Possible involvement of gelatinases in basement membrane damage and wrinkle formation in chronically ultraviolet B-exposed hairless mouse

Coffea arabica extract and its constituents prevent photoaging by suppressing MMPs expression and MAP kinase pathway

UV is a potent factor in skin photoaging and photocarcinogenesis. Therefore, investigating the inhibiting mechanisms of photoaging would be useful to enable development of agents to slow down the aging process. UV-irradiation increased metalloproteinase (MMP)-1, -3, and -9 and then causes collagen and elastin degradation, leading to the formation of coarse wrinkles and sagging skin. Polyphenols, a group of compounds, possessing a variety of biological activities including inhibition of MMP-1 and elastase, are widely distributed in plants including Coffea arabica. In this study, Coffea arabica leaves extract (CAE), its hydrolysates (CAH), chlororgenic acid and caffeic acid, are studied for their anti-photoaging effect. Coffea arabica leaves were extracted with methanol, and the extract was hydrolyzed with different concentrations of hydrochloric acid. The various concentrations of CAE, CAH, chlororgenic acid and caffeic acid were subject to MMPs and elastase inhibition tests. The fibroblast was used for collagen synthesis and MMP-1, -3, -9 inhibition tests on herbal extracts. The results showed that CAE stimulated type I procollagen expression, inhibited MMP-1, -3, -9 expression and inhibited the phosphorylation of JNK, ERK and p38. The results suggest that CAE can prevent photo-damage in skin through inhibiting MMP expression and MAP kinase pathway.

Mechanics of wrinkle formation: micromechanical analysis of skin deformation during wrinkle formation in ultraviolet-irradiated mice

BACKGROUND/PURPOSE

The mechanical aspects of wrinkle formation were studied in the dorsal skin of hairless mice.

METHODS

Wrinkles were induced by irradiating with ultraviolet (UV) B for 10 weeks, while observing skin deformation during wrinkle formation. Changes in skin dimensions were also observed during the specimen excision process. Wrinkle depth and interval were measured before and after removal of the cutaneous muscle layer. Local deformation of wrinkled skin during uniaxial stretch was also measured. Changes in curvature of skin specimens upon muscle layer removal were then observed to determine the force balance in skin layers.

RESULTS

The skin showed spontaneous contraction in response to UV irradiation. Wrinkled skin showed a marked decrease in the wrinkle depth and a slight increase in wrinkle interval following muscle layer removal, a peculiar mechanical response that cannot be explained by homogeneous deformation of the skin. This response was due to compressive deformations of dermal tissue caused by the muscle layer and concentrated at valleys of the wrinkles. Curvature measurements indicated that the muscle layer compressed the dermal tissue predominantly in the craniocaudal direction. Morphological observations showed that the wrinkles coincided with rows of pores and sulci cutis, where the structural stiffness of the horny layer was relatively low. The horny layer showed significant thickening.

CONCLUSION

Taken together, we propose the following hypothetical mechanisms of wrinkle formation during UV irradiation: spontaneous contraction of the dermis while maintaining or increasing the epidermal area induces buckling of the epidermis into the dermis at mechanically weak lines, namely, the rows of pores and sulci cutis, and buckling may be amplified by the axial compression of the dermis by the muscle layer.

Prevention of UV-induced skin damages by 11,14,17-eicosatrienoic acid in hairless mice in vivo

Polyunsaturated fatty acids (PUFAs) are known to play important roles in various physiological and pathological processes. Recent studies have shown that some omega-3 (omega-3) PUFAs, such as eicosapentaenoic acid (EPA) and dodecahexaenoic acid (DHA), have protective effects on acute and chronic UV-induced changes. However, the effects of other omega-3 PUFAs including 11,14,17-eicosatrienoic acid (20:3) (ETA) on UV-induced skin damages are poorly understood. In this study, we investigated the cutaneous photoprotective effects of ETA in hairless mice in vivo. Female HR-1 hairless mice were topically treated with vehicle (ethanol:polyethylene glycol=30:70) only, 0.1% ETA, or 1% ETA once a day for 3 successive days after one time UV irradiation (200 mJ/cm(2)) on dorsal skins. Skin biopsy was carried out on the fourth day (72 hr after UV irradiation). We found that topical treatment with ETA attenuated UV-induced epidermal and dermal thickness and infiltration of inflammatory cells, and impairment of skin barrier function. In addition, ETA suppressed the expression of IL-1beta, COX-2, and MMP-13 induced by UV irradiation. Our results show that the topical application of ETA protects against UV-induced skin damage in hairless mice and suggest that ETA can be a potential agent for preventing and/or treating UV-induced inflammation and photoaging.

