Skin hydration: a review on its molecular mechanisms

Krill oil supplementation improves transepidermal water loss, hydration and elasticity of the skin in healthy adults: Results from two randomized, double-blind, placebo-controlled, dose-finding pilot studies

BACKGROUND

Dietary marine omega-3 fatty acids and phospholipids have individually shown favorable effects on skin barrier function. Krill oil offers a combination of omega-3 in phospholipid form which might enhance the efficacy in supporting skin health.

AIMS

The aim was to investigate the impact of two different doses of krill oil on skin transepidermal water loss (TEWL) in healthy adults. Secondary outcomes were skin hydration, elasticity and the omega-3 index.

METHODS

Two randomized, double-blind, placebo-controlled, pilot studies were conducted in healthy adults with a baseline TEWL of >10 and ≤24.9 g/m2/h. In study 1, 51 participants consumed 1 g of krill oil or placebo daily. In study 2, 50 participants consumed 2 g of krill oil or placebo daily. The outcomes were assessed at baseline, 6 and 12 weeks.

RESULTS

The krill oil supplemented groups significantly increased their omega-3 index versus placebo in both studies. Furthermore, the krill oil groups in both studies showed statistically significant beneficial reductions in TEWL (from 14.47 ± 3.65 to 13.83 ± 3.78 in study 1 and from 14.25 ± 3.21 to 13.02 ± 2.76 in study 2) and increases in hydration and elasticity when compared to placebo. There were significant linear relationships between changes in the omega-3 index and changes in TEWL, hydration and elasticity in both studies.

CONCLUSIONS

Daily oral supplementation with 1 and 2 g of krill oil showed significant and dose-dependent improvements in skin TEWL, hydration, and elasticity compared to placebo that correlated with changes in the omega-3 index.

Influence of skin hydration level on the occurrence of blisters on the foot during hiking

Friction blisters are common among outdoor enthusiasts, yet their causes remain uncertain. This study aimed to compare foot hydration in long-distance hikers with and without blisters, and to assess variability based on age and sex. An observational case-control study involving 86 hikers was conducted. Skin hydration was measured using a corneometer on various foot zones. Data on blister count, footwear, sex, age, and temperature were recorded. The most hydrated zones were the digital area, forefoot, and heel. Higher hydration was found in the blister group (61.6%) compared to the control group (38.4%). A significant relationship between hydration and blisters was observed in the left foot (p = 0.032). Total foot hydration was higher in women (p = 0.007) and inversely related to age (r = -0.333; p = 0.002). Hydration values above 30.40 a.u. in the right foot and 27.37 a.u. in the left foot were linked to blisters with 80% sensitivity. This study highlights the variability in foot hydration and its relationship with blisters. The influence of age and wet socks underscores the complexity of blister formation, emphasizing the need for future research on effective prevention.

Treatment effects of two pharmaceutical skin care creams for xerotic feet among persons with diabetes: Rationale and design of a two-armed double blind randomized controlled trial

Introduction

To minimize the risk of developing foot-ulcers, persons with diabetes are given the advice to daily inspect their feet and to apply skincare formulations. However, commercially available skincare products have rarely been developed and evaluated for diabetes foot care specifically. The primary aim of this randomized controlled trial (RCT) is to evaluate the effects in reducing foot xerosis in persons with diabetes without foot-ulcers using two skincare creams containing different humectants (interventions) against a cream base non-humectant (comparator). Secondary outcomes are to evaluate differences on skin barrier integrity, low-molecular weight biomarkers and skin microbiota, microcirculation including transcutaneous oxygen pressure, degree of neuropathy, and HbA1c between intervention-comparator creams.

Methods

Two-armed double-blind RCT, registered in ClinicalTrials.gov Identifier: NCT06427889. With 80 % power, two-tailed significance of 2.5 % in each arm, 39 study persons is needed in each arm, total 78 persons, 98 including dropouts, to be able to prove a reduction of at least one category in the Xerosis Severity Scale with the intervention creams compared to the comparator. In one arm, each participant will treat one foot with one of the intervention creams (Oviderm® or Canoderm®), while the opposite foot will be treated with the comparator cream (Decubal®lipid cream), twice a day. If needed, participants are enrolled after a wash-out period of two weeks. The participants will undergo examinations at baseline, day 14 and day 28.

Discussion

This RCT evaluate the potential effects of humectants in skin creams against foot xerosis in persons with diabetes.

Improved Skin Barrier Function Along with Hydration Benefits of Viola yedoensis Extract, Aesculin, and Schaftoside and LC-HRMS/MS Dereplication of Its Bio-Active Components

The skin hydration level is a key factor that influences the physical and mechanical properties of the skin. The stratum corneum (SC), the outermost layer of the epidermis, is responsible for the skin's barrier function. In this study, we investigated the role of a unique composition of Viola yedoensis extract for its ability to activate CD44, a cell-surface receptor of hyaluronic acid, and aquaporin-3, a water-transporting protein, in human keratinocytes (HaCaT). An ELISA assay evaluating the protein expression levels of CD44, aquaporin-3 (AQP3), filaggrin, and keratin-10 revealed that V. yedoensis extract upregulated the levels of CD44 and AQP3 by 15% and 78%, respectively. Additionally, V. yedoensis extract demonstrated a comparative effect on water vapor flux in TEWL and lipid perturbation in DSC versus the reference, glycerin. In light of this new biological efficacy, a detailed phytochemical characterization was undertaken using an integrated LC-HRMS/MS-based metabolomics approach, which provided further insights on the chemistry of V. yedoensis. This led to the identification of 29 secondary metabolites, 14 of which are reported here for the first time, including esculetin, aesculin, apigenin and kaempferol C-glycosides, megastigmane glycosides, roseoside, platanionoside B, and an eriojaposide B isomer, along with the rare, calenduloside F and esculetin diglucoside, which are reported for the first time from the genus, Viola. Notably, two active components identified in the V. yedoensis extract, namely, aesculin and schaftoside, showed an upregulation of the protein expression of CD44 in HaCaT cells by 123% and 193% within 24 h of treatment, respectively, while aesculin increased AQP3 levels by 46%. Aesculin and schaftoside also significantly upregulated the expression of K-10 levels by 299% and 116%, which was considerably higher than sodium hyaluronate, the positive control. The rationale used to characterize the new structures is outlined along with the related biosynthetic pathways envisioned to generate roseoside and Eriojaposide B. These findings provide new molecular insights to deepen the understanding of how V. yedoensis extract, along with the biomarkers aesculin and schaftoside, restores the skin barrier and skin hydration benefits.

Effect of Ceramides Derivatives from the Peach on Skin Function Improvement in UV-Irradiated Hairless Mice

This study investigated the protective effects of a ceramides derivates from the peach (PF3) on photoaging by UV-irradiated hairless mice. Mice were randomly divided into seven groups: AIN93G without UVB exposure (normal control, NC), AIN93G with UVB exposure (control, C), AIN93G supplemented 100 mg/kg body weight (BW) of L-ascorbic acid with UVB exposure (AA), AIN93G supplemented 100 mg/kg BW of arbutin with UVB exposure (Arbutin), AIN93G supplemented 10 mg/kg BW of PF3 with UVB exposure (10PF3), AIN93G supplemented 20 mg/kg BW of PF3 with UVB exposure (20PF3), and AIN93G supplemented 40 mg/kg BW of PF3 with UVB exposure (40PF3). The study examined the impact of PF3 on skin hydration, wrinkle formation, and melanogenesis using enzyme-linked immunosorbent assay (ELISA), real-time polymerase chain reaction (real-time PCR), and Western blot analysis. The PF3 demonstrated significant protective effects against photoaging by reducing skin wrinkle formation, decreasing epidermal and dermal thickening, and improving skin hydration. It also enhanced the expression of moisture-related factors (hyaluronic acid synthase [HAS], long-chain ceramides [LCBs], dihydroceramide desaturase 1 [DEGS1], and type I collagen [COL1A]) and antioxidant enzyme activities while reducing pro-inflammatory cytokines and oxidative stress markers. The PF3 supplementation positively modulated skin wrinkle formation-related factors, increasing collagen-related gene expression and decreasing matrix metalloproteinases. Additionally, PF3 showed potential in regulating melanogenesis by reducing the nitric oxide and cAMP content, as well as the expression of melanogenesis-related proteins. These comprehensive findings suggest that PF3 supplementation may be an effective strategy for preventing and treating UVB-induced skin photoaging through multiple mechanisms, including improved skin structure, hydration, antioxidant defense, and reduced inflammation and pigmentation.

