SKH-1 Hairless Mice Research Articles

Abstract 5266: Metabolic rewiring and epigenetic reprogramming by the environmental carcinogen benzo[a]pyrene in a two-stage skin carcinogenesis mouse model and cancer interception by triterpenoid ursolic acid

Abstract Nonmelanoma skin cancer (NMSC) is the most common skin cancer burden on the U.S. population. Environmental exposure to chemical carcinogens is one of the major causes of NMSC initiation, promotion, and progression. Ursolic acid (UA) is a naturally abundant pentacyclic triterpenoid showing anticancer potentials against diverse cancers. In the current study, we developed a two-stage skin carcinogenesis model in SKH1 hairless mice by administering cancer-initiating agent benzo[a]pyrene (B[a]P) and promoting agent 12-O-tetra-decanoylphorbol-13-acetate to study the epigenetic, transcriptomic, and metabolic changes at different stages (5, 20, and 26 weeks) during the development of NMSC, and investigated how UA regulates B[a]P-mediated alterations for NMSC interception. We found that UA protects against B[a]P-induced tumorigenesis at different phases of NMSC. Epigenetic CpG methyl-seq showed UA abrogated B[a]P-mediated alterations in differentially methylated regions (DMRs) profiles. Transcriptomic RNA-seq data exhibited UA reversed the differentially expressed genes (DEGs) of several inflammatory genes, such as chemokine ligand 8 (Ccl8) and interleukin 17F (Il17f), and epigenetic genes, such as DNA-methyltransferase 3-like (Dnmt3l) and protein-l-isoaspartate O-methyltransferase domain-containing protein 1 (Pcmtd1) during different stages of NMSC. Association study between DEGs and DMRs showed that B[a]P promoted transcription of kallikrein-related peptidase 13 (Klk13) by promoter demethylation, while UA suppressed Klk13 expression through hypermethylation in the promoter during the initiation stage, indicating the early intervention of UA. Ingenuity pathway analysis further showed significant upregulation of macrophage-stimulating protein-recepteur d'origine nantais (MSP-RON) signaling pathway by B[a]P during the initiation stage while suppressed by UA treatment. The metabolomic study revealed UA modulated cancer-associated changes in metabolisms, including the TCA cycle and pyruvate metabolism/metabolites during the promotion phase, indicating UA plays a critical role in regulating B[a]P-regulated metabolic changes and intercepting NMSC progression. In summary, UA protects against the environmental carcinogen B[a]P-driven epigenetic, transcriptomic, and metabolic changes during the initiation, promotion, and progression of NMSC, potentially contributing to the anticancer effects of UA. (Supported by NIH R01 CA200129 to A.N.K) Citation Format: Md. Shahid Sarwar, Christina N. Ramirez, Hsiao-Chen Dina Kuo, Pochung Chou, Renyi Wu, Davit Sargsyan, Ahmad Shannar, Rebecca Mary Peter, Ran Yin, Yujue Wang, Xiaoyang Su, Ah-Ng Kong. Metabolic rewiring and epigenetic reprogramming by the environmental carcinogen benzo[a]pyrene in a two-stage skin carcinogenesis mouse model and cancer interception by triterpenoid ursolic acid. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5266.

Nymphoides peltata Root Extracts Improve Atopic Dermatitis by Regulating Skin Inflammatory and Anti-Oxidative Enzymes in 2,4-Dinitrochlorobenzene (DNCB)-Induced SKH-1 Hairless Mice.

