Hallmarks and Biomarkers of Skin Senescence: An Updated Review of Skin Senotherapeutics

BAK and ARG Have Moisturizing, Anti-Inflammatory, Antioxidant, and Antioxidant Bioactivities, in the Zebrafish Model

BACKGROUND

Bakuchiol (BAK) and acetyl hexapeptide-8 have favorable biological activities and have promising applications in the cosmetic industry. However, the evaluation of the biological activity of both alone or in combination has not been reported.

AIMS

The biological activity of both alone or in combination was evaluated based on the zebrafish model.

METHODS

Zebrafish embryos were induced to form models using different methods. Add BAK and Argireline YOUth peptide oil solution MB (ARG, containing 0.125% acetyl hexapeptide-8) to treat zebrafish embryos, and they were evaluated for their restorative effects on preexisting damage in zebrafish embryos.

RESULTS

BAK and ARG were able to reduce water loss from the caudal fin of zebrafish induced by 0.9% NaCl solution. They were able to alleviate the UVB-induced decrease in the expression level of the skin tightness-related gene (ELN/COL1a1b) in zebrafish embryos, and BAK or ARG effectively reversed the increase in β-galactosidase activity induced by exposure to H2O2 solution and restored telomerase activity in zebrafish embryos. In addition, both were able to counteract oxidative stress and mitochondrial damage in zebrafish embryos as a result of LPS treatment. Finally, BAK and ARG were also effective in suppressing the increase in neutrophil counts and inflammatory cytokine levels in zebrafish embryos due to LPS exposure. Notably, BAK and ARG were more effective when used in combination.

CONCLUSIONS

Acetyl hexapeptide-8 promotes the bioactivity of BAK in zebrafish embryos (Danio rerio). BAK and ARG have moisturizing, anti-inflammatory, antioxidant, and antioxidant bioactivities in the zebrafish model.

In Vitro, Ex Vivo, Instrumental, and Clinical Assessment of a Novel Anti-aging Serum Targeting Oxidative Stress

BACKGROUND

Primarily driven by oxidative stress, aging results from the attrition of cells, aggravated by environmental stressors. Therefore, protection from oxidative stress is the main target of antiaging cosmetics.

AIMS

To evaluate the efficacy of a unique cosmetic serum combining five antioxidants and hyaluronic acid.

METHODS

The inactivation of reactive oxygen species by the serum was evaluated in-tubo. IL-1α release was evaluated using EpiDermTM skin models, while gene expression analysis and elastin fiber length were evaluated on human skin explants. Finally, the effect of twice daily serum application for 28 days was compared to those induced by a control serum, focusing on instrumental and assessor evaluations.

RESULTS

In-tubo, the serum reduces reactive oxygen species by 45.2%. A single topical application on EpiDermTM skin models limits UV-induced ROS-mediated IL-1α release. Compared to untreated explants, HB-EGF (heparin-binding epidermal growth factor) skin homeostasis marker expression increases by 22-fold with treatment. Additionally, the serum increases elastin fiber length by 40.2%. Clinically, twice daily application of the serum over a period of 7 days revealed significant improvements in clinical scoring of skin's wrinkle (-12.8%), smoothness (+12.5%), and radiance (+22.2%). The serum also leads to a rapid and long-lasting increase in skin hydration (30 min: +50.5%, 28 days: +19.9%) and reduced transepidermal water loss (30 min: -7.7%, 28 days: -8.7%). The serum is highly efficacious and well tolerated by the subjects.

CONCLUSION

The serum has antioxidant, soothing, photoprotective, and moisturizing properties that can be explained by the individual properties of its unique blend of actives.

Innovative Plant Exosome Delivery System for Enhancing Antiaging Potency on Skin

Plant exosomes, small vesicles released by plant cells that contain various bioactive molecules, have garnered great attention for their potential applications in medicine, yet their delivery applications for skincare remain underexploited. Resveratrol (RES), renowned for its remarkable antiaging properties, faces challenges in transdermal absorption due to the stratum corneum barrier, hindering its efficacy. To address this, we developed a delivery system incorporating RES-loaded plant (Leontopodium alpinum) exosome (LEOEXO@RES). Evaluation through both in vitro and in vivo experiments demonstrated LEOEXO@RES's enhanced delivery of bioactive compounds and multifaceted skincare impact. Specifically, this approach not only promoted environmentally responsible waste reuse but also achieved harmonious synergy between LEOEXO carriers and RES, enhancing their overall efficacy. The LEOEXO@RES effectively ameliorated inflammation levels and inhibited cellular senescence, highlighting its promising potential in antiaging skincare applications.

