UVB-irradiated Mice Research Articles

The anti-photoaging and moisturizing effects of Bouea macrophylla extract in UVB-irradiated hairless mice.

Ultraviolet (UV) light, a main cause of photoaging, leads to collapse of skin structure, resulting in wrinkle formation and dehydration. The present study assessed the anti-photoaging and moisturizing effects of Bouea macrophylla extract (BRE). UVB-irradiated hairless mice were orally administered with BME (300mg/kg/day) for 8weeks. BME ameliorated wrinkle formation, skin thickening, and inelasticity. BME upregulated COL1A1, COL3A1, COL4A1, and COL7A1 mRNA levels through activation of the transforming growth factor-β (TGF-β)/Smad pathway, thereby recovering the content of collagen reduced by UVB. Further, BME suppressed UVB-induced matrix metalloproteinase (MMP)-3 and MMP-13 expression and inhibited MMP-2 and MMP-9 activity by mediating the mitogen-activated protein kinases (MAPKs)/activator protein-1 (AP-1). BME improved moisture content by stimulating the expression of cornified envelope proteins and filaggrin-processing enzymes. Overall, the results show that BME prevents photoaging and promotes moisturization in UVB-irradiated hairless mice, suggesting its potential as a nutraceutical candidate for anti-photoaging and moisturizing effects.

Effects of phenolic constituents of Luffa cylindrica on UVB-damaged mouse skin and on dome formation by MDCK I cells

We showed that Luffa cylindrica extract prevented transepidermal water loss in UVB-irradiated hairless mice. Phenolic constituents were detected in L. cylindrica by high-performance liquid chromatography, and 12 phenylpropanoids were isolated and confirmed by NMR and negative-ion mode mass spectroscopy. 4-O-caffeoyl-glucose, 6-O-caffeoyl-glucose, 4-O-p-coumaroyl-glucose, 6-O-p-coumaroyl-glucose, 4-O-feruloyl-glucose, 6-O-feruloyl-glucose, caffeic acid, and ferulic acid were isolated from L. cylindrica for the first time. The L. cylindrica extract and phenylpropanoids were found to promote the dome formation by Madin–Darby canine kidney I epithelial cells, with p-coumaric acid being the most effective. Furthermore, p-coumaric acid upregulated the expression of aquaporin-3 (AQP3) mRNA in a dose- and time-dependent manner. These results suggested that L. cylindrica extract enhances the water permeability of the skin, owing to the AQP3 expression induced by p-coumaric acid. Therefore, L. cylindrica extract might contribute to the treatment of diseases such as dry syndrome, which cause the tissue’s inability to retain moisture.

Eucalyptus globulus extract protects against UVB-induced photoaging by enhancing collagen synthesis via regulation of TGF-β/Smad signals and attenuation of AP-1

UV irradiation triggers the overproduction of matrix metalloproteinases and collagen degradation, which in turn causes increased pigmentation, dryness, and deep wrinkling of the skin. These chronic symptoms are collectively referred to as photoaging. Eucalyptus globulus is an evergreen tree that is widely used in cosmetics because of its antimicrobial activity. In this study, we investigated the protective effect of 50% ethanol extracts of Eucalyptus globulus on UV-induced photoaging in vitro and in vivo. Normal human dermal fibroblasts were treated with Eucalyptus globulus at concentrations ranging from 1 to 100 μg/mL after UVB or non-UVB irradiation. We found that Eucalyptus globulus suppressed the expression of MMPs and IL-6, but increased the expression of TGF-β1 and procollagen type 1. In addition, Eucalyptus globulus inhibited activation of the AP-1 transcription factor, an inducer of MMPs. Eucalyptus globulus was also found to regulate TGF-β/Smad signaling by reversing the activity of negative Smad regulators. Lastly, in vivo studies showed that topical application of Eucalyptus globulus on UVB-irradiated hairless mice reduced wrinkle formation and dryness by down-regulating MMP-1 and up-regulating expression of elastin, TGF-β1, and procollagen type 1. Taken together, these data suggest that Eucalyptus globulus may be a useful agent in cosmetic products.

Recovery Effects of Oral Administration of Glucosylceramide and Beet Extract on Skin Barrier Destruction by UVB in Hairless Mice.

