The combination of tetramethylpyrazine and vitamin A acid in the treatment of skin photoaging by activating the HIF-1α pathway.

Skin photoaging is a skin degenerative disease that causes patients to develop malignant tumors. The existing clinical treatment of photoaging has limitations. This greatly reduces the recovery rate of photoaging patients. Studies have confirmed that Ligusticum wallichii Franch (LWF) monomer tetramethylpyrazine (TMP) alleviates various skin diseases. The combination of traditional Chinese medicine and Western medicine helps with this process. Our research aimed to explore the specific treatment mode and molecular mechanism of TMP in treating skin photoaging. CCK-8 assays were used to evaluate the activity and toxicity of HaCaT cells. ß-galactosidase aging, Carbonyl compound and nitrosylated tyrosine assays were used to analyze the aging of HaCaT cells. ROS assays and ELISA were used to analyze the enrichment of ROS. The molecular docking experiment analyzed the binding of TMP and HIF-1α. qRT-PCR and Western blot were used to detect the activation of skin aging-related pathways. HE staining was used to analyze the thickness of the stratum corneum skin on the back skin of mice. 200µg/L LWF alleviates cellular photoaging and mouse skin photoaging by reducing ROS enrichment. Its monomer TMP plays an important role in this process. The combination of TMP and HIF-1α accelerates the degradation of ROS by activating the Nrf2/ARE signaling pathway. This process reduces the apoptosis of cells damaged by light. In addition, we also found that the combination of TMP and retinoic acid (RA) is more beneficial for the treatment of skin damage caused by light in mice. The combination therapy of TMP and RA alleviates skin oxidative stress response through overexpression of HIF-1α. This plan is beneficial for the treatment of skin photoaging.

Radiofrequency Treatment Attenuates Age-Related Changes in Dermal-Epidermal Junctions of Animal Skin.

The dermal-epidermal junction (DEJ) is essential for maintaining skin structural integrity and regulating cell survival and proliferation. Thus, DEJ rejuvenation is key for skin revitalization, particularly in age-related DEJ deterioration. Radiofrequency (RF) treatment, known for its ability to enhance collagen fiber production through thermal mechanisms and increase heat shock protein (HSP) expression, has emerged as a promising method for skin rejuvenation. Additionally, RF activates Piezo1, an ion channel implicated in macrophage polarization toward an M2 phenotype and enhanced TGF-ß production. This study investigated the impact of RF treatment on HSP47 and HSP90 expression, known stimulators of DEJ protein expression. Furthermore, using in vitro and aged animal skin models, we assessed whether RF-induced Piezo1 activation and the subsequent M2 polarization could counter age-related DEJ changes. The RF treatment of H2O2-induced senescent keratinocytes upregulated the expression of HSP47, HSP90, TGF-ß, and DEJ proteins, including collagen XVII. Similarly, the RF treatment of senescent macrophages increased Piezo1 and CD206 (M2 marker) expression. Conditioned media from RF-treated senescent macrophages enhanced the expression of TGF-ß and DEJ proteins, such as nidogen and collagen IV, in senescent fibroblasts. In aged animal skin, RF treatment increased the expression of HSP47, HSP90, Piezo1, markers associated with M2 polarization, IL-10, and TGF-ß. Additionally, RF treatment enhanced DEJ protein expression. Moreover, RF reduced lamina densa replication, disrupted lesions, promoted hemidesmosome formation, and increased epidermal thickness. Overall, RF treatment effectively enhanced DEJ protein expression and mitigated age-related DEJ structural changes by increasing HSP levels and activating Piezo1.

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.

Protective effects of sugarcane polyphenol against UV-B-induced photoaging in Balb/c mouse skin: Antioxidant, anti-inflammatory, and anti-glycosylation Effects.