Senescence as a molecular target in skin aging and disease

Skin aging represents a multifactorial process influenced by both intrinsic and extrinsic factors, collectively known as the skin exposome. Cellular senescence, characterized by stable cell cycle arrest and secretion of pro-inflammatory molecules, has been implicated as a key driver of physiological and pathological skin aging. Increasing evidence points towards the role of senescence in a variety of dermatological diseases, where the accumulation of senescent cells in the epidermis and dermis exacerbates disease progression. Emerging therapeutic strategies such as senolytics and senomorphics offer promising avenues to target senescent cells and mitigate their deleterious effects, providing potential treatments for both skin aging and senescence-associated skin diseases. This review explores the molecular mechanisms of cellular senescence and its role in promoting age-related skin changes and pathologies, while compiling the observed effects of senotherapeutics in the skin and discussing the translational relevance.

A subset of human dermal fibroblasts overexpressing Cockayne syndrome group B protein resist UVB radiation-mediated premature senescence

Ultraviolet B (UVB) radiation is a major contributor to skin photoaging. Although mainly absorbed by the epidermis, UVB photons managing to penetrate the upper dermis affect human dermal fibroblasts (HDFs), leading, among others, to the accumulation of senescent cells. In vitro studies have shown that repeated exposures to subcytotoxic UVB radiation doses provoke HDFs' premature senescence shortly after the end of the treatment period. Here, we found that repetitive exposures to non-cytotoxic UVB radiation doses after several days lead to mixed cultures, containing both senescent cells and fibroblasts resisting senescence. "Resistant" fibroblasts were more resilient to a novel intense UVB radiation stimulus. RNA-seq analysis revealed that ERCC6, encoding Cockayne syndrome group B (CSB) protein, is up-regulated in resistant HDFs compared to young and senescent cells. CSB was found to be a key molecule conferring protection toward UVB-induced cytotoxicity and senescence, as siRNA-mediated CSB loss-of-expression rendered HDFs significantly more susceptible to a high UVB radiation dose, while cells from a CSB-deficient patient were found to be more sensitive to UVB-mediated toxicity, as well as senescence. UVB-resistant HDFs remained normal (able to undergo replicative senescence) and non-tumorigenic. Even though they formed a distinct population in-between young and senescent cells, resistant HDFs retained numerous tissue-impairing characteristics of the senescence-associated secretory phenotype, including increased matrix metalloprotease activity and promotion of epidermoid tumor xenografts in immunodeficient mice. Collectively, here we describe a novel subpopulation of HDFs showing increased resistance to UVB-mediated premature senescence while retaining undesirable traits that may negatively affect skin homeostasis.

Low-temperature cold plasma promotes wound healing by inhibiting skin inflammation and improving skin microbiome

Wound healing includes four consecutive and overlapping stages of hemostasis, inflammation, proliferation, and remodeling. Factors such as aging, infection, and chronic diseases can lead to chronic wounds and delayed healing. Low-temperature cold plasma (LTCP) is an emerging physical therapy for wound healing, characterized by its safety, environmental friendliness, and ease of operation. This study utilized a self-developed LTCP device to investigate its biological effects and mechanisms on wound healing in adult and elderly mice. Histopathological studies found that LTCP significantly accelerated the healing rate of skin wounds in mice, with particularly pronounced effects in elderly mice. LTCP can markedly inhibit the expression of pro-inflammatory cytokines (TNF-α, IL-6, IL-1β) and senescence-associated secretory phenotype factors (MMP-3, MMP-9), while significantly increasing the expression of tissue repair-related factors, such as VEGF, bFGF, TGF-β, COL-I, and α-SMA. It also regulated the expression of genes related to cell proliferation and migration (Aqp5, Spint1), inflammation response (Nlrp3, Icam1), and angiogenesis (Ptx3, Thbs1), promoting cell proliferation and inhibit apoptosis. Furthermore, LTCP treatment reduced the relative abundance of harmful bacteria such as Delftia, Stenotrophomonas, Enterococcus, and Enterobacter in skin wounds, while increasing the relative abundance of beneficial bacteria such as Muribaculaceae, Acinetobacter, Lachnospiraceae NK4A136_group, and un_f__Lachnospiraceae, thereby improving the microbial community structure of skin wounds. These research findings are of significant implications for understanding the mechanism of skin wound healing, as well as for the treatment and clinical applications of skin wounds, especially aging skin.

TriHex 2.0-Advancing Skin Health Science and the TriHex Technology

BACKGROUND

The original TriHex combination-Tripeptide-1 and Hexapeptide-12 (TriHex) encompasses a peptide combination selected for its ability to modulate the extracellular matrix (ECM) by progressively eliminating clumped collagen and elastin fragments and then stimulating replacement with new collagen and elastin. Incorporation of a proprietary, patent-pending Octapeptide-45 (Octa) to the TriHex original provides potential for added benefit based on the peptide's capacity to stimulate hyaluronic acid (HA) and its anticipated added benefit in wound healing. This is named TriHex 2.0 in the paper.

