Seasonal changes in the physiological features of healthy and sensitive skin
Abstract
摘要
英文原文
Background: The effects of seasonal factors on sensitive skin (SS) have been reported intensively, but the mechanisms still remain poorly understood.
Objective: To investigate the effects of seasonal factors on SS, by comparing the physiological changes in the healthy skin and different subgroups of SS with seasonal variation.
Methods: Through a questionnaire survey, lactic acid sting test, and capsaicin test, qualified subjects were classified into four groups: healthy skin, only lactic acid sting test positive (LAST(+)/CAT(−)), only capsaicin test positive (LAST(−)/CAT(+)), and both positive (LAST(+)/CAT(+)). Skin physiological parameters were measured in winter and summer.
Conclusions: Seasonal variation influences the skin barrier function of different types of sensitive skin at different levels. We therefore strongly suggest that, with seasonal variation, different treatments will be undertaken for different subgroups of sensitive skin.
对应中文
背景：季节因素对敏感皮肤(SS)的影响已被广泛报道，但其作用机制尚不清楚。
目的：通过比较在季节变化下健康皮肤及SS不同亚群的生理改变，研究季节因素对SS的影响
方法：通过问卷调查、乳酸刺痛试验、辣椒素试验，将合格的受试者分为4组：皮肤健康组、乳酸刺痛试验阳性组(LAST(+)/CAT(−))、辣椒素试验阳性组(LAST(−)/CAT(+))、两组均阳性组(LAST(+)/CAT(+))，在冬季和夏季测定皮肤生理参数。
结论：季节变化对不同类型敏感皮肤的皮肤屏障功能有不同程度的影响。因此，我们强烈建议，随着季节的变化，对不同的敏感皮肤亚型采取不同的治疗方法。
INTRODUCTION
引言
英文原文
Sensitive skin (SS) is a widespread condition that presents a reduced tolerance to frequent and prolonged use of cosmetics and toiletries.However, it is not easy to identify sensitive skin because of the inherent characteristics of distinctly subjective discomfort accompanying with or without rare visible signs. A self-assessment questionnaire survey, therefore, is considered a classic evaluation method, and has been applied widely in the studies of SS.Consequently, several epidemiological studies were conducted on influencing factors to determine the pathogenesis of SS. Among them, a common phenomenon was found to be closely related to climatic conditions, such as temperature, sun, and wind.A survey conducted by Misery et al.showed that SS was more frequent in summer than in winter. However, the author did not clearly explain the mechanism. In contrast, another study showed that individual with SS experienced a stronger sting response to lactic acid in winter than in summer, speculating that heightened neurosensory input and defective barrier function associated with winter xerosis are potential mechanisms of SS.Unfortunately, no further investigation was performed to test this hypothesis.
对应中文
敏感皮肤(SS)是一种普遍存在的疾病，表现为对频繁和长时间使用化妆品和对化妆品的耐受性下降。然而敏感皮肤的固有特征是主观上明显的不适，并伴有或不伴有罕见的可见症状，因此不易被识别。因此，自我评估问卷调查被认为是一种经典的评价方法，并被广泛应用于SS的研究中。因此，人们对SS发病的影响因素进行了多项流行病学研究。其中，一个普遍现象与气候条件密切相关，如温度、阳光和风。一项由Misery等人进行的调查显示，SS在夏季比冬季更频繁。然而，作者并没有清楚地解释这一机制。相反，另一项研究表明，在冬季SS患者对乳酸的刺痛反应比夏季更强烈，推测SS的潜在机制是冬季干燥相关的神经感觉输入增强和屏障功能缺陷。遗憾的是，没有进行进一步的调查来验证这一假设。
英文原文
With the development of bioengineering technology, noninvasive tests were considered more accurate and promising methods for evaluating SS.Previous studies have demonstrated marked differences between SS and general health, by evaluating skin physiological functions including transepidermal water loss (TEWL), stratum corneum hydration (SCH), epidermal density, and current perception threshold of peripheral sensory nerve fibers (CPT).The studies also suggested that defective barrier function was a vital mechanism of SS, which can result in heightened neurosensory input and reduced protection from extrinsic stimuli.Additionally, it has been reported the barrier function in healthy population could develop adaptive changes in different seasons.Therefore, it has been hypothesized that the increased complaints regarding SS with changing seasons are attributed to the changes in epidermal barrier function, and its change level.
