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Medical practice has proven that chronic wounds can be treated successfully if the dressing is chosen according to the healing phase of the wound. Correct intervention from the hemostasis and inflammatory phase can prevent oxidative stress and ensure optimal conditions for healing. It is important to design a new wound dressing that does not cause additional injury, has an antioxidant effect, removes dead cells, and promotes wound healing. Considering that the traditional dressings are not moisture-retentive, we proposed an alginate-gum arabic polymeric matrix enhanced with cerium oxide nanoparticles. The cryogels were prepared by cross-linking polysaccharides and cerium oxide nanoparticles via calcium cations to form a sponge-like structure. The blend of micro- and macro-pores provides a suitable environment for nutrient distribution and keeps an adequate moisture level, mimicking the functions of the native cellular matrix. The release of cerium oxide nanoparticles occurs gradually, at the same time as the degradation of the biopolymer, promoting the attachment and viability of keratinocytes and fibroblast cells. It was found that stimulating epithelial regeneration is improved through the antioxidant effect and the adsorption capacity of hemoglobin. The results also indicate good in vitro biocompatibility and recommend them as promising dressings for skin wound treatments., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Arsenic is a widespread environmental carcinogen, and its carcinogenic mechanism has been the focus of toxicology. N 6 -methyladenosine (m 6 A) binding protein YTH domain family protein 2 (YTHDF2) performs various biological functions by degrading m 6 A-modified mRNAs. However, the m 6 A-modified target mRNA of YTHDF2 in regulating arsenic carcinogenesis remains largely unknown. To explore the effect of YTHDF2 in regulating arsenic carcinogenicity, we exposed the human keratinocyte HaCaT cells to 1 μM sodium arsenite for 50 generations to create a cell model of arsenic carcinogenesis (HaCaT-T). Our results demonstrated that YTHDF2 protein levels were higher in HaCaT-T cells than HaCaT cells, and knockdown of YTHDF2 significantly inhibited arsenic-induced malignant phenotypes. In addition, m 6 A levels in HaCaT-T cells were remarkably elevated, accompanied by abnormal expression of m 6 A methyltransferases and m 6 A demethylases. Mechanistically, YTHDF2 bound to p53-induced death domain protein 1 (PIDD1) mRNA in an m 6 A-dependent manner, thereby promoting the degradation of PIDD1 mRNA. Moreover, the decay of PIDD1 mRNA inhibited the formation of PIDDosome complex that is essential for activating the apoptosis initiator caspase-2, leading to a decrease in caspase-2-dependent mitochondrial apoptosis and subsequently promoting the malignant phenotypes of HaCaT-T cells. Collectively, our study reveals the role of YTHDF2 in arsenic-induced malignant phenotypes of human keratinocytes through direct interaction with PIDD1 mRNA in an m 6 A-dependent manner, which provides new insight into the precise mechanism underlying arsenic-induced skin cancer., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The phase separation of N 6 -methyladenosine (m 6 A) binding protein YTHDF2 plays a vital role in arsenic-induced skin damage, and YTHDF2 can bind to m 6 A-methylated mRNA of tumor suppressor PTEN. However, whether and how YTHDF2 phase separation regulates PTEN involved in arsenic-induced malignant transformation of keratinocytes remains blank. Here, we established arsenite-induced transformation models with stable expression of wild-type YTHDF2 or mutant YTHDF2 protein in vitro and in vivo. We found that the YTHDF2 protein underwent phase separation during arsenite-induced malignant transformation of keratinocytes, and YTHDF2 phase separation promoted the malignant phenotype of keratinocytes. Mechanically, YTHDF2 phase separation reduced PTEN protein levels, which in turn activated the pro-survival AKT signal. The binding of YTHDF2 to multiple m 6 A sites on PTEN mRNA drove YTHDF2 phase separation, inhibiting PTEN translation initiation and thus reducing PTEN protein levels. YTHDF2 phase separation recruited translation-initiation-factor kinase EIF2AK1 to phosphorylate eIF2α, thereby inhibiting translation initiation of poly-m 6 A-methylated PTEN mRNA. Furthermore, arsenite-induced oxidative stress triggered YTHDF2 phase separation by increasing m 6 A levels of PTEN mRNA. Our results demonstrated that YTHDF2 phase separation promotes arsenite-induced malignant transformation by inhibiting PTEN translation in a poly-m 6 A-dependent manner. This study sheds light on arsenic carcinogenicity from the novel aspect of m 6 A-mediated YTHDF2 phase separation., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Nano- and microplastics (NMPs), ubiquitous in the environment, pose significant health risks. We report for the first time a comprehensive study using in-vitro, in-vivo, and ex-vivo models to investigate the penetration and inflammatory effects of fragmented polystyrene (fPS) on human skin, including the analysis of both penetration depth and fPS amounts that penetrate the skin. Human keratinocyte (HaCaT) and human dermal fibroblast (HDF) cells exposed to fPS exhibited notable internalization and cytotoxicity. In a 3D human skin model, fPS particles penetrated the dermal layer within one hour, with an average maximum penetration of 4.7 μg for particles smaller than 2 µm. Similarly, mouse dorsal skin and human abdominal skin models confirmed fPS penetration. RNA sequencing revealed substantial upregulation of inflammatory genes, including IL-1α, IL-1β, IL-18, IL-6, IL-8, ICAM-1, FOS, and JUN, following fPS exposure. These findings were validated at both the mRNA and protein levels, indicating a robust inflammatory response. Notably, the inflammatory response in both the 3D human skin and mouse models increased in a dose-dependent manner, underscoring the toxicological impact of fPS on skin health. This study provides crucial insights into the mechanisms through which NMPs affect human health and underscores the need for further research to develop effective mitigation strategies., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: Psoriasis is a chronic inflammatory skin disease characterized by a complex pathogenesis involving various types of cells and cytokines. Among those, the pro-inflammatory cytokine IL-23/IL-17A axis plays a crucial role in the development and rapid progression of psoriasis. Phenformin, a derivative of metformin and a member of the biguanide class of drugs, exhibits superior anti-inflammatory and anti-tumor efficacy compared to metformin. However, the potential role of phenformin in anti-psoriatic skin inflammation has not been explored., Methods: In this study, we utilized a mouse model of psoriasis and an in vitro model using human keratinocytes to investigate whether phenformin can suppress psoriasis-like inflammatory responses., Results: Our results demonstrate that the topical application of phenformin significantly inhibited acute skin inflammatory responses in the psoriasis mouse model induced by imiquimod (IMQ). Additionally, phenformin suppressed the expression of psoriasis-related cytokines IL-17, IL-23, IL-8, and S100A8/S100A9 in an in vitro psoriatic keratinocyte model induced by IMQ. Furthermore, we found that IMQ-induced psoriatic skin and IMQ-treated keratinocytes exhibited high expression of the c-Myc gene, which was downregulated by phenformin. The c-Myc inhibitor JQ1 similarly inhibited the psoriatic inflammatory response and the expression of psoriasis-related cytokines in both in vitro and in vivo models., Conclusion: phenformin ameliorates the psoriasis-like inflammatory response by inhibiting c-Myc expression in keratinocytes, suggesting its potential as a topical drug for the treatment of psoriasis., Competing Interests: Declaration of competing interest All authors declare no potential conflict of interest with respect to the research, authorship and publication of this article., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Primary endpoints of clinical studies investigating treatments for actinic keratosis (AK) are mainly based on clinical evaluation, but a recent study showed that in AK, clinical classification according to Olsen and the extent of keratinocyte atypia do not necessarily correlate. The influence of the epidermal extent of atypia on treatment efficacy is usually not investigated and therefore remains largely unknown., Objective: To evaluate whether the extent of keratinocyte atypia influences efficacy of photodynamic therapy (PDT) when treating AK., Methods: We performed a post-hoc analysis of histological (keratinocyte intraepithelial neoplasia (KIN)), and clinical (Olsen) data of biopsied lesions of three pivotal studies evaluating PDT using 10 % aminolevulinic acid (ALA) gel or vehicle and narrow- or broad-spectrum red light lamps., Results: Overall, 514 biopsied lesions were considered. Clearance rates after red light PDT with 10 % ALA gel were comparable for KIN I-III (88.2 %, 92.0 % and 87.9 %) and Olsen I-II lesions for any given lamp type. Generally, clearance rates were higher using narrow- compared to broad-spectrum lamps. For both lamp types, the variation in clearance rates from KIN I-III was low. Clearance was lower with vehicle., Limitations: Varying lesion numbers in the subgroups and a remaining risk of bias due to the biopsies are potential limitations., Conclusion: Our results suggest that red light PDT with 10 % ALA gel is an effective treatment option for AK regardless of the extent of keratinocyte atypia., Competing Interests: Declaration of competing interest R.-M.S. has received grants from Almirall, Biofrontera, Dr. Wolff-Group, Galderma, Leo Pharma, Novartis, and photonamic for clinical studies; has received consulting fees and speakers’ honoraria from Abbvie, Almirall, Eli Lilly, Galderma, Janssen, and Leo Pharma, and is Vice-President of the EURO-PDT Society; T.D. has received funding from Almirall, Biofrontera, Galderma, Meda, Schulze & Böhm GmbH for research support; has received consulting fees from Almirall, Biofrontera, GSK, Dr. Pfleger, Galderma, Janssen-Cilag, Leo, Meda, Neracare, Novartis, Scibase, smartinmedia AG, UCB, Vichy; and has received speakers honoraria from Almirall, Biofrontera, Galderma, GSK, infectopharm, Leo, Meda, Neracare, Novartis, Janssen-Cilag, Riemser; E.B. and U.R. have no conflict of interest to declare., (Copyright © 2024. Published by Elsevier B.V.)

