The Pathobiology of Skin Aging: New Insights into an Old Dilemma

Endocrine Controls of Skin Aging

Skin is the largest organ of the human body and undergoes both intrinsic (chronological) and extrinsic aging. While intrinsic skin aging is driven by genetic and epigenetic factors, extrinsic aging is mediated by external threats such as UV irradiation or fine particular matters, the sum of which is referred to as exposome. The clinical manifestations and biochemical changes are different between intrinsic and extrinsic skin aging, albeit overlapping features exist, eg, increased generation of reactive oxygen species, extracellular matrix degradation, telomere shortening, increased lipid peroxidation, or DNA damage. As skin is a prominent target for many hormones, the molecular and biochemical processes underlying intrinsic and extrinsic skin aging are under tight control of classical neuroendocrine axes. However, skin is also an endocrine organ itself, including the hair follicle, a fully functional neuroendocrine "miniorgan." Here we review pivotal hormones controlling human skin aging focusing on IGF-1, a key fibroblast-derived orchestrator of skin aging, of GH, estrogens, retinoids, and melatonin. The emerging roles of additional endocrine players, ie, α-melanocyte-stimulating hormone, a central player of the hypothalamic-pituitary-adrenal axis; members of the hypothalamic-pituitary-thyroid axis; oxytocin, endocannabinoids, and peroxisome proliferator-activated receptor modulators, are also reviewed. Until now, only a limited number of these hormones, mainly topical retinoids and estrogens, have found their way into clinical practice as anti-skin aging compounds. Further research into the biological properties of endocrine players or its derivatives may offer the development of novel senotherapeutics for the treatment and prevention of skin aging.

Bioactives for Estrogen-Deficient Skin: Topical and Oral Supplement Clinical Studies. A Narrative Review

Bioactive compound applications by topical or oral administration have gained increased utilization/awareness in providing health benefits particularly due to changes in hormone levels and aging, especially in women with the decline and loss of estrogens. This narrative review focuses on the bioactive compounds such as the phytoestrogens that have estrogenic properties for improving skin health. Notably, phytoestrogens bind and/or activate estrogen beta receptors, which are abundant in skin layers to improve dermal health. This review presents: (a) skin characteristics with aging in women, (b) changes in hormone levels with aging in women (especially with estrogen deficiency), (c) the characteristics of phytoestrogens and other bioactive compounds, (d) topical and oral clinical studies of bioactive compounds (phytoestrogens) as antiaging treatment(s) for estrogen-deficient skin (during peri- and postmenopause), and (e) the advantages of treating the skin from the outside to inside by traditional topical therapies and treating the skin from the inside to the outside by nutraceutical supplementation, which represents a relatively new innovation of increasing popularity. While this is a growing area of research with promising results, more investigations are needed to understand the mechanism(s) of how combination ingredient formulations work to improve skin health and slow down the advancement of the aging process.

Synthetic and Natural Agents Targeting Advanced Glycation End-Products for Skin Anti-Aging: A Comprehensive Review of Experimental and Clinical Studies

Advanced glycation end-products (AGEs) cause blood vessel damage and induce diabetic complications in various organs, such as the eyes, kidneys, nerves, and skin. As glycation stress causes aesthetic, physical, and functional changes in the skin, glycation-targeting skin anti-aging strategies are attracting attention in cosmetology and dermatology. The primary goal of this review is to understand the significance of glycation-induced skin aging and to examine the therapeutic potential of glycation-targeting strategies. This study covers experimental and clinical studies exploring various interventions to attenuate glycation-induced skin aging. Glycation stress decreases the viability of cells in culture media, the cell-mediated contraction of collagen lattices in reconstructed skin models, and the expression of fibrillin-1 at the dermo-epidermal junction in the skin explants. It also increases cross-links in tail tendon collagen in animals, prolonging its breakdown time. However, these changes are attenuated by several synthetic and natural agents. Animal and clinical studies have shown that dietary or topical administration of agents with antiglycation or antioxidant activity can attenuate changes in AGE levels (measured by skin autofluorescence) and skin aging parameters (e.g., skin color, wrinkles, elasticity, hydration, dermal density) induced by chronological aging, diabetes, high-carbohydrate diets, ultraviolet radiation, or oxidative stress. Therefore, the accumulating experimental and clinical evidence supports that dietary supplements or topical formulations containing one or more synthetic and natural antiglycation agents may help mitigate skin aging induced by AGEs.

Skin Protection Effects of Lactobacillus paragasseri HN910 Lysate and the Role of Alanine

Skin aging is influenced by structural alterations, oxidative stress, inflammation, and microbiome changes, and a comprehensive approach to addressing these factors may be effective for mitigating skin aging. This study evaluates the multifaceted anti-aging effects of heat-killed (HK-HN910) and lysed (LS-HN910) forms of Lactobacillus paragasseri HN910. Protective effects on cell viability, cell permeability, nitric oxide (NO) production, and skin anti-aging gene expression for both HK-HN910 and LS-HN910 were observed. Both forms significantly enhanced tight junction (TJ) protein zonula occludens- 1 (ZO- 1) and antioxidant enzyme glutathione peroxidase (GPx) gene expression, while significantly downregulating that of senescence-associated secretory phenotype pro-inflammatory cytokines interleukin (IL)- 1α, IL- 1β, IL- 6, IL- 8, and tumor necrosis factor-alpha (TNFα). LS-HN910 showed significantly greater upregulation of ZO- 1 and GPx and greater downregulation of IL- 1β and TNFα expression compared to HK-HN910. Cell wall component D-alanine (D-Ala) was released in higher amounts in LS-HN910 than in HK-HN910 and demonstrated anti-aging effects. D-Ala upregulated gene expression of skin barrier ZO- 1, claudin- 1 (Cla- 1), occludin (OCC), filaggrin (FLG), and sphingomyelin phosphodiesterase 2 (SMPD2) and antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and GPx, while downregulating IL- 1α, IL- 1β, IL- 6, IL- 8, and TNFα. LS-HN910 treatment clinically revealed improvements in anti-aging parameters, including transepidermal water loss, skin water contents, sebum levels, dermal density, eye wrinkle index, skin pH, brightness, and microbiota composition, with a significant increase in Rhodococcus abundance. These findings indicate that LS-HN910, containing released D-Ala, is a promising cosmeceutical for preventing skin aging by enhancing the skin barrier, promoting oxidative defense, modulating inflammatory responses, and influencing skin microbiota.

Age-related meningeal extracellular matrix remodeling compromises CNS lymphatic function

Efficient clearance of central nervous system (CNS) waste proteins and appropriate immune surveillance is essential for brain health. These processes are facilitated by lymphatic networks present in the meninges that drain cerebrospinal fluid (CSF). Age-related impairments to meningeal lymphatic drainage contribute to CNS waste accumulation and immune dysfunction, yet the underlying mechanisms remain poorly understood. Here, we identify extracellular matrix (ECM) remodeling in the aged dura as a key driver of CSF clearance deficits, demonstrating that peri-lymphatic collagen accumulation disrupts lymphatic function. Exploring immune-derived factors contributing to this ECM remodeling, we identify transforming growth factor beta 1 (TGFβ1) as a major regulator using primary human dural fibroblasts. Using a novel mouse model with constitutively active TGFβ receptor 1 (TGFβR1) signaling in dural fibroblasts, we show that excessive peri-lymphatic collagen deposition impairs meningeal lymphatic drainage and alters meningeal immunity. Mechanistically, we reveal that ECM-associated matrix stiffness disrupts lymphatic junction integrity and impairs lymphangiogenesis in human lymphatic endothelial cells. These findings establish dural immune cell and fibroblast-mediated ECM remodeling as a critical regulator of CSF clearance and highlight it as a potential therapeutic target for restoring brain waste clearance in aging.

Exploring melatonin's signalling pathways in the protection against age-related skin deterioration

Melatonin, renowned for regulating sleep-wake cycles, also exhibits notable anti-aging properties for the skin. Synthesized in the pineal gland and various tissues including the skin, melatonin's efficacy arises from its capacity to combat oxidative stress and shield the skin from ultraviolet (UV)-induced damage. Moreover, it curbs melanin production, thereby potentially ameliorating hyperpigmentation. The presence of melatonin receptors in diverse skin cell types and its documented ability to enhance skin tone, hydration, and texture upon topical administration underscores its promise as an anti-aging agent. Melatonin's protective effects likely emanate from its multifaceted characteristics, encompassing antioxidant, anti-inflammatory, and immunomodulatory functions, as well as its influence on collagen synthesis and mitochondrial activity. Chronic inflammation and oxidative stress initiate a detrimental feedback loop. Reactive oxygen species (ROS), notorious for damaging cellular structures, provoke immune responses by oxidizing vital molecules and activating signaling proteins. This triggers heightened expression of inflammatory genes, perpetuating the cycle. Such dysregulation significantly compromises the body's resilience against infections and other health adversities. This study embarks on an exploration of the fundamental signaling pathways implicated in skin aging. Furthermore, it delves into the therapeutic potential of melatonin and its anti-aging attributes within the realm of skin health.