对应中文
随着生物工程技术的发展，无创检测被认为是评估SS更准确和更有发展的方法。以前的研究通过评估皮肤生理功能，包括经表皮失水（TEWL）、角质层水化（SCH）、表皮密度和周围感觉神经纤维的电流感知阈值（CPT），证明了SS与一般健康状况之间的明显差异。研究还表明，屏障功能缺陷是SS的一个重要机制，它可以导致神经感觉输入的增加和对外在刺激的保护减少。此外，有报道称健康人群的屏障功能在不同季节会发生适应性变化。因此，有假说认为随着季节的变化，SS发病率增加与表皮屏障功能及其变化水平有关。
英文原文
Therefore, the aim of our study is to preliminarily investigate the changes in skin physiological parameters as a function of season and their relationship with sensitive skin. These parameters include TEWL, SCH, pH, CPT, cutaneous blood flow (CBF), epidermal thickness, and density. Among them, TEWL, SCH, pH, and epidermal thickness and density reflect the stratum corneum barrier function based on different mechanisms. CPT represents neuronal sensitivity, the lower its values are, the stronger the response to external stimulus is. CBF reflects superficial microcirculation which is one of the prerequisites for maintaining skin normal functions. According to the questionnaire survey, lactic acid sting test (LAST), and capsaicin test (CAT), all qualified subjects were divided into four groups as follows: healthy skin, only lactic acid sting test positive (LAST(+)/CAT(−)), only capsaicin test positive (LAST(−)/CAT(+)) and both positive (LAST(+)/CAT(+)), and then their skin physiological parameters were measured in winter and summer, respectively.
对应中文
因此，本研究的目的是初步探讨皮肤生理参数随季节的变化及其与敏感皮肤的关系。这些参数包括TEWL、SCH、pH、CPT、皮肤血流(CBF)、表皮厚度和密度。其中，水分流失率(TEWL)、SCH、pH、表皮厚度和密度反映了角质层屏障功能的不同机制。CPT代表神经元的敏感性，其值越低，表示对外界刺激的反应越强烈。CBF反映了浅表微循环，是维持皮肤正常功能的前提条件之一。根据问卷调查、乳酸刺痛试验(LAST)和辣椒素试验(CAT)，将所有合格的受试者分为以下四组：健康皮肤、仅乳酸刺痛试验阳性(LAST(+)/CAT(−))、仅辣椒素试验阳性(LAST(−)/CAT(+))和双阳性(LAST(+)/CAT(+))，然后分别在冬季和夏季对测定其皮肤生理参数。
MATERIALS AND METHODS
材料和方法
Study site and population
研究地点和人口
英文原文
The study was conducted in Shanghai, located in the east of China, which has four distinct seasons. The climate is favorable in spring and autumn, but it is the opposite in summer and winter. Here, the summer is from June to August, characterized by high temperature (35–40°C) and absolute humidity (17.26–22.73 kg/m³), whereas it is cold (0–5°C) and low absolute humidity (6.10 ~ 7.04 kg/m³) in winter from December of the previous year to February of the following year. In view of the climate feature, the study was finally performed in summer and winter.
对应中文
这项研究是在中国东部上海进行的，这里有四个不同的季节。春秋两季气候适宜，夏冬两季气候相反。上海的夏季为6-8月，气温高(35-40℃)，绝对湿度高(17.26-22.73 kg/m³)；冬季从去年12月到次年2月，气温寒冷(0-5℃)，绝对湿度低(6.10-7.04 kg/m³)。考虑到气候特点，最终选择夏季和冬季进行研究。
英文原文
A total of 140 qualified subjects, aged 20–60 years were enrolled in the study. First, all subjects were classified into four groups according to the questionnaire survey, LAST, and CAT in the winter of 2018. Physiological parameters were measured in the winter of 2018 and summer of 2019. All subjects had stayed for at least 6 years in Shanghai, were free of active skin diseases (eczema, acne, seborrheic dermatitis, etc.). The written informed consent was obtained from all subjects prior to the study.
