Keratinocyte Production Research Articles

Activation of matrix metalloproteinases and FoxO3a in HaCaT keratinocytes by radiofrequency electromagnetic field exposure

As the skin is the largest body organ and critically serves as a barrier, it is frequently exposed and could be physiologically affected by radiofrequency electromagnetic field (RF-EMF) exposure. In this study, we found that 1760 MHz RF-EMF (4.0 W/kg specific absorption rate for 2 h/day during 4 days) exposure could induce intracellular reactive oxygen species (ROS) production in HaCaT human keratinocytes using 2′,7′-dichlorofluorescin diacetate fluorescent probe analysis. However, cell growth and viability were unaffected by RF-EMF exposure. Since oxidative stress in the skin greatly influences the skin-aging process, we analyzed the skin senescence-related factors activated by ROS generation. Matrix metalloproteinases 1, 3, and 7 (MMP1, MMP3, and MMP7), the main skin wrinkle-related proteins, were significantly increased in HaCaT cells after RF-EMF exposure. Additionally, the gelatinolytic activities of secreted MMP2 and MMP9 were also increased by RF-EMF exposure. FoxO3a (Ser318/321) and ERK1/2 (Thr 202/Tyr 204) phosphorylation levels were significantly increased by RF-EMF exposure. However, Bcl2 and Bax expression levels were not significantly changed, indicating that the apoptotic pathway was not activated in keratinocytes following RF-EMF exposure. In summary, our findings show that exposure to 1760 MHz RF-EMF induces ROS generation, leading to MMP activation and FoxO3a and ERK1/2 phosphorylation. These data suggest that RF-EMF exposure induces cellular senescence of skin cells through ROS induction in HaCaT human keratinocytes.

Indirubin attenuates IL-17A-induced CCL20 expression and production in keratinocytes through repressing TAK1 signaling pathway

Psoriatic skin inflammation is mainly driven by complex interactions of infiltrating immune cells and activated keratinocytes. Keratinocytes play an active role in initiating and maintenance of psoriatic skin inflammation by secreting chemokines and cytokines. IL-17A produced by T cells potently upregulates the production of chemokine CCL20 in the keratinocytes, which further chemoattracts IL-17A-producing CCR6+ immune cells to the site of inflammation. Indirubin, an active constituent of indigo naturalis, has been reported to possess anti-inflammatory activities, but whether it can suppress the production of chemokines in keratinocytes is largely unknown. To address this question, IL-17A stimulated HaCaT cells were used as cell model to explore the effects of indirubin on the expression and secretion of chemokines. Also, RNA-seq analysis was performed to extensively understand the entire gene expression changes after indirubin treatment and identify the differentially expressed genes further. Indirubin treatment strongly inhibited CCL20 expression and secretion in IL-17A stimulated HaCaT cells. The inhibitory action of indirubin on CCL20 expression was mainly mediated by TAK1 signaling pathway in a mouse psoriasis-like model and cultured HaCaT cells in vitro. Combining with our previous report, indirubin ameliorated psoriasiform dermatitis by breaking CCL20/CCR6 axis-mediated inflammatory loops. Our results provide novel insights into the mechanisms of indirubin in the treatment of psoriasis.

Suppression of IL-17A-induced CCL20 production by cytokine inducible SH2-containing protein 1 in epidermal keratinocytes

