Expression Of Keratinocyte Differentiation Markers Research Articles

Electrical Impedance Spectroscopy Quantifies Skin Barrier Function in Organotypic In Vitro Epidermis Models

3 D human epidermal equivalents (HEEs) are a state-of-the-art organotypic culture model in pre-clinical investigative dermatology and regulatory toxicology. Here, we investigated the utility of electrical impedance spectroscopy (EIS) for non-invasive measurement of HEE epidermal barrier function. Our setup comprised a custom-made lid fit with 12 electrode pairs aligned on the standard 24-transwell cell culture system. Serial EIS measurements for seven consecutive days did not impact epidermal morphology and readouts showed comparable trends to HEEs measured only once. We determined two frequency ranges in the resulting impedance spectra: a lower frequency range termed EISdiff correlated with keratinocyte terminal differentiation independent of epidermal thickness and a higher frequency range termed EISSC correlated with stratum corneum thickness. HEEs generated from CRISPR/Cas9 engineered keratinocytes that lack key differentiation genes FLG, TFAP2A, AHR or CLDN1 confirmed that keratinocyte terminal differentiation is the major parameter defining EISdiff. Exposure to pro-inflammatory psoriasis- or atopic dermatitis-associated cytokine cocktails lowered the expression of keratinocyte differentiation markers and reduced EISdiff. This cytokine-associated decrease in EISdiff was normalized after stimulation with therapeutic molecules. In conclusion, EIS provides a non-invasive system to consecutively and quantitatively assess HEE barrier function and to sensitively and objectively measure barrier development, defects and repair.

Epidermal loss of Bcl6 exacerbates MC903-induced atopic dermatitis-like skin inflammation

Atopic dermatitis (AD) is a chronic inflammatory skin disease where Th2-type immune responses are dominant. In the lesional skin of AD, keratinocytes show differentiation defects and secrete proinflammatory cytokines and chemokines, amplifying Th2-type responses in AD. We previously reported that inducible loss of B-cell lymphoma 6 (Bcl6), a transcription repressor and a master transcriptional regulator of follicular helper T cells and germinal center B cells, in the whole body results in upregulation of Th2-related cytokines in mouse skin. However, the role of Bcl6 in keratinocytes remains to be clarified. Here, we observed that BCL6 positively regulates the expression of keratinocyte differentiation markers and plasma membrane localization of adherence junctional proteins in keratinocyte cell culture. Although keratinocyte-specific loss of Bcl6 alone did not induce AD-like skin inflammation, it aggravates MC903-induced AD-like skin inflammation in mice. In addition, Bcl6 expression is decreased in the epidermis of lesional skin from MC903-induced AD-like skin inflammation in mice. These results strongly suggest that Bcl6 downregulation in keratinocytes contributes to the development and aggravation of AD-like skin inflammation in mice.

The HPV8 E6 protein targets the Hippo and Wnt signaling pathways as part of its arsenal to restrain keratinocyte differentiation.

Human papillomaviruses (HPVs) infect basal epithelial cells and cause a dramatic expansion of basal-like, proliferative cells. This reflects the ability of papillomaviruses to delay keratinocyte differentiation, thereby maintaining aspects of the basal cell identity of persistently infected cells. This may enable papillomaviruses to establish and maintain long-term infections in squamous epithelial tissues. Previous work has revealed that the ability of β-HPV8 E6 protein to inhibit Notch and transforming growth factor β signaling importantly contributes to this activity. Here, we present evidence that HPV8 E6 also subverts Hippo and Wnt signaling and that these activities also aid in restraining keratinocyte differentiation.

IL-6 and TGF-β-Secreting Adoptively-Transferred Murine Mesenchymal Stromal Cells Accelerate Healing of Psoriasis-like Skin Inflammation and Upregulate IL-17A and TGF-β.

