Protective effects of a cream containing Dead Sea minerals against UVB-induced stress in human skin

Background:  Dead Sea (DS) mud and water are known for their unique composition of minerals, and for their therapeutic properties on psoriasis and other inflammatory skin diseases. Their mode of action, however, remains poorly known.
Objectives:  To analyse the ability of Dermud™, a leave-on skin preparation containing DS mud and other ingredients like DS water, zinc oxide, aloe-vera extract, pro-vitamin B5 and vitamin E, to antagonize biological effects induced by UVB irradiation in skin when topically applied in organ cultures.
Methods:  We have used human skin organ cultures as a model to assess the biological effects of UVB irradiation and of Dermud™ cream topical application. Skin pieces were analysed for mitochondrial activity by MTT assay, for apoptosis by caspase 3 assay, for cytokine secretion by solid phase ELISA, for overall antioxidant capacity by ferric reducing antioxidant power and Oxygen radical absorbance capacity assays (epidermis) or by cyclic voltammetry (external medium), and for uric acid (UA) content by HPLC.
Results:  We report that UVB irradiation decreases cell viability, total antioxidant capacity and UA contents in the epidermis of skin organ cultures, while increasing the levels of apoptosis in cells and their cytokine secretion. Topical application of Dermud™ decreased all these effects significantly.
Conclusions:  Our results clearly show that Dermud™ has protective, anti-oxidant and anti-inflammatory properties that can antagonize biological effects of UVB irradiation in skin. It may therefore be able to reduce skin photodamage and photoaging, and more generally to reduce oxidative stress and inflammation in skin pathologies.     

Skin organ culture as a model to study oxidative stress, inflammation and structural alterations associated with UVB-induced photodamage

Background: Ultraviolet (UV) irradiation is a major cause of skin damage, of long‐term alteration of skin metabolism, homoeostasis and physical structure. The analysis of UV‐induced pathogenic processes requires in vitro models allowing biochemical studies, and appropriate for the development of novel, accurate diagnosis methods based on non‐invasive procedures. Objectives: This work was aimed to reproduce the effects of UVB on whole‐skin explants ex vivo and to study underlying biochemical mechanisms, especially in correlation with skin autofluorescence. Methods: Human skin organ cultures were irradiated with UVB and subjected to enzyme assays, Western blots, solid‐phase ELISA, HPLC and fluorescence measurements. Results: UVB irradiation was found to enhance ROS production, to deplete the pool of low‐molecular‐weight antioxidants and to decrease the overall antioxidant capacity in the epidermis, in a manner dependent on xanthine‐oxidase activity. Epidermal cell proliferation and mitochondrial activity were transiently stimulated. IκB‐α was degraded, and the secretion of inflammatory cytokines was drastically increased. Inducible nitric oxide synthase activity was increased in non‐irradiated controls, probably due to the mechanical stress of skin excision, and this phenomenon was suppressed by UVB. Autofluorescence measurements revealed alterations of dermal protein crosslinks following UVB irradiation. Conclusions: Skin organ culture proved to be an integrated model appropriate for in vitro analysis of UVB biologic effects and their correlations, and for the study of non‐invasive diagnostic methods in cellular and molecular terms.     

Unusual wrinkle formation after temporary skin fixation followed by UVB irradiation in hairless mouse skin

Abstract Generally, many wrinkles form on the human face, and temporary wrinkles eventually become permanent. We evaluated the effects of temporary skin fixation on wrinkle formation after UVB irradiation using the back skin of hairless mice. In the group treated with UVB irradiation immediately after production using cyanoacrylate resin of an artificial groove parallel to the midline, wrinkles formed parallel to the midline, an uncommon direction for wrinkle formation in this mouse model. These wrinkles did not disappear even when the skin was stretched. No such changes were observed in the group in which only the temporary groove alone was produced without UVB irradiation. In 3-D surface parameter analysis, all roughness parameters in the group treated with UVB irradiation immediately after production of an artificial groove were significantly increased relative to the age-matched control group. In contrast, no differences were observed between the group in which only the temporary groove alone was produced without UVB irradiation and age-matched controls. The results of this study suggest that both a temporary groove in the skin and UVB irradiation are necessary for wrinkle formation in the back skin of hairless mice.     

