The environment and skin aging

A Transdermal Prion-Bionics Supermolecule as a RAB3A Antagonist for Enhancing Facial Youthfulness

The mechanism research of skin wrinkles, conducted on volunteers underwent high-intensity desk work and mice subjected to partial sleep deprivation, revealed a significant reduction in dermal thickness associated with the presence of wrinkles. This can be attributed to the activation of facial nerves in a state of hysteria due to an abnormally elevated interaction between SNAP25 and RAB3A proteins involved in the synaptic vesicle cycle (SVC). Facilitated by AI-assisted structural design, a refined peptide called RSIpep is developed to modulate this interaction and normalize SVC. Drawing inspiration from prions, which possess the ability to protect themselves against proteolysis and invade neighboring nerve cells through macropinocytosis, RSIpep is engineered to demonstrate a GSH-responsive reversible self-assembly into a prion-like supermolecule (RSIprion). RSIprion showcases protease resistance, micropinocytosis-dependent cellular internalization, and low adhesion with constituent molecules in the cuticle, thereby endowing it with the transdermic absorption and subsequent biofunction in redressing the frenzied SVC. As a facial mud mask, it effectively reduces periorbital and perinasal wrinkles in the human face. Collectively, RSIprion not only presents a clinical potential as an anti-wrinkle prion-like supermolecule, but also exemplifies a reproducible instance of bionic strategy-guided drug development that bestows transdermal ability upon the pharmaceutical molecule.

Protective effects of the phenolic compounds from mung bean hull against H2O2-induced skin aging through alleviating oxidative injury and autophagy in HaCaT cells and HSF cells

To add value to food waste and seek skin aging suppressor, petroleum ether, ethyl acetate, n-butanol and water phenolic extracts were produced from mung bean hulls subjected to ultrasound-assisted ethanolic extraction. The four extracts all contained protocatechuic acid, isovitexin, vitexin, caffeic acid, 4-coumaric acid, ferulic acid, rutin and chlorogenic acid (revealed by UHPLC-MS/MS). The effects of the four extracts and their main phenolic compounds against H₂O₂-caused cell damage and aging in HaCaT and HSF cells were examined (including cell viability, ROS, MDA, SOD, GSH-px and β-galactosidase levels). The four extracts and the eight phenolic compounds exhibited different protective effects on H₂O₂-treated HaCaT/HSF cells viability, with the ethyl acetate extract among the extracts, and isovitexin and vitexin among the eight compounds, exerting the greatest protection. Therefore, isovitexin and vitexin may be the key oxidative stress and autophagy modulators of mung bean hull, and they inhibit skin aging and damage likely through suppressing Nrf2/keap1/HO-1 related oxidative damage and LC3II/p62/GATA4 related autophagy.

An Oenothera biennis Cell Cultures Extract Endowed with Skin Anti-Ageing Activity Improves Cell Mechanical Properties

Skin aging is a very well-known process setting a gradual worsening of skin mechanical features due to a decline in the production of the extra-cellular matrix machinery and to a concurrent change in the contraction process. To slow this progression, it is crucial to induce the expression of several proteins able to promote elastic fibers formation and tissue repair. Here, the Oenothera biennis cell culture aqueous extract has been investigated from a chemical point of view and then it was tested in vitro, in cell, and in ex vivo experiments as adjuvant in counteracting skin aging. Accordingly, it has been shown that the Oenothera biennis extract was able, by increasing MYLK gene expression, to promote matrix collagen contraction, actin polymerization, and the production of essential ECM proteins.

Fungal melanin as a biocompatible broad-spectrum sunscreen with high antioxidant activity

Melanin is considered a bio-inspired dermo-cosmetic component due to its high UV absorption and antioxidant activity. Among various melanin sources, fungal melanin is a promising candidate for sunscreen because of its sustainability and scalability; however, quantitative assessment of its function has not yet been sufficiently explored. In this study, melanin samples derived from Amorphotheca resinae were prepared, followed by the evaluation of their sunscreen performance, antioxidant activity, and cytotoxicity. Melanin-blended cream was prepared by blending a melanin suspension and a pure cream. The cream showed an in vitro sun protection factor value of 2.5 when the pigment content was 5%. The cream showed a critical wavelength of approximately 388 nm and a UVA/UVB ratio of more than 0.81, satisfying the broad-spectrum sunscreen requirement. Oxygen radical absorbance capacity assays indicated that fungal melanin had antioxidant activity similar to ascorbic acid but higher than reduced glutathione. Fungal melanin had no statistically significant cytotoxicity to human keratinocyte cell lines until 72 h of exposure, even at a concentration of 4 mg mL-1. Consequently, melanin pigment can be used as a biocompatible broad-spectrum sunscreen with high antioxidant activity and as a practical alternative in dermo-cosmetic formulations.

