Hyaluronate accumulation in human epidermis treated with retinoic acid in skin organ culture

A novel sophorolipids extraction method by yeast fermentation process for enhanced skin efficacy

AIMS

Oriental herbs have been used as medicines in the folk remedy for their numerous phytochemicals and bioactivities. In this study, we have selected five Korean traditional medical herbs and applied bio conversion extraction technology, named it as Bioconversion Oji complex, to identify phytochemicals and evaluate skin related efficacies.

MATERIAL AND METHODS

The process of two-step bio conversion was sequentially conducted. The first step of fermentation was to produce biosurfactants using macadamia seed oil with Candida bombicola, and then five natural plants were added to carry out the main fermentation. To evaluate skin improvement efficacy of Bioconversion Oji complex, in vitro and in vivo studies were conducted. We studied HaCaT cells cultured to assess viability, skin anti-inflammatory, moisturizing and barrier improvement-related mRNA expression. For efficacy study, 21 participants were tested evaluating anti-inflammatory, skin moisturizing and skin barrier improving effects of Bioconversion Oji complex compared to Water extraction of Oji (placebo) for the 4 weeks test period.

RESULTS

The application of bioconversion technology highly increased the content of amino acids and lipids within Bioconversion Oji complex, and 23 flavonoids were also identified. Bioconversion Oji complex was found to be non-toxic and showed significant effects in all parameters tested, including anti-inflammation, skin moisture, and skin barrier in both in vitro and in clinical studies.

CONCLUSIONS

Bioconversion Oji complex has demonstrated skin-friendly properties with significant beneficial effects on anti-inflammatory, skin hydration and barrier function properties. This study provides evidence for the use of Bioconversion Oji complex as an active ingredient in cosmetics and skincare products.

Recent Updates on Nanocosmeceutical Skin Care and Anti-Aging Products

Nanotechnology is an innovative area of science that deals with things smaller than 100 nanometers. The influence of nanotechnology in the cosmetic industry is overwhelming since it can enhance the properties attained by the particles at the nano level which includes color, solubility, etc, and also promotes the bioavailability of API. A plethora of nanomaterials can be employed in cosmetics including organic and inorganic nanoparticles. Unlike orthodox carriers, they facilitate easy penetration of the product into the skin and thereby increasing the stability and allowing a controlled drug release so that they can permeate deeper into the skin and start revitalizing it. Nanomaterials rejuvenate the skin by forming an occlusive barrier to inhibit the loss of water from the skin's surface and thereby moisturize the skin. Nano-cosmeceuticals are used to provide better protection against UV radiation, facilitate deeper skin penetration, and give long-lasting effects. Although they still have some safety concerns, hence detailed characterization or risk assessments are required to fulfill the standard safety requirements. In this review, an attempt is made to make a brief overview of various nanocosmeceutical skincare and anti-aging products.

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.

Anti-Inflammatory, Antioxidant, Moisturizing, and Antimelanogenesis Effects of Quercetin 3-O-β-D-Glucuronide in Human Keratinocytes and Melanoma Cells via Activation of NF-κB and AP-1 Pathways

Quercetin 3-O-β-D-glucuronide (Q-3-G), the glucuronide conjugate of quercetin, has been reported as having anti-inflammatory properties in the lipopolysaccharide-stimulated macrophages, as well as anticancer and antioxidant properties. Unlike quercetin, which has been extensively described to possess a wide range of pharmacological activities including skin protective effects, the pharmacological benefits and mechanisms Q-3-G in the skin remained to be elucidated. This study focused on characterizing the skin protective properties, including anti-inflammatory and antioxidant properties, of Q-3-G against UVB-induced or H₂O₂-induced oxidative stress, the hydration effects, and antimelanogenesis activities using human keratinocytes (HaCaT) and melanoma (B16F10) cells. Q-3-G down-regulated the expression of the pro-inflammatory gene and cytokine such as cyclooxygenase-2 (COX-2) and tumor necrosis factor (TNF)-α in H₂O₂ or UVB-irradiated HaCaT cells. We also showed that Q-3-G exhibits an antioxidant effect using free radical scavenging assays, flow cytometry, and an increased expression of nuclear factor erythroid 2- related factor 2 (Nrf2). Q-3-G reduced melanin production in α-melanocyte-stimulating hormone (α-MSH)-induced B16F10 cells. The hydration effects and mechanisms of Q-3-G were examined by evaluating the moisturizing factor-related genes, such as transglutaminase-1 (TGM-1), filaggrin (FLG), and hyaluronic acid synthase (HAS)-1. In addition, Q-3-G increased the phosphorylation of c-Jun, Jun N-terminal kinase (JNK), Mitogen-activated protein kinase (MAPK) kinase 4 (MKK4), and TAK1, involved in the MAPKs/AP-1 pathway, and the phosphorylation of IκBα, IκB kinase (IKK)-α, Akt, and Src, involved in the NF-κB pathway. Taken together, we have demonstrated that Q-3-G exerts anti-inflammatory, antioxidant, moisturizing, and antimelanogenesis properties in human keratinocytes and melanoma cells through NF-κB and AP-1 pathways.

Aspergillus oryzae-Fermented Wheat Peptone Enhances the Potential of Proliferation and Hydration of Human Keratinocytes through Activation of p44/42 MAPK

Identifying materials contributing to skin hydration, essential for normal skin homeostasis, has recently gained increased research interest. In this study, we investigated the potential benefits and mechanisms of action of Aspergillus oryzae-fermented wheat peptone (AFWP) on the proliferation and hydration of human skin keratinocytes, through in vitro experiments using HaCaT cell lines. The findings revealed that compared to unfermented wheat peptone, AFWP exhibited an improved amino acid composition, significantly (p < 0.05) higher DPPH scavenging capability and cell proliferation activity, and reduced lipopolysaccharide-induced NO production in RAW 264.7 cells. Furthermore, we separated AFWP into eleven fractions, each ≤2 kDa; of these, fraction 4 (AFW4) demonstrated the highest efficacy in the cell proliferation assay and was found to be the key component responsible for the cell proliferation potential and antioxidant properties of AFWP. Additionally, AFW4 increased the expression of genes encoding natural moisturizing factors, including filaggrin, transglutaminase-1, and hyaluronic acid synthase 1–3. Furthermore, AFW4 activated p44/42 MAPK, but not JNK and p38 MAPK, whereas PD98059, a p44/42 MAPK inhibitor, attenuated the beneficial effects of AFW4 on the skin, suggesting that the effects of AFW4 are mediated via p44/42 MAPK activation. Finally, in clinical studies, AFW4 treatment resulted in increased skin hydration and reduced trans-epidermal water loss compared with a placebo group. Collectively, these data provide evidence that AFW4 could be used as a potential therapeutic agent to improve skin barrier damage induced by external stresses.

