PhotoSENSIL-18 assay development: Enhancing the safety testing of cosmetic raw materials and finished products to support the in vitro photosensitization assessment?

Although photosensitization remains a major toxicological endpoint for the safety assessment of cosmetic products and their raw materials, there is no validated in vitro method available for the evaluation of this adverse effect so far. Given that previous studies have proposed that the Interleukine-18 (IL-18) plays a key role in keratinocyte-driven pro-inflammatory responses specific of the skin sensitization process, we hypothesize that IL-18 might be used as a specific biomarker for in vitro photosensitization assessment. The aim of the present study was the set-up of a new in vitro assay using IL-18 as a biomarker for the identification of photosensitizers in a reconstructed human epidermis (RHE) model. EpiCS™ RHE were incubated with a set of 16 known sensitising / phototoxic / photosensitizing substances and exposed to ultra-violet (UV) irradiation. Then, the cell viability was analysed by MTT assay, while the IL-18 secretion was quantified by ELISA. Preliminary assays have shown that 1 h of incubation followed by a recovery period of 23 h induced the highest IL-18 production in response to UV exposure. This protocol was used to test 16 substances and a ratio of IL-18 production (UV+/UV- ratio) was then generated. Our data shows that the cut-off of 1.5 (UV+/UV- ratio) is the most predictive model among the tested conditions, being capable of identifying true positive photosensitizers (8 of 9) with a good prediction in comparison with in vivo data. In a nutshell, our data suggests that the PhotoSENSIL-18 is a promising in vitro method for identification of photosensitizing substances. Although further studies are necessary to optimize the model, we foresee that the PhotoSENSIL-18 assay can be used in the context of an Integrative Approach to Testing and Assessment (IATA) of chemicals.

Updated skin transcriptomic atlas depicted by reciprocal contribution of single-nucleus RNA sequencing and single-cell RNA sequencing

BACKGROUND

Single-cell RNA sequencing (scRNA-seq) has advanced our understanding of skin biology, but its utility is restricted by the requirement of fresh samples, inadequate dissociation-induced cell loss or death, and activation during tissue digestion. Single-nucleus RNA sequencing (snRNA-seq) can use frozen, hard-to-dissociate materials, which might be a promising method to circumvent the limitations of scRNA-seq for the skin tissue.

OBJECTIVE

To profile skin cells using snRNA-seq in parallel with scRNA-seq.

METHODS

We performed snRNA-seq in parallel with scRNA-seq for the bisected skin sample of one person and integrated previously published scRNA-seq data for analysis. We comparatively analyzed the differences in cell proportions and gene expression between the two methods. The differentiation trajectories of keratinocytes and fibroblasts were analyzed by Slingshot analysis.

RESULTS

snRNA-seq was less susceptible to contamination from mitochondrial and ribosomal RNA, and exhibited a greater capacity to detect transcription factors. snRNA-seq identified more spatially and functionally relevant keratinocyte clusters that constitute cell trajectories with expected differentiation dynamics. Novel markers, e.g., LYPD3, EMP2, and CSTB, were revealed for different differentiation stages of keratinocytes, and NFIB and GRHL1 were identified as transcription factors involving in the proliferation and functional differentiation of keratinocytes. Fibroblasts were found in a state of activation in scRNA-seq. And scRNA-seq detected a greater number of immune cells.

CONCLUSIONS

We generated an updated atlas of the skin transcriptome based on the reciprocal contribution of scRNA-seq and snRNA-seq.

Transplantation of human induced pluripotent stem cell derived keratinocytes accelerates deep second-degree burn wound healing

BACKGROUND

Current evidence shows that human induced pluripotent stem cells (hiPSCs) can effectively differentiate into keratinocytes (KCs), but its effect on skin burn healing has not been reported.

AIM

To observe the effects of hiPSCs-derived KCs transplantation on skin burn healing in mice and to preliminarily reveal the underlying mechanisms.

METHODS

An analysis of differentially expressed genes in burn wounds based on GEO datasets GSE140926, and GSE27186 was established. A differentiation medium containing retinoic acid and bone morphogenetic protein 4 was applied to induce hiPSCs to differentiate into KCs. The expression of KCs marker proteins was detected using immunofluorescence staining. A model of a C57BL/6 mouse with deep cutaneous second-degree burn was created, and then phosphate buffered saline (PBS), hiPSCs-KCs, or hiPSCs-KCs with knockdown of COL7A1 were injected around the wound surface. The wound healing, re-epithelialization, engraftment of hiPSCs-KCs into wounds, proinflammatory factor level, and the NF-κB pathway proteins were assessed by hematoxylin-eosin staining, carboxifluorescein diacetate succinimidyl ester (CFSE) fluorescence staining, enzyme linked immunosorbent assay, and Western blotting on days 3, 7, and 14 after the injection, respectively. Moreover, the effects of COL7A1 knockdown on the proliferation and migration of hiPSCs-KCs were confirmed by immunohistochemistry, EdU, Transwell, and damage repair assays.

RESULTS

HiPSCs-KCs could express the hallmark proteins of KCs. COL7A1 was down-regulated in burn wound tissues and highly expressed in hiPSCs-KCs. Transplantation of hiPSCs-KCs into mice with burn wounds resulted in a significant decrease in wound area, an increase in wound re-epithelialization, a decrease in proinflammatory factors content, and an inhibition of NF-κB pathway activation compared to the PBS group. The in vitro assay showed that COL7A1 knockdown could rescue the inhibition of hiPSCs-KCs proliferation and migration, providing further evidence that COL7A1 speeds up burn wound healing by limiting cell proliferation and migration.