Targeted overexpression of the angiogenesis inhibitor thrombospondin-1 in the epidermis of transgenic mice prevents ultraviolet-B-induced angiogenesis and cutaneous photo-damage

Chronic ultraviolet-B irradiation of the skin results in epidermal hyperplasia, degradation of extracellular matrix molecules, and formation of wrinkles. To characterize the biologic role of the vascular system in the mediation of ultraviolet-B-induced skin damage, we performed quantitative analyses of cutaneous blood vessels of mice after 10 wk of ultraviolet-B irradiation. Skin vascularization was greatly increased after chronic ultraviolet-B exposure with a significant increase of both the number and the size of dermal blood vessels, associated with upregulation of vascular endothelial growth factor expression in the hyperplastic epidermis. To directly study whether inhibition of angiogenesis may diminish ultraviolet-B-induced cutaneous damage, wild-type and transgenic mice with skin-specific overexpression of the endogenous angiogenesis inhibitor thrombospondin-1 were subjected to the same ultraviolet-B irradiation regimen. Ultraviolet-B-irradiated thrombospondin-1 transgenic mice showed a significantly reduced skin vascularization, decreased endothelial cell proliferation, and increased endothelial cell apoptosis rates, compared with wild-type mice. Moreover, dermal photo-damage and wrinkle formation were greatly reduced in thrombospondin-1 transgenic mice. These results reveal an important role of the cutaneous vascular system in mediating ultraviolet-B-induced skin damage and suggest inhibition of angiogenesis as a potential new approach for the prevention of chronic cutaneous photo-damage.     

Recent advances in characterizing biological mechanisms underlying UV-induced wrinkles: a pivotal role of fibrobrast-derived elastase

In clinical studies, the formation of facial wrinkles has been closely linked to the loss of elastic properties of the skin. Cumulative irradiation with ultraviolet (UV) B at suberythemal doses significantly reduces the elastic properties of the skin, resulting in the formation of wrinkles. In in vitro studies, we identified a paracrine pathway between keratinocytes and fibroblasts, which leads to wrinkle formation via the up-regulation of fibroblast elastases that degrade elastic fibers. UVB irradiation stimulates the activity of fibroblast elastases in animal skin. Scanning electron microscopy revealed that cumulative UVB irradiation elicits a marked alteration in the three-dimensional structure of elastic fibers, which is closely associated with the subsequent reduction in the elastic properties of the skin, resulting in wrinkle formation. Studies using anti-wrinkle treatments suggest a close relationship between the recovery of wrinkles and an improvement in the linearity of elastic fibers. Those studies also suggest a close correlation between the recovery in the linearity of elastic fibers and the improvement in skin elasticity. In a study using ovariectomized animals, we characterized the important role of elastase in their high vulnerability to UV-induced wrinkle formation. A synthetic inhibitor specific for fibroblast elastases significantly prevents wrinkle formation without reducing the elastic properties of the skin, accompanied by minor damage in elastic fibers. Finally, we identified an effective extract of Zingiber officinale (L.) Rose from a screen of many herb extracts, which has a safe and potent inhibitory activity against fibroblast elastases. Animal studies using the L. Rose extract revealed that it has significant preventive effects against UVB-induced wrinkle formation, which occur in concert with beneficial effects on skin elasticity. A 1-year clinical study on human facial skin to determine the efficacy of the L. Rose extract demonstrated that it inhibits the UV-induced decrease in skin elasticity and prevents or improves wrinkle formation in skin around the corner of the eye without changing the water content of the stratum corneum. Our long-term studies support our hypothesis for a mechanism of wrinkle formation in which cytokine expression is activated by UV irradiation and triggers dermal fibroblasts to increase the expression of elastase. That increase in elastase results in the deterioration of the three-dimensional architecture of elastic fibers, reducing skin elasticity and finally leading to the formation of wrinkles.     

