Perception gap of aged facial appearance; self-perception is younger than actual status due to angle of viewing.

BACKGROUND: Facial morphology changes with aging, resulting in an aged appearance that is a great matter of concern for people. However, it is not clear whether people perceive their own facial appearance accurately, in part because there are few methods to evaluate this. AIM: The aim of this study is firstly to establish an evaluation system for the perception gap of aged facial appearance between the self-perceived status and the actual status, and then to use this evaluation system to quantify the perception gap and to clarify the mechanism of this gap METHOD: Thirty-six middle-aged female volunteers were first asked to rate their facial aging-related morphology according to a 6-grade set of photos taken at a 45° angle from the front showing progressive stages of sagging severity, without looking either in a mirror or at photos of themselves (self- or "subjective" perception). Then they were shown photos of their face taken at a 45° angle from the front, and asked again to rate their sagging grade based on these photos ("objective" rating). In addition, facial photos taken from several angles from the front to the side were evaluated for sagging severity by trained evaluators. RESULTS: This system for analyzing perception gap revealed that the self-perception of aged appearance was significantly younger than the actual situation in three facial areas, namely the cheek, around the eyes and the facial contour, and the gap corresponded to an age difference of as much as 8 years in middle-aged females. Trained evaluators found that the severity of sagging judged from photos taken from a frontal direction was significantly less than in photos of the same subject taken from side angles. This suggests that recognition of sagging is more difficult from the front, which is the direction from which people view their own face in daily life. Indeed, viewing photos taken from the side, a rare viewing angle of one's own face, increased the motivation to improve aged appearance in more than 70% of the subjects in a questionnaire survey. CONCLUSION: The results suggest that people perceive their own facial appearance as less aged than it actually is. The reason for this appears to be that viewing from the front, the usual viewing angle of one's own face in daily life, results in lower perceived sagging severity, likely due to reduced depth perception.

Subcutaneous fat infiltration into the dermal layer induces wrinkle formation.

BACKGROUND: Wrinkles appear with aging, producing an aged impression, but the mechanism of wrinkle formation has not yet been fully elucidated. We recently reported that subcutaneous fat infiltrates into the dermal layer with aging and impairs skin elasticity, but the contribution of this process to wrinkle formation is still unclear. PURPOSE: We aimed to clarify the contribution of dermal fat infiltration to wrinkle formation by analyzing the relationship between them in the forehead of female volunteers. METHODS: We measured the severity of fat infiltration in the forehead of 29 middle-aged female volunteers by means of ultrasonography. Fixed wrinkles present when the eyes were closed and wrinkles transiently formed when the eyes were open were evaluated using a photograph-based 6-grade evaluation system for each type of wrinkle. RESULTS: Fat infiltration at the forehead area was observed similarly to that in the cheek area as we reported previously. We found that opening the eyes induced the formation of stable transient wrinkles, the grade of which was significantly related to fat infiltration severity. Furthermore, fat infiltration was also significantly related to the severity of fixed wrinkles. Moreover, the severity of transient wrinkles was significantly related to that of fixed wrinkles. CONCLUSIONS: Our results suggest that fat infiltration into the dermal layer enhances transient wrinkle formation during facial expression by impairing the ability of the skin to resist deformation, thereby promoting fixed wrinkle formation. Therefore, fat infiltration is a critical cause of wrinkle formation.

Vellus hair condition is related to dermal elasticity and facial sagging severity.

BACKGROUND: Sagging of facial skin is a critical factor associated with an aged appearance. However, the mechanism of sagging has not been fully elucidated. The facial skin contains vellus hair (fine hair), but the contribution of vellus hair to skin condition and facial aging has yet to be studied. AIM: We aimed to clarify the influence of vellus hair on the physical properties and sagging severity of facial skin by establishing an evaluation system for vellus hair condition. METHOD: Photographs were taken to assess the vellus hair condition in the cheek area in 30 middle-aged female volunteers. Skin elasticity was measured with a cutometer and sagging severity was evaluated by using previously established photograph-based grading criteria. RESULTS: Facial skin vellus hairs were divided into three types: fine, thick, and normal thickness. Based on this observation, we established a 6-grade photograph-based grading system based on the dominant type of vellus hair in the target area and used it to evaluate vellus hair condition at the cheek. We found that vellus hair condition is significantly positively related to skin elasticity parameters Ua/Uf (representing overall elasticity including creep and creep recovery), Ur/Ue (representing net elasticity without viscoelastic creep), and Ur/Uf (ratio of elastic recovery to total deformation). Further, vellus hair condition was significantly negatively correlated to sagging severity. CONCLUSION: Our results suggest that vellus hair condition positively contributes to the skin's physical properties, and consequently deterioration of the vellus hair condition promotes an aged facial appearance.