Acer tataricum subsp. ginnala Inhibits Skin Photoaging via Regulating MAPK/AP-1, NF-κB, and TGFβ/Smad Signaling in UVB-Irradiated Human Dermal Fibroblasts

Skin, the organ protecting the human body from external factors, maintains structural and tensile strength by containing many collagen fibrils, particularly type I procollagen. However, oxidative stress by ultraviolet (UV) exposure causes skin photoaging by activating collagen degradation and inhibiting collagen synthesis. Acer tataricum subsp. ginnala extract (AGE) is a herbal medicine with anti-inflammatory and anti-oxidative effects, but there is no report on the protective effect against skin photoaging. Therefore, we conducted research concentrating on the anti-photoaging effect of Acer tataricum subsp. ginnala (AG) in UVB (20 mJ/cm²)-irradiated human dermal fibroblasts (HDF). Then, various concentrations (7.5, 15, 30 µg/mL) of AGE were treated in HDF for 24 h following UVB irradiation. After we performed AGE treatment, the matrix metalloproteinase1 (MMP1) expression was downregulated, and the type I procollagen level was recovered. Then, we investigated the mitogen-activated protein kinases/activator protein 1 (MAPK/AP-1) and nuclear factor-κB (NF-κB) pathway, which induce collagen breakdown by promoting the MMP1 level and pro-inflammatory cytokines. The results indicated that AGE downregulates the expression of the MAPK/AP-1 pathway, leading to MMP1 reduction. AGE inhibits nuclear translocation of NF-κB and inhibitor of nuclear factor-κB (IκB) degradation. Therefore, it downregulates the expression of MMP1 and pro-inflammatory cytokines such as TNF-α, IL-1β, and IL-6 increased by UVB. Besides, the TGFβ/Smad pathway, which is mainly responsible for the collagen synthesis in the skin, was also analyzed. AGE decreases the expression of Smad7 and increases TGFβRII expression and Smad3 phosphorylation. This means that AGE stimulates the TGFβ/Smad pathway that plays a critical role in promoting collagen synthesis. Thus, this study suggests that AGE can be a functional material with anti-photoaging properties.

Measurement of dermal water content by confocal RAMAN spectroscopy to investigate intrinsic aging and photoaging of human skin in vivo

BACKGROUND

In vivo confocal Raman spectroscopy (CRS) revealed a clear correlation of age and dermal water content, indicating increasing water content of the dermis with increasing age. This enhancement of water has been interpreted as an age-dependent depletion, of proteins, mainly of collagen. Chronical sun exposure is known to destroy the collagen network of the skin, which leads to the signs of photoaging as the formation of wrinkles. Noninvasive in vivo measuring techniques for photoaging are limited. Therefore, sensitive techniques to quantify even mild degrees of photoaging in a clinical setting are of high interest. We used CRS to measure the water content in human dermis in vivo, assuming that additionally to the increase of water content in intrinsic aging, photoaging would lead to further collagen depletion and an additional increase in water content of the dermis.

MATERIALS AND METHODS

A panel of 24 female subjects of different age-groups and scores of photoaging was recruited. A ranking of high resolution dorsal forearm photographs was used to classify the degree of photoaging with high precision. After that, CRS water content and collagen measurements were performed in the photoexposed dorsal as well as the photoprotected volar dermis of the subjects.

RESULTS

A positive correlation of water content in the dermis with age could be confirmed (r = .550). Further, a positive correlation between water content of dorsal dermis and photoaging ranks was observed (Pearson's r = .417).

CONCLUSION

Assessment of water content in the dermis with confocal Raman spectroscopy was found to be a promising method to measure the degree of photoaging in human subjects in vivo.