Purified glucosylceramide from beet extract (beet GlcCer) and beet extract containing an equal amount of GlcCer were administered orally to ultra violet B (UVB)-irradiated mice, and differences in the protective effects against skin barrier dysfunction caused by UVB irradiation were compared. In the beet GlcCer group, epidermal thickening and the decrease in stratum corneum (SC) ceramide content caused by UVB irradiation were reduced. In the group that was orally administered beet extract containing glucosylceramide, effects similar to those in the beet GlcCer group were observed. Oral administration of beet GlcCer had no obvious effects against an increase in TEWL or decrease in SC water content after UVB irradiation, but there was improvement in the beet extract group. Oral administration of beet GlcCer is effective in improving skin barrier function in UVB-irradiated mice. Beet extract contains constituents other than GlcCer that are also effective in improving skin barrier function.

Oral Administration of Glycine and Leucine Dipeptides Improves Skin Hydration and Elasticity in UVB-Irradiated Hairless Mice.

Placenta is a special organ that contains many nutrients such as growth factors, minerals, and bioactive peptides. Dipeptides of glycine and leucine are major components of porcine placenta extracts (PPE) that has been used as an alternative of human placenta extracts. In this study, we investigated whether major peptides of PPE, Glycyl-L-Leucine (Gly-Leu), L-Leucyl-Glycine (Leu-Gly), and L-Leucyl-L-Leucine (Leu-Leu), affect skin hydration and elasticity in vitro and in vivo. We found that Gly-Leu and Leu-Gly dipeptides induced the expression of transglutaminase 1 in normal human epidermal keratinocytes (NHEKs) whereas Leu-Leu dipeptides did not. Treatment with Gly-Leu or Leu-Gly significantly increased hyaluronan (HA) synthesis in NHEKs and the upregulation of hyaluronan synthase 2 (HAS2) mRNA level was confirmed. In addition, elastase activity was inhibited in NHEKs treated with Gly-Leu or Leu-Gly dipeptides. Oral administration of Gly-Leu or Leu-Gly dipeptides increased skin hydration and elasticity in UVB-irradiated hairless mice. The significant upregulation of HA in UVB-irradiated hairless mice was observed in response to oral administration of Gly-Leu or Leu-Gly. These results suggest that the major dipeptides of porcine placenta, Gly-Leu and Leu-Gly, are potentially active ingredients for skin moisturization formulations.

The pathogenic role of interleukin-22 and its receptor during UVB-induced skin inflammation.

Recent studies show that IL-22, a cytokine produced by activated CD4+ T cells and NK cells, plays a pathogenic role in acute and chronic skin diseases. While IL-22 is produced by immune cells, the expression of IL-22Rα, the functional subunit of IL-22R, is mostly restricted to non-hematopoietic cells in organs such as the skin and pancreas. Although it is well known that ultraviolet B (UVB) radiation induces skin inflammation, there have been no reports regarding the effect of UVB on the expression of IL-22Rα. This study investigated IL-22Rα expression and IL-22-mediated proliferation and pro-inflammatory cytokine production by UVB-irradiated keratinocytes. IL-22Rα was increased in HaCaT and primary human keratinocytes after UVB irradiation through the translocation of IL-22Rα from the cytosol to the membrane. This increase in the expression of IL-22Rα was mediated by the PI3K/Akt pathway. Moreover, the suppression of keratinocyte proliferation by UVB irradiation was inhibited by treatment with IL-22. At the same time, IL-22 increased the production of IL-1α, IL-6, and IL-18 in UVB-irradiated HaCaT cells and primary human keratinocytes. Finally, IL-22Rα expression was increased in UVB-irradiated human and mouse skin by immunohistochemistry. The increased expression of IL-22Rα therefore promotes keratinocyte proliferation and pro-inflammatory cytokine production during UVB-induced skin inflammation, suggesting that UVB facilitates skin inflammation by increasing the responsiveness of keratinocytes to IL-22. This study provides a new insight into UVB-induced skin inflammation and the regulation of related inflammatory skin diseases.

