Aquaporin-3 in keratinocytes and skin: its role and interaction with phospholipase D2

The Role of PGC-1α in Aging Skin Barrier Function

Skin provides a physical and immune barrier to protect the body from foreign substances, microbial invasion, and desiccation. Aging reduces the barrier function of skin and its rate of repair. Aged skin exhibits decreased mitochondrial function and prolonged low-level inflammation that can be seen in other organs with aging. Peroxisome proliferator-activated receptor (PPAR)-γ coactivator-1α (PGC-1α), an important transcriptional coactivator, plays a central role in modulating mitochondrial function and antioxidant production. Mitochondrial function and inflammation have been linked to epidermal function, but the mechanisms are unclear. The aim of this review is to discuss the mechanisms by which PGC-1α might exert a positive effect on aged skin barrier function. Initially, we provide an overview of the function of skin under physiological and aging conditions, focusing on the epidermis. We then discuss mitochondrial function, oxidative stress, cellular senescence, and inflamm-aging, the chronic low-level inflammation observed in aging individuals. Finally, we discuss the effects of PGC-1α on mitochondrial function, as well as the regulation and role of PGC-1α in the aging epidermis.

Nuclear receptors for epidermal lipid barrier: Advances in mechanisms and applications

The skin plays an essential role in preventing the entry of external environmental threats and the loss of internal substances, depending on the epidermal permeability barrier. Nuclear receptors (NRs), present in various tissues and organs including full-thickness skin, have been demonstrated to exert significant effects on the epidermal lipid barrier. Formation of the lipid lamellar membrane and the normal proliferation and differentiation of keratinocytes (KCs) are crucial for the development of the epidermal permeability barrier and is regulated by specific NRs such as PPAR, LXR, VDR, RAR/RXR, AHR, PXR and FXR. These receptors play a key role in regulating KC differentiation and the entire process of epidermal lipid synthesis, processing and secretion. Lipids derived from sebaceous glands are influenced by NRs as well and participate in regulation of the epidermal lipid barrier. Furthermore, intricate interplay exists between these receptors. Disturbance of barrier function leads to a range of diseases, including psoriasis, atopic dermatitis and acne. Targeting these NRs with agonists or antagonists modulate pathways involved in lipid synthesis and cell differentiation, suggesting potential therapeutic approaches for dermatosis associated with barrier damage. This review focuses on the regulatory role of NRs in the maintenance and processing of the epidermal lipid barrier through their effects on skin lipid synthesis and KC differentiation, providing novel insights for drug targets to facilitate precision medicine strategies.

Synergetic Effects of Aloe Vera Extract with Trimethylglycine for Targeted Aquaporin 3 Regulation and Long-Term Skin Hydration

Aquaporin 3 (AQP3) channels are tetrameric membrane-bound channels that facilitate the transport of water and other small solutes across cell membranes in the skin. Decreased AQP3 expression is associated with skin dryness, skin aging, psoriasis, and delayed wound healing. Thus, our study focused on a novel combination based on Aloe barbadensis leaf extract and trimethylglycine for targeted AQP3 regulation in skin keratinocytes and deep skin moisturization. Firstly, a dose-finding cytotoxicity assay of the selected substances was performed with a 2,5-diphenyl-2H-tetrazolium bromide (MTT) indicator on HaCaT cells. The substances' ability to increase the amount of AQP3 in keratinocytes was evaluated in a keratinocyte cell culture by means of ELISA. Additionally, the deep skin hydration effect was confirmed in clinical research with healthy volunteers. According to the results, the maximum tolerated doses providing viability at 70% (MTDs) values for Aloe barbadensis leaf extract and trimethylglycine were 24.50% and 39.00%, respectively. Following the research and development, a complex based on Aloe barbadensis leaf extract and trimethylglycine in a 1:1 mass ratio exhibited a good cytotoxicity profile, with an MTDs value of 37.90%. Furthermore, it was shown that the combination had a clear synergetic effect and significantly increased AQP3 by up to 380% compared to the negative control and glyceryl glucoside (p < 0.001). It was clinically confirmed that the developed shower gel containing Aloe barbadensis leaf extract and trimethylglycine safely improved skin hydration after one use and over 28 days. Thus, this novel plant-based combination has promising potential for AQP3 regulation in the skin epidermis and a role in the development of dermatological drugs for the treatment of skin xerosis and atopic-related conditions.

Aquaporins in the Cornea

The cornea is an avascular, transparent tissue that allows light to enter the visual system. Accurate vision requires proper maintenance of the cornea's integrity and structure. Due to its exposure to the external environment, the cornea is prone to injury and must undergo proper wound healing to restore vision. Aquaporins (AQPs) are a family of water channels important for passive water transport and, in some family members, the transport of other small molecules; AQPs are expressed in all layers of the cornea. Although their functions as water channels are well established, the direct function of AQPs in the cornea is still being determined and is the focus of this review. AQPs, primarily AQP1, AQP3, and AQP5, have been found to play an important role in maintaining water homeostasis, the corneal structure in relation to proper hydration, and stress responses, as well as wound healing in all layers of the cornea. Due to their many functions in the cornea, the identification of drug targets that modulate the expression of AQPs in the cornea could be beneficial to promote corneal wound healing and restore proper function of this tissue crucial for vision.

The Assessment of Infection Risk in Patients with Vitiligo Undergoing Dialysis for End-Stage Renal Disease: A Retrospective Cohort Study

Vitiligo is an autoimmune condition that causes patchy skin depigmentation. Although the mechanism by which vitiligo induces immunocompromise is unclear, other related autoimmune diseases are known to predispose those affected to infection. Individuals with vitiligo exhibit epidermal barrier disruption, which could potentially increase their susceptibility to systemic infections; patients with renal disease also show a predisposition to infection. Nevertheless, there is little research addressing the risk of infection in dialysis patients with vitiligo in comparison to those without it. A retrospective analysis was performed on patients with end-stage renal disease (ESRD) in the United States Renal Data System who started dialysis between 2004 and 2019 to determine if ESRD patients with vitiligo are at an increased risk of bacteremia, cellulitis, conjunctivitis, herpes zoster, or septicemia. Multivariable logistic regression modeling indicated that female sex, black compared to white race, Hispanic ethnicity, hepatitis C infection, and tobacco use were associated with an enhanced risk of vitiligo, whereas increasing age and catheter, versus arteriovenous fistula, and access type were associated with a decreased risk. After controlling for demographics and clinical covariates, vitiligo was found to be significantly associated with an increased risk of bacteremia, cellulitis, and herpes zoster but not with conjunctivitis and septicemia.

Benefits of topical natural ingredients in epidermal permeability barrier

Because of the crucial role of epidermal permeability barrier in regulation of cutaneous and extracutaneous functions, great efforts have been made to identify and develop the regimens that can improve epidermal permeability barrier function. Studies have demonstrated that oral administration of natural ingredients can improve epidermal permeability barrier in various skin conditions, including inflammatory dermatoses and UV-irradiation. Moreover, topical applications of some natural ingredients can also accelerate the repair of epidermal permeability barrier after acute barrier disruption and lower transepidermal water loss in the intact skin. Natural ingredient-induced improvements in epidermal permeability barrier function can be attributable to upregulation of keratinocyte differentiation, lipid production, antioxidant, hyaluronic acid production, expression of aquaporin 3 and sodium-hydrogen exchanger 1. In this review, we summarize the benefits of topical natural ingredients in epidermal permeability barrier in normal skin with or without acute barrier disruption and the underlying mechanisms.

