Visible skin condition and perception of human facial appearance
Introduction
引言
英文原文
Variability in visible skin appearance is an important signal and moderator in human social interaction. For example, flushing because of increased blood flow when embarrassed or from sexual arousal facilitates non-verbal communication, as it reflects an individual’s emotional state. Moreover, deliberate modifications of the skin, such as scarification, tattoos and piercing, are used for personal expression, rite of passage or fashion trends. The significance of the appearance of the skin is also evident in dermatological disorders, which can have a major impact on patients’ daily activities, self-esteem, mental well being and social relationships because of their conspicuous visibility . Interestingly, a study of patients from different social and ethnic groups in South Africa revealed that women were more likely than men to report the effects of skin disease on self-esteem, clothing choice, treatment problems and anxiety . Because of the existence of an attractiveness stereotype, public response to skin diseases such as psoriasis, atopic dermatitis and acne often results in prejudice and stigmatization. The origins of such response are thought to be rooted firmly in history and culture because skin disease has long been associated with disgrace and danger in several cultures . Hence, it has been reported that the prevalence of psychiatric and psychosocial comorbidity, including depressive illness, obsessive-compulsive disorder, social phobia and body dysmorphic disorder in dermatological patients ranges from 25% to 43% . Moreover, in a study by Gupta et al, 6% of patients suffering from psoriasis reported suicidal thoughts.
对应中文
可见皮肤外观的变异性是人类社会互动的一个重要信号和调节因素。例如，尴尬时因血流增加而脸红或因性唤起而脸红有助于非言语交流，因为这反映了个人的情绪状态。此外，刻意修改皮肤，如划痕、纹身和穿孔，已经广泛用于个人表达、成年仪式或时尚趋势。皮肤外观的重要性在皮肤科疾病中也很明显，这些疾病会对患者的日常活动、自尊、心理健康和社会关系产生重大影响，因为它们具有明显的可见性。有趣的是，一项针对南非不同社会和种族群体患者的研究表明，女性比男性更容易报告皮肤病对自尊、衣着选择、治疗问题和焦虑的影响。由于吸引力刻板印象的存在，公众对牛皮癣、特应性皮炎和痤疮等皮肤病的反应往往会导致偏见和污名。这种反应的起源被认为牢固地植根于历史和文化，因为在不同文化中，皮肤病长期以来一直与耻辱和危险联系在一起。因此，据报道，皮肤科患者中精神和心理社会并存的患病率从25%到43%不等，包括抑郁症、强迫症、社交恐惧症和躯体变形障碍。此外，在Gupta等人的一项研究中，6%的银屑病患者有自杀念头。
英文原文
The cosmetic industry has often conveyed the image that youthful and healthy looking skin, free of blemishes and hair, is most desirable, primarily for women. As the face is of particular impor- tance in human social communication and body image, even minor imperfections can have an often disproportionately major impact on mental health and quality of life (QoL). Hence, it is now known that women with facial skin complaints may be particularly prone to depression and an increased risk of suicide. In accordance with previous studies, make-up was found to improve significantly the QoL in women with disfiguring skin disorders. For example, Hayashi et al.reported a significant decrease in the score of the ‘General Health Questionnaire 30’ (GHQ 30) in female acne sufferers after receiving advice on the appropriate use of make-up. The GHQ 30 was originally designed to screen people for psychological or mental health care services, and patients who scored higher than seven were recommended for psychological counselling. Women scored on average >9 on the GHQ 30 before the makeup lessons, whereas afterwards, the score improved to a normal level (<5).
