Age-associated reduction of cell spreading induces mitochondrial DNA common deletion by oxidative stress in human skin dermal fibroblasts: implication for human skin connective tissue aging

The total extract of Abelmoschus manihot (L.) medic flowers (TEA) mediated Nrf2-TFAM signalling to regulate mitochondrial antioxidant mechanism

Skin, as the first line of defence of the human body, is exposed to dangers such as overheating substances, ultraviolet rays, and environmental pollutants, and the incidence of skin diseases is increasing annually. Oxidative stress plays a dominant role in most skin diseases. Abelmoschus manihot (L.) medic flower (TEA) is a traditional Chinese medicine widely used to treat injuries to the skin such as water and fire scalds. It has been reported that TEA has excellent antioxidant effects. In this study, we aimed to explore the antioxidant and mitochondrial protection effects of TEA in H2O2-mediated HaCaT cell damage. HaCaT cells were incubated with H2O2 to simulate oxidative stress in the skin. The effect of TEA on HaCaT cells was also evaluated. Cell morphology was observed via inverted microscopy, and cell viability was measured via the MTT reagent. The cells were stained with Hoechst 33,324 solution. Reactive oxygen species (ROS), superoxide dismutase (SOD), malondialdehyde (MDA) and ATP detection kits were used to detect the corresponding indicators. The mitochondrial membrane potential was detected by JC-1. RT-PCR was used to detect mRNA and mtDNA expression. The expression of the target protein was detected by Western blotting and immunofluorescence. H2O2 triggered oxidative damage in HaCaT cells, which manifested as apoptosis, increased ROS and MDA contents, and decreased SOD activity. H2O2 activates the KEAP1/Nrf2/NQO1 signalling pathway, which decreases the expression of the intracellular KEAP1 protein and slightly increases the expression of the Nrf2 and NQO1 proteins, further causing mitochondrial oxidative stress, resulting in changes in the mitochondrial membrane potential, a reduction in the mtDNA copy number, and decreased expression of the PGC-1α and TFAM proteins. In addition the expression of mitochondrial respiratory chain genes and proteins decreased. TEA promoted the expression of Nrf2 in HaCaT cells, activated the downstream antioxidant response, and alleviated the oxidative stress and mitochondrial damage caused by H2O2. ML385 is an Nrf2 inhibitor, under which the antioxidant and mitochondrial protective effects of TEA are inhibited. When TFAM was knocked down, the protective effect of TEA on mitochondria was also inhibited. TEA protects HaCaT cells from H2O2-induced oxidative damage and mitochondrial oxidative damage through the KEAP1/Nrf2/NQO1/PGC-1α/TFAM pathway.

Tailoring biomaterials for skin anti-aging

Skin aging is the phenomenon of degenerative changes in the structure and function of skin tissues over time and is manifested by a gradual loss of skin elasticity and firmness, an increased number of wrinkles, and hyperpigmentation. Skin anti-aging refers to a reduction in the skin aging phenomenon through medical cosmetic technologies. In recent years, new biomaterials have been continuously developed for improving the appearance of the skin through mechanical tissue filling, regulating collagen synthesis and degradation, inhibiting pigmentation, and repairing the skin barrier. This review summarizes the mechanisms associated with skin aging, describes the biomaterials that are commonly used in medical aesthetics and their possible modes of action, and discusses the application strategies of biomaterials in this area. Moreover, the synergistic effects of such biomaterials and other active ingredients, such as stem cells, exosomes, growth factors, and antioxidants, on tissue regeneration and anti-aging are evaluated. Finally, the possible challenges and development prospects of biomaterials in the field of anti-aging are discussed, and novel ideas for future innovations in this area are summarized.

Specific Features of the Functional Activity of Human Adipose Stromal Cells in the Structure of a Partial Skin-Equivalent

Mesenchymal adipose stromal cells (ASCs) are considered the most promising and accessible material for translational medicine. ASCs can be used independently or within the structure of scaffold-based constructs, as these not only ensure mechanical support, but can also optimize conditions for cell activity, as specific features of the scaffold structure have an impact on the vital activity of the cells. This manuscript presents a study of the secretion and accumulation that occur in a conditioned medium during the cultivation of human ASCs within the structure of such a partial skin-equivalent that is in contact with it. It is demonstrated that the ASCs retain their functional activity during cultivation both within this partial skin-equivalent structure and, separately, on plastic substrates: they proliferate and secrete various proteins that can then accumulate in the conditioned media. Our comparative study of changes in the conditioned media during cultivation of ASCs on plastic and within the partial skin-equivalent structure reveals the different dynamics of the release and accumulation of such secretory factors in the media under a variety of conditions of cell functioning. It is also demonstrated that the optimal markers for assessment of the ASCs' secretory functions in the studied partial skin-equivalent structure are the trophic factors VEGF-A, HGF, MCP, SDF-1α, IL-6 and IL-8. The results will help with the development of an algorithm for preclinical studies of this skin-equivalent in vitro and may be useful in studying various other complex constructs that include ASCs.

The mitochondrial DNA common deletion as a potential biomarker of cancer-associated fibroblasts from skin basal and squamous cell carcinomas

Cancer-associated fibroblasts (CAFs) are components of the tumor microenvironment and represent appealing therapeutic targets for translational studies. Conventional protein-based biomarkers for CAFs have been reported to be limited in their specificity, rendering difficult the identification of CAFs from normal fibroblasts (NFs) in clinical samples and dampening the development of CAF-targeted therapies to treat cancer. In this study, we propose the mitochondrial RNA and the mitochondrial DNA (mtDNA) common deletion (CD) as novel indicators of CAF identity. We found that cancer-activation correlated with decreased levels of the mtDNA CD, a condition not due to altered mitochondria count or cellular redox state, but potentially linked to the generalized overexpression of mtDNA maintenance genes in CAFs. Decreased mtDNA CD content in CAFs was associated with moderate to strong overexpression of mtDNA-encoded genes and to slightly improved mitochondrial function. We identified similar patterns of upregulation of mtDNA-encoded genes in independent single-cell RNA seq data obtained from squamous cell carcinoma (SCC) patients. By using the identified nucleic acids-based indicators, identification of CAFs from NFs could be improved, leading to potential therapeutic benefits in advancing translational and clinical studies.

Hallmarks of Skin Aging: Update

Aging is defined as impaired physiological integrity, decreased function, increased susceptibility to external risk factors and various diseases. Skin, the largest organ in our body, may become more vulnerable to insult as time goes by and behave as aged skin. Here, we systemically reviewed three categories including seven hallmarks of skin aging. These hallmarks including genomic instability and telomere attrition, epigenetic alterations and loss of proteostasis, deregulated nutrient-sensing, mitochondrial damage and dysfunction, cellular senescence, stem cell exhaustion/dysregulation, and altered intercellular communication. These seven hallmarks can generally be divided into three categories including (i) causes of damages as primary hallmarks in skin aging; (ii) responses to damage as antagonistic hallmarks in skin aging; and (iii) culprits of the phenotype as integrative hallmarks in skin aging.