CONCLUSION

In deep, second-degree burn wounds, COL7A1 can promote KC proliferation and migration while also suppressing the inflammatory response.

Pharmacological inhibition of demethylzeylasteral on JAK-STAT signaling ameliorates vitiligo

BACKGROUND

The activation of CD8⁺ T cells and their trafficking to the skin through JAK-STAT signaling play a central role in the development of vitiligo. Thus, targeting this key disease pathway with innovative drugs is an effective strategy for treating vitiligo. Natural products isolated from medicinal herbs are a useful source of novel therapeutics. Demethylzeylasteral (T-96), extracted from Tripterygium wilfordii Hook F, possesses immunosuppressive and anti-inflammatory properties.

METHODS

The efficacy of T-96 was tested in our mouse model of vitiligo, and the numbers of CD8⁺ T cells infiltration and melanocytes remaining in the epidermis were quantified using whole-mount tail staining. Immune regulation of T-96 in CD8⁺ T cells was evaluated using flow cytometry. Pull-down assay, mass spectrum analysis, molecular docking, knockdown and overexpression approaches were utilized to identify the target proteins of T-96 in CD8⁺ T cells and keratinocytes.

RESULTS

Here, we found that T-96 reduced CD8⁺ T cell infiltration in the epidermis using whole-mount tail staining and alleviated the extent of depigmentation to a comparable degree of tofacitinib (Tofa) in our vitiligo mouse model. In vitro, T-96 decreased the proliferation, CD69 membrane expression, and IFN-γ, granzyme B, (GzmB), and perforin (PRF) levels in CD8⁺ T cells isolated from patients with vitiligo. Pull-down assays combined with mass spectrum analysis and molecular docking showed that T-96 interacted with JAK3 in CD8⁺ T cell lysates. Furthermore, T-96 reduced JAK3 and STAT5 phosphorylation following IL-2 treatment. T-96 could not further reduce IFN-γ, GzmB and PRF expression following JAK3 knockdown or inhibit increased immune effectors expression upon JAK3 overexpression. Additionally, T-96 interacted with JAK2 in IFN-γ-stimulated keratinocytes, inhibiting the activation of JAK2, decreasing the total and phosphorylated protein levels of STAT1, and reducing the production and secretion of CXCL9 and CXCL10. T-96 did not significantly inhibit STAT1 and CXCL9/10 expression following JAK2 knockdown, nor did it suppress upregulated STAT1-CXCL9/10 signaling upon JAK2 overexpression. Finally, T-96 reduced the membrane expression of CXCR3, and the culture supernatants pretreated with T-96 under IFN-γ stressed keratinocytes markedly blocked the migration of CXCR3⁺CD8⁺ T cells, similarly to Tofa in vitro.

CONCLUSION

Our findings demonstrated that T-96 might have positive therapeutic responses to vitiligo by pharmacologically inhibiting the effector functions and skin trafficking of CD8⁺ T cells through JAK-STAT signaling.

Involvement of necroptosis in the selective toxicity of the natural compound (±) gossypol on squamous skin cancer cells in vitro

Cutaneous basal and squamous cell carcinoma reflect the first and second most common type of non-melanoma skin cancer, respectively. Especially cutaneous squamous cell carcinoma has the tendency to metastasize, finally resulting in a rather poor prognosis. Therapeutic options comprise surgery, radiation therapy, and a systemic or targeted chemotherapy. There are some good treatment results, but overall, the response rate of newly developed drugs is still modest. Drug repurposing represents an alternative approach where already available and clinically approved substances are used, which originally intended for other clinical benefits. In this context, we tested the effect of the naturally occurring polyphenolic aldehyde (±) gossypol with concentrations between 1 and 5 µM on the invasive squamous cell carcinoma cell line SCL-1 and normal human epidermal keratinocytes. Gossypol treatment up to 96 h resulted in a selective cytotoxicity of SCL-1 cells (IC50: 1.7 µM, 96 h) compared with normal keratinocytes (IC50: ≥ 5.4 µM, 96 h) which is mediated by mitochondrial dysfunction and finally leading to necroptotic cell death. Taken together, gossypol shows a high potential as an alternative anticancer drug for the treatment of cutaneous squamous cell carcinoma.

Effect of Au@SiO2 core shell nanoparticles on HG-induced oxidative stress triggered apoptosis in keratinocytes

