5,7-Dimethoxyflavone, an activator of PPARα/γ, inhibits UVB-induced MMP expression in human skin fibroblast cells

Skin Rejuvenation Efficacy and Safety Evaluation of Kaempferia parviflora Standardized Extract (BG100) in Human 3D Skin Models and Clinical Trial

Polymethoxyflavones from Kaempferia parviflora rhizomes have been shown to effectively combat aging in skin cells and tissues by inhibiting senescence, reducing oxidative stress, and enhancing skin structure and function. This study assessed the anti-aging effects and safety of standardized K. parviflora extract (BG100), enriched with polymethoxyflavones including 5,7-dimethoxyflavone, 5,7,4'-trimethoxyflavone, 3,5,7,3',4'-pentamethoxyflavone, 3,5,7-trimethoxyflavone, and 3,5,7,4'-tetramethoxyflavone. We evaluated BG100's impact on skin rejuvenation and antioxidant properties using photoaged human 3D full-thickness skin models. The potential for skin irritation and sensitization was also assessed through studies on reconstructed human epidermis and clinical trials. Additionally, in vitro genotoxicity testing was performed following OECD guidelines. Results indicate that BG100 promotes collagen and hyaluronic acid production, reduces oxidative stress, and minimizes DNA damage in photoaged full-thickness 3D skin models. Furthermore, it exhibited non-irritating and non-sensitizing properties, as supported by tests on reconstructed human epidermis and clinical settings. BG100 also passed in vitro genotoxicity tests, adhering to OECD guidelines. These results underscore BG100's potential as a highly effective and safe, natural anti-aging agent, suitable for inclusion in cosmeceutical and nutraceutical products aimed at promoting skin rejuvenation.

New Insights into the Role of PPARγ in Skin Physiopathology

Peroxisome proliferator-activated receptor gamma (PPARγ) is a transcription factor expressed in many tissues, including skin, where it is essential for maintaining skin barrier permeability, regulating cell proliferation/differentiation, and modulating antioxidant and inflammatory responses upon ligand binding. Therefore, PPARγ activation has important implications for skin homeostasis. Over the past 20 years, with increasing interest in the role of PPARs in skin physiopathology, considerable effort has been devoted to the development of PPARγ ligands as a therapeutic option for skin inflammatory disorders. In addition, PPARγ also regulates sebocyte differentiation and lipid production, making it a potential target for inflammatory sebaceous disorders such as acne. A large number of studies suggest that PPARγ also acts as a skin tumor suppressor in both melanoma and non-melanoma skin cancers, but its role in tumorigenesis remains controversial. In this review, we have summarized the current state of research into the role of PPARγ in skin health and disease and how this may provide a starting point for the development of more potent and selective PPARγ ligands with a low toxicity profile, thereby reducing unwanted side effects.

The effect of tomato and lycopene on clinical characteristics and molecular markers of UV-induced skin deterioration: A systematic review and meta-analysis of intervention trials

Lycopene as a natural antioxidant that have been studied for ultraviolet radiation (UVR) photo protection and is one of the most effective carotenoids to scavenge reactive oxygen species (ROS). This review aims to summarize the protective effect of tomato and lycopene on skin photo damage and skin photoaging in healthy subjects by reviewing the existing population intervention experiments. A total of five electronic databases including PubMed, Scopus, EBSCO, Web of Science and Cochrane Library were searched from inceptions to January 2021 without any restriction. Out of 19336 publications identified, 21 fulfilled the inclusion criteria and were meta-analysis. Overall, interventions supplementing tomato and lycopene were associated with significant reductions in Δa*, MMP-1, ICAM-1 and skin pigmentation; while tomato and lycopene supplementation were associated with significant increase in MED, skin thickness and skin density. Based on the results of this systematic review and meta-analysis, supplementation with tomato and lycopene could reduce skin erythema formation and improve the appearance and pigmentation of the skin, thereby preventing light-induced skin photodamage and skin photoaging. Lycopene-rich products could be used as endogenous sun protection and may be a potential nutraceutical for sun protection.