对应中文
化妆品行业经常传达这样的形象：年轻健康的皮肤，没有瑕疵和头发，是最理想的，特别对于女性。由于面部在人类社会交流和身体形象中具有特别重要的意义，即使是微小的缺陷也会对心理健康和生活质量（QoL）产生不成比例的重大影响。因此，人们现在知道，患有面部皮肤不适的妇女可能特别容易患抑郁症，而且自杀的风险增加。在与之前的研究一致的情况下，化妆被发现能显著改善患有毁容皮肤病的女性的生活质量。例如，Hayashi等人报告说，在接受了适当化妆的建议后，女性痤疮患者的“一般健康问卷30“ (GHQ 30) 得分显著下降。GHQ 30最初是设计用来对人进行筛查的在心理或心理保健服务方面，得分高于7的患者被推荐接受心理咨询。女性在化妆课前的GHQ30平均得分>9，而在化妆课后，得分提高到正常水平(<5)。
英文原文
Importantly, unblemished facial skin also drives the positive perception of attractiveness in healthy women without dermatological disease. In a study by Mulhern et al.10 female volunteers were made up by a beautician to produce five possible scenarios: (1) no make up, (2) foundation only, (3) lip make-up only, (4) eye make-up only, (5) and full facial make-up. The results revealed that faces with full make-up were judged higher on attractiveness than without make-up. Moreover, it was found that attractiveness ratings of certain facial regions were also influenced by the sex of the rater. Whereas women judged eye-make up as having the greatest impact on attractiveness, in men both eye make-up and skin foundation influenced their attractiveness ratings. In accordance with the effect of make-up on mental well being in patients with skin disorders, cosmetic usage also enhances self-esteem in healthy women, as it positively influences both self-perception and perception by others. Moreover, Cash et al. reported a systematic relationship between the use of cosmetics and locus of control, suggesting that cosmetic products are used to achieve an attractive appearance. Given that men seem to prefer women with facial make-up, it is likely that women may, consciously or unconsciously, use this improvement of visible skin condition to ultimately increase their mating success through the enhancement of facial attractiveness. A more recent study by Nash et al. supports the hypothesis that women can successfully employ cosmetic products to manipulate their appearance. They found that, in contrast to bare skin, Caucasian women who wore makeup were perceived as healthier and more confident, as well as having greater earning potential and more prestigious jobs. Most studies of this nature are conducted with college students or middle-aged women, although the positive effect on self-perception because of the use of facial makeup has also been validated with elderly women aged 60–96 years.
对应中文
重要的是，没有瑕疵的面部皮肤也会让没有皮肤病的健康女性对吸引力产生积极的看法。在Mulhern等人的一项研究中，一位美容师给10名女性志愿者做了5种可能的化妆方法：(1)不化妆，(2)只做粉底，(3)只做唇妆，(4)只做眼部化妆，(5)做完整面部化妆。结果显示，完整化妆后的面孔比不化妆的面孔更具吸引力。此外，研究还发现，某些面部区域的吸引力评分也会受到评分者性别的影响。女性认为眼妆对吸引力的影响最大，而男性的眼妆和皮肤粉底都会影响他们的吸引力评分。根据化妆品对患有皮肤病的住院患者心理健康的影响，化妆品的使用也会增强健康女性的自尊，因为它会积极影响自我认知和他人的认知。此外，Cash等人报告了化妆品的使用和控制点之间的系统关系，表明化妆品是用来获得吸引人的外表的。考虑到男性似乎更喜欢脸部化妆的女性，女性很可能会有意识或无意识地利用这种可见皮肤状况的改善，通过增强面部吸引力来最终提升择偶成功的概率。Nash等人最近的一项研究支持了这样的假设，即女性可以成功地使用化妆品来控制自己的外表。他们发现，与裸露皮肤相比，化妆的高加索女性被认为更健康、更自信，而且有更高的收入潜力和更有声望的工作。大多数这方面的研究都是针对大学生或中年女性进行的，尽管60-96岁的老年女性也证实了化妆对自我认知的积极影响。
英文原文
Given the importance that humans attach to skin appearance, evolutionary psychologists have proposed that skin condition, particularly that of women, may signal aspects of mate value (e.g. age and health). Findings that disfiguring skin disorders, such as acne vulgaris and hirsutism (male pattern of body hair in women), reflect elevated androgen levels in blood plasma and may thus have consequences on an individual’s reproductive potential, support this hypothesis. Of note, Bunker et al. also showed that 83% of women with acne had polycystic ovaries. The polycystic ovary syndrome is the most common endocrine disorder among women of reproductive age and is regarded as a leading cause of infertility.
