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Rosacea is a chronic inflammatory skin disorder, whose underlying cellular and molecular mechanisms remain obscure. Here, we generate a single-cell atlas of facial skin from female rosacea patients and healthy individuals. Among keratinocytes, a subpopulation characterized by IFNγ-mediated barrier function damage is found to be unique to rosacea lesions. Blocking IFNγ signaling alleviates rosacea-like phenotypes and skin barrier damage in mice. The papulopustular rosacea is featured by expansion of pro-inflammatory fibroblasts, Schwann, endothelial and macrophage/dendritic cells. The frequencies of type 1/17 and skin-resident memory T cells are increased, and vascular mural cells are characterized by activation of inflammatory pathways and impaired muscle contraction function in rosacea. Most importantly, fibroblasts are identified as the leading cell type producing pro-inflammatory and vasodilative signals in rosacea. Depletion of fibroblasts or knockdown of PTGDS, a gene specifically upregulated in fibroblasts, blocks rosacea development in mice. Our study provides a comprehensive understanding of the aberrant alterations of skin-resident cell populations and identifies fibroblasts as a key determinant in rosacea development.

Air pollution consists of complex mixtures of chemicals with serious deleterious health effects from acute and chronic exposure. To help understand the mechanisms by which adverse effects occur, the present work examines the responses of cultured human epidermal keratinocytes to specific chemicals commonly found in woodsmoke. Our earlier findings with liquid smoke flavoring (aqueous extract of charred wood) revealed that such extracts stimulated the expression of genes associated with oxidative stress and proinflammatory response, activated the aryl hydrocarbon receptor, thereby inducing cytochrome P4501A1 activity, and induced cross-linked envelope formation, a lethal event ordinarily occurring during terminal differentiation. The present results showed that furfural produced transcriptional responses resembling those of liquid smoke, cyclohexanedione activated the aryl hydrocarbon receptor, and several chemicals induced envelope formation. Of these, syringol permeabilized the cells to the egress of lactate dehydrogenase at a concentration close to that yielding envelope formation, while furfural induced envelope formation without permeabilization detectable in this way. Furfural (but not syringol) stimulated the incorporation of amines into cell proteins in extracts in the absence of transglutaminase activity. Nevertheless, both chemicals substantially increased the amount of cellular protein incorporated into envelopes and greatly altered the envelope protein profile. Moreover, the proportion of keratin in the envelopes was dramatically increased. These findings are consistent with the chemically induced protein cross-linking in the cells. Elucidating mechanisms by which this phenomenon occurs may help understand how smoke chemicals interact with proteins to elicit cellular responses, interpret bioassays of complex pollutant mixtures, and suggest additional sensitive ways to monitor exposures.

BACKGROUND: A traditional view is that stem cells (SCs) divide slowly. Meanwhile, both embryonic and pluripotent SCs display a shorter cell cycle duration (CCD) in comparison to more committed progenitors (CPs). METHODS: We examined the in vitro proliferation and cycling behavior of somatic adult human cells using live cell imaging of passage zero keratinocytes and single-cell RNA sequencing. RESULTS: We found two populations of keratinocytes: those with short CCD and protracted near exponential growth, and those with long CCD and terminal differentiation. Applying the ergodic principle, the comparative numbers of cycling cells in S phase in an enriched population of SCs confirmed a shorter CCD than CPs. Further, analysis of single-cell RNA sequencing of cycling adult human keratinocyte SCs and CPs indicated a shortening of both G1 and G2M phases in the SC. CONCLUSIONS: Contrary to the pervasive paradigm, SCs progress through cell cycle more quickly than more differentiated dividing CPs. Thus, somatic human adult keratinocyte SCs may divide infrequently, but divide rapidly when they divide. Additionally, it was found that SC-like proliferation persisted in vitro.

IL-17C is an epithelial cell-derived proinflammatory cytokine whose transcriptional regulation remains unclear. Analysis of the IL17C promoter region identified TCF4 as putative regulator, and siRNA knockdown of TCF4 in human keratinocytes (KCs) increased IL17C. IL-17C stimulation of KCs (along with IL-17A and TNF-α stimulation) decreased TCF4 and increased NFKBIZ and ZC3H12A expression in an IL-17RA/RE-dependent manner, thus creating a feedback loop. ZC3H12A (MCPIP1/Regnase-1), a transcriptional immune-response regulator, also increased following TCF4 siRNA knockdown, and siRNA knockdown of ZC3H12A decreased NFKBIZ, IL1B, IL36G, CCL20, and CXCL1, revealing a proinflammatory role for ZC3H12A. Examination of lesional skin from the KC-Tie2 inflammatory dermatitis mouse model identified decreases in TCF4 protein concomitant with increases in IL-17C and Zc3h12a that reversed following the genetic elimination of Il17c, Il17ra, and Il17re and improvement in the skin phenotype. Conversely, interference with Tcf4 in KC-Tie2 mouse skin increased Il17c and exacerbated the inflammatory skin phenotype. Together, these findings identify a role for TCF4 in the negative regulation of IL-17C, which, alone and with TNF-α and IL-17A, feed back to decrease TCF4 in an IL-17RA/RE-dependent manner. This loop is further amplified by IL-17C-TCF4 autocrine regulation of ZC3H12A and IL-17C regulation of NFKBIZ to promote self-sustaining skin inflammation.

Purpose: To evaluate the survival and success rates of short (> 6 mm and = 8.5 mm) implants after at least 2 years of functional loading. Implants were assessed using clinical parameters such as marginal bone loss (MBL), pocket depth (PD), keratinized mucosa width (KMW), bleeding on probing (BoP), and the peri-implant condition (mucositis or periimplantitis). Any correlations between clinical parameters were analyzed. Materials and Methods: This observational and retrospective study included 114 posterior maxillary and mandibular implants placed in 27 women and 38 men with a mean age of 68.04 ± 9.07 years. Patients included in the study had received at least one short implant between 2001 and 2013, such that each implant was in occlusal function for at least 2 years by 2015. Patients with only long (= 10 mm) implants, patients with any systemic condition, and smokers were excluded from the study. PD, KMW, periimplant condition, BoP, and MBL were the clinical parameters assessed in the study. Data on prosthesis type (single or splinted) and implant features were also obtained. All data were submitted to analysis via Mann-Whitney unpaired test, with a significance level of P < .05. Spearman correlation coefficient was also measured to verify the negative or positive correlation. Results: The mean follow-up time was 74.08 months, and mean implant success and survival rates were 87.63% and 94.74%, respectively. There were 6 implant failures (5.26%). A total of 66 (59.46%) prostheses were screw-retained implant-supported restorations, and 45 (40.54%) were cemented. A total of 93 (86.49%) short implants were splinted to another implant, and 15 out of 111 (13.51%) restorations were single implants. Keratinized mucosa was missing around 43 (39%) implants, whereas PD was measured to be between 0 and 3 mm in 64.86% of implants and = 4 mm in 31.53% of implants. MBL was = 1.5 mm in 71.17% of cases and > two-thirds the length of the implant in 2.71% of cases. Mucositis and peri-implantitis were found in 22.52% and 7.21% of implants, respectively. The correlation coefficient showed a positive result for PD and MBL (0.11; P = .368) and negative results for PD and KMW (-0.42; P = .002) and KMW and MBL (-0.19; P = .183). Conclusions: Within the limitations of this study, it is possible to conclude that short implants are a feasible treatment option for dental rehabilitation. They are considered an excellent alternative to complex procedures and have high survival rates after at least 2 years of follow-up, with compatible peri-implant local tissue response. Moreover, a significant negative correlation between KMW and PD was observed. [ABSTRACT FROM AUTHOR]

A comprehensive understanding of the intricate cellular and molecular changes governing the complex interactions between cells within acne lesions is currently lacking. Herein, we analyzed early papules from six subjects with active acne vulgaris, utilizing single-cell and high-resolution spatial RNA sequencing. We observed significant changes in signaling pathways across seven different cell types when comparing lesional skin samples (LSS) to healthy skin samples (HSS). Using CellChat, we constructed an atlas of signaling pathways for the HSS, identifying key signal distributions and cell-specific genes within individual clusters. Further, our comparative analysis revealed changes in 49 signaling pathways across all cell clusters in the LSS- 4 exhibited decreased activity, whereas 45 were upregulated, suggesting that acne significantly alters cellular dynamics. We identified ten molecules, including GRN, IL-13RA1 and SDC1 that were consistently altered in all donors. Subsequently, we focused on the function of GRN and IL-13RA1 in TREM2 macrophages and keratinocytes as these cells participate in inflammation and hyperkeratinization in the early stages of acne development. We evaluated their function in TREM2 macrophages and the HaCaT cell line. We found that GRN increased the expression of proinflammatory cytokines and chemokines, including IL-18, CCL5, and CXCL2 in TREM2 macrophages. Additionally, the activation of IL-13RA1 by IL-13 in HaCaT cells promoted the dysregulation of genes associated with hyperkeratinization, including KRT17, KRT16, and FLG. These findings suggest that modulating the GRN-SORT1 and IL-13-IL-13RA1 signaling pathways could be a promising approach for developing new acne treatments.

