Sensitive skin: mechanisms and diagnosis

A Dermocosmetic Significantly Reduces the Frequency and Intensity of Facial Skin Intolerability and Sensitivity in Subjects with Skin Intolerant to Skin Care Products and Sensitive Skin

Introduction

Intolerance to dermocosmetics is frequent in subjects with allergic contact dermatitis (ACD). A dermocosmetic (DC) was developed to restore the natural skin barrier, to reduce skin inflammation and to improve sensitive skin in ACD.

Objective

To assess the benefit of a DC in subjects with an allergic background and intolerance to cosmetic care, or with sensitive skin.

Materials and Methods

In this open-label study, 107 subjects above 16 years of age applied DC on the face twice a day for 28 days. Assessments at Days 0, 14 and 28, included skin sensitivity, stinging test, local tolerance, transepidermal water loss (TEWL), skin hydration, inflammatory biomarkers (IL-1α, IL-1RA, PGE2) using tape stripping and subject satisfaction.

Results

88% were women and mean age was 42.0±15.0 years. Skin sensitivity at inclusion scored 5.9±0.35; 46% had ACD, 95% skin irritation, 92% sensitive skin and 88% intolerance to cosmetics. A significant (p<0.0001) 85% decrease of frequency and intensity of the composite score was observed at both endpoints. Stinging scores significantly (p<0.0001) decreased from 3.9 at baseline to 2.4 at Day 14 and 1.4 at Day 28; 77% and 81% of subjects reported improved skin reactivity at Day 14 and Day 28, respectively. Similar improvements were noted in the frequency and intensity of irritation, erythema, stinging, burning and discomfort. TEWL, skin hydration and inflammatory biomarker levels significantly (p<0.0001) improved. Overall subject satisfaction (85%) and tolerance (investigators: 99%, subjects: 97%) were high.

Conclusion

DC significantly reduced the frequency and intensity of facial skin intolerability and sensitivity in subjects with skin intolerant to skin care products.

Clinicaltrialsgov Identifier

NCT05487937.

An Autologous Topical Serum Derived from Platelet-Rich Plasma Therapy for the Management of Sensitive Skin Alterations: A Case Series Report

Background

Although the underlying pathophysiology of sensitive skin remains unknown, it presents clinical symptoms like erythema, burning and dryness associated with other inflammatory dermatoses such as dermatitis or rosacea.

Objective

The aim of the present report was to provide preliminary data about the efficacy of Endoret-Serum (ES) as an autologous therapy for the topical management of sensitive skin alterations.

Materials and Methods

Five patients underwent a daily topical ES treatment that was maintained for three months. Clinical assessment was carried out using validated dermatological surveys (DLQI, IGA, Likert, PGI-I). Additionally, skin hydration measurement and high-resolution topographic and reflectance confocal imaging analysis were carried out.

Results

No adverse events were observed during the treatment. At the end of the follow-up period, surveys highlighted a significant therapeutic effect compared to baseline. Skin hydration was also improved, and topographic images showed a decrease in patient’s underlying inflammatory and vascular condition.

Conclusion

This preliminary report suggests that Endoret-Serum may be useful in the management of clinical symptoms derived from sensitive skin alterations.

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.

Acid-base combination principles for preparation of anti-acne dissolving microneedles loaded with azelaic acid and matrine

To overcome the poor solubility, skin irritation, and low permeability of azelaic acid (AZA) existed on the marketed formulations, a co-drug principle via matrine (MAT) was adopted to prepare anti-acne dissolving microneedles (DMNs). The formula was optimized according to the solubility and antibacterial activity of novel ionic salt. The results indicated solubilization of AZA could be achieved at a molar ratio between AZA and MAT was 1:1. Meanwhile, synergistic antibacterial and anti-irritative properties were acquired. The matrix materials were composed of sodium carboxymethyl cellulose (CMC), polyvinylpyrrolidone (PVP), and trehalose. And drug loadings of AZA and MAT in DMNs were 201.88 ± 4.81 µg and 259.71 ± 1.72 µg, respectively. After insertion into porcine skin for 10 h, the cumulative permeability of AZA and MAT were 68.16% ± 3.79% and 57.37 ± 5.17%, respectively, while just 4.13 ± 0.39% (p < 0.01) was detected for commercially available AZA gel. In vitro antibacterial experiment, bacteriostatic rates of DMNs were all above 95% for Staphylococcus aureus, Staphylococcus epidermidis, and Propionibacterium acnes. Besides, DMNs exhibited no cytotoxicity and skin irritation. In conclusion, combination between AZA and MAT addressed shortcomings of AZA, and made it easier, safer, and more effective in acne treatment.