Mesenchymal stromal cells (MSC) show promise as cellular therapeutics. Psoriasis is a chronic inflammatory disease affecting the skin and the joints. Injury, trauma, infection and medications can trigger psoriasis by disrupting epidermal keratinocyte proliferation and differentiation, which activates the innate immune system. Pro-inflammatory cytokine secretion drives a T helper 17 response and an imbalance of regulatory T cells. We hypothesized that MSC adoptive cellular therapy could immunomodulate and suppress the effector T cell hyperactivation that underlies the disease. We used the imiquimod-induced psoriasis-like skin inflammation model to study the therapeutic potential of bone marrow and adipose tissue-derived MSC in vivo. We compared the secretome and the in vivo therapeutic potential of MSC with and without cytokine pre-challenge ("licensing"). The infusion of both unlicensed and licensed MSC accelerated the healing of psoriatic lesions, and reduced epidermal thickness and CD3+ T cell infiltration while promoting the upregulation of IL-17A and TGF-β. Concomitantly, the expression of keratinocyte differentiation markers in the skin was decreased. However, unlicensed MSC promoted the resolution of skin inflammation more efficiently. We show that MSC adoptive therapy upregulates the transcription and secretion of pro-regenerative and immunomodulatory molecules in the psoriatic lesion. Accelerated healing is associated with the secretion of TGF-β and IL-6 in the skin and MSC drives the production of IL-17A and restrains T-cell-mediated pathology.

Heme Oxygenase-1 Is Upregulated during Differentiation of Keratinocytes but Its Expression Is Dispensable for Cornification of Murine Epidermis.

The epidermal barrier of mammals is initially formed during embryonic development and continuously regenerated by the differentiation and cornification of keratinocytes in postnatal life. Cornification is associated with the breakdown of organelles and other cell components by mechanisms which are only incompletely understood. Here, we investigated whether heme oxygenase 1 (HO-1), which converts heme into biliverdin, ferrous iron and carbon monoxide, is required for normal cornification of epidermal keratinocytes. We show that HO-1 is transcriptionally upregulated during the terminal differentiation of human keratinocytes in vitro and in vivo. Immunohistochemistry demonstrated expression of HO-1 in the granular layer of the epidermis where keratinocytes undergo cornification. Next, we deleted the Hmox1 gene, which encodes HO-1, by crossing Hmox1-floxed and K14-Cre mice. The epidermis and isolated keratinocytes of the resulting Hmox1f/f K14-Cre mice lacked HO-1 expression. The genetic inactivation of HO-1 did not impair the expression of keratinocyte differentiation markers, loricrin and filaggrin. Likewise, the transglutaminase activity and formation of the stratum corneum were not altered in Hmox1f/f K14-Cre mice, suggesting that HO-1 is dispensable for epidermal cornification. The genetically modified mice generated in this study may be useful for future investigations of the potential roles of epidermal HO-1 in iron metabolism and responses to oxidative stress.

Preventative Effects of Antioxidants against PM10 on Serum IgE Concentration, Mast Cell Counts, Inflammatory Cytokines, and Keratinocyte Differentiation Markers in DNCB-Induced Atopic Dermatitis Mouse Model.

Particulate matter (PM) can cause oxidative stress, inflammation, and skin aging. We investigated the effects of antioxidants such as dieckol, punicalagin, epigallocatechin gallate (EGCG), resveratrol, and Siegesbeckiae Herba extract (SHE) against PM < 10 μm (PM10) on serum IgE concentration, mast cell counts, inflammatory cytokines, and keratinocyte differentiation markers in a 2,4-Dinitrochlorobenzene (DNCB)-induced atopic dermatitis mouse model. Seven-week-old BALB/c mice were sensitized with 2% DNCB. Atopic dermatitis-like lesions were induced on the mice with 0.2% DNCB. Antioxidants and PM10 were applied to the mice for 4 weeks. PM10 increased the serum IgE concentration and spleen weight in mice, and all antioxidants downregulated these parameters. Histological examination showed an increase in epidermal thickness and mast cell counts in response to PM10, and all antioxidants showed a decrease. PM10 upregulates the expression of inflammatory cytokines, including interleukin (IL)-1β, IL-4, IL-6, IL-17α, IL-25, IL-31 and thymic stromal lymphopoietin (TSLP) in mice, and all antioxidants inhibited the upregulation of inflammatory cytokines. ELISA showed the same results as real-time PCR. PM10 downregulates the expression of keratinocyte differentiation markers, including loricrin and filaggrin, in mouse keratinocytes and antioxidants prevented the downregulation of the keratinocyte differentiation markers. Conclusively, PM10 aggravated the DNCB-induced mouse model in serum IgE concentration, mast cell counts, inflammatory cytokine, and keratinocyte differentiation markers. In addition, antioxidants modulated changes in the DNCB-induced mouse model caused by PM10.