Selective adhesion inhibition and hyaluronan envelope reduction of dermal tumor cells by cold plasma-activated medium

The sensitivity to cold plasma is specific to tumor cells while leaving normal tissue cells unaffected. This is the desired challenge in cancer therapy. Therefore, the focus of this work was a comparative study concerning the plasma sensitivity of dermal tumor cells (A-431) versus non-tumorigenic dermal cells (HaCaT) regarding their adhesion capacity. We found a selective inhibiting effect of plasma-activated medium on the adhesion of tumor cells while hardly affecting normal cells. We attributed this to a lower basal gene expression for the adhesion-relevant components CD44, hyaluronan synthase 2 (HAS2), HAS3, and the hyaluronidases in A431. Noteworthy, after plasma exposure, we revealed a significantly higher expression and synthesis of the hyaluronan envelope, the HAS3 gene, and the transmembrane adhesion receptors in non-tumorigenic HaCaTs.

Aquaporin 1, Aquaporin 8, and Aquaporin 9 Expressions in Malignant Melanoma: A Possible Correlation with Prognosis and Clinical Outcome

Aquaporins (AQPs) are small transmembrane proteins able to facilitate the passive transport of water and small molecules throughout cells. Several studies have demonstrated that modulation of AQPs' expression contributes to cancer development and progression. However, to date, very little is known about their involvement in malignant melanoma (MM) progression. In this retrospective observational study, we evaluated the correlation between AQP1, -8, and -9 expression and the clinical outcomes of 58 patients diagnosed with MM from 2014 to 2016, of which 14 were diagnosed as nodular melanoma (NM) and 44 as superficial spreading melanoma (SSM). In general, we found that AQPs were more highly expressed in SSM than NM, suggesting a potential correlation with prognosis. While analyzing the expression of each AQP, we discovered that AQP1 was associated with a specific body site and low mitotic index, AQP8 with a negative sentinel lymph node, and AQP9 with the Breslow thickness and lack of ulcerations. Together with the survival analysis performed in this study, our results suggest that the expression of AQP1, -8, and -9 could be correlated with a better prognosis for malignant melanoma.

The Skin and Inflamm-Aging

With its unique anatomical location facing both the external and internal environment, the skin has crucial functions, including shielding the body from damage caused by ultraviolet radiation and chemicals, preventing water loss, acting as a primary barrier against pathogens, participating in metabolic processes like vitamin D production and temperature control and relaying information to the body through sensory and proprioceptor nerves. Like all organ systems, skin is known to undergo multiple changes with aging. A better understanding of the mechanisms that mediate aging-related skin dysfunction may allow the creation of targeted therapeutics that have beneficial effects not only on aged skin but also on other organs and tissues that experience a loss of or decline in function with aging. The skin is the largest organ of the body and can contribute to serum inflammatory mediator levels. One alteration known to occur with age is an impairment of skin barrier function; since disruption of the barrier is known to induce inflammation, skin may be a major contributor to the sustained, sub-clinical systemic inflammation associated with aging. Such "inflamm-aging" may underlie many of the deleterious changes observed in aged individuals. This review explores the role of age-related skin changes, skin inflammation and inflamm-aging.

LncRNA-miRNA-mRNA regulatory networks in skin aging and therapeutic potentials

Skin aging is a complex process influenced by intrinsic and extrinsic factors. Although dermatology offers advanced interventions, molecular mechanisms in skin aging remain limited. Competing endogenous RNAs (ceRNAs), a subset of coding or non-coding RNAs, regulate gene expression through miRNA competition. Several ceRNA networks investigated up to now offer insights into skin aging and wound healing. In skin aging, RP11-670E13.6-miR-663a-CDK4/CD6 delays senescence induced by UVB radiation. Meg3-miR-93-5p-epiregulin contributes to UVB-induced inflammatory skin damage. Predicted ceRNA networks reveal UVA-induced photoaging mechanisms. SPRR2C sequesters miRNAs in epidermal aging-associated alteration of calcium gradient. H19-miR-296-5p-IGF2 regulates dermal fibroblast senescence. PVT1-miR-551b-3p-AQP3 influences skin photoaging. And bioinformatics analyses identify critical genes and compounds for skin aging interventions. In skin wound healing, MALAT1-miR-124 aids wound healing by activating the Wnt/β-catenin pathway. Hair follicle MSC-derived H19 promotes wound healing by inhibiting pyroptosis. And the SAN-miR-143-3p-ADD3 network rejuvenates adipose-derived mesenchymal stem cells in wound healing. Thus, ceRNA networks provide valuable insights into the molecular underpinnings of skin aging and wound healing, offering potential therapeutic strategies for further investigation. This comprehensive review serves as a foundational platform for future research endeavors in these crucial areas of dermatology.

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.

Phosphatidylglycerol to Treat Chronic Skin Wounds in Diabetes

This review proposes the use of dioleoylphosphatidylglycerol (DOPG) to enhance diabetic wound healing. Initially, the characteristics of diabetic wounds are examined, focusing on the epidermis. Hyperglycemia accompanying diabetes results in enhanced inflammation and oxidative stress in part through the generation of advanced glycation end-products (AGEs), in which glucose is conjugated to macromolecules. These AGEs activate inflammatory pathways; oxidative stress results from increased reactive oxygen species generation by mitochondria rendered dysfunctional by hyperglycemia. These factors work together to reduce the ability of keratinocytes to restore epidermal integrity, contributing to chronic diabetic wounds. DOPG has a pro-proliferative action on keratinocytes (through an unclear mechanism) and exerts an anti-inflammatory effect on keratinocytes and the innate immune system by inhibiting the activation of Toll-like receptors. DOPG has also been found to enhance macrophage mitochondrial function. Since these DOPG effects would be expected to counteract the increased oxidative stress (attributable in part to mitochondrial dysfunction), decreased keratinocyte proliferation, and enhanced inflammation that characterize chronic diabetic wounds, DOPG may be useful in stimulating wound healing. To date, efficacious therapies to promote the healing of chronic diabetic wounds are largely lacking; thus, DOPG may be added to the armamentarium of drugs to enhance diabetic wound healing.

LncRNA PVT1 delays skin photoaging by sequestering miR-551b-3p to release AQP3 expression via ceRNA mechanism

Understanding human skin photoaging requires in-depth knowledge of the molecular and functional mechanisms. Human dermal fibroblasts (HDFs) gradually lose their ability to produce collagen and renew intercellular matrix with aging. Therefore, our study aims to reveal the mechanistic actions of a novel ceRNA network in the skin photoaging by regulating HDF activities. Photoaging-related genes were obtained in silico, followed by GO and KEGG enrichment analyses. Differentially expressed lncRNAs and miRNAs were screened from the GEO database to construct the ceRNA co-expression network. In skin photoaging samples, PVT1 and AQP3 were poorly expressed, while miR-551b-3p was highly expressed. The relationships among the lncRNA, miRNA and mRNA were explored through the ENCORI database and dual luciferase reporter assay. Mechanistically, PVT1 could sequester miR-551b-3p to upregulate the expression of AQP3, which further inactivated the ERK/p38 MAPK signaling pathway. HDFs were selected to construct an in vitro cell skin photoaging model, where the senescence, cell cycle distribution and viability of young and senescent HDFs were detected by SA-β-gal staining, flow cytometry and CCK-8 assay. In vitro cell experiments confirmed that overexpression of PVT1 or AQP3 enhanced viability of young and senescent HDFs and inhibited HDF senescence, while miR-551b-3p upregulation counteracted the effect of PVT1. In conclusion, PVT1-driven suppression of miR-551b-3p induces AQP3 expression to inactivate the ERK/p38 MAPK signaling pathway, thereby inhibiting HDF senescence and ultimately delaying the skin photoaging.

