Female sex hormone stimulates cultured human keratinocyte proliferation and its RNA- and protein-synthetic activities

Delivery of Bioactive Compounds to Improve Skin Cell Responses on Microfabricated Electrospun Microenvironments

The introduction of microtopographies within biomaterial devices is a promising approach that allows one to replicate to a degree the complex native environment in which human cells reside. Previously, our group showed that by combining electrospun fibers and additive manufacturing it is possible to replicate to an extent the stem cell microenvironment (rete ridges) located between the epidermal and dermal layers. Our group has also explored the use of novel proangiogenic compounds to improve the vascularization of skin constructs. Here, we combine our previous approaches to fabricate innovative polycaprolactone fibrous microtopographical scaffolds loaded with bioactive compounds (2-deoxy-D-ribose, 17β-estradiol, and aloe vera). Metabolic activity assay showed that microstructured scaffolds can be used to deliver bioactive agents and that the chemical relation between the working compound and the electrospinning solution is critical to replicate as much as possible the targeted morphologies. We also reported that human skin cell lines have a dose-dependent response to the bioactive compounds and that their inclusion has the potential to improve cell activity, induce blood vessel formation and alter the expression of relevant epithelial markers (collagen IV and integrin β1). In summary, we have developed fibrous matrixes containing synthetic rete-ridge-like structures that can deliver key bioactive compounds that can enhance skin regeneration and ultimately aid in the development of a complex wound healing device.

Xenobiotic Receptors and Their Mates in Atopic Dermatitis

Atopic dermatitis (AD) is the most common inflammatory skin disease worldwide. It is a chronic, relapsing and pruritic skin disorder which results from epidermal barrier abnormalities and immune dysregulation, both modulated by environmental factors. AD is strongly associated with asthma and allergic rhinitis in the so-called 'atopic march.' Xenobiotic receptors and their mates are ligand-activated transcription factors expressed in the skin where they control cellular detoxification pathways. Moreover, they regulate the expression of genes in pathways involved in AD in epithelial cells and immune cells. Activation or overexpression of xenobiotic receptors in the skin can be deleterious or beneficial, depending on context, ligand and activation duration. Moreover, their impact on skin might be amplified by crosstalk among xenobiotic receptors and their mates. Because they are activated by a broad range of endogenous molecules, drugs and pollutants owing to their promiscuous ligand affinity, they have recently crystalized the attention of researchers, including in dermatology and especially in the AD field. This review examines the putative roles of these receptors in AD by critically evaluating the conditions under which the proteins and their ligands have been studied. This information should provide new insights into AD pathogenesis and ways to develop new therapeutic interventions.

How hormones may modulate human skin pigmentation in melasma: An in vitro perspective

Melasma is a common acquired hyperpigmentary disorder occurring primarily in photo-exposed areas and mainly affecting women of childbearing age. To decipher the role of sex hormones in melasma, this viewpoint reviews the effects of sex hormones on cutaneous cells cultured in monolayers, in coculture, in 3D models and explants in the presence or the absence of UV. The data show that sex steroid hormones, especially oestrogen, can modulate in vitro pigmentation by stimulating melanocytes and keratinocyte pro-pigmentary factors, but not via fibroblast or mast cell activation. In vitro data suggest that oestrogen acts on endothelial cell count, which may in turn increase endothelin-1 concentrations. However, data on explants revealed that sex steroid even at doses observed during pregnancy cannot induce melanogenesis alone nor melanosome transfer but that it acts in synergy with UVB. In conclusion, we hypothesize that in predisposed persons, sex steroid hormones initiate hyperpigmentation in melasma by amplifying the effects of UV on melanogenesis via direct effects on melanocytes or indirect effects via keratinocytes and on the transfer of melanosomes. They also help to sustain hyperpigmentation by increasing the number of blood vessels and, in turn, the level of endothelin-1.

The relationship between menopausal hormone therapy and keratinocyte carcinoma: A review

Introduction

Keratinocyte carcinoma (KC) is the most common malignancy in the United States. The two most common forms of KC are basal cell carcinoma and squamous cell carcinoma (SCC), which account for 80% and 20% of cases, respectively.

Objective

There are many well-established risk factors for KC, but a more controversial risk factor for KC development is menopausal hormone therapy (MHT). This review synthesizes existing information on this topic and identifies knowledge gaps for future study.

Methods

A systematic review of the literature using the Medical Subject Headings terms “menopausal hormone therapy; skin neoplasms” was conducted in the PubMed database from March 19, 2018 to April 1, 2018. This yielded 168 articles, case reports, and reviews, which were further refined for inclusion during the development of this manuscript. Additional articles were identified from cited references.

Results

Four studies pertaining to this topic were identified. The results were evaluated in the context of these studies’ strengths and weaknesses. MHT contributes to an increased risk of basal cell carcinoma in Caucasian subjects and may make these tumors histologically more aggressive. There is not enough evidence to make a conclusion with regard to a potential relationship between MHT and SCC. However, one study suggested an increased risk of SCC with MHT use and another demonstrated a temporal association with prolonged MHT use and increased risk of SCC development.

Conclusion

Ever users of MHT should be screened more frequently for KC. This issue is of importance to dermatologists because patients who receive earlier diagnoses of KC will have a better opportunity to pursue treatment.