SPRY1 regulates macrophage M1 polarization in skin aging and melanoma prognosis

INTRODUCTION

Skin aging is a complex, multifactorial process involving cellular damage, inflammation, and increased susceptibility to diseases. Despite its importance, the role of SPRY1 in skin aging remains poorly understood. This study aims to investigate the function of SPRY1 in skin aging, particularly its impact on macrophage M1 polarization, and explore its potential as a therapeutic target for mitigating skin aging and melanoma.

METHODS

Bioinformatics analyses were performed using datasets from the GTEx and GEO databases, alongside in vitro cellular experiments. These included Weighted Gene Co-expression Network Analysis (WGCNA), single-cell sequencing, and various cellular assays in RAW264.7 murine monocyte/macrophage leukemia cells and NIH/3T3 mouse skin fibroblasts. The assays comprised gene transfection, Cell Counting Kit-8 (CCK-8) assays, quantitative real-time PCR (qRT-PCR), and measurements of reactive oxygen species (ROS) and superoxide dismutase (SOD) activity.

RESULTS

SPRY1 was identified as a key gene within modules linked to skin aging. Single-cell sequencing revealed its enrichment in macrophages and keratinocytes. Knockdown of SPRY1 in RAW264.7 cells resulted in a shift from M1 to M2 macrophage polarization, reduced oxidative stress, and decreased expression of inflammatory markers. In NIH/3T3 cells, SPRY1 knockdown reduced cell viability and lowered the expression of inflammatory genes. Additionally, SPRY1 expression was downregulated in melanoma, and its reduced levels were associated with poorer survival outcomes.

CONCLUSIONS

SPRY1 accelerates skin aging by promoting macrophage M1 polarization and may serve as a promising therapeutic target. Future research should focus on in vivo validation and further exploration of its regulatory networks to develop novel treatments.

Streptococcus thermophilus CNCM I-5570 lysate counteracts the aging process in human dermal fibroblast cells by neutralizing harmful free radicals and impacting antioxidant and anti-inflammatory pathways, thus restoring their physiological functions

Previous studies have highlighted the in vitro and in vivo anti-aging potential of Streptococcus thermophilus prompting us to investigate the biomolecular mechanisms underlying its effects. We evaluated the reparative ability of S. thermophilus lysate in a hydrogen peroxide (H2O2)-induced senescence model of human dermal fibroblasts (HDFs). Cell proliferation, cell number, and senescence level were evaluated by IncuCyte® Live Cell Imager system, trypan blue dye exclusion test and β-galactosidase activity, respectively. We analyzed p21, prolyl 4-hydroxylase A1, intracellular collagen I, nuclear factor E2-related factor 2 (Nrf2), nuclear factor kappa B (NF-κB) and heme oxygenase-1 expression through western blot. Extracellular levels of collagen I, interleukin-1β, and IL-6 were assessed by ELISA. The oxidative stress markers were assayed using standard methods. The direct antioxidant activity of probiotic was quantified using multiple techniques. The presence of antioxidant genes in probiotic was detected via PCR assay. Probiotic lysate exposure increased the proliferation rate, counteracted the aging by reducing β-galactosidase activity and p21 levels, promoted collagen I synthesis and neutralized oxidative stress by activating Nrf2. The probiotic lysate inhibited the NF-κB pathway with pro-inflammatory marker downregulation. Notably, we revealed that probiotic exhibited strong free radical scavenging ability, iron-chelating properties, and significant ferric reducing power in a concentration-dependent manner. We identified seven genes with antioxidant function in its genome. Our results show that S. thermophilus lysate is efficacious in suppressing the biomolecular events associated with H2O2-induced cellular aging, thus supporting the reparative action of S. thermophilus, helpful in treating skin aging.

OS-01 Peptide Topical Formulation Improves Skin Barrier Function and Reduces Systemic Inflammation Markers: A Pilot 12-Week Clinical Trial

OBJECTIVE

As the body's largest organ, the skin plays a crucial role in defending against external stressors. Skin characteristics change with age, decreasing skin barrier integrity and compromising skin and body health. This study aimed to investigate the potential of a topical formulation containing OS-01 (a.k.a. Peptide 14), a senotherapeutic peptide, to counteract age-related skin changes and their systemic consequences.

METHODS

A randomized, double-blinded clinical trial involving 60 female volunteers aged 60-90 was conducted over 12 weeks. Participants received either an OS-01 topical formulation or a commercially available moisturizer control formulation. Skin parameters, subjective perceptions, and circulating cytokine levels were assessed. Skin instrumental analysis included transepidermal water loss (TEWL), skin hydration, and pH measurements.

RESULTS

Participants treated with the OS-01 topical formulation displayed significantly improved skin barrier function and hydration compared to the control group. Participant perceptions aligned with objective findings: after 12 weeks, 70% of participants in the OS-01 group noticed an improvement in general skin appearance versus 42% for the control group. The systemic levels of proinflammatory cytokines tended to normalize, with a significant decrease in IL-8 in the blood analysis of participants from the OS-01 group. On the other hand, the control group demonstrated an increase in a few circulating cytokines, particularly TNF-ɑ and IFN-γ. Moreover, GlycanAge analysis measuring participants' biological age suggested the slowing of systemic aging in the group treated with the OS-01 topical formulation.

CONCLUSION

The study suggests that the OS-01 formulation can impact skin health by improving the skin barrier function, potentially influencing systemic inflammation and biological age. In conclusion, the study supports that targeting skin health may contribute to better longevity outcomes, underscoring the skin's pivotal role in systemic aging and supporting an integrated approach to health management.

Machine learning methods for determining skin age: A systematic review

AIM

This systematic review explores how machine learning is used in determining skin aging, aiming to evaluate accuracy, limitations, and gaps in the current literature.

MATERIALS AND METHODS

OVID Embase, OVID Medline, IEEE Xplore, and ACM Digitial Library were searched from inception to March 16, 2024.

RESULTS

A total of 1467 non-duplicate articles were screened, and 27 were ultimately included in the systematic review. The machine learning models exhibited a range of accuracies from a mean absolute error of 2.30-8.16 years. The most common approach was full facial image analysis, followed by non-image-based studies utilizing biomarkers such as the methylome and the proteome. The incorporation of dynamic facial expressions in the analysis was shown to improve the accuracy of age estimation, with a mean absolute error of 3.74. Confocal microscopy demonstrated potential for accurate skin aging estimation, with some studies achieving up to 85 % accuracy. Many studies were found with high PROBAST risk of bias scores, most commonly due to small sample sizes.

CONCLUSION

Future studies should aim for greater diversity in ethnicity and variables within datasets to improve generalizability.

Mechanistic Insights Into 5'-tiRNA-His-GTG Mediated Activation of the JNK Pathway in Skin Photoaging

UV exposure leads to skin damage, thus inducing skin aging. The aims of this study were to explore the differences in tRNA-derived small RNAs (tsRNAs) expression in the Human dermal fibroblasts (HDF cells) photoaging cell model and to explore the biological functions of tsRNA in skin photoaging. In this study, we found that in both photoaging cell models and the skin of photoaging mice, the 5'-tiRNA-His-GTG expression levels were significantly elevated. In HDF cells, overexpression of 5'-tiRNA-His-GTG induces cellular senescence. Inhibition of 5'-tiRNA-His-GTG attenuates UVB-induced cellular senescence in the photoaging cell model. Intradermal injection of Adeno-associated virus 9-5'-tiRNA-His-GTG -Inhibition ameliorates UVB-induced skin photoaging in nude mice. We confirmed that 5'-tiRNA-His-GTG targeted nuclear pore proteins 98, which further activated the JNK signaling pathway and induced cell senescence. Targeting 5'-tiRNA-His-GTG may provide a novel therapeutic option for ameliorating skin photoaging.

Bioactive Potential of a Grape Stem Blend: A Sustainable Approach to Skin Regeneration

The European wine industry is embracing sustainability through circular economy principles, particularly by valorizing by-products, such as grape stems. Grape stems are rich in phenolic compounds with recognized health benefits. This study investigates the bioactive potential of molecules extracted from a blend of grape stems (GS blend extract). The GS blend extract was chemically characterized in terms of total phenolic content (TPC), ortho-diphenol content (ODC), and flavonoid content (FC), with key compounds identified via HPLC-MS. The extract's antioxidant capacity was assessed using ABTS, FRAP, and DPPH assays, while its anti-aging and depigmenting properties were evaluated through elastase and tyrosinase inhibition assays. Additionally, in vitro assays were conducted to assess its effects on skin cells, including morphology, metabolic activity, cell cycle, and cell migration. The GS blend extract was found to be rich in proanthocyanidins and exhibited notable antioxidant and depigmenting properties. In vitro assays demonstrated that the extract had no significant impact on cellular metabolic activity or cell morphology, although a reorganization of the cell monolayer was observed. Furthermore, deviations in cell migration and cell cycle regulation suggest that the GS blend extract may aid in scar formation management. Notably, the extract arrested fibroblasts in the Sub G0-G1 phase and inhibited HaCaT cell migration, supporting its potential application in cosmetic and pharmaceutical formulations aimed at scar modulation and skin health.