The collective migration of keratinocytes during wound healing requires both the generation and transmission of mechanical forces for individual cellular locomotion and the coordination of movement across cells. Leader cells along the wound edge transmit mechanical and biochemical cues to ensuing follower cells, ensuring their coordinated direction of migration across multiple cells. Despite the observed importance of mechanical cues in leader cell formation and in controlling coordinated directionality of cell migration, the underlying biophysical mechanisms remain elusive. The mechanically-activated ion channel PIEZO1 was recently identified to play an inhibitory role during the reepithelialization of wounds. Here, through an integrative experimental and mathematical modeling approach, we elucidate PIEZO1's contributions to collective migration. Time-lapse microscopy reveals that PIEZO1 activity inhibits leader cell formation at the wound edge. To probe the relationship between PIEZO1 activity, leader cell formation and inhibition of reepithelialization, we developed an integrative 2D continuum model of wound closure that links observations at the single cell and collective cell migration scales. Through numerical simulations and subsequent experimental validation, we found that coordinated directionality plays a key role during wound closure and is inhibited by upregulated PIEZO1 activity. We propose that PIEZO1-mediated retraction suppresses leader cell formation which inhibits coordinated directionality between cells during collective migration.

Cornified envelopes (CEs) of human epidermis ordinarily consist of transglutaminase-mediated cross-linked proteins and are essential for skin barrier function. However, in addition to enzyme-mediated isopeptide bonding, protein cross-linking could also arise from oxidative damage. Our group recently demonstrated abnormal incorporation of cellular proteins into CEs by pro-oxidants in woodsmoke. In this study, we focused on 2,3-dimethoxy-1,4-naphthoquinone (DMNQ), mesquite liquid smoke (MLS), and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), to further understand the mechanisms through which environmental pro-oxidants induce CE formation and alter the CE proteome. CEs induced by the ionophore X537A were used for comparison. Similar to X537A, DMNQ- and MLS-induced CE formation was associated with membrane permeabilization. However, since DMNQ is non-adduct forming, its CEs were similar in protein profile to those from X537A. By contrast, MLS, rich in reactive carbonyls that can form protein adducts, caused a dramatic change in the CE proteome. TCDD-CEs were found to contain many CE precursors, such as small proline-rich proteins and late cornified envelope proteins, encoded by the epidermal differentiation complex. Since expression of these proteins is mediated by the aryl hydrocarbon receptor (AhR), and its well-known downstream protein, CYP1A1, was exclusively present in the TCDD group, we suggest that TCDD alters the CE proteome through persistent AhR activation. This study demonstrates the potential of environmental pro-oxidants to alter the epidermal CE proteome and indicates that the cellular redox state has an important role in CE formation.

The demand for skin models as alternatives to animal testing has grown due to ethical concerns and the need for accurate substance evaluation. These alternatives, known as New Approach Methodologies (NAMs), are increasingly used for regulatory decisions. Current skin models from primary human cells often rely on bovine collagen, raising ethical issues. This study explores self-assembled skin models (SASM) as a new method, utilizing hair follicle-derived keratinocytes reprogrammed into induced pluripotent stem cells (iPSC) and differentiated into fibroblasts and keratinocytes. The model relies on the ability of fibroblasts to secrete collagen to produce a xeno-free dermal layer and on the differentiation of keratinocytes to create a functional epidermal layer. These layers exhibited confirmed metabolic activity and the capability to withstand test substances. The successful development of SASM underscores the significance of accurate alternatives in dermatological research, providing an ethical and reliable option for substance evaluation and regulatory testing. [ABSTRACT FROM AUTHOR]

Cold atmospheric plasma (CAP) is an emerging technology that can generate various reactive oxygen and nitrogen species (RONS) at room temperature and shows promising applications for skin wound healing. The effects of plasma‐treated medium (PTM) promoting cell proliferation have been verified, but the biological mechanisms involved are not well known. This study aims to assess the proliferation effect and mechanism induced by PTM on human keratinocyte cells (HaCaT) and human umbilical vein endothelial cells (HUVEC) in vitro. The results showed that the concentrations of H2O2 and NO2− inside PTM increased in a time‐dependent manner as the atmospheric pressure plasma jet (APPJ) treatment time was prolonged. The biological outcomes were determined by cell counting kit, wound healing assay, flow cytometry, enzyme‐linked immunosorbent assay (ELISA), and western blot analysis. The cell viability and motility assays indicated that appropriate plasma conditions of short treatment time (15s‐, 30s‐ and 45s‐PTM) could promote cell proliferation, while long treatment time would inhibit cell proliferation (60s‐PTM). With an appropriate time of PTM treatment, the secretion of vascular endothelial growth factor‐α (VEGF‐α) and transforming growth factor alpha (TGF‐α) was promoted and the extracellular signal‐regulated kinase/serine‐threonine protein kinase pathways were activated, which induced HaCaT and HUVEC cell proliferation eventually. These behaviors of cells were mainly related to the enhancement of intracellular reactive oxygen species levels. These findings established a theoretical foundation for potential clinical applications of PTM in wound healing. [ABSTRACT FROM AUTHOR]

Fibroblast growth factors (FGFs) are key orchestrators of development, tissue homeostasis and repair. FGF receptor (FGFR) deficiency in mouse keratinocytes causes an inflammatory skin phenotype with similarities to atopic dermatitis, but the human relevance is unclear. Therefore, we generated human keratinocytes with a CRISPR/Cas9-induced knockout of FGFR2. Loss of this receptor promoted the expression of interferon-stimulated genes and pro-inflammatory cytokines under homeostatic conditions and in particular in response to different inflammatory mediators. Expression of FGFR2 itself was strongly downregulated in cultured human keratinocytes exposed to various pro-inflammatory stimuli. This is relevant in vivo, because bioinformatics analysis of bulk and single-cell RNA-seq data showed strongly reduced expression of FGFR2 in lesional skin of atopic dermatitis patients, which likely aggravates the inflammatory phenotype. These results reveal a key function of FGFR2 in human keratinocytes in the suppression of inflammation and suggest a role of FGFR2 downregulation in the pathogenesis of atopic dermatitis and possibly other inflammatory diseases. [ABSTRACT FROM AUTHOR]

Melanomas arise from transformed melanocytes, positioned at the dermal‐epidermal junction in the basal layer of the epidermis. Melanocytes are completely surrounded by keratinocyte neighbors, with which they communicate through direct contact and paracrine signaling to maintain normal growth control and homeostasis. UV radiation from sunlight reshapes this communication network to drive a protective tanning response. However, repeated rounds of sun exposure result in accumulation of mutations in melanocytes that have been considered as primary drivers of melanoma initiation and progression. It is now clear that mutations in melanocytes are not sufficient to drive tumor formation—the tumor environment plays a critical role. This review focuses on changes in melanocyte‐keratinocyte communication that contribute to melanoma initiation and progression, with a particular focus on recent mechanistic insights that lay a foundation for developing new ways to intercept melanoma development. [ABSTRACT FROM AUTHOR]