Nymphoides peltata is widely used pharmacologically in Traditional Chinese Medicine and Ayurvedic medicine as a diuretic, antipyretic, or choleretic and to treat ulcers, snakebites, and edema. Previous studies have shown that phytochemicals from N. peltata have physiological activities such as anti-inflammatory, anti-tumor, and anti-wrinkle properties. Nevertheless, research on the anti-atopic dermatitis (AD) effect of N. peltata extract is limited. This study was undertaken to assess the in vitro and in vivo anti-atopic and antioxidant activities of a 95% EtOH extract of N. peltata roots (NPR). PI-induced RBL-2H3 cells and two typical hapten mice (oxazolone-induced BALB/c mice and 2,4-dinitrochlorobenzene (DNCB)-induced SKH-1 hairless mice) were used to investigate the effect of NPR extract on AD. The expressions of AD-related inflammatory cytokines, skin-related genes, and antioxidant enzymes were analyzed by ELISA, immunoblotting, and immunofluorescence, and skin hydration was measured using Aquaflux AF103 and SKIN-O-MAT instruments. The chemical composition of NPR extract was analyzed using an HPLC-PDA system. In this study, NPR extracts were shown to most efficiently inhibit IL-4 in PI-induced RBL-2H3 cells and AD-like skin symptoms in oxazolone-BALB/c mice compared to its whole and aerial extracts. NPR extract markedly reduced DNCB-induced increases in mast cells, epidermal thickness, IL-4 and IgE expressions, and atopic-like symptoms in SKH-1 hairless mice. In addition, NPR extract suppressed DNCB-induced changes in the expressions of skin-related genes and skin hydration and activated the Nrf2/HO-1 pathway. Three phenolic acids (chlorogenic acid, 3,5-dicaffeoylquinic acid, and 3,4-dicaffeoylquinic acid) were identified by HPLC-PDA in NPR extract. The study shows that NPR extract exhibits anti-atopic activities by inhibiting inflammatory and oxidative stress and improving skin barrier functions, and indicates that NPR extract has potential therapeutic use for the prevention and treatment of AD.

Transfersome Encapsulated with the R-carvedilol Enantiomer for Skin Cancer Chemoprevention.

The R-carvedilol enantiomer, present in the racemic mixture of the chiral drug carvedilol, does not bind to the β-adrenergic receptors, but exhibits skin cancer preventive activity. For skin delivery, R-carvedilol-loaded transfersomes were prepared using various ratios of drug, lipids, and surfactants, and characterized for particle size, zeta potential, encapsulation efficiency, stability, and morphology. Transfersomes were compared for in vitro drug release and ex vivo skin penetration and retention. Skin irritation was evaluated by viability assay on murine epidermal cells and reconstructed human skin culture. Single-dose and repeated-dose dermal toxicity was determined in SKH-1 hairless mice. Efficacy was evaluated in SKH-1 mice exposed to single or multiple ultraviolet (UV) radiations. Transfersomes released the drug at a slower rate, but significantly increased skin drug permeation and retention compared with the free drug. The transfersome with a drug-lipid-surfactant ratio of 1:3:0.5 (T-RCAR-3) demonstrated the highest skin drug retention and was selected for further studies. T-RCAR-3 at 100 µM did not induce skin irritation in vitro and in vivo. Topical treatment with T-RCAR-3 at 10 µM effectively attenuated acute UV-induced skin inflammation and chronic UV-induced skin carcinogenesis. This study demonstrates feasibility of using R-carvedilol transfersome for preventing UV-induced skin inflammation and cancer.

Micronuclei analysis in mice peripheral blood exposed to polarized polychromatic noncoherent light (Bioptron® Light)

The increase in cancer in recent years suggests an inadvertent exposure to agents that cause genetic damage. The polarized polychromatic noncoherent light Bioptron® lamp is used to accelerate healing, among other therapeutic applications and its potential carcinogenic effects as a mitogenic agent have not been explored. The objective was to evaluate the genotoxicity of the Bioptron light therapy by means of the micronucleus assay in mouse erythrocytes. Male SKH1 hairless mice were randomly divided into six groups (5 mice/group); Group 1: negative control received ambient light; Group 2: positive control was exposed to ultraviolet light lamp A (UV-A) for 80 min; Experimental Groups 3–6 were exposed to the Bioptron lamp light for 10, 20, 40 and 80 min, respectively. Exposures in all groups were once a day for 4 days and blood smears were performed daily for 5 days and subsequently read with a microscope equipped with epifluorescence. The values of micronucleated erythrocytes (MNE), micronucleated polychromatic erythrocytes (MNPCE) and the proportion of polychromatic erythrocytes (PCE) were determined. The study group that received the UV-A light was the only one that increased MNE and MNPCE values, while in the groups exposed to the Bioptron lamp and the negative control did not show increases in any of the sampling days. In conclusion, under the conditions presented here, our results suggest that the light of the Bioptron lamp does not cause damage to the genetic material of SKH1 mice, by means of the micronucleus test in peripheral blood.