Growing evidences suggest that excess generation of highly reactive free oxygen/nitrogen radicals (ROS/RNS) are largely due to hyperglycemia causes oxidative stress. Further, excess accumulation of ROS/RNS in cellular compartments aggravates the development and progression of diabetes and its associated complications. Impaired wound healing in diabetic condition is a known vital complication all around the world. Thus, an antioxidant agent having the potential for hindering the oxidative/nitrosative stress triggered diabetic skin complication is required. The present investigation was carried out to understand the impact of silica coated gold nanoparticle (Au@SiO₂ NPs) on high glucose (HG)-induced keratinocyte complications. We demonstrated that HG environment enhanced the ROS and RNS accumulations and reduced in cellular antioxidant capacities in keratinocte cells, however, Au@SiO₂ NPs treatment restored the HG effect. Furthermore, excess production of ROS/RNS was associated with mitochondrial dysfunction, characterized by loss of mitochondrial membrane potential (ΔΨm), and increased in mitochondrial mass, which was restored by Au@SiO₂ NPs treatment in keratinocyte cells. In addition, HG-induced excess production of ROS/RNA caused an increased in the biomolecules damage including lipid peroxidation (LPO), and protein carbonylation (PC), 8-oxoguanine DNA glycosylase-1 (OGG1) expression and increased 8-hydroxydeoxyguanosine (8-OHdG) accumulations in DNA, leading to activation of ERK1/2MAPK, AKT and tuberin pathway, inflammatory reaction, and finally apoptotic cell death. In conclusion, our findings showed that Au@SiO₂ NPs treatment improved the HG-induced keratinocytes injury by suppressing the oxidative/nitrosative stress, elevating the antioxidant defence system, thereby inhibiting the inflammatory mediators and apoptosis, which may be a therapeutic cure for the diabetic keratinocyte problems.

Cholesterol homeostasis in hair follicle keratinocytes is disrupted by impaired ABCA5 activity

The importance of cholesterol in hair follicle biology is underscored by its links to the pathogenesis of alopecias and hair growth disorders. Reports have associated defects in ABCA5, a membrane transporter, with altered keratinocyte cholesterol distribution in individuals with a form of congenital hypertrichosis, yet the biological basis for this defect in hair growth remains unknown. This study aimed to determine the impact of altered ABCA5 activity on hair follicle keratinocyte behaviour. Primary keratinocytes isolated from the outer root sheath of plucked human hair follicles were utilised as a relevant cell model. Following exogenous cholesterol loading, an increase in ABCA5 co-localisation to intracellular organelles was seen. Knockdown of ABCA5 revealed a dysregulation in cholesterol homeostasis, with LXR agonism leading to partial restoration of the homeostatic response. Filipin staining and live BODIPY cholesterol immunofluorescence microscopy revealed a reduction in endo-lysosomal cholesterol following ABCA5 knockdown. Analysis of oxysterols showed a significant increase in the fold change of 25-hydroxycholesterol and 7-β-hydroxycholesterol following cholesterol loading in ORS keratinocytes, after ABCA5 knockdown. These data suggest a role for ABCA5 in the intracellular compartmentalisation of free cholesterol in primary hair follicle keratinocytes. The loss of normal homeostatic response, following the delivery of excess cholesterol after ABCA5 knockdown, suggests an impact on LXR-mediated transcriptional activity. The loss of ABCA5 in the hair follicle could lead to impaired endo-lysosomal cholesterol transport, impacting pathways known to influence hair growth. This avenue warrants further investigation.

Convalescent action of menthol against T-2 mycotoxin-induced toxicity: An in vitro study with HaCaT cells

Only T-2 mycotoxin is emitted as an aerosol and is the most toxic fungal secondary metabolite among mycotoxins. In its clinical condition, the skin is severely irritated and painful due to lesions and alimentary toxic aleukia. Herein, we have assessed various bioactive molecules, viz. kaempferol, menthol, curcumin, and quercetin, against T-2-induced toxicity in HaCaT cells. Menthol offered exceptional protection, protecting 92% of HaCaT cells after exposure to 300 nM T-2 and reducing LDH leakage by up to 42%. Its pre-treatment provided considerable protection against T-2 toxicity, as evidenced by the assessment of mitochondrial membrane potential. Propidium iodide staining revealed a cell cycle halt at the G1, S, and M phases and a significant increase in the sub-G1 percentage in T-2-challenged cells, indicating cell death. However, pre-treatment with menthol promoted cell cycle progression in cells exposed to T-2. Immunoblotting results demonstrated that menthol resulted in a discernible down-regulation of i-NOS expression in T-2-challenged HaCaT cells.

Mulla J, Imam Rabbani S. Evaluation of solid-lipid nanoparticles formulation of methotrexate for anti-psoriatic activity

Background & Objectives

Methotrexate (MTX) is commonly used to manage psoriasis. The drug has erratic absorption characteristics and shows several complications. The present study uses different experimental models to evaluate the solid-lipid nanoparticles of MTX (SLN-MTX) for the anti-psoriatic effect.

Methods

A prepared SLN-MTX formulation was used and its permeability studies were conducted on Wistar rat abdominal skin. The organ-level distribution of the drug in the formulation was tested in mice and the in-vitro anti-psoriatic activity was determined in CL-177; XB-2 keratinocytes cell lines. The efficacy of SLN-MTX formulation was compared with standard MTX and marketed MTX preparations. The results are analyzed statistically using the student's t-test.

Results

The data suggested that MTX from the formulation was slowly released and completely (80.36%) permeated through the skin. The flux and permeation data were found to be maximum for SLN-MTX compared to marketed and standard preparations. MTX in the formulation was found to be distributed more in the liver (67.5%) and kidney (2.34%). Further, SLN-MTX formulation showed dose-dependent inhibition on the growth of keratinocytes, and the cytotoxic concentration (CTC50) was found to be the least (518 mcg/ml).

Interpretation & Conclusion

The findings suggested that MTX in solid-lipid nanoparticles could be a promising formulation for the management of psoriasis since the drug was slowly released, progressively inhibited the growth of keratinocytes, and distributed mostly in organs meant for elimination. More studies in this direction might establish the precise safety and efficacy of SLN-MTX formulation in psoriasis.