Although the benefits of sugarcane polyphenol (SP) are well documented, its function in preventing photoaging has not yet been investigated. This study aimed to investigate the protective effects of SP in preventing ultraviolet (UV)-B-induced skin photoaging in Balb/c mice, as well as the underlying mechanism. Chlorogenic acid was determined to be the primary component of SP by using high-performance liquid chromatography-mass spectrometry. SP and chlorogenic acid were orally administrated to mice for 56 days, and UV-B radiation exposure was administered 14 days after SP and chlorogenic acid administration and lasted 42 days to cause photoaging. SP and chlorogenic acid administrations significantly alleviated the UV-B-induced mouse skin photoaging, as indicated by the decrease in epidermal thickness, increase in the collagen (COL) volume fraction, and elevation in type 1 and type 3 COL contents. Notably, both SP and chlorogenic acid effectively reversed the overexpression of matrix metalloproteinase induced by UV-B exposure in the mouse skin. Furthermore, SP and chlorogenic acid reduced the expression of receptor for advanced glycosylation end products in the mice; amplified the activities of antioxidant enzymes superoxide dismutase and catalase; reduced malondialdehyde levels; and decreased inflammatory cytokines interleukin 1ß, interleukin 6, and tumor necrosis factor α levels. SP could be a prospective dietary supplement for anti-photoaging applications due to its antioxidant, anti-inflammatory, and anti-glycosylation attributes, and chlorogenic acid might play a major role in these effects. PRACTICAL APPLICATION: This study can provide a scientific basis for the practical application of sugarcane polyphenols. We expect that sugarcane polyphenols can be used in food and beverage products to provide flavor while combating skin 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.

Treatment with synchronized radiofrequency and facial muscle stimulation: Histologic analysis of human skin for changes in collagen and elastin fibers.

BACKGROUND: Skin's exposure to intrinsic and extrinsic factors causes age-related changes, leading to a lower amount of dermal collagen and elastin. AIM: This study investigated the effects of a novel facial muscle stimulation technology combined with radiofrequency (RF) heating on dermal collagen and elastin content for the treatment of facial wrinkles and skin laxity. METHODS: The active group subjects (N = 6) received four 20-min facial treatments with simultaneous RF and facial muscle stimulation, once weekly. The control subject (N = 1) was untreated. Skin biopsies obtained at baseline, 1-month and 3-month follow-up were evaluated histologically to determine collagen and elastin fibers content. A group of independent aestheticians evaluated facial skin appearance and wrinkle severity. Patient safety was followed. RESULTS: In the active group, collagen-occupied area reached 11.91 ± 1.80 × 106 µm2 (+25.32%, p < 0.05) and 12.35 ± 1.44 × 105 µm2 (+30.00%, p < 0.05) at 1-month and 3-month follow-up visits. Elastin-occupied area at 1-month and 3-month follow-up was 1.64 ± 0.14 × 105 µm2 (+67.23%, p < 0.05), and 1.99 ± 0.21 × 105 µm2 (+102.80%, p < 0.05). In the control group, there was no significant difference (p > 0.05) in collagen and elastin fibers. Active group wrinkle scores decreased from 5 (moderate, class II) to 3 (mild, class I). All subjects, except the control, improved in appearance posttreatment. No adverse events or side effects occurred. CONCLUSION: Decreased dermal collagen and elastin levels contributes to a gradual decline in skin elasticity, leading to facial wrinkles and unfirm skin. Study results showed noticeable improvement in facial appearance and increased dermal collagen and elastin content subsequent to simultaneous, noninvasive RF, and facial muscle stimulation treatments.

Effect of glabridin combined with bakuchiol on UVB-induced skin damage and its underlying mechanism: An experimental study.