Advanced Glycation End Products and Activation of Toll-like Receptor-2 and -4 Induced Changes in Aquaporin-3 Expression in Mouse Keratinocytes

Prolonged inflammation and impaired re-epithelization are major contributing factors to chronic non-healing diabetic wounds; diabetes is also characterized by xerosis. Advanced glycation end products (AGEs), and the activation of toll-like receptors (TLRs), can trigger inflammatory responses. Aquaporin-3 (AQP3) plays essential roles in keratinocyte function and skin wound re-epithelialization/re-generation and hydration. Suberanilohydroxamic acid (SAHA), a histone deacetylase inhibitor, mimics the increased acetylation observed in diabetes. We investigated the effects of TLR2/TLR4 activators and AGEs on keratinocyte AQP3 expression in the presence and absence of SAHA. Primary mouse keratinocytes were treated with or without TLR2 agonist Pam3Cys-Ser-(Lys)4 (PAM), TLR4 agonist lipopolysaccharide (LPS), or AGEs, with or without SAHA. We found that (1) PAM and LPS significantly upregulated AQP3 protein basally (without SAHA) and PAM downregulated AQP3 protein with SAHA; and (2) AGEs (100 µg/mL) increased AQP3 protein expression basally and decreased AQP3 levels with SAHA. PAM and AGEs produced similar changes in AQP3 expression, suggesting a common pathway or potential crosstalk between TLR2 and AGEs signaling. Our findings suggest that TLR2 activation and AGEs may be beneficial for wound healing and skin hydration under normal conditions via AQP3 upregulation, but that these pathways are likely deleterious in diabetes chronically through decreased AQP3 expression.

Aquaporins in Skin

The skin is the largest organ of our body and plays a protective role against the external environment. The skin functions as a mechanical and water permeability barrier, assisting with thermoregulation and defending our body against a variety of stresses such as ultraviolet radiation, microbial infection, physical injuries, and chemical hazards. The structure of the skin consists of three main layers: the hypodermis, the dermis, and the epidermis. Aquaporins (AQPs) are a family of integral membrane proteins whose function is to regulate intracellular fluid hemostasis by facilitating the transportation of water, and in some cases small molecules, across the cell membranes. Up to six different AQPs (AQP1, 3, 5, 7, 9, and 10) are expressed in a variety of cell types in the skin. The AQP family plays an important role in these various locations, contributing to many key functions of the skin including hydration, wound healing, and immune responses. The involvement of different aquaporin family members in skin is discussed.

Betula alba Bark Extract and Empetrum nigrum Fruit Juice, a Natural Alternative to Niacinamide for Skin Barrier Benefits

The Scandinavian region is home to a unique biome with endemic plant species. The aim of this study was to explore this natural diversity and identify plant extracts providing positive skin barrier effects. Six plant extracts were identified as starting material. Following biochemical screening, two candidates outperformed the rest: Betula alba (BA) and Empetrum nigrum (EN). Quantitative PCR analysis showed that BA and EN upregulated barrier genes, when used individually and in combination. Betula alba increased AQP3 and OCLN protein expression, something niacinamide was incapable of. Additionally, the skin barrier was strengthened, evidenced by inhibition of KLK5 and hyaluronidase and showed strong antioxidant and anti-inflammatory activity through DPPH and COX2 inhibition, respectively. A first split-face clinical study was conducted using the combination of extracts versus placebo. There was a significantly better skin restructuring effect and corneocyte cohesion on the side treated with combined extracts. A second split-face clinical study assessed the combined extracts versus 3% niacinamide. Significant variations in skin hydration and TEWL were observed in favor of the extract treated side. In conclusion, we identified a natural alternative to niacinamide for improving skin barrier health, in Scandinavian plant extracts, which yield strong performance, but at a lower concentration.

Poria cocos Extract from Mushrooms Stimulates Aquaporin-3 via the PI3K/Akt/mTOR Signaling Pathway

Background

Poria cocos (PC), a fungus, has been used for more than 2000 years as a food and medicine in China. PC and its components have various pharmacological effects on the skin, including immunomodulatory activities, barrier function improvement, and anti-tumor effects. However, the effect of PC in aquaporin-3 (AQP3) expression, which is essential for epidermal water permeability barrier maintenance, was not reported.

Methods

This study examined the mechanism through which the ethanol extract of the sclerotium of PC (EPC) promoted the expression of AQP3 in cultured human keratinocytes. Western blotting was used to investigate the expression of AQPs and the activation of phosphoinositide 3-kinase (PI3K)/Akt-related signaling molecules in HaCaT cells. Cells were treated with inhibitors of PI3K/Akt and mechanistic target of rapamycin (mTOR) prior to EPC treatment.

Results

EPC promoted the expression of AQP3 in HaCaT cells without affecting AQP1 and AQP2 expression. Phosphorylated Akt levels were increased by EPC treatment, and the inhibition of PI3K by LY2940002 resulted in a reduction in EPC-induced AQP3 expression. Furthermore, EPC stimulated the phosphorylation of p70S6K and Akt^Ser473, which are downstream targets of mTORC1 and mTORC2, respectively. The mTOR complex inhibitors, rapamycin and Torin 1, partially reduced EPC-induced AQP3 expression.

Conclusion

These results suggest that EPC increased expression of AQP3, which is important for skin moisturization, by activating the PI3K/Akt/mTOR signaling pathway in human keratinocytes.

Cetacean epidermal specialization: A review

Cetacean skin continues to be the investigative focus of researchers from several different scientific disciplines. Yet, most research on the basic functions of lipo-keratinocytes, which constitute most of the cetacean epidermis, providing the first layer of protection against various environmental aggressors (including an ever-increasing level of pollutants), is restricted to specialized literature on the permeability barrier only. In this review, we have attempted to bring together much of the recent research on the functional biology of cetacean skin, including special adaptations at the cellular, genetic and molecular level. We have correlated these data with the cetacean permeability barrier's unique structural and metabolic adaptations to fully aquatic life, including the development of secondary barriers to ward off challenges such as biofouling as well as exposure to extreme cold for the epidermis, which is outside of the insulation provided by blubber. An apparent contradiction exists between some of the reported gene loss for lipogenic enzymes in cetacean skin and the high degree of cetacean epidermal lipogenesis, as well as loss of desmocollin 1 and desmoplakin genes [while immunolocalization of these proteins is reported (Journal of Anatomy, 234, 201)] warrants a re-evaluation of the gene loss data.

The contribution of mouse models to understanding atopic dermatitis

Atopic dermatitis (AD) is a dermatological disease accompanied by dry and cracked skin with severe pruritus. Although various therapeutic strategies have been introduced to alleviate AD, it remains challenging to cure the disorder. To achieve such a goal, understanding the pathophysiological mechanisms of AD is a prerequisite, requiring mouse models that properly reflect the AD phenotypes. Currently, numerous AD mouse models have been established, but each model has its own advantages and weaknesses. In this review, we categorized and summarized mouse models of AD and described their characteristics from a researcher's perspective.

Aquaporins Are One of the Critical Factors in the Disruption of the Skin Barrier in Inflammatory Skin Diseases

The skin is the largest organ of the human body, serving as an effective mechanical barrier between the internal milieu and the external environment. The skin is widely considered the first-line defence of the body, with an essential function in rejecting pathogens and preventing mechanical, chemical, and physical damages. Keratinocytes are the predominant cells of the outer skin layer, the epidermis, which acts as a mechanical and water-permeability barrier. The epidermis is a permanently renewed tissue where undifferentiated keratinocytes located at the basal layer proliferate and migrate to the overlying layers. During this migration process, keratinocytes undertake a differentiation program known as keratinization process. Dysregulation of this differentiation process can result in a series of skin disorders. In this context, aquaporins (AQPs), a family of membrane channel proteins allowing the movement of water and small neutral solutes, are emerging as important players in skin physiology and skin diseases. Here, we review the role of AQPs in skin keratinization, hydration, keratinocytes proliferation, water retention, barrier repair, wound healing, and immune response activation. We also discuss the dysregulated involvement of AQPs in some common inflammatory dermatological diseases characterised by skin barrier disruption.