Perceived age is associated with bone status in women aged 25-93 years

Higher perceived age (PA) is reported to be associated with age-related diseases. Because osteoporosis is considered an age-related disease, we hypothesized that age perceived from photographs is associated with bone mineral density (BMD)/trabecular bone score (TBS) when controlled for chronological age. This is a cross-sectional study of 460 women aged 25-93 years. BMD/TBS was measured. Twenty physicians assessed age from facial and whole-body photographs. Residual PA (R(PACA)) was calculated from the regression of PA on chronological age. Participants were divided into "looking old" (LO) or "looking young" (LY). Linear mixed models and general linear models fitted with BMD/TBS as outcome and either R(PACA) or LO/LY as an independent variable, considering chronological age. Estimates of R(PACA) were all negative; i.e., an increase in R(PAC) is associated with lower BMD, consistent with the hypothesis (e.g., β -0.29%; 95% confidence interval (CI) 0.55, 0.03). Statistical significance of the association of age-adjusted facial R(PACA) with BMD was found. Adjusted for body mass index (BMI), menopause, and hormone replacement therapy, higher R(PACA) from all photographic presentations were significantly associated with lower BMD based on statistical significance. BMD/TBS was in all analyses higher in the group LY compared with LO, when adjusted for age and BMI (e.g., β 4.37%; 95 CI 0.62, 8.26), but statistical significance was obtained only from the BMD analyses. A higher PA was significantly associated with a lower BMD/TBD, and the size of association in older women indicates that it might have value as part of the clinical assessment of osteoporotic risk.

Stem cells and aberrant signaling of molecular systems in skin aging

The skin is the body's largest organ and it is able to self-repair throughout an individual's life. With advanced age, skin is prone to degenerate in response to damage. Although cosmetic surgery has been widely adopted to rejuvinate skin, we are far from a clear understanding of the mechanisms responsible for skin aging. Recently, adult skin-resident stem/progenitor cells, growth arrest, senescence or apoptotic death and dysfunction caused by alterations in key signaling genes, such as Ras/Raf/MEK/ERK, PI3K/Akt-kinases, Wnt, p21 and p53, have been shown to play a vital role in skin regeneration. Simultaneously, enhanced telomere attrition, hormone exhaustion, oxidative stress, genetic events and ultraviolet radiation exposure that result in severe DNA damage, genomic instability and epigenetic mutations also contribute to skin aging. Therefore, cell replacement and targeting of the molecular systems found in skin hold great promise for controlling or even curing skin aging.

Skin hydration in postmenopausal women: argan oil benefit with oral and/or topical use

The aim of this study

The aim of this study was to evaluate the effect of daily consumption and/or application of argan oil on skin hydration in postmenopausal women.

Material and methods

Sixty postmenopausal women consumed butter during the stabilization period and were randomly divided into two groups for the intervention period: the treatment group absorbed alimentary argan oil (n = 30) and the control group olive oil (n = 30). Both groups applied cosmetic argan oil in the left volar forearm during a sixty days’ period. Evaluation of skin hydration, i.e. transepidermal water loss (TEWL) and water content of the epidermis (WCE) on both volar forearms of the two groups, were performed during three visits at D0, D30 and after sixty days (D60) of oils treatment.

Results

The consumption of argan oil has led to a significant decrease in TEWL (p = 0.023) and a significant increase in WCE (p = 0.001). The application of argan oil has led to a significant decrease in TEWL (p = 0.01) and a significant increase in WCE (p < 0.001).

Conclusions

Our findings suggest that the daily consumption and application of argan oil have improved the skin hydration by restoring the barrier function and maintaining the water-holding capacity.

Pre-clinical evaluation of soybean-based wound dressings and dermal substitute formulations in pig healing and non-healing in vivo models

In the last decade, a new class of natural biomaterials derived from de-fatted soybean flour processed by either thermoset or extraction procedures has been developed. These biomaterials uniquely combine adaptability to various clinical applications to proven tissue regeneration properties. In the present work, the biomaterials were formulated either as hydrogel or as paste formulation and their potential as wound dressing material or as dermal substitute was assessed by two in vivo models in pig skin: The healing full-thickness punch biopsy model and the non-healing full-thickness polytetrafluoroethylene (PTFE) chamber model. The results clearly show that collagen deposition is induced by the presence of these biomaterials. A unique pattern of early inflammatory response, eliciting neutrophils and controlling macrophage infiltration, is followed by tissue cell colonization of the wound bed with a significant deposition of collagen fibers. The study also highlighted the importance in the use of optimal formulations and appropriate handling upon implantation. In large size, non-healing wounds, wound dermis was best obtained with the paste formulation as hydrogels appeared to be too loose to ensure lasting scaffolding properties. On the contrary, packing of the granules during the application of paste reduced biomaterial degradation rate and prevent the penetration of newly vascularized tissue, thus impeding grafting of split-thickness autologous skin grafts on the dermal substitute base.

