The Skin Epilipidome in Stress, Aging, and Inflammation

Causal and mediating effects of lipid and facial aging: association study integrating GWAS, eQTL, mQTL, and pQTL data

BACKGROUND

Increasing evidence suggests a potential causal association between lipid levels and facial aging. The aim of this study was to investigate the relationship between levels of specific lipids and facial aging via Mendelian randomization methods. Additionally, this study aimed to identify mediators and explore relevant genes and drug targets.

METHODS

In this study, genome-wide association data on plasma lipids from 7,174 Finnish individuals in the UK Biobank were used. Two-sample Mendelian randomization was applied to assess the causal effects of specific lipids on facial aging. Sensitivity and pleiotropy analyses were conducted to ensure the robustness and reliability of the results. Multivariate Mendelian randomization was conducted to account for the potential impact of confounding factors. Furthermore, summary-data-based Mendelian randomization was used to identify relevant genes, which were validated through multiomics data. Finally, drug‒gene interactions were explored via molecular docking techniques.

RESULTS

Two-sample Mendelian randomization analysis revealed a causal relationship between lipid levels and facial aging. According to the multivariate Mendelian randomization results, smoking was found to mediate this association, and these lipids remained significantly associated with facial aging, even after accounting for environmental confounders. Using summary-data-based Mendelian randomization, CYP21A2, CCND1, PSMA4, and MED1 were identified as potential gene targets, with MED1 further validated through pQTL and mQTL data. Additionally, the MED1 protein was found to bind spontaneously with astragalin, fenofibrate, and ginsenoside.

CONCLUSIONS

The results revealed a causal relationship between lipid levels and facial aging, revealing key gene targets that were still significantly associated with facial aging after controlling for environmental confounders. Additionally, the interactions between MED1 and certain drugs may indicate potential pathways for therapeutic interventions related to facial aging.

Causal relationship between dyslipidemia and risk of facial aging: Insights from Mendelian randomization in East Asian populations

BACKGROUND

Emerging observational studies showed an association between dyslipidemia and aging. However, it remains unclear whether this association is causal, particularly in the case of Asians, which are aging more rapidly than other continents. Given the visible manifestations of aging often include changes in facial appearance, the objective of this study is to assess the causal relationship between dyslipidemia and facial aging in East Asian populations.

METHODS

SNPs related to dyslipidemia in East Asian people such as Total cholesterol (TC), High-density-lipoprotein cholesterol (HDL), Low-density-lipoprotein cholesterol (LDL), and Triglyceride (TG) along with outcomes data on facial aging, were extracted from public genome-wide association studies (GWAS). A two-sample Mendelian randomization (MR) analysis was then performed using publicly available GWAS data to investigate the potential causal relationship. The effect estimates were primarily calculated using the fixed-effects inverse variance weighted (IVW) method.

RESULTS

Totally, 88 SNPs related to HDL among 70657 East Asian participants in GWAS. Based on the primary causal effects model using MR analyses with the IVW method, high HDL level was demonstrated as significantly related to the risk of facial aging (OR, 1.060; 95% CI, 1.005-1.119, p = 0.034), while high TC level (OR, 0.995; 95% CI, 0.920-1.076, p = 0.903), high LDL level (OR, 0.980, 95% CI, 0.924-1.041, p = 0.515), as well as high TG level (OR, 0.999, 95% CI, 0.932-1.071, p = 0.974), showed no significant correlation with facial aging.

CONCLUSIONS

The two-sample MR analysis conducted in this study revealed a positive causal relationship between high HDL levels and facial aging. In contrast, facial aging demonstrated no significant correlation with high levels of TC, LDL, or TG. Further large-sample prospective studies are needed to validate these findings and to provide appropriate recommendations regarding nutrition management to delay the aging process among old patients in East Asia.