BACKGROUND: Research has demonstrated the anti-photoaging properties of glabridin and bakuchiol. METHODS: The impact of glabridin, glabridin + bakuchiol, and bakuchiol on the levels of tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1ß) in mice skin fibroblasts was observed. Furthermore, we investigated the potential roles of fibronectin (FN), interferon-γ (IFN-γ), interleukin-22 (IL-22), and transforming growth factor-ß (TGF-ß) in the tissues, and evaluated their impact on the enzymatic levels in the skin. In conjunction with transcriptomic analysis, metabolomic profiling, and network pharmacology, all samples underwent comprehensive metabolomic and principal component analysis. The Venny2.1 method was utilized to identify variances in shared metabolites between the treatment group and the UVB group, as well as between the UVB group and the control group. Subsequently, a cluster heat map was generated to forecast and analyze metabolic pathways and targets. RESULTS: The outcomes from the hematoxylin and eosin and toluidine blue staining revealed that glabridin and bakuchiol markedly decreased dermal thickness and suppressed mast cell infiltration in photoaged mice. Immunohistochemistry and Elisa analysis revealed that glabridin and bakuchiol effectively attenuated the levels of pro-inflammatory factors, including IL-1ß, tumor necrosis factor-α, IL-22, and IFN-γ. Furthermore, an increase in the levels of anti-inflammatory factors such as FN and TGF-ß was also observed. The determination of the contents of superoxide dismutase, hydroxypropyltransferase and malondialdehyde in mice dorsal skin revealed that glabridin and bakuchiol not only elevated the levels of superoxide dismutase and hydroxyproline, but also reduced malondialdehyde content. Due to the limited number of shared differential metabolites exclusively within Kyoto Encyclopedia of Genes and Genomes, comprehensive pathway enrichment analysis was not feasible. CONCLUSION: This study demonstrates that glabridin and bakuchiol effectively impede photoaging and alleviate skin inflammation in mice.

Water-soluble intracellular extract of Desmodesmus sp. YT enhanced the antioxidant capacity of human skin fibroblast to protect the skin from UV damage.

BACKGROUND: The oxidative stress induced by ultraviolet (UV) radiation is a pivotal factor in skin aging and can even contribute to the development of skin cancer. AIM: This study explored the antioxidant effect and mechanism of water-soluble intracellular extract (WIE) of Desmodesmus sp.YT (YT), aiming to develop a natural antioxidant suitable for incorporation into cosmetics. METHODS: The study evaluated the scavenging capacity of YT-WIE against free radicals and assessed its impact on human skin fibroblasts (HSF) cell viability and UV resistance using Cell Counting Kit-8 (CCK-8). Transcriptome sequencing was employed to elucidate the mechanism of action, while RT-qPCR and western blot were used to validate the expression of key genes. RESULTS: YT-WIE displayed robust antioxidant activity, demonstrating potent scavenging abilities against 2,2-diphenyl-1-picrylhydrazyl (DPPH; IC50 = 0.55 mg mL-1), 2,2'-Azino-bis (3 ethylbenzothiazoline-6-sulfonic acid; ABTS; IC50 = 3.11 mg mL-1), Hydroxyl (·OH; IC50 = 2.21 mg mL-1), and Superoxide anion (O2 •-; IC50 = 0.98 mg mL-1). Furthermore, compared to the control group, the YT-WIE group exhibited an 89.30% enhancement in HSF viability and a 44.63% increase in survival rate post-UV irradiation. Significant upregulation of antioxidant genes (GCLC, GCLM, TXNRD1, HMOX1, NQO1) was observed with YT-WIE treatment at 400 µg mL-1, with fold increases ranging from 1.13 to 5.85 times. CONCLUSION: YT-WIE demonstrated considerable potential as an antioxidant, shielding human cells from undue oxidative stress triggered by external stimuli such as UV radiation. This suggests its promising application in cosmetics antioxidants.

METTL14 affects UVB-induced human dermal fibroblasts photoaging via miR-100-3p biogenesis in an m6A-dependent manner.

Exposure to ultraviolet radiation can lead to skin photoaging, which increases the risk of skin tumors. This study aims to investigate how microRNA m6A modification contributes to skin photoaging. This study found that skin fibroblasts exposed to a single UVB dose of 30 mJ/cm2 exhibited characteristics of photoaging. The m6A level of total RNA decreased in photoaged cells with a down-regulated level of METTL14, and overexpression of METTL14 displayed a photoprotective function. Moreover, miR-100-3p was a downstream target of METTL14. And METTL14 could affect pri-miR-100 processing to mature miR-100-3p in an m6A-dependent manner via DGCR8. Furthermore, miR-100-3p targeted at 3' end untranslated region of ERRFI1 mRNA with an inhibitory effect on translation. Additionally, photoprotective effects of overexpression of METTL14 were reversed by miR-100-3p inhibitor or overexpression of ERRFI1. In UVB-induced photoaging of human skin fibroblasts, METTL14-dependent m6A can regulate miR-100-3p maturation via DGCR8 and affect skin fibroblasts photoaging through miR-100-3p/ERRFI1 axis.