Background: Psoriasis is an immune‐mediated inflammatory skin disorder with a multifaceted pathogenesis. Immune dysregulation and immune cell dysfunction are among the mechanisms involved. TEA domain family member 4 (TEAD4) is suggested to play a role in psoriasis development. TEAD4 expression in keratinocytes may have a chemotactic effect and could disturb the function of FOXP3‐positive T lymphocytes. This study aimed to evaluate the expressions of TEAD4 and FOXP3 in lesional, nonlesional psoriatic, and healthy skin and assess the clinical impact of their expression. Methods: This case–control study included 32 cases with psoriasis vulgaris and 32 control groups. Hematoxylin and eosin‐stained slides were examined to evaluate the histopathological findings. Moreover, other sections were immunohistochemically stained with FOXP3 and TEAD4. Results: FOXP3 was expressed in inflammatory cells in 56.5, 37.5, and 12.5% of lesional, nonlesional, and healthy skin, whereas it was entirely negative in the keratinocytes. TEAD4 was expressed in keratinocytes in 93.7 and 46.9% of lesional and nonlesional skin, while negative in healthy skin. Significant differences were observed between their lesional, nonlesional, and healthy skin expressions. Furthermore, FOXP3 expression in lesional skin was significantly associated with early onset (P = 0.016), low PASI score (P = 0.002), mild psoriasis (P = 0.007), and axial affection (P = 0.022), while TEAD4 expression was associated with progressive course (P = 0.032), high PASI score (P = 0.002), severe psoriasis (P = 0.001), severe inflammation (P = 0.001), and progressive course (P = 0.017). Conclusion: TEAD4 expression was higher in lesional than nonlesional skin and absent in healthy skin, suggesting a role in psoriasis development. TEAD4 expression was also associated with severe and progressive psoriasis. This may be mediated by the downregulation of FOXP3 and dysfunction of Treg cells. TEAD4 could serve as a promising therapeutic target in psoriasis. [ABSTRACT FROM AUTHOR]

Hydroxyurea is an antimetabolite that inhibits DNA synthesis and is used as a treatment option in chronic myeloproliferative disorders. Rarely, "dermatomyositis (DM)‐like" skin lesions are observed after long‐term therapy. In this case series, five skin biopsies of four patients were evaluated by histology, immunohistochemistry, and next‐generation sequencing of the TP53 gene locus. All biopsies showed focal basal pleomorphic keratinocytes and suprabasal aberrant p53 expression as well as sparse to severe vacuolar interface dermatitis. Histopathologically, "DM‐like" skin lesions can be clearly distinguished from DM by marked subepidermal fibrosis, vascular proliferation, and the absence of dermal mucin deposits. In 75% of the specimens multiple, partly inactivating and/or pathogenic point mutations of TP53 were found in low frequencies. "DM‐like" skin eruptions as a long‐term consequence of hydroxyurea therapy are possibly not chemotherapy‐associated benign toxic changes, but rather inflammatory reactions to complex keratinocyte alterations that clinically mimic the picture of DM. Synergistic mutagenic effects of hydroxyurea and sunlight might be responsible for this unique drug side effect and could provide a pathogenic link to the known increased risk of skin cancer in these patients. [ABSTRACT FROM AUTHOR]

Niosomes are employed for their improved physical properties and stability and as a controlled delivery system. However, their large-scale production and different preparation methods affect their physical properties. The microfluidic method represents a novel approach to the preparation of niosomes that enables precise control and decreases the preparation time and steps compared to alternative methods. The UVB protection and anti-hyperpigmentation activities of lycopene-loaded niosomes prepared by microfluidic (MF) and novel conventional thin-film hydration (THF) methods were compared. Extract powders from tomatoes (T), carrots (C), and mixed red vegetables (MR) were utilized to prepare lycopene-rich extract-entrapped niosomes. The resulting niosome formulations were characterized by particle size, polydispersity index (PDI), zeta potential, FT-IR spectra, entrapment efficiency, lycopene-release profile, permeation, and stability. The lycopene extract–niosome formulations were evaluated for their potential to provide UVB protection to human keratinocytes (HaCaT) and for their anti-melanogenesis effects on B16F10 melanoma cells. The results indicated that niosomes prepared by the MF method exhibited high uniformity and homogeneity (reflected by a low PDI value) and maintained smaller sizes when processed through a chip utilizing a hydrodynamic flow-focusing (HFF) platform compared to THF niosomes. The release kinetics of all lycopene–niosome formulations followed the Korsmeyer–Peppas model. The FT-IR spectra indicated that lycopene was incorporated into the niosome bilaminar membrane. Moreover, niosomes obtained from MF demonstrated enhanced stability during heating–cooling cycles, along with high UVB protection and anti-melanogenesis effects. Therefore, these developed niosome preparation methods could be effectively applied to topical products. [ABSTRACT FROM AUTHOR]

Background: Psoriasis is an inflammatory skin condition where immune cells play a significant role. The importance of the cross-talk between keratinocytes and immune cells in the pathogenesis of psoriasis has recently been reaffirmed. Recent studies have found that several S1PR functional antagonists, other than S1PR2, are effective in improving psoriasis. This study aims to investigate the role of S1PR2 in psoriasis, that has not been investigated before. Methods: Spatial transcriptomics, RT-qPCR, and flow cytometry were used to map the immune cell landscape and its association with metabolic pathways in an imiquimod (IMQ)-induced psoriasis-like inflammation in S1pr2fl/fl K14-Cre mice that could not sense sphingosine-1-phosphate (S1P) in the epidermis through the S1PR2 receptor. Results: Our analysis suggests that S1PR2 in keratinocytes plays a major role in psoriasis-like inflammation compared to other S1PRs. It acts as a downregulator, inhibiting the recruitment of Th17 cells into the skin. In IMQ-induced psoriasis skin, both S1pr2-/- and S1pr2fl/fl K14-Cre mice showed higher expressions of proinflammatory cytokines such as TNF-a, IL-17A, and IL-1b together with higher expressions of MyD88/NF-kB pathway compared to the wild-type mice. Remarkably, in IMQ-treated mice, the deletion of S1pr2 in keratinocytes only resulted in a larger population of Th17 cells in skin-draining lymph nodes. Other S1PR modulators did not improve the worsening of psoriasis-like inflammation caused by S1PR2 deficiency in keratinocytes. Conclusion: This study reaches two main conclusions: signals from keratinocytes play a central role in creating an immune environment that promotes the development of psoriasis, and stimulating S1PR2, instead of suppressing it, represents a potential therapeutic approach for psoriasis. [ABSTRACT FROM AUTHOR]

Venous leg ulcers (VLUs) represent one of the most prevalent types of chronic wounds characterised by perturbed microbiome and biofilm‐forming bacteria. As one of the most abundant skin‐commensal, Staphylococcus epidermidis is known as beneficial for the host, however, some strains can form biofilms and hinder wound healing. In this study, S. epidermidis distribution in VLUs and associated resistome were analysed in ulcer tissue from patients. Virulence of S. epidermidis isolates from VLUs were evaluated by whole genome sequencing, antimicrobial susceptibility testing, in vitro biofilm and binding assays, and assessment of biofilm‐forming capability and pro‐inflammatory potential using human ex vivo wound model. We demonstrated that S. epidermidis isolates from VLUs inhibit re‐epithelialization through biofilm‐dependent induction of IL‐1β, IL‐8, and IL‐6 which was in accordance with impaired healing outcomes observed in patients. High extracellular matrix binding ability of VLU isolates was associated with antimicrobial resistance and expression levels of the embp and sdrG, responsible for bacterial binding to fibrinogen and fibrin, respectively. Finally, we showed that S. epidermidis from VLUs demonstrate pathogenic features with ability to impair healing which underscores the emergence of treatment‐resistant virulent lineages in patients with chronic ulcers. [ABSTRACT FROM AUTHOR]