Exploring Skin Wound Healing Models and the Impact of Natural Lipids on the Healing Process

Cutaneous wound healing is a complex biological process involving a series of well-coordinated events aimed at restoring skin integrity and function. Various experimental models have been developed to study the mechanisms underlying skin wound repair and to evaluate potential therapeutic interventions. This review explores the diverse array of skin wound healing models utilized in research, ranging from rodent excisional wounds to advanced tissue engineering constructs and microfluidic platforms. More importantly, the influence of lipids on the wound healing process is examined, emphasizing their role in enhancing barrier function restoration, modulating inflammation, promoting cell proliferation, and promoting remodeling. Lipids, such as phospholipids, sphingolipids, and ceramides, play crucial roles in membrane structure, cell signaling, and tissue repair. Understanding the interplay between lipids and the wound microenvironment provides valuable insights into the development of novel therapeutic strategies for promoting efficient wound healing and tissue regeneration. This review highlights the significance of investigating skin wound healing models and elucidating the intricate involvement of lipids in the healing process, offering potential avenues for improving clinical outcomes in wound management.

Research Progress in Skin Aging, Metabolism, and Related Products

In recent years, skin aging has received increasing attention. Many factors affect skin aging, and research has shown that metabolism plays a vital role in skin aging, but there needs to be a more systematic review. This article reviews the interaction between skin metabolism and aging from the perspectives of glucose, protein, and lipid metabolism and explores relevant strategies for skin metabolism regulation. We found that skin aging affects the metabolism of three major substances, which are glucose, protein, and lipids, and the metabolism of the three major substances in the skin also affects the process of skin aging. Some drugs or compounds can regulate the metabolic disorders mentioned above to exert anti-aging effects. Currently, there are a variety of products, but most of them focus on improving skin collagen levels. Skin aging is closely related to metabolism, and they interact with each other. Regulating specific metabolic disorders in the skin is an important anti-aging strategy. Research and development have focused on improving collagen levels, while the regulation of other skin glycosylation and lipid disorders including key membrane or cytoskeleton proteins is relatively rare. Further research and development are expected.

Skin Cancer Microenvironment: What We Can Learn from Skin Aging?

Aging is a natural intrinsic process associated with the loss of fibrous tissue, a slower cell turnover, and a reduction in immune system competence. In the skin, the continuous exposition of environmental factors superimposes extrinsic damage, mainly due to ultraviolet radiation causing photoaging. Although not usually considered a pathogenic event, photoaging affects cutaneous biology, increasing the risk of skin carcinogenesis. At the cellular level, aging is typified by the rise of senescence cells a condition characterized by reduced or absent capacity to proliferate and aberrant hyper-secretory activity. Senescence has a double-edged sword in cancer biology given that senescence prevents the uncontrolled proliferation of damaged cells and favors their clearance by paracrine secretion. Nevertheless, the cumulative insults and the poor clearance of injured cells in the elderly increase cancer incidence. However, there are not conclusive data proving that aged skin represents a permissive milieu for tumor onset. On the other hand, tumor cells are capable of activating resident fibroblasts onto a pro-tumorigenic phenotype resembling those of senescent fibroblasts suggesting that aged fibroblasts might facilitate cancer progression. This review discusses changes that occur during aging that can prime neoplasm or increase the aggressiveness of melanoma and non-melanoma skin cancer.

Electroacupuncture promotes skin wound repair by improving lipid metabolism and inhibiting ferroptosis