Increased oxygen tension attenuates acute ultraviolet-B-induced skin angiogenesis and wrinkle formation

Acute ultraviolet (UV)-B irradiation causes skin wrinkle formation associated with hyperplasia of cutaneous blood vessels. This study reports that increased dermal oxygen tension attenuates acute UVB-induced angiogenesis and wrinkle formation. Twenty-four hairless mice (HOS:HR-1) were assigned to 3 groups: 1) control group, 2) UVB-irradiated (UVB) group, and 3) UVB-irradiated and hyperoxia-exposed (UVB+HO) group. The backs of the mice were exposed to UVB irradiation 3 times per week for a 5-wk period. To increase dermal oxygen tension, the mice were exposed to hyperoxia (90% oxygen) for 2 h immediately after each UVB irradiation. Hyperoxic exposure increased dermal oxygen tension by about 10 times compared with the control level. Degree of wrinkle formation and epidermal thickness increased significantly after a 5-wk UVB-irradiation period, whereas hyperoxic exposure attenuated these increases. Tissue adenosine triphosphate concentration and angiogenesis increased significantly only in the UVB group compared with the control group. Although the expression of hypoxia inducible factor-1alpha mRNA, a key molecule for angiogenesis, increased significantly in the UVB and UVB+HO groups compared with the control group, the protein level increased significantly only in the UVB group. The activity of matrix metalloproteinase-2 and -9, critical molecules for angiogenesis, did not increase in the UVB and UVB+HO groups compared with the control group. Active type 1 collagenase activity and soluble collagen content in all of the groups were roughly similar. These results suggest that increased dermal oxygen tension attenuates angiogenesis and wrinkle formation following acute UVB irradiation.

Anti-photoaging and photoprotective compounds derived from marine organisms

Marine organisms form a prominent component of the oceanic population, which significantly contribute in the production of cosmeceutical and pharmaceutical molecules with biologically efficient moieties. In addition to the molecules of various biological activities like anti-bacterial, anti-cancerous, anti-inflammatory and anti-oxidative etc., these organisms also produce potential photoprotective or anti-photoaging agents, which are attracting present day researchers. Continuous exposure to UV irradiation (both UV-A and UV-B) leads to the skin cancer and other photoaging complications, which are typically mediated by the reactive oxygen species (ROS), generated in the oxidative pathways. Many of the anti-oxidative and anti-photoaging compounds have been identified previously, which work efficiently against photodamage of the skin. Recently, marine originated photoprotective or anti-photoaging behavior was observed in the methanol extracts of Corallina pilulifera (CPM). These extracts were found to exert potent antioxidant activity and protective effect on UV-A-induced oxidative stress in human dermal fibroblast (HDF) cells by protecting DNA and also by inhibiting matrix metalloproteinases (MMPs), a key component in photoaging of the skin due to exposure to UV-A. The present review depicts various other photoprotective compounds from algae and other marine sources for further elaborative research and their probable use in cosmeceutical and pharmaceutical industries.

Myricetin suppresses UVB-induced wrinkle formation and MMP-9 expression by inhibiting Raf

Chronic exposure to solar ultraviolet (UV) light causes skin photoaging. Many studies have shown that naturally occurring phytochemicals have anti-photoaging effects, but their direct target molecule(s) and mechanism(s) remain unclear. We found that myricetin, a major flavonoid in berries and red wine, inhibited wrinkle formation in mouse skin induced by chronic UVB irradiation (0.18J/cm(2), 3 days/week for 15 weeks). Myricetin treatment reduced UVB-induced epidermal thickening of mouse skin and also suppressed UVB-induced matrix metalloproteinase-9 (MMP-9) protein expression and enzyme activity. Myricetin appeared to exert its anti-aging effects by suppressing UVB-induced Raf kinase activity and subsequent attenuation of UVB-induced phosphorylation of MEK and ERK in mouse skin. In vitro and in vivo pull-down assays revealed that myricetin bound with Raf in an ATP-noncompetitive manner. Overall, these results indicate that myricetin exerts potent anti-photoaging activity by regulating MMP-9 expression through the suppression of Raf kinase activity.

Effects of a turmeric extract (Curcuma longa) on chronic ultraviolet B irradiation-induced skin damage in melanin-possessing hairless mice

Turmeric (the rhizomes of Curcuma longa L., Zingiberacease) is widely used as a dietary pigment and spice, and has been traditionally used for the treatment of inflammation, skin wounds and hepatic disorders in Ayurvedic, Unani and Chinese medicine. Although the topical application or oral administration of turmeric is used to improve skin trouble, there is no evidence to support this effect. The aim of this study was to clarify whether turmeric prevents chronic ultraviolet B (UVB)-irradiated skin damage. We examined the effects of a turmeric extract on skin damage including changes in skin thickness and elasticity, pigmentation and wrinkling caused by long-term, low-dose ultraviolet B irradiation in melanin-possessing hairless mice. The extract (at 300 or 1000 mg/kg, twice daily) prevented an increase in skin thickness and a reduction in skin elasticity induced by chronic UVB exposure. It also prevented the formation of wrinkles and melanin (at 1000 mg/kg, twice daily) as well as increases in the diameter and length of skin blood vessels and in the expression of matrix metalloproteinase-2 (MMP-2). Prevention of UVB-induced skin aging by turmeric may be due to the inhibition of increases in MMP-2 expression caused by chronic irradiation.