Orobol, 3′-hydroxy-genistein, suppresses the development and regrowth of cutaneous SCC

Chronic solar ultraviolet exposure is a major risk factor for cutaneous squamous cell carcinoma (cSCC), which is the second most common type of skin cancer. Our previous data showed that total protein and phosphorylation levels of T-LAK cell-originated protein kinase (TOPK) were enhanced in solar-simulated light (SSL)-induced skin carcinogenesis and overexpressed in actinic keratosis (AK) and cSCC human skin tissues compared to those in matched normal skin. Thus, targeting TOPK activity could be a helpful approach for treating cSCC. Our data showed that orobol directly binds to TOPK in an ATP-independent manner and inhibits TOPK kinase activity. Furthermore, orobol inhibited anchorage-independent colony formation by SCC12 cells in a dose-dependent manner. After discontinuing the treatment, patients commonly return to tumor-bearing conditions; therefore, therapy or intermittent dosing of drugs must be continued indefinitely. Thus, to examine the efficacy of orobol against the development and regrowth of cSCC, we established mouse models including prevention, and therapeutic models on the chronic SSL-irradiated SKH-1 hairless mice. Early treatment with orobol attenuates chronic SSL-induced cSCC development. Furthermore, orobol showed therapeutic efficacy after the formation of chronic SSL irradiation-induced tumor. In the mouse model with intermittent dosing of orobol, our data showed that re-application of orobol is effective for reducing tumor regrowth after discontinuation of treatment. Moreover, oncogenic protein levels were significantly attenuated by orobol treatment in the SSL-stimulated human skin. Thus, we suggest that orobol, as a promising TOPK inhibitor, could have an effective clinical approach to prevent and treat the development and regrowth of cSCC.

Anti-skin aging activity of eggshell membrane administration and its underlying mechanism

BackgroundThere is active research on developing materials for improving skin function. Eggshell membrane (ESM) is one such raw material that is consumed as a functional food to support skin health. However, studies on the mechanism of improvement of skin function on ingestion of ESM are still lacking.ObjectivesTo explore this mechanism of action, we conducted an ultraviolet (UV) irradiation study on a SKH-1 hairless mouse model. Feeding ESM was found to improve skin moisture and reduce wrinkles during 12 weeks of UVB irradiation.ResultsOral administration of ESM restored moisture in the dorsal skin tissue of mice. In addition, oral ingestion of ESM also reversed the increased transepidermal water loss and reduction of mRNA expression of hyaluronic synthases induced by UVB irradiation. Furthermore, UVB irradiation-induced collagen degradation was inhibited, and the expression of the collagenase MMP was reduced in the ESM intake group compared to the control. These results confirmed that oral ingestion of the ESM has an anti-wrinkle effect. In addition, the mRNA expression of the antioxidant enzyme SOD1, which was reduced on UVB irradiation, was restored on ingestion of the ESM. Restoring the expression of antioxidant enzymes is a key strategy for improving skin function of the ESM.ConclusionTaken together, the findings from our study reveal the potential of ESM as a nutricosmetic material with anti-wrinkle and skin moisturizing properties.

Nanodroplets for methicillin-resistant Staphylococcus aureus (MRSA) eradication in murine diabetic wounds

Bacterial biofilms are the leading cause of delayed healing in chronic wounds. Aminoglycoside antibiotics, such as gentamicin (Gent), are ineffective against biofilm cells as they maintain proton motive force below the threshold for drug uptake. We employ a novel aminoglycoside adjuvant, palmitoleic acid (PA), to facilitate drug uptake. Here, we propose a dual strategy to eradicate a chronic wound infection; utilizing ultrasound-stimulated nanodroplets (US+ND) to improve the penetration of the novel drug combination Gent/PA. A chronic wound infection model was established in SKH-1 hairless mice; 6–8 week old mice were treated with streptozocin to induce diabetes. A circular wound was created on the back of the mice and infected with methicillin-resistant Staphylococcus aureus (MRSA). Wounds were treated topically with Gent and/or PA, twice daily for four days. One daily antibiotic treatment was combined with US+ND. On day 5, mice were euthanized and the wound area was excised and plated to enumerate bacterial survivors. Neither Gent nor Gent/PA reduced bacterial burden but both treatments were significantly improved by applying US+ND to improve drug penetration. Importantly, bacteria were eradiated from 3 out of the 8 wounds in the Gent/PA group that were treated with US+ND. These data show that improving the penetration of a novel anti-biofilm drug combination is a viable strategy to eradicate biofilms in chronic wounds. [Some authors are inventors on patents related to this work.]