Lipid metabolism plays an important role in the repair of skin wounds. Studies have shown that acupuncture is very effective in skin wound repair. However, there is little knowledge about the mechanism of electroacupuncture. Thirty-six SD rats were divided into three groups: sham-operated group, model group and electroacupuncture group, with 12 rats in each group. After the intervention, local skin tissues were collected for lipid metabolomics analysis, wound perfusion and ferroptosis-related indexes were detected and finally the effect of electroacupuncture on skin wound repair was comprehensively evaluated by combining wound healing rate and histology. Lipid metabolomics analysis revealed 37 differential metabolites shared by the three groups, mainly phospholipids, lysophospholipids, glycerides, acylcarnitine, sphingolipids and fatty acids, and they could be back-regulated after electroacupuncture. The recovery of blood perfusion and wound healing was faster in the electroacupuncture group than in the model group (p < 0.05). The levels of GPX4, FTH1, SOD and GSH-PX, which are related to ferroptosis, were higher in the electroacupuncture group than in the model group (p < 0.05). The levels of ACSL4 and MDA were lower in the electroacupuncture group than in the model group (p < 0.05). Electroacupuncture may promote skin wound repair by improving lipid metabolism and inhibiting ferroptosis in local tissues.

Nanofabrication of cobalt-tellurium using Allium sativum extract and its protective efficacy against H2O2-induced oxidative damage in HaCaT cells

Allium sativum (A. sativum)is well known for its therapeutic and culinary uses. Because of their high medicinal properties, the clove extract was selected to synthesize cobalt-tellurium nanoparticles. The aim of the study was to evaluate the protective activity of the nanofabricated cobalt-tellurium using A. sativum (Co-Tel-As-NPs) against H₂O₂-induced oxidative damage in HaCaT cells. Synthesized Co-Tel-As-NPs were analyzed using UV-Visible spectroscopy, FT-IR, EDAX, XRD, DLS, and SEM. Various concentrations of Co-Tel-As-NPs were used as a pretreatment on HaCaT cells before H₂O₂ was added. Then, the cell viability and mitochondrial damage were compared between pretreated and untreated control cells using an array of assays (MTT, LDH, DAPI, MMP, and TEM), and the intracellular ROS, NO, and antioxidant enzyme production were examined. In the present research, Co-Tel-As-NPs at different concentrations (0.5, 1.0, 2.0, and 4.0μg/mL) were tested for toxicity using HaCaT cells. Furthermore, the effect of H₂O₂ on the viability of HaCaT cells was evaluated using the MTT assay for Co-Tel-As-NPs. Among those, Co-Tel-As-NPs at 4.0 μg/mL showed notable protection; with the same treatment, cell viability was discovered to be 91% and LDH leakage was also significantly decreased. Additionally, the measurement of mitochondrial membrane potential was significantly decreased by Co-Tel-As-NPs pretreatment against H₂O₂. The recovery of the condensed and fragmented nuclei brought about by the action of Co-Tel-As-NPs was identified using DAPI staining. TEM examination of the HaCaT cells revealed that the Co-Tel-As-NPs had a therapeutic effect against H₂O₂ keratinocyte damage.

Malassezia restricta-mediated Lipoperoxidation: A Novel Trigger in Dandruff

Dandruff is a common scalp disorder with multiple microbial and host-related factors contributing to its aetiology, including alterations in scalp sebum. Despite existing evidence that the yeast Malassezia restricta plays a key role in the onset of dandruff, the interplay of these factors is poorly understood. Recently, squalene monohydroperoxide and malondialdehyde were established as biomarkers of dandruff-afflicted scalp, highlighting the role of sebum lipoperoxidation in the triggering and maintenance of dandruff, although its mechanism of action is unknown. The current study provides evidence that M. restricta mediates sebum peroxidation, leading to production of squalene monohydroperoxide and malondialdehyde. Furthermore, in vitro data show that these lipoperoxidation products act on epidermal cells and alter the skin barrier. These results support the role of Malassezia restricta-induced lipoperoxides as triggers of dandruff, which suggests that blocking their production could be a novel anti-dandruff treatment approach.

On the Potential Role of the Antioxidant Couple Vitamin E/Selenium Taken by the Oral Route in Skin and Hair Health

The relationship between oxidative stress and skin aging/disorders is well established. Many topical and oral antioxidants (vitamins C and E, carotenoids, polyphenols) have been proposed to protect the skin against the deleterious effect induced by increased reactive oxygen species production, particularly in the context of sun exposure. In this review, we focused on the combination of vitamin E and selenium taken in supplements since both molecules act in synergy either by non-enzymatic and enzymatic pathways to eliminate skin lipids peroxides, which are strongly implicated in skin and hair disorders.