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.

Non-invasive evaluation of subjective sensitive skin by transcriptomics using mRNA in skin surface lipids

Sensitive skin is a condition characterized by hypersensitivity to environmental stimuli, and its pathophysiology has not been fully elucidated. Questionnaires based on subjective symptoms, intervention tests, and measuring devices are used to diagnose sensitive skin; however, objective evaluation methods, including biomarkers, remain to be established. This study aimed to investigate the molecular profiles of self-reported sensitive skin, understand its pathophysiology and explore its biomarkers. Here, we analysed RNAs in skin surface lipids (SSL-RNAs), which can be obtained non-invasively by wiping the skin surface with an oil-blotting film, to compare the transcriptome profiles between questionnaire-based "sensitive" (n = 11) and "non-sensitive" (n = 10) skin participants. Exactly 417 differentially expressed genes in SSL-RNAs from individuals with sensitive skin were identified, of which C-C motif chemokine ligand 17 and interferon-γ pathways were elevated, while 50 olfactory receptor (OR) genes were downregulated. The expression of the detectable 101 OR genes was lower in individuals with sensitive skin compared to that in those with non-sensitive skin and was particularly associated with the subjective sensitivity among skin conditions. The receiver operating characteristic (ROC) curve demonstrated that the mean expression levels of OR genes in SSL-RNAs could discriminate subjective skin sensitivity with an area under the ROC curve of 0.836. SSL-RNA profiles suggest a mild inflammatory state in sensitive skin, and overall OR gene expression could be a potential indicator for sensitive skin.

Correlation Between Facial Skin Microbiota and Skin Barriers in a Chinese Female Population with Sensitive Skin

Background and Aim

The association of microbiota changes with sensitive skin remains controversial until now. Although a strong correlation is detected between skin microbiota distribution and biophysical parameters, there is little knowledge on the link between sensitive skin and skin microbiota in Chinese women. This study aimed to unravel the correlation between facial skin microbiota distribution and skin barriers in Chinese women with sensitive skin.

Materials and Methods

In total, 34 volunteers were enrolled, including 24 subjects with sensitive skin (SS group) and 10 subjects with non-sensitive skin (NS group). The cuticle moisture content, transepidermal water loss (TEWL), and facial skin sebum secretion were measured, and the facial skin surface morphology was evaluated. Sensitive skin samples were collected from the facial (SS-F group) and chest skin of subjects in the SS group (SS-C group), while non-sensitive skin samples were collected from the facial skin of subjects in the NS group (NS-F group). All skin samples were subjected to 16S rRNA sequencing.

Results

16S rRNA sequencing detected Actinobacteria, Firmicutes, and Proteobacteria as the three most common microbiota phyla and Propionibacterium, Paracoccus, and Corynebacterium as the three most common microbiota genera, and there were no significant differences in the relative frequency of Actinobacteria, Firmicutes, or Proteobacteria, or Propionibacterium, Paracoccus, or Corynebacterium among the SS-F, SS-C, and NS-F groups (P>0.05). We detected no significant difference in the diversity of bacterial communities among the SS-F, SS-C, and NS-F groups; however, the Shannon’s diversity index was significantly higher in the NS-F group than in the SS-C group. In addition, Spearman correlation analysis showed a correlation between the microbiota genera and skin physiological parameters (P<0.05).

Conclusion

This study preliminarily unravels the skin microbiota of sensitive skin using a high-throughput tool, and there are no microbiota genera with strong associations with skin physiological parameters.