甘草、红景天、黄芪粗提物对中波紫外线诱导小鼠皮肤组织白介素—10的影响

目的探索甘草、红景天、黄芪等粗提物对中波紫外线（uw3）损伤BALB／c小鼠皮肤组织的保护作用及其机制。方法将54只BALB／c小鼠用随机数字法分为9组（每组6只）：正常对照组、UVB对照组、溶剂对照组、UVB＋5％与10％甘草组、UVB＋5％与10％红景天组、UVB＋5％与10％黄芪组。其中,正常对照组不予处理,UVB对照组单独给予UVB照射,溶剂对照组给予外涂蒸馏水＋UVB照射,其余各处理组分别给予外涂相应浓度药物＋UVB照射,连续1个月。采用酶联免疫吸附试验（ELISA）测定各组小鼠背部照射部位皮肤组织匀浆上清液中白介素（IL）．10水平。结果经UVB慢性照射后小鼠皮肤中Ⅲ—10水平为（838．8±114．34）pg／ml,较正常对照组（568．45±78．8）pg／ml显著增高（P〈0．01）,经不同剂量甘草、红景天、黄芪粗提物水溶液处理后可进一步上调IL-10水平,以甘草组最为明显,但IL-10水平与粗提物浓度之间无明显依赖关系。结论在受到UVB慢性照射后小鼠皮肤组织中IL-10表达水平增加,甘草、红景天、黄芪粗提物水溶液可进一步上调其IL-10水平,上述3种药物对UVB诱导的小鼠皮肤损伤的保护作用可能与上调IL-10表达水平有关。     

Contrasting effects of an ultraviolet B and an ultraviolet A tanning lamp on interleukin-6, tumour necrosis factor-α and intercellular adhesion molecule-1 expression

BACKGROUND: Recent studies have demonstrated that a tanning lamp emitting predominantly ultraviolet (UV) A induces significant yields of the type of potentially mutagenic DNA damage that are associated with the onset of skin cancer (i.e. cyclobutane pyrimidine dimers). UV-induced immunosuppression is also an important event leading to skin cancer. OBJECTIVES: To the modulation of key immunological molecules following exposure to a broad-spectrum UVB lamp and a predominantly UVA-emitting tanning lamp using model in vitro systems. METHODS: We compared secretion and mRNA expression of interleukin (IL)-6 and tumour necrosis factor (TNF)-alpha in normal human epidermal keratinocytes, and interferon (IFN)-gamma-induced intracellular adhesion molecule (ICAM)-1 in normal human fibroblasts irradiated in vitro with a broad-spectrum UVB lamp or with a Philips 'Performance' tanning lamp. RESULTS: With broad-spectrum UVB irradiation, upregulation of IL-6 and TNF-alpha mRNA was detected 6 h after irradiation, and a dose-dependent increase of cytokines in the supernatants of irradiated cells was found 24 h after irradiation. In contrast, there was no cytokine secretion and little evidence for mRNA upregulation following exposure to a tanning lamp. When cells were exposed first to broad-spectrum UVB, then the tanning lamp, UVB-induced cytokine secretion was inhibited, although mRNA levels were upregulated to a level close to that observed with UVB alone. By using a Schott WG 320 nm filter to attenuate the level of UVB relative to UVA emitted by the tanning lamp, the inhibition of cytokine secretion was shown to be associated with UVA exposure. Both UV sources inhibited IFN-gamma-induced ICAM-1 mRNA expression in a dose-dependent fashion. By using a Schott WG 335 nm filter, inhibition of ICAM-1 mRNA expression by the tanning lamp was shown to be associated with UVB exposure. CONCLUSIONS: These results suggest that UV sources emitting different levels of UVA and UVB have differential effects on the modulation of different immunoregulatory molecules, and indicate that there are potential interactions between these wavelengths.     

