The evaluation of neural and vascular hyper-reactivity for sensitive skin

Lactic acid sting test and capsaicin test differentially induce facial erythematous reaction in subjects with sensitive skin

BACKGROUND

Sensitivity skin (SS) is a common skin disorders, which have a various of clinical manifestation. Facial erythema is common objective symptom of SS. However, the reasons for the occurrence of erythema in sensitive skin are not fully understood.

AIMS

In this study, we preliminarily explain the possible factors inducing erythema of sensitive skin by evaluating facial erythematous reaction to lactic acid sting test (LAST) and capsaicin test (CAT) in subjects with sensitive skin.

METHODS

A total of 197 subjects were divided into five groups, that is, normal controls (NC), LAST-positive (LAST+ ), both LAST and CAT positive (L+ C+ ), both LAST and CAT negative (L- C- ) and CAT-positive (CAT+ ). Erythema index (EI), a* value, and tissue viability imaging (TIVI) were measured before and after LAST and CAT, The ΔEI, Δa*, and ΔTIVI before and after LAST and CAT were calculated, and the correlation between the scores of CAT, EI values, a* values, and TIVI values were analyzed to clarify the causes of facial erythema.

RESULTS

Our results showed that EI values and a* values were significantly higher in the L+ C+ and CAT+ group than in NC group, TIVI values were higher in the L+ C+ group than in NC group. ΔEI and Δa* values after LAST did not differ significantly among five groups. However, ΔEI values in L+ C+ group were higher than that in L- C- group, while Δa* values were higher in CAT+ group than in NC. Moreover, ΔTIVI values in L+ C+ group and CAT+ group were also significantly higher than that in NC group after capsaicin stimulation. CAT scores correlated positively with EI, a* and TIVI values.

CONCLUSION

Our results suggest that sensitive skin subjects with positive CAT are more likely to experience erythema reactions, and vasodilation is more pronounced after capsaicin stimulation. Reducing vascular and neural hyperreactivity could be therapeutic target in management of facial erythema in subjects with sensitive skin.

Rosacea and seborrheic dermatitis differentially respond to lactic acid sting and capsaicin tests in Chinese women

BACKGROUND

Although rosacea and seborrheic dermatitis share some symptoms of sensitive skin, whether they respond differently to lactic acid sting and capsaicin tests, common tests for diagnosis of sensitive skin, is unknown.

OBJECTIVES

To reveal the cutaneous responses to lactic acid sting (LAST) and capsaicin test (CAT) in females with either rosacea vs. seborrheic dermatitis.

METHODS

A total of 60 patients with rosacea, 20 patients with seborrheic dermatitis and 40 normal controls were enrolled in the study. Their skin sensitivity to stimuli were evaluated following topical application of either 10% lactic acid solution or 0.001% capsaicin solution. Transepidermal water loss (TEWL) rates and erythema indexes were also measured on the face.

RESULTS

In comparison to normal controls, the positive rate to either LAST or CAT was significantly higher in subjects with rosacea (p < 0.001), but not in that with seborrheic dermatitis. Similarly, individuals with rosacea displayed a higher positive rate to both LAST and CAT than those with seborrheic dermatitis and normal controls (p < 0.001). In parallel, the LAST scores and CAT scores in individuals with rosacea were significantly higher than in that with either seborrheic dermatitis or normal controls (p < 0.001). The baseline TEWL rates and erythema indexes were higher in individual with rosacea than in normal controls (p < 0.001). But the baseline TEWL rates and erythema indexes did not differ significantly between subjects with rosacea and that with seborrheic dermatitis. Moreover, LAST scores and CAT scores correlated positively with TEWL (p < 0.0001). TEWL rates were higher in CAT positive than in CAT negative subjects (p < 0.0001). Finally, erythema index correlated positively with CAT scores (p < 0.0001), but not with LAST scores (p = 0.0842).

CONCLUSIONS

Skin responses to LAST and CAT differ between individuals with rosacea and those with seborrheic dermatitis, possibly due to the differences in epidermal permeability barrier and the neurovascular hyperreactivity. The higher LAST and CAT scores, as well as positive rates of both LAST and CAT can be attributable to inferior permeability barrier and the neurovascular hyperreactivity in subjects with rosacea.