Sensitive Skin Syndrome: An Update

Sensitive skin syndrome is a widely reported complaint but a diagnostic challenge because of its subjective symptoms and lack of clearly visible manifestations. Epidemiological studies have shown the prevalence of sensitive skin to be as high as 60-70% among women and 50-60% among men. Patients with this syndrome usually have unpleasant sensations when exposed to physical, thermal, or chemical stimuli that normally cause no provocation on healthy skin. Recent studies and newly accepted position papers have provided a more in-depth understanding and consensus of its underlying pathophysiology, associations, diagnosis, and treatment. Since no clinical studies have been conducted about specific treatment protocols, patients with this condition should be provided with personalized skin management. Given this updated knowledge, our review offers an approach to sensitive skin syndrome, with differential diagnoses, and interventions targeting its pathophysiology.

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.

Sensitive Skin: Lessons From Transcriptomic Studies

In 2016, a special interest group from the International Forum for the Study of Itch defined sensitive skin (SS) as a syndrome that manifests with the occurrence of unpleasant sensations (stinging, burning, pain, pruritus, and tingling sensations) after stimuli that should not cause a reaction, such as water, cold, heat, or other physical and/or chemical factors. The pathophysiology of sensitive skin is still poorly understood, but the symptoms described suggest inflammation and peripheral innervation. Only two publications have focused on sensitive skin transcriptomics. In the first study, the authors performed a microarray comparison of SS and non-sensitive skin (NSS) samples and showed differences in the expression of numerous genes in SS and NSS samples. Moreover, in the SS samples, two clusters of genes were identified, including upregulated and downregulated genes, compared to NSS samples. These results provide some interesting clues for the understanding of the pathophysiology of SS. The second study compared SS and NSS samples using RNA-seq assays. This method allowed the identification of long non-coding RNAs (lncRNAs) and differentially expressed mRNAs and provided a comprehensive profile in subjects with SS. The results showed that a wide range of genes may be involved in the pathogenesis of SS and suggested pathways that could be associated with them. In this paper, we discuss these two studies in detail and show how transcriptomic studies can help understand the pathophysiology of sensitive skin. We call for new transcriptomic studies on larger populations to be conducted before putative pathogenic mechanisms can be detected and analyzed to achieve a better understanding of this complex condition.

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.

Transcriptional profiling of lactic acid treated reconstructed human epidermis reveals pathways underlying stinging and itch

The incidence of sensitive skin with stinging and itch following chemical exposure in products such as cosmetics is increasing, but molecular mechanisms underlying this pathophysiology remain understudied. Here we performed transcriptional analysis of reconstructed human epidermis (RHE) 1, 6, and 24 h following topical lactic acid (LA) application, a known inducer of the sensitive skin reaction. Since little is known about the specific role of keratinocyte transcriptional changes in mediating stinging and itch, we performed pathway analysis using several publically available databases and then focused on significantly changed transcripts involved in stress responses and itch signaling using the Comparative Toxicogenomics Database. LA treatment induced damage-associated genes HSPA1A, DDIT3, IL1A, and HMGB2. Neurotrophic factors including BDNF, ARTN, PGE2, and chemokines were also upregulated. Stimulation of the RHE with 5% LA did not reduce cell viability, but reduced the trans-epidermal electric resistance, suggesting barrier dysfunction. Accordingly, skin barrier formation genes such as filaggrins (FLG, FLG2) and corneodesmosin (CDSN) were downregulated. To our knowledge, this is the first study focusing on transcriptional changes underlying the stinging response of keratinocytes upon LA stimulation. While follow-up research is needed, this study provides new insight into the mechanisms underlying the sensitive skin reaction.

