Photoaging Model Research Articles

Autophagy-Enhancing Properties of Hedyotis diffusa Extracts in HaCaT Keratinocytes: Potential as an Anti-Photoaging Cosmetic Ingredient

The decline in autophagy disrupts homeostasis in skin cells, leading to oxidative stress, energy deficiency, and inflammation—all key contributors to skin photoaging. Consequently, activating autophagy has become a focal strategy for delaying skin photoaging. Natural plants are rich in functional molecules and widely used in the development of anti-photoaging cosmetics. Hedyotis diffusa (HD), as a medicinal plant, is renowned for its anti-inflammatory and anticancer properties; however, its effects on skin photoaging remain unclear. This study investigates HD’s potential to counteract skin photoaging by restoring mitochondrial autophagy in keratinocytes. We used HPLC to detect the main chemical components in HD and, using a UVB-induced photoaging model in HaCaT keratinocytes, examined the effects of HD on reactive oxygen species (ROS) levels, Ca2+ concentration, mitochondrial membrane potential (MMP), apoptosis, and the cell cycle. Cellular respiration was further evaluated with the Seahorse XFp Analyzer, and RT-PCR and Western blotting were used to analyze the impact of HD on mitochondrial autophagy-related gene expression and signaling pathways. Our findings indicate that HD promotes autophagy by modulating the PI3K/AKT/mTOR and PINK/PARK2 pathways, which stabilizes mitochondrial quality, maintains MMP and Ca2+ balance, and reduces cytochrome c release. These effects relieve cell cycle arrest and prevent apoptosis associated with an increased BAX/BCL-2 ratio. Thus, HD holds promise as an effective anti-photoaging ingredient with potential applications in the development of cosmetic products.

Photoprotective effects of quercetin on photoaging-induced rats

Purpose Photoaging is characterised by cutaneous changes caused by exposure to ultraviolet light over time. Quercetin is a bioflavanoid with antioxidant, antineoplastic, and anti-inflammatory effects. This study investigated the therapeutic effects of topical quercetin on photoaging, a phenomenon not previously studied in ultraviolet A (UVA)-induced photoaging. Methods A total of 40 rats were randomly categorised into 5 groups, each comprising 8 rats. A photoaging model was induced by applying UVA to the dorsal region of all rats, except for the negative control group. Topical 0.1% retinoic acid was applied to one UVA group, topical 0.3% quercetin to another UVA group, and both agents were applied in combination to yet another UVA group 5 days a week for 8 weeks. Subsequently, wrinkle values were measured, reactive oxygen species (ROS) and matrix metalloproteinase-1 (MMP-1) levels were analysed, and histopathological parameters were examined. Results The wrinkle value of the UVA group was found to be significantly higher than that of the UVA + Quercetin group. Collagen damage was lower in the UVA + Quercetin group than in the UVA group, although this difference was not statistically significant. Compared with the UVA + Retinoic Acid group, the UVA + Quercetin group exhibited a more significant decrease in inflammation. MMP-1 values were considerably higher in the UVA + Retinoic Acid and UVA + Quercetin + Retinoic Acid groups as well as in the UVA + Quercetin group compared with the control and UVA groups. Conclusion The present study showed that quercetin can be utilised in the treatment of photoaging, especially when combined with retinoic acid.

Antiaging synergistic effect in noninvasive transdermal delivery of peptide loaded liposomes by low energy/frequency radiofrequency