Effect of indomethacin on alteration of ATPase-positive Langerhans cell density and cutaneous sunburn reaction induced by ultraviolet-B radiation

We have investigated the effect of ultraviolet-B (UVB) irradiation on the density of epidermal ATPase-positive Langerhans cells, and the modulation of this effect by indomethacin (IND). Depilated backs of albino guinea pigs were exposed to varying doses of UVB (10-550 mJ/cm2). Skin biopsies were taken serially. There was an UVB dose-dependent decrease in the density of dendritic epidermal Langerhans cells, as identified by their membrane ATPase activity. This was accompanied by thinning and shortening, or disappearance of dendritic processes. Such changes were followed by a gradual recovery of the cell density to preirradiation level by day 21. Despite the high doses of UVB given, the maximal decrease in the density of ATPase-positive cells was only 58%. Topical application of IND, a prostaglandin-synthetase inhibitor, after irradiation resulted in a decrease of the erythema; however, the decrease in the density of ATPase-positive cells was still observed. In contrast, guinea pigs that received IND topically prior to irradiation showed a decrease erythemal response, but failed to show any decrease in the density of ATPase-positive cells. Administration of IND orally for 3 days prior to UVB exposure did not prevent the decrease in the cell density. The protective effect of topical IND, applied prior to irradiation, may be explained by its in vitro absorbance at both the UVB and UVA ranges. Topical application of IND 20 min prior to exposure to UVB in 2 human subjects resulted in an increase in the minimal erythema dose, giving a sun protection factor of 1.6, which is comparable to that produced by an equimolar concentration of para-aminobenzoic acid solution. The sun-protective property of IND, together with its activity as a prostaglandin synthetase inhibitor, indicate that it potentially could be a useful sunscreen agent. Its clinical safety and efficacy, however, remain to be determined.     

Ergocalciferol promotes in vivo differentiation of keratinocytes and reduces photodamage caused by ultraviolet irradiation in hairless mice

BACKGROUND: Ergocalciferol (VD(2)) is usually administered orally and it is metabolized to produce its biologically active metabolites in the liver and kidney. Active vitamin D is a well-known potent regulator of cell growth and differentiation. PURPOSE: Active vitamin D such as 1,25-dihydroxyvitamin D(3) (1alpha,25(OH)(2)D(3)) prevents photodamage, including wrinkles and morphologic alterations. However, its clinical and cosmetic use is limited because of its potent, associated effect on calcium metabolism. We examined the efficacy of vitamin D analogues with few adverse effects for preventing skin photodamage. METHOD: Topical application of VD(2) to hairless mouse dorsal skin, and exposure to solar-simulating ultraviolet (UV) radiation at a dose of 10.8 J/cm(2) (UVA) were performed for 15 weeks, five times a week on weekdays. At the end of the final irradiation, histological and analytical studies were performed. RESULTS: Topical application of VD(2) significantly prevented wrinkle formation and abnormal accumulation of extracellular matrix components. In addition, VD(2) suppressed excessive secretion of IL-6 induced by UV irradiation in cultured human normal keratinocytes, in a dose-dependent manner. CONCLUSION: VD(2) promoted keratinocytes differentiation in the epidermis and showed diverse physiological effects, the same as the active form of VD(3). The results suggested that the suppression of skin photodamage involved the promotion of keratinocytes differentiation and suppression of IL-6 secretion induced by exposure to UV. Topical application of VD(2) may become an effective means to suppress solar UV-induced human skin damage.     

Carbon dioxide laser treatment promotes repair of the three-dimensional network of elastic fibres in rat skin