Biomimetic proopiomelanocortin suppresses capsaicin-induced sensory irritation in humans

Sensitive skin is a frequently mentioned cosmetic complaint. Addition of a biomimetic of neuromediator has recently appeared as a promising new way to cure skin care product problems. This study was aimed to assess the inhibitory effect of a biomimetic lipopeptide derived from proopiomelanocortin (bPOMC) on capsaicin-induced sensory irritation in human volunteers and also to compare its protective effect with that of the well-known anti irritant strontium chloride. The effect of each test compound was studied on 28 selected healthy volunteers with sensitive skin in accordance with a double-blind vehicle-controlled protocol. From day 1 to day 13 each group was applied the test compound (bPOMC or strontium chloride) to one wing of the nose and the corresponding placebo (vehicle) to the other side twice daily. On days 0 and 14, acute skin irritation was induced by capsaicin solution and quantified using clinical stinging test assessments. Following the application of capsaicin solution, sensory irritation was evaluated using a 4-point numeric scale. The sensations perceived before and after treatment (on days 0 and 14) was calculated for the two zones (test materials and vehicle). Ultimately the percentage of variation between each sample and the placebo and also the inhibitory effect of bPOMC compared to that of strontium chloride were reported. Clinical results showed that after two weeks treatment, the levels of skin comfort reported in the group treated with bPOMC were significantly higher than those obtained in the placebo group and the inhibitory effect of bPOMC was about 47% higher than that of strontium chloride. The results of the present study support the hypothesis that biomimetic peptides may be effective on sensitive skin.

Randomised double-blind placebo-controlled study of the effect of Lactobacillus paracasei NCC 2461 on skin reactivity

In recent decades, the prevalence of subjects with reactive skin has considerably increased in industrialised countries. 50% of women and 30% of men report cutaneous discomfort classified under reactive/sensitive skin. Several topical approaches have been proposed, in particular through improvement of galenic forms or protection of epidermal surface. We propose to act differently, deeply from inside the body via an innovative nutritional approach. To this purpose, Lactobacillus paracasei NCC 2461 (ST11) was selected because of its specific beneficial skin properties discovered in in vitro studies, i.e. diminution of neurogenic inflammation and promotion of the recovery of skin barrier function. We designed a randomised double-blind placebo-controlled clinical study with a two-month supplementation in two female treatment groups (n=32 per group). A capsaicin test was performed to monitor the time course of skin sensitivity. Moreover, transepidermal water loss was assessed to analyse the rate of skin barrier function recovery; dryness of the leg and roughness of the cheeks was investigated by a dermatologist as well as by self-assessment. The results of the present clinical trial show that oral supplementation with the probiotic decreases skin sensitivity and increases the rate of barrier function recovery. Thus, the data provide evidence that daily intake of ST11 could improve reactive skin condition.

Decreased ATP synthesis and lower pH may lead to abnormal muscle contraction and skin sensitivity in human skin

BACKGROUND

Sensitive skin represents hyperactive sensory symptoms showing exaggerated reactions in response to internal stimulants or external irritants. Although sensitive skin is a very common condition affecting an estimated 50% of the population, its pathophysiology remains largely elusive, particularly with regard to its metabolic aspects.

OBJECTIVE

The objective of our study was to investigate the pathogenesis of sensitive skin.

METHODS

We recruited healthy participants with 'sensitive' or 'non-sensitive' skin based on standardized questionnaires and 10% lactic acid stinging test, and obtained skin samples for microarray analysis and subsequent experiments.

RESULTS

Microarray transcriptome profiling revealed that genes involved in muscle contraction, carbohydrate and lipid metabolism, and ion transport and balance were significantly decreased in sensitive skin. These altered genes could account for the abnormal muscle contraction, decreased ATP amount in sensitive skin. In addition, pain-related transcripts such as TRPV1, ASIC3 and CGRP were significantly up-regulated in sensitive skin, compared with non-sensitive skin.

CONCLUSIONS

Our findings suggest that sensitive skin is closely associated with the dysfunction of muscle contraction and metabolic homeostasis.

Skin sensitivity and intolerance in Shanghai: cumulative influence of different meteorological parameters

BACKGROUND

Although Sensitive skin (SS) conditions are reported to be affected by climate changes, the correlations with meteorological parameters remain mostly unclear.

OBJECTIVE

To investigate the changes of facial skin conditions in different seasons in Shanghai, including the speed and severity of the influences imposed by different meteorological parameters.

METHODS

Totally eighty-one healthy female volunteers completed the study in both spring (May) and summer (August). Evaluations of facial skin conditions included stimulating sensory test, clinical grading and biophysical measurements. Correlations between the meteorological parameters and ΔTEWL as well as clinical parameters were analyzed.