Integrative metabolomic analysis reveals diet supplementation with green tea alleviates UVB-damaged mouse skin correlated with ascorbate metabolism and urea cycle

While green tea is known to protect skin from ultraviolet (UV) light, underlying damage-repair mechanisms remain unclear. The major objective of this study was to investigate, using multi-omics analysis, the metabolic mechanisms associated with the effects of a diet supplemented with green tea (SGT) in UVB-damaged mice. Six to eight weeks old female Skh:HR-1 mice were randomly divided into three experimental groups i.e., non-irradiated with control diet (NOR), UVB-irradiated with control diet (UND), and UVB-irradiated with SGT (UGD), and subjected to experimental conditions over 10 weeks. The skin samples were analyzed by metabolomics, transcriptomics, and in silico modeling. Our results revealed that SGT significantly alleviated UVB-induced metabolite alterations (aspartic acid, ornithine, ascorbic acid, ethanolamine, and C20:0-lysophosphatidylethanolamine) and gene expressions (keratin sulfate biosynthesis/degradation, fatty acid oxidation, and steroid metabolism) in the skin. Among these changes, key metabolic pathways, including ascorbate metabolism and the urea cycle, were the major pathways mitigated through SGT diet among UGD group mice. Additionally, SGT treatment also affected serum and hepatic lysophospholipid levels through attenuating and intensifying UVB-induced metabolic changes, respectively. Our results suggested that the SGT diets primarily influenced ascorbate metabolism and the urea cycle in UVB-irradiated mouse skin, alleviating deleterious UVB-induced skin wrinkles, epidermal thickening, and collagen-fiber destruction.

757 A possible role for M2 macrophages in preservation of dermal collagen during UVB exposure

We previously reported that giving anti-TNFα antibodies (etanercept) to mice blocks UVB recruitment of neutrophils and macrophages into the dermis, but paradoxically, etanercept accelerates UVB-induced loss of dermal collagen. To examine an unsuspected role for neutrophils or macrophages in dermal collagen preservation during UVB exposure, we performed neutrophil depletion and quantification of macrophage subtypes. Of note, M2 macrophages are involved in tissue remodeling in other circumstances and produce TGFβ, an inducer of procollagen. C57BL/6J mice were treated with either murine etanercept (4mg/kg/d) or an anti-Ly6G-specific monoclonal antibody (400μg/d to deplete neutrophils) for 7 days i.p, beginning 2 days before UVB exposure. Mice were irradiated with UVB (100 mJ/cm2/d for 5 d) or sham-irradiated. Skin was stained for neutrophils, M2 macrophages, TGFβ by IHC, and collagen fibers using picrosirius red. Under circular polarized light, picrosirius red differentiates collagen fibers as red or yellow (mature thick type I fibers) versus green (thin type III fibers). Our data show that in UVB-irradiated mice red fibers were decreased compared with sham-irradiated controls. In UVB+etanercept-treated mice, red fibers were markedly decreased compared to UVB without etanercept (p=0.001). Neutrophil-depleted UVB-treated mice showed more red fibers relative to UVB+etanercept-treated mice (p=0.01) and were similar to that seen with sham-irradiated mice. We show that blocking TNFα significantly inhibited M2 macrophage recruitment and TGFβ accumulation in UVB-irradiated mice (p=0.01). Neutrophil depletion in UVB-treated mice did not inhibit M2 macrophage recruitment or TGFβ staining relative to UVB alone. In conclusion etanercept inhibits recruitment of M2 macrophages into skin, as well as TGFβ production, coinciding with decreased mature collagen in the dermis of UVB+etanercept–treated mice relative to neutrophil-depleted UVB-treated mice. Future studies will examine the effects of macrophage depletion on mature collagen in UV-irradiated murine models.

Ultraviolet B Irradiation Causes Stimulator of Interferon Genes-Dependent Production of Protective Type I Interferon in Mouse Skin by Recruited Inflammatory Monocytes.