BackgroundLesions of atopic dermatitis have fewer Th17 cells than those of psoriasis, resulting in frequent skin infections. Expression of CCL20, a chemokine that is important for recruiting Th17 cells, is suppressed in the lesions of atopic dermatitis. We previously reported that IL-4 induces the expression of cytokine-inducible SH2-containing protein 1 (CIS1), a member of the CIS/SOCS family, in epidermal keratinocytes. ObjectiveTo investigate whether CIS1 influences CCL20 production in epidermal keratinocytes. MethodsExpression of CIS1 was examined in atopic dermatitis skin and in cultured keratinocytes. The effects of overexpression of CIS1 on CCL20 production by IL-17A, and on signaling pathways inhibited by CIS1, were assessed in vitro. ResultsExpression of CIS1 was enhanced in the basal layer of the lesional epidermis of skin with atopic dermatitis. When CIS1 was expressed in keratinocytes using adenoviral vectors, IL-17A-induced CCL20 expression, but not HBD2 or S100A7 expression, was significantly suppressed. TNF-α/IL-1-induced CCL20 production was not altered by CIS1. Overexpression of CIS1 attenuated IL-17A-induced ERK phosphorylation. ERK phosphorylation was mediated by the Act1 and Src family kinase pathways. CIS1 overexpression suppressed Src phosphorylation. Among the Src family kinases, the Yes kinase may have an important role because knockdown of Yes in epidermal keratinocytes resulted in suppression of ERK phosphorylation and CCL20 mRNA expression by IL-17A. ConclusionCIS1 induced by Th2 cytokines has the ability to change the response of epidermal keratinocytes to IL-17A by suppression of Src family kinases.

Nootkatol prevents ultraviolet radiation-induced photoaging via ORAI1 and TRPV1 inhibition in melanocytes and keratinocytes.

Skin photoaging occurs due to chronic exposure to solar ultraviolet radiation (UV), the main factor contributing to extrinsic skin aging. Clinical signs of photoaging include the formation of deep, coarse skin wrinkles and hyperpigmentation. Although melanogenesis and skin wrinkling occur in different skin cells and have different underlying mechanisms, their initiation involves intracellular calcium signaling via calcium ion channels. The ORAI1 channel initiates melanogenesis in melanocytes, and the TRPV1 channel initiates MMP-1 production in keratinocytes in response to UV stimulation. We aimed to develop a drug that may simultaneously inhibit ORAI1 and TRPV1 activity to help prevent photoaging. We synthesized nootkatol, a chemical derivative of valencene. TRPV1 and ORAI1 activities were measured using the whole-cell patch-clamp technique. Intracellular calcium concentration [Ca2+]i was measured using calcium-sensitive fluorescent dye (Fura-2 AM). UV-induced melanin formation and MMP-1 production were quantified in B16F10 melanoma cells and HaCaT cells, respectively. Our results indicate that nootkatol (90 μM) reduced TRPV1 current by 94% ± 2% at –60 mV and ORAI1 current by 97% ± 1% at –120 mV. Intracellular calcium signaling was significantly inhibited by nootkatol in response to ORAI1 activation in human primary melanocytes (51.6% ± 0.98% at 100 μM). Additionally, UV-induced melanin synthesis was reduced by 76.38% ± 5.90% in B16F10 melanoma cells, and UV-induced MMP-1 production was reduced by 59.33% ± 1.49% in HaCaT cells. In conclusion, nootkatol inhibits both TRPV1 and ORAI1 to prevent photoaging, and targeting ion channels may be a promising strategy for preventing photoaging.

Rhus semialata M. extract ameliorate para-phenylenediamine-induced toxicity in keratinocytes.

para-Phenylediamine (PPD), a major component of hair dyeing ingredients, can induce allergenic sensitization and exert mutagenic, tumorigenic and cytotoxic effect. In this study, we determined the cytotoxic effect of PPD on human keratinocytes and evaluated the protective effect of Rhus semialata M. extracts (RSE) on PPD induced cytotoxicity for the first time. We observed that RSE is a strong inhibitory agent against PPD-induced toxicity in human keratinocytes. The results indicated that RSE pretreatment significantly could suppress PPD induced cytotoxic effects, including decrease of cell viability, accumulation in subG1 phase of cells, and relocation of phosphatidylserine on keratinocytes. Also, we found that PPD caused cytotoxicity was associated with mitochondrial membrane potential loss and subsequent activation of caspase and PARP degradation. However, pretreatment of RSE showed preventive activities against PPD induced mitochondrial membrane potential loss and ROS production in keratinocytes. In conclusion, the results of present study suggest that RSE was able to protect the skin from several cytotoxic effects of PPD and could be a meaningful material in many industries using PPD.

