Diameter-dependent classification of dermal vasculature using optical coherence tomography angiography.

Background: Dermal blood vessels beneath the epidermis play critical roles in epidermal homeostasis and are functionally divided into several types, such as capillaries. Optical coherence tomography angiography (OCTA) is a powerful tool for the non-invasive assessment of dermal vasculature. However, the classification of vessel types has been limited. To address this issue, we proposed an algorithm for diameter-dependent classification that preserves three-dimensional (3D) information using OCTA. Methods: OCTA data were acquired by a prototype swept-source-type optical coherence tomography (OCT) system, which was processed through several imaging filters: an optical microangiography (OMAG) imaging filter, a vesselness imaging filter, and a diameter map filter. All vessels were visually classified into three types based on their diameters, as micro-vessels, intermediate vessels, and thick vessels. Aging-related alterations and their association with the epidermis were investigated for each vessel type. The measurements were conducted on the cheeks of 124 female subjects aged 20-79 years. Results: The 3D vascular structure was visualized by applying our proposed post-processing filters. Based on visual assessment, the thresholds for the diameters of the micro, intermediate and thick vessels were set at 80 and 160 µm. It was found that micro-vessels were predominantly located in the upper layer of the dermis and thick vessels in the deeper layer. Analysis of vessel metrics revealed that the volume density of the micro-vessels decreased significantly with age (r=-0.36, P<0.001) and was positively correlated with epidermal thickness (r=0.50, P<0.001). In contrast, the volume density of thick vessels significantly increased with age (r=0.2, P<0.05) and was not significantly correlated with epidermal thickness (r=0.13, P≥0.05). Conclusions: In this study, we proposed a 3D quantification method using OCTA for dermal blood vessels and various vessel metrics, such as vessel volume density. This proposed classification will be beneficial for determining the function of the dermal vasculature and its diagnostic applications.

Epidemiological survey of the quantity and anatomical position of facial pigmented spots in relation to age in 454 Japanese women.

Facial pigmented spots are one of the phenotypes of skin aging, but no quantitative analysis of spot features such as color intensity, size, anatomical position, and number on the cheek has yet been performed. In the current study, we conducted an epidemiological survey of 454 Japanese women in their 20s to 70s and analyzed age-related changes and site differences of facial pigmented spots. Using image analysis of high-resolution digital facial photographs, 4912 individual pigmented spots were quantified according to color, size, anatomical position, and total number on the cheek. As a result of color analysis, the color intensity of individual pigmented spots increased with aging, significantly so between ages 30s and 50s. The age-related increase in melanin index of facial spots was confirmed in all sites but did not significantly differ between facial subregions. Regarding the size of pigmented spots, the frequency of large spots increased with age, and large spots were detected in all facial sites. The total number of pigmented spots on the entire cheek increased with aging, significantly so between the 20s and 40s. The number of pigmented spots tended to increase from the region near the canthi to the lower cheeks. The number of spots was markedly increased in the buccal regions compared with the infraorbital and zygomatic regions. The data and methodology presented in the current study can link the state of facial pigmentation with the various factors involved in the histological development of pigmented spots, opening new possibilities in the fields of skin pharmacology and dermatology.

How emotional changes affect skin odor and its impact on others.

The gas emanating from human skin is known to vary depending on one's physical condition and diet. Thus, skin gas has been gaining substantial scholarly attention as an effective noninvasive biomarker for understanding different physical conditions. This study focuses on the relationship between psychological stress and skin gas, which has remained unclear to date. It has been deduced that when participants were subjected to interviews confirmed as stressful by physiological indicators, their skin emitted an odor similar to stir-fried leeks containing allyl mercaptan and dimethyl trisulfide. This characteristic, recognizable odor appeared reproducibly during the stress-inducing situations. Furthermore, the study deduced that individuals who perceive this stress odor experience subjective tension, confusion, and fatigue (Profile of Mood States scale). Thus, the study findings indicate the possibility of human nonverbal communication through odor, which could enhance our understanding of human interaction.

Evaluation of psychological stress in confined environments using salivary, skin, and facial image parameters.

