The Multifaceted Roles of Mast Cells in Immune Homeostasis, Infections and Cancers

Mast cells (MCs) play important roles in normal immune responses and pathological states. The location of MCs on the boundaries between tissues and the external environment, including gut mucosal surfaces, lungs, skin, and around blood vessels, suggests a multitude of immunological functions. Thus, MCs are pivotal for host defense against different antigens, including allergens and microbial pathogens. MCs can produce and respond to physiological mediators and chemokines to modulate inflammation. As long-lived, tissue-resident cells, MCs indeed mediate acute inflammatory responses such as those evident in allergic reactions. Furthermore, MCs participate in innate and adaptive immune responses to bacteria, viruses, fungi, and parasites. The control of MC activation or stabilization is a powerful tool in regulating tissue homeostasis and pathogen clearance. Moreover, MCs contribute to maintaining the homeostatic equilibrium between host and resident microbiota, and they engage in crosstalk between the resident and recruited hematopoietic cells. In this review, we provide a comprehensive overview of the functions of MCs in health and disease. Further, we discuss how mouse models of MC deficiency have become useful tools for establishing MCs as a potential cellular target for treating inflammatory disorders.

A re-innervated in vitro skin model of non-histaminergic itch and skin neurogenic inflammation: PAR2-, TRPV1- and TRPA1-agonist induced functionality

Background

Skin, and epidermis, is innervated by sensory nerve fibres. Interactions between them and signal transduction are only partially elucidated in physiological/pathological conditions, especially in pruritus.

Objectives

To study the mechanisms involved in pruritus in vitro, we developed a skin explant model re‐innervated by sensory neurons.

Methods

This model is based on the co‐culture of human skin explants and sensory neurons from dorsal root ganglia of rats. Innervation and the expression of protease activated receptor 2 (PAR2), transient receptor potential vanilloid 1 (TRPV1) and transient receptor potential ankyrin one (TRPA1) was analysed by immunostaining. The response of the model to TRPV1, PAR2 and TRPA1 agonists was analysed by patch‐clamp, qPCR and enzyme‐linked immunosorbent assay.

Results

After 5 days of re‐innervating nerve fibres was evidenced in the epidermis. Re‐innervation was correlated with decrease of epidermal thickness and the number of apoptotic cells in the tissue. The major actors of non‐histaminergic itch (PAR‐2, thymic stromal lymphopoietin [TSLP], TSLP‐R, TRPA1 and TRPV1) were expressed in neurons and/or epidermal cells of skin explants. After topical exposure of TRPV1‐(Capsaicin), TRPA1‐(Polygodial) and PAR2‐agonist (SLIGKV‐NH₂) activation of reinnervating neurons could be shown in patch‐clamp analysis. The release of TSLP was increased with capsaicin or SLIGKV but decreased with polygodial. Release of CGRP was increased by capsaicin and polygodial but decreased with SLIGKV. Activation by SLIGKV showed a decrease of VEGF; polygodial induced an increase of TSLP, Tumour necrosis factor (TNF) and nerve growth factor and capsaicin lead to a decrease of sema3 and TNF expression.

Conclusion

The present model is suitable for studying itch and neurogenic inflammation pathways in vitro. We observed that activation of TRPV1, TRPA1 and PAR‐2 leads to different response profiles in re‐innervated skin explants.

Relationship between sensitive skin and sleep disorders, fatigue, dust, sweating, food, tobacco consumption or female hormonal changes: Results from a worldwide survey of 10 743 individuals

BACKGROUND

Sensitive skin is related to environmental factors.

OBJECTIVES

We aimed to investigate the roles of poorly known associated and triggering factors on sensitive skin in a large global population.

METHODS

A survey was administrated to a representative sample of the adult population aged 18-75 years in five different countries (Brazil, China, France Russia, and the United States). All participants answered a web-based questionnaire on sociodemographic characteristics, sensitive skin and environmental factors.

RESULTS

Among the 10 743 included individuals (5285 men and 5458 women), 48.2% declared that they had sensitive skin. The group with sensitive skin reported significant increases in fatigue, dust or sweating and to a lesser extent food or tobacco consumption. The members of this group also declared that they experienced more sleep disorders than individuals without sensitive skin. Sensitive skin was very frequent in pregnant women, women with painful menstruations or women using contraceptive pills.

CONCLUSIONS

This large cohort study identified new factors, including female hormonal status, fatigue, sleep disorders and food, associated with sensitive skin. These associations suggest that sensitive skin is not restricted to an epidermal disorder but may be included in a larger context. The identified factors are potential upstream drivers of neurogenic inflammation in sensitive skin.

Omalizumab in patients with NSAIDs-exacerbated respiratory disease

BACKGROUND

The association of acetylsalicylic acid (ASA) intolerance, chronic rhinosinusitis with nasal polyps (CRSwNP), asthma, or chronic urticaria is known as NSAID-exacerbated respiratory disease (N-ERD). N-ERD patients often suffer from recurrent nasal polyps, severe asthma or also from urticaria. The aim of the present study was to retrospectively analyze the clinical efficacy of anti-IgE antibody treatment with omalizumab in patients with confirmed N-ERD.

METHODS

In the open trial with patients receiving verum patients with CRSwNP, confirmed N-ERD by oral or nasal ASA challenges, asthma or chronic urticaria were included in the study. Rhinological and pulmonary parameters were evaluated before and after 3, 6 and 9 months of therapy by rhinological questionnaires (CRS VAS-scores and RSOM-31), nasal polyp (NP)-, ACT-scores and FEV1 values. Urticaria activity was monitored clinically. N-ERD patients with aspirin desensitization were included as control group (follow-up 9 months).

RESULTS

In the omalizumab group 16 patients were included (10 female, 6 male, mean age 51 yrs). CRS symptoms, RSOM-31- and NP-score decreased significantly following omalizumab therapy compared to baseline. The ACT-score (MV 16.5 to 20.6) and FEV1values (MV 80 % to 89 %) improved significantly. No urticaria symptoms were reported after 3 months. Oral prednisolone therapy was required in one case and a repeated nasal sinus surgery in an additional case due to progression of NP. In the control group (8 female, 8 male, mean age 45 yrs) the NP-score was unchanged.

CONCLUSIONS

Omalizumab is an effective therapy option in N-ERD patients in a 9 month study period.

[Nasal provocation with increased ASA dose: improved "non-steroidal anti-inflammatory drugs (NSAIDs)-exacerbated disease" (N‑ERD) detection rate in chronic rhinosinusitis patients]

BACKGROUND

Analgesic intolerance (AI) is an important diagnostic feature of disease progression in patients with chronic rhinosinusitis (CRS) accompanied by nasal polyps (CRSwNP) and asthma.

OBJECTIVE

The aim of the present study was to determine whether increasing the concentration of acetylsalicylic acid (ASA) used in the diagnostic nasal challenge would improve detection of ASA intolerance (NSAIDs-exacerbated respiratory disease, N‑ERD).

METHODS

Patients with CRSwNP, asthma, and with (CRSwNP-AAI, n = 20) or without (CRSwNP-A, n = 15) anamnestically reported AI, as well as control subjects with CRS but no nasal polyps, asthma, or AI (n = 15), were challenged nasally with 16 mg ASA and, in case of a negative result, with 25 mg of ASA.

RESULTS

In CRSwNP-AAI subjects, the challenge with 16 mg ASA resulted in detection of AI in 80% of cases; increasing the challenge of ASA to 25 mg improved the AI detection to 95%. In CRSwNP-A subjects, the detection of AI increased from 40% (16 mg ASA) to 53% (25 mg ASA). In the control group, no reaction to nasal ASA challenge was detected. No difference in the diagnosis of positive reactions after provocation was found when using the German vs. the European recommended evaluation criteria. Mild pulmonary symptoms occurred in 2 (10%) CRSwNP-AAI patients following the 16 mg ASA challenge.

CONCLUSION

In patients with CRSwNP, asthma, and anamnestic AI, nasal provocation can effectively confirm the diagnosis of N‑ERD and can also be recommended for patients with recurrent CRSwNP and asthma but without reported AI. Increasing the ASA challenge to 25 mg increases the overall detection rate.

Characterization of cowhage-induced pruritus in inflamed and non-inflamed skin

BACKGROUND AND OBJECTIVE

Pruritus is a major symptom of many inflammatory diseases and impacts greatly the quality of life in patients. We aimed to specify the characteristics of experimentally induced pruritus in normal skin and in experimentally induced inflammatory dermatitis in healthy volunteers.