Endoplasmic reticulum stress and alterations of peroxiredoxins in aged hearts

Aging-related cardiovascular disease is influenced by multiple factors, with oxidative stress being a key contributor. Aging-induced endoplasmic reticulum (ER) stress exacerbates oxidative stress by impairing mitochondrial function. Furthermore, a decline in antioxidants, including peroxiredoxins (PRDXs), augments the oxidative stress during aging. To explore if ER stress leads to PRDX degradation during aging, young adult (3 mo.) and aged (24 mo.) male mice were studied. Treatment with 4-phenylbutyrate (4-PBA) was used to alleviate ER stress in young adult and aged mice. Aged hearts showed elevated oxidative stress levels compared to young hearts. However, treatment with 4-PBA to attenuate ER stress reduced oxidative stress in aged hearts, indicating that ER stress contributes to increased oxidative stress in aging. Moreover, aging resulted in reduced levels of peroxiredoxin 3 (PRDX3) in mitochondria and peroxiredoxin 4 (PRDX4) in myocardium. While 4-PBA treatment improved PRDX3 content in aged hearts, it did not restore PRDX4 content in aged mice. These findings suggest that ER stress not only leads to mitochondrial dysfunction and increased oxidant stress but also impairs a vital antioxidant defense through decreased PRDX3 content. Additionally, the results suggest that PRDX4 may contribute an upstream role in inducing ER stress during aging.

Topical foam as a promising carrier system for active pharmaceutical ingredients: review of clinical studies

Skin disorders are preferentially treated by topical administration of medicines or cosmetics because of the possibility of local action. However, a great concern is the delivery of topical actives with effective penetration through the stratum corneum to ensure the desired effect. Considering the search for a carrier system that allows the penetration/permeation of active pharmaceutical ingredients through this structure, searching for effective topical pharmaceutical forms is needed. Foams have been widely studied over the years due to their high capacity to favor the active to overcome the cutaneous barrier and because this form of presentation has ease of application and high acceptability by users. The objective of this review was to analyze the potential of foam as a topical pharmaceutical form for treating skin disorders, upon clinical cases reported in the literature. Foam presents technical advantages when compared to other conventional topical pharmaceutical forms due to its fast action, high tolerance, and safety, with reduction or total remission of adverse events. Regarding the patient, foam increased the rate of adherence to the treatment. Therefore, it is concluded that foam is an effective, secure, and stable topical presentation form for carrying active pharmaceutical ingredients and widely accepted by patients.

Insights into risk factors for basal cell carcinoma: a Mendelian randomization study

Basal cell carcinoma (BCC) is one of the most common skin cancers. However, risk factors for BCC, especially nonenvironmental features, have not been wholly identified. Consequently, we conducted a Mendelian randomization (MR) analysis to explore possible causal risk factors in a cohort of millions of Europeans. We used data on genetic variants for risk factors from publicly available genome-wide association studies. This resulted in the present MR study that analysed 43 risk factors and demonstrates that telomere length [odds ratio (OR) 1.53, 95% confidence interval (CI) 1.35-1.74, P < 0.001], birthweight (OR 1.13, 95% CI 1.01-1.26, P = 0.03) and height (OR 1.07, 95% CI 1.01-1.13, P = 0.02) may casually be related to an increased risk of BCC. However, no genetic liability between BCC risk and other potential risk factors was noted. These findings may help contribute to identifying high-risk populations susceptible to BCC.

Sex-specific differences in oxidative stress markers and collagen expression in perioral skin wrinkling

Wrinkling is the hallmark of skin ageing. We previously reported that perioral wrinkling is more severe in females; however, the molecular basis is unknown. This study assessed sex differences in the molecular expression of key ageing regulators in perioral skin. Twelve subjects (n = 6 male/female) were enrolled in this cross-sectional study and biopsies were taken from the perioral and periocular regions. RNA expression of collagen I, collagen III, cysteine-rich angiogenic inducer 61 (CYR61) and insulin-like growth factor 1 (IGF-1) was assessed by qPCR. There was no difference between females' and males' Griffith's grades (6 and 5.67, respectively, p = 0.092) or periocular wrinkling grades (3.2 and 2.6, p = 0.421), but females had more severe perioral wrinkling grades than males (6.2 and 2.8, p = 0.020). Females not only expressed significantly more CYR61 (p = 0.018) in the perioral region than malesm but also expressed more collagen III (p = 0.016). There was no difference in collagen I (p = 0.115) or IGF-1 (p = 0.124) expression in the perioral region between sexes. In the periocular region, there were no significant differences between sexes in the expression of all four markers. The significant molecular differences in the perioral region between the sexes may contribute to the greater perioral skin wrinkling seen clinically in females.

Association Between Telomere Length and Skin Cancer and Aging: A Mendelian Randomization Analysis

Background: Telomere shortening is a hallmark of cellular senescence. However, telomere length (TL)-related cellular senescence has varying effects in different cancers, resulting in a paradoxical relationship between senescence and cancer. Therefore, we used observational epidemiological studies to investigate the association between TL and skin cancer and aging, and to explore whether such a paradoxical relationship exists in skin tissue.

Methods: This study employed two-sample Mendelian randomization (MR) to analyze the causal relationship between TL and skin cancer [melanoma and non-melanoma skin cancers (NMSCs)] and aging. We studied single nucleotide polymorphisms (SNPs) obtained from pooled data belonging to genome-wide association studies (GWAS) in the literature and biobanks. Quality control was performed using pleiotropy, heterogeneity, and sensitivity analyses.

Results: We used five algorithms to analyze the causal relationship between TL and skin aging, melanoma, and NMSCs, and obtained consistent results. TL shortening reduced NMSC and melanoma susceptibility risk with specific odds ratios (ORs) of 1.0344 [95% confidence interval (CI): 1.0168–1.0524, p = 0.01] and 1.0127 (95% CI: 1.0046–1.0209, p = 6.36E-07), respectively. Conversely, TL shortening was validated to increase the odds of skin aging (OR = 0.96, 95% CI: 0.9332–0.9956, p = 0.03). Moreover, the MR-Egger, maximum likelihood, and inverse variance weighted (IVW) methods found significant heterogeneity among instrumental variable (IV) estimates (identified as MR-Egger skin aging Q = 76.72, p = 1.36E-04; melanoma Q = 97.10, p = 1.62E-07; NMSCsQ = 82.02, p = 1.90E-05). The leave-one-out analysis also showed that the SNP sensitivity was robust to each result.

Conclusion: This study found that TL shortening may promote skin aging development and reduce the risk of cutaneous melanoma and NMSCs. The results provide a reference for future research on the causal relationship between skin aging and cancer in clinical practice.