Effects of Hahella chejuensis-Derived Prodigiosin on UV-Induced ROS Production, Inflammation and Cytotoxicity in HaCaT Human Skin Keratinocytes.

Prodigiosins, which are natural tripyrrole red pigments and synthetic derivatives, reportedly have multiple biological effects mainly on various types of cancer cells. However, the effects of bacterial prodigiosin on non-cancerous HaCaT human skin keratinocytes have not been reported. Therefore, the present study aimed to investigate the functional activities of prodigiosin derived from cultures of the bacterium Hahella chejuensis in HaCaT cells. Cell viability, the cell proliferation rate, and reactive oxygen species (ROS) production in vitro were assayed following treatment of HaCaT cells with prodigiosin. Prodigiosin did not cause cytotoxicity and notably increased proliferation of HaCaT cells. Furthermore, prodigiosin reduced ultraviolet (UV) irradiation-induced ROS production and the inflammatory response in HaCaT cells. More importantly, prodigiosin reduced matrix metalloproteinase-9 expression and increased collagen synthesis in UV-irradiated HaCaT cells, demonstrating that it elicits anti-aging effects. In conclusion, our results reveal that H. chejuensis-derived prodigiosin is a potential natural product to develop functional cosmetic ingredients.

Serum level of interleukin-22 in patients with cutaneous warts: A case-control study.

Warts are viral cutaneous infections caused by human papilloma virus (HPV), presented by verrucous growth over the skin surface. The immune response is considered to play a crucial role in HPV clearance. It depends on intact cellular immunity including natural killer (NK) cell and cytotoxic T cells. It has been clarified that T-helper (Th) 1 cytokines (interleukin (IL)-2, interferon-γ, and tumor necrosis factor-a) and IL-17 are involved in HPV clearance. IL-22 is one of IL-10 family of cytokines produced by NK cells, Th1, Th17, and Th22 cells. In the skin, IL-22 reduces keratinocyte cornification and enhances keratinocyte production of antimicrobial peptides. IL-22 overexpression has been demonstrated in various viral infections and skin inflammatory disorders. The aim of this study was to assess serum levels of IL-22 in patients with warts and its association with their different clinical characteristics. The study included 20 patients with warts and 20 control subjects. Serum concentration of IL-22 was measured by enzyme-linked immune sorbent assay. Serum levels of IL-22 were significantly higher in patients with warts than in control subjects (P<.001). The levels were significantly higher in patients with recurrent warts after prior treatment than in patients with first-time warts (P=.007). Moreover, a significant positive correlation was detected between serum levels of IL-22 and the number of warts (P=.017). Serum level of IL-22 was elevated in patients with warts. Thus, IL-22 may have a crucial role in the antiviral immune response against this infection.

Honey and Chamomile Activate Keratinocyte Antioxidative Responses via the KEAP1/NRF2 System.

IntroductionThe stratum corneum protects against the entry of pathogens, allergens, and irritants while preventing dehydration. The Kelch-like erythroid cell-derived protein with cap-n-collar homology-associated protein 1 (KEAP1)/NF-E2-related factor 2 (NRF2) system maintains skin barrier homeostasis. Aggregated evidence suggests that NRF2-mediated antioxidative response is hardwired into the stratified squamous epithelia. Honey and chamomile have long been regarded as natural antioxidants. Nonetheless, it is still unclear whether they activate the KEAP1/NRF2 system in the epidermis and could promote epidermal barrier recovery.MethodsTo address the abovementioned issue, we explored the antioxidative property of honey/chamomile extract by using non-cell-based KEAP1-inhibition assay and cultured human epidermal keratinocytes.ResultsHerein we report that the extract inhibited KEAP1-NRF2 interaction and induced keratinocyte production of antioxidant small proline-rich protein.ConclusionOur results may offer an opportunity to develop cosmetic products that boost NRF2-mediated antioxidative/antiaging, epidermis-intrinsic bio-responses.

Altered expression of CCN1 in oral lichen planus associated with keratinocyte activation and IL-1β, ICAM1, and CCL5 up-regulation.