METHODS

Skin inflammation was induced by the repeated application of sodium lauryl sulphate (SLS 2%) on the volar forearms of 30 healthy volunteers. Inflammatory dermatitis intensity was assessed using the eczema score adapted from Frosch and Kligman. Non-histaminergic pruritus was induced by cowhage spicules rubbed on the volar forearms and recorded for 30 min on a 10-cm visual analogue scale (VAS) in both non-inflamed and inflamed skin.

RESULTS

Induction of inflammatory dermatitis by SLS resulted in a mild inflammatory dermatitis with an inflammation score of 2.3 ± 0.1 within 7 days of treatment. Cowhage-induced pruritus was of markedly higher intensity (P < 0.001), and all but two individuals had higher maximum pruritus intensity in inflamed skin as compared to non-inflamed skin, whereas the kinetics of the pruritus response were similar. The quality of cowhage-induced pruritus was significantly different with more 'burning' and 'painful sensations' in inflamed skin (P < 0.01). Maximum pruritus intensity in inflamed skin strongly correlated with maximum pruritus intensity in non-inflamed skin (r = 0.51, P = 0.004). Skin hydration, skin barrier integrity and dermatitis severity did not correlate with pruritus intensity.

CONCLUSION

Taken together, pruritus in inflamed skin is perceived as more intense, painful and burning. This may explain, in part, why pruritus is a major driver of quality-of-life impairment in patients with chronic inflammatory skin conditions such as atopic dermatitis.

[Medical caravan in Morocco: Mobile dermatology]

This publication is based on personal experiences gathered during participation in several "medical caravans". These caravans where under the leadership of either a Moroccan nongovernmental organization (NGO) or a Belgian NGO. Medical caravans are multidisciplinary mobile groups that offer basic medical care in rural areas. The location usually changes every 1-2 days. The physician team comprises more than 10 different specialties including midwives, psychologists, nurses, hearing instrument specialists and podologists. The work was supported by Moroccan caregivers (fluent in French, Arabic and Berber). They were able to reduce the linguistic and cultural barriers as well as fear and insecurity thus creating an environment of trust for the consultations. The spectrum of diagnosed and treated dermatoses included benign and malignant cutaneous tumors like basal cell carcinoma, squamous cell carcinoma, melanoma, infectious skin diseases, inflammatory dermatoses like atopic dermatitis and psoriasis as well as genodermatosis. The personal satisfaction and the feeling of being able to contribute to medical support for an underprivileged population in a remote rural area outweighed critical aspects, e.g. regarding the sustainable effects of a temporary medical caravan.

Positive impact of dietary water on in vivo epidermal water physiology

BACKGROUND/PURPOSE

The importance of water in human physiology is well known, also for skin functionality. This study was conducted to assess the effects of dietary water on epidermal skin hydration in healthy females.

METHODS

Thirty-four healthy females (mean 24.5 ± 6.34 years old) were selected and characterized according to their dietary daily habits, by a previously validated Food Frequency Questionnaire. For 1 month, these subjects were asked to add 2 L/day of water to their regular dietary habits. Measurements took place at day D0, D15, and D30, and involved general variables (body weight, blood pressure, Body Mass Index) and specific skin physiological variables in five anatomical sites (ventral forearm, anterior leg, dorsal hand, zygomatic area, and forehead) involving epidermal superficial and deep hydration, by capacitance and transepidermal water loss (TEWL).

RESULTS

This water overload (2 L/day/30 days) did not change the blood volume or weight of the individuals. However, both superficial and deep skin hydration were clearly in those individuals that regularly consumed lees water per day. No significant effect was observed in the TEWL.

CONCLUSIONS

This study clearly suggests that dietary water intake seems to influence skin water content. Nevertheless further in vivo investigations involving other variables, such as biomechanical descriptors, should follow to look deeper into this aspect of skin physiology.

Development and organization of human stratum corneum after birth: electron microscopy isotropy score and immunocytochemical corneocyte labelling as epidermal maturation's markers in infancy

BACKGROUND

There is growing evidence for the ongoing structural and functional adaptation of the skin after birth.

OBJECTIVES

The aim of this study was the definition of scanning electron microscopy markers of skin maturation in different age groups (birth to adulthood). We propose a semiquantitative score to analyse the maturation of the skin surface and a complementary evaluation of the distribution of corneodesmosin and corneodesmosomes.

MATERIAL AND METHODS

An electron microscopy isotropy (E.M.I.) score was performed in six age-groups to include fullterm neonates, babies, children and adults. The distribution of corneodesmosome remnants was analysed by corneodesmosin distribution with immunocytochemical corneocyte labelling.

RESULTS

The E.M.I. score showed the highest anisotropy in neonates. The youngest groups displayed irregular and thick cell clusters composed of poorly individualized cells. In the older groups, the distribution of superficial corneocytes was more regular. The cells evenly covered the surface and displayed easily visualized single cell outlines. The distribution of immune-labelled corneodesmosome remnants and the corneocyte projected area showed a correlation between age and structural maturation. The observed evolution indicated a poorly controlled process of corneocyte desquamation in infants and confirmed the relative immaturity of the epidermal barrier up to 1-2 years after birth under basal conditions.

CONCLUSION

Our study is the first attempt at semiquantitative evaluation of the micromorphology maturation of the epidermal surface at the ultrastructural level. The E.M.I. score and the associated pattern of corneodesmosome breakdown may be used as markers of the stratum corneum maturation.

Correlation of optical coherence tomography and histology in microcystic adnexal carcinoma: a case report

BACKGROUND/AIMS

Herein, we report a case of microcystic adnexal carcinoma (MAC), which we correlated and evaluated by optical coherence tomography (OCT) and conventional H&E histology.

METHODS

A commercially available OCT scanner was used for imaging. Several multi-slice images were obtained from the central portion of the lesion. Correlation of OCT findings with histology was performed retrospectively.

RESULTS

Microcystic adnexal carcinoma showed characteristic criteria, which were divided into superficial and sub-epidermal findings.

CONCLUSION

The use of OCT can visualize characteristic criteria of MAC, thus enabling prompt diagnosis before surgery.

In vivo methods for the analysis of the penetration of topically applied substances in and through the skin barrier

The efficacy of a drug is characterized by its action mechanism and its ability to pass the skin barrier. In this article, different methods are discussed, which permit this penetration process to be analysed non-invasively. Providing qualitative and quantitative information, tape stripping is one of the oldest procedures for penetration studies. Although single cell layers of corneocytes are removed from the skin surface, this procedure is considered as non-invasive and is applicable exclusively to the stratum corneum. Recently, optical and spectroscopic methods have been used to investigate the penetration process. Fluorescence-labelled drugs can be easily detected in the skin by laser scanning microscopy. This method has the disadvantage that the dye labelling changes the molecular structures of the drug and consequently might influence the penetration properties. The penetration process of non-fluorescent substances can be analysed by Raman spectroscopy, electron paramagnetic resonance, CARS and multiphoton microscopic measurements. Using these methods, the concentration of the topically applied formulations in different depths of the stratum corneum can be detected by moving the laser focus from the skin surface deeper into the stratum corneum. The advantages and disadvantages of these methods will be discussed in this article.

Infant epidermal skin physiology: adaptation after birth

BACKGROUND

Functional and structural skin adaptation is a dynamic process which starts immediately after birth in humans and in mammalian skin in general. This adjustment to the extrauterine dry environment is accomplished in the first year of postnatal life of humans.

OBJECTIVES

To assess the dynamic changes in vivo after birth in the molecular composition and skin physiology parameters compared with older children and adults.

METHODS

The molecular composition of the stratum corneum (SC) and the water profile were investigated noninvasively by in vivo Raman confocal microscopy as a function of depth. Functional parameters including transepidermal water loss (characterizing epidermal permeability barrier), capacitance (as an indirect parameter for SC hydration) and skin surface pH were assessed noninvasively. The measurements were performed in 108 subjects divided into six age groups: full-term newborns (1-15 days), babies aged 5-6 weeks, babies aged 6±1 months, children aged 1-2 years, children aged 4-5 years and adults aged 20-35 years.

RESULTS

We showed that skin acidification is still under development during the first weeks of life. While the basal epidermal barrier is competent immediately after birth, the SC is less hydrated in the first 2 weeks of postnatal life. Similar continuous decreasing water content towards the surface for all age groups was observed, whereas this gradient was lower for the newborns. Dynamic changes in the amounts of the natural moisturizing factor constituents were revealed in the period of infancy.

CONCLUSIONS

We demonstrated the relation of formation of an acidic pH as well as underlying mechanisms in the induction of a fully hydrated SC over the first weeks of human life as a dynamic functional adaptation.