MATERIALS AND METHODS

A full-scale validation process was structured to assess Octa synergy with TriHex using an ex vivo model, assessing ECM changes histologically in relation to elastin, HA and basement membrane components. In addition, gene expression studies were undertaken, including bulk and single cell sequencing analysis to assess the particular changes that occurred by adding Octa to the TriHex. Following the gene expression analysis, a further round of ex vivo studies was conducted to assess protein expression of the defined differentially expressed genes using histological staining.

RESULTS

Octa synergized with TriHex as demonstrated by significantly upregulated genes (p < 0.05) affecting the ECM and basement membrane. A histological assessment using the ex vivo model demonstrated tropoelastin intensity significantly increasing with TriHex (43%) and 2.0 (42%) (p < 0.05 for both) compared to untreated explants. HA levels (CD44 intensity) significantly increased with TriHex (69%; p < 0.01), while TriHex 2.0 demonstrated HA levels 160% greater (p < 0.001) than the untreated tissue. Single cell sequencing identified a gene expression profile upregulation relating to ECM modulation and wound healing in both TriHex and 2.0, but TriHex 2.0 showed additional activities in basement membrane physiology, stem cell recruitment, and protection of fibroblasts against cellular senescence.

CONCLUSION

The addition of Octapeptide-45 to TriHex technology in the form of TriHex 2.0 is a significant advance to TriHex technology science. Both forms demonstrate ECM remodeling and positive wound healing, but supplementary benefits are evident including increased elastin and hyaluronic acid stimulation, added effects on the basement membrane, additional wound healing capacity in basal keratinocytes and anti-senescent effects in fibroblasts. This is helpful for pre-conditioning of the skin prior to procedures and post procedure related to additional ECM remodeling, wound healing advantages, senescent cell targeting and DEJ strengthening. Clinical studies to follow.

Diosmetin Delays In Vitro Aging of Porcine Oocytes by Improving Mitochondrial Function and Reducing Oxidative Stress

Oocyte quality is crucial for successful fertilization and subsequent embryonic development. Post-ovulatory aging leads to reduced oocyte quality and impaired embryogenesis, representing an unavoidable challenge in terms of certain assisted reproductive techniques. Diosmetin (DIOS), a natural flavonoid found in lemons, spearmint, and spider moss, exhibits antioxidant, anti-inflammatory, and anti-apoptotic properties. However, its effects on the aging of mature porcine oocytes in vitro remain unexplored. This study investigated the impact of DIOS on porcine oocyte aging. In the IVM medium, fresh oocytes were cultured for 44 h, while aging oocytes were cultured for 68 h. Following the addition of varying DIOS concentrations (0.01, 0.1, and 1 μM) to the IVM medium, the DIOS-treated aging oocyte group was cultured for 68 h. The results demonstrated that 0.1 μM DIOS significantly improved the blastocyst rates and cell counts, reduced the reactive oxygen species (ROS), elevated the glutathione (GSH) levels, enhanced the mitochondrial function, and decreased the markers of autophagy (LC3B), apoptosis (annexin V), endoplasmic reticulum stress (CHOP), and senescence (SA-β-Gal). Furthermore, DIOS treatment upregulated the expression of relevant genes compared to the aged group. These findings suggest that DIOS effectively delays porcine oocyte aging.

Senolytic Vaccines from the Central and Peripheral Tolerance Perspective

Preventive medicine has proven its long-term effectiveness and economic feasibility. Over the last century, vaccination has saved more lives than any other medical technology. At present, preventative measures against most infectious diseases are successfully used worldwide; in addition, vaccination platforms against oncological and even autoimmune diseases are being actively developed. At the same time, the development of medicine led to an increase in both life expectancy and the proportion of age-associated diseases, which pose a heavy socio-economic burden. In this context, the development of vaccine-based approaches for the prevention or treatment of age-related diseases opens up broad prospects for extending the period of active longevity and has high economic potential. It is well known that the development of age-related diseases is associated with the accumulation of senescent cells in various organs and tissues. It has been demonstrated that the elimination of such cells leads to the restoration of functions, rejuvenation, and extension of the lives of experimental animals. However, the development of vaccines against senescent cells is complicated by their antigenic heterogeneity and the lack of a unique marker. In addition, senescent cells are the body's own cells, which may be the reason for their low immunogenicity. This mini-review discusses the mechanisms of central and peripheral tolerance that may influence the formation of an anti-senescent immune response and be responsible for the accumulation of senescent cells with age.

