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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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

Reconstructed epidermal equivalents (REEs) consist of two distinct cell layers – the stratum corneum (SC) and the keratinocyte layer (KL). The interplay of these layers is particularly crucial in pruritic inflammatory disorders, like psoriasis, where a defective SC barrier is associated with immune dysregulation. However, independent evaluation of the skin barrier function of the SC and KL in REEs is highly challenging because of the lack of quantitative methodologies that do not disrupt the counter layer. Here, a non‐invasive impedance spectroscopy technique is introduced for dissecting the distinct contributions of the SC and KL to overall skin barrier function without disrupting the structure. These findings, inferred from the impedance spectra, highlight the individual barrier resistances and maturation levels of each layer. Using an equivalent circuit model, a correlation between impedance parameters and specific skin layers, offering insights beyond traditional impedance methods that address full‐thickness skin only is established. This approach successfully detects subtle changes, such as increased paracellular permeability due to mild irritants and the characterization of an immature SC in psoriatic models. This research has significant implications, paving the way for detailed mechanistic investigations and fostering the development of therapies for skin irritation and inflammatory disorders. [ABSTRACT FROM AUTHOR]

Extracellular vesicles (EVs) are important mediators of communication between cells. Here, we reveal a new mode of intercellular communication by melanosomes, large EVs secreted by melanocytes for melanin transport. Unlike small EVs, which are disintegrated within the receiver cell, melanosomes stay intact within them, gain a unique protein signature, and can then be further transferred to another cell as "second-hand" EVs. We show that melanoma-secreted melanosomes passaged through epidermal keratinocytes or dermal fibroblasts can be further engulfed by resident macrophages. This process leads to macrophage polarization into pro-tumor or pro-immune cell infiltration phenotypes. Melanosomes that are transferred through fibroblasts can carry AKT1, which induces VEGF secretion from macrophages in an mTOR-dependent manner, promoting angiogenesis and metastasis in vivo. In melanoma patients, macrophages that are co-localized with AKT1 are correlated with disease aggressiveness, and immunotherapy non-responders are enriched in macrophages containing melanosome markers. Our findings suggest that interactions mediated by second-hand extracellular vesicles contribute to the formation of the metastatic niche, and that blocking the melanosome cues of macrophage diversification could be helpful in halting melanoma progression. Synopsis: Extracellular vesicles (EVs) are known to mediate cell-to-cell communication in various contexts. This study reveals a new mode of intercellular communication involving recycled, "second-hand" EVs that are originally secreted by melanoma cells and drive tumor-associated macrophage diversification. Melanosomes passaged through epidermal keratinocytes or dermal fibroblasts can be further engulfed by resident macrophages. This process polarizes macrophages into pro-tumor or pro-immune cell infiltration phenotypes. Macrophages treated with melanosomes from different source cells exhibit functional diversity. Fibroblasts can transfer melanosomes loaded with AKT1, which promote angiogenesis and metastasis in vivo. Melanoma patients that do not respond to immunotherapy exhibit elevated levels of macrophages containing melanosome markers. "Second-hand" extracellular vesicles secreted by melanoma cells induce macrophage polarization and diversification after passage through different cell types. [ABSTRACT FROM AUTHOR]

Objective: This study explores the application of Line‐field Confocal Optical Coherence Tomography (LC‐OCT) imaging coupled with artificial intelligence (AI)‐based algorithms to investigate atopic dermatitis (AD), a common inflammatory dermatosis. Materials and methods: AD acute and chronic lesions (ADL) were compared to clinically healthy‐looking skin (ADNL). LC‐OCT was used noninvasively and in real‐time to image the skin of AD patients during flare‐ups and monitor remissions under topical steroid treatment for 2 weeks. Quantitative parameters were extracted from the images, including morphological and cellular‐level markers of epidermal architecture. A novel cellular‐level parameter, nuclei "atypia," which quantifies the orderliness of epidermal renewal, was used to highlight abnormal maturation processes. Results: Compared to healthy skin, AD lesions exhibited significant increases in both epidermal and stratum corneum (SC) thickness, along with a more undulated dermo‐epidermal junction (DEJ). Additionally, keratinocyte nuclei (KN) were larger, less compact, and less organized in lesional areas, as indicated by the atypia parameter. A higher degree of atypia was observed in chronic lesions compared to acute ones. Following treatment, all the parameters normalized to levels observed in healthy skin within 2 weeks, mirroring clinical improvements. Conclusion: This study provides insights into the quantification of epidermal renewal using a noninvasive imaging technique, highlighting differences between ADL/ADNL and acute/chronic lesions. It also presents the AD treatment mechanism, paving the way for future investigations on AD and other skin barrier function‐related conditions. [ABSTRACT FROM AUTHOR]

Aim: To explore the levels of neutrophil extracellular traps (NETs) in patients with periodontitis and examine their effects on keratinization, barrier function of human gingival keratinocytes (HGKs) and the associated mechanisms. Materials and Methods: Saliva, gingival crevicular fluid (GCF), clinical periodontal parameters and gingival specimens were collected from 10 healthy control subjects and 10 patients with stage II–IV periodontitis to measure the NET levels. Subsequently, mRNA and protein levels of keratinization and barrier indicators, as well as intracellular calcium and epithelial barrier permeability, were analysed in HGKs after NET stimulation. Results: The study showed that NET levels significantly elevated in patients with periodontitis, across multiple specimens including saliva, GCF and gingival tissues. Stimulation of HGKs with NETs resulted in a decrease in the expressions of involucrin, cytokeratin 10, zonula occludens 1 and E‐cadherin, along with decreased intracellular calcium levels and increased epithelial barrier permeability. Furthermore, the inhibition of keratinization by NETs is ERK‐KLF4‐dependent. Conclusions: This study indicates that NETs impair the barrier function of HGKs and suppress keratinization through ERK/KLF4 axis. These findings provide potential targets for therapeutic approaches in periodontitis to address impaired gingival keratinization. [ABSTRACT FROM AUTHOR]