Nanofabrication of cobalt-tellurium using Allium sativum extract and its protective efficacy against H2O2-induced oxidative damage in HaCaT cells

Allium sativum (A. sativum)is well known for its therapeutic and culinary uses. Because of their high medicinal properties, the clove extract was selected to synthesize cobalt-tellurium nanoparticles. The aim of the study was to evaluate the protective activity of the nanofabricated cobalt-tellurium using A. sativum (Co-Tel-As-NPs) against H₂O₂-induced oxidative damage in HaCaT cells. Synthesized Co-Tel-As-NPs were analyzed using UV-Visible spectroscopy, FT-IR, EDAX, XRD, DLS, and SEM. Various concentrations of Co-Tel-As-NPs were used as a pretreatment on HaCaT cells before H₂O₂ was added. Then, the cell viability and mitochondrial damage were compared between pretreated and untreated control cells using an array of assays (MTT, LDH, DAPI, MMP, and TEM), and the intracellular ROS, NO, and antioxidant enzyme production were examined. In the present research, Co-Tel-As-NPs at different concentrations (0.5, 1.0, 2.0, and 4.0μg/mL) were tested for toxicity using HaCaT cells. Furthermore, the effect of H₂O₂ on the viability of HaCaT cells was evaluated using the MTT assay for Co-Tel-As-NPs. Among those, Co-Tel-As-NPs at 4.0 μg/mL showed notable protection; with the same treatment, cell viability was discovered to be 91% and LDH leakage was also significantly decreased. Additionally, the measurement of mitochondrial membrane potential was significantly decreased by Co-Tel-As-NPs pretreatment against H₂O₂. The recovery of the condensed and fragmented nuclei brought about by the action of Co-Tel-As-NPs was identified using DAPI staining. TEM examination of the HaCaT cells revealed that the Co-Tel-As-NPs had a therapeutic effect against H₂O₂ keratinocyte damage.

The human discs large protein 1 interacts with and maintains connexin 43 at the plasma membrane in keratinocytes

Gap junction channels, composed of connexins, allow direct cell-to-cell communication. Connexin 43 (Cx43; also known as GJA1) is widely expressed in tissues, including the epidermis. In a previous study of human papillomavirus-positive cervical epithelial tumour cells, we identified Cx43 as a binding partner of the human homologue of Drosophila Discs large (Dlg1; also known as SAP97). Dlg1 is a member of the membrane associated-guanylate kinase (MAGUK) scaffolding protein family, which is known to control cell shape and polarity. Here, we show that Cx43 also interacts with Dlg1 in uninfected keratinocytes in vitro and in keratinocytes, dermal cells and adipocytes in normal human epidermis in vivo. Depletion of Dlg1 in keratinocytes did not alter Cx43 transcription but was associated with a reduction in Cx43 protein levels. Reduced Dlg1 levels in keratinocytes resulted in a reduction in Cx43 at the plasma membrane with a concomitant reduction in gap junctional intercellular communication and relocation of Cx43 to the Golgi compartment. Our data suggest a key role for Dlg1 in maintaining Cx43 at the plasma membrane in keratinocytes.

In vitro effects of undifferentiated callus extracts from Plantago major L, Rhodiola rosea L and Silybum marianum L in normal and malignant human skin cells

Background and objectives

The occurrence of non-melanoma and melanoma skin cancers is currently increasing rapidly with one in every three cancers diagnosed as a skin cancer. A useful strategy to control the progression of skin cancer could be the use of plant flavonoids that suppress pro-inflammatory cytokines involved in tumor initiation and progression. In this study, the anti-inflammatory and antioxidant activity of undifferentiated callus extracts from Plantago major L, Silybum marianum L and Rhodiola rosea L was investigated both in normal and malignant skin cells.

Methods

Antioxidant activity of the extracts was analyzed by using the Trolox Equivalent Antioxidant Capacity (TEAC) assay. High-Performance Thin-Layer Chromatography (HPTLC) was performed to demonstrate the phytochemical profile, and the total flavonoid content was analyzed with an aluminum chloride colorimetric method. The anti-inflammatory effect was investigated by cell treatments using the plant extracts. Thereafter, the possible suppression of induced IL-6 response was measured from the cultured skin cancer cell lines A2058 and A431, and normal primary keratinocytes with Enzyme-Linked Immunosorbent Assay (ELISA).

Results

The HPTLC analysis assessed that the extracts contained a complex phytochemical profile that was rich in phenolic and flavonoid compounds. Dose response assays showed that concentrations between 15 and 125 μg/mL of all three plant extracts could be used to investigate an effect on the IL-6 production. The S. marianum extract had the most pronounced anti-inflammatory effect, which significantly inhibited induced IL-6 production in both normal keratinocytes and skin cells derived from epidermal carcinoma. The extract from S. marianum also had the highest flavonoid content and showed the highest antioxidant activity of the three extracts tested.

Conclusion

All in all, we have confirmed that undifferentiated callus extracts of S. marianum possess properties such as antioxidant and anti-inflammatory activities in both normal and malignant keratinocytes, and thus could be a promising agent controlling the pro-inflammatory IL-6 production.