Dry skin induced chronic pruritus is an increasingly common and debilitating problem, especially in the elderly. Although keratinocytes play important roles in innate and adaptive immunity and keratinocyte proliferation is a key feature of dry skin induced chronic pruritus, the exact contribution of keratinocytes to the pathogenesis of dry skin induced chronic pruritus is poorly understood. In this study, we generated the acetone-ether-water induced dry skin model in mice and found that epidermal hyperplasia induced by this model is partly dependent on the β-catenin signaling pathway. XAV939, an antagonist of β-catenin signaling pathway, inhibited epidermal hyperplasia in dry skin model mice. Importantly, dry skin induced chronic pruritus also dramatically reduced in XAV939 treated mice. Moreover, acetone-ether-water treatment-induced epidermal hyperplasia and chronic itch were decreased in Trpv4 -/- mice. In vitro, XAV939 inhibited hypo-osmotic stress induced proliferation of HaCaT cells, and hypo-osmotic stress induced proliferation of in HaCaT cells and primary cultured keratinocytes were also significantly reduced by blocking TRPV4 function. Finally, thymic stromal lymphopoietin release was examined both in vivo and in vitro, which was significantly inhibited by XAV939 treatment and Trpv4 deficiency, and anti-TSLP antibody treatment significantly decreased AEW-induced scratching behavior. Overall, our study revealed a unique ability of TRPV4 expressing keratinocytes in the skin, which critically mediated dry skin induced epidermal hyperplasia and chronic pruritus, thus provided novel insights into the development of therapies for chronic pruritus in the elderly., Competing Interests: Declaration of competing interest The authors have declared that no conflict of interest exists., (Copyright © 2024. Published by Elsevier B.V.)

Fine particulate matter (PM 2.5 ) induces a range of diseases, including skin disorders, through inflammatory responses. In this study, we investigated the novel mechanisms by which PM 2.5 causes skin inflammation in human keratinocytes HaCaT. We observed increased protein expression of cyclooxygenase-2 (COX-2) and the production of prostaglandin E2 (PGE2) in PM 2.5 -treated HaCaT cells. To identify the pathways promoting the expression of these inflammatory proteins, we conducted a phospho-kinase antibody array and confirmed that the phosphorylation levels of JNK and p38 were increased by PM 2.5 -treated HaCaT cells. Further investigation of the phosphorylation levels of mitogen-activated protein kinases (MAPKs) and upstream signals revealed that PM 2.5 activated the MKK4/7-JNK-c-Jun and MKK3/6-p38-p70 S6K signaling pathways, while the phosphorylation level of ERK1/2 remained unchanged. HaCaT cells treated with PM 2.5 phosphorylated Mixed-lineage kinase 3 (MLK3), an upstream regulator of p38 and JNK. Furthermore, inhibition of ROS production by N-Acetylcysteine (NAC) treatment inhibited MLK3 phosphorylation. Taken together, ROS production induced by PM 2.5 activated the MLK3 signaling pathway and induced skin inflammation., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are severe adverse drug reactions with extensive keratinocyte death. Carbamazepine (CBZ), the most commonly implicated drug in SJS/TEN, is metabolized by the cytochrome P450 enzyme 3A4 (CYP3A4) into carbamazepine-10,11-epoxide (CBZE) in the liver. While CD8 + cytotoxic T cells play an important role in SJS/TEN, the underlying mechanism of exuberant immune response by CD8 + T cells in these conditions remains incompletely understood., Objectives: To examine the expression of NLRP3 inflammasome and their skin migration in CBZE-induced SJS/TEN., Methods: The expression of the NLRP3 inflammasome complex in skin lesions, sera, and blister fluids of SJS/TEN patients were analyzed by immunohistochemistry and enzyme-linked immunosorbent assay. NLRP3 formation and CD8 + T cell activation status and their functions were examined by immunoblotting, immunofluorescence, and chemotaxis assays., Results: The expression of the NLRP3 inflammasome complex was greatly increased in skin lesions of SJS/TEN patients. Moreover, IL-1β and IL-18 levels in sera and blister fluids of SJS/TEN patients were approximately 3-fold higher than those in healthy individuals, with a linear correlation between IL-1β levels and disease activity. CBZE induced NLRP3 inflammasome formation, upregulated CXCL9/CXCL10 levels, and activated CD8 + cytotoxic T cell functions via IL-1β/IL-1R or IL-18/IL-18R signaling in SJS/TEN keratinocytes, which promoted CD8 + cytotoxic T cell migration in SJS/TEN patients., Conclusion: This study showed that CBZE promoted NLRP3 inflammasome formation and strengthened the activation and function of CD8 + cytotoxic T cells in the skin, which contributed to the initiation and progression of SJS/TEN., (Copyright © 2024 Japanese Society for Investigative Dermatology. Published by Elsevier B.V. All rights reserved.)

Nano-titanium dioxide (Nano-TiO 2 ) is extensively utilized across various industries and has the capacity to penetrate human tissues through multiple biological barriers. The HaCaT cell line, as one of human immortalized keratinocytes, is usually used as a model for studying skin drug toxicology. The objective was to assess the toxic effects of nano-TiO 2 on HaCaT cells and to trigger pyroptosis. We used MTT method to evaluate the effects of three nano-TiO 2 particle sizes (15 nm, 30 nm and 80 nm) on cell viability at different concentrations. Subsequently, we used LDH, Hoechst 33342 and propidium iodide (PI) double staining, scanning electron microscopy (SEM), Western blotting (WB) and real-time quantitative polymerase chain reaction (RT-qPCR) to evaluate the effects of different particle sizes on cells at the same concentration. Our findings indicated that HaCaT cell viability diminished with increasing nano-TiO 2 concentrations. Moreover, nano-TiO 2 increased LDH level in cellular supernatant. Fluorescence double staining, SEM, WB and RT-qPCR showed that nano-TiO 2 induced cell membrane damage by activating pyroptosis pathway of NLRP3/caspase-1/GSDMD. These results suggest that nano-TiO 2 toxicity in HaCaT cells is influenced by both dose and particle size, and is associated with the induction of pyroptosis. Frequent and large exposures to nano- TiO 2 in daily life may cause serious health hazards., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Lingyun Xu reports financial support was provided by Medical Products Administration of Hubei Province. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Furanoids are a class of contaminants prevalent in both airborne and occupational environments, with potential health implications through inhalation, oral ingestion, and skin penetration. Given their diminutive molecular size, there is a presumption that furanoids can readily permeate the skin. To systematically explore this presumption, we investigated the skin absorption and toxicity of a series of furans (furfuryl alcohol, furfuryl acetate, furfural, methyl 2-furoate, and 5-methylfurfural) using in silico, in vitro, and in vivo models. The in vitro permeation test (IVPT) from neat and aqueous suspension (5 mM) of furans demonstrated a facile absorption through pig and nude mouse skins. The lipophilicity of furans significantly influenced skin deposition, with higher lipophilicity displaying greater deposition. However, an opposing trend emerged in the receptor compartment accumulation. In barrier-defective skin simulating atopic dermatitis (AD) and psoriasis, enhanced deposition occurred with more hydrophilic furans but not with the more lipophilic ones. In the cell-based study, furanoids induced the proliferation of keratinocytes and skin fibroblasts except for the compounds with the aldehyde group (furfural and 5-methylfurfural). Both furfuryl acetate and 5-methylfurfural activated keratinocytes via the overexpression of COX-2 and PGE 2 by 1.5‒2-fold. This stimulation involved the mitogen-activated protein kinase (MAPK) signaling pathway. For the in vivo mouse skin treatment, we selected furfuryl acetate (hydrophilic) and 5-methylfurfural (lipophilic). Both furans showed different patterns of skin lesions, where repeated application of furfuryl acetate caused epidermal hyperplasia and scaling, while 5-methylfurfural predominantly evoked skin inflammation and barrier disintegration. Toxicokinetics analysis revealed a higher plasma concentration of topically applied furfuryl acetate than that of the 5-methylfurfural (5.04 versus 2.34 nmol/ml), resulting in the mild injury of furfuryl acetate-treated peripheral organs. Conversely, no notable adverse effects on organs were observed for the 5-methylfurfural. This study established the relationship between cutaneous absorption and the toxicity of furans following skin exposure., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Hydrochlorothiazide (HCTZ) is a widely utilized diuretic for the treatment of hypertension. The photosensitivity of HCTZ has been recognized for six decades, with UVA being considered the primary culprit. However, the precise molecular mechanism of HCTZ sensitizing skin to UV radiation remains unknown. In this study, we demonstrate that HCTZ exacerbates UVB-induced photosensitivity in normal skin by disrupting the DNA damage response, a crucial network responsible for maintaining epidermal homeostasis. Here, we found that HCTZ aggravates UVB-induced mouse skin damage. Through transcriptomic and proteomic profiling, we have found that the cell cycle and p53 signaling pathway may contribute to the photosensitivity caused by HCTZ. In keratinocytes, HCTZ promotes the transition from G1 to S phase and inhibits the p53 signaling pathway after exposure to UV radiation. We have found that HCTZ enhances the accumulation of DNA damage induced by UVB and impairs nucleotide excision repair (NER), which is responsible for repairing UVB-induced DNA lesions, by inhibiting the expression of NER-related genes and shortening the duration of G1 phase. Furthermore, pharmacologically inducing G1 arrest eliminates HCTZ-induced accumulation of damaged DNA. These findings unveil an unknown mechanism through which HCTZ impairs NER and interferes with UVB-induced cell cycle arrest, ultimately leading to improper response towards DNA damage and increased skin sensitivity., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