Mitochondria in cutaneous health, disease, ageing and rejuvenation-the 3PM-guided mitochondria-centric dermatology

Association of both intrinsic and extrinsic risk factors leading to accelerated skin ageing is reflected in excessive ROS production and ir/reversible mitochondrial injury and burnout, as abundantly demonstrated by accumulating research data. Due to the critical role of mitochondrial stress in the pathophysiology of skin ageing and disorders, maintained (primary care) and restored (secondary care) mitochondrial health, rejuvenation and homoeostasis are considered the most effective holistic approach to advance dermatological treatments based on systemic health-supportive and stimulating measures. Per evidence, an effective skin anti-ageing protection, wound healing and scarring quality - all strongly depend on the sustainable mitochondrial functionality and well-balanced homoeostasis. The latter can be objectively measured and, if necessary, restored in a systemic manner by pre- and rehabilitation algorithms tailored to individualised patient profiles. The entire spectrum of corresponding innovations in the area includes natural and systemic skin rejuvenation, aesthetic and reconstructive medicine, sustainable skin protection and targeted treatments of skin disorders. Contextually, mitochondria-centric dermatology is instrumental for advanced 3PM-guided approach which makes a good use of predictive multi-level diagnostics and targeted protection of skin against both - the health-to-disease transition and progression of relevant disorders. Cost-effective targeted protection and new treatment avenues focused on sustainable mitochondrial health and physiologic homoeostasis are proposed in the article including in-depth analysis of patient cases and exemplified 3PM-guided care with detailed mechanisms and corresponding expert recommendations presented.

Senescence in the ageing skin: a new focus on mTORC1 and the lysosome

Ageing is defined as the progressive loss of tissue function and regenerative capacity and is caused by both intrinsic factors i.e. the natural accumulation of damage, and extrinsic factors i.e. damage from environmental stressors. Cellular senescence, in brief, is an irreversible exit from the cell cycle that occurs primarily in response to excessive cellular damage, such as from ultraviolet (UV) exposure and oxidative stress, and it has been comprehensively demonstrated to contribute to tissue and organismal ageing. In this review, we will focus on the skin, an organ which acts as an essential protective barrier against injury, insults, and infection. We will explore the evidence for the existence and contribution of cellular senescence to skin ageing. We discuss the known molecular mechanisms driving senescence in the skin, with a focus on the dysregulation of the master growth regulator, mechanistic Target of Rapamycin Complex 1 (mTORC1). We explore the interplay of dysregulated mTORC1 with lysosomes and how they contribute to senescence phenotypes.

Efficacy and Safety of Topical Application of Plant-Based Products on Skin Aging in Healthy Individuals: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Recently, numerous topical products containing plant-based ingredients have been reported to resist skin aging. However, there is a lack of sufficient evidence to substantiate these claims. This paper presents a comprehensive review and meta-analysis to evaluate the efficacy and safety of topical products containing plants or plant extracts in anti-aging.

METHODS

Four databases-PubMed, Embase, Web of Science, and the Cochrane Library (CENTRAL)-were systematically searched for articles related to plant-based interventions and skin aging, covering the period from January 2000 to December 2024. A total of eight randomized controlled trials (RCTs) met the inclusion criteria and were included in the meta-analysis.

RESULTS

Products containing plant extracts demonstrated a statistically significant difference in improving skin hydration and skin elasticity, reducing melanin and erythema compared to other products. No significant statistical difference was observed in reducing transepidermal water loss (TEWL). Subgroup analysis revealed a significant statistical difference in improvement overall skin elasticity (R2) during short-term (≤ 8 weeks)treatments, while no statistical difference was observed during long-term (> 8 weeks)treatments. Additionally, no significant difference was observed in the specific measurements of skin elasticity, including R5 (net elasticity) and R7 (the ratio of elastic recovery to total deformation). Regarding safety, no adverse events were reported in six studies, while the remaining two studies did not specify whether adverse events occurred.

CONCLUSION

The meta-analysis results indicated that botanical preparations significantly enhanced skin hydration, reduced melanin levels and erythema, and increased overall skin elasticity. However, the analysis did not provide sufficient evidence to support a reduction in transepidermal water loss (TEWL), or improvements in R5 (net elasticity) and R7 (the ratio of elastic recovery to total deformation).

SYSTEMATIC REVIEW REGISTRATION

PROSPERO (york.ac.uk) identifier: CRD42023478803.

Facial assessment methods for inhibiting glycation and aging effects and the correlation between glycation and aging parameters

This study aimed to develop in vivo methods for assessing facial anti-glycation and anti-aging effects and to investigate the link between glycation and aging signs. We utilized an AGE reader to measure AGEs levels on the face and arms, establishing a correlation to validate the reader's use for facial AGEs detection. Then the product's 7-day anti-glycation effect was evaluated. And its 56-day anti-aging effects were evaluated using non-invasive probes and VISIA CR, assessing skin tone (skin brightness L* and yellowness b*, skin gloss), texture (skin elasticity R2 and firmness F4, skin pores), and hydration (skin moisture content). Correlations between facial AGEs levels and aging parameters were analyzed. Results indicated a strong correlation between facial and arm AGEs after product application, supporting facial AGEs level as an assessment parameter. The product demonstrated substantial anti-glycation and anti-aging effects, suggesting the methods' efficacy for cosmetic evaluation. A stronger overall correlation was found between AGEs levels and skin tone than with skin texture and hydration, highlighting glycation's impact on skin color.

Aging Skin: A Dermatitis To Which All Flesh Is Heir?

The human body is composed mostly of water fortified by a variety of proteins, fats, carbohydrates, vitamins, minerals, and other nutrients, all organized into an elegant structurally complex and functionally efficient machine in which our consciousness resides. This heterogeneous assemblage of essential ingredients is enclosed in a container known as the integument, or simply, the skin. The container is as important as its contents; when itself devoid of structural and functional integrity, it will both leak as well as become infused with potentially harmful external agents. As we age, skin loses its integrity, and over time it is not unreasonable to conceive of the skin as becoming progressively "leaky." With this deterioration, skin becomes dry, scaly, accessible to microbes, pruritic, and inflamed, the latter setting up the potentially vicious cycle known as "inflammaging." One major example of the effects of chronological aging on the barrier function of skin involves depletion of filaggrin, a 37-kD histidine-rich protein which originates within keratohyaline granules of the epidermis. Some of the consequences of age-related filaggrin depletion may be inferred by experiments of nature known as ichthyosis vulgaris and atopic dermatitis (AD), the latter with atopy being the most common inflammatory disease worldwide. In AD, loss of function mutations in the FLG gene encoding for the filaggrin precursor, profilaggrin, are associated with skin that, as with aging, is also dry, scaly, accessible to microbes, pruritic and inflamed. In this mini-review, AD will be compared and contrasted with aging in terms of the consequences of deficient filaggrin barrier function. The goal is to enhance recognition that one of the most clinically symptomatic and visible signs of aging is a subtle yet ubiquitous form of "dermatitis" due to "leaky" skin, one that may be addressed therapeutically with smart combinatorial strategies that restore the molecular basis for skin barrier dysfunction.

The A-Z of age-related dermatological diseases

Skin ageing is an inevitable process influenced by both intrinsic and extrinsic factors. Intrinsic aging leads to thinner, drier and less elastic skin with fine wrinkles, while extrinsic factors such as sun exposure, smoking and environmental stresses amplify these changes. Photo-ageing, in particular, causes deep wrinkles, uneven pigmentation and increases the risk of skin cancers. Age-related alterations in skin structure and function include thinning of the epidermis, reduced collagen and elastin and changes in fat distribution, all of which compromise the skin's barrier and mechanical properties. These changes not only increase the susceptibility to conditions such as xerosis, fungal infections and atopic dermatitis but also carry psychological implications. Interestingly, atopic dermatitis, often associated with childhood, has a secondary peak in older adults and may be linked to neurodegenerative conditions such as Alzheimer's disease. This article explores the interplay between skin aging, dermatological diseases, and their broader physical and emotional impacts.

