Stratum Corneum Hydration Level Research Articles

The Effects of Auricular Acupressure on Pruritus, Skin Dryness, and Depression in Hemodialysis Patients

Purpose: This study investigated the effects of auricular acupressure therapy on pruritus, skin dryness, and depression in hemodialysis patients.Methods: This was a randomized control group pre-post experimental study. Fifty-four patients undergoing maintenance hemodialysis at a single center voluntarily participated in the study. Twenty-seven participants were randomly assigned to the experimental group, to whom auricular acupressure was applied to five designated acupoints (shenmen, heart, kidney, lung, and occiput) for 5 weeks. The control group (n=27) received no intervention for the first 5 weeks, and the auricular acupressure intervention was administered due to ethical considerations after 5 weeks. Pruritus, pruritus-related sleep disturbance, and depression were scored accordingly. Skin dryness was assessed by measuring transepidermal water loss (TEWL) and stratum corneum hydration (SCH) levels.Results: Auricular acupressure therapy significantly reduced pruritus (z=-3.97, <i>p</i><.001) and pruritus-related sleep disturbance (z=-2.97, <i>p</i>=.003) in the experimental group. TEWL showed a significant reduction in the arm (z=-2.23, <i>p</i>=.026) and body (z=-1.97, <i>p</i>=.049) but not in the leg. There were no differences in SCH levels and depression (z=-0.35, <i>p</i>=.721).Conclusion: Auricular acupressure therapy effectively alleviated pruritus and skin dryness. This study confirmed the safety and effectiveness of auricular acupressure therapy as a viable intervention for pruritus in hemodialysis patients.

Improvement in Cutaneous Conditions Can Benefit Some Health Conditions in the Elderly.

As we are aging, a number of cutaneous and extracutaneous disorders will be developed. Although the pathogenesis of these aging-associated disorders is not clear yet, abnormalities in the skin are linked to some aging-associated disorders at least to some extent. Inflammatory dermatoses such as psoriasis and atopic dermatitis predispose to the development of cardiovascular diseases, obesity and type 2 diabetes. In addition, both chronologically aged skin and individuals with some aging-associated systemic conditions display altered epidermal function, such as reduced stratum corneum hydration levels, which can provoke cutaneous inflammation. Because aged skin exhibits higher expression levels of inflammatory cytokines, which play a pathogenic role in a variety of aging-associated health condition, the association of the skin with some aging-associated disorders is likely mediated by inflammation. This postulation is supported by the evidence that improvement in either epidermal function or inflammatory dermatoses can mitigate some aging-associated disorders such as mild cognitive impairment and insulin sensitivity. This perspective discusses the association of the skin with aging-associated disorders and highlights the potential of improvement in cutaneous conditions in the management of some health conditions in the elderly.

Barrier function and ultrastructure characteristics of epidermis in patients with primary cutaneous amyloidosis.

Previous studies on primary cutaneous amyloidosis (PCA) have mainly focused on exploring genetic mutation and components of amyloid in patients with PCA. However, studies on skin barrier function in PCA patients are scarce. Here, we detected the skin barrier function in PCA patients and healthy people by using noninvasive techniques and characterized ultrastructural features of PCA lesions compared with healthy people using transmission electron microscopy (TEM). The expression of proteins related to skin barrier function was examined by immunohistochemistry staining. A total of 191 patients with clinically diagnosed PCA and 168 healthy individuals were enrolled in the study. Our analysis revealed that all investigated lesion areas displayed higher transepidermal water loss and pH values, and lower Sebum levels and stratum corneum hydration levels in PCA patients compared with the same site area in healthy individuals. The TEM results showed that the intercellular spaces between the basal cells were enlarged and the number of hemidesmosomes decreased in PCA lesions. Immunohistochemical staining showed that the expression of integrin α6 and E-cadherin in PCA patients was less than that in healthy controls, while no differences in the expression of loricrin and filaggrin were observed. Our study revealed that individuals with PCA displayed skin barrier dysfunction, which may be related to alterations in epidermal ultrastructure and a decrease in the skin barrier-related protein E-cadherin. However, the molecular mechanisms underlying skin barrier dysfunction in PCA remain to be elucidated.