Review of Fractional Nonablative Lasers for the Treatment of Dermatologic Conditions in Darker Skin Phototypes.

BACKGROUND: Fractional nonablative lasers (NAFLs) have demonstrated efficacy and safety for treating dermatologic conditions in patients with darker skin phototypes. Nonablative lasers are preferred in darker skin tones due to lower risk of postinflammatory hyperpigmentation. OBJECTIVE: This review aims to identify the ideal laser options and parameters for treating common dermatologic conditions in patients with skin types IV-VI. MATERIALS AND METHODS: A comprehensive literature search was conducted on PubMed in May 2023. Of 1,065 articles were identified, and 40 articles met the inclusion criteria. The studies were classified based on design, dermatologic condition, and skin phototype of patients, and assigned levels of evidence according to the Modified Criteria of the Oxford Center of Evidence Based Medicine. RESULTS: Strong level 1 evidence supports the treatment of melasma and atrophic scars using NAFL. Moderate level 2 evidence was found for using NAFL in acne vulgaris, striae, and skin rejuvenation; 45% of the studies examined skin types III-IV, 20% III-V, 7.5% II-IV, 5% II-V, 5% IV alone, and 2.5% I-IV. CONCLUSION: Further research is needed to determine the optimal treatment modalities and parameters for skin types V and VI. Appropriate device selection and conservative treatment settings are crucial for optimizing outcomes and minimizing adverse events.

Changes of Facial Lipidomics by Intense Pulsed Light Treatment Based on LC-MS.

BACKGROUND: Intense pulsed light (IPL) has been widely used to improve cutaneous photoaging in recent years. Several studies began to explore the changes of skin barrier function after treatment, but the changes of skin surface lipids (SSL), especially specific lipid content and types are still unclear. METHODS: A total of 25 female volunteers were included in our study, and each of them received three full-face treatments with one month apart. Before the first treatment and 1 month after the last treatment, we collected clinical photos and skin stratum corneum samples from individuals. A 5-level scale was used to evaluate the efficacy of IPL treatment, liquid chromatography-mass spectrometry (LC-MS), and Orthogonal Partial Least Squares Discrimination Analysis (OPLS-DA) were used to analyze the changes of SSL. RESULTS: Two patients got no improvement after treatment, 6 patients had poor improvement and mild improvement was achieved in 9 patients, 5 and 3 patients reported moderate and significant improvement. The overall "effective" rate was 68 % and the "significant effective" rate was 32 %. The results showed 18 lipid subclasses and 487 lipid molecules were identified. The change of total lipid volume was not statistically significant (P = 0.088>0.05), but lipid subclass analysis showed the amount of Triglyceride (TG), Phosphatidic Acid (PA), Phosphatidylglycerol (PG) and Lysophosphatidylglycerol (LPG) were significantly increased (P < 0.05). There were 55 kinds of lipid molecules with significant difference after treatment (P < 0.05), and 51 of them belong to TG. The analysis of chain saturation of TG showed that the quantity of TG with 0, 1 and 2 unsaturated bonds increased significantly (P < 0.05). CONCLUSIONS: IPL treatment does not have a significant effect on the overall amount of lipids while the amount of TG, PA, PG, LPG were significantly increased. These lipid changes may potentially improve the skin barrier function, but more high-quality and comprehensive studies are still needed. BULLET POINT: Lipidomics analysis based on LC-MS; Changes of skin surface lipid after IPL treatment; the relationships between skin surface lipid and skin barrier functions. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Native collagen sheet mask improves skin health and appearance: A comprehensive clinical evaluation.