In this work, chitosan/collagen-based membranes loaded with 2,3-dihydrobenzofuran (2,3-DHB) were developed through a simple solvent-casting procedure for use in the treatment of cutaneous Leishmaniasis. The obtained membranes were characterized by elemental analysis, FTIR, TG, DSC, and XRD. Porosity, swelling, mechanical properties, hydrophilicity, and antioxidant activity were analyzed. In addition, assessment to the biocompatibility, through fibroblasts/keratinocytes and in vitro wound healing essays were performed. The obtained results show that the new 2,3-DHB loaded chitosan/collagen membrane presented high porosity and swelling capacity as well as maximum strength, hydrophilicity, and antioxidant activity higher in relation to the control. The tests of antileishmanial activity and the AFM images demonstrate great efficacy of inhibition growth of the parasite, superior to those from the standard therapeutic agent that is currently used: Amphotericin B. The new membranes are biocompatible and stimulated the proliferation of keratinocytes. SEM images clearly demonstrate that fibroblasts were able to adhere, maintained their characteristic morphology. The healing test evidenced that the membranes have adequate environment for promoting cell proliferation and growth. As the conventional treatments often use drugs with high toxicity, the as-developed new membranes proved to be excellent candidate to treat cutaneous Leishmaniasis and can be clearly indicated for further advanced studies in vivo., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Edvani Curti Muniz reports financial support was provided by National Council for Scientific and Technological Development. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Engineered matrices with aligned microarchitectures are pivotal in regulating the fibroblast-to-myofibroblast transition, a critical process for wound healing and scar reduction. However, developing a three-dimensional (3D) aligned matrix capable of effectively controlling this transition remains challenging. Herein, we developed a cell-adaptive hydrogel with highly oriented microporous structures, fabricated through bioprinting of thermo/ion/photo-crosslinked gelatin methacrylate/sodium alginate (GelMA/SA) incorporating shear-oriented polyethylene oxide (PEO) filler. The synergistic interactions among GelMA, PEO, and SA yield a homogeneous mixture conducive to the printing of biomimetic 3D constructs with anisotropic micropores. These anisotropic micropores, along with the biochemical cues provided by the GelMA/PEO/SA scaffolds, enhance the oriented spreading and organization of fibroblasts. The resultant spread and aligned cellular morphologies promote the transition of fibroblasts into myofibroblasts. By co-culturing human keratinocytes on the engineered dermal layer, we successfully create a bilayer skin construct, wherein the keratinocytes establish tight junctions accompanied by elevated expression of cytokeratin-14, while the fibroblasts display a highly spread morphology with increased fibronectin expression. The printed hydrogels accelerate full-thickness wound closure by establishing a bioactive microenvironment that mitigate inflammation and stimulate angiogenesis, myofibroblast transition, and extracellular matrix remodeling. This anisotropic hydrogel demonstrates substantial promise for applications in skin tissue engineering., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Chronic wounds can develop as a result of prolonged inflammation during the healing process, which can happen due to bacterial infection. Therefore, preventing infection and controlling inflammation can accelerate wound healing. Antimicrobial peptides have different protective properties in addition to antimicrobial activity. Some of these activities include the stimulation of cytokine or chemokine synthesis, the facilitation of chemotaxis and cell proliferation, the acceleration of cell proliferation, the induction of anti-inflammatory responses, and the promotion of wound repair. This study aimed to assess the wound healing potential of a novel in silico-designed antimicrobial peptide. Then, its anti-inflammatory activity was investigated by measuring the level of tumor necrosis factor-α (TNF-α) and transforming growth factor beta (TGF-β) as indicators of the wound healing process. In addition, the influence of the peptide on cell migration was evaluated by a scratch test on human dermal fibroblasts (HDF) and HaCaT cells as a human epidermal keratinocyte cell line. The results showed that our new peptide could act well in inhibiting TNF-α over-secretion while increasing the expression of TGF-β as an anti-inflammatory factor. This peptide showed a significant potential to stimulate HDF and HaCaT cell migration and proliferation. Therefore, using this peptide as an anti-inflammatory component of wound dressings may be promising., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Maryam Tabarzad reports financial support was provided by Shahid Beheshti University of Medical Sciences., (Copyright © 2024 Elsevier Ltd and ISBI. All rights reserved.)

Despite substantial advancements in wound dressing development, effective skin repair remains a significant challenge, largely due to the persistent issue of recurrent infections. Three-dimensional printed constructs that integrate bioactive and antibacterial agents hold significant potential to address this challenge. In this study, a 3D-printed hydrogel scaffold composed of polyallylamine hydrochloride (PAH) and pectin (Pc), incorporated with mupirocin (Mp)-loaded quaternized chitosan nanoparticles (QC NPs) was fabricated. The primary objective of this study was to facilitate a controlled and sustained release of Mp via the QC NPs. The average size of QC-Mp nanoparticles was measured to be 66.05 nm and the average strand diameter and pore size of the 3D-printed construct were measured as 147.22 ± 5.83 and 388.44 ± 14.50 μm, respectively. The hemolysis rate of all scaffolds was below 2 %, indicating that they can be classified as non-hemolytic materials with sufficient blood compatibility. The PAH-Pc/QC-Mp scaffold exhibited significant antibacterial activity, enhanced cell viability in HaCat cells, sustained Mp release until day 7 (⁓60 %), and in-vivo wound healing promotion by stimulation of human keratinocytes. In conclusion, the proposed biocompatible construct demonstrates significant potential for the treatment of chronic and infected wounds by preventing infection and promoting accelerated wound healing., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

There has been a growing interest in skin recovery in both the medical and cosmetics fields, leading to an increasing number of studies reporting diverse materials being utilized for this purpose. Among them, polydeoxyribonucleotide (PDRN) is known for its efficacy in skin repair processes, while Hibiscus sabdariffa (HS) is recognized for its antioxidant, hypolipidemic, and wound healing properties, including its positive impact on mammalian skin and cells. We hypothesized that these characteristics may have a germane relationship during the healing process. Consequently, we induced calli from HS and then extracted PDRN for use in treating human keratinocytes. PDRN (5 μg/mL) had considerable wound healing effects and wrinkle improvement effects. To confirm its function at the molecular level, we performed real-time polymerase chain reaction, western blotting, and immunocytochemistry. Furthermore, genes related to wound healing (MMP9, Nrf2, KGF, VEGF, SOD2, and AQP3) were significantly upregulated. Additionally, the protein expression of MMP9, AQP3, and CAT, which are closely related to wound healing and antioxidant cascades, was considerably enhanced. Based on cellular morphology and molecular-level evidence, we propose that PDRN from calli of HS can improve wound healing in human keratinocytes. Furthermore, its potential to serve as a novel material in cosmetic products is demonstrated., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