对应中文
本研究共纳入140名符合条件的受试者，年龄20-60岁。首先，根据2018年冬季的问卷调查、LAST和CAT，将所有受试者分为四组。生理参数测定分别于2018年冬季和2019年夏季进行。所有受试者在上海居住至少6年，无活动性皮肤病(湿疹、痤疮、脂溢性皮炎等)。在研究前所有受试者均获得书面知情同意书。
DISCUSSIONS
讨论
英文原文
Previous studies have suggested that SS is not a single condition and encompasses different categories based on different mechanisms.In this study, according to the questionnaire, LAST, and CAT, volunteers were divided into four subgroups: healthy skin group, LAST(+)/CAT(−) group, LAST(−)/CAT(+) group, and LAST(+)/ CAT(+) group. Capsaicin, as a natural agonist of the transient re- ceptor potential vanilloid subfamily, member 1, is suggested to be a reliable tool to identify SS with heightened neuroreactivity.LAST has been proposed as the best predictor available for SS,and the existing studies have indicated higher TEWL in lactic acid stinger.Namely, LAST(+) is equal to a SS with an impaired skin barrier.It implies that LAST(+)/CAT(−), LAST(−)/CAT(+), and LAST(+)/CAT(+) represented SS with a defective barrier function, heightened neural reaction, and a mix of these factors, in the present study. With growing research, more scientists and dermatologists have attached importance to the effect of the environment on SS. Consequently, we carried out a comprehensive comparison of skin physiological parameters between the healthy skin and different types of SS with seasonal variation.
对应中文
以前的研究表明，SS不是一种单一的疾病，而是根据不同的机制分为不同的类别。在这项研究中，根据问卷调查、LAST和CAT，志愿者被分为四个亚组：健康皮肤组、LAST(+)/CAT(-)组、LAST(-)/CAT(+)组和LAST(+)/ CAT(+)组。辣椒素，作为一种天然的瞬态受体电位香草素亚家族的激动剂成员1，被认为是一种可以鉴别具有高度神经反应性的SS可靠的工具。LAST已被认为是SS的最佳预测因子，现有研究表明乳酸刺痛试验阳性水分流失较高。也就是说，LAST(+)等于皮肤屏障受损的SS。这意味着在本研究中，LAST(+)/CAT(-)、LAST(-)/CAT(+)和LAST(+)/CAT(+)代表屏障功能缺陷、神经反应增强以及这些因素混合的SS。随着研究的不断深入，越来越多的科学家和皮肤科医生开始重视环境对SS的影响。因此，我们对健康皮肤和具有季节性变化的不同类型的SS的皮肤生理参数进行了综合比较。
英文原文
Transepidermal water loss is a universally used indicator of skin barrier function.Our results showed that TEWL values of the LAST(+)/CAT(−) and LAST(+)/CAT(+) groups were significantly higher than that of the healthy skin group in both winter and summer, which was in line with the previous studies.The results also indirectly supported that LAST was an effective method to evaluate facial sensitive skin with a defective skin barrier. However, the level of change in TEWL in SS was not different from the healthy skin group in our study. A possible reason is that TEWL of the LAST(+)/ CAT(−) and LAST(+)/CAT(+) groups in summer was as high as that of the LAST(−)/CAT(+) and the healthy skin groups in winter. Obviously, the skin barrier function of the LAST(+)/CAT(−) and LAST(+)/CAT(+) groups is much worse than the other two groups under the equivalent level of change in TEWL in winter. The surface skin pH was similar to the results of TEWL in winter, which was higher in the LAST(+)/CAT(−) and LAST(+)/CAT(+) groups compared to that in the health. And the level of change in the skin pH in the LAST(+)/CAT(−) and LAST(+)/CAT(+) groups was also higher than the health. The study from Hachem et al.suggested that the acidic milieu of the skin surface played a crucial role in cutaneous permeability barrier homeostasis, stratum corneum integrity, and cohesion. It means further serious effects on SS with a defective skin barrier by seasonal variation.