Background: Long‐term exposure to UVB induces DNA damage, inflammatory response, mitochondrial dysfunction, and apoptosis in skin cells, thus causing skin photodamage. Research has demonstrated the noteworthy antioxidant, anti‐inflammatory, DNA repair, and mitochondrial protective properties of keratinocyte growth factor‐2 (KGF‐2). Methods: To examine the impact of KGF‐2 on UVB‐triggered skin photodamage in mice, hair‐removed mice were initially exposed under UVB radiation and subsequently treated with KGF‐2 hydrogel and repeated for 6 days. On day 7, the assessment of histopathological alterations, inflammation, DNA damage, mitochondrial function, and apoptosis in mouse skin was assessed. Results: It was found that KGF‐2 could effectively relieve cutaneous photodamage symptoms and inhibit epidermal proliferation in mice. Meanwhile, KGF‐2 was found to significantly reduce DNA damage, attenuate the inflammatory response, and inhibit the mitochondria‐mediated intrinsic apoptotic pathway in the UVB‐exposed mouse skin photodamage model. Conclusion: To summarize, our results indicated that KGF‐2 reduces the severity of mouse skin photodamage caused by UVB rays by attenuating DNA damage and the inflammatory response, besides inhibiting the mitochondria‐mediated intrinsic apoptosis pathway. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to investigate the effect of plasma‐activated Ringer's lactate solution (PAL) on oral squamous cell carcinoma (OSCC) cells and carcinogenic processes with a particular focus on iron and collagenous matrix formation. Materials and Methods: We used three OSCC cell lines, one keratinocyte cell line, and two fibroblast lines, and cell viability assays, immunoblotting, flow cytometry, and transmission electron microscopy were performed to evaluate the effect and type of cell death. The effect of PAL treatment on lysyl oxidase (LOX) expression was investigated in vitro and in vivo. Tamoxifen‐inducible Mob1a/b double‐knockout mice were used for the in vivo experiment. Results: PAL killed OSCC cells more effectively than the control nontumorous cells and suppressed cell migration and invasion. Ferroptosis occurred and the protein level of LOX was downregulated in cancer cells in vitro and in vivo. Additionally, PAL improved the survival rate of mice and suppressed collagenous matrix formation. Conclusions: We demonstrated that PAL specifically kills OSCC cells and that ferroptosis occurs in vitro and in vivo. Furthermore, PAL can prevent carcinogenesis and improve the survival rate of oral cancer, especially tongue cancer, by changing collagenous matrix formation via LOX suppression. [ABSTRACT FROM AUTHOR]

Diabetic foot complications that lead to lower extremity amputations pose a significant challenge to the entire global health system. In this multicentre clinical trial, 26 patients with chronic Wagner one diabetic foot ulcers (DFUs) were treated with a unique human keratin matrix graft applied either weekly or bi‐weekly, in addition to standard of care. The hypothesis was that bi‐weekly application would be similar to weekly application. The primary endpoint was complete wound closure by 12 weeks, and secondary endpoints included healing time, percent area reduction and weekly changes in peripheral neuropathy, pain and quality of life. In the intent‐to‐treat population, 77% (10/13) of DFUs treated with bi‐weekly application healed compared with 69% (9/13) treated with weekly application. The mean time to heal within 12 weeks in the bi‐weekly group was 61 days and in the weekly group was 54 days. The mean percent area reduction at 12 weeks was 94.7% in the bi‐weekly group compared with 84.8% in the weekly group. The number of grafts used in the bi‐weekly group was 3.9 compared with 6.2 in the weekly group. The results of this trial confirm our hypothesis that whether bi‐weekly or weekly application of the unique keratin matrix graft is used to treat nonhealing indolent DFUs, there is a high rate of complete healing. Based on these results, future studies should be conducted that further investigate the use of this novel human keratin matrix graft for the treatment of chronic DFUs. [ABSTRACT FROM AUTHOR]

Alternative splicing of precursor messenger RNA (pre‐mRNA), including linear splicing and back splicing, produces multiple isoforms that lead to diverse cell fates in response to stimuli including ultraviolet radiation (UVR). Although UVR‐induced linear gene splicing has been extensively studied in skin cells, the UVR‐induced gene back‐splicing events that lead to the production of circular RNAs (circRNAs) have not been thoroughly investigated. The present study used circRNA transcriptome sequencing to screen the differentially expressed circRNAs in human keratinocytes (HaCaT) after UVA irradiation. A total of 312 differentially expressed circRNAs were found in HaCaT cells post‐UVR. Among the UVA‐induced differentially expressed circRNAs, circUBE2I—a novel circRNA formed by exons 2–6 of the UBE2I gene—was the most significantly upregulated circRNA. RT–qPCR assay further confirmed the increase of circUBE2I level in HaCaT cells after UVA irradiation or H2O2 treatment. RNase R digestion experiment revealed the stability of circUBE2I. Overexpression of circUBE2I in keratinocytes induced ferroptosis after UVA or H2O2, preventable by the ferroptosis inhibitor ferrostatin‐1. Our study provides new insights into the role of circular RNAs in UVA‐induced skin cell damage and suggests that circUBE2I could be a therapeutic target in UVR‐aroused ferroptosis in skin cells. [ABSTRACT FROM AUTHOR]

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Immortalized keratinocytes can offer a low‐cost experimental platform for human skin research, with increased cell yield compared to primary cultures. However, the usefulness of these surrogate cell models is highly dependent on their ability to retain the phenotypic attributes of the parent cells. Keratins K14 and K5 are the hallmarks of undifferentiated, mitotically active basal keratinocytes. We observed occasional progressive loss of K14 expression in growing keratinocyte cell lines, with persistent retention of K5 and an epithelial phenotype, and investigated possible reasons for this. We show that K14 repression occurs by DNA promoter methylation of KRT14 gene and is compounded by histone deacetylation and by the presence of EGF. In vivo, keratinocytes shut down K14 synthesis as they commit to terminal differentiation and move from the basal to spinous layer, but by laser‐capture microdissection of human epidermis we could detect no evidence of increased selective KRT14 methylation in this normal process. Loss of K14 expression suggests that epidermal identity of cultured keratinocytes can be compromised in certain tissue culture situations, possibly due to the immortalization method and persistent EGF supplementation. [ABSTRACT FROM AUTHOR]