Photosensitivity is common in patients with systemic lupus erythematosus, although the mechanisms linking ultraviolet (UV) light to flares are not well understood. We undertook this study to determine whether repetitive UVB exposure could induce type I interferon (IFN) production in normal mouse skin, and to investigate the roles of inflammatory monocytes and plasmacytoid dendritic cells (PDCs) in type I IFN production and development of UVB irradiation-induced inflammation. Mice were irradiated with UVB at 100 mJ/cm2 for 5 days, and cutaneous manifestations were examined by messenger RNA expression of inflammatory and type I IFN response genes, histology, and flow cytometry. Inflammatory monocyte and PDC depletion experiments were performed in CCR2-diphtheria toxin receptor (DTR)-transgenic mice and blood dendritic cell antigen 2-DTR-transgenic mice. The roles of type I IFN and of the adaptor protein stimulator of IFN genes (STING) in UVB irradiation-induced inflammation were investigated using IFN-α/β/ω receptor (IFNAR)-knockout mice and STING-knockout mice. Repeated UVB irradiation stimulated an inflammatory cell infiltrate and induction of type I IFN and proinflammatory cytokines. Interestingly, the type I IFN response was independent of PDCs but dependent on inflammatory monocytes, which were recruited following UVB irradiation. The adaptor protein STING was necessary for both type I IFN and proinflammatory cytokine expression in the skin. UVB-irradiated IFNAR-knockout mice showed increased levels of proinflammatory genes and more severe inflammation by histology, suggesting a protective role for type I IFN. In wild-type mice, repeated doses of UVB irradiation induce monocyte-dependent and PDC-independent expression of type I IFN together with expression of other proinflammatory cytokines. Induction is dependent on the adaptor protein STING. Surprisingly, studies using IFNAR-deficient mice revealed that type I IFN protects against UVB irradiation-induced skin inflammation, in part by attenuating proinflammatory cytokine expression and limiting tissue damage.

Far-infrared suppresses skin photoaging in ultraviolet B-exposed fibroblasts and hairless mice.

Ultraviolet (UV) induces skin photoaging, which is characterized by thickening, wrinkling, pigmentation, and dryness. Collagen, which is one of the main building blocks of human skin, is regulated by collagen synthesis and collagen breakdown. Autophagy was found to block the epidermal hyperproliferative response to UVB and may play a crucial role in preventing skin photoaging. In the present study, we investigated whether far-infrared (FIR) therapy can inhibit skin photoaging via UVB irradiation in NIH 3T3 mouse embryonic fibroblasts and SKH-1 hairless mice. We found that FIR treatment significantly increased procollagen type I through the induction of the TGF-β/Smad axis. Furthermore, UVB significantly enhanced the expression of matrix metalloproteinase-1 (MMP-1) and MMP-9. FIR inhibited UVB-induced MMP-1 and MMP-9. Treatment with FIR reversed UVB-decreased type I collagen. In addition, FIR induced autophagy by inhibiting the Akt/mTOR signaling pathway. In UVB-induced skin photoaging in a hairless mouse model, FIR treatment resulted in decreased skin thickness in UVB irradiated mice and inhibited the degradation of collagen fibers. Moreover, FIR can increase procollagen type I via the inhibition of MMP-9 and induction of TGF-β in skin tissues. Therefore, our study provides evidence for the beneficial effects of FIR exposure in a model of skin photoaging.

Topical application of neem leaves prevents wrinkles formation in UVB-exposed hairless mice

Azadirachta indica A. Juss. (Neem) has been used in India for the treatment of skin problems for centuries. However, no skin photoaging-related research has been performed with this agent. In the present study, neem leaf extract at 1, 10, and 50μg/mL was investigated for its skin anti-aging effects in UVB-irradiated NHDFs and hairless mice. Regulation of molecular signaling pathways by neem leaf extract during UVB exposure was investigated in both in vitro and in vivo models. UVB-irradiated skin model treated with neem leaf extract showed increased type I procollagen and elastin as a result of enhanced synthesis via two pathways. Firstly, transforming growth factor TGF-β1 is up-regulated. Secondly, intracellular reactive oxygen species (ROS), transcription activator AP-1 protein expression, and MAPK are down-regulated. The down-regulation of signaling molecules caused the suppression of type I procollagen degrading enzymes such as matrix metalloproteinase-1 and type I procollagen synthesis inhibitor such as interleukin-6. In particular, topical application of neem leaf to UVB-irradiated hairless mice was shown to be very effective in treating the symptoms of skin aging such as wrinkles, thickening, water loss, and erythema. Therefore, our results indicated that neem leaf ethanolic extract is a promising anti-aging candidate for topical therapy products.