Chronic inflammation and infection often lead to delayed healing in skin wounds of patients with diabetes, presenting a significant challenge in clinical wound repair. In an effort to tackle this issue, we explored the utilization of the natural compounds Rhein and chitosan in the creation of a crosslinked in situ gel. Developed as Rhein-chitosan in situ hydrogel (CS-Rh gel), this formulation has the ability to gel at body temperature, making it suitable for irregular wounds of varying shapes. Our experimental investigations have demonstrated its excellent biocompatibility, controlled release of Rhein, biodegradability, anti-inflammatory properties, antibacterial effect, as well as its ability to enhance keratinocyte proliferation and migration. Furthermore, in vivo studies have confirmed that CS-Rh gel can effectively mitigate tissue inflammation, promote collagen deposition, and significantly accelerate wound healing in diabetic mice within a short timeframe of two weeks. Consequently, this innovative approach holds promise as a viable therapeutic strategy for supporting the healing of diabetic wounds in a clinical setting., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: Epidermal growth factor receptor inhibitors (EGFRIs) reduce β-defensin 3 (BD3) from keratinocytes stimulated by S. epidermidis, potentially leading to the development of acneiform rashes in patients undergoing EGFRIs treatment. However, the mechanism through which S. epidermidis induces BD3 via EGFR remains incompletely understood., Objective: To elucidate the BD3 production pathway triggered by S. epidermidis., Methods: To assess the impact of S. epidermidis on EGFR ligand expression, the levels of released EGFR ligands in the keratinocyte culture medium following S. epidermidis stimulation were quantified using ELISA. Subsequently, to confirm the synergistic effect of TGF-α and S. epidermidis, we administered S. epidermidis and TGF-α to the keratinocyte culture medium and measured the expression levels of BD3. In addition, we stimulated Toll-like receptor 2 (TLR2)-knockdown keratinocytes with S. epidermidis and measured the expression levels of TGF-α., Results: While S. epidermidis did not induce EGF and HB-EGF, they increased TGF-α. The expression of BD3 was higher in keratinocytes stimulated by S. epidermidis in the presence of TGF-α, as compared to its absence. Moreover, both S. epidermidis- and TGF-α-induced BD3 were significantly suppressed by cetuximab. The expression levels of TGF-α induced by S. epidermidis were reduced in TLR2-knockdown keratinocytes CONCLUSION: Our findings suggest that S. epidermidis induces the expression of TGF-α in keratinocytes through TLR2, which, in cooperation with TGF-α, stimulates the production of BD3., Competing Interests: Declaration of Competing Interest The authors have no conflict of interest to declare., (Copyright © 2024 Japanese Society for Investigative Dermatology. Published by Elsevier B.V. All rights reserved.)

Read-through therapy suppresses premature termination codons and induces read-through activity, consequently restoring missing proteins. Aminoglycosides are widely studied as read-through drugs in different human genetic disorders, including hereditary skin diseases. Our previous work revealed that aminoglycosides affect COL17A1 nonsense mutations and represent a therapeutic option to alleviate disease severity. However, the amount of restored type XVII collagen (C17) in C17-deficient junctional epidermolysis bullosa keratinocytes was <1% relative to that in normal keratinocytes and was achieved only after high-dose gentamicin treatment, which induced deep transcriptional changes. Therefore, in this study, we designed a strategy combining aminoglycosides with compounds known to reduce their side effects. We developed translational read-through-inducing drug cocktail, version 5 containing low dosage of aminoglycosides, CC-90009, NMDI-14, melatonin, and apocynin that was able to induce about 20% of missing C17 without cell toxicity or an effect on in vitro wound closure. Translational read-through-inducing drugs cocktail, version 5 significantly induced COL17A1 expression and reverted the proinflammatory phenotype of C17-deficient junctional epidermolysis bullosa keratinocytes. Evaluation of this drug cocktail regarding its stability, penetration, and efficacy as a topical treatment remains to be determined. Translational read-through-inducing drug cocktail, version 5 might represent an improved therapeutic strategy for junctional epidermolysis bullosa and for other genetic skin disorders., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Novel pathways of vitamin D3, lumisterol 3 (L3), and tachysterol 3 (T3) activation have been discovered, initiated by CYP11A1 and/or CYP27A1 in the case of L3 and T3. The resulting hydroxymetabolites enhance protection of skin against DNA damage and oxidative stress; stimulate keratinocyte differentiation; exert anti-inflammatory, antifibrogenic, and anticancer activities; and inhibit cell proliferation in a structure-dependent manner. They act on nuclear receptors, including vitamin D receptor, aryl hydrocarbon receptor, LXRα/β, RAR-related orphan receptor α/γ, and peroxisome proliferator-activated receptor-γ, with selectivity defined by their core structure and distribution of hydroxyl groups. They can activate NRF2 and p53 and inhibit NF-κB, IL-17, Shh, and Wnt/β-catenin signaling. Thus, they protect skin integrity and physiology., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Ferroptosis is considered as an immunogenic type of regulated cell death and associated with the pathogenesis of inflammatory skin diseases. However, the involvement and function of ferroptosis in allergic contact dermatitis (ACD) remains unknown., Objective: To explore the role of ferroptosis in ACD. To reveal which type of cells develops ferroptosis in ACD., Methods: We detected the key markers of ferroptosis in 1-Chloro-2,4-dinitrochlorobenzene (DNCB)-induced ACD mice model. We applicated ferrostatin-1 (Fer-1) to restrain ferroptosis in ACD mice and then compared the severity of dermatitis and the level of inflammation and ferroptosis in dermis and epidermis, respectively. Keratinocyte-specific Gpx4 conditional knockout (cKO) mice were used to investigate the function of keratinocyte ferroptosis in the development of ACD. Single-cell RNA sequencing was conducted to analyze the affection of Fer-1 on different type of cells in ACD., Results: Ferroptosis was involved in DNCB-induced ACD mice. Ferroptosis activation was more remarkable in dermis rather than in epidermis. Gpx4 cKO mice showed similar severity of skin dermatitis as control mice. Fer-1 alleviated skin inflammation in mice and reduced ferroptosis in neutrophils and CD8 + T cells both of which contribute to development of ACD., Conclusion: Ferroptosis was activated in immune cells, especially neutrophils and CD8 + T cells in DNCB-induced ACD mice. Fer-1 treatment inhibited ferroptosis of neutrophils and CD8 + T cells and relieved skin damage in ACD mice., Competing Interests: Declaration of Competing Interest The authors have no conflict of interest to declare., (Copyright © 2024 Japanese Society for Investigative Dermatology. Published by Elsevier B.V. All rights reserved.)