Ozonized glycerin (OG)-based cosmetic products lighten age spots on human facial skin.

BackgroundFew cosmetic ingredients are shown to be able to safely remove or lighten facial dark spots once they have formed. OG has been reported to possess oxidation power and exhibit various biological activities such as antibacterial, antiviral, and wound healing promotion.AimsThis study aimed to clarify the effects of OG on human skin, especially on age spots on the face.MethodsOG formulations (80 and 800 ppm) were mixed with synthetic melanin in vitro for 4 weeks and then assessed for its ability to degrade the melanin. OG also investigated its effect on gene expression of keratinocyte differentiation markers in vitro to explore the cell maturation. In clinical study for the evaluation of effects of OG formulations on age spots on facial skin, 48 women were measured for the melanin content of them by a Mexameter at 4 and 8 weeks after daily twice application of OG formulations. Adverse events were monitored during the study.ResultsBoth OG formulations showed direct melanin degradation in a time‐dependent manner, with significant effects observed as early as 6 h. OG formulation at 800 ppm showed higher activity than OG formulation at 80 ppm, and the amount of melanin was decreased by about 40% on Day 14 of the mixing reaction. Differentiation marker studies using human keratinocytes showed that the gene expression of involucrin and serine palmitoyltransferase was upregulated by OG, which was almost equivalent concentration to OG formulation 80 ppm, suggesting that OGs can enhance turnover of the skin epidermis. In clinical study, OG formulations 80 and 800 ppm showed larger decreases in melanin contents at 8 weeks compared with those at 4 weeks and their mean values of △melanin index were −16.7 and −15.2, respectively. Statistically significant differences were detected against respective controls. Number of subjects with a decrease in melanin index from baseline to 4 or 8 weeks increased in both OG formulations 80 and 800 ppm, especially prominent at 8 weeks. There were no adverse events related to treatments of OG 80 and 800 ppm during the study.ConclusionThe result indicated that applications of OG formulations are safe and effective in lightening age spots on the facial skin.

Screening of Plant-Derived Natural Extracts to Identify a Candidate Extract Capable of Enhancing Lipid Synthesis in Keratinocytes.

BackgroundReduced lipid content in the stratum corneum is a major cause of skin-barrier dysfunction in various pathological conditions. Promoting lipid production is a potential strategy to improve skin-barrier function. Recent evidence supports the beneficial effects of adiponectin on lipid metabolism and senescence in keratinocytes.ObjectiveThis study aimed to investigate whether plant extracts can enhance skin-barrier function.MethodsWe screened fruit and herb extracts that enhance the lipid synthesis of keratinocytes via AMP-activated protein kinase (AMPK) activation and SIRT1 signaling in the adiponectin pathway. The levels of major lipid synthesis enzymes and transcription factors as well as epidermal barrier lipids involved in adiponectin-associated epidermal barrier formation were evaluated in the herbal extracts- or adiponectin-treated human epidermal keratinocyte and equivalent models. The mRNA expression of major lipid synthesis enzymes increased following treatment with Lycii Fructus, Prunus tomentosa, and Melia toosendan extracts.ResultsThe expression of transcription factors SIRT1, liver X receptor α, peroxisome proliferator-activated receptors (PPARs), and sterol regulatory element-binding proteins (SREBPs) were upregulated. Levels of free fatty acids, cholesterol, and ceramides were elevated. The expression of keratinocyte differentiation markers increased. In particular, among fruit extracts with a detectable effect, Melia toosendan induced the highest expression of lipid synthase.ConclusionThese results indicate that Melia toosendan is a promising candidate for improving skin-barrier function.

Effects of Eggshell Membrane on Keratinocyte Differentiation and Skin Aging In Vitro and In Vivo.