Senescence-like Phenotype After Chronic Exposure to Isoproterenol in Primary Quiescent Immune Cells

Chronic stress is associated with a higher risk for carcinogenesis as well as age-related diseases and immune dysfunction. There is evidence showing that psychological stress can contribute to premature immunosenescence. Therefore, the question arose whether chronic exposure to catecholamine could drive immune cells into senescence. Peripheral blood mononuclear cells were isolated from whole blood. After repeated ex vivo treatment with isoproterenol, an epinephrine analog, well-established senescence biomarkers were assessed. We found (i) DNA double-strand break induction, (ii) telomere shortening, (iii) failure to proliferate, (iv) higher senescence-associated β-galactosidase activity, (v) decreases in caspases 3 and 7 activity, and (vi) strong upregulation of the proteoglycan versican accompanied by increased cellular adhesion suggesting the induction of a senescence-like phenotype. These results emphasize the complexity of the effect of isoproterenol on multiple cellular processes and provide insights into the molecular mechanisms of stress leading to immunosenescence.

The Senolytic Effect of Indole-3-Carbinol (I3C) on Mouse Embryonic (MEF) and Human Fibroblast Cell Lines

Senescence and apoptosis are two fundamental cellular processes that play crucial roles in various physiological and pathological conditions. Senescence refers to the irreversible growth arrest that cells undergo in response to various stimuli, including telomeric alterations, stress, and oncogenic signaling. Pharmacological and/or genetic removal of senescent cells, also referred to as senolysis, triggers organ rejuvenation and tissue regeneration. Indole-3-carbinol (I3C) is a natural compound contained in Brassicaceae plants and identified in multiple in vitro and in vivo studies as a well-tolerated and effective compound in cancer prevention and therapy. Its anti-cancer properties have been attributed at least in part to its inhibitory activity of proto-oncogenic HECT E3-ubiquitin ligases such as NEDD4 and WWP1. While the tumor suppressive effects of I3C in cancer cell lines have been reported in multiple studies, little is known regarding the biological effects of I3C in primary normal cells, which attain spontaneous cellular senesce over serial passaging. To this end, we used two model systems: mouse embryonic fibroblasts (MEFs) and human primary dermal fibroblasts. Here, we surprisingly show that I3C does increase cellular senescence at early passages, while dramatically reducing the number of senescent cells through the induction of apoptosis in both mouse and human primary cells. Thus, our findings support the notion that I3C acts as a senolytic compound with important therapeutic implications for the prevention and treatment of aging manifestations. The notion can be readily tested in future clinical trials in humans also in view of the high tolerability and safety previously displayed by I3C in preclinical and clinical studies.

SIRT6 alleviates senescence induced by Porphyromonas gingivalis in human gingival fibroblasts

OBJECTIVE

Bidirectional influences between senescence and inflammation are newly discovered. This study aimed to clarify the roles and mechanism of Porphyromonas gingivalis (P. gingivalis) in exacerbating senescence in human gingival fibroblasts (HGFs).

DESIGN

Subgingival plaque and gingivae were collected from twenty-four periodontitis patients and eighteen periodontally healthy subjects. Quantities of P. gingivalis in subgingival plaque were explored using real-time PCR and the expressions of p53, p21 and SIRT6 in gingivae were detected by IHC. Moreover, senescence in HGFs was induced by P. gingivalis lipopolysaccharide (LPS) and the expressions of senescence-related β-galactosidase (SA-β-gal), p53, p21 and senescence-associated secretory phenotype (IL-6 and IL-8) with or without treatment by SIRT6 activator UBCS039 were explored by IHC, western blot and ELISA, respectively. In addition, the levels of SIRT6, Nrf2, HO-1 and reactive oxygen species (ROS) were examined by western blot and flow cytometry.

RESULTS

Quantities of P. gingivalis in subgingival plaque and semi-quantitative scores of p53 and p21 in gingivae of periodontitis patients were increased compared with healthy controls (p < 0.05), while SIRT6 score in periodontitis patients was decreased (p < 0.001). Quantities of P. gingivalis were positively correlated with p53 and p21 scores (0.6 < r < 0.9, p < 0.01), and negatively correlated with SIRT6 score (-0.9 < r<-0.6, p < 0.01). Moreover, P. gingivalis LPS increased the levels of SA-β-gal, p53, p21, IL-6, IL-8 and ROS and decreased the levels of SIRT6, Nrf2 and HO-1 in HGFs, which was rescued by UBCS039 (p < 0.05).

CONCLUSIONS

P. gingivalis LPS could induce senescence of HGFs, which could be reversed by SIRT6 via Nrf2-HO-1 signaling pathway.

Mechanisms of Senescence and Anti-Senescence Strategies in the Skin

The skin is the layer of tissue that covers the largest part of the body in vertebrates, and its main function is to act as a protective barrier against external environmental factors, such as microorganisms, ultraviolet light and mechanical damage. Due to its important function, investigating the factors that lead to skin aging and age-related diseases, as well as understanding the biology of this process, is of high importance. Indeed, it has been reported that several external and internal stressors contribute to skin aging, similar to the aging of other tissues. Moreover, during aging, senescent cells accumulate in the skin and express senescence-associated factors, which act in a paracrine manner on neighboring healthy cells and tissues. In this review, we will present the factors that lead to skin aging and cellular senescence, as well as ways to study senescence in vitro and in vivo. We will further discuss the adverse effects of the accumulation of chronic senescent cells and therapeutic agents and tools to selectively target and eliminate them.