Background: Psoriasis is a chronic inflammatory skin disease that can cause systemic inflammation in various organs. Rutin has been suggested to fight psoriasis, but the signaling pathways by which it works need to be explored. Materials and methods: HaCaT cells co‐stimulated with interleukin (IL)‐17, IL‐22, tumor necrosis factor‐alpha (TNF‐α), IL‐1α, and oncostatin M (M5) were used as an in vitro cell model of psoriasis. The proliferation and viability of HaCaT cells were determined by 5‐ethynyl‐2′‐deoxyuridine and cell counting assays. Relative mRNA levels of IL‐6, TNF‐α, chemokines (CXCL1 and CXCL2), and anti‐microbial peptides (S100A7 and S100A8) were detected by reverse transcriptase‐quantitative PCR. Release of IL‐6 and TNF‐α from HaCaT cells was measured by enzyme‐linked immunosorbent assay. Keratin1, Keratin5, p‐JAK2, and p‐STAT3 protein levels were estimated with western blotting. Molecular docking predicted binding sites for Rutin and STAT3. Results: Rutin treatment undercut M5‐urged viability increase and proliferation boost in HaCaT cells. Moreover, M5 stimulation mediated upregulation of IL‐6, TNF‐α, CXCL1, CXCL2, S100A7, and S100A8 was partially reversed after Rutin treatment. In addition, M5 stimulation induced downregulation of Keratin1 and Keratin5 proteins as well as upregulation of p‐JAK2 and p‐STAT3 proteins were attenuated in response to Rutin treatment, manifesting that Rutin treatment inhibited M5‐promoted aberrant differentiation and impaired M5‐mediated activation of the JAK2/STAT3 signaling in HaCaT cells. Molecular docking discovered that residues GLN326 and ASP334 in STAT3 might bind to Rutin. Conclusion: Rutin treatment blocked the JAK2/STAT3 signaling, thus attenuating psoriasis‐related inflammation and anomalous differentiation in keratinocytes. [ABSTRACT FROM AUTHOR]

Frequent itching and incessant scratching are commonly observed in various chronic inflammatory skin conditions, including atopic dermatitis and psoriasis. The persistent and prolonged nature of pruritus can worsen one's quality of life. Keratinocytes (KCs), the predominant cells of the epidermis, have been confirmed to interact with sensory neurons and immune cells and be involved in chronic skin inflammatory diseases associated with pruritus. Initially, KCs and sensory neurons form a unique synapse‐like connection within the epidermis, serving as the structural foundation for their interaction. Additionally, several receptors, including toll‐like receptors and protease‐activated receptor 2, expressed on KCs, become activated in an inflammatory milieu. On the one hand, activated KCs are sources of pro‐inflammatory cytokines and neurotrophic factors, such as adenosine triphosphate, thymic stromal lymphopoietin, and nerve growth factor, which directly or indirectly participate in stimulating sensory neurons, thereby contributing to the itch sensations. On the other hand, KCs also function as primary transducers alongside intraepidermal nerve endings, directly initiating pruritic responses. This review summarizes the current literature and highlights the critical role of KCs in the development and persistence of chronic itch in inflammatory skin disorders. [ABSTRACT FROM AUTHOR]

Seborrheic keratosis (SK) is a common benign tumour, often associated with hyperpigmentation. To investigate the mechanism of melanin accumulation in SK, we have conducted comprehensive gene expression and histological analyses. We obtained five pairs of skin samples, including non‐lesional and SK samples, from the backs of three male Japanese participants aged 40–59 years. To examine melanocytes and keratinocytes in SK, three pairs of skin samples were separated by laser capture microdissection into the basal layer and the other layer in the epidermis. We performed a comprehensive gene expression analysis to identify differentially expressed genes between non‐lesional and SK skin, followed by gene ontology and pathway analysis. We found abnormal morphogenesis and cell proliferation in the basal layer, along with increased immune response and impaired cell differentiation and metabolism in the other layer of SK. We focused on cell proliferation and differentiation, as these are directly associated with melanin accumulation. Immunohistochemical analyses of Ki67, keratin 10, and keratin 14 demonstrated the decreases in the proliferation and early differentiation of the epidermis. Contrarily, no significant changes were observed in terminal differentiation markers, filaggrin and loricrin. Although the number of melanocytes was higher in SK than in non‐lesional skin, melanogenic activity showed no difference. These results indicated that melanin accumulation in SK is caused by delayed melanin excretion due to reduced turnover around the basal and spinous layers of the epidermis and melanin production due to an increased number of melanocytes. Our findings provide new insights for therapeutic approaches in SK. [ABSTRACT FROM AUTHOR]

Background: Reports suggest that lipid profiles may be linked to the likelihood of developing skin cancer, yet the exact causal relationship is still unknown. Objective: This study aimed to examine the connection between lipidome and skin cancers, as well as investigate any possible mediators. Methods: A two‐sample Mendelian randomization (MR) analysis was conducted on 179 lipidomes and each skin cancer based on a genome‐wide association study (GWAS), including melanoma, basal cell carcinoma (BCC), and squamous cell carcinoma (SCC). Then, Bayesian weighted MR was performed to verify the analysis results of two‐sample MR. Moreover, a two‐step MR was employed to investigate the impact of TNF‐like weak inducer of apoptosis (TWEAK)‐mediated lipidome on skin cancer rates. Results: MR analysis identified higher genetically predicted phosphatidylcholine (PC) (17:0_18:2) could reduce the risk of skin tumors, including BCC (OR = 0.9149, 95% CI: 0.8667–0.9658), SCC (OR = 0.9343, 95% CI: 0.9087–0.9606) and melanoma (OR = 0.9982, 95% CI: 0.9966–0.9997). The proportion of PC (17:0_18:2) predicted by TWEAK‐mediated genetic prediction was 6.6 % in BCC and 7.6% in SCC. The causal relationship between PC (17:0_18:2) and melanoma was not mediated by TWEAK. Conclusion: This study identified a negative causal relationship between PC (17:0_18:2) and keratinocyte carcinomas, a small part of which was mediated by TWEAK, and most of the remaining mediating factors are still unclear. Further research on other risk factors is needed in the future. [ABSTRACT FROM AUTHOR]