Trend of changes in epidermal biophysical properties in the Chinese aged 1 month to 17-year old.

Although it is known that epidermal biophysical properties vary with age and gender, the changes in epidermal biophysical properties over the time from baby to adolescence have not been elucidated yet. In the present study, we assessed the trend of changes in transepidermal water loss rates (TEWL), stratum corneum hydration, and skin surface pH in Chinese children. A total of 780 boys and 610 girls, aged 1 month to 17-year old, were enrolled in this study. TEWL and stratum corneum hydration on theforearmandtheshinwere measured with GPSkin Barrier, whereas skin surface pH was measured with portable skin pH meter. Overall, TEWL and stratum corneum hydration levels decreased, whereas skin surface pH increased in children from 1-month old to 17-year old. Significant decline in TEWL was observed on both the forearm and the shin of girls, and the shin of boys aged 13-17-year old. Similarly, marked decline in stratum corneum hydration levels started at ages of 6-12-year old. In contrast, decline in skin surface pH was observed in both girls and boys aged one to 12-month old except on the forearm of boys. Afterward, skin surface pH remained either stable or slight increase except on the shin of boys aged >12 months to 3-year old. These results demonstrate that both TEWL and stratum corneum hydration levels decrease, whereas skin surface pH increases in children aged 1 month to 17-year old. The changes in these biophysical properties vary with age, gender, and body site.

Role of Centella asiatica and ceramide in skin barrier improvement: a double blind clinical trial of Indonesian batik workers.

Batik dyes contain irritant chemicals that increase the risk of skin barrier disruption. This study aims to determine the effect of Centella asiatica and ceramide in transepidermal water loss (TEWL), hydration of the stratum corneum and skin acidity (pH). This was a double blind clinical trial of 30 Indonesian batik workers who suffered from skin dryness, but had no clinical manifestation of contact dermatitis. Subjects were given cream containing C. asiatica or ceramide that formulated and randomly labeled by manufacturer (PT Paragon Technology and Innovation). Both subjects and researchers were blinded to the type of the cream. Cream was applied to the hands and arms twice a day. Biological function of the skin (TEWL, stratum corneum hydration level, and skin acidity) was examined by Cutometer dual MP-580. Baseline was recorded in the first examination, followed by second and third examinations at two and four weeks after treatment. After four weeks treatment, there were significant improvement of C. asiatica application in evaluation of corneometer palmar (p=0.007; CI 95%), corneometer dorsum (p=0.001; CI 95%), and skin acidity dorsum (p=0.017; CI 95%). Ceramide application also gave significant improvement of corneometer palmar (0.038; CI 95%), skin acidity palmar (p=0.001; CI 95%), TEWL dorsum (p=0.023; CI 95%), corneometer dorsum (p=0.002; CI 95%) and skin acidity dorsum (p=0.011; CI 95%). There were no significant differences of C. asiatica effectiveness compared to ceramide in skin barrier improvement. C. asiatica and ceramide can improve skin barrier hydration in order to prevent the risk of contact dermatitis in batik workers.

Either transepidermal water loss rates or stratum corneum hydration levels can predict quality of life in children with atopic dermatitis.

ABSTRACTImportancePatients with atopic dermatitis (AD) display compromised epidermal barrier and suffer from poor quality of life. We hypothesized that quality of life could reflect in the changes in the epidermal barrier function.ObjectiveTo determine whether the epidermal barrier function correlates with the severity of pruritus and/or life quality in children with AD.MethodsA total of 120 children, aged 0–12 years, with moderate AD were enrolled. Children were topically treated with topical corticosteroids (TCS) and an emollient for 2 weeks. The Eczema Area and Severity Index (EASI), visual analogue scale (VAS) for pruritus severity, the Infant’s Dermatitis Quality of Life Index (IDQOL) and the Children’s Dermatology Life Quality Index (CDLQI) were evaluated. Transepidermal water loss (TEWL) rates, stratum corneum (SC) hydration, and skin surface pH were measured. Correlations of epidermal barrier function with pruritus, life quality, and EASI were determined.ResultsFollowing 2‐week treatments, significant improvements were observed in EASI, TEWL, SC hydration, the VAS of pruritus, as well as DQOL (P < 0.001 for all). TEWL positively, while SC hydration negatively correlated with VAS pruritus, DQOL, and EASI (P < 0.001).InterpretationBoth TEWL and SC hydration levels can serve as indicators of the severity of pruritus and quality of life in children with AD.