BACKGROUND: We have previously reported that ultraviolet (UV) B irradiation induces a loss of linearity in the three-dimensional structure of dermal elastic fibres, which results in the reduction of elastic properties of the skin and leads to wrinkle formation. We further reported that repair of wrinkles by all-trans retinoic acid is accompanied by recovery of the linearity of elastic fibres. Carbon dioxide (CO2) lasers are widely used for treating wrinkles in cosmetic surgery. OBJECTIVES: To perform CO2 laser treatment of wrinkles induced in rat skin by UVB irradiation and to evaluate changes in the three-dimensional structure of dermal elastic fibres during wrinkle repair. METHODS: Wrinkles were induced in the hind limb skin of Sprague-Dawley rats by UVB irradiation (130 mJ cm-2 three times weekly for 6 weeks), followed by CO2 laser treatment (11.3 J cm-2). The surface appearance of the skin was evaluated by replica observation 6 and 10 weeks after CO2 laser treatment followed by measurement of mechanical properties using a Cutometer. Subsequently, perfusion fixation and digestion with formic acid were performed and elastic fibres were observed by scanning electron microscopy (SEM). Image analysis of SEM micrographs was carried out to evaluate the linearity in the three-dimensional structure of elastic fibres. RESULTS: Six weeks after CO2 laser treatment, all parameters of skin mechanical properties in the UVB-irradiated group recovered to levels of the control non-irradiated group, accompanied by repair of wrinkles and a significant increase in linearity of the three-dimensional structure of elastic fibres. CONCLUSIONS: These findings indicate that CO2 laser treatment has a therapeutic potential to repair wrinkles to non-irradiated levels through recovery of the three-dimensional structure of elastic fibres.     

The formation of wrinkles caused by transition of keratin intermediate filaments after repetitive UVB exposure

It has been reported that the formation of wrinkles involves changes in the elastic properties of the dermis due to the denaturation of elastic fibers. Several studies have shown that the hydration condition of the stratum corneum is also important in wrinkle formation. It is, however, still unclear how the stratum corneum contributes to wrinkle formation. Here we investigated the relationship between the formation of wrinkles and changes in the physical properties and condition of the skin after repetitive ultraviolet B (UVB) irradiation of hairless mice (HR/ICR). Repetitive UVB irradiation caused wrinkles on the dorsal skin of the mice. The elasticity (E) of the stratum corneum of UVB-irradiated mice was significantly lower than that of age-matched control (unirradiated) mice. UVB exposure also caused a deterioration of the fibrous ultrastructure of keratin intermediate filaments (KIFs) in the skin. We conclude that the deterioration of KIFs in the stratum corneum caused by repetitive UVB irradiation decreases the elastic properties of the stratum corneum, resulting in the formation of wrinkles.     

FK506 inhibits tumour necrosis factor-alpha secretion in human keratinocytes via regulation of nuclear factor-kappaB

BACKGROUND: Tacrolimus (FK506) ointment has been used for treatment of inflammatory dermatoses with remarkable success. Our previous studies have indicated that direct modulation of tacrolimus on keratinocytes (KCs) may have an impact on its therapeutic effect. The use of monoclonal antibody specific for tumour necrosis factor (TNF)-alpha has shown efficacy in treating both psoriasis and Crohn disease. Topical tacrolimus has also been shown to be effective for treating cutaneous manifestations of both diseases. OBJECTIVES: To explore the effects of FK506 on human KCs in terms of TNF-alpha secretion and to investigate the regulatory pathway involved. METHODS: Ultraviolet (UV) B-irradiated cultured KCs were treated with various concentrations of FK506. At indicated time points after UVB irradiation we determined: (i) the TNF-alpha concentrations present in the culture supernatants; (ii) the activation and translocation of nuclear factor (NF)-kappaB in the cell nucleus; and (iii) the protein expressions of IkappaB kinase (IKK) and IkappaB in the cell lysates. In addition, a mouse model was used to corroborate our in vitro findings in vivo. More specifically, topical tacrolimus was applied on to mouse skin unilaterally after UVB irradiation. The effects of FK506 on nuclear NF-kappaB expression of UVB-irradiated mouse skin were determined. RESULTS: Our results showed that FK506 dose-dependently downregulated the secretion of TNF-alpha from UVB-irradiated KCs. The activation and translocation of NF-kappaB in UVB-irradiated KCs were also dose-dependently suppressed by FK506. The degradation of IkappaB induced by UVB was also inhibited by FK506, while no change in IKK expression was noted regardless of UVB and FK506 treatment. Murine skin biopsies showed that nuclear NF-kappaB expression induced by UVB was inhibited by topical tacrolimus treatment. CONCLUSIONS: Our results indicate that FK506 inhibits TNF-alpha secretion in human KCs via direct regulation of NF-kappaB. This modulatory effect of FK506 on KCs offers a possible mechanism for how topical tacrolimus regulates cutaneous inflammatory conditions.     