Olive leaf extract and its main component oleuropein prevent chronic ultraviolet B radiation-induced skin damage and carcinogenesis in hairless mice

Chronic exposure to solar UV radiation damages skin, increasing its thickness and reducing its elasticity, and causes skin cancer. Our aim in this study was to examine the effects of an olive leaf extract and its component oleuropein on skin damage and the incidence of skin tumors caused by long-term UVB irradiation in hairless mice. Male hairless mice (5 wk old) were divided into 6 groups, including a non-UVB group, a vehicle-treated UVB group (control), 2 olive leaf extract-treated UVB groups, and 2 oleuropein-treated UVB groups. Five groups were UVB irradiated (36-180 mJ/cm(2)) 3 times each week for 30 wk and skin thickness and elasticity after UVB irradiation were measured every week. Olive leaf extract (300 and 1000 mg/kg) and oleuropein (10 and 25 mg/kg) were administered orally twice daily every day for 30 wk. The extract and oleuropein significantly inhibited increases in skin thickness and reductions in skin elasticity, and skin carcinogenesis and tumor growth. Furthermore, they prevented increases in the expression of matrix metalloproteinase (MMP)-2, MMP-9, and MMP-13 as well as in levels of vascular endothelial growth factor (VEGF) and cyclooxygenase-2 (COX-2) in the skin. Based on histological evaluation, they prevented increases in the expression of Ki-67 and CD31-positive cells induced by the irradiation. These results suggest that the preventative effects of the olive leaf extract and oleuropein on chronic UVB-induced skin damage and carcinogenesis and tumor growth may be due to inhibition of the expression of VEGF, MMP-2, MMP-9, and MMP-13 through a reduction in COX-2 levels.

14-3-3epsilon protein increases matrix metalloproteinase-2 gene expression via p38 MAPK signaling in NIH3T3 fibroblast cells

One of the 14-3-3 protein isoforms, 14-3-3epsilon, was previously shown to be increased during skin aging. We suggest here a possible role for the 14-3-3epsilon protein in skin aging by providing evidence that 14-3-3epsilon increases the expression of the matrix-metalloproteinase (MMP)-2 gene in NIH3T3 fibroblast cells. Expression of the 14-3-3epsilon gene in NIH3T3 cells primarily up-regulated the expression of the MMP-2 gene at the transcriptional level by inducing specific DNA binding proteins bound to an upstream region of the MMP-2 promoter from -1,629 to -1,612. Inhibition of endogenous 14-3-3epsilon gene expression by RNA interference also decreased endogenous MMP-2 gene expression. Furthermore, up-regulation of the MMP-2 gene by 14-3-3epsilon was suppressed by expression of a dominant-negative mutant of p38 MAP kinase. These findings strongly suggest that increased expression of 14-3-3epsilon contributes to remodeling of extracellular matrix in skin through increasing MMP-2 gene expression via p38 MAP kinase signaling.

Coenzyme Q10 protects against oxidative stress-induced cell death and enhances the synthesis of basement membrane components in dermal and epidermal cells

Coenzyme Q10 (CoQ10), which has both energizing and anti-oxidative effects, is also reported to have antiaging action, e.g., reducing the area of facial wrinkles. However, the mechanism of its anti-aging activity is not fully established. Here, we examined the effect of CoQ10 on human dermal and epidermal cells. CoQ10 promoted proliferation of fibroblasts but not keratinocytes. It also accelerated production of basement membrane components, i.e., laminin 332 and type IV and VII collagens, in keratinocytes and fibroblasts, respectively; however, it had no effect on type I collagen production in fibroblasts. CoQ10 also showed protective effects against cell death induced by several reactive oxygen species in keratinocytes, but only when its cellular absorption was enhanced by pretreatment of the cells with highly CoQ10-loaded serum. These results suggest that protection of epidermis against oxidative stress and enhancement of production of epidermal basement membrane components may be involved in the antiaging properties of CoQ10 in skin.

Possible involvement of basement membrane damage in skin photoaging

Aging of sun-exposed skin is accelerated by three major environmental factors: UV radiation, dryness, and oxidation. UV radiation exposure is the most influential factor in skin aging (so-called photoaging). To find ways to protect against damage caused by UV exposure and to delay photoaging, we studied internal changes of sun-exposed skin compared with those of sun-protected skin. We found that the basement membrane (BM) at the dermal-epidermal junction (DEJ) of sun-exposed skin becomes damaged and multilayered and partly disrupted compared with that of sun-protected skin. BM plays important roles in maintaining a healthy epidermis and dermis, and repeated damage destabilizes the skin, accelerating the aging process. Matrix metalloproteinases (MMPs) and urinary plasminogen activator are increased in UV-irradiated skin. MMPs are detected in the cornified layer in sun-exposed skin, but not in sun-protected skin. Using skin-equivalent models, we found that MMPs and plasmin cause BM damage and that the reconstruction of BM is enhanced by inhibiting these proteinases, as well as by increasing the synthesis of BM components. Enhancement of BM repair mechanisms may be a useful strategy in retarding photoaging.Journal of Investigative Dermatology Symposium Proceedings (2009) 14, 2-7; doi:10.1038/jidsymp.2009.5.