Background: Monocyte Chemotactic Protein 1-Induced Protein 1 (MCPIP1, also called Regnase-1) is a negative modulator of inflammation with tumor-suppressive properties. Mice with keratinocyte-specific deletion of the Zc3h12a gene, encoding MCPIP1, (Mcpip1eKO mice) are more susceptible to the development of epidermal papillomas initiated by 7,12-dimethylbenz[a]-anthracene (DMBA) and promoted by 2-O-tetradecanoylphorbol-13-acetate (TPA). Methods: The aim of this study was to investigate the MCPIP1 RNase-dependent microRNA (miRNA)‒mRNA regulatory network in chemically induced squamous cell carcinoma (SCC)-like skin papillomas. Next-generation sequencing (NGS) coupled with bioinformatic analysis was used to shortlist the MCPIP1-dependent changes in protein-coding genes and miRNAs. The expression levels of the selected miRNAs were analyzed by quantitative PCR in human keratinocytes with MCPIP1 silencing. Functional studies were performed in human keratinocytes transfected with appropriate miRNA mimics. The DIANA-microT-CDS algorithm and DIANA-TarBase v7 database were used to predict potential target genes and identify the experimentally validated targets of differentially expressed (DE) miRNAs. Results: RNA sequencing (RNA-Seq) analysis of control and Mcpip1eKO DMBA/TPA-induced papillomas revealed transcriptome changes, with 2400 DE protein-coding genes and 33 DE miRNAs. The expression of miR-223-3p, miR-376c-3p, and miR-139-5p was confirmed to be dependent on MCPIP1 activity in both murine and human models. We showed that MCPIP1 directly regulates the expression of miR-376c-3p via direct cleavage of the corresponding precursor miRNA. The pro-proliferative activity of miR-223-3p, miR-376c-3p, and miR-139-5p was experimentally confirmed in SCC-like keratinocytes. Bioinformatic prediction of the mRNA targets of the DE-miRNAs revealed 416 genes as putative targets of the 18 upregulated miRNAs and 425 genes as putative targets of the 15 downregulated miRNAs. Further analyses revealed the murine interactions that are conserved in humans. Functional analysis indicated that during the development of cutaneous SCC, the most important pathways/processes mediated by the miRNA‒mRNA MCPIP1-dependent network are the regulation of inflammatory processes, epithelial cell proliferation, Wnt signaling, and miRNA transcription. Conclusions: Loss of MCPIP1 modulates the expression profiles of 33 miRNAs in chemically induced Mcpip1eKO papillomas, and these changes directly affect the miRNA‒mRNA network and the modulation of pathways and processes related to carcinogenesis. [ABSTRACT FROM AUTHOR]

The epidermis of the skin and skin appendages, such as nails, hair and sebaceous glands, depend on a balance of cell proliferation and terminal differentiation in order to fulfill their functions at the interface of the body and the environment. The differentiation of epithelial cells of the skin, commonly referred to as keratinocytes, involves major remodeling processes that generate metabolically inactive cell remnants serving as building blocks of the epidermal stratum corneum, nail plates and hair shafts. Only sebaceous gland differentiation results in cell disintegration and holocrine secretion. A series of studies performed in the past decade have revealed that the lysosome-dependent intracellular degradation mechanism of autophagy is active during keratinocyte differentiation, and the blockade of autophagy significantly alters the properties of the differentiation products. Here, we present a model for the autophagy-mediated degradation of organelles and cytosolic proteins as an important contributor to cellular remodeling in keratinocyte differentiation. The roles of autophagy are discussed in comparison to alternative intracellular degradation mechanisms and in the context of programmed cell death as an integral end point of epithelial differentiation. [ABSTRACT FROM AUTHOR]

The complex network governing self-renewal in epidermal stem cells (EPSCs) is only partially defined. FOXM1 is one of the main players in this network, but the upstream signals regulating its activity remain to be elucidated. In this study, we identify cyclin-dependent kinase 1 (CDK1) as the principal kinase controlling FOXM1 activity in human primary keratinocytes. Mass spectrometry identified CDK1 as a key hub in a stem cell-associated protein network, showing its upregulation and interaction with essential self renewal-related markers. CDK1 phosphorylates FOXM1 at specific residues, stabilizing the protein and enhancing its nuclear localization and transcriptional activity, promoting self-renewal. Additionally, FOXM1 binds to the CDK1 promoter, inducing its expression. We identify the CDK1-FOXM1 feedforward loop as a critical axis sustaining EPSCs during in vitro cultivation. Understanding the upstream regulators of FOXM1 activity offers new insights into the biochemical mechanisms underlying self-renewal and differentiation in human primary keratinocytes. [ABSTRACT FROM AUTHOR]

One in every three cancers diagnosed is a skin cancer. Europe has the global lead in the number of UV‐attributable cancer cases with the highest number of melanoma cases worldwide and the second highest number of keratinocyte cancers (KC). Further increases are expected in Europe for the coming decades. Projected increases are highest for KC with increases in incidence around 40% and increases in mortality around 50%, with KC mortality in males approximating melanoma mortality in females. The two main drivers for this skin cancer epidemic are ageing of the population but especially UV exposure. In conclusion, skin cancer represents a major challenge in the cancer field in Europe today and will continue to do so in the coming decades. This calls for a European skin cancer action plan intended to reduce avoidable UV exposure and to prepare the healthcare system to safeguard early diagnosis and treatment of skin cancer. [ABSTRACT FROM AUTHOR]

Psoriasis is a chronic inflammatory skin disease characterized by abnormal keratinocyte proliferation and inflammation. MiRNAs and serum exosomes participate in the pathogenesis of many diseases. The objective of this study is to explore the function of miR-6785-5p in psoriatic keratinocytes and its upstream and downstream mechanisms. For our study, we employed qRT-PCR and fluorescence in situ hybridization to evaluate miR-6785-5p in psoriatic keratinocytes and conducted a microRNA microarray for identifying differentially expressed miRNAs in patient serum exosomes. We then cocultured keratinocytes with these exosomes, using immunofluorescence staining and qRT-PCR to assess uptake and miR-6785-5p overexpression. We explored miR-6785-5p's role through transfection with specific mimics and inhibitors and confirmed MNK2 as its target using a luciferase assay. MNK2's function was further examined using siRNA technology. Lastly, we applied an imiquimod-induced psoriasis mouse model, also employing siRNA, to investigate MNK2's role in psoriasis. MiR-6785-5p demonstrates a notable overexpression in the keratinocytes of psoriasis patients as well as in their serum exosomes. These keratinocytes actively uptake the miR-6785-5p-enriched serum exosomes. Functionally, miR-6785-5p appears to alleviate psoriasis-like skin damage, observable both in vitro and in vivo, by downregulating MNK2 expression. Psoriasis keratinocytes uptake serum exosomes highly expressing miR-6785-5p. MiR-6785-5p inhibits the abnormal proliferation and inflammatory state of keratinocytes by reducing MNK2 expression and interfering with the MNK2/p-eIF4E axis. [ABSTRACT FROM AUTHOR]

Wound healing is a complex, multi-phase process involving the coordinated interaction of various cells and molecules. This study evaluates the effects of vanillic acid (VA) on wound healing using HaCaT cells. The results demonstrate that VA treatment increases the levels of phosphorylated AMPK protein, thereby activating the AMPK pathway. This activation leads to an upregulation of PNCA expression and enhances the proliferation of HaCaT cells. Additionally, VA treatment reduces the expression of Bax and cleaved Caspase-3 while increasing Bcl2 expression, which inhibits apoptosis in HaCaT cells. Furthermore, VA treatment upregulates the expression of MMP-2 and MMP-9, promoting HaCaT cell migration. VA also induces the secretion of FGF, VEGF, and PDGF, which enhances tube formation in HUVECs. In conclusion, VA may have potential therapeutic benefits in wound healing by promoting keratinocyte proliferation, migration, and angiogenesis. [ABSTRACT FROM AUTHOR]

Chronic wounds remain trapped in a pro-inflammatory state, with strategies targeted at inducing re-epithelialization and the proliferative phase of healing desirable. As a member of the lectin family, galectin-3 is implicated in the regulation of macrophage phenotype and epithelial migration. We investigated if local delivery of galectin-3 enhanced skin healing in a full-thickness excisional C57BL/6 mouse model. An electrospun gelatin scaffold loaded with galectin-3 was developed and compared to topical delivery of galectin-3. Electrospun gelatin/galectin-3 scaffolds had an average fiber diameter of 200 nm, with 83% scaffold porosity approximately and an average pore diameter of 1.15 μm. The developed scaffolds supported dermal fibroblast adhesion, matrix deposition, and proliferation in vitro. In vivo treatment of 6 mm full-thickness excisional wounds with gelatin/galectin-3 scaffolds did not influence wound closure, re-epithelialization, or macrophage phenotypes, but increased collagen synthesis. In comparison, topical delivery of galectin-3 [6.7 µg/mL] significantly increased arginase-I cell density at day 7 versus untreated and gelatin/galectin-3 scaffolds (p < 0.05). A preliminary assessment of increasing the concentration of topical galectin-3 demonstrated that at day 7, galectin-3 [12.5 µg/mL] significantly increased both epithelial migration and collagen content in a concentration-dependent manner. In conclusion, local delivery of galectin 3 shows potential efficacy in modulating skin healing in a concentration-dependent manner. [ABSTRACT FROM AUTHOR]