Association between lifestyle and skin moisturizing function in community-dwelling older adults

The skin's moisturizing function declines with age, resulting in skin dryness in around 40% of older people. Various lifestyle habits may affect the skin moisturizing function, however it is not clear which ones are particularly relevant. A cross-sectional study was conducted between September and December 2023, involving individuals aged 65 years and over. Self-administered questionnaires were employed to collect information on lifestyle habits. Stratum corneum hydration (SC hydration), as an indicator of skin hydration, was measured and analyzed using multiple regression. A total of 124 individuals participated in the study, with a mean age of 83.6 years. Daily use of moisturizer (p=0.024) and exercise level (p=0.002) demonstrated significant associations with increased SC hydration. Although not statistically significant, smoking exhibited a trend towards decreased SC hydration (p=0.173). The findings of this study suggest that, among various lifestyle habits, exercise and daily moisturizing contribute to enhanced SC hydration. These results indicate that lifestyle modifications may improve the skin moisturizing function of the elderly.

Age-related variations in stratum corneum hydration in the foot

OBJECTIVE

The aims of the study are to identify which region of the foot has lower hydration according to age, measure the variation in the level of stratum corneum hydration of the foot across the a wide age range, and examine hydration differences of the foot according to gender.

STUDY DESIGN

A descriptive observational study was conducted to assess stratum corneum hydration of the foot among 504 participants recruited between November 2023 and March 2024.

MAIN OUTCOMES MEASURES

Stratum corneum hydration assessment was conducted using a Corneometer 825® probe at 10 specific points on the foot. Data on sociodemographic variables, medical history, foot care habits, and hydration-related factors were collected. Statistical analyses were performed using SPSS v. 24.0.

RESULTS

Stratum corneum hydration of the foot varied significantly across regions, with higher hydration in the digital zone and lower hydration in the heel. An inverse correlation was found between age and hydration, with younger participants exhibiting higher hydration levels. Women showed higher hydration than men. Differences in hydration were observed between the right and left feet.

CONCLUSION

This study highlights the importance of localized assessment of foot skin dehydration. Aging significantly affects stratum corneum hydration of the foot. Gender differences in hydration suggest the importance of personalized approaches to skin care. Differential hydration between feet underscores the influence of mechanical load.

The Potential Role of Cannabidiol in Cosmetic Dermatology: A Literature Review

Cannabidiol (CBD) is a non-psychotropic cannabinoid with multiple pharmacological properties. Cannabidiol has attracted growing attention in the cosmetic industry, with an increasing number of CBD-containing skincare products on the market in recent years. The aim of this review is to evaluate the current evidence on the use of CBD for cosmetic purposes. Following an overview of CBD and the endocannabinoid system in the skin, we summarize pre-clinical and clinical studies that address the potential of CBD in cosmetic dermatology. Available in vitro and in vivo evidence suggests that CBD has anti-oxidant, anti-inflammatory, moisturizing, anti-acne, wound-healing, and anti-aging properties. However, only a few clinical studies have been conducted on the use of CBD in the skin. In addition, there is a critical need to develop an efficient drug-delivery system for topical/transdermal application of CBD. Further research, including clinical and pharmacokinetic studies, are needed to fully evaluate the role of CBD in cosmetic dermatology.

Short-term skin reactions and changes in stratum corneum following different ways of facial sheet mask usage

BACKGROUND

The global facial mask market grows steadily at 8.5 % annually. However, prolonged use may lead to skin inflammation.

OBJECTIVE

To investigate how various mask types and wearing durations impact skin physiology and aquaporins3 (AQP3) expression in healthy subjects.

METHODS

We used a randomized controlled design to investigate the effects of three types of facial masks (pure water, hyaluronan, and bifida ferment lysate) and four different duration(5, 15, 25, and 40 min) on various skin parameters in volunteers, assessing moisture content, transepidermal water loss (TEWL), sebum, corneocyte size, and AQP3 expression before and after mask application, while also evaluating adverse reactions, discomfort, and noncompliance.

RESULT

Hydration and TEWL increased at first, then decreased. Sebum increased with all types of masks, particularly after 40 min. Vasodilation and AQP3 expression were linked to mask duration. Corneocyte sizes remained constant. The main adverse reactions were redness (10.71 %, n = 28) and dryness (57.14 %, n = 28), especially with pure water masks lasting over 25 min.

CONCLUSION

Short-term use of facial sheet masks (<25 min) benefits skin with improved hydration, reduced redness, and AQP3 activation, while prolonged use can lead to increased dryness and redness.

Perspectives of aminoacylases in biocatalytic synthesis of N-acyl-amino acids surfactants

Many industrial processes are performed using harmful chemicals. The current technical synthesis of N-acyl-amino acids relies on acyl chlorides, which are typically obtained from phosgene chemistry. A greener alternative is the application of whole cells or enzymes to carry out synthesis in an environmentally friendly manner. Aminoacylases belong to the hydrolase family and the resolution of racemic mixtures of N-acetyl-amino acids is a well-known industrial process. Several new enzymes accepting long-chain fatty acids as substrates were discovered in recent years. This article reviews the synthetic potential of aminoacylases to produce biobased N-acyl-amino acid surfactants. The focus lays on a survey of the different types of aminoacylases available for synthesis and their reaction products. The enzymes are categorized according to their protein family classification and their biochemical characteristics including substrate spectra, reaction optima and process stability, both in hydrolysis and under process conditions suitable for synthesis. Finally, the benefits and future challenges of enzymatic N-acyl-amino acid synthesis with aminoacylases will be discussed. KEY POINTS: • Enzymatic synthesis of N-acyl-amino acids, biobased surfactants by aminoacylases.

Skin Hydration Measurement: Comparison Between Devices and Clinical Evaluations

BACKGROUND

The need for an objective method for measuring skin hydration levels is becoming increasingly important. Various devices with different measuring principles for assessing skin hydration have been developed and are widely used.

OBJECTIVE

This study aimed to investigate the reproducibility and correlation between clinical evaluation and skin hydration measurement devices that are the most widely used in the field.

METHODS

A prospective comparative clinical trial was conducted on 184 healthy volunteers. Skin hydration levels were measured using the Corneometer (CM820) and hydration probe (HP: DermaLab Combo) at 3 points: the ventral forearm, the dorsal forearm, and the shin. We used the intraclass correlation coefficient (ICC) to evaluate the reproducibility and Pearson's correlation coefficient (PCC) to evaluate the correlation of each measurement. Simple linear regression was used to analyze the Corneometer and HP skin hydration value changes according to changes in xerosis severity scale (XSS) values, which were evaluated by clinicians.

RESULTS

Both the Corneometer and HP showed significant, excellent reproducibility (ICC for Corneometer: 0.954-0.971, ICC for HP: 0.980-0.986) and significant high positive correlations (PCC: 0.708-0.737) regardless of the measurement site. Both devices showed negative regression coefficients in all measurement sites in XSS analysis, but this was not statistically significant.

CONCLUSION

The Corneometer and HP were both accurate and objective skin hydration measuring devices, regardless of the measurement site. Using reliable and objective devices such as the Corneometer or HP can aid in understanding an individual's skin condition and making more informed decisions for skin care.

TRIAL REGISTRATION

Clinical Research Information Service Identifier: KCT0005146.

Novel Cosmetic Ingredient CS-AA Polyion Complex and Skin Moisturizing Effect

PURPOSE

The study explored the enhanced skin moisturizing capabilities and moisture retention effects achieved by forming a polyion complex using sulfated glycosaminoglycan (GAG), specifically chondroitin sulfate (CS), and amino acids (AA) such as glutamine (Q) and arginine (R). The overall hydration effect of this CS-AA complex was examined.

METHODS

After analyzing the CS-AA polyion complex structure using spectroscopic methods, the ex vivo moisture retention ability was assessed under dry conditions using porcine skin samples. Additionally, the efficacy of the CS-AA polyion complex in reducing transepidermal water loss (TEWL) and improving skin hydration was evaluated on human subjects using a digital evaporimeter and a corneometer, respectively.

RESULTS

Validating a systematic reduction in particle size, the following order was observed: CS > CS/AA simple mixture > CS-AA complex based on dynamic light scattering (DLS) and transmission electron microscopy (TEM) analysis. Furthermore, observations revealed that the CS-AA complex exhibits negligible surface charge. Additionally, Fourier-transform infrared spectroscopy (FT-IR) analysis demonstrated a distinct peak shift in the complex, confirming the successful formation of the CS-AA complex. Subsequently, the water-holding effect through porcine skin was assessed, revealing a notable improvement in moisture retention (weight loss) for the CS-Q complex: 40.6% (1 h), 20.5% (2 h), and 18.7% (4 h) compared to glycerin. Similarly, the CS-R complex demonstrated enhancements of 50.2% (1 h), 37.5% (2 h), and 33% (4 h) compared to glycerin. Furthermore, TEWL improvement efficacy on human skin demonstrated approximately 25% improvement for both the CS-Q complex and CS-R complex, surpassing the modest 12.5% and 18% improvements witnessed with water and glycerin applications, respectively. Finally, employing a corneometer, hydration changes in the skin were monitored over 4 weeks. Although CS alone exhibited nominal alterations, the CS-Q complex and CS-R complex showed a significant increase in moisture levels after 4 weeks of application.

