Keratin-water-NMF interaction as a three layer model in the human stratum corneum using in vivo confocal Raman microscopy

The secondary and tertiary structure of keratin and natural moisturizing factor (NMF) are of great importance regarding the water regulating functions in the stratum corneum (SC). In this in vivo study, the depth-dependent keratin conformation and its relationship to the hydrogen bonding states of water and its content in the SC, are investigated using confocal Raman microscopy. Based on the obtained depth-profiles for the β-sheet/α-helix ratio, the stability of disulphide bonds, the amount of cysteine forming disulphide bonds, the buried/exposed tyrosine and the folding/unfolding states of keratin, a “three layer model” of the SC, regarding the keratin-water-NMF interaction is proposed. At the uppermost layers (30–0% SC depth), the keratin filaments are highly folded, entailing limited water binding sites, and NMF is mostly responsible for binding water. At the intermediate layers (70–30% SC depth), the keratin filaments are unfolded, have the most water binding sites and are prone to swelling. At the bottom layers (100–80% SC depth), the water binding sites are already occupied with water and cannot swell substantially. The hydrogen bonding states of water molecules can only be explained by considering both, the molecular structure of keratin and the contribution of NMF as a holistic system

Follicular Targeting–A Promising Tool in Selective Dermatotherapy

The penetration of topically applied compounds varies considerably in the different regions of the human body. The presence of hair follicles significantly contributes to this effect by an increase in surface area and a disruption of the epidermal barrier towards the lower parts of the hair follicle. The human hair follicle, hereby, serves not only as a reservoir, but also as a major entry point for topically applied compounds. Topical delivery of active compounds to specific targets within the skin may help reduce side-effects caused by unspecific reactions, and may help develop new strategies in the prevention and treatment of skin diseases. Various drug carrier and drug delivery systems are currently being investigated. The aim of these investigational efforts is to direct topically applied compounds to the different types of hair follicles and, ideally, to specific compartments and cell populations within the hair follicles. Follicular targeting offers opportunities for new developments, not only in hair therapy and in the treatment of hair follicle associated diseases but also in gene therapy and immunotherapy

Methods for optical skin clearing in molecular optical imaging in dermatology

This short review describes recent progress in using optical clearing (OC) technique in skin studies. Optical clear-ing is an efficient tool for enhancing the probing depth and data quality in multiphoton microscopy and Raman spec-troscopy. Here, we discuss the main mechanisms of OC, its safety, advantages, and limitations. The data on the OC effect on the skin water content are presented. It was demonstrated that 70% glycerol and 100% OmnipaqueTM 300 reduce the water content in the skin. Both OC agents (OCAs) significantly affect the strongly bound and weakly bound water. However, OmnipaqueTM 300 causes considerably less skin dehydration than glycerol. In addition, the results of examination of the OC effect on autofluorescence in two-photon excitation and background fluorescence in Raman scattering at different skin depths are presented. It is shown that OmnipaqueTM 300 is a promising OCA due to its ability to reduce background fluo-rescence in the upper skin layers. The possibility of multimodal imaging combining optical methods and OC technique is discussed

Reflectance confocal microscopy for noninvasive examination of nonmelanocytic tumors and virus‐associated skin lesions in organ transplant recipients

Background: Drug-induced immunosuppression is necessary to prevent rejection of the foreign organ in transplanted patients, but neoplastic and virus-associated skin diseases are frequent complications. Reflectance confocal microscopy (RCM) recently emerged as a promising tool for the early diagnosis of skin lesions. Materials and methods: A total of 61 skin lesions, among them 20 basal cell carcinomas, six Bowen's diseases, 23 actinic keratoses, and 12 verrucae, were analyzed. All lesions were clinically evaluated followed by RCM evaluation by two independent dermatologists and histological examination. Results: For the diagnosis of basal cell carcinoma, a sensitivity of 100% by both investigators (INV I + II) and a specificity of 100% by INV I and 80% by INV II were achieved. The sensitivity average rate for RCM features reached by both investigators ranged between 60% and 100%, and the specificity between 55% and 90%. For the diagnosis of actinic keratosis, a concordant sensitivity of 94.4% and a specificity of 80% (INV I) and 60% (INV II) were detected. The sensitivity average rate of specific RCM criteria ranged between 72.3% and 97.2%, whereas specificity ranged between 20% and 90%. Regarding verrucae, RCM confirmed the histological diagnosis with a sensitivity of 85.7% (INV I) and 100% (INV II), while specificity was 100% and 80%, respectively. Conclusion: Reflectance confocal microscopy resulted to be a reliable tool for the noninvasive diagnosis of neoplastic and virus-associated skin changes in organ transplant recipients. Nevertheless, given the frequency and diagnostic complexity of the hyperkeratotic lesions occurring post-transplantation, larger cohorts of patients are required to confirm and consolidate these findings

