Low environmental humidity induces synthesis and release of cortisol in an epidermal organotypic culture system

Characterization of Mucosal Immune-Related lncRNAs and mRNAs in a Mouse Model of Allergic Conjunctivitis

Background

Allergic conjunctivitis (AC) is a common inflammatory condition characterized by immune dysregulation in response to environmental allergens. Despite extensive research into general allergic mechanisms, the specific immunological features of the ocular mucosal microenvironment remain poorly understood. Investigating immune-related mRNAs and LncRNAs may provide insights into the mechanisms underlying AC and potential novel targets for therapeutic intervention.

Methods

An AC model was established using female BALB/c mice sensitized with ragweed pollen. Conjunctival tissues from AC and control groups were pooled for RNA extraction, followed by Illumina sequencing. Differential gene expression was identified using DESeq2, and functional enrichment was analyzed using GO, KEGG, and GSEA. RT-qPCR validated results, while the Human Protein Atlas was used to assess protein expression.

Results

A murine model of AC was successfully established, confirmed by progressively increasing clinical scores and significantly elevated scratching frequency. Transcriptomic analysis revealed significant differences in mRNAs and lncRNAs expression between AC and control groups. GO analysis indicated that both upregulated and downregulated genes were enriched in biological processes related to response to stimulus, immune system processes, signaling, and metabolic processes. KEGG analysis showed that upregulated genes were enriched in pathways such as steroid hormone biosynthesis, histidine metabolism, glycolysis/gluconeogenesis, and IL-17 signaling, while downregulated genes were involved in cytokine-cytokine receptor interaction and hematopoietic cell lineage. GSEA identified significant enrichment in inflammatory pathways, including MAPK, STAT1, and STAT2. Mucosal immunity-related genes such as Bpifa1, Lcn2, and Reg3g were upregulated in AC. Co-expression analysis also revealed several upregulated lncRNAs, including Stoml3-202 and Etohd2-205.

Conclusion

This study is the first to systematically analyze immune-related mRNAs and LncRNAs in AC, identifying mucosal immunity molecules like Bpifa1 and Reg3g. These findings underscore the unique involvement of mucosal immunity in AC and provide potential new targets for immune modulation in ocular allergy treatment.

Unveiling the interplay among skin microbiota, cytokines, and T2DM: an insightful Mendelian randomization study

BACKGROUND

Previous observational studies have indicated a correlation between the skin microbiome and Type 2 diabetes (T2DM). It is hypothesized that this causal relationship may be influenced by inflammatory responses. However, these factors as determinants of T2DM remain largely unexplored.

METHOD

This study incorporated data from the GWAS database on the skin microbiome, 91 types of inflammatory cytokines, and T2DM. We employed two-sample MR and multivariable MR methods to assess the correlation between the skin microbiome and T2DM, and to investigate whether this correlation is affected by inflammatory cytokines.

RESULTS

The results of the two-sample MR analysis indicate that within the skin microbiome, genetically predicted genus: Acinetobacter, class: Alphaproteobacteria, genus: Bacteroides, ASV005[Propionibacterium granulosum], and ASV072[Rothia mucilaginosa] are associated with an increased risk of T2DM, while phylum: Proteobacteria, genus: Enhydrobacter, family: Clostridiales, ASV006[Staphylococcus hominis] serve as protective factors against T2DM. Among the inflammatory cytokines, levels of Macrophage colony-stimulating factor 1, Tumor necrosis factor receptor superfamily member 9, Urokinase-type plasminogen activator, and C-C motif chemokine 28 are associated with an increased risk of T2DM. Multivariable MR analysis further revealed that Macrophage colony-stimulating factor 1 levels act as a mediating factor between ASV072[Rothia mucilaginosa] and T2DM.

CONCLUSION

In this study, we found a connection between the skin microbiome and T2DM, with inflammatory cytokines playing a key role in this relationship. This research helps us better understand this complex link and shows that addressing inflammation is important for preventing and treating diabetes. This could greatly benefit public health by reducing the impact of diabetes and its complications. Our results suggest that future studies should explore the specific biological interactions between the skin microbiome and diabetes to develop more effective risk management and treatment strategies from a microbial perspective.

