an increase in peroxisome proliferator-activated receptor ß/δ (PPAR ß/δ). Promoting lipid transport to lamellar granules has been suggested to improve epidermal barrier function in patients with dry skin. OBJECTIVE: We investigated whether mevalonolactone (MVL) produced by Saccharomycopsis fibuligera improves dry skin by promoting ABCA12 expression and the amount of free fatty acids in epidermal keratinocytes. METHODS: We examined whether MVL increases ABCA12 mRNA and protein levels and the amount of Nile red-positive lipids in cultured epidermal keratinocytes and in a three-dimensional epidermal model by cell staining. Promotion of fatty acid production by MVL was analyzed by liquid chromatography-mass spectrometry. We also evaluated whether MVL addition increases PPAR ß/δ mRNA expression in cultured keratinocytes. Based on the results, a randomized controlled trial was conducted in which milky lotions containing MVL and placebo were applied to dry facial skin of healthy female volunteers in winter. RESULTS: MVL increased ABCA12 mRNA and protein levels and lamellar granule number and size. Fatty acid analysis revealed that MVL elevated myristic acid, palmitic acid, and palmitoleic acid levels as well as PPAR ß/δ mRNA expression. In human tests, milky lotions containing MVL were shown to significantly improve transepidermal water loss (TEWL) in the stratum corneum compared to placebo. CONCLUSION: The results suggest that MVL increases fatty acid uptake and ABCA12, promotes fatty acid transport to lamellar granules, and improves epidermal barrier function in dry skin through increased expression of PPAR ß/δ.

A Connecting Link between Hyaluronan Synthase 3-Mediated Hyaluronan Production and Epidermal Function.

Hyaluronan (HA), an essential component of the extracellular matrix of the skin, is synthesized by HA synthases (HAS1-3). To date, epidermal HA has been considered a major player in regulating cell proliferation and differentiation. However, a previous study reported that depletion of epidermal HA by Streptomyces hyaluronidase (St-HAase) has no influence on epidermal structure and function. In the present study, to further explore roles of epidermal HA, we examined effects of siRNA-mediated knockdown of HAS3, as well as conventional HA-depletion methods using St-HAase and 4-methylumbelliferone (4MU), on epidermal turnover and architecture in reconstructed skin or epidermal equivalents. Consistent with previous findings, HA depletion by St-HAase did not have a substantial influence on the epidermal architecture and turnover in skin equivalents. 4MU treatment resulted in reduced keratinocyte proliferation and epidermal thinning but did not seem to substantially decrease the abundance of extracellular HA. In contrast, siRNA-mediated knockdown of HAS3 in epidermal equivalents resulted in a significant reduction in epidermal HA content and thickness, accompanied by decreased keratinocyte proliferation and differentiation. These results suggest that HAS3-mediated HA production, rather than extracellularly deposited HA, may play a role in keratinocyte proliferation and differentiation, at least in the developing epidermis in reconstructed epidermal equivalents.

In vivo melanin 3D quantification and z-epidermal distribution by multiphoton FLIM, phasor and Pseudo-FLIM analyses.

Characterizing melanins in situ and determining their 3D z-epidermal distribution is paramount for understanding physiological/pathological processes of melanin neosynthesis, transfer, degradation or modulation with external UV exposure or cosmetic/pharmaceutical products. Multiphoton fluorescence intensity- and lifetime-based approaches have been shown to afford melanin detection, but how can one quantify melanin in vivo in 3D from multiphoton fluorescence lifetime (FLIM) data, especially since FLIM imaging requires long image acquisition times not compatible with 3D imaging in a clinical setup? We propose an approach combining (i) multiphoton FLIM, (ii) fast image acquisition times, and (iii) a melanin detection method called Pseudo-FLIM, based on slope analysis of autofluorescence intensity decays from temporally binned data. We compare Pseudo-FLIM to FLIM bi-exponential and phasor analyses of synthetic melanin, melanocytes/keratinocytes coculture and in vivo human skin. Using parameters of global 3D epidermal melanin density and z-epidermal distribution profile, we provide first insights into the in vivo knowledge of 3D melanin modulations with constitutive pigmentation versus ethnicity, with seasonality over 1 year and with topical application of retinoic acid or retinol on human skin. Applications of Pseudo-FLIM based melanin detection encompass physiological, pathological, or environmental factors-induced pigmentation modulations up to whitening, anti-photoaging, or photoprotection products evaluation.

Paclitaxel-Induced Epidermal Alterations: An In Vitro Preclinical Assessment in Primary Keratinocytes and in a 3D Epidermis Model.

Paclitaxel is a microtubule-stabilizing chemotherapeutic agent approved for the treatment of ovarian, non-small cell lung, head, neck, and breast cancers. Despite its beneficial effects on cancer and widespread use, paclitaxel also damages healthy tissues, including the skin. However, the mechanisms that drive these skin adverse events are not clearly understood. In the present study, we demonstrated, by using both primary epidermal keratinocytes (NHEK) and a 3D epidermis model, that paclitaxel impairs different cellular processes: paclitaxel increased the release of IL-1α, IL-6, and IL-8 inflammatory cytokines, produced reactive oxygen species (ROS) release and apoptosis, and reduced the endothelial tube formation in the dermal microvascular endothelial cells (HDMEC). Some of the mechanisms driving these adverse skin events in vitro are mediated by the activation of toll-like receptor 4 (TLR-4), which phosphorylate transcription of nuclear factor kappa B (NF-κb). This is the first study analyzing paclitaxel effects on healthy human epidermal cells with an epidermis 3D model, and will help in understanding paclitaxel's effects on the skin.