Wound healing is a complex biological process crucial for tissue repair, wherein keratinocytes play a pivotal role in initiating, sustaining and completing the cascade. Various local and systemic factors, such as lifestyle, age metabolic disorders and vascular insufficiency, can influence this process, and in the context of diabetic wounds, disrupted biological mechanisms, including inflammation, tissue hypoxia, decrease in collagen production along with increased oxidative stress and keratinocyte dysfunction, contribute to delayed healing. During re‐epithelialisation, keratinocytes undergo rapid multiplication and migration, forming a dense hyperproliferative epithelial layer that restores the epidermal barrier. Nuclear factor‐erythroid 2‐related factor (Nrf2), a vital transcription factor, emerges as a central regulator in managing antioxidant proteins and detoxifying enzymes, serving as a guardian against elevated reactive oxygen species (ROS) levels during stress. Nrf2 also orchestrates angiogenesis and anti‐inflammatory responses crucial for wound repair. Studies demonstrate that under high‐glucose conditions, Nrf2 activation promotes wound healing by enhancing cell proliferation and migration while reducing apoptosis. Nrf2 activators stimulate endogenous antioxidant production, thereby mitigating oxidative stress. Furthermore, Nrf2 upregulation is associated with decreased expression of cytokines such as TNF‐α and IL‐ 6. Recent research underscores the potential of bioactive molecules, including dietary polyphenols, traditional medicinal compounds and pharmacological agents, in activating Nrf2 and preventing diseases such as diabetes due to their robust antioxidative properties. This review aims to investigate the activation of Nrf2 by these bioactive molecules in cultured keratinocytes and animal models, elucidating the key molecular regulatory mechanisms involved in alleviating oxidative stress and facilitating the diabetic wound healing process. Understanding these complex pathways may offer insights into novel therapeutic strategies for enhanced wound healing in diabetes‐associated complications. [ABSTRACT FROM AUTHOR]

Crisaborole has broad-spectrum anti-inflammatory activity by mainly targeting phosphodiesterase 4 (PDE4) enzyme that is a key regulator of inflammatory cytokine production. As this enzyme is expressed in keratinocytes and immune cells, crisaborole mediates an anti-inflammatory effect on almost all inflammatory cells. Topical application of this drug is useful as it potentiates the localization of this drug in the skin and this anti-inflammatory activity is in the low micromolar range. The objective of present research work is to enhance the aqueous solubility of poorly water soluble drug Crisaborole using Co-solvency technique. The prepared formulation was evaluated for physical characteristics, drug content and drug release. [ABSTRACT FROM AUTHOR]

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. To elucidate the BD3 production pathway triggered by S. epidermidis. 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. 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 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. • S. epidermidis triggers the upregulation of TGF-α in keratinocytes via Toll-like receptor 2. • S. epidermidis and and TGF-α demonstrate a synergistic capacity to induce the production of β-defensin 3. • Epidermal growth factor receptor inhibitors modulate the keratinocyte immune response via the S. epidermidis-TGF-α pathway. • This may lead to cutaneous side effects, such as acneiform rashes. [ABSTRACT FROM AUTHOR]

Wearable devices have generally been rigid due to their reliance on silicon‐based technologies, while future wearables will utilize flexible components for example transistors within microprocessors to manage data. Two‐dimensional (2D) semiconducting flakes have yet to be investigated in fiber transistors but can offer a route toward high‐mobility, biocompatible, and flexible fiber‐based devices. Here, the electrochemical exfoliation of semiconducting 2D flakes of tungsten diselenide (WSe2) and molybdenum disulfide (MoS2) is shown to achieve homogeneous coatings onto the surface of polyester fibers. The high aspect ratio (>100) of the flake yields aligned and conformal flake‐to‐flake junctions on polyester fibers enabling transistors with mobilities μ ≈1 cm2 V−1 s−1 and a current on/off ratio, Ion/Ioff ≈102–104. Furthermore, the cytotoxic effects of the MoS2 and WSe2 flakes with human keratinocyte cells are investigated and found to be biocompatible. As an additional step, a unique transistor 'knot' architecture is created by leveraging the fiber diameter to establish the length of the transistor channel, facilitating a route to scale down transistor channel dimensions (≈100 µm) and utilize it to make a MoS2 fiber transistor with a human hair that achieves mobilities as high as μ ≈15 cm2 V−1 s−1. [ABSTRACT FROM AUTHOR]

The pursuit of cosmetic ingredients with proven efficacy and safety that meet consumer needs drives the advancement of new products. Ascorbic acid (AA) is utilized in cosmetic products, predominantly for its potent antioxidant properties. Nonetheless, its instability compromises its efficacy. In this work, ascorbyl 2-O-glucoside persulfate (AAGS) was synthesized, characterized, and evaluated regarding its safety profile and potential bioactivities and the results were compared to AA and its glycoside AAG. Pre-formulation studies were performed to assess the stability of the compounds and their compatibility with typical excipients commonly used in topical formulations. AAGS did not affect the metabolic activity of keratinocyte, macrophage, and monocyte cell lines, up to 500 µM. AAGS also exhibited a non-prooxidant and non-sensitizing profile and anti-allergic activity by impeding the allergen-induced maturation of THP-1 cells. When compared to AA and AAG, AAGS was shown to be more stable at pH values between 5 and 7, as well as superior thermostability and photostability. AAGS demonstrated higher stability in metal solutions of Fe(II) and Mg(II) than AA. AAGS demonstrated similar DPPH radical scavenging activity compared to AA. These results provide useful information for the development of new AA derivatives, highlighting AAGS as a novel cosmetic ingredient. [ABSTRACT FROM AUTHOR]

Cosmetically applicable soluble agonists for Toll-like receptor 2 (TLR2), which can strengthen skin barrier function, were produced by fermentation of asparagus (Asparagus officinalis L.) extract supplemented with skimmed milk using Lactobacillus delbrueckii subsp. lactis TL24. Their molecular size was estimated to be >100 kDa. Their TLR2-stimulating activity was stable over 1 year at 4 °C, but it decreased by more than 95% within 10 and 4 months at 25 °C and 40 °C, respectively. The possibility of stabilization of TLR2-stimulating activity by powdering was tested, and we found that lyophilization with 10% or a higher amount of dextrin could stabilize the activity even at 40 °C. The powdered fermented product dose-dependently stimulated TLR2. It augmented the formation of tight junctions in normal human keratinocytes, as detected by fluorescence staining of occludin and ZO-1, whereas their protein and gene expression levels did not increase, suggesting that a change in subcellular localization of these proteins without significant changes in their amounts might be responsible. The powder nature has some benefits over the aqueous, besides stability, e.g., it can be dissolved just before application, allowing fresh material to be used each time, and it may widen a range of cosmetic applications in non-aqueous types of cosmetics. [ABSTRACT FROM AUTHOR]

The skin microenvironment created by keratinocytes (KC) influences the stress responses of melanocytes (MC) to UVB insults. This study employed RNA sequencing analysis as well as in vitro and in vivo models to elucidate the underlying mechanisms. Our RNA-Seq analysis revealed a statistically significant upregulation of GCSF and CCL20 genes in UVB-irradiated KC, correlating with the protective effects of KC on MC responses to UVB exposure. Recombinant GCSF and CCL20 exhibited the most pronounced modulation of UVB-induced MC responses. These effects included the attenuation of apoptosis and reduction of ROS formation, along with the upregulation of tyrosinase and tyrosinase-related protein-1, which are involved in the melanogenic pathway. ELISA was also used to confirm that UVB could induce the secretion of GCSF and CCL20 from KC. A similar correlation between GCSF and CCL20 expression in KC and tyrosinase levels in MC was observed in UVB-irradiated mouse skin. Our study provides novel insights into the protective role of GCSF and CCL20 in the paracrine effects of KC on UVB-induced MC damage through the modulation of stress response pathways, the MITF-tyrosinase axis, and the regulation of p53. These findings have implications for the development of pharmacological strategies targeting KC-derived paracrine factors for the prevention of skin photodamage. [ABSTRACT FROM AUTHOR]