Study of progesterone and cortisol concentrations in the Italian Friesian claw

The present research was conducted to study progesterone and cortisol concentrations in the claw of cattle and to verify whether the cattle claw could be considered an efficient matrix to provide retrospective information regarding progesterone and cortisol concentrations related to pregnancy and peripartum periods. These 2 steroids are involved in hoof growth. The study was performed on 32 calves and 24 pregnant milking cows of the Holstein breed, which were clinically healthy and lacking any claw disorders. Samples of at least 0.5cm in thickness were taken from the sole. Progesterone and cortisol concentrations were determined by RIA. The cortisol concentration in the horny shoe of calves from 0 to 30 d of age was significantly higher than the concentration at 31 to 60 and 61 to 120 d of age. Conversely, the progesterone concentration showed no statistically significant difference in relation to age. The horn progesterone concentrations recorded in the milking dairy cows at 7 mo of pregnancy showed high variability in the horizontal sections of the sole (the individual coefficient of variation ranged between 0.09 and 1.11). In 6 cows, genuine extreme values (genuine outliers) of the progesterone level were found. Moreover, significant differences existed among the progesterone concentrations of the sole's transverse sections. We detected a significant positive correlation between the weight of the horn samples after freeze-drying and their weight after hydration. The cortisol and progesterone levels in soaked horn samples were found to be significantly lower than in the same dry samples. These results show that cortisol and progesterone can be measured in the cattle claw horn. The claws of mature dairy cows could not be used as a matrix to provide a retrospective measure of cumulative hormone secretion, whereas the analysis of the calves' claw horns showed retrospective hormonal information similar to hair samples.

Gonadal hormones differently modulate cutaneous wound healing of chronically stressed mice

Gonadal hormones influence physiological responses to stress and cutaneous wound healing. The aim of this study was to investigate the role of gonadal hormones on cutaneous wound healing in chronically stressed mice. Male and female mice were gonadectomized, and after 25 days, they were spun daily at 115 rpm for 15 min every hour until euthanasia. Twenty-eight days after the gonadectomy, an excisional lesion was created. The animals were killed 7 or 14 days after wounding, and the lesions were collected. Myofibroblast density, macrophage number, catecholamine level, collagen deposition, and blood vessel number were evaluated. In the intact and gonadectomized groups, stress increased the plasma catecholamine levels in both genders. In intact groups, stress impaired wound contraction and re-epithelialization and increased the macrophage number in males but not in females. In addition, stress compromised myofibroblastic differentiation and blood vessel formation and decreased collagen deposition in males but not in females. In contrast to intact mice, wound healing in ovariectomized female mice was affected by stress, while wound healing in castrated male mice was not. In conclusion, gender differences contribute to the cutaneous wound healing of chronically stressed mice. In addition, androgens contribute to the stress-induced impairment of the healing of cutaneous wounds but estrogens inhibit it.

Hormonal therapy of intrinsic aging

Intrinsic skin aging represents the biological clock of the skin cells per se and reflects the reduction processes that are common in internal organs. The reduced secretion of the pituitary, adrenal glands, and the gonads contributes to characteristic aging-associated body and skin phenotypes as well as behavior patterns. Our knowledge of whether there is a direct or indirect connection between hormonal deficiency and skin aging still remains limited. In females, serum levels of 17β-estradiol, dehydroepiandrosterone, progesterone, growth hormone (GH), and its downstream hormone insulin-like growth factor I (IGF-I) are significantly decreased with increasing age. In males, serum levels of GH and IGF-I decrease significantly, whereas it can decrease in late age in a part of the population. Hormones have been shown to influence skin morphology and functions, skin permeability, wound healing, sebaceous lipogenesis, and the metabolism of skin cells. Prevention of skin aging by estrogen/progesterone replacement therapy is effective if administered early after menopause and influences intrinsically aged skin only. Vitamin D substitution and antioxidant treatment may also be beneficial. Replacement therapy with androgens, GH, IGF-I, progesterone, melatonin, cortisol, and thyroid hormones still remains controversial.

Estrogen and skin: therapeutic options

Aging of the skin is associated with skin thinning, atrophy, dryness, wrinkling, and delayed wound healing. These undesirable aging effects are exacerbated by declining estrogen levels in postmenopausal women. With the rise in interest in long-term postmenopausal skin management, studies on the restorative benefits that estrogen may have on aged skin have expanded. Systemic estrogen replacement therapy (ERT) has been shown to improve some aspects of skin. Estrogen restores skin thickness by increasing collagen synthesis while limiting excessive collagen degradation. Wrinkling is improved following estrogen treatment since estrogen enhances the morphology and synthesis of elastic fibers, collagen type III, and hyaluronic acids. Dryness is also alleviated through increased water-holding capacity, increased sebum production, and improved barrier function of the skin. Furthermore, estrogen modulates local inflammation, granulation, re-epithelialization, and possibly wound contraction, which collectively accelerates wound healing at the expense of forming lower quality scars. Despite its promises, long-term ERT has been associated with harmful systemic effects. In the search for safe and effective alternatives with more focused effects on the skin, topical estrogens, phytoestrogens, and tissue-specific drugs called selective estrogen receptor modulators (SERMs) have been explored. We discuss the promises and challenges of utilizing topical estrogens, SERMs, and phytoestrogens in postmenopausal skin management.