Fat infiltration into dermal layer induces aged facial appearance by decreasing dermal elasticity.

BACKGROUND: Facial morphology changes with aging, producing an aged appearance, but the mechanisms involved are not fully established. We recently showed that subcutaneous fat infiltrates into the dermal layer with aging, but it is not yet clear whether and how this drastic change of the dermal layer influences facial appearance. PURPOSE: We aimed to establish the role of fat infiltration in producing an aged facial appearance and to clarify the mechanism involved. METHODS: We analyzed the severity of fat infiltration in cheek skin of 30 middle-aged female volunteers by means of ultrasonography. Severity of the nasolabial fold, an established age-related morphology, was evaluated based on our photographic grading criteria as a measure of aged appearance. Skin elasticity was measured with a Cutometer. RESULTS: Fat infiltration to the dermal layer was detected at the cheek skin noninvasively by means of ultrasonography. Fat infiltration severity, measured as the minimum depth of the fat inside the dermal layer from the skin surface, was positively correlated with the magnitude of the nasolabial fold. Further, fat infiltration severity was significantly negatively correlated with dermal elasticity. CONCLUSIONS: Our results suggest that fat infiltration into the dermal layer is a critical factor inducing aged appearance of the face. The infiltrated fat decreases the dermal elasticity, which exacerbates nasolabial folds, namely producing an aged facial appearance.

Quantitative characterization of 3D structure of vellus hair arrector pili muscles by micro CT.

BACKGROUND: Vellus hair is the fine, wispy hair found over most of the body surface, and the arrector pili muscles (hair muscle) serve to raise these hairs. Hair muscles are also critical for skin regeneration, contributing to the maintenance of stem cells in epidermis and hair follicles. However, little is known about their fundamental properties, especially their structure, because of the limitations of conventional two-dimensional histological analysis. OBJECTIVES: We aimed to quantitatively characterize the structure of vellus hair muscles by establishing a method to visualize the 3D structure of hair muscle. METHODS: We observed young female abdominal skin specimens by means of X-ray micro CT and identified hair muscles in each cross-sectional CT image. We then digitally reconstructed the 3D structure of the hair muscles on computer (digital-3D skin), and numerically evaluated their structural parameters. RESULTS: Vellus hair muscles were clearly distinguished from the surrounding dermal layer in X-ray micro CT images and were digitally reconstructed in 3D from those images for quantification of the structural parameters. The mean value of number of divisions of vellus hair muscles was 1.6, mean depth was 943.6 µm from the skin surface, mean angle to the skin surface was 28.8 degrees, and mean length was 1657.9 µm. These values showed relatively little variation among subjects. The mean muscle volume was approximately 20 million µm3 but showed greater variability than the other parameters. CONCLUSION: Digital-3D skin technology is a powerful approach to understand the tiny but complex 3D structure of vellus hair muscles. The fundamental nature of vellus hair muscles was characterized in terms of their 3D structural parameters, including number of divisions, angle to the skin surface, depth, and volume.

Infiltration of subcutaneous adipose layer into the dermal layer with aging.

