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.     

Selective inhibition of skin fibroblast elastase elicits a concentration-dependent prevention of ultraviolet B-induced wrinkle formation

We previously reported that wrinkle formation in the skin following long-term ultraviolet B irradiation is accompanied by decreases in skin elasticity and the curling of elastic fibers in the dermis. We further showed that wrinkles could be repaired by treatment with retinoic acid and that this was concomitant with the recovery of skin elasticity ascribed to the repair of damaged elastic fibers. Those studies suggested that decreasing the tortuosity of dermal elastic fibers is an important factor involved in inhibiting or repairing wrinkle formation. Therefore, it is of particular interest to determine whether the inhibition of elastase activity in vivo would prevent the damage of dermal elastic fibers and might abolish wrinkle formation associated with the loss of skin elasticity. Because the major elastase in the skin under noninflammatory conditions is skin fibroblast elastase, we used a specific inhibitor of that enzyme to assess its biologic role in wrinkle formation. The hind limb skins of Sprague-Dawley rats were irradiated with ultraviolet B at a suberythemal dose three times a week for 6 wk. During that period, 0.1-10.0 mM N-phenetylphosphonyl-leucyl-tryptophane, an inhibitor of skin fibroblast elastase, was applied topically five times a week. N-phenetylphosphonyl-leucyl-tryptophane application at concentrations of 0.1-1.0 mM abolished wrinkle formation in a concentration-dependent manner, with a peak for inhibition at 1.0 mM. This inhibition was accompanied by a continued low tortuosity of dermal elastic fibers and a maintenance of skin elasticity. Measurement of elastase activity after 6 wk of ultraviolet B irradiation demonstrated that whereas phosphoramidon-sensitive elastase activity was significantly enhanced in the ultraviolet B-exposed skin, there was no significant increase in that activity in the ultraviolet B-exposed, N-phenetylphosphonyl-leucyl-tryptophane-treated skin. These findings suggest that skin fibroblast elastase plays an essential part in the degeneration and/or tortuosity of elastic fibers induced by cumulative ultraviolet B irradiation.     

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.     

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.     

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.     

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.     

Epidermal changes caused by chronic low-dose UV irradiation induce wrinkle formation in hairless mouse

To investigate the effects of chronic low-dose UV irradiation on the skin, hairless mice were irradiated with a 1/3 minimal erythemal dose (MED) of UV. We examined the relationship between visible changes and skin damage in the dermis and epidermis. Hairless mice were irradiated with UVB (20 mJ/cm2) and UVA (14 J/cm2) three times a week for 10 weeks, followed by a 24-week non-irradiation period. Visible fine wrinkling was present after 4 weeks of irradiation, and the wrinkling progressively worsened throughout the period of irradiation. The wrinkles remained after irradiation was discontinued. In dermal components, no significant histological changes in the collagen fibers and elastic fibers were found, and the amount of hydroxyproline was also not changed. Thus, in the epidermis, there was a significant increase in the number of stratum corneum layers and the terminal-differentiation marker, filaggrin, positive cells. The intensity of staining for the differentiation marker, keratin 1, was reduced. These changes were accompanied by wrinkle formation, and remained after discontinuance of irradiation. These findings suggested that chronic low-dose UV irradiation induces structural and quantitative changes in the epidermis as a result of keratinization impairment, and that this damage in the epidermis is an important causative factor in wrinkle formation.     