Discovery of matrix metalloproteinase inhibitors as anti-skin photoaging agents

Photodamage is the result of prolonged exposure of the skin to sunlight. This exposure causes an overexpression of matrix metalloproteinases (MMPs), leading to the abnormal degradation of collagen in the skin tissue and resulting in skin aging and damage. This review presents a detailed overview of MMPs as a potential target for addressing skin aging. Specifically, we elucidated the precise mechanisms by which MMP inhibitors exert their anti-photoaging effects. Furthermore, we comprehensively analyzed the current research progress on MMP inhibitors that demonstrate significant inhibitory activity against MMPs and anti-skin photoaging effects. The review also provides insights into the structure-activity relationships of these inhibitors. Our objective in conducting this review is to provide valuable practical information to researchers engaged in investigations on anti-skin photoaging.

The potential of traditional herbal active ingredients in the treatment of sarcopenia animal models: focus on therapeutic effects and mechanisms

Sarcopenia is a major global public health problem that harms individual physical function. In 2018, the European Working Group on Sarcopenia in the Elderly 2 classified sarcopenia into primary and secondary sarcopenia. However, information on the pathogenesis and effective treatment of primary and secondary sarcopenia is limited. Traditional herbal active ingredients have biological activities that promote skeletal muscle health, showing potential preventive and therapeutic effects on sarcopenia. Therefore, this narrative review aims to provide a comprehensive overview of global traditional herbal active ingredients' beneficial therapeutic effects and molecular mechanisms on sarcopenia-related animal models. For this purpose, we conducted a literature search in three databases, PubMed, Web of Science, and Embase, consistent with the review objectives. After the screening, 12 animal studies met the review themes. The review results showed that the pathological mechanisms in sarcopenia-related animal models include imbalanced protein metabolism, oxidative stress, inflammation, apoptosis, insulin resistance, endoplasmic reticulum stress, impaired mitochondrial biogenesis, and autophagy-lysosome system aggravation. Eleven traditional herbal active ingredients exerted positive anti-sarcopenic effects by ameliorating these pathological mechanisms. This narrative review will provide meaningful insight into future studies regarding traditional herbal active ingredients for treating sarcopenia.

Mechanisms of ultraviolet-induced melasma formation: A review

Melasma, a pigmentation disorder, commonly occurs in exposed skin areas and can be attributed to several factors. Ultraviolet radiation (UVR) is the primary factor that induces and aggravates melasma. Considering gene expression, exposed skin areas experience abnormal gene expression, involving melanin metabolism, oxidative stress, impaired skin barrier function, and abnormal composition of nerve factors. From a histological perspective, UVR can cause basement membrane collapse, melanocyte sinking, and disorders of skin lipid metabolism. Emerging therapies have focused on these pathological alterations in melasma, including platelet-rich plasma, mesotherapy, and phytochemicals. Understanding the role of UVR in the development of melasma can facilitate early prevention and highlight the future direction of melasma treatment.

Exploring the fuzzy border between senolytics and senomorphics with chemoinformatics and systems pharmacology

Senescent cells accumulate within tissues during aging and secrete an array of pro-inflammatory molecules known as senescent-associated secretory phenotype (SASP), which contribute to the appearance and progression of various chronic degenerative diseases. Novel pharmacological approaches aimed at modulating or eliminating senescent cells´ harmful effects have recently emerged: Senolytics are molecules that selectively eliminate senescent cells, while senomorphics modulate or decrease the inflammatory response to specific SASP. So far, the physicochemical, structural, and pharmacological properties that define these two kinds of pharmacological approaches remain unclear. Therefore, the identification and correct choice of molecules, based on their physicochemical, structural, and pharmacological properties, likely to exhibit the desired senotherapeutic activity is crucial for developing effective, selective, and safe senotherapies. Here we compared the physicochemical, structural, and pharmacological properties of 84 senolytics and 79 senomorphics using a chemoinformatic and systems pharmacology approach. We found great physicochemical, structural, and pharmacological similarities between them, also reflected in their cellular responses measured through transcriptome perturbations. The identified similarities between senolytics and senomorphics might explain the dual activity of some of