Stratum Corneum Of Human Skin Research Articles

Construction of Triboelectric Series and Chirality Detection of Amino Acids Using Triboelectric Nanogenerator.

Triboelectrification necessitates a frictional interaction between two materials, and their contact electrification is characteristically based on the polarity variance in the triboelectric series. Utilizing this fundamental advantage of the triboelectric phenomenon, different materials can be identified according to their contact electrification capability. Herein, an in-depth analysis of the amino acids present in the stratum corneum of human skin is performed and these are quantified regarding triboelectric polarization. The principal focus of this study lies in analyzing and identifying the amino acids present in copious amounts in the stratum corneum to explain their positive behavior during the contact electrification process. Thus, an augmented triboelectric series of amino acids with quantified triboelectric charging polarity by scrutinizing the transfer charge, work function, and atomic percentage is presented. Furthermore, the chirality of aspartic acid as it is most susceptible to racemization with clear consequences on the human skin is detected. The study is expected to accelerate research exploiting triboelectrification and provide valuable information on the surface properties and biological activities of these important biomolecules.

Investigating the Effectiveness of Exopolysaccharide-Producing Lactic Acid Bacteria in Biosorbing Lead (II), Attaching to Caco-2 Cells, and Provoking Antiinflammatory Responses

Lead is a common toxic heavy metal with harmful effects on the human body and is widely used in several industries. It can contaminate the environment by air and water emissions and can enter the human body through the respiratory tract, ingestion, or skin contact. Lead is considered as a persistent environmental pollutant, with a half-life of 30 days in the blood, and exists in the skeletal system for decades and causes damage to other systems. Biosorption is receiving increasing attention. Due to its high efficiency and economic value in removing heavy metals from the environment, a variety of biosorption methods can be used for the removal of heavy metals. Lactic acid bacteria (LAB) strains were capable of attaching to both human skin stratum corneum HaCaT cells and human rectal cancer Caco-2 cells. NBM-04-10-001 and NBM-01-07-003 significantly reduced the secretion of IL-6 and IL-8 after coculture with HaCaT cells. In the immune response of RAW264.7 mouse macrophages, high bacterial counts reduced the concentrations of IL-6 and TNF-α in a dose-dependent manner. The results of animal experiments revealed that feeding lead solution exerted no effect on the animal’s food intake, and feeding PURE LAC NBM11 powder could effectively remove lead content in the blood. The group fed with PURE LAC NBM11 powder showed significantly less damage and lesions to liver cells. The LAB powder developed in this study has the potential to bind metals, preventing them from entering the body and protecting the host. LAB can be an ideal strain for future bioadsorption chelators.

Real-Time Infrared Spectroscopic Measurement of Natural Moisturizing Factor

Real-Time Infrared Spectroscopic Measurement of Natural Moisturizing Factor

Low-flux electron diffraction study on body site dependence of stratum corneum structures in human skin

For analysis of the structure of human skin stratum corneum (SC), we introduced low-flux electron diffraction (ED) and developed a new statistical analysis method for obtained ED intensity profiles. By use of this method we compared the differences in the intercellular lipid organization on the SC corneocytes collected at human forehead, cheek, and forearm by the grid-stripping method. As a result, we found a significant regional difference in the distribution of lipid hydrocarbon chain packing domains in the SC; the ring-type ED pattern with orthorhombic symmetry was more often observed in the forearm SC than in the forehead and cheek SCs. We also found that the dependence of the background electron diffraction intensity on the modulus of the scattering vector differed significantly among them. The present method for the analysis of a large number of ED patterns of noninvasively obtained SC samples could be a powerful tool to scrutinize the structural difference between the SCs under various experimental conditions.

Evaluation of Constrained and Restrained Molecular Dynamics Simulation Methods for Predicting Skin Lipid Permeability.