Full-body skin mapping for six biophysical parameters: baseline values at 16 anatomical sites in 125 human subjects

BACKGROUND/AIM

The skin, as the outermost organ, protects against exogenous hazards (outside-in barrier) and prevents the loss of essential parts of the body (inside-out barrier). The epidermal barrier exerts several functions with specific morphological elements. Regional differences in skin functions are well known. The aim of the present study was to assess and compare skin physiological parameters in vivo at 16 anatomical sites: Barrier function in terms of transepidermal water loss (TEWL), stratum corneum (SC) hydration (assessed by capacitance), skin surface pH, skin surface temperature, erythema index and skin pigmentation were quantified at 16 anatomical sites under basal conditions. In addition, casual skin lipid level as a function of sebaceous lipids was measured on the forehead.

MATERIAL AND METHODS

The 6 functions at the 16 anatomical sites were assessed in a cohort of 125 volunteers working in the food processing industry. These functions were quantified with noninvasive instruments, namely a Tewameter (barrier function), a Corneometer (SC hydration), a pH-meter, a Mexameter (erythema index and pigmentation), a skin surface thermometer and a Sebumeter (casual sebum level).

RESULTS

We identified ranges for the 16 anatomical locations for each instrument and some parameters could be classified into distinctive groups. Furthermore, a left-right comparison was performed at 3 sites (dorsal hand, ventral hand and ventral forearm). Certain side differences could be shown for SC hydration, surface pH, erythema index, melanin index and skin surface temperature in the 3 assessed areas. A left-to-right, statistically nonsignificant difference was also established for TEWL.

CONCLUSION

The detected site-specific characteristics could be attributed to factors such as occlusion, different degrees of UV exposure, microcirculation and distribution of afferent and efferent nerve endings as well as fat distribution. External factors, such as life style, UV exposure and working conditions need to be taken into account. The present data are intended for an adequate selection of parameters and anatomical locations when assessing working conditions and designing clinical dermatological and pharmaceutical studies.

Increased mass levels of certain serine proteases in the stratum corneum in acute eczematous atopic skin

Acute eczematous atopic dermatitis (AD) is associated with increases in stratum corneum (SC) serine protease activity. The purpose of this study was to examine whether the increased SC protease activities in acute eczematous atopic dermatitis were associated with increased mass levels of SC proteases. Six subjects with healthy skin and six patients with AD each with non-lesional skin or lesional acute eczematous skin had the mass levels of their extractable SC kallikreins (KLK), plasmin and urokinase quantified using Luminex multiplex bead-based assays from SC tape strippings. The mass levels of KLK5 and KLK14 together with urokinase were not elevated in the SC in atopic skin. However, the mass levels of KLK7 and KLK11 together with plasmin were greatly elevated compared with the extracts from the non-lesional and the healthy skin and correlated with the corresponding enzymatic activities.

Topical retinoids in the management of photodamaged skin: from theory to evidence-based practical approach

Skin, being exposed directly to the environment, represents a unique model for demonstrating the synergistic effects of intrinsic and extrinsic factors on the ageing process. Ultraviolet radiation (UVR) is the major factor among exogenous stressors responsible for premature skin ageing. The problem of skin ageing has captured public attention and has an important social impact. Different therapeutic approaches have been developed to treat cutaneous ageing and to diminish or prevent the negative effects of UVR. Topical retinoids represent an important and powerful class of molecules in the dermatologist's hands for the treatment of photodamaged skin. Since their introduction more than 20 years ago, topical retinoids have shown beneficial efficacy and good safety profiles in the management of photodamaged skin, and as therapeutic anti-ageing agents. This review provides a brief retrospective of the development of topical retinoids in the treatment of photodamaged skin, elucidates their mechanism of action, delineates their use and addresses clinical, pharmaceutical and regulatory issues in connection with their intended use.

Positive effect of HPA lanolin versus expressed breastmilk on painful and damaged nipples during lactation

Painful and/or damaged nipples associated with breastfeeding are common and represent a challenge for both the persons experiencing nipple pain and/or trauma and for those providing treatment. However, evidence-based data has been insufficient to demonstrably minimize these common reasons for failure to initiate or continue successful breastfeeding. The aim of this study was to evaluate the efficacy of specific-grade highly purified anhydrous (HPA) lanolin versus expressed breastmilk (EBM) for the treatment of painful and damaged nipples associated with breastfeeding in a prospective controlled clinical trial evaluating 84 lactating mothers. Nipple trauma and healing rates were rated by the Nipple Trauma Score. Nipple pain intensity was assessed on a visual analog scale. Outcome parameters were in favor of the HPA lanolin group, reaching statistical significance for healing rates, nipple trauma and nipple pain. In our study, we found HPA lanolin more effective than EBM, inducing faster healing of nipple trauma (absolute risk reduction of 0.43) and reducing nipple pain (absolute risk reduction of 0.61 on day 3). We concluded that HPA lanolin, combined with breastfeeding education, was more effective than EBM, combined with breastfeeding education, in reducing nipple pain and promoting healing of nipple trauma.

Clinical study on the effects of a cosmetic product on dermal extracellular matrix components using a high-resolution multiphoton tomograph

BACKGROUND/PURPOSE

The aim of this study was to demonstrate the effects of selected plant extracts in a cosmetic cream on the dermal network components after a 3-month treatment using an in vivo multiphoton tomographic device.

METHODS

Twenty-four Caucasian women aged between 45 and 65 applied randomly a cosmetic emulsion B containing active ingredients (soy and jasmine) twice a day on one arm and its vehicle A (without active ingredients) on the other arm during 3 months. Measurements were performed on the internal side of the forearm before starting the treatment (T0), after 4 week (T4) and 12 weeks (T12) treatment. Measurements consisted of a multi-layers acquisitions using a multiphoton tomograph with subcellular resolution. Optical sections (about 6 microm thick) were recorded from 0 to about 200 microm using two different wavelengths: 760 and 820 nm. To compare the series of images and obtain an objective quantification of the signal of second harmonic generation (SHG) and autofluorescence, the method used consisted of taking the integrated brightness of an image (same rectangular area for all images) as a measure of the signal. Following this step, a ratio between brightness of images from the area treated with cream A or B and brightness of untreated area was calculated and used as an assessment of treatment efficacy. The parameter used for statistical analysis (variance analysis) is the difference before and after 12 weeks of treatment by either cream A or B of the signal ratios calculated in the upper dermis (118-130 microm) and those from a deeper region of the upper dermis (165-178 microm).

RESULTS

Signals (autofluorescence+SHG) of extracellular matrix do not change significantly with time (weeks 0, 4 and 12) when cream A (vehicle with no active ingredient) is applied. Treatment with cream B results in an enhancement in the signal level of extracellular matrix at week 12. The comparison of signals, in both areas (118-130 microm and 160-178 microm), show an higher increase in the deeper region than in the more superficial one for product B while we do not notice any change with product A.

CONCLUSION

The multiphoton tomograph provided excellent high-resolution images, which describe clearly the different skin layers, single cells and extracellular matrix components in all the 24 volunteers. Statistic analyses reveal a real effect for product B with selected plant extracts, known to increase collagen synthesis. Changes observed are characteristics of modifications in dermal collagen and elastin content. To our knowledge, it is the first time that it was possible to demonstrate in vivo the effect of a cosmetic product on the superficial dermal layer, in a non-invasive and non-destructive process, i.e. without cutting the skin.

Sun-induced changes in stratum corneum function are gender and dose dependent in a Chinese population

Previous studies have demonstrated that UVB radiation changes the epidermal permeability barrier and stratum corneum (SC) hydration. It is well known that sun exposure causes erythema, sunburn and melanoma. However, whether daily sun exposure alters SC integrity and epidermal permeability barrier function is largely unknown, especially in Chinese subjects. In the present study, we assess the SC integrity, SC hydration and epidermal permeability barrier function following various doses of sun exposure. A total of 258 subjects (124 males and 134 females) aged 18-50 years were enrolled. A multifunctional skin physiology monitor (Courage & Khazaka MPA5) was used to measure SC hydration and transepidermal water loss (TEWL) on the forearms. In males, basal TEWL was higher with higher doses of sun exposure than with lower doses and control, whereas in females, basal TEWL was higher with lower doses of sun exposure than with higher doses and control. In the group with higher doses of sun exposure, TEWL in females was significantly lower than that in males. The barrier recovery was faster in females than in males in both control and lower-dose groups. In both males and females, barrier recovery was delayed with higher doses of sun exposure. In males, sun exposure did not alter SC hydration, while in females SC hydration was lower with lower doses of sun exposure as compared with control and higher doses of sun exposure. These results demonstrated that sun-induced changes in SC function and SC hydration vary with gender and the extent of sun exposure.