Emerging evidence indicates that CCN1 is a novel inflammation-regulated mediator involved in the pathogenesis of some immune-mediated inflammatory diseases. The objective of this study was to investigate the preliminary roles of CCN1 and its related cytokines IL-1β, CCL5, and ICAM1 in oral lichen planus (OLP). CCN1 expression levels in biopsies from OLP patients against normal oral mucosa (NOM) using immunohistochemistry (42 OLP vs 9 NOM) and RT-qPCR (20 OLP vs 20 NOM) were compared, respectively. The correlation of CCN1 and IL-1β, CCL5, and ICAM1 expression was examined by RT-qPCR in tissue samples and an in vitro cell culture system using keratinocyte HaCaT cells incubated with lipopolysaccharides. Immunohistochemistry showed that CCN1 protein mainly expressed in the cytoplasm of epithelial keratinocytes of OLP. Consistently, RT-qPCR revealed that mRNA expression of CCN1 was increased in OLP compared with NOM (P<.05) and positively correlated with the high expression of IL-1β, ICAM1, and CCL5 (P<.001), respectively. Importantly, an in vitro study showed that keratinocyte proliferation significantly (P<.05) increased by CCN1 stimulation. Moreover, IL-1β, ICAM1, and CCL5 expression in keratinocytes stimulated by CCN1 was increased (P<.05), respectively. This preliminary study for the first time reported that altered expression of CCN1 was associated with high expression of IL-1β, ICAM1, and CCL5 in OLP. And we demonstrated CCN1 promoted keratinocyte activation, as well as IL-1β, ICAM1, and CCL5 production in keratinocytes. Our data indicated that the potential role of CCN1 and its related cytokines was involved in the pathogenesis of OLP.

HPV11E7 inhibits IMQ-induced chemokine and colony-stimulating factor production in keratinocytes.

Imiquimod (IMQ) is approved as a first-line treatment for genital warts caused by human papillomavirus (HPV) infection. However, the recurrence rate is very high. HPV E7 protein plays a critical role in HPV immune escape. However, the role of HPV11 E7 protein in genital warts recurrence during IMQ treatment is not clear. Here, we found that the expression profile of NHEK cells was obviously changed after IMQ treatment, and a large number of genes encoding cytokines and genes involved in cytokine-mediated signaling pathways and cellular metabolic signaling pathways were up- or downregulated. HPV11E7 overexpression inhibited the IMQ-induced production of of multiple chemokines and colony-stimulating factors in NHEK cells. Furthermore, we found that HPV11E7 could impair the activation of mitogen-activated protein kinase (MAPK) signaling pathway. Therefore, our results suggested that HPV11 E7 diminishes the production of chemokines, colony-stimulating factors and other cytokines via inhibition of the MAPK signaling pathway, which suppresses the therapeutic effect of IMQ and promotes the recurrence of diseases, such as condyloma acuminatum.

Derivatives of 1,2,4-triazole imines acting as dual iNOS and tumor cell growth inhibitors

A set of 4-(R2-imino)-3-mercapto-5-(R1)-4H-1,2,4-triazoles derivatives were synthesized, characterized and evaluated for their ability to inhibit nitric oxide (NO) production in PAM212 mouse keratinocytes, which led to the discovery and the subsequent evaluation of their growth inhibitory cytotoxic potency toward that same mouse cell line together with a number of human cells lines (PC3, HT-29 and HeLa). Some limited SAR could be established for both NO production inhibition potency and growth inhibition cytotoxicity. Noticeably, the compounds designed to be nitrofurantoin mimics were the most potent anti-neoplastic agents.