Inhibitory effect of oyster hydrolysate on wrinkle formation against UVB irradiation in human dermal fibroblast via MAPK/AP-1 and TGFβ/Smad pathway

The skin keeps the human body healthy from extrinsic stimuli such as ultraviolet (UV) irradiation. However, chronic exposure of these stimuli reduces the number of proteins that constitute the extracellular matrix (ECM) and causes wrinkle formation. The amount of collagen, the main protein that constitutes connective tissue, is reduced in the human skin due to UV radiation. When human dermal fibroblasts were damaged by UVB, UVB increased the MMPs expressions and degraded type I collagen and other ECM proteins. Oyster (Crassostrea gigas) hydrolysate (OH) is known to have anticancer, antioxidant, and anti-apoptotic effects. To scrutinize the anti-wrinkle effect of the OH in the viewpoint of the balance between collagen degradation and synthesis, we conducted the study in UVB damaged human dermal fibroblasts. We determined type I procollagen, MMPs and related proteins using ELISA kit, qRT-PCR and western blot. In our study, we discovered that OH inhibits collagen degradation by regulating MAPKs, AP-1 and MMPs expression. Also, we found that OH promotes collagen production by enhancing TGFβ receptor II expression and Smad3 phosphorylation. These results showed that OH regulates collagen degradation and stimulates collagen synthesis. Through this study, we found that OH is effective in inhibiting wrinkle formation and restore photo-aged human skin. It indicates that OH can be one of the functional materials in the fields of anti-wrinkle research.

Enhanced Skin Permeation of Anti-wrinkle Peptides via Molecular Modification

Wrinkles can have a negative effect on quality of life and Botox is one of the most effective and common treatments. Argireline (Arg0), a mimetic of Botox, has been found to be safer than Botox and effective in reducing wrinkles, with efficacies up to 48% upon 4 weeks of twice daily treatment. However, the skin permeation of Arg0 is poor, due to its large molecular weight and hydrophilicity. Arg0 exists in zwitterionic form and this charged state hindered its skin permeation. Chemical modification of the peptide structure to reduce the formation of zwitterions may result in increased skin permeability. We investigated a total of 4 peptide analogues (Arg0, Arg1, Arg2, Arg3), in terms of skin permeation and wrinkle reduction. The 4 peptides were dissolved in various propylene glycol and water co-solvents. Enhanced human skin permeation was demonstrated by both Arg2 and Arg3 in vitro. On the other hand, the abilities of the 4 analogues to reduce wrinkle formation were also compared using primary human dental pulp stem cells derived neurons. By measuring the inhibition of glutamate release from the neurons in vitro, it was shown that Arg3 was the most effective, followed by Arg1, Arg0 and Arg2.

What is the role of mitochondrial dysfunction in skin photoaging?

Skin ageing is a complex process involving both internal and external factors, which leads to a progressive loss of cutaneous function and structure. Solar radiation is the primary environmental factor implicated in the development of skin ageing, and the term photoaging describes the distinct clinical, histological and structural features of chronically sun-exposed skin. The changes that accompany photoaging are undesirable for aesthetic reasons and can compromise the skin and make it more susceptible to a number of dermatological disorders. As a result, skin ageing is a topic that is of growing interest and concern to the general population, illustrated by the increased demand for effective interventions that can prevent or ameliorate the clinical changes associated with aged skin. In this viewpoint essay, we explore the role that mitochondria play in the process of skin photoaging. There is continuing evidence supporting the proposal that mitochondrial dysfunction and oxidative stress are important contributing factors in the development of skin photoaging. Further skin-directed mitochondrial research is warranted to fully understand the impact of mitochondrial status and function in skin health. A greater understanding of the ageing process and the regulatory mechanisms involved could lead to the development of novel preventative interventions for skin ageing.

Histological observation of hairless mice skin after exposure to Simulated Solar Light: Comparison between the histological findings with different methodologies and 3R principle correlations

BACKGROUND

Albino hairless mouse (AHM) has been used as a biological model in photodermatology. However, the experimental landscape is diverse to follow and need particular attention.