Loss of H3K9 trimethylation leads to premature aging

Aging is the major risk factor for most human diseases and represents a major socioeconomical challenge for modern societies. Despite its importance, the process of aging remains poorly understood. Epigenetic dysregulation has been proposed as a key driver of the aging process. Alterations in transcriptional networks and chromatin structure might be central to age-related functional decline. A prevalent feature described during aging is the overall reduction in heterochromatin, specifically marked by the loss of the repressive histone modification, histone 3 lysine 9 trimethylation (H3K9me3). However, the role of H3K9me3 in aging, especially in mammals, remains unclear. Here we show using a novel mouse strain, "TKOc", carrying a triple knockout of three methyltransferases responsible for H3K9me3 deposition, that the inducible loss of H3K9me3 in adulthood results in premature aging. TKOc mice exhibit reduced lifespan, lower body weight, increased frailty index, multi-organ degeneration, transcriptional changes with significant upregulation of transposable elements, and accelerated epigenetic age. Our data strongly supports the concept that the loss of epigenetic information might directly drives the aging process. These findings reveal the importance of epigenetic regulation in aging and suggest that interventions targeting epigenetic modifications could potentially slow down or reverse age-related decline. Understanding the molecular mechanisms underlying the process of aging will be crucial for developing novel therapeutic strategies that can delay the onset of age-associated diseases and preserve human health at old age specially in rapidly aging societies.

Topical ABT-263 treatment reduces aged skin senescence and improves subsequent wound healing

Senescent cells accumulate in aging tissues, impairing their ability to undergo repair and regeneration following injury. Previous research has demonstrated that targeting tissue senescence with senolytics can enhance tissue regeneration and repair by selectively eliminating SnCs in specific aged tissues. In this study, we focused on eliminating senescent skin cells in aged mice to assess the effects on subsequent wound healing. We applied ABT-263 directly to the skin of 24-month-old mice over a 5-day period. Following topical ABT-263, aged skin demonstrated decreased gene expression of senescence markers p16 and p21, accompanied by reductions in SA-β-gal- and p21-positive cells compared to DMSO controls. However, ABT-263 also triggered a temporary inflammatory response and macrophage infiltration in the skin. Bulk RNA sequencing of ABT-263-treated skin revealed prompt upregulation of genes associated with wound healing pathways, including hemostasis, inflammation, cell proliferation, angiogenesis, collagen synthesis, and extracellular matrix organization. Aged mice skin pre-treated with topical ABT-263 exhibited accelerated wound closure. In conclusion, topical ABT-263 effectively reduced several senescence markers in aged skin, thereby priming the skin for improved subsequent wound healing. This enhancement may be attributed to ABT-263-induced senolysis which in turn stimulates the expression of genes involved in extracellular matrix remodeling and wound repair pathways.

Battery-Free, Wireless Multi-Modal Sensor, and Actuator Array System for Pressure Injury Prevention

Simultaneous monitoring of critical parameters (e.g., pressure, shear, and temperature) at bony prominences is essential for the prevention of pressure injuries in a systematic manner. However, the development of wireless sensor array for accurate mapping of risk factors has been limited due to the challenges in the convergence of wireless technologies and wearable sensor arrays with a thin and small form factor. Herein, a battery-free, wireless, miniaturized multi-modal sensor array is introduced for continuous mapping of pressure, shear, and temperature at skin interfaces. The sensor array includes an integrated pressure and shear sensor consisting of 3D strain gauges and micromachined components. The mechanically decoupled design of the integrated sensor enables reliable data acquisition of pressure and shear at skin interfaces without the need for additional data processing. The sensor platform enables the analysis of interplay among localized pressure, shear, and temperature in response to changes in the patient's movement, posture, and bed inclination. The validation trials using a novel combination of wireless sensor arrays and customized pneumatic actuator demonstrate the efficacy of the platform in continuous monitoring and efficient redistribution of pressure and shear without repositioning, thereby improving the patient's quality of life.

Efficacy and safety of a novel monopolar radiofrequency device with a continuous water-cooling system in patients with age-related facial volume loss

BACKGROUND

Esthetic radiofrequency (RF) technology has much attracted public attention with the increasing demand for skin rejuvenation. A continuous water cooling-based monopolar RF (MRF) device was designed for the first time to protect the epidermis and maximize clinical outcomes.

OBJECTIVE

Assess the efficacy and safety of the proposed MRF device in patients with mild-to-moderate sunken cheeks and jawline laxity.

METHODS

Twenty-one patients underwent a single session of MRF treatment. Quantitative analysis was performed using a 3D imaging technique. Postprocedural clinical improvements were assessed with the Merz Scale. Regarding safety, adverse events (AEs), thermal sensation (TS) and pain intensity were explored. Patient satisfaction was surveyed with the Self-Assessment Questionnaire (SAQ).

RESULTS

The follow-up investigation demonstrated that facial volume increased across the cheek and jawline, with lifting effects throughout the treatment area. The Merz Scale assessment revealed that sunken cheeks, sagging jawlines and wrinkles were markedly improved. In addition, there were transient AEs, mild TS and moderate pain. In SAQ, 81% patients were satisfied with the procedure.

CONCLUSIONS

This study provided quantitative evidence for postprocedural volumetric increases along with enhanced lifting effects, strongly implying that the proposed MRF device can be an attractive option for improving facial skin volume loss and laxity.

Biotics as novel therapeutics in targeting signs of skin ageing via the gut-skin axis

Skin ageing is a phenomenon resulting from the aggregative changes to skin structure and function and is clinically manifested by physical features such as wrinkles, hyperpigmentation, elastosis, telangiectasia, and deterioration of skin barrier integrity. One of the main drivers of skin ageing, UV radiation, negatively influences the homeostasis of cells and tissues comprising the skin by triggering production of immune-mediated reactive oxygen species (ROS) and pro-inflammatory cytokines, as well as a various hormones and neuropeptides. Interestingly, an established link between the gut and the skin coined the 'gut-skin axis' has been demonstrated, with dysbiosis and gut barrier dysfunction frequently observed in certain inflammatory skin conditions and more recently, implicated in skin ageing. Therapeutic use of 'biotics' including prebiotics, probiotics, postbiotics, and synbiotics, which modulate the gut microbiota and production of microbially associated metabolites, influence the activity of the gut mucosal and immune systems and are showing promise as key candidates in addressing signs of skin ageing. In this review we aim to focus on the structure and function of the gut-skin axis and showcase the recent in-vitro and clinical evidence demonstrating the beneficial effects of select biotics in targeting signs of skin ageing and discuss the proposed mechanisms mediated via the gut-skin axis underpinning these effects.

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.

Skin senescence-from basic research to clinical practice

The most recognizable implications of tissue aging manifest themselves on the skin. Skin laxity, roughness, pigmentation disorders, age spots, wrinkles, telangiectasia or hair graying are symptoms of physiological aging. Development of the senescent phenotype depends on the interaction between aging cells and remodeling of the skin's extracellular matrix (ECM) that contains collagen and elastic fiber. Aging changes occur due to the combination of both endogenous (gene mutation, cellular metabolism or hormonal agents) and exogenous factors (ultraviolet light, environmental pollutants, and unsuitable diet). However, overproduction of mitochondrial reactive oxygen species (ROS) is a key factor driving cellular senescence. Aging theories have disclosed a range of diverse molecular mechanisms that are associated with cellular senescence of the body. Theories best supported by evidence include protein glycation, oxidative stress, telomere shortening, cell cycle arrest, and a limited number of cell divisions. Accumulation of the ECM damage is suggested to be a key factor in skin aging. Every cell indicates a functional and morphological change that may be used as a biomarker of senescence. Senescence-associated β-galactosidase (SA-β-gal), cell cycle inhibitors (p16INK4a, p21CIP1, p27, p53), DNA segments with chromatin alterations reinforcing senescence (DNA-SCARS), senescence-associated heterochromatin foci (SAHF), shortening of telomeres or downregulation of lamina B1 constitute just an example of aging biomarkers known so far. Aging may also be assessed non-invasively through measuring the skin fluorescence of advanced glycation end-products (AGEs). This review summarizes the recent knowledge on the pathogenesis and clinical conditions of skin aging as well as biomarkers of skin senescence.

Feasibility of Monitoring Heart and Respiratory Rates Using Nonwearable Devices and Consistency of the Measured Parameters: Pilot Feasibility Study

Background

As Japan is the world's fastest-aging society with a declining population, it is challenging to secure human resources for care providers. Therefore, the Japanese government is promoting digital transformation and the use of nursing care equipment, including nonwearable devices that monitor heart and respiratory rates. However, the feasibility of monitoring heart and respiratory rates with nonwearable devices and the consistency of the rates measured have not been reported.

Objective

In this study, we focused on a sheet-type nonwearable device (Safety Sheep Sensor) introduced in many nursing homes. We evaluated the feasibility of monitoring heart rate (HR) and respiratory rate (RR) continuously using nonwearable devices and the consistency of the HR and RR measured.

Methods

A sheet-type nonwearable device that measured HR and RR every minute through body vibrations was placed under the mattress of each participant. The participants in study 1 were healthy individuals aged 20-60 years (n=21), while those in study 2 were older adults living in multidwelling houses and required nursing care (n=20). The HR was measured using standard methods by the nurse and using the wearable device (Silmee Bar-type Lite sensor), and RR was measured by the nurse. The primary outcome was the mean difference in HR and RR between nonwearable devices and standard methods.