Modeling Stratum Corneum Swelling for the Optimization of Electrode-Based Skin Hydration Sensors

We present a novel computational model of the human skin designed to investigate dielectric spectroscopy electrodes for stratum corneum hydration monitoring. The multilayer skin model allows for the swelling of the stratum corneum, as well as the variations of the dielectric properties under several hydration levels. According to the results, the stratum corneum thickness variations should not be neglected. For high hydration levels, swelling reduces the skin capacitance in comparison to a fixed stratum corneum thickness model. In addition, different fringing-field electrodes are evaluated in terms of sensitivity to the stratum corneum hydration level. As expected, both conductance and capacitance types of electrodes are influenced by the electrode geometry and dimension. However, the sensitivity of the conductance electrodes is more affected by dimension changes than the capacitance electrode leading to potential design optimization.

The Role of Aloe vera and Centella asiatica to the Improvement of Skin Barrier Function in Indonesian Batik Workers

Background: The batik industry uses dyes and candles, that can disrupt the skin barrier function and may precipitate skin disease. Objective: To determine the role of Aloe vera and Centella asiatica to the improvement of the skin barrier function in Indonesian batik workersMethods: This was a double blind clinical trial of 30 Indonesian batik workers were divided into 2 group and given Aloe vera or Centella asiatica topical randomly was applied twice a day. Transepidermal water loss (TEWL) level, stratum corneum hydration level, and pH level, were examined using Cutometer dual MP-580. Result: Sensitivity (Sn) of new local compared with imported allergen extracts in this study was between 15.38%-84.61%, the highest point was house dust mite extract. Specificity (Sp) was ranged from 81.48%-93.75%, the highest rank was shrimp extract. Compared with IgE results, the Sn of new local and imported house dust mite extracts was good (85.7%; 92.9%). The Sp was good for egg white and cow’s milk new local extracts (86.4%; 84.4%). Conclusion: Aloe vera topical gave significant improvement on palm area of TEWL level (P=0.033; CI 95%), stratum corneum hydration (P=0.000; CI 95%), and pH level (P=0.004; CI 95%); while on dorsal hand area of stratum corneum hydration (P=0.002; CI 95%). Centella asiatica topical gave significant improvement on palm area of stratum corneum hydration (P=0.007; CI 95%); while on dorsal hand area of stratum corneum hydration (P=0.001; CI 95%) and pH level (P=0.17; CI 95%). No significant differences of Aloe vera compared to Centella asiatica in the improvement of skin barrier function.

The association between activity levels and skin moisturising function in adults.

Factors associated with skin moisture retention include age and lifestyle, such as diet and sleep efficiency. However, the impact of exercise habits on skin moisturising function is unclear. We surveyed 86 participants from a Japanese university about their activity levels using the International Physical Activity Questionnaire. We also examined their skin moisturising function, measuring stratum corneum (SC) hydration levels and transepidermal water loss (TEWL). Comparisons of participants’ activity levels, SC hydration, and TEWL, accounting for their gender and age differences, revealed activity levels significantly related to differences in SC hydration levels. Results of multiple comparisons showed increased activity relates to significantly higher SC hydration − the higher the activity levels, the higher the hydration. No difference was found in TEWL. The results suggest exercise habits can prevent dry skin. The findings may be useful for the prevention and treatment of dry skin and promoting the benefits of exercise.