The role of estrogen-metabolizing enzymes and estrogen receptors in human epidermis

Local estrogen metabolism and its sensitivities in the skin have been also suggested to contribute to skin homeostasis in addition to age- and/or gender-dependent circulating estrogen, even though their local mechanisms have been largely unknown. To characterize their potential correlations, age- and gender-dependencies were evaluated focusing on 5 pivotal estrogen-metabolizing enzymes including aromatase, estrogen sulfotransferase, steroid sulfatase, and 17β-hydroxysteroid dehydrogenases and estrogen receptors (ERα and ERβ) using immunohistochemistry of 100 human skin specimens. When their epidermal expression levels were compared among 7 age groups, ranging from the teens to the seventies, the highest expression in the teens group and the lowest expression in the seventies group were found in the expression of aromatase and ERβ, respectively, while no significant differences between the male and the female groups were found in the immunoreactivities of our interested proteins. Our results suggest that age-related differences in aromatase and ERβ expressions impact epidermal homeostasis.

Oral contraceptives: a risk factor for squamous cell carcinoma?

Oral contraceptives (OCs) affect the risk of several cancers in women, but have been virtually unstudied for squamous cell carcinoma (SCC). We examined the hypothesis that OCs influence SCC risk in a case-control study among women and also examined whether polymorphisms in the DNA repair gene, Xeroderma pigmentosum group D (XPD), modified the risk. Incident cases of SCC were identified by a network of dermatologists and pathology laboratories. Population-based controls were frequency matched to cases by age and gender (n=261 SCC cases, 298 controls). Overall, OC use was associated with a 60% higher risk of SCC (odds ratio (OR), 1.6; 95% confidence interval (95% CI): 1.0-2.5). ORs for SCC were higher among those who last used OCs > or =25 years before diagnosis (OR: 2.1; 95% CI: 1.2-3.7), and among these women, SCC risk increased with duration of use (OR for < or =2 years, 1.7; 95% CI: 0.9-3.5; OR for 3-6 years, 2.6; 95% CI: 1.0-6.5; OR for > or =7 years, 2.7; 95% CI: 0.9-8.5, P(trend)=0.01). Furthermore, the XPD Lys751Gln polymorphism was a significant modifier of the OC-SCC association (P(interaction)=0.03). These findings lead us to hypothesize a potential relationship between OCs and SCC risk, and that this could involve DNA repair pathways.

Novel effects of diosgenin on skin aging

Extracts of Dioscorea coomposita or Dioscorea villosa are consumed as supplemental health foods at the time of climacteric. The extracts contain large amounts of the plant steroid, diosgenin. Here, we studied the safety and efficacy of diosgenin against skin aging at the time of climacteric. In vitro, diosgenin enhanced DNA synthesis in a human 3D skin equivalent model, and increased bromodeoxyuridine uptake and intracellular cAMP level in adult human keratinocytes. The increase of bromodeoxyuridine uptake by diosgenin was blocked by an adenylate cyclase inhibitor, but not by antisense oligonucleotides against estrogen receptor alpha, estrogen receptor beta or an orphan G-protein-coupled receptor, GPR30, indicating the involvement of cAMP but not estrogen receptor alpha, estrogen receptor beta or GPR30. In vivo, administration of diosgenin improved the epidermal thickness in the ovariectomized mice, a climacteric model, without altering the degree of fat accumulation. In order to examine the safety of diosgenin, diosgenin and 17beta-estradiol were administered to breast cancer-burdened mice. The results revealed that while 17beta-estradiol accelerated the tumor growth, diosgenin did not show this effect. Our finding, a restoration of keratinocyte proliferation in aged skin, suggests that diosgenin may have potential as a safe health food for climacteric.

Aldo-keto reductase 1C subfamily genes in skin are UV-inducible: possible role in keratinocytes survival

Please cite this paper as: Aldo-keto reductase 1C subfamily genes in skin are UV-inducible: possible role in keratinocytes survival. Experimental Dermatology 2009; 18: 611-618.Abstract: Human skin is endowed with the capacity to synthesize and metabolize steroid hormones, a function of importance in skin physiology and pathology. It is the hormone-regulatory enzymes, including the aldo-keto reductase 1C subfamily (AKR1Cs) that are largely responsible for the local levels of active steroid hormones. AKR1C1 and AKR1C2 inactivate progesterone and 5alpha-dihydrotestosterone, respectively, whereas AKR1C3 activates oestradiol and testosterone. Here, we show that AKR1C1-3 are expressed in keratinocytes and fibroblasts, with marginal expression in melanocytes. In human primary keratinocytes, AKR1C1 and -2 were UVB-inducible in a dose-dependent manner, as shown by quantitative PCR and Western blot analyses. The induction of AKR1C1 by UVB was concomitant with the presence of an apoptotic marker, the cleavage product of poly-ADP ribose polymerase. Similarly, the activation of AKR1C1 and -2 upon UVB exposure was demonstrated in swine skin in vivo and in human skin explants. As expected, hydrogen peroxide-derived reactive oxygen species also induced AKR1C1 and -2 mRNA and protein levels in keratinocytes in a dose-dependent manner. Furthermore, down-regulation of AKR1Cs by small interfering ribonucleic acid led to significantly reduced cell viability. Based on the combined evidence of the presence of an apoptotic marker in the UVB-exposed keratinocytes with increased AKR1Cs expression and reduced cell viability in down-regulated AKR1Cs, we suggest that AKR1C subfamily genes are stress-inducible and might function as survival factors in keratinocytes.