对应中文
考虑到人类对皮肤外观的重视，进化心理学家提出了皮肤状况，特别是女性，可能标志着配偶价值的各个方面 (例如年龄和健康)。研究发现，毁容性皮肤疾病，如寻常痤疮和多毛症（女性体毛的男性模式），反映了血浆中雄激素水平的升高，因此可能对个体的生殖潜力产生影响，支持这一假设。值得注意的是，Bunker等人还显示83%的女性痤疮患者有多囊卵巢。多囊卵巢综合征是育龄妇女中最常见的内分泌紊乱，被认为是不孕不育的主要原因。
The human skin
人的皮肤
英文原文
Human skin accounts for one-sixth of total body weight , and is the largest, independent endocrine organ in the body. It consists of numerous components that give the skin a complex, multi-layered structure. Skin appearance is determined primarily by its colouration and surface topography.
对应中文
人体皮肤占总体重的六分之一，是人体内最大、独立的器官。它由许多成分组成，使皮肤具有复杂的多层结构。皮肤外观主要由其颜色和表面形貌决定。
英文原文
Skin pigmentation, leading to skin colour differences among different ethnic groups, is a highly heritable trait. So far, six genes have been identified in the expression of normal pigmentation, and there is evidence that several additional genes may play a role in skin, hair, and iris pigmentation. The colouration of human skin is determined by only four major pigments: carotenoids of exogenous origin (yellow) and endogenously produced melanin (brown) in the epidermis, oxygenated haemoglobin (red) and reduced haemoglobin (red-blue) in the capillaries and the venules of the dermis. Of these, the chromophores melanin and haemoglobin are the major determinants of differences in skin colour between individuals, with melanin playing the primary role. Interestingly, it has been reported that women differ from men in these two main components of skin colour. That is, the skin of women is generally poorer in melanin and (oxygenated) haemoglobin than that of men . This appears to be a genuine biological sexual dimorphism. In women, lightness of skin colour correlates with the ratio of second finger length to fourth finger length, a possible biomarker for prenatal sex steroids. Furthermore, women were also reported to have greater concentrations of carotene within their skin. Besides the four chromophores, the structural dermal protein collagen, additionally, contributes to skin colouration by scattering light in the visible spectrum.
对应中文
皮肤色素沉着导致不同种族之间的肤色差异，是一种高度可遗传的特征。到目前为止，在正常色素沉着的表达中已经确定了六个基因，而且有证据表明，另外几个基因可能在皮肤、头发和虹膜色素沉着中起作用。人类皮肤的颜色只由四种主要色素决定：表皮中的外源性类胡萝卜素(黄色)和内源性黑色素(棕色)，毛细血管和真皮小静脉中的氧合血红蛋白(红色)和还原血红蛋白(红色-蓝色)。其中，发色团黑色素和血红蛋白是决定个体间肤色差异的主要因素，其中黑色素起主要作用。有趣的是，据报道，女性在这两种主要肤色成分上与男性有所不同。也就是说，女性皮肤的黑色素和(含氧)血红蛋白通常比男性少。这似乎是一种生物性的两性异形。在女性中，肤色的明度与第二指长度和第四指长度的比率（2D:4D）相关，这是产前性类固醇激素的一个可能的生物标记物。此外，据报道，女性皮肤中的胡萝卜素浓度更高。除了四种发色体外，结构真皮蛋白胶原还通过在可见光光谱中散射光来促进皮肤着色。
英文原文