Low energy/frequency radiofrequency (LRF) combined with the transdermal delivery of liposome (L) encapsulated antiaging peptides technology is a remarkable, newly developed physical noninvasive transdermal penetration technique; it is considered a highly efficient, comprehensive and safe technology. In this study, our objective was to evaluate the physical and chemical mechanisms underlying the efficacy of this innovative technique involving a combination of LRF and L, termed LLRF, that exerts a synergistic anti-aging effect on human skin, via an animal experiment. Physical and chemical analyses indicated that a relatively stable liposome with a uniform nano-size, which was formed, possessed good transdermal permeability that was 2.74 folds higher than that of the free peptide (F). LLRF exhibited a higher transdermal permeation performance that was of 3.65 folds higher than that of the free one, which was substantiated via confocal laser scanning fluorescence microscopy. The mouse UVB photoaging model trial confirmed that the LLRF technology exerted a significant synergistic effect compared to liposome technology, or free peptide, by downregulating inflammatory factors (IL-6, TNF-α), inhibiting the mRNA and protein expression of matrix metalloproteinases (MMP1, MMP3), promoting the mRNA and protein expression of related collagens (Procollagen, Col1α1 and Col3α1), and repairing the stratum corneum barrier function, as evidenced by trans-epidermal water loss (TEWL), skin cuticle hydration (SCH), and decreased expression of β-gal, an aging marker. These findings indicated that photoaging skin can be effectively and comprehensively rejuvenated, and that even photodamage can be reversed, thereby restoring the original physiological characteristics of healthy skin. Clinical tests have confirmed that although liposome technology is an effective antiaging method which helps exert tightening and anti-wrinkle effects on human skin, LLRF is an even more effective anti-aging technique. This study reveals a highly effective technique involving a combination physical and chemical therapy that may be utilized for antiaging purposes as well as repairing lightly damaged skin, and can be made readily available in the future.

Screening the active ingredients of plants via molecular docking technology and evaluating their ability to reduce skin photoaging.

The active ingredients of plants were screened by molecular docking technology and the result were verified. According to the verification results of molecular docking, the five active ingredients were combined in equal proportions to form a compound drug. In the HaCaT photoaging model, the effects of the compound drug on antioxidant and senescence-associated secretory phenotype (SASP) factors of the NF-κB and MAPK pathways were studied via SOD and MDA kits, DCFH-DA fluorescent probes and ELISA. In the skin photoaging model, the effects of the compound drug on antioxidants and the SASP factors of the NF-κB and MAPK pathways were studied via SOD, MDA, and CAT kits and ELISA. The results revealed that the compound drug increased SOD activity, decreased the MDA content and intracellular ROS, inhibited IL-6 in the NF-κB pathway, and inhibited MMP-1 and collagen I in the MAPK pathway. The results of HE, Masson and Victoria blue skin staining revealed that the compound drug inhibited abnormal thickening of the epidermis, abnormal breaking and accumulation of collagen fibers and elastic fibers, and maintained their orderly arrangement. Moreover, the results revealed that the compound drug increased SOD, CAT and collagen I, and reduced the MDA content, the SASP factors IL-6 and TNF-α of the NF-κB pathway, and the SASP factors MMP-1 of the MAPK pathway. The above results indicate that the active ingredients of the compound drug screened by molecular docking have the potential to reduce skin photoaging.

Expression profiles and functional analysis of transfer RNA-derived small RNAs (tsRNAs) in photoaged human dermal fibroblasts.

Transfer RNA-derived small RNAs (tsRNAs) refer to a newly established family of non-coding RNAs that regulate a diverse set of biological processes. However, the function of tsRNAs in skin photoaging remains unclear. This research aims to investigate the potential correlation between tsRNAs and skin photoaging. Human dermal fibroblasts (HDFs) were irradiated with UVA at 10 J/cm2 once a day lasting for 14 days, resulting in the establishment of a photoaging model induced by UVA. To identify the expression profiles and functions of tsRNAs, tsRNA sequencing and bioinformatics analysis were conducted. qPCR was employed to validate the results of differentially expressed (DE) tsRNAs. A total of 34 tsRNAs exhibited significant differential expression between the UVA and control groups (n = 3), with nine upregulated and 25 downregulated (log2 fold change >1.5, p-value <0.05). Six tsRNAs were selected at random and validated by qRT-PCR. The enrichment analysis of DE tsRNAs target genes indicated that the dysregulated tsRNAs appeared to be connected with cell cycle, DNA replication and the AGE-RAGE signaling pathway. The expression of tsRNAs was found to be aberrant in UVA-HDF. These findings provide insights into the UVA-induced damage and potential target genes for skin photoaging.

5-aminolevulinic acid photodynamic therapy protects against UVB-induced skin photoaging: A DNA-repairing mechanism involving the BER signalling pathway.