BACKGROUND: The elasticity of the dermal layer decreases with aging, leading to ulcer formation and wrinkling, but the mechanism of this change is not fully understood, because it is difficult to access the complex three-dimensional (3D) internal structure of the dermis. OBJECTIVE: To clarify age-dependent changes in the overall 3D structure of the dermal layer by means of 3D analysis technology. METHODS: We observed sun-protected human skin by means of X-ray micro CT, identified the layers of the skin, and reconstructed the 3D structure on computer. Age-dependent structural changes of the dermal layer were evaluated by statistical comparison of young and aged skin. RESULTS: Histological observations suggested the presence of two types of ectopic fat deposits, namely infiltrated subcutaneous fat and isolated fat, in the lower region of the reticular dermal layer in aged skin. To elucidate their nature, we observed skin specimens by X-ray microCT. The epidermis, dermal layer, and subcutaneous adipose layer were well differentiated on CT images, and 3D skin was digitally reconstructed on computer. This method clearly showed that the isolated fat observed histologically was in fact connected to the subcutaneous fat, namely all ectopic fat is connected to the subcutaneous adipose layer. Statistical analysis showed that the severity of fat infiltration into dermal layer is significantly increased in aged skin compared with young skin. CONCLUSION: Our findings indicate that subcutaneous fat infiltrates into the dermal layer of aged skin. Our 3D analysis approach is advantageous to understand changes of complex internal skin structures with aging.

Aging-related shift of eccrine sweat glands toward the skin surface due to tangling and rotation of the secretory ducts revealed by digital 3D skin reconstruction.

BACKGROUND: Sweat gland function deteriorates with aging, leading to loss of heat tolerance. However, it is unclear whether and how the structure of sweat glands changes during aging, because the 3D structure is complex and inaccessible. METHODS: To clarify age-dependent changes in sweat glands, we developed a method for 3D structure analysis of sweat glands by means of X-ray micro-CT observation of human skin specimens followed by 3D digital reconstruction on computer (digital 3D skin). RESULTS: Comparison of eccrine sweat glands of abdominal skin from young and old subjects showed that the density and volume of sweat glands do not change with aging. In contrast, the depth of the secretory coil from the skin surface is decreased in the aged group. Surprisingly, the secretory ducts appear tortuous or meandering though their length is unchanged. The secretory coils are located at the dermal-adipose layer boundary in both groups, but the thickness of the dermal layer decreases with aging, and the depth of the coils is correlated with the dermal thickness. CONCLUSION: Our results suggest that sweat glands twist and rotate with aging to maintain the position of the coil at the dermal-adipose boundary, causing an overall shift toward the skin surface.

Stanniocalcin-1 mediates negative regulatory action of epidermal layer on expression of matrix-related genes in dermal fibroblasts.

Dermal-epidermal interaction plays a role in many pathophysiological processes, such as tumor invasion and psoriasis, as well as wound healing, and is mediated at least in part by secretory factors. In this study, we investigated the factor(s) involved. We found that stanniocalcin-1 (STC1), a cytokine, is expressed at the basal layer of epidermis. Knockdown of STC1 with siRNA in HaCaT cells decreased matrix metalloproteinase 1 (MMP1) expression, suggesting that STC1 serves as an autocrine factor, maintaining MMP1 mRNA expression in the epidermal layer. In dermal fibroblasts, STC1 increased MMP1 mRNA expression and decreased collagen1A1 and elastin mRNA expression. These actions were inhibited by SP600125, a jun kinase (JNK) inhibitor. Nuclear translocation of AP-1, a downstream signal of JNK, was implicated in the actions of STC1. In a coculture system of HaCaT cells and fibroblasts, used as a model of dermal-epidermal interaction, knockdown of STC1 in HaCaT cells with siRNA reduced the negative effects (i.e., induction of MMP1 and decrease of collagen1A1 and elastin) of STC1 on fibroblasts. These results suggest that STC1 secreted from the epidermal layer is a mediator of dermal-epidermal interaction.

Senescent dermal fibroblasts negatively influence fibroblast extracellular matrix-related gene expression partly via secretion of complement factor D.