Glycolysis is vital for the excessive proliferation of keratinocytes in psoriasis, and uridine phosphorylase‐1 (UPP1) functions as an enhancer of cancer cell proliferation. However, little is known about whether UPP1 promotes keratinocyte proliferation and accelerates psoriasis development. This study revealed that UPP1 facilitates cell viability and cell‐cycle progression in human epidermal keratinocytes (HEKs) by modulating the glycolytic pathway. Bioinformatics analysis of UPP1 gene expression and its correlation with the Reactome revealed that UPP1 mRNA expression, cell‐cycle progression, the interleukin‐6 (IL‐6)/Janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) pathway and glycolysis were positively associated with psoriasis. Cell proliferation, the cell cycle and glycolysis were evaluated after UPP1 was silenced or overexpressed. The results showed that UPP1 overexpression increased cell proliferation, cell‐cycle progression and glycolysis, which was contrary to the effects of UPP1 silencing. However, the STAT3 inhibitor diminished UPP1 expression because STAT3 can bind to the UPP1 promoter. In conclusion, UPP1 was significantly activated by the IL‐6/STAT3 pathway and could modulate glycolysis to regulate cell proliferation and cell‐cycle progression in keratinocytes during the development of psoriasis. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the protective effect of NAcM‐OPT, a small molecule inhibitor of defective in cullin neddylation 1 (DCN1), on H2O2‐induced oxidative damage in keratinocytes. Immortalized human keratinocytes (HaCaT cells) were treated with NAcM‐OPT and exposed to oxidative stress. CCK‐8 assays were used to measure cell viability. The mGFP‐RFP‐LC3 dual fluorescent autophagy indicator system was utilized to evaluate changes in autophagic flux. Western blotting was used to measure the expression of the autophagy‐related proteins LC3 and Beclin 1. Keratinocytes were treated with the autophagy activator rapamycin, and HaCaT cell supernatant was added to PIG1 cells (immortalized human melanocytes), followed by evaluation of tyrosinase (TYR) expression via qRT‐PCR. NAcM‐OPT increased cell viability and cell proliferation. Furthermore, this molecule promoted autophagic flux through increased expression of autophagy‐related proteins under H2O2‐induced oxidative stress. Additionally, rapamycin increased the mRNA levels of TYR in PIG1 cells. Moreover, NAcM‐OPT alleviated mitochondrial damage, restored mitochondrial function, and upregulated the expression of NFE2L2, HO1, NQO1, and GCLM. Importantly, NAcM‐OPT also increased epidermal thickness, follicle length, and melanin synthesis under oxidative stress in vivo. These findings suggest that NAcM‐OPT may be a promising small molecule antioxidant drug for the treatment of vitiligo. [ABSTRACT FROM AUTHOR]

Chronic non‐healing cutaneous wounds represent a major burden to patients and healthcare providers worldwide, emphasising the continued unmet need for credible and efficacious therapeutic approaches for wound healing. We have recently shown the potential for collagen peptides to promote proliferation and migration during cutaneous wound healing. In the present study, we demonstrate that the application of porcine‐derived collagen peptides significantly increases keratinocyte and dermal fibroblast expression of integrin α2β1 and activation of an extracellular signal‐related kinase (ERK)‐focal adhesion kinase (FAK) signalling cascade during wound closure in vitro. SiRNA‐mediated knockdown of integrin β1 impaired porcine‐derived collagen peptide‐induced wound closure and activation of ERK‐FAK signalling in keratinocytes but did not impair ERK or FAK signalling in dermal fibroblasts, implying the activation of differing downstream signalling pathways. Studies in ex vivo human 3D skin equivalents subjected to punch biopsy‐induced wounding confirmed the ability of porcine‐derived collagen peptides to promote wound closure by enhancing re‐epithelialisation. Collectively, these data highlight the translational and clinical potential for porcine‐derived collagen peptides as a viable therapeutic approach to promote re‐epithelialisation of superficial cutaneous wounds. [ABSTRACT FROM AUTHOR]

Skin wound healing is driven by proliferation, migration and differentiation of several cell types that are controlled by the alterations in the gene expression programmes. Brahma Gene 1 (BRG1) (also known as SMARCA4) is a core ATPase in the BRG1 Associated Factors (BAF) ATP‐dependent chromatin remodelling complexes that alter DNA‐histone interaction in chromatin at the specific gene regulatory elements resulting in increase or decrease of the target gene transcription. Using siRNA mediated suppression of BRG1 during wound healing in a human ex vivo and in vitro (scratch assay) models, we demonstrated that BRG1 is essential for efficient skin wound healing by promoting epidermal keratinocytes migration, but not their proliferation or survival. BRG1 controls changes in the expression of genes associated with gene transcription, response to wounding, cell migration and cell signalling. Altogether, our data revealed that BRG1 play positive role in skin repair by promoting keratinocyte migration and impacting the genes expression programmes associated with cell migration and cellular signalling. [ABSTRACT FROM AUTHOR]

Urban Particulate Matter (UPM) induces skin aging and inflammatory responses by regulating skin cells through the transient receptor potential vanilloid 1 (TRPV1). Although oleic acid, an unsaturated free fatty acid (FFA), has some functional activities, its effect on UPM‐induced skin damage has not been elucidated. Here, we investigated signaling pathways on how oleic acid is involved in attenuating UPM induced cell damage. UPM treatment increased XRE‐promoter luciferase activity and increased translocation of AhR to the nucleus, resulting in the upregulation of CYP1A1 gene. However, oleic acid treatment attenuated the UPM effects on AhR signaling. Furthermore, while UPM induced activation of TRPV1 and MAPKs signaling which activated the downstream molecules NFκB and AP‐1, these effects were reduced by cotreatment with oleic acid. UPM‐dependent generation of reactive oxygen species (ROS) and reduction of cellular proliferation were also attenuated by the treatment of oleic acid. These data reveal that cell damage induced by UPM treatment occurs through AhR signaling and TRPV1 activation which in turn activates ERK and JNK, ultimately inducing NFκB and AP‐1 activation. These effects were reduced by the cotreatment of oleic acid on HaCaT cells. These suggest that oleic acid reduces UPM‐induced cell damage through inhibiting both the AhR signaling and activation of TRPV1 and its downstream molecules, leading to a reduction of pro‐inflammatory cytokine and recovery of cell proliferation. [ABSTRACT FROM AUTHOR]

The study examines bovine colostrum as a potent source of bioactive compounds, particularly growth factors, for tissue regeneration in humans. While previous research has hinted at therapeutic benefits, a comprehensive understanding of its mechanisms remains elusive, necessitating further investigation. This review analyzes nine selected scientific articles on bovine colostrum's bioactive potential in tissue regeneration. In vitro studies highlight its positive impact on cell behavior, including reduced proliferation and induced differentiation. Notably, optimal concentrations and specific colostrum components, such as extracellular vesicles and insoluble milk fat, show more favorable outcomes. In vivo studies underscore bovine colostrum as a promising natural resource for wound healing, despite some studies failing to identify associated benefits. Further research is crucial to unravel the intricate mechanisms, grasp the full potential in regenerative medicine, and develop more effective wound healing therapies. This refined understanding will pave the way for harnessing the complete regenerative potential of bovine colostrum in clinical applications. Significance Statement: Investigating the potential therapeutic benefits of bovine colostrum in human tissue regeneration is crucial for advancing our understanding of innovative and sustainable approaches to medical interventions. This systematic review endeavors to comprehensively assess existing literature, providing a synthesized analysis of the current state of knowledge. By exploring the viability of bovine colostrum as a regenerative agent, this research not only contributes to the expanding field of regenerative medicine but also holds promise for the development of novel, nature‐inspired strategies to enhance tissue repair and recovery in human health. [ABSTRACT FROM AUTHOR]