Antiwrinkle efficacy of 1-ethyl-β-N-acetylglucosaminide, an inducer of epidermal hyaluronan production

BACKGROUND

Hyaluronan (HA) has a unique hydration capacity that contributes to firmness and bounciness of the skin. Epidermal HA declines with skin aging, which may lead to clinical signs of aging including skin wrinkles and loss of hydration and elasticity. Recently, we developed a new cosmetic agent 1-ethyl-β-N-acetylglucosaminide (β-NAG2), which enhances HA production in cultured human keratinocytes. The aim of this study was to explore antiaging potential of β-NAG2 in reconstructed human epidermal models and human clinical trial.

MATERIALS AND METHODS

The amount of HA in β-NAG2-treated epidermal models by topical application was analyzed by enzyme-linked immunosorbent assay (ELISA)-like assay. A randomized, double-blind and placebo-controlled study was conducted in Japanese females (n = 33) by topically treating each side of the face with a lotion formulated with β-NAG2 or placebo for 8 weeks.

RESULTS

Topically applied β-NAG2 dose dependently increased HA production in epidermal models. Treatment with β-NAG2-formulated lotion significantly improved skin hydration and elasticity and reduced skin wrinkling in crow's foot areas when compared to the placebo formulation.

CONCLUSION

Topically applied β-NAG2 promoted epidermal HA production in vitro and showed antiwrinkle activity in vivo accompanying the improvement in skin hydration and elasticity. Our study provides a novel strategy for antiwrinkle care through β-NAG2-induced epidermal HA production.

Genome Divergence and Dynamics in the Thin-Tailed Desert Sheep From Sudan

With climate change bound to affect food and feed production, emphasis will shift to resilient and adapted indigenous livestock to sustain animal production. However, indigenous livestock comprise several varieties, strains and ecotypes whose genomes are poorly characterized. Here, we investigated genomic variation in an African thin-tailed Desert Sheep sampled in Sudan, using 600K genotype data generated from 92 individuals representing five ecotypes. We included data from 18 fat-tailed and 45 thin-tailed sheep from China, to investigate shared ancestry and perform comparative genomic analysis. We observed a clear genomic differentiation between the African thin-tailed Desert Sheep and the Chinese thin-tailed and fat-tailed sheep, suggesting a broad genetic structure between the fat-tailed and thin-tailed sheep in general, and that at least two autosomal gene pools comprise the genome profile of the thin-tailed sheep. Further analysis detected two distinct genetic clusters in both the African thin-tailed Desert Sheep and the Chinese thin-tailed sheep, suggesting a fine-scale and complex genome architecture in thin-tailed sheep. Selection signature analysis suggested differences in adaptation, production, reproduction and morphology likely underly the fine-scale genetic structure in the African thin-tailed Desert Sheep. This may need to be considered in designing breeding programs and genome-wide association studies.

1-Ethyl-β-N-acetylglucosaminide increases hyaluronan production in human keratinocytes by being converted to N-acetylglucosamine via β-N-acetylglucosaminidase-dependent manner

Regulation of hyaluronan (HA) is important for the maintenance of epidermal homeostasis. Here, we examined the mechanism by which 1-ethyl-β-N-acetylglucosaminide (β-NAG2), a newly developed N-acetylglucosamine (NAG) derivative, increases HA production in cultured human epidermal keratinocytes. When keratinocytes were treated with β-NAG2, mRNA expression of HA synthase 3, which is responsible for HA production in human keratinocytes, was not influenced, but the intracellular level of UDP-NAG, a substrate used for HA synthesis, was increased. By using a synthetic substrate for β-N-acetylglucosaminidase (β-NAGase), keratinocytes were found to possess β-NAGase activity, and treatment of o-(2-acetamido-2-deoxy-d-glucopyranosylidene) amino N-phenyl carbamate (PUGNAc), an inhibitor of β-NAGase, abolished the release of NAG from β-NAG2 in keratinocytes. Furthermore, PUGNAc attenuated the β-NAG2-induced intracellular UDP-NAG and HA production in keratinocytes. These results suggest that β-NAG2 is converted to NAG by endogenous β-NAGase in keratinocytes, and the resulting NAG is further metabolized to UDP-NAG and utilized for HA production.

Extracellular Superoxide Dismutase Prevents Skin Aging by Promoting Collagen Production through the Activation of AMPK and Nrf2/HO-1 Cascades

With aging, the skin becomes thin and drastically loses collagen. Extracellular superoxide dismutase (EC-SOD), also known as superoxide dismutase (SOD) 3, is the major SOD in the extracellular matrix of the tissues and is well-known to maintain the reduction‒oxidation homeostasis and matrix components of such tissues. However, the role of EC-SOD in aging-associated reductions of skin thickness and collagen production is not well-studied. In this study, we compared the histological differences in the dorsal skin of EC-SOD‒overexpressing transgenic mice (Sod3^+/+) of different age groups with that in wild-type mice and also determined the underlying signaling mechanism. Our data showed that the skin thickness in Sod3^+/+ mice significantly increased with aging compared with that in wild-type male mice. Furthermore, Sod3^+/+ mice had promoted collagen production through the activation of adenosine monophosphate-activated protein kinase and Nrf2/HO-1 pathways in aged mice. Interestingly, subcutaneous injection of adeno-associated virus‒overexpressing EC-SOD exhibited increased skin thickness and collagen expression. Furthermore, combined recombinant EC-SOD and dihydrotestosterone treatment synergistically elevated collagen production through the activation of TGFβ in human dermal fibroblasts. Altogether, these results showed that EC-SOD prevents skin aging by promoting collagen production in vivo and in vitro. Therefore, we propose that EC-SOD may be a potential therapeutic target for antiaging in the skin.

Interventions Preventing Vaginitis, Vaginal Atrophy after Brachytherapy or Radiotherapy Due to Malignant Tumors of the Female Reproductive Organs-A Systematic Review

BACKGROUND

Radiotherapy, as a method of treatment of cervical and uterine cancers, may induce severe late-onset vaginal side effects. Unfortunately, little evidence on the management of adverse effects has been presented. This study aimed to evaluate the available interventions which reduce symptoms of vaginitis and vaginal atrophy by improving dyspareunia, mucosal inflammation, vaginal pH and vaginal dryness in women who have undergone brachytherapy or radiotherapy due to uterine or cervical malignancies.

MATERIALS AND METHODS

A comprehensive literature search was performed following PRISMA guidelines. The systematic search was conducted using electronic databases, namely Scopus, Web of Science and PubMed, between October and November 2020 to identify randomized controlled trials (RCT) and, prospective randomized studies (PRS).

RESULTS

The analyzed population consists of 376 patients with uterine or cervical cancer, treated with hyaluronic acid, vitamin A, vitamin E, alpha-tocopherol acetate and dienestrol. Intervention with HA along with vitamin A and vitamin E revealed advantage in endpoints such as reduced dyspareunia, vaginal mucosal inflammation, vaginal dryness, bleeding, fibrosis and cellular atypia. Administration of alpha-tocopherol acetate reduced vaginal mucosal inflammation and improved vaginal acanthosis, whereas dienestrol resulted in reduced dyspareunia, vaginal caliber and bleeding.

CONCLUSIONS

Vaginal suppositories were found to be clinically effective at the management of late-onset vulvovaginal side effects after radiotherapy.