The multibiocomponent hybrid alginate hydrogels based on brown and sea algae, containing 100 % ingredients of natural origin were prepared by ionic crosslinking reaction of a polymeric matrix with lipid nanodispersion. To the best of the Authors' knowledge such multicomponent biobased hydrogel of promising medical and cosmetical applications for the first time was obtained in the environment of flower water, received earlier as a waste by-product from various chemical processes. An innovative hybrid alginate hydrogel that is completely biodegradable and eco-friendly was obtained following waterless and upcycling trends that are in line with the principles of sustainable development. The optimal composition of the lipid nanodispersion and the polymeric matrix was selected using the statistical method of design of the experiment. Based on obtained results, multibiocomponent hybrid alginate hydrogels with various ratios of lipid nanodispersion were obtained. Subsequently, the porous structure and elasticity of the hybrid hydrogels were analyzed. Moreover, to confirm the safety of the multibiocomponent alginate hybrid hydrogels the cytotoxic tests were carried out using human fibroblasts and keratinocytes cell lines. As the final product hybrid of hydrolate-swollen alginate hydrogel and lipid nanodispersion containing several active ingredients (silymarin, bakuchiol, spirulina) was obtained., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Fucoidan from Saccharina japonica (SJF) was isolated and characterized, and its anti-inflammatory effects on fine dust/ambient particulate matter (PM)-stimulated HaCaT keratinocytes were investigated. SJF increased cell viability by reducing intracellular ROS production in PM-stimulated HaCaT keratinocytes. Moreover, SJF downregulated the expression/production of inflammatory cytokines (IL-6, IL-8, IL-13, IL-25, IL-33, TNF-α, IFN-γ, and TSLP) and chemokines (MDC and TARC) through modulating NF-κB/MAPK signaling in PM-stimulated HaCaT keratinocytes. Extended studies investigated the impact of SJF-treated HaCaT keratinocyte culture media on HDFs. Interestingly, media from SJF-treated HaCaT keratinocytes on HDFs demonstrated a notable downregulation of the production of inflammatory mediators such as TSLP, IL-6, IL-8, IL-13, and TNF-α, as well as TARC and MDC. Furthermore, the study examined the impact of SJF on 12-O-tetradecanoylphorbol 13-acetate (TPA) induced ear edema in BALB/c mice and results indicated the reduced ear thickness and decreased iNOS and COX-2 expression. Our study confirmed the effectiveness of SJF in ameliorating PM-induced skin inflammation in in vitro experiments, along with the TPA-induced in vivo inflammatory model., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Organophosphate flame retardants 2-ethylhexyldiphenyl phosphate (EHDPP) and cadmium (Cd) are ubiquitous in environmental matrices, and dermal absorption is a major human exposure pathway. However, their detrimental effects on the human epidermis remain largely unknown. In this study, human keratinocytes (HaCaT cells) were employed to examine the toxicity and underlying mechanisms of co-exposure to EHDPP and Cd. Their influence on cell morphology and viability, oxidative damage, apoptosis, and tight junction were determined. The results showed that co-exposure decreased cell viability by >40 %, induced a higher level of oxidative damage by increasing the generation of reactive oxygen species (1.3 folds) and inhibited CAT (79 %) and GPX (90 %) activities. Moreover, Cd exacerbated EHDPP-induced mitochondrial disorder and cellular apoptosis, which was evidenced by a reduction in mitochondrial membrane potential and an elevation of cyt-c and Caspase-3 mRNA expression. In addition, greater loss of ZO-1 immunoreactivity at cellular boundaries was observed after co-exposure, indicating skin epithelial barrier function disruption, which may increase the human bioavailability of contaminants via the dermal absorption pathway. Taken together, oxidative damage, cell apoptosis, and tight junction disruption played a crucial role in EHDPP + Cd triggered cytotoxicity in HaCaT cells. The detrimental effects of EHDPP + Cd co-exposure were greater than individual exposure, suggesting the current health risk assessment or adverse effects evaluation of individual exposure may underestimate their perniciousness. Our data imply the importance of considering the combined exposure to accurately assess their health implication., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Chlorothalonil (CHT) is a widely used antifungal agent and is reported to be a sensitizer that can cause allergic contact dermatitis (ACD). ACD initiation is associated with various innate immune cell contributions and is usually accompanied by persistent inflammation, which is a potential contributing factor to skin damage. However, detailed information on the mechanisms by which CHT induces skin sensitization and damage is still insufficient. This study focused on investigating the possible sensitization process and mechanism of CHT and the adverse effects of repeated CHT exposure. CHT activates dendritic cells and promotes the proliferation of lymph cells in the skin sensitization phase, causing severe inflammation. Keratinocytes activate the NLRP3 inflammasome pathway to cause inflammation during CHT treatment, and macrophages also secrete inflammatory cytokines. In addition, CHT-induced inflammation triggered skin wrinkles, decreased epidermal thickness and decreased collagen. Cell experiments also showed that repeated exposure to CHT led to cell proliferation inhibition and senescence, and CHT-induced autophagy dysfunction was not only the reason for inflammation but also for senescence. This study defined the possible process through which CHT is involved in the skin sensitization phase and elucidated the mechanism of CHT-induced inflammation in innate immune responses. We also determined that repeated CHT exposure caused persistent inflammation, ultimately leading to skin aging., Competing Interests: Declaration of Competing Interest The authors declare that they have no known conflict financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Phenylarsine oxide (PAO) is a known environmental pollutant and skin keratinocytes are most seriously affected. Baicalin (BCN) was reported to have antioxidant and anti-inflammatory effects, but its protective effect against PAO toxicity is unknown. This study aimed at exploring whether baicalin can reverse the toxicity of human epidermal keratinocytes that are subjected to PAO exposure and underlying mechanisms. In silico analysis from a publicly accessible HaCaT cell transcriptome dataset exposed to chronic Arsenic showed significant differential expression of several genes, including the genes related to DNA replication. Later, we performed in vitro experiments, in which HaCaT cells were exposed to PAO (500 nM) in the existence of BCN (10-50 µM). Treatment of PAO alone induces the JNK, p38 and caspase-3 activation, which were engaged in the apoptosis induction, while the activity of AKT was significantly inhibited, which was engaged in the suppression of apoptosis. PAO suppressed SIRT3 expression and induced intracellular reactive oxygen species (ROS), causing a marked reduce in cell viability and apoptosis. However, BCN treatment restored the PAO-induced suppression of SIRT3 and AKT expression, reduced intracellular ROS generation, and markedly suppressed both caspase-3 activation and apoptosis induction. However, the protective effect of BCN was significantly attenuated after pretreatment with nicotinamide, an inhibitor of SIRT3. These findings indicate that BCN protects against cell death induced by PAO via inhibiting excessive intracellular ROS generation via restoring SIRT3 activity and reactivating downstream AKT pathway. In this study, we firstly shown that BCN is an efficient drug to prevent PAO-induced skin cytotoxicity, and these findings need to be confirmed by in vivo and clinical investigations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

Air pollution, a global health concern, has been associated with adverse effects on human health. In particular, particulate matter (PM), which is a major contributor to air pollution, impacts various organ systems including the skins. In fact, PM has been suggested as a culprit for accelerating skin aging and pigmentation. In this study, using single-cell RNA sequencing, IL-24 was found to be highly upregulated among the differentially expressed genes commonly altered in keratinocytes and fibroblasts of ex vivo skins exposed to PM. It was verified that PM exposure triggered the expression of IL-24 in keratinocytes, which subsequently led to a decrease in type I procollagen expression and an increase in MMP1 expression in fibroblasts. Furthermore, long-term treatment of IL-24 induced cellular senescence in fibroblasts. Through high-throughput screening, we identified chemical compounds that inhibit the IL-24-STAT3 signaling pathway, with lovastatin being the chosen candidate. Lovastatin not only effectively reduced the expression of IL24 induced by PM in keratinocytes but also exhibited a capacity to restore the decrease in type I procollagen and the increase in MMP1 caused by IL-24 in fibroblasts. This study provides insights into the significance of IL-24, illuminating mechanisms behind PM-induced skin aging, and proposes IL-24 as a promising target to mitigate PM-associated skin aging., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Ultraviolet B (UVB) radiation accelerates the aging process of skin cells by triggering oxidative stress and inflammatory responses. The aim of this study was to investigate the mechanism of action of sRNAs and protein molecules in the regenerative extracellular vesicles of Lactobacillus plantarum against the UVB-induced photoaging process of human keratinocytes. The extracellular vesicles regenerated by Lactobacillus plantarum were isolated and purified to identify sRNAs and protein components. Human keratinocytes were treated with UVB radiation to simulate the photoaging model. The effects of different concentrations of vesicle extract on cell survival rate, oxidative stress index and inflammatory marker expression were evaluated in control group and treatment group. The results showed that the regenerated extracellular vesicles of L. plantarum significantly improved the survival rate of keratinocytes after UVB radiation, and delayed the aging process of skin cells by reducing oxidative stress and inhibiting inflammatory response., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Despite the growing awareness of potential human and environmental risks associated with sunscreens, identifying the specific constituents responsible for their potential toxicity is challenging. In this study, we applied three different types of sunscreens with contrasting compositions and compared the effects of their particulate and soluble fractions based on 15 cellular biomarkers of HaCaT cells. Multilinear regression analysis revealed that the internalized soluble fractions played a primary role in the overall cytotoxicity of sunscreen mixtures, which was primarily attributed to their biotransformation, generating metabolites with higher toxicity. The presence of plastic microspheres in sunscreens either inhibited the internalization of soluble fractions or led to their redistribution toward lysosomes. Conversely, subcellular toxicity resulting from the sunscreen mixture was predominantly influenced by particulates. Bio-transformable particulates such as ZnO dissolved in the organelles and induced higher subcellular toxicity compared to bioinert particulates such as microplastics. Subcellular biomarkers including lysosomal count, lysosomal size, mitochondrial count and mitochondrial shape emerged as the potential predictors of sunscreen presence. Our study provides important understanding of sunscreen toxicity by elucidating the differential impacts of particulate and soluble fractions in mixture contaminants., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Hexagonal boron nitride (hBN) is an emerging two-dimensional material attracting considerable attention in the industrial sector given its innovative physicochemical properties. Potential risks are associated mainly with occupational exposure where inhalation and skin contact are the most relevant exposure routes for workers. Here we aimed at characterizing the effects induced by composites of thermoplastic polyurethane (TPU) and hBN, using immortalized HaCaT skin keratinocytes and BEAS-2B bronchial epithelial cells. The composite was abraded using a Taber® rotary abraser and abraded TPU and TPU-hBN were also subjected to photo-Fenton-mediated degradation mimicking potential weathering across the product life cycle. Cells were exposed to the materials for 24 h (acute exposure) or twice per week for 4 weeks (chronic exposure) and evaluated with respect to material internalization, cytotoxicity, and proinflammatory cytokine secretion. Additionally, comprehensive mass spectrometry-based proteomics and metabolomics (secretomics) analyses were performed. Overall, despite evidence of cellular uptake of the material, no significant cellular and/or protein expression profiles alterations were observed after acute or chronic exposure of HaCaT or BEAS-2B cells, identifying only few pro-inflammatory proteins. Similar results were obtained for the degraded materials. These results support the determination of hazard profiles associated with cutaneous and pulmonary hBN-reinforced polymer composites exposure., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Bengt Fadeel, Alberto Bianco, Maurizio Prato, Ester Vazquez, Peter Wick reports financial support was provided by Graphene Flagship. Alberto Bianco reports financial support was provided by French National Research Agency. Ester Vazquez reports financial support was provided by European Union. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Photodamage is one of the most common causes of skin injury. High molecular weight hyaluronic acid (HHA) has shown immense potential in the treatment of skin photodamage by virtue of its anti-inflammatory, reparative, and antioxidative properties. However, due to its large molecular structure of HHA, HHA solution could only form a protective film on the skin surface in conventional application, failing to effectively penetrate the skin, which necessitates the development of new delivery strategies. Liposomes, with a structure similar to biological membranes, have garnered extensive attention as transdermal drug delivery carriers because of their advantages in permeability, dermal compatibility, and biosafety. Herein, we have developed a HHA-liposome transdermal system (HHL) by embedding HHA into the liposome structure using reverse evaporation, high-speed homogenization, and micro-jet techniques. The effective penetration and long-term residence of HHA in skin tissue were multidimensionally verified, and the kinetics of HHA in the skin were extensively studied. Moreover, it was demonstrated that HHL significantly strengthened the activity of human keratinocytes and effectively inhibits photo-induced cellular aging in vitro. Furthermore, a murine model of acute skin injury induced by laser ablation was established, where the transdermal system showed significant anti-inflammatory and immunosuppressive properties, promoting skin proliferation and scar repair, thereby demonstrating immense potential in accelerating skin wound healing. Meanwhile, HHL significantly ameliorated skin barrier dysfunction caused by simulated sunlight exposure, inhibited skin erythema, inflammatory responses, and oxidative stress, and promoted collagen expression in a chronic photodamage skin model. Therefore, this transdermal delivery system with biocompatibility represents a promising new strategy for the non-invasive application of HHA in skin photodamage, revealing the significant potential for clinical translation and broad application prospects. STATEMENT OF SIGNIFICANCE: The transdermal system utilizing hyaluronic acid-based liposomes enhances skin permeability and retains high molecular weight hyaluronic acid (HHL). In vitro experiments with human keratinocytes demonstrate significant skin repair effects of HHL and its effective inhibition of cellular aging. In an acute photodamage model, HHL exhibits stronger anti-inflammatory and immunosuppressive properties, promoting skin proliferation and scar repair. In a chronic photodamage model, HHL significantly improves skin barrier dysfunction, reduces oxidative stress induced by simulated sunlight, and enhances collagen expression., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