Skin aging is one of the hallmarks of the aging process that causes physiological and morphological changes. Recently, several nutritional studies were conducted to delay or suppress the aging process. This study investigated whether nutritional supplementation of the eggshell membrane (ESM) has a beneficial effect on maintaining skin health and improving the skin aging process in vitro using neonatal normal human epidermal keratinocytes (NHEK-Neo) and in vivo using interleukin-10 knockout (IL-10 KO) mice. In NHEK-Neo cells, 1 mg/mL of enzymatically hydrolyzed ESM (eESM) upregulated the expression of keratinocyte differentiation markers, including keratin 1, filaggrin and involucrin, and changed the keratinocyte morphology. In IL-10 KO mice, oral supplementation of 8% powdered-ESM (pESM) upregulated the expression of growth factors, including transforming growth factor β1, platelet-derived growth factor-β and connective tissue growth factor, and suppressed skin thinning. Furthermore, voltage-gated calcium channel, transient receptor potential cation channel subfamily V members were upregulated by eESM treatment in NHEK-Neo cells and pESM supplementation in IL-10 KO mice. Collectively, these data suggest that ESM has an important role in improving skin health and aging, possibly via upregulating calcium signaling.

Three Constituents of Moringa oleifera Seeds Regulate Expression of Th17-Relevant Cytokines and Ameliorate TPA-Induced Psoriasis-Like Skin Lesions in Mice.

As a folk medicine, Moringa oleifera L. is used effectively to treat inflammatory conditions and skin diseases. However, its mechanism of action is not well understood, limiting its medical use. We isolated and identified three compounds, namely niazirin, marumoside A and sitosterol-3-O-β-d-glucoside, from the seeds of Moringa oleifera, and studied their effects on the expression of Th17-relevant cytokines (IL-12/IL-23 p40, IL-17A, IL-22 and IL-23 p19) using lipopolysaccharide-stimulated THP-1 cells. Additionally, as Th17 plays a critical role in the pathogenesis of psoriasis, we used a 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced psoriasis-like skin lesion mouse model to study their potential therapeutic application in vivo. The compounds suppressed the expression of IL-12/IL-23 p40, IL-17A, IL-22 and IL-23 p19 in vitro, and in vivo they ameliorated psoriasis-like skin lesions, decreased IL-17A mRNA expression, and increased the expression of keratinocyte differentiation markers. To our knowledge, this is the first report regarding the mechanism and therapeutic application of Moringa oleifera seeds to treat psoriasis-like lesions in vivo.

673 11β-hydroxysteroid dehydrogenase type 1 activation induced by UVB might be a possible mechanism of skin barrier dysfunction due to UV exposure

Ultraviolet light (UV) radiation to the skin causes dose- and wavelength- dependent reactions, including skin barrier dysfunction. Long-term exposure to even low dose UV induces the alteration of skin barrier presenting prominent ceramide decrease in the stratum corneum (SC) intercellular lipids. 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), which converts inactive cortisone to active cortisol in peripheral tissues and inhibits keratinocytes and fibroblasts proliferation, is known to be induced by UVB. We performed in vitro, in vivo, ex-vivo studies to elucidate whether skin barrier dysfunction induced by UV could be resulted from 11β-HSD1 activation after UV irradiation. We observed that 11β-HSD1 expression was increased by cortisol treatment itself and UV irradiation, thereby rapidly converting cortisone into cortisol. UVB irradiation increases 11β-HSD1 expression as well as inflammatory cytokines using HSD11B1 siRNA transfected normal human epidermal keratinocytes. 11β-HSD1 mRNA was prominently higher in UVB irradiated primary human keratinocytes compared with control. Keratinocytes transfected with HSD11B1 siRNA decreased the expression of 11β-HSD1 mRNA and did not increase cortisol even when the keratinocytes were irradiated by UVB. In vitro, increased cortisol converted by 11β-HSD1 inhibits keratinocyte differentiation. Cortisone decreased the mRNA and protein expression of keratinocyte differentiation markers in UVB-exposed keratinocytes. 11β-HSD1 expression remarkably increased in UV exposed skin and intrinsic aged skin. Skin barrier function presented by transpidermal water loss, SC hydration and SC integrity was impaired in long term UV exposed skin and intrinsic aged skin. Therefore, 11β-HSD1 activation by UVB might suggest another possible mechanism on skin barrier dysfunction due to UV exposure.