CONCLUSION

In this study, polyion complexes were successfully formed between CS, a sulfated GAG, and AA. Comparisons with glycerin, a well-known moisturizing agent, confirmed that the CS-AA complex exhibits superior moisturizing effects in various aspects. These findings suggest that the CS-AA complex is a more effective ingredient than CS or AA alone in terms of efficacy.

Variation of skin hydration profile with biophysical factors and lifestyle revealed by in vivo terahertz sensing

The skin, being the body's largest organ, plays a pivotal role in protecting the body against dangerous external factors. The maintenance of adequate hydration levels is essential for the skin to fulfill this protective function. However, skin hydration depends upon different biophysical factors and lifestyles, such as ethnicity, sex, age, water consumption, and many more. Consequently, methods to assess skin hydration in a precise and non-invasive manner are in high demand. In this paper, using a portable and handheld terahertz (THz) probe, we systematically examine the correlation between diverse biophysical factors and skin hydration profile in a population exceeding 300 participants. Through comparative analysis of THz light reflected from the skin against a dielectric model, we successfully extracted the thickness and hydration percentage of the outermost layer of the epidermis, the stratum corneum (SC). Our findings indicate that SC hydration and thickness are associated with variables such as daily water consumption, age, drinking coffee, and exercise. Additionally, our measurements reveal distinctions in the skin's hydration properties concerning susceptibility to UV-induced effects by bringing in the Fitzpatrick skin types. This THz-based technique holds the potential for facile integration into clinical settings for the evaluation and diagnosis of various skin-related conditions.

Oral tranexamic acid treats papulopustular rosacea by improving the skin barrier

BACKGROUND

Papulopustular rosacea (PPR) is a chronic inflammatory disease with a significant impact on facial aesthetics. An impaired skin barrier is an important factor in the development and exacerbation of PPR. Tranexamic acid (TXA) has immune regulatory and anti-inflammatory effects, inhibits angiogenesis and endothelial hyperplasia, and promotes skin barrier repair.

AIMS

We investigated the efficacy and safety of oral TXA for PPR treatment.

PATIENTS/METHODS

In total, 70 patients were randomly assigned to receive traditional therapy plus oral TXA or traditional therapy alone for 8 weeks, with a 4-week follow-up period. The subjective improvement in rosacea was assessed using the clinical erythema assessment (CEA), investigator's global assessment (IGA), patient self-assessment (PSA) score, rosacea-specific quality of life (RQoL) score, and global aesthetic improvement score (GAIS). An objective improvement in rosacea was assessed using skin hydration, trans-epidermal water loss (TEWL), clinical photography, and an eight spectrum facial imager.

RESULTS

CEA/IGA/PSA, dryness, and RQoL scores were significantly lower and GAIS was higher in the TXA group than in the traditional therapy group. Furthermore, oral TXA significantly improved skin barrier function, increased skin hydration, and decreased TEWL, with no significant side effects. Notably, we observed better outcomes and a greater improvement in skin barrier function with TXA treatment in patients with dry-type rosacea than in patients with oily skin.

CONCLUSIONS

The addition of oral TXA to traditional therapy can lead to rapid and effective improvements in PPR, which may be attributed to improvements in skin barrier function.

Dermal Injection of Recombinant Filaggrin-2 Ameliorates UVB-Induced Epidermal Barrier Dysfunction and Photoaging

The epidermal barrier is vital for protecting the skin from environmental stressors and ultraviolet (UV) radiation. Filaggrin-2 (FLG2), a critical protein in the stratum corneum, plays a significant role in maintaining skin barrier homeostasis. However, the precise role of FLG2 in mitigating the adverse effects of UV-induced barrier disruption and photoaging remains poorly understood. In this study, we revealed that UVB exposure resulted in a decreased expression of FLG2 in HaCaT keratinocytes, which correlated with a compromised barrier function. The administration of recombinant filaggrin-2 (rFLG2) enhanced keratinocyte differentiation, bolstered barrier integrity, and offered protection against apoptosis and oxidative stress induced by UVB irradiation. Furthermore, in a UV-induced photodamage murine model, the dermal injection of rFLG2 facilitated the enhanced restoration of the epidermal barrier, decreased oxidative stress and inflammation, and mitigated the collagen degradation that is typical of photoaging. Collectively, our findings suggested that targeting FLG2 could be a strategic approach to prevent and treat skin barrier dysfunction and combat the aging effects associated with photoaging. rFLG2 emerges as a potentially viable therapy for maintaining skin health and preventing skin aging processes amplified by photodamage.

Delivery of small hydrophilic molecules across the stratum corneum: Identification of model systems and parameters to study topical delivery of free amino acids

Free amino acids (FAAs) constitute the largest component (∼40 %) of the so-called natural moisturizing factors of the skin. Their level declines in dry skin conditions and one strategy to overcome this problem may involve the topical delivery of FAAs through appropriate strategy. The objective of the present study was therefore to identify alternative skin models and study the corneocyte-water partition coefficients (KCOR/W) and permeation coefficient (KP) of 18 FAAs. The KCOR/W was studied using standard protocols and the permeation studies were conducted using Franz diffusion cell. The results indicate that the FAAs have high partitioning behavior to the corneocytes. The KCOR/W values of the human COR and that of pig ear skin were better correlated with each other than that of keratin isolated from chicken feathers. The presence of lipid in the stratum corneum (SC), initial concentration of the FAAs, and permeation enhancers affect the KCOR/W. The FAAs have low permeation into the SC which suggests the need for permeation enhancers in designing dosage form containing these compounds. Even though the investigated mathematical models show good prediction of the Kp values, better prediction could be obtained by considering factors such as the possible entrapment of the FAAs by the CORs.

A Pressure-Sensitive, Repositionable Bioadhesive for Instant, Atraumatic Surgical Application on Internal Organs

Pressure-sensitive adhesives are widely utilized due to their instant and reversible adhesion to various dry substrates. Though offering intuitive and robust attachment of medical devices on skin, currently available clinical pressure-sensitive adhesives do not attach to internal organs, mainly due to the presence of interfacial water on the tissue surface that acts as a barrier to adhesion. In this work, a pressure-sensitive, repositionable bioadhesive (PSB) that adheres to internal organs by synergistically combining the characteristic viscoelastic properties of pressure-sensitive adhesives and the interfacial behavior of hydrogel bioadhesives, is introduced. Composed of a viscoelastic copolymer, the PSB absorbs interfacial water to enable instant adhesion on wet internal organs, such as the heart and lungs, and removal after use without causing any tissue damage. The PSB's capabilities in diverse on-demand surgical and analytical scenarios including tissue stabilization of soft organs and the integration of bioelectronic devices in rat and porcine models, are demonstrated.

Epidermal and dermal hydration in relation to skin color parameters

BACKGROUND

Our goal was to investigate linkages between skin color parameters and skin hydration. Since most prior studies focused on stratum corneum hydration, we focused on epidermal and dermal hydration in relation to skin color parameters in both sexes.

MATERIALS AND METHODS

Thirty adults (16 female) with an age ± SD of 24.3 ± 0.6 years participated. Three sites on both volar forearms were evaluated for melanin index (MI), erythema index (EI), Individual Typology Angle (ITA), tissue dielectric constant (TDC) values to depths of 0.5 mm (TDC0.5) and 2.5 mm (TDC2.5), and Fitzpatrick skin type (FST).

RESULTS

MI and EI were highly correlated (r = 0.800, p < 0.001) with maximum differences in MI and ITA along the arm of 3% and 6.3% with no difference between arms. Male MI was greater than females (p < 0.01). Male TDC2.5 was 36.1 ± 5.4 and correlated with EI (r = 0.231, p = 0.035). Contrastingly, female TDC25 was 28.5 ± 3.6 with no correlation with EI but was correlated with MI (r = -0.301, p = 0.003). These differential patterns held true for TDC0.5. For both sexes, FST and ITA were highly correlated (r = -0.756, p < 0.001).

CONCLUSIONS

The findings revealed several correlations between skin color parameters and hydration that differed between males in females in some cases. The observed correlations may indicate that melanin may differentially impact water-holding capacity between sexes and provides a future research target. Further, these initial findings also may hold significance for dermatological assessments and the customization of skincare treatments tailored to individual skin types and demographics.