Relationship between dermal birefringence and the skin surface roughness of photoaged human skin

The dermal degeneration accompanying photoaging is considered to promote skin roughness features such as wrinkles. Our previous study demonstrated that polarization-sensitive spectral domain optical coherence tomography (PS-SD-OCT) enabled noninvasive three-dimensional evaluation of the dermal degeneration of photoaged skin as a change in dermal birefringence, mainly due to collagenous structures. Our purpose is to examine the relationship between dermal birefringence and elasticity and the skin morphology in the eye corner area using PS-SD-OCT. Nineteen healthy male subjects in their seventees were recruited as subjects. A transverse dermal birefringence map, automatically produced by the algorithm, did not show localized changes in the dermal birefringence in the part of the main horizontal wrinkle. The averaged upper dermal birefringence, however, showed depth-dependent correlation with the parameters of skin roughness significantly, suggesting that solar elastosis is a major factor for the progress of wrinkles. Age-dependent parameters of skin elasticity measured with Cutometer did not correlate with the parameters. These results suggest that the analysis of dermal birefringence using PS-SD-OCT enables the evaluation of photoaging-dependent upper dermal degeneration related to the change of skin roughness.

Activation of phosphatidylinositol 3-kinase is required for tumor necrosis factor-alpha-induced upregulation of matrix metalloproteinase-9: its direct inhibition by quercetin

Matrix metalloproteinases (MMPs) are involved in various skin disorders, including photoaging, dermatitis, and tumorigenesis. Tumor necrosis factor (TNF)-alpha is a key proinflammatory cytokine that acts to provoke inflammation, proliferation, and tumorigenesis. The present study investigated the possible inhibitory effects of red wine polyphenols on TNF-alpha-induced upregulation of MMP-9 and on the migratory phenotype of JB6 P+ mouse epidermal (JB6 P+) cells. Red wine extract (RWE) and quercetin, which is a major flavonoid present in red wine, inhibited significantly the TNF-alpha-induced upregulation of MMP-9 and cell migration, whereas resveratrol did not have significant inhibitory effects. The inhibitory effects of RWE and quercetin were mediated by suppression of the phosphorylation of Akt and the transactivation of activator protein-1 and nuclear factor-kappaB, as determined by Western blotting and luciferase assays, respectively. Aside from Akt, quercetin had no effect on the phosphorylation of other mitogen-activated protein kinases. Direct kinase assay data revealed that RWE and quercetin inhibited phosphatidylinositol 3-kinase (PI3K) activity. The results of direct and cell-based pull-down assays demonstrated that RWE and quercetin bound to PI3K, resulting in the inhibition of PI3K activity. Using chemical inhibitors, it was confirmed that the PI3K-dependent Akt pathway was involved in TNF-alpha-induced MMP-9 upregulation and migration in JB6 P+ cells. Collectively, these results indicate that TNF-alpha-induced MMP-9 upregulation and the migratory phenotype are associated with the PI3K/Akt pathway, and that these effects are inhibited strongly by RWE and quercetin.

Observation of dermal collagen fiber in wrinkled skin using polarization-resolved second-harmonic-generation microscopy

Optical probe methods for in vivo assessments of cutaneous photoaging are necessary in fields such as anti-aging dermatology and skin cosmetic development. We investigated the relation between wrinkle direction and collagen orientation in ultraviolet-B-exposed (UVB-exposed) skin using polarization-resolved second-harmonic-generation (SHG) microscopy. A polarization anisotropic image of the SHG light indicated that wrinkle direction in UVB-exposed skin is predominantly parallel to the orientation of dermal collagen fibers. Furthermore, collagen orientation in post-UVB-exposed skin with few wrinkles changed from that of UVB-exposed wrinkled skin to that of no-UVB-exposed skin. The method proposed has the potential to become a powerful non-invasive tool for assessment of cutaneous photoaging.

Mechanistic effects of long-term ultraviolet B irradiation induce epidermal and dermal changes in human skin xenografts

UVB irradiation has been reported to induce photoaging and suppress systemic immune function that could lead to photocarcinogenesis. However, because of the paucity of an UVB-induced photodamaged skin model, precise and temporal mechanism(s) underlying the deleterious effects of long-term UVB exposure on human skin have yet to be delineated. In this study, we established a model using human skin xenografted onto severe combined immunodeficient mice, which were subsequently challenged by repeated UVB irradiation for 6 weeks. Three-dimensional optical image analysis of skin replicas and noninvasive biophysical measurements illustrated a significant increase in skin surface roughness, similar to premature photoaging, and a significant loss of skin elasticity after long-term UVB exposure. Resembling authentically aged skin, UVB-exposed samples exhibited significant increases in epithelial keratins (K6, K16, K17), elastins, and matrix metalloproteinases (MMP-1, MMP-9, MMP-12) as well as degradation of collagens (I, IV, VII). The UVB-induced deterioration of fibrous keratin intermediate filaments was also observed in the stratum corneum. Additionally, similarities in gene expression patterns between our model and chronologically aged skin substantiated the plausible relationship between photodamage and chronological age. Furthermore, severe skin photodamage was observed when neutralizing antibodies against TIMP-1, an endogenous inhibitor of MMPs, were administered during the UVB exposure regimen. Taken together, these findings suggest that our skin xenograft model recapitulates premature photoaged skin and provides a comprehensive tool with which to assess the deleterious effects of UVB irradiation.