Sophora japonica extracts accelerates keratinocyte differentiation through miR-181a

BackgroundThe Sophora japonica extracts contain flavonol triglycoside, isoflavonol, coumarone chromone, saponin, triterpene glucoside, phospholipids, alkaloids, amino acids, polysaccharides, and fatty acids. These components have physiological effects such as anti-infertility and anti-cancer activities. This study investigated the regulation of keratinocyte differentiation upon treatment with the S. japonica extracts in keratinocyte and the molecular cell biological mechanism involved.MethodsTo determine whether the S. japonica extracts or troxerutin, which is its main component, regulates keratinocyte differentiation, quantitative real-time polymerase chain reaction (qRT-PCR) was performed on keratinocyte differentiation markers such as keratin 1 (K1), keratin 10 (K10), involucrin, and filaggrin after treatment with the S. japonica extracts. miR-181a knockdown confirmed that keratinocyte differentiation was regulated by increased miR-181a expression upon treatment with the S. japonica extracts or troxerutin.ResultsThe expression of keratinocyte differentiation markers such as K1, K10, involucrin, and filaggrin increased upon treatment with the S. japonica extracts and troxerutin. Furthermore, miR-181a expression, which is known to increase during keratinocyte differentiation, increased upon treatment with the S. japonica extracts and troxerutin. When miR-181a was knocked down, the increased expression of keratinocyte differentiation markers upon treatment with the S. japonica extracts and troxerutin decreased again. Finally, it was confirmed that miR-181a directly regulated and reduced the expression of Notch2, which reduces keratinocyte differentiation, and that the decrease in Notch2 expression by miR-181a regulated keratinocyte differentiation.ConclusionsThese results suggest that the S. japonica extracts or troxerutin accelerates keratinocyte differentiation through miR-181a. This accelerated keratinocyte differentiation was confirmed to have resulted from the regulation of Notch2 expression by miR-181a. The results of this study provide an opportunity to confirm the molecular cell biological mechanism of S. japonica extracts or troxerutin on skin keratinization, and we expected that this study contribute to develop a moisturizing cosmetic material that can strengthen the skin barrier through regulating keratinocyte differentiation.

Physiological Doses of Red Light Induce IL-4 Release in Cocultures between Human Keratinocytes and Immune Cells.

Phototherapy is routinely used for the treatment of various skin conditions and targeted therapy of superficial cancers. However, the molecular mechanisms behind their biological effects and the need for efficacy enhancing photosensitizers are not well addressed. Particularly, not much is known about the inherent effect of light from the visible spectrum on cytokine release and its downstream effects in keratinocytes and immune cells located in skin and therefore exposed to light. To address this, we delivered calibrated doses of well-defined light qualities (380 to 660nm) to cocultures of human keratinocytes and macrophage/dendritic cells in the absence or presence of the commonly used photosensitizer 8-methoxypsoralen (8-MOP). The experiments identified IL-4 as a key effector cytokine released by this coculture model with need for 8-MOP in the UVA1 /blue (380nm) and no requirement for photosensitizer in the red light spectrum (627nm). 3D organotypic skin cultures treated with IL-4 showed thickening of the epidermal layer and delayed differentiation. However unlike IL-4 and UVA1 /blue light treatment, red light did not reduce the expression of keratinocyte differentiation markers or increase signs of photo-oxidative damage. This supports the application of isolated red light as a possible alternative for photo-immunotherapy without need for additional photosensitizers.

Kinetin Improves Barrier Function of the Skin by Modulating Keratinocyte Differentiation Markers.

BackgroundKinetin is a plant hormone that regulates growth and differentiation. Keratinocytes, the basic building blocks of the epidermis, function in maintaining the skin barrier.ObjectiveWe examined whether kinetin induces skin barrier functions in vitro and in vivo.MethodsTo evaluate the efficacy of kinetin at the cellular level, expression of keratinocyte differentiation markers was assessed. Moreover, we examined the clinical efficacy of kinetin by evaluating skin moisture, transepidermal water loss (TEWL), and skin surface roughness in patients who used kinetin-containing cream. We performed quantitative real-time polymerase chain reaction to measure the expression of keratinocyte differentiation markers in HaCaT cells following treatment. A clinical trial was performed to assess skin moisture, TEWL, and evenness of skin texture in subjects who used kinetin-containing cream for 4 weeks.ResultsKinetin increased involucrin, and keratin 1 mRNA in HaCaT cells. Moreover, use of a kinetin-containing cream improved skin moisture and TEWL while decreasing roughness of skin texture.ConclusionKinetin induced the expression of keratinocyte differentiation markers, suggesting that it may affect differentiation to improve skin moisture content, TEWL, and other signs of skin aging. Therefore, kinetin is a potential new component for use in cosmetics as an anti-aging agent that improves the barrier function of skin.