Cowhage-induced itch scores and the current perception threshold in assessing sensitive skin: An observational laboratory study

BACKGROUND

The diagnosis of sensitive skin remains nonuniform, and the underlying mechanism is unclear. Previous studies were inconsistent in the current perception threshold (CPT) measurement for sensitive skin; thus, the neural sensitivity of sensitive skin needs to be clarified.

OBJECTIVES

This study aimed to compare the CPT measurement and the cowhage test for sensitive skin and to investigate the correlation between CPT values and cowhage-itch scores.

METHODS

Participants with and without sensitive skin (n = 30, 30) were included. The cowhage test and CPT measurement with its related sensations were performed.

RESULTS

No difference was found in CPT between the sensitive and nonsensitive groups at either the site of the face or the forearm (5, 250, or 2000 Hz). Once the CPT was reached, sensations (itch, stinging, and throbbing) were significantly different between the two groups. Cowhage provoked more intense itch with a longer duration in the face (visual analog scale [VAS] score 1.90 ± 1.47 vs. 0.52 ± 0.90, p < 0.001; duration 3.80 ± 3.31 vs. 0.87 ± 1.43 min, p < 0.001) and forearm (VAS 2.53 ± 2.60 vs. 0.72 ± 1.06, p < 0.001; duration 3.37 ± 3.46 vs. 1.33 ± 2.14 min, p < 0.01) of the sensitive group compared with the nonsensitive group. Cowhage-induced itch and CPT-related itch (5 Hz) showed moderate correlations in both the face (r = 0.441, p < 0.001) and forearm (r = 0.491 p < 0.001) and weak correlations in the forearm (r = 0.323 at 250 Hz, p = 0.012; r = 0.376 at 2000 Hz, p = 0.003).

CONCLUSIONS

Cowhage test showed better performance in assessing the neural sensitivity of sensitive skin in comparison with the CPT measurement. Evaluation of CPT-related sensations may add valuable information to sensitive skin assessment.

The Challenges in Investigating the Pathogenesis of Sensitive Skin by Noninvasive Measurements: A Systematic Review

Sensitive skin (SS) is a common cutaneous condition that seriously affects people's quality of life, but studies of sensitive skin pathogenesis are unclear, the exploration are ongoing, and the biophysical properties of sensitive skin disagree with the study results. In this paper, we summarize the noninvasive biophysical and imaging instrumental methods used for sensitive skin and provide support for the classification of sensitive skin subtypes to prescribe precise treatment. PubMed and Web of Science databases were searched according to PRISMA guidelines for articles from January 1971 to May 2022 that used noninvasive biophysical or imaging methods to monitor adult subjects with sensitive skin. The quality of the included articles was determined based on 22 items of the STrengthening the Reporting of OBservational studies in Epidemiology (STROBE) statement. A total of 55 studies were included, representing 8 biophysical and 5 imaging methods and their applications in treatment efficacy evaluation studies. The biophysical parameter and cutaneous morphological property changes in sensitive skin subjects were observed. The quality of the studies was relatively low, and there was high variability in results between studies. Several parameters have shown tremendous potential in exploring the pathogenesis with different sensitive skin subtypes: type I may be detected with higher transepidermal water loss and lower stratum corneum hydration values, as well as with thinner epidermis with a shallower and more irregular honeycomb structure; Type II and III are more prone to higher blood flow, lower current perception threshold than normal skin. This systematic review identifies key reasons for the lack of uniform trends in noninvasive measurements and recommends the use of effective selection instruments or relevant parameters to explore the pathogenesis of sensitive skin, and to differentiate the subtypes of sensitive skin for achieving the precise treatment.

Will repeated Intense Pulsed Light (IPL) treatment sessions affect facial skin sensitivity? Results of a twelve-Month, prospective, randomized split-face study

BACKGROUND

Despite the widespread use of intense pulsed light (IPL) technology in cosmetic dermatology, the effects of its repeated use on facial skin sensitivity in healthy individuals remains unknown.

METHODS

Seventeen healthy female volunteers were included in the study. We measured objective biophysical parameters of the skin, including transepidermal water loss (TEWL), skin glossiness, thickness and density of the epidermis and dermis, sensory nerve current perception threshold (CPT), and regional blood flow before and after treatment at different time points.