Quercetin promotes cutaneous wound healing in mice through Wnt/β-catenin signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Oxytropis falcata Bunge is a legume distributed in Northwest China, which is mainly used to treat knife wounds and inflammation. Quercetin is a bioactive flavonoid in O. falcata and becomes a promising healing compound for its angiogenic and anti-inflammatory activities. However, the healing mechanism of quercetin in cutaneous wound remains elusive.

AIM OF THE STUDY

The purpose of this study was to evaluate the healing effect of quercetin on cutaneous wound models in vivo and in vitro, and to reveal the Wnt/β-catenin pathway and Telomerase reverse transcriptase (TERT) involved mechanisms.

MATERIALS AND METHODS

The effects of quercetin on the proliferation and migration of 4 kinds of skin cells were determined by CCK-8 and scratch assay. The wound-healing capacity of quercetin was evaluated in cutaneous wound model of C57BL/6 mice and the wound healing degree was observed by histological staining. The expressions of inflammatory factors, growth factors and the related proteins were detected via Western blot and RT-qPCR analyses. The molecular docking was adopted to evaluate the binding ability of quercetin and TERT.

RESULTS

Quercetin could promote both proliferation and migration of fibroblasts, and enhance cutaneous wound healing capacity in mice. Compared to the control group, the wound healing rates in low (1.5 mg/mL), medium (3.0 mg/mL) and high dose (6.0 mg/mL) quercetin groups reached 94.67%, 97.31% and 98.42%, respectively. Moreover, the dermal structure in quercetin treated mice restored normal and the content of collagen fiber became abundant after administration. The levels of inflammatory factors, including tumor necrosis factor-α, interleukin-1β and interleukin-6 were significantly reduced after quercetin administration. Among which, the level of IL-1β in cutaneous wound was 0.007 times higher than that of the control group when treated with quercetin of high dose (6.0 mg/mL). The improved level of GSH in quercetin treated cutaneous wounds also indicated its higher antioxidant ability. In addition, dose-dependent positive associations were found in the expression levels of vascular endothelial growth factor, fibroblast growth factor and alpha smooth muscle actin in quercetin treated cutaneous wounds. The significantly upregulated protein levels of Wnt and β-catenin further indicated the important role of quercetin in promoting wound healing in mice. According to molecular docking analysis, the formed hydrogen bonds between quercetin and Ala195, Gln308, Asn369 and Lys372 residues of TERT also indicated the indispensable role of TERT in improving wound healing capacity.

CONCLUSION

Quercetin effectively promoted cutaneous wound healing by enhancing the proliferation and migration of fibroblasts, as well as inhibiting inflammation and increasing the expression of growth factors in mice via Wnt/β-catenin signaling pathway and TERT. It provides a basis for a more thorough understanding of mechanism of action of O. falcata Bunge in the treatment of knife wounds and burns.

Pholiota nameko Polysaccharides Protect against Ultraviolet A-Induced Photoaging by Regulating Matrix Metalloproteinases in Human Dermal Fibroblasts

Ultraviolet-A (UVA) exposure is a major cause of skin aging and can induce oxidative damage and accelerate skin wrinkling. Many natural polysaccharides exhibit a UV protective effect. In research on Pholiota nameko polysaccharides (PNPs), a natural macromolecular polysaccharide (4.4–333.487 kDa), studies have shown that PNPs can significantly decrease elastase activity to protect against UVA-induced aging in Hs68 human dermal fibroblasts. Cellular experiments in the present study indicated that PNPs can protect against UVA-induced oxidative damage in Hs68 cells by inhibiting the production of reactive oxygen species. Furthermore, PNPs significantly attenuated UVA-induced cell aging by decreasing the protein expression of matrix metalloproteinase 1, 3, and 9. Pretreatment of Hs68 cells with PNP-40, PNP-60, and PNP-80 before UVA irradiation increased protein expression of tissue inhibitor metalloproteinase 1 by 41%, 42%, and 56% relative to untreated cells. In conclusion, this study demonstrates that PNPs are a natural resource with potentially beneficial effects in protecting against UVA-induced skin aging.

Protective Role of Melatonin and Its Metabolites in Skin Aging

The skin, being the largest organ in the human body, is exposed to the environment and suffers from both intrinsic and extrinsic aging factors. The skin aging process is characterized by several clinical features such as wrinkling, loss of elasticity, and rough-textured appearance. This complex process is accompanied with phenotypic and functional changes in cutaneous and immune cells, as well as structural and functional disturbances in extracellular matrix components such as collagens and elastin. Because skin health is considered one of the principal factors representing overall “well-being” and the perception of “health” in humans, several anti-aging strategies have recently been developed. Thus, while the fundamental mechanisms regarding skin aging are known, new substances should be considered for introduction into dermatological treatments. Herein, we describe melatonin and its metabolites as potential “aging neutralizers”. Melatonin, an evolutionarily ancient derivative of serotonin with hormonal properties, is the main neuroendocrine secretory product of the pineal gland. It regulates circadian rhythmicity and also exerts anti-oxidative, anti-inflammatory, immunomodulatory, and anti-tumor capacities. The intention of this review is to summarize changes within skin aging, research advances on the molecular mechanisms leading to these changes, and the impact of the melatoninergic anti-oxidative system controlled by melatonin and its metabolites, targeting the prevention or reversal of skin aging.

The Impact of Vitamin D on Skin Aging

The active metabolites of vitamin D₃ (D₃) and lumisterol (L₃) exert a variety of antiaging and photoprotective effects on the skin. These are achieved through immunomodulation and include anti-inflammatory actions, regulation of keratinocytes proliferation, and differentiation programs to build the epidermal barrier necessary for maintaining skin homeostasis. In addition, they induce antioxidative responses, inhibit DNA damage and induce DNA repair mechanisms to attenuate premature skin aging and cancerogenesis. The mechanism of action would involve interaction with multiple nuclear receptors including VDR, AhR, LXR, reverse agonism on RORα and -γ, and nongenomic actions through 1,25D₃-MARRS receptor and interaction with the nongenomic binding site of the VDR. Therefore, active forms of vitamin D₃ including its canonical (1,25(OH)₂D₃) and noncanonical (CYP11A1-intitated) D₃ derivatives as well as L₃ derivatives are promising agents for the prevention, attenuation, or treatment of premature skin aging. They could be administrated orally and/or topically. Other forms of parenteral application of vitamin D₃ precursor should be considered to avoid its predominant metabolism to 25(OH)D₃ that is not recognized by CYP11A1 enzyme. The efficacy of topically applied vitamin D₃ and L₃ derivatives needs further clinical evaluation in future trials.