Paclitaxel Induces Epidermal Molecular Changes and Produces Subclinical Alterations in the Skin of Gynecological Cancer Patients

Simple Summary

Skin toxicity is one of paclitaxel’s adverse effects. However, its real impact on the skin could be underestimated as these alterations can also appear asymptomatic. We have observed that paclitaxel modifies gene and protein expression of skin markers in a 3D epidermis model, and impairs physical, physiological, and biomechanical properties of the skin in gynecologic cancer patients. These subclinical alterations might be avoided by using prophylactic measures during treatment to prevent possible future adverse reactions.

Abstract

Background: Paclitaxel is a microtubule-stabilizing chemotherapeutic agent. Despite its widespread use, it damages healthy tissues such as skin. The goal of this study was to prove that the real impact of paclitaxel-induced skin toxicity could be underestimated because the adverse events might appear asymptomatic. Methods: Gynecological cancer patients were recruited. Skin parameters measurements were taken after three and six paclitaxel cycles. Measurements were conducted using specific probes which measure hydration, transepidermal water loss (TEWL), sebum, elasticity and firmness, erythema, roughness, smoothness, skin thickness, and desquamation levels. Further, a 3D epidermis model was incubated with paclitaxel to analyze gene and protein expression of aquaporin 3, collagen type 1, elastin, and fibronectin. Results: Paclitaxel induced alterations in the skin parameters with no visible clinical manifestations. Gynecological cancer patients under paclitaxel treatment had a decrease in hydration, TEWL, sebum, elasticity, and thickness of the skin, while erythema, roughness, and desquamation were increased. The molecular markers, related to hydration and the support of the skin layers, and analyzed in the 3D epidermis model, were decreased. Conclusions: Results suggest that paclitaxel modifies gene and protein expression of skin-related molecular markers, and impairs different physical, physiological, and biomechanical properties of the skin of cancer patients at a subclinical level.

Vorinostat, a histone deacetylase inhibitor, as a potential novel treatment for psoriasis

BACKGROUND

Psoriasis is characterized by aberrant activation of several pro-inflammatory circuits as well as abnormal hyperproliferation and dysregulated apoptosis of keratinocytes (KCs). Most currently available therapeutic options primarily target psoriasis-associated immunological defects rather than epidermal abnormalities.

OBJECTIVE

To investigate the efficacy of the histone deacetylase (HDAC) inhibitor, Vorinostat, in targeting hyperproliferation and impaired apoptosis in psoriatic skin.

METHODS

Vorinostat effect was investigated in primary KCs cell cultures using cell cycle analysis by flow cytometry, apoptosis assays (Annexin V-FICH and caspase-3/7) and antibody arrays, qRT-PCR and immunohistochemistry. Vorinostat impact on clinical manifestations of psoriasis was investigated in a chimeric mouse model.

RESULTS

Vorinostat was found to inhibit KCs proliferation and to induce their differentiation and apoptosis. Using a chimeric mouse model, vorinostat was found to result in marked attenuation of a psoriasiform phenotype with a significant decrease in epidermal thickness and inhibition of epidermal proliferation.

CONCLUSIONS

Our results support the notion that vorinostat, a prototypic HDAC inhibitor, may be of potential use in the treatment of psoriasis and other hyperproliferative skin disorders.

Partially Hydrolysed Whey-Based Infant Formula Improves Skin Barrier Function

Specific partially hydrolysed whey-based infant formulas (pHF-W) have been shown to decrease the risk of atopic dermatitis (AD) in infants. Historically, AD has been associated primarily with milk allergy; however, defective skin barrier function can be a primary cause of AD. We aimed to ascertain whether oral supplementation with pHF-W can improve skin barrier function. The effect of pHF-W was assessed on transepidermal water loss (TEWL) and antibody productions in mice epicutaneously exposed to Aspergillus fumigatus. Human primary keratinocytes were stimulated in vitro, and the expression of genes related to skin barrier function was measured. Supplementation with pHF-W in neonatal mice led to a significant decrease in TEWL and total IgE, but not in allergen-specific antibody levels. The whey hydrolysate was sufficient to decrease both TEWL and total IgE. Aquaporin-3 gene expression, linked with skin hydration, was modulated in the skin of mice and human primary keratinocytes following protein hydrolysate exposure. Skin barrier improvement may be an additional mechanism by which pHF-W may potentially reduce the risk of AD development in infants. Further human studies are warranted to confirm the clinical efficacy of these observations.

Is vitiligo associated with systemic aquaporin-3 deficiency?

Introduction

Recent studies on pathomechanisms of vitiligo have focused on the abnormality of keratinocytes that affect the melanocytes. Aquaporin-3 (AQP3) was implicated as a mechanism for keratinocyte apoptosis owing to the relationship between the PI3K/AKT pathway and the E-cadherin-catenin complex.

Aim

Based on this evidence, we undertook a cross-sectional study to assess the skin and blood AQP-3 levels in patients with non-segmental vitiligo in comparison to controls and to correlate these levels with malondialdehyde (MDA) levels and total antioxidant status (TAS) in the skin and blood of patients with non-segmental vitiligo and also with their disease activity.

Material and methods

Thirty-six patients with non-segmental vitiligo and 36 controls were included in this study. AQP3, TAS and MDA levels were assayed both in skin as well as in circulation.

Results

We observed that skin and plasma aquaporin and TAS were lowered and MDA levels were increased in patients with non-segmental vitiligo as compared to controls. There was a significant negative correlation of skin and plasma aquaporin levels with disease activity. We also observed the local and systemic AQP3 deficiency to correlate with the local and systemic oxidative stress in vitiligo.

Conclusions

Our results demonstrate a systemic and local AQP3 deficiency in vitiligo correlating with the disease severity and oxidative stress which might have therapeutic implications.

Glycerol Improves Skin Lesion Development in the Imiquimod Mouse Model of Psoriasis: Experimental Confirmation of Anecdotal Reports from Patients with Psoriasis

Glycerol is used in many skin care products because it improves skin function. Anecdotal reports by patients on the National Psoriasis Foundation website also suggest that glycerol may be helpful for the treatment of psoriasis, although to date no experimental data confirm this idea. Glycerol entry into epidermal keratinocytes is facilitated by aquaglyceroporins like aquaporin-3 (AQP3), and its conversion to phosphatidylglycerol, a lipid messenger that promotes keratinocyte differentiation, requires the lipid-metabolizing enzyme phospholipase-D2 (PLD2). To evaluate whether glycerol inhibits inflammation and psoriasiform lesion development in the imiquimod (IMQ)-induced mouse model of psoriasis, glycerol’s effect on psoriasiform skin lesions was determined in IMQ-treated wild-type and PLD2 knockout mice, with glycerol provided either in drinking water or applied topically. Psoriasis area and severity index, ear thickness and ear biopsy weight, epidermal thickness, and inflammatory markers were quantified. Topical and oral glycerol ameliorated psoriasiform lesion development in wild-type mice. Topical glycerol appeared to act as an emollient to induce beneficial effects, since even in PLD2 knockout mice topical glycerol application improved skin lesions. In contrast, the beneficial effects of oral glycerol required PLD2, with no improvement in psoriasiform lesions observed in PLD2 knockout mice. Our findings suggest that the ability of oral glycerol to improve psoriasiform lesions requires its PLD2-mediated conversion to phosphatidylglycerol, consistent with our previous report that phosphatidylglycerol itself improves psoriasiform lesions in this model. Our data also support anecdotal evidence that glycerol can ameliorate psoriasis symptoms and therefore might be a useful therapy alone or in conjunction with other treatments.