210 Association of epidermal dysfunction and constipation in the elderly

Chronologically aged humans display epidermal dysfunction and high prevalence of constipation. Whether epidermal dysfunction and constipation are associated is unknown. In the present study, we compared the epidermal function in subjects with and without constipation. A total of 577 aged subjects, including 169 males and 408 females, were enrolled in this study. Epidermal biophysical properties, including transdermal water loss (TEWL) rates and stratum corneum hydration, on the flexor forearm, were measured with a Gpskin device, while skin surface pH was measured with a portable pH meter. Our results showed that the stratum corneum hydration levels were 14% lower in subjects with constipation than that without constipation. Moreover, both TEWL rates and skin surface pH were significantly higher in subjects with constipation than that without constipation (p<0.05). Furthermore, permeability barrier recovery was delayed in subjects with constipation in comparison with those without constipation. In contrast, epidermal biophysical properties were comparable in subjects with or without gastric disorders. Interestingly, twice-daily applications of an emollient for 6 months improved epidermal functions, such as stratum corneum hydration, TEWL rates and barrier recovery rates, along with marked reductions in constipation scores. These results suggest that epidermal dysfunction plays a pathogenic role in aging-associated constipation, and improvements in epidermal function can alleviate aging-associated constipation.

197 Altered epidermal function in uninvolved skin supports a pathogenic role of epidermal dysfunction in hand eczema

Although compromised epidermal permeability barrier can contribute to the development of contact dermatitis, whether subjects with hand eczema display abnormalities in epidermal permeability barrier function in their uninvolved skin remains unknown. We assess here epidermal permeability barrier function in subjects with or without hand eczema. All volunteers were recruited from clothing manufacturers in Guangdong, China. Epidermal functions, including transepidermal water loss (TEWL) rates, stratum corneum (SC) hydration and skin surface pH were measured on the flexural surface of the left forearm in all volunteers. These epidermal functions were compared among cohorts of subjects with active hand eczema, a prior history of hand eczema and without any history of hand eczema. A total of 650 questionnaires were collected from 462 females and 188 males. Thirty five subjects (5.4%) currently had hand eczema, while 28 subjects (4.3%) reported a prior history of hand eczema that was inactive currently. Neither a prior personal nor a family history of allergies was associated with the prevalence of hand eczema. But certain occupations and frequent contact with disinfectants were independently associated with the prevalence of hand eczema. Males displayed higher TEWL rates and SC hydration levels than did females. Both skin surface pH and TEWL rates differed significantly among normal controls and subjects with active hand eczema, or a prior history of hand eczema (p<0.05).In conclusion, the uninvolved skin site of subjects with hand eczema exhibits abnormalities in epidermal permeability barrier, supporting a pathogenic role of epidermal dysfunction in hand eczema. Whether subjects with hand eczema in other occupations also display altered epidermal function on uninvolved skin remains to be explored.

Altered Epidermal Permeability Barrier Function in the Uninvolved Skin Supports a Role of Epidermal Dysfunction in the Pathogenesis of Occupational Hand Eczema

Although a compromised epidermal permeability barrier can contribute to the development of contact dermatitis, whether subjects with hand eczema display abnormalities in baseline epidermal permeability barrier function in their uninvolved skin remains unknown. The aim of the present study was to assess epidermal permeability barrier function in subjects with and without hand eczema in clothing manufacturers. Upon approval by the institutional review board, volunteers were recruited from clothing manufacturers in Guangzhou City, China. An 11-item questionnaire was used to collect general data from the volunteers. The diagnoses of self-proclaimed hand eczema were further confirmed by a dermatologist. Epidermal biophysical properties, including transepidermal water loss (TEWL) rates, stratum corneum hydration and skin surface pH were measured on the flexural surface of the left forearm in all volunteers. Epidermal biophysical properties were compared among cohorts of subjects with active hand eczema, a prior history of hand eczema and without any history of hand eczema. A total of 650 questionnaires were collected from 462 females and 188 males, with a mean age of 36.7 ± 0.46 years (range 16–69 years; 95% CI 35.8–37.59). Thirty-five subjects (5.4%) currently had hand eczema, while 28 subjects (4.3%) reported a prior history of hand eczema that was inactive currently. The prevalence of hand eczema did not differ significantly between genders. Neither a prior personal nor a family history of allergies was associated with the prevalence of hand eczema, but certain occupations and frequent contact with disinfectants were independently associated with the prevalence of hand eczema. In the overall cohort, males displayed higher TEWL rates and stratum corneum hydration levels than did females. Both skin surface pH and TEWL rates differed significantly among normal controls and subjects with active hand eczema or a prior history of hand eczema (p < 0.05). In conclusion, the uninvolved skin site of subjects with hand eczema exhibits abnormalities in epidermal perme­ability barrier, supporting a pathogenic role of epidermal dysfunction in hand eczema. Whether subjects with hand eczema in other occupations also display altered epidermal function on uninvolved skin remains to be explored.