Keratinocytes, located in the outermost layer of human skin, are pivotal cells to resist environmental damage. Cellular autophagy plays a critical role in eliminating damaged organelles and maintaining skin cell homeostasis. Low‐dose 5‐Aminolevulinic acid photodynamic therapy (ALA‐PDT) has been demonstrated to enhance skin's antistress ability; however, the regulatory mechanisms of autophagy in keratinocytes remain unclear. In this study, we treated immortalized human keratinocytes (HaCaT cells) with low‐dose ALA‐PDT (0.5 mmol/L, 3 J/cm2). Through RNA‐sequencing analysis, we identified that low‐dose ALA‐PDT modulated autophagy‐related pathways in keratinocytes and pinpointed Unc‐51‐like kinase 1 (ULK1) as a key gene involved. Western blot results revealed that low‐dose ALA‐PDT treatment upregulated the expression of autophagy‐related proteins Beclin‐1 and LC3‐II/LC3‐I ratio. Notably, low‐dose ALA‐PDT regulated autophagy by inducing an appropriate level of reactive oxygen species (ROS), transiently reducing mitochondrial membrane potential, and decreasing adenosine triphosphate production; all these processes functioned on the AMP‐activated protein kinase (AMPK)/ULK1 pathway to activate autophagy. Finally, we simulated external environmental damage using ultraviolet B (UVB) at a dose of 60 mJ/cm2 and observed that low‐dose ALA‐PDT mitigated UVB‐induced cell apoptosis; however, this protective effect was reversed when using the autophagy inhibitor 3‐methyladenine. Overall, these findings highlight how low‐dose ALA‐PDT enhances antistress ability in HaCaT cells through controlling ROS generation and activating the AMPK/ULK1 pathway to arouse cellular autophagy. [ABSTRACT FROM AUTHOR]

Porphyromonas gingivalis produces five classes of serine/glycine lipids that are recovered in lipid extracts from periodontitis‐afflicted teeth and diseased gingival tissues, particularly at sites of periodontitis. Because these lipids are recovered in diseased gingival tissues, the purpose of the present study was to evaluate the capacity of cultured human gingival fibroblasts (HGF), keratinocytes, and macrophages to hydrolyze these lipids. We hypothesize that one or more of these cell types will hydrolyze the serine/glycine lipids. The primary aim was to treat these cell types for increasing time in culture with individual highly enriched serine/glycine lipid preparations. At specified times, cells and culture media samples were harvested and extracted for hydrolysis products. The serine/glycine lipids and hydrolysis products were quantified using liquid chromatography–mass spectrometry (LC–MS) and free fatty acids were quantified using gas chromatograph–mass spectrometer. LC–MS analysis used two different mass spectrometric methods. This study revealed that treatment of HGF or macrophage (THP1) cells with lipid (L) 654 resulted in breakdown to L342 and subsequent release into culture medium. However, L654 was converted only to L567 in gingival keratinocytes. By contrast, L1256 was converted to L654 by fibroblasts and macrophages but no further hydrolysis or release into medium was observed. Gingival keratinocytes showed no hydrolysis of L1256 to smaller lipid products but because L1256 was not recovered in these cells, it is not clear what hydrolysis products are produced from L1256. Although primary cultures of gingival fibroblasts and macrophages are capable of hydrolyzing specific serine/glycine lipids, prior analysis of lipid extracts from diseased gingival tissues revealed significantly elevated levels of L1256 in diseased tissues. These results suggest that the hydrolysis of bacterial lipids in gingival tissues may reduce the levels of specific lipids, but the hydrolysis of L1256 is not sufficiently rapid to prevent significant accumulation at periodontal disease sites. [ABSTRACT FROM AUTHOR]

Background: The antimicrobial ribonuclease RNase 7 is abundantly expressed in the epidermis of lesional skin of atopic dermatitis (AD). Host RNase inhibitor (RI) binds to RNase 7 and blocks its ribonuclease activity. This study aimed to evaluate the impact of RNase 7–RI interactions on AD. Methods: Cultured human primary keratinocytes, with siRNA‐mediated downregulation of RNase 7 and RI, were stimulated with the synthetic RNA polyinosinic‐polycytidylic acid (poly I:C). Induction of proinflammatory mediators was analyzed by real‐time PCR and ELISA. RI expression in AD non‐lesional and lesional skin biopsies and healthy controls was analyzed by real‐time PCR and immunostaining. RI protein release in vivo on the AD skin surface was determined by western blot. Antimicrobial and ribonuclease assays were used to investigate the functional role of RI. Results: RNase 7 inhibited the RNA‐induced expression of proinflammatory mediators in keratinocytes. Accordingly, downregulation of RNase 7 in keratinocytes enhanced RNA‐mediated induction of proinflammatory mediators, whereas downregulation of RI had the opposite effect. RI was released by damaged keratinocytes and epidermis. In vivo expression and release of RI on the skin surface were enhanced in lesional AD skin. Rinsing solution from the surface of lesional AD skin blocked the ribonuclease activity of RNase 7. The anti‐Staphylococcus aureus activity of RNase 7 was abrogated by RI. Conclusions: Our data suggest a novel role of RI as a trigger factor of inflammation in AD by blocking the ribonuclease and antimicrobial activity of RNase 7, thereby enhancing RNA‐mediated inflammation and S. aureus growth. [ABSTRACT FROM AUTHOR]

Objectives: To examine recent changes in the numbers of Medicare‐subsidised keratinocyte cancer excisions, particularly for younger people exposed to primary prevention campaigns since the early 1980s. Study design: Retrospective cohort study; analysis of administrative data. Setting, participants: Analysis of Medicare Benefits Schedule (MBS) claims data for procedures related to the diagnosis and treatment of keratinocyte cancer in Australia, 2012–2021. Main outcome measures: Age‐standardised rates for MBS‐subsidised claims for first surgical squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) excisions, Mohs surgery, surgical excisions of benign lesions, skin biopsies, and cryotherapy or serial curettage of premalignant and malignant lesions, overall, and by sex, state/territory, and age group; average annual percentage change in rate for time intervals determined by joinpoint regression. Results: In men, the age‐standardised rate of BCC/SCC excisions increased by 1.9% (95% confidence interval [CI], 1.4–2.4%) per year during 2012–2019 (from 2931 to 3371 per 100 000 men) and then declined by 3.8% (95% CI, 0.5–7.0%) per year during 2019–2021 (to 3152 per 100 000). In women, the age‐standardised rate increased by 2.2% (95% CI, 1.7–2.8%) per year during 2012–2019 (from 1798 to 2093 per 100 000 women); the decline to 1967 excisions per 100 000 women in 2021 was not statistically significant. BCC/SCC excision rates declined for men under 55 years of age (by 1.0–3.4% per year) and women under 45 years of age (by 1.7–2.3% per year). Age‐standardised biopsy rates increased during 2012–2021 in all age groups (by 2.8–6.9% per year). Conclusions: Rates of MBS‐subsidised treatment for keratinocyte cancers increased during 2012–2019, but BCC/SCC treatment rates declined among younger Australians, who have probably been exposed to less sunlight than earlier generations because of public health interventions and population‐wide lifestyle changes related to technology use. [ABSTRACT FROM AUTHOR]