Effects of solar radiations on stratum corneum hydration: Part II, protective action of solar filters

The skin surface lipids (SSLs) film, composed of sebum and keratinocyte membrane lipids, is crucial to the barrier function of the stratum corneum (SC). The first part of this study investigated the impact of solar radiation on the SC based on a novel hydration and dehydration approach using Raman spectroscopy. The SSLs were found to absorb solar light, and thus participate to the protection of the skin surface. However, the protective function of the SSLs may be limited and is dependent to the heterogenous distribution of SSLs over the body surface. To ensure comprehensive protection, synergistic measures such as the application of solar filters are necessary. In this second part of the study, we have evaluated the limits of the protection capacity of SSLs and explored the protective action of a solar filters on both SSLs composition and the water hydration and dehydration kinetics in the SC.

Polyglycerol-Functionalized β-Cyclodextrins as Crosslinkers in Thermoresponsive Nanogels for the Enhanced Dermal Penetration of Hydrophobic Drugs

Thermoresponsive nanogels (tNGs) are promising candidates for dermal drug delivery. However, poor incorporation of hydrophobic drugs into hydrophilic tNGs limits the therapeutic efficiency. To address this challenge, β-cyclodextrins (β-CD) are functionalized by hyperbranched polyglycerol serving as crosslinkers (hPG-βCD) to fabricate βCD-tNGs. This novel construct exhibits augmented encapsulation of hydrophobic drugs, shows the appropriate thermal response to dermal administration, and enhances the dermal penetration of payloads. The structural influences on the encapsulation capacity of βCD-tNGs for hydrophobic drugs are analyzed, while concurrently retaining their efficacy as skin penetration enhancers. Various synthetic parameters are considered, encompassing the acrylation degree and molecular weight of hPG-βCD, as well as the monomer composition of βCD-tNGs. The outcome reveals that βCD-tNGs substantially enhance the aqueous solubility of Nile Red elevating to 120 µg mL-1 and augmenting its dermal penetration up to 3.33 µg cm-2. Notably, the acrylation degree of hPG-βCD plays a significant role in dermal drug penetration, primarily attributed to the impact on the rigidity and hydrophilicity of βCD-tNGs. Taken together, the introduction of the functionalized β-CD as the crosslinker in tNGs presents a novel avenue to enhance the efficacy of hydrophobic drugs in dermatological applications, thereby offering promising opportunities for boosted therapeutic outcomes.

Skin Aging and the Upcoming Role of Ferroptosis in Geroscience

The skin is considered the most important organ system in mammals, and as the population ages, it is important to consider skin aging and anti-aging therapeutic strategies. Exposure of the skin to various insults induces significant changes throughout our lives, differentiating the skin of a young adult from that of an older adult. These changes are caused by a combination of intrinsic and extrinsic aging. We report the interactions between skin aging and its metabolism, showing that the network is due to several factors. For example, iron is an important nutrient for humans, but its level increases with aging, inducing deleterious effects on cellular functions. Recently, it was discovered that ferroptosis, or iron-dependent cell death, is linked to aging and skin diseases. The pursuit of new molecular targets for ferroptosis has recently attracted attention. Prevention of ferroptosis is an effective therapeutic strategy for the treatment of diseases, especially in old age. However, the pathological and biological mechanisms underlying ferroptosis are still not fully understood, especially in skin diseases such as melanoma and autoimmune diseases. Only a few basic studies on regulated cell death exist, and the challenge is to turn the studies into clinical applications.

Multi-omics analysis to evaluate the effects of solar exposure and a broad-spectrum SPF50+ sunscreen on markers of skin barrier function in a skin ecosystem model

Sun exposure induces major skin alterations, but its effects on skin metabolites and lipids remain largely unknown. Using an original reconstructed human epidermis (RHE) model colonized with human microbiota and supplemented with human sebum, we previously showed that a single dose of simulated solar radiation (SSR) significantly impacted the skin metabolome and microbiota. In this article, we further analyzed SSR-induced changes on skin metabolites and lipids in the same RHE model. Among the significantly altered metabolites (log2-fold changes with p ≤ 0.05), we found several natural moisturizing factors (NMFs): amino acids, lactate, glycerol, urocanic acid, pyrrolidone carboxylic acid and derivatives. Analyses of the stratum corneum lipids also showed that SSR induced lower levels of free fatty acids and higher levels of ceramides, cholesterols and its derivatives. An imbalance in NMFs and ceramides combined to an increase of proinflammatory lipids may participate in skin permeability barrier impairment, dehydration and inflammatory reaction to the sun. Our skin model also allowed the evaluation of an innovative ultraviolet/blue light (UV/BL) broad-spectrum sunscreen with a high sun protection factor (SPF50+). We found that using this sunscreen prior to SSR exposure could in part prevent SSR-induced alterations in NMFs and lipids in the skin ecosystem RHE model.

Prinsepia utilis Royle polysaccharides promote skin barrier repair through the Claudin family

BACKGROUND

Plant polysaccharides have various biological activities. However, few studies have been conducted on the skin barrier of Prinsepia utilis Royle polysaccharide extract (PURP).

MATERIALS AND METHODS

The proportions of polysaccharides, monosaccharides and proteins were determined by extracting polysaccharides from fruit meal using water. The healing rate was measured by cell scratch assays. SDS-damaged reconstructed human epidermal models, an acetone-ether-induced mouse model and an IL-4-induced cellular inflammation model were used to detect the effects of polysaccharides on the phenotype, HA, TEWL, and TEER, with further characterizations performed using QRT-PCR, Western blotting, immunofluorescence (IF) assays.

RESULTS

PURP contained 35.73% polysaccharides and 11.1% proteins. PURP promoted cell migration and increased skin thickness in a reconstructed human epidermis model. The TEWL significantly decreased, and the HA content significantly increased. PURP significantly increased the TEER and decreased the permeability of the SDS-damaged reconstructed human epidermis model. Claudin-3, Claudin-4, and Claudin-5 were significantly upregulated. IF and Western blot analysis revealed that the Claudin-4 level significantly increased after treatment with PURP. Claudin-1, Claudin-3, Claudin-4, and Claudin-5 gene expression and IF and immunohistochemical staining were significantly increased in mice treated with acetone-ether. PURP promoted the expression of Claudin-1, Claudin-3, Claudin-4, and Claudin-5 after treatment with 100 ng/mL IL-4. PURP also downregulated the expression of NO, IL6, TNFα and NFκB in Raw 264.7 cells and in a mouse model.

CONCLUSION

We hypothesize that PURP may repair the skin barrier by promoting the expression of the claudin family and can assist in skin therapy.

Dissolvable microneedles in the skin: Determination the impact of barrier disruption and dry skin on dissolution

Dissolvable microneedles (DMNs), fabricated from biocompatible materials that dissolve in both water and skin have gained popularity in dermatology. However, limited research exists on their application in compromised skin conditions. This study compares the hyaluronic acid-based DMNs penetration, formation of microchannels, dissolution, and diffusion kinetics in intact, barrier-disrupted (tape stripped), and dry (acetone-treated) porcine ear skin ex vivo. After DMNs application, comprehensive investigations including dermoscopy, stereomicroscope, skin hydration, transepidermal water loss (TEWL), optical coherence tomography (OCT), reflectance confocal laser scanning microscopy (RCLSM), confocal Raman micro-spectroscopy (CRM), two-photon tomography combined with fluorescence lifetime imaging (TPT-FLIM), histology, and scanning electron microscopy (SEM) were conducted. The 400 µm long DMNs successfully penetrated the skin to depths of ≈200 µm for dry skin and ≈200-290 µm for barrier-disrupted skin. Although DMNs fully inserted into all skin conditions, their dissolution rates were high in barrier-disrupted and low in dry skin, as observed through stereomicroscopy and TPT-FLIM. The dissolved polymer exhibited a more significant expansion in barrier-disrupted skin compared to intact skin, with the smallest increase observed in dry skin. Elevated TEWL and reduced skin hydration levels were evident in barrier-disrupted and dry skins compared to intact skin. OCT and RCLSM revealed noticeable skin indentation and pronounced microchannel areas, particularly in barrier-disrupted and dry skin. Additional confirmation of DMN effects on the skin and substance dissolution was obtained through histology, SEM, and CRM techniques. This study highlights the impact of skin condition on DMN effectiveness, emphasizing the importance of considering dissolvability and dissolution rates of needle materials, primarily composed of hyaluronic acid, for optimizing DMN-based drug delivery.