MicroRNA-331-3p Suppresses Cervical Cancer Cell Proliferation and E6/E7 Expression by Targeting NRP2.

Aberrant expression of microRNAs (miRNAs) is involved in the development and progression of various types of cancers. In this study, we investigated the role of miR-331-3p in cell proliferation and the expression of keratinocyte differentiation markers of uterine cervical cancer cells. Moreover, we evaluated whether neuropilin 2 (NRP2) are putative target molecules that regulate the human papillomavirus (HPV) related oncoproteins E6 and E7. Cell proliferation in the human cervical cancer cell lines SKG-II, HCS-2, and HeLa was assessed using the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) assay. Cellular apoptosis was measured using the TdT-mediated dUTP nick end labeling (TUNEL) and Annexin V assays. Quantitative RT-PCR was used to measure the messenger RNA (mRNA) expression of the NRP2, E6, E7, p63, and involucrin (IVL) genes. A functional assay for cell growth was performed using cell cycle analyses. Overexpression of miR-331-3p inhibited cell proliferation, and induced G2/M phase arrest and apoptosis in SKG-II, HCS-2 and HeLa cells. The luciferase reporter assay of the NRP2 3′-untranslated region revealed the direct regulation of NRP2 by miR-331-3p. Gene expression analyses using quantitative RT-PCR in SKG-II, HCS-2, and HeLa cells overexpressing miR-331-3p or suppressing NRP2 revealed down-regulation of E6, E7, and p63 mRNA and up-regulation of IVL mRNA. Moreover, miR-331-3p overexpression was suppressed NRP2 expression in protein level. We showed that miR-331-3p and NRP2 were key effectors of cell proliferation by regulating the cell cycle, apoptosis. NRP-2 also regulates the expression of E6/E7 and keratinocyte differentiation markers. Our findings suggest that miR-331-3p has an important role in regulating cervical cancer cell proliferation, and that miR-331-3p may contribute to keratinocyte differentiation through NRP2 suppression. miR-331-3p and NRP2 may contribute to anti-cancer effects.

Hypoxia-mediated activation of autophagic flux inhibits apoptosis of keratinocytes via blocking tumor necrosis factor-related apoptosis-inducing ligand

Tumor necrosis factor‑related apoptosis‑inducing ligand (TRAIL) is toxic against transformed tumor cells. Cornification is the terminal differentiation of keratinocytes and a specific form of programmed cell death caused by TRAIL that occurs in keratinocytes. Apoptosis can also be triggered when TRAIL induces expression of keratinocyte differentiation markers. The present study reported that hypoxia inhibits TRAIL‑induced apoptosis due to autophagic flux. It is well known that hypoxia activates autophagy in keratinocytes and reduces p62 protein levels. The present study demonstrated that hypoxia inhibited TRAIL‑mediated apoptosis and induced autophagic flux in HaCaT cells. In addition, autophagic flux‑inactivating reagents, including 3‑methyladenine and chloroquine, increased the TRAIL sensitivity of HaCaT cells exposed to hypoxia. In conclusion, these results indicated that inactivating autophagy increased TRAIL sensitivity in hypoxic HaCaT cells. Autophagy inhibitors may be beneficial in therapies using TRAIL against skin cancers.

The antimicrobial protein S100A7/psoriasin enhances the expression of keratinocyte differentiation markers and strengthens the skin's tight junction barrier.