RESULTS

Sixteen volunteers completed a follow-up of 12 months. The treated side of the face showed a decreased TEWL on D1 and D3, which reverted to normal on D7. Epidermal thickness increased and skin glossiness decreased on the treated side on D1, but returned to normal on D3. We found no statistically significant differences in CPT values or in regional blood flow volume and velocity, with the exception of D1, which exhibited a higher regional blood flow volume on the treated side.

CONCLUSION

Repeated IPL treatments had no effects on facial skin barrier function, skin nerve sensitivity, or local microcirculation among healthy individuals. IPL is a safe skin care procedure that does not affect skin sensitivity.

Can Performance and Gentleness Be Reconciled? A Skin Care Approach for Sensitive Skin

People with self-reported sensitive skin may reluctantly use performing anti-ageing skin care products as it could elicit skin discomfort. We thus aimed to design and test an anti-ageing skin care routine that is suitable for people reporting sensitive skin. Key principles for developing products for sensitive skin were applied and formulas were screened for their mildness in vitro using the Reconstructed Human Epidermis ET50 method. Anti-ageing efficacy and mildness was evaluated during a clinical study in China, with 33 female volunteers aged 40–65 years, with sensitive skin. The anti-ageing benefits were measured using Primos 3D, the cutometer and clinical evaluation. Hallmarks for sensitive skin such as skin hydration, skin barrier, skin redness and response to lactic acid were also measured. The ET50 method yielded values suggesting moderate to mild expected irritancy effect in vivo for most of them, and non-irritating effect for the serum. During the clinical study, no physical or functional signs of discomfort were reported with twice-daily usage of the routine. Instrumental evaluation of Wrinkle depth, skin elasticity/firmness, skin hydration, skin barrier and skin redness revealed improvement at 4 and 8 weeks. Clinical evaluation evidenced skin smoothness, skin suppleness and radiance improvements. The skin was less reactive to lactic acid stimuli, while the sensitive skin burden was lowered according to the dermatological quality of life index. Lastly, a separate investigation suggested the potential relief aspect of such routines to alleviate discomforts from mask wearing. With the right formulation design, the benefits of layering products from a routine can be made accessible to people with sensitive skin while simultaneously alleviating the burden of sensitive skin.

Genetic variants affecting chemical mediated skin immunotoxicity

The skin is an immune-competent organ and this function may be impaired by exposure to chemicals, which may ultimately result in immune-mediated dermal disorders. Interindividual variability to chemical-induced skin immune reactions is associated with intrinsic individual characteristics and their genomes. In the last 30-40 years, several genes influencing susceptibility to skin immune reactions were identified. The aim of this review is to provide information regarding common genetic variations affecting skin immunotoxicity. The polymorphisms selected for this review are related to xenobiotic-metabolizing enzymes (CYPA1 and CYPB1 genes), antioxidant defense (GSTM1, GSTT1, and GSTP1 genes), aryl hydrocarbon receptor signaling pathway (AHR and ARNT genes), skin barrier function transepidermal water loss (FLG, CASP14, and SPINK5 genes), inflammation (TNF, IL10, IL6, IL18, IL31, and TSLP genes), major histocompatibility complex (MHC) and neuroendocrine system peptides (CALCA, TRPV1, ACE genes). These genes present variants associated with skin immune responses and diseases, as well as variants associated with protecting skin immune homeostasis following chemical exposure. The molecular and association studies focusing on these genetic variants may elucidate their functional consequences and contribution in the susceptibility to skin immunotoxicity. Providing information on how genetic variations affect the skin immune system may reduce uncertainties in estimating chemical hazards/risks for human health in the future.

Burden of Sensitive Skin (BoSS) Questionnaire and Current Perception Threshold: Use as Diagnostic Tools for Sensitive Skin Syndrome

The assessment of sensitive skin syndrome, characterized by subjective unpleasant sensations, remains a challenge, since there is no international consensus on the best diagnostic tools. This study evaluated the combination of the Burden of Sensitive Skin (BoSS) questionnaire and the current perception threshold as diagnostic tools for sensitive skin syndrome, and the relationship between BoSS and the subjects’ smoking status, phototype and skin type. A total of 100 women completed the BoSS questionnaire, and current perception threshold was measured on the face. The BoSS score was significantly higher in the self-reported sensitive skin group compared with the non-sensitive skin group (25.61 vs 14.05; p < 0.001), and in non-smokers vs smokers (23.00 vs 18.37; p < 0.05). In addition, the current perception threshold values were similar between the sensitive and non-sensitive groups. These results suggest that BoSS is a better diagnostic tool for sensitive skin syndrome than the current perception threshold, and that smokers less frequently have sensitive skin than do non-smokers.