Detecting the influence of psychological stress is particularly important in prolonged space missions. In this study, we determined potential markers of psychological stress in a confined environment. We examined 23 Japanese subjects staying for 2 weeks in a confined facility at Tsukuba Space Center, measuring salivary, skin, and facial image parameters. Saliva was collected at four points in a single day to detect diurnal variation. Increases in salivary cortisol were detected after waking up on the 4th and 11th days, and at 15:30 on the 1st and in the second half of the stay. Transepidermal water loss (TEWL) and sebum content of the skin were higher compared with outside the facility on the 4th and 1st days respectively. Increased IL-1ß in the stripped stratum corneum was observed on the 14th day, and 7 days after leaving. Differences in facial expression symmetry at the time of facial expression changes were observed on 11th and 14th days. Thus, we detected a transition of psychological stress using salivary cortisol profiles and skin physiological parameters. The results also suggested that IL-1ß in the stripped stratum corneum and facial expression symmetry are possible novel markers for conveniently detecting psychological stress.

A Role of Staphyococcus aureus, Interleukin-18, Nerve Growth Factor and Semaphorin 3A, an Axon Guidance Molecule, in Pathogenesis and Treatment of Atopic Dermatitis.

Staphylococcus aureus (SA) is usually present not only in the skin lesions of atopic dermatitis (AD) but also in the atopic dry skin. SA discharges various toxins and enzymes that injure the skin, results in activation of epidermal keratinocytes, which produce and release IL-18. IL-18 that induces the super Th1 cells secreting IFN-γ and IL-13 is supposed to be involved in development of AD and its pathogenesis. Indeed, the number of SA colonies on the skin surface and the serum IL-18 levels in patients with AD significantly correlated with the skin scores of AD lesions. Also, there is strong positive correlation between the skin scores and serum IL-18 levels in DS-Nh mice (P<0.0001, r=0.64), which develop considerable AD-like legions when they are housed under conventional conditions, but develop skin legions with less severity and less frequency under specific pathogens free (SPF) conditions. Therefore, they are well-known as model mice of AD, in which SA is presumed to be critical factor for the development of AD lesions. Also, theses DS-Nh mice pretreated with Cy developed more remarkable AD-like lesions in comparison with non-treated ones. The levels of INF-r and IL-13 in the supernatants of the lymph node cell cultures stimulated with staphylococcal enterotoxin B (SEB) or ConA were increased in the Cy-treated mice, although the serum levels of total IgE were not. In this experiment, we revealed that Cy-treated mice, to which CD25 +CD4 + reguratory T cells taken from non-treated ones had been transferred, developed the AD-like legions with less severity and less number of SA colonies on the skin surface. Therefore, it is presumed that CD25 +CD4 + reguratory T cells might be involved in the suppression of super Th1 cells which are induced by IL-18 and are involved in the development of AD-like lesions rather than IgE production. The efficient induction of CD25 +CD4 + reguratory T cells is expected for the new type of treatment of AD. We also found that farnesol (F) and xylitol (X) synergistically inhibited biofilm formation by SA, and indeed the ratio of SA in total bacteria at sites to which the FX cream containing F and X had been applied was significantly decreased 1 week later, accompanied with improvement of AD, when compared with that before application and at placebo sites. Therefore, the FX cream is a useful skin-care agent for atopic dry skin colonized by SA. The nerve growth factor (NGF) in the horny layer (the horn NGF) of skin lesions on the cubital fossa was collected by tape stripping and measured using ELISA in AD patients before and after 2 and 4 weeks treatments. Simultaneously, the itch and eruptions on the whole body and on the lesions, in which the horn NGF was measured, were recorded, and also the peripheral blood eosinophil count, serum LDH level and serum total IgE level were examined. The level of NGF was significantly higher in AD patients than in healthy controls, correlated with the severity of itch, erythema, scale/xerosis, the eosinophil count and LDH level, and also significantly decreased after treatments with olopatadine and/or steroid ointment for 2 and 4 weeks. Therefore, the measurement of the NGF by this harmless method seems to be useful to assess the severity of AD and the therapeutic effects on AD. In AD patients, C-fiber in the epidermis increase and sprout, inducing hypersensitivity, which is considered to aggravate the disease. Semaphorin 3A (Sema3A), an axon guidance molecule, is a potent inhibitor of neurite outgrowth of sensory neurons. We administered recombinant Sema3A intracutaneously into the skin lesions of NC/Nga mice, an animal model of AD, and investigated the effect of Sema3A on the skin lesions and their itch. Sema3A dose-dependently improved skin lesions and attenuated the scratching behavior in NC/Nga mice. Histological examinations revealed a decrease in the epidermal thickness, the density of invasive nerve fibers in the epidermis, inflammatory infiltrate including mast cells and CD4 +T cells, and the production of IL-4 in the Sema3A-treated lesions. Because the interruption of the itch-scratch cycle likely contributes to the improvement of the AD-like lesions, Sema3A is expected to become a promising treatment of patients with refractory AD.