Natural moisturizing factor components in the stratum corneum as biomarkers of filaggrin genotype: evaluation of minimally invasive methods

BACKGROUND

The carriers of loss-of-function mutations in the filaggrin gene (FLG) have reduced levels of natural moisturizing factor (NMF) in the stratum corneum. The concentration of NMF components which are formed by filaggrin protein breakdown in the stratum corneum might therefore be useful as a biomarker of the FLG genotype. OBJECTIVES To investigate the feasibility of different sampling methods for the determination of two NMF components, 2-pyrrolidone-5-carboxylic acid (PCA) and urocanic acid (UCA), in the stratum corneum as biomarkers for the FLG genotype.

METHODS

PCA and UCA from the stratum corneum were sampled by using a tape stripping technique and an extraction technique using skin patches containing potassium hydroxide (KOH). The concentrations of PCA and UCA were measured by high-performance liquid chromatography. Eleven carriers of an FLG mutation and 10 individuals wild type for the two most common FLG mutations (R501X and R2447X) [corrected] were included in the study.

RESULTS

The most significant difference between the FLG genotypes was found for PCA sampled by the tape stripping technique. The mean values of PCA obtained by the tape stripping technique were, respectively, 0.18, 0.50 and 1.64 mmol g(-1) protein in homozygous (or compound heterozygous), heterozygous and wild-type genotypes (P < 0.005 homozygous vs. heterozygous; P < 0.0001 heterozygous vs. wild type). The tape stripping technique showed less intrasubject variation compared with the KOH patches, in particular when the concentrations of UCA and PCA on the tape strips were normalized for protein amount.

CONCLUSIONS

The concentration of PCA in the stratum corneum collected by tape stripping showed it to be a feasible biomarker of the FLG genotype.

Increased stratum corneum serine protease activity in acute eczematous atopic skin

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory disease associated with changes in stratum corneum (SC) structure and function. The breakdown of epidermal barrier function in AD is associated with changes in corneocyte size and maturation, desquamation, lipid profiles, and some protease activities.

OBJECTIVES

The purpose of this study was: (i) to examine physiological changes in lesional (L) skin of acute eczematous AD, compared with nonlesional (NL) AD skin and healthy (H) skin, using sequential tewametry and SC protein analysis to estimate SC thickness; and (ii) to assess which serine proteases might be involved in pathogenesis.

METHODS

Six subjects with H skin, six AD patients with NL skin and six AD patients with mild to moderate eczema (L skin) were enrolled. Skin was assessed using several noninvasive techniques but SC thickness was estimated using tewametry and SC protein content of D-Squame strippings. SC integrity was determined by sequential tape stripping (D-Squame) and infrared densitometry. Kallikreins, plasmin, urokinase and leucocyte elastase protease activities together with a novel SC tryptase-like enzyme activity were quantified.

RESULTS

Transepidermal water loss (TEWL) levels after D-Squame stripping were elevated in L compared with NL and H skin at all sampling points (P < 0.05). Conversely, the amount of SC removed by sequential tape stripping was decreased in L skin, indicating increased intracorneocyte cohesion (P < 0.05). By correlating 1/TEWL values and SC removed as an estimate of SC thickness, a significantly thinner SC was observed in L compared with NL and H skin (P < 0.05). Elevated extractable serine protease activity was measured in AD skin in the order: SC tryptase-like enzyme (45x), plasmin (30x), urokinase (7.1x), trypsin-like kallikreins (5.8x) and chymotrypsin-like kallikreins (3.9x). Leucocyte elastase activity was not detected in H and NL skin but was observed in AD SC samples (L skin). All enzymes were elevated in the deeper layers of L SC compared with NL and H SC samples. All consistently elevated SC protease activities were significantly correlated with the bioinstrumental data.

CONCLUSIONS

We report increased serine protease activities in acute eczematous AD, especially in deeper layers of the SC, including SC tryptase-like enzyme, plasmin, urokinase and leucocyte elastase activities. These elevations in protease activities were associated with impaired barrier function, irritation, and reduced skin capacitance. Increased SC cohesion was apparent despite elevated TEWL during tape stripping, which would indicate reduced SC thickness in acute eczematous lesions of AD. Indeed, this was observed using an estimate of SC thickness.

Non-invasive in vivo methods for investigation of the skin barrier physical properties

Skin as an organ of protection covers the body and accomplishes multiple defensive functions. The intact skin represents a barrier to the uncontrolled loss of water, proteins, and plasma components from the organism. Due to its complex structure, the epidermal barrier with its major component, stratum corneum, is the rate-limiting unit for the penetration of exogenous substances through the skin. The epidermal barrier is not a static structure. The permeability barrier status can be modified by different external and internal factors such as climate, physical stressors, and a number of skin and systemic diseases. Today, different non-invasive approaches are used to monitor the skin barrier physical properties in vivo. The quantification of parameters such as transepidermal water loss, stratum corneum hydration, and skin surface acidity is essential for the integral evaluation of the epidermal barrier status. Novel methods such as in vivo confocal Raman microspectroscopy offer the possibility for precise and detailed characterization of the skin barrier. This paper will allow the readership to get acquainted with the non-invasive, in vivo methods for the investigation of the skin barrier.

Glycerol and the skin: holistic approach to its origin and functions

Glycerol is a trihydroxy alcohol that has been included for many years in topical dermatological preparations. In addition, endogenous glycerol plays a role in skin hydration, cutaneous elasticity and epidermal barrier repair. The aquaporin-3 transport channel and lipid metabolism in the pilosebaceous unit have been evidenced as potential pathways for endogenous delivery of glycerol and for its metabolism in the skin. Multiple effects of glycerol on the skin have been reported. The diverse actions of the polyol glycerol on the epidermis include improvement of stratum corneum hydration, skin barrier function and skin mechanical properties, inhibition of the stratum corneum lipid phase transition, protection against irritating stimuli, enhancement of desmosomal degradation, and acceleration of wound-healing processes. Even an antimicrobial effect has been demonstrated. Topical application of glycerol-containing products improves skin properties in diseases characterized by xerosis and impaired epidermal barrier function, such as atopic dermatitis. The increase of epidermal hydration by glycerol is critical in skin conditions aggravated by dry and cold environmental conditions, e.g. winter xerosis. This paper provides a review on effects of glycerol on the skin, the mechanisms of its action, and the potential applications of glycerol in dermatology.

Activity of different desoximetasone preparations compared to other topical corticosteroids in the vasoconstriction assay

INTRODUCTION

We report on a double-blind, vehicle-controlled, single-center confirmatory study with random assignment. The purpose of the study was to investigate the topical bioavailability of different topical corticosteroid formulations in healthy human beings focussing on desoximetasone (DM).

MATERIALS AND METHODS

Two DM 0.25% formulations [ointment (DM-o) and fatty ointment (DM-fo, water-free); class III corticosteroids], the corresponding active ingredient-free vehicles and three comparators of different strength [clobetasol propionate 0.05% (CP 0.05%), fatty ointment, class IV; hydrocortisone (HC) 1%, fatty ointment, class I, and betamethasone (BM) 0.05%, fatty ointment, class III] were tested using the vasoconstriction assay. The degree of vasoconstriction (blanching) in the treatment field was compared to the one found in untreated control fields using chromametric measurements and clinical assessment.

RESULTS/CONCLUSION

DM-o 0.25%, DM-fo 0.25% and BM 0.05% showed similar vasoconstrictive potential, i.e., clear blanching. In fact, both DM preparations were proven to be noninferior to BM 0.05%, while CP 0.05% was found a little less active. HC 1.0% and the DM vehicles showed no clear-cut vasoconstrictive effect. No adverse events related to the study medications were observed. Good topical bioavailability of both DM formulations was detected by chromametric measurement and clinical assessment.

Skin irritation and sensitization: mechanisms and new approaches for risk assessment. 1. Skin irritation

Cutaneous irritation presents a major health problem with serious social and occupational impact. The interaction between an irritant and the human skin depends on multiple factors: the intrinsic properties and the nature of the irritant itself, and specific individual- and environment-related variables. The main pathological mechanisms of irritancy include skin barrier disruption, induction of a cytokine cascade and involvement of the oxidative stress network; all of them resulting in a visible or subclinical inflammatory reaction. In vivo, different non-invasive parameters for the evaluation of skin irritation and irritant potential of compounds and their specific formulations have been introduced, such as epidermal barrier function, skin hydration, surface pH, lipid composition, skin colour and skin blood flow. The diverse physiological changes caused by irritating agents require implementation of a multiparametric approach in the evaluation of cutaneous irritancy.

Acute barrier disruption by adhesive tapes is influenced by pressure, time and anatomical location: integrity and cohesion assessed by sequential tape stripping. A randomized, controlled study

BACKGROUND

Tape stripping is an established procedure in stratum corneum (SC) physiology research. Adhesive films are pressed to the surface of the skin and then removed. The superficial layers of the SC adhere to the film and are accessible for further investigations. Although this method is widely used, only scant information about standardization is known. Various protocols are used but are difficult to compare.