Effect of Thai banana (Musa AA group) in reducing accumulation of oxidation end products in UVB-irradiated mouse skin

ScopeChronic UVB exposure causes skin disorders and cancer through DNA strand breaks and oxidation of numerous functional groups of proteins and lipids in the skin. In this study, we investigated the effects of Thai banana (Musa AA group, “Khai,” and Musa ABB group, “Namwa”) on the prevention of UVB-induced skin damage when fed to male ICR mice. Methods and ResultsMice were orally fed banana (Khai or Namwa) fruit pulps at dose of 1mg/g body weight/day for 12weeks. The shaved backs of the mice were irradiated with UVB for 12weeks. The intensity dose of UVB-exposure was increased from 54mJ/cm2/exposure at week 1 to 126mJ/cm2/exposure at week 12. A significant increase in skin thickness, lipid peroxidation, protein oxidation end products, and expression of MMP-1 was observed in UVB-irradiated mouse skin. A reduction in the accumulation of oxidation end products was found in the skin of UVB-irradiated mice receiving Khai. This occurred in conjunction with a reduction in MMP-1 expression, inhibition of epidermal thickening, and induction of γ-GCS expression. ConclusionThe dietary intake of Khai prevented skin damage from chronic UVB exposure by increased γ-GCS expression and reduced oxidation end products included carbonyls, malondialdehyde and 4-hydroxynonenal.

Ginsenoside Rg1 attenuates ultraviolet B-induced glucocortisides resistance in keratinocytes via Nrf2/HDAC2 signalling.

Oxidative stress, which occurs after ultraviolet (UV) radiation, usually results in Glucocorticoid (GC) resistance and the subsequent development of skin inflammation. One approach to protecting the skin against UV radiation is the use of antioxidants. The ginsenoside Rg1 is a novel natural antioxidant isolated from the medicinal plant Panax ginseng C.A. Mey. We demonstrated that UVB exposure exacerbated inflammation and reduced both the level of the glucocorticoid receptor (GR) and the efficacy of dexamethasone (Dex) in human keratinocytes (HaCaT cells). Pretreatment with Rg1 increased the expression of GR and restored Dex responsiveness to inflammation in UVB-irradiated HaCaT cells. Mechanistically, Rg1 rescued UVB-induced HDAC2 degradation. HDAC2 knockdown partially abolished the Rg1-induced up-regulation of GR and the enhancement of GC sensitivity. In addition, Rg1 reduced the production of reactive oxygen species (ROS), which preceded the up-regulation of HDAC2, and consequent sensitization of cells to Dex. Moreover, Rg1 treatment promoted the translocation and activation of Nrf2. Nrf2 knockdown partially abolished the Rg1-induced decrease of ROS production and increase of HDAC2. Rg1 also potentiated the anti-inflammatory effects of Dex in UVB-irradiated mouse skin. In conclusion, we demonstrated that Rg1 attenuated UVB-induced GC insensitivity. Notably, these effects were partially mediated by the Nrf2/HDAC2 pathway.

Protective Effects of Standardized Siegesbeckia glabrescens Extract and Its Active Compound Kirenol against UVB-Induced Photoaging through Inhibition of MAPK/NF-κB Pathways.

Anti-photoaging effects of standardized Siegesbeckia glabrescens extract (SGE) and its major active compound kirenol were investigated using Hs68 human dermal fibroblasts and hairless mice, respectively. UVB-irradiated hairless mice that received oral SGE (600 mg/kg/day) showed reduced wrinkle formation and skinfold thickness compared with the UVB-irradiated control. Furthermore, SGE treatment increased the mRNA levels of collagen synthesis genes (COL1A1, COL3A1, COL4A1, and COL7A1) and activated antioxidant enzyme (catalase), while suppressing matrix metalloproteinase (MMP-2, -3, -9, and -13) expression. In Hs68 fibroblasts, kirenol also significantly suppressed MMP expression while increasing the expression of COL1A1, COL3A1, and COL7A1. Collectively, our data demonstrate that both SGE and kirenol attenuated UVB-induced photoaging in hairless mice and fibroblasts through inhibition of the mitogen-activated protein kinases and nuclear factor kappa B pathways, suggesting that SGE has potential to serve as a natural anti-photoaging nutraceutical.

Anti-wrinkle effects of Sargassum muticum ethyl acetate fraction on ultraviolet B-irradiated hairless mouse skin and mechanistic evaluation in the human HaCaT keratinocyte cell line.