A dose-dependent protective effect of n-3 PUFAs in photoaging by promoting collagen production through MAPK pathway in SKH-1 mouse model

BACKGROUND

Dietary supplementation of n-3 polyunsaturated fatty acids (n-3 PUFAs) can inhibit inflammation and oxidation of photoaging, but the effect and mechanism on regulation of dermis collagen remains poorly elucidated. The destruction of dermal collagen plays a crucial role in the process of long-term ultraviolet radiation (UVR) induced-photoaging, especially leading to deterioration of skin appearance and function.

METHODS

In this study, we explored the protective effect of n-3 PUFAs on the regulation of collagen through the MAPK pathway using the SKH-1 photoaging mouse model.

RESULTS

The results showed that n-3 PUFAs promoted collagen synthesis and reduced collagen degradation in a dose-dependent manner, which was mediated by the down-regulation of the MAPK pathway. In addition, n-3 PUFAs supplementation inhibited the production of MMP-1 and the UV-induced abnormal proliferation of keratinocytes. All these effects resulted in the remodeling of extracellular matrix (ECM) and finally made a significant improvement in the appearance of skin.

CONCLUSION

Overall, the present study suggested that dietary supplementation of n-3 PUFAs has the potential clinical prospect to prevent UV-induced skin damage and photoaging.

Sebocytes contribute to melasma onset

Melasma is a hyperpigmentary disorder with photoaging features, whose manifestations appear on specific face areas, rich in sebaceous glands (SGs). To explore the SGs possible contribution to the onset, the expression of pro-melanogenic and inflammatory factors from the SZ95 SG cell line exposed to single or repetitive ultraviolet (UVA) radiation was evaluated. UVA up-modulated the long-lasting production of α-MSH, EDN1, b-FGF, SCF, inflammatory cytokines and mediators. Irradiated SZ95 sebocyte conditioned media increased pigmentation in melanocytes and the expression of senescence markers, pro-inflammatory cytokines, and growth factors regulating melanogenesis in fibroblasts cultures. Cocultures experiments with skin explants confirmed the role of sebocytes on melanogenesis promotion. The analysis on sebum collected from melasma patients demonstrated that in vivo sebocytes from lesional areas express the UVA-activated pathways markers observed in vitro. Our results indicate sebocytes as one of the actors in melasma pathogenesis, inducing prolonged skin cell stimulation, contributing to localized dermal aging and hyperpigmentation.

Inhibitory Effect of Lotusine on Solar UV-Induced Matrix Metalloproteinase-1 Expression

Solar ultraviolet (sUV) radiation remains a major cause of skin aging. Nelumbo nucifera (lotus) is a well-known edible plant widely grown in Asia, including Korea, China, and Japan. The lotus consists of flowers, leaves, stems, and seeds, and all parts reportedly possess nutritional and medical values. Traditionally, lotus flowers, leaves, stems, and seeds have been used as antidiarrheal agents, diuretics, antipyretics, and antimicrobial and antihyperlipidemic agents. In addition, the Nelumbo nucifera lotus embryo has been shown to possess sedative and antipyretic properties and can relieve hemostatic thirst and treat eye diseases. Recently, Nelumbo nucifera lotus flower extract has been widely used in cosmetics due to its ability to reduce wrinkles and its whitening effects. Numerous cosmetics using Nelumbo nucifera lotus embryo extracts are commercially available. However, the active components of Nelumbo nucifera remain elusive. Lotusine is a phytochemical and soluble alkaloid found in lotus embryos. Herein, we examined the anti-wrinkle effect of lotusine using sUV-exposed human keratinocytes. We observed that lotusine reduced sUV-induced matrix metalloproteinase (MMP)-1 expression and modulated transcriptional activities of activator protein (AP)-1 and nuclear factor kappa B (NF-κB). sUV-induced AP-1 and NF-κB activity could be activated via multiple signal transduction cascades, including the p38 MAPK, JNK, ERK1/2, and Akt pathways in the skin. Lotusine inhibited the MEK1/2-ERK1/2-p90^RSK, MKK3/6-p38, and Akt-p70^S6K pathways. Overall, our findings suggest that lotusine has potential benefits related to MMP-1 expression and skin aging following sUV exposure. Hence, the lotus can be developed as a valuable functional food and cosmetic material.