OBJECTIVES

The aim of the present study was to investigate the effects of the type of tape, pressure, time, anatomical site and type of applied pressure.

METHODS

Twelve healthy volunteers (age range 20-31 years) were entered in a randomized, controlled study with sequential tape stripping at the volar forearm, upper arm, cheek and back. Different methods (roller, stamp, thumb, stretched skin), total duration of applied pressure (2 s, 10 s), degrees of pressure (2 N stamp, 7 N stamp) and different tapes (D-Squame, Corneofix, Blenderm) were investigated and the impact on barrier function assessed by transepidermal water loss measurements. Furthermore, measurements of SC hydration, skin colour and skin surface pH were performed. Spectroscopic measurements and a Bradford protein assay to determine the mass of removed SC were carried out in parallel.

RESULTS

The degree of barrier disruption, irritation and SC cohesion is influenced by the character of adhesive tapes, total duration of applied pressure (2 s, 10 s; 2 N, 7 N), the kind of method for pressure application (roller, stamp, thumb, stretched skin), anatomical site and condition before stripping (occlusion vs. nonocclusion). The spectroscopic assessment and Bradford protein assay determination showed a significant correlation (P < 0.0001; r = 0.7041).

CONCLUSIONS

The present study showed significant differences between different factors on controlled barrier disruption. The results indicate the importance of defining these factors when a study is initiated and when results of different studies should be compared. Based on our data we propose using a 2 N stamp for a duration of 2 s on 15 sequential D-Squame tape strips on the volar forearm and then discarding the first and second strips. This approach allows the performance of a standardized study with a reasonable amount of resources.

Functional Assessment of a Skin Care System in Patients on Chemotherapy

BACKGROUND/PURPOSE

Cancer patients undergoing chemotherapy frequently experience skin problems such as xerosis. The aim of this study was to verify whether a concomitant treatment with an acidic washing and an acidic emollient (both pH 5.5) can significantly improve the quality of the skin in such patients.

METHODS

30 adult patients on chemotherapy experiencing dry and sensitive skin were included in a controlled, monocentric, 3-week treatment trial. One forearm served as a test site, the other one remained untreated. Noninvasive biophysical measurements were performed at baseline, on days 7, 14 and 21, along with clinical evaluation of the skin symptoms.

RESULTS

After a 3-week treatment, a significant increase in stratum corneum hydration was recorded in the treated site (p < 0.001). Reduced transepidermal water loss values, consistent with a restored barrier function, were obtained (p < 0.001). Casual sebum levels as measured by sebumetry showed a significant increase (p < 0.03). All skin symptoms investigated revealed a considerable improvement over 3 weeks.

CONCLUSION

Controlled and regular use of a skin care system, especially an acidic one, improved skin physiology in patients undergoing chemotherapy.

Assessment of anti-inflammatory activity of Poria cocos in sodium lauryl sulphate-induced irritant contact dermatitis

OBJECTIVE

In the present study, we evaluated the anti-inflammatory activity of Poria cocos (PoCo) on experimentally induced irritant contact dermatitis (ICD) in a repeated sodium lauryl sulphate (SLS) irritation model.

METHODS

The anti-irritative effect of PoCo was evaluated with a visual score and quantified by non-invasive bioengineering methods, namely chromametry and transepidermal water loss. Three concentrations of PoCo in base cream DAC (amphiphilic emollient; German pharmacopoeia) were tested in a 4-day repetitive irritation test using SLS.

RESULTS

A statistically significant anti-inflammatory activity was observed for PoCo by all three methods when applied in parallel to the induction period of ICD. Application of PoCo after induction of ICD once a day for 5 days, starting just at the end of 4 days, was without any effect.

CONCLUSION

An anti-inflammatory efficacy of PoCo on the elicitation phase of the ICD induced by repeated SLS test could be observed and quantified by three independent, non-invasive biophysical assessment parameters. This effect can be explained by its influence on pro-inflammatory enzymes, namely phospholipase A2.

Efficacy and safety testing. The clinical perspective

The number of workplace substances is uncountable, and technical progress enforces the adaptation of substances such as cutting fluids to the new demands. For that reason new substances can hardly be tested in in vivo studies. In vitro models are widely used to test the effects of barrier creams since they are simple, rapid and safe. Since no animal model could perfectly mimic human percutaneous absorption, these tests are particularly recommended as screening procedures for barrier cream candidates. A number of in vivo methods exist whereupon conventional, non-invasive bioengineering methods, along with clinical scoring, provide the most accurate, highly reproducible assessment of the inflammatory response to irritants and allergens. Nevertheless, no general accepted procedure for the evaluation of skin protection products exists. It is essential that all the products applied to the skin (protective creams inclusive) should be clinically tested in order to verify their propensity for causing cutaneous reactions. Safety testing is a stepwise approach, comprising various in vitro and in vivo test models. The nature of the plausible biological or even toxic reactions that might occur and the types of tests designed to determine the safety of the topical formulations in men are described in this chapter.

Microtubules Regulate Expression of ICAM-1 in Epidermoid Cells (KB Cells)

The intercellular adhesion molecule-1/CD54 (ICAM-1) functions as a counterreceptor for other adhesion molecules (e.g. the lymphocyte function-associated antigen-1/CD11a/CD18) required for the interaction of a large variety of cells with leucocytes. Constitutive expression of ICAM-1 in human epidermoid cells (KB cells) is low, but inducible by interferon-gamma (IFN-gamma). Treatment of KB cells with microtubule-disrupting agents, like colchicine, nocodazole and vinblastine, potentiated the constitutive and cytokine-induced ICAM-1 expression on the cell surface. Actinomycin D inhibited microtubule-disrupting agent-induced ICAM-1 surface expression. Increased steady-state levels of ICAM-1 transcripts were found after treatment of KB cells with microtubule-disrupting agents. However, microtubule-disrupting agents neither altered the glyceraldehyde-3-phosphate dehydrogenase mRNA levels nor the amount of expressed alpha(2)-, alpha(3)-and beta(1)-integrins at the cell surface. In addition, they did not change the ICAM-1 mRNA half-life. These studies indicate a control function of the microtubule network on the expression of ICAM-1.

Significance of interleukin-16, macrophage-derived chemokine, eosinophil cationic protein and soluble E-selectin in reflecting disease activity of atopic dermatitis--from laboratory parameters to clinical scores

BACKGROUND

The search for the ideal clinical score reflecting atopic dermatitis (AD) severity has developed in parallel with unveiling key events in disease pathogenesis and finding laboratory parameters for monitoring disease activity. A major difficulty in assessing the relevance of reported serum markers of AD severity is the use of nonvalidated referent tools, which compromises comparison of results across studies.

OBJECTIVES

The aim of our study was to compare the significance of serum levels of interleukin (IL)-16, macrophage-derived chemokine (MDC), soluble E-selectin (sE-selectin) and eosinophil cationic protein (ECP) in reflecting AD severity and identify the most relevant parameter for monitoring the course of disease. Serum levels were tested against the same referent severity score in the same time frame and group of patients.

METHODS

The Severity Scoring of Atopic Dermatitis (SCORAD) index was used for assessment of disease severity in 21 adult patients in acute stage of AD and after complete resolution of clinical findings. Serum levels of IL-16, MDC, ECP and sE-selectin were measured at the same time points in 18 patients and compared with healthy nonatopic controls. The correlation between SCORAD and each laboratory parameter was tested for significance and compared.

RESULTS

Serum levels of IL-16, MDC, ECP and sE-selectin were significantly higher in patients in acute stage of AD compared with controls and decreased significantly after treatment, in parallel with clinical improvement. All monitored parameters reflected disease severity assessed by the clinical score. We found the highest significance level of correlation with SCORAD for IL-16 (r = 0.68, P =0.0019), followed by ECP (r = 0.65, P = 0.0032) and MDC (r = 0.55, P =0.0326). There was significant correlation between serum levels of IL-16 and MDC (r = 0.53, P = 0.0443) and ECP and sE-selectin (r = 0.48, P = 0.0427).

CONCLUSIONS

The study established a significant correlation between serum levels of IL-16 and SCORAD in adult AD patients. We report a significant correlation between IL-16 and MDC, both T-helper 2 activation markers. Our data suggested that IL-16 reflects most convincingly disease severity and may be used as a marker in clinical studies preferentially in combination with a clinical activity score.