Plasmin induces degradation and dysfunction of laminin 332 (laminin 5) and impaired assembly of basement membrane at the dermal-epidermal junction

BACKGROUND

The epidermal basement membrane (BM), located at the dermal-epidermal junction (DEJ), plays important roles not only in adhesion between epidermis and dermis, but also in controlling skin functions. In sun-exposed skin, the BM becomes disrupted and multilayered. In order to explore the impairment of BM assembly, we have used a skin-equivalent (SE) as a model of BM damage and previously clarified the involvement of matrix metalloproteinases (MMPs) in impairment of BM assembly.

OBJECTIVES

In this work, we examined the role of urokinase-type plasminogen activator (uPA) and plasmin in impairment of BM assembly at the DEJ by using the SE, as ultraviolet irradiation to the skin increases uPA as well as MMPs.

METHODS

SEs were used as a model of formation and damage of BM. Human uPA was detected by enzyme-linked immunosorbent assay and zymography, and gelatinases such as MMP-2 and MMP-9 were detected by zymography. Human plasminogen was added at 0.06 micromol L(-1) (about 3% of plasma level) to increase plasmin to a pathological level. N-terminal peptide sequence analysis of plasmin-treated laminin 332 was carried out to identify alpha3, beta3 and gamma2 chains of laminin 332 and their cleavage sites of each chain. Plasmin-treated laminin 332 was analysed in keratinocyte adhesion activity and binding to type VII collagen.

RESULTS

Human uPA was detected in addition to MMP-2 and MMP-9, in conditioned medium of SE. Although the BM was well organized in the presence of an MMP inhibitor alone, the activated plasmin disorganized the BM even in the presence of the inhibitor. The impairment of BM assembly made the epidermis thinner as compared with that of a control cultured in the presence of MMP inhibitor, indicating that the BM affects the polarity and differentiation of the epidermis. The addition of aprotinin, a serine proteinase inhibitor, and tranexamic acid, a uPA-plasmin inhibitor, inhibited the plasmin-induced impairment of BM assembly and facilitated BM reorganization, thereby improving the epidermal structure. N-terminal peptide sequence analysis of plasmin-treated laminin 332 revealed the removal of a 5- or 10-kDa fragment, including the cell adhesion region, from the G3 domain of the alpha3 chain, and the LN domain, which binds to the noncollagenous 1 domain in type VII collagen, from the beta3 chain. Plasmin-treated laminin 332 showed lower keratinocyte adhesion activity and reduced binding to type VII collagen.

CONCLUSIONS

These results suggest that uPA and plasmin are involved in the impairment of BM assembly and epidermal differentiation, and that these effects arise at least partly through direct degradation of laminin 332.

Mechanisms of inhibitory effects of CoQ10 on UVB-induced wrinkle formation in vitro and in vivo

Photodamaged skin exhibits wrinkles, pigmented spots, dryness and tumors. Solar UV radiation induces cyclobutane pyrimidine dimers (CPD) and further produces base oxidation by reactive oxygen species (ROS). ROS are thought to be a major factor to initiate the up-regulation of matrix metalloproteinases (MMPs) in keratinocytes and fibroblasts via activation of receptor proteins on the cell membrane of keratinocytes and fibroblasts, and to degrade fiber components in dermis, leading to wrinkle formation. Coenzyme Q10 (CoQ10) was reported to reduce ROS production and DNA damage triggered by UVA irradiation in human keratinocytes in vitro. Further, CoQ10 was shown to reduce UVA-induced MMPs in cultured human dermal fibroblasts. We speculated that UVB radiation-induced cytokine production in keratinocytes may be inhibited by CoQ10, resulting in the reduction of MMPs in fibroblasts leading to wrinkle reduction. Our in vitro studies showed that UVB-induced IL-6 production of normal human keratinocyte (NHKC) decreased in the presence of CoQ10. Furthermore, MMP-1 production of fibroblasts cultured with the medium containing CoQ10 collected from UVB-irradiated NHKC significantly decreased during 24 h culture. In the clinical trial study, we found that the use of 1% CoQ10 cream for five months reduced wrinkle score grade observed by a dermatologist. Taken together, our results indicate that CoQ10 may inhibit the production of IL-6 which stimulate fibroblasts in dermis by paracrine manner to up-regulate MMPs production, and contribute to protecting dermal fiber components from degradation, leading to rejuvenation of wrinkled skin.

