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 (45×), plasmin (30×), urokinase (7·1×), trypsin‐like kallikreins (5·8×) and chymotrypsin‐like kallikreins (3·9×). 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 assessment of tryptophan fluorescence and confocal microscopy provide information on skin barrier repair dynamics beyond TEWL

The stratum corneum (SC) serves a primary function of skin barrier and understanding the kinetics of SC formation may provide great insight for skin diagnosis and evaluation of therapies. Besides trans‐epidermal water loss (TEWL), few methods have been characterized to assess skin barrier non‐invasively in vivo, particularly for dynamic measurements on the same specimen over time. The objective of this study was to characterize alternative non‐invasive methods to evaluate the dynamic processes involved in the recovery of normal human SC after total removal. TEWL, tryptophan fluorescence and reflectance confocal microscopy (RCM) were used to determine skin barrier function, cell turnover and epidermal morphology over a period of 10 days after total removal of the SC by tape stripping. The results show a biphasic recovery of TEWL over time, which contrasted with a linear increase of 2.3 μm/day in SC thickness. Tryptophan assessment of cell turnover also demonstrated a biphasic pattern attaining a maximum three to four times the levels of the control site 3 days after injury that slowly returned to baseline and displayed great correlation (R² > 0.95) to viable epidermis thickness that also achieved a maximum about 3 days after injury with an approximate increase of 55%. When plotting the change of TEWL versus SC thickness, a single exponential function is observed [Δ‐TEWL = 55 exp (?0.157×)] which contrasts with other proposed models. These methods were able to present rates for SC recovery processes beyond skin barrier (TEWL) that may provide new insights on kinetics of barrier formation for evaluation of skin conditions and treatments.     

Distinct molecular signatures of mild extrinsic and intrinsic atopic dermatitis

Atopic dermatitis (AD) is a common inflammatory skin disease with underlying defects in epidermal function and immune responses. In this study, we used microarray analysis to investigate differences in gene expression in lesional skin from patients with mild extrinsic or intrinsic AD compared to skin from healthy controls and from lesional psoriasis skin. The primary aim was to identify differentially expressed genes involved in skin barrier formation and inflammation, and to compare our results with those reported for patients with moderate and severe AD. In contrast to severe AD, expression of the majority of genes associated with skin barrier formation was unchanged or upregulated in patients with mild AD compared to normal healthy skin. Among these, no significant differences in the expression of filaggrin (FLG) and loricrin at both mRNA and protein level were found in lesional skin from patients with mild AD, despite the presence of heterozygous FLG mutations in the majority of patients with mild extrinsic AD. Several inflammation‐associated genes such as S100A9, MMP12, CXCL10 and CCL18 were highly expressed in lesional skin from patients with mild psoriasis and were also increased in patients with mild extrinsic and intrinsic AD similar to previous reports for severe AD. Interestingly, expression of genes involved in inflammatory responses in intrinsic AD resembled that of psoriasis more than that of extrinsic AD. Overall, differences in expression of inflammation‐associated genes found among patients with mild intrinsic and extrinsic AD correlated with previous findings for patients with severe intrinsic and extrinsic AD.     

Filaggrin loss-of-function mutations are associated with early-onset eczema, eczema severity and transepidermal water loss at 3 months of age