Protective Effects of Orange Sweet Pepper Juices Prepared by High-Speed Blender and Low-Speed Masticating Juicer against UVB-induced Skin Damage in SKH-1 Hairless Mice.

Sweet pepper fruits (Capsicum annuum L.) contain various nutrients and phytochemicals that enhance human health and prevent the pathogenesis of certain diseases. Here, we report that oral administration of orange sweet pepper juices prepared by a high-speed blender and low-speed masticating juicer reduces UVB-induced skin damage in SKH-1 hairless mice. Sweet pepper juices reduced UVB-induced skin photoaging by the regulation of genes involved in dermal matrix production and maintenance such as collagen type I α 1 and matrix metalloproteinase-2, 3, 9. Administration of sweet pepper juices also restored total collagen levels in UVB-exposed mice. In addition, sweet pepper juices downregulated the expression of pro-inflammatory proteins such as cyclooxygenase-2, interleukin (IL)-1β, IL-17, and IL-23, which was likely via inhibiting the NF-κB pathway. Moreover, primary antioxidant enzymes in the skin were enhanced by oral supplementation of sweet pepper juices, as evidenced by increased expression of catalase, glutathione peroxidase, and superoxide dismutase-2. Immunohistochemical staining showed that sweet pepper juices reduced UVB-induced DNA damage by preventing 8-OHdG formation. These results suggest that sweet pepper juices may offer a protective effect against photoaging by inhibiting the breakdown of dermal matrix, inflammatory response, and DNA damage as well as enhancing antioxidant defense, which leads to an overall reduction in skin damage.

Comprehensive analysis reveals potential hub genes and therapeutic drugs in an acquired lymphedema model.

BackgroundAcquired lymphedema is a common and often severe complication of breast cancer surgery and radiology that seriously affects patients’ quality of life. Nevertheless, the pathogenesis for acquired lymphedema is complex and remains unclear. The aim of this study is to find out possible genetic markers and potential drugs for acquired lymphedema.MethodsFirst, the GSE4333 datasets, which include expression data for six female humanized hairless immunocompetent SKH-1 mice (the condition of whom mimics acquired lymphedema), were reanalyzed. According to the criteria of a fold change (FC) ≥1.4 and an adjusted P value <0.05, we identified the differentially expressed genes (DEGs) between a normal group and the lymphedema group. Next, we analyzed the Gene Ontology (GO) terms and enriched signaling pathways associated with these DEGs with an online tool DAVID. We also constructed protein-protein interaction (PPI) networks and selected meaningful gene modules for additional gene-drug interaction research. Finally, the extant drugs targeting these module genes were identified for further study of their therapeutic effects against acquired lymphedema.ResultsA total of 481 DEGs were identified that were closely associated with the immune system, inflammatory response, and extracellular matrix (ECM) structural constituent terms, among others. Moreover, we identified the top 10 significant genes in the PPI networks and identified one extant drug, fiboflapon, that targets the ALOX5AP gene.ConclusionsWe ultimately identified 10 hub genes, molecular mechanisms, and one extant drug related to acquired lymphedema. The findings identified targets and a potential drug for further research on acquired lymphedema.

Lobelia chinensis Extract and Its Active Compound, Diosmetin, Improve Atopic Dermatitis by Reinforcing Skin Barrier Function through SPINK5/LEKTI Regulation.