BACKGROUND: Collagen, a critical structural protein found abundantly in animal skin and bones, has become increasingly recognized for its potential therapeutic role in skincare. Despite growing interest, the scientific evidence for the efficacy of collagen sheet masks remains limited. The principal objective of our study was to provide insights into the multifaceted role of collagen in skin health, with a specific focus on its application in collagen sheet masks. METHODS: The effects of a collagen sheet mask consisting of >92% native bovine collagen were investigated. The soluble protein components of the collagen matrix were analyzed and the influence of soluble collagen components on fibroblast regulation was examined. Scanning Electron Microscope (SEM) analysis was performed for structural analysis and effect on irritated skin. Five different clinical studies were conducted, including a comparison of the diversity of the skin microbiome, the tolerance and local irritating reactions in atopic dermatitis, an evaluation of skin redness after UV radiation, wrinkle reduction, and hydration and skin roughness of the collagen mask in comparison to a pre-soaked cellulose sheet mask. RESULTS: The collagen mask contains soluble protein components, including small collagen peptides. The mask showed potential for promoting fibroblast activity. SEM analysis showed a native collagen structure similar to human dermis. The mask maintained the skin microbiome diversity and decreased skin pH levels. It demonstrated good tolerability on both intact and lesional skin and had a significant effect in reducing erythema caused by UV radiation compared to other skincare products. It showed significant improvements in skin hydration and the volume of eye wrinkles and was more effective than pre-soaked cellulose sheet masks. CONCLUSION: Collagen sheet masks have the potential to positively impact skin health and appearance by increasing hydration, reducing erythema, minimizing wrinkles, and maintaining a healthy skin microbiome and skin barrier.

Carcinogenic effects of prolonged daily low-emission phototherapy in psoriasis.

BACKGROUND: Low-dose UV treatment has been shown to be effective in mild psoriasis. However, the prolonged use of this treatment modality may raise concerns about its safety. These concerns are mainly focused on potential carcinogenic risks and overuse of this treatment modality. OBJECTIVES: This study was set out to evaluate possible carcinogenic risks of prolonged low-dose phototherapy. METHODS: Three groups of psoriasis patients were evaluated: patients with local treatment only (n = 15); low-dose UV treatment at home for at least 18 months (n = 39); and patients with conventional NB-UVB (n = 8). Patients underwent visual inspection for signs of photoageing, and p53, CPDs and γH2AX were measured in skin biopsies. Patients undergoing low-dose phototherapy answered a survey about their recent patterns of use in a survey. RESULTS: In the skin biopsies, low-dose UV treatment caused a lower amount of CPDs (p = .016) and p53 (p = .015) than NB-UVB. γH2AX did not show a significant difference. Self-report in patients undergoing low-dose phototherapy showed only one case of overuse (2.7%). Visual skin inspection showed no difference in signs of photoageing in the three groups. CONCLUSION: Prolonged treatment with low-dose UV for 18 months appears at least as safe as a course of conventional NB-UVB.

Study of a 532/1064 Fractional Picosecond Laser for Facial Rejuvenation.

BACKGROUND AND OBJECTIVES: Picosecond (ps) fractional lasers create small wounds, presumably by laser-induced optical breakdown. We studied a ps fractional laser in the treatment of wrinkles and mottled pigment. MATERIALS AND METHODS: This was a single center, prospective, open-label clinical trial. Patients with at least 2 facial areas, with visible wrinkles and dyschromia, were enrolled in the study and received 3 treatments at monthly intervals and appeared at 3 follow-up visits at 1, 3, and 6 months after treatment. The laser is an 800 ps fractional system with nominal 10 mm macrospot diameter. Both 532 nm and 1,064 nm wavelengths were applied in each subject. Wrinkle and pigmentation clearance were assessed by 2 blinded investigators using a 5-point clearance scale. Skin improvement was assessed by investigators using the 5-point Global Aesthetic Improvement (GAI) Scale based on before/after photographs for the following categories: (1) fine lines/wrinkles and (2) pigmentation. RESULTS: A total of 18 healthy subjects at a single site were enrolled. At least moderate pigmentation and fine line/wrinkles improvement were observed in 93% and 79% of patients at 1 month after the last treatment according to GAI, respectively. Pigment clearance approached a mean of approximately 40%. CONCLUSION: A ps 1,064/532 fractional laser achieves reduction in fine lines and pigment.