Low-dose 5-aminolevulinic acid photodynamic therapy (ALA-PDT) has been used to cope with skin photoaging, and is thought to involve DNA damage repair responses. However, it is still unknown how low-dose ALA-PDT regulates DNA damage repair to curb skin photoaging. We established a photoaging model using human dermal fibroblasts (HDFs) and rat skin. RNA-sequencing (RNA-seq) analysis was conducted to identify differentially expressed genes (DEGs) in HDFs before and after low-dose ALA-PDT treatment, followed by bioinformatics analysis. Senescence-associated β-galactosidase (SA-β-gal) staining was employed to assess skin aging-related manifestations and Western blotting to evaluate the expression of associated proteins. A comet assay was used to detect cellular DNA damage, while immunofluorescence to examine the expression of 8-hydroxy-2'-deoxyguanosine (8-oxo-dG) in cells and skin tissues. In both invivo and invitro models, low-dose ALA-PDT alleviated the manifestations of ultraviolet B (UVB)-induced skin photoaging. Low-dose ALA-PDT significantly reduced DNA damage in photoaged HDFs. Furthermore, low-dose ALA-PDT accelerated the clearance of the photoproduct 8-oxo-dG in photoaged HDFs and superficial dermis of photoaged rat skin. RNA-seq analysis suggested that low-dose ALA-PDT upregulated the expression of key genes in the base excision repair (BER) pathway. Further functional validation showed that inhibition on BER expression by using UPF1069 significantly suppressed SA-β-gal activity, G2/M phase ratio, expression of aging-associated proteins P16, P21, P53, and MUTYH proteins, as well as clearance of the photoproduct 8-oxo-dG in photoaged HDFs. Low-dose ALA-PDT exerts anti-photoaging effects by activating the BER signalling pathway.

The role and mechanism of engineered nanovesicles derived from hair follicle mesenchymal stem cells in the treatment of UVB-induced skin photoaging.

Extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs) are effective in the treatment of skin photoaging; however, their low yield and functional decline with passage progression limit their clinical application. Cell-derived nanovesicles (CNVs) are potential alternatives that can address the limitations of EVs derived from MSCs and are conducive to clinical transformations. Hair follicle mesenchymal stem cells (HFMSCs), a type of MSCs, have demonstrated the function of repairing skin tissues; nevertheless, the efficacy of CNVs from HFMSCs (HFMSC-CNVs) in the treatment of skin photoaging remains unclear. Therefore, ultraviolet radiation B (UVB)-induced photoaging nude mice and human dermal fibroblasts (HDFs) were used as experimental models to investigate the therapeutic effects of HFMSC-CNVs in photoaging models. HFMSC-CNVs were successfully prepared using the mechanical extrusion method. UVB-induced nude mice and HDFs were used as experimental models of photoaging. Multiple approaches, including hematoxylin-eosin and Masson staining, immunohistochemistry, immunofluorescence, detection of reactive oxygen species (ROS), flow cytometry, western blotting, and other experimental methods, were combined to investigate the possible effects and mechanisms of HFMSC-CNVs in the treatment of skin photoaging. In the nude mouse model of skin photoaging, treatment with HFMSC-CNVs reduced UVB-induced skin wrinkles (p < 0.05) and subcutaneous capillary dilation, alleviated epidermis thickening (p < 0.001), and dermal thinning (p < 0.001). Furthermore, HFMSC-CNVs upregulated proliferating cell nuclear antigen (PCNA) expression (p < 0.05) and decreased the levels of ROS, β-galactosidase (β-Gal), and CD86 (p < 0.01). Invitro experiments, treatment with HFMSC-CNVs enhanced the cellular activity of UVB-exposed HDFs (p < 0.05), and reduced ROS levels and the percentage of senescent cells (p < 0.001), and alleviated cell cycle arrest (p < 0.001). HFMSC-CNVs upregulated the expression of Collagen I (Col I), SMAD2/3, transforming growth factor beta (TGF-β), catalase (CAT), glutathione peroxidase-1 (GPX-1), and superoxide dismutase-1 (SOD-1) (p < 0.05) and downregulated the expression of cycle suppressor protein (p53), cell cycle suppressor protein (p21), and matrix metalloproteinase 3 (MMP3) (p < 0.05). Conclusively, the anti-photoaging properties of HFMSC-CNVs were confirmed both invivo and invitro. HFMSC-CNVs exert anti-photoaging effects by alleviating cell cycle arrest, decreasing cellular senescence and macrophage infiltration, promoting cell proliferation and extracellular matrix (ECM) production, and reducing oxidative stress by increasing the activity of antioxidant enzymes.