Indian Gooseberry and Barley Sprout Complex Prevent Oxidative Stress and Photoaging of the Skin in Ultraviolet B-Irradiated SHK-I Mice

This study investigated the protective effects of a complex of Indian gooseberry and barley sprout (IB complex) on oxidative stress and skin damage caused by ultraviolet B irradiation in SHK-I hairless mice. The study examined the impact of IB complex on skin hydration, wrinkle formation, and melanogenesis using enzyme-linked immunosorbent assay, real-time polymerase chain reaction, and western blot analysis. The IB complex reduced skin hydration loss and wrinkle formation, while also demonstrating enhanced antioxidant activities. The IB complex maintained skin hydration via upregulation of hyaluronic acid and ceramide synthesis, including the regulation of hyaluronic acid synthase, long-chain ceramide formation, dihydroceramide desaturase 1 activity, and type I collagen production. The IB complex prevented wrinkle formation via downregulating JNK and upregulating TGF-β pathways. Moreover, IB complex blocked melanin production via inhibition of protein kinase A, cAMP response element-binding protein, and microphthalmia-associated transcription factor pathways. These results suggest that IB complex is a potential agent to protect the skin against photodamage caused by exposure to UVB radiation. The research protocols underwent approval from the Institutional Animal Care and Use Committee of Kyung Hee University (KHGASP-21-577), ensuring compliance with ethical standards.

Development of an Emulgel for the Effective Treatment of Atopic Dermatitis: Biocompatibility and Clinical Investigation

Atopic dermatitis (AD) is a common dermatological disease affecting both children and adults. No drug-free emulgel has been developed and studied in vitro and in vivo for the treatment of AD. The aim of this study was to develop and assess the efficacy of a topical emulgel containing hyaluronic acid, glycerol, Calendula officinalis, Aloe vera, polyphenols and EGF for the concomitant treatment in patients with AD aged over 14. Objective skin barrier function parameters were included, such as transepidermal water loss (TEWL), skin temperature, pH, stratum corneum hydration, skin elasticity and erythema. The subjective opinion of the patients was determined including acceptability, absorption, comfort of use and tolerability, as well as the degree of improvement in patients' quality of life. We observed an improvement in the subjective parameters studied and statistically significant differences in the objective parameters. Specifically, we found an improvement in TEWL (p = 0.006), erythema (p = 0.008) and hydration (p < 0.001), parameters indicating an improvement in the epidermal barrier. One hundred per cent of patients were satisfied with the product. Therefore, these results suggest that the product may contribute to the treatment of AD.

Stratum Corneum Hydration Measurements with a Bluetooth Wireless Probe: A Real-Life Study at Home Compared to Measurements under Laboratory Conditions

INTRODUCTION

Non-invasive measurement of the stratum corneum hydration (SCH) with capacitance-based instrumentation is established in dermatological and cosmetic studies. We wanted to test the reliability of non-invasive self-measurements for SCH performed under real-life conditions by volunteers with a Bluetooth-based (wireless) probe Corneometer® (CM 825i) transmitting the data via a smartphone application to a central server. Probes and smartphones communicated using Bluetooth Low Energy. Data from the smartphone were securely transferred to a remote server in a different country with TLS encryption using HTTPS protocols. CM 825i values were correlated with the established CM 825 under laboratory conditions. The primary endpoint was the correlation of the two probes. Secondary endpoints were the coefficient of variation (CV) and delta values (before and after treatment).

METHODS

Eighteen healthy volunteers (f: 8; m: 10) participated in the prospective observational study. The real-world home use of the wireless CM 825i was performed before and after treatments with base cream DAC for 7 days.

RESULTS

Both instruments showed a significant and relevant correlation (p < 0.0001; Spearman coefficient of r = 0.8647). CM 825i and CM 825 differentiate significantly between normal and high SCH. Both devices showed comparable robustness in repeated measurements with a CV between 5.6% and 9.2%.

CONCLUSION

We could show a significant correlation between both devices and a comparable differentiation between low and high SCH and comparable CVs. The real-life use demonstrated adequate acquiring and transmitting of in vivo data to a smartphone and subsequently transmitting to the secure server with low numbers of missed transmissions (<0.2%) and missed measurements (<5%).

Oral Administration of Deer Bone Collagen Peptide Can Enhance the Skin Hydration Ability and Antioxidant Ability of Aging Mice Induced by D-Gal, and Regulate the Synthesis and Degradation of Collagen

Skin problems caused by aging have attracted much attention, and marine collagen peptides have been proved to improve these problems, while mammalian collagen peptides are rarely reported. In this study, fermented deer bone collagen peptide (FCP) and non-fermented deer bone collagen peptide (NCP) were extracted from fermented and non-fermented deer bone, respectively, and their peptide sequences and differential proteins were analyzed using LC-MS/MS technology. After they were applied to aging mice induced with D-gal, the skin hydration ability, antioxidant ability, collagen synthesis, and degradation ability of the mice were studied. The results show that FCP and NCP are mainly peptides that constitute type Ⅰ collagen, and their peptide segments are different. In vivo experiments show that FCP and NCP can improve the richness of collagen fibers in the skin of aging mice; improve the hydration ability of skin; promote the activity of antioxidant-related enzymes; and also show that through the TGF-β and MAPK pathways, the synthesis and degradation of collagen in skin are regulated. These results show that deer bone collagen peptide can improve skin problems caused by aging, promote skin hydration and antioxidant capacity of aging mice, and regulate collagen synthesis and degradation through the MAPK pathway.

Anti-Photodamage Effect of Agaricus blazei Murill Polysaccharide on UVB-Damaged HaCaT Cells

UVB radiation is known to induce photodamage to the skin, disrupt the skin barrier, elicit cutaneous inflammation, and accelerate the aging process. Agaricus blazei Murill (ABM) is an edible medicinal and nutritional fungus. One of its constituents, Agaricus blazei Murill polysaccharide (ABP), has been reported to exhibit antioxidant, anti-inflammatory, anti-tumor, and immunomodulatory effects, which suggests potential effects that protect against photodamage. In this study, a UVB-induced photodamage HaCaT model was established to investigate the potential reparative effects of ABP and its two constituents (A1 and A2). Firstly, two purified polysaccharides, A1 and A2, were obtained by DEAE-52 cellulose column chromatography, and their physical properties and chemical structures were studied. A1 and A2 exhibited a network-like microstructure, with molecular weights of 1.5 × 104 Da and 6.5 × 104 Da, respectively. The effects of A1 and A2 on cell proliferation, the mitochondrial membrane potential, and inflammatory factors were also explored. The results show that A1 and A2 significantly promoted cell proliferation, enhanced the mitochondrial membrane potential, suppressed the expression of inflammatory factors interleukin-1β (IL-1β), interleukin-8 (IL-8), interleukin-6 (IL-6), and tumor necrosis factor α (TNF-α), and increased the relative content of filaggrin (FLG) and aquaporin-3 (AQP3). The down-regulated JAK-STAT signaling pathway was found to play a role in the response to photodamage. These findings underscore the potential of ABP to ameliorate UVB-induced skin damage.

Anti-inflammatory, Antioxidative, and Moisturizing Effects of Oxyceros horridus Lour. Ethanol Extract in Human Keratinocytes via the p38 Signaling Pathway

Skin is the largest and outermost organ in the human body; it serves as a vital defense mechanism against various external threats. Therefore, it is crucial to maintain its health through protection against harmful substances and adequate moisture levels. This study investigates the anti-inflammatory, antioxidant, and moisturizing properties of Oxyceros horridus Lour. (Oh-EE) in human keratinocytes. Oh-EE demonstrates potent antioxidant activity and effectively protects against oxidative stress induced by external stimuli such as UVB radiation and H2O2. Additionally, it exhibits significant anti-inflammatory effects proven by its ability to downregulate the expression of pro-inflammatory cytokines, namely COX-2 and IL-6. The study also explores the involvement of the AP-1 pathway, highlighting the ability of Oh-EE to suppress the expression of p38 and its upstream regulator, MKK3/6, under UVB-induced conditions. Interestingly, Oh-EE can activate the AP-1 pathway in the absence of external triggers. Furthermore, Oh-EE enhances skin moisture by upregulating the expression of key genes involved in skin hydration, namely HAS3 and FLG. These findings underscore the potential of Oh-EE as a versatile ingredient in skincare formulations, providing a range of skin benefits. Further research is warranted to comprehensively understand the underlying mechanisms through which Oh-EE exerts its effects.

The Potential of Exercise on Lifestyle and Skin Function: Narrative Review

BACKGROUND

The skin is an important organ of the human body and has moisturizing and barrier functions. Factors such as sunlight and lifestyle significantly affect these skin functions, with sunlight being extremely damaging. The effects of lifestyle habits such as smoking, diet, and sleep have been studied extensively. It has been found that smoking increases the risk of wrinkles, while excessive fat and sugar intake leads to skin aging. Lack of sleep and stress are also dangerous for the skin's barrier function. In recent years, the impact of exercise habits on skin function has been a focus of study. Regular exercise is associated with increased blood flow to the skin, elevated skin temperature, and improved skin moisture. Furthermore, it has been shown to improve skin structure and rejuvenate its appearance, possibly through promoting mitochondrial biosynthesis and affecting hormone secretion. Further research is needed to understand the effects of different amounts and content of exercise on the skin.