Inhibition of ultraviolet-B-induced wrinkle formation by an elastase-inhibiting herbal extract: implication for the mechanism underlying elastase-associated wrinkles

BACKGROUND: Previously, we have demonstrated that fibroblast-derived elastase plays an essential role in the increased three-dimensional tortuosity of elastic fibers, contributing to the loss of skin elasticity in UV-B-exposed skin. This decrease in skin elasticity is closely associated with the formation of wrinkles induced by UV exposure. OBJECTIVE: To further clarify the role of elastase in the formation of wrinkles induced by UV exposure, we assessed the effects of an extract of Zingiber officinale (L.) Rose (which inhibits fibroblast-derived elastase) on the wrinkle formation induced by chronic UV-B irradiation. RESULTS: Topical application of an extract of Zingiber officinale (L.) Rose to rat or hairless mouse skin significantly inhibited the wrinkle formation induced by chronic UV-B irradiation at a suberythemal dose, which was accompanied by a significant prevention of the decrease in skin elasticity in both types of animal skin. In the rat hind limb skin, consistent with the inhibition of reduced skin elasticity, wrinkle prevention occurred concomitantly with a significant decrease in the curling and three-dimensional tortuosity of dermal elastic fibers. CONCLUSION: Our results indicate that herbal extracts with an ability to inhibit fibroblast-derived elastase may prove to be effective as anti-wrinkling agents, confirming the important role of elastase in UV-B-induced wrinkle formation.     

Effect of skin pH for wrinkle formation on Asian: Korean,Vietnamese and Singaporean

Background Skin pH may be influenced by various factors, such as hydration of stratum corneum, rate of sebum excretion rate, transepidermal water loss (TEWL) and sweating in relation to skin ageing. Objective The aim of this study was to evaluate the correlation between skin pH and wrinkle formation that is directly related to ageing. In addition, we investigated the factors related to skin ageing by comparing the association between skin pH and other skin properties. Methods Three hundred volunteers were selected from three countries: Korea, Vietnam and Singapore. Hydration on the stratum corneum, the rate of sebum excretion rate, melanin index, TEWL and skin temperature on the cheek were measured in a controlled room, and wrinkle length and depth using replicas were compared with skin pH variation. Results The mean and standard deviation of skin surface pH among the three countries were 5.510 ± 0.625. The greatest gap of skin pH that revealed significant differences for skin properties was represented between the Koreans and the Vietnamese. For all three countries, skin hydration, melanin contents, wrinkle length, wrinkle depth and skin temperature were significantly correlated with skin pH. Factors related to skin moisturizing, such as skin hydration, sebum excretion rate and skin temperature, were negatively correlated with skin pH. Wrinkle length and depth decreased as skin pH became more acidic. Conclusions Skin properties displayed various values depending on skin pH. In particular, wrinkle formation significantly decreased as skin pH becomes more acidic. We conclude that skin pH is determined by skin properties, such as skin hydration, sebum excretion rate, melanin concentration, TEWL and skin temperature that affects wrinkle formation.     

Demonstration of UVB-induced synthesis of 1α,25-dihydroxyvitamin D<Subscript>3</Subscript> (calcitriol) in human skin by microdialysis