Chronobiology: biological clocks and rhythms of the skin

The cyclicity of time affects virtually all aspects of our being and is the basis of the underlying rhythmicity which is typical of our lives. To 'tell time', most living organisms use internal timing mechanisms known as 'biological clocks'. These 'clocks' coordinate our physiological and behavioral functions and interactions with our environment. One of the strongest influences on rhythmicity is the solar day. The study of these temporal rhythms in biological systems has been coined chronobiology. With the present article we aim to give an overview on chronobiology. Examples of chronobiological effects on skin will be described. Particular emphasis will be placed on circadian rhythms (including rhythms that take place within a 24-hour period, including so-called infradian and/or diurnal rhythms) but also on seasonal variations (circaannual rhythms).

The objective severity assessment of atopic dermatitis (OSAAD) score: validity, reliability and sensitivity in adult patients with atopic dermatitis

BACKGROUND

The Objective Severity Assessment of Atopic Dermatitis (OSAAD) score is a recently developed scale for evaluation of severity of atopic dermatitis, constructed from the assessment of epidermal barrier function, and properties using noninvasive bioengineering methods and computer-assisted estimates of disease extent. The method has been validated for use in infants and children with atopic dermatitis and compared with a referent scoring system.

OBJECTIVES

The aim of the present study was to test the validity, reliability and sensitivity of the OSAAD score as an objective tool for the assessment of the severity of atopic dermatitis in adult patients.

METHODS

Thirty-two adult patients with atopic dermatitis were included in the study. To assess the validity of the OSAAD score we tested it against the Severity Scoring of Atopic Dermatitis (SCORAD) index of the European Task Force on Atopic Dermatitis as a referent clinical severity scale, and the serum levels of interleukin (IL)-16 as a laboratory variable for monitoring the activity of atopic dermatitis. Responsiveness to change was assessed in a longitudinal study comparing OSAAD, SCORAD and serum levels of IL-16 before and after treatment. To test the reliability of the OSAAD score we studied the interobserver variability of the score recorded by three independent board-certified dermatologists in 16 patients and compared it with SCORAD.

RESULTS

We report a significant correlation between the OSAAD and the SCORAD index as an acknowledged referent severity scale. The OSAAD score correlated significantly with the serum levels of IL-16 in the acute stage of atopic dermatitis. In a longitudinal study, the OSAAD score decreased significantly, parallel with improvement of the skin findings and a significant decrease in the SCORAD score and IL-16 serum levels. We report improved interobserver variability for the OSAAD score compared with SCORAD.

CONCLUSIONS

This is the first study validating the OSAAD score as a sensitive and reliable tool for the assessment of the severity of atopic dermatitis in adult patients.

Additive impairment of the barrier function and irritation by biogenic amines and sodium lauryl sulphate: a controlled in vivo tandem irritation study

Biogenic amines are potential irritants e.g. in fish-, meat-, milk- and egg-processing professions like cooks, butchers and bakers. The aim of this study was to test the irritative and barrier-disrupting properties of the biogenic amines ammonium hydroxide (AM), dimethylamine (DMA) and trimethylamine (TMA). A repeated sequential irritation of 30 min twice per day was performed over a total of 4 days (tandem repeated irritation test) on the back of 20 healthy volunteers of both sexes with AM, DMA, TMA and sodium lauryl sulphate (SLS). The epidermal barrier function was assessed with a Tewameter TM 210, stratum corneum surface pH was measured with a Skin-pH-Meter 900, inflammation was assessed with a Chromameter CR-300 on the a* axis for redness and a visual score was recorded. All tested biogenic amines (AM, DMA and TMA) induced a barrier disruption and a pH increase paralleled with a 1-day-delayed onset of inflammatory signs. These effects were further enhanced and accelerated by a sequential application of SLS together with the biogenic amines, and inflammation occurred earlier than with the single compounds. Acetic acid (AA) in contrast did only show mild barrier disruption and no significant inflammatory signs. Our system allowed a ranking of the different compounds in their irritative potential in the tandem irritation with SLS: SLS > NaOH > TMA > AA > AM > DMA. The results are suggestive that in the food-processing industry the simultaneous contact with biogenic amines and harmful detergents like SLS should be minimized.

Additive impairment of the barrier function by mechanical irritation, occlusion and sodium lauryl sulphate in vivo

BACKGROUND

The interaction between potential irritants in the workplace might be important because workers are not usually exposed to a single irritant, but to multiple potentially harmful substances. Physical irritant contact dermatitis caused by friction or mechanical abrasion is a common occupational dermatosis. Prolonged water exposure by occlusion is also common in the workplace. Several studies have revealed the negative effect of the common anionic detergent sodium lauryl sulphate (SLS) on permeability barrier function.

OBJECTIVES

To study the additive impairment of permeability barrier function by mechanical irritation combined with 0.5% SLS or prolonged water exposure by occlusion, as models of mild irritation.

METHODS

The volar forearms of 20 healthy volunteers were exposed to mechanical irritation and occlusion with water or 0.5% SLS for four consecutive days in a combined tandem repeated irritation test (TRIT). Permeability barrier function was measured with a Tewameter TM 210. Irritation was assessed with a Chromameter CR 300 and a visual score.

RESULTS

Barrier disruption in our model was rated as follows: occlusion with SLS and mechanical irritation > occlusion with SLS > occlusion with water and mechanical irritation > mechanical irritation and occlusion with water > occlusion with a glove and mechanical irritation > mechanical irritation > occlusion with water. Barrier disruption caused by occlusion or mechanical irritation was enhanced by the tandem application. The choice of irritant under occlusion, time of occlusion and order of tandem application all affected the degree of barrier disruption. Evaporimetry was able to detect early stages in the development of an irritant reaction before it became visible. Chromametry was not able to detect this early response.

CONCLUSIONS

Physical irritants (friction, abrasive grains, occlusion) and detergents such as SLS represent a significant irritation risk and should be minimized, especially when acting together, as shown in our TRIT model.

Antimikrobiell wirksame Magistralrezepturen

Triphenyl-methan dyes, traditionally used in dermatology should be reevaluated with caution. Their use should be limited due to the uncertain pharmacological-toxicological risk-benefit ratio and the lack of pharmacological quality of the raw substances. Sometimes antimicrobial activity is insufficient and the cytotoxic effects, along with the inhibition of wound healing, make these dyes less suitable for topical treatment in dermatology. Chinolinolsulfat (Chinosol) and Clioquinol should be used in low concentrations and only on small areas. Due to their negative benefit-risk profile ethracidinlactate-monohydrate (Rivanol) and phenylmercuri-borate (Mercuchrom) should not be used as topical antimicrobial substances. The present publication is intended to give practical recommendations on compounded medications for topical antimicrobial use. Even though some of the cited compounds must be considered critically, we recommend the topical use of chlorhexidine salts, polihexanide, triclosan, polyvidone iodide and silver compounds. Useful standardised compounded formulations containing these four groups are listed in the NRF (Neues Rezeptur Formularium: New German Pharmacopoeia for compounded medication).

Air flow at different temperatures increases sodium lauryl sulphate-induced barrier disruption and irritation in vivo

BACKGROUND

Combined exposure to dry climatic conditions and local heat sources together with detergents represents a common workplace situation. These conditions may support the induction of chronic barrier disruption leading subsequently to irritant contact dermatitis (ICD).

OBJECTIVES

To test the irritant and barrier disrupting properties of air flow at different temperatures and velocities.

METHODS

Using noninvasive biophysical measurements such as transepidermal water loss (TEWL) (TM 210; Courage & Khazaka, Cologne, Germany) we assessed the effects of short-term exposure to air flow at different temperatures (24 degrees C and 43 degrees C) in combination with sodium lauryl sulphate (SLS) 0.5% on the skin of 20 healthy volunteers in a tandem repeated irritation test. Chromametry was used to control the accuracy of the SLS irritation model.

RESULTS

In our study air flow alone did not lead to a significant increase in TEWL values. Sequential treatment with air flow and SLS led to an impairment of barrier function and irritation stronger than that produced by SLS alone. The two different air flow temperatures led to different skin temperatures but had no influence on permeability barrier function.

CONCLUSIONS

Warm air flow has an additional effect on the SLS-induced barrier disruption in a tandem irritation test with sequential exposure to SLS/air flow. This combination is suspected to promote ICD in workplace and household situations, especially in short-term applications as tested in our model.

Sequential application of cold and sodium lauryl sulphate decreases irritation and barrier disruption in vivo in humans

BACKGROUND

Irritant contact dermatitis (ICD) is one of the most frequent types of occupational dermatitis. Different factors are involved in the development of contact dermatitis. In the food-processing industry, the combined exposure to different irritants may be involved in the development of ICD. Few data have been published regarding the irritant potential of sodium lauryl sulphate (SLS) in combination with cold.

OBJECTIVES

The present study was intended to analyse whether cold exposure and low skin temperature influence the development of ICD.