The human health risk assessment through the dermal exposure of metal (loid)s in dust from low latitude and high geological background plateau cities was largely unknown. In this study, the road dust samples were harvested from a typical low-latitude plateau provincial capital city Kunming, Southwest China. The total concentration and dermal bioaccessibility of heavy metal (loid)s in road dust were determined, and their health risks as well as cytotoxicity on human skin keratinocytes were also assessed. The average concentrations of As (28.5 mg/kg), Cd (2.65 mg/kg), Mn (671 mg/kg), and Zn (511 mg/kg) exceeded the soil background values. Arsenic had the highest bioaccessibility after 2 h (3.79%), 8 h (4.24%), and 24 h (16.6%) extraction. The dermal pathway when bioaccessibility is considered has a higher hazard quotient than the conventional method using total metal(loid)s in the dust. In addition, toxicological verification suggested that the dust extracts suppressed the cell viability, increased the reactive oxygen species (ROS) level and DNA damage, and eventually activated the mitochondria-mediated apoptosis pathway, evidenced by the upregulation of Caspase-3/9, Bax, and Bak-1. Cadmium was positively correlated with the mRNA expression of Bax. Taken together, our data indicated that both dermal bioaccessibility and cytotoxicity should be considered for accurate human skin health risk assessment of heavy metal(loid)s in road dust, which may provide new insight for accurate human health risk assessment and environmental management., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The aim of this work was to investigate the influence of Leucidal® Liquid (abbr. Leucidal), which is recommended as a natural cosmetic ingredient of antimicrobial properties, on model membranes of keratinocytes and fibroblasts. The toxicity tests on cell lines were also performed to allow for a more detailed discussion of the results. As model membrane systems the lipid Langmuir monolayers were applied. During the investigations, the surface pressure/area measurements, penetration studies and Brewster Angle Microscopy (BAM) visualization were performed for one component and mixed lipid monolayers. It was evidenced that at the membrane - corresponding conditions, the components of Leucidal do not penetrate either model keratinocyte and fibroblast membranes or one component films composed of the major lipids of skin cell membranes. Leucidal makes these systems slightly more expanded and less stable, however this is not reflected in the changes in the film morphology. Only the ceramide systems were sensitive to the presence of Leucidal, i.e. the incorporation of Leucidal components manifested well in the decrease of the films' condensation and alterations in their morphology. The tests on cells demonstrated that Leucidal is non toxic for these types of cells at the concentrations suggested by the producer. A thorough comparison of these results with those published for bacteria model membranes enabled us to discuss them in the context of the mechanism of action of Leucidal components. It was concluded that Leucidal components are of low affinity to the skin cellular model membranes of low content of Leucidal-sensitive ceramides and are not toxic for fibroblast and keratinocyte cell lines. Moreover, the lipid composition of the membrane and its molecular organization can be important targets for Leucidal components, decisive from the point of view of the activity and selectivity of the studied composition., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Anthracene, a polycyclic aromatic hydrocarbon (PAH), is a widespread environmental pollutant that poses potential risks to human health. Exposure to anthracene can result in various adverse health effects, including skin-related disorders. Photo exposure sufficiently removes the anthracene from the environment but also generates more degradation products which can be more toxic. The goal of this study was to assess the change in anthracene dermotoxicity caused by photodegradation and understand the mechanism of this change. In the present study, over 99.99% of anthracene was degraded within 24 h of sunlight exposure, while producing many intermediate products including 9,10-anthraquinone and phthalic acid. The anthracene products with different durations of photo exposure were applied to 2D and 3D human keratinocyte cultures. Although the non-degraded anthracene significantly delayed the cell migration, the cell viability and differentiation decreased dramatically in the presence of the photodegraded anthracene. Anthracene photodegradation products also altered the expression patterns of a number of inflammation-related genes in comparison to the control cells. Among these genes, il1a, il1b, il8, cxcl2, s100a9, and mmp1 were upregulated whereas the tlr4 and mmp3 were downregulated by the photodegraded anthracene. Topical deliveries of the photodegraded and non-degraded anthracene to the dorsal skin of hairless mice showed more toxic effects by the photodegraded anthracene. The 4-hour photodegradation products of anthracene thickened the epidermal layer, increased the dermal cellularity, and induced the upregulation of inflammatory markers, il1a, il1b, s100a9, and mmp1. In addition, it also prevented the production of a gap junction protein, Connexin-43. All the evidence suggested that photodegradation enhanced the toxicities of anthracene to the skin. The 4-hour photodegradation products of anthracene led to clinical signs similar to acute inflammatory skin diseases, such as atopic and contact dermatitis, eczema, and psoriasis. Therefore, the potential risk of skin irritation by anthracene should be also considered when an individual is exposed to PAHs, especially in environments with strong sunlight., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The skin, the organ with the largest surface area in the body, is the most susceptible to chemical exposure from the external environment. In this study, we aimed to establish an in vitro skin toxicity monitoring system that utilizes the mechanism of stress granule (SG) formation induced by various cellular stresses. In HaCaT cells, a keratinocyte cell line that comprises the human skin, a green fluorescent protein (GFP) was knocked in at the C-terminal genomic locus of Ras GTPase-activating protein-binding protein 1 (G3BP1), a representative component of SGs. The G3BP1-GFP knock-in HaCaT cells and wild-type (WT) HaCaT cells formed SGs containing G3BP1-GFP upon exposure to arsenite and household chemicals, such as bisphenol A (BPA) and benzalkonium chloride (BAC), in real-time. In addition, the exposure of G3BP1-GFP knock-in HaCaT cells to BPA and BAC promoted the phosphorylation of eukaryotic initiation factor 2 alpha and protein kinase R-like endoplasmic reticulum kinase, which are cell signaling factors involved in SG formation, similar to WT HaCaT cells. In conclusion, this novel G3BP1-GFP knock-in human skin cell system can monitor SG formation in real-time and be utilized to assess skin toxicity to various substances., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: Mucopolysaccharide polysulfate (MPS) is widely used as an active ingredient in topical preparations for the treatment of asteatosis and blood flow disorders. Although topical MPS products can increase cutaneous blood flow (CBF), the underlying mechanism remains unclear., Objective: In this study, we aimed to elucidate how MPS increases CBF. We investigated the association of nitric oxide (NO), a powerful mediator associated with increased local blood volume, with the blood flow-accelerating action of MPS in mice. In addition, we verified the effects of MPS on NO production in different skin cell types, such as keratinocytes (KCs), endothelial cells (ECs), and dermal fibroblasts (DFs)., Methods: We used raster-scanning optoacoustic imaging mesoscopy to observe in vivo changes in the skin blood volume. NO production was determined in each cell using an NO indicator. An enzyme-linked immunoassay was used to measure the phosphorylated nitric oxide synthase (NOS) levels in ECs, DFs, and KCs in the presence or absence of MPS., Results: Topical application of MPS increased the skin blood volume in mice, and this increase was abolished through the addition of NOS inhibitors. MPS promoted the dose-dependent production of NO in various cells, which caused alterations in the phosphorylation state of NOS., Conclusion: Our findings demonstrate that MPS promotes an increase in skin blood volume and NO production in various skin cell types. These results suggest that MPS can potentially accelerate CBF through the NO biosynthesis pathway in different skin cell types., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Glycolic acid (GA) is extensively used in cosmetic formulations and skin peeling treatments but its adverse effects, notably severe disruption of epidermal structure, limit its clinical utility. However, the detailed impact of GA on epidermal homeostasis, including changes in structure and protein expression over time, is not fully understood. This study employed a reconstructed human epidermis (RHE) model to assess the effects of varying GA concentrations on epidermal proliferation, differentiation, and desquamation at different time points. Through histology, immunofluorescence, and immunohistochemistry, we observed that 35% GA concentration adversely caused abnormal epidermal homeostasis by affecting epidermal proliferation, differentiation and desquamation. Our findings reveal time-specific responses of key proteins to GA: Filaggrin, Involucrin, Loricrin, and Ki67 showed very early responses; KLK10 an early response; and AQP3 and K10 late responses. This research provides a detailed characterization of GA's effects in an RHE model, mimicking clinical superficial peeling and identifying optimal times for detecting GA-induced changes. Our results offer insights for designing interventions to mitigate GA's adverse effects on skin, enhancing the safety and efficacy of GA peeling treatments., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Particulate matter 2.5 (PM 2.5 ) poses a serious threat to human health and is responsible for respiratory disorders, cardiovascular diseases, and skin disorders. 3-Bromo-4,5-dihydroxybenzaldehyde (3-BDB), abundant in marine red algae, exhibits anti-inflammatory, antioxidant, and antidiabetic activities. In this study, we investigated the protective mechanisms of 3-BDB against PM 2.5 -induced cell cycle arrest and autophagy in human keratinocytes. Intracellular reactive oxygen species generation, DNA damage, cell cycle arrest, intracellular Ca 2+ level, and autophagy activation were tested. 3-BDB was found to restore cell proliferation and viability which were reduced by PM 2.5 . Furthermore, 3-BDB reduced PM 2.5 -induced reactive oxygen species levels, DNA damage, and attenuated cell cycle arrest. Moreover, 3-BDB ameliorated the PM 2.5 -induced increases in cellular Ca 2+ level and autophagy activation. While PM 2.5 treatment reduced cell growth and viability, these were restored by the treatment with the autophagy inhibitor bafilomycin A1 or 3-BDB. The findings indicate that 3-BDB ameliorates skin cell death caused by PM 2.5 via inhibiting cell cycle arrest and autophagy. Hence, 3-BDB can be exploited as a preventive/therapeutic agent for PM 2.5 -induced skin impairment., Competing Interests: Declaration of Competing Interests The authors declare no competing interests., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

