Stratum corneum free amino acids following barrier perturbation and repair
ABSTRACT Modulation of the skin environment after stratum corneum (SC) perturbation has profound effects on the rate and effectiveness of barrier repair. Intermediate water exposure, e.g. moderate relative humidity, may provide the optimum water gradient for SC repair. More rapid recovery with semipermeable (SP) films in vivo was associated with increased hydration measured as moisture accumulation rate. We hypothesized that (i) damaged SC recovering under the high water exposure of full occlusion (FO) would have lower free amino acids (FAA) than sites with low hydration (no occlusion, NO) and semi-occlusion (SP, semipermeable film, intermediate hydration) and (ii) SC under semi-occlusion would have higher FAA than with low hydration. Volar forearm sites in 15 healthy adults were perturbed via cellophane tape stripping and treated with SP, FO and NO for five days. Barrier recovery rate, hydration, dryness and erythema were determined. Serial SC samples (n=15) were collected on day 5 and FAA quantified using reverse-phase HPLC and fluorescence detection. The cumulative protein removed was higher for SP than the control, NO and FO. FAA as total, individual amino acids and citrulline were consistently higher in the control than the three damaged sites. Generally, FAA was higher in NO than FO. Citrulline was higher for NO than SP and FO over the sampled SC. Levels were higher for SP than FO in certain, but not all of the FAAs. FAA was inversely correlated to barrier integrity. Skin hydration was relatively constant at the external microenvironment of the SP site, whereas the NO and FO had a reduction, i.e. a gradient, over the time. Overall, barrier recovery under conditions of a decreasing hydration gradient produced SC with higher levels of FAA than did conditions of full occlusion.
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ABSTRACT: Silver nanoparticles (AgNPs) are increasingly applied to a wide range of materials for biomedical use. These enable a close contact with human skin, thanks to the large release of silver ions that is responsible for a broad spectrum of antimicrobial activity. Silver can permeate the skin; however, there are no data available on silver permeation through skin grafts commonly used in burns recovery. The aim of our study was to evaluate silver penetration using fresh, cryopreserved, and glycerolized human skin grafts after exposure to a suspension of AgNPs in synthetic sweat using a Franz diffusion cell apparatus for 24 h. Silver permeation profiles revealed a significantly higher permeation through glycerolized skin compared with both fresh and cryopreserved skin: 24-h silver flux penetration was 0.2 ng cm−2 h−1 (lag time: 8.2 h) for fresh skin, 0.3 ng cm−2 h−1 (lag time: 10.9 h) for cryopreserved skin, and 3.8 ng cm−2 h−1 (lag time: 6.3 h) for glycerolized skin. Permeation through glycerolized skin is significantly higher compared to both fresh and cryopreserved skin. This result can generate relevant clinical implications for burns treatment with products containing AgNPs.Burns: journal of the International Society for Burn Injuries 11/2014; 40(7). DOI:10.1016/j.burns.2014.02.003 · 1.84 Impact Factor
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ABSTRACT: The levels of natural moisturizing factors in the skin can be used as a biomarker of hydration, for studying the effect of skin irritants, or as a biomarker of loss-of-function mutations in the filaggrin gene which are the main risk factor for atopic dermatitis. In this study the chromatographic performance and recovery of natural moisturizing factors and proteins from the skin were investigated using different extraction solvents and adhesive tapes. The uppermost layer of the skin stratum corneum, collected by using commercially available D-squame and corneofix adhesive tapes, was extracted by ammonia or potassium hydroxide. Protein levels used to correct for a variable stratum corneum amount on a tape were assessed by measuring optical density of a tape or indirectly by measuring proteins by a spectrophotometric assay. The measured natural moisturizing factors, pyrrolidone-5-carboxylic acid, histidine, tyrosine, trans-urocanic acid, and cis-urocanic acid were determined by ion pair reverse phase HPLC. Sample preparation and chromatographic performance were favorable when ammonia was used as an extraction solvent. Extraction of the natural moisturizing factors with ammonia avoids a time consuming neutralization step as required with extraction procedures using strong base or acid. The only drawback of the ammonia method is incomplete extraction of proteins from the tapes; however this can be avoided by measuring the optical density of stratum corneum-loaded tapes. The sensitivity of the method was sufficiently high to quantify the analytes even in homozygous filaggrin gene carriers. Reduced natural moisturizing factors levels found in the individuals with filaggrin gene mutation or after exposure to a skin irritant sodium lauryl sulfate were consistent with the previously reported studies.Analytical Letters 09/2013; 46(14). DOI:10.1080/00032719.2013.789881 · 0.98 Impact Factor
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ABSTRACT: Natural moisturizing factor (NMF) serves as the primary humectant of the stratum corneum (SC), principally comprised of hygroscopic amino acids and derivatives that absorb moisture. Barrier disruption has been shown to differentially affect the levels of specific NMF components, though the kinetics of NMF component restoration following disruption has not been examined. Here we investigated the impact of barrier disruption caused by surfactant exposure on a subset of NMF components immediately following exposure and out to 10 days post-exposure. Volunteers wore patches containing either 1% w/v sodium lauryl sulfate (SLS) or distilled water on their forearms for 24 h. Measurements of transepidermal water loss, erythema, SC water content, and a subset of SC NMF and lipid components were obtained at both sites before treatment, the day of patch removal, and 1, 2, 3, 6, and 10 days following treatment. Most measured NMF components decreased in response to SLS exposure. Exceptions were increases in lactate, ornithine, and urea, and no difference in proline levels. In the days following exposure, reduced levels of several NMF components continued at the SLS site; however, all measured NMF components demonstrated equivalence to the vehicle control within 10 days. Histidine pH 7, lactate, ornithine, and urea were the first to achieve levels equivalent to the vehicle control site, normalizing within 1 day after patch removal. Results imply that NMF components derived from sweat and urea cycling are least impacted by SLS exposure while NMF components derived from degradation of filaggrin and/or other S-100 proteins are most impacted. This implies the restoration of the processes responsible for S-100 protein processing into free amino acids take several days to return to normal. Further examination of the enzymes involved in S-100 protein processing following barrier disruption would provide insight into the pathway(s) for NMF restoration during SC recovery. This article is protected by copyright. All rights reserved.International journal of cosmetic science 10/2013; DOI:10.1111/ics.12101 · 1.45 Impact Factor