Loss of elastic fibers causes skin wrinkles in sun-damaged human skin

BACKGROUND: Although wrinkling is the most obvious sign of aged skin, the detailed pathomechanism of wrinkle development has not been elucidated. OBJECTIVES: In this study, we investigated the role of elastic fibers in the formation of skin wrinkles. METHODS: Loss of elastic fibers was measured quantitatively in the facial skins of subjects representing seven decades, and then compared with wrinkle severities. We also investigated whether topical retinoic acid treatment to photoaged human skin can restore destroyed elastic fiber, and the correlation between wrinkle improvement with increase in elastic fibers in RA-treated facial skin. RESULTS: We found a significant correlation between decreases in the length, width, number and total area of oxytalan fibers and wrinkle severity. Furthermore, we found that topical application of retinoic acid (0.025%) to chronically photodamaged skin regenerated and restored elastic fibers, and that there was a significant positive correlation between the amount of newly regenerated elastic fiber and the wrinkle improvement caused by retinoic acid. CONCLUSIONS: Our results provide an objective insight into the role of elastic fibers in skin wrinkle formation by providing a quantitative correlation between changes in oxytalan fibers and the severity of skin wrinkling.     

All-trans retinoic acid promotes the repair of tortuosity of elastic fibres in rat skin

To elucidate the repair effects of all-trans retinoic acid (t-RA) on ultraviolet (UV)-induced tortuosity of elastic fibres in rat skin, the hind limbs of Sprague-Dawley rats were irradiated at a suberythemal dose of UV (three times/week for 6 weeks) and 0.025% t-RA in ethanol was applied topically five times/week for 6 weeks. The three-dimensional arrangement of elastic fibres with special reference to their linearity was quantified by image analysis using a scanning electron microscope following a combination of intravascular resin injection and selective digestion using formic acid. When t-RA was topically applied for 6 weeks on wrinkles formed by 6 weeks' exposure of the skin of rat hind limbs to UV radiation, the wrinkles disappeared to control levels, concomitant with an improvement in skin elasticity. The linearity of the elastic fibres was significantly (P < 0.01) increased compared with age-matched UV-irradiated controls. These findings suggest that the degeneration and deposition of elastic fibres accompanied by an increase in their linearity is involved in the process of wrinkle repair by topical application of t-RA.     

Fibrillin-rich microfibrils are reduced in photoaged skin. Distribution at the dermal-epidermal junction

Chronic sun exposure results in photoaged skin with deep coarse wrinkles and loss of elasticity. We have examined the distribution and abundance of fibrillin-rich microfibrils, key structural components of the elastic fiber network, in photoaged and photoprotected skin. Punch biopsies taken from photoaged forearm and from photoprotected hip and upper inner arm of 16 subjects with a clinical range of photoaging were examined for fibrillin-1 and fibrillin-2 expression and microfibril distribution. In situ hybridization revealed decreased fibrillin-1 mRNA but unchanged fibrillin-2 mRNA levels in severely photoaged forearm biopsies relative to photoprotected dermal sites. An immunohistochemical approach demonstrated that microfibrils at the dermal-epidermal junction were significantly reduced in moderate to severely photoaged forearm skin. Confocal microscopy revealed that the papillary dermal microfibrillar network was truncated and depleted in photoaged skin. These studies highlight that the fibrillin-rich microfibrillar network associated with the upper dermis undergoes extensive remodeling following solar irradiation. These changes may contribute to the clinical features of photoaging, such as wrinkle formation and loss of elasticity.     

Extracts from Glycine max (soybean) induce elastin synthesis and inhibit elastase activity

Abstract:  Elastic fibres are essential extracellular matrix components of the skin, contributing to its resilience and elasticity. In the course of skin ageing, elastin synthesis is reduced, and elastase activity is accelerated, resulting in skin sagging and reduced skin elasticity. Our studies show that non-denatured Glycine max (soybean) extracts induced elastin promoter activity, inhibited elastase activity and protected elastic fibres from degradation by exogenous elastases in vitro . Mouse and swine skins topically treated with soybean extracts showed enhanced elastic fibre network and increased desmosine content. Elastin expression was also augmented in human skin transplanted onto SCID mice in response to soy treatment. These data suggest that non-denatured soybean extracts may be used as skin care agents to reduce the signs of skin ageing.     