Results

The mean difference in HR was -0.32 (SD 3.12) in study 1 and 0.04 (SD: 3.98) in study 2; both the differences were within the predefined accepted discrepancies (<5 beats/min). The mean difference in RR was -0.98 (SD 3.01) in study 1 and -0.49 (SD 2.40) in study 2; both the differences were within the predefined accepted discrepancies (3 breaths/min).

Conclusions

HR and RR measurements obtained using the nonwearable devices and the standard method were similar. Continuous monitoring of vital signs using nonwearable devices can aid in the early detection of abnormal conditions in older people.

Efficacy and Safety of Microencapsulated Benzoyl Peroxide Cream, 5%, in Papulopustular Rosacea in Elderly Patients: Post-hoc Analysis of Results from Two Randomized, Phase III, Vehicle-controlled Trials

Objective

We sought to compare the efficacy and safety of encapsulated benzoyl peroxide (E-BPO) cream, 5%, versus vehicle in subjects <65 years of age versus subjects ≥65 with moderate to severe papulopustular rosacea.

Methods

This analysis used pooled results from two 12-week, randomized, vehicle-controlled Phase III trials (NCT03564119, NCT03448939) of E-BPO cream, 5%. These trials included 733 subjects randomized 2:1 to E-BPO or vehicle. The primary endpoints were success in the Investigator's Global Assessment (IGA) score and reduction in mean inflammatory lesion count at Week 12.

Results

Our analysis shows that E-BPO cream, 5%, was significantly superior to vehicle in achieving IGA success and reducing inflammatory lesions in both age groups. IGA success was achieved in 48.3% of subjects who received E-BPO versus 25.4% for vehicle in the intent-to-treat population. The E-BPO and vehicle IGA success percentages for subjects <65 were 45.7% and 23.8%, respectively, and those for subjects ≥65 were 60.0% and 28.1%, respectively. The absolute reduction from baseline in inflammatory lesions was -19.3 for subjects who received E-BPO versus -11.4 for those who received vehicle. The E-BPO and vehicle absolute reduction values for subjects <65 were -19.6 and -11.2, respectively, and 17.5 and -10.4 for subjects ≥65. There were no significant differences in the frequencies of adverse events or cutaneous tolerability.

Limitations

E-BPO was not compared to nonencapsulated BPO.

Conclusion

This combined analysis of results from the two Phase III, randomized, double-blind controlled studies of E-BPO cream, 5%, showed it was efficacious, tolerable, and safe, regardless of age.

Targeting organ-specific mitochondrial dysfunction to improve biological aging

In an aging society, unveiling new anti-aging strategies to prevent and combat aging-related diseases is of utmost importance. Mitochondria are the primary ATP production sites and key regulators of programmed cell death. Consequently, these highly dynamic organelles play a central role in maintaining tissue function, and mitochondrial dysfunction is a pivotal factor in the progressive age-related decline in cellular homeostasis and organ function. The current review examines recent advances in understanding the interplay between mitochondrial dysfunction and organ-specific aging. Thereby, we dissect molecular mechanisms underlying mitochondrial impairment associated with the deterioration of organ function, exploring the role of mitochondrial DNA, reactive oxygen species homeostasis, metabolic activity, damage-associated molecular patterns, biogenesis, turnover, and dynamics. We also highlight emerging therapeutic strategies in preclinical and clinical tests that are supposed to rejuvenate mitochondrial function, such as antioxidants, mitochondrial biogenesis stimulators, and modulators of mitochondrial turnover and dynamics. Furthermore, we discuss potential benefits and challenges associated with the use of these interventions, emphasizing the need for organ-specific approaches given the unique mitochondrial characteristics of different tissues. In conclusion, this review highlights the therapeutic potential of addressing mitochondrial dysfunction to mitigate organ-specific aging, focusing on the skin, liver, lung, brain, skeletal muscle, and lung, as well as on the reproductive, immune, and cardiovascular systems. Based on a comprehensive understanding of the multifaceted roles of mitochondria, innovative therapeutic strategies may be developed and optimized to combat biological aging and promote healthy aging across diverse organ systems.

A γδ T cell-IL-3 axis controls allergic responses through sensory neurons

In naive individuals, sensory neurons directly detect and respond to allergens, leading to both the sensation of itch and the activation of local innate immune cells, which initiate the allergic immune response1,2. In the setting of chronic allergic inflammation, immune factors prime sensory neurons, causing pathologic itch3-7. Although these bidirectional neuroimmune circuits drive responses to allergens, whether immune cells regulate the set-point for neuronal activation by allergens in the naive state is unknown. Here we describe a γδ T cell-IL-3 signalling axis that controls the allergen responsiveness of cutaneous sensory neurons. We define a poorly characterized epidermal γδ T cell subset8, termed GD3 cells, that produces its hallmark cytokine IL-3 to promote allergic itch and the initiation of the allergic immune response. Mechanistically, IL-3 acts on Il3ra-expressing sensory neurons in a JAK2-dependent manner to lower their threshold for allergen activation without independently eliciting itch. This γδ T cell-IL-3 signalling axis further acts by means of STAT5 to promote neuropeptide production and the initiation of allergic immunity. These results reveal an endogenous immune rheostat that sits upstream of and governs sensory neuronal responses to allergens on first exposure. This pathway may explain individual differences in allergic susceptibility and opens new therapeutic avenues for treating allergic diseases.

A Comprehensive Review of Stem Cell Conditioned Media Role for Anti-Aging on Skin

Various studies have been widely conducted on conditioned medium for the development of anti-aging preparations, including the utilization of stem cells, which present a promising alternative solution. This narrative review aims to understand the latest developments in various conditioned medium stem cell applications for anti-aging on the skin. A search of the Scopus database yielded publications of interest. The research focused on articles published without restrictions on the year. After finding 68 articles in the search results, they moved on to the checking phase. Upon comprehensive literature review, 23 articles met the inclusion criteria, while 45 articles were deemed ineligible for participation in this research. The results of the review indicate that conditioned medium from various stem cells has demonstrated success in reducing risk factors for skin aging, as proven in various tests. The successful reduction of the risk of skin aging has been established in vitro, in vivo, and in clinical trials. Given the numerous studies on the progress of exploring and utilizing conditioned medium, it is expected to provide a solution to the problem of skin aging.

Potential anti-aging applications of microbial-derived surfactantsin cosmetic formulations

The skin aging process is a complex interaction of genetic, epigenetic, and environmental factors, such as chemical pollution and UV radiation. There is growing evidence that biosurfactants, especially those of microbial origin, have distinct age-supportive effects through different mechanisms, such as stimulation of fibroblast growth, high antioxidant capacities, and favorable anti-inflammatory properties. With a growing financial contribution of more than 15 m€per year, microbial surfactants (MSs) display unique biological effects on the skin including improved cell mobility, better nutrient access, and facilitated cellular growth under harsh conditions. Their biodegradable nature, unusual surface activity, good safety profile and tolerance to high temperature and pH variations widen their potential spectrum in biomedical and pharmaceutical applications. MSs typically have lower critical micelle concentration (CMC) levels than chemical surfactants enhancing their effectiveness. As natural surfactants, MSs are considered possible "green" alternatives to synthetic surfactants with better biodegradability, sustainability, and beneficial functional properties. This review therefore aims to explore the potential impacts of MSs as anti-aging ingredients.

Development of Transdermal Formulation Integrating Polymer-Based Solid Microneedles and Thermoresponsive Gel Fucoidan for Antiaging: Proof of Concept Study

Skin can be damaged by intense and prolonged exposure to ultraviolet (UV) radiation. Photoaging and acute damage from sun exposure result in collagen degradation and enzymatic activity decline in the skin. Fucoidan (FUC) exhibits potential antiaging properties, including collagen synthesis promotion and enzyme activity inhibition. However, FUC's limited ability to penetrate the skin layers due to its large molecular weight makes it a challenge for topical application. In this study, we successfully developed a new approach by integrating thermoresponsive gel (TRG) containing FUC with solid microneedles (SMNs) as a delivery system. TRG is formulated using a combination of Pluronic F127 (PF127) and Pluronic F68 (PF68) polymers, while SMNs are made from a mixture of poly(vinyl alcohol) (PVA) and poly(vinylpyrrolidone) (PVP) polymers with a variety of cross-linkers. Based on the results of ex vivo testing, it was shown that more than 80% of FUC can be delivered using the optimized formula. Furthermore, the results of the in vitro blood hemolytic test showed that TRG-FUC-SMNs were relatively biocompatible. In vivo antiaging activity tests using a rat model exposed to UV for 14 days showed that histological assessment, skin elasticity measurement, wrinkle evaluation, and skin moisture content had no significant differences (p < 0.05) compared to the positive control group. In contrast, a significant difference (p < 0.05) was observed when comparing the TRG-FUC-SMNs group with the group that received only TRG-FUC without pretreatment and negative controls. These findings suggest that FUC has potential to be delivered using the TRG system in combination with SMNs to harness its antiaging properties.