对应中文
经表皮失水是衡量皮肤屏障功能的常用指标。我们的结果显示，在冬季和夏季，LAST(+)/CAT(-)和LAST(+)/CAT(+)组的TEWL值都明显高于健康皮肤组，这与以前的研究一致。结果间接支持LAST是评估面部敏感皮肤皮肤屏障缺陷的有效方法。然而，在我们的研究中，SS的TEWL变化水平与健康皮肤组没有区别。一个可能的原因是夏季LAST(+)/CAT(-)和LAST(+)/CAT(+)组的TEWL与冬季LAST(-)/CAT(+)和健康皮肤组的一样高。显然，在冬季同等水平的TEWL变化下，LAST(+)/CAT(-)和LAST(+)/CAT(+)组的皮肤屏障功能要比其他两组差很多。表面皮肤pH值与冬季TEWL的结果相似，与健康组相比，LAST(+)/CAT(-)和LAST(+)/CAT(+)组的pH值较高。而LAST(+)/CAT(-)和LAST(+)/CAT(+)组的皮肤pH值变化水平也高于健康组。Hachem等人的研究表明，在皮肤通透性屏障动态平衡、角质层完整性和凝聚力方面皮肤表面的酸性环境起着至关重要的作用。这意味着季节性变化对皮肤屏障缺陷的SS有进一步的严重影响。
英文原文
In summer, SCH of the LAST(+)/CAT(−) and LAST(+)/CAT(+) groups was higher than the health, but no statistically significant difference was observed, similar to the study by An et al.However, as the temperature lowed through winter, SCH of the LAST(+)/CAT(−) and LAST(+)/CAT(+) groups decreased markedly, and was lower than that of the LAST(−)/CAT(+) and healthy skin groups. The previous studies have suggested lower temperature in winter resulted in drier skin and more greatly influenced an impaired skin barrier.Taken together, these seasonal changes result in double influences on the SCH of SS with a defective skin barrier. The findings also suggest that differential moisturization treatments need to be undertaken for the LAST(+)/CAT(−) and LAST(+)/CAT(+) groups as per seasonal changes.
对应中文
与An等人的研究相似，在夏季，LAST(+)/CAT(-)和LAST(+)/CAT(+)组的SCH高于健康组，但没有观察到统计学上的显著差异。然而，随着冬季温度的降低，LAST(+)/CAT(-)和LAST(+)/CAT(+)组的SCH明显下降，并且低于LAST(-)/CAT(+)和健康皮肤组。以前的研究表明，冬季温度较低，导致皮肤更干燥，对皮肤屏障受损的影响更大。总的来说，这些季节性变化对皮肤屏障受损的SS的SCH有双重影响。研究结果还表明，针对LAST(+)/CAT(-)和LAST(+)/CAT(+)组，需要根据季节变化进行不同的保湿治疗。
英文原文
Studies conducted by Lee et al.and Kim et al. showed that quantitative measurement of facial current perception threshold was a useful test for the identification of SS with heightened neural reaction. The current frequencies at 250 Hz and 5 Hz are the main nerve fibers that mediate irritation sensations, such as itching, burning, and stinging. In previous studies, significant differences were observed in the two current frequencies between SS and healthy skin However, in our study, a significant difference was observed only in CPT at 5 Hz between the LAST(−)/CAT(+), LAST(+)/ CAT(+) groups, and the LAST(+)/CAT(−), healthy skin groups in both winter and summer. In the present study, qualified subjects were those that met simultaneously the criteria of the screening questionnaire, 10% lactic acid sting test, and 1.0 × 10−5 capsaicin test. Different study populations were potential factors for producing inconsistent results. In addition, no difference between two seasons was observed in three current frequencies except CPT at 250 Hz in LAST(+)/CAT(+) in the study. The climate seems to be a faintly influential factor for CTP. The claim is partly verified by Xia’s study in which changing skin temperature did not give rise to CPT variation.It is well known the increased permeability of external irritants has been acknowledged in SS with an impaired skin barrier,and repeated stimuli can reduce the sensitivity of neural response.This might be the reason why no difference observed in the CPT at 5 Hz between the LAST(+)/CAT(−) and healthy skin groups in the study.