Hidradenitis Suppurativa (HS) is a chronic autoinflammatory skin disease with activated keratinocytes, tunnel formation and a complex immune infiltrate in tissue. The HS microbiome is polymicrobial with an abundance of commensal gram‐positive facultative (GPs) Staphylococcus species and gram‐negative anaerobic (GNA) bacteria like Prevotella, Fusobacterium and Porphyromonas with increasing predominance of GNAs with disease severity. We sought to define the keratinocyte response to bacteria commonly isolated from HS lesions to probe pathogenic relationships between HS and the microbiome. Type strains of Prevotella nigrescens, Prevotella melaninogenica, Prevotella intermedia, Prevotella asaccharolytica, Fusobacterium nucleatum, as well as Staphylococcus aureus and the normal skin commensal Staphylococcus epidermidis were heat‐killed and co‐incubated with normal human keratinocytes. RNA was collected and analysed using RNAseq and RT‐qPCR. The supernatant was collected from cell culture for protein quantification. Transcriptomic profiles between HS clinical samples and stimulated keratinocytes were compared. Co‐staining of patient HS frozen sections was used to localize bacteria in lesions. A mouse intradermal injection model was used to investigate early immune recruitment. TLR4 and JAK inhibitors were used to investigate mechanistic avenues of bacterial response inhibition. GNAs, especially F. nucleatum, stimulated vastly higher CXCL8, IL17C, CCL20, IL6, TNF and IL36γ transcription in normal skin keratinocytes than the GPs S. epidermidis and S. aureus. Using RNAseq, we found that F. nucleatum (and Prevotella) strongly induced the IL‐17 pathway in keratinocytes and overlapped with transcriptome profiles of HS patient clinical samples. Bacteria were juxtaposed to activated keratinocytes in vivo, and F. nucleatum strongly recruited murine neutrophil and macrophage migration. Both the TLR4 and pan‐JAK inhibitors reduced cytokine production. Detailed transcriptomic profiling of healthy skin keratinocytes exposed to GNAs prevalent in HS revealed a potent, extensive inflammatory response vastly stronger than GPs. GNAs stimulated HS‐relevant genes, including many genes in the IL‐17 response pathway, and were significantly associated with HS tissue transcriptomes. The close association of activated keratinocytes with bacteria in HS lesions and innate infiltration in murine skin cemented GNA pathogenic potential. These novel mechanistic insights could drive future targeted therapies. [ABSTRACT FROM AUTHOR]

The transmembrane protein claudin‐1 is critical for formation of the epidermal barrier structure called tight junctions (TJ) and has been shown to be important in multiple disease states. These include neonatal ichthyosis and sclerosing cholangitis syndrome, atopic dermatitis and various viral infections. To develop a model to investigate the role of claudin‐1 in different disease settings, we used CRISPR/Cas9 to generate human immortalized keratinocyte (KC) lines lacking claudin‐1 (CLDN1 KO). We then determined whether loss of claudin‐1 expression affects epidermal barrier formation/function and KC differentiation/stratification. The absence of claudin‐1 resulted in significantly reduced barrier function in both monolayer and organotypic cultures. CLDN1 KO cells demonstrated decreases in gene transcripts encoding the barrier protein filaggrin and the differentiation marker cytokeratin‐10. Marked morphological differences were also observed in CLDN1 KO organotypic cultures including diminished stratification and reduced formation of the stratum granulosum. We also detected increased proliferative KC in the basale layer of CLDN1 KO organotypic cultures. These results further support the role of claudin‐1 in epidermal barrier and suggest an additional role of this protein in appropriate stratification of the epidermis. [ABSTRACT FROM AUTHOR]

Skin oxidative stress results in structural damage, leading to premature senescence, and pathological conditions such as inflammation and cancer. The plant‐derived prenylated pyrone–phloroglucinol heterodimer arzanol, isolated from Helichrysum italicum ssp. microphyllum (Willd.) Nyman aerial parts, exhibits anti‐inflammatory, anticancer, antimicrobial, and antioxidant activities. This study explored the arzanol protection against hydrogen peroxide (H2O2) induced oxidative damage in HaCaT human keratinocytes in terms of its ability to counteract cytotoxicity, reactive oxygen species (ROS) generation, apoptosis, and mitochondrial membrane depolarization. Arzanol safety on HaCaT cells was preliminarily examined by the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay and microscopic observation. The arzanol pre‐incubation (5–100 μM, for 24 h) did not induce cytotoxicity and morphological alterations. The phloroglucinol, at 50 μM, significantly protected keratinocytes against cytotoxicity induced by 2 h‐incubation with 2.5 and 5 mM H2O2, decreased cell ROS production induced by 1 h‐exposure to all tested H2O2 concentrations (0.5–5 mM), as determined by the 2′,7′‐dichlorodihydrofluorescein diacetate (H2DCFDA) assay, and lipid peroxidation (thiobarbituric acid reactive substances [TBARS] method). The 2‐h incubation of keratinocytes with H2O2 determined a significant increase of apoptotic cells versus control cells, evaluated by NucView® 488 assay, from the dose of 2.5 mM. Moreover, an evident mitochondrial membrane potential depolarization, monitored by fluorescent mitochondrial dye MitoView™ 633, was assessed at 5 mM H2O2. Arzanol pre‐treatment (50 μM) exerted a strong significant protective effect against apoptosis, preserving the mitochondrial membrane potential of HaCaT cells at the highest H2O2 concentrations. Our results validate arzanol as an antioxidant agent for the prevention/treatment of skin oxidative‐related disorders, qualifying its potential use for cosmeceutical and pharmaceutical applications. The 2 h‐exposure of human HaCaT keratinocytes to H2O2 induced cytotoxicity, morphological alterations, ROS production, apoptosis, and mitochondrial depolarization. Pre‐treatment (24 h) of keratinocytes with the phloroglucinol arzanol (50 μM), obtained from Helichrysum italicum ssp. microphyllum (Willd.) Nyman, preserved against H2O2‐induced oxidative damage. The phloroglucinol significantly protected keratinocytes against cytotoxicity induced by 2‐h incubation with 2.5 and 5 mM H2O2, decreased cell ROS production induced by 0.5–5 mM H2O2, and significantly reduced apoptotic cell number and mitochondrial membrane depolarization. [ABSTRACT FROM AUTHOR]