Cutaneous vitamin D(3) (VD(3)) is generated by UVB-induced photolysis of 7-dehydrocholesterol (7-DHC). VD(3) then undergoes sequential hydroxylation to calcidiol (25-OHD(3)) in the liver and to hormonally active calcitriol (1 alpha,25-(OH)(2)D(3)) in the kidney. Recently, we have described the epidermal VD(3) metabolic pathway by demonstrating the autochthonous formation of calcitriol in cultured keratinocytes. In this study we sought to determine whether photolysis of 7-DHC induced by irradiation of human skin with monochromatic UVB at 300 nm results in epidermal synthesis of calcitriol in vivo. Using a microdialysis technique we demonstrated that UVB irradiation results in a dose- and time-dependent increase in the calcitriol concentration in the extracellular fluid of UVB-irradiated skin. Topical treatment of skin with an ointment containing 2% ketoconazole immediately after irradiation suppressed UVB-induced intraepidermal calcitriol synthesis. This study demonstrates for the first time UVB-triggered synthesis of calcitriol in human skin in vivo. The link between UVB irradiation and synthesis of calcitriol in the skin may be of great importance for regulation of biological processes such as cell growth, differentiation, apoptosis and immunological reactions.     

Fermentable metabolite of Zymomonas mobilis controls collagen reduction in photoaging skin by improving TGF-beta/Smad signaling suppression

Solar ultraviolet (UV) irradiation causes damages on human skin and premature skin aging (photoaging). UV-induced reduction of type I collagen in dermis is widely considered primarily induction of wrinkled appearance of photoaging skin. Type I procollagen synthesis is reduced under UV irradiation by blocking transforming growth factor-beta (TGF-beta)/Smad signaling; more specifically, it is down-regulation of TGF-beta type II receptor (T beta RII). Therefore, preventing UV-induced loss of T beta RII results decreased type I collagen reduction in photoaging skin. Zymomonas mobilis is an alcohol fermentable, gram-negative facultative anaerobic bacterium whose effect on skin tissue is scarcely studied. We investigated the protective effects of fermentable metabolite of Z. mobilis (FM of Z. mobilis) against reduction of type I procollagen synthesis of UV-induced down-regulation of T beta RII in human dermal fibroblasts FM of Z. mobilis was obtained from lyophilization of bacterium culture supernatant. The levels of T beta RII and type I procollagen mRNA in human dermal fibroblasts were measured by quantitative real-time RT-PCR, and T beta RII protein levels were assayed by western blotting. T beta RII, type I procollagen, and type I collagen proteins in human dermal fibroblasts or hairless mouse skin were detected by immunostaining. FM of Z. mobilis inhibited down regulation of T beta RII mRNA, and protein levels in UVB irradiated human dermal fibroblasts consequently recover reduced type I procollagen synthesis. These results indicate UVB irradiation inhibits type I procollagen synthesis by suppression of TGF-beta/Smad signaling pathway, and FM of Z. mobilis has inhibitory effect on UVB-induced reduction of type I procollagen synthesis. While short period UVB irradiation decreased both T beta RII and type I procollagen protein levels in hairless mouse skin, topical application of FM of Z. mobilis prevented this decrease. Wrinkle formation in hairless mouse skin surface was accelerated by continuous 5 month UVB irradiation along with a reduction of type I collagen in the dermis, but this change was prevented by topical application of FM of Z. mobilis. From this experimental data, it is suggested that FM of Z. mobilis is effective for suppression of wrinkle formation in photoaging skin by inhibition of type I procollagen synthesis reduction.     

Hyaluronan minimizes effects of UV irradiation on human keratinocytes

Exposure to ultraviolet (UV) irradiation has detrimental effects on skin accompanied by the increased metabolism of hyaluronan (HA), a linear polysaccharide important for the normal physiological functions of skin. In this study, the modulation of human keratinocyte response to UVB irradiation by HA (970 kDa) was investigated. Immortalized human keratinocytes (HaCaT) were irradiated by a single dose of UVB and immediately treated with HA for 6 and 24 h. The irradiation induced a significant decrease in the gene expression of CD44 and toll-like receptor 2 6 h after irradiation. The expressions of other HA receptors, including toll-like receptor 4 and the receptor for HA-mediated motility, were not detected in either the control or UVB-irradiated or HA-treated HaCaT cells. UVB irradiation induced a significant decrease in the gene expression of HA synthase-2 and hyaluronidase-2 6 h after irradiation. The expressions of HA synthase-3 and hyaluronidase-3 were not significantly modulated by UV irradiation. Interestingly, HA treatment did not significantly modulate any of these effects. In contrast, HA significantly suppressed UVB-induced pro-inflammatory cytokine release including interleukin-6 and interleukin-8. Similarly, HA treatment reduced the UVB-mediated production of transforming growth factor β1. HA treatment also significantly reduced the UV irradiation-mediated release of soluble CD44 into the media. Finally, HA partially, but significantly, suppressed the UVB-induced decrease in cell viability. Data indicate that HA had significant protective effects for HaCaT cells against UVB irradiation.     