Keratinocytes play an essential role in the inflammatory phase of wound regeneration. In addition to migrating and proliferating for tissue regeneration, they produce a large amount of cytokines that modulate the inflammatory process. Previous studies have shown that subthermal treatment with radiofrequency (RF) currents used in capacitive resistive electric transfer (CRET) therapy promotes the proliferation of HaCat keratinocytes and modulates their cytokine production. Although physical therapies have been shown to have anti-inflammatory effects in a variety of experimental models and in patients, knowledge of the biological basis of these effects is still limited. The aim of this study was to investigate the effect of CRET on keratinocyte proliferation, cytokine production (IL-8, MCP-1, RANTES, IL-6, IL-11), TNF-α secretion, and the expression of MMP9, MMP1, NF-κB, ERK1/2, and EGFR. Human keratinocytes (HaCat) were treated with an intermittent 448 kHz electric current (CRET signal) in subthermal conditions and for different periods of time. Cell proliferation was analyzed by XTT assay, cytokine and TNF-α production by ELISA, NF-κB expression and activation by immunofluorescence, and MMP9, MMP1, ERK1/2, and EGF receptor expression and activation by immunoblot. Compared to a control, CRET increases keratinocyte proliferation, increases the transient release of MCP-1, TNF-α, and IL-6 while decreasing IL-8. In addition, it modifies the expression of MMPs and activates EGFR, NF-κB, and ERK1/2 proteins. Our results indicate that CRET reasonably modifies cytokine production through the EGF receptor and the ERK1/2/NF-κB pathway, ultimately modulating the inflammatory response of human keratinocytes. [ABSTRACT FROM AUTHOR]

Transglutaminase enzymes catalyze Ca2+- and thiol-dependent posttranslational modifications of glutamine-residues that include esterification, hydrolysis and transamidation, which results in covalent protein–protein crosslinking. Among the eight transglutaminase family members in mammals, transglutaminase 1 (TG1) plays a crucial role in skin barrier formation via crosslinking and insolubilizing proteins in keratinocytes. Despite this established function in skin, novel functions have begun merging in normal tissue homeostasis as well as in pathologies. This review summarizes our current understanding of the structure, activation, expression and activity patterns of TG1 and discusses its putative novel role in other tissues, such as in vascular integrity, and in diseases, such as cancer and fibrosis. [ABSTRACT FROM AUTHOR]

Simple Summary: The role of the GPER in cancer is controversial due to its dual anti and protumor effects. Elevated GPER expression in cervical cancer has been associated with improved survival outcomes. In cervical cancer cell lines, the selective GPER agonist G-1 induces cell cycle arrest and apoptosis, although the precise molecular mechanisms behind these effects are not fully understood. This study explores the impact of GPER activation by G-1 on the transcriptome, cell migration, and invasion in SiHa cells, as well as in non-tumorigenic keratinocytes transduced with HPV16 E6 or E7 oncogenes. G-1 has been shown to exert antitumor effects by activating apoptotic pathways and modulating migration and invasion processes. The findings support the GPER as a promising prognostic marker and suggest that G-1 could be a valuable therapeutic tool for treating cervical cancer. Background/Objectives: Estrogens and HPV are necessary for cervical cancer (CC) development. The levels of the G protein-coupled estrogen receptor (GPER) increase as CC progresses, and HPV oncoproteins promote GPER expression. The role of this receptor is controversial due to its anti- and pro-tumor effects. This study aimed to determine the effect of GPER activation, using its agonist G-1, on the transcriptome, cell migration, and invasion in SiHa cells and non-tumorigenic keratinocytes transduced with the HPV16 E6 or E7 oncogenes. Methods: Transcriptome analysis was performed to identify G-1-enriched pathways in SiHa cells. We evaluated cell migration, invasion, and the expression of associated proteins in SiHa, HaCaT-16E6, and HaCaT-16E7 cells using various assays. Results: Transcriptome analysis revealed pathways associated with proliferation/apoptosis (TNF-α signaling, UV radiation response, mitotic spindle formation, G2/M cell cycle, UPR, and IL-6/JAK/STAT), cellular metabolism (oxidative phosphorylation), and cell migration (angiogenesis, EMT, and TGF-α signaling) in SiHa cells. Key differentially expressed genes included PTGS2 (pro/antitumor), FOSL1, TNFRSF9, IL1B, DIO2, and PHLDA1 (antitumor), along with under-expressed genes with pro-tumor effects that may inhibit proliferation. Additionally, DKK1 overexpression suggested inhibition of cell migration. G-1 increased vimentin expression in SiHa cells and reduced it in HaCaT-16E6 and HaCaT-16E7 cells. However, G-1 did not affect α-SMA expression or cell migration in any of the cell lines but increased invasion in HaCaT-16E7 cells. Conclusions: GPER is a promising prognostic marker due to its ability to activate apoptosis and inhibit proliferation without promoting migration/invasion in CC cells. G-1 could potentially be a tool in the treatment of this neoplasia. [ABSTRACT FROM AUTHOR]

Diabetic neuropathy is a debilitating disorder characterized by spontaneous and mechanical allodynia. The role of skin mechanoreceptors in the development of mechanical allodynia is unclear. We discovered that mice with diabetic neuropathy had decreased sirtuin 1 (SIRT1) deacetylase activity in foot skin, leading to reduced expression of brain-derived neurotrophic factor (BDNF) and subsequent loss of innervation in Meissner corpuscles, a mechanoreceptor expressing the BDNF receptor TrkB. When SIRT1 was depleted from skin, the mechanical allodynia worsened in diabetic neuropathy mice, likely due to retrograde degeneration of the Meissner-corpuscle innervating Aβ axons and aberrant formation of Meissner corpuscles which may have increased the mechanosensitivity. The same phenomenon was also noted in skin-keratinocyte specific BDNF knockout mice. Furthermore, overexpression of SIRT1 in skin induced Meissner corpuscle reinnervation and regeneration, resulting in significant improvement of diabetic mechanical allodynia. Overall, the findings suggested that skin-derived SIRT1 and BDNF function in the same pathway in skin sensory apparatus regeneration and highlighted the potential of developing topical SIRT1-activating compounds as a novel treatment for diabetic mechanical allodynia. [ABSTRACT FROM AUTHOR]

Objectives: Cell models have shown great promise as tools for research, potentially providing intriguing alternatives to animal models. However, the original tissue characteristics must be maintained in culture, a fact that is often assumed, but seldom assessed. We aimed to follow the retention of the original tissue identities of cleft lip‐derived skin and mucosa keratinocytes in vitro. Methods: Cleft lip‐derived keratinocytes were isolated from discarded tissue along the cleft margins during cheiloplasty. Cell identities were assessed by immunohistochemistry and quantitative real‐time PCR for tissue‐specific markers and compared with native lip tissue. Moreover, keratinocytes were regularly analyzed for the retention of the original tissue characteristics by the aforementioned methods as well as by differentiation assays. Results: The various anatomical zones of the human lip could be distinguished using a panel of differentiation and functional‐based markers. Using these markers, retention of the original tissue identities could be followed and confirmed in the corresponding primary keratinocytes in culture. Conclusions: Our findings promote patient‐derived cells retaining their original identities as astonishing and clinically relevant in vitro tools. Such cells allow a better molecular understanding of various lip‐associated pathologies as well as their modeling in vitro, including but not restricted to orofacial clefts. [ABSTRACT FROM AUTHOR]