Recently, molecular dynamics (MD) simulations have been utilized to investigate the barrier properties of human skin stratum corneum (SC) lipid bilayers. Different MD methods and force fields have been utilized, with predicted permeabilities varying by few orders of magnitude. In this work, we compare constrained MD simulations with restrained MD simulations to obtain the potential of the mean force and the diffusion coefficient profile for the case of a water molecule permeating across an SC lipid bilayer. Corresponding permeabilities of the simulated lipid bilayer are calculated via the inhomogeneous solubility diffusion model. Results show that both methods perform similarly, but restrained MD simulations have proven to be the more robust approach for predicting the potential of the mean force profile. Critical to both methods are the sampling of the whole trans-bilayer axis and the following symmetrization process. Re-analysis of the previously reported free energy profiles showed that some of the discrepancies in the reported permeability values is due to misquotation of units, while some are due to the inaccurately obtained potential of the mean force. By using the existing microscopic geometrical models via the intercellular lipid pathway, the permeation through the whole SC is predicted from the MD simulation results, and the predicted barrier properties have been compared to experimental data from the literature with good agreement.

Methodological Considerations for Lipid and Polar Component Analyses in Human Skin Stratum Corneum.

Collection of skin very top layer, called stratum corneum, by tape stripping and the analysis of stratum corneum components by mass spectrometry provides multiple advantages for clinical studies that aim to understand the origins of allergic skin diseases and food allergy. However, such a methodology has multiple challenges on the way of complex stratum corneum analysis when molecules of different polarity are needed to be analyzed from minimal amount of skin tape strips. This review provides an overview of current knowledge about lipid and polar molecules in the skin, discusses challenging aspects of sample processing when dealing with skin tape strips, and provides some guidance towards approaches that generate complex, quantitative, normalized to total sample protein data that fit best the purpose of analysis of stratum corneum components for the purpose of clinical trials.

Analysis of sweating by optical coherence tomography in patients with palmoplantar hyperhidrosis.

Optical coherence tomography (OCT) is a high-resolution tomographic imaging technique that uses optical interference. OCT has enabled the non-invasive three-dimensional analysis of individual acrosyringia in the stratum corneum in human skin. However, no report on the measurement of sweating by OCT using clinical data from humans has been published to date. Twenty patients with hyperhidrosis and twenty healthy subjects were included in this study. Imaging of acrosyringia in the stratum corneum using OCT and measurement of the sweat rate using the ventilated capsule method were performed simultaneously. The hand grip exercise of the right hand was used as a load to induce sweating, and the left fingertip was measured before and after the exercise load. Five acrosyringia were extracted from each OCT image, and their volumes were calculated. The mean volume of each acrosyringium was divided by the thickness of the stratum corneum to calculate the mean cross-sectional area of the acrosyringium. Furthermore, the number of sweat droplets on the skin surface was measured. The mean cross-sectional area of acrosyringia after the load increased both in patients with hyperhidrosis and in healthy subjects (P<0.001). The mean cross-sectional area of acrosyringia of patients with hyperhidrosis was larger than that of healthy subjects (P<0.001). The mean cross-sectional area of acrosyringia and the sweat rate showed a positive correlation before and after the load (r=0.88 to 0.91). The number of droplets also increased after the load (P<0.001), and the number of droplets in patients with hyperhidrosis was higher than in healthy subjects (P<0.001). Our study has shown that acrosyringia in the stratum corneum increase in proportion to the sweat rate. OCT is a rigorous and valuable method that can measure and quantify sweating in the body without being an invasive procedure.

Microbeam X-ray diffraction study of lipid structure in stratum corneum of human skin.

Human skin, not previously frozen, was studied by small-angle X-ray diffraction. The samples were folded so that a 6μm X-ray beam passed through the top layer of skin, stratum corneum. Diffraction patterns recorded with this method consisted of peaks at about q = 0.5, 1.0 and 1.4 nm-1 in the direction perpendicular to the skin surface more clearly than in previous studies. These peaks are interpreted to arise from lipids between corneocytes. A simple unit of a linear electron density profile with three minima was used to account for the observed intensity profiles. Combinations of calculated diffraction from models with one, two and three units accounted for the major part of the observed diffraction pattern, showing the diversity in the structure of the intercellular lipids.