Inhibition of thymic stromal lymphopoietin production to improve pruritus and quality of life in infants and children with atopic dermatitis

BackgroundAtopic dermatitis (AD) is an inflammatory pruritic chronic dermatosis involving the alarmin thymic stromal lymphopoietin (TSLP), which is directly implicated in AD pruritus.AimsTo evaluate the efficacy of Tambourissa trichophylla leaf extract (TTLE) titrated in polyphenols and 18β‐glycyrrhetinic acid (GA) in vitro and in vivo for AD pruritus.Patients/MethodsInitially, in vitro assessment of TSLP production in keratinocytes was undertaken. In normal human keratinocytes in vitro, TSLP was induced by polyinosinic:polycytidylic acid (Poly:IC), tumor necrosis factor (TNF)‐α, and interleukin (IL)‐4 and then quantified by ELISA in supernatants. Some cells were pretreated with TTLE and/or GA. Thereafter, an in vivo clinical study was performed including 48 infants and children with mild to severe AD flare‐ups, some of which were treated with topical corticosteroids. A topical spray containing TTLE and GA was applied. After 21 days of topical spray application, pruritus, sleeplessness, the SCORing Atopic Dermatitis (SCORAD) index, the Infant's Dermatitis Quality of Life index (IDQOL), and the Dermatitis Family Impact Questionnaire (DFIQ) were assessed.ResultsThymic stromal lymphopoietin secretion was inhibited significantly in an AD environment by TTLE and GA by up to 57.2% and 73.3%, respectively. The use of the topical spray induced a significant reduction in pruritus and sleeplessness scores, as well as the SCORAD, IDQOL, and DFIQ indexes in the total group. Similar results were observed in patient subgroups with or without topical corticosteroid treatment.ConclusionsA topical spray containing TTLE and GA, which inhibit TSLP secretion, efficiently decreases AD pruritus and improves the quality of life of AD patients.

131 The effect of PM 2.5 from three rural USA areas on inflammatory markers in human keratinocytes

Poor air quality in large cities has shown to have a negative effect on human health and to induce skin inflammation and premature aging. Less attention has been paid to rural environments, thus the effects on skin of specific rural pollutants are largely unknown. In addition, the combined effect of rural PM and solar radiation is also of interest. Here we investigate the effects of fine particulate matter (PM2.5) collected from rural environments on interleukin (IL) and matrix metalloprotease (MMP) production in human neonatal keratinocytes in the absence or presence of solar simulated UVR (ssUVR).

(-)-Loliolide Isolated from Sargassum horneri Protects against Fine Dust-Induced Oxidative Stress in Human Keratinocytes.

The emergence of fine dust (FD) among air pollutants has taken a toll during the past few decades, and it has provided both controversy and a platform for open conversation amongst world powers for finding sustainable solutions and effective treatments for health issues. The present study emphasizes the protective effects of (–)-loliolide (HTT) isolated from Sargassum horneri against FD-induced oxidative stress in human HaCaT keratinocytes. The purification of (–)-loliolide was carried out by centrifugal partition chromatography. HTT did not show any cytotoxicity, and it further illustrated the potential to increase cell viability by reducing the reactive oxygen species (ROS) production in FD-stimulated keratinocytes. Furthermore, HTT suppressed FD-stimulated DNA damage and the formation of apoptotic bodies, and it reduced the population of cells in the sub-G1 apoptosis phase. FD-induced apoptosis was advancing through the mitochondria-mediated apoptosis pathway. The cytoprotective effects of the HTT against FD-stimulated oxidative damage is mediated through squaring the nuclear factor E2-related factor 2 (Nrf2)-mediated heme oxygenase-1 (HO-1) pathway, dose-dependently increasing HO-1 and NAD(P)H dehydrogenase (quinone) 1 (NQO1) levels in the cytosol while concomitantly improving the nuclear translocation of Nrf2. Future studies could implement the protective functionality of HTT in producing pharmaceuticals that utilize natural products and benefit the diseased.

Syringaresinol Inhibits UVA-Induced MMP-1 Expression by Suppression of MAPK/AP-1 Signaling in HaCaT Keratinocytes and Human Dermal Fibroblasts.