Research Techniques Made Simple: Lipidomic Analysis in Skin Research

Although lipids are crucial molecules for cell structure, metabolism, and signaling in most organs, they have additional specific functions in the skin. Lipids are required for the maintenance and regulation of the epidermal barrier, physical properties of the skin, and defense against microbes. Analysis of the lipidome-the totality of lipids-is of similar complexity to those of proteomics or other omics, with lipid structures ranging from simple, linear, to highly complex structures. In addition, the ordering and chemical modifications of lipids have consequences on their biological function, especially in the skin. Recent advances in analytic capability (usually with mass spectrometry), bioinformatic processing, and integration with other dermatological big data have allowed researchers to increasingly understand the roles of specific lipid species in skin biology. In this paper, we review the techniques used to analyze skin lipidomics and epilipidomics.

The role of lipid-based signalling in wound healing and senescence

Lipid-based signalling modulates several cellular processes and intercellular communication during wound healing and tissue regeneration. Bioactive lipids include but are not limited to the diverse group of eicosanoids, phospholipids, and extracellular vesicles and mediate the attraction of immune cells, initiation of inflammatory responses, and their resolution. In aged individuals, wound healing and tissue regeneration are greatly impaired, resulting in a delayed healing process and non-healing wounds. Senescent cells accumulate with age in vivo, preferably at sites implicated in age-associated pathologies and their elimination was shown to alleviate many age-associated diseases and disorders. In contrast to these findings, the transient presence of senescent cells in the process of wound healing exerts beneficial effects and limits fibrosis. Hence, clearance of senescent cells during wound healing was repeatedly shown to delay wound closure in vivo. Recent findings established a dysregulated synthesis of eicosanoids, phospholipids and extracellular vesicles as part of the senescent phenotype. This intriguing connection between cellular senescence, lipid-based signalling, and the process of wound healing and tissue regeneration prompts us to compile the current knowledge in this review and propose future directions for investigation.

Inhibition of Solar UV-Induced Matrix Metalloproteinase (MMP)-1 Expression by Non-Enzymatic Softening Cherry Blossom (Prunus yedoensis) Extract

Cherry blossom (Prunus yedoensis) petals are used as ingredients in many cosmetics. However, despite their use in numerous products, the exact function of cherry blossom petals in cosmetics is unclear. Therefore, we need evidence-based studies to support the labeling claims that are made in cherry blossom products in the cosmetics industry. We investigated the skin anti-aging potential of non-enzymatic softening cherry blossom extract (NES-CBE) in this study. The extract desalinated, to improve its quality such that it can be used as a functional material for the skin. The anti-wrinkle effect of NES-CBE was investigated on human keratinocytes (HaCaT cells) under solar UV (sUV) light exposure. We found that NES-CBE reduced the sUV-induced matrix metalloproteinase (MMP)-1 expression and modulated the transactivation of the activator protein (AP)-1. Furthermore, NES-CBE suppressed the phosphorylation of MEK1/2 and ERK proteins, indicating its regulation of sUV-induced MAPK signaling. Additionally, we observed NES-CBE reduced MMP-1 protein expression in a human skin equivalent model. Taken together, these results suggest that NES-CBE reduces sUV-induced MMP-1 protein expression through reducing AP-1 transactivation via regulation of the MEK1/2-ERK pathway.