Comparison of transepidermal water loss rates in subjects with skin patch test positive vs negative to skin care products

Adverse cutaneous reactions to skin care products (SCP) are becoming increasingly common and may be indicative of defective permeability barrier function. To determine the differences in transepidermal water loss rates (TEWL) between skin patch positive vs negative to skin care products in normal Chinese females. Skin patch test reactions to nine skin care products were assessed in 65 normal Chinese females. Correlations of cutaneous reactions to a panel of nine foreign and domestic SCP with permeability barrier function and stratum corneum (SC) hydration levels were analyzed. Out of 65 subjects, 24 (37%) displayed positive reactions to one or more SCP. However, the occurrence of positive reactions to patch tests did not correlate with either transepidermal water loss rates or SC hydration levels. Though a substantial proportion of normal females display adverse reactions to SCP, this problem cannot be attributed to differences in the qualities of their epidermal permeability barriers, and therefore, these reactions more likely reflect the potential adverse events of the SCP themselves. However, further studies in large cohort of both males and females would be helpful to ascertain whether TEWL levels can predict cutaneous reactions to SCP.

Phytochemical profiling of Avena sativa for phytoantioxidants compounds with their multidirectional non-invasive investigation for anti-pigmenting and facial skin fatiguing effect with a stable emulgel formulation.

Objective: The current research work was initiated to develop stable Emulgel formulation loaded with natural phenolic compounds from Avena sativa that were extracted with various solvents. Method: The free radical scavenging and tyrosinase inhibition activities were performed in order to observe the effects of phenols and flavonoids in emulgel formulation on healthy human volunteers with non-invasive biophysical methods. Results: The results of the study revealed that ethanolic fraction of Avena sativa accommodate high amount of phenolic acids (147.1135 μg/mg dry powder extract) and flavonoids (161.6374 μg/mg dry powder extract) contents with extraordinary high mushroom tyrosinase (63.651 mg/ml)) inhibition and free radical scavenging (85.39 1mg/mL) potential. The developed formulation loaded with phenolic compounds potentially enhance stratum corneum hydration level, increase collagen synthesis, decrease melanin from melanocytes and oil secretions from sebaceous glands at 0.05 level of significance. Conclusion: The presence of useful phytoantioxidants in Avena sativa results in polishing of mechanical features of skin with reduced levels of roughness, scaliness, smoothness, and wrinkles of photo-aged skin. The investigator attributed that anti-aging activity is related to polyphenols present in extract; as the phenolics have the capability to quench reactive oxygen species.

Aging-like physiological changes in the skin of Japanese obese diabetic patients.