Transdermal Delivery of Recombinant Human Growth Hormone by Liposomal Gel for Skin Photoaging Therapy.

Human growth hormone (hGH) has emerged as a promising therapeutic agent to prevent and treat skin photoaging. However, the success of hGH therapy largely lies in the availability of an optimal delivery system that enables the efficient delivery of hGH to the dermal layer of the skin. Here, we report a delivery system of hyaluronic acid/liposome-gel-encapsulated hGH (HA/HL-Gel) that can transdermally deliver hGH into the skin for hGH-based photoaging therapy through the upregulation of collagen type I (collagen-I). Specifically, hGH-liposomes were prepared by ethanol injection and then modified with HA to achieve specific targeting. The best formulation of HA/hGH-liposomes (HA/HL) had a high encapsulation efficiency (about 20%), with a size of 180 ± 1.2 nm. The optimized HA/HL was further incorporated into the carbomer gel to form an HA/HL-Gel. The biological activity of HA/HL on human dermal fibroblasts (HDFs) was confirmed by the elevated expression level of collagen-I through the enhanced local formation of insulin-like growth factor-1 (IGF-1) in the photoaging model. Moreover, HA/HL-Gel reduced ultraviolet (UV)-induced erythema and wrinkle formation. Meanwhile, immunohistochemical staining further showed higher levels of collagen-I in the HA/HL-Gel group compared to other groups tested. Taken together, these results demonstrate that HA/HL-Gel treatment could significantly ameliorate skin photoaging and thus may be used as a clinical potential for antiaging therapy.

Salvianolic acid B protects against UVB-induced skin aging via activation of NRF2

BackgroundProlonged exposure to sun radiation may result in harmful skin photoaging. Therefore, discovering novel anti-photoaging treatment modalities is critical. An active component isolated from Salvia miltiorrhiza (SM), Salvianolic acid B (Sal-B), is a robust antioxidant and anti-inflammatory agent. This investigation aimed to discover the therapeutic impact and pathways of salvianolic acid B for UVB-induced skin photoaging, an area that remains unexplored. MethodsWe conducted in vitro experiments on human dermal fibroblasts (HDFs) exposed to UVB radiation, assessing cellular senescence, superoxide dismutase (SOD) activity, cell viability, proliferation, migration, levels of reactive oxygen species (ROS), and mitochondrial health. The potential mechanism of Sal-B was analyzed using RNA sequencing, with further validation through Western blotting, PCR, and nuclear factor erythroid 2-related factor 2 (NRF2) silencing methods. In vivo, a model of skin photoaging induced by UVB in nude mice was employed. The collagen fiber levels were assessed utilizing hematoxylin and eosin (H&E), Masson, and Sirus red staining. Additionally, NRF2 and related gene and protein expression levels were identified utilizing PCR and Western blotting. ResultsSal-B was found to significantly counteract photoaging in UVB-exposed skin fibroblasts, reducing aging-related decline in fibroblast proliferation and an increase in apoptosis. It was observed that Sal-B aids in protecting mitochondria from excessive ROS production by promoting NRF2 nuclear translocation. NRF2 knockdown experiments established its necessity for Sal-B's anti-photoaging effects. The in vivo studies also verified Sal-B's anti-photoaging efficacy, surpassing that of tretinoin (Retino-A). These outcomes offer novel insights into the contribution of Sal-B in developing clinical treatment modalities for UVB-induced photodamage in skin fibroblasts. ConclusionIn this investigation, we identified the Sal-B protective impact on the senescence of dermal fibroblasts and skin photoaging induced by radiation of UVB. The outcomes suggest Sal-B as a potential modulator of the NRF2 signaling pathway.