Transcriptomics reveals key regulatory pathways and genes associated with skin diseases induced by face paint usage

The use of face paint cosmetics can cause skin diseases in opera performers due to the presence of heavy metals and other toxic ingredients in the cosmetics. However, the underlying molecular mechanism for these diseases remains unknown. Here we examined the transcriptome gene profile of human skin keratinocytes exposed to artificial sweat extracts of face paints, and identified the key regulatory pathways and genes, using RNA sequencing technique. Bioinformatics analyses suggested that the face paint exposure induced the differentially expression of 1531 genes and enriched inflammation-relevant TNF and IL-17 signaling pathways after just 4 h of exposure. Inflammation-relevant genes CREB3L3, FOS, FOSB, JUN, TNF, and NFKBIA were identified as the potential regulatory genes, and SOCS3 capable to prevent inflammation-induced carcinogenesis as the hub-bottleneck gene. Long-term exposure (24 h) could exacerbate inflammation, accompanied by interference in cellular metabolism pathways, and the potential regulatory genes (ATP1A1, ATP1B1, ATP1B2, FXYD2, IL6, and TNF) and hub-bottleneck genes (JUNB and TNFAIP3) were all related to inflammation induction and other adverse responses. We proposed that the exposure to face paint might cause the inflammatory factors TNF and IL-17, which are encoded by the genes TNF and IL17, to bind to receptors and activate TNF and IL-17 signaling pathways, leading to the expression of cell proliferation factors (CREB and AP-1) and proinflammatory mediators including transcription factors (FOS, JUN, and JUNB), inflammatory factors (TNF-α and IL6), and intracellular signaling factors (TNFAIP3). This finally resulted in cell inflammation, apoptosis, and other skin diseases. TNF was identified as the key regulator and connector in all the enriched signaling pathways. Our study provides the first insights into the cytotoxicity mechanism of face paints to skin cells and highlights the need for stricter regulations in face paint safety.

Hexavalent chromium disrupts the skin barrier by targeting ROS-mediated mitochondrial pathway apoptosis in keratinocytes

Hexavalent chromium (Cr(VI)), a toxic heavy metal, is ubiquitous in daily life. Exposure to this toxic substance in occupational settings can cause dermatitis and cancer. As the body's largest organ, the skin plays a crucial role in protecting the organism against external aggressions. While previous studies have focused on the effects of Cr(VI) on skin inflammation, this study investigates the potential toxicity of Cr(VI) from the skin barrier and integrity perspective. The in vivo results of this study showed that mice exposed to Cr(VI) experienced skin deterioration and hemorrhaging, as well as a reduction in the thickness of the collagen fiber layer. TUNEL and Occludin staining results revealed that Cr(VI)'s toxicity primarily targeted keratinocytes. Experiments in vitro demonstrated that Cr(VI) treatment decreased the activity of HaCaT cells, altered cell morphology, and increased LDH secretion. Further research revealed that Cr(VI) could modify membrane permeability, impair membrane integrity, and reduce the protein expression of ZO-1 and Occludin. In addition, it was discovered that Cr(VI) promoted cell apoptosis and inhibited AKT activation. However, the addition of a caspase inhibitor and an AKT activator prevented Cr(VI)-induced injury to the cell membrane barrier, indicating that apoptosis plays a crucial role in this process. The addition of three apoptotic pathway inhibitors, confirmed that Cr(VI) damaged the cell barrier through ROS-mediated mitochondrial pathway apoptosis. Moreover, the use of a ROS inhibitor significantly reduced Cr(VI)-induced apoptosis and cell barrier injury. In conclusion, this study provides an experimental foundation for the treatment of skin injury caused by Cr(VI).

Roles of TRPM4 in immune responses in keratinocytes and identification of a novel TRPM4-activating agent

The skin is a protective interface between the internal organs and environment and functions not only as a physical barrier but also as an immune organ. However, the immune system in the skin is not fully understood. A member of the thermo-sensitive transient receptor potential (TRP) channel family, TRPM4, which acts as a regulatory receptor in immune cells, was recently reported to be expressed in human skin and keratinocytes. However, the function of TRPM4 in immune responses in keratinocytes has not been investigated. In this study, we found that treatment with BTP2, a known TRPM4 agonist, reduced cytokine production induced by tumor necrosis factor (TNF) α in normal human epidermal keratinocytes and in immortalized human epidermal keratinocytes (HaCaT cells). This cytokine-reducing effect was not observed in TRPM4-deficient HaCaT cells, indicating that TRPM4 contributed to the control of cytokine production in keratinocytes. Furthermore, we identified aluminum potassium sulfate, as a new TRPM4 activating agent. Aluminum potassium sulfate reduced Ca²⁺ influx by store-operated Ca²⁺ entry in human TRPM4-expressing HEK293T cells. We further confirmed that aluminum potassium sulfate evoked TRPM4-mediated currents, showing direct evidence for TRPM4 activation. Moreover, treatment with aluminum potassium sulfate reduced cytokine expression induced by TNFα in HaCaT cells. Taken together, our data suggested that TRPM4 may serve as a new target for the treatment of skin inflammatory reactions by suppressing the cytokine production in keratinocytes, and aluminum potassium sulfate is a useful ingredient to prevent undesirable skin inflammation through TRPM4 activation.

Lupeol alleviates atopic dermatitis-like skin inflammation in 2,4-dinitrochlorobenzene/Dermatophagoides farinae extract-induced mice

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease that affects from children to adults widely, presenting symptoms such as pruritus, erythema, scaling, and dryness. Lupeol, a pentacyclic triterpenoid, has anti-inflammatory and antimicrobial activities. Based on these properties, the therapeutic effects of lupeol on skin disorders have been actively studied. In the present study, we aimed to determine the effectiveness of lupeol on AD.