对应中文
Lee等人和Kim等人的研究表明，定量测量面部电流感知阈值是一种识别神经反应增强的SS的有用测试。250HZ和5HZ的电流频率是介导刺激感觉的主要神经纤维，如瘙痒、燃烧和刺痛。在以前的研究中，SS和健康皮肤在这两个电流频率上有明显的差异。然而，在我们的研究中，在冬季和夏季，LAST(-)/CAT(+)、LAST(+)/CAT(+)组和LAST(+)/CAT(-)、健康皮肤组之间仅在5HZ的CPT观察到明显差异。在本研究中，合格的受试者是同时符合筛选问卷、10%乳酸刺痛试验和1.0×10-5辣椒素试验标准的人。不同的研究人群是产生不一致结果的潜在因素。此外，在研究中，除了LAST(+)/CAT(+)组250Hz的CPT外，三个电流频率没有观察到两个季节的差异。气候似乎是CTP一个微弱的影响因素。在一定程度上夏教授的研究证实了这一说法，即皮肤温度的变化不会引起CPT的变化。众所周知，在皮肤屏障受损的SS中，外部刺激物的渗透性增加，重复刺激可降低神经反应的敏感性。这可能是在5Hz的CPT研究中LAST(+)/CAT(-)组和健康皮肤组之间没有观察到差异的原因。
DISCUSSIONS
讨论
英文原文
Similar to the results of previous studies,no difference was observed in the CBF of each group in summer. However, the CBF values increased significantly in both SS and the healthy skin in winter compared to that in summer. It is well known that CBF plays a crucial role in supplying nutrition, and oxygen and heat regulation of the epidermis.The temperature of the ambient environment greatly influences the skin surface temperature.In order to balance the skin temperature, CBF values increased sharply in the low winter temperature. However, lower CBF was observed in the LAST(+)/CAT(−) and LAST(+)/CAT(+) groups compared to the healthy skin group, which could be because of: abnormal structure of the superficial blood vessels, failure of stimulus conduction, or both. It might be also the reason why individual complain of SS is more often in winter.
对应中文
与以前的研究结果类似，在夏季各组的CBF没有观察到差异。然而，与夏季相比，SS和健康皮肤的CBF值在冬季都明显增加。众所周知，CBF在供应营养、氧气和表皮的热量调节方面起着至关重要的作用。为了平衡皮肤温度，CBF值在冬季低温下急剧增加。然而，与健康皮肤组相比，LAST(+)/CAT(-)和LAST(+)/CAT(+)组的CBF较低，这可能是由于：浅表血管结构异常，刺激传导失败，或两者都有。这也可能是很多人抱怨SS在冬季更频繁的原因。
英文原文
High-frequency ultrasound technology has been introduced to measure skin thickness and density for the diagnosis and monitoring of skin diseases and the evaluation of healthy skin characterization.Due to different anatomic sites and measurement methods, the epidermal thickness in the study was different from the results of studies by Sandby et al. and Ma et al. But as reported by Ma et al,there was no difference between SS and the healthy skin in either winter or summer. Unlike the epidermal thickness, epidermal echo density of the healthy skin was distinctly higher than that of SS in both winter and summer. Unfortunately, very few studies have reported the histological basis of epidermal density. Wortsman suggested that the epidermal echogenicity depends largely on keratin.Although till date, no evidence has demonstrated abnormal expression of keratin, it has reported corneocyte mutation, irregular arrangement, smaller size, or less number of corneocytes in SS.Obviously, it is urgently necessary to conduct more studies to clarify the factors influencing epidermal density. Compared to winter, epidermal density of only the healthy skin group decreased markedly in summer. However, the change did not cause skin barrier dysfunction, suggesting that healthy skin could perfectly regulate the skin structure to adapt to climatic change, unlike SS.