Objective:Obesity-associated diabetes causes aging-like changes to skin physiology in animal models, but there have been no clinical studies focusing on human obese diabetic patients. The purpose of this study was to examine the hypothesis that obesity-associated diabetes accelerates aging-like skin changes in Japanese people.Methods:This cross-sectional study enrolled obese-diabetes patients (body mass index ≥ 25 kg m−2) and healthy volunteers (body mass index < 25 kg m−2) as controls. Skin physiology parameters relating to aging (stratum corneum hydration, transepidermal water loss, skin pH, advanced glycation end-products, and dermal collagen density) were evaluated in the two groups.Results:About 37 subjects participated (16 in a control group and 21 in an obese-diabetes group). Age was not significantly different between the groups. The stratum corneum hydration level was significantly lower in the obese-diabetes group. Transepidermal water loss and levels of advanced glycation end-products were significantly higher in this group. Skin pH was not significantly different between groups. Dermal collagen density decreased in the obese-diabetes group.Conclusion:We showed that obese-diabetes patients have decreased stratum corneum hydration, increased transepidermal water loss, higher skin advanced glycation end-products and decreased dermal collagen fiber density compared with normal-weight subjects. These results indicate that the ordinary age-related physiological skin changes seen in the elderly can also occur in obese-diabetes patients aged in their 40s.

Evaluation of a Skin Carcinoma Xenograft Mice Model Supplemented by Chemical Immunosuppression

As we know today, cancer is a disease caused by the uncontrolled growth of a single cell. This development is triggered by mutations, changes in DNA that affect genes in such a way that they increase cancer cells. In the present study, an experimental model based on skin carcinoma xenograft mice was developed and tested. There were studied: the mice weight, the tumor volume, and the evolution of different skin parameters such as transepidermal water loss (TWL), erythema and the hydration level of stratum corneum; mice were divided in four groups: a control group, a group of mice injected with physiological saline solution, another one with immunosuppression, and a group of mice with immunosuppression and xenograft of A375 cells. The results indicate that administration of cyclophosphamide significantly reduced the number of neutrophils and lymphocytes and last two mice groups revealed more pronounced modifications of skin parameters compared to first two groups.

A Novel Cassia fistula (L.)-Based Emulsion Elicits Skin Anti-Aging Benefits in Humans

Cassia fistula, a flowering plant in the family of Caesalpinaceae (Fabaceae), is used in traditional medicine for several indications. Nevertheless, too little is known about its effects on skin conditions and skin aging. Therefore, in this pioneering study, the extracts of oil-in-water macro-emulsions containing 5% C. fistula (L.) crude pods (i.e., phyto-active formulation) were optimally developed and compared to the placebo (i.e., emulsions without the crude extract) for assessment of their effects on human skin aging. Healthy adult male volunteers (n = 13) with a mean age of 31 ± 5.5 years (range: 24–47 years) were enrolled after informed written consent. For 12 consecutive weeks, the subjects were directed to use a patch containing the active emulsion on one of their forearms as well as a patch containing the placebo on their other forearm. Biometrological measurements of skin hydration (SH) and transepidermal water loss (TEWL) were performed on both sides of their respective cheeks at time 0 (baseline values), 2, 4, 6, 8, 10 and 12th weeks. Surface evaluation of living skin (SELS) was taken at time 0 (baseline values) or after 1, 2 and 3 months. Topical application of C. fistula extracts showed a significant (p &lt; 0.05) increase in stratum corneum hydration level, a significant enhancement in its water-holding function as well as in its barrier function. Further, significant (p &lt; 0.005) ameliorations of skin aspects were observed (i.e., less roughness, less dryness, less wrinkles). Taken together, our results strongly suggest therapeutic and esthetic potential of C. fistula pod’s extracts to prevent or delay human skin aging.

Evaluation of biophysical skin parameters and assessment of hair growth in patients with acne treated with isotretinoin.