A prospective, randomized, double-blind, placebo-controlled study on the influence of a hormone replacement therapy on skin aging in postmenopausal women

BACKGROUND

There is mounting evidence that menopause affects some functions of the skin. Hormone replacement therapy (HRT) appears to limit some of the climacteric aspects of cutaneous aging.

OBJECTIVE

In the light of a growing interest in the endocrinological influence of skin, we performed a study evaluating the effects of HRT on skin aging in postmenopausal women.

METHODS

Forty non-hysterectomized, postmenopausal women were included in this prospective, randomized, double-blind, placebo-controlled study on the influence of oral sequential treatment with a combination of 2 mg 17beta-estradiol/10 mg dydrogesterone (Femoston) for seven 28-day cycles. Skin elasticity, skin surface lipids, skin hydration and skin thickness were measured by non-invasive methods, and both adverse-event profile and clinical-dermatological status were evaluated.

RESULTS

After 7 months of HRT, skin elasticity increased significantly at the right ramus of the mandible, while skin hydration tended to improve significantly at the right upper arm (inner side); skin thickness improved significantly but skin surface lipids did not. Absolute effects did not differ significantly between HRT and placebo patients. A dermatological evaluation was largely consistent with measurement results. Safety and tolerability of HRT were positive.

CONCLUSION

The results showed improvements in the parameters involved in skin aging in the HRT group as compared to baseline. While skin aging is no indication for systemic hormone supplementation, a positive effect on aging skin can be observed.

Use of an in vitro model of tissue-engineered skin to investigate the mechanism of skin graft contraction

Skin graft contraction leading to loss of joint mobility and cosmetic deformity remains a major clinical problem. In this study we used a tissue-engineered model of human skin, based on sterilized human adult dermis seeded with keratinocytes and fibroblasts, which contracts by up to 60% over 28 days in vitro, as a model to investigate the mechanism of skin contraction. Pharmacologic agents modifying collagen synthesis, degradation, and cross-linking were examined for their effect on contraction. Collagen synthesis and degradation were determined using immunoassay techniques. The results show that skin contraction was not dependent on inhibition of collagen synthesis or stimulation of collagen degradation, but was related to collagen remodelling. Thus, reducing dermal pliability with glutaraldehyde inhibited the ability of cells to contract the dermis. So did inhibition of matrix metalloproteinases and inhibition of lysyl oxidase-mediated collagen cross-linking, but not transglutaminase-mediated cross-linking. In summary, this in vitro model of human skin has allowed us to identify specific cross-linking pathways as possible pharmacologic targets for prevention of graft contracture in vivo.

Human skin pigmentation: melanocytes modulate skin color in response to stress

All organisms, from simple invertebrates to complex human beings, exist in different colors and patterns, which arise from the unique distribution of pigments throughout the body. Pigmentation is highly heritable, being regulated by genetic, environmental, and endocrine factors that modulate the amount, type, and distribution of melanins in the skin, hair, and eyes. In addition to its roles in camouflage, heat regulation, and cosmetic variation, melanin protects against UV radiation and thus is an important defense system in human skin against harmful factors. Being the largest organ of the body that is always under the influence of internal and external factors, the skin often reacts to those agents by modifying the constitutive pigmentation pattern. The focus of this review is to provide an updated overview of important physiological and biological factors that increase pigmentation and the mechanisms by which they do so. We consider endocrine factors that induce temporary (e.g., during pregnancy) or permanent (e.g., during aging) changes in skin color, environmental factors (e.g., UV), certain drugs, and chemical compounds, etc. Understanding the mechanisms by which different factors and compounds induce melanogenesis is of great interest pharmaceutically (as therapy for pigmentary diseases) and cosmeceutically (e.g., to design tanning products with potential to reduce skin cancer risk).

Effect of estrogens on skin aging and the potential role of SERMs

In humans, structural and functional changes attributable to aging are more visibly evident in the skin than in any other organ. Estrogens have significant effects on skin physiology and modulate epidermal keratinocytes, dermal fibroblasts and melanocytes, in addition to skin appendages including the hair follicle and the sebaceous gland. Importantly, skin aging can be significantly delayed by the administration of estrogen. This paper reviews the effects of estrogens on skin and the mechanisms by which estrogens can alleviate the changes due to aging that occur in human skin. The relevance of estrogen replacement therapy (HRT) in postmenopausal women and the potential value of selective estrogen receptor modulators (SERMs) as a therapy for diminishing skin aging are also highlighted.