Human Keratinocytes Synthesize Ultra Long‐Chain Sphingoid Bases (Up To C28) That Are Abundant in Skin Stratum Corneum

Skin sphingolipids are unique and fulfill the important task of forming a hydrophobic barrier to limit water loss from the body but also to protect from allergen, bacterial and viral penetration through the skin. Skin sphingolipids are highly diverse in their combination of fatty acids and sphingoid bases, the presence of highly hydrophobic ω‐esterified ceramides (EOS‐CER), and the abundance of ultra long‐chain fatty acids (ULCFA, up to C36) within ceramide molecules. The chain length of sphingoid bases in ceramides is commonly attributed to C18 molecules but there are only a few reports demonstrating the presence of C20‐ and C22‐sphingoid bases in skin ceramides. As free sphingoid bases and ceramides are metabolically connected, it is assumed that similar to other tissues, C18‐sphingoid bases represent the majority of sphingoid bases within the total pool of free and ceramide‐linked molecules in the skin.Our sphingolipidomic work during the study of the mechanisms leading to the impairment of skin barrier function has revealed that ceramides with C18‐, C20‐, and C22‐ sphingoid bases are almost equally represented in human skin stratum corneum. Surprisingly, we found that free sphingoid bases in stratum corneum are highly abundant and composed primarily of ultra long‐chain (C24‐ and C26‐) dihydrosphingosines. This finding prompted us to investigate in details the ability of skin keratinocytes to synthesize ultra long‐chain length sphingoid bases. Using undifferentiated and Ca2+‐differentiated primary human keratinocytes, [U‐13C,15N]‐serine, and stable isotope pulse‐labeling approach in vitro, we have confirmed that all ceramides and free sphingoid base molecules do incorporate the labeled serine into their structure. Next, we explored the ability of serine palmitoyltransferase (SPT), the enzyme that initiates sphingolipid biosynthesis, to synthesize ultra long‐chain sphingoid bases in vitro. By comparing the activity of SPT in total cell lysates prepared from undifferentiated and Ca2+‐differentiated human keratinocytes, 16:0–24:0‐Coenzyme A molecules and [U‐13C,15N]‐serine, we confirmed the ability of SPT expressed in human keratinocytes to produce, albeit at low capacity, C24‐ and C26‐3‐keto‐dihydrosphingosines. As keratinocytes and skin stratum corneum do not have measurable amounts of ceramides with C24‐C26‐dihydrosphingosines or C24‐C26‐sphingosines, we conclude that keratinocyte ceramide synthases are unable to utilize dihydrosphingosines with carbon chain length more than C22, thus providing a foundation for the accumulation of C24‐C26‐dihydrosphingosine in human stratum corneum. The question of the possible special biological function of long‐chain dihydrosphingosines in human skin is currently under investigation.

Neutrophil Recruitment to Noninvasive MRSA at the Stratum Corneum of Human Skin Mediates Transient Colonization

Staphylococcus aureus is a leading cause of skin and soft issue infection, but paradoxically, it also transiently, and often harmlessly, colonizes human skin. An obstacle to understanding this contradiction has been a shortage of invivo models reproducing the unique structure and immunology of human skin. In this work, we developed a humanized model to study how healthy adult human skin responds to colonizing methicillin-resistant S.aureus (MRSA). We demonstrate the importance of the outer stratum corneum as the major site of bacterial colonization and how noninvasive MRSA adhesion to corneocytes induces a local inflammatory response in underlying skin layers. This signaling recruits neutrophils to the skin, where they control bacterial numbers, mediating transiency in colonization. This work highlights the spatiotemporal aspects of human skin colonization and demonstrates a subclinical inflammatory response to noninvasive MRSA that allows human skin to regulate the bacterial population at its outer surface.

Simultaneous Measurements of Structure and Water Permeability in an Isolated Human Skin Stratum Corneum Sheet

Stratum corneum (SC), the outermost layer of human skin, acts as an intelligent physicochemical interface between the inside and the outside of our body. To make clear the relationship between structure and physical barrier properties of SC, we developed a method that enables us to simultaneously acquire X-ray diffraction (XD) patterns and transepidermal water loss (TEWL) values using a spread SC sheet isolated from human skin. The synchrotron X-ray was incident on the SC sheet surface at an angle of 45° to avoid interference between the two kinds of measurements. Detailed comparison between XD and TEWL data suggested that the thermal behavior of water permeability is closely related to the thermal expansion of the lattice spacings of the hexagonal phases above 40 °C and to the existence ratio of the orthorhombic phase below 40 °C. Thus, the new method we developed can give useful information on the mechanism of water permeation in SC without ambiguity caused by separate measurements of structure and water permeability with different samples.