Ovariectomy is sufficient to accelerate spontaneous skin ageing and to stimulate ultraviolet irradiation-induced photoageing of murine skin

Background: Wrinkling and sagging of the skin during photoageing is physiologically associated with diminished elasticity, which can be attributed to increased fibroblast-derived elastase activity. This degrades the dermal elastic fibres needed to maintain the three-dimensional structure of the skin. We previously reported that ovariectomy accelerates ultraviolet (UV)B-induced wrinkle formation in rat hind limb skin by altering the three-dimensional structure of elastic fibres. OBJECTIVES: In this study, we used hairless mice to assess the effects of ovariectomy with or without chronic UVA or UVB radiation on sagging and wrinkling of skin, on the elasticity of skin, as well as on matrix metalloproteinase activities in the skin. METHODS: Ovariectomies or sham operations were performed on 6-week-old female ICR/HR hairless mice. RESULTS: Even in the ovariectomy group without UV irradiation, the skin elasticity was significantly decreased during the 3-13 weeks after ovariectomy, which was accompanied by a significant increase in elastase activity in the skin. After UVA or UVB irradiation, skin elasticity was significantly decreased to a greater extent in the ovariectomy group than in the sham operation group, and this was accompanied by a reciprocal increase in elastase activity but not in the activities of collagenases I or IV in the skin. Consistent with the decreased skin elasticity, UVA irradiation for 12 weeks elicited more marked sagging in the ovariectomy group than in the sham operation group. UVB irradiation for 12 weeks also induced more marked wrinkle formation in the ovariectomy group than in the sham operation group. CONCLUSIONS: These results suggest that ovariectomy alone is sufficient to accelerate skin ageing and to increase UV sensitivity, which results in the further deterioration of the skin and photoageing, and may account for the accelerated skin ageing seen in postmenopausal women.     

P38 and JNK signal pathways are involved in the regulation of phlorizin against UVB‐induced skin damage

Phlorizin is well known to inhibit sodium/glucose cotransporters in the kidney and intestine for the treatment of diabetes, obesity and stress hyperglycaemia. However, the effects of phlorizin against ultraviolet B (UVB) irradiation and its molecular mechanism are still unknown. We examined the effects of phlorizin on skin keratinocyte apoptosis, reactive oxygen species (ROS) production, pro‐inflammatory responses after UVB irradiation and the changes of some signal molecules by in vitro and in vivo assay. We observed that phlorizin pretreatments inhibited HaCaT cell apoptosis and overproduction of ROS induced by UVB. Phlorizin also decreased the expression of UVB‐induced pro‐inflammatory cytokines, such as interleukin‐1 beta (IL‐1β), interleukin‐6 (IL‐6) and interleukin‐8 (IL‐8) at the mRNA level. Topical application of phlorizin on UVB‐exposed skin of nude mice prevented the formation of scaly skin and erythema, inhibited the increase of epidermal thickness and reduced acute inflammation infiltration in skin. Additionally, PCR, Western blot and immunohistochemical data showed that phlorizin reversed the overexpression of cyclooxygenase‐2 (Cox‐2) induced by UVB irradiation both in vitro and in vivo. The activation of p38 and JNK mitogen‐activated protein kinases (MAPK) after UVB irradiation was also inhibited by phlorizin. These findings suggest that phlorizin is effective in protecting skin against UVB‐induced skin damage by decreasing ROS overproduction, Cox‐2 expression and the subsequent excessive inflammation reactions. It seemed that p38 and JNK MAPK signal pathways are involved in the regulation of the protective function of phlorizin.