Antioxidant and Anti-Aging Potential of Indian Sandalwood Oil against Environmental Stressors In Vitro and Ex Vivo

Distilled from the heartwood of Santalum album, Indian sandalwood oil is an essential oil that historically has been used as a natural active ingredient in cosmetics to condition and brighten the skin. It has been documented to exhibit antioxidant, anti-inflammatory, and anti-proliferative activities. Here, we investigated the protective and anti-aging effects of Indian sandalwood oil in scavenging reactive oxygen species (ROS) in HaCaT cells and in human skin explants after exposure to oxidative stress. Using a probe DCFH-DA, the antioxidant capacity of Indian sandalwood oil was monitored following exposure to blue light at 412 nm and 450 nm or cigarette smoke. The anti-aging effect of sandalwood oil was also explored in human skin explants via the assessment of collagenase level (MMP-1). We reported that Indian sandalwood oil possessed antioxidant potential that can scavenge the ROS generated by a free radical generating compound (AAPH). Subsequent exposure to environmental stressors revealed that Indian sandalwood oil possessed superior antioxidant activity in comparison to vitamin E (alpha tocopherol). Using human skin explants, this study demonstrated that Indian sandalwood oil can also inhibit the pollutant-induced level of MMP-1. The findings indicated that Indian sandalwood oil can potentially serve as a protective and anti-aging active ingredient in cosmetics and dermatology against environmental stressors.

Potential of Naturally Derived Compounds in Telomerase and Telomere Modulation in Skin Senescence and Aging

Proper functioning of cells-their ability to divide, differentiate, and regenerate-is dictated by genomic stability. The main factors contributing to this stability are the telomeric ends that cap chromosomes. Telomere biology and telomerase activity have been of interest to scientists in various medical science fields for years, including the study of both cancer and of senescence and aging. All these processes are accompanied by telomere-length modulation. Maintaining the key levels of telomerase component (hTERT) expression and telomerase activity that provide optimal telomere length as well as some nontelomeric functions represents a promising step in advanced anti-aging strategies, especially in dermocosmetics. Some known naturally derived compounds contribute significantly to telomere and telomerase metabolism. However, before they can be safely used, it is necessary to assess their mechanisms of action and potential side effects. This paper focuses on the metabolic potential of natural compounds to modulate telomerase and telomere biology and thus prevent senescence and skin aging.

Antioxidant Properties of Plant-Derived Phenolic Compounds and Their Effect on Skin Fibroblast Cells

Plants are rich sources of a diverse range of chemicals, many of which have significant metabolic activity. One large group of secondary compounds are the phenolics, which act as inter alia potent reactive oxygen scavengers in cells, including fibroblasts. These common dermis residue cells play a crucial role in the production of extracellular matrix components, such as collagen, and maintaining the integrity of connective tissue. Chronic wounds or skin exposure to UV-irradiation disrupt fibroblast function by the generation of reactive oxygen species, which may damage cell components and modify various signaling pathways. The resulting imbalance may be reversed by the antioxidant activity of plant-derived phenolic compounds. This paper reviews the current state of knowledge on the impact of phenolics on fibroblast functionality under oxidative stress conditions. It examines a range of compounds in extracts from various species, as well as single specific plant-derived compounds. Phenolics are a good candidate for eliminating the causes of skin damage including wounds and aging and acting as skin care agents.

Continuous monitoring of cell transfection efficiency with micropatterned substrates

The effect of cell-cell contact on gene transfection is mainly unknown. Usually, transfection is carried out in batch cell cultures without control over cellular interactions, and efficiency analysis relies on complex and expensive protocols commonly involving flow cytometry as the final analytical step. Novel platforms and cell patterning are being studied to control cellular interactions and improve quantification methods. In this study, we report the use of surface patterning of fibronectin for the generation of two types of mesenchymal stromal cell patterns: single-cell patterns without cell-to-cell contact, and small cell-colony patterns. Both scenarios allowed the integration of the full transfection process and the continuous monitoring of thousands of individualized events by fluorescence microscopy. Our results showed that cell-to-cell contact clearly affected the transfection, as single cells presented a maximum transfection peak 6 h earlier and had a 10% higher transfection efficiency than cells with cell-to-cell contact.

Probiotic Activity of Staphylococcus epidermidis Induces Collagen Type I Production through FFaR2/p-ERK Signaling

Collagen type I is a key structural component of dermis tissue and is produced by fibroblasts and the extracellular matrix. The skin aging process, which is caused by intrinsic or extrinsic factors, such as natural aging or free radical exposure, greatly reduces collagen expression, thereby leading to obstructed skin elasticity. We investigated the effective fermentation of Cetearyl isononanoate (CIN), a polyethylene glycol (PEG) analog, as a carbon source with the skin probiotic bacterium Staphylococcus epidermidis (S.epidermidis) or butyrate, as their fermentation metabolites could noticeably restore collagen expression through phosphorylated extracellular signal regulated kinase (p-ERK) activation in mouse fibroblast cells and skin. Both the in vitro and in vivo knockdown of short-chain fatty acid (SCFA) or free fatty acid receptor 2 (FFaR2) considerably blocked the probiotic effect of S. epidermidis on p-ERK-induced collagen type I induction. These results demonstrate that butyric acid (BA) in the metabolites of fermenting skin probiotic bacteria mediates FFaR2 to induce the synthesis of collagen through p-ERK activation. We hereby imply that metabolites from the probiotic S. epidermidis fermentation of CIN as a potential carbon source could restore impaired collagen in the dermal extracellular matrix (ECM), providing integrity and elasticity to skin.

Alpha-Arbutin Promotes Wound Healing by Lowering ROS and Upregulating Insulin/IGF-1 Pathway in Human Dermal Fibroblast

Alpha-arbutin (4-hydroxyphenyl alpha-glucopyranoside) is a known inhibitor of tyrosinase in keratinocytes; however, its effect on other genes and pathways in other skin cells has not been thoroughly investigated. In this study, we investigate the mechanism of alpha-arbutin activity in human dermal fibroblast cultures for 48 h. Results showed that the oxidative stress pathway was activated as alpha-arbutin reduced reactive oxygen species. In addition, we found a high possibility of wound healing and the upregulation of the insulin-like growth factor 1 receptor (IFG1R) pathway. We also investigated the role of the NRF2 gene in mediating the alpha-arbutin response. In silico comparative genomics analysis conducted using our original tool, SHOE, suggested transcription factors with a role in tumor suppression and toxicity response as candidates for regulating the alpha-arbutin-mediated pathway.

Bases for Treating Skin Aging With Artificial Mitochondrial Transfer/Transplant (AMT/T)

The perception of mitochondria as only the powerhouse of the cell has dramatically changed in the last decade. It is now accepted that in addition to being essential intracellularly, mitochondria can promote cellular repair when transferred from healthy to damaged cells. The artificial mitochondria transfer/transplant (AMT/T) group of techniques emulate this naturally occurring process and have been used to develop therapies to treat a range of diseases including cardiac and neurodegenerative. Mitochondria accumulate damage with time, resulting in cellular senescence. Skin cells and its mitochondria are profoundly affected by ultraviolet radiation and other factors that induce premature and accelerated aging. In this article, we propose the basis to use AMT/T to treat skin aging by transferring healthy mitochondria to senescent cells, possibly revitalizing them. We provide insightful information about how skin structure, components, and cells could age rapidly depending on the amount of damage received. Arguments are shown in favor of the use of AMT/T to treat aging skin and its cells, among them the possibility to stop free radical production, add new genetic material, and provide an energetic boost to help cells prolong their viability over time. This article intends to present one of the many aspects in which mitochondria could be used as a universal treatment for cell and tissue damage and aging.