The present study investigated the photoprotective properties of the ethyl acetate fraction of Sargassum muticum (SME) against ultraviolet B (UVB)-induced skin damage and photoaging in a mouse model. HR-1 strain hairless male mice were divided into three groups: An untreated control group, a UVB-irradiated vehicle group and a UVB-irradiated SME group. The UVB-irradiated mice in the SME group were orally administered with SME (100 mg/kg body weight in 0.1 ml water per day) and then exposed to radiation at a dose of 60–120 mJ/cm2. Wrinkle formation and skin damage were evaluated by analysis of skin replicas, epidermal thickness and collagen fiber integrity in the dermal connective tissue. The mechanism underlying the action of SME was also investigated in the human HaCaT keratinocyte cell line following exposure of the cells to UVB at a dose of 30 mJ/cm2. The protein expression levels and activity of matrix metalloproteinase-1 (MMP-1), and the binding of activator protein-1 (AP-1) to the MMP-1 promoter were assessed in the HaCaT cells using western blot analysis, an MMP-1 fluorescent assay and a chromatin immune-precipitation assay, respectively. The results showed that the mean length and depth of the wrinkles in the UVB-exposed hairless mice were significantly improved by oral administration of SME, which also prevented the increase in epidermal thickness triggered by UVB irradiation. Furthermore, a marked increase in collagen bundle formation was observed in the UVB-treated mice with SME administration. SME pretreatment also significantly inhibited the UVB-induced upregulation in the expression and activity of MMP-1 in the cultured HaCaT keratinocytes, and the UVB-enhanced association of AP-1 with the MMP-1 promoter. These results suggested that SME may be useful as an anti-photoaging resource for the skin.

Anti-photoaging properties of the phosphodiesterase 3 inhibitor cilostazol in ultraviolet B-irradiated hairless mice.

We investigated whether cilostazol, an activator of cyclic adenosine monophosphate (cAMP)-dependent intracellular signaling, could inhibit ultraviolet B (UVB) irradiation-induced photoaging in HR-1 hairless mice. Cilostazol decreased wrinkle formation and skin thickness in UVB-irradiated mice, as well as increased staining of collagen fibers and inhibition of reactive oxygen species (ROS) formation in the skin. Moreover, the proteolytic activities of gelatinase matrix metalloproteinase (MMP)-9 and collagenase MMP-3 were significantly decreased in UVB-irradiated mice treated with cilostazol. Western blotting showed that UVB-induced activation of p38 mitogen-activated protein kinases (MAPK) and nuclear factor (NF)-κB was significantly inhibited by cilostazol, whereas the activation of Akt was significantly enhanced by cilostazol. Confirmation of localized protein expression in the skin revealed marked p38 MAPK and NF-κB activation that was mainly detected in the dermis. Marked Akt activation was mainly detected in the epidermis. Our results suggest that cilostazol may have anti-photoaging effects on UVB-induced wrinkle formation by maintaining the extracellular matrix density in the dermis, which occurs via regulation of ROS and related p38 MAPK and NF-κB signaling, and subsequent down-regulation of MMPs. Therefore, cilostazol may protect against photoaging-induced wrinkle formation.

The underlying mechanism of proinflammatory NF-κB activation by the mTORC2/Akt/IKKα pathway during skin aging.

Mammalian target of rapamycin complex 2 (mTORC2), one of two different enzymatic complexes of mTOR, regulates a diverse set of substrates including Akt. mTOR pathway is one of well-known mediators of aging process, however, its role in skin aging has not been determined. Skin aging can be induced by physical age and ultraviolet (UV) irradiation which are intrinsic and extrinsic factors, respectively. Here, we report increased mTORC2 pathway in intrinsic and photo-induced skin aging, which is implicated in the activation of nuclear factor-κB (NF-κB). UVB-irradiated or aged mice skin revealed that mTORC2 activity and its component, rictor were significantly upregulated which in turn increased Akt activation and Akt-dependent IκB kinase α (IKKα) phosphorylation at Thr23 in vivo. We also confirmed that UVB induced the mTORC2/Akt/IKKα signaling pathway with HaCaT human normal keratinocytes. The increased mTORC2 signaling pathway during skin aging were associated to NF-κB activation. Suppression of mTORC2 activity by the treatment of a mTOR small inhibitor or knockdown of RICTOR partially rescued UVB-induced NF-κB activation through the downregulation of Akt/IKKα activity. Our data demonstrated the upregulation of mTORC2 pathway in intrinsic and photo-induced skin aging and its role in IKKα/NF-κB activation. These data not only expanded the functions of mTOR to skin aging but also revealed the therapeutic potential of inhibiting mTORC2 in ameliorating both intrinsic skin aging and photoaging.