METHODS

Twenty (part I) and 12 (part II) healthy volunteers were exposed twice daily for 4 days to SLS alone, different low temperatures alone (4 degrees C six times for 90 s with an interval of 20 s or 15 degrees C for 10 min) or a combination of cold and SLS (19.6 microL SLS 1% cm(-2), part I; or 52.6 microL SLS 0.5% cm(-2), part II) using the tandem repetitive irritation test. Irritant cutaneous reactions were measured by noninvasive biophysical methods with transepidermal water loss as a parameter for permeability barrier function and skin colour reflectance together with visual scoring as parameters for inflammatory reactions.

RESULTS

Cold alone caused no significant skin reaction compared with untreated control. Exposure to SLS alone and SLS together with cold (independent of the applied temperature of 4 or 15 degrees C) twice daily induced a clear irritant reaction and barrier disturbance. Reactions did not differ whether SLS was applied before or after cold. Furthermore, 'tandem application' of cold and SLS diminished the barrier disruption and irritant reaction compared with SLS alone.

CONCLUSIONS

We conclude that the application of cold may have a protective effect on the development of ICD, at least in our short-term model.

Functional assessment of a washing emulsion for sensitive skin: mild impairment of stratum corneum hydration, pH, barrier function, lipid content, integrity and cohesion in a controlled washing test

BACKGROUND/PURPOSE

Sensitive skin has been described as a skin type with higher reactivity than normal skin and exaggerated reactions to external irritants. Washing with soaps is harmful for barrier-related parameters. Cutaneous irritation induced by cleansing products under exaggerated test conditions, e.g. patch testing, is not necessarily predictive of the irritation occurring under standardized daily use conditions. The purpose of the study was to assess the effect of an improved washing solution for sensitive skin in a half-site comparison on barrier-related parameters.

METHODS

Thirty healthy volunteers with self-reported sensitive and so-called problematic skin performed standardized washings with a soap-free washing emulsion with mild acidity (pH 5.5) for 3 weeks. Test areas were both forearms and the cheek. Non-invasive biophysical measurements of the following skin parameters, epidermal permeability barrier function measured as transepidermal water loss (TEWL), stratum corneum (SC) hydration, pH value, skin surface lipids, skin temperature and SC integrity/cohesion, were assessed prior to the first washing, on days 7, 14 and 21 after beginning the washing procedure. SC cohesion was quantified using two independent methods on D-Squame tapes: optical spectroscopy measuring the absorbance and a protein assay assessing the total protein (Bradford). Both methods showed a good correlation. SC integrity was quantified by measuring TEWL after sequential stripping with D-Squame tapes.

RESULTS

The use of the washing emulsion led to a mild damage of the epidermal permeability barrier function with no marked difference to water application. Furthermore, a mild but significant dehydration was assessed after 21 days vs. baseline without any differences between the water-treated and the washing emulsion-treated forearm. On the cheek no dehydration was detectable but the lipid content was reduced under the washing emulsion. The pH value increased in all three test areas after 21 days, again without significant differences between water and the washing solution. SC cohesion was quantified using two independent methods on D-Squame tapes: optical spectroscopy measuring the absorbance and a protein assay assessing the total protein (Bradford). Both methods showed a good correlation. The SC cohesion decreased after 21 days on the water-treated as well as on the washing emulsion-treated arm. The decrease over time was significant when used the optical spectroscopy measuring. A standardized questionnaire revealed positive characteristics of the washing emulsion and good acceptance.

CONCLUSION

The investigated standardized washing model with the endpoints epidermal barrier function, SC hydration, surface pH, skin surface lipids, skin temperature and SC integrity/cohesion showed only mild damage comparable to washing with water.

The quality of human skin xenografts on SCID mice: a noninvasive bioengineering approach

BACKGROUND

Animal models are important tools for studies in skin physiology and pathophysiology. Due to substantial differences in skin characteristics such as thickness and number of adnexa, the results of animal studies cannot always be directly transferred to the human situation. Therefore, transplantation of human skin on to SCID (severe combined immunodeficiency) mice might offer a promising tool to perform studies in viable human skin without the direct need for human volunteers.

OBJECTIVES

To characterize the physiological and anatomical changes of a human skin transplant on a SCID animal host.

METHODS

In this study human skin was transplanted on to 32 SCID mice and followed for 6 months. Barrier function was assessed by transepidermal water loss (TEWL; tewametry) and moisture content of the stratum corneum was studied by measurement of electrical capacitance (corneometry).

RESULTS

The results showed considerable deviations of TEWL values and skin hydration between the grafts and human skin in vivo. The human skin showed epidermal hyperkeratosis and moderate sclerosis of the corium 4 and 6 months after transplantation on to SCID mice.

CONCLUSIONS

Our results indicate that human skin does not completely preserve its physiological and morphological properties after transplantation on to SCID mice. Therefore, results from experiments using this model system need to be discussed cautiously.

Fruit acids and sodium hydroxide in the food industry and their combined effect with sodium lauryl sulphate: controlled in vivo tandem irritation study

BACKGROUND

Cutaneous exposure to a variety of irritants has been extensively studied in recent years. Nevertheless, knowledge of the induction of irritant dermatitis, especially by mild irritants at low doses and for a short duration of exposure, is still incomplete.

OBJECTIVES

To quantify the irritant effects and barrier disruption properties of ascorbic acid (ASC), acetic acid (ACA) and sodium hydroxide (NaOH), particularly in combination with an anionic detergent, sodium lauryl sulphate (SLS).

METHODS

In a tandem repeated irritation test, the irritants were applied for 30 min twice daily for 4 days to the skin of the mid-back of 19 healthy volunteers of both sexes. We used bioengineering techniques for measurement of transepidermal water loss (TEWL) and skin colour reflectance, as well as visual scoring.

RESULTS

Repeated application of ASC and ACA caused a moderate increase in TEWL and erythema. The sequential application of ASC or ACA and SLS enhanced these effects. NaOH induced a strong reaction when applied both occlusively and nonocclusively as well as in combination with SLS, with an early onset of the inflammatory signs, leading to discontinuation of the application on the third day in most of the test fields. Notably, the irritant effect of NaOH was not as marked when applied sequentially with SLS.

CONCLUSIONS

Our results demonstrate that concurrent application of an anionic detergent and a mild acidic irritant can lead to disruption of the barrier function which, although not additive, is still considerable. The combined application of SLS and mild acids does not prevent SLS-induced irritation. Furthermore, we showed that NaOH in low concentrations may also act as a potent irritant but that its effect is not enhanced by SLS. The necessity of adequate skin protection and reduction of contact with substances that are potentially barrier disruptive and irritant, e.g. in the food industry, is emphasized, not only when handling detergents, but also when processing food products.

Percutaneous Penetration of Topically Applied Melatonin in a Cream and an Alcoholic Solution

In a clinical study, the skin penetration properties of melatonin 0.01% in a cream and 0.01 and 0.03% in a solution were investigated by evaluation of the serum melatonin levels over a 24-hour time course in 15 healthy volunteers. Blood samples for melatonin measurements were taken at 9.00 a.m. before applying the test preparations and 1, 4, 8 and 24 h after application. The measurements were carried out by radioimmunoassay for melatonin. In 15 volunteers, the serum levels of melatonin before application of the topical preparations were between 0.6 and 15.9 pg/ml. After application of the 0.01% melatonin cream, there was a steady increase starting from 9.00 a.m. up to a mean serum value of 9.0 pg/ml at 9.00 a.m. the next day. The solution of 0.01% melatonin also showed an increase, starting from 5.00 p.m., up to a mean melatonin level of 12.7 pg/ml 24 h after application. The solution containing 0.03% melatonin resulted in elevated melatonin levels 1 and 8 h after application. The values were 18.1 and 19.0 pg/ml. The cumulative melatonin values for each preparation were 7.1, 8.6 and 15.7 pg/ml, respectively. This study shows that the strongly lipophilic substance melatonin is able to penetrate through the skin and leads to dose- and galenic-dependent melatonin levels in the blood. No increase of melatonin above the physiological range was observed.

Impact of anatomical location on barrier recovery, surface pH and stratum corneum hydration after acute barrier disruption

BACKGROUND

It is not known whether distinct anatomical locations will respond with different recovery rates following acute barrier challenges.

OBJECTIVES

To investigate whether barrier parameters differ at five body sites during recovery from acute disruption.

METHODS

Acute barrier disruption was achieved by tape stripping and by acetone extraction of stratum corneum lipids. Transepidermal water loss (to assess barrier function), capacitance (for stratum corneum hydration) and skin surface pH were measured at each of five different body sites in 14 human volunteers. Individual measurements were obtained every 24 h for 96 h.