Edible Bird's Nest, an Asian Health Food Supplement, Possesses Moisturizing Effect by Regulating Expression of Filaggrin in Skin Keratinocyte

Edible bird's nest (EBN) has been consumed as a Chinese delicacy for hundreds of years; the functions of which have been proposed to prevent lung disease, strengthen immune response, and restore skin youthfulness. To support the skin function of EBN, the water extract and the enzymatic digest of EBN with enriched digested peptides were tested in cultured keratinocyte, HaCaT cell line. The effects of EBN extract and digest in inducing proteins crucial for skin moisturizing were determined in both in vitro and ex vivo models. In cultured keratinocytes, the expressions of S100-fused type proteins contributing to skin barrier function in the stratum corneum, e.g. filaggrin and filaggrin-2, were determined in both mRNA and protein levels, which were markedly induced in the treatment of EBN extract or digest. The EBN-induced gene transcriptions of filaggrin and filaggrin-2 were mediated by activation of p38 MAPK pathway and various transcription factors, e.g. GATA3, PPARα, PPARβ, and PPARγ: these transcriptional factors were markedly activated by the digested products of EBN, as compared to the extract, in cultured keratinocytes. By using atomic force microscopy (AFM), the EBN-treated keratinocyte was shown to have more liquid-like morphology, as compared to a control cell. The EBN digest showed better induction on these moisturizing effects as compared to the extract. These lines of evidence therefore suggested the water moisturizing effect of EBN in skin function.

Aquaporin regulation in metabolic organs

Aquaporins (AQPs) are a family of 13 small trans-membrane proteins, which facilitate shuttling of glycerol, water and urea. The peculiar role of AQPs in glycerol transport makes them attractive targets in metabolic organs since glycerol represents the backbone of triglyceride synthesis. Importantly, AQPs are known to be regulated by various nuclear receptors which in turn govern lipid and glucose metabolism as well as inflammatory cascades. Here, we review the role of AQPs regulation in metabolic organs exploring their physiological impact in health and disease.

Identification of Key Pathways and Genes Related to the Development of Hair Follicle Cycle in Cashmere Goats

The development of hair follicle in cashmere goats shows significant periodic change, as with mice and humans. However, for cashmere goat with double-coat, the periodic change may be due to other regulatory molecules and signal pathways. To understand the mechanism of periodic development of hair follicle, we performed a weighted gene coexpression network analysis (WGCNA) to mine key genes and establish an interaction network by utilizing the NCBI public dataset. Ten coexpression modules, including 7689 protein-coding genes, were constructed by WGCNA, six of which are considered to be significantly related to the development of the hair follicle cycle. A functional enrichment analysis for each model showed that they are closely related to ECM- receptor interaction, focal adhesion, PI3K-Akt signaling pathway, estrogen signaling pathway, and so on. Combined with the analysis of differential expressed genes, 12 hub genes from coexpression modules were selected as candidate markers, i.e., COL1A1, C1QTNF6, COL1A2, AQP3, KRTAP3-1, KRTAP11-1, FA2H, NDUFS5, DERL2, MRPL14, ANTKMT and XAB2, which might be applied to improve cashmere production.

Effect of Astaxanthin on the Expression and Activity of Aquaporin-3 in Skin in an In-Vitro Study

Astaxanthin (3,3′-dihydroxy-β,β-carotene-4,4′-dione) is a red lipophilic pigment with strong antioxidant action. Oral or topical administration of astaxanthin has been reported to improve skin function, including increasing skin moisture. In this study, we examined the mechanism by which astaxanthin improves skin function by focusing on the water channel aquaporin-3 (AQP3), which plays important roles in maintaining skin moisture and function. When astaxanthin was added to PHK16-0b or HaCaT cells, the mRNA expression level of AQP3 increased significantly in a concentration-dependent manner in both cell lines. The AQP3 protein expression level was also confirmed to increase when astaxanthin was added to HaCaT cells. Similarly, when astaxanthin was added to 3D human epidermis model EpiSkin, AQP3 expression increased. Furthermore, when glycerol and astaxanthin were simultaneously added to EpiSkin, glycerol permeability increased significantly compared with that observed for the addition of glycerol alone. We demonstrated that astaxanthin increases AQP3 expression in the skin and enhances AQP3 activity. This result suggests that the increased AQP3 expression in the skin is associated with the increase in skin moisture by astaxanthin. Thus, we consider astaxanthin useful for treating dry skin caused by decreased AQP3 due to factors such as diabetes mellitus and aging.

Involvement of Aquaporins in the Intense Pulsed Light-Enhanced Wound Healing in Diabetic Rats

BACKGROUND AND OBJECTIVES

We previously demonstrated that intense pulsed light (IPL) irradiation prior to wounding improved the wound healing in rats with diabetes mellitus (DM). Also, we found that IPL upregulated the expression of aquaporin 3 (AQP3), a protein that is crucial for wound healing, in normal rats. This present study aimed to examine the involvement of AQPs in the IPL-enhanced wound healing in diabetic rats.

STUDY DESIGN/MATERIALS AND METHODS

Streptozotocin was used to induce diabetes in Sprague-Dawley rats. Animals were divided into four groups: normal group, DM only group, DM rats with IPL treatment 2 weeks before wounding (DM + IPL-Pre group), and DM rats with concurrent IPL irradiation and wounding (DM + IPL-Con group). Wounds were created on the dorsal skin of rats. The expressions of AQP1, 3, 4, 7, and 9 in the pre-injured skin, periwound, and wound were determined.

RESULTS

Among all the AQPs analyzed, only the expressions of AQP3 and AQP7 were significantly altered. Unirradiated diabetic rats showed much higher expression level of AQP3 in the regenerating skin compared with normal rats. IPL pretreatment, but not concurrent treatment, attenuated the expression toward the level detected in the normal wounds. In contrast, a lower expression level of AQP7 was noted in the regenerating skin of DM only rats and IPL pretreatment upregulated the expression to a level similar to that in the normal rats.

CONCLUSION

The beneficial effect of IPL pretreatment on the wound healing in diabetic rats might involve a mechanism by which the expression of AQPs is regulated. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Unsaturated fatty acid-enriched extract from Hippophae rhamnoides seed reduces skin dryness through up-regulating aquaporins 3 and hyaluronan synthetases 2 expressions

Background

Seed oil of sea buckthorn (SBT) is well known to contain high amount of polyunsaturated fatty acid (PUFA), and PUFA is generally acknowledged to promote skin hydration by reducing trans‐epidermal water loss (TEWL).

Aims

The present study is aimed to investigate that skin hydration offered by SBT seed oil is whether through up‐regulating AQP3 or HAS2 expression.

Methods

MTT assay was performed to detect cytotoxicity of SBT seed oil, and then, PCR was carried out to explore whether SBT seed oil can increase AQP3 mRNA expression in normal human epidermis keratinocytes (NHEK) cells or not. Immunofluorescence (IF) and Western blot analysis were used to test the protein level expression of AQP3 and HAS2 influenced by SBT seed oil in NHEK cells or in reconstructed epidermis skin model.