Background Filaggrin loss‐of‐function (FLG) mutations are associated with eczema and skin barrier impairment, but it is unclear whether skin barrier impairment precedes phenotypic eczema in FLG mutation carriers. Objectives To study the association between FLG mutations, skin barrier impairment and clinical eczema at 3 months of age. Methods A total of 88 infants were examined for eczema. Disease severity was determined by the SCORAD eczema severity score. Transepidermal water loss (TEWL) was measured on unaffected forearm skin. Venous blood samples were screened for the four most common FLG mutations found in the U.K. white population (R501X, 2282del4, R2447X and S3247X). Median SCORAD and TEWL measurements in children with and without eczema and FLG mutations were compared. Results Thirty‐three per cent (29/88) of children had clinical eczema. Median SCORAD was 10·6 (range 3·5–31·0). TEWL (g m^?2 h^?1) was higher in children with eczema compared with unaffected infants (median TEWL 14·24 vs. 11·24, P < 0·001). Higher TEWL was associated with more severe disease (r = 0·59, P < 0·001, median TEWL, SCORAD < 15, 13·1 vs. 29·6, SCORAD ≥ 15, P = 0·029). Clinically dry skin was associated with higher TEWL, even in the absence of eczema (median TEWL 17·55 vs. 11·08, P = 0·008). Seventeen per cent (15/88) of children carried at least one FLG mutation. FLG mutation carriers were significantly more likely to have clinically dry skin, even in the absence of eczema [odds ratio (OR) 8·50, 95% confidence interval (CI) 1·09–66·58, P = 0·042]. FLG mutation carriers were also more likely to have eczema by 3 months of age (OR 4·26, 95% CI 1·34–13·57, P = 0·014). FLG mutations were significantly associated with higher median TEWL (all children, FLG‘yes’ 21·59 vs. FLG‘no’ 11·24, P < 0·001), even without clinical eczema (FLG‘yes’ 15·99 vs. FLG‘no’ 10·82, P = 0·01). Conclusions By the age of 3 months, FLG mutations are associated with an eczema phenotype, dry skin and TEWL. The observation that TEWL is elevated in unaffected FLG mutation carriers suggests that skin barrier impairment precedes clinical eczema.     

Molecular interactions of plant oil components with stratum corneum lipids correlate with clinical measures of skin barrier function

Plant‐derived oils consisting of triglycerides and small amounts of free fatty acids (FFAs) are commonly used in skincare regimens. FFAs are known to disrupt skin barrier function. The objective of this study was to mechanistically study the effects of FFAs, triglycerides and their mixtures on skin barrier function. The effects of oleic acid (OA), glyceryl trioleate (GT) and OA/GT mixtures on skin barrier were assessed in vivo through measurement of transepidermal water loss (TEWL) and fluorescein dye penetration before and after a single application. OA's effects on stratum corneum (SC) lipid order in vivo were measured with infrared spectroscopy through application of perdeuterated OA (OA‐d₃₄). Studies of the interaction of OA and GT with skin lipids included imaging the distribution of OA‐d₃₄ and GT ex vivo with IR microspectroscopy and thermodynamic analysis of mixtures in aqueous monolayers. The oil mixtures increased both TEWL and fluorescein penetration 24 h after a single application in an OA dose‐dependent manner, with the highest increase from treatment with pure OA. OA‐d₃₄ penetrated into skin and disordered SC lipids. Furthermore, the ex vivo IR imaging studies showed that OA‐d₃₄ permeated to the dermal/epidermal junction while GT remained in the SC. The monolayer experiments showed preferential interspecies interactions between OA and SC lipids, while the mixing between GT and SC lipids was not thermodynamically preferred. The FFA component of plant oils may disrupt skin barrier function. The affinity between plant oil components and SC lipids likely determines the extent of their penetration and clinically measurable effects on skin barrier functions.     

The importance of free fatty acid chain length for the skin barrier function in atopic eczema patients

An important feature of atopic eczema (AE) is a decreased skin barrier function. The stratum corneum (SC) lipids – comprised of ceramides (CERs), free fatty acids (FFAs) and cholesterol – fulfil a predominant role in the skin barrier function. In this clinical study, the carbon chain length distribution of SC lipids (FFAs and CERs) and their importance for the lipid organization and skin barrier function were examined in AE patients and compared with control subjects. A reduction in FFA chain length and an increase in unsaturated FFAs are observed in non‐lesional and lesional SC of AE patients. The reduction in FFA chain length associates with a reduced CER chain length, suggesting a common synthetic pathway. The lipid chain length reduction correlates with a less dense lipid organization and a decreased skin barrier function. All changes are more pronounced in lesional SC compared with non‐lesional skin. No association was observed between lipid properties and filaggrin mutations, an important predisposing factor for developing AE. The results of this study demonstrate an altered SC lipid composition and signify the importance of these changes (specifically regarding the CER and FFA chain lengths) for the impaired skin barrier function in AE. This provides insights into epidermal lipid metabolism as well as new opportunities for skin barrier repair.     