Quantifying skin sensitivity caused by mechanical insults: A review

BACKGROUND

Skin sensitivity (SS) is a commonly occurring response to a range of stimuli, including environmental conditions (e.g., sun exposure), chemical irritants (e.g., soaps and cosmetics), and mechanical forces (e.g., while shaving). From both industry and academia, many efforts have been taken to quantify the characteristics of SS in a standardised manner, but the study is hindered by the lack of an objective definition.

METHODS

A review of the scientific literature regarding different parameters attributed to the loss of skin integrity and linked with exhibition of SS was conducted. Articles included were screened for mechanical stimulation of the skin, with objective quantification of tissue responses using biophysical or imaging techniques. Additionally, studies where cohorts of SS and non-SS individuals were reported have been critiqued.

RESULTS

The findings identified that the structure and function of the stratum corneum and its effective barrier properties are closely associated with SS. Thus, an array of skin tissue responses has been selected for characterization of SS due to mechanical stimuli, including: transepidermal water loss, hydration, redness, temperature, and sebum index. Additionally, certain imaging tools allow quantification of the superficial skin layers, providing structural characteristics underlying SS.

CONCLUSION

This review proposes a multimodal approach for identification of SS, providing a means to characterise skin tissue responses objectively. Optical coherence tomography (OCT) has been suggested as a suitable tool for dermatological research with clinical applications. Such an approach would enhance the knowledge underlying the multifactorial nature of SS and aid the development of personalised solutions in medical and consumer devices.

Seasonal changes in the physiological features of healthy and sensitive skin

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.

RESULTS

A total of 140 subjects completed the study. Significant differences were found in transepidermal water loss (TEWL), skin pH, and cutaneous blood flow (CBF) between winter and summer in the four groups. There were significant differences in stratum corneum hydration (SCH) of the LAST(+)/CAP(-) and LAST(+)/CAP(+) groups, current perception threshold (CPT) at 250 Hz of the LAST(+)/CAT(+) group, and epidermal density of the healthy skin group between the two seasons. Sum of the scores of sting (SSS) showed a close correlation with TEWL, SCH, pH, CPT at 250 Hz, and epidermal density. Sum of the scores of burning (SSB) showed a strong correlation with TEWL, pH, CPT at 250 Hz and 5 Hz, and epidermal density.

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.

Questionnaire and Lactic Acid Sting Test Play Different Role on the Assessment of Sensitive Skin: A Cross-sectional Study

BACKGROUND

Questionnaires and lactic acid sting test (LAST) are two widely used methods to identify sensitive skin. However, the self-perceived sensitive skin by questionnaires was not consistent with the determination of LAST.

OBJECTIVE

The aim of the study was to measure the biophysical properties noninvasively of sensitive skin evaluated by questionnaire and LAST and to investigate their correlations with the scores of questionnaire and LAST.

METHODS

A total of 209 healthy Chinese females completed the study. Self-assessment questionnaire and LAST were both performed to identify sensitive skin. Epidermal biophysical properties, including skin hydration, transepidermal water loss (TEWL), sebum content, erythema index (EI), a* value, L* value, skin elasticity, and skin pH, were measured with noninvasive instruments.

RESULTS

The frequency of sensitive skin was 50.2% and 66.0% by questionnaire and LAST, respectively. Subjects with self-assessed sensitive skin had a slightly higher LAST positive rate. Skin hydration, sebum content, a* and EI values were significantly higher in the self-assessed sensitive skin group, while TEWL, a* and EI values increased but L* value decreased with significance in the LAST positive group. The LAST stingers among sensitive skin subjects had higher EI but not in the healthy skin subjects. In addition, questionnaire scores positively correlated with skin hydration, sebum content, a* and EI values, while a positive relationship of LAST scores with TEWL, a* and EI values was observed. The scores of questionnaire and LAST both negatively related to L* value.