Uncovering the clinical impact of kallikrein-related peptidase 5 (KLK5) mRNA expression in the colorectal adenoma-carcinoma sequence.

Background Kallikrein-related peptidases (KLKs) are a subgroup of serine proteases located on chromosome 19q13.3. Most KLKs have been extensively studied as potential biomarkers for several carcinomas and other diseases. KLK5 was originally identified from a keratinocyte library, and its enzyme was purified from the stratum corneum of human skin. KLK5 was shown to be differentially expressed in a variety of endocrine tumors, although it is not as yet examined widely in colorectal cancer (CRC). Methods In this study, we quantitatively assessed the mRNA expression status of KLK5 in 197 colorectal tissues from 133 patients (70 cancerous and their paired normal colonic mucosa for 64 of them, as well as 63 colorectal adenomas) by quantitative real-time PCR (qPCR) using TaqMan probes. Statistical analysis evaluated the results. Results It was shown that KLK5 expression is reduced following the histologically non-cancerous-adenoma sequence (p<0.001), whereas it is increased during the sequence adenoma-carcinoma (p<0.001). Furthermore, KLK5 positive expression is associated with positive nodal status (p=0.022), advanced tumor stage (p=0.038) and high histological grade (p=0.033). Cox univariate analysis revealed that KLK5 positive expression is associated with disease-free survival (DFS) (p=0.028) and overall survival (OS) of patients (p=0.048). Kaplan-Meyer survival models showed that patients with positive KLK5 expression have lower DFS (p=0.009) and OS (p=0.019). Receiver operating characteristic (ROC) analysis demonstrated for first time that KLK5 expression had significant discriminatory values between cancer and adenoma tissues (area under the curve [AUC] 0.77; 95% confidence interval [CI]=0.69-0.85, p=0.03). Conclusions KLK5 mRNA expression may be useful for the differentiation of CRC from colorectal adenoma and represents a potential unfavorable prognostic biomarker for CRC.

Potential of short-wave infrared spectroscopy for quantitative depth profiling of stratum corneum lipids and water in dermatology.

We demonstrate the feasibility of short wave infrared (SWIR) spectroscopy combined with tape stripping for depth profiling of lipids and water in the stratum corneum of human skin. The proposed spectroscopic technique relies on differential detection at three wavelengths of 1720, 1750, and 1770 nm, with varying ratio of the lipid-to-water absorption coefficient and an 'isosbestic point'. Comparison of the data acquired using SWIR spectroscopy with that obtained by a gold standard for non-invasive quantitative molecular-specific skin measurements, namely confocal Raman spectroscopy (CRS), revealed specificity of the proposed modality for water and lipid quantification. At the same time, we provide evidence showing aberrant sensitivity of Corneometer hydration read-outs to the presence of skin surface lipids, and a lack of sensitivity of the Sebumeter when attempting to measure the lipids of the cornified lipid envelope and intracellular lipid layers. We conclude that a spectroscopic SWIR-based spectroscopic method combined with tape stripping has the potential for depth profiling of the stratum corneum water and lipids, due to superior measurement sensitivity and specificity compared to the Corneometer and Sebumeter.

Nano-formulation for topical treatment of precancerous lesions: skin penetration, in vitro, and in vivo toxicological evaluation.