METHODS

We utilized tumor necrosis factor (TNF)-α/interferon (IFN)-γ-stimulated keratinocytes and 2, 4-dinitrochlorobenzene/Dermatophagoides farinae extract (DFE)-induced AD mice to confirm the action.

RESULTS

Lupeol inhibited TNF-α/IFN-γ-stimulated keratinocytes activation by reducing the expressions of pro-inflammatory cytokines and chemokines which are mediated by the activation of signaling molecules such as signal transducer and activator of transcription 1, mitogen-activated protein kinases (p38 and ERK), and nuclear factor-κB. Oral administration of lupeol suppressed epidermal and dermal thickening and immune cell infiltration in ear tissue. Immunoglobulin (Ig) E (total and DFE-specific) and IgG2a levels in serum were also reduced by lupeol. The gene expression and protein secretion of T helper (Th) 2 cytokines, Th1 cytokines, and pro-inflammatory cytokine in ear tissue were decreased by lupeol.

CONCLUSIONS

These results suggest that lupeol has inhibitory effects on AD-related responses. Therefore, lupeol could be a promising therapeutic agent for AD.

Assessment of antibacterial properties and skin irritation potential of anodized aluminum impregnated with various quaternary ammonium

The importance of the inert environment in the transmission of pathogens has been reassessed in recent years. To reduce cross-contamination, new biocidal materials used in high touch surfaces (e.g., stair railings, door handles) have been developed. However, their impact on skin remains poorly described. The present study aimed to evaluate the antibacterial properties and the risk of skin irritation of two materials based on hard-anodized aluminum (AA) impregnated with quaternary ammonium compound solutions (QAC#1 or QAC#2). The QAC#1 or QAC#2 solutions vary in composition, QAC#2 being free of dioctyl dimethyl ammonium chloride (Dio-DAC) and octyl decyl dimethyl ammonium chloride (ODDAC). Unlike AA used as a control, both AA-QAC#1 and AA-QAC#2 had excellent and rapid antibacterial efficacy, killing 99.9 % of Staphylococcus aureus and Escherichia coli bacteria, in 15 s and 1 min, respectively. The impregnation solutions (QAC#1 and QAC#2) did not show any skin sensitizing effect on transformed human keratinocytes. Nevertheless, these solutions as well as the materials (AA-QAC#1, AA-QAC#2), and the liquid extracts derived from them, induced a very rapid cytotoxicity on L929 murine fibroblasts (>70 % after 1 h of contact) as shown by LDH, MTS and neutral red assays. This cytotoxicity can be explained by the fast QACs release occurring when AA-QAC#1 and AA-QAC#2 were immersed in aqueous medium. To overcome the limitation of assays based on liquid condition, an in vitro skin irritation assay on reconstructed human epidermis (RHE) was developed. The effect of the materials upon their direct contact with the epidermis grown at the liquid-air interface was determined by evaluating tissue viability and quantifying interleukin-1 alpha (IL-1α) which is released in skin during injury or infection. AA-QAC#1 induced a significant decrease in RHE viability, close to OECD and ISO 10993-10 acceptability thresholds and enhanced the pro-inflammatory IL-1α secretion compared with AA-QAC#2. Finally, these results were corroborated by in vivo assays on mice using erythema and edema visual scores, histological observations, and epidermal thickness measurement. AA had no effect on the skin, while a stronger irritation was induced by AA-QAC#1 compared with AA-QAC#2. Hence, these materials were classified as moderate and slight irritants, respectively. In summary, this study revealed that AA-QAC#2 without Dio-DAC and ODDAC could be a great candidate for high touch surface applications, showing an extremely effective and rapid bactericidal activity, without inducing adverse effects for skin tissue.

HAI-1 is required for the novel role of FGFBP1 in maintenance of cell morphology and F-actin rearrangement in human keratinocytes

Formation and maintenance of skin barrier function require tightly controlled membrane-associated proteolysis, in which the integral membrane Kunitz-type serine protease inhibitor, HAI-1, functions as the primary inhibitor of the membrane-associated serine proteases, matriptase and prostasin. Previously, HAI-1 loss in HaCaT human keratinocytes resulted in an expected increase in prostasin proteolysis but a paradoxical decrease in matriptase proteolysis. The paradoxical decrease in shed active matriptase is further investigated in this study with an unexpected discovery of novel functions of fibroblast growth factor-binding protein 1 (FGFBP1), which acts as an extracellular ligand that can rapidly elicit F-actin rearrangement and subsequently affect the morphology of human keratinocytes. This novel growth factor-like function is in stark contrast to the canonical activity of this protein through interactions with FGFs for its pathophysiological functions. This discovery began with the observation that HAI-1 KO HaCaT cells lose the characteristic cobblestone morphology of the parental cells and exhibit aberrant F-actin formation along with altered subcellular targeting of matriptase and HAI-2. The alterations in cell morphology and F-actin status caused by targeted HAI-1 deletion can be restored by treatment with conditioned medium from parental HaCaT cells, in which FGFBP1 was identified by tandem mass spectrometry. Recombinant FGFBP1 down to 1 ng/ml was able to revert the changes caused by HAI-1 loss. Our study reveals a novel function of FGFBP1 in the maintenance of keratinocyte morphology, which depends on HAI-1.