Anti-Aging Effects of Flavonoids from Plant Extracts

Aging is a natural and irreversible process, affecting living organisms by negatively impacting the tissues' and cells' morphology and functionality and consequently being responsible for aging-related diseases. Taking into account the actual preoccupations of both consumers and researchers, healthy anti-aging alternatives are being intensively studied in order to address such concerns. Due to their functional features, plant flavonoids can be considered valuable nutraceuticals. This paper highlights the possibilities to use flavonoids extracted from various plants for their anti-aging potential on the skin, brain, and heart. Moreover, their anticarcinogenic, anti-inflammatory, and anti-diabetic properties are summarized, along with the senescence-associated mechanisms. Both the nutraceutical and cosmeceutical fields are continuously developing and flavonoids originating from plants are promising candidates to obtain such products. Thus, the bioactive compounds' extraction and their subsequent involvement in innovative product manufacturing must be carefully performed while being aware of the various intrinsic and extrinsic factors that may affect the phytochemicals' structures, bioavailability, and health effects.

Senomorphic activity of a combination of niacinamide and hyaluronic acid: correlation with clinical improvement of skin aging

Intrinsic and extrinsic factors, including lifestyle and sun exposure, can contribute to cell senescence, which impairs skin homeostasis, that may in turn lead to skin aging. Senescent cells have a specific secretome, called the senescence-associated secretory phenotype (SASP) that includes MMPs, CXCLs and S100A8/9. Reducing the SASP with senotherapeutics is a promising strategy to reduce skin aging. Here we evaluated the effect of a formula containing niacinamide and hyaluronic acid, which are known to limit senescence and skin aging. We conducted three different studies. (1) Ex vivo explants treated with the formula had more collagen and glycosaminoglycan. (2) In a clinical trial with forty-four women, two months of treatment improved fine lines, wrinkles, luminosity, smoothness, homogeneity, and plumpness. (3) In a third study on thirty women, we treated one arm for two months and took skin biopsies to study gene expression. 101 mRNAs and 13 miRNAs were differentially expressed. We observed a likely senomorphic effect, as there was a decrease in many SASP genes including MMP12 and CXCL9 and a significant downregulation of autocrine signaling genes: S100A8 and S100A9. These pharmaco-clinical results are the first to demonstrate the senomorphic properties of an effective anti-aging formula in skin.

Nicotinamide N-Methyltransferase (NNMT): A New Hope for Treating Aging and Age-Related Conditions

The complex process of aging leads to a gradual deterioration in the function of cells, tissues, and the entire organism, thereby increasing the risk of disease and death. Nicotinamide N-methyltransferase (NNMT) has attracted attention as a potential target for combating aging and its related pathologies. Studies have shown that NNMT activity increases over time, which is closely associated with the onset and progression of age-related diseases. NNMT uses S-adenosylmethionine (SAM) as a methyl donor to facilitate the methylation of nicotinamide (NAM), converting NAM into S-adenosyl-L-homocysteine (SAH) and methylnicotinamide (MNA). This enzymatic action depletes NAM, a precursor of nicotinamide adenine dinucleotide (NAD+), and generates SAH, a precursor of homocysteine (Hcy). The reduction in the NAD+ levels and the increase in the Hcy levels are considered important factors in the aging process and age-related diseases. The efficacy of RNA interference (RNAi) therapies and small-molecule inhibitors targeting NNMT demonstrates the potential of NNMT as a therapeutic target. Despite these advances, the exact mechanisms by which NNMT influences aging and age-related diseases remain unclear, and there is a lack of clinical trials involving NNMT inhibitors and RNAi drugs. Therefore, more in-depth research is needed to elucidate the precise functions of NNMT in aging and promote the development of targeted pharmaceutical interventions. This paper aims to explore the specific role of NNMT in aging, and to evaluate its potential as a therapeutic target.