Biology of estrogens in skin: implications for skin aging

Estrogens have a profound influence on skin. The relative hypoestrogenism that accompanies menopause exacerbates the deleterious effects of both intrinsic and environmental aging. Estrogens clearly have a key role in skin aging homeostasis as evidenced by the accelerated decline in skin appearance seen in the perimenopausal years. Estrogens improve skin in many ways. Among these, they increase collagen content and skin thickness and improve skin moisture. However, despite the knowledge that estrogens have such important effects on skin, the cellular and subcellular sites and mechanisms of estrogen action are still poorly understood. Estrogen receptors (ERs) have been detected in skin, and recent studies suggest that estrogens exert their effect in skin through the same molecular pathways used in other non-reproductive tissues. Although systemic hormone replacement therapy (HRT) has been used for many years, recent trials have reported a significant increased risk of breast cancer and other pathologies with this treatment. This has led to reconsider the risks and benefits of HRT. For this reason, systemic HRT cannot be recommended today to treat skin aging. Currently, intensive research is conducted to develop new drugs called selective ER modulators (SERMs). These drugs exert mixed estrogenic and antiestrogenic effects depending on the tissue and cell type. One might expect in the future such a drug targeting specifically the skin without systemic side effects.

Oestrogen functions in skin and skin appendages

Oestrogens have significant effects on different cell types important in skin physiology, including the epidermal keratinocytes, dermal fibroblasts and melanocytes. In addition, they can also modulate skin appendages such as the hair follicle, the sebaceous gland and the apocrine glands. Oestrogens may also have important modulatory roles in events such as skin ageing, pigmentation, hair growth, sebum production and skin cancer. It is now recognised that oestrogens can modulate their actions via two distinct intracellular receptors (ERalpha and ERbeta) or via cell surface receptors, which activate specific second messenger signalling pathways. This paper highlights the effects of oestrogens on different components of the skin and reviews some of the more recent developments in terms of receptor expression and cell signalling pathways.

Regulatory roles of sex hormones in cutaneous biology and immunology

Recent studies have revealed that sex hormones manifest a variety of biological and immunological effects in the skin. Pregnancy, menstruation and the menopause modulate the natural course of psoriasis, indicating a female hormone-induced regulation of skin inflammation. Estrogen in vitro down-regulates the production of the neutrophil, type 1 T cell and macrophage-attracting chemokines, CXCL8, CXCL10, CCL5, by keratinocytes, and suppresses IL-12 production and antigen-presenting capacity while enhancing anti-inflammatory IL-10 production by dendritic cells. These data indicate that estrogen may attenuate inflammation in psoriatic lesions. Estrogen, alone or together with progesterone, prevents or reverses skin atrophy, dryness and wrinkles associated with chronological or photo-aging. Estrogen and progesterone stimulate proliferation of keratinocytes while estrogen suppresses apoptosis and thus prevents epidermal atrophy. Estrogen also enhances collagen synthesis, and estrogen and progesterone suppress collagenolysis by reducing matrix metalloproteinase activity in fibroblasts, thereby maintaining skin thickness. Estrogen maintains skin moisture by increasing acid mucopolysaccharide or hyaluronic acid levels in the dermis. Progesterone increases sebum secretion. Estrogen accelerates cutaneous wound healing stimulating NGF production in macrophages, GM-CSF production in keratinocytes and bFGF and TGF-beta1 production in fibroblasts, leading to the enhancement of wound re-innervation, re-epithelialization and granulation tissue formation. In contrast, androgens prolong inflammation, reduce deposition of extracellular matrix in wounds, and reduce the rate of wound healing. Estrogen enhances VEGF production in macrophages, an effect that is antagonized by androgens and which may be related to the development of granuloma pyogenicum during pregnancy. These regulatory effects of sex steroids may be manipulated as therapeutic or prophylactic measures in psoriasis, aging, chronic wounds or granuloma pyogenicum.

17beta-estradiol stimulates the growth of human keratinocytes by inducing cyclin D2 expression

Estrogen is reported to prevent age-associated epidermal thinning in the skin. We examined if 17beta-estradiol (E2) may enhance the growth of human keratinocytes, focusing on its effects on the expression of cell cycle-regulatory proteins. E2 enhanced proliferation, bromodeoxyuridine incorporation of keratinocytes, and increased the proportion of cells in the S phase. The E2-induced stimulation of proliferation and bromodeoxyuridine incorporation was suppressed by antisense oligonucleotide against cyclin D2, which induces G1 to S phase progression. E2 increased protein and mRNA levels of cyclin D2, and resultantly enhanced assembly and kinase activities of cyclin D2-cyclin-dependent kinases 4 or 6 complexes. E2 enhanced cyclin D2 promoter activity, and the element homologous to cAMP response element (CRE) on the promoter was responsible for the effect. Cyclin D2 expression was enhanced by antiestrogens, ICI 182,780 and 4-hydroxytamoxifen, and membrane-impermeable bovine serum albumin-conjugated E2, indicating the effects via membrane E2-binding sites. E2 increased the enhancer activity of CRE-like element and the amount of phosphorylated cAMP response element binding protein (CREB) binding this element, and the increases were suppressed by H-89, an inhibitor of cAMP-dependent protein kinase A. H-89 also suppressed E2-induced cyclin D2 expression, proliferation, and bromodeoxyuridine incorporation in keratinocytes. Antisense oligonucleotide against G-protein-coupled receptor GPR30 suppressed the E2-induced increases of phosphorylated CREB, cyclin D2 level, proliferation, and bromodeoxyuridine incorporation in keratinocytes. These results suggest that E2 may stimulate the growth of keratinocytes by inducing cyclin D2 expression via CREB phosphorylation by protein kinase A, dependent on cAMP. These effects of E2 may be mediated via cell surface GPR30.