Skin ageing: clinical and histopathologic study of permanent and reducible wrinkles

Wrinkles are modifications of the skin associated with cutaneous ageing and develop preferentially on sun-exposed skin. The aim of the study was to analyse the clinicopathological features of wrinkles, among the different types of skin relief modifications. Despite its importance in dermato-cosmetology and skin ageing, few studies have been specifically devoted to wrinkles. In the present study, we analyzed the histological features of the pre-auricular wrinkle compared to retro-auricular skin, obtained from sixteen patients undergoing facial surgery; skin samples were immediately processed for routine histology and histochemical staining. Four types of skin depressions could be defined according to their depth: folds, permanent wrinkles, reducible wrinkles and skin micro-relief. Two different types of pre-auricular wrinkles were observed: (i) permanent wrinkles which were conserved after sampling and, (ii) reducible wrinkles which required in vivo staining to be visible at histology. Histological analysis of the epidermis and dermis of the skin forming the pre-auricular wrinkle revealed a normal skin morphology, identical to that of the skin immediately adjacent to the wrinkle. This was particularly striking for the reducible wrinkles which could not be individualized in the absence of in vivo staining. Both types of wrinkles comprised skin modifications observed in sun-exposed skin, however, in the upper dermis, permanent wrinkles showed a more pronounced accumulation of basophilic fibers, i.e. actinic elastosis, than reducible wrinkles did. These data suggest that the development of wrinkles could be secondary to actinic elastosis and to the disappearance of microfibrils and collagen fibers at the dermal-epidermal junction.     

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.     

Accumulation of elafin in actinic elastosis of sun-damaged skin: elafin binds to elastin and prevents elastolytic degradation

Elafin has a primary structure with two functional domains; a transglutaminase substrate domain at the N-terminus and a protease inhibitor domain at the C-terminus. Elafin expression has so far been reported only for epithelial tissues. Accumulation of elafin was immunohistochemically detected in the actinic elastosis of sun-damaged skin. Exposure of normal skin to UVA induced elafin expression that colocalized with elastic fibers. Incubation of synthetic transglutaminase substrate domain of elafin and elastin molecules in the presence of tissue transglutaminase in vitro resulted in the formation of a higher molecular complex on SDS-PAGE. Elafin expression was not detected in normal cultured skin fibroblasts, but was induced by UVA irradiation at both messenger RNA and protein levels. When radiolabeled insoluble elastin was incubated with recombinant full-length elafin and tissue transglutaminase, insoluble elastin became more resistant to neutrophil elastase digestion. These results indicate that (1) dermal fibroblasts potentially express elafin on UV irradiation, (2) UV-mediated elafin interacts with elastin, and (3) the elafin-elastin complex protects elastic fibers from elastolytic degradation, leading to the accumulation of elastic fibers in the actinic elastosis of sun-damaged skin. The transglutaminase substrate moiety of elafin plays an important role in anchoring elafin at its proper sites of action during UV-induced aging processes.     

Photo-damage protective effect of two facial products, containing a unique complex of Dead Sea minerals and Himalayan actives

Background Skin appearance is badly affected when exposed to solar UV rays, which encourage physiological and structural cutaneous alterations that eventually lead to skin photo-damage. Aims To test the capability of two facial preparations, extreme day cream (EXD) and extreme night treatment (EXN), containing a unique complex of Dead Sea water and three Himalayan extracts, to antagonize biological effects induced by photo-damage. Methods Pieces of organ cultures of human skin were used as a model to assess the biological effects of UVB irradiation and the protective effect of topical application of two Extreme preparations. Skin pieces were analyzed for mitochondrial activity by MTT assay, for apoptosis by caspase 3 assay, and for cytokine secretion by solid phase ELISA. Human subjects were tested to evaluate the effect of Extreme preparations on skin wrinkle depth using PRIMOS and skin hydration by a corneometer. Results UVB irradiation induced cell apoptosis in the epidermis of skin organ cultures and increased their pro-inflammatory cytokine, tumor necrosis α (TNFα) secretion. Topical applications of both preparations significantly attenuated all these effects. Furthermore, in human subjects, a reduction in wrinkle depth and an elevation in the intense skin moisture were observed. Conclusions The observations clearly show that EXD and EXN preparations have protective anti-apoptotic and anti-inflammatory properties that can attenuate biological effects of skin photo-damage. Topical application of the preparations improves skin appearance by reducing its wrinkles depth and increasing its moisturizing impact.     