Aging is associated with a decrease of extracellular matrix and an increase of senescent cells in the dermal layer. Here, to examine whether and how senescent cells are involved in aging-related deterioration of the dermal layer, we cocultured dermal young fibroblasts (low-passage number) with senescent cells (high-passage number) in Transwells, in which the two cell types are separated by a semipermeable membrane. Young fibroblasts in coculture showed decreased collagen type I alpha 1 chain and elastin gene expression, and increased matrix metalloproteinase 1 (MMP1) gene expression. To identify causative factors, we compared gene expression of young and senescent cells and selected candidate secretory factors whose expression was increased by ≥2.5 in senescent fibroblasts. Then, we used siRNAs to knock down each of the 11 candidate genes in senescent fibroblasts in the coculture system. Knockdown of complement factor D (CFD) in senescent fibroblasts significantly reduced the increase of MMP1 in the cocultured young fibroblasts. In monocultures, treatment of young fibroblasts with CFD resulted in increased MMP1 gene expression, while knockdown of CFD in senescent fibroblasts decreased MMP1 gene expression. In addition, production of CFD was increased in culture medium of untreated senescent fibroblasts. Furthermore, CFD gene and protein expression were increased in the dermal layer of skin specimens from aged subjects (>70 years old), compared to young subjects (<20 years old). Overall, these results suggest that senescent cells negatively influence matrix production and promote degradation of nearby fibroblasts in the dermal layer, in part through secretion of CFD.

Increment of subcutaneous adipose tissue is associated with decrease of elastic fibres in the dermal layer.

Obesity is a significant risk factor for various skin disorders, including pressure ulcer and delayed wound healing. We previously showed that increment of subcutaneous adipose tissue contributes to poor skin condition by decreasing dermal elasticity. Here, we examined the mechanism involved. Histologic observation of abdominal skin from middle-aged females with a wide range of body mass index (BMI), an indicator of subcutaneous fat mass, showed that dermal elastic fibre abundance was significantly decreased with increment of BMI. Concomitantly, adipocytes were significantly enlarged. Adipocyte enlargement was significantly negatively correlated with dermal elastic fibre abundance. We hypothesized that enlarged adipocytes negatively influence dermal elastic fibres, so we investigated elastic fibre-degrading factors in in vitro-cultured enlarged adipocytes. MMP9 gene expression and secretion were significantly increased; further, these changes were blocked by extracellular signal-regulated kinase (ERK) inhibitor. Nuclear translocation (activation) of AP-1, a downstream ERK signalling molecule, was also observed in enlarged adipocytes. MMP9 abundance was significantly increased in skin of subjects with high BMI and enlarged adipocytes. These results suggest that increment of subcutaneous adipose tissue leads to adipocyte enlargement together with increased degradation of dermal elastic fibres, mediated at least in part by an ERK signalling-mediated increase of MMP9 in enlarged adipocytes.

Involvement of upper cheek sagging in nasolabial fold formation.

BACKGROUND: Nasolabial folds are a well-known feature of aging, but the mechanism of their formation remains unclear. OBJECTIVES: To clarify the mechanism of nasolabial fold formation, we established grading criteria for severity and explored the influence of dermal elasticity and subcutaneous adipose mass. We also investigated the involvement of facial morphological changes, such as wrinkling and sagging. METHODS: Faces of 108 healthy Japanese female volunteers (age range: 20-60) were photographed at the angle of 45°, and a six-grade photograph-based grading scheme for nasolabial fold severity was established and evaluated. In 70 Japanese female volunteers (middle-aged: 30-50), dermal elasticity was measured with a Cutometer MPA 580® and subcutaneous adipose layer thickness was measured by ultrasound using a Prosound alpha 5®. RESULTS: Nasolabial fold severity was significantly and positively correlated with age in subjects in their twenties to sixties (R = 0.777, P < 0.001). Nasolabial folds were drastically reduced, or disappeared, when the facial position was changed (subjects lay down instead of sitting) to reduce sagging; only 13.8% of subjects showed fixed wrinkles at the positions of the nasolabial folds after the facial position change. Nasolabial fold severity in middle-aged volunteers was significantly and negatively correlated with dermal elasticity parameters, i.e., net elasticity excluding viscoelastic creep (Ur/Ue), overall elasticity including creep and creep recovery (Ua/Uf), ratio of elastic recovery to total deformation (Ur/Uf), and the negative value of the amount of deformation that did not recover to the original state [-Uf-Ua)], all of which were significantly and negatively correlated with age. Subcutaneous adipose layer thickness was significantly and negatively correlated with dermal elasticity parameter Ua/Uf, and also significantly and positively related to nasolabial fold severity (R = 0.285, P < 0.017). CONCLUSIONS: Nasolabial fold severity increases with decreasing dermal elasticity and with increment of the subcutaneous adipose layer. These changes might induce sagging formation in the upper cheek area, promoting fold formation at the border between the inner and outer nasolabial areas.