Basement Membrane Helps Maintain Epidermal Hyaluronan Content

Hyaluronan (HA) is the major glycosaminoglycan in the extracellular matrix of most mammalian tissues, including the epidermis. It is synthesized in epidermis, and mainly metabolized after transfer to the liver via lymphatic vessels in the dermis following its passage through the basement membrane (BM) at the dermal-epidermal junction. The aim of the present study was to investigate the influence of BM integrity on the level of HA in the epidermis. Epidermal HA content was decreased in sun-exposed skin of older subjects, whose BM structure was impaired, compared with sun-exposed young skin and sun-protected skin, in which BM integrity was well maintained. In an organotypic culture model of sun-exposed facial skin, epidermal HA was increased in the presence of inhibitors of BM-degrading matrix metalloproteinases and heparanase. In a skin equivalent model treated with these inhibitors, HA content was increased in the epidermis, but decreased in conditioned medium. These findings suggest that the BM at the dermal-epidermal junction plays an important role in maintaining epidermal HA levels.

Low-Temperature Argon Plasma Regulates Skin Moisturizing and Melanogenesis-Regulating Markers through Yes-Associated Protein

Extensive water loss and melanin hyperproduction can cause various skin disorders. Low-temperature argon plasma (LTAP) has shown the possibility of being used for the treatment of various skin diseases, such as atopic dermatitis and skin cancer. However, the role of LTAP in regulating skin moisturizing and melanogenesis has not been investigated. In this study, we aimed to determine the effect of LTAP on yes-associated protein (YAP), a major transcriptional coactivator in the Hippo signaling pathway that is involved in skin moisturizing and melanogenesis-regulating markers. In normal human epidermal keratinocytes (NHEKs), the human epidermal keratinocyte line HaCaT, and human dermal fibroblasts (HDFs), we found that LTAP exhibited increased expression levels of YAP protein. In addition, the expression levels of filaggrin (FLG), which is involved in natural moisturizing factors (NMFs), and hyaluronic acid synthase (HAS), transglutaminase (TGM), and involucrin (IVL), which regulate skin barrier and moisturizing, were also increased after exposure to LTAP. Furthermore, collagen type I alpha 1 and type III alpha 1 (COL1A1, COL3A1) were increased after LTAP exposure, but the expression level of matrix metalloproteinase-3 (MMP-3) was reduced. Moreover, LTAP was found to suppress alpha-melanocyte stimulating hormone (α-MSH)-induced melanogenesis in murine melanoma B16F10 cells and normal human melanocytes (NHEMs). LTAP regulates melanogenesis of the melanocytes through decreased YAP pathway activation in a melanocortin 1 receptor (MC1R)-dependent manner. Taken together, our data show that LTAP regulates skin moisturizing and melanogenesis through modulation of the YAP pathway, and the effect of LTAP on the expression level of YAP varies from cell to cell. Thus, LTAP might be developed as a treatment method to improve the skin barrier, moisture content, and wrinkle formation, and to reduce melanin generation.

Accelerated human epidermal turnover driven by increased hyaluronan production

BACKGROUND

Hyaluronan (HA) is an essential component of extracellular matrix in the skin, but its functions in the epidermis remain elusive.

OBJECTIVE

We examined the interaction of increased HA production mediated by 1-ethyl-β-N-acetylglucosaminide (β-NAG2), a newly developed highly selective inducer of HA production which is intracellularly converted to UDP-N-acetylglucosamine, a substrate of HA, with epidermal proliferation and differentiation.

METHODS

The amount, molecular size and epidermal tissue distribution of HA and expression of CD44, a cell surface receptor for HA, were analyzed in β-NAG2-treated organ cultured human skin, reconstructed human skin equivalents or cultured human skin keratinocytes. The relationship between HA and epidermal proliferation or differentiation was examined.

RESULTS

β-NAG2 significantly increased HA production in the epidermis of skin explants or skin equivalents without affecting molecular size of HA (>2000 kDa) or CD44 mRNA expression. Histochemical experiments revealed that β-NAG2 enhances HA signals in the basal to granular layers of the epidermis of skin equivalents, accompanying increased epidermal stratification. Immunohistochemical experiments demonstrated that signals of Ki67, transglutaminase 1 and filaggrin are increased in β-NAG2-treated skin equivalents, and these observations were confirmed by the data showing that mRNA expression of PCNA, transglutaminase 1 (TGM1) and filaggrin (FLG) is significantly up-regulated by β-NAG2 in skin equivalents. Importantly, blockade of HA production by inhibiting conversion of β-NAG2 to UDP-NAG abolished β-NAG2-mediated up-regulation of PCNA, TGM1 and FLG mRNA expression in cultured keratinocytes.

CONCLUSION

These results suggest that increased epidermal HA production plays a key role in epidermal morphogenesis and homeostasis by accelerating keratinocyte proliferation and differentiation.

Role of FGF and Hyaluronan in Choroidal Neovascularization in Sorsby Fundus Dystrophy

Sorsby's fundus dystrophy (SFD) is an inherited blinding disorder caused by mutations in the tissue inhibitor of metalloproteinase-3 (TIMP3) gene. The SFD pathology of macular degeneration with subretinal deposits and choroidal neovascularization (CNV) closely resembles that of the more common age-related macular degeneration (AMD). The objective of this study was to gain further insight into the molecular mechanism(s) by which mutant TIMP3 induces CNV. In this study we demonstrate that hyaluronan (HA), a large glycosaminoglycan, is elevated in the plasma and retinal pigment epithelium (RPE)/choroid of patients with AMD. Mice carrying the S179C-TIMP3 mutation also showed increased plasma levels of HA as well as accumulation of HA around the RPE in the retina. Human RPE cells expressing the S179C-TIMP3 mutation accumulated HA apically, intracellularly and basally when cultured long-term compared with cells expressing wildtype TIMP3. We recently reported that RPE cells carrying the S179C-TIMP3 mutation have the propensity to induce angiogenesis via basic fibroblast growth factor (FGF-2). We now demonstrate that FGF-2 induces accumulation of HA in RPE cells. These results suggest that the TIMP3-MMP-FGF-2-HA axis may have an important role in the pathogenesis of CNV in SFD and possibly AMD.

Skin Structure-Function Relationships and the Wound Healing Response to Intrinsic Aging

Significance: Chronic wounds, such as diabetic foot ulcers, venous stasis ulcers, and pressure ulcers affect millions of Americans each year, and disproportionately afflict our increasingly older population. Older individuals are predisposed to wound infection, repeated trauma, and the development of chronic wounds. However, a complete understanding of how the attributes of aging skin affect the wound healing process has remained elusive. Recent Advances: A variety of studies have demonstrated that the dermal matrix becomes thinner, increasingly crosslinked, and fragmented with advanced age. These structural changes, as well as an increase in cell senescence, result in altered collagen fiber remodeling and increased stiffness. Studies combining mechanical testing with advanced imaging techniques are providing new insights into the relationships between these age-related changes. Emerging research into the mechanobiology of aging and the wound healing process indicate that the altered mechanical environment of aged skin may have a significant effect on age-related delays in healing. Critical Issues: The interpretation and synthesis of clinical studies is confounded by the effects of common comorbidities that also contribute to the development of chronic wounds. A lack of quantitative biomarkers of wound healing and age-related changes makes understanding structure-function relationships during the wound healing process challenging. Future Directions: Additional work is needed to establish quantitative and mechanistic relationships among age-related changes in the skin microstructure, mechanical function, and the cellular responses to wound healing.