The skin acts as a mechanical barrier that protects the body from the exterior environment, and skin barrier function is attributed to the stratum corneum (SC), which is composed of keratinocytes and skin lipids. Skin barrier homeostasis is maintained by a delicate balance between the differentiation and exfoliation of keratinocytes, and keratinocyte desquamation is regulated by members of the serine protease kalikrein (KLK) family and their endogenous inhibitor SPINK5/LEKTI (serine protease inhibitor Kazal type 5/lympho-epithelial Kazal-type-related inhibitor). Furthermore, SPINK5/LEKTI deficiency is involved in impaired skin barrier function caused by KLK over-activation. We sought to determine whether increased SPINK5/LEKTI expression ameliorates atopic dermatitis (AD) by strengthening skin barrier function using the ethanol extract of Lobelia chinensis (LCE) and its active compound, diosmetin, by treating human keratinocytes with UVB and using a DNCB-induced murine model of atopic dermatitis. LCE or diosmetin dose-dependently increased the transcriptional activation of SPINK5 promoter and prevented DNCB-induced skin barrier damage by modulating events downstream of SPINK5, that is, KLK, PAR2 (protease activated receptor 2), and TSLP (thymic stromal lymphopoietin). LCE or diosmetin normalized immune response in DNCB treated SKH-1 hairless mice as determined by reductions in serum immunoglobulin E and interleukin-4 levels and numbers of lesion-infiltrating mast cells. Our results suggest that LCE and diosmetin are good candidates for the treatment of skin barrier-disrupting diseases such as Netherton syndrome or AD, and that they do so by regulating SPINK5/LEKTI.

Effect of A. polygama APEE (Actinidia polygama ethanol extract) or APWE (Actinidia polygama water extract) on wrinkle formation in UVB-irradiated hairless mice.

Actinidia polygama (silver vine) is considered a medical plant which has been used in oriental medicine. It has been used for the treatment of pain, gout, rheumatoid arthritis, and inflammation. Few studies reported on the effect of Actinidia polygama (silver vine) on skin photoaging. To evaluate the anti-photoaging effect of the ethanol and water extracts of A.polygama (APEE and APWE, respectively) in UVB-irradiated hairless mice. SKH-1hairless mice were exposed to UVB irradiation (30-60mJ/cm2 ), following orally APEE or APWE oral administration for 10weeks. We examined the effect on winkle improvement by a measuring Fullscope, PRIMOS, Craniometer, and Cutometer. Furthermore, we analyzed histological changes in mouse dorsal skin through hematoxylin and eosin (H&E) and Masson's trichrome (MT) staining. The expression of matrix metalloproteinase (1, 3, and 9) was analyzed by immunoblotting. Oral administration of APEE or APWE at 100 or 200mg/kg in UVB-irradiated mice alleviated the symptoms of skin aging, such as wrinkling, epidermal hyperplasia, and water loss. In addition, the APEE or APWE oral administration increased skin elasticity by enhancing the production of type I collagen, elastin, and hyaluronic acid synthase and downregulating matrix metalloproteinase (1, 3, and 9) expression. Based on results for our study, APEE or APWE could protect the UVB-mediated skin wrinkle and is new target for the developing anti-wrinkle cosmetics.

7-O-Methylluteolin Suppresses the 2,4-Dinitrochlorobenzene-Induced Nrf2/HO-1 Pathway and Atopic Dermatitis-like Lesions.

7-O-methylluteolin (7-ML) is a flavonoid isolated from the aerial parts of Wikstroemia ganpi (W. ganpi). We describe the anti–atopic dermatitis (AD) effects of 7-ML in tert-butyl hydroperoxide (tBHP)-induced HepG2 cells and 2,4-dinitrochlorobenzene (DNCB)-induced SKH-1 hairless mice. Results demonstrated that 7-ML dose-dependently inhibited the activation of Nrf2 (nuclear factor-erythroid 2-related factor 2) in tBHP-induced HepG2 cells. 7-ML applied topically to our DNCB-induced mouse model upregulated the antioxidant protein expression (phosphorylated Nrf2 (pNrf2), Nrf2, and heme oxygenase-1 (HO-1)) in skin tissues, improved epidermal thickness, and reduced mast cell infiltration into the skin. In addition, 7-ML reduced the serum levels of immunoglobulin E (IgE) and interleukin-4 (IL-4) and improved skin barrier functions. These results suggest that 7-ML should be considered a novel antioxidant and anti-AD agent.