In humans, melanin can be found in two forms: eumelanin and phaeomelanin. The former chromophore is a black-brown pigment and, because of its location within the skin, hair, and eyes, it is also called ‘cutaneous’ melanin. Phaeomelanin, however, varies in colour from yellow to reddish brown and is also found in the skin and eyes, as well as in hair, while in red hair, it is found in high concentrations. In hair, varying proportions of the two pigments produce a wide range of colours, from the original black to brown, flaxen, golden, and red. Phaeomelanin, however, is less photostable than eumelanin and also occurs in less density . Both pigments are synthesized by melanocytes, which are dendritic cells located in the basal layer of the epidermis. This synthesis process is called melanogenesis and is catalysed by the enzyme tyrosinase. Melanocyte activity is influenced by a variety of stimuli, such as UV-radiation , melanocyte stimulating hormones, adrenocorticotropic hormone and corticosterone . After melanin synthesis, melanin chromophores are transferred in discrete packages (melanosomes) along the dendritic processes of the melanocytes and delivered into surrounding keratinocytes by exoand endocytosis. Once within keratinocytes, melanin species co-localize within membranous structures. Interestingly, the number of melanocytes is actually equal in human ethnic groups, so that the melanin component of skin colour is determined solely by the size and pattern of distribution of melanosomes, the eumelanin and phaeomelanin content within the melanosomes, and metabolic and tyrosinase activity within the melanocytes.
对应中文
在人类中，黑色素有两种形式：真黑色素和棕黑素。前一种发色团是一种黑褐色色素，因为它位于皮肤、头发和眼睛内，所以也被称为“皮肤”黑色素。然而，褐黑素的颜色从黄色到红棕色不等，在皮肤和眼睛以及头发中也有发现，而在红色头发中，它的浓度很高。在头发中，这两种色素的不同比例会产生各种各样的颜色，从最初的黑色到棕色、淡黄色、金色和红色。然而，棕黑素比真黑素更稳定，而且密度也较低。这两种色素都是由黑色素细胞合成的，黑质细胞是位于表皮基底层的树突状细胞。这个合成过程被称为黑素合成，由酪氨酸酶催化。黑素细胞活性受多种刺激的影响，如紫外线照射、黑素细胞刺激激素、促肾上腺皮质激素和皮质酮。黑色素合成后，黑色素发色团沿着巨噬细胞的树突以离散包(黑素小体)传递，并通过外吞和内吞输送到周围的角质细胞。一旦与黑色素细胞结合，黑色素物种就会与膜结构共同定位。有趣的是，在人类种族中，黑色素细胞的数量实际上是相等的，因此肤色中的黑色素成分仅由黑色素小体的大小和分布模式、黑色素小体中的真黑色素和棕黑素含量以及黑色素细胞内的代谢和酪氨酸酶活性决定。
Skin surface topography
皮肤表面形貌
英文原文
The surface topography of the skin is basically determined by the structure of the dermis and the mechanical forces imposed on this tissue. It is characterized by regular patterns of intersecting lines and irregular dispersed pilosebaceous follicles and eccrine pores. The main mechanical roles of the human skin are (1) to instantly and/or permanently match dynamic changes in shape and volume of the viscera and adipose tissue, (2) to protect them against external mechanical stress and (3) to facilitate, via palmar and plantar skin, the gripping of objects and negotiation of the surrounding environment.
对应中文
皮肤的表面形貌基本上由真皮的结构和施加在该组织上的机械力决定。其特点是有规则的相交线和不规则分散的皮脂腺毛囊和小汗腺毛孔。人类皮肤的主要机械作用是(1)即时和/或永久地匹配内脏和脂肪组织的形状和体积的动态变化，(2)保护它们免受外部机械应力的影响，以及(3)通过手掌和足底皮肤便于抓住物体和与周围环境协调。
英文原文
The skin is composed of three primary layers, each with varying mechanical properties: the superficial layer [stratum corneum (SC)], the epidermis and the dermis. These three layers cover the hypodermis (also referred to as subcutaneous adipose layer or subcutis).