Results

According to the result of MTT assay, all test concentration of SBT seed oil showed no cytotoxicity to cells. 10 μg/mL SBT seed oil treatment evidently increased AQP3 mRNA level compared to negative control (NC). IF and Western blot analysis results demonstrated that AQP3 and HAS2 protein levels in NHEK cells treated with 10 μg/mL SBT seed oil were much higher than that of NC. Finally, treatment with 10 μg/mL SBT seed oil substantially up‐regulated expression of AQP3 and HAS2 protein in reconstructed epidermis skin model in comparison to NC.

Conclusions

In summary, our study first proved that SBT seed oil can improve skin hydration through increasing AQP3 and HAS2 expressions.

Dioleoylphosphatidylglycerol Accelerates Corneal Epithelial Wound Healing

Purpose

In contact with the external environment, the cornea can easily be injured. Although corneal wounds generally heal rapidly, the pain and increased risk of infection associated with a damaged cornea, as well as the impaired healing observed in some individuals, emphasize the need for novel treatments to accelerate corneal healing. We previously demonstrated in epidermal keratinocytes that the glycerol channel aquaporin-3 (AQP3) interacts with phospholipase D2 (PLD2) to produce the signaling phospholipid phosphatidylglycerol (PG), which has been shown to accelerate skin wound healing in vivo. We hypothesized that the same signaling pathway might be operational in corneal epithelial cells.

Methods

We used co-immunoprecipitation, immunohistochemistry, scratch wound healing assays in vitro, and corneal epithelial wound healing assays in vivo to determine the role of the AQP3/PLD2/PG signaling pathway in corneal epithelium.

Results

AQP3 was present in human corneas in situ, and AQP3 and PLD2 were co-immunoprecipitated from corneal epithelial cell lysates. The two proteins could also be co-immunoprecipitated from insect cells simultaneously infected with AQP3- and PLD2-expressing baculoviruses, suggesting a likely direct interaction. A particular PG, dioleoylphosphatidylglycerol (DOPG), enhanced scratch wound healing of a corneal epithelial monolayer in vitro. DOPG also accelerated corneal epithelial wound healing in vivo, both in wild-type mice and in a mouse model exhibiting impaired corneal wound healing (AQP3 knockout mice).

Conclusions

These results indicate the importance of the AQP3/PLD2/PG signaling pathway in corneal epithelial cells and suggest the possibility of developing DOPG as a pharmacologic therapy to enhance corneal wound healing in patients.

Pathogen-Associated Molecular Pattern-Induced TLR2 and TLR4 Activation Increases Keratinocyte Production of Inflammatory Mediators and is Inhibited by Phosphatidylglycerol

Skin serves not only as a protective barrier to microbial entry into the body but also as an immune organ. The outer layer, the epidermis, is composed predominantly of keratinocytes, which can be stimulated to produce proinflammatory mediators. Although some inflammation is useful to defend against infection, excessive or persistent inflammation can lead to the development of inflammatory skin diseases, such as psoriasis, a common skin disorder affecting approximately 2% of the US population. We have previously found that phosphatidylglycerol (PG) derived from soy can inhibit inflammation in a contact irritant ear edema mouse model. Here, we investigated the ability of soy PG to inhibit inflammatory mediator expression in response to activators of the pattern recognition receptors, toll-like receptor-2 (TLR2) and -4 (TLR4). We found that in epidermal keratinocytes, soy PG inhibited TLR2 and TLR4 activation and inflammatory mediator expression in response to a synthetic triacylated lipopeptide and lipopolysaccharide, respectively, as well as an endogenous danger-associated molecular pattern. However, at higher concentrations, soy PG alone enhanced the expression of some proinflammatory cytokines, suggesting a narrow therapeutic window for this lipid. Dioleoylphosphatidylglycerol (DOPG), but not dioleoylphosphatidylcholine, exerted a similar inhibitory effect, completely blocking keratinocyte inflammatory mediator expression induced by TLR2 and TLR4 activators as well as NFκB activation in a macrophage cell line (RAW264.7); however, DOPG was not itself proinflammatory even at high concentrations. Furthermore, DOPG had no effect on NFκB activation in response to a TLR7/8 agonist. Our results suggest that DOPG could be used to inhibit excessive skin inflammation. SIGNIFICANCE STATEMENT: Although inflammation is beneficial for clearing an infection, in some cases, the infection can be excessive and/or become chronic, thereby resulting in considerable tissue damage and pathological conditions. We show here that the phospholipid phosphatidylglycerol can inhibit the activation of toll-like receptors 2 and 4 of the innate immune system as well as the downstream inflammatory mediator expression in response to microbial component-mimicking agents in epidermal keratinocytes that form the physical barrier of the skin.

Plasmodium vivax Liver and Blood Stages Recruit the Druggable Host Membrane Channel Aquaporin-3

Plasmodium vivax infects hepatocytes to form schizonts that cause blood infection, or dormant hypnozoites that can persist for months in the liver before leading to relapsing blood infections. The molecular processes that drive P. vivax schizont and hypnozoite survival remain largely unknown, but they likely involve a rich network of host-pathogen interactions, including those occurring at the host-parasite interface, the parasitophorous vacuole membrane (PVM). Using a recently developed P. vivax liver-stage model system we demonstrate that host aquaporin-3 (AQP3) localizes to the PVM of schizonts and hypnozoites within 5 days after invasion. This recruitment is also observed in P. vivax-infected reticulocytes. Chemical treatment with the AQP3 inhibitor auphen reduces P. vivax liver hypnozoite and schizont burden, and inhibits P. vivax asexual blood-stage growth. These findings reveal a role for AQP3 in P. vivax liver and blood stages and suggest that the protein may be targeted for therapeutic treatment.

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Host aquaporin-3 (AQP3) is recruited to P. vivax hypnozoites and schizonts

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The AQP3 inhibitor auphen inhibits P. vivax hypnozoites and schizonts

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Host AQP3 is recruited to P. vivax-infected erythrocytes derived from patient samples

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Auphen inhibits blood stages of clinical P. vivax isolates

Aquaporin-3 in the epidermis: more than skin deep

The skin is essential for terrestrial life. It is responsible for regulating water permeability and functions as a mechanical barrier that protects against environmental insults such as microbial infection, ultraviolet light, injury, and heat and cold, which could damage the cells of the body and compromise survival of the organism. This barrier is provided by the outer layer, the epidermis, which is composed predominantly of keratinocytes; keratinocytes undergo a program of differentiation to form the stratum corneum comprising the cornified squame "bricks" and lipid "mortar." Dysregulation of this differentiation program can result in skin diseases, including psoriasis and nonmelanoma skin cancers, among others. Accumulating evidence in the literature indicates that the water-, glycerol-, and hydrogen peroxide-transporting channel aquaporin-3 (AQP3) plays a key role in various processes involved in keratinocyte function, and abnormalities in this channel have been observed in several human skin diseases. Here, we discuss the data linking AQP3 to keratinocyte proliferation, migration, differentiation, and survival as well as its role in skin properties and functions like hydration, water retention, wound healing, and barrier repair. We also discuss the mechanisms regulating AQP3 levels, localization, and function and the anomalies in AQP3 that are associated with various skin diseases.

Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor Erlotinib Induces Dry Skin via Decreased in Aquaporin-3 Expression

An adverse reaction of dry skin occurs frequently during treatment with anticancer epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs). In this study, we conducted basic research to clarify the mechanism of EGFR-TKI-induced dry skin and propose new treatments or preventative measures. Dermal water content was significantly lower in the erlotinib-treated mice than in the control group. An assessment of the expression levels of functional genes in the skin revealed that only the expression of the water channel aquaporin-3 (AQP3) was significantly decreased in the erlotinib-treated group. When erlotinib was added to epidermal keratinocyte HaCaT cells, the expression levels of both AQP3 mRNA and protein decreased. Erlotinib treatment also significantly decreased the expression levels of phospho-EGFR and phospho-extracellular signal-regulated kinase (ERK), both in HaCaT cells and mouse skin. Dry skin due to erlotinib may be caused by the decreased expression of AQP3 in the skin, thereby limiting water transport from the vascular side to the corneum side. The decrease in AQP3 may also be attributable to ERK suppression via inhibition of EGFR activity by erlotinib. Therefore, substances that increase AQP3 expression may be effective for erlotinib-induced dry skin.