Negative regulation of dermal fibroblasts by enlarged adipocytes through release of free fatty acids.

Subcutaneous adipose tissue lies just beneath the dermal layer, but the interaction between the two types of tissue remains obscure. Recently, we reported that obesity is associated with decreased dermal elasticity. To investigate the mechanism of the adipose tissue/dermal interaction, fibroblasts were cocultured with small or enlarged adipocytes, using a membrane insert to prevent direct contact. Enlarged adipocytes reduced 3T3-L1 fibroblast proliferation and gene expression of collagen (I)-α1 (col (I)-α1) and elastin while increasing gene expression of matrix metalloproteinase 13 (MMP13). In contrast, small adipocytes had no such effects. These results indicate that factors secreted by enlarged adipocytes influence dermal condition. As enlarged adipocytes are known to release free fatty acids (FFAs), the effects of these acids on 3T3-L1 fibroblasts were examined. Palmitic acid decreased fibroblast proliferation, reduced gene expressions of col (I)-α1 and elastin, and increased MMP13. Similar effects were observed in human dermal fibroblasts. The influence of palmitic acid on fibroblasts was inhibited by eicosapentaenoic acid (EPA), an inhibitor of Toll-like receptors (TLRs). Furthermore, EPA inhibited the effects of enlarged adipocytes on fibroblasts in the coculture system. These data indicate that enlarged adipocytes negatively control the function of dermal fibroblasts through the activation of TLRs by secreted FFAs.

Comparison of sagging at the cheek and lower eyelid between male and female faces.

BACKGROUND: Facial sagging is a well-known morphological feature associated with aging and reduced dermal elasticity. Its morphological characteristics and mechanism have been studied in females, but it is unclear whether or not there is a gender difference. AIMS: The aim of this study was to clarify the morphological characteristics of sagging and the mechanism of sagging formation in male faces as compared with female faces, focusing on changes in dermal elasticity. METHODS: Faces of 98 healthy Japanese male volunteers, in their 20s-60s, were photographed at an angle of 45°. Upper and lower cheek sagging severity was evaluated by using photograph-based grading criteria. In addition, new photograph-based grading criteria of sagging severity at the lower eyelid were established and used. Dermal elasticity was measured using a non-invasive, in vivo suction skin elasticity meter, Cutometer(®). Furthermore, photographs of 108 healthy Japanese female volunteers in their 20s-60s were used to compare the difference in the morphological characteristics of sagging between males and females. RESULTS: Male facial sagging was prominent at the lower eyelid, upper cheek and lower cheek. Sagging severity in the upper and lower cheek was almost the same between males and females at all ages, whereas sagging at the lower eyelid in males was significantly more severe than that in females after middle age. Although dermal extensibility (U(f)) was not related to age, total deformation recovery (U(a)), -(amount of deformation) -(U(f)-U(a)), overall elasticity of the skin including creep and creep recovery (U(a)/U(f)), net elasticity excluding viscoelastic creep (U(r)/U(e)), ratio of elastic recovery to total deformation (U(r)/U(f)) and -(ratio of viscoelastic to elastic distention) -(U(v)/U(e)) were all significantly negatively related to age in both men and women. Furthermore, as in female faces, male facial sagging was significantly negatively related to dermal elasticity parameters, such as -(U(f)-U(a)), U(a)/U(f), U(r)/U(e) and U(r)/U(f). CONCLUSION: These results indicate that the morphology and areas of sagging in male faces are similar to those in females in the cheek, but sagging at the lower eyelid is more severe in males after middle age. Furthermore, the dermal elasticity of male facial skin decreased with age similar to that of females, and may therefore be associated with the sagging formation in male faces.

Rubus suavissimus S. Lee extract increases early adipogenesis in 3T3-L1 preadipocytes.