Re-epithelialization of adult skin wounds: Cellular mechanisms and therapeutic strategies

Cutaneous wound healing in adult mammals is a complex multi-step process involving overlapping stages of blood clot formation, inflammation, re-epithelialization, granulation tissue formation, neovascularization, and remodelling. Re-epithelialization describes the resurfacing of a wound with new epithelium. The cellular and molecular processes involved in the initiation, maintenance, and completion of epithelialization are essential for successful wound closure. A variety of modulators are involved, including growth factors, cytokines, matrix metalloproteinases, cellular receptors, and extracellular matrix components. Here, we focus on cellular mechanisms underlying keratinocyte migration and proliferation during epidermal closure. Inability to re-epithelialize is a clear indicator of chronic non-healing wounds, which fail to proceed through the normal phases of wound healing in an orderly and timely manner. This review summarizes the current knowledge regarding the management and treatment of acute and chronic wounds, with a focus on re-epithelialization, offering some insights into novel future therapies.

Characterization of bound water in skin hydrators prepared with and without a 3D3P interpenetrating polymer network

Background

Hyaluronic acid (HA) has been considered the gold standard ingredient for improving skin hydration and combating age‐related effects, however it is an inefficient polymer with inconsistent results partially due to its poor skin penetration, surface deposition, and rapid degradation. Herein we report the synthesis and in vitro characterization of a newly developed, topical super‐humectant with the goal of attracting and binding water molecules more efficiently than traditional, cosmetic‐grade forms of HA.

Methods

A modified interpenetrating polymer network (IPN) was developed using three polymers into a three‐dimensional formation (3D3P) for entrapping HA and water. This 3D3P‐IPN functions as a super‐humectant, attracting and binding water molecules more efficiently than the traditional cosmetic‐grade forms of HA. We compare 3D3P‐IPN serum samples to a traditional commercial benchmark product of similar ingredients using microscopic analysis, rheology, Karl Fischer (KF) titration, differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and dynamic vapor sorption (DVS) techniques.

Results

The 3D3P‐IPN samples appeared to bind water tighter than the benchmark sample as evidenced by maximum endpoints of endotherms occurring at significantly higher temperatures. The DVS results further confirm this speculation as the 3D3P‐IPN samples lost approximately 10% less water up to 35% RH than the benchmark. The 3D3P‐IPN samples also absorbed more water as the humidity level increased,demonstrating superior humectant properties. KF titration indicated that all three samples had similar water concentrations; however, TGA results demonstrated that the benchmark (a viscous, humectant‐rich hydrating masque) did not have much bound water.

Conclusion

Through the synthesis of a 3D3P‐IPN using simplified methods, we were able to increase the water‐binding and HA‐delivery capabilities of a thin serum. This 3D3P‐IPN serum has potential to deliver more hydration to the skin's surface compared to traditional HA formulations.

Skin Protective Effect of Epigallocatechin Gallate

Epigallocatechin gallate (EGCG) is a catechin and an abundant polyphenol in green tea. Although several papers have evaluated EGCG as a cosmetic constituent, the skin hydration effect of EGCG is poorly understood. We aimed to investigate the mechanism by which EGCG promotes skin hydration by measuring hyaluronic acid synthase (HAS) and hyaluronidase (HYAL) gene expression and antioxidant and anti-pigmentation properties using cell proliferation assay, Western blotting analysis, luciferase assay, 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, and reverse transcription polymerase chain reaction (RT-PCR) analysis. RT-PCR showed that EGCG increased the expression of natural moisturizing factor-related genes filaggrin (FLG), transglutaminase-1, HAS-1, and HAS-2. Under UVB irradiation conditions, the expression level of HYAL was decreased in HaCaT cells. Furthermore, we confirmed the antioxidant activity of EGCG and also showed a preventive effect against radical-evoked apoptosis by downregulation of caspase-8 and -3 in HaCaT cells. EGCG reduced melanin secretion and production in melanoma cells. Together, these results suggest that EGCG might be used as a cosmetic ingredient with positive effects on skin hydration, moisture retention, and wrinkle formation, in addition to radical scavenging activity and reduction of melanin generation.

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.

Hyaluronan: More than just a wrinkle filler

Dermatology is a field that strives not only to alleviate skin disease (therapeutics) but also to improve the perception of wellness (cosmetics). Thus, in this special issue of Glycobiology, it seems appropriate to discuss the biology of a glycosaminoglycan, called hyaluronic acid (hyaluronan, or HA), that has become the most popular agent today for intradermal injections to improve wrinkles and other cosmetic defects. HA is a simple linear polymer in which a simple disaccharide is repeated thousands of time, thereby creating a huge hydrophilic molecule that confers a large volume of hydration and contributes to the turgor and flexibility of healthy skin. Beyond cosmetic considerations, however, HA also has important biological and physiological functions that were largely under-appreciated until recently. New research has confirmed that HA is dynamically produced by most skin cells, not only fibroblasts (the cells that make most of the skin's extracellular matrix) but also by keratinocytes in the outer protective layer (epidermis). For both fibroblasts and keratinocytes, HA plays a regulatory role in controlling cell physiology through interaction of extracellular HA with a major cell-surface receptor, CD44. This interaction mediates intracellular signaling both directly and indirectly, through CD44 interactions with the cytoskeleton and with EGF and TGFβ receptors. Furthermore, degradation of HA by specific hyaluronidase enzymes produces HA fragments that can help to regulate inflammatory processes. In this review, current knowledge about the role of HA in skin inflammation and wound healing are reviewed and possible future applications of such knowledge discussed.

Proteoglycans in Normal and Healing Skin

Significance: Proteoglycans have a distinct spatial localization in normal skin and are essential for the correct structural development, organization, hydration, and functional properties of this tissue. The extracellular matrix (ECM) is no longer considered to be just an inert supportive material but is a source of directive, spatial and temporal, contextual information to the cells via components such as the proteoglycans. There is a pressing need to improve our understanding of how these important molecules functionally interact with other matrix structures, cells and cellular mediators in normal skin and during wound healing. Recent Advances: New antibodies to glycosaminoglycan side chain components of skin proteoglycans have facilitated the elucidation of detailed localization patterns within skin. Other studies have revealed important proliferative activities of proteinase-generated fragments of proteoglycans and other ECM components (matricryptins). Knockout mice have further established the functional importance of skin proteoglycans in the assembly and homeostasis of the normal skin ECM. Critical Issues: Our comprehension of the molecular and structural complexity of skin as a complex, dynamic, constantly renewing, layered connective tissue is incomplete. The impact of changes in proteoglycans on skin pathology and the wound healing process is recognized as an important area of pathobiology and is an area of intense investigation. Future Directions: Advanced technology is allowing the development of new artificial skins. Recent knowledge on skin proteoglycans can be used to incorporate these molecules into useful adjunct therapies for wound healing and for maintenance of optimal tissue homeostasis in aging skin.