对应中文
皮肤由三个主要层组成，每层具有不同的机械性能：浅层[角质层（SC）]、表皮和真皮。这三层覆盖在皮下（也称为皮下脂肪层或皮下组织）。
英文原文
In their review, Pie ́rard et al.describe four types of wrinkles, which result from structural changes in the skin layers elucidated above. Depending on their histological aspects, pathogenesis, orientation and depth they are classified as (1) atrophic, (2) elastotic, (3) expressional and (4) gravitational wrinkles. Atrophic wrinkles are fine, almost parallel lines, which vanish when the skin is put under transversal tension. They occur because of collagen degradation both in the dermis and the hypodermis. Elastotic wrinkles, however, become progressively permanent lines, which do not lessen upon stretching. As a result of an accumulation of abnormal, thickened, tangled, and non-functional fibres of elastin in and around these wrinkles (histologically known as solar elas- tosis), the skin takes on a characteristic ‘cobblestone’ appearance and becomes significantly more rigid. Expressional wrinkles gradually become permanent furrows, caused by the repeated contraction of the muscles of facial expression (the frown lines, glabellar lines and the ‘crow’s-feet’ being typical examples). Expressional wrinkles are of a lower frequency and higher amplitude than those described previously. Finally, gravitational wrinkles result from folding and sagging of the skin, which has lost its turgidity, under its own weight. The structural changes responsible for these changes are found in the hypodermis.
对应中文
在他们的综述中，Piérard等人描述了四种类型的皱纹，这些皱纹是由上述皮肤层结构变化引起的。根据其组织学特征、致病性、方向和深度，它们被分为（1）萎缩性皱纹、（2）弹性皱纹、（3）表情皱纹和（4）重力性皱纹。萎缩性皱纹是细小的、几乎平行的线条，当皮肤受到横向张力时，这些线条就会消失。它们的发生是因为真皮和皮下组织中的胶原蛋白降解。然而，弹性皱纹会逐渐变成永久的线条，伸展后丝毫不会减少。由于这些皱纹及其周围聚集了异常、增厚、缠结和无功能的弹性蛋白纤维（组织学上称为日光性弹性变性），皮肤呈现出典型的“鹅卵石”外观，并变得更加坚硬。面部表情皱纹逐渐成为永久性皱纹，由面部表情肌肉反复收缩引起（皱眉纹、眉间纹和“鱼尾纹”就是典型的例子）。与前面描述的相比，表情皱纹的频率更低、幅度更大。重力性皱纹是由于皮肤在自身重量的作用下折叠和下垂造成的，皮肤已经失去了其本身的饱和度。引起这些现象的结构改变见于皮下组织。
Skin ageing
皮肤衰老
英文原文
The ageing process represents a steady accumulation of cell and tissue change as the result of progressive disorder of regulatory mechanisms and an associated reduction in systemic reserves to counter stress and disease. The human skin undergoes an ageing process in a similar manner as the viscera (at least in non sun-exposed sites) and, thus, represents a unique visible indicator of systemic age. Wrinkling and changes in pigmentation are obvious signs of cutaneous ageing, influenced by both intrinsic and extrinsic factors. However, as both factors interact, it is often difficult to assign phenotypic consequences of the ageing process to one or the other.