Leaves of Rubus suavissimus S. Lee (Rosaceae) are used to prepare tiencha or sweet tea, which is helpful for body weight control by restricting calorie intake in obese patients. Obesity is a risk factor for metabolic syndrome, and a possible approach to treatment is to promote early adipogenesis in adipose tissue, thereby leading to replacement of enlarged adipocytes that secrete inflammatory factors with small adipocytes.We therefore investigated the effect of extract of tiencha leaves on early adipogenesis by using 3T3-L1 preadipocytes as a model. Tiencha extract significantly and concentration-dependently increased adipogenesis measured in terms of lipid accumulation by means of Oil Red O assay and increased the expression of adiponectin and leptin. In the early phase of adipogenesis, tiencha extract increased the mRNA expression of adipogenic transcription factors CCAAT/enhancer binding protein α (C/EBPα) and proliferator-activated receptor γ (PPARγ). In contrast, mRNA expression of other adipogenic transcription factors, C/EBPδ and C/EBPß, was unaffected. The mRNA expression levels of adipocyte-specific genes encoding adipocyte protein 2 (aP2), lipoprotein lipase (LPL), and glucose transporter 4 (Glut4), which are regulated by C/EBPα and PPARγ, were also increased. A PPARγ inhibitor, GW9662, partially inhibited the enhancing effect of tiencha extract on lipogenesis. These results suggest that tiencha extract enhances early adipogenesis by increasing the expression of adipogenic transcription factors C/EBPα and PPARγ.

Influence of subcutaneous adipose tissue mass on dermal elasticity and sagging severity in lower cheek.

BACKGROUND: Subcutaneous adipose tissue lies just beneath the dermal layer, but the interaction between the two is not well understood. Recently, we showed that the subcutaneous adipose layer affects dermal properties in an obese rodent model. OBJECTIVE: To explore the influence of the subcutaneous adipose layer on dermal properties and morphology in humans. METHODS: Subcutaneous adipose mass was measured by ultrasound using a Prosound alpha 5, dermal elasticity was measured using an in vivo suction skin elasticity meter (Cutometer MPA 580, and sagging severity were evaluated morphologically using photograph-based grading criteria at the lower cheek in 70 Japanese female volunteers (age; 31-59, BMI; 17.1-36.2). The correlations among the results were examined. RESULTS: Thickness of the subcutaneous adipose layer was significantly and negatively correlated with dermal elasticity parameters, i.e., elastic deformation, elastic deformation recovery, extensibility, total deformation recovery, ratio of viscoelasticity to elastic distention and overall elasticity, including creep and creep recovery. Furthermore, we investigated their influence on facial morphology, such as sagging. The subcutaneous adipose mass was significantly and positively correlated with sagging severity at the lower cheek (R=0.442, P<0.001), and there was a significant negative correlation between dermal elasticity and sagging severity (R=-0.358, P<0.01). CONCLUSION: These results indicate that increment of subcutaneous adipose mass impairs dermal elasticity, which in turn exacerbates sagging severity.

The severity of wrinkling at the forehead is related to the degree of ptosis of the upper eyelid.

BACKGROUND: Most studies on wrinkle formation have focused on changes in the dermal condition that promote the fixation of transiently formed wrinkles. Little is known about the age-dependent changes in transient wrinkle formation in response to altered facial expression or the mechanism leading to fixed wrinkle formation. OBJECTIVE: To clarify the mechanism of wrinkle formation at the forehead, we investigated the factors that influence the severity of transient wrinkling and the relationship of transient with fixed wrinkles, using a newly established method to evaluate transient wrinkle formation. METHODS: Transient wrinkles were generated by requesting subjects to gaze in an upward direction. Foreheads of the subjects with or without an upward gaze at a fixed angle were photographed and the severity of wrinkles at the forehead was graded from 0 to 5 in 50 healthy Japanese female volunteers in their 20s, 40s, or 60s. Skin elasticity was measured using a Cutometer. Frontalis muscle activity and ptosis of the upper eyelid were estimated by measuring movement of the eyebrow during upward gazing and the position of the upper eyelid of the open eye, respectively. RESULTS: Wrinkles formed transiently at the forehead by upward gazing were highly reproducible in each subject. Their severity increased with aging and was highly correlated to that of fixed wrinkles (R=0.81, P<0.001). Therefore, this method appears to be suitable for studying the mechanism of transient wrinkle formation and the relationship between transient and fixed wrinkles at the forehead. The severity of transient wrinkles was correlated with elevation of the eyebrow during upward gazing (R=0.69, P<0.001), but not with dermal elasticity. This suggests that transient wrinkles are induced by increased frontalis muscle activity during upward gazing. Frontalis muscle activation was negatively correlated with upper eyelid position (R=-0.37, P<0.05), which descended with aging, meaning ptosis of the upper eyelid, and negatively correlated with the severity of transient wrinkles induced by upward gazing (R=-0.43, P<0.05). Furthermore, the upper eyelid position was also negatively correlated with the severity of fixed wrinkles (R=-0.44, P<0.05). CONCLUSION: These results suggest that ptosis of the upper eyelid is associated with increased activation of the frontalis muscle during upward gazing and increased severity of transient and fixed wrinkling at the forehead.