Topical Minoxidil Rejuvenates Hair Follicles from Men with Androgenetic Alopecia in Vivo

Abstract is missing (Short communication)

Aging of Superficial Musculoaponeurotic System of the Face-Novel Biomarkers and Micro-CT Relevance of Facial Anti-Gravity Support

The soft superficial tissues of the face are against gravity through an intricate network of ligaments and ligamentous attachments. The aim of this investigation is to delineate the relationship between the muscular, fibrous, and vascular components of the superficial musculoaponeurotic system of the face (SMAS) at the level of its periosteal fixation areas from advanced radiological and novel biomarkers' perspectives. These areas represent key points underlying skin aging and the longevity of restorative surgery results. Methods: This study was carried out on 37 surgical specimens, excised from patients admitted for surgery. On the excised specimens, we used special immunohistochemical techniques, such as markers for collagen type III, angiogenesis, vascular endothelium (I-CAM2) and muscle fibers (MYH2). We performed a micro-CT evaluation of these 37 specimens. Results: The results of this study showed different radiologic and IHC characteristics of the means of periosteal fixation of the SMAS. Evidence of morphohistological and radiological peculiarities of the retaining ligaments highlights new data for future functional studies of these structures. Our research must be continued with larger groups of subjects and through detailed methodological studies of vascular microperfusion and could represent an important new step in biotissue engineering and the customization of surgical techniques involving the sub-SMAS layers.

Dietary supplementation with α-ionone alleviates chronic UVB exposure-induced skin photoaging in mice

Photoaging is widely regarded as the most significant contributor to skin aging damage. It is triggered by prolonged exposure to ultraviolet (UV) light and typically manifests as dryness and the formation of wrinkles. Nutritional intervention is a viable strategy for preventing and treating skin photoaging. In previous studies, we demonstrated that α-ionone had ameliorating effects on photoaging in both epidermal keratinocytes and dermal fibroblasts. Here, we investigated the potential anti-photoaging effects of dietary α-ionone using a UVB-irradiated male C57BL/6N mouse model. Our findings provided compelling evidence that dietary α-ionone alleviates wrinkle formation, skin dryness, and epidermal thickening in chronic UVB-exposed mice. α-Ionone accumulated in mouse skin after 14 weeks of dietary intake of α-ionone. α-Ionone increased collagen density and boosted the expression of collagen genes, while attenuating the UVB-induced increase of matrix metalloproteinase genes in the skin tissues. Furthermore, α-ionone suppressed the expression of senescence-associated secretory phenotypes and reduced the expression of the senescence marker p21 and DNA damage marker p53 in the skin of UVB-irradiated mice. Transcriptome sequencing results showed that α-ionone modifies gene expression profiles of skin. Multiple pathway enrichment analyses on both the differential genes and the entire genes revealed that α-ionone significantly affects multiple physiological processes and signaling pathways associated with skin health and diseases, of which the p53 signaling pathway may be the key signaling pathway. Taken together, our findings reveal that dietary α-ionone intervention holds promise in reducing the risks of skin photoaging, offering a potential strategy to address skin aging concerns.

The Role of p53 in Regulating Chronic Inflammation and PANoptosis in Diabetic Wounds

Diabetic wounds represent a formidable challenge in the clinical management of diabetes mellitus, markedly diminishing the patient's quality of life. These wounds arise from a multifaceted etiology, with the pathophysiological underpinnings remaining elusive and complex. Diabetes precipitates neuropathies and vasculopathies in the lower extremities, culminating in infections, ulcerations, and extensive tissue damage. The hallmarks of non-healing diabetic wounds include senescence, persistent inflammation, heightened apoptosis, and attenuated cellular proliferation. The TP53 gene, a pivotal tumor suppressor frequently silenced in human malignancies, orchestrates cellular proliferation, senescence, DNA repair, and apoptosis. While p53 is integral in cell cycle regulation, its role in initial tissue repair appears to be deleterious. In typical cutaneous wounds, p53 levels transiently dip, swiftly reverting to baseline. Yet in diabetic wounds, protracted p53 activation impedes healing via two distinct pathways: i) activating the p53-p21-Retinoblastoma (RB) axis, which halts the cell cycle, and ii) upregulating the cGAS-STING and nuclear factor-kappaB (NF-κB) cascades, instigating ferroptosis and pyroptosis. Furthermore, p53 intersects with various metabolic pathways, including glycolysis, gluconeogenesis, oxidative phosphorylation, and autophagy. In diabetic wounds, p53 may drive metabolic reprogramming, thus potentially derailing macrophage polarization. This review synthesizes case studies investigating the therapeutic modulation of p53 in diabetic wounds care. In summation, p53 modulates chronic inflammation and cellular aging within diabetic cutaneous wounds and is implicated in a novel cell death modality, encompassing ferroptosis and pyroptosis, which hinders the reparative process.