Establishment of a mouse skin model of the lichenification in human chronic eczematous dermatitis

BACKGROUND

Repeated mechanical stresses, such as scratching and rubbing, on a lesional skin area induce a rough skin condition known as lichenification in patients with chronic eczematous dermatitis. For ethical reasons, the pathomechanisms involved are difficult to study, so an animal model is required.

OBJECTIVES

To study the pathomechanisms of the unique rough skin changes seen in chronic eczematous dermatitis, we established a mouse skin model by repeated tape stripping to inflict stratum corneum (SC) barrier disruption. The skin characteristics of the model were investigated biologically, histologically and pharmacologically.

METHODS

Tape stripping was done on mouse back skin three times a week for 4 weeks. The skin changes were studied by obtaining negative replicas, haematoxylin and eosin staining, immunostaining for CD31 and BrdU, and measuring epidermal and cutaneous thickness and skin capacitance. Activities of matrix metalloproteinase (MMP)-2, 9 and urokinase-type plasminogen activator (uPA) in the skin tissues were analysed by zymography. The effects of MMP inhibitor and glycine were assessed.

RESULTS

The repeated tape stripping produced crusting and desquamation at 48 h, followed 1 week later by the formation of shallow furrows, which became much deeper after 4 weeks, appearing as fine and regular wrinkles. The resultant wrinkled skin resembled lichenified skin seen in patients with chronic eczematous dermatitis. Histopathologically, we found acanthosis, hypergranulosis and hyperkeratosis even at 48 h, and the skin was 2.5 times thicker than untreated control skin at 4 weeks. We observed angiogenesis in the upper dermis at 1 and 4 weeks. Skin capacitance, a parameter of SC hydration, displayed consistently low levels throughout the experimental period. Although the dermis was also thickened, the activity of MMP-9 was sharply increased only at 24 and 48 h after tape stripping, declining thereafter to the control level. Topical applications of CGS-27023A (CGS), an MMP inhibitor, failed to suppress this tape-stripping-induced wrinkle formation. In contrast, topical applications of a barrier recovery accelerator, glycine, effectively inhibited the wrinkle formation induced by repeated tape stripping.

CONCLUSIONS

The induction of fine and regular wrinkles by inflicting chronic SC barrier disruption in this model involves mainly epidermal changes, which is in sharp contrast to the mainly dermal changes induced by chronic ultraviolet B irradiation.

Matrix metalloproteinase-19 expression in keratinocytes is repressed by transcription factors Tst-1 and Skn-1a: implications for keratinocyte differentiation

Matrix metalloproteinase-19 (MMP-19), unlike other members of the MMP family, is expressed in basal keratinocytes of intact epidermis whereas keratinocytes in suprabasal and higher epidermal layers express this enzyme only during cutaneous disorders. As the activity of MMP-19 effects proliferation, migration, and adhesion of keratinocytes we examined whether transcription factors involved in keratinocyte differentiation repress the expression of MMP-19. Using luciferase reporter assays, POU transcription factors Tst-1 (Oct-6) and Skn-1a (Oct-11) markedly downregulated the activity of MMP-19 promoter in COS-7 cells and HaCaT keratinocytes. Tst-1 alone was able to inhibit 85% of the promoter activity. Skn-1a exhibited a weak inhibitory effect although it synergistically increased effects of Tst-1. HaCaT cells stably transfected with Tst-1 showed a strong decrease of activity of MMP-19 promoter that correlated with suppression of MMP-19, cytokeratin 14 and 5, decreased cell proliferation, and altered expression of involucrin and loricrin. The expression of MMP-9 was also significantly reduced in Tst-1 expressing keratinocytes. MMP-2 was substantially affected during its activation whereas the expression of MMP-28 was unchanged. Our results suggest that Tst-1 and Skn-1a regulate expression of MMPs in keratinocytes and effect both the expression and activation of these proteolytic enzymes.

Marked improvement induced in photoaged skin of hairless mouse by ER36009, a novel RARgamma-specific retinoid, but not by ER35794, an RXR-selective agonist

BACKGROUND

Photoaging (premature skin aging) results largely from repeated exposure of the skin to ultraviolet (UV) radiation from the sun. Topical all-trans retinoic acid (RA), the only agent that has been approved for the treatment of photoaging, has been shown to reverse this process. In this study, we evaluated the pharmacologic effects of novel synthetic retinoids, ER36009 and ER35794, on murine wrinkles induced by UVB. ER36009 is a specific agonist of retinoic acid receptor (RAR)gamma, the most abundant RAR subtype in the skin, while ER35794 is a potent retinoid X receptor (RXR)-selective agonist.

METHOD

After a 10-week exposure to escalating doses of UVB irradiation, the animals were treated three times per week with ER36009 (0.0001%, 0.00025%, 0.0005%), ER35794 (0.025%, 0.05%, 0.1%), RA (0.05%) or acetone (control) for 3 weeks.