Effects of aging on activity of the prefrontal cortex and autonomic nervous system during mental stress task.

We evaluated the effect of aging on the prefrontal cortex (PFC) activity and heart rate during the task. Employing near infrared spectroscopy (NIRS), we measured hemoglobin concentration changes in the bilateral PFC during a mental arithmetic task in young and older females. We selected the subjects who exhibited an increase in oxyhemoglobin with a decrease in deoxyhemoglobin during the task. We observed that right PFC activity predominantly modulates sympathetic effects during the task in both groups. However, the changes of oxyhemoglobin and heart rate during the task in older subjects were significantly smaller than those in young subjects. These results indicate that aging affects evoked cerebral blood oxygenation (CBO) response patterns of the PFC during a mental stress task. Aging did not affect the laterality of PFC activity in modulation of ANS function in the subjects who exhibited increases of oxyhemoglobin and deoxyhemoglobin associated with a decrease of deoxyhemoglobin during the task. However, aging reduced the heart rate increase during the task.

Functional characteristics of the skin surface of children approaching puberty: age and seasonal influences.

The aim of this study was to determine differences in the functional properties of the stratum corneum of children and adults, focusing on the influence of approaching puberty. Biophysical measurements were made of the stratum corneum of 32 healthy Japanese children aged 10-14 years and their mothers in summer and the following winter. The children showed significantly lower skin surface hydration. Stratum corneum barrier function, evaluated in terms of trans-epidermal water loss, was poorer on the forearm in the children than in the adults regardless of season. By contrast, the stratum corneum barrier of the cheek, which was better in the children, tended to become poorer when the children reached puberty. Although the immaturity of the cornified envelopes of the superficial corneocytes, which ratio increased significantly in winter, was not different from that of adults, the corneocytes were significantly smaller in the children, suggesting a more rapid turnover of the stratum corneum. The amount of skin surface lipid, which was measured only on the cheek, remained low until 13 years of age, but at 14 years of age it increased remarkably, approaching adult levels. We conclude that, until puberty, most functional characteristics of the skin of children remain distinct from those of adults.

Glucocorticoids enhance Toll-like receptor 2 expression in human keratinocytes stimulated with Propionibacterium acnes or proinflammatory cytokines.

Toll-like receptors (TLRs) on keratinocytes are important cell surface receptors involved in the innate and acquired immune response to invading microorganisms. In acne vulgaris, TLR2 activation by Propionibacterium acnes (P. acnes) may induce skin inflammation via induction of various proinflammatory molecules that stimulate the invasion of inflammatory cells. Although corticosteroids themselves exert immunosuppressive or anti-inflammatory effects, it is well known clinically that systemic or topical glucocorticoid treatment provokes an acneiform reaction. Nevertheless, the effect of steroids on TLR2 expression in human keratinocytes remains unknown. Here, we found that the addition of glucocorticoids, such as dexamethasone and cortisol, to cultured human keratinocytes increased their TLR2 gene expression. Moreover, these glucocorticoids markedly enhanced TLR2 gene expression, which was further stimulated by P. acnes, tumor necrosis factor-alpha, and IL-1alpha. Gene expression of mitogen-activated protein kinase (MAPK) phosphatase-1 was also increased by the addition of dexamethasone. By using several inhibitors and activators, we found that TLR2 gene induction by glucocorticoids was mediated by the suppression of p38 MAPK activity following induction of MAPK phosphatase-1. These findings strongly suggest that steroid-induced TLR2 together with P. acnes existing as normal resident flora plays an important role in the exacerbation of acne vulgaris as well as in possible induction of corticosteroid-induced acne or in that of rosacea-like dermatitis.