Cutaneous Redox Senescence

Our current understanding of skin cell senescence involves the role of environmental stressors (UV, O3, cigarette smoke, particulate matter, etc.), lifestyle (diet, exercise, etc.) as well as genetic factors (metabolic changes, hormonal, etc.). The common mechanism of action of these stressors is the disturbance of cellular redox balance characterized by increased free radicals and reactive oxygen species (ROS), and when these overload the intrinsic antioxidant defense system, it can lead to an oxidative stress cellular condition. The main redox mechanisms that activate cellular senescence in the skin involve (1) the oxidative damage of telomeres causing their shortening; (2) the oxidation of proteomes and DNA damage; (3) an a in lysosomal mass through the increased activity of resident enzymes such as senescence-associated β-galactosidase (SA-β-gal) as well as other proteins that are products of lysosomal activity; (4) and the increased expression of SASP, in particular pro-inflammatory cytokines transcriptionally regulated by NF-κB. However, the main targets of ROS on the skin are the proteome (oxi-proteome), followed by telomeres, nucleic acids (DNAs), lipids, proteins, and cytoplasmic organelles. As a result, cell cycle arrest pathways, lipid peroxidation, increased lysosomal content and dysfunctional mitochondria, and SASP synthesis occur. Furthermore, oxidative stress in skin cells increases the activity of p16INK4A and p53 as inhibitors of Rb and CDks, which are important for maintaining the cell cycle. p53 also promotes the inactivation of mTOR-mediated autophagic and apoptotic pathways, leading to senescence. However, these markers alone cannot establish the state of cellular senescence, and multiple analyses are encouraged for confirmation. An updated and more comprehensive approach to investigating skin senescence should include further assays of ox-inflammatory molecular pathways that can consolidate the understanding of cutaneous redox senescence.

Revitalizing Photoaging Skin through Eugenol in UVB-Exposed Hairless Mice: Mechanistic Insights from Integrated Multi-Omics

Chronic ultraviolet (UV) exposure causes photoaging, which is primarily responsible for skin damage. Nutritional intervention is a viable strategy for preventing and treating skin photoaging. Eugenol (EU) presents anti-inflammatory and antioxidant properties, promotes wound healing, and provides contact dermatitis relief. This study explored the ability of EU to mitigate skin photoaging caused by UVB exposure in vitro and in vivo. EU alleviated UVB-induced skin photodamage in skin cells, including oxidative stress damage and extracellular matrix (ECM) decline. Dietary EU alleviated skin photoaging by promoting skin barrier repair, facilitating skin tissue regeneration, and modulating the skin microenvironment in photoaged mice. The transcriptome sequencing results revealed that EU changed the skin gene expression profiles. Subsequent pathway enrichment analyses indicated that EU might reverse the pivotal ECM-receptor interaction and cytokine-cytokine receptor interaction signaling pathways. Furthermore, EU alleviated the intestinal dysbiosis induced by chronic UVB exposure. Spearman analysis results further revealed the close connection between gut microbiota and skin photoaging. Considering the near-inevitable UVB exposure in modern living, the findings showed that the EU effectively reverted skin photoaging, offering a potential strategy for addressing extrinsic skin aging.

Hesperetin activates CISD2 to attenuate senescence in human keratinocytes from an older person and rejuvenates naturally aged skin in mice

BACKGROUND

CDGSH iron-sulfur domain-containing protein 2 (CISD2), a pro-longevity gene, mediates healthspan in mammals. CISD2 is down-regulated during aging. Furthermore, a persistently high level of CISD2 promotes longevity and ameliorates an age-related skin phenotype in transgenic mice. Here we translate the genetic evidence into a pharmaceutical application using a potent CISD2 activator, hesperetin, which enhances CISD2 expression in HEK001 human keratinocytes from an older person. We also treated naturally aged mice in order to study the activator's anti-aging efficacy.

METHODS

We studied the biological effects of hesperetin on aging skin using, firstly, a cell-based platform, namely a HEK001 human keratinocyte cell line established from an older person. Secondly, we used a mouse model, namely old mice at 21-month old. In the latter case, we investigate the anti-aging efficacy of hesperetin on ultraviolet B (UVB)-induced photoaging and naturally aged skin. Furthermore, to identify the underlying mechanisms and potential biological pathways involved in this process we carried out transcriptomic analysis. Finally, CISD2 knockdown HEK001 keratinocytes and Cisd2 knockout mice were used to study the Cisd2-dependent effects of hesperetin on skin aging.

RESULTS

Four findings are pinpointed. Firstly, in human skin, CISD2 is mainly expressed in proliferating keratinocytes from the epidermal basal layer and, furthermore, CISD2 is down-regulated in the sun-exposed epidermis. Secondly, in HEK001 human keratinocytes from an older person, hesperetin enhances mitochondrial function and protects against reactive oxygen species-induced oxidative stress via increased CISD2 expression; this enhancement is CISD2-dependent. Additionally, hesperetin alleviates UVB-induced damage and suppresses matrix metalloproteinase-1 expression, the latter being a major indicator of UVB-induced damage in keratinocytes. Thirdly, transcriptomic analysis revealed that hesperetin modulates a panel of differentially expressed genes that are associated with mitochondrial function, redox homeostasis, keratinocyte function, and inflammation in order to attenuate senescence. Intriguingly, hesperetin activates two known longevity-associated regulators, namely FOXO3a and FOXM1, in order to suppress the senescence-associated secretory phenotype. Finally, in mouse skin, hesperetin enhances CISD2 expression to ameliorate UVB-induced photoaging and this occurs via a mechanism involving CISD2. Most strikingly, late-life treatment with hesperetin started at 21-month old and lasting for 5 months, is able to retard skin aging and rejuvenate naturally aged skin in mice.