More than just a filler - the role of hyaluronan for skin homeostasis

In recent years, hyaluronan (HA) has become an increasingly attractive substance as a non-immunogenic filler and scaffolding material in cosmetic dermatology. Despite its wide use for skin augmentation and rejuvenation, relatively little is known about the molecular structures and interacting proteins of HA in normal and diseased skin. However, a comprehensive understanding of cutaneous HA homeostasis is required for future the development of HA-based applications for skin regeneration. This review provides an update on HA-based structures, expression, metabolism and its regulation, function and pharmacological targeting of HA in skin.

The use of hyaluronic acid based dressings to treat burns: A review

Deep cutaneous lesions such as burns, traumas or ulcers are all conditions characterized by a massive loss of dermis, bringing several important consequences. For the treatment of these conditions, the evolution of material science has made available new dressings based on natural and synthetic polymers. Hyaluronic acid (HA) is involved in many steps of the wound healing process, such as inflammation, granulation and re-epithelialization. In order to overcome the poor physical properties of the native polymer, such as solubility and rapid degradation, insoluble molecules starting from the natural compound were produced via esterification. Thanks to their improved structural properties, the dressings based on these hyaluronic acid derivatives represent a valuable option for the treatment of deep burns. This narrative monograph describes the development and the outcome of the use of these products in burns. The currently available clinical experience suggests that these HA medical devices represent a safe therapeutic method useful for the treatment of acute wounds.

Applications and emerging trends of hyaluronic acid in tissue engineering, as a dermal filler and in osteoarthritis treatment

Hyaluronic acid (HA) is a naturally occurring biodegradable polymer with a variety of applications in medicine, including scaffolding for tissue engineering, dermatological fillers and viscosupplementation for osteoarthritis treatment. HA is available in most connective tissues in body fluids such as synovial fluid and the vitreous humor of the eye. HA is responsible for several structural properties of tissues as a component of extracellular matrix and is involved in cellular signaling. Degradation of HA is a stepwise process that can occur via enzymatic or non-enzymatic reactions. A reduction in HA mass or molecular weight via degradation or slowing of synthesis affects physical and chemical properties such as tissue volume, viscosity and elasticity. This review addresses the distribution, turnover and tissue-specific properties of HA. This information is used as the context for considering recent products and strategies for modifying the viscoelastic properties of HA in tissue engineering, as a dermal filler and in osteoarthritis treatment.

Superoxide dismutase 3 suppresses hyaluronic acid fragments mediated skin inflammation by inhibition of toll-like receptor 4 signaling pathway: superoxide dismutase 3 inhibits reactive oxygen species-induced trafficking of toll-like receptor 4 to lipid rafts

AIMS

Hyaluronic acid (HA) is a component of the extracellular matrix and has been extensively applied for cosmetic, therapeutic, and antiaging purposes. However, HA fragments (HAFs) cause adverse effects. Considering that UV-exposure produces HAF that accumulated on the skin, the role of HAF in skin inflammation and its precise mechanism needs to be clarified, and strategies for the prevention of skin inflammation are necessary.

RESULTS

We found that extracellular superoxide dismutase (SOD), SOD3, suppresses HAF-mediated skin inflammation, while HAF mediated skin inflammation, macrophages and dendritic cells (DCs) dominantly infiltrate, up-regulating inflammatory cytokines and chemokines receptors. However, keratinocytes indirectly responded to HAF. Instead, epidermis containing keratinocytes were stimulated by secreted molecules from HAF-treated macrophages or DC and produced inflammatory molecules including chemokines, which, in turn, led to skin inflammation. This orchestrated inflammatory response was inhibited by SOD3. In addition, SOD3 inhibited DC maturation by suppressing the expression of major histocompatibility complex II, CD80, and CD86. Interestingly, these responses did not occur in Toll-like receptor 4 (TLR4) deficient mice. Similar to lipopolysaccharide (LPS), HAF promoted TLR4 translocation into the lipid rafts to initiate signaling. This trafficking was mediated, at least in part, by NAPDH oxidase-dependent reactive oxygen species (ROS) generation. Subsequently, nuclear factor kappa B (NFκB) subunit, p65, was recruited the promoters of genes encoding inflammatory molecules. This inflammatory machinery was blocked by SOD3.

INNOVATION AND CONCLUSION

Thus, we propose that SOD3 might provide an effective strategy for the treatment of HAF-mediated skin inflammation.

HAS3-induced accumulation of hyaluronan in 3D MDCK cultures results in mitotic spindle misorientation and disturbed organization of epithelium

The amount of hyaluronan (HA) is low in simple epithelia under normal conditions, but during tumorigenesis, trauma or inflammation HA is increased on the epithelial cells and surrounding stroma. Excessive HA in epithelia is suggested to interfere with cell-cell adhesions, resulting in disruption of the epithelial barrier function. In addition, stimulated HA synthesis has been correlated with epithelial-to-mesenchymal transition and invasion of cancer cells. However, the effects of HA overload on normal epithelial morphogenesis have not been characterized in detail. Madin-Darby canine kidney (MDCK) cells form polarized epithelial cysts, when grown in a 3-dimensional (3D) matrix. These cells were used to investigate whether stimulated HA synthesis, induced by stable overexpression of GFP-HAS3, influences cell polarization and epithelial morphogenesis. GFP-HAS3 expression in polarized MDCK cells resulted in active HA secretion at apical and basolateral membrane domains. HA-deposits interfered with the formation of cell-cell junctions, resulting in impaired barrier function. In 3D cyst cultures, HA accumulated into apical lumina and was also secreted from the basal side. The HAS3-expressing cysts failed to form a single lumen and instead displayed multiple small lumina. This phenotype was correlated with aberrant mitotic spindle orientation in dividing cells. The results of this study indicate that excess pericellular HA disturbs the normal cell-cell and cell-ECM interactions in simple epithelia, leading to aberrant epithelial morphogenesis. The morphological abnormalities observed in 3D epithelial cultures upon stimulated HAS3 expression may be related to premalignant changes, including intraluminal invasion and deregulated epithelialization, probably mediated by the mitotic spindle orientation defects.

Ultraviolet-B irradiation induces differential regulations of hyaluronidase expression and activity in normal human keratinocytes

Skin aging is a complex process determined by genetic factors (intrinsic aging) and environmental factors (extrinsic aging). One of the most influential environmental factor is UV-B irradiation. Hyaluronic acid (HA) is an abundant component of skin extracellular matrix where it plays many roles such as hydration and architectural support. Downregulation of HA during photoaging was reported previously. Changes in expression and function of its degrading enzymes, the hyaluronidases (Hyals) might be involved in this decrease. In the present study, normal human keratinocytes were submitted to increasing doses of UV-B. The mRNA expression of HYAL1, HYAL2 and HYAL3 and the hyaluronidase enzymatic activity were quantified using real-time PCR and a microtiter-based assay, respectively. After UV-B irradiation, HYAL1 mRNA expression was upregulated whereas HYAL2 and HYAL3 mRNAs were downregulated and hyaluronidase enzymatic activity was increased in both cell layer and culture medium. In parallel, immunohistochemical studies performed on UV-B irradiated reconstructed epidermis confirmed that Hyal-1, Hyal-2 and Hyal-3 protein expression were differently regulated by UV-B. Taken together, our results demonstrate that UV-B irradiation induces differential regulations of hyaluronidase expression and enzymatic activity in human keratinocytes. These differential modulations of hyaluronidase expression and activity by UV-B could contribute to cutaneous photoaging.