Hopes and Limits of Adipose-Derived Stem Cells (ADSCs) and Mesenchymal Stem Cells (MSCs) in Wound Healing

Adipose tissue derived stem cells (ADSCs) are mesenchymal stem cells identified within subcutaneous tissue at the base of the hair follicle (dermal papilla cells), in the dermal sheets (dermal sheet cells), in interfollicular dermis, and in the hypodermis tissue. These cells are expected to play a major role in regulating skin regeneration and aging-associated morphologic disgraces and structural deficits. ADSCs are known to proliferate and differentiate into skin cells to repair damaged or dead cells, but also act by an autocrine and paracrine pathway to activate cell regeneration and the healing process. During wound healing, ADSCs have a great ability in migration to be recruited rapidly into wounded sites added to their differentiation towards dermal fibroblasts (DF), endothelial cells, and keratinocytes. Additionally, ADSCs and DFs are the major sources of the extracellular matrix (ECM) proteins involved in maintaining skin structure and function. Their interactions with skin cells are involved in regulating skin homeostasis and during healing. The evidence suggests that their secretomes ensure: (i) The change in macrophages inflammatory phenotype implicated in the inflammatory phase, (ii) the formation of new blood vessels, thus promoting angiogenesis by increasing endothelial cell differentiation and cell migration, and (iii) the formation of granulation tissues, skin cells, and ECM production, whereby proliferation and remodeling phases occur. These characteristics would be beneficial to therapeutic strategies in wound healing and skin aging and have driven more insights in many clinical investigations. Additionally, it was recently presented as the tool key in the new free-cell therapy in regenerative medicine. Nevertheless, ADSCs fulfill the general accepted criteria for cell-based therapies, but still need further investigations into their efficiency, taking into consideration the host-environment and patient-associated factors.

The role of bioidentical hormone replacement therapy in anti-aging medicine: a review of the literature

The changes in skin and overall appearance that occur with increasing age can be partly attributed to declining hormone levels. While hormonal deficiencies are most commonly associated with postmenopausal females, males are also subject to age-related testosterone decline and may benefit from replacement of deficient hormones. However, great disparities exist between the recommendations of scientific societies and actual use of hormone supplements in aging patients. The purpose of this literature review is to discuss the role of hormones in the aging process of the skin, explain the safety profile of hormone replacement therapy, specifically discussing the superiority of bioidentical hormones, and highlight the benefits of hormone replacement in anti-aging of the skin. In summary, this literature review suggests that hormone replacement with bioidentical hormones is a safe and effective way to prevent skin aging.

Materials Stiffness-Dependent Redox Metabolic Reprogramming of Mesenchymal Stem Cells for Secretome-Based Therapeutic Angiogenesis

Cellular redox metabolism has emerged as a key tenet in stem cell biology that can profoundly influence the paracrine activity and therapeutic efficacy of mesenchymal stem cells (MSCs). Although the use of materials cues to direct the differentiation of MSCs has been widely investigated, little is known regarding the role of materials in the control of redox paracrine signaling in MSCs. Herein, using a series of mechanically tunable fibronectin-conjugated polyacrylamide (FN-PAAm) hydrogel substrates, it is shown that a mechanically compliant microenvironment with native-tissue mimicking stiffness (E = 0.15 kPa) can mechano-regulate the intracellular reactive oxygen species (ROS) level in human adipose-derived MSCs (ADMSCs). The cells reciprocate to the ROS imbalance by co-activating the nuclear factor erythroid 2-related factor 2 and hypoxia-inducible factor 1 alpha stress response signaling pathways to increase the production of vascular endothelial growth factor and basic fibroblast growth factor. Conditioned medium collected from ADMSCs grown on the 0.15 kPa FN-PAAm is found to significantly promote in vitro and ex ovo vascularization events. Collectively, these findings highlight the importance of delineating critical materials properties that can enable the reprogramming of cellular redox signaling for advanced MSCs-based secretome regenerative medicine.

Environmental Stressors on Skin Aging. Mechanistic Insights

The skin is the main barrier that protects us against environmental stressors (physical, chemical, and biological). These stressors, combined with internal factors, are responsible for cutaneous aging. Furthermore, they negatively affect the skin and increase the risk of cutaneous diseases, particularly skin cancer. This review addresses the impact of environmental stressors on skin aging, especially those related to general and specific external factors (lifestyle, occupation, pollutants, and light exposure). More specifically, we have evaluated ambient air pollution, household air pollutants from non-combustion sources, and exposure to light (ultraviolet radiation and blue and red light). We approach the molecular pathways involved in skin aging and pathology as a result of exposure to these external environmental stressors. Finally, we reflect on how components of environmental stress can interact with ultraviolet radiation to cause cell damage and the critical importance of knowing the mechanisms to develop new therapies to maintain the skin without damage in old age and to repair its diseases.

Nrf2 dependent antiaging effect of milk-derived bioactive peptide in old fibroblasts

Prolonged passaging of primary fibroblast cells totally shapes the natural biological phenomena and leads to the appearance of features related to senescence. As a result, it is a good natural tool to delineate the molecular mechanism of cellular aging. The present investigation revealed the antiaging effect of milk-derived novel bioactive peptide (VLPVPQK). The peptide played an important role in downregulating apoptosis-related markers in late passages of cultured fibroblast cells. The peptide treatment to aged fibroblasts caused enhancement in cell migration, DNA integrity, and decrease in the lipid peroxidation, reactive oxygen species, nitric oxide production as well as pro-inflammatory cytokines, TNF-α and IL-6. Moreover, the peptide decreased the expression of apoptotic caspases, Bax, and senescence-associated β-galactosidase (SA-β-gal) proteins. The peptide pretreatment also enhanced the extracellular collagen protein and antiapoptotic, Bcl-xL. In addition, the peptide treatment reversed the senescence-related activity in fibroblasts by stimulating Nrf2 mediated antioxidative defense system and inhibiting the action of NFkB/p38MAPK signaling, similar to the commercially available inhibitor (SB203580) of p38MAPK. Thus, the peptide exhibits the antiaging effect in dermal fibroblast cells.

Mitochondrial DNA 3,860-bp Deletion Increases with Aging in the Auditory Nervous System of C57BL/6J Mice

BACKGROUND/AIMS

Mitochondrial DNA (mtDNA) is sensitive to oxidative damage during aging, which can result in mtDNA mutations. A previous study reported that a 3,860-bp mtDNA deletion, similar to a 4,977-bp mtDNA deletion in humans, is also common occurrence in murine tissues, and increases in the brain and liver with aging. However, no previous study evaluated both topics in the murine auditory nervous system.