Skin aging induced by ultraviolet exposure and tobacco smoking: evidence from epidemiological and molecular studies

BACKGROUND: Tobacco smoking, similar to ultraviolet (UV) A radiation exposure, has previously been identified as an important factor contributing to premature aging of human skin. OBJECTIVE AND DESIGN: To investigate the relationship between these two environmental factors, we have conducted a cross-sectional study of 83 subjects (48 males, 35 females, age range 23-95), in which sun exposure, pack-years of smoking history and potential confounding variables were assessed by questionnaire. Facial wrinkles were quantified using the Daniell score. In order to study the molecular mechanism by which smoking caused wrinkle formation, in vitro studies were conducted to assess the alteration of matrix metalloproteinase-1 (MMP-1) mRNA expression in human fibroblasts stimulated with tobacco smoke extract or/and UVA. RESULTS: Logistic statistic analysis of the data revealed that age [odds ratio (OR)=7.5, 95% confidence interval (CI)=1.87-30.161, pack-years (OR=5.8, 95% CI=1.72-19.87), and sun exposure (OR=2.65, 95% CI=1.0-7.0) independently contributed to facial wrinkle formation. When excessive sun exposure (>2 h/day) and heavy smoking (35 pack-years) occurred together, the risk for developing wrinkles was 11.4 times higher than that of non-smokers and those with less sun exposure (<2 h/day) at the same age. The in vitro studies revealed that MMP-1 expression was significantly increased in fibroblasts after the stimulation with either tobacco smoke extract or UVA. Maximum induction was observed when cells were treated with tobacco smoke extract plus UVA, indicating that the two factors act in an additive manner. MMP-1 induction was significantly higher in the low glutathione (GSH) content fibroblast compared to that in the high GSH fibroblast, indicating that the differences in glutathione content define the susceptibility of fibroblasts towards UV- or tobacco smoking-induced MMP-1 expression. CONCLUSION: Tobacco smoke and UVA cause wrinkle formation independently of each other. We propose that both factors cause aging of human skin through additive induction of MMP-1 expression.     

Skin rejuvenating effects of chemical peeling: a study in photoaged hairless mice

Background Chemical peeling is a dermatologic treatment for skin aging. However, the mechanism by which the chemical peel achieves its results is not clear. We investigated the effects of chemical peeling and the mechanism of wrinkle reduction in photoaged hairless mice skin. Methods After inducing photoaged skin in hairless mice by repetitive ultraviolet‐B irradiation applied over 14 weeks, we applied trichloroacetic acid (TCA) 30%, TCA 50%, and phenol on areas of the same size on the backs of the mice. Punch biopsies were obtained 7, 14, 28, and 60 days after the procedure for histologic and immunohistochemical analyses. Results Histologic examination showed an increase in dermal thickness, collagen fibers, and elastic fibers in the dermis of intervention groups compared with control groups. These increases were maintained significantly for 60 days. Conclusions This study demonstrates that chemical peeling reduces wrinkles and regenerates skin by increasing dermal thickness and the amount of collagen and elastic fibers in photoaged skin.     