RESULTS

Lipid-rich skin areas (e.g. the forehead) were the most vulnerable to barrier disruption by either method. While acetone treatment affected barrier function and decreased stratum corneum hydration, tape stripping similarly altered barrier function but increased capacitance values. Although the effect of barrier disruption on surface pH appeared to vary with location, no significant pattern of variation emerged. Independent of the method used for barrier disruption, the pH normalized within 96 h.

CONCLUSIONS

Skin at different body sites shows distinct patterns of barrier recovery that are likely to be related to structural and physiological differences. Therefore, 'anatomically specific' regimens appear possible and relevant for the treatment of cutaneous disorders. In addition, adequate statistical analyses are essential to detect real differences in barrier recovery parameters.

Testing for irritation with a multifactorial approach: comparison of eight non-invasive measuring techniques on five different irritation types

BACKGROUND

Non-invasive bioengineering methods are widely used in the assessment of irritant skin reactions.

OBJECTIVES

To assess the ability of eight non-invasive measurement techniques to distinguish changes in skin conditions over time, these changes being induced by five different irritants.

METHODS

The following techniques were compared in a multivariate analysis: laser-Doppler perfusion imaging (LDI), laser-Doppler flowmetry (LDF), transepidermal water loss (TEWL), visual scoring (VS), colorimetric measurements (Chromameter CR 200 a* and L* scales), Mexameter Hb scale (Mexa Hb) and capacitance (Corneometer CM 820). Irritants tested were sodium lauryl sulphate 2% (SLS), tape stripping (TS), tretinoin 0.05% (TRET), ultraviolet (UV) exposure to 30 W m(-2) UVB/95 W m(-2) UVA, and dithranol 0.5% (DIT). Measurements were performed at baseline and after 24, 48 and 72 h. The study was conducted on the upper back of 11 healthy volunteers of both sexes aged 27-51 years.

RESULTS

For DIT it was possible to discriminate over time with CR 200 a* and L*, VS, LDI, LDF and Mexa Hb. In SLS discrimination over time was seen with TEWL and LDF. Discrimination in TS was demonstrated for TEWL, VS, CR 200 a*, CM 820, LDF, LDI and Mexa Hb. In TRET discrimination ability was seen for LDI, LDF, Mexa Hb and VS. For UV it was possible to discriminate using VS, TEWL, LDF, LDI and Mexa Hb.

CONCLUSIONS

Different irritation patterns need different measurement modalities in order to give optimal discrimination over time.

Differences in corneocyte surface area in pre- and post-menopausal women. Assessment with the noninvasive videomicroscopic imaging of corneocytes method (VIC) under basal conditions

The differences between pre- and postmenopausal women and men on corneocyte surface area were investigated by a noninvasive exfoliation method. Surface corneocytes were collected with a modified detergent scrub technique. Separated corneocytes were analyzed by videomicroscopy and image analyses (NIH Image 1.59). Additionally transepidermal water loss (TEWL) and stratum corneum hydration, water-holding capacity and moisture accumulation velocity were measured. 21 postmenopausal females without hormonal substitution (age 50.6 years), 33 premenopausal women (age 41.0 years) and 25 men matched for age (age 44.0 years) were included in this study. The smallest corneocyte surface area was seen in premenopausal women (368.0 pixels). For postmenopausal women and the male control population almost equal values could be detected (postmenopausal women 401.1 pixels; men 401.8 pixels). Significant differences were calculated with the ANOVA test (p = 0.0050) and post-hoc analyses (Dunn test); premenopausal vs. postmenopausal women (p < 0.05) and premenopausal women vs. men (p < 0.05), but not postmenopausal women vs. men (p > 0.05). No statistically significant differences could be detected for TEWL, stratum corneum hydration parameters. No correlation could be found between the corneocyte surface area and barrier or hydration parameters. The detected differences support the hypothesis that sexual hormones have an impact on corneocyte surface area, because sex hormone levels are higher in premenopausal women than in non-hormone-substituted postmenopausal women or men.

Generation of free fatty acids from phospholipids regulates stratum corneum acidification and integrity

There is evidence that the "acid mantle" of the stratum corneum is important for both permeability barrier formation and cutaneous antimicrobial defense. The origin of the acidic pH of the stratum corneum remains conjectural, however. Both passive (e.g., eccrine/sebaceous secretions, proteolytic) and active (e.g., proton pumps) mechanisms have been proposed. We assessed here whether the free fatty acid pool, which is derived from phospholipase-mediated hydrolysis of phospholipids during cornification, contributes to stratum corneum acidification and function. Topical applications of two chemically unrelated secretory phospholipase sPLA2 inhibitors, bromphenacylbromide and 1-hexadecyl-3-trifluoroethylglycero-sn-2-phosphomethanol, for 3 d produced an increase in the pH of murine skin surface that was paralleled not only by a permeability barrier abnormality but also altered stratum corneum integrity (number of strippings required to break the barrier) and decreased stratum corneum cohesion (protein weight removed per stripping). Not only stratum corneum pH but also all of the functional abnormalities normalized when either palmitic, stearic, or linoleic acids were coapplied with the inhibitors. Moreover, exposure of intact murine stratum corneum to a neutral pH for as little as 3 h produced comparable abnormalities in stratum corneum integrity and cohesion, and further amplified the inhibitor-induced functional alterations. Furthermore, short-term applications of an acidic pH buffer to inhibitor-treated skin also reversed the abnormalities in stratum corneum integrity and cohesion, despite the ongoing decrease in free fatty acid levels. Finally, the secretory-phospholipase-inhibitor-induced alterations in integrity/cohesion were in accordance with premature dissolution of desmosomes, demonstrated both by electron microscopy and by reduced desmoglein 1 levels in the stratum corneum (shown by immunofluorescence staining and visualized by confocal microscopy). Together, these results demonstrate: (i) the importance of phospholipid-to-free-fatty-acid processing for normal stratum corneum acidification; and (ii) the potentially important role of this pathway not only for barrier homeostasis but also for the dual functions of stratum corneum integrity and cohesion.

Direct comparison of skin physiology in children and adults with bioengineering methods

The aim of the study was to investigate whether the physiologic skin parameters of transepidermal water loss (TEWL), stratum corneum hydration (capacitance and conductance), dynamic stratum corneum hydration parameters (hygroscopicity and water-holding capacity), skin color (a* and L* axes; chromameter), cutaneous blood perfusion [laser Doppler flowmetry (LDF)], and pH value differ between a sample of 44 children [C] (average age 3.5 years) and a directly comparable sample of 44 adults (their parents) [P] (average age 34.6 years). The results can be described as follows: TEWL C: 6.2 g/m2/h, P: 5.4 g/m2/h; stratum corneum hydration, capacitance C: 75.4 AU, P: 76.1 AU; conductance C: 27.1 microS, P: 19.2 microS; hygroscopicity C: 129.0 AU, P: 132.7 AU; water-holding capacity: C: 127.7 AU, P: 127.6 AU; redness (a*) C: 7.31, P: 8.21; lightness (L*) C: 67.63, P: 66.36; LDF (%) C: 24.6, P: 18.7; pH value C: 4.91, P: 5.07. In comparison to the skin of the adult sample we investigated (the parents of the 44 children), the skin of the small child can be characterized in the following way: it has a significantly lower hygroscopicity, a lighter (higher L* values) and less red color (lower a* values), and an increased cutaneous blood perfusion (LDF).

Glycerol accelerates recovery of barrier function in vivo

Two studies were performed to evaluate the influence of glycerol on the recovery of damaged stratum corneum barrier function. Measurements of transepidermal water loss and capacitance were conducted in a 3-day follow-up after tape stripping (study 1) and a 7-day follow-up after a barrier damage due to a repeated washing with sodium lauryl sulphate. In study 1 a faster barrier repair (transepidermal water loss) was monitored in glycerol-treated sites. Significant differences between glycerol open vs. untreated and glycerol occluded vs. untreated were observed at day 3. Stratum corneum hydration showed significantly higher values in the sites treated with glycerol+occlusion, compared with all other sites. In study 2 a faster barrier repair was seen in glycerol-treated sites, with significant differences against untreated and base-treated sites 7 days after the end of the treatment. Stratum corneum hydration showed highest values in the glycerol treated sites after 3 days of treatment. Glycerol creates a stimulus for barrier repair and improves the stratum corneum hydration; stratum corneum hydration is not strictly related to barrier homeostasis and can be optimized by different mechanisms and pathways. The observed effects were based on the modulation of barrier repair and were not biased by the humectant effect of glycerol. As the glycerol-induced recovery of barrier function and stratum corneum hydration were observed even 7 days after the end of treatment, glycerol can be regarded as a barrier stabilizing and moisturizing compound.