S100A7/psoriasin is a member of the S100 protein family and is encoded in the epidermal differentiation complex, which contains genes for markers of epidermal differentiation. S100A7/psoriasin is overexpressed in hyperproliferative skin diseases, where it is believed not only to exhibit antimicrobial functions, but also to induce immunomodulatory activities, including chemotaxis and cytokine/chemokine production. To evaluate the effect of S100A7/psoriasin on keratinocyte differentiation and regulation of the tight junction (TJ) barrier. Expression of differentiation markers and TJ proteins in human keratinocytes was determined by real-time polymerase chain reaction and Western blot. The changes in TJ barrier function were assessed by transepithelial electrical resistance and paracellular permeability assays. Glycogen synthase kinase-3 (GSK-3) and mitogen-activated protein kinase (MAPK) activation was analysed by Western blot, whereas β-catenin and E-cadherin activation was evaluated by Western blot and immunofluorescence. S100A7/psoriasin enhanced the expression of several differentiation markers and selectively increased the expression of TJ proteins (e.g. claudins and occludin), which are known to strengthen the TJ barrier. Furthermore, S100A7/psoriasin increased β-catenin and E-cadherin accumulation at cell-cell contact, and enhanced transepithelial electrical resistance while reducing the paracellular permeability of keratinocyte layers. The data suggest that S100A7/psoriasin-mediated regulation of the TJ barrier was via both the GSK-3 and MAPK pathways, as evidenced by the inhibitory effects of inhibitors for GSK-3 and MAPKs. Our finding that S100A7/psoriasin regulates differentiation and strengthens TJ barrier function provides novel evidence that, in addition to antimicrobial and immunoregulatory activities, S100A7/psoriasin is involved in skin innate immunity.

The Expression of Involucrin, Loricrin, and Filaggrin in Cultured Sebocytes

Dear Editor: It is well established that a complex interplay of corneocytes and intercellular lipids in the stratum corneum of the skin is responsible for the skin barrier against environmental factors. A cornified cell envelope, which is composed of involucrin, loricrin, filaggrin, and other proteins, is a component of fully differentiated epidermal keratinocytes and corneocytes, and it is important in the skin barrier1. Although sebaceous gland sebocytes are considered to originate from the same stem cells as epidermal keratinocyte, it is not clear whether the keratinocyte differentiation markers are expressed in the sebocytes or not2. Because the transfollicular route has been known as a major route for drug delivery, more information is required to investigate the expression of the markers in the sebaceous gland sebocytes. A primary culture of human scalp sebocytes was performed with Dulbecco's modified Eagle's medium (DMEM; Gibco BRL, Grand Island, NY, USA) and Epilife (MEPI500CA; Gibco BRL) according to a method described previously3. Sebocytes were cultured at various concentrations of calcium (0.25, 0.5, 1, and 1.2 mM), or treated with vitamin D (10-10, 10-9, 10-8, 10-7, and 10-6 M). Reverse transcription polymerase chain reaction (RT-PCR) for involucrin, loricrin, and filaggrin was conducted in triplicate using the first strand cDNA synthesis kit (Promega, Madison, WI, USA) and oligonucleotide primers (Genotech, Daejeon, Korea). RT-PCR amplification was conducted using the GoTaq Flexi DNA Polymerase: involucrin for 34 cycles at 59℃, loricrin 34 cycles at 69℃, and filaggrin for 30 cycles at 58℃. Immunocytofluorescence for involucrin, loricrin, and filaggrin (Sigma-Aldrich, St. Louis, MO, USA) was also performed on cultured sebocytes. In this study, it was revealed that the expression of involucrin, loricrin, and filaggrin in cultured sebocytes was very weak (Fig. 1, ​,2).2). In addition, their expression in cultured sebocytes was not changed according to calcium concentration or after treatment with vitamin D (Fig. 2). Fig. 1 The expression of involucrin (A), loricrin (B), and filaggrin (C) was very weak in the cytoplasm of cultured sebocytes in immunocytofluorescence. (D) Control (A~D: ×200). Fig. 2 Gene expression of involucrin (A), loricrin (B), and filaggrin (C) in cultured sebocytes after treatment with calcium and VitD (vitamin D), respectively. Cont: control. Sebocytes are highly specialized, lipid-producing epithelial cells that release their contents by a rupture of the cell membrane and cellular degradation during differentiation4. Keratinocyte differentiating markers, including involucrin, loricrin, and filaggrin, provide structural support to the cell. Although sebocytes originate from the same stem cells as keratinocytes, it is thought that there are many differences in the expression of keratinocyte differentiating markers in sebocytes. In addition, it is recognized by our previous study (not published) that sebaceous gland sebocytes in vivo, both basal proliferating cells and central differentiating cells, show little expression of involucrin, loricrin, and filaggrin. Doran et al.5 reported that sebocytes did not produce cornified envelopes in vitro and could only be induced to produce small quantities (less than 5%) of envelopes with a calcium ionophore. However, Lo Celso et al.6 observed the presence of cornifin and involucrin positive immortalized sebocytes. This study showed very weak expression of involucrin, loricrin, and filaggrin in the cytoplasm of cultured sebocytes. Like cultured epidermal keratinocytes, proliferation and differentiation of cultured sebocytes are influenced by extracellular calcium concentration. Vitamin D also induces time- and dose-dependent modulation of cell proliferation and lipid content in cultured sebocytes through binding to vitamin D receptors. Nevertheless, this study showed that both extracellular calcium concentration and treatment with vitamin D did not affect the expression of involucrin, loricrin, and filaggrin in cultured sebocytes. In conclusion, cultured sebocytes showed little expression of keratinocyte differentiation markers. Weak physical barrier in the sebaceous gland may cause much better transfollicular drug delivery.