This study involved creating oligomeric conjugates of 3-hydroxy fatty acids and diclofenac, named Dic-oligo(3HAs). Advanced NMR techniques confirmed no free diclofenac in the mix. We tested diclofenac release under conditions resembling healthy and chronic wound skin. These oligomers were used to make P(3HO) blends, forming patches for drug delivery. Their preparation used the solvent casting/porogen leaching (SCPL) method. The patches' properties like porosity, roughness, and wettability were thoroughly analysed. Antimicrobial assays showed that Dic-oligo(3HAs) exhibited antimicrobial activity against reference (S. aureus, S. epidermis, S. faecalis) and clinical (Staphylococcus spp.) strains. Human keratinocytes (HaCaT) cell line tests, as per ISO 10993-5, showed no toxicity. A clear link between material roughness and HaCaT cell adhesion was found. Deep cell infiltration was verified using DAPI and phalloidin staining, observed under confocal microscopy. SEM also confirmed HaCaT cell growth on these scaffolds. The strong adhesion and proliferation of HaCaT cells on these materials indicate their potential as wound dressing layers. Additionally, the successful diclofenac release tests point to their applicability in treating both normal and chronic wounds., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: The aberrant expression of tight junction (TJ) proteins play an important role in several diseases with impaired skin barriers, including atopic dermatitis, psoriasis, and chronic wounds. The evidence provided thus far suggests an important role of calcitriol in skin homeostasis. However, it is not known whether calcitriol improves the impaired skin barrier., Objective: To investigate the effect of calcitriol on TJ barrier function in human primary keratinocytes., Methods: Normal human primary keratinocytes were stimulated with calcitriol, and the expression of TJ-related proteins was measured by real-time PCR and Western blotting. Immunofluorescence was used to examine the intercellular distribution of TJ-related proteins. TJ barrier function was assessed by the transepithelial electrical resistance (TER) assay., Results: We demonstrated that calcitriol increased the expression levels of TJ-related proteins, including claudin-4, claudin-7, occludin, and zonula occludens (ZO)- 1. Calcitriol enhanced the distribution of TJ-related proteins at cellcell borders and induced the phosphorylation of pathways involved in the regulation of TJ barrier function, such as atypical protein kinase C (aPKC), Ras-related C3 botulinum toxin substrate 1 (Rac1), phosphoinositide 3-kinase (PI3K), and protein kinase B (Akt), as evidenced by the effects of specific inhibitors on the above pathways. Indeed, we confirmed that calcitriol enhanced TER in keratinocyte monolayers., Conclusion: These findings showed that calcitriol could modify the expression of keratinocyte TJ proteins, contributing to the maintenance of homeostatic barrier function., Competing Interests: Declaration of Competing Interest The authors have no conflicts of interest to declare., (Copyright © 2024 Japanese Society for Investigative Dermatology. Published by Elsevier B.V. All rights reserved.)

Background: Bullous pemphigoid (BP) is an antibody-mediated blistering disease predominantly affecting the elderly. The pathogenesis involves both complement-dependent and complement-independent mechanisms. The therapeutic potential of targeting complement-independent mechanism has not yet been determined. The mainstay of treatment, corticosteroid, has many side effects, indicating the needs of better treatments., Objective: We tempted to establish an in vitro model of BP which resembles complement-independent mechanism and to examine the therapeutic potential of a novel anti-inflammatory agent, diacerein., Methods: Cultured HaCaT cells were treated with purified antibodies from BP patients, with or without diacerein to measure the cell interface presence of BP180, protein kinase C, and the production of proinflammatory cytokines. An open-label, randomized, phase 2 trial was conducted to compare topical diacerein and clobetasol ointments in patients with mild-to-moderate BP (NCT03286582)., Results: The reduced presentation of BP180 at cell interface after treating with BP autoantibodies was noticed in immunofluorescence and western blotting studies. The phenomenon was restored by diacerein. Diacerein also reduced the autoantibody-induced increase of pro-inflammatory cytokines. Reciprocal changes of BP180 and protein kinase C at the cell interface were found after treating with BP autoantibodies. This phenomenon was also reversed by diacerein in a dose-dependent manner. The phase 2 trial showed that topical diacerein reduced the clinical symptoms which were comparable to those of topical clobetasol., Conclusion: Diacerein inhibited BP autoantibody-induced reduction of BP180 and production of proinflammatory cytokines in vitro and showed therapeutic potential in patients with BP. It is a novel drug worthy of further investigations., Competing Interests: Declaration of Competing Interest Ms. Lee JY was an employee of Twi Biotechnology., (Copyright © 2024 Japanese Society for Investigative Dermatology. Published by Elsevier B.V. All rights reserved.)

Purpose: Psoriasis is a skin disease characterized by excessive proliferation, inflammation and oxidative stress in keratinocytes. The present study aimed to investigate the therapeutic effects of Dendrobium officinale polysaccharide (DOP) on keratinocyte psoriasis-like models., Methods: The HaCaT keratinocyte inflammation models were induced by interleukin (IL)-22 or lipopolysaccharide (LPS), respectively, and oxidative stress damage within cells was elicited by H 2 O 2 and treated using DOP. CCK-8 and EdU were carried out to detect cell proliferation. ELISA, qRT-PCR, and Western blot were conducted to measure the expression of pro-inflammatory cytokines IL17A, IL-23, IL1β, tumor necrosis factor alpha (TNF-α), and IL-6. Reactive oxygen species (ROS) level in keratinocytes was detected by flow cytometry. Cell proliferation-associated proteins (PCNA, Ki67, Cyclin D1) and pathway proteins (p-AKT and AKT), and oxidative stress marker proteins (Nrf-2, CAT, SOD1) were detected by Western blot., Result: DOP did not affect the proliferation of normal keratinocytes, but DOP was able to inhibit the proliferative activity of IL-22-induced overproliferating keratinocytes and suppress the expression of proliferation-related factors PCNA, Ki67, and Cyclin D1 as well as the proliferation pathway p-AKT. In addition, DOP treatment was able to inhibit IL-22 and LPS-induced inflammation and H 2 O 2 -induced oxidative stress, including the expression of IL17A, IL-23, IL1β, TNF-α, IL-6, and IL1β, as well as the expression levels of intracellular ROS levels and cellular oxidative stress-related indicators SOD, MDA, CAT, Nrf-2 and SOD1., Conclusion: DOP inhibits keratinocyte hyperproliferation, inflammation and oxidative stress to improve the keratinocyte psoriasis-like state., Competing Interests: Declaration of competing interest The authors declare no conflict of interests., (Copyright © 2024. Published by Elsevier B.V.)