Involvement of type-1 pathway in phototoxicity of benzo[ghi]perylenean ingredient of tattoo ink at ambient exposure of UVR and sunlight

Tattooing on different parts of the body is a very common fashion trend in all sections of society globally. Skin allergies and other related skin diseases are very common among tattoo users. Benzo[ghi]perylene (BP) is a PAH and an important component of tattoo ink that showed prominent absorption under ultraviolet radiation (UVR) region. Therefore, to provide safety to the skin, a thorough safety study of BP exposed under UVR and Sunlight is very essential to understand their hazardous impact on the skin. BP showed a strong absorption of UVA and UVB radiation of sunlight. It is photolabile and degraded under UVA, UVB, and Sunlight in progressing order of time (1-4 h) without generating any novel photoproducts. Further, BP showed a specific generation of O₂^.- and OH radicals via activation of type I photodynamic reaction under exposure to UVA, UVB and Sunlight. Photocytotoxicity results illustrated concentration-dependent cell viability reduction in all exposure conditions of UVA, UVB, and Sunlight, respectively. Fluorescent probes (2',7'-dichlorofluorescein diacetate and dihydroethidium) for intracellular reactive oxygen species (ROS) generation supported the involvement of ROS in the phototoxicity of BP in the HaCaT cell line. Hoechst staining showed significant genomic insult induced by BP under UVA and UVB. Photoexcited BP promoted cell cycle arrest in the G1 phase and induced apoptosis confirmed via acridine orange/ethidium bromide staining. The findings of gene expression also supported apoptotic cell death in photoexcited BP via an increase in the level of pro-apoptotic gene (Bax) and a decrease in the level of anti-apoptotic gene (Bcl-2). The aforementioned finding indicates that tattoo users should avoid using BP since it can cause skin damage/diseases if they are exposed to UVR or Sunlight while tattooing on the body.

Advanced Therapy Medicinal Products in Vitiligo; Current Status, Future Prospect, and Approved Treatments

Vitiligo is an auto-immune disease, causing depigmentation of skin in 0.2-1.8% of global population. Topical corticosteroids and calcineurin inhibitors are the only treatments with firm evidence of optimal effectiveness with considerable side effects. Phototherapies might not induce serious side effects, although the effectiveness of the method is limited. Advanced therapy medicinal products (ATMPs) are emerging treatment modalities based on correction and replacement of affected genes, damaged tissues or cells in treatment of difficult-to-treat diseases. Due to optimal effectiveness and minimal side effects, ATMPs have recently gained much attention in order to develop new treatments. In this review, the ATMPs for treating vitiligo were along with its clinical success, affordability and cost-effectiveness. Currently, the main ATMP based products using in treatment of vitiligo are non-cultured epidermal cell, melanocytes, and hair follicle melanocytes. These products have shown promising results in the non-responding vitiligo patients. Furthermore, mesenchymal stem cells and multi-lineage differentiating stress enduring cells are other new potential modalities. Recently, Iranian Food and Drug Administration (IR-FDA) authorized the first cell-based product for vitiligo. This product is autologous suspension of keratinocytes and melanocytes. Although ATMPs are efficient and could be cost-effective in long term, the most important obstacle is affordability of them. This could be facilitated by insurance companies and instalments payment programs from manufacturers.

Design and in vitro effectiveness evaluation of Echium amoenum extract loaded in bioadhesive phospholipid vesicles tailored for mucosal delivery

The Echium amoenum Fisch. and C.A. Mey. (E. amoenum) is an herb native from Iranian shrub, and its blue-violet flowers are traditionally used as medical plants. In the present study, an antioxidant phytocomplex was extracted from the flowers of E. amoenum by ultrasounds-assisted hydroalcoholic maceration. The main components, contained in the extract, have been detected using HPLC-DAD, and rosmarinic acid was found to be the most abundant. The antioxidant power of the extract along with the phenolic content were measured using colorimetric assays. The extract was loaded in liposomes, which were enriched adding different bioadhesive polymers (i.e., mucin, xanthan gum and carboxymethyl cellulose sodium salt) individually or in combination. The main physico-chemical properties (i.e. size, size distribution, surface charge) of the prepared vesicles were measured as well as their stability on storage. The viscosity of dispersion and the ability of vesicles to interact with mucus were evaluated measuring their stability in a mucin dispersion and mobility in a mucin film. The biocompatibility and the ability of the formulations to protect keratinocytes from damages caused by hydrogen peroxide and to promote the cell migration were measured in vitro.

FXYD3 enhances IL-17A signaling to promote psoriasis by competitively binding TRAF3 in keratinocytes

Psoriasis is a common chronic inflammatory skin disease characterized by inflammatory cell infiltration and epidermal hyperplasia. However, the regulatory complexity of cytokine and cellular networks still needs to be investigated. Here, we show that the expression of FXYD3, a member of the FXYD domain-containing regulators of Na+/K+ ATPases family, is significantly increased in the lesional skin of psoriasis patients and mice with imiquimod (IMQ)-induced psoriasis. IL-17A, a cytokine important for the development of psoriatic lesions, contributes to FXYD3 expression in human primary keratinocytes. FXYD3 deletion in keratinocytes attenuated the psoriasis-like phenotype and inflammation in an IMQ-induced psoriasis model. Importantly, FXYD3 promotes the formation of the IL-17R-ACT1 complex by competing with IL-17R for binding to TRAF3 and then enhances IL-17A signaling in keratinocytes. This promotes the activation of the NF-κB and MAPK signaling pathways and leads to the expression of proinflammatory factors. Our results clarify the mechanism by which FXYD3 serves as a mediator of IL-17A signaling in keratinocytes to form a positive regulatory loop to promote psoriasis exacerbation. Targeting FXYD3 may serve as a potential therapeutic approach in the treatment of psoriasis.