Effects of fragrance administration on stress-induced prefrontal cortex activity and sebum secretion in the facial skin.

Although fragrances have long been known to influence stress-induced psychosomatic disorders, the neurophysiological mechanism remains unclear. We evaluated the effect of fragrance on the relation between the level of sebum secretion in the facial skin and the stress-induced prefrontal cortex (PFC) activity, which regulates the activity of the hypothalamic-pituitary-adrenal axis. Employing near infrared spectroscopy, we measured hemoglobin concentration changes in the bilateral PFC during a mental arithmetic task in normal adults (n=31), and evaluated asymmetry of the PFC activity in terms of the laterality index (i.e., [(right-left)/(right+left)]) of oxyhemoglobin concentration changes (LI-oxyHb). We measured the level of sebum secretion in the facial skin before the task performance. There was a significant positive correlation between the LI-oxyHb and the level of sebum secretion (r=+0.44, p=0.01). We selected the subjects who exhibited high levels of sebum secretion and right-dominant PFC activity for the study on the fragrance effect (n=12). Administration of fragrance for four weeks significantly reduced the level of sebum (p=0.02) in the fragrance group (n=6). In addition, the LI-oxyHb decreased significantly from 0.11+/-0.07 to -0.10+/-0.18 (p=0.01), indicating that the dominant side of the stress-induced PFC activity changed from the right to left side. In contrast, neither LI-oxyHb nor the levels of sebum secretion changed significantly in the control group (n=6). These results suggest that administration of fragrance reduced the level of sebum secretion by modulating the stress-induced PFC activity. The PFC may be involved in the neurophysiological mechanism of fragrance effects on systemic response to mental stress.

Relation between mental stress-induced prefrontal cortex activity and skin conditions: a near-infrared spectroscopy study.

Although psychological stress affects skin condition, the neurophysiological mechanism involved is unclear. In this study, we evaluated the relationship between skin condition and left/right asymmetry in prefrontal cortex (PFC) activity during mental stress tasks since recent studies have suggested that the right PFC dominates the regulation of the stress response system, including the hypothalamic-pituitary-adrenal (HPA) axis. Using near-infrared spectroscopy, we measured hemoglobin concentration changes in the bilateral PFC during a mental arithmetic task in normal adults and evaluated the laterality scores (i.e., [(right-left)/(right+left)]) of oxyhemoglobin concentration changes. Elicitation of stress was verified by the State-Trait Anxiety Inventory (STAI) and heart rate. The sebum levels and Propionibacterium acnes populations in the facial skin were measured before the task. The task significantly increased the STAI-II scores (p=0.00079) and heart rate (p=0.0000049). The oxyhemoglobin concentration increased in the bilateral PFC during the task, associated with a decrease in deoxyhemoglobin concentration. The laterality scores of oxyhemoglobin concentration changes were positively correlated with sebum levels (r=+0.50, p=0.026) and P. acnes populations (r=+0.49, p=0.029) in the facial skin before the task. There was a significant positive correlation between heart rate changes and the laterality scores of oxyhemoglobin concentration changes (r=+0.54, p=0.015). These results demonstrate that the subjects with higher sebum levels and higher P. acnes populations in the facial skin have a right dominant PFC activity during a mental stress task and suggest that such subjects are sensitive to mental stress associated with hyperactivity of the stress response system, including the HPA axis system.

A novel method to control the balance of skin microflora. Part 1. Attack on biofilm of Staphylococcus aureus without antibiotics.