Ultraviolet (UV) irradiation induces detrimental changes in human skin which result in photoaging. UV-induced intracellular changes cause degradation of extracellular matrix (ECM). UV-stimulated cleavage of collagen in ECM occurs via matrix metalloproteinases (MMPs). (±)-syringaresinol (SYR), a phytochemical which belongs to the lignan group of polyphenols, was investigated for its ability to reverse the UVA-induced changes in human HaCaT keratinocytes and dermal fibroblasts (HDFs) in vitro. Effect of SYR on UVA-induced changes was investigated by production and activation of MMPs and its transcriptional upstream effectors; mitogen-activated protein kinases (MAPKs) and pro-inflammatory mediators. Levels of expression were determined using ELISA, RT-PCR and immunoblotting. UVA irradiation stimulated the production of MMP-1 and inhibited collagen production. SYR treatment suppressed MMP-1 and enhanced collagen production in UVA-irradiated HaCaT keratinocytes and HDFs. SYR repressed the UV-induced phosphorylation of p38, ERK and JNK MAPKs in HaCaT keratinocytes while only suppressing JNK phosphorylation in HDFs. In addition, SYR was able to inhibit UVA-induced production of inflammatory cytokines; TNF-α, COX-2, IL-1β and IL-6. Moreover, SYR suppressed the activator protein-1 (AP-1), a heterodimer of phosphorylated transcription factors c-Jun and c-Fos. SYR-treatment decreased nuclear levels of activated c-Fos and c-Jun as a mechanism to inhibit UVA-induced transcriptional activities leading to MMP-1 production. In conclusion, current results demonstrated that SYR could inhibit UVA-induced upregulation of MMP-1 by suppressing MAPK/AP-1 signaling in HaCaT keratinocytes and HDFs. Therefore, SYR was suggested as a potential compound with antiphotoaging properties against UVA-induced skin aging.

Human Papillomavirus Quasivirus Production and Infection of Primary Human Keratinocytes.

This protocol describes the production of human papillomavirus (HPV)-derived quasiviruses. Quasiviruses are infectious particles that are produced in 293TT packaging cells and contain a complete viral genome. We describe methods for infection of primary human keratinocytes with HPV quasiviruses, as well as assays to measure early viral DNA replication and transcription. Published 2020. U.S. Government. Basic Protocol 1: Transfection, harvest, and isolation of HPV quasiviruses Alternate Protocol 1: Packaging HPV DNA replicated in 293TT cells Alternate Protocol 2: Production of higher-purity quasivirus using the "Ripcord" method Support Protocol 1: Production of HPV minicircles Support Protocol 2: Production of recircularized HPV genomes Support Protocol 3: Screening of fractions for viral proteins Support Protocol 4: Screening of fractions for viral DNA Support Protocol 5: Measuring viral titer Support Protocol 6: Quantitation of quasivirions Basic Protocol 2: Infection of primary human foreskin keratinocytes with quasivirus Basic Protocol 3: HPV quasivirus transcription assay Basic Protocol 4: HPV quasivirus replication assay.

Correction to "Pathogen-Associated Molecular Pattern-Induced TLR2 and TLR4 Activation Increases Keratinocyte Production of Inflammatory Mediators and Is Inhibited by Phosphatidylglycerol".

Correction to "Pathogen-Associated Molecular Pattern-Induced TLR2 and TLR4 Activation Increases Keratinocyte Production of Inflammatory Mediators and Is Inhibited by Phosphatidylglycerol".

Delayed application of silver nanoparticles reveals the role of early inflammation in burn wound healing

Burn injury is common, and antimicrobial agents are often applied immediately to prevent wound infection and excessive inflammatory response. Although inflammation is essential for clearing bacteria and creating an environment conducive to the healing process, it is unclear what time-frame inflammation should be present for optimal wound healing. This study critically investigated the role of early inflammation in burn wound healing, and also revealed the molecular mechanisms underlying the pro-healing effects of silver nanoparticles (AgNPs). We created a burn injury mouse model using wild-type and Smad3−/− mice, which were topically treated with AgNPs at different post-burn days, and examined the healing processes of the various groups. We also delineated the molecular pathways underlying the anti-inflammation and pro-healing effects of AgNPs by morphological and histological analysis, immuno-histochemistry, and western blotting. Our results showed that (1) AgNPs regulated pro-inflammatory cytokine IL-6 production of keratinocytes and neutrophils infiltration through KGF-2/p38 signaling pathway, (2) Topical AgNPs treatment immediately after burn injury significantly supressed early inflammation but resulted in delayed healing, (3) A short delay in AgNPs application (post-burn day 3 in our model) allowed early inflammation in a controlled manner, and led to optimal burn wound healing. Thus, our current study showed that some degree of early inflammation was beneficial, but prolonged inflammation was detrimental for burn wound healing. Further evaluation and clinical translation of this finding is warranted.