RESULTS

There was no significant difference between two seasons in lactic acid sting test. The stimulation sensations felt by Vitamin B3 (VB3) containing cream was significantly higher in May than that in August. In accordance, baseline visual scores for erythema and scaliness in May were also significantly higher than those scores in August. The baseline transepidermal water loss (TEWL) value was significantly higher in May than that in August. Positive correlations were detected between ΔTEWL and atmospheric pressure on the test day, adjust 3-day and 7-day mean of daily solar radiation respectively. There were negative correlations between ΔTEWL and temperature outside on the test day, adjust 3-day mean as well as adjust 7-day mean of relative humidity.

CONCLUSIONS

Facial skin conditions in summer are better than that in spring in Shanghai. The influences from atmospheric pressure and temperature are relatively quick in speed, while the influences from relative humidity and solar radiation are slow but cumulative.

Alstonia scholaris R. Br. Significantly Inhibits Retinoid-Induced Skin Irritation In Vitro and In Vivo

Topical retinoids inhibit matrix metalloproteinases and accelerate collagen synthesis, thereby triggering antiaging effects in the skin. However, topical retinoids can cause severe skin reactions, including scaling, erythema, papules, and inflammation. The present study demonstrates that the ethanolic bark extract of Alstonia scholaris R. Br. can significantly inhibit all-trans retinoic acid-induced inflammation in human HaCat keratinocyte cells. Furthermore, two representative retinoid-induced proinflammatory cytokines, monocyte chemoattractant protein-1 and interleukin-8, were significantly suppressed by A. scholaris extract (by 82.1% and 26.3% at 100 ppm, and dose-dependently across the tested concentrations) in vitro. In a cumulative irritation patch test, A. scholaris extract decreased retinol-induced skin irritation, while strengthening the ability of retinoids to inhibit matrix metalloproteinase-1 expression, which is strongly associated with aging effects. These results suggest that A. scholaris is a promising compound that may increase the antiaging function of retinoids while reducing their ability to cause skin irritation.

Putative neuronal mechanisms of sensitive skin

According to epidemiological studies, up to 50% of adults report facial sensitivity with various distinctive symptoms, such as prickling, burning, tingling, pain or itching. This is termed sensitive skinand represents a syndrome of physiological reactions rather than a disease entity. In this review, we discuss the currently available literature on this syndrome and describe the possible underlying neuronal pathomechanisms. The sensory receptors expressed on unmyelinated nerve fibres and keratinocytes involved in nociception, such as TRPV1 and endothelin receptors, are hypothesized to play a role in the induction of sensitive skin. Furthermore, we discuss the role of neurotrophins and the influence of stress on sensitive skin.

Intervention with flaxseed and borage oil supplements modulates skin condition in women

Ingestion of selected nutrients modulates dermal properties. In the present study, two groups of women ingested flaxseed or borage oil for 12 weeks. The control group received a placebo containing medium-chain fatty acids. Dose was 2·2 g total fatty acids/d with α-linolenic acid and linoleic acid as major constituents in the flaxseed oil group; in the borage oil group linoleic and γ-linolenic acid were predominant. In the flaxseed oil group, the contribution of α-linolenic acid to total fatty acids in plasma was significantly increased on weeks 6 and 12, whereas there was an increase in γ-linolenic acid in the borage oil group (P < 0·05). Skin irritation was performed by nicotinate treatment, and changes in skin reddening and blood flow were monitored. Compared to week 0, skin reddening was diminished in both groups; blood flow was also lowered. Skin hydration was significantly increased after 12 weeks of treatment compared to week 0, with flaxseed or borage oil (P < 0·05). Transepidermal water loss was decreased in both oil groups by about 10 % after 6 weeks of supplementation. A further decrease was determined after 12 weeks in the flaxseed oil group. Surface evaluation of living skin revealed that roughness and scaling of the skin were significantly decreased with flaxseed and borage oil comparing week 0 and week 12 (P < 0·05). Except for hydration, none of the parameters was affected in the placebo group. The present data provide evidence that skin properties can be modulated by an intervention with dietary lipids.