Skin barrier response to occlusion of healthy and irritated skin: Differences in trans‐epidermal water loss,erythema and stratum corneum lipids

Background. Occlusion of the skin is a risk factor for development of irritant contact dermatitis. Occlusion may, however, have a positive effect on skin healing. No consensus on the effect of occlusion has been reached. Objectives. To investigate skin barrier response to occlusion on intact and damaged skin. Methods. In study A, the response to occlusion (nitrile glove material) for either 8 hr daily for 7 days or for 72 consecutive hours, respectively, was determined and compared with that of non‐occluded skin. In study B, the response to occlusion of for 72 consecutive hours of skin that had been damaged by either sodium lauryl sulfate (SLS) or tape stripping, respectively, was determined and compared with that of to non‐occluded pre‐damaged skin. Skin barrier function was assessed by measurements of trans‐epidermal water loss (TEWL) and erythema. In study A, stratum corneum lipids were analysed. Results. Occlusion of healthy skin did not significantly influence skin barrier function, ceramide profile or the ceramide/cholesterol ratio. Occlusion of the skin after SLS irritation resulted in higher TEWL than in the control (P = 0.049). Occlusion of the skin after tape stripping resulted in lower TEWL than in control skin (P = 0.007). Conclusions. A week of occlusion did not significantly affect healthy skin, but was found to decrease healing of SLS‐damaged skin, and to improve healing of tape‐stripped skin.     

Knock‐down of filaggrin does not affect lipid organization and composition in stratum corneum of reconstructed human skin equivalents

Human skin mainly functions as an effective barrier against unwanted environmental influences. The barrier function strongly relies on the outermost layer of the skin, the stratum corneum (SC), which is composed of corneocytes embedded in an extracellular lipid matrix. The importance of a proper barrier function is shown in various skin disorders such as atopic dermatitis (AD), a complex human skin disorder strongly associated with filaggrin (FLG) null mutations, but their role in barrier function is yet unclear. To study the role of FLG in SC barrier properties in terms of SC lipid organization and lipid composition, we generated an N/TERT‐based 3D‐skin equivalent (NSE) after knock‐down of FLG with shRNA. In these NSEs, we examined epidermal morphogenesis by evaluating the expression of differentiation markers keratin 10, FLG, loricrin and the proliferation marker ki67. Furthermore, the SC was extensively analysed for lipid organization, lipid composition and SC permeability. Our results demonstrate that FLG knock‐down (FLG‐KD) did not affect epidermal morphogenesis, SC lipid organization, lipid composition and SC permeability for a lipophilic compound in NSEs. Therefore, our findings indicate that FLG‐KD alone does not necessarily affect the functionality of a proper barrier function.     

Atopic dermatitis: correlation between non-damaged skin barrier function and disease activity

Background Atopic dermatitis (AD) is a chronic dermatosis, predominant in childhood, characterized by pruritus and eczematous‐type lesions with xerosis as the prominent clinical sign. Objectives To analyze the correlation between biophysical measurements of skin barrier function and other assessment criteria of clinical severity according to Rajka and Langeland’s criteria. Methods Biophysical measurements [transepidermal water loss (TEWL) and corneometry] were obtained from 120 patients with the diagnosis of AD. Serum levels of IgE were also evaluated. Results A significant correlation between corneometry, TEWL, and clinical severity of AD was found. Data showed an inverse correlation between corneometry, TEWL, and AD severity, and a significant difference (P < 0.001) between mean of corneometry and TEWL and AD severity (mild, moderate, and severe). As for IgE levels, corneometry had significant negative correlation, in contrast with TEWL, which showed a significant positive correlation (P < 0.001). Conclusion Biophysical measurements of skin barrier in non‐lesional skin of AD may work as an evaluation factor for AD severity.     