对应中文
高频超声技术被引入测量皮肤厚度和密度，用于皮肤病的诊断和监测以及健康皮肤表征的评价。由于解剖部位和测量方法不同，本研究中的表皮厚度与Sandby等人和Ma等人的研究结果存在差异。但正如Ma等人报道的，SS与健康皮肤的表皮厚度在冬季、夏季均无差异。与表皮厚度不同，健康皮肤在冬季和夏季的表皮回声密度明显高于SS。不幸的是，很少有研究报道表皮密度的组织学基础。Wortsman认为，在很大程度上表皮回声依赖于角蛋白，虽然到目前为止还没有证据表明角蛋白的异常表达，但已有报道称，SS中角质细胞突变、排列不规则、体积较小或数量较少，显然，迫切需要进行更多的研究来阐明影响表皮密度的因素。与冬季相比，夏季只有健康皮肤组的表皮密度显著降低。然而，这种变化并没有导致皮肤屏障功能障碍，这表明健康的皮肤可以完美地调节皮肤结构，以适应气候变化，这与SS不同。
英文原文
It was shown in the study that SSS had a strong correlation with TEWL, SCH, pH, CPT at 5 Hz, and epidermal density. In addition, there was a strong correlation between SSB and TEWL, pH, CPT at 250 Hz and 5 Hz, and epidermal density. SSS and SSB have been reported to have a positive correlation with the severity of SS with skin barrier impairment and facial skin neurosensitivity.This means that different types of SS are affected by different physiological parameters. The targeted parameters play different roles in the occurrence and development of SS. Of note, as a component of the skin function, the parameters may interact with each other, that is, there are possible multiple colinear relations among them. There was another limitation in the study, all subjects were not determined again whether to be SS in summer. It has been reported there was difference in skin sensitivity as seasonal shift. Although seasonal changes in skin physiological parameters were observed in the study, it is unknown if the identical correlation with SSS and SSB still remains in summer.
对应中文
研究表明，SSS与TEWL、SCH、pH、5Hz的CPT和表皮密度有很强的相关性。此外，SSB与TEWL、pH、250HZ和5HZ的CPT以及表皮密度之间也有很强的相关性。据报道，SSS和SSB与皮肤屏障受损和面部皮肤神经敏感的SS的严重程度有正相关。这意味着不同类型的SS受到不同生理参数的影响。目标参数在SS的发生和发展中发挥不同的作用。值得注意的是，作为皮肤功能的组成部分，这些参数可能会相互影响，也就是说，它们之间可能存在着多重关系。该研究还有一个局限性，即所有受试者都没有再次确定在夏季是否是SS。据报道，随着季节的变化，皮肤敏感性也有差异。虽然在研究中观察到皮肤生理参数的季节性变化，但尚不清楚夏季是否仍保持与SSS和SSB的相同相关性。
英文原文
To sum up, SS with a defective barrier function is more sensitive to seasonal factors than healthy skin and SS with a heightened neural reaction. Combined with the analysis of the correlation with SS, it could be concluded that seasonal variation impacts different types of SS through multiple pathways at different levels. Therefore, for SS with an impaired skin barrier, the top priority is to repair the skin barrier, and an intensive moisturizing treatment is indispensable in the winter. For SS with a heightened neural reaction, it is necessary to apply sensory nerve inhibitors reasonably and to strengthen the skin barrier to reduce the input of exogenous stimuli in both seasons.
对应中文
总而言之，屏障功能有缺陷的SS比健康皮肤和神经反应增强的SS对季节性因素更敏感。结合与SS的相关性分析，可以得出结论，季节性变化通过多种途径在不同层面影响不同类型的SS。因此，对于皮肤屏障受损的SS，首要任务是修复皮肤屏障，在冬季进行密集的保湿护理是必不可少的。对于神经反应增强的SS，有必要合理应用感觉神经抑制剂，并加强皮肤屏障，以减少2个季节的外源性刺激输入。
REFERENCES
1.Jiang W, Wang J, Zhang H, Xu Y, Jiang C, Yang J, Liu W, Tan Y. Seasonal changes in the physiological features of healthy and sensitive skin. J Cosmet Dermatol. 2021 Oct 2.