OBJECTIVE

This study aims to briefly summarize the relationship between lifestyle and skin function and the mechanisms that have been elucidated so far and introduce the expected effects of exercise on skin function.

METHODS

We conducted a review of the literature using PubMed and Google Scholar repositories for relevant literature published between 2000 and 2022 with the following keywords: exercise, skin, and life habits.

RESULTS

Exercise augments the total spectrum power density of cutaneous blood perfusion by a factor of approximately 8, and vasodilation demonstrates an enhancement of approximately 1.5-fold. Regular exercise can also mitigate age-related skin changes by promoting mitochondrial biosynthesis. However, not all exercise impacts are positive; for instance, swimming in chlorinated pools may harm the skin barrier function. Hence, the exercise environment should be considered for its potential effects on the skin.

CONCLUSIONS

This review demonstrates that exercise can potentially enhance skin function retention.

Environmentally relevant concentrations of chemically complex shale gas wastewater led to reduced fitness of water fleas (Daphnia carinata): Multiple lines of evidence approach

Shale gas hydraulic fracturing generates flowback waters that pose a threat to aquatic organisms if released into the environment. In order to prevent adverse effects on aquatic ecosystems, multiple lines of evidence are needed to guide better decisions and management actions. This study employed a multi-disciplinary approach, combining direct toxicity assessment (DTA) on the water flea Daphnia carinata and LC-MS metabolomics analysis to determine the impact of a major ion salinity control (SC) and a cumulative flowback shale gas wastewater (SGW) from a well in the Beetaloo Sub-basin, Northern Territory, Australia. The exposures included a culture water control, simply further referred to as 'control', SC at 1% and 2% (v/v) and SGW at 0.125, 0.25, 0.5, 1% and 2% (v/v). The results showed that reproduction was significantly increased at SGW 0.5%, and significantly decreased when exposed to SC 2%. SGW 2% was found to be acutely toxic for the D. carinata (< 48-h). Second generation (F1) of D. carinata exposed to 0.125-1% SGW generally saw reduced activity in four oxidative biomarkers: glutathione S-transferase, lipid peroxidation, reactive oxygen species, and superoxide dismutase. At the metabolomics level, we observed significant changes in 103 metabolites in Daphnia exposed to both SGW and elevated salinity, in comparison to the control group. These changes indicate a range of metabolic disturbances induced by SGW and salinity, such as lipid metabolism, amino acid metabolism, nucleotide synthesis, energy production, and the biosynthesis of crucial molecules like hormones and pigments. These multiple lines of evidence approach not only highlights the complexities of SGW's impact on aquatic ecosystems but also underscores the importance of informed decision-making and management practices to safeguard the environment and its inhabitants.

Chiral Supramolecular Hydrogel Enhanced Transdermal Delivery of Sodium Aescinate to Modulate M1 Macrophage Polarization Against Lymphedema

Sodium aescinate (SA) shows great potential for treating lymphedema since it can regulate the expression of cytokines in M1 macrophages, however, it is commonly administered intravenously in clinical practice and often accompanied by severe toxic side effects and short metabolic cycles. Herein, SA-loaded chiral supramolecular hydrogels are prepared to prove the curative effects of SA on lymphedema and enhance its safety and transdermal transmission efficiency. In vitro studies demonstrate that SA- loaded chiral supramolecular hydrogels can modulate local immune responses by inhibiting M1 macrophage polarization. Typically, these chiral hydrogels can significantly increase the permeability of SA with good biocompatibility due to the high enantioselectivity between chiral gelators and stratum corneum and L-type hydrogels are found to have preferable drug penetration over D-type hydrogels. In vivo studies show that topical delivery of SA via chiral hydrogels results in dramatic therapeutic effects on lymphedema. Specifically, it can downregulate the level of inflammatory cytokines, reduce the development of fibrosis, and promote the regeneration of lymphatic vessels. This study initiates the use of SA for lymphedema treatment and for the creation of an effective chiral biological platform for improved topical administration.

Interaction between the microbiota and the skin barrier in aging skin: a comprehensive review

The interplay between the microbes and the skin barrier holds pivotal significance in skin health and aging. The skin and gut, both of which are critical immune and neuroendocrine system, harbor microbes that are kept in balance. Microbial shifts are seen with aging and may accelerate age-related skin changes. This comprehensive review investigates the intricate connection between microbe dynamics, skin barrier, and the aging process. The gut microbe plays essential roles in the human body, safeguarding the host, modulating metabolism, and shaping immunity. Aging can perturb the gut microbiome which in turn accentuates inflammaging by further promoting senescent cell accumulation and compromising the host's immune response. Skin microbiota diligently upholds the epidermal barrier, adeptly fending off pathogens. The aging skin encompasses alterations in the stratum corneum structure and lipid content, which negatively impact the skin's barrier function with decreased moisture retention and increased vulnerability to infection. Efficacious restoration of the skin barrier and dysbiosis with strategic integration of acidic cleansers, emollients with optimal lipid composition, antioxidants, and judicious photoprotection may be a proactive approach to aging. Furthermore, modulation of the gut-skin axis through probiotics, prebiotics, and postbiotics emerges as a promising avenue to enhance skin health as studies have substantiated their efficacy in enhancing hydration, reducing wrinkles, and fortifying barrier integrity. In summary, the intricate interplay between microbes and skin barrier function is intrinsically woven into the tapestry of aging. Sound understanding of these interactions, coupled with strategic interventions aimed at recalibrating the microbiota and barrier equilibrium, holds the potential to ameliorate skin aging. Further in-depth studies are necessary to better understand skin-aging and develop targeted strategies for successful aging.

Anti-aging formula protects skin from oxidative stress-induced senescence through the inhibition of CXCR2 expression

ETHNOPHARMACOLOGICAL RELEVANCE

The skin is affected by endogenous and exogenous factors, which are the intuitive consequence expression of aging. Aging not only affects the aesthetics of the skin but also causes the decline of skin functions, leading to many skin diseases and even skin cancer. Anti-aging formula (AAF) has various biological effects such as antioxidants, regulation of intestinal flora metabolism, anti-aging, and memory improvement. However, it is not clarified whether it could be anti-aging of the skin and the anti-aging mechanism.

AIM OF THE STUDY

This study aimed to investigate whether AAF could prevent skin from oxidative stress-induced senescence and explore the underlying molecular mechanisms.

MATERIALS AND METHODS

A mouse skin oxidative stress aging model was established based on ultraviolet (UV) irradiation, and parameters such as skin water content, melanogenesis, wrinkle production, pathological changes, and aging marker proteins were measured to elucidate whether AAF has an anti-aging effect on the skin. Subsequently, transcriptome sequencing (RNA-Seq) was used to identify target genes. An in vitro cellular senescence model was established to assess the role of AAF against cellular oxidative stress senescence by detecting senescence-related markers, while the specific mechanism of action of AAF in delaying skin senescence was elucidated by silencing or overexpression of targets.

RESULTS

In vivo experiments demonstrated that AAF significantly increased skin water content, reduced skin sensitivity and melanin content, slowed wrinkles, improved UV-induced epidermal thickening, increased collagen fiber content, improved elastic fiber morphology, and reduced the expression of senescence proteins P21 and P16 in skin tissues. The RNA-Seq results identified chemokine receptor 2 (CXCR2) as one of the potential targets for delaying skin senescence. In vitro experiments showed that AAF markedly improved the aging phenotype, and knockdown or overexpression experiments verified the essential role of CXCR2 in the skin senescence process. Mechanistic studies suggested that AAF inhibited the P38/P53 pathway by reducing CXCR2 expression, which improved the aging phenotype, reduced oxidative damage, and ultimately delayed cellular senescence.

CONCLUSION

The results reveal that AAF protects skin from oxidative stress-induced senescence by regulating the expression of critical target CXCR2, reducing P38 protein phosphorylation, and inhibiting P53 pathway activation. These discoveries implicate the potential of AAF in the protection of skin aging disease.

Research on the anti-aging efficacy of fermented lysate VHProbi® MixA as the functional skincare ingredient

AIMS

This study aimed to investigate the efficacy of a cream containing VHProbi® MixA for improving skin aging.