Impact of filaggrin mutations on Raman spectra and biophysical properties of the stratum corneum in mild to moderate atopic dermatitis

Background Atopic dermatitis (AD) is associated with null mutations in the filaggrin (FLG) gene. Objective To assess the impact of FLG null mutations on biophysical properties and the molecular composition of the stratum corneum (SC) in healthy individuals and AD patients. Methods A total of 196 French adults, including 97 with a history of mild to moderate AD, were genotyped for the three major European FLG mutations. Components of the natural moisturizing factor (NMF), lipids and water content in the SC were determined using Raman spectroscopy. In addition, trans‐epidermal water loss, capacitance and pH of the SC were measured. Results Stratum corneum concentrations of total NMF, water, ornithine and urocanic acid (UCA) were significantly lower in AD patients than in healthy controls. Null mutations of FLG were detected in 4% of controls and 10% of AD patients. FLG mutations were associated with increased SC levels of lactate, reduced concentrations of most other NMF components and higher disease severity in AD patients. In AD patients without FLG mutations, the content of NMF constituents decreased with increasing disease severity. The concomittant presence of low concentrations of histidine, alanine and either glycine or pyrrolidone‐5‐carboxylic acid (PCA) in the SC was associated with FLG mutations with 92% specificity. Conclusions Our findings suggest a low prevalence of FLG mutations in mild AD and support an important role for filaggrin in determining the physicochemical parameters of the SC. The combined measurement of several filaggrin breakdown products in the SC may be useful to specifically predict the presence of FLG mutations.     

Topical application of a linoleic acid‐ceramide containing moisturizer exhibit therapeutic and preventive benefits for psoriasis vulgaris: a randomized controlled trial

Psoriasis is a chronic skin inflammatory disorder with frequent relapse. Ceramides and their key enzymes are deficient in the lesions, resulting in impaired epidermal permeability barrier, which correlates with disease severity. We evaluated the efficacy of linoleic acid‐ceramide moisturizer (LA‐Cer) as an adjunctive and preventive therapy for psoriasis vulgaris. 106 patients were randomized into two groups. The control group (C₁) received Mometasone Furoate 0.1% Cream (MF) while the treatment group (T₁) was given 0.1% MF in combination with LA‐Cer moisturizer. Psoriasis Area and Severity Index (PASI), pruritus, capacitance (CAP), and transepidermal water loss (TEWL) of normal skin and lesion were evaluated at Week 0, 2, 4, 8. Subsequently, T₁ patients were randomized for another 1 year. LA‐Cer‐group (T₂) maintained the use of moisturizer while control group (C₂) discontinued. CAPs, TEWLs, PASI were assessed after 1 year. Primary endpoints (PASI‐50 at Week 8) revealed superiority of LA‐Cer‐MF versus MF, less relapse, and rebound in LA‐Cer‐group than control (C₂) at Year 1. There were time‐by‐therapy interaction effect on CAPs, lesional TEWL, and PASI. LA‐Cer‐MF induced higher CAP, an earlier reduction of lesional TEWL and PASI than control (C₁). CAPs, lesional TEWL, and PASI remained stable in LA‐Cer‐group. CAPs, lesional TEWL, and PASI were comparable to the baseline levels in control group (C₂). Topical LA‐Cer moisturizer can alleviate psoriasis, and could be a valuable approach for the treatment and prevention of psoriasis.     

The effect of aqueous cream BP on the skin barrier in volunteers with a previous history of atopic dermatitis

Background The emollient aqueous cream BP is frequently used for the treatment of atopic dermatitis (AD), yet it is associated with a high rate of adverse cutaneous reactions. It contains the harsh anionic surfactant sodium lauryl sulphate, a known negative environmental factor associated with the exacerbation of AD. Objectives To investigate the effect of aqueous cream BP on stratum corneum (SC) integrity and skin barrier function in volunteers with a predisposition to a defective skin barrier. Methods Thirteen volunteers with a previous history of AD (no symptoms for 6 months) applied aqueous cream BP twice daily to the volar side of one forearm for 4 weeks. The other forearm was left untreated as a control. Permeability barrier function and SC integrity were determined before and after treatment by measuring transepidermal water loss (TEWL) in conjunction with tape‐stripping. For comparison, 13 volunteers with current AD were recruited for assessment, without treatment, of SC integrity and skin barrier function at unaffected sites. Results Topical application of aqueous cream BP resulted in significant elevation of baseline TEWL and a concomitant decrease in SC integrity. Measurements made after no treatment in volunteers with current AD, at unaffected sites, suggest that application of aqueous cream BP negatively affects the skin barrier towards the damaged state associated with onset of flares of the disease. Conclusions Aqueous cream BP used as a leave‐on emollient caused severe damage to the skin barrier in volunteers with a previous history of AD. Aqueous cream BP should not be used as a leave‐on emollient in patients with AD.     