The efficacy of hyaluronic acid fragments with amino acid in combating facial skin aging: an ultrasound and histological study

BACKGROUND

Various techniques have been employed in aesthetic medicine to combat skin aging, in particular that of the facial region. Hyaluronic acid is utilized to enhance moisture levels and extracellular matrix molecules. This study aims to histologically assess the effects of low molecular weight hyaluronic acid fragments combined with amino acids (HAAM) on facial skin rejuvenation through intradermal microinjections.

METHODS

A total of twenty women, with an average age of 45 and ranging from 35 to 64 years old, participated in the study, including 8 in menopause and 12 in the childbearing age group. Mesotherapy was used to administer HAAM to the patients. Prior to and three months after the treatment, each patient underwent small circular punch biopsies. Ultrasound examinations were conducted using B-mode, capturing 2D images in longitudinal or transverse orientations with frequencies ranging from 5 to 13 Mega-hertz (MY LAB X8, ESAOTE, Genova, Italy). A total of 60 ultrasound examinations were taken, with 30 collected before treatment and 30 after treatment.

RESULTS

The histological analysis demonstrates an increase in fibroblast activity resulting in the production of Type III reticular collagen, as well as an increased number of blood vessels and epidermal thickness. However, the analysis of ultrasound data before and after treatment showed no statistical difference in skin thickness in malar area, chin and mandibular angle.

CONCLUSIONS

Histological assessments indicate that subcutaneous infiltration of HAAM has a substantial impact on the dermis of facial skin.

Natural autophagy activators: A promising strategy for combating photoaging

BACKGROUND

Photodamage to the skin stands out as one of the most widespread epidermal challenges globally. Prolonged exposure to sunlight containing ultraviolet radiation (UVR) instigates stress, thereby compromising the skin's functionality and culminating in photoaging. Recent investigations have shed light on the importance of autophagy in shielding the skin from photodamage. Despite the acknowledgment of numerous phytochemicals possessing photoprotective attributes, their potential to induce autophagy remains relatively unexplored.

PURPOSE

Diminished autophagy activity in photoaged skin underscores the potential benefits of restoring autophagy through natural compounds to enhance photoprotection. Consequently, this study aims to highlight the role of natural compounds in safeguarding against photodamage and to assess their potential to induce autophagy via an in-silico approach.

METHODS

A thorough search of the literature was done using several databases, including PUBMED, Science Direct, and Google Scholar, to gather relevant studies. Several keywords such as Phytochemical, Photoprotection, mTOR, Ultraviolet Radiation, Reactive oxygen species, Photoaging, and Autophagy were utilized to ensure thorough exploration. To assess the autophagy potential of phytochemicals through virtual screening, computational methodologies such as molecular docking were employed, utilizing tools like AutoDock Vina. Receptor preparation for docking was facilitated using MGLTools.

RESULTS

The initiation of structural and functional deterioration in the skin due to ultraviolet radiation (UVR) or sunlight-induced reactive oxygen species/reactive nitrogen species (ROS/RNS) involves the modulation of various pathways. Natural compounds like phenolics, flavonoids, flavones, and anthocyanins, among others, possess chromophores capable of absorbing light, thereby offering photoprotection by modulating these pathways. In our molecular docking study, these phytochemicals have shown binding affinity with mTOR, a negative regulator of autophagy, indicating their potential as autophagy modulators.

CONCLUSION

This integrated review underscores the photoprotective characteristics of natural compounds, while the in-silico analysis reveals their potential to modulate autophagy, which could significantly contribute to their anti-photoaging properties. The findings of this study hold promise for the advancement of cosmeceuticals and therapeutics containing natural compounds aimed at addressing photoaging and various skin-related diseases. By leveraging their dual benefits of photoprotection and autophagy modulation, these natural compounds offer a multifaceted approach to combatting skin aging and related conditions.

Comparison of facial skin ageing in healthy Asian and Caucasian females quantified by in vivo line-field confocal optical coherence tomography 3D imaging

BACKGROUND

Quantitative biomarkers of facial skin aging were investigated in 109 healthy Asian female volunteers, aged 20 to 70 years.

MATERIALS AND METHODS

In vivo 3D Line-field Confocal Optical Coherence Tomography (LC-OCT) imaging, enhanced by Artificial Intelligence (AI)-based quantification algorithms, was utilized to compute various metrics, including stratum corneum thickness (SC), viable epidermal (VE) thickness, and Dermal-Epidermal Junction (DEJ) undulation along with cellular metrics for the temple, cheekbone, and mandible.

RESULTS

Comparison with data from a cohort of healthy Caucasian volunteers revealed similarities in the variations of stratum corneum and viable epidermis layers, as well as cellular shape and size with age in both ethnic groups. However, specific findings emerged, such as larger, more heterogeneous nuclei in both layers, demonstrated by an increase in nuclei volume and their standard deviation, and increased network atypia, all showing significant age-related variations. Caucasian females exhibited a flatter and more homogeneous epidermis, evidenced by a decreased standard deviation of the number of layers, and a less dense cellular network with fewer cells per layer, indicated by a decrease in cell surface density.

CONCLUSION

Ethnicity-wise comparisons highlighted distinct biological features specific to each population. Asian individuals showed significantly higher DEJ undulation, higher compactness, and lower cell network atypia compared to their Caucasian counterparts across age groups. Differences in stratum corneum and viable epidermal thickness on the cheekbone were also significant. LC-OCT 3D imaging provides valuable insights into the aging process in different populations and underscores inherent biological differences between Caucasian and Asian female volunteers.

Defining cell type-specific immune responses in a mouse model of allergic contact dermatitis by single-cell transcriptomics

Allergic contact dermatitis (ACD), a prevalent inflammatory skin disease, is elicited upon repeated skin contact with protein-reactive chemicals through a complex and poorly characterized cellular network between immune cells and skin resident cells. Here, single-cell transcriptomic analysis of the murine hapten-elicited model of ACD reveals that upon elicitation of ACD, infiltrated CD4+ or CD8+ lymphocytes were primarily the IFNγ-producing type 1 central memory phenotype. In contrast, type 2 cytokines (IL4 and IL13) were dominantly expressed by basophils, IL17A was primarily expressed by δγ T cells, and IL1β was identified as the primary cytokine expressed by activated neutrophils/monocytes and macrophages. Furthermore, analysis of skin resident cells identified a sub-cluster of dermal fibroblasts with preadipocyte signature as a prominent target for IFNγ+ lymphocytes and dermal source for key T cell chemokines CXCL9/10. IFNγ treatment shifted dermal fibroblasts from collagen-producing to CXCL9/10-producing, which promoted T cell polarization toward the type-1 phenotype through a CXCR3-dependent mechanism. Furthermore, targeted deletion of Ifngr1 in dermal fibroblasts in mice reduced Cxcl9/10 expression, dermal infiltration of CD8+ T cell, and alleviated ACD inflammation in mice. Finally, we showed that IFNγ+ CD8+ T cells and CXCL10-producing dermal fibroblasts co-enriched in the dermis of human ACD skin. Together, our results define the cell type-specific immune responses in ACD, and recognize an indispensable role of dermal fibroblasts in shaping the development of type-1 skin inflammation through the IFNGR-CXCR3 signaling circuit during ACD pathogenesis.

Topical ABT-263 treatment reduces aged skin senescence and improves subsequent wound healing

Senescent cells (SnC) accumulate in aging tissues, impairing their ability to undergo repair and regeneration following injury. Previous research has demonstrated that targeting tissue senescence with senolytics can enhance tissue regeneration and repair by selectively eliminating SnCs in specific aged tissues. In this study, we focused on eliminating SnC skin cells in aged mice to assess the effects on subsequent wound healing. We applied ABT-263 directly to the skin of 24-month-old mice over a 5-day period. Following topical ABT-263, aged skin demonstrated decreased gene expression of senescent markers p16 and p21, accompanied by reductions in SA-β-gal and p21-positive cells compared to DMSO controls. However, ABT-263 also triggered a temporary inflammatory response and macrophage infiltration in the skin. Bulk RNA sequencing of ABT-263-treated skin revealed prompt upregulation of genes associated with wound healing pathways, including hemostasis, inflammation, cell proliferation, angiogenesis, collagen synthesis, and extracellular matrix organization. Aged mice skin pre-treated with topical ABT-263 exhibited accelerated wound closure. In conclusion, topical ABT-263 effectively reduced several senescence markers in aged skin, thereby priming the skin for improved subsequent wound healing. This enhancement may be attributed to ABT-263-induced senolysis which in turn stimulates the expression of genes involved in extracellular matrix remodeling and wound repair pathways.