Increased subcutaneous adipose tissue impairs dermal function in diet-induced obese mice.

Increment of subcutaneous adipose tissue is a risk factor for facial morphological changes, such as sagging, which may be at least partly because of the increased weight burden of accumulated fat. However, it is not clear how the increase of subcutaneous adipose tissue affects dermal structure and function. We examined this issue in HR-1 hairless mice given a high-fat diet (HFD). After having been fed with HFD for 12 weeks, the mice became obese and the subcutaneous adipose tissue layer was significantly thickened, while the dermal layer became significantly thinner than that of control mice fed normal diet. However, the thickness of the dermal layer was not changed in the ear pinna, which lacks a subcutaneous adipose layer, suggesting that increase of subcutaneous adipose tissue may induce dermal changes. The number of dermal fibroblasts in the dermis was significantly reduced in obese mice, although there was no change in gene expression levels of extracellular matrix components, including collagen, hyaluronic acid synthase, fibulin5, fibrillin-1, laminin ß1, matrix metalloproteinases and tissue inhibitor of metalloproteinases. Dermal elasticity was significantly decreased in obese hairless mice. These results suggest that subcutaneous adipose cells in obese mice may reduce the proliferation of dermal fibroblasts and induce a decrease of dermal thickness and elasticity. Therefore, the increment of the subcutaneous adipose layer in obese subjects may induce impairment of dermal biomechanical characteristics and promote the appearance of sagging.

Heat stimulation reduces early adipogenesis in 3T3-L1 preadipocytes.

In this study, we used 3T3-L1 preadipocytes as a model to investigate the effects of heat stimulation on adipogenesis, which is a key process in the development of obesity. Heat stimulation at 43 degrees C for 60 min significantly reduced lipid accumulation, as measured by Oil Red-O assay. In the early phase of adipogenesis, heat stimulation almost completely blocked the increase of CCAAT/enhancer binding protein delta (C/EBPdelta) gene expression and delayed the onset of the increase of C/EBPbeta gene expression. The expression of proliferator-activated receptor gamma (PPARgamma), which is regulated by these factors, was also reduced. In the later phase of adipogenesis, the induction of adipocyte-specific genes, such as C/EBPalpha, adipocyte protein 2 (aP2), lipoprotein lipase (LPL), adiponectin, and glucose transporter 4 (Glut4), which are regulated by PPARgamma, was reduced. However, adipogenesis was not significantly reduced if heat stimulation was carried out after the early phase of adipogenesis. These results suggest that heat stimulation reduces adipogenesis by decreasing the expression of adipogenesis-related transcriptional factors during early adipogenesis.

Adiponectin and leptin up-regulate extracellular matrix production by dermal fibroblasts.

Adipocytes were recently shown to secrete adipocytokines, such as adiponectin and leptin, which may have an endocrine role. Subcutaneous adipose tissue lies just beneath the dermis, and dermal condition is correlated with body mass index (BMI). However, it is not clear whether adipocytokines released by adipocytes in subcutaneous adipose tissue influence the adjacent dermis. We found that human dermal fibroblasts express genes encoding receptors for adiponectin and leptin, and that those cytokines both significantly increase production of hyaluronic acid (HA), a major extracellular matrix component (ECM) of dermis, by dermal fibroblasts. This effect is accompanied with up-regulation of HA synthase 2 gene expression. Moreover, adiponectin significantly increases production of collagen, the most abundant component of ECM in dermis, by dermal fibroblasts. These results suggest that subcutaneous adipocytes influence dermal condition by up-regulating collagen and HA production by dermal fibroblasts via secretion of adiponectin and leptin.