METHODS

We compared mtDNA oxidative damage, mitochondrial ultrastructural changes, and the frequency of the 3,860-bp deletion in the peripheral (spiral ganglion, SG) and central (auditory cortex, AC) auditory nervous system of C57BL/6J mice aged 2, 12, and 18 months.

RESULTS

We found that the threshold of auditory brainstem response increased with age along with the signal of 8-hydroxy-2'-deoxyguanosine - a marker of DNA oxidative damage - in the mitochondria of SG and AC neurons. The mitochondrial ultrastructural damage also increased with aging in the SG and AC neurons. Moreover, the relative amount of mtDNA 3,860-bp deletion in 12- and 18-month-old mice was significantly higher in the SG and AC as compared to 2-month-old mice.

CONCLUSION

These results suggest that the mtDNA 3,860-bp deletion is common in the auditory nervous system of mice and increases with age and may contribute to age-related hearing loss.

Molecular Mechanisms of Dermal Aging and Antiaging Approaches

The dermis is primarily composed of the extracellular matrix (ECM) and fibroblasts. During the aging process, the dermis undergoes significant changes. Collagen, which is a major component of ECM, becomes fragmented and coarsely distributed, and its total amount decreases. This is mainly due to increased activity of matrix metalloproteinases, and impaired transforming growth factor-β signaling induced by reactive oxygen species generated during aging. The reduction in the amount of collagen hinders the mechanical interaction between fibroblasts and the ECM, and consequently leads to the deterioration of fibroblast function and further decrease in the amount of dermal collagen. Other ECM components, including elastic fibers, glycosaminglycans (GAGs), and proteoglycans (PGs), also change during aging, ultimately leading to a reduction in the amount of functional components. Elastic fibers decrease in intrinsically aged skin, but accumulate abnormally in photoaged skin. The changes in the levels of GAGs and PGs are highly diverse, and previous studies have reported conflicting results. A reduction in the levels of functional dermal components results in the emergence of clinical aging features, such as wrinkles and reduced elasticity. Various antiaging approaches, including topicals, energy-based procedures, and dermal fillers, can restore the molecular features of dermal aging with clinical efficacy. This review summarizes the current understanding of skin aging at the molecular level, and associated treatments, to put some of the new antiaging technology that has emerged in this rapidly expanding field into molecular context.

A comprehensive overview of mitochondrial DNA 4977-bp deletion in cancer studies

Mitochondria are cellular machines essential for energy production. The biogenesis of mitochondria is a highly complex and it depends on the coordination of the nuclear and mitochondrial genome. Mitochondrial DNA (mtDNA) mutations and deletions are suspected to be associated with carcinogenesis. The most described mtDNA deletion in various human cancers is called the 4977-bp common deletion (mDNA⁴⁹⁷⁷) and it has been explored since two decades. In spite of that, its implication in carcinogenesis still unknown and its predictive and prognostic impact remains controversial. This review article provides an overview of some of the cellular and molecular mechanisms underlying mDNA⁴⁹⁷⁷ formation and a detailed summary about mDNA⁴⁹⁷⁷ reported in various types of cancers. The current knowledges of mDNA⁴⁹⁷⁷ as a prognostic and predictive marker are also discussed.

Actin cytoskeleton assembly regulates collagen production via TGF-β type II receptor in human skin fibroblasts

The dermal compartment of skin is primarily composed of collagen-rich extracellular matrix (ECM), which is produced by dermal fibroblasts. In Young skin, fibroblasts attach to the ECM through integrins. During ageing, fragmentation of the dermal ECM limits fibroblast attachment. This reduced attachment is associated with decreased collagen production, a major cause of skin thinning and fragility, in the elderly. Fibroblast attachment promotes assembly of the cellular actin cytoskeleton, which generates mechanical forces needed for structural support. The mechanism(s) linking reduced assembly of the actin cytoskeleton to decreased collagen production remains unclear. Here, we report that disassembly of the actin cytoskeleton results in impairment of TGF-β pathway, which controls collagen production, in dermal fibroblasts. Cytoskeleton disassembly rapidly down-regulates TGF-β type II receptor (TβRII) levels. This down-regulation leads to reduced activation of downstream effectors Smad2/Smad3 and CCN2, resulting in decreased collagen production. These responses are fully reversible; restoration of actin cytoskeleton assembly up-regulates TβRII, Smad2/Smad3, CCN2 and collagen expression. Finally, actin cytoskeleton-dependent reduction of TβRII is mediated by induction of microRNA 21, a potent inhibitor of TβRII protein expression. Our findings reveal a novel mechanism that links actin cytoskeleton assembly and collagen expression in dermal fibroblasts. This mechanism likely contributes to loss of TβRII and collagen production, which are observed in aged human skin.

The Na/K-ATPase Oxidant Amplification Loop Regulates Aging

As aging involves oxidant injury, we examined the role of the recently described Na/K-ATPase oxidant amplification loop (NKAL). First, C57Bl6 old mice were given a western diet to stimulate oxidant injury or pNaKtide to antagonize the NKAL. The western diet accelerated functional and morphological evidence for aging whereas pNaKtide attenuated these changes. Next, human dermal fibroblasts (HDFs) were exposed to different types of oxidant stress in vitro each of which increased expression of senescence markers, cell-injury, and apoptosis as well as stimulated the NKAL. Further stimulation of the NKAL with ouabain augmented cellular senescence whereas treatment with pNaKtide attenuated it. Although N-Acetyl Cysteine and Vitamin E also ameliorated overall oxidant stress to a similar degree as pNaKtide, the pNaKtide produced protection against senescence that was substantially greater than that seen with either antioxidant. In particular, pNaKtide appeared to specifically ameliorate nuclear oxidant stress to a greater degree. These data demonstrate that the NKAL is intimately involved in the aging process and may serve as a target for anti-aging interventions.

Mitochondria and Reactive Oxygen Species in Aging and Age-Related Diseases

Aging has been linked to several degenerative processes that, through the accumulation of molecular and cellular damage, can progressively lead to cell dysfunction and organ failure. Human aging is linked with a higher risk for individuals to develop cancer, neurodegenerative, cardiovascular, and metabolic disorders. The understanding of the molecular basis of aging and associated diseases has been one major challenge of scientific research over the last decades. Mitochondria, the center of oxidative metabolism and principal site of reactive oxygen species (ROS) production, are crucial both in health and in pathogenesis of many diseases. Redox signaling is important for the modulation of cell functions and several studies indicate a dual role for ROS in cell physiology. In fact, high concentrations of ROS are pathogenic and can cause severe damage to cell and organelle membranes, DNA, and proteins. On the other hand, moderate amounts of ROS are essential for the maintenance of several biological processes, including gene expression. In this review, we provide an update regarding the key roles of ROS-mitochondria cross talk in different fundamental physiological or pathological situations accompanying aging and highlighting that mitochondrial ROS may be a decisive target in clinical practice.