Photochemoprevention of ultraviolet Beam Radiation-induced DNA damage in keratinocytes by topical delivery of nanoformulated Epigallocatechin-3-gallate

Ultraviolet Beam (UVB) radiation is the main cause of skin cancer worldwide. Besides biocompatibility, the instability and limited skin permeability are the most challenging features of many effective photochemopreventive agents. (−)-Epigallocatechin-3-gallate (EGCG) is a natural polyphenolic compound extracted from Camellia sinensis that has been demonstrated to have antioxidant, anti-inflammatory, and anti-cancer properties. We evaluated the efficacy of three innovative EGCG nanoformulations in chemoprevention of UVB-induced DNA damage in keratinocytes. Results indicated that the EGCG nanoformulations reduced UVB-induced oxidative stress elevation and DNA damage. The nanoformulations also reduced the UVB-induced formation of pyrimidine and pyrimidone photoproducts in 2D human immortalized HaCaT keratinocytes and SKH-1 hairless mice through antioxidant effects and possibly through absorption of UVB radiation. In addition, EGCG nanoformulations inhibited UVB-induced chemokine/cytokine activation and promoted EGCG skin permeability and stability. Taken together, the results suggest the use of EGCG nanoformulations as potential natural chemopreventive agents during exposure to UVB radiation.

Ulvan/gelatin-based nanofibrous patches as a promising treatment for burn wounds

Burn wounds are among the most common skin injuries and, depending on the size and severity of the damage, they might be linked to considerable morbidity and mortality. Even though the healing process often takes place naturally, prolonged wound healing periods increase the risk for infections, often leading to chronic wounds. In order to prevent wound infection and improve the healing process, a number of wound dressings have been developed. Marine biopolymers, exhibiting high biocompatibility and biodegradability and lacking toxicity, have recently attracted considerable attention for the preparation of novel biomedical systems. In the present study, electrospun nanofibrous matrices composed of ulvan and marine gelatin in various combinations were designed, fabricated and characterized and their wound healing efficacy was evaluated on a second-degree burn model on the burn-inflamed skin of SKH-1 hairless mice. In addition, the potential synergistic effect of either hydrolyzed collagen or silver nanoparticles incorporated in ulvan-based nanofibers was assessed. Burn wound healing efficacy was evaluated by clinical assessment, histopathological analysis and measurement of parameters, including transepidermal water loss, hydration, skin thickness, wound area, texture and hemoglobin. The results of this study clearly show that patches composed of both ulvan and marine gelatin in appropriate ratio promote faster wound contraction during the early stages of the burn wound healing process, suppressing inflammation and achieving uniform wound closure, thus representing potentially efficient therapies for the treatment of burn wounds.

Role of hair follicles in the pathogenesis of arsenical-induced cutaneous damage.

Arsenical vesicants cause skin inflammation, blistering, and pain. The lack of appropriate animal models causes difficulty in defining their molecular pathogenesis. Here, Ptch1+/- /C57BL/6 mice were employed to investigate the pathobiology of the arsenicals lewisite and phenylarsine oxide (PAO). Following lewisite or PAO challenge (24h), the skin of animals becomes grayish-white, thick, leathery, and wrinkled with increased bi-fold thickness, Draize score, and necrotic patches. In histopathology, infiltrating leukocytes (macrophages and neutrophils), epidermal-dermal separation, edema, apoptotic cells, and disruption of tight and adherens junction proteins can be visualized. PCR arrays and nanoString analyses showed significant increases in cytokines/chemokines and other proinflammatory mediators. As hair follicles (HFs), which provide an immune-privileged environment, may affect immune cell trafficking and consequent inflammatory responses, we compared the pathogenesis of these chemicals in this model to that in Ptch1+/- /SKH-1 hairless mice. Ptch1+/- /SKH-1 mice have rudimentary, whereas Ptch1+/- /C57BL/6 mice have well-developed HFs. Although no significant differences were observed in qualitative inflammatory responses between the two strains, levels of cytokines/chemokines differed. Importantly, the mechanism of inflammation was identical; both reactive oxygen species induction and consequent activation of unfolded protein response signaling were similar. These data reveal that the acute molecular pathogenesis of arsenicals in these two murine models is similar.

No Evidence of Induced Skin Cancer or Other Skin Abnormalities after Long-Term (66 week) Chronic Exposure to 222-nm Far-UVC Radiation.