Effect of Aqueous Cream BP on human stratum corneum in vivo

Background Aqueous Cream BP is widely prescribed to patients with eczema to relieve skin dryness. The formulation contains sodium lauryl sulphate (SLS), a chemical that is a known skin irritant and a commonly used excipient in personal care and household products. The chronic effects of Aqueous Cream BP application on skin barrier function have not been determined. Objectives To characterize and assess skin barrier function of healthy skin after application of Aqueous Cream BP and to study the physical effects of the formulation on the stratum corneum (SC). Methods The left and right volar forearms of six human volunteers were each separated into treated and control sides. The treated sides of each forearm were subjected to twice daily applications of Aqueous Cream BP for 4 weeks at the end of which concomitant tape stripping and transepidermal water loss (TEWL) measurements were made. The untreated sides of the forearms were not exposed to any products containing SLS during the study period. Results Changes in SC thickness, baseline TEWL and rate of increase in TEWL during tape stripping were observed in skin treated with Aqueous Cream BP. The mean decrease in SC thickness was 1·1 μm (12%) (P = 0·0015) and the mean increase in baseline TEWL was 2·5 g m^?2 h^?1 (20%) (P < 0·0001). Reduced SC thickness and an increase in baseline TEWL, as well as a faster rate of increase in TEWL during tape stripping, were observed in 16 out of 27 treated skin sites. Conclusions The application of Aqueous Cream BP, containing ～1% SLS, reduced the SC thickness of healthy skin and increased its permeability to water loss. These observations call into question the continued use of this emollient on the already compromised barrier of eczematous skin.     

Cold plasma is well‐tolerated and does not disturb skin barrier or reduce skin moisture

Background: Cold plasma, a new treatment principle in dermatology based on ionic discharge delivering reactive molecular species and UV‐light, exhibits strong antimicrobial efficacy in vitro and in vivo. Before implementing plasma as new medical treatment tool, its safety must be proven, as well as assessing skin tolerance and patient acceptance. Patients and Methods: We investigated the plasma effects of three different plasma sources (pulsed, non‐pulsed atmospheric pressure plasma jet (APPJ) and a dielectric barrier discharge (DBD)) on the transepidermal water loss (TEWL) and skin moisture after treating the fingertips of four healthy male volunteers. Results: TEWL values were reduced by pulsed APPJ and DBD by about 20% but increased after non‐pulsed APPJ by 5–20%. TEWL values normalized 30 min after all forms of plasma treatment. Skin moisture was increased immediately and 30 min after treatment with pulsed APPJ but was not affected by non‐pulsed APPJ and DBD. Conclusions: All plasma treatments were well‐tolerated and did not damage the skin barrier nor cause skin dryness. Cold plasma fulfils basic recommendations for safe use on human skin and as future option may serve as the first physical skin antiseptic.     

Increased carbonyl protein level in the stratum corneum of inflammatory skin disorders: A non‐invasive approach

The stratum corneum (SC) is the interface of body and environment, and is continuously exposed to oxidative stress, resulting in carbonyl modification of proteins. We have developed a simple and non‐invasive method to assess carbonyl protein (CP) level in the SC, applied it to various kinds of skin, and revealed a link between the stratum corneum carbonylated protein (SCCP) level and water content in the SC. The purpose of the present study is to examine the SCCP level in inflammatory skin disorders associated with xerosis. Psoriasis vulgaris (PV) and atopic dermatitis (AD) are typical inflammatory skin disorders, of which the stratum corneum shows markedly low water content. SC samples were non‐invasively collected from the lesional and non‐lesional areas of PV and AD by adhesive tape stripping, and their carbonyl groups were determined by reaction with fluorescein‐5‐thiosemicarbazide. The average fluorescence intensity of the SC was calculated as SCCP level. Higher SCCP level was observed in the lesional area of PV as compared with non‐lesional area or healthy control. Lesional area of AD also exhibited higher SCCP level than corresponding non‐lesional area, of which SCCP level was slightly higher than the healthy control. These data suggest the involvement of oxidative modification of the SC protein, at least in part, in generation of xerotic skin in inflammatory skin disorders as well as dry skin in healthy subjects.     