Mitochondrial damage and cytoskeleton reorganization in human dermal fibroblasts exposed to artificial visible light similar to screen-emitted light

BACKGROUND

Artificial visible light is everywhere in modern life. Social communication confronts us with screens of all kinds, and their use is on the rise. We are therefore increasingly exposed to artificial visible light, the effects of which on skin are poorly known.

OBJECTIVE

The purpose of this study was to model the artificial visible light emitted by electronic devices and assess its effect on normal human fibroblasts.

METHODS

The spectral irradiance emitted by electronic devices was optically measured and equipment was developed to accurately reproduce such artificial visible light. Effects on normal human fibroblasts were analyzed on human genome microarray-based gene expression analysis. At cellular level, visualization and image analysis were performed on the mitochondrial network and F-actin cytoskeleton. Cell proliferation, ATP release and type I procollagen secretion were also measured.

RESULTS

We developed a device consisting of 36 LEDs simultaneously emitting blue, green and red light at distinct wavelengths (450 nm, 525 nm and 625 nm) with narrow spectra and equivalent radiant power for the three colors. A dose of 99 J/cm2 artificial visible light was selected so as not to induce cell mortality following exposure. Microarray analysis revealed 2984 light-modulated transcripts. Functional annotation of light-responsive genes revealed several enriched functions including, amongst others, the "mitochondria" and "integrin signaling" categories. Selected results were confirmed by real-time quantitative PCR, analyzing 24 genes representing these two categories. Analysis of micro-patterned culture plates showed marked fragmentation of the mitochondrial network and disorganization of the F-actin cytoskeleton following exposure. Functionally, there was considerable impairment of cell growth and spread, ATP release and type I procollagen secretion in exposed fibroblasts.

CONCLUSION

Artificial visible light induces drastic molecular and cellular changes in normal human fibroblasts. This may impede normal cellular functions and contribute to premature skin aging. The present results extend our knowledge of the effects of the low-energy wavelengths that are increasingly used to treat skin disorders.

IDH2 deficiency accelerates skin pigmentation in mice via enhancing melanogenesis

Melanogenesis is a complex biosynthetic pathway regulated by multiple agents, which are involved in the production, transport, and release of melanin. Melanin has diverse roles, including determination of visible skin color and photoprotection. Studies indicate that melanin synthesis is tightly linked to the interaction between melanocytes and keratinocytes. α-melanocyte-stimulating hormone (α-MSH) is known as a trigger that enhances melanin biosynthesis in melanocytes through paracrine effects. Accumulated reactive oxygen species (ROS) in skin affects both keratinocytes and melanocytes by causing DNA damage, which eventually leads to the stimulation of α-MSH production. Mitochondria are one of the main sources of ROS in the skin and play a central role in modulating redox-dependent cellular processes such as metabolism and apoptosis. Therefore, mitochondrial dysfunction may serve as a key for the pathogenesis of skin melanogenesis. Mitochondrial NADP⁺-dependent isocitrate dehydrogenase (IDH2) is a key enzyme that regulates mitochondrial redox balance and reduces oxidative stress-induced cell injury through the generation of NADPH. Downregulation of IDH2 expression resulted in an increase in oxidative DNA damage in mice skin through ROS-dependent ATM-mediated p53 signaling. IDH2 deficiency also promoted pigmentation on the dorsal skin of mice, as evident from the elevated levels of melanin synthesis markers. Furthermore, pretreatment with mitochondria-targeted antioxidant mito-TEMPO alleviated oxidative DNA damage and melanogenesis induced by IDH2 deficiency both in vitro and in vivo. Together, our findings highlight the role of IDH2 in skin melanogenesis in association with mitochondrial ROS and suggest unique therapeutic strategies for the prevention of skin pigmentation.

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Melanogenesis is associated with the production of ROS.

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IDH2 is an essential enzyme in the mitochondrial antioxidant system.

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Downregulation of IDH2 induces ROS-dependent ATM-mediated p53 signaling.

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IDH2 deficiency promotes skin pigmentation.

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mito-TEMPO alleviates melanogenesis caused by IDH2 deficiency.

Nutraceuticals for Skin Care: A Comprehensive Review of Human Clinical Studies

The skin is the body’s largest organ, it participates in sensitivity and offers protection against microorganisms, chemicals and ultraviolet (UV) radiation. Consequently, the skin may suffer alterations such as photo-ageing, immune dysfunction and inflammation which may significantly affect human health. Nutraceuticals represent a promising strategy for preventing, delaying, or minimising premature ageing of the skin and also to alleviate certain skin disorders. Among them, bioactive peptides and oligosaccharides, plant polyphenols, carotenoids, vitamins and polyunsaturated fatty acids are the most widely used ingredients. Supplementation with these products has shown evidence of having an effect on the signs of ageing and protection against UV radiation ageing in several human trials. In this review, the most relevant human studies on skin nutraceuticals are evaluated and the statistical resolution, biological relevance of their results, and, the trial protocols are discussed. In conclusion, quality and rigorousness of the trials must be improved to build credible scientific evidence for skin nutraceuticals and to establish a cause-effect relationship between the ingredients the beneficial effects for the skin.

A review of the role of estrogen in dermal aging and facial attractiveness in women

Estrogens are known to have protective and favorable influences on skin health; conversely, androgens oppose the actions of estrogens. Estrogen's chemical messages are transmitted via the classical nuclear hormone estrogen receptors (ER) alpha and beta and the rapid-acting G-coupled membrane estrogen receptor. Androgens [both testosterone and 5α-dihydrotestosterone (5α-DHT)] bind the same androgen receptor. Estrogen levels peak in the mid- to late 20s in women and then decline by 50% by 50 years of age and dramatically decrease further after menopause. The loss of estrogens with aging contributes to diminished dermal health, whereas estrogen hormone therapy [eg, oral conjugated equine estrogens (CEE)] restores skin health. Several reports suggest positive correlations between the levels of circulating estrogens and: (1) perceived age, (2) attractiveness, (3) enhanced skin health, and (4) facial coloration in women. Based upon a psychological dermato-endocrine perspective, the positive correspondence of high estrogens levels with perceived age and facial attractiveness in women especially with aging demonstrates the importance of hormonal influences on observed dermal health and youthful appearance.

Silk fibroin scavenges hydroxyl radicals produced from a long-term stored water-soluble fullerene system

In this study, we find that silk fibroin as an antioxidant is capable of scavenging OH˙ and accelerating the degradation of water-soluble fullerene, which provides further insight into the application of WSF in intratracheal instillation and inhalation.