Multi-target mechanisms and potential applications of quercetin in the treatment of acne vulgaris

Acne vulgaris, a prevalent inflammatory dermatosis, afflicts approximately 90% of adolescents globally. Despite the efficacy of conventional therapies, including antibiotics and retinoids, their use is frequently limited by adverse effects and the emergence of drug resistance. Quercetin, a naturally occurring flavonoid, has garnered significant attention owing to its diverse biological activities, encompassing anti-inflammatory, antioxidant, antimicrobial, and immunomodulatory properties. This review comprehensively explores the multi-target mechanisms of quercetin in the treatment of acne, focusing on its ability to modulate inflammatory cytokine production, oxidative stress pathways, sebaceous gland activity, and microbial populations. Additionally, quercetin promotes skin barrier repair and reduces post-inflammatory hyperpigmentation and scarring through its antioxidant and anti-fibrotic effects. Despite promising in vitro and preclinical findings, challenges such as quercetin's low bioavailability and lack of robust clinical evidence necessitate further research. Advanced delivery systems, including nanoparticles and combination therapies, may optimize its therapeutic potential. This review provides insights into the molecular mechanisms and clinical applications of quercetin, highlighting its potential as a safe and effective alternative for acne management.

Skin Disease and Behavior Changes in the Cat

The health of the skin and coat of a cat is connected to the behavioral health of the animal. Stressed animals can cause lesions to their skin and coat such as alopecia, ulcers, and self-mutilation. On the other hand, localized or systemic health problems can cause stress, or pain, and therefore can increase overgrooming and poor skin health. When treating overgrooming and related skin lesions, all the physical and behavioral causes must be addressed through a multimodal approach.

Association of Epidermal Biophysical Properties with Obesity and Its Implications

BACKGROUND

Obesity is a condition defined by an excess amount of body fat, with body mass index (BMI) of 30 and higher. It is associated with a number of other medical conditions, including insulin resistance, diabetes mellitus, and cardiovascular diseases, as well as dyslipidemia, and it is also associated with several cutaneous disorders such as atopic dermatitis, psoriasis, intertriginous dermatitis, acanthosis nigricans and skin infections.

SUMMARY

Evidence suggests a link between obesity and epidermal dysfunction. Generally, individuals with obesity display higher transepidermal water loss rate and lower stratum corneum hydration levels, although no association of obesity with epidermal dysfunction has been documented. Results of skin surface pH are controversial. But study demonstrated a positive correlation of BMI with skin surface pH on both the forearm and the shin in males, suggesting that the changes in epidermal function vary with gender in individuals with obesity.

KEY MESSAGES

This review summarizes the association between obesity and epidermal function, and discusses possible underlying mechanisms. Individuals with obesity exhibit poor epidermal permeability barrier and lower stratum corneum hydration levels. Because of the pathogenic role of compromised epidermal function in inflammation, which is also linked to obesity, improvement in epidermal function could benefit individuals with obesity, particularly those with abnormalities in epidermal function.

Do epidermal keratinocytes have sensory and information processing systems?

It was long considered that the role of epidermal keratinocytes is solely to construct a water-impermeable protective membrane, the stratum corneum, at the uppermost layer of the skin. However, in the last two decades, it has been found that keratinocytes contain multiple sensory systems that detect environmental changes, including mechanical stimuli, sound, visible radiation, electric fields, magnetic fields, temperature and chemical stimuli, and also a variety of receptor molecules associated with olfactory or taste sensation. Moreover, neurotransmitters and their receptors that play crucial roles in the brain are functionally expressed in keratinocytes. Recent studies have demonstrated that excitation of keratinocytes can induce sensory perception in the brain. Here, we review the sensory and information processing capabilities of keratinocytes. We discuss the possibility that epidermal keratinocytes might represent the earliest stage in the development of the brain during the evolution of vertebrates.