Estradiol induces proliferation of keratinocytes via a receptor mediated mechanism

In this study, we investigated the effects of estradiol on the proliferation of neonatal keratinocytes, the expression of estrogen receptor isoforms, and the signaling mechanisms by which estradiol mediates cell growth. We demonstrate that estradiol binds neonatal keratinocytes with high affinity (Kd=5.2nM) and limited capacity (Bmax of 14.2fmol/mg of protein), confirming the presence of estrogen binding sites. Using specific antibodies, we demonstrate that keratinocytes express both estrogen receptor (ER)-alpha and ER-beta. At physiological concentrations, estradiol up-regulates the level of ER-alpha receptors in keratinocytes and induces keratinocyte proliferation. The proliferative effect of estradiol requires the availability of functional estrogen receptors, as it is abrogated by anti-estrogen administration. Estradiol effect on keratinocyte proliferation is most likely mediated in part by activation of a nongenomic, membrane-associated, signaling pathway involving activation of the extracellular signal regulated kinases 1 and 2 and in part by the genomic signaling pathway through activation of nuclear receptors.

17beta-estradiol inhibits oxidative stress-induced apoptosis in keratinocytes by promoting Bcl-2 expression

We examined in vitro effects of 17beta-estradiol on H2O2-induced apoptosis in human keratinocytes. 17beta-estradiol prevented the H2O2-induced apoptosis. H2O2 decreased, whereas 17beta-estradiol increased Bcl-2 protein and mRNA levels in keratinocytes, and H2O2 plus 17beta-estradiol led to basal levels. Overexpression of Bcl-2 protected keratinocytes against H2O2-induced apoptosis, indicating the anti-apoptotic effect of Bcl-2. H2O2 suppressed, whereas 17beta-estradiol enhanced bcl-2 promoter activity, and H2O2 plus 17beta-estradiol led to basal activity. Cyclic adenosine monophosphate (cAMP) response element on bcl-2 promoter was responsible for the effects of 17beta-estradiol and H2O2. Bcl-2 expression was enhanced by membrane-impermeable bovine serum albumin-conjugated 17beta-estradiol, indicating the effects via membrane 17beta-estradiol-binding sites. H2O2 decreased, whereas 17beta-estradiol increased the amount of phosphorylated cAMP response element-binding protein and cAMP response element-dependent transcriptional activity, and H2O2 plus 17beta-estradiol led to basal levels. H-89, an inhibitor of cAMP-dependent protein kinase A, suppressed basal and 17beta-estradiol-induced cAMP response element-binding protein phosphorylation, cAMP response element-dependent transcriptional activity, Bcl-2 expression, and apoptosis resistance. The cAMP analog, dibutyryl cAMP, enhanced cAMP response element-binding protein phosphorylation, cAMP response element-dependent transcriptional activity, Bcl-2 expression, and apoptosis resistance. 17Beta-estradiol increased intracellular cAMP level and protein kinase A activity, whereas these were not altered by H2O2. Keratinocytes expressed mRNA for estrogen receptor beta and guanine nucleotide-binding protein-coupled receptor, GPR30. GPR30 anti-sense oligonucleotide did, but anti-sense estrogen receptor beta did not suppress 17beta-estradiol-induced cAMP signal, cAMP response element-binding protein phosphorylation, Bcl-2 expression, and apoptosis resistance. These results suggest that 17beta-estradiol may enhance Bcl-2 expression and prevent H2O2-induced apoptosis by phosphorylating cAMP response element-binding protein via cAMP/protein kinase A pathway in keratinocytes. These effects of 17beta-estradiol may be mediated via membrane GPR30.

Novel cell lines established from a human myxoid malignant fibrous histiocytoma arising in the uterus

Two cell lines (Nara-H and Nara-F) with different phenotypes were established from a myxoid MFH of the uterus. In vitro, Nara-F grew in sheets showing a storiform arrangement and Nara-H in raised colonies. Although tumors generated in nude mice shared similar morphological features of abundant myxoid tumor in Nara-H and -F, the pleomorphic component was conspicuous in Nara-F. Both cell lines produced hyaluronic-acid but CD44 was expressed only in Nara-H. Estrogen receptor alpha (ER alpha) and progesterone receptor (PgR) were detected in Nara-H. Nara-F was positive for ER beta and PgR. Among hormonal agents, the response to the anti-estrogen tamoxifen was more sensitive than progesterone agents. This report illustrates the characteristics of these newly established cell lines, and presents the possibility of an adjuvant hormonal therapy for MFH.