Mitochondrial DNA "common deletion" in post-fine needle aspiration infarcted oncocytic thyroid tumors

Thyroid fine needle aspiration (FNA) can rarely induce morphological changes potentially hindering the histopathological diagnosis, especially in Hurthle cell tumors (HCTs), which may easily undergo post-FNA infarction or necrosis. HCTs contain mitochondrion (mt)-rich cells that may bear mtDNA mutations, the most frequent being the so-called common deletion (CD). The aim of this study was to determine the presence and extent of the mtDNA CD in a series of thyroid HCTs that underwent extensive infarction following FNA procedure in comparison with a control series of HCTs lacking post-FNA ischemic/hemorrhagic alterations. Of 257 HCTs with available matched FNA and surgical specimens, 8 cases showed extensive (≥80%) infarction or necrosis in the resected nodule (4 adenomas, 1 carcinoma, 3 HCTs undefined for malignancy). Noninfarcted tumors in the control series included 9 adenomas, 1 carcinoma, and 1 follicular tumor of uncertain malignant potential. These lesions were significantly (P = .03) larger than infarcted nodules. The mtDNA CD was identified using semiquantitative real-time polymerase chain reaction in 2 of 8 (25%) infarcted tumors. In HCTs lacking infarction/necrosis of the control series, the CD was significantly (P = .05) more common (8/11 cases, 72.7%). In 7 of the 10 deleted cases, the CD was present also in the adjacent nonneoplastic parenchyma. In conclusion, the rare oncocytic tumors undergoing extensive infarction are smaller than those lacking ischemic changes and bear the mtDNA CD in a significantly lower proportion compared with control noninfarcted HCTs. This may suggest that mtDNA deletion confers a survival advantage to oncocytic cells in stress conditions, including FNA procedures.

Ezrin regulates skin fibroblast size/mechanical properties and YAP-dependent proliferation

Ezrin acts as a dynamic linkage between plasma membrane and cytoskeleton, and thus involved in many fundamental cellular functions. Yet, its potential role in human skin is virtually unknown. Here we investigate the role of Ezrin in primary skin fibroblasts, the major cells responsible extracellular matrix (ECM) production. We report that Ezrin play an important role in the maintenance of skin fibroblast size/mechanical properties and proliferation. siRNA-mediated Ezrin knockdown decreased fibroblast size and mechanical properties, and thus impaired the nuclear translocation of YAP, a protein commonly response to cell size and mechanical force. Functionally, depletion of Ezrin significantly inhibited YAP target gene expression and fibroblast proliferation. Conversely, restoration of YAP nuclear translocation by overexpression of constitutively active YAP reversed YAP target genes expression and rescued proliferation in Ezrin knockdown cells. These data reveal a novel role for Ezrin in maintenance of fibroblast size/mechanical force and regulating YAP-mediated proliferation.

Skin aging and oxidative stress: Equol's anti-aging effects via biochemical and molecular mechanisms

Oxygen in biology is essential for life. It comes at a cost during normal cellular function, where reactive oxygen species (ROS) are generated by oxidative metabolism. Human skin exposed to solar ultra-violet radiation (UVR) dramatically increases ROS production/oxidative stress. It is important to understand the characteristics of human skin and how chronological (intrinsic) aging and photo-aging (extrinsic aging) occur via the impact of ROS production by cascade signaling pathways. The goal is to oppose or neutralize ROS insults to maintain good dermal health. Botanicals, as active ingredients, represent one of the largest categories used in dermatology and cosmeceuticals to combat skin aging. An emerging botanical is equol, a polyphenolic/isoflavonoid molecule found in plants and food products and via gastrointestinal metabolism from precursor compounds. Introductory sections cover oxygen, free radicals (ROS), oxidative stress, antioxidants, human skin aging, cellular/molecular ROS events in skin, steroid enzymes/receptors/hormonal actions and genetic factors in aging skin. The main focus of this review covers the characteristics of equol (phytoestrogenic, antioxidant and enhancement of extracellular matrix properties) to reduce skin aging along with its anti-aging skin influences via reducing oxidative stress cascade events by a variety of biochemical/molecular actions and mechanisms to enhance human dermal health.

[Epidermal aging and anti-aging strategies]

Epithelial senescence is a complex process depending on intrinsic as well as extrinsic factors (e.g., UV or IR light, tobacco smoke) and must be seen in the context of the aging process especially of the corium and the subcutis. Morphological alterations become apparent in the form of epithelial atrophy, structural changes within the basal membrane, and a decrease in cell count of melanocytes and Langerhans cells. Signs of cellular senescence are reduced proliferation of keratinocytes, cumulation of dysplastic keratinocytes, various mutations (e.g., c-Fos/c-Jun, STAT3, FoxO1), as well as multiple lipid or amino acid metabolic aberrations (e.g., production of advanced glycation endproducts). This causes functional changes within the physical (lipid deficiency, water distribution dysfunction, lack of hygroscopic substances), chemical (pH conditions, oxygen radicals), and immunological barrier. Prophylactically, barrier-protective care products, antioxidant substances (e.g., vitamin C, B3, E, polyphenols, flavonoids), sunscreen products/measurements, and retinoids are used. For correcting alterations in aged epidermis, chemical peelings (fruit acids, β-hydroxy acid, trichloroacetic acid, phenolic compounds), non-ablative (IPL, PDL, Nd:YAG) as well as ablative (CO2, Erbium-YAG) light-assisted methods are used.

Molecular basis of retinol anti-ageing properties in naturally aged human skin in vivo

OBJECTIVE

Retinoic acid has been shown to improve the aged-appearing skin. However, less is known about the anti-ageing effects of retinol (ROL, vitamin A), a precursor of retinoic acid, in aged human skin in vivo. This study aimed to investigate the molecular basis of ROL anti-ageing properties in naturally aged human skin in vivo.

METHODS

Sun-protected buttock skin (76 ± 6 years old, n = 12) was topically treated with 0.4% ROL and its vehicle for 7 days. The effects of topical ROL on skin epidermis and dermis were evaluated by immunohistochemistry, in situ hybridization, Northern analysis, real-time RT-PCR and Western analysis. Collagen fibrils nanoscale structure and surface topology were analysed by atomic force microscopy.

RESULTS

Topical ROL shows remarkable anti-ageing effects through three major types of skin cells: epidermal keratinocytes, dermal endothelial cells and fibroblasts. Topical ROL significantly increased epidermal thickness by stimulating keratinocytes proliferation and upregulation of c-Jun transcription factor. In addition to epidermal changes, topical ROL significantly improved dermal extracellular matrix (ECM) microenvironment; increasing dermal vascularity by stimulating endothelial cells proliferation and ECM production (type I collagen, fibronectin and elastin) by activating dermal fibroblasts. Topical ROL also stimulates TGF-β/CTGF pathway, the major regulator of ECM homeostasis, and thus enriched the deposition of ECM in aged human skin in vivo. 0.4% topical ROL achieved similar results as seen with topical retinoic acid, the biologically active form of ROL, without causing noticeable signs of retinoid side effects.

CONCLUSION

0.4% topical ROL shows remarkable anti-ageing effects through improvement of the homeostasis of epidermis and dermis by stimulating the proliferation of keratinocytes and endothelial cells, and activating dermal fibroblasts. These data provide evidence that 0.4% topical ROL is a promising and safe treatment to improve the naturally aged human skin.