Keratinocyte aquaporin-3 expression induced by histone deacetylase inhibitors is mediated in part by peroxisome proliferator-activated receptors (PPARs)

The water and glycerol channel, aquaporin-3 (AQP3), plays an important role in the skin epidermis, with effects on hydration, permeability barrier repair and wound healing; therefore, information about the mechanisms regulating its expression is important for a complete understanding of skin function physiologically and in disease conditions. We previously demonstrated that histone deacetylase inhibitors (HDACi) induce the mRNA and protein expression of AQP3, in part through the p53 family, transcription factors for which acetylation is known to affect their regulatory activity. Another set of transcription factors previously shown to induce AQP3 expression and/or regulate skin function are the peroxisome proliferator-activated receptors (PPARs). Since there are reports that PPARs are also acetylated, we examined the involvement of these nuclear hormone receptors in HDACi-induced AQP3 expression. We first verified that a PPARγ agonist upregulated AQP3 mRNA and protein levels and that this increase was blocked by a PPARγ antagonist. We then showed that the PPARγ antagonist also inhibited AQP3 expression induced both by a broad-spectrum HDACi and an HDAC3-selective inhibitor. Interestingly, a PPARα antagonist also inhibited HDACi-induced AQP3 expression. These antagonist effects were observed in both primary mouse and normal human keratinocytes. Furthermore, PPARγ overexpression enhanced HDACi-stimulated AQP3 mRNA levels. Thus, our results suggest that PPARγ and/or PPARα may play a role in regulating AQP3 levels in the skin; based on the ability of PPAR agonists to promote epidermal differentiation and/or inhibit proliferation, topical PPAR agonists might be considered as a therapy for hyperproliferative skin disorders, such as psoriasis.

Plant plasma membrane vesicles interaction with keratinocytes reveals their potential as carriers

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Broccoli root vesicles showed stability and high entrapment efficiency.

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Nanoencapsulation with membrane vesicles provide an efficient system for keratinocytes cell delivery.

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Effectivity is probed by penetrating in skin layers.

During the last few years, membrane vesicles (as exovesicles) have emerged as potential nanocarriers for therapeutic applications. They are receiving attention due to their proteo-lipid nature, size, biocompatibility and biodegradability. In this work, we investigated the potential use of isolated root plasma membrane vesicles from broccoli plants as nanocarriers. For that, the entrapment efficiency and integrity of the vesicles were determined. Also, the delivery of keratinocytes and penetrability through skin were studied. The results show that the broccoli vesicles had high stability, in relation to their proteins, and high entrapment efficiency. Also, the interaction between the vesicles and keratinocytes was proven by the delivery of an encapsulated fluorescent product into cells and by the detection of plant proteins in the keratinocyte plasma membrane, showing the interactions between the membranes of two species of distinct biological kingdoms. Therefore, these results, together with the capacity of brassica vesicles to cross the skin layers, detected by fluorescent penetration, enable us to propose a type of nanocarrier obtained from natural plant membranes for use in transdermal delivery.

Molecular Mechanisms at the Basis of Pharmaceutical Grade Triticum vulgare Extract Efficacy in Prompting Keratinocytes Healing

BACKGROUND

It has been shown that many plant- or microbial-derived oligos and polysaccharides may prompt tissue repair. Among the different extracts that have been studied, the aqueous one of Triticum vulgare (TVE) that was obtained from a whole germinated plant has been proven to have different biological properties that are useful in the process of wound healing. Nevertheless, with the long tradition of its use in pharmaceutical cream and ointments, especially in Italy, a new protocol was recently proposed (and patented) to improve the extraction process.

METHODS

In a simplified in vitro model, human keratinocyte monolayers were scratched and used to run time lapse experiments by using time lapse video microscopy (TLVM) to quantify reparation rate while considering a dose-response effect. Contemporarily, the molecular mechanisms that are involved in tissue repair were studied. In fact, key biomarkers that are involved in remodeling, such as MMP-2 and MMP-9, and in matrix structure assembly, such as collagen I, elastin, integrin αV and aquaporin 3, were evaluated with gene expression analyses (RT-PCR) and protein quantification in western blotting.

RESULTS

All TVE doses tested on the HaCat-supported cell proliferation. TVE also prompted cell migration in respect to the control, correctly modulating the timing of metalloproteases expression toward a consistent and well-assessed matrix remodeling. Furthermore, TVE treatments upregulated and positively modulated the expression of the analyzed biomarkers, thus resulting in a better remodeling of dermal tissue during healing.

CONCLUSIONS

The in vitro results on the beneficial effects of TVE on tissue elasticity and regeneration may support a better understanding of the action mechanism of TVE as active principles in pharmaceutical preparation in wound treatment.

Obesity-associated insulin resistance adversely affects skin function

The aim of this study was to identify changes in skin function associated with obesity and the mechanisms underlying these changes. Functional changes and gene expression in skin were investigated in C57BL/6J mice fed either a control or high-fat diet (HFD). The insulin responsiveness of the skin and skeletal muscle was also evaluated. The effects of inhibiting insulin signaling and altered glucose concentration on skin function-associated molecules and barrier function were analyzed in keratinocytes. HFD-fed mice were not only severely obese, but also exhibited impaired skin barrier function and diminished levels of glycerol transporter aquaporin-3, keratins, and desmosomal proteins involved in maintaining skin structure. Moreover, the expression of cell cycle regulatory molecules was altered. Insulin signaling was attenuated in the skin and skeletal muscle of HFD-fed mice. In keratinocytes, inhibition of insulin signaling leads to decreased keratin expression and diminished barrier function, and higher glucose concentrations increased the expression of CDK inhibitor 1A and 1C, which are associated with cell-cycle arrest. Obesity-associated impairment of skin function can be attributed to structural fragility, abnormal glycerol transport, and dysregulated proliferation of epidermal cells. These alterations are at least partly due to cutaneous insulin resistance and hyperglycemia.

High Throughput Screening of Additives Using Factorial Design to Promote Survival of Stored Cultured Epithelial Sheets

There is a need to optimize storage conditions to preserve cell characteristics during transport of cultured cell sheets from specialized culture units to distant hospitals. In this study, we aimed to explore a method to identify additives that diminish the decrease in the viability of stored undifferentiated epidermal cells using multifactorial design and an automated screening procedure. The cultured cells were stored for 7–11 days at 12°C in media supplemented with various additives. Effects were evaluated by calcein staining of live cells as well as morphology. Twenty-six additives were tested using (1) a two-level factorial design in which 10 additives were added or omitted in 64 different combinations and (2) a mixture design with 5 additives at 5 different concentrations in a total of 64 different mixtures. Automated microscopy and cell counting with Fiji enabled efficient processing of data. Significant regression models were identified by Design-Expert software. A calculated maximum increase of live cells to 37 ± 6% was achieved upon storage of cell sheets for 11 days in the presence of 6% glycerol. The beneficial effect of glycerol was shown for epidermal cell sheets from three different donors in two different storage media and with two different factorial designs. We have thus developed a high throughput screening system enabling robust assessment of live cells and identified glycerol as a beneficial additive that has a positive effect on epidermal cell sheet upon storage at 12°C. We believe this method could be of use in other cell culture optimization strategies where a large number of conditions are compared for their effect on cell viability or other quantifiable dependent variables.