CONCLUSION

Self-assessed questionnaire is associated with sensitive skin featured by oily and red face without impaired barrier function, whereas LAST is suitable to identify fragile skin barrier and enhanced blood flow on the face. Combination of both methods to diagnose sensitive skin might be more reliable.

Understanding the Sensitive Skin Subject to Achieve a More Holistic Diagnosis

Sensitive skin Syndrome (SSS) is a complex global clinical phenomenon that is defined by the self-reported presence of different sensory perceptions, including tightness, stinging, burning, tingling, pain and pruritus and often without objective signs. Due to the subjective nature of this clinical condition, the diagnosis is complex and there is often a disconnect between what subjects feel and what medical professionals can observe. This chapter reviews the known underlying physiology, some of the triggering factors associated with SSS, co-morbidities as well as the psychological impact on individuals suffering from this condition. The goal is to bridge the gap between the physicians’ understanding and the subjects’ perceptions of this real-life condition that affects so many.

Skin sensitivity to capsaicin, perceived stress and burn out among patients with building-related symptoms

Objective

The mechanisms behind building-related symptoms have remained unknown despite many years of research. It is known that environmental and psychosocial factors are of importance. Some receptors in the Transient Receptor Potential family elicit the same symptoms when stimulated, as reported by those suffering from building-related symptoms. The aim of this study was to compare capsaicin sensitivity between people with and without skin symptoms. A second aim was to investigate perceived stress among individuals with different levels of capsaicin sensitivity.

Methods

People referred to an occupational health care unit and judged to have building-related symptoms by a physician answered a questionnaire regarding their symptoms. Solutions with different capsaicin concentrations were applied to participants’ nasolabial folds. Self-reported stress and burnout were assessed using two questionnaires: the Perceived Stress Scale (PSS) and the Shirom-Melamed Burnout Questionnaire (SMBQ).

Results

We found that people who reported facial erythema or itching, stinging, tight or burning facial skin were more sensitive than those without symptoms and similarities with Sensitive Skin are discussed. We also found that participants who reacted to the lowest capsaicin concentrations scored significantly higher on scales for stress and burnout.

Conclusions

We found associations between sensitivity to capsaicin and skin symptoms among people with building-related symptoms, as well as associations between capsaicin sensitivity and perceived stress/burnout.

Nationwide Survey and Identification of Potential Stress Factor in Sensitive Skin of Chinese Women

Purpose

Sensitive skin is characterized by uncomfortable sensations in response to a number of factors. We performed a large-scale study to investigate the prevalence of sensitive skin at all ages and the impacts of related factors across China.

Methods

A nationwide sampling of the Chinese population aged over 18 was conducted. Subjects were categorized into sensitive and non-sensitive groups, and critical differences between these two groups were investigated.

Results

In total, 22,085 questionnaires were collected from Chinese women with sensitive skin. The prevalence of sensitive skin is 49.6% and is associated with age, skin type, geographic area of subjects, and other factors. Heavy life stress and the application of several cosmetic products also affect the prevalence of sensitive skin.

Conclusion

Having a combination or oily skin type, living in the municipalities, being under heavy stress, and applying several cosmetic products will increase skin stress and contribute to the occurrence of sensitive skin.

Cutaneous vessel features of sensitive skin and its underlying functions

Background

Following the sufficient studies of the effects of skin barrier impairment and heightened neural reaction on sensitive skin (SS), many scholars have paid great attention to the roles of superficial microvasculature in SS.

Methods

By questionnaire survey, lactic acid sting test, and capsaicin test, eligible subjects were classified as normal skin, only lactic acid sting test positive (LASTP), only capsaicin test positive (CATP), and both positive (both LASTP and CATP). D‐OCT was used to photograph images for evaluating the cutaneous vessels features each group.

Results

Totally 137 subjects completed the study. Compared with LASTN group, the vascular vessels were closer to epidermis in LASTP group. Mesh and branching vessels were more popular in SS than normal skin. High blood vessel density was more prevalent in SS, while low density frequently presented in normal skin. The vascular depth had a closely negative correlation with face flushing and SSS, and vascular shapes had a good positive correlation with face flushing and SSB.