Fluorescence detection of hyaluronidase

We labeled hyaluronan (HA) with two fluorophores, fluorescein amine and rhodamine B amine. These two fluorophores are suitable for a fluorescence (Foerster) resonance energy transfer (FRET) which results in a fluorescein quenching and an enhanced rhodamine emission. Such labeled HA (HA-FRET) is a potential sensor for HA degradation. We studied fluorescence properties of HA-FRET in the absence and presence of hyaluronidase enzyme (HA-ase). The time-resolved fluorescence measurements indicate more than 50% of FRET in the absence of HA-ase. In the presence of HA-ase FRET decreases with time, and relative fluorescence intensities of fluorescein and rhodamine shifts to fluorescein indicating a release of FRET. The kinetics of the digestion process of HA by HA-ase depends on the concentration of the enzyme. We demonstrate that simultaneous measurements of green and red emission of HA-FRET can be used in ratio metric detection of the HA-ase presence and activity. This in turn, can be utilized for the construction of a robust but reliable HA-ase sensing device.

4-Methylumbelliferone inhibits tumour cell growth and the activation of stromal hyaluronan synthesis by melanoma cell-derived factors

BACKGROUND

There is a close correlation between tumour progression and hyaluronan production, either by tumour cells or by stromal cells that are stimulated by tumour-derived factors. Inhibition of tumour stimulation of fibroblast hyaluronan may suppress tumour growth and invasion.

OBJECTIVES

To examine the effect of the hyaluronan synthesis inhibitor 4-methylumbelliferone (4-MU) on the growth of and hyaluronan synthesis by fibroblasts and C8161 and MV3 melanoma cell lines, invasion, and inhibition of tumour cell-derived factor activation of fibroblasts.

METHODS

Effects of 4-MU on growth and hyaluronan synthesis by fibroblasts and melanoma cells were examined in monolayer culture and fibroblast-contracted collagen lattices, and their effects on the growth and invasion of tumour cells into collagen lattices were also studied.

RESULTS

4-MU caused a dose-dependent growth inhibition of fibroblast and melanoma cells with maximum inhibition at 0·5 mmol L(-1) 4-MU. At this dose, 4-MU inhibited (3) H-glucosamine incorporation into fibroblast glycosaminoglycans by 52%, and hyaluronan synthesis by 64%. The relative inhibition was more pronounced when fibroblasts were stimulated with C8161 melanoma cell-conditioned medium. 4-MU reduced the level of hyaluronan in fibroblast-contracted collagen lattices, and inhibited both the growth on and invasion into the lattices by melanoma cells. This growth inhibition appears to be predominantly independent of inhibition of hyaluronan synthesis. The effect on growth inhibition was reversible, and 4-MU had no effect on apoptosis.

CONCLUSIONS

4-MU is a potent inhibitor of hyaluronan synthesis, induction of stromal hyaluronan accumulation by tumour cells, and fibroblast and melanoma cell proliferation, and results suggest that 4-MU may have potential as a tumour cell anti-invasive and antiproliferative agent.

Stimulation of epidermal calcium gradient loss increases the expression of hyaluronan and CD44 in mouse skin

BACKGROUND

Hyaluronan (HA), a major extracellular matrix component in epidermis, has been found to accumulate in the epidermis after disruption of the epidermal barrier; however, the precise mechanisms underlying this process are not yet clear. Alterations in the epidermal calcium gradient are an important signal for permeability-barrier homeostasis. Thus, we hypothesized that epidermal calcium-ions might regulate HA expression.

AIM

To investigate whether changes in the epidermal calcium gradient and subsequent induction of cytokines regulate HA, HA synthase (HAS) and HA receptor (CD44) expression in mouse epidermis, and to clarify the mechanisms of HA induction.

METHODS

Sonophoresis of 1.5 mmol/L Ca(2+)-containing gel or Ca(2+)-free gel was performed to manipulate the epidermal Ca(2+) content without disrupting the permeability barrier. We also manipulated the Ca(2+) gradient by tape-stripping with or without 2 h immersion in 1.2 mmol/L Ca(2+)-containing solutions. Next we inhibited cytokine activity using tumour necrosis factor (TNF)-alpha or interleukin (IL)-1 inhibitors before sonophoresis. Six hours after each treatment, the expression of HA, HAS and CD44 were analysed using reverse transcription PCR and immunohistochemical stains.

RESULTS

Sonophoresis of Ca(2+)-free gel significantly increased HA, HAS3 and CD44 expression in epidermis and in tape-stripped skin. However, the inhibition of Ca(2+) decrease in the upper epidermis by sonophoresis of Ca(2+)-containing gel or immersion of barrier-disrupted skin into a Ca(2+)-containing solution attenuated these inductions. Specific inhibitors of TNF-alpha and IL-1 specific inhibitors also abolished the sonophoresis-induced expression of HA, HAS3 and CD44.

CONCLUSIONS

These results suggest that modulations in epidermal calcium regulate HA and CD44 expression directly or via induction of cytokines.

Stimulating effects of Bacillus subtilis natto-fermented Radix astragali on hyaluronic acid production in human skin cells

ETHNOPHARMACOLOGICAL RELEVANCE

Radix astragali, a well-known Chinese herb, which has been traditionally used for skincare, and microbial fermentation is one of the conventional methods for processing Chinese herbs.

AIM OF THE STUDY

This research studied the effects of non-fermented (HQNB) and fermented preparations (HQB) of Radix astragali on hyaluronic acid (HA) production in primary human skin cells.

MATERIALS AND METHODS

HQB and HQNB were prepared and added to the cultures of primary human skin cells. Hyaluronic acid content was determined using ELISA. Real-time RT-PCR was used to evaluate hyaluronan synthase gene expression. The bioactive compounds were analyzed by HPLC.

RESULTS

The growth-stimulating effect of HQNB on both of keratinocytes and fibroblasts were significantly higher than that of HQB. Conversely, HQB, but not HQNB significantly stimulated HA production in both cultured primary human epidermal keratinocytes and human dermal fibroblasts in dose-dependent manners. In addition, HQB markedly and dose-dependently increased the expression of hyaluronan synthase 3 and hyaluronan synthase 2 mRNA in HaCaT cells and human fibroblasts, respectively. Therefore, HQB might be a promising candidate for preventing the age-dependent loss of HA content in aged human skin, and its effect on the enhancement of HA synthesis in skin cells is highly related to its effect on the expression of hyaluronan synthase genes. The three major active isoflavonoids in Radix astragali were identified as ononin, calycosin, and formononetin. After fermentation, all of these three compounds in HQB were significantly reduced. However, HQB still had significantly higher enhancement effect on the production of HA than HQNB. It appeared that isoflavonoid aglycones or other metabolites, converted from their primary isoflavones during fermentation, might be responsible for the skincare functions found in this study.