PURPOSE

Irradiation parameters were investigated for the development of a protocol to assess alterations in the AHM skin using Simulated Solar Light (SSL). The present study was compared with published articles (last 15 years) according to irradiation protocols, morphological findings to minimize animal suffering and UV exposure.

MATERIALS AND METHODS

Three groups: Control (G1), experimental - sunburn (G2) and skin photodamage assay (G3). G2 were immobilized and exposed to SSL once for 15, 30 and 45min. G3 were exposed to SSL, without immobilization, for 15min once a day for one week. The dorsal skin was analyzed using hematoxylin and eosin technique.

RESULTS

G2 displayed different sunburn degrees. Based on the profile of the observed morphological alterations, a 15min irradiation was chosen as the exposure time to expose G3, without immobilization, for 5 consecutive days.

CONCLUSION

These conditions produced the same morphological changes in the AHM with a shorter solar exposure time, without immobilizing the animals but using environmental exposure fluences, conforming to 3R (reduction - refinement - replacement) recommendations.

Molecular Mechanisms of Stress-Responsive Changes in Collagen and Elastin Networks in Skin

Collagen and elastin networks make up the majority of the extracellular matrix in many organs, such as the skin. The mechanisms which are involved in the maintenance of homeostatic equilibrium of these networks are numerous, involving the regulation of genetic expression, growth factor secretion, signalling pathways, secondary messaging systems, and ion channel activity. However, many factors are capable of disrupting these pathways, which leads to an imbalance of homeostatic equilibrium. Ultimately, this leads to changes in the physical nature of skin, both functionally and cosmetically. Although various factors have been identified, including carcinogenesis, ultraviolet exposure, and mechanical stretching of skin, it was discovered that many of them affect similar components of regulatory pathways, such as fibroblasts, lysyl oxidase, and fibronectin. Additionally, it was discovered that the various regulatory pathways intersect with each other at various stages instead of working independently of each other. This review paper proposes a model which elucidates how these molecular pathways intersect with one another, and how various internal and external factors can disrupt these pathways, ultimately leading to a disruption in collagen and elastin networks.

The life cycles and biological end pathways of dermal fillers

BACKGROUND

There is an increased demand for soft tissue augmentation procedures. A wide range of products can provide correction through different mechanisms and it is important for clinicians to understand the biological pathways of each material. This study presents a systematic review of the pathways of commonly used fillers, with consideration of the complications associated with each.

METHODS

The PubMed (National Library of Medicine) database was searched for MeSH headings for different types of fillers, including trade names, between January 1, 2000, and January 1, 2013. Article titles were screened, and only studies designed to determine the mechanism of action and histopathology of complications were included.

RESULTS

When restricted to studies on biological mechanisms, 109 manuscripts were identified and the mechanisms of action of short-term and long-term degradable as well as permanent fillers were reviewed. Hyaluronic acid fillers, which are the most commonly used, form a fibrous capsule and induce limited de novo collagen. Poly-l-lactic acid and calcium hydroxylapatite are semipermanent fillers that provide long-term restoration of tissue volume by stimulating fibroblasts to lay down a matrix of collagen and elastic fibers. Polymethyl methacrylate is the only FDA-approved permanent implant that is held in place by encapsulation, providing a scaffold upon which the dermis can recover to its original thickness.

DISCUSSION

Soft tissue augmentation products are variable, and no single product can be considered the most effective or ideal. An understanding of biological mechanisms may help guide physicians choose the best suited product among the various options available while minimizing the occurrence of complications.

Methods for evaluation of cosmetic antioxidant capacity

The skin as the largest part of human body is one of the main targets for ultraviolet radiation, environmental pollution, toxic chemicals and some metal ions, which share responsibility for the formation of free radicals. The resulting free radicals, both oxygen and nitrogen species are one of the main causes of aging due to impaired regulation of cell respiratory metabolism involving incomplete oxygen reduction in mitochondria and production a superoxide anion, hydroxyl radicals et al. In modern cosmetology to minimize the adverse effects of free radicals, antioxidants, which inhibit free radical reactions, mainly autoxidation processes are used. Currently, not only many cosmetic products containing antioxidants are available, but a large diversity of methods for determination of cosmetics antioxidant activity is also accessible. These methods can be divided into three main groups: in vitro, in vivo, and ex vivo as reported herein. Due to lack of standardization and validation it is necessary to use a variety of methods as well as conditions for those purposes, which are presented to the context.