RESULTS

ER36009 exerted a dose-dependent wrinkle-effacing effect, and 0.0005% ER36009-treated skin was significantly different from the control. ER36009 also significantly and dose-dependently increased both epidermal thickness and the area of the dermal repair zone defined by newly synthesized collagen. The effect of 0.0005% ER36009 on photodamaged skin was superior to that of 0.05% RA. In contrast, ER35794 was inactive in this model, though this compound exhibited lower local toxicity than other retinoids.

CONCLUSIONS

These data indicate that RARgamma, but not RXR, plays an important role in the improvement of the signs of photoaging, and so a specific RARgamma agonist might be superior to an RAR pan-agonist for clinical treatment. We conclude that ER36009 is a candidate for a potent anti-skin-aging agent.

Phlorotannins in Ecklonia cava extract inhibit matrix metalloproteinase activity

Matrix metalloproteinase (MMP) inhibitors have been identified as potential therapeutic candidates for metastasis, arthritis, chronic inflammation and wrinkle formation. For the first time here we report a detailed study on the inhibitory effects of phlorotannins in brown algae, Ecklonia cava (EC) on MMP activities in cultured human cell lines. A novel gelatin digestion assay could visualize complete inhibition of bacterial collagenase-1 activity at 20 microg/ml of EC extract during preliminary screening studies. Sensitive fluorometric assay revealed that EC extract can specifically inhibit both MMP-2 and MMP-9 activities significantly (P < 0.001) at 10 microg/ml. In addition, artificially induced activities of MMP-2 and MMP-9 in human dermal fibroblasts and HT1080 cells were inhibited by EC extract in a more or less similar manner to the positive control doxycycline. Even though the expression levels of MMPs differ from one cell type to the other, gelatin zymography clearly revealed that both MMP expression and activity in cells can be inhibited by EC extract. More interestingly, EC extract did not exert any cytotoxic effect even at 100 microg/ml anticipating its potential use as a safe MMP inhibitor.

Non-invasive study of gelatinases in sun-exposed and unexposed healthy human skin based on measurements in stratum corneum

Gelatinases, which belong to the family of matrix metalloproteinases, degrade various components of skin, and may be involved in photoaging, since they are upregulated by low-dose UV exposure to the skin. However, their behavior in healthy human skin is still unclear. In the present study, gelatinases was specifically detected in stratum corneum (SC) of skin from sun-exposed sites, including the face, in healthy humans, but not in SC of skin from unexposed sites. Following experimental UVB irradiation of the abdomen in volunteers, gelatinases were detected in tape-stripped SC from the site for several weeks, and subsequently disappeared. The appearance of gelatinase in SC after a lag time consistent with SC turnover is considered to reflect upregulation of gelatinase expression in keratinocytes in response to UVB-exposure of the skin. A survey of gelatinases in facial SC samples collected by tape-stripping from the cheeks of 100 healthy women revealed that the enzyme was present in 90% of subjects. These results, taken together, suggest that gelatinase is constantly upregulated by sunlight in the facial epidermis of most women during their daily lives, and may be an etiological factor in photoaging, e.g., by promoting wrinkle formation.

Phenolic constituents of Malus doumeri var. formosana in the field of skin care

Plant phenolic compounds isolated from a 70% aqueous acetone extract of the leaves of Malus doumeri A. CHEV. var. formosana (KAWAK. & KOIDZ.) S. S. YING, a type of Taiwanese indigenous plant, were evaluated for potential application in the field of skin care. A phytochemical investigation of the active fractions resulted in the isolation of seven compounds of which the structures were identified by spectroscopic characterization. In the present study, the isolated phenolic compounds were evaluated for their free radical-scavenging activities against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and the superoxide radicals, anti-elastase, and for their anti-matrix metalloproteinase-1 (MMP-1) activity in human skin fibroblast cells. Of these compounds, 3-hydroxyphloridzin (2), 3-hydroxyphloretin (6), and quercetin (7) exhibited the strongest DPPH and superoxide radical-scavenging activities. The IC50 values of these compounds were 9.2, 7.7, and 15.4 microM, respectively, for the DPPH radical, and 25.0, 19.6, and 42.6 microM, respectively, for the superoxide radical. 3-Hydroxyphloridzin (2) and 3-hydroxyphloretin (6) also showed xanthine oxidase inhibitory activity, with IC(50) values of 52.1 and 22.4 muM, respectively. In the test for elastase inhibitory activity, phloretin (5) and 3-hydroxyphloretin (6) were the most potent compounds. Phloretin (5), 3-hydroxyphloretin (6), and quercetin (7) showed better inhibition of MMP-1 production in fibroblast cells. To the best of our knowledge, this is the first time that the active phenolic compounds from M. doumeri var. formosana have been isolated, reported, and described. The above results suggest that the extract of M. doumeri var. formosana containing phenolic compounds could be suitable naturally occurring active constituents for use in anti-aging or cosmetic products.