Resveratrol activates autophagy and protects from UVA-induced photoaging in human skin fibroblasts and the skin of male mice by regulating the AMPK pathway

Skin photoaging is mostly caused by ultraviolet A (UVA), although active medications to effectively counteract UVA-induced photoaging have not yet been created. Resveratrol, a naturally occurring polyphenol found in the skin of grapes, has been shown to have various biological functions such as anti-inflammatory and antioxidant characteristics. However, the role of resveratrol in UVA-induced photoaging has not been clarified. We investigated the mechanism of action of resveratrol by UVA irradiation of human skin fibroblasts (HSF) and innovatively modified a mouse model of photoaging. The results demonstrated that resveratrol promoted AMP-activated protein kinase (AMPK) phosphorylation to activate autophagy, reduce reactive oxygen species (ROS) production, inhibit apoptosis, and restore normal cell cycle to alleviate UVA-induced photoaging. In addition, subcutaneous injection of resveratrol not only improved the symptoms of roughness, erythema, and increased wrinkles in the skin of UVA photodamaged mice, but also alleviated epidermal hyperkeratosis and hyperpigmentation, reduced inflammatory responses, and inhibited collagen fiber degradation. In conclusion, our studies proved that resveratrol can treat UVA-induced photoaging and elucidated the possible molecular mechanisms involved, providing a new therapeutic strategy for future anti-aging.

Salvianolic acid A prevents UV-induced skin damage by inhibiting the cGAS-STING pathway

DNA damage resulting from UV irradiation on the skin has been extensively documented in numerous studies. In our prior investigations, we demonstrated that UVB-induced DNA breakage from keratinocytes can activate the cGAS-STING pathway in macrophages. The cGAS-STING signaling pathway serves as the principal effector for detecting and responding to abnormal double-stranded DNA in the cytoplasm. Expanding on our previous findings, we have further validated that STING knockout significantly diminishes UVB-induced skin damage, emphasizing the critical role of cGAS-STING activation in this context. Salvianolic acid A, a principal active constituent of Salvia miltiorrhiza Burge, has been extensively studied for its therapeutic effects in conditions such as coronary heart disease, angina pectoris, and diabetic peripheral neuropathy. However, its effect on cGAS-STING pathway and its ability to alleviate skin damage have not been previously reported. In a co-culture system, supernatant from UVB-treated keratinocytes induced IRF3 activation in macrophages, and this activation was inhibited by salvianolic acid A. Our investigation, employing photodamage and photoaging models, establishes that salvianolic acid A effectively mitigates UV-induced epidermal thickening and collagen degeneration. Treatment with salvianolic acid A significantly reduced skin damage, epidermal thickness increase, and keratinocyte hyperproliferation compared to the untreated photo-damage and photoaging model groups. In summary, salvianolic acid A emerges as a promising candidate for preventing UV-induced skin damage by inhibiting cGAS-STING activation. This research enhances our understanding of the intricate mechanisms underlying skin photodamage and provides a potential avenue for the development of therapeutic interventions.

The therapeutic effects of ADSCs on photoaging of skin induced by UVB irradiation.

Skin photoaging affects appearance and is associated with a variety of skin diseases, even skin cancer. Therefore, the prevention and treatment of skin photoaging is very important. However, there is a lack of effective evaluation methods, so it is an urgent problem to explore a comprehensive, non-invasive and in vivo evaluation method. Adipose-derived mesenchymal stem cells (ADSCs) are widely used to improve skin conditions as easier to obtain and positive effects. Recently, as the development of ultrasound technology, skin ultrasound has been widely used. Changes in skin layer and structure can be observed by high-frequency ultrasound (HFUS). In addition, Shear wave elastography (SWE) technology can be used to monitor the change of skin hardness. However, it is necessary to further explore the ultrasound parameters in interpreting histological changes. We simulate the progression and treatment process of human skin photoaging by using UVB-induced nude mice skin photoaging model and ADSCs injection. The analysis of the degree and therapeutic effect of skin photoaging was conducted by HFUS, SWE and to verify with histopathology. Our study aims to clarify the value of HFUS combined SWE techniques in evaluating the degree and therapeutic efficacy of skin photoaging, which provides theoretical basis for diagnosis and treatment evaluation systems.