IntroductionTreatment of the severe forms of acne vulgaris remains a challenge. Isotretinoin is a drug often used in these cases. Retinoids affect the mechanisms that play a role in the pathogenesis of acne, reduce the production of sebum and sizes of the sebaceous glands. However, isotretinoin appears to have undesirable side effects in the skin, mucous membranes and hair.AimThe aim of this study was to assess the effect of acne vulgaris treatment with isotretinoin on biophysical skin parameters: skin sebum and stratum corneum hydration levels, transepidermal water loss values, pH, erythema and hair growth parameters: total number, density and proportion of anagen hair.Material and methodsThe study included thirty patients with acne types: papulopustular, conglobata and phlegmonosa. Patients were treated with isotretinoin at a dose of 0.5–1.0 mg/kg/day for a period of 4–7 months. The measurements of skin biophysical parameters were performed before and after the treatment using Sebumeter SM815, Corneometer CM825, Tewameter TM300, MX Mexameter MX18 and Skin-pH-Meter PH908. Hair growth parameters were evaluated with FotoFinder Dermoscope using the TrichoScan Professional V3.0.8.76 software.ResultsThe results of biophysical skin parameter measurements after the treatment showed a reduction in the severity of seborrhea. However, the skin was dry, which confirmed a lowered degree of stratum corneum hydration and an increase in transepidermal water loss values. Moreover, severity of erythema, an increase in pH value, and variations in selected hair growth parameters: decrease in total count, density and proportion of anagen hair were demonstrated.ConclusionsThe reduction in the skin sebum levels was observed after the treatment. There was dryness of the skin, which was confirmed by biophysical skin parameter measurements. Changes in the hair growth parameters showed telogen effluvium hair loss.

Barreira cutânea na dermatite atópica

O estudo da barreira cutânea e de suas propriedades ganhou impulso a partir da década de 60, com estudos que apontaram sua resistência de forma isolada e suas propriedades com relação à permeação cutânea. Paralelamente, a descrição dos corpos de Odland auxiliou a compreensão da manutenção da estabilidade da camada córnea. O modelo brick &amp; mortar, em que os corneócitos são os tijolos e o cimento são os lipídeos intercelulares, é o mais aceito, até o momento. Atualmente, há evidências consistentes de que o estrato córneo é uma estrutura metabolicamente ativa e exerce funções adaptativas. A barreira cutânea também tem um papel na resposta inflamatória, com ativação de melanócitos, angiogênese e fibroplasia, cuja intensidade depende, basicamente, da intensidade da agressão. As anormalidades da barreira cutânea da dermatite atópica são clinicamente observáveis pela presença de pele seca, achado muito frequente e significativo, que constitui parâmetro iagnóstico e de acompanhamento. O grau de hidratação da camada córnea, assim como a perda de água transepidérmica (transepidermal water loss - TEWL), estão relacionados com o grau de dano à barreira, constituindo parâmetros biofísicos que permitem acompanhar os pacientes de maneira não invasiva e com maior grau de sensibilidade.

Stratum corneum keratin structure, function and formation – a comprehensive review

A comprehensive review on stratum corneum keratin organization, largely based on the recently published cubic rod-packing and membrane templating model [J. Invest. Dermatol., 123, 2004, 715], is presented. Keratin is the major non-aqueous component (wt/wt) of stratum corneum. As 90-100% of the stratum corneum water is thought to be located intracellularly one may presume that keratin also is a major factor (together with filaggrin-derived free amino acids) determining stratum corneum hydration level and water holding capacity. This water holding capacity depends in turn on the structural organization of the corneocyte keratin intermediate filament network. The cubic rod-packing model for the structure and function of the stratum corneum cell matrix postulates that corneocyte keratin filaments are arranged according to a cubic-like rod-packing symmetry. It is in accordance with the cryo-electron density pattern of the native corneocyte keratin matrix and could account for the swelling behaviour and the mechanical properties of mammalian stratum corneum. The membrane templating model for keratin dynamics and for the formation of the stratum corneum cell matrix postulates the presence in viable epidermal cellular space of a highly dynamic small lattice parameter (<30 nm) membrane structure with cubic-like symmetry, to which keratin is associated. It further proposes that membrane templating, rather than spontaneous self-assembly, is responsible for keratin intermediate filament formation and dynamics. It is in accordance with the cryo-electron density patterns of the native keratinocyte cytoplasmic space and could account for the characteristic features of the keratin network formation process, the dynamic properties of keratin intermediate filaments, the close lipid association of keratin, the insolubility in non-denaturating buffers and pronounced polymorphism of keratin assembled in vitro, and the measured reduction in cell-volume and hydration level between stratum granulosum and stratum corneum.