BACKGROUND: Staphylococcus aureus (SA) is usually present in atopic dry skin, and not only in regions seriously affected by atopic dermatitis. SA discharges various toxins and enzymes that injure the skin, and forms a biofilm from fibrin fiber and glycocalyx; the biofilm is important for adhesion of SA to the skin and for resistance to anti-microbial agents. Even highly effective moisturizers do not work perfectly on atopic dry skin. Staphylococcus epidermidis (SE) is a major constituent of skin microflora on healthy human skin, and provides protection against the growth of pathogenic bacteria. OBJECTIVES: Since treatment with anti-microbials may lead to re-growth of SA, which grows faster than other Staphylococci and often shows antibiotic resistance, we searched for novel approaches to control the skin-microfloral balance without using conventional anti-microbials. METHOD: Biofilm formation by SA in vitro was observed in detail using scanning electron microscopy. Approximately 500 substances were screened for a selective effect on SA growth and SA biofilm. RESULTS: We found that xylitol inhibited the formation of glycocalyx, and farnesol dissolved fibrin fibers. Farnesol suppressed the growth of only SA, and did not affect that of SE. Xylitol and farnesol synergistically inhibited biofilm formation by SA. CONCLUSION: Xylitol and farnesol have potential for controlling the skin-microfloral balance because of their selective effects and inhibition of biofilm formation. They might provide a useful and safe method to care for skin colonized by SA, without using antibiotics.

A novel method to control the balance of skin microflora Part 2. A study to assess the effect of a cream containing farnesol and xylitol on atopic dry skin.

BACKGROUND: It is recognized that colonization by Staphylococcus aureus (SA) on the skin is one of the factors that can worsen atopic dermatitis (AD). Antibiotics and germicides are not the best choice to remove bacteria from the skin of AD patients, because of problems of irritation to the skin and bacterial resistance. We therefore turned our attention to the biofilm of SA with the aim of removing only SA from the skin surface of AD patients. We found that xylitol (X) and farnesol (F) synergistically inhibited biofilm formation by SA and dissolved biofilm formed in vivo (Part 1). OBJECTIVE: To test whether application of AD for 1 week with FX cream can reduce SA without affecting Staphylococcus epidermidis. METHODS: A randomized, double-blind, placebo-controlled right-and-left comparison study was performed. The arms of 17 patients with dry-type AD were applied with skin-care cream including/or not including a 0.02% F and 5% X combination for 1 week. The clinical response, biophysical assessment of the skin surface and counts of skin microflora were recorded before and after 1 week of therapy. RESULTS: The ratio of SA in total bacteria at sites to which FX cream had been applied was significantly decreased after 1 week (P = 0.007), compared with before application and with placebo sites (P = 0.045). The mean skin conductance (a parameter indicating the state of hydration of the skin surface) of FX cream sites was increased significantly compared with the conductance before application (P = 0.0001) and at placebo sites (P = 0.002). CONCLUSION: This study provides evidence supporting the idea that cream containing F and X is a useful skin-care agent for atopic dry skin colonized by SA.

Actions of farnesol and xylitol against Staphylococcus aureus.

BACKGROUND: Heavy colonization of atopic dermatitis (AD) with Staphylococcus aureus is well documented. The isolation rate of methicillin-resistant S. aureus is high in strains from AD in Japan. Our objective in the present study was to investigate the actions of farnesol and xylitol against S. aureus for the control of AD skin lesion-colonizing S. aureus. METHODS: We examined the actions of farnesol on plasma coagulation and superantigenic exotoxin production by S. aureus, the antimicrobial activity of beta-lactam antibiotics combined with farnesol at concentrations below the minimal inhibitory concentration (MIC) and the effect of xylitol on glycocalyx production. RESULTS: Coagulation by S. aureus cells was inhibited in plasma containing farnesol at a concentration of 1/12 of the MIC (100 microg/ml) after incubation for 24 h. The production of superantigenic exotoxins by S. aureus cells with farnesol (100 microg/ml) was about 10 times lower than that by S. aureus cells alone. The MICs of ampicillin and cefdinir against S. aureus were reduced to < or =0.06 microg/ml in Mueller-Hinton agar plates with farnesol (100 microg/ml). We suggest that farnesol at concentrations above the MIC had a suppressive effect against S. aureus cells in the exponential and stationary phase and acted on the cell wall of S. aureus cells in both phases. CONCLUSIONS: Farnesol is a promising adjuvant agent against S. aureus skin infections treated with beta-lactam antibiotics. Further, 5% xylitol inhibited glycocalyx production by S. aureus cells and consequently had a suppressive effect on the colonization of S. aureus on the horny cells of AD lesions.