Mode of action of glycolic acid on human stratum corneum: ultrastructural and functional evaluation of the epidermal barrier

Alpha-hydroxy acids (AHA) such as glycolic acid have recently been used extensively in cosmetic and dermatological formulas. In low concentration (2– 5%) glycolic acid is believed to facilitate progressive weakening of cohesion of the intercellular material of the stratum corneum (SC), resulting in uniform exfoliation of its outermost layers (the stratum disjunctum). Since thinning of the SC as well as changes of intercellular lipids could theoretically compromise the barrier functions of the skin, we investigated the mode of AHA action on the SC to determine whether enhanced desquamation compromises the barrier structures of the SC and changes transepidermal water loss (TEWL) values. Electron microscopy of the epidermis biopsied from the volar forearm of human volunteers after 3 weeks of treatment with a 4% glycolic acid formulation twice daily was employed to evaluate 1) epidermal morphology and thickness of the SC, (2) the lamellar body and SC lipid bilayer organization, and (3) desquamative events based on degradation of desmosomes. TEWL values and SC hydration were recorded prior to and at the end of the study. Electron microscopy revealed no ultrastructural changes in the nucleated layers of the epidermis. The lamellar body (LB) secretory system in the stratum granulosum (SG), and intercellular lipid lamellae in the SC in both vehicle- and glycolic acid-treated samples were comparable to normal human SC. Within the SC, enhanced desmosomal breakdown, promoting loss of cohesion and desquamation, was restricted to the stratum disjunctum while desmosomes of the stratum compactum were unaffected. Treated areas displayed histologically, a more compact appearing SC. TEWL values remained unchanged in glycolic acid- and vehicle-treated skin. Our findings indicate that the barrier structures of the SC are not disrupted by glycolic acid formulations at the concentration used. One of the mechanism of action of AHA on the SC seemed to be a „targeted“ desmosomal (corneosomal) action without compromising the barrier structures of the skin. Received: 20 November 1996     

Stratum corneum integrity as a predictor for peristomal skin problems in ostomates

Background Peristomal skin problems are common, most often the result is disruption of the skin barrier and this may account for more than one in three visits to ostomy nurses. Therefore a specific assessment of individual risk factors relating to the skin barrier function would be of great interest. Methods Skin barrier integrity in ostomy patients with peristomal skin problems (PSP) was compared with that of ostomy patients with normal skin (controls) using transepidermal water loss (TEWL). Mechanical barrier disruption was determined by a tape stripping test and chemical barrier disruption [sodium lauryl sulphate (SLS) 0·25%]. Results Patients and controls had a highly significant increase in TEWL value in the peristomal area compared with nonperistomal contralateral abdominal skin (P < 0·0001 for both groups). The skin barrier of normal‐looking contralateral skin of ostomates was found to be borderline impaired in patients with PSP compared with those without. A linear association was seen between the number of tape strips removed and TEWL for both cases and controls. Tape stripping suggested that patients with PSP had less resilient skin (P = 0·002). A significant difference in TEWL value between cases and controls was also seen for the SLS patch test on the dorsal skin (P = 0·02). Conclusion Successive tape stripping, a situation analogous to the normal use of a pouching system, caused a higher degree of barrier damage more rapidly in patients with PSP, indicating an impaired mechanical quality of the barrier. The SLS exposure test suggested a generally increased susceptibility to irritant dermatitis as assessed by TEWL. Our findings suggest tape stripping and SLS testing may have a role as predictive tests to identify patients at risk of PSP.     