A novel glyceroglycolipid from brown algae Ishige okamurae improve photoaging and counteract inflammation in UVB-induced HaCaT cells.

BACKGROUND: Excessive exposure to Ultraviolet (UV) rays can cause premature skin aging. Ishigoside (IGS) is a new glyceroglycolipid compound isolated from brown algal Ishige okamurae, However, whether it can protect the skin from (Ultraviolet-B) UVB damage has not been illuminated. METHODS: The in vitro anti-photoaging effect of IGS was conducted in UVB-induced HaCaT. The HaCaT cells were divided into the following five groups: (1) cells didn't suffer from UVB irradiation or IGS treatment. (2-5) Cells were treated with various concentrations of IGS (0, 10, 50, and 100 µM) and irradiated by 40 mJ/cm2 UVB. The Matrix metalloproteinase (MMP) of photoaging process was determined by ELISA kits and the latent interaction between IGS and MMP was further performed by molecular docking. The crucial signaling pathway proteins involved in the collagen synthesis and degradation were subsequently evaluated by Western blotting, immunofluorescence and EMSA. RESULTS: IGS effectively suppresses the high expressions and secretions of matrix metalloproteinases (MMPs) and photo-inflammation by blocking MAPKs, AP-1 and NF-κB. Meanwhile, increasing antioxidant enzyme expression. Molecular docking results suggest that inhibition of IGS on MMPs may be attributed to its hydrogen supply and hydrophobic capacity. In addition, IGS enhanced procollagen production by upregulating the TGF-ß/Smad pathways. CONCLUSIONS: IGS exhibited anti-photoaging activity in UVB-damage HaCaT. These effects might be a contribution by its suppression of MMPs expression via MAPKs, AP-1 and NF-κB pathway and have anti-oxidative and anti-inflammatory effects. Therefore, IGS has the great potential to become skin-care products or functional foods for preventing skin photoaging.

Defining skin aging and its risk factors: a systematic review and meta-analysis.

Skin aging has been defined to encompass both intrinsic and extrinsic aging, with extrinsic aging effected by environmental influences and overlaying the effects of chronological aging. The risk factors of skin aging have been studied previously, using methods of quantifying skin aging. However, these studies have yet to be reviewed. To better understand skin aging risk factors and collate the available data, we aimed to conduct a systematic review and meta-analysis. We conducted our systematic review in compliance with Preferred Reporting Item for Systematic Review and Meta-Analyses (PRISMA) guidelines. Embase, PubMed and Web of Science databases were searched in October 2020 using specific search strategies. Where odds ratios were reported, meta-analyses were conducted using the random effects model. Otherwise, significant factors were reported in this review. We identified seven notable risk factors for various skin aging phenotypes: age, gender, ethnicity, air pollution, nutrition, smoking, sun exposure. This review's results will guide future works, such as those aiming to examine the interaction between genetic and environmental influences.

Protective Effect of Fat-Tissue-Derived Products against Ultraviolet Irradiation-Induced Photoaging in Mouse Skin.