Immunomodulatory effect of dopamine in human keratinocytes and macrophages under chronical bisphenol-A exposure conditions

Dopamine is a key neurotransmitter that links the nervous and the immune system. Bisphenol A (BPA) is an endocrine disruptor with a wide distribution in the environment that is used in the manufacturing of plastic products. Evidence shows that BPA can interfere with the central dopaminergic transmission; however, there are no previous reports of this effect outside the central nervous system. Thus, the aim of this work was to investigate the in vitro mechanisms of action involved in the response to dopamine in both human keratinocyte and macrophage cell lines chronically exposed to BPA. Dopamine modulates cytokine secretion and NF-κB expression in BPA-treated HaCaT keratinocytes, without modifying these parameters in BPA-treated THP-1 macrophages. In addition, dopamine increases MMP activity in both BPA-treated cell lines, although it decreases keratinocytes migration. We suggest the immunomodulatory effect of dopamine might be different in keratinocytes and macrophages under chronical BPA exposure conditions. These findings revealed for the first time the in vitro immunomodulatory effect of dopamine in the presence of BPA at peripheral level.

Expression of PKM2 in wound keratinocytes is coupled to angiogenesis during skin repair in vivo and in HaCaT keratinocytes in vitro

An injured skin is rapidly restored in a manner of wound healing. We have previously shown that intact insulin signaling and glucose uptake are fundamental to proper wound closure. Consequently, under exacerbated inflammation, compromised insulin action and glucose uptake lead to impaired healing. However, in spite of the increased attention to cell metabolism during tissue regeneration, metabolic mediators that govern cellular and physiological processes throughout skin repair remained largely elusive. Through assessment of mRNA using real-time PCR and protein blot analysis, we report that healing of cutaneous wounds comprise a boosted expression of genes involved in glycolysis, oxidative phosphorylation, pentose phosphate shunt, and glutamine anaplerosis. We further focused on the functional role of pyruvate kinase M (PKM) isoenzymes that catalyze the final and rate-limiting step of glycolysis. Whereas the expression of the metabolic constitutively active Pkm1 isozyme remained almost unchanged, Pkm2 is augmented during the inflammatory phase of healing. The immunohistochemistry and RNA in situ hybridization analysis showed a confined Pkm2 expression to keratinocytes of the hyperproliferative epithelium and, to a lesser extent, infiltrating neutrophils and monocytes as well as later on in macrophages. Notably, the expression of Pkm2 in keratinocytes facing the wound bed side colocalized with VEGF expression. The in vitro knockdown of PKM2 in HaCaT keratinocytes using small interfering (si) RNA confirmed an acute role for PKM2 in facilitating the complete induction of VEGF mRNA and protein expression in keratinocytes; this function is mainly HIF-1α independent. KEY MESSAGES: • Wound healing involves activation of glycolysis, oxidative phosphorylation, pentos-phosphate shunt, and replenishment of tri-carboxylic acid (TCA) cycle through glutamine anaplerosis. • The pyruvate kinase M2 (PKM2) isoform is upregulated during the inflammatory phase of cutaneous healing, mainly in keratinocytes of hyperproliferative epithelia. • In vivo, the expression of VEGF in wound keratinocytes is colocalized with PKM2. • PKM2 is required for full induction of VEGF in HaCaT keratinocytes in vitro.

CircVAPA contributes to hyper-proliferation and inflammation of keratinocytes through miR-125b-5p/sirt6 axis in psoriasis

Psoriasis is an autoimmune skin disease with abnormal keratinocyte hyperproliferation. The important roles of circular RNAs (circRNAs) in various inflammatory diseases have been revealed. The present study aimed to investigate the roles of circVAPA and its molecular mechanisms in psoriasis. Quantitative real-time polymerase chain reaction was performed to measure the RNA expression. Enzyme-linked immunosorbent assays were employed to examine the production of inflammatory factors. Cell-counting kit-8, EDU and flow cytometry assay were conducted to examine the cell viability, proliferation and apoptosis respectively. Dual-luciferase reporter assay and ribonucleoprotein immunoprecipitation (RIP) were conducted to verify the target relationship between miR-125b-5p and circVAPA or Sirt6. Herein our findings showed increased expression of circVAPA and Sirt6 and decreased level of miR-125b-5p in psoriatic lesional tissues and M5-stimulated keratinocytes. Mechanistically, circVAPA knockdown significantly suppressed the promotion of M5 on cell viability, proliferation, and inflammation of HaCaT cells. circVAPA was verified to interact with miR-125b-5p, while inhibition of miR-125b-5p counteracted circVAPA knockdown-mediated effects in M5-stimulated HaCaT cells. Sirt6 was confirmed as a target of miR-125b-5p, and miR-125b-5p overexpression inhibited cell growth and inflammation partly by targeting Sirt6 in M5-stimulated HaCaT cells. Moreover, circVAPA was featured as a competing endogenous RNA by directly sponging miR-125b-5p to up-regulate the expression of Sirt6. CircVAPA participate in the progression of psoriasis through miR-125b-5p/sirt6 axis by regulating proliferation and inflammation of keratinocytes, highlighting a potential therapeutic target for psoriasis.