CONCLUSION

This study demonstrated the low toxicity and the stimulating effects of HQB on HA synthesis, and suggests that HQB may play a promising role in anti-aging cosmetic applications.

A Bilayer Hyaluronic Acid Wound Dressing to Promote Wound Healing in Diabetic Ulcer

Several spongy wound dressings composed of various hyaluronic acid (HA) materials were developed: HA aqueous solution with cross-linking agent (epoxy compound (HAWC), without cross-linking agent (HAWOC), and combined bilayer material HAWC and HAWOC (2LHA). The microstructure, sensitivity to hyaluronidase, sensitivity to free radicals, in vitro cytotoxicity, healing potential on full-thickness defect on and diabetic ulcers were evaluated. Scanning electron micrograph views of all HA wound dressings showed an interconnected channel and high porosity structure. HAWOC was degraded rapidly in hyaluronidase and free radical solution. The in vitro cytotoxicity of HAWC was significantly (p<0.05) higher than other HA wound dressings and reduced the released amount of VEGF from human fibroblast. The HAWOC remarkably facilitated the formation of vascularized granulation tissue and provided a HA enrichment wound healing process of either a full-thickness defect or a diabetic ulcer. In contrast, the presence of un-degradable products of HAWC seemed to interfere dermal tissue restoration. Nevertheless, because of the fragile properties, rapid degradation and wound adhesion of HAWOC, the 2LHA should be developed for diabetic ulcer therapy.

Matrix Gene Expression in Dermal Fibroblasts Cultured on Hyaluronan-coated Polysulfone Membranes

Polysulfone (PSU) membranes, coated and uncoated hyaluronan (HA), were compared for their ability to allow dermal fibroblast express genes related to extracellular matrix synthesis and remodeling. Fibroblasts type I and type III collagens were studied on both types of membranes; only type I collagen was synthesized on control cultures in plastic Petri dishes, whereas type III collagen was also expressed on PSU membranes. Expression of metalloproteinase (MMP)1, MMP3, and MMP2 was enhanced on PSU and HA-coated PSU membranes, with a lower level of MMP2 on HA-covered membranes. These membranes promote fetal-like matrices that provide good support for skin wound healing as well as favor nonscarring tissue repair.

Development, molecular composition and freeze tolerance of bovine embryos cultured in TCM-199 supplemented with hyaluronan

Hyaluronan (HA) is glycosaminoglycan that is present from the start of embryonic development and its role and concentration increases with embryo development. The objective of this study was to evaluate if the presence of HA in TCM-199 culture medium had an effect on the development and quality of bovine embryos. There was no effect of HA on the total number of zygotes developing to blastocysts on day 7, however more expanded and hatched blastocyst stages were observed on days 8 and 9 in the group supplemented with HA (p< 0.05). Following freeze/thawing, significantly more (p< 0.05) embryos cultured in medium supplemented with HA hatched than those cultured in TCM-199 alone or those with BSA. Medium supplemented with HA and BSA significantly increased the level of expression of glucose metabolismGlut-1gene and embryo compactionCx43gene (p< 0.05), and had no effect onGlut-5andIGF-IIexpression. In addition, HA presence in culture decreased the level of expression of apoptosisBaxand oxidative stressSOXgenes (p< 0.05). There was significant difference in total number of nuclei between TCM-199 medium only and the remaining media containing BSA or HA plus BSA, between which there was no difference. In summary, our results indicate that the addition of high molecular weight HA to TCM-199 medium that contains BSA on day 4 of culture improved embryo development to hatching and hatched blastocysts and the quality of produced embryos, which were superior to embryos cultured without HA addition.

Oral intake of soy isoflavone aglycone improves the aged skin of adult women

A double-blind, placebo-controlled trial was conducted to clinically evaluate the effect of soy isoflavone aglycone on the aged skin of middle-aged women. Twenty-six women volunteers in their late 30s and early 40s were randomly assigned to receive either a test food (13 women, the test food group) or a placebo food (13 women, the control group). These groups were given the test food (40 mg of soy isoflavone aglycone per day) and placebo, respectively, for 12 wk. The extent of linear and fine wrinkles at the lateral angle of the eyes was selected as the major evaluation criterion to assess the effects of foods, and the wrinkles' area ratio was used as the evaluation parameter. The extent of skin microrelief at the lateral angle of eyes and that of malar skin elasticity were used as secondary evaluation criteria, and the skin microrelief's area ratio and recovery of skin elasticity were used as the respective evaluation parameters. These parameters were assessed 4, 8, and 12 wk after the start of the test food or placebo intake. The test food group showed a statistically significant improvement of fine wrinkles at week 12 (p<0.05) and of malar skin elasticity at week 8 (p<0.05), compared with the control group. Although there was no significant difference between the test food group and the control group regarding effects on skin microrelief at lateral angle of the eyes, a significant intragroup improvement was observed at week 8 in the test food group (p<0.05). As for the test food safety, none of the subjects presented adverse symptoms during the study period or discontinued the intake of the test food. These data indicate that the oral intake of 40 mg soy isoflavone aglycones per day improves the aged skin of middle-aged women.

Hyaluronan-dependent pericellular matrix

Hyaluronan is a multifunctional glycosaminoglycan that forms the structural basis of the pericellular matrix. Hyaluronan is extruded directly through the plasma membrane by one of three hyaluronan synthases and anchored to the cell surface by the synthase or cell surface receptors such as CD44 or RHAMM. Aggregating proteoglycans and other hyaluronan-binding proteins, contribute to the material and biological properties of the matrix and regulate cell and tissue function. The pericellular matrix plays multiple complex roles in cell adhesion/de-adhesion, and cell shape changes associated with proliferation and locomotion. Time-lapse studies show that pericellular matrix formation facilitates cell detachment and mitotic cell rounding. Hyaluronan crosslinking occurs through various proteins, such as tenascin, TSG-6, inter-alpha-trypsin inhibitor, pentraxin and TSP-1. This creates higher order levels of structured hyaluronan that may regulate inflammation and other biological processes. Microvillous or filopodial membrane protrusions are created by active hyaluronan synthesis, and form the scaffold of hyaluronan coats in certain cells. The importance of the pericellular matrix in cellular mechanotransduction and the response to mechanical strain are also discussed.

Dermatoporosis: A Chronic Cutaneous Insufficiency/Fragility Syndrome

BACKGROUND

Skin aging has long been considered only as a cosmetic problem. With the increase in lifespan, we are now more often experiencing a further dimension of skin aging, which is no longer only cosmetic, but also functional, in the sense that the skin has lost its protective mechanical function. Dermatoporosis is the name proposed to capture, in a holistic approach, all the aspects of this chronic cutaneous insufficiency/fragility syndrome.