Influence of season on some skin properties: winter vs. summer, as experienced by 354 Shanghaiese women of various ages

The facial skin of 354 women, aged 18-80, living in Shanghai, was investigated over two successive 6-month periods, summer and winter. Results from clinical assessments indicate that aging signs, such as wrinkling and sagging, are unaffected over such period. However, physical measurements revealed alterations in some functional criteria of the skin, such as sebum output, skin colour, melanin content of pigmented spots, skin hydration, all being increased during summer. The relationships between all criteria, as well as technical or applied inferences/consequences from this study, are discussed.

Age-related changes in elastic properties and moisture content of lower labial mucosa

The purpose of this study was to clarify age-related changes in the elastic properties and moisture content of the lower labial mucosa. Elastic properties and moisture content were also compared between the lower labial mucosa and skin. A total of 85 adults aged 20-82 took part in the study. Elastic properties (distensibility and elasticity) and moisture content of lower labial mucosa and skin were determined in each participant. Measurements for the oral mucosa were taken at the midline of the lower labial mucosa; for the skin, they were taken at the midpoint of the right anterior surface of the forearm. Pearson's correlation coefficient and the Mann-Whitney U test were used for the statistical analysis. A stepwise multiple linear regression analysis was also performed, with age as the dependent variable and sex, distensibility, elasticity and moisture content of the lower labial mucosa as independent variables. A negative correlation was found between age and distensibility of the lower labial mucosa. No correlation was observed between age and elasticity of the lower labial mucosa. A negative correlation was observed between age and moisture content of the lower labial mucosa. A significant difference was observed in moisture content between the 20- to 39-year-old group and the over 40-year-old group. Stepwise analysis identified distensibility and moisture content of the lower labial mucosa as predictive factors of age. The results indicate that distensibility and moisture content of the lower labial mucosa decrease with age. Moisture content in the over 40-year-old group, in particular, was lower than in the 20- to -30-year-old group.

Male skin care needs

Male skin care has undergone significant development over the past decade, with many companies now marketing skin care products directly to the male consumer. Despite the claims of many of these companies, few over-the-counter products have data to support their efficacy at a clinical level. A basic, effective regimen for preventive male skin care should include twice-daily facial cleansing and twice-daily moisturizer application, which should include sunscreen during the day. This article focuses on topical therapies directed at the maintenance and repair of photoaged male skin. The future holds promise for new developments in skin care. However, in the absence of significant scientific breakthroughs, the most cost-effective intervention will continue to be prevention.

Non-invasive monitoring of oxidative skin stress by ultraweak photon emission measurement. II: biological validation on ultraviolet A-stressed skin

BACKGROUND/PURPOSE

Several physical or chemical environmental stressors generate reactive oxygen species, which trigger oxidation reactions of cells or tissues and thereby induce a correlated ultraweak photon emission (UPE) signal. The present study was designed to qualify and validate UPE measurement following ultraviolet (UV) excitation of porcine and human skin as an analytical method to assess the potency of topical antioxidants in vivo.

METHODS

UPE of porcine skin in vitro and human skin in vivo following excitation with UVA was recorded using sensitive photomultiplier systems. For validation purposes, the effects of variation of extrinsic and intrinsic parameters encompassing skin thickness, humidity, temperature, pH, and composition of the surrounding atmosphere were assessed. Signals were analyzed with regard to overall signal intensity and spectral distribution. In two clinical trials enrolling 20 volunteers each, the effects of topical antioxidant treatment on UVA-induced UPE were validated.

RESULTS

Different stressors encompassing exposition to ozone, UVA irradiation, or even cigarette smoke induced UPE of skin. Critical parameters affecting the quality and quantity of the UPE signal were the spectral composition of the exciting UV light, skin temperature, skin humidity, and the O(2) concentration of the surrounding atmosphere. Generally, UVA-induced UPE decreased with increasing temperature, humidity, and O(2) concentration. Skin pH had no significant effect on UPE with regard to signal quality and quantity over a pH range of 2.8-8.2. In a clinical study UPE measurement following UVA excitation could precisely reflect a dose-dependent antioxidant effect of topically applied vitamin C and alpha-glucosylrutin.