Far-UVC radiation, typically defined as 200-235 nm, has similar or greater anti-microbial efficacy compared with conventional 254-nm germicidal radiation. In addition, biophysical considerations of the interaction of far-UVC with tissue, as well as multiple short-term safety studies in animal models and humans, suggest that far-UVC exposure may be safe for skin and eye tissue. Nevertheless, the potential for skin cancer after chronic long-term exposure to far-UVC has not been studied. Here, we assessed far-UVC induced carcinogenic skin changes and other pathological dermal abnormalities in 96 SKH-1 hairless mice of both sexes that were exposed to average daily dorsal skin doses of 400, 130 or 55 mJ cm-2 of 222 nm far-UVC radiation for 66 weeks, 5 days per week, 8 h per day, as well as similarly-treated unexposed controls. No evidence for increased skin cancer, abnormal skin growths or incidental skin pathology findings was observed in the far-UVC-exposed mice. In addition, there were no significant changes in morbidity or mortality. The findings from this study support the long-term safety of long-term chronic exposure to far-UVC radiation, and therefore its potential suitability as a practical anti-microbial approach to reduce airborne viral and bacterial loads in occupied indoor settings.

Mechanism of Phosgene Oxime Induced Skin Toxicity in C57BL/6 Mouse Model

Phosgene Oxime (CX) is a potent chemical warfare agent. It is grouped with vesicants; however, its effect resembles of an urticant or nettle agent. CX has faster penetration compared to other vesicating chemical warfare agents and causes erythema, urticaria, blanching, itching hives, necrosis, and systemic toxic effects upon exposure. The mechanism of CX induced toxicity is not known and there are no approved therapies. We have shown that dermal CX exposure in SKH‐1 hairless mice causes clinical lesions, epidermal cell death, mast cell degranulation, infiltration of immune cells, and increase in the level of DNA damage and inflammatory markers. In this study we examined the mechanism of CX‐induced inflammatory response in C57BL/6 mice. Dorsal skin of mice was exposed to neat CX for 0.5 or 1.0 min using two 12 mm vapor caps at MRI Global. CX exposure caused decrease in heart rate and breath rate with significant mortality (50%) after 1.0 min CX exposure. CX exposure caused erythema, and edema at the exposure site and led to increase in epidermal thickness. Significant mast cell degranulation was observed within 2h of CX exposure in male and female mice at both the exposure durations. The increase in mast cell degranulation was associated with increased tryptase and chymase levels in the mouse skin. CX exposure also led to increased expression of inflammatory mediators, cyclooxygenase‐2 (COX‐2), matrix metallopeptidase‐9 (MMP‐9), myeloperoxidase (MPO), and MAP kinases JNK. Inflammatory cytokines and chemokines were analyzed in the skin tissue lysates using cytokine array. CX exposure caused increases in several pro‐inflammatory cytokines and chemokines including IL‐6 and TNF‐α, and a decrease in anti‐inflammatory cytokines IL‐4 and IL‐10. Together, these results suggest mast cells as important contributors of CX induced dermal inflammation and toxicity. Further studies are being carried out using WT (C57BL/6) and mast cell deficient mice to evaluate the role of mast cells in CX‐induced toxicity.

Snail mucin is a functional food ingredient for skin

• Exposure to UVB is a primary reason for skin aging, including wrinkle formation, skin dryness, and loss of elasticity. • Administration of snail mucin displayed anti-wrinkle activity by suppressing MMP-1/-13 expression with collagen restoration in mouse dorsal skin. • Skin hydration activity of snail mucin intake was confirmed by preventing water loss. • UVB-reduced skin elasticity was increased by oral administration of snail mucin in a dose-dependent manner. Recently, the interests about functional ingredients for skin has been increased. Snail mucin has been used to as cosmetic constituent for skin though, the potential of snail mucin for nutricosmetic ingredient has not been fully evaluated. Mucin is a biosynthesized macromolecule which can protect the external damage. The present study investigated the photoprotective effect of the snail mucin against ultraviolet B (UVB)-induced skin photoaging in an animal model. SKH-1 hairless male mice were fed with snail mucin or vehicle for 14 weeks with UVB exposure. Evaluation for the skin damage was analyzed skin replicas, epidermal thickness and collagen fiber integrity, and the moisture contents in the dermal tissue. As well as we studied the effect of snail mucin on the expression of matrix metalloproteinase (MMP)-1/13, hyaluronic acid synthase (HAS) and hyaluronidase (HYAL). The safety of intake of snail mucin is also evaluated in the liver, spleen, and liver damage enzyme level. The results showed that the depth of the wrinkles, relative moisture content, relative elasticity induced by UVB irradiation on the epidermis of mice were obviously improved by supplementation of snail mucin. Furthermore, snail mucin intake did not cause liver size change, body weight change, spleen enlargement, and liver damage enzyme. Taken together, oral administration of snail mucin improved UVB-induced photoaging properties such as wrinkle depth, moisture loss, and loss of elasticity on the skin with no toxicity. Therefore, we suggest potential of ingredient of nutricosmetics.