Objectives: ACE2, known as a host receptor involved with SARS‐CoV‐2 infection, binds to viral spike proteins for host cell entry. However, details regarding its induction and function in oral mucosal cells remain unknown. Materials and Methods: We examined ACE2 expression and its induction by transfected mimic nucleotides and pro‐inflammatory cytokines in oral keratinocytes (RT7) and fibroblasts (GT1). Subsequently, the effects of viral spike S1 protein via ACE2 on CXCL10 expression induced by pro‐inflammatory cytokines in both cells were examined. Results: ACE2 was constitutively expressed in RT7 and GT1. Transfected Poly(I:C) and Poly(dA:dT) increased ACE2 expression in those cells, while knockdown of RIG‐I decreased ACE2 expression induced by those transfected ds nucleotides. IFN‐γ and TNF‐α enhanced transfected ds nucleotides‐induced ACE2 expression in RT7 but not GT1. S1 protein alone did not affect CXCL10 expression in either cell type, whereas it enhanced IFN‐β‐induced CXCL10 in both, while immune responses of IFN‐γ‐ and TNF‐α‐induced CXCL10 enhanced by S1 protein were different between RT7 and GT1. Finally, knockdown of ACE2 decreased cytokines and S1 protein mediated‐CXCL10 levels in both cells. Conclusions: ACE2 in oral mucosal cells may contribute to development of infection and inflammation in cooperation with pro‐inflammatory cytokines following SARS‐CoV‐2 invasion. [ABSTRACT FROM AUTHOR]

A wide variety of biomaterials has been developed to assist in wound healing, including acellular animal and human‐derived protein matrices. However, millions of patients worldwide still suffer from non‐healing chronic wounds, demonstrating a need for further innovation in wound care. To address this need, a novel biomaterial, the human keratin matrix (HKM), was developed, characterised, and tested in vitro and in vivo. HKM was found to be degradation‐resistant, and a proteomics analysis showed it to be greater than 99% human keratin proteins. PCR revealed adult human epidermal keratinocytes (HEKa) grown in contact with HKM showed increased gene expression of keratinocyte activations markers such as Epidermal Growth Factor (EGF). Additionally, a cytokine microarray demonstrated culture on HKM increased the release of cytokines involved in wound inflammatory modulation by both HEKa cells and adult human dermal fibroblasts (HDFa). Finally, in a murine chronic wound model, full‐thickness wounds treated weekly with HKM were smaller through the healing process than those treated with human amniotic membrane (AM), bovine dermis (BD), or porcine decellularized small intestinal submucosa (SIS). HKM‐treated wounds also closed significantly faster than AM‐ and SIS‐treated wounds. These data suggest that HKM is an effective novel treatment for chronic wounds. [ABSTRACT FROM AUTHOR]

Although biologics have achieved tremendous success in the treatment of psoriasis and revolutionized the clinical management of the disease, certain issues arise during treatments, including the phenotypic switch from psoriasis to other skin disorders and the recurrence of psoriasis after the cessation of biologic treatment. Here we provide a concise overview of the roles of keratinocytes in the pathogenesis of psoriasis, elucidate the involvement of keratinocytes in the phenotypic switch and relapse of psoriasis, and address the challenges encountered in both basic and clinical research on psoriasis. [ABSTRACT FROM AUTHOR]

Helianthus annuus seed byproduct is a residual product obtained after seed oil extraction. The present study investigated the preventive and repair effects of the H. annuus seed byproduct ethanol extract (HSE) on ultraviolet radiation (UVR)‐induced injury in human immortalized keratinocytes (HaCaTs) and human skin fibroblasts (HSFs). Results revealed that the total phenolic acid and oligosaccharide content in HSE was >50%. HSE had a stronger preventive effect on UVR‐induced injury than the repair effect. Moreover, phenolic acids were the main active component of HSE mediating the preventative effect. In HaCaTs and HSFs, HSE prevented UVR‐induced injury by inhibiting excessive ROS production. It reduced the secretion of tumor necrosis TNF‐α, IL‐1α, IL‐1β, IL‐6, and IL‐8 by inhibiting the level of ROS, thus reducing inflammation‐mediated injury to skin cells. In addition, HSE inhibited the expression of various mRNA kinases in the MAPK–ERK/p38/JNK pathway. This downregulated the expression of activator protein‐1 (AP‐1) mRNA and further reduced the secretion of matrix metalloproteinase (MMP)‐1, MMP‐3, and MMP‐9 as well as reduced UVR‐induced injury to the cells. In conclusion, HSE is a broad‐spectrum, natural UV filter with high efficiency and low toxicity that has the potential to be used in sunscreen products. [ABSTRACT FROM AUTHOR]

Natural products derived from plants can be used as photosensitizers for antimicrobial photodynamic therapy (aPDT) combining key therapeutic strategies for tissue repair while controlling microorganisms' growth. We investigated a standardized extract of pequi peels (Caryocar brasiliense Cambess) as a brownish natural photosensitizer for aPDT using blue light. Three concentrations of the pequi extract (PE; 10, 30, or 90 μg/mL) were tested solely or associated with blue laser (445 nm, 100 mW, 138 J/cm2, 6 J, 60 s). In vitro, we quantified reactive oxygen species (ROS), assessed skin keratinocytes (HaCat) viability and migration, and aPDT antimicrobial activity on Streptococcus or Staphylococcus strains. In vivo, we assessed wound closure for the most active concentration disclosed by the in vitro assay (30 μg/mL). Upon aPDT treatments, ROS were significantly increased in cell monolayers regardless of PE concentration. PE at low doses stimulates epithelial cells. Although PE stimulated cellular migration, aPDT was moderately cytotoxic to skin keratinocytes, particularly at the highest concentration. The antimicrobial activity was observed for PE at the lowest concentration (10 μg/mL) and mostly at PE 10 μg/mL and 30 μg/mL when used as aPDT photosensitizers. aPDT with PE 30 μg/mL presents antimicrobial activity without compromising the initial phases of skin repair. [ABSTRACT FROM AUTHOR]