With the aim of improving the topical delivery of the antineoplastic drug 5-fluorouracil (5FU), it was loaded into ultradeformable liposomes composed of soy phosphatidylcholine and sodium cholate (UDL-5FU). The liposome populations had a mean size of 70nm without significant changes in 56days, and the ultradeformable formulations were up to 324-fold more elastic than conventional liposomes. The interaction between 5FU and the liposomal membrane was studied by three methods, and also release profile was obtained. UDL-5FU did penetrate the stratum corneum of human skin. At in vitro experiments, the formulation was more toxic on a human melanoma-derived than on a human keratinocyte-derived cell line. Cells captured liposomes by metabolically active processes. In vivo toxicity experiments were carried out in zebrafish (Danio rerio) larvae by studying the swimming activity, morphological changes, and alterations in the heart rate after incubation. UDL-5FU was more toxic than free 5FU. Therefore, this nano-formulation could be useful for topical application in deep skin precancerous lesions with advantages over current treatments. This is the first work that assessed the induction of apoptosis, skin penetration in a Saarbrücken penetration model, and the toxicological effects in vivo of an ultradeformable 5FU-loaded formulation.

Pitfalls in using fluorescence tagging of nanomaterials: tecto-dendrimers in skin tissue as investigated by Cluster-FLIM.

Targeted topical application promises high drug concentrations in the skin and low systemic adverse effects. To locate drugs and drug-delivery systems like nanocarriers, fluorescent dyes are commonly used as drug surrogates or nanocarrier labels in micrographs of tissue sections. Here, we investigate how labeling degree, concentration of fluorophore, and nanocarrier may affect the interpretation of these micrographs. False-negative penetration results due to inter- and intramolecular quenching effects are likely. Using tecto-dendrimers as an example, we present a detailed analysis of pitfalls in the (semi-)quantitative evaluation of skin nanocarrier penetration. Fluorescence lifetime imaging microscopy (FLIM) allows distinguishing the target fluorescence of dye-tagged nanocarriers from skin autofluorescence, providing a highly sensitive tool for clear-cut localization of the nanocarriers. Cluster-FLIM images reveal that FITC-labeled tecto-dendrimers penetrate the stratum corneum of human skin ex vivo and reconstructed human skin but do not cross the tight junction barrier.

Lipidomic platform for structural identification of skin ceramides with α-hydroxyacyl chains.

Skin ceramides are sphingolipids consisting of sphingoid bases, which are linked to fatty acids via an amide bond. Typical fatty acid acyl chains are composed of α-hydroxy fatty acid (A), esterified ω-hydroxy fatty acid (EO), non-hydroxy fatty acid (N), and ω-hydroxy fatty acid (O). We recently established a lipidomic platform to identify skin ceramides with non-hydroxyacyl chains using tandem mass spectrometry. We expanded our study to establish a lipidomic platform to identify skin ceramides with α-hydroxyacyl chains. Tandem mass spectrometry analysis of A-type ceramides using chip-based direct infusion nanoelectrospray-mass spectrometry showed the characteristic fragmentation pattern of both acyl and sphingoid units, which can be applied for structural identification of ceramides. Based on the tandem mass spectrometry fragmentation patterns of A-type ceramides, comprehensive fragmentation schemes were proposed. Our results may be useful for identifying A-type ceramides in the stratum corneum of human skin.

Sa1974 Long-Term Exposure to Low Concentration of Radioactive Cesium Promotes Azoxymethane-Induced Colon Tumorigenesis in Mice

INTRODUCTION: Colon cancer (CC) presents the third most frequent cause of cancerrelated death inmen and womenworldwide. Currently, available prognostic and/or predictive markers for colon cancer lack specificity and sensitivity. Developing new biomarkers for early detection, accurate diagnosis and therapeutic treatment for CC is of great importance in improving the clinical outcome of the disease. Kallikrein-related peptidases (KLKs) are a subgroup of serine proteases located on chromosome 19q13.3. Most members of the Kallikrein-related peptidase family have been extensively studied as potential biomarkers for several carcinomas and other diseases. KLK5 (HSCTE) was originally identified from a keratinocyte library, and its enzyme was purified from the stratum corneum of human skin. KLK5 has been shown to be differentially expressed in a variety of endocrine tumors, but is not as yet examined in colon cancer. AIM: The aim of this study was to analyse the expression of KLK5 in tissue samples at different stages in the process of colon cancer development. MATERIALS AND METHODS: We assessed the expression status of KLK5 in 90 colon cancer tissues and their paired normal colonic mucosa, as well as in 70 adenomas by real time qPCR using TaqMan probes. RESULTS: It was shown that KLK5 positive expression is associated with patients' nodal status (p=0.022) and with tumor histological grade (p=0.033). Cox univariate analysis revealed that KLK5 positive expression is associated with disease-free survival (p=0.028) and overall survival of patients (p=0.048). KaplanMeyer survival models showed that patients with positive KLK5 have lower disease-free survival (p=0.009) and overall survival (p=0.019). ROC analysis demonstrated that KLK5 expression had significant discriminatory value between cancer and adenoma tissues (AUC 0.77; 95% CI=0.69-0.85, p=0.03). CONCLUSION: The present study suggests that KLK5 mRNA expression shows a discriminatory value between cancerous and adenomatous colonic tissues and that it can predict poor prognosis for colon cancer patients.