Depletion of stratum corneum intercellular lipid lamellae and barrier function abnormalities after long-term topical corticosteroids

The intercellular lipid lamellae of the stratum corneum (SC) is believed to provide the permeability barrier of the epidermis. Previous functional studies have demonstrated an increase in the transepidermal water loss (TEWL) after long-term use of topical corticosteroids (TCS); however, direct morphological confirmation of this barrier abnormality is still lacking. The aim of this study was to determine whether any abnormality could be detected in the structure of the SC intercellular lipid lamellae in patients after long-term TCS. Atrophic skin and untreated normal skin of 10 patients after long-term TCS were examined by transmission electron microscopy using ruthenium tetroxide- fixed tissue for the multilamellar lipid sheets of SC, and oil red O stain for neutral lipids of the SC. Layers of the SC were evaluated by 0·1% methylene blue stain after alkaline expansion, and TEWL was measured by Evaporimeter EPI. The TCS-treated atrophic skin had fewer layers of horny cells, mean 9–4 layers, than the normal control skin, 18 layers (P<0·001) and increased TEWL of 21·3g/m² compared with the control skin TEWL of 6·7 g/m²(P<0·01). The mean neutral lipid content of the SC was also significantly lower (P<0·001). Moreover, ultrastructural studies revealed a marked decrease in both the numbers of intercellular lipid lamellae of SC and membrane-coating granules of stratum granulosum in the atrophic skin. These results suggest that the diminution in the SC intercellular lipid lamellae and SC cell layers play an important part in the pathogenesis of barrier dysfunction after long-term use of TCS.     

Patterns of aluminum hydroxychloride deposition onto the skin

Background: Aluminum hydroxychloride (AlCl₃) is an antiperspirant. Aim: To revisit the AlCl₃ deposition in vivo and in vitro on glass slides and stratum corneum (SC) harvested by cyanoacrylate skin surface strippings (CSSS). Methods: Transepidermal water loss (TEWL) was assessed following application of 5% AlCl₃ on the forearms. The AlCl₃‐coated skin, glass slides and CSSS were observed using two ultraviolet light‐emitting CCD cameras in order to record changes in specular reflectance related to AlCl₃ deposition. In addition, the corneoxenometry bioassay was performed in order to predict AlCl₃ irritation. Results: AlCl₃ deposited on glass slides looked as linear threads and rings of similar sizes. AlCl₃ deposits on skin were almost restricted inside the microrelief lines and as annular deposits at their crossings where acrosyringia are opening. After daily AlCl₃ applications, deposits extended on the CSSS plateaus. At rest in absence of sweating, TEWL was decreased following AlCl₃ applications. During physical exercise, the TEWL increase was limited on the AlCl₃ areas. CSSS appeared unreactive to AlCl₃ at the corneoxenometry bioassay. Conclusion: The similar aspect of AlCl₃ deposits on human SC and on glass slides suggested a physical property of AlCl₃. Repetitive applications of AlCl₃ increased both the deposit area and the barrier function.     

Filaggrin mutations are associated with recurrent skin infection in Singaporean Chinese patients with atopic dermatitis

Background Loss‐of‐function (null) mutations within the filaggrin (FLG) gene are a strong risk factor for atopic dermatitis (AD). We hypothesized that the absence or reduction of the filaggrin protein could compromise skin barrier and increase patients’ susceptibility to recurrent skin infection. Objectives To investigate the association between FLG‐null mutations and the risk of recurrent skin infection among a series of patients with AD in Singapore. Methods This study included 228 Singaporean Chinese patients with AD with at least 1 year of follow‐up at the time of recruitment between January 2008 and December 2009 at the National Skin Centre in Singapore. Each patient had their medical records reviewed for history of skin infection in the preceding year and was genotyped for 22 FLG‐null mutations. Results Compared with those without the FLG‐null mutations, patients with AD who had FLG mutation(s) had approximately a seven times increased risk of more than four episodes of skin infection requiring antibiotics in the past year (odds ratio 6·74; 95% confidence interval 2·29–19·79). This risk was much greater in those with mild or moderate disease, and was present in both users and nonusers of oral steroids. Conclusion This study highlights a novel association between FLG‐null mutations and an increased susceptibility to recurrent bacterial skin infection among patients with AD.