A persistent infection with human papillomavirus (HPV) can induce precancerous lesions of the cervix that may ultimately develop into cancer. Cervical cancer development has been linked to altered microRNA (miRNA) expression, with miRNAs regulating anchorage‐independent growth being particularly important for the progression of precancerous lesions to cancer. In this study, we set out to identify and validate targets of miR‐129‐5p, a previously identified tumor suppressive miRNA involved in anchorage‐independent growth and HPV‐induced carcinogenesis. We predicted 26 potential miR‐129‐5p targets using online databases, followed by KEGG pathway enrichment analysis. RT‐qPCR and luciferase assays confirmed that 3'UTR regions of six genes (ACTN1, BMPR2, CAMK4, ELK4, EP300, and GNAQ) were targeted by miR‐129‐5p. Expressions of ACTN1, CAMK4, and ELK4 were inversely correlated to miR‐129‐5p expression in HPV‐transformed keratinocytes, and their silencing reduced anchorage‐independent growth. Concordantly, miR‐129‐5p overexpression decreased protein levels of ACTN1, BMPR2, CAMK4 and ELK4 in anchorage‐independent conditions. Additionally, c‐FOS, a downstream target of ELK4, was downregulated upon miR‐129‐5p overexpression, suggesting regulation through the ELK4/c‐FOS axis. ACTN1 and ELK4 expression was also upregulated in high‐grade precancerous lesions and cervical cancers, supporting their clinical relevance. In conclusion, we identified six targets of miR‐129‐5p involved in the regulation of anchorage‐independent growth, with ACTN1, BMPR2, ELK4, EP300, and GNAQ representing novel targets for miR‐129‐5p. For both ACTN1 and ELK4 functional and clinical relevance was confirmed, indicating that miR‐129‐5p‐regulated ACTN1 and ELK4 expression contributes to HPV‐induced carcinogenesis. [ABSTRACT FROM AUTHOR]

Chloride channel accessory 2 (CLCA2) is a transmembrane protein, which promotes adhesion of keratinocytes and their survival in response to hyperosmotic stress. Here we show that CLCA2 is transported to the nucleus of keratinocytes via extracellular vesicles. The nuclear localization is functionally relevant, since wild‐type CLCA2, but not a mutant lacking the nuclear localization signal, suppressed migration of keratinocytes and protected them from hyperosmotic stress‐induced cell death. In the nucleus, CLCA2 bound to and activated β‐catenin, resulting in enhanced expression of Wnt target genes. Mass‐spectrometry‐based interaction screening and functional rescue studies identified RNA binding protein 3 as a key effector of nuclear CLCA2. This is of likely relevance in vivo because both proteins co‐localize in the human epidermis. Together, these results identify an unexpected nuclear function of CLCA2 in keratinocytes under homeostatic and stress conditions and suggest a role of extracellular vesicles and their nuclear transport in the control of key cellular activities. [ABSTRACT FROM AUTHOR]

Background: Natural products are often friendly and can be used on children's skin after systematic and careful research. Therefore, in this study, the Royal Oji Complex (ROC), a product with natural ingredients, was used to study their effectiveness on keratinocytes taken from the skin of children from 0 to 3 years old. Method: Normal human epidermal keratinocytes and tissue‐isolated keratinocytes (TIKC) from young donors were treated with three different concentrations of ROC: 0.1, 1, and 10 ppm. The mRNA expression of the epidermal barrier's essential genes, such as hyaluronic acid synthase 3 (Has3), involucrin (IVL), loricrin (LOR), and claudin‐1 (CLD1) was investigated using qRT‐PCR. Ceramide content was measured by ELISA, with retinoic acid (R.A.) and amarogentin (AMA) serving as positive controls. Results: ROC significantly elevated HAS3 gene expression in HEKn cells, especially at 10 ppm, indicating potential advantages for skin hydration in young infants. IVL increased at first but decreased as ROC concentrations increased. LOR was upregulated at lower ROC concentrations but reduced at higher doses. CLD1 gene expression increased considerably in HEKn but reduced with increasing ROC doses. Ceramide concentration increased somewhat but not significantly at 10 ppm. Conclusion: ROC shows potential in altering keratinocyte gene expression, with unique responses in HEKn and TIKC from young donors. While changes in ceramide content were insignificant, these results help to comprehend ROC's multiple effects on young children's skin. [ABSTRACT FROM AUTHOR]

Objective: Cholesteatoma is a hyperproliferative, pseudoneoplastic lesion of the middle ear characterized by aggressive growth and bone destruction. Hypoxia‐inducible factor‐1α (HIF‐1α, also known as HIF1A) is a key transcription factor that enters the nucleus and upregulates many genes involved in cancer progression in the oxygen‐free environment. This study is designed to explore the role and mechanism of HIF1A in the progression of cholesteatoma. Methods: HIF1A and endothelin converting enzyme 1 (ECE1) levels were determined using real‐time quantitative polymerase chain reaction. The protein levels of HIF1A, Cyclin D1, proliferating cell nuclear antigen, and ECE1 were measured using western blot. Cell viability, proliferation, and cell cycle progression were analyzed using cell counting kit‐8, Colony formation, 5‐ethynyl‐2′‐deoxyuridine, and flow cytometry assays. Binding between HIF‐1α and ECE1 promoter was predicted by Jaspar and verified using Chromatin immunoprecipitation and dual‐luciferase reporter assays. Results: HIF1A and ECE1 were highly expressed in cholesteatoma patients and keratinocytes. Moreover, HIF1A knockdown might suppress the cell viability, proliferation, and cycle progression of cholesteatoma keratinocytes. Furthermore, HIF1A upregulated the transcription of ECE1 through binding to its promoter region. Conclusion: HIF1A might expedite cholesteatoma keratinocyte proliferation partly by increasing ECE1 expression, providing a possible therapeutic target for the cholesteatoma treatment. [ABSTRACT FROM AUTHOR]

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Copyright of Veterinary Dermatology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: Recombinant humanized type III collagen (rhCol III) is a highly adhesive biomaterial composed of 16 adhesion‐related tandem repeats refined from human type III collagen. Here, we aimed to investigate the effect of rhCol III on oral ulcers and reveal the underlying mechanism. Methods: Acid‐induced oral ulcers were induced on the murine tongue, and rhCol III or saline drops were administered. The effect of rhCol III on oral ulcers was assessed using gross and histological analyses. The effects on the proliferation, migration, and adhesion of human oral keratinocytes were investigated in vitro. The underlying mechanism was explored using RNA sequencing. Results: Administration of rhCol III accelerated the lesion closure of oral ulcers, reduced the release of inflammatory factors, and alleviated pain. rhCol III promoted the proliferation, migration, and adhesion of human oral keratinocytes in vitro. Mechanistically, the enrichment of genes associated with the Notch signaling pathway was upregulated after rhCol III treatment. Conclusion: rhCol III promoted the healing of oral ulcers, showing promising therapeutic potential in oral clinics. [ABSTRACT FROM AUTHOR]