Tissue-scale in vitro epithelial wrinkling and wrinkle-to-fold transition

Although epithelial folding is commonly studied using in vivo animal models, such models exhibit critical limitations in terms of real-time observation and independent control of experimental parameters. Here, we develop a tissue-scale in vitro epithelial bilayer folding model that incorporates an epithelium and extracellular matrix (ECM) hydrogel, thereby emulating various folding structures found in in vivo epithelial tissue. Beyond mere folding, our in vitro model realizes a hierarchical transition in the epithelial bilayer, shifting from periodic wrinkles to a single deep fold under compression. Experimental and theoretical investigations of the in vitro model imply that both the strain-stiffening of epithelium and the poroelasticity of ECM influence the folded structures of epithelial tissue. The proposed in vitro model will aid in investigating the underlying mechanism of tissue-scale in vivo epithelial folding relevant to developmental biology and tissue engineering.

Cosmeceuticals: A Review of Clinical Studies Claiming to Contain Specific, Well-Characterized Strains of Probiotics or Postbiotics

The skin serves as a critical barrier against external threats-dehydration, ultraviolet exposure, and infections-playing a significant role in internal homeostasis and moisture retention. Additionally, and equally importantly, it interacts dynamically with the complex microbiome resident in it, which is essential for maintaining skin health. Recent interest has focused on the use of probiotics and postbiotics, besides their ability to modulate the skin microbiome, to enhance barrier function, and exhibit anti-inflammatory properties, to be involved in skincare, by having the potential to improve skin hydration, elasticity, and overall appearance, as well as in reducing signs of aging, such as wrinkles and fine lines. The products-being a combination of a cosmetic regime plus probiotic[s] or postbiotic[s]-are named cosmeceuticals. However, to comply with the regulations for the characterization of a microorganism as a specific probiotic strain, the pro- or postbiotics incorporated into the cosmetic regime should be both genetically and phenotypically defined. Thus, in this review, we present 14 published clinical trials using such cosmetic products with specific, well-characterized strains of probiotics or postbiotics applied to volunteers with healthy skin. Looking at the results of these studies collectively, we can say that these genetically and phenotypically defined strains of either live or inanimate bacteria and/or their components seem to keep the treated skin at least fully hydrated, with intact epithelial tone, increased radiance, and with decreased wrinkle depth, while normalizing the commensal skin microbiota. Future advancements in personalized skin care may lead to genomic sequencing and metabolomics to tailor probiotic and postbiotic treatments to individual skin microbiomes, promising a new frontier in cosmeceuticals.

Loss of H3K9 trimethylation leads to premature aging

Aging is the major risk factor for most human diseases and represents a major socio-economical challenge for modern societies. Despite its importance, the process of aging remains poorly understood. Epigenetic dysregulation has been proposed as a key driver of the aging process. Modifications in transcriptional networks and chromatin structure might be central to age-related functional decline. A prevalent feature described during aging is the overall reduction in heterochromatin, specifically marked by the loss of repressive histone modification, Histone 3 lysine 9 trimethylation (H3K9me3). However, the role of H3K9me3 in aging, especially in mammals, remains unclear. Here we show using a novel mouse strain, (TKOc), carrying a triple knockout of three methyltransferases responsible for H3K9me3 deposition, that the inducible loss of H3K9me3 in adulthood results in premature aging. TKOc mice exhibit reduced lifespan, lower body weight, increased frailty index, multi-organ degeneration, transcriptional changes with significant upregulation of transposable elements, and accelerated epigenetic age. Our data strongly supports the concept that the loss of epigenetic information directly drives the aging process. These findings reveal the importance of epigenetic regulation in aging and suggest that interventions targeting epigenetic modifications could potentially slow down or reverse age-related decline. Understanding the molecular mechanisms underlying the process of aging will be crucial for developing novel therapeutic strategies that can delay the onset of age-associated diseases and preserve human health at old age specially in rapidly aging societies.

A Clinical Trial Shows Improvement in Skin Collagen, Hydration, Elasticity, Wrinkles, Scalp, and Hair Condition following 12-Week Oral Intake of a Supplement Containing Hydrolysed Collagen

Background

Hydrolysed collagen supplements are reported to fight the signs of aging and improve skin appearance, but more authoritative clinical evidence is needed to support efficacy.

Aim

This randomised, double-blind, placebo-controlled study evaluated the efficacy of a supplement containing hydrolysed collagen and vitamin C (Absolute Collagen, AC) on biophysical parameters and visible signs of aging for skin, scalp, and hair, when taken daily or every 48 hours.

Methods

We measured dermal collagen using confocal microscopy and high-resolution ultrasound. Hydration, elasticity, wrinkles, and clinical trichoscopy were measured in parallel to expert visual grading. Efficacy measures were recorded at baseline, week 6, and week 12.

Results

Following 12 weeks daily use of the AC supplement, using confocal microscopy, we observed a significant 44.6% decrease in fragmentation vs. placebo (p < 0.01). We also measured a change in the ultrasound LEP (low echogenic pixel) ratio comparing upper and lower dermis (-9.24 vs. -7.83, respectively, p=0.05), suggesting collagen improvements occurred more in the upper dermal compartment. After 12 weeks vs. placebo, skin hydration was increased by 13.8% (p < 0.01), R2 elasticity index was increased by 22.7% (p<0.01), and Rz profilometry index was decreased by 19.6% (p < 0.01). Trichoscopy showed an average 11.0% improvement in scalp scaling and a 27.6% increase in the total number of hairs counted vs. placebo (p=n.s.). This was associated with a 31.9% increase in clinical grading score for hair healthy appearance (p < 0.01).

Conclusion

The AC supplement has shown clinical benefits for skin, scalp, and hair, when used either daily or every 48 hours, over a 12-week period.

Natural Compounds for Preventing Age-Related Diseases and Cancers

Aging is a multifaceted process influenced by hereditary factors, lifestyle, and environmental elements. As time progresses, the human body experiences degenerative changes in major functions. The external and internal signs of aging manifest in various ways, including skin dryness, wrinkles, musculoskeletal disorders, cardiovascular diseases, diabetes, neurodegenerative disorders, and cancer. Additionally, cancer, like aging, is a complex disease that arises from the accumulation of various genetic and epigenetic alterations. Circadian clock dysregulation has recently been identified as an important risk factor for aging and cancer development. Natural compounds and herbal medicines have gained significant attention for their potential in preventing age-related diseases and inhibiting cancer progression. These compounds demonstrate antioxidant, anti-inflammatory, anti-proliferative, pro-apoptotic, anti-metastatic, and anti-angiogenic effects as well as circadian clock regulation. This review explores age-related diseases, cancers, and the potential of specific natural compounds in targeting the key features of these conditions.

The Role of PGC-1α in Aging Skin Barrier Function

Skin provides a physical and immune barrier to protect the body from foreign substances, microbial invasion, and desiccation. Aging reduces the barrier function of skin and its rate of repair. Aged skin exhibits decreased mitochondrial function and prolonged low-level inflammation that can be seen in other organs with aging. Peroxisome proliferator-activated receptor (PPAR)-γ coactivator-1α (PGC-1α), an important transcriptional coactivator, plays a central role in modulating mitochondrial function and antioxidant production. Mitochondrial function and inflammation have been linked to epidermal function, but the mechanisms are unclear. The aim of this review is to discuss the mechanisms by which PGC-1α might exert a positive effect on aged skin barrier function. Initially, we provide an overview of the function of skin under physiological and aging conditions, focusing on the epidermis. We then discuss mitochondrial function, oxidative stress, cellular senescence, and inflamm-aging, the chronic low-level inflammation observed in aging individuals. Finally, we discuss the effects of PGC-1α on mitochondrial function, as well as the regulation and role of PGC-1α in the aging epidermis.

Unveiling the metabolites underlying the skin anti-ageing properties of Cytinus hypocistis (L.) L. through a biochemometric approach

BACKGROUND

The genus Cytinus, recognised as one of the most enigmatic in the plant kingdom, has garnered attention for its bioactive potential, particularly its skin anti-ageing properties. Despite this recognition, much remains to be accomplished regarding deciphering and isolating its most active compounds.

HYPOTHESIS

This study aimed to identify the compounds responsible for C. hypocistis skin anti-ageing potential.

METHODS

Using multivariate analysis, a biochemometric approach was applied to identify the discriminant metabolites by integrating extracts' chemical profile (Liquid Chromatography-High-Resolution Mass Spectrometry, LCHRMS) and bioactive properties. The identified bioactive metabolite was structurally elucidated by 1D and 2D Nuclear Magnetic Resonance (NMR).

RESULTS

Among the studied bioactivities, the anti-elastase results exhibited a significant variation among the samples from different years. After the biochemometric analysis, the compound 2,3:4,6-bis(hexahydroxydiphenoyl)glucose, with a molecular mass of 784.075 Da, was structurally elucidated as the discriminant feature responsible for the outstanding human neutrophil elastase inhibition. Remarkably, the subfraction containing this compound exhibited a tenfold improvement in neutrophil elastase inhibition efficacy compared to the crude extract; its effectiveness fell within the same range as SPCK, a potent irreversible neutrophil elastase inhibitor. Moreover, this subfraction displayed no cytotoxicity or phototoxicity and excellent efficacy for the tested anti-ageing properties.