Regulation of cell growth and HPV genes by exogenous estrogen in cervical cancer cells

Human papillomavirus (HPV) infection is known as the major cause of the development of cervical cancer. The E6 and E7 proteins of oncogenic HPV can play critical roles in immortalization and malignant transformation of cervical epithelial cells. From the previous epidemiologic data, it has been determined that long-term use of oral contraceptives may be a risk factor for cervical cancer. Investigation of the estrogenic and antiestrogenic effects on the proliferation of cervical cancer cells and the gene expression of HPV would help to explain the role of estrogen in the HPV-associated pathogenesis of cervical cancer. In this study, cervical cancer cells (HeLa, CaSki, and C33A) were cultured in vitro in the presence of 17beta-estradiol or tamoxifen to observe their regulatory growth effect and HPV E6/E7 gene expression. The estrogenic effect on the promoter activity of HPV URR was further confirmed by transient transfection assay, which was conducted in C33A cells using the HPV-18 URR-CAT reporter plasmid. The supplemental effect of estrogen receptors on URR promoter activity was also evaluated. The proliferation of HeLa and CaSki cells was stimulated by estradiol at physiologic concentration levels (</=1 x 10-6 M). At a low concentration (0.1 x 10-6 M), tamoxifen also stimulated the proliferation of HeLa and CaSki cells. In contrast to HPV-positive cervical cells, the proliferation of C33A was not influenced by exogenous estradiol or tamoxifen, indicating that HPV might play a role in the hormonal stimulation of cell growth. Interestingly, the proliferation of HeLa was markedly suppressed at high concentrations of estradiol and tamoxifen (5 and 10 x 10-6 M). The levels of HPV-18 E6 and E7 mRNA were significantly increased by estradiol at a concentration of 0.5 x 10-6 M. Transient transfection experiments using the HPV URR-CAT reporter plasmid in C33A cells indicated that the expression of HPV E6/E7 genes was increased by the treatment of estradiol and tamoxifen. Co-transfection of estrogen receptors (ER) and URR-CAT leads to a fourfold increase in CAT activity by estradiol or tamoxifen at physiologic concentrations. When estradiol or tamoxifen was administered at high concentrations (5 x 10-6 M), a DNA ladder, typically indicative of apoptosis, was observed in HeLa cells. In conclusion, estradiol stimulated the growth of HPV-positive cervical cancer cells, as did tamoxifen at low concentrations (0.1 x 10-6 M). The growth stimulation of HPV-positive cervical cancer cells by estrogen appeared to be related to the increased expression of HPV E6/E7. Growth suppression observed at high concentrations of estradiol and tamoxifen in HeLa cells might be a result of apoptosis. Taken together, these data suggested that exogenous estradiol might be a risk factor in HPV-mediated cervical carcinogenesis.

17beta-hydroxysteroid dehydrogenases: physiological roles in health and disease

Androgens and estrogens play crucial roles in the growth and development of sex organs. Interconversion of these hormones between biologically active and inactive forms is catalyzed by 17beta-hydroxysteroid dehydrogenase (17beta-HSD) isozymes. Aberrations in the regulation or expression of the various 17beta-HSD isoforms has been implicated in the genesis/progression of hormonally dependent cancers of various tissues, including ovary, breast and prostate; in the predisposition of women with upper body obesity to several types of diseases, such as non-insulin dependent diabetes mellitus; and in the abnormal development of sexually ambiguous individuals, as seen in 17beta-HSD-deficient male pseudohermaphrodites. Of the five known 17beta-HSD isozymes, deleterious mutations in the type 3 isoform were found to give rise to male pseudohermaphroditism. The 16 mutations characterized to date include 12 missense mutations, three splice junction mutations, and one small deletion that results in a downstream premature stop codon. 17beta-HSD has also been studied in other species. The most notable species difference observed is the placental expression in humans of the 17beta-HSD type 1 isoform.

1,25-dihydroxyvitamin D3 regulates estrogen metabolism in cultured keratinocytes

Local estrogen metabolism may play an important role in modulating cell development in peripheral tissues such as breast, adipose, and bone. C19 androgens are converted to C18 estrogens by the enzyme aromatase, overexpression of which is associated with breast cancer. Interconversion of active estradiol (E2) to inactive estrone is controlled by various isoforms of the enzyme 17beta-hydroxysteroid dehydrogenase (17betaHSD). We have studied the expression of these two enzymes in human keratinocytes and report rapid changes in 17betaHSD activity in response to treatment with 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]. Keratinocytes cultured in serum-free medium showed aromatase activity of 2.5 fmol/h x mg cell protein, which was unaffected by any culture treatment. A much higher level of 17betaHSD activity was observed in the keratinocytes, predominantly conversion of E2 to estrone (approximately 120 pmol/h x mg cell protein). This inactivation of E2 increased in a dose-dependent fashion after treatment of the cells with antiproliferative doses of 1,25-(OH)2D3 (0.1-200 nM). The effect of 1,25-(OH)2D3 on 17betaHSD activity was enhanced by simultaneous treatment with dexamethasone, which also increased the antiproliferative action of 1,25-(OH)2D3. Reverse transcription-PCR and Northern analysis showed that keratinocytes expressed messenger RNA for three 17betaHSD isoenzymes (types I, II, and IV). Treatment with 1,25-(OH)2D3 (10 nM for 20 h) resulted in the up-regulation of messenger RNA levels for type 2 17betaHSD. Further RNA studies combined with E2 binding experiments demonstrated the presence of estrogen receptors in the cultured keratinocytes. These data indicate that keratinocytes are potential targets for systemically or locally produced estrogens, which may, in turn, play a key role in the development of normal skin. In particular, we propose that 17betaHSD isoenzymes are key target genes for 1,25-(OH)2D3 in keratinocytes and may be an important feature of the antipsoriatic effects of vitamin D and its analogs.