CONCLUSIONS

Our results reveal that a pharmacological elevation of CISD2 expression at a late-life stage using hesperetin treatment is a feasible approach to effectively mitigating both intrinsic and extrinsic skin aging and that hesperetin could act as a functional food or as a skincare product for fighting skin aging.

Potential roles of circulating microRNAs in the healing of type 1 diabetic wounds treated with green tea extract: molecular and biochemical study

Background

Circulating miRNAs have been implicated in various aspects of diabetic wound healing, including inflammation, angiogenesis, and extracellular matrix remodeling. Thus, in alternative herbal medicine strategies, miRNAs will be potential therapeutic molecular targets in nonhealing wounds. These could be valuable elements for understanding the molecular basis of diabetic wound healing and could be used as good elements in bioinformatics.

Objectives

To elucidate the molecular mechanisms of microRNAs in association with apoptosis-inducing genes in controlling skin wound healing in diabetic wounds treated with green tea polyphenols (GTPs).

Methods

Green tea hydro extract (GTE) at doses of100-200 mg/ml was topically applied to the skin tissues of rats with T1DM induced by a single dose of streptozotocin (STZ; 100 mg/kg, in 0.01 M sodium citrate, pH 4.3-4.5) injected intraperitoneally for seven consecutive days to induce T1DM. The rats were treated with green tea for three weeks. A sterile surgical blade was used to inflict a circular wound approximately 2 cm in diameter on the anterior-dorsal side of previously anesthetized rats by a combination of ketamine hydrochloride (50 mg/kg, i.e., body weight) and xylazine hydrochloride. Afterward, the molecular roles of the circulating miRNAs miR-21, miR-23a, miR-146a, and miR-29b and apoptotic genes were determined by quantitative real-time PCR to evaluate Bax, Caspase-3, and Bcl-2 in wound healing. In addition, HPLC analysis was also performed to estimate the active polyphenols (GTPs) present in the hydro extract of green tea leaves.

Results

Wound healing was improved in diabetic skin wounds following treatment with GTE at doses of 100-200 mg/dl for three weeks. The wound parameters contraction, epithelialization, and scar formation significantly improved in a short time (14 days) compared to the longer periods identified in diabetic non-treated rats (20 days) and the standard control (15.5 days). Molecular analyses reported a significant increase in the levels of miR-21, miR-23a, and miR-146a and a decrease in the levels of miR-29b in green tea-treated diabetic rats compared to those in the standard control and STZ-diabetic non-treated rats. In addition, the molecular apoptotic genes Bax and caspase-3 significantly increased, and the BcL-2 gene significantly decreased following treatment with green tea polyphenols.

Conclusions

The data showed that active green tea polyphenols (GTPs) present in GTE significantly improved diabetic wound healing by controlling apoptotic genes and the circulating microRNAs miR-21, miR-23a, miR-146a, and miR-29b, which might be involved in cellular apoptosis and angiogenesis processes. Thus, to establish a future model for the treatment of diabetic wounds, further studies are needed to understand the potential association of these biological parameters with the wound-healing process in diabetic wounds.

Inflammaging and Immunosenescence as Part of Skin Aging-A Narrative Review

Inflammaging and immunosenescence are associated with aging of the human body, but there are key differences between them. Immunosenescence aims to adapt the body systems to aging, while inflammaging is considered a consequence of immunosenescence. There has been much research in the area of immunosenescence and inflammaging recently, yet our understanding of aging and the ability to develop interventions to decrease the harmful effect of aging on the human body is insufficient. This review is focused on immunosenescence and inflammaging processes in the skin. We aimed to identify factors that influence inflammaging, skin aging, and their mechanisms. We discussed the role of triggering factors (e.g., UV radiations, changes in bioavailability of nitric oxide, senescence-associated secretory phenotype factors, and reactive oxygen species) and inhibiting factors that can potentially be used as anti-aging treatments, as well as the idea of geroprotectors and senotherapeutics. We concluded that while knowledge on external factors can help people to improve their health conditions, knowledge on biochemical factors can help researchers to understand inflammaging process and develop interventions to minimize the impact of aging on the human body. Further research is needed to better understand the role of factors that can slow down or accelerate inflammaging.