Protective effects of adipose-derived stem cells against UVB-induced skin pigmentation

Background: Hyperpigmentation, mainly following UV-irradiation, can cause major cosmetic concerns. Human adipose tissue-derived stem cells (ASCs) have been reported to serve as whitening agents through a paracrine effect. However, there have been few reports on the direct effects of ASCs on skin pigmentation following UVB-irradiation.Methods: To evaluate the effect of ASCs on UVB-irradiated mouse skin, UVB-irradiation alone was applied to one side of the backs of mice (melanin-processing hairless mouse, HRM-2) as a control, and UVB-irradiation plus injection of ASCs was applied to the contralateral side. Skin pigmentation and histology were evaluated and the number of DOPA-positive melanocytes in the mouse skin was counted. The absolute value of ΔL* via a colorimeter was measured to evaluate the degree of skin pigmentation. The effects of ASCs on the melanogenic activities of mouse skin were examined by measuring the tyrosinase activity and the melanin contents in the epidermis of the mouse skin.Results: Skin pigmentation was suppressed in the ASC-injected side. Moreover, the change in skin thickness following UVB irradiation was reduced in the ASC-injected side. The number of DOPA-positive melanocytes in the ASC-injected side (139 ± 18 cells/mm2) was significantly lower than that in the control side (239 ± 48 cells/mm2). The tyrosinase activity (67.4 ± 9.8% of that of the control side) and melanin content (63.4 ± 5.7% of that of the control side) of the ASC-injected side were also significantly reduced.Conclusions: Collectively, these results suggest that ASCs injected subcutaneously into the backs of mice can attenuate tanning following UVB-irradiation, through suppression of tyrosinase activity.

HPLC–DAD–MS/MS profiling of standardized rosemary extract and enhancement of its anti-wrinkle activity by encapsulation in elastic nanovesicles

The anti-wrinkle activity of defatted rosemary extract (DER) was assessed, and its effect was optimized by encapsulation in transferosomes (TFs). DER was standardized to a rosmarinic acid content of 4.58±0.023mg% using reversed-phase high performance liquid chromatography (Rp-HPLC), and its components were identified by HPLC-diode array detection-tandem mass spectrometry. In vitro free radical scavenging assays showed DER had high free radical scavenging activity against 2,2-diphenyl-2-picryl hydrazyl, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), and superoxide radicals. DERalso inhibited bleaching of β-carotene with high Fe(III) and Fe(II) chelating ability. In vivo anti-wrinkle activities of topically applied DER (20, 50, and 100mg) and a TF formulation (TF4, 20mg of DER) were evaluated in UVB-irradiated mice using a wrinkle scoring method, metalloproteinase (MMP) expression, and histopathology. Among the nanovesicles, TF4 was the most deformable, and had an acceptable size and encapsulation efficiency and enhanced permeation of DER through rat skin compared with unencapsulated DER. DER (50 and 100mg) and TF4 significantly inhibited MMP-2 and MMP-9 expression and improved wrinkle scores. DER and TF4 moderately decreased epidermal thickness without pigmentation. DER is a potent natural antioxidant for combating skin aging. Moreover, encapsulation of DER in TFs will enhance its skin permeation and anti-wrinkle activity.

Caffeic Acid Inhibits Chronic UVB-Induced Cellular Proliferation Through JAK-STAT3 Signaling in Mouse Skin.

Signal transducers and activators of transcription 3 (STAT3) play a critical role in inflammation, proliferation and carcinogenesis. Inhibition of JAK-STAT3 signaling is proved to be a novel target for prevention of UVB-induced skin carcinogenesis. In this study, chronic UVB irradiation (180mJcm(-2) ; weekly thrice for 30weeks) induces the expression of IL-10 and JAK1 that eventually activates the STAT3 which leads to the transcription of proliferative and antiapoptotic markers such as PCNA, Cyclin-D1, Bcl2 and Bcl-xl, respectively. Caffeic acid (CA) inhibits JAK-STAT3 signaling, thereby induces apoptotic cell death by upregulating Bax, Cytochrome-C, Caspase-9 and Caspase-3 expression in mouse skin. Furthermore, TSP-1 is an antiangiogeneic protein, which is involved in the inhibition of angiogenesis and proliferation. Chronic UVB exposure decreased the expression of TSP-1 and pretreatment with CA prevented the UVB-induced loss of TSP-1 in UVB-irradiated mouse skin. Thus, CA offers protection against UVB-induced photocarcinogenesis probably through modulating the JAK-STAT3 in the mouse skin.