Characteristics of skin wrinkling and dermal changes induced by repeated application of squalene monohydroperoxide to hairless mouse skin

We have studied the effect of squalene monohydroperoxides (Sq-OOH), initial products of UV-peroxidated squalene, on the skin of hairless mice. Repeated topical application of 10 mM Sq-OOH to hairless mice for 15 weeks induced definite skin wrinkling. When image analysis was used to compare wrinkle formation induced by ultraviolet B (UVB) irradiation and Sq-OOH treatment, the degree of wrinkling in exposed skin was seen to be similar. However, the characteristics of wrinkles induced by either method differed markedly with regard to direction and distribution. Biochemical analysis revealed a significant decrease in collagen content per unit area and mass in Sq-OOH-treated skin, whereas no changes per unit area and decrease in collagen per unit mass were observed in UVB-irradiated skin. As for glycosaminoglycan (GAG) content per unit area, significant increases were observed in both Sq-OOH-treated skin and UVB-irradiated skin. These changes were not induced by organic hydroperoxides such as TERT-butylhydroperoxide or cumene hydroperoxide treatment. Histological observation revealed epidermal hyperplasia and dermal alterations such as collagen degradation and GAG increases in Sq-OOH-treated skin. Histological changes induced by Sq-OOH were not as pronounced as those induced by UVB irradiation. These results clearly suggest that the wrinkling and changes in dermal collagen content induced by Sq-OOH are qualitatively different to those induced by UVB exposure. This may provide a useful model for the study of skin aging, particularly with regard to collagen content.     

UVB irradiation stimulates deposition of new elastic fibers by modified epithelial cells surrounding the hair follicles and sebaceous glands in mice

UVB irradiation stimulates the synthesis of elastin in the skin of humans and experimental animals. In this study we localized the site and the cells that are responsible for the synthesis of murine dermal elastic fibers. SKH-1 hairless mice were irradiated with UVB and the skin removed for light microscopy, electron microscopy, in situ hybridization, immunohistochemistry, and biochemical studies. In response to chronic low doses of UVB there was an initial moderate increase in tropoelastin mRNA in the papillary dermis. By contrast, there was a continuous marked elevation of collagen alpha1(I) message localizing to sites of inflammatory cell influx throughout the upper and lower dermis. After 25 wk of UV irradiation there was a 2-fold increase in skin elastin, yet total collagen remained unchanged. Serial desmosine analysis from en face sections indicated the increase in elastin content was due to dermal elastic fibers, an increase in the size and number of the dermal cysts, and an increase in subpanniculus elastic fibers. Elastin stains of en face sections suggested that the elastic fibers in the upper dermis were exclusively derived from cells lining the epithelial root sheath and sebaceous glands. In response to UV irradiation, the elastic fibers increased in number and size, wrapping around these structures and aligning in both directions as long fibers parallel to the body axis. Electron micrographs indicated that modified epithelial cells in close proximity to the flattened epithelial cells that encircled the root sheath and sebaceous glands were the source of the elastic fibers.     

Hyaluronic acid microneedle patch for the improvement of crow's feet wrinkles

Hyaluronic acid (HA) has an immediate volumizing effect, due to its strong water‐binding potential, and stimulates fibroblasts, causing collagen synthesis, with short‐ and long‐term effects on wrinkle improvement. We investigated the efficacy and safety of HA microneedle patches for crow's feet wrinkles. Using a randomized spilt‐face design, we compared microneedle patches with a topical application containing the same active ingredients. We enrolled 34 Korean female subjects with mild to moderate crow's feet wrinkles. The wrinkle on each side of the subject's face was randomly assigned to a HA microneedle patch or HA essence application twice a week for 8 weeks. Efficacy was evaluated at weeks 2, 4, and 8. Skin wrinkles were measured as average roughness using replica and PRIMOS. Skin elasticity was assessed using a cutometer. Two independent blinded dermatologists evaluated the changes after treatment using the global visual wrinkle assessment score. Subjects assessed wrinkles using the subject global assessment score. Skin wrinkles were significantly reduced and skin elasticity significantly increased in both groups, although improvement was greater in the patch group at week 8 after treatment. In the primary and cumulative skin irritation tests, the HA microneedle patch did not induce any skin irritation. The HA microneedle patch is more effective than the HA essence for wrinkle improvement and is a safe and convenient without skin irritation.