BACKGROUND: Exposure to ultraviolet radiation causes erythema, inflammation, and photoaging. Mechanical micronization of adipose tissue can concentrate functional cells and has great potential as an alternative for regenerative medicine. Stromal vascular fraction gel is produced by means of a series of mechanical processes of lipoaspirates and can be injected intradermally. This study aimed to assess the therapeutic effect of stromal vascular fraction gel on photoaging skin. METHODS: A photoaging model was established in nude mice. Photoaging mice received treatments of stromal vascular fraction gel, fat, tretinoin, or phosphate-buffered saline. Photoaging skin was characterized by histologic and immunohistochemical analyses. Expression of collagen synthesis-related or photoaging-related genes was assessed. RESULTS: Stromal vascular fraction gel, fat, and tretinoin reversed photoaging, whereas stromal vascular fraction gel demonstrated the greatest therapeutic effect. Treatment with stromal vascular fraction gel restored intradermal fat tissue content and increased dermal collagen density. Injection of stromal vascular fraction gel had the strongest effect on stimulating fibroblasts and increasing the expression of transforming growth factor ß1 (TGF-ß1), propeptide of type-I procollagen, and Smad 2, decreasing the expression of Smad 3, compared with fat and tretinoin. Expression of photoaging-related genes was significantly reduced, whereas expression of fibulin-5 was significantly increased after stromal vascular fraction gel treatment. CONCLUSIONS: Stromal vascular fraction gel demonstrated remarkable therapeutic effects in reversing photoaging skin. Stromal vascular fraction gel can be injected intradermally and survive within dermal layer after grafting. This product increased TGF-ß1expression and activated fibroblasts to produce propeptide of type I procollagen, thus increasing the amount of collagen I, leading to thickening of the dermis of photoaging skin.

Challenges in Sun Protection.

Since time immemorial, people protected themselves from solar radiation. Limiting time in the sun by seeking shade or wearing clothing was a matter of course. In the early 20th century, tanned skin - a result of exposure to sunlight - was associated with good health. At the same time, however, one also had to protect oneself against the potential of excessive exposure to avoid sunburns. Around 1945, the first sunscreen products for protection against solar radiation became available. In the years to follow and up to the recent past, a vast number of different sunscreen filters were developed and incorporated into a wide variety of product formats. Frameworks regulating filter substances and preparations and methods to characterize sunscreen products' performance parameters were developed. Over the past 50-70 years, the perception regarding the tasks of sunscreen products changed several times. It was initially promoted as a lifestyle product and had the task of preventing sun-related erythema (tan without burn). Later, the prevention of skin cancer was added. Only in recent times, sunscreen products have been increasingly advertised and perceived as beauty and lifestyle products again. Also, the use of sunscreen products for antiaging purposes is now commonplace. The different intended purposes (averting harm and prevention) and the widespread use of topical sunscreen products have promoted many investigations and generated a vast and ongoing need for consumer and patient information and education. In the following review, we analyze and discuss current topics from conflicting areas, such as sun protection products (e.g., ideal sun protection products, sun protection metrics), product safety (e.g., nanoparticulate sunscreen filters, regulatory issues), application in everyday life (e.g., wish to tan, vulnerable cohorts), as well as controversies and future challenges (e.g., risks and benefits of UV radiation).

Spectral Homeostasis - The Fundamental Requirement for an Ideal Sunscreen.

Sunscreen application to UV-exposed skin is promoted to prevent skin cancer and sun damage, within a comprehensive photoprotection strategy that also includes sun avoidance and wearing UV protective clothing. The benefits of sunscreen are verified in preventing sunburn but appear to be largely presumptive in skin cancer prevention. Contemporary science establishes UVA as a primary driver of melanoma and photoaging. Consequentially, the traditional UVB-skewed protection of sunscreens provides an intellectual and logical explanation for rising skin cancer rates and, in particular, their failure to protect against melanoma. Better protection could be achieved with more balanced UVB/UVA sunscreens, toward spectral homeostasis protection. Greater balanced protection has another advantage of attenuating fewer UVB rays, which aid synthesis of vitamin D and nitric oxide. Percutaneous absorption of Soluble Organic UV Filters leads to systemic exposure, which becomes the relevant safety consideration. It is minimized by selecting Insoluble UV Filters with low absorption potential from a molecular weight above 500 Da. The filters must also be very hydrophilic, very lipophilic, or consist of particles. The risk-benefit ratio is a medical imperative, more so for cosmetics or sunscreens, since in principle there should be no risk from their use. The production of ideal sunscreens that mimic the effective, balanced UVB/UVA attenuation of textiles and shade is now possible, while maintaining an acceptable therapeutic margin of safety in humans and a favorable ecologic profile. Sunscreens with a favorable risk-benefit ratio and good esthetic properties or other consumer-friendly attributes will improve compliance and may achieve substantial clinical benefits.