Bitter taste receptors (TAS2Rs) are not only expressed in the oral cavity but also in skin. Extraoral TAS2Rs are thought to be involved in non‐taste perception and tissue‐specific functions. Keratinocytes that express TAS2Rs in the skin provide a first‐line defense against external threats. However, the functional roles of these receptors in host defense remain unclear. Here, we demonstrated the sensory role of intracellularly located TAS2Rs against toxic substances in keratinocytes. Although many G protein‐coupled receptors elicit signals from the surface, TAS2Rs were found to localize intracellularly, possibly to the ER, in human keratinocytes and HaCaT cells. TAS2R38, one of the TAS2R members, activated the Gα12/13/RhoA/ROCK/p38 MAP kinase/NF‐κB pathway upon stimulation by phenylthiocarbamide (PTC), an agonist for this receptor, leading to the production of ABC transporters, such as ABCB1, in these cells. Notably, treatment with bitter compounds, such as PTC and saccharin, induced the upregulation of ABCB1 in HaCaT cells. Mechanistically, intracellular TAS2R38 and its downstream signaling Gα12/13/RhoA/ROCK/p38 MAP kinase/NF‐κB pathway were identified to be responsible for the above effect. Pretreatment with PTC prevented the accumulation of rhodamine 123 because of its excretion via ABCB1. Furthermore, pretreatment with PTC or saccharin counteracted the effect of the toxic compound, diphenhydramine, and pretreated HaCaT cells were found to proliferate faster than untreated cells. This anti‐toxic effect was suppressed by treatment with verapamil, an ABCB1 inhibitor, indicating that enhanced ABCB1 helps clear toxic substances. Altogether, harmless activators of TAS2Rs may be promising drugs that enhance the excretion of toxic substances from the human skin. [ABSTRACT FROM AUTHOR]

Adverse effects of ionizing radiation on normal tissues limit the radiation dose in cancer treatment, thereby compromising treatment efficiency. Among the consistently affected non-cancer cells, peripheral blood mononuclear cells (PBMCs) exhibit high radiosensitivity and have the potential to induce systemic effects. PBMC-released extracellular vesicles (EVs), contribute to the communication of such systemic effects. This study aimed to investigate the effects of ionizing radiation on EVs as part of the systemic response of PBMCs in terms of microRNA cargo and biological functions. Therefore, whole blood samples from healthy donors were irradiated ex-vivo (0 Gy, 1 Gy, 2 Gy, 4 Gy) and EVs from PBMCs were isolated after 96 h by PEG precipitation or ultracentrifugation. Candidate microRNAs were examined in PBMC-derived EVs from individual donors. The uptake of membrane-stained fluorescent EVs by different recipient cells was quantified by fluorescence-activated cell sorting analysis. The biological effects of increased miR-34a-5p and of total EVs on recipient cells were assessed. Irradiation of PBMCs induced a dose-dependent upregulation of miR-34a-5p within EVs and PBMCs. However, interindividual differences between donors were noticed in the extent of upregulation, and small EVs displayed more pronounced changes in microRNA levels in comparison to large EVs. Irradiation in presence of the small molecule inhibitor KU-60019 demonstrated that this upregulation is dependent on ATM (Ataxia telangiectasia mutated) activation. Moreover, fibroblasts and keratinocytes were identified as preferred EV recipients. Increased miR-34a-5p levels led to a significant reduction in viability and induction of senescence in keratinocytes but not in fibroblasts, indicating a cell type-specific response. In conclusion, this study further elucidated the complex cellular response of normal tissue after radiation exposure. It confirmed radiation-induced modifications of microRNA expression levels in EVs from PBMCs and identified a robust upregulation of miR-34a-5p in the small EV subfraction, suggesting this microRNA as a potential novel candidate for the development of biomarkers for radiation exposure. Moreover, the different uptake efficiencies observed among specific cell types suggested that EVs induce cell type-specific responses in the intercellular communication of systemic radiation effects. [ABSTRACT FROM AUTHOR]

Background: Substances that can efficiently enhance skin penetration while exerting no adverse effect are useful for drug and cosmetics formulation. Objective: To investigate the safety and enhance skin penetration efficacy of Putocrin®, a combination containing 2% isosorbide dimethyl ether, 1% pentanediol, and 0.5% inositol. Methods: An in vitro keratinocyte cell assay using 3‐(4,5‐dimethylthiazolyl‐2)‐2,5 diphenyltetrazolium bromide (MTT), and an in vitro EpiKutis® skin study adopted hematoxylin and eosin staining, immunostaining, and liquid chromatography–mass spectrometry (LC–MS) analysis were carried out to investigate the safety of Putocrin®. A pigskin‐Franz cell system experiment applied high‐performance liquid chromatography (HPLC) to compare the skin penetration efficiency of fluorescein isothiocyanate (Fitc)‐labeled tranexamic acid with or without the assistance of Putocrin®. The safety and efficacy of Putocrin® was further evaluated on zebrafish embryos. Results: The MTT assay showed that Putocrin® at concentration ≤2.5% did not significantly affect cell viability. The in vitro EpiKutis® skin study revealed that 2.5% Putocrin® did not affect skin morphology, filaggrin content, ceramide/protein, or fatty acid/protein ratios, but significantly increased loricrin content by 86.00% (p < 0.001). The pigskin‐Franz cell penetration experiment demonstrated that Fitc‐labeled tranexamic acid could barely penetrate the skin (with penetration rate of 1.121%), while Putocrin® significantly enhanced the penetration rate up to 83.983%, which was close to unlabeled tranexamic acid (90.013%). The zebrafish embryo study showed that 2.5% Putocrin® did not exert observable toxicity and obviously assisted the skin penetration of Fitc‐labeled tranexamic acid into fish embryos. These results indicate the strong enhancing skin penetration potency of Putocrin®. Conclusion: This study demonstrated the safety as well as the strong enhancing skin penetration potency of Putocrin® for cosmetics formulation use. [ABSTRACT FROM AUTHOR]

Tapinarof (3,5-dihydroxy-4-isopropylstilbene) is a therapeutic agent used in the treatment of psoriasis (VTAMA®). In this study, we examined the redox behaviour, (photo)stability, (photo)toxicity and (bio)transformation of tapinarof in the context of a structure-activity relationship study. Selected derivatives of the structurally related tapinarof were investigated, namely resveratrol, pterostilbene, pinosylvin and its methyl ether. Tapinarof undergoes electrochemical oxidation in a neutral aqueous medium at a potential of around +0.5 V (vs. Ag|AgCl|3M KCl). The anodic reaction of this substance is a proton-dependent irreversible and adsorption-driven process. The p K a value of tapinarof corresponds to 9.19 or 9.93, based on empirical and QM calculation approach, respectively. The oxidation potentials of tapinarof and its analogues correlate well with their HOMO (highest occupied molecular orbital) energy level. The ability to scavenge the DPPH radical decreased in the order trolox ≥ resveratrol > pterostilbene > tapinarof > pinosylvin ≫ pinosylvin methyl ether. It was also confirmed that tapinarof, being a moderate electron donor, is able to scavenge the ABTS radical and inhibit lipid peroxidation. The 4′-OH group plays a pivotal role in antioxidant action of stilbenols. During the stability studies, it was shown that tapinarof is subject to spontaneous degradation under aqueous conditions, and its degradation is accelerated at elevated temperatures and after exposure to UVA (315–399 nm) radiation. In aqueous media at pH 7.4, we observed an ∼50 % degradation of tapinarof after 48 h at laboratory temperature. The main UVA photodegradation processes include dihydroxylation and hydration. In conclusion, the phototoxic effect of tapinarof on a human keratinocytes cell line (HaCaT) was evaluated. Tapinarof exhibited a clear phototoxic effect, similar to phototoxic standard chlorpromazine. The IC 50 values of the cytotoxicity and phototoxic effects of tapinarof correspond to 27.6 and 3.7 μM, respectively. The main HaCaT biotransformation products of tapinarof are sulfates and glucuronides. [Display omitted] • Tapinarof, also benvitimod, is redox active moderate electron-donor. • Structure-activity relationship study is presented here with resveratrol analogues. • Tapinarof undergoing irreversible adsorption-driven electrochemical anodic reaction. • The instability of tapinarof could be accelerated by higher temperature or UVA irradiation. • Tapinarof is phototoxic in uM concentration range after UVA irradiation of keratinocytes. [ABSTRACT FROM AUTHOR]