CONCLUSIONS

Hydrolysable tannins were confirmed as the metabolites behind C. hypocistis skin anti-ageing properties, effectively mitigating critical molecular mechanisms that influence the phenotypically distinct ageing clinical manifestations. Pedunculagin was particularly effective in inhibiting neutrophil elastase, considered one of the most destructive enzymes in skin ageing.

Looking for the philosopher's stone: Emerging approaches to target the hallmarks of aging in the skin

Senescence and epigenetic alterations are two important hallmarks of cellular aging. During aging, cells subjected to stress undergo many cycles of damage and repair before finally entering either apoptosis or senescence, a permanent state of cell cycle arrest. The first biomarkers of senescence to be identified were increased ß-galactosidase activity and induction of p16INK4a. Another feature of senescent cells is the senescence-associated secretory phenotype (SASP), a complex secretome containing more than 80 pro-inflammatory factors including metalloproteinases, growth factors, chemokines and cytokines. The secretome is regulated through a dynamic process involving a self-amplifying autocrine feedback loop and activation of the immune system. Senescent cells play positive and negative roles depending on the composition of their SASP and may participate in various processes including wound healing and tumour suppression, as well as cell regeneration, embryogenesis, tumorigenesis, inflammation and finally aging. The SASP is also a biomarker of age, biological aging and age-related diseases. Recent advances in anti-age research have shown that senescence can be now prevented or delayed by clearing the senescent cells or mitigating the effects of SASP factors, which can be achieved by a healthy lifestyle (exercise and diet), and senolytics and senomorphics, respectively. An alternative is tissue rejuvenation, which can be achieved by stimulating aged stem cells and reprogramming deprogrammed aged cells. These non-clinical findings will open up new avenues of clinical research into the development of treatments capable of preventing or treating age-related pathologies in humans.

Advances in skin gene therapy: utilizing innovative dressing scaffolds for wound healing, a comprehensive review

The skin, serving as the body's outermost layer, boasts a vast area and intricate structure, functioning as the primary barrier against external threats. Disruptions in the composition and functionality of the skin can lead to a diverse array of skin conditions, such as wounds, burns, and diabetic ulcers, along with inflammatory disorders, infections, and various types of skin cancer. These disorders not only exacerbate concerns regarding skin health and beauty but also have a significant impact on mental well-being. Due to the complexity of these disorders, conventional treatments often prove insufficient, necessitating the exploration of new therapeutic approaches. Researchers develop new therapies by deciphering these intricacies and gaining a thorough understanding of the protein networks and molecular processes in skin. A new window of opportunity has opened up for improving wound healing processes because of recent advancements in skin gene therapy. To enhance skin regeneration and healing, this extensive review investigates the use of novel dressing scaffolds in conjunction with gene therapy approaches. Scaffolds that do double duty as wound protectors and vectors for therapeutic gene delivery are being developed using innovative biomaterials. To improve cellular responses and speed healing, these state-of-the-art scaffolds allow for the targeted delivery and sustained release of genetic material. The most recent developments in gene therapy techniques include RNA interference, CRISPR-based gene editing, and the utilization of viral and non-viral vectors in conjunction with scaffolds, which were reviewed here to overcome skin disorders and wound complications. In the future, there will be rare chances to develop custom methods for skin health care thanks to the combination of modern technology and collaboration among disciplines.

Central Nervous System Medications: Pharmacokinetic and Pharmacodynamic Considerations for Older Adults

Most drugs have not been evaluated in the older population. Recognizing physiological alterations associated with changes in drug disposition and with the ultimate effect, especially in central nervous system-acting drugs, is fundamental. While considering pharmacokinetics, it should be noted that the absorption of most drugs from the gastrointestinal tract does not change in advanced age. There are only few data about the effect of age on the transdermal absorption of medications such as fentanyl. Absorption from an intramuscular injection may be similar in older adults as in younger patients. The distribution of lipophilic drugs (such as diazepam) is increased owing to a relative increase in the percentage of body fat, causing drug accumulation and prolonged drug elimination following cessation. Phase I drug biotransformation is variably decreased in aging, impacting elimination, and hepatic drug clearance has been shown to decrease in older individuals by 10-40% for most drugs studied. Lower doses of phenothiazines, butyrophenones, atypical antipsychotics, antidepressants (citalopram, mirtazapine, and tricyclic antidepressants), and benzodiazepines (such as diazepam) achieve the same extent of exposure. For renally cleared drugs with no prior metabolism (such as gabapentin), the glomerular filtration rate appropriately estimates drug clearance. Important pharmacodynamic changes in older adults include an increased sedative effect of benzodiazepines at a given drug exposure, and a higher sensitivity to mu opiate receptor agonists and to opioid adverse effects. Artificial intelligence, physiologically based pharmacokinetic modeling and simulation, and concentration-effect modeling enabling a differentiation between the pharmacokinetic and the pharmacodynamic effects of aging might help to close some of the gaps in knowledge.

Revisiting the Effect of Aging on the Transport of Molecules through the Skin

Both intrinsic and extrinsic aging lead to a series of morphological changes in the skin including the flattening of the dermal-epidermal junction, increased stratum corneum dryness, reduction in sebaceous gland activity and enzyme activity as well as atrophy of blood vessels. In this study, the impact of these changes on the transport of molecules through the skin was revised. The increase in the number of transdermal formulations on the market in recent decades and life expectancy represent the main reasons for an in-depth discussion of this topic. Furthermore, elderly subjects have often been excluded from clinical trials due to polypharmacy, raising concerns in terms of efficacy and safety. In this way, ex vivo and in vivo studies comparing the transport of molecules through the mature and young skin were analyzed in detail. The reduced water content in mature skin had a significant impact on the transport rate of hydrophilic molecules. The lower enzymatic activity in aged skin, in turn, would explain changes in the activation of prodrugs. Interestingly, greater deposition of nanoparticles was also found in mature skin. In vivo models should be prioritized in future experimental studies as they allow to evaluate both absorption and metabolism simultaneously, providing more realistic information.

Skin Color Analysis of Various Body Parts (Forearm, Upper Arm, Elbow, Knee, and Shin) and Changes with Age in 53 Korean Women, Considering Intrinsic and Extrinsic Factors

Background/Objectives: Skin color is innately determined by race and other genetic factors, and it also undergoes acquired changes due to various intrinsic and extrinsic factors. Previous studies on skin color have mainly focused on the face, and research has recently expanded to other body parts. However, there is limited information about the age-dependent changes in the skin color of these body parts. The purpose of this study is to analyze the differences in skin color between various body parts and the changes in skin color of each body part with age. Methods: This study examined the skin color of 53 Korean women subjects evenly distributed in age from the 20s to 60s on several body parts: forearm, upper arm, elbow (extended or folded), knee (extended or folded), thigh, and shin. The lightness (L*), redness (a*), and yellowness (b*) were measured using a spectrophotometer, and the individual typology angle (ITA°) was calculated from the L* and b* values. The melanin index and erythema index were measured using the mexameter. Results: The results showed that the elbow skin had the lowest L* and ITA° values and the highest a* and b* values among the examined body parts, followed by the knee. The melanin index and erythema index were also high in the skin of these body parts. In the analysis of age-dependent changes in the skin color of various body parts, the forearm skin exhibited the most notable decrease in the L* and ITA° values and increases in the a* and b* values, followed by upper-arm skin. The melanin and erythema indices in the forearm also increased as the subjects aged, whereas those in the elbow and knee rather decreased with age. Conclusions: This study suggests that differences in intrinsic and extrinsic skin aging in various body parts may be expressed as different changes in skin color and raises the need for cosmetic and dermatological research to identify the physiological significance of these changes.

Polysaccharides from shell waste of shellfish and their applications in the cosmeceutical industry: A review

Shell waste from shellfish processing contains valuable natural polysaccharides, including sulfated polysaccharides, acidic polysaccharides, glycosaminoglycans, chitin and their derivatives. These shellfish waste-derived polysaccharides have numerous functional and biological properties that can be applied in various industries, including the cosmeceutical industry. In keeping with global sustainability and green industry trends, the cosmeceuticals industry is transitioning from petrochemical-based ingredients to natural substitutes. In this context, shell waste-derived polysaccharides and their derivatives can play a major role as natural substitutes for petroleum-based components in various cosmeceutical skincare, hair care, oral care and body care products. This review focuses on the presence of polysaccharides and their derivatives in shell waste and discusses their various cosmeceutical applications in skin care, hair care, sun care, oral care and body care products. This indicates that shell waste utilization will help create a circular economy in which extracted polysaccharides are used to produce green cosmeceutical products.