Application of single molecule fluorescence microscopy to characterize the penetration of a large amphiphilic molecule in the stratum corneum of human skin.

We report here on the application of laser-based single molecule total internal reflection fluorescence microscopy (TIRFM) to study the penetration of molecules through the skin. Penetration of topically applied drug molecules is often observed to be limited by the size of the respective drug. However, the molecular mechanisms which govern the penetration of molecules through the outermost layer of the skin are still largely unknown. As a model compound we have chosen a larger amphiphilic molecule (fluorescent dye ATTO-Oxa12) with a molecular weight >700 Da that was applied to excised human skin. ATTO-Oxa12 penetrated through the stratum corneum (SC) into the viable epidermis as revealed by TIRFM of cryosections. Single particle tracking of ATTO-Oxa12 within SC sheets obtained by tape stripping allowed us to gain information on the localization as well as the lateral diffusion dynamics of these molecules. ATTO-Oxa12 appeared to be highly confined in the SC lipid region between (intercellular space) or close to the envelope of the corneocytes. Three main distinct confinement sizes of 52 ± 6, 118 ± 4, and 205 ± 5 nm were determined. We conclude that for this amphiphilic model compound several pathways through the skin exist.

Contact and frictional properties of stratum corneum of human skin

Abstract Most skin tribology studies gave attention on the examination of frictional properties of normal and healthy skin surfaces. This study aims to investigate the frictional and mechanical properties of skin under different load and friction conditions after removing the stratum corneum from the designated uninjured forearm tissue by a tape stripping method. The influence of water on friction coefficient was explained by using adhesion model of friction. For quantifying the amount of removed stratum corneum from the skin surfaces, an UV/vis spectrum analysis was used to measure the absorbance and pseudo-absorbance of stratum corneum on the tape. To evaluate the influence of water on friction coefficient, trans-epidermal water loss (TEWL) value of different skin conditions was assessed by water evaporation measurements. Frictional and mechanical properties of the skin surfaces were acquired via a tribometer. Results revealed that the elastic modulus of skin decreased and the friction coefficient of skin increased with the increasing of the amount of removed stratum corneum. Friction force versus normal force was presented to explain the influence of water on friction coefficient and section change phenomenon of friction coefficient under different degrees of tape strips.

Low-flux electron diffraction study for the intercellular lipid organization on a human corneocyte

Human skin stratum corneum (SC) structures were investigated by electron diffraction (ED) with a very low-flux electron beam with the help of high-sensitivity detectors, the imaging plate and the CCD camera. This low-flux electron diffraction (LFED) method made it possible to minimize the unfavorable effect of electron beam damage and to give a reliable diffraction pattern from a small selected area (0.2μm2) on a corneocyte. Dependence of the 2-dimensional ED pattern on the size of the selected area showed that orientational correlation between lipid packing domains can persist over the area much larger than their domain size. The LFED method also allowed us to trace the detailed structural change induced by the electron beam damage. The ED diffraction peak for the lattice constant of about 4.1nm decayed in three steps. The detailed analysis of these three steps suggested that a different type of orthorhombic structure exists interacted with the well-described hexagonal and orthorhombic structures, in the process of decay resulting from electron beam damage.