Rosemary extract and rosmarinic acid accelerate elastic fiber formation by increasing the expression of elastic fiber components in dermal fibroblasts.

Ultraviolet (UV)-induced skin photoaging is caused by qualitative and quantitative degradation of dermal extracellular matrix components such as collagen and elastic fibers. Elastic fibers are important for maintaining cutaneous elasticity, despite their small amount in the skin. Previously, microfibril-associated protein 4 (MFAP-4), which is downregulated in photoaging dermis, has been found to be essential for elastic fiber formation by interaction with both fibrillin-1 and elastin, which are core components of elastic fiber. In addition, enhanced cutaneous MFAP-4 expression in a human skin-xenografted murine photoaging model protects against UV-induced photodamage accompanied by the prevention of elastic fiber degradation and aggravated elasticity. We therefore hypothesized that the upregulation of MFAP-4 in dermal fibroblasts may more efficiently accelerate elastic fiber formation. We screened botanical extracts for MFAP-4 expression-promoting activity in normal human dermal fibroblasts (NHDFs). We found that rosemary extract markedly promotes early microfibril formation and mature elastic fiber formation along with a significant upregulation of not only MFAP-4 but also fibrillin-1 and elastin in NHDFs. Furthermore, rosmarinic acid, which is abundant in rosemary extract, accelerated elastic fiber formation via upregulation of transforming growth factor β-1. This was achieved by the induction of cAMP response element-binding protein phosphorylation, demonstrating that rosmarinic acid represents one of the active ingredients in rosemary extract. Based on the findings in this study, we conclude that rosemary extract and rosmarinic acid represent promising materials that exert a preventive or ameliorative effect on skin photoaging by accelerating elastic fiber formation.

Myconoside and Calceolarioside E Restrain UV-Induced Skin Photoaging by Activating NRF2-Mediated Defense Mechanisms.

Chronic and excessive ultraviolet (UVA/UVB) irradiation exposure is known as a major contributor to premature skin aging, which leads to excessive reactive oxygen species generation, disturbed extracellular matrix homeostasis, DNA damage, and chronic inflammation. Sunscreen products are the major preventive option against UVR-induced photodamage, mostly counteracting the acute skin effects and only mildly counteracting accelerated aging. Therefore, novel anti-photoaging and photopreventive compounds are a subject of increased scientific interest. Our previous investigations revealed that the endemic plant Haberlea rhodopensis Friv. (HRE) activates the antioxidant defense through an NRF2-mediated mechanism in neutrophiles. In the present study, we aimed to investigate the photoprotective potential of HRE and two of its specialized compounds-the phenylethanoid glycosides myconoside (MYC) and calceolarioside E (CAL)-in UVA/UVB-stimulated human keratinocytes in an in vitro model of photoaging. The obtained data demonstrated that the application of HRE, MYC, and CAL significantly reduced intracellular ROS formation in UVR-exposed HaCaT cells. The NRF2/PGC-1α and TGF-1β/Smad/Wnt signaling pathways were pointed out as having a critical role in the observed CAL- and MYC-induced photoprotective effect. Collectively, CAL is worth further evaluation as a potent natural NRF2 activator and a promising photoprotective agent that leads to the prevention of UVA/UVB-induced premature skin aging.

Recombinant collagen for the repair of skin wounds and photo-aging damage.

The skin, being the body's primary defense mechanism, is susceptible to various injuries such as epidermal wounds, natural aging, and ultraviolet-induced damage. As a result, there is growing interest in researching skin repair methods. Traditional animal-derived collagen, widely available on the market, poses risks due to its immunogenicity and potential for viral contamination. In contrast, recombinant collagen sourced from human genes offers a safer alternative. To investigate the potential of human recombinant collagen in skin repair, our research team applied two types, type I human collagen (Col I) and CF-1552(I), to two different skin injury models: a wound-healing model and a photo-aging model. Our findings indicate that both Col I and CF-1552(I) effectively enhance wound healing and repair skin damaged by ultraviolet exposure. Notably, CF-1552(I) showed effects comparable to Col I in promoting cell proliferation in the wound-healing model and increasing malondialdehyde content in the photo-aging model, suggesting that CF-1552(I) may offer greater potential for skin repair compared to the larger Col I molecule.