Enhanced Thermal Sensitivity of TRPV3 in Keratinocytes Underlies Heat-Induced Pruritogen Release and Pruritus in Atopic Dermatitis

Itch in atopic dermatitis (AD) is aggravated under warm conditions. Transient receptor potential vanilloid (TRPV) 3, a member of the thermosensitive transient receptor potential channels, is activated by innocuous heat and is abundantly expressed in keratinocytes. The potential role of TRPV3 in itch is illustrated in TRPV3 channelopathies of humans and mice. However, the role of TRPV3 in heat-induced itch in AD and the underlying mechanisms are unclear. Here we showed that keratinocytes isolated from patients with AD exhibit enhanced expression and heat sensitivity with hyperactive channel function of TRPV3. Heat stimulus induced enhanced secretion of thymic stromal lymphopoietin, nerve growth factor, and prostaglandin E2 by keratinocytes from patients with AD through TRPV3 activation. TRPV3 agonists increased thymic stromal lymphopoietin, nerve growth factor, prostaglandin E2, and IL-33 production in human keratinocytes and induced scratching behavior upon intradermal injection in mice. TRPV3 was upregulated in the skin of MC903-induced AD mouse model. Heat stimulation to MC903-treated mice increased scratching behavior and produced higher levels of thymic stromal lymphopoietin, nerve growth factor, prostaglandin E2, and IL-33 from the epidermis, which were attenuated by pharmacologic inhibition of TRPV3. Moreover, neutralization of thymic stromal lymphopoietin reduced heat-evoked scratching in MC903-challenged mice. These results suggest that TRPV3 is a potential therapeutic target for heat-induced itch in AD.

Potential toxic effects of 4-OH-chlorothalonil and photodegradation product on human skin health

Chlorothalonil (CHT) is widely used in agriculture as a fungicide and has been detected in various ecosystems along with its degradation products. A primary intermediate product of degradation, 4-hydroxychlorothalonil (4-OH-CHT) has demonstrated toxic effects on aquatic organisms. However, the toxic effects of 4-OH-CHT on human health and the impacts of environmental factors on the toxicity remain unclear. To understand the environmental modification on the toxicity of 4-OH-CHT to human health, we used a three-dimensional human skin culture model. 4-OH-CHT and irradiated 4-OH-CHT were applied to the model for the dermatoxicity analyses. Although neither the 4-OH-CHT nor the irradiated 4-OH-CHT inhibited the cell proliferation, the 4-OH-CHT significantly attenuated the keratinocyte migration by 26% at a concentration of 20 ppb and by 44 % at 100 ppb. The 4-OH-CHT also demonstrated inhibitory effects on keratinocyte differentiation at both 20 ppb and 100 ppb. In contrast, photodegraded 4-OH-CHT did not show inhibitory effects on the migration and differentiation of the keratinocytes at any concentration. Similarly, the 4-OH-CHT treated 3D keratinocyte culture dramatically activated the co-cultured dermal fibroblast cells by increasing the production of α smooth muscle actin (α-SMA) and pro-Collagen Iα. The mRNA levels of these two proteins were upregulated by 1.13 and 10.97 folds with the stimulation of 100 ppb 4-OH-CHT. The protein level of pro-Collagen Iα in dermal fibroblast cells was increased by 68 % with 100 ppb 4-OH-CHT. The photodegraded 4-OH-CHT failed to activate the co-cultured fibroblast cells. The 4-OH-CHT also enhanced pro-inflammatory cytokine production in keratinocytes compared to the photodegraded products. These results suggest that exposure to environmental 4-OH-CHT could increase the risk of inflammatory skin diseases in humans.