对应中文
衰老过程代表着细胞和组织变化的稳定积累，这是调节机制的进行性紊乱以及与之相关的对抗压力和疾病的系统储备减少的结果。人类皮肤经历了与其他内脏器官类似的衰老过程（至少在非阳光照射的部位），因此代表了系统年龄的独特可见指标。皱纹和色素沉着变化是皮肤衰老的明显标志，受内外因素的影响。然而，由于这两个因素相互作用，往往很难将老化过程的表型后果分配给一个或另一个。
Intrinsic ageing
内源性衰老
英文原文
Intrinsic ageing processes are structural changes that occur as natural consequences of ageing and are determined genetically . Consequently, these processes are also seen in most internal organs. Intrinsic ageing refers, in particular, to a decrease in the gonadal production of oestrogen in females (menopause) and testosterone in males (andropause), the adrenal production of the androgen dehydroepiandrosterone (DHEA) and its metabolite DHEA sulphate (DHEAS), and the activity of growth hormone, as well as of the insulinlike growth factor (somatopause) (reviewed in). Lowered secretion of these hormones is thought to be linked to decreased proliferation capacity leading to senescence and altered biosynthetic activity of the skin.
对应中文
内源性衰老过程是作为衰老的自然结果发生的结构性变化，并由基因决定。因此，这些过程也见于大多数内部器官。内源性衰老尤其是指女性(更年期)和男性(男性更年期）性腺等内分泌器官产生的内分泌因子减少，包括性腺产生的雌激素和睾酮、肾上腺产生的雄激素脱氢表雄酮(DHEA)及其代谢产物脱氢表雄甾酮(DHEAS)，以及生长激素和胰岛素样生长因子(躯体更年期)的活性降低(见文献)。这些荷尔蒙分泌的减少被认为与导致皮肤衰老和生物合成活动改变的增殖能力降低有关。
Extrinsic ageing
外源性衰老
英文原文
Extrinsic ageing is driven by environmental factors, including exposure to solar UV-radiation (e.g), IR-radiation), smoking, ozone, and dust, and involves changes in cellular biosynthetic activity and a progressive disorganization of the dermal matrix. Among these environmental factors, casual exposure to solar UV-radiation is the most potent and prominent driver of so-called ‘premature skin ageing’, causing the production of free radicals or ‘reactive oxygen species’ (ROS) which, by nature, damage virtually every class of cell component, including protein, lipid and nucleic acid. For instance, it is now believed that free radicals can damage the guanine residues that make up 50% of the telomere overhang structure, accelerating telomere shortening and, thus, speeding up premature ageing. These reactive species have also been shown to stimulate the degeneration of dermal matrix components, e.g, collagen and elastin, leading to an accumulation of compromised, so-called ‘elastotic’ tissue and associated mechanical failure. ROS are also known to drive a variety of pigmentation disorders, resulting in selective over- (e.g., lentigos, diffuse hyperpigmentation) and under- (e.g. guttate idiopathic hypomelanosis) expression of melanin, causing a progressive visible heterogeneity in melanin distribution (reviewed in).
对应中文
外源性衰老是由环境因素驱动的，包括暴露于太阳紫外线辐射（例如红外辐射）、吸烟、臭氧和灰尘，以及细胞生物合成活动的变化和皮肤基质的渐进性紊乱。在这些环境因素中，偶然暴露在太阳紫外线辐射下是所谓“皮肤过早老化”的最有力和最突出的驱动因素，导致自由基或“活性氧”（ROS）的产生，而活性氧从本质上来说，几乎会损害包括蛋白质、脂质和核酸在内的所有细胞成分。例如，现在人们认为自由基可以破坏占端粒上悬结构50%的鸟嘌呤，加速端粒缩短，从而加速过衰老。这些活性物质还被证明能刺激真皮基质成分(如胶原和弹性蛋白)的退化，导致受损的所谓“弹性”组织的堆积和相关的机械故障。众所周知，活性氧还可引起各种色素沉着障碍，导致黑色素的选择性过度表达 (如雀斑、弥漫性色素沉着)和表达不足(如点状特发性黑色素沉着症)，结果就是黑色素分布呈进行性明显的异质性(见综述)。
REFERENCES
1. Samson N, Fink B, Matts PJ.Visible skin condition and perception of human facial appearance.Int J Cosmet Sci. 2010 Jun;32(3):167-84.