Blue Light Induces Down-Regulation of Aquaporin 1, 3, and 9 in Human Keratinocytes

The development in digital screen technology has exponentially increased in the last decades, and many of today’s electronic devices use light-emitting diode (LED) technology producing very strong blue light (BL) waves. Long-term exposure at LED-BL seems to have an implication in the dehydration of the epidermis, in the alterations of shape and number of the keratinocytes, and in the aging of the skin. Aquaporins (AQPs) are water membrane channels that permeate both water and glycerol and play an important role in the hydration of epidermis, as well as in proliferation and differentiation of keratinocytes. Thus, we have hypothesized that AQPs could be involved in the aging of the skin exposed to LED-BL. Therefore, we have examined the expression of AQPs in human keratinocytes exposed to LED-BL at dose of 45 J/cm², used as an in vitro model to produce the general features of photo aging of the skin. The aim was to verify if LED-BL induces changes of the basal levels of AQPs. The keratinocytes exposure to LED-BL produced an increase of reactive oxygen species (ROS), an activation of 8-hydroxy-2’-deoxyguanosine (8-OHdG), an alteration of proliferating cell nuclear antigen (PCNA), and a down-regulation of AQP1, 3 and 9. These findings are preliminary evidences that may be used as starting points for further investigations about the mechanistic involvement of AQP1, 3, and 9 in LED-BL-induced skin aging.

Phenotypic and lipidomic characterization of primary human epidermal keratinocytes exposed to simulated solar UV radiation

BACKGROUND

Ultraviolet (UV) radiation is known to be one of the most important environmental hazards acting on the skin. The most part of UV radiation is absorbed in the epidermis, where keratinocytes are the most abundant and exposed cell type. Lipids have an important role in skin biology, not only for their important contribution to the maintenance of the permeability barrier but also for the production and storage of energy, membrane organization and cell signalling functions. However, the effects on the lipid composition of keratinocytes under UV radiation are little explored.

OBJECTIVE

The present work aims to explore the effects on the phenotype and lipid content of primary human keratinocytes exposed to simulated solar UV radiation.

METHODS

Keratinocytes were exposed to a single (acute exposure) and repeated simulated solar UV irradiations for 4 weeks (chronic exposure). Cell viability and morphology were explored, as well as the production of reactive oxygen species. Then, lipid extracts were analysed through liquid chromatography coupled to mass spectrometry (LC-MS) and the data generated was processed using the ROIMCR chemometric methodology together with partial least squares discriminant analysis (PLS-DA), to finally reveal the most relevant lipid changes that occurred in keratinocytes upon UV irradiation. Also, the potential induction of keratinocyte differentiation was explored by measuring the increase of involucrin.

RESULTS

Under acute irradiation, cell viability and morphology were not altered. However, a general increase of phosphatidylcholines (PC) phosphatidylethanolamines (PE) and phosphatidylglycerol (PG) together with a slight sphingomyelin (SM) decrease were found in UV irradiated cells, among other changes. In addition, keratinocyte cultures did not present any differentiation hallmark. Contrary to acute-irradiated cells, in chronic exposures, cell viability was reduced and keratinocytes presented an altered morphology. Also, hallmarks of differentiation, such as the increase of involucrin protein and the autophagy induction were detected. Among the main lipid changes that accompanied this phenotype, the increase of long-chain ceramides, lysoPC and glycerolipid species were found.

CONCLUSION

Important lipid changes were detected under acute and chronic UV irradiation. The lipid profile under chronic exposure may represent a lipid fingerprint of the keratinocyte differentiation phenotype.

Nuclear Receptor Regulation of Aquaglyceroporins in Metabolic Organs

Nuclear receptors, such as the farnesoid X receptor (FXR) and the peroxisome proliferator-activated receptors gamma and alpha (PPAR-γ, -α), are major metabolic regulators in adipose tissue and the liver, where they govern lipid, glucose, and bile acid homeostasis, as well as inflammatory cascades. Glycerol and free fatty acids are the end products of lipid droplet catabolism driven by PPARs. Aquaporins (AQPs), a family of 13 small transmembrane proteins, facilitate the shuttling of water, urea, and/or glycerol. The peculiar role of AQPs in glycerol transport makes them pivotal targets in lipid metabolism, especially considering their tissue-specific regulation by the nuclear receptors PPARγ and PPARα. Here, we review the role of nuclear receptors in the regulation of glycerol shuttling in liver and adipose tissue through the function and expression of AQPs.

Plasmodium parasite exploits host aquaporin-3 during liver stage malaria infection

Within the liver a single Plasmodium parasite transforms into thousands of blood-infective forms to cause malaria. Here, we use RNA-sequencing to identify host genes that are upregulated upon Plasmodium berghei infection of hepatocytes with the hypothesis that host pathways are hijacked to benefit parasite development. We found that expression of aquaporin-3 (AQP3), a water and glycerol channel, is significantly induced in Plasmodium-infected hepatocytes compared to uninfected cells. This aquaglyceroporin localizes to the parasitophorous vacuole membrane, the compartmental interface between the host and pathogen, with a temporal pattern that correlates with the parasite’s expansion in the liver. Depletion or elimination of host AQP3 expression significantly reduces P. berghei parasite burden during the liver stage and chemical disruption by a known AQP3 inhibitor, auphen, reduces P. falciparum asexual blood stage and P. berghei liver stage parasite load. Further use of this inhibitor as a chemical probe suggests that AQP3-mediated nutrient transport is an important function for parasite development. This study reveals a previously unknown potential route for host-dependent nutrient acquisition by Plasmodium which was discovered by mapping the transcriptional changes that occur in hepatocytes throughout P. berghei infection. The dataset reported may be leveraged to identify additional host factors that are essential for Plasmodium liver stage infection and highlights Plasmodium’s dependence on host factors within hepatocytes.

Plasmodium parasites undergo an obligatory morphogenesis and replication within the liver before they invade red blood cells and cause malaria. The liver stage is clinically silent but essential for the Plasmodium parasite to complete its life cycle. During this time, the parasite relies on the host cell to support a massive replication event, yet host factors that are critical to this expansion are largely unknown. We identify human aquaporin-3 (AQP3), a water and glycerol channel, as essential for the proper development of the parasite within the liver cell. AQP3 localizes to the parasitophorous vacuole membrane, the interface between the host cytoplasm and the parasite, possibly aiding in the nutritional uptake for the parasite. Genetic disruption or treatment with the AQP3 inhibitor auphen, reduces parasite load in liver and blood cells.

Forensic application of epidermal AQP3 expression to determination of wound vitality in human compressed neck skin

In forensic practices, it is often difficult to determine wound vitality in compression marks of the neck with naked eyes. AQP1 and AQP3 are the major water channels associated with skin. Thus, we immunohistochemically examined the expression of AQP1 and AQP3 in neck skin samples to discuss their forensic applicability to determination of the wound vitality. Skin samples were obtained from 56 neck compression cases (hanging, 35 cases; strangulation, 21 cases). The intact skin from the same individual was taken as a control. Although AQP1 was immnunostained in dermal capillaries in both the neck compression marks and intact skin samples, there was no significant difference in the magnitude of AQP1 expression between both groups. On the contrary, AQP3-positive signals could be faintly detected in uninjured skin samples, and the positive signals seemed more intense in the keratinocytes in compression regions. Morphometrical analyses revealed that the ratio of AQP3-expressed keratinocytes was significantly enhanced in neck compression regions, compared with control groups. From the viewpoints of forensic pathology, immunohistochemical detection of AQP3 in the neck skin can be considered a valuable marker to diagnose the trace of antemortem compression.