The significance of CYP11A1 expression in skin physiology and pathology

CYP11A1, a member of the cytochrome P450 family, plays several key roles in the human body. It catalyzes the first and rate-limiting step in steroidogenesis, converting cholesterol to pregnenolone. Aside from the classical steroidogenic tissues such as the adrenals, gonads and placenta, CYP11A1 has also been found in the brain, gastrointestinal tract, immune systems, and finally the skin. CYP11A1 activity in the skin is regulated predominately by StAR protein and hence cholesterol levels in the mitochondria. However, UVB, UVC, CRH, ACTH, cAMP, and cytokines IL-1, IL-6 and TNFα can also regulate its expression and activity. Indeed, CYP11A1 plays several critical roles in the skin through its initiation of local steroidogenesis and specific metabolism of vitamin D, lumisterol, and 7-dehydrocholesterol. Products of these pathways regulate the protective barrier and skin immune functions in a context-dependent fashion through interactions with a number of receptors. Disturbances in CYP11A1 activity can lead to skin pathology.

The role of the microbiome in diabetes mellitus

The microbiome is greatly significant for immune system development and homeostasis. Dysbiosis in gut microbial composition and function is linked to immune responses and the development of metabolic diseases, including diabetes mellitus (DM). However, skin microbiome changes in diabetic patients and their role in DM are poorly elucidated. In this review, we summarize recent findings about the association between the gut and skin microbiota and DM, highlighting their roles in the proinflammatory status of DM. Moreover, although there is evidence that the connection between the gut and skin causes the same activated innate immune response, additional studies are needed to explore the mechanism. These findings might inform future DM prevention, diagnosis and treatment.

Attenuated Activation of Homeostatic Glucocorticoid in Keratinocytes Induces Alloknesis via Aberrant Artemin Production

Intense chronic itch significantly reduces quality of life for atopic dermatitis patients, impairing daily activity. Although abnormal itch sensation can be induced by innocuous stimuli, known as alloknesis, the mechanisms driving this process remain obscure. Psychological and environmental stimuli are known to aggravate atopic dermatitis symptoms. Recently, the enzyme 11β-hydroxysteroid dehydrogenase-1 (HSD11β1), which is expressed in keratinocytes, has been implicated in maintaining homeostasis against environmental stimuli by activating endogenous glucocorticoids. To investigate the role of HSD11β1 in keratinocytes, we generated keratinocyte-specific Hsd11b1-knockout (Hsd11b1^KC-/-) mice and analyzed skin phenotype. Hsd11b1^KC-/- mice exhibited abnormal cutaneous innervation and skin sensitivity, including light mechanical stimulus-evoked itch (i.e., alloknesis). Attenuated endogenous glucocorticoid activation induced by aberrant artemin production in keratinocytes was involved in alloknesis in Hsd11b1^KC-/- mice. Finally, we observed a significant negative correlation between expression of HSD11β1 and artemin in human skin with and without AD. These results suggest that endogenous glucocorticoids that maintain skin homeostasis in the epidermis affect both skin innervation and cutaneous sensation. Modulation of HSD11β1 activation could be a therapeutic target for sensitive or itchy skin.

Association between Stress and the HPA Axis in the Atopic Dermatitis

The hypothalamic–pituitary–adrenal (HPA) axis is one of the body’s neuroendocrine networks that responds to psychological stress (PS). In the skin, there exists a peripheral HPA axis similar to the central axis. Glucocorticoids (GCs) are key effector molecules of the HPA axis and are essential for cutaneous homeostasis. Atopic dermatitis (AD) is a condition typically characterized by a chronic relapsing course that often results in PS. HPA dysfunction is present in AD patients by the decreased response of GCs elevation to stress as compared to those unaffected by AD. Nevertheless, in skin, acute PS activates several metabolic responses that are of immediate benefit to the host. During the acute phase of PS, increased endogenous GCs have been shown to provide benefit rather than by aggravating cutaneous inflammatory dermatoses. However, a chronic T helper cell type 2 (Th2) predominant cytokine profile acts as a negative feedback loop to blunt the HPA axis response in AD. In this article, we reviewed the role of CRF, pro-opiomelanocortin (POMC)-derived peptides, GCs of the HPA, and 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) in AD, with a discussion of the pathogenetic mechanisms of inflammation and skin barrier functions, including antimicrobial defense, and their association with PS.