Automatic characterization and segmentation of human skin using three-dimensional optical coherence tomography

A set of fully automated algorithms that is specialized for analyzing a three-dimensional optical coherence tomography (OCT) volume of human skin is reported. The algorithm set first determines the skin surface of the OCT volume, and a depth-oriented algorithm provides the mean epidermal thickness, distribution map of the epidermis, and a segmented volume of the epidermis. Subsequently, an en face shadowgram is produced by an algorithm to visualize the infundibula in the skin with high contrast. The population and occupation ratio of the infundibula are provided by a histogram-based thresholding algorithm and a distance mapping algorithm. En face OCT slices at constant depths from the sample surface are extracted, and the histogram-based thresholding algorithm is again applied to these slices, yielding a three-dimensional segmented volume of the infundibula. The dermal attenuation coefficient is also calculated from the OCT volume in order to evaluate the skin texture. The algorithm set examines swept-source OCT volumes of the skins of several volunteers, and the results show the high stability, portability and reproducibility of the algorithm.

Matrix metalloproteinase-9 modulates intestinal injury in rats with transmural colitis

Proteolysis and degradation of extracellular matrix by metalloproteinases (MMPs) may contribute to intestinal injury in inflammatory bowel disease. In the present study, we investigated the pathogenic role of gelatinases (MMP-9 and MMP-2) on transmural colonic injury in a rat model of chronic colitis, which was induced by intracolonic instillation of trinitrobenzene sulfonic acid (TNBS). The activity and expression of MMP-2 and MMP-9 were measured in colonic tissue and peripheral neutrophils by fluorescence, zymography, Western blot, or immunohistochemistry at different time-points. Furthermore, myeloperoxidase content in colonic homogenates was analyzed to evaluate inflammation. Finally, morphological changes were assessed following early or delayed administration of CGS-27023-A, a synthetic inhibitor of MMPs. We found that the induction of colitis led to a significant up-regulation in tissue gelatinase concentration, whereas no changes in collagenase activity were observed. In addition, up-regulation of pro-MMP-9, but not of pro-MMP-2, was found on Days 7 and 10 following the induction of colitis. Furthermore, transmural MMP-9 was detected by immunofluorescent staining in the inflamed tissue. Consistent with tissue samples, neutrophils from colitic rats showed a significantly increased activity of pro-MMP-9. Finally, early but not delayed treatment with CGS-27023-A attenuated colonic mucosal injury in rats with TNBS-induced colitis. In conclusion, up-regulation of MMP-9 in peripheral and colonic neutrophils modulates transmural colonic injury in rats with TNBS-induced colitis.

Chemical Peeling by SA-PEG Remodels Photo-damaged Skin: Suppressing p53 Expression and Normalizing Keratinocyte Differentiation

Chemical peeling with salicylic acid in polyethylene glycol vehicle (SA-PEG), which specifically acts on the stratum corneum, suppresses the development of skin tumors in UVB-irradiated hairless mice. To elucidate the mechanism through which chemical peeling with SA-PEG suppresses skin tumor development, the effects of chemical peeling on photodamaged keratinocytes and cornified envelopes (CEs) were evaluated in vivo. Among UVB-irradiated hairless mice, the structural atypia and expression of p53 protein in keratinocytes induced by UVB irradiation were intensely suppressed in the SA-PEG-treated mice 28 days after the start of weekly SA-PEG treatments when compared to that in the control UVB-irradiated mice. Incomplete expression of filaggrin and loricrin in keratinocytes from the control mice was also improved in keratinocytes from the SA-PEG-treated mice. In photo-exposed human facial skin, immature CEs were replaced with mature CEs 4 weeks after treatment with SA-PEG. Restoration of photodamaged stratum corneum by treatment with SA-PEG, which may affect remodeling of the structural environment of the keratinocytes, involved the normalization of keratinocyte differentiation and suppression of skin tumor development. These results suggest that the stratum corneum plays a protective role against carcinogenesis, and provide a novel strategy for the prevention of photo-induced skin tumors.

In Vitro and In Vivo Inhibition of Skin Matrix Metalloproteinases by Pothomorphe umbellata Root Extract

Exposure to UV radiation up-regulates the synthesis of matrix metalloproteinases (MMPs), a group of matrix-degrading enzymes. MMPs are regarded as promising therapeutic targets and the development of effective inhibitors is an important research focus. The plant Pothomorphe umbellata has been shown to exert a potent antioxidant activity on the skin and to delay the onset and reduce the incidence of UVB-induced chronic skin damage. The aim of the present study was to determine the effect of P. umbellata ethanolic root extract on MMP-2 and MMP-9. The in vitro inhibition of MMP-2 and MMP-9 was measured by gelatin zymography in the presence of different concentrations of P. umbellata extract, as well as in the presence of its isolated active principle 4-nerolidylcatechol (4-NC). The inhibitory effect of the P. umbellata extract was stronger than that of 4-NC. Gelatin zymography and histological analysis revealed that P. umbellata was able to inhibit constitutive MMP-9 activity in vivo in mice sacrificed 2 h after UVB irradiation. The intensity of the MMP-2 band was unchanged. Our data contribute to the elucidation of the mechanism of prevention of photoaging by P. umbellata and may provide a rational basis for the use of this plant in prophylaxis against and treatment of skin cancer.