Conclusions

Our study indicates that there is a significant difference in vascular depth, shape, and density between SS and normal skin which is valuable to explore SS pathologic mechanism and to further investigate cutaneous microvasculature functions in SS.

Association between lactic acid sting test scores, self-assessed sensitive skin scores and biophysical properties in Chinese females

Background

Lactic acid sting test (LAST) is a classical method to identify sensitive skin. However, some subjects with self‐perceived sensitive skin are negative for LAST.

Objective

To determine whether LAST scores are associated with specific phenotype of sensitive skin.

Methods

A total of 292 subjects with self‐perceived sensitive skin were enrolled in this study. The Sensitive Scale was used to evaluate the severity of burning, stinging, itching, tautness, erythema and scaling based on 0–10 scale scores. In addition to the assessment of LAST scores, epidermal biophysical properties were measured using an MPA system.

Results

The Sensitive Scale scores of stinging, itching, tautness and scaling were significantly different between the LAST‐positive and ‐negative groups. However, burning and erythema scores did not differ between the LAST‐positive and ‐negative groups. LAST scores were positively correlated with the Sensitive Scale scores for stinging, itching, tautness and scaling, but not for burning and erythema scores. Moreover, LAST scores negatively correlated with stratum corneum hydration, but positively with transepidermal water loss (TEWL) rates.

Conclusions

Lactic acid sting test scores positively correlated with TEWL rates. LAST scores could be used to identify subjects with sensitive skin characterized mainly by stinging and itching, but not those mainly by burning and erythema.

The Prevalence of Sensitive Skin

Sensitive skin has been described as unpleasant sensory responses to stimuli that should not provoke such sensations. Objectively measurable signs of irritation are not always present in individuals with sensitive skin, however, subjective sensory effects such as, itching, burning, stinging, tightness, and dryness, are consistently present. Given the subjective nature of the phenomenon known as sensitive skin, surveys have been a popular approach to evaluating the prevalence of this condition among the general population, and a number of them have been conducted worldwide. Overall, ~60–70% of women and 50–60% of men report having some degree of sensitive skin. However, there are differences between populations in various geographies, and perceptions of sensitive skin at specific anatomic sites. This article is a review of survey data on the prevalence of self-declared sensitive skin in various geographies, among different gender and age groups, and at various anatomic sites. In addition, we review the factors that may contribute to sensitive skin, and the physiological characteristics associated with this condition, including impaired barrier function and heightened neural reactions.

Will Repeated Ablative Er:YAG Laser Treatment Sessions Cause Facial Skin Sensitivity? Results of a 12-Month, Prospective, Randomized Split-Face Study

Whether multiple laser irradiations affect skin sensitivity is still elusive. We aimed to investigate if repeated ablative erbium:yttrium-aluminum-garnet (Er:YAG) laser therapy could cause or increase skin sensitivity in the treatment areas. Nineteen healthy females received three sessions of a randomized, split-face, Er:YAG laser treatment in a scanning ablative mode (MicroLaserPeel™), with a 6-mm spot size, 8-μm ablative depths, and 30% of pulse overlap first. The next round was conducted in the fractional mode (ProFractional™) at depths ranging from 100 to 150 μm, with one pass by at coverage of 11% in the coagulation mode. Objective biophysical parameters, including transepidermal water loss (TEWL), skin glossiness, epidermal and dermal thickness and density, sensory nerve current perception threshold (CPT), and local blood flow, were measured before and after treatment. Quantitative evaluation of the Er:YAG laser treatment's effect on skin sensitivity is presented. Seventeen volunteers completed a follow-up of 12 months. On days 1 and 3, skin TEWL and epidermal thickness increased, while glossiness decreased. On day 7, there was no significant difference in the skin barrier function between the treated and the control side. Similarly, there was no significant difference in CPT values or local microvascular blood flow between sides at any time point before or after treatment, except that the local microvascular blood flow on the treated side was higher on the first day post-treatment. Er:YAG laser treatment does not influence skin sensitivity in healthy subjects in a long-term follow-up.

Grifolin derivatives from Albatrellus ovinus as TRPV1 receptor blockers for cosmetic applications

OBJECTIVE

Blocking the TRPV1 receptor is an interesting approach for the treatment of sensitive skin. Here we investigated the potential of grifolin derivatives from Albatrellus ovinus to act as TRPV1 receptor blockers and their potential to serve as cosmetic active ingredients.