Background: Abnormal biological behaviour of keratinocytes (KCs) is a critical pathophysiological manifestation of psoriasis. Ferroptosis is programmed cell death induced by the accumulation of lipid reactive oxygen species (ROS) in the presence of increased intracellular iron ions or inhibition of GPX4. Objectives: The purpose of this study was to investigate the effects of ferroptosis on the biological behaviour of Keratinocytes (KCs) in psoriasis vulgaris and its possible regulatory mechanisms in clinical samples, cells, and mouse models. Methods: We first examined the differences in the expression of GPX4 and 4-HNE between psoriasis and normal human lesions. And detected KRT6, FLG, and inflammatory cytokines after inducing ferroptosis in animal and cell models by RT-qPCR, Western blot, immunohistochemistry, and flow cytometry. Results: We found that GPX4 was decreased and that the oxidation product 4-hydroxy-2-nonenal (HNE) was increased in the skin lesions of patients with psoriasis vulgaris. The expression level of GPX4 correlates with the severity of skin lesions. Moreover, inducing ferroptosis promoted the expression of FLG and reduced the expression of KRT6 and inflammatory cytokines in vitro, and alleviated the phenotype of skin lesions in vivo. Limitations: Our study has limitations, notably small sample size. Larger clinical trials are necessary to investigate the association between ferroptosis and disease progression further. More research is necessary to explore how the ferroptosis inducer RSL3 regulates the abnormal biological behaviour of KCs at both cellular and animal levels and establish ferroptosis inhibitors as controls. Conclusions: This study confirms the existence of ferroptosis in psoriatic lesions, which may be inversely correlated with disease severity. The ferroptosis inducer RSL3 ameliorated psoriatic symptoms by improving the abnormal biological behaviour of KCs. [ABSTRACT FROM AUTHOR]

Circular RNAs (circRNAs) are demonstrated to be involved in psoriasis progression. CircRNAs can act as RNA-binding protein (RBP) sponges. Here, we investigated the action of circAKR1B10 in psoriasis, and explored the potential proteins interacted with circAKR1B10. Levels of genes and proteins were assayed by qRT-PCR and western blotting analyses. Keratinocytes in functional groups were treated with interleukin (IL)-22. Functional analysis were conducted using MTT, 5-ethynyl-2’-deoxyuridine (EdU), and transwell assays, respectively. Interaction analysis among circAKR1B10, Eukaryotic initiation factor 4 A-III (EIF4A3) and Aurora Kinase A (AURKA) was conducted using bioinformatics analysis, RNA pull-down assay, and RNA immunoprecipitation (RIP) assay. CircAKR1B10 was highly expressed in psoriasis patients and IL-22-induced keratinocytes. Functionally, knockdown of circAKR1B10 abolished IL-22-induced proliferation, migration and invasion in keratinocytes. AURKA expression was also higher in psoriasis patients and IL-22-induced keratinocytes, and was negatively correlated with circAKR1B10 expression. Moreover, AURKA silencing reduced the proliferative, migratory and invasive abilities of IL-22-induced keratinocytes. Mechanistically, circAKR1B10 interacted with EIF4A3 protein to stabilize and regulate AURKA expression. CircAKR1B10 contributes to IL-22-induced proliferation, migration and invasion in keratinocytes via up-regulating AURKA expression through interacting with EIF4A3 protein. [ABSTRACT FROM AUTHOR]

Vitiligo is an autoimmune disorder characterized by epidermal melanocyte damage, with the typical clinical manifestation of white patches of skin. Keratinocytes, which work in concert with melanocytes to maintain the structural and functional integrity of the skin, are implicated in the progression of vitiligo. Recent studies have reported abnormal keratinocyte proliferation and epidermal thickening in some patients with vitiligo; however, the relationship between these changes and the clinical characteristics of vitiligo remains unclear. We assessed the changes in epidermal thickness in patients with vitiligo and their correlation with clinical characteristics. Compared to the non-lesional skins, the stratum corneum, viable epidermis, and full epidermis in the lesional skins were all significantly thicker. The thickness of the stratum corneum in the head, neck, and trunk was greatly lower than that in the extremities. The thickness of the stratum corneum in the sun-exposed area was higher than that in the sun-protected area, whereas the thickness of the viable epidermis decreased. In conclusion, our study found that the epidermis in the lesional skins of patients with vitiligo was significantly thickened, especially in the sun-exposed areas and extremities. [ABSTRACT FROM AUTHOR]

Occupational exposure to welding fumes constitutes a serious health concern. Although the effects of fumes on the respiratory tract have been investigated, few apparent reports were published on their effects on the skin. The purpose of this study was to investigate the effects of exposure to welding fumes on skin cells, focusing on interleukin-24 (IL-24), a cytokine involved in the pathophysiology of skin conditions, such as atopic dermatitis and psoriasis. Treatment with welding fumes increased IL-24 expression and production levels in human dermal microvascular endothelial cells (HDMEC) which were higher than that in normal human epidermal keratinocytes. IL-24 levels in Trolox and deferoxamine markedly suppressed welding fume-induced IL-24 expression in HDMEC, indicating that oxidative stress may be involved in this cytokine expression. IL-24 released from HDMEC protected keratinocytes from welding fume-induced damage and enhanced keratinocyte migration. Serum IL-24 was higher in welding workers than in general subjects and was positively correlated with elevated serum levels of 8-hydroxy-2'-deoxyguanosine, an oxidative stress marker. In summary, welding fumes enhanced IL-24 expression in HDMEC, stimulating keratinocyte survival and migration. IL-24 expression in endothelial cells may act as an adaptive response to welding-fume exposure in the skin. [ABSTRACT FROM AUTHOR]

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Approximately 22% of moderately to severely affected atopic dermatitis (AD) patients have a history of eczema herpeticum, a disseminated rash primarily caused by herpes simplex virus type 1 (HSV‐1). Reduced activity of antimicrobial peptides may contribute to the increased susceptibility of AD patients to HSV‐1. We previously demonstrated that the antimicrobial protein RNase 7 limits HSV‐1 infection of human keratinocytes by promoting self‐DNA sensing. Here, we addressed whether RNase 7 has any effect on HSV‐1 infection when infecting keratinocytes without exogenously added costimulatory DNA, and which step(s) of the infection cycle RNase 7 interferes with. We quantified viral gene expression by RT‐qPCR and flow cytometry, viral genome replication by qPCR, virucidal effects by plaque titration, and plaque formation and the subcellular localization of incoming HSV‐1 particles by microscopy. Recombinant RNase 7 restricted HSV‐1 gene expression, genome replication, and plaque formation in human keratinocytes. It decreased HSV‐1 immediate‐early transcripts independently of the induction of interferon‐stimulated genes. Its main effect was on intracellular infection processes and not on extracellular virions or virus binding to cells. RNase 7 reduced the amount of cell‐associated capsids and the HSV‐1 envelope glycoprotein D at 3 but not at 0.5 h postinfection. Our data show that RNase 7 directly restricts HSV‐1 infection of human keratinocytes, possibly by promoting the degradation of incoming HSV‐1 particles. This suggests that RNase 7 may limit HSV‐1 spread in the skin and that mechanisms that reduce its activity in the lesional skin of AD patients may increase their susceptibility to eczema herpeticum. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus (S. aureus) commonly reside on human skin in residents in long‐term care facilities, yet its colonization and impact on the skin of hemodialysis (HD) patients have yet to be studied. The aim of the present study was to investigate the colonization of S. aureus on the skin of pruritic and non‐pruritic HD patients, and the influence of S. aureus and S. aureus‐secreted α‐toxin on skin barrier function‐related protein expression. In this study, a higher relative S. aureus count in pruritic HD patients compared to non‐pruritic HD patients and healthy subjects were revealed by real‐time polymerase chain reaction. S. aureus and α‐toxin decreased mRNA and protein expression levels of aryl hydrocarbon receptor (AHR), ovo‐like transcriptional repressor 1 (OVOL1), and filaggrin (FLG) in keratinocytes. In addition, anti‐alpha‐hemolysin (anti‐hla) was used as an α‐toxin neutralizer, and it successfully abrogated S. aureus‐induced AHR, OVOL1, and FLG mRNA and protein expression downregulation. Mechanistically, α‐toxin could decrease FLG activity by preventing the recruitment of AHR to the FLG promoter region. In conclusion, pruritic HD patients had higher S. aureus colonization, with S. aureus‐secreted α‐toxin suppressing FLG expression through the AHR‐FLG axis. [ABSTRACT FROM AUTHOR]