Needle-Free Injection of Metformin Ameliorates Skin Photoaging Through Inhibition of Ferroptosis and Oxidative Stress.

Skin photoaging is a complex process of skin aging caused by continuous exposure to ultraviolet (UV) radiation through oxidative stress and other pathways, yet effective treatments are scarce. Metformin is a drug with both anti-senescence and antioxidant functions; however, there are fewer studies on photoaging. The study aimed to investigate the role of needle-free injection of metformin in alleviating ultraviolet radiation B (UVB) induced skin photoaging, and to explore the mechanisms through which metformin alleviates fibroblast photoaging by inhibiting ferroptosis and oxidative stress. In our study, we initially performed bioinformatic analysis on the gene expression profile (GSE38308), and our RNA sequencing (RNA-Seq) found that photoaging is associated with ferroptosis. We investigated the potential skin-protective mechanism of metformin by utilizing a UVB-induced rat skin photoaging model and human skin fibroblasts (HSF) treated with UVB. For in vitro experiments, cellular senescence was detected using SA-β-galactosidase staining and p16 in western blot. Ferroptosis and oxidative stress were assessed via western blot (glutathione Peroxidase 4 (GPX4) and nuclear factor erythroid-2-related factor 2 (Nrf2)), reactive oxygen species (ROS) levels, transmission electron microscope, Lillie's staining, and immunofluorescence staining. During in vivo experiments, metformin was administered by needle-free jet injectors injected into the backs of rats. The effectiveness of metformin was detected using the Masson staining and western blot. We found that the ferroptosis pathway was closely associated with photoaging through bioinformatics analysis. In the UVB-induced photoaging HSF cells, treatment with metformin exhibits the following effects: a reduction in blue-stained granules in SA-β-galactosidase staining and a decrease in the expression of p16, indicating a reduction in cellular senescence. Moreover, metformin leads to decreased ROS levels and increased expression of the oxidative stress-related protein Nrf2, suggesting inhibition of oxidative stress within the cells. Additionally, metformin results in an elevation of GPX4 expression, a decrease in blue-stained granules in Lillie's staining, and a reduction in ferroptosis-associated mitochondrial damage, indicating a decline in ferroptosis. Needle-free injection of metformin could directly achieve therapeutic effects by affecting HSF cells in the dermis. The needle-free injection of metformin treatment effectively improved the photoaging skin in rats compared to the photoaging group, ameliorated oxidative stress, and reduced ferroptosis. Our data highlights a novel needle-free injection of metformin that improves photoaging and has good therapeutic potential.

Association between SPRY1 and TET3 in skin photoaging and natural aging mechanisms.

SPRY1 is associated with the invasiveness and prognosis of various tumors, and TET3 affects aging by regulating gene expression. We investigated the roles of SPRY1 and TET3 in natural skin aging, replicative aging, and photoaging, along with the effect of UVA on genome-wide DNA methylation in HaCaT cells. TET3 and SPRY1 expression were measured in the skin of patients of different age groups, as well as invitro human skin, HaCaT cell replicative senescence, and HaCaT and HaCaT-siTET3 cell photoaging models. Senescence was verified using β-galactosidase staining, and DNA damage was detected using immunofluorescence staining for γ-H2A.X. 5-Methyl cytosine (5-mC) content in the genome was determined using ELISA. SPRY1 expression increased with age, whereas TET3 expression decreased. Similarly, SPRY1 was upregulated and TET3 was downregulated with increasing cell passages. TET3-siRNA upregulated SPRY1 expression in HaCaT cells. UVA irradiation promoted HaCaT cell senescence and induced cellular DNA damage. SPRY1 was upregulated and TET3 was downregulated upon UVA irradiation. Genome-wide 5-mC content increased upon TET3 silencing and UVA irradiation, indicating a surge in overall methylation. SPRY1 and TET3 are natural skin aging-related genes that counteract to regulate replicative aging and UVA-induced photoaging in HaCaT cells. The cell photoaging model may limit experimental bias caused by different exposure times of skin model samples.