METHODS AND RESULTS

In vitro studies demonstrated that the lysate produced from Lacticaseibacillus paracasei E12 (E12) exhibited immunoregulatory effects in a 3D skin model, with significant reductions in levels of interleukin (IL)-1α, IL-1β, and IL-8 (P < 0.05) compared with the control group. In addition, the lysate of E12 mitigated the hydrogen peroxide-induced mortality of 3D skin cells and enhanced the transepithelial electrical resistance to show significant differences in comparison with control (P < 0.05), suggesting favorable antioxidant effects. The antioxidant capacity of the lysate of E12 was also confirmed using the Caenorhabditis elegans N2 model. C. elegans N2 fed the E12 strain showed a significantly higher % survival than those fed Escherichia coli OP50 (P < 0.05). Subsequently, VHProbi® MixA was formulated using the fermented lysates of E12, Lactiplantibacillus plantarum E15, and Limosilactobacillus reuteri E18. In a clinical study to ascertain if a cream containing VHProbi® MixA could improve the skin aging trends, participants were asked to use the investigational products for 60 days, and six indicators, transepidermal water loss (TEWL), hydration, elasticity, wrinkles, skin texture (roughness), and pores were measured at baseline and the endpoint of the study. A self-evaluation questionnaire analysis was also provided. TEWL, wrinkles, skin texture, and thickness of pores decreased significantly after treatment with the cream for 60 days (P < 0.01), whereas hydration and elasticity increased significantly (P < 0.01), in comparison to the baseline measurements.

CONCLUSIONS

We hypothesize that the use of the cream containing VHProbi® MixA could be favorable for skin anti-aging management.

Hacking the International Nomenclature of Cosmetic Ingredients List- How to Read Ingredients in Cosmetic Products and What Is Important for a Dermatologist to Know?

Skin specialists and practitioners are commonly requested to recommend on cosmetic products to improve skin appearance and address certain "non-medical" concerns. During residency and further education, dermatologists rarely expand their knowledge regarding cosmetic ingredients, except if they are a cause of medical condition or disease, such as contact dermatitis. This review provides guidelines to the INCI list structure, together with basic principles of cosmetic products formulation.

Incidence of radiodermatitis and factors associated with its severity in women with breast cancer: a cohort study

BACKGROUND

One of the main adverse reactions of adjuvant radiotherapy for breast cancer is radiodermatitis.

OBJECTIVE

To assess the incidence of radiodermatitis in women with breast cancer, identify factors associated with its severity and determine the time at which this event occurs.

METHODS

Prospective cohort study in 113 women with breast cancer who were evaluated before radiotherapy and at every fifth session until the end of treatment. Logistic regression and Cox proportional regression model were used for the assessment of risk factors; P values < 0.05 were considered significant.

RESULTS

The incidence rate of radiodermatitis was 98.2% and it was demonstrated that for each additional point of the Body Mass Index (BMI), the chance of occurrence of grades II to IV radiodermatitis increases by 14% (OR=1.14 [95% CI 1.04-1.26]; p=0.004) and statin use increases the risk of more severe skin lesions by four-fold (OR=4.27 [95% CI 1.11-16.42]; p=0.035). The exclusive use of hydrogel for skin hydration was an independent factor in delaying the onset of radiodermatitis (HR=0.55 [95% CI 0.36-0.82]; p=0.004).

STUDY LIMITATIONS

The main limitation of this study was its external validity. The identified factors should be considered for services and populations similar to those in this study.

CONCLUSIONS

There was a high incidence of radiodermatitis and its severity was related to higher BMI, statin use; there was a protective effect of hydrogel use.

Squalene Peroxidation and Biophysical Parameters in Acne-Prone Skin: A Pilot "In Vivo" Study

Nowadays, acne vulgaris therapies are often unsuccessful. One of the responsible factors for the formation of comedones and inflammatory lesions could be the peroxidation of squalene, a hydrocarbon representing one of the major components of human sebum. This peroxidation is increased by solar irradiation. The purpose of this work was to set up an in vivo method for the extraction and quantification of squalene from acne skin and to correlate the results with biophysical skin parameters such as sebum amount, protein content and TEWL. Healthy volunteers were used as control. The results obtained demonstrated that acne-prone skin had a major quantity of squalene, and, in the stratum corneum area, its peroxide form is present. Moreover, Spearman's rank correlation showed a positive correlation between sebum content and peroxide squalene and between porphyrin intensity and peroxide squalene.

Effects of regular exercise on skin moisturizing function in adults

Among lifestyle habits, the effect of exercise on skin moisturizing function has not been studied. Therefore, we aimed to clarify the effect of regular exercise on skin moisturizing function. The participants were 30-64 years old with no history of skin diseases and no exercise habits at the start of the study. The intervention group (n=9) continued to exercise at least 600 Mets/week for 8 weeks, while the control group (n=28) followed conventional lifestyle habits for 8 weeks. Questionnaires regarding lifestyle habits were administered at the beginning and after 8 weeks, and skin moisturizing function (stratum corneum hydration: SC hydration, Trans-Epidermal Water Loss: TEWL) was measured. Analysis of covariance was performed using sex, age, and measurements at the start of the study as covariates. Analysis of covariance showed that after 8 weeks of "moderate" or "higher" exercise, there was a trend toward higher SC hydration in the intervention group compared to that in the control group (p=0.083, η2=0.10). There was no difference in TEWL after 8 weeks (p=0.864, η2=0.00). These results suggest that regular exercise may help maintain and improve skin moisturizing function.

Characterization of Epidermal Function in Individuals with Primary Cutaneous Amyloidosis

Purpose

To compare epidermal biophysical properties, indicators of epidermal function, in individuals with and without primary cutaneous amyloidosis (PCA).

Patients and Methods

This study incorporated 189 patients with PCA and 166 healthy individuals. The GPSkin Barrier was employed to measure transepidermal water loss (TEWL) rates and hydration levels of the stratum corneum. The Sebumeter and the Skin pH Meter were utilized to determine the skin surface's sebum content and pH, respectively. The severity of pruritus in participants was evaluated using the visual analog scale (VAS).

Results

Compared to the control group without PCA, individuals with PCA displayed a notable increase in skin surface pH and TEWL and a decrease in the hydration levels of the stratum corneum (p<0.0001 for all parameters). Additionally, the sebum content was markedly lower in those with PCA than in the controls (p<0.0001). Of particular note, both TEWL and skin surface pH at the lesion sites on the back and the shin were more elevated in lichenoid amyloidosis (LA) and in macular amyloidosis (MA), whereas hydration levels of the stratum corneum and sebum levels were diminished in LA compared to MA (p<0.05). In conclusion, both hydration levels of the stratum corneum and sebum content exhibited an inverse relationship with pruritus severity, whereas TEWL and skin surface pH demonstrated a positive correlation with pruritus intensity.

Conclusion

The function of the epidermis is compromised in individuals diagnosed with PCA. However, the mechanisms underlying these changes await further investigation.

Research Progress in Skin Aging, Metabolism, and Related Products

In recent years, skin aging has received increasing attention. Many factors affect skin aging, and research has shown that metabolism plays a vital role in skin aging, but there needs to be a more systematic review. This article reviews the interaction between skin metabolism and aging from the perspectives of glucose, protein, and lipid metabolism and explores relevant strategies for skin metabolism regulation. We found that skin aging affects the metabolism of three major substances, which are glucose, protein, and lipids, and the metabolism of the three major substances in the skin also affects the process of skin aging. Some drugs or compounds can regulate the metabolic disorders mentioned above to exert anti-aging effects. Currently, there are a variety of products, but most of them focus on improving skin collagen levels. Skin aging is closely related to metabolism, and they interact with each other. Regulating specific metabolic disorders in the skin is an important anti-aging strategy. Research and development have focused on improving collagen levels, while the regulation of other skin glycosylation and lipid disorders including key membrane or cytoskeleton proteins is relatively rare. Further research and development are expected.

Carbon dioxide foam bubbles enhance skin penetration through the stratum corneum layer with mechanical mechanism

Topical skin formulations often include penetration enhancers that interact with the outer stratum corneum (SC) layer to chemically enhance diffusion. Alternatively, penetration can be mechanically enhanced with simple rubbing in the presence of solid particles sometimes included to exfoliate the top layers of the SC. Our goal was to evaluate micron-sized carbon dioxide bubbles included in a foamed moisturizing formulation as a mechanical penetration enhancement strategy. We show that moisturizing foam bubbles cause an increase in SC formulation penetration using both mechanical and spectroscopic characterization. Our results suggest viscous liquid film drainage between coalescing gaseous bubbles creates local regions of increased hydrodynamic pressure in the foam liquid layer adjacent to the SC surface that enhances treatment penetration. An SC molecular diffusion model is used to rationalize the observed behavior. The findings indicate marked increased levels of treatment concentration in the SC at 2 h and that persists to 18 h after exposure, far exceeding non-foamed treatments. The study suggests an alternate strategy for increasing formulation penetration with a non-chemical mechanism.

Prediction of Food Sensitization in Children with Atopic Dermatitis Based on Disease Severity and Epidermal Layer Impairment

INTRODUCTION

Atopic dermatitis (AD) is characterized by an impaired epidermal barrier, which could be associated with sensitization to food allergens (FAs) and/or inhaled allergens and contribute to the severity of AD. However, no clinical guidance has been established for evaluations of food sensitization (FS) in AD patients. This study investigated how AD severity and epidermal barrier impairment are associated with FS and factors that can predict FS in children with AD.