The skin microbiome: impact of modern environments on skin ecology, barrier integrity, and systemic immune programming

Skin barrier structure and function is essential to human health. Hitherto unrecognized functions of epidermal keratinocytes show that the skin plays an important role in adapting whole-body physiology to changing environments, including the capacity to produce a wide variety of hormones, neurotransmitters and cytokine that can potentially influence whole-body states, and quite possibly, even emotions. Skin microbiota play an integral role in the maturation and homeostatic regulation of keratinocytes and host immune networks with systemic implications. As our primary interface with the external environment, the biodiversity of skin habitats is heavily influenced by the biodiversity of the ecosystems in which we reside. Thus, factors which alter the establishment and health of the skin microbiome have the potential to predispose to not only cutaneous disease, but also other inflammatory non-communicable diseases (NCDs). Indeed, disturbances of the stratum corneum have been noted in allergic diseases (eczema and food allergy), psoriasis, rosacea, acne vulgaris and with the skin aging process. The built environment, global biodiversity losses and declining nature relatedness are contributing to erosion of diversity at a micro-ecological level, including our own microbial habitats. This emphasises the importance of ecological perspectives in overcoming the factors that drive dysbiosis and the risk of inflammatory diseases across the life course.

Dysfunctional Skin-Derived Glucocorticoid Synthesis Is a Pathogenic Mechanism of Psoriasis

Glucocorticoids (GC) are the primary steroids that regulate inflammation and have been exploited therapeutically in inflammatory skin diseases. Despite the broad-spectrum therapeutic use of GC, the biochemical rationale for locally treating inflammatory skin conditions is poorly understood, as systemic GC production remains largely functional in these patients. GC synthesis has been well characterized in healthy skin, but the pathological consequence has not been examined. Here we show de novo GC synthesis, and GC receptor expression is dysfunctional in both nonlesional and lesional psoriatic skin. Use of GC receptor epidermal knockout mice with adrenalectomy allowed for the distinction between local (keratinocyte) and systemic GC activity. Compensation exhibited by adult GC receptor epidermal knockout mice demonstrated that keratinocyte-derived GC synthesis protected skin from topical phorbol 12-myristate 13-acetate-induced inflammatory assault. Thus, localized de novo GC synthesis in skin is essential for controlling inflammation, and loss of the GC pathway in psoriatic skin represents an additional pathological process in this complex inflammatory skin disease.

Cortisol Homeostasis in the Epidermis is Influenced by Topical Corticosteroids in Patients with Atopic Dermatitis

Background:

The skin produces cortisol by itself and regulates its own proliferation and differentiation. There is a possibility that topical corticosteroids (TCSs) influence the cortisol homeostasis in the skin.

Aims and Objectives:

The author described the density and distribution of cortisol and its parties in the epidermis after application of topical steroids immunohistologically.

Materials and Methods:

The forearm skin was biopsied before and after 2 weeks’ application of clobetasol propionate 0.05% two times a day in one healthy volunteer. The biopsied skin was stained immunohistologically by ant-MLN64, StAR, CPY11A1, cortisol, HSD11B1, HSD11B2, glucocorticoid receptor alpha, glucocorticoid receptor beta (GRB), and mineralocorticoid receptor (MCR) antibodies. The skin biopsy was performed similarly in 19 adult patients with atopic dermatitis who had used TCS for a considerable period. They were 4 TCS present users (TCS+), 12 TCS nonusers with skin manifestation on the biopsied site (TCS-E+) and 3 TCS nonusers without skin manifestation on the biopsied site (TCS-E−).

Results:

The staining density increased during TCS application in MLN64, cortisol and HSD11B2 in a healthy volunteer. The staining density was stronger in HSD11B2 of the basal layer and MCR of the spinous layer in the TCS-E+ patients than in the TCS+ and TCS-E− patients. The staining density was weaker in MLN64 of the basal and granular layers, HSD11B1 of the basal layer and GRB of the whole layer in the TCS-E+ patients than in the TCS+ and TCS-E− patients.

Conclusion:

The hypertrophy of the epidermis and insufficient keratinization recognized in the TCS-E+ patients might be caused by the decreased cortisol synthesis regulated by MLN64 and the increased cortisol inactivation by HSD11B2. Decreased GRB and increased MCR might enhance the reactivity of cortisol in the keratinocytes.