Obligatory roles of filamin A in E-cadherin-mediated cell–cell adhesion in epidermal keratinocytes

BackgroundExtracellular Ca2+ (Cao2+)-induced E-cadherin-mediated cell–cell adhesion plays a critical role in promoting differentiation in epidermal keratinocytes. Our previous studies show that the calcium-sensing receptor (CaR) regulates keratinocyte cell–cell adhesion and differentiation via Rho A-mediated signaling. CaR forms a protein complex with Rho A, guanine nucleotide exchange factor Trio, and a cytoskeletal actin-binding protein, filamin A, at the cell–cell junctions in response to elevated Cao2+ levels. Filamin A has the ability to interact directly with CaR, Trio, and Rho and mediate CaR-dependent signaling events. ObjectiveThis study was conducted to investigate the roles of filamin A and Trio in regulating Cao2+-induced Rho activation and intercellular adhesion. MethodsExpression of filamin A and Trio in keratinocytes was inhibited by siRNA. Its effects on Cao2+-dependent junction formation and adhesion complex formation were evaluated by fluorescence immunostaining and immunoprecipitation. Endogenous Rho activity and expression of keratinocyte differentiation markers were also examined. The significance of the physical interactions of filamin A with Trio and Rho was assessed in dominant-negative inhibition studies. ResultsInhibiting filamin A expression blocked the formation of CaR-Rho A-Trio-E-cadherin protein complex. Knockdown of filamin A or Trio inhibited Cao2+-induced membrane localization and activation of Rho A, formation of the E-cadherin–catenin adhesion complex, and keratinocyte terminal differentiation. Expressing dominant-negative peptides disruptive to the endogenous filamin–Trio, filamin–Rho, and CaR–filamin interactions suppressed the formation of adherens junctions. ConclusionThrough physical interactions with CaR, Trio and Rho, filamin A generates a scaffold for organizing a signaling complex that promotes E-cadherin-mediated cell–cell adhesion and keratinocyte differentiation.

The atypical retinoid E-3-(3’-Adamantan-1-yl-4’-methoxybiphenyl-4-yl)-2-propenoic acid (ST1898) displays comedolytic activity in the rhino mouse model

Retinoids represent the first-line therapy for the treatment of acne vulgaris. Their effect is comedolytic and anti-comedogenic, and associates with hyperplasia and deregulated differentiation of the epidermis, and decreased inflammation. We here tested the comedolytic effect of the novel atypical retinoid E-3-(3'-Adamantan-1-yl-4'-methoxybiphenyl-4-yl)-2-propenoic acid (ST1898) in the rhino mouse, as a model of comedogenic acne, and compared this effect to that of adapalene (Differin® gel), as reference compound. Topical administration of 0.1% ST1898 for three weeks exerted a comedolytic effect comparable to that of adapalene 0.1%. In ST1898-treated mice, epidermal hyperplasia was significantly reduced and the expression of keratinocyte differentiation markers was less perturbed compared to adapalene-treated animals. Moreover, keratin 6, which stains activated keratinocytes, was strongly and uniformly induced in interfollicular epidermis of adapalene-treated mice, while only faintly and focally expressed in ST1898-treated ones. Our data indicate that ST1898 has strong comedolytic activity but modest topical side effects.