OBSERVATIONS

In this paper, we review the clinical aspects of dermatoporosis, its histological features and the current understanding of its etiological factors. The clinical manifestations of dermatoporosis comprise (i) morphological markers of fragility--rather trivial--such as senile purpura, stellate pseudoscars and skin atrophy, and (ii) functional expression of skin fragility resulting from minor traumas such as frequent skin laceration, delayed wound healing, nonhealing atrophic ulcers and subcutaneous bleeding with the formation of dissecting hematomas leading to large zones of necrosis. Dissecting hematomas bear significant morbidity needing hospitalization and urgent surgical procedures. Molecular mechanisms implying hyaluronate-CD44 pathways in the control and maintenance of epithelial growth and the viscoelastic properties of the extracellular matrix offer new opportunities for preventive intervention.

CONCLUSION

We propose to group the different manifestations and implications of this syndrome under the umbrella term of 'dermatoporosis', because we think it will help to capture the understanding of health professionals that, as osteoporosis, 'dermatoporosis' should be prevented and treated to avoid complications. Dermatologists should be aware of this emerging syndrome and function as key players in prevention and therapy. Randomized clinical trials should demonstrate which intervention may best prevent and/or reverse dermatoporosis.

The effect of vestibular nerve section on the expression of the hyaluronan in the frog, Rana esculenta

Following postganglionic lesion of the eighth cranial nerve, the changes in the expression of hyaluronan (HA), one of the extracellular matrix macromolecules, were examined in the medial (MVN) and lateral (LVN) vestibular nuclei and in the entry or transitional zone (TZ) of the nerve in the frog. HA was detected in different survival times by using a specific biotinylated hyaluronan-binding probe. HA expression was defined by the area-integrated optical density (AIOD), calculated from pixel intensities of digitally captured images. During the first postoperative days the perineuronal net (PN), a HA-rich area around the neurons, was not distinguishable from the surrounding neuropil in the MVN and LVN, characterized by a bilateral drop of AIOD specifically on the operated side. From postoperative day 14 onwards AIOD increased whilst the PN reorganized. In contrast, the AIOD wobbled up and down bilaterally without any trend in the TZ. Statistical analysis indicated that AIOD changes in the structures studied ran parallel bilaterally presumably because of the operation. Our results demonstrated for the first time that (1) the lesion of the eighth cranial nerve is accompanied by the modification of AIOD reflected HA expression in the MVN, LVN and TZ, (2) different tendencies exist in the time course of AIOD in the structures studied and (3) these tendencies are similar on the intact and operated sides. Our findings may suggest an area dependent molecular mechanism of HA in the restoration of vestibular function.

Integration of the activation of the human hyaluronan synthase 2 gene promoter by common cofactors of the transcription factors retinoic acid receptor and nuclear factor kappaB

Hyaluronan (HA) is a polysaccharide of the vertebrate extracellular matrix, produced by three related HA synthases (HASs) that influence numerous physiological processes. We screened the first 2250 bp of the HAS2 promoter for transcription factor response elements (REs) in silico and found 1 cluster of 2 retinoic acid (RA) REs, 3 discrete NF-kappaB factors, and 12 Sp1 REs. In parallel, we scanned nine overlapping promoter regions in HaCaT human immortalized keratinocytes using chromatin immunoprecipitation assays to identify binding of mediator, coactivator, and corepressor proteins and Sp1 transcription factor in response to all-trans-RA and tumor necrosis factor-alpha (TNF-alpha). We found that all-trans-RA modulated the binding of the RA receptor and several coregulators to the region containing the RARE cluster at position -1230. The importance of this region is supported in reporter gene assays by the all-trans-RA induction of the respective promoter region. Similarly, we showed by chromatin immunoprecipitation assays as well as by gel-shift assays with nuclear extracts that TNF-alpha induced NF-kappaB binding to regions at positions -380, -1420, and -1890, demonstrated its association with RNA polymerase II and cofactor proteins, and confirmed the functionality of the respective promoter regions in vivo. These findings partially explain the induction of HAS2 mRNA by all-trans-RA and TNF-alpha and provide an example how the action of different transcription factor families can use the same cofactors.

Differential regulation of hyaluronan metabolism in the epidermal and dermal compartments of human skin by UVB irradiation

Hyaluronan (HA), a major component of the cutaneous extracellular-matrix, is involved in tissue repair. Human skin is exposed to and damaged by UVB-irradiation. Here, we investigate the regulation of HA metabolism in human skin during acute UVB-induced inflammation. Expression of HA synthesizing (HAS) and degrading enzymes hyaluronidase (HYAL) as evaluated by quantitative reverse transcribed PCR in response to UVB differed when fibroblasts and HaCaT-keratinocytes, representative cell types in dermis and epidermis, respectively, were compared. Both demonstrated temporally different expression patterns of these genes 3- and 24-hours post-irradiation. This resulted 24-hours post-irradiation in an increase in HAS gene expression in both fibroblasts and HaCaT-keratinocytes, and an increase in HYAL expression only in fibroblasts. HA-production as analyzed by the HA content of conditioned medium was reduced in HaCaT and fibroblast cultures 3-hours post-irradiation, whereas HA increased in HaCaT-cultures 24-hours post-irradiation but remained suppressed in fibroblasts-cultures. Consistently, immunohistochemical staining for HA in human skin 24-hours post-irradiation demonstrated an increased epidermal HA, but a decrease in the dermal compartment. Moreover, analysis of the HA content of dermal microdialysis-fluid revealed increased accumulation of HA degradation products 24-hours post-irradiation. These data demonstrate that there is a complex temporal and spatial regulation of HA-metabolism in skin in response to UVB irradiation.

The effects of Musk T on peroxisome proliferator-activated receptor [PPAR]-alpha activation, epidermal skin homeostasis and dermal hyaluronic acid synthesis

Peroxisome proliferators activated receptors (PPARs) are a family of nuclear hormone receptors that heterodimer with the retinoid X receptor and function as transcriptional regulators of genes. Topically Applied PPAR-alpha agonists possess receptor mediated, pro-differentiating/anti-proliferative effects, lipid metabolism stimulation, and anti-inflammatory activity, which suggest that they could be beneficial for the treatment of a variety of cutaneous diseases. Hyaluronan (HA), a high-molecular-weight linear glycosaminoglycan consisting of alternating D: -glucuronic acid and N-acetyl-D: -glucosamine residues, is one of the major extracellular matrix components in skin. Among the family of HA synthase genes (HAS1, 2, 3) so far identified, one group has demonstrated that the expressions of HAS2 and HAS3 play crucial roles in the regulation of HA synthesis in human skin fibroblasts and keratinocytes, respectively, but the precise regulatory mechanisms are still unknown. We examine Musk T called Ethylene brassylate, Astratone or 1,4-Dioxacycloheptadecane-5,17-dione, which used as just a perfume ingredient, plays a role as PPAR-alpha ligand in vitro and stimulates skin barrier recovery, ceramide synthesis, beta-Glucocerebrosidase, involucrin expression in epidermis in vivo; and examine that Musk T stimulates HAS expression and HA synthesis in human skin fibroblast. Through these experiments, we conclude that Musk T is PPAR-alpha ligand, effects on keratinocyte differentiation, intercellular lipid synthesis in epidermis, HA synthesis stimulation in dermis.