Keratinocytes at the uppermost layer of epidermis might act as sensors of atmospheric pressure change

It has long been suggested that climate, especially atmospheric pressure change, can cause health problems ranging from migraine to myocardial infarction. Here, I hypothesize that the sensory system of epidermal keratinocytes mediates the influence of atmospheric pressure change on the human physiological condition. We previously demonstrated that even subtle changes of atmospheric pressure (5–20 hPa) induce elevation of intracellular calcium level in cultured human keratinocytes (excitation of keratinocytes). It is also established that communication occurs between epidermal keratinocytes and peripheral nerve systems. Moreover, various neurotransmitters and hormones that influence multiple systems (nervous, cardiovascular, endocrine, and immune systems) are generated and released from epidermal keratinocytes in response to various external stimuli. Thus, I suggest that pathophysiological phenomena induced by atmospheric pressure changes might be triggered by epidermal keratinocytes.

Storage Temperature Alters the Expression of Differentiation-Related Genes in Cultured Oral Keratinocytes

Purpose

Storage of cultured human oral keratinocytes (HOK) allows for transportation of cultured transplants to eye clinics worldwide. In a previous study, one-week storage of cultured HOK was found to be superior with regard to viability and morphology at 12°C compared to 4°C and 37°C. To understand more of how storage temperature affects cell phenotype, gene expression of HOK before and after storage at 4°C, 12°C, and 37°C was assessed.

Materials and Methods

Cultured HOK were stored in HEPES- and sodium bicarbonate-buffered Minimum Essential Medium at 4°C, 12°C, and 37°C for one week. Total RNA was isolated and the gene expression profile was determined using DNA microarrays and analyzed with Partek Genomics Suite software and Ingenuity Pathway Analysis. Differentially expressed genes (fold change > 1.5 and P < 0.05) were identified by one-way ANOVA. Key genes were validated using qPCR.

Results

Gene expression of cultures stored at 4°C and 12°C clustered close to the unstored control cultures. Cultures stored at 37°C displayed substantial change in gene expression compared to the other groups. In comparison with 12°C, 2,981 genes were differentially expressed at 37°C. In contrast, only 67 genes were differentially expressed between the unstored control and the cells stored at 12°C. The 12°C and 37°C culture groups differed most significantly with regard to the expression of differentiation markers. The Hedgehog signaling pathway was significantly downregulated at 37°C compared to 12°C.

Conclusion

HOK cultures stored at 37°C showed considerably larger changes in gene expression compared to unstored cells than cultured HOK stored at 4°C and 12°C. The changes observed at 37°C consisted of differentiation of the cells towards a squamous epithelium-specific phenotype. Storing cultured ocular surface transplants at 37°C is therefore not recommended. This is particularly interesting as 37°C is the standard incubation temperature used for cell culture.

Histological and Immunohistological Findings Using Anti-Cortisol Antibody in Atopic Dermatitis with Topical Steroid Addiction

Introduction

Though topical steroid addiction (TSA) in patients with atopic dermatitis (AD) has been recently discussed as a clinical problem, there are very few studies about its mechanism. The purpose of this study was to elucidate histological and immunohistological characteristics of TSA using anti-cortisol antibody.

Methods

Skin biopsy specimen from eight patients with AD was stained by anti-cortisol antibody (Biorbyt, orb79379). Subjects consisted of a child patient with a short history of topical corticosteroids (TCS) application, an adult patient with a long history of TCS application, and six adult patients who have experienced topical steroid withdrawal (TSW) and the rebound phenomenon.

Results

The staining in the epidermis by anti-cortisol antibody presented patchy defects in the child patient, the patient with a long history of TCS application, and two patients at the rebound period. Parakeratosis with poor formation of corneal layer was obvious in the child patient, the patient with a long history of TCS application, two patients recovered from TSA, and two patients at the rebound period.

Conclusion

Prolonged application of TCS might suppress the cortisol production of keratinocytes which is poorly developed at the early ages before childhood and completed naturally as to growth. Rebound phenomenon after TSW can occur due to the relative insufficiency of cortisol in the epidermis and the immature corneal layer formation.

Electronic supplementary material

The online version of this article (doi:10.1007/s13555-016-0096-7) contains supplementary material, which is available to authorized users.