METHODS

Binding characteristics of grifolin derivatives from Albatrellus ovinus were determined in competitive and functional in vitro assays to achieve IC₅₀ values. The TRPV1 receptor was activated in vivo with capsaicin and noxious heat to investigate skin reddening, microcirculation, skin sensations and heat pain thresholds.

RESULTS

Grifolin derivatives extracted from Albatrellus ovinus proved to inhibit the TRPV1 receptor in vitro and in vivo. Besides suppression of the TRPV1 receptor activity upon chemical stimulation with capsaicin, thermal activation was shown to be inhibited as well by application of cosmetic formulations containing 3% Albatrellus ovinus extract. The reduction of stinging and burning sensations as well as reduction of reddening and microcirculation upon irritation with capsaicin or thermal stress proved efficacy in vivo.

CONCLUSION

Grifolin derivatives from Albatrellus ovinus are able to serve as fungal-derived TRPV1 receptor blockers with capability to serve as a cosmetic active ingredient on sensitive skin.

Reflectance confocal microscopy for the evaluation of sensitive skin

BACKGROUND

Nowadays, the diagnosis for sensitive skin relies on subjective assessment or on the combination of subjective and objective evaluation. No quantitative evaluation is available. It could be expected that confocal microscopy imaging could be of interest to better define the condition.

METHODS

Total 166 healthy female subjects were recruited in this study. Firstly, all subjects completed the sensitive questionnaire. Then, the cutaneous structures were measured by the reflectance confocal microscopy (RCM) on the face and fossa cubitalia. The lactic acid sting test was conducted finally. According to the results of self-perception sensitive skin questionnaire and lactic acid stinging test to evaluate facial skin sensitivity the both positive subjects were regarded as sensitive skin group and both negative group as healthy control group.

RESULT

The results of RCM indicating that the proportion of 'disarranged honeycomb pattern' and 'spongiform edema' in the sensitive group and healthy control group were statistically different (P < 0.05), respectively; The following report 'damaged dermal papilla rings' was not a distinctive pattern, with no significant statistical difference (P > 0.05). The epidermal thickness was 38.88 ± 6.81 μm, healthy control group was 40.31 ± 9.37 μm in, respectively, sensitive skin group and healthy control group, there was no significant statistical difference between the two groups (P > 0.05). The honeycomb structure depth of sensitive group was 20.57 ± 4.86 μm. It was for 23.27 ± 6.38 μm, healthy control group the difference being statistically different between the two groups (P < 0.05).

CONCLUSION

Based on the RCM results, 'epidermal honeycomb structure' and 'spongiform edema' may be used as new skin signs of RCM evaluation of sensitive skin effectively. Indeed, sensitive skin honeycomb structure depth was thinner compared with healthy control group. Such a specific pattern has good clinical and monitoring value for the further exploration. RCM could provide new data and patterns for the evaluation of sensitive skin.

A model for perception-based identification of sensitive skin

BACKGROUND

With high prevalence of sensitive skin (SS), lack of strong evidence on pathomechanisms, consensus on associated symptoms, proof of existence of 'general' SS and tools to recruit subjects, this topic attracts increasing attention of research.

OBJECTIVE

To create a model for selecting subjects in studies on SS by identifying a complete set of self-reported SS characteristics and factors discriminatively describing it.

METHODS

A survey (n = 3058) was conducted, comprising questions regarding socio-demographics, atopy, skin characteristics, personal care, degree of self-assessed SS and subjective and objective reactions to endogenous and exogenous factors. Exploratory factor analysis on 481 questionnaires was performed to identify underlying dimensions and multivariate logistic regression to find contributing variables to the likelihood of reporting SS.

RESULTS

The prevalence of SS was found to be 41%, and 56% of SS subjects reports a concomitant atopic condition. The most discriminative were the eliciting factors toiletries and emotions, and not specific skin symptoms in general.

CONCLUSION

Triggers of different origins seem to elicit SS, it is not defined by concomitant skin diseases only, suggesting existence of 'general' SS. A multifactorial questionnaire could be a better diagnostic than a one-dimensional provocative test.