Regular Intake of Green Tea Polyphenols Suppresses the Development of Nonmelanoma Skin Cancer through miR-29-Mediated Epigenetic Modifications.

Previously, we and others have shown that the regular intake of green tea polyphenols (GTPs) reduces ultraviolet B (UVB) radiation-induced skin cancer by targeting multiple signaling pathways, including DNA damage, DNA repair, immunosuppression, and inflammation. Here, we determine the effect of GTPs on UVB-induced epigenetic changes, emphasizing DNA hypermethylation in UV-exposed skin and tumors and their association with miR-29, a key regulator of DNA methyltransferases (DNMTs). Skin cancer was induced in SKH-1 hairless mice following repeated exposures of UVB radiation (180 mJ/cm2, three times/week, 24 weeks) with or without GTPs supplementation (0.2%) in drinking water. Regular intake of GTPs inhibited tumor growth by hindering the cascade of DNA hypermethylation events. GTPs supplementation significantly blocked UVB-induced DNA hypermethylation in the skin (up to 35%; p < 0.0001) and in tumors (up to 50%; p < 0.0001). Experimental results showed that the levels of DNA hypermethylation were higher in GTPs-treated mice than in the control group. The expressions of miR-29a, miR-29b, and miR-29c were markedly decreased in UV-induced skin tumors, and GTPs administration blocked UVB-induced miR-29s depletion. Furthermore, these observations were verified using the in vitro approach in human skin cancer cells (A431) followed by treatment with GTPs or mimics of miR-29c. Increased levels of miR-29 were observed in GTPs-treated A431 cells, resulting in increased TET activity and decreased DNA hypermethylation. In conclusion, UVB-mediated miR-29 depletion promotes DNA hypermethylation and leads to enhanced tumor growth by silencing tumor suppressors. Regular intake of GTPs rescued UVB-induced miR-29 depletion and prevented tumor growth by maintaining reduced DNA hypermethylation and activating tumor suppressors. Our observations suggest that miR-based strategies and regular consumption of GTPs could minimize the risk of UVB-induced skin cancers and contribute to better management of NMSCs.

Q-Switched 1,064-nm Neodymium-Doped yttrium aluminum garnet laser irradiation induces collagen remodeling in SKH-1 Hairl ess mice by activating ERK1/2 and p38MAPK signaling pathway

To select the optimal condition of 1064 nm Q-switched Nd:YAG laser irradiation and study the molecular mechanism of laser irradiation for skin rejuvenation. Sixty male, 6-week-old SKH-1 hairless mice were equally divided into 6 groups: 3d, 7d, 21d, 28d, 42d and 56d of 1064 nm laser irradiation at both 0 J/cm2 (left region) and 1.5 J/cm2 (right region) fluence. The basic skin performances were analysed via quantifying hydroxyproline content and skin hydration in the dermis and epidermis. The Collagen I, MMP2 and TIMP1, as well as ERK 1/2, p38MAPK, JNK and ERK5 signaling pathways levels were detected by qRT-PCR. Laser irradiation led to a marked increase in hydroxyproline content and skin hydration in the dermis and epidermis compared to the non-irradiated area. After laser irradiation, collagen I was markedly up-regulated, MMP2 was significantly decreased and TIMP1 was unchanged. Moreover, qRT-PCR results revealed ERK 1/2 and p38MAPK signaling pathways were activated after laser irradiation. we are firstly proves that 1064 nm laser irradiation can inhibit collagen degradation by stimulating the activation of ERK1/2 and p38MAPK signaling pathways. Additionally, the condition of laser irradiation lasting 21d at fluence of 1.5 J/cm2 displays the best effect of skin rejuvenation in our study.