Lowered humidity produces human epidermal equivalents with enhanced barrier properties

Multilayered human keratinocyte cultures increasingly are used to model human epidermis. Until now, studies utilizing human epidermal equivalents (HEEs) have been limited because previous preparations do not establish a normal epidermal permeability barrier. In this report, we show that reducing environmental humidity to 50% relative humidity yields HEEs that closely match human postnatal epidermis and have enhanced repair of the permeability barrier. These cultures display low transepidermal water loss and possess a calcium and pH gradient that resembles those seen in human epidermis. These cultures upregulate glucosylceramide synthase and make normal-appearing lipid lamellar bilayers. The epidermal permeability barrier of these cultures can be perturbed, using the identical tools previously described for human skin, and recover in the same time course seen during in vivo barrier recovery. These cultures will be useful for basic and applied studies on epidermal barrier function.

On the role of environmental humidity on cortisol production by epidermal keratinocytes

Evidence is accumulating that skin can act as an independent steroidogenic organ. It can respond to various stresses including UV light, trauma and oncogenesis by upregulating glucocorticoid production via elements of the local hypothalamic-pituitary-adrenal (HPA) axis. Recent data by Takei and collaborators provided in this issue of Experimental Dermatology included dryness to the list of stressors stimulating cutaneous cortisol synthesis with a possible involvement of IL-1β as a mediator of this regulation. Thus, the last decade of research has not only documented that skin can produce cortisol, but that levels of its production change in response to environmental stress. The role of this regulated steroidogenic system in physiological or pathological outcomes requires further studies with focus on cutaneous homeostasis, formation of epidermal barrier, antimicrobial activity and display of immune (both pro- and anti-inflammatory) properties.

Increased corticotropin-releasing hormone (CRH) expression in cutaneous lupus lesions

Objective

Corticotropin-releasing hormone (CRH) and pro-opiomelanocortin (POMC) axis activation leads to the production of hormones, such as adrenocorticotrophic hormone (ACTH) and the α-melanocyte stimulating hormone (α-MSH). Data regarding the role of these hormones in systemic lupus erythematosus (SLE) are scarce. In the present study we aim to evaluate the participation of this axis in the cutaneous involvement of SLE.

Methods

Seventeen SLE patients were clinically evaluated, and biopsies from affected and unaffected skin of these patients were compared with 17 healthy control individuals. Immunohistochemical analyses for CRH, ACTH, α-MSH, and MC-1R were performed, and the serum levels of α-MSH, IL-1, IL-1ra, IL-6, IL-10, IL-12p70, IL-17, TNF-α, and IFN-γ were measured.

Results

The affected skin of the SLE patients exhibited higher CRH expression in the deep dermis compared to the skin of the controls ( p = 0.024), whereas the tissue expression of ACTH, cortisol, α-MSH and its receptor MC-1R were comparable in SLE patients and controls. Higher serum levels of IFN-γ ( p = 0.041), TNF-α ( p = 0.001) and IL-6 ( p = 0.049) were observed in SLE patients compared with controls, while α-MSH levels were similar in both groups.

Conclusion

The novel finding of elevated CRH expression solely in the affected skin deep dermis supports the notion of a cutaneous local dysfunction of the CRH-POMC axis in the pathogenesis of cutaneous SLE lesions.

3D In vitro model of a functional epidermal permeability barrier from human embryonic stem cells and induced pluripotent stem cells

Cornification and epidermal barrier defects are associated with a number of clinically diverse skin disorders. However, a suitable in vitro model for studying normal barrier function and barrier defects is still lacking. Here, we demonstrate the generation of human epidermal equivalents (HEEs) from human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs). HEEs are structurally similar to native epidermis, with a functional permeability barrier. We exposed a pure population of hESC/iPSC-derived keratinocytes, whose transcriptome corresponds to the gene signature of normal primary human keratinocytes (NHKs), to a sequential high-to-low humidity environment in an air/liquid interface culture. The resulting HEEs had all of the cellular strata of the human epidermis, with skin barrier properties similar to those of normal skin. Such HEEs generated from disease-specific iPSCs will be an invaluable tool not only for dissecting molecular mechanisms that lead to epidermal barrier defects but also for drug development and screening.

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Manufacture of HEEs with a functional epidermal barrier in vitro from hESCs/iPSCs

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Unique model for skin diseases with defective epidermal permeability barriers

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Easily adaptable model for use in regenerative and aesthetic medicine

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Cost-effective model for testing new drugs and cosmetics