METHODS

This cross-sectional study included 100 children (12-60 months) diagnosed with AD. AD severity was determined using the Scoring Atopic Dermatitis (SCORAD) index. FS was evaluated by measuring serum-specific IgE antibodies against 31 FAs using an immunoblotting method. Epidermal barrier impairment was assessed by measuring transepidermal water loss (TEWL) and stratum corneum hydration (SCH) levels.

RESULTS

90% of participants were sensitized to at least one tested FA, with cow's milk, egg white, beef, almond, egg yolk, and peanut being the most common. Children with moderate-severe AD had lower SCH levels than those with mild AD. Children with AD who were sensitized to >10 FAs had significantly higher TEWL and lower SCH levels, compared with those sensitized to 1-4 FAs and 5-10 FAs. The SCORAD score and SCH level in lesional skin provided moderately predictive value for sensitization to FAs in children with AD.

CONCLUSION

FS is common in children with AD and closely associate with AD severity as well as epidermal barrier impairment. Evaluations of FS should be considered for children with moderate to severe AD and/or low SCH levels.

Altered structure indicating reduced barrier function of lesional compared to non-lesional psoriatic skin-A non-invasive in vivo study of the human stratum corneum with confocal Raman micro-spectroscopy

Psoriasis, one of the most common skin diseases affecting roughly 2%-3% of the world population, is associated with a reduced skin barrier function (SBF) that might play an important role in its pathophysiology. The SBF is provided primarily by the stratum corneum (SC) of the skin. Previous studies have revealed a higher trans-epidermal water loss, lower hydration, abnormal concentration and composition of intercellular lipids, as well as alterations in secondary keratin structure in the psoriatic SC. We compared on molecular level lesional psoriatic skin (LPS) with non-lesional psoriatic skin (nLPS) from 19 patients non-invasively in vivo, using confocal Raman micro-spectroscopy. By analysing the corresponding Raman spectra, we determined SBF-defining parameters of the SC depth-dependently. Our results revealed a lower total lipid concentration, a shift of lamellar lipid organisation towards more gauche-conformers and an increase of the less dense hexagonal lateral packing of the intercellular lipids in LPS. Furthermore, we observed lower natural moisturising factor concentration, lower total water as well as a strong tendency towards less strongly bound and more weakly bound water molecules in LPS. Finally, we detected a less stable secondary keratin structure with increased β-sheets, in contrast to the tertiary structure, showing a higher degree of folded keratin in LPS. These findings clearly suggest structural differences indicating a reduced SBF in LPS, and are discussed in juxtaposition to preceding outcomes for psoriatic and healthy skin. Understanding the alterations of the psoriatic SC provides insights into the exact pathophysiology of psoriasis and paves the way for optimal future treatments.

The Skin Barrier and Moisturization: Function, Disruption, and Mechanisms of Repair

BACKGROUND

The anatomic layers of the skin are well-defined, and a functional model of the skin barrier has recently been described. Barrier disruption plays a key role in several skin conditions, and moisturization is recommended as an initial treatment in conditions such as atopic dermatitis. This review aimed to analyze the skin barrier in the context of the function model, with a focus on the mechanisms by which moisturizers support each of the functional layers of the skin barrier to promote homeostasis and repair.

SUMMARY

The skin barrier is comprised of four interdependent layers - physical, chemical, microbiologic, and immunologic - which maintain barrier structure and function. Moisturizers target disruption affecting each of these four layers through several mechanisms and were shown to improve transepidermal water loss in several studies. Occlusives, humectants, and emollients occlude the surface of the stratum corneum (SC), draw water from the dermis into the epidermis, and assimilate into the SC, respectively, in order to strengthen the physical skin barrier. Acidic moisturizers bolster the chemical skin barrier by supporting optimal enzymatic function, increasing ceramide production, and facilitating ideal conditions for commensal microorganisms. Regular moisturization may strengthen the immunologic skin barrier by reducing permeability and subsequent allergen penetration and sensitization.

KEY MESSAGES

The physical, chemical, microbiologic, and immunologic layers of the skin barrier are each uniquely impacted in states of skin barrier disruption. Moisturizers target each of the layers of the skin barrier to maintain homeostasis and facilitate repair.

Association of Epidermal Biophysical Properties with Obesity and Its Implications

BACKGROUND

Obesity is a condition defined by an excess amount of body fat, with body mass index (BMI) of 30 and higher. It is associated with a number of other medical conditions, including insulin resistance, diabetes mellitus, and cardiovascular diseases, as well as dyslipidemia, and it is also associated with several cutaneous disorders such as atopic dermatitis, psoriasis, intertriginous dermatitis, acanthosis nigricans and skin infections.

SUMMARY

Evidence suggests a link between obesity and epidermal dysfunction. Generally, individuals with obesity display higher transepidermal water loss rate and lower stratum corneum hydration levels, although no association of obesity with epidermal dysfunction has been documented. Results of skin surface pH are controversial. But study demonstrated a positive correlation of BMI with skin surface pH on both the forearm and the shin in males, suggesting that the changes in epidermal function vary with gender in individuals with obesity.

KEY MESSAGES

This review summarizes the association between obesity and epidermal function, and discusses possible underlying mechanisms. Individuals with obesity exhibit poor epidermal permeability barrier and lower stratum corneum hydration levels. Because of the pathogenic role of compromised epidermal function in inflammation, which is also linked to obesity, improvement in epidermal function could benefit individuals with obesity, particularly those with abnormalities in epidermal function.

Skin and Artificial Skin Models in Electrical Sensing Applications

Skin electrical properties play a significant role in recording biopotentials by using electrophysiological sensors. To test and evaluate sensor systems, it is commonly accepted to employ artificial skin models due to complications associated with testing on living tissues. The first goal of this Review is to provide a systematic understanding of the relation between skin structure and skin electrochemical behavior at an appropriate depth for electrophysiological sensing applications through a focus on skin structure, electrochemical properties of skin, and theoretical models (equivalent circuits) representing skin electrochemical behavior. The second goal is to review artificial skin models mimicking the electrochemical properties of skin and to give suggestions for future studies on relevant skin models based on a comparison between the behavior of skin and that of artificial skin models. The Review aims to help the reader to analyze the relation between the structure, elements of the equivalent circuits, and the resulting impedance data for both skin and artificial skin models.

A Novel Multi-Component Formulation Reduces Inflammation In Vitro and Clinically Lessens the Symptoms of Chronic Eczematous Skin

Long-term treatments for inflammatory skin diseases like atopic dermatitis or eczema can cause adverse effects. Super Protein Multifunction (SPM) was investigated as a potential treatment for managing skin inflammation by monitoring the expression of pro-inflammatory cytokines induced using LPS and poly(I:C)/TNFα in HaCaT keratinocytes and Hs27 fibroblasts as measured via RT-PCR. SPM solution was also assessed for its effect on cytokine release, measured using ELISA, in a UVB-irradiated 3D human skin model. To evaluate the efficiency of SPM, 20 patients with mild eczematous skin were randomized to receive SPM or vehicle twice a day for three weeks in a double-blind controlled trial. In vitro studies showed SPM inhibited inflammation-induced IL-1β, IL-6, IL-33, IL-1α, TSLP, and TNFα expression or release. In the clinical study, the SPM group showed significant improvements in the IGA, PA, and DLQI scores compared to the vehicle group. Neither group showed significant differences in VAS (pruritus). Histological analysis showed reduced stratum corneum thickness and inflammatory cell infiltration. The results suggest that SPM may reduce inflammation in individuals with chronic eczematous skin.

Poroelastic behavior and water permeability of human skin at the nanoscale

Topical skin care products and hydrating compositions (moisturizers or injectable fillers) have been used for years to improve the appearance of, for example facial wrinkles, or to increase "plumpness". Most of the studies have addressed these changes based on the overall mechanical changes associated with an increase in hydration state. However, little is known about the water mobility contribution to these changes as well as the consequences to the specific skin layers. This is important as the biophysical properties and the biochemical composition of normal stratum corneum, epithelium, and dermis vary tremendously from one another. Our current studies and results reported here have focused on a novel approach (dynamic atomic force microscopy-based nanoindentation) to quantify biophysical characteristics of individual layers of ex vivo human skin. We have discovered that our new methods are highly sensitive to the mechanical properties of individual skin layers, as well as their hydration properties. Furthermore, our methods can assess the ability of these individual layers to respond to both compressive and shear deformations. In addition, since human skin is mechanically loaded over a wide range of deformation rates (frequencies), we studied the biophysical properties of skin over a wide frequency range. The poroelasticity model used helps to quantify the hydraulic permeability of the skin layers, providing an innovative method to evaluate and interpret the impact of hydrating compositions on water mobility of these different skin layers.