A guideline of antiphotoaging activity of polysaccharide assay in vitro and in vivo

AbstractPeople have become increasingly concerned about skin beauty and health issues, especially skin photoaging. Previous studies showed that skin photoaging was characterized by skin roughness and dryness. It was caused by UV radiation‐related dysregulation of matrix metalloproteinases (MMPs) and oxidative stress. Therefore, to investigate the antiphotoaging activity of polysaccharides, it is critical to establish the skin photoaging model, including the in vitro cellular model and the in vivo animal model. The in vitro cellular model is judged by cell viability, the MMPs expression, oxidative detection, and the quantities of inflammation cytokines. Moreover, both the damage to the epidermis and dermis of nude mice and the change of collagen content in the skin are indicators of the in vivo animal model. Thus, in this guideline, we tried to summarize the practice of antiphotoaging activity for polysaccharides.

Comparison of five retinoids for anti-photoaging therapy: Evaluation of anti-inflammatory and anti-oxidative activities invitro and therapeutic efficacy invivo.

Over the past decades, increasing evidences have demonstrated that five retinoids, including retinol (ROL), retinol acetate (RAc), retinol propionate (RP), retinol palmitate (RPalm), and hydroxypinacolone retinoate (HPR), can be potential therapeutic agents for skin photoaging. However, therapeutic efficacies and biosafety have never been compared to these compounds. This study aimed to determine the optimal retinoid type(s) for anti-photoaging therapy both invitro and invivo. Our data demonstrated that four retinoids (RPalm, RP, HPR and ROL) but not RAc were effective for anti-photoaging treatment at 5 μg/mL invitro, with action mechanisms associated with antioxidative, anti-inflammatory and anti-skin ECM degradation activities. Notably, both RPalm and RP appeared superior to HPR and ROL for those activities. Importantly, both RPalm and RP were shown to be optimal for anti-photoaging therapy when topically applied at 5 mg/kg in a UVB-induced mice model of photoaging, which is consistent with their high anti-photoaging activities invitro. Additionally, topical application of these five retinoids showed satisfactory biosafety without causing significant apoptosis in animal organs, although RP application led to a slight decline in animal body weights. Collectively, these data have laid a good foundation for the next development of the clinical application of these retinoids for skin healthcare.

Oral intake of collagen hydrolysate from mackerel scad (Decapterus macarellus) attenuates skin photoaging by suppressing the UVB-induced expression of MMP-1 and IL-6.

Excessive skin exposure to UVB radiation can induce photoaging caused by an imbalance in oxidative stress and inflammatory responses, damaging the skin's structure and surface layer. A previous study revealed that collagen hydrolisate extracted from the skin of mackarel scads (Decapterus macarellus) had antiaging properties thatwere tested invitro, which serves as a foundation for asubsequent study of its use invivo. This study aimed at investigating the repair effect of the mackerel scad's skin collagen hydrolysate (MSS-CH) in photoaging conditions in amouse model. MSS-CH was given orally in mice model of skin photoaging under chronic exposure to UVB irradiation for12weeks. Morphological and histological changes on the skin were evaluated using SEM and HE staining, along withthe measurement of the expression of matrix metalloproteinases (MMP-1) and cytokine pro-inflammatory interleukin 6 (IL-6) using ELISA. MSS-CH inhibits the occurrence of epidermal thickening and damage to the dermal layer of the skin. As aresult, it restores the epidermis' barrier function and reduces surface damage caused by photoaging. The skin ofthe MSS-CH treated group exhibited improved physical appearance with reduced fine lines, wrinkles, and enhanced smoothness. Additionally, administering MSS-CH to the mice groups reduced the expression of MMP-1 and IL-6 in UVB-exposed skin. Altogether, this invivo study demonstrates thephotoaging-protective properties of CH-MSS, aligning with previous invitro data. Thus, MSS-CH emerges as a strong candidate for use as an ingredient in nutraceuticals and biocosmetics.