CONCLUSION

Our data indicate that UVA irradiation induces UPE especially in deeper (living) skin layers, where antioxidants must be active in order to interfere with accelerated skin ageing. Based on the clinical data, and with knowledge of modulating external variables, UPE measurement following UV excitation can be qualified as a reliable and valid method for the non-invasive measurement of antioxidant efficacy on the skin.

A topical lipophilic niacin derivative increases NAD, epidermal differentiation and barrier function in photodamaged skin

The effects of myristyl nicotinate (MN), a nicotinic acid derivative designed to deliver nicotinic acid to skin without vasodilatation, on subjects with photodamaged skin have been studied. MN increased skin cell nicotinamide adenine dinucleotide (NAD) by 25% (P = 0.001) demonstrating effective delivery of nicotinic acid to skin. Relative to placebo, MN treatment of photodamaged facial skin increased stratum corneum thickness by approximately 70% (P = 0.0001) and increased epidermal thickness by approximately 20% (P = 0.001). In two separate studies, MN treatment increased rates of epidermal renewal by 6% (P = 0.003) to 11% (P = 0.001) and increased the minimal erythemal dose by 8.9 (P = 0.07) and 10% (P = 0.05) relative to placebo. MN treatment resulted in reductions in the rates of transepidermal water loss (TEWL) of approximately 20% relative to placebo on cheeks (P = 0.012) and arms (P = 0.017) of study subjects. Results of a tape stripping challenge before and after MN treatment demonstrated a significant correlation (P = 0.03) between increased skin NAD content and resistance to changes in TEWL for MN treated but not placebo subjects. Rates of TEWL changed more rapidly and to a greater extent in atopic subjects compared with normal subjects. The results indicate that MN enhances epidermal differentiation and barrier function in skin, suggesting that this method of nicotinic acid delivery may prove useful in limiting progression of actinic skin damage and possibly in treating other conditions involving skin barrier impairment.

Elderly skin and its rejuvenation: products and procedures for the aging skin

In the last few decades, there has been a substantial increase in the population of people over 60 years of age. Most of them maintain a good general health and physical activity and fitness. For these individuals there is a good number of dermatologic procedures, medications, and cosmetics that can be prescribed to improve the aspect of skin aging, providing an improvement in their self-esteem and quality of life as a result of their better look. We will discuss the mechanisms of skin aging, and the procedures and substances used to minimize its deleterious effects, such as sunscreens, estrogens, chemical peels, toxin botulinum, fillers and surgical procedures, among others. The use of makeup and the adverse reactions to cosmetics will also be mentioned.

Skin aging and natural photoprotection

Aging of skin is a continuous process that may be enhanced by sun exposure. Photoaging may provoke changes different from aging. Epidermal changes involve thinning of stratum spinosum and flattening of the dermo-epidermal junction. The senescent keratinocytes becomes resistant to apoptosis and may survive for a long time giving time for DNA and protein damage to accumulate with possible implication for carcinogenesis. The numbers of melanocytes decrease with age with dysregulation of melanocyte density resulting in freckles, guttate hypo-melanosis, lentigines and nevi. The number of dendritic Langerhans cells also decreases with age and the cells get less dendrites and have reduced antigen-trapping capacity. Aging involves dermal changes such as damage to elastic and collagen fibers giving thickened, tangled, and degraded non-functional fibers. Collagen intermolecular cross-links are stable and essential for stability and tensile strength. Cross-links increase with age converting divalent cross-links into mature trivalent cross-links of, e.g. histidinohydroxylysinonorleucine. Two mechanisms are involved; an enzyme-controlled process of maturation and a non-enzymatic glycosylation, the Maillard reaction leading to cross-links in proteins such as in collagen between arginine and lysine. Such may be seen with age and in diabetes mellitus. However, autofluorescence studies have shown that UVR reduces collagen cross-links. Natural photoprotection involves thickening of stratum corneum by sunlight and increased pigmentation. This leads to a factor 2 increase in photoprotection from spring until after-summer. The constitutive pigmentation is independent of age and thickness of stratum corneum is likewise independent of age. The minimal erythema dose is thus the same through life, when corrected for pigmentation or measured in areas with constitutive pigmentation.