Wound Healing Process After Thermomechanical Skin Ablation

Background and Objectives: Energy-based devices have been widely applied for skin ablation. A novel ablation technique based on thermomechanical principles (Tixel©) has been recently developed. The aim of this study was to examine the wound-healing process and clinical aspects after thermomechanical skin ablation. Study Design/Materials and Methods: Six female participants were treated with Tixel© on healthy skin of the dorsal side of the right forearm in a single session with a 600 µm protrusion and 12 milliseconds pulse. The treated area was examined with confocal laser scanning microscopy on day 1, 2, 7, and 14 after treatment. Clinical symptoms were evaluated at the same time-points. Results: All patients developed erythema and mild edema on the treated areas, which completely disappeared within 14 days. No post-inflammatory hyperpigmentation or scarring was observed. Thermomechanical skin ablation resulted in the formation of homogeneous micro-ablation zones. Two weeks after ablation, the honeycomb patterns of the epidermis in all examined layers was thoroughly restored. Thus, wound-healing was completed. Conclusions: Wound healing after thermomechanical skin ablation is much faster compared with other fractionated ablation methods. Treatment intervals of 2–4 weeks could be recommended

Influences of Orally Taken Carotenoid-Rich Curly Kale Extract on Collagen I/Elastin Index of the Skin

Two differently designed, spatially resolved reflectance spectroscopy-based scanners and two-photon tomography were used for noninvasive in vivo determination of cutaneous carotenoids, and collagen I/elastin aging index of dermis, respectively, in the skin of 29 healthy female volunteers between 40 and 56 years of age. The volunteers received a supplement in the form of a carotenoid-rich natural curly kale extract containing 1650 µg of carotenoids in total (three capsules of 550 µg), once a day. Measurements were taken before, after 5 months and after 10 months of daily supplementation. The results showed significantly increased values for the cutaneous carotenoids and the collagen I/elastin aging index of dermis 5 and 10 months after the beginning of the study. The obtained results show that a natural carotenoid- rich extract could prevent the aging-related collagen I degradation in the dermis and improve the extracellular matrix

In vivo detection of changes in cutaneous carotenoids after chemotherapy using shifted excitation resonance Raman difference and fluorescence spectroscopy

Background: Various cutaneous toxicities under chemotherapy indicate a local effect of chemotherapy by secretion after systemic application. Here, changes in the fluorescence and Raman spectral properties of the stratum corneum subsequent to intravenous chemotherapy were assessed. Methods: Twenty healthy subjects and 20 cancer patients undergoing chemotherapy were included. Measurement time points in cancer patients were before the first cycle of chemotherapy (Tbase) and immediately after intravenous application of the chemotherapy (T1). Healthy subjects were measured once without any further intervention. Measurements were conducted using an individually manufactured system consisting of a handheld probe and a wavelength-tunable diode laser-based 488 nm SHG light source. Hereby, changes in both skin fluorescence and shifted excitation resonance Raman difference spectroscopy (SERRDS) carotenoid signals were assessed. Results: Healthy subjects showed significantly (P <.001) higher mean concentrations of carotenoids compared to cancer subjects at Tbase. An increase in fluorescence intensity was detected in almost all patients after chemotherapy, especially after doxorubicin infusion. Furthermore, a decrease in the carotenoid concentration in the skin after chemotherapy was found. Conclusion: The SERRDS based noninvasive detection can be used as an indirect quantitative assessment of fluorescent chemotherapeutics. The lower carotenoid SERRDS intensities at Tbase might be due to cancerous diseases and co-medication. © 2020 The Authors. Skin Research and Technology Published by John Wiley & Sons Ltd

assessment of blood capillaries and structural proteins localization

The papillary dermis of human skin is responsible for its biomechanical properties and for supply of epidermis with chemicals. Dermis is mainly composed of structural protein molecules, including collagen and elastin, and contains blood capillaries. Connective tissue diseases, as well as cardiovascular complications have manifestations on the molecular level in the papillary dermis (e.g. alteration of collagen I and III content) and in the capillary structure. In this paper we assessed the molecular structure of internal and external regions of skin capillaries using two-photon fluorescence lifetime imaging (FLIM) of endogenous compounds. It was shown that the capillaries are characterized by a fast fluorescence decay, which is originated from red blood cells and blood plasma. Using the second harmonic generation signal, FLIM segmentation was performed, which provided for spatial localization and fluorescence decay parameters distribution of collagen I and elastin in the dermal papillae. It was demonstrated that the lifetime distribution was different for the inner area of dermal papillae around the capillary loop that was suggested to be due to collagen III. Hence, we propose a generalized approach to two-photon imaging of the papillary dermis components, which extends the capabilities of this technique in skin diagnosis

Laser scanning microscopy for control of skin decontamination efficacy from airborne particulates using highly absorbent textile nanofiber material in combination with PEG‐12 dimethicone

Background The decontamination of the skin is indispensable if airborne particulate contaminants deposit on the skin surface. Skin washing can have adverse effects as by skin rubbing the particles can be transferred deeply into the hair follicles, where they can be entrapped for a period of more than 10 days. Thus, alternative skin decontamination strategies are necessary. Materials and Methods For imaging the contaminants in the skin, sodium fluorescein-labeled soot particles of submicron size (approximate to 600 nm) were visualized using laser scanning microscopy. Results In the present ex vivo pilot study on porcine ear skin, it was shown that sodium fluorescein-labeled soot particles of submicron size (approximate to 600 nm) could be efficiently removed from the skin with highly absorbent textile nanofiber material, whose efficacy could be further increased by spraying the contaminated skin area with the viscous fluid PEG-12 dimethicone before textile application. Conclusion In case of skin contamination with particulates, the contact washing should be avoided due to rubbing particles deeply into the hair follicles, where they can accumulate for a long time and induce negative consequences. Efficient skin decontamination could include pretreatment of skin surface with the viscous fluid PEG-12 dimethicone and subsequent application of highly absorbent textile nanofiber material

In vivo Skin Penetration, Radical Protection, and Structural Changes after Topical Application of a Herbal Oil Cream Compared to Topical Calcipotriol in Mild to Moderate Psoriasis

Background: The chronicity of psoriasis often requires continuous topical treatment. Materials and Methods: Here, the radical protection of a cream containing various herbal oils was evaluated in vivo by electron paramagnetic resonance (EPR) spectroscopy and its skin penetration by Raman microscopy in intact and barrier-disturbed skin. Changes in skin barrier properties were evaluated after 4 weeks of daily topical application using in vivo laser scanning microscopy (LSM) and transepidermal water loss in 26 healthy volunteers. A randomized, controlled, double-blind, three-arm parallel clinical study evaluated the efficacy of the herbal oil cream compared to a 0.05% calcipotriol-containing cream and to a vehicle cream, in 135 patients with mild to moderate plaque psoriasis with the change in Psoriasis Area and Severity Index (PASI) from baseline to week 12 as the primary endpoint. Results: EPR spectroscopy disclosed a significantly higher radical formation in untreated than skin treated with the herbal oil cream (p ≤ 0.05). LSM measurements indicated a protective skin barrier effect in treated compared to untreated skin. In the clinical trial, the topical application of herbal oils showed a significant reduction of the PASI score compared to topical calcipotriol at week 12 (p = 0.016). The mean reduction in PASI was 49% for the herbal oil cream, 38% for calcipotriol, and 55% for the vehicle cream. The percentage of patients, who reached PASI 50 and 75 at any time point, was 55.9% and 29.4% for the herbal oil cream, 47.4% and 15.8% for calcipotriol, and 23 (60.5%) and 13 (34.2%) for the vehicle, respectively (p > 0.05). The vehicle, originally designed as a placebo, contained a main ingredient of the herbal oil cream and therefore showed corresponding results. Conclusion: The herbal oil cream demonstrated effectiveness in the treatment of mild to moderate plaque psoriasis