Ascorbic acid (AA) is one of the important biomolecules involved in all phases of wound healing. The aim of this study was to develop a new hydrogel system that offers topical delivery of ascorbic acid to wounds during wound care management. In this work, we grafted poly (ethylene glycol) methacrylate onto a renewable biopolymer gellan, and the graft copolymer (GPMA) formed was crosslinked covalently and ionically, and used as a matrix for delivering AA to the wounds. By the processes of grafting and crosslinking, the mechanical properties of the gellan increased several fold compared to mechanically weak native gellan. In vitro cytotoxicity evaluation showed that GPMA was non-cytotoxic to fibroblast cells. GPMA hydrogel matrix allowed the sustained release of AA. When AA was incorporated in GPMA, a significant improvement in wound closure was observed in scratch wound assay performed with keratinocytes. Since AA acts as a cofactor in collagen synthesis, the controlled delivery of AA to the wound microenvironment favors the up-regulation of colα1 gene expression. This study revealed that ascorbic acid, at a concentration of 150 μM, has a favorable impact on wound healing when tested in vitro. Overall results indicate that the GPMA matrix could be a promising material for wound healing applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Background: Cannabidiol, a non-psychoactive phytocannabinoid, has antioxidant and anti-inflammatory activity in keratinocytes. However, the signaling pathway through which cannabidiol exerts its effect on keratinocytes or whether it can modulate keratinocyte differentiation has not been fully elucidated yet., Objective: We investigated whether cannabidiol modulates epidermal differentiation and scavenges reactive oxygen species through the aryl hydrocarbon receptor (AhR) in keratinocytes and epidermal equivalents., Methods: We investigated the cannabidiol-induced activation of AhR using AhR luciferase reporter assay, qRT-PCR, western blot, and immunofluorescence assays. We also analyzed whether keratinocyte differentiation and antioxidant activity are regulated by cannabidiol-induced AhR activation., Results: In both keratinocytes and epidermal equivalents, cannabidiol increased both the mRNA and protein expression of filaggrin, involucrin, NRF2, and NQO1 and the mRNA expression of the AhR target genes, including CYP1A1 and aryl hydrocarbon receptor repressor. Additionally, cannabidiol showed antioxidant activity that was attenuated by AhR knockdown or co-administration with an AhR antagonist. Moreover, cannabidiol increased the ratio of OVOL1/OVOL2 mRNA expression, which is a downstream regulator of AhR that mediates epidermal differentiation. In addition to increased expression of barrier-related proteins, cannabidiol-treated epidermal equivalent showed a more prominent granular layer than the control epidermis. The increased granular layer by cannabidiol was suppressed by the AhR antagonist., Conclusion: Cannabidiol can be a modulator of the AhR-OVOL1-filaggrin axis and AhR-NRF2-NQO1 signaling, thus indicating a potential use of cannabidiol in skin barrier enhancement and reducing oxidative stress., Competing Interests: Declaration of Competing Interest The authors have no conflict of interest to declare., (Copyright © 2023 Japanese Society for Investigative Dermatology. Published by Elsevier B.V. All rights reserved.)

Dasatinib, a second-generation BCR-ABL inhibitor, is currently used as first-line treatment for patients with chronic myeloid leukemia. However, dasatinib treatment increases the risk of severe cutaneous toxicity, which limits its long-term safe use in clinic. The underlying mechanism for dasatinib-induced cutaneous toxicity has not been clarified. In this study, we tested the toxicity of dasatinib on human immortal keratinocyte line (HaCaT) and normal human epidermal keratinocytes (NHEK). We found that dasatinib directly caused cytotoxicity on keratinocytes, which could be the explanation of the clinical characteristic of pathology. Mechanistically, dasatinib impaired mitophagy by downregulating HMGB1 protein level in keratinocytes, which led to the accumulation of dysfunctional mitochondria. Mitochondria-derived ROS caused DNA damage and cell apoptosis. More importantly, we confirmed that overexpression of HMGB1 could reverse dasatinib-induced keratinocyte apoptosis, and preliminarily explored the intervention effect of saikosaponin A, which could increase HMGB1 expression, on cutaneous toxicity caused by dasatinib. Collectively, our study revealed that dasatinib induced keratinocyte apoptosis via inhibiting HMGB1-mediated mitophagy and saikosaponin A could be a viable strategy for prevention of dasatinib-induced cutaneous toxicity., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Although modulation of claudin-1-based tight junction (TJ) in stratum granulosum is an option for transdermal absorption of drugs, granular permeation enhancers have never been developed. We previously found that homoharringtonine (HHT), a natural alkanoid, weakened intestinal epithelial barrier with changing expression and cellular localization of TJ components such as claudin-1 and claudin-4. In the present study, we investigated whether HHT is an epidermal granular permeation enhancer. Treatment of normal human epidermal keratinocytes (NHEK) cells with HHT decreased claudin-1 and claudin-4 but not zonula occludens-1 and E-cadherin. HHT lowered TJ-integrity in NHEK cells, accompanied by permeation-enhancement of dextran (4 kDa) in a dose-dependent manner. Transdermal treatment of mice with HHT weakened epidermal barrier. HHT treatment enhanced transdermal absorption of dextran with a molecular mass of up to 10 kDa. Together, HHT may be a transdermal absorption enhancer., Competing Interests: Declaration of competing interest The authors have no conflicts of interest to declare., (Copyright © 2022. Published by Elsevier Inc.)

Aims: Estrogen (E) and progesterone (P) are the major female hormones and are secreted with changing concentration ratios throughout the menstrual cycle. These hormones have been studied individually regarding their physiological function in the skin, but their concentration ratio (E/P) and its effect on the skin has not yet been investigated. The purpose of this study was to clarify the effect of the E/P ratio on skin barrier function. The menstrual cycle was divided into the menstrual, follicular, ovulation, and luteal phases., Materials and Methods: The E/P concentration ratios corresponding with each phase were added to a three-dimensional epidermal model or normal human epidermal keratinocytes for 5 days. Gene and protein expression levels of several markers of cell differentiation, including loricrin (LOR) and transglutaminase (TGase), were quantified by real-time PCR and western blotting, respectively. Transepidermal water loss (TEWL) of the three-dimensional epidermal model was measured, and ceramide content was quantified by thin-layer chromatography., Key Findings: Gene expression of the epidermal differentiation markers, LOR and TGase, increased when applying the concentration ratio of E/P associated with the menstrual and luteal phases. The LOR protein level decreased from menstrual to luteal phases, and the TGase protein level increased from menstrual to luteal phases. During the same phases, ceramide NS increased and TEWL decreased., Significance: Skin barrier function was improved by culturing cells at specific E/P concentration ratios, which would, therefore, be considered beneficial for female skin. This suggests that dysregulated E/P concentration ratios may be the cause of certain skin problems., (Copyright © 2022 Elsevier Inc. All rights reserved.)

IRF6 is a transcription factor that is required for craniofacial development and epidermal morphogenesis. Specifically, Irf6-deficient mice lack the terminally differentiated epidermal layers, leading to an absence of barrier function. This phenotype also includes intraoral adhesions due to the absence of the oral periderm, leading to the mislocalization of E-cadherin and other cell‒cell adhesion proteins of the oral epithelium. However, the mechanisms by which IRF6 controls the localization of cell adhesion proteins are not understood. In this study, we show that in human and murine keratinocytes, loss of IRF6 leads to a breakdown of epidermal sheets after mechanical stress. This defect is due to a reduction of adhesion proteins at the plasma membrane. Dynamin inhibitors rescued the IRF6-dependent resistance of epidermal sheets to mechanical stress, but only inhibition of clathrin-mediated endocytosis rescued the localization of junctional proteins at the membrane. Our data show that E-cadherin recycling but not its endocytosis is affected by loss of IRF6. Overall, we demonstrate a role for IRF6 in the delivery of adhesion proteins to the cell membrane., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Ethanol has been demonstrated to exert profound effects upon cells and tissues via multiple mechanisms. One recently appreciated means by which cells can communicate with other cells is via the production and release of extracellular vesicles. Though smaller exosomes have been demonstrated to be released in response to ethanol exposure, the ability of ethanol to modulate the generation and release of larger microvesicle particles (MVP) is lesser studied. The present studies examined the ability of exogenous ethanol to generate MVP with a focus on skin cells. Acute ethanol exposure resulted in augmented MVP release in keratinocytes and in the skin and blood of mice. Unlike other stimuli such as ultraviolet B radiation or thermal burn injury, ethanol-mediated MVP release was independent of the Platelet-activating Factor receptor (PAFR). However, ethanol pretreatment was found to augment thermal burn injury-induced MVP in a PAFR-dependent manner. These studies provide a novel mechanism for ethanol-mediated effects, that could be relevant in the significant toxicity associated with thermal burn injury in the setting of alcohol intoxication., Competing Interests: Declaration of Competing Interest The authors report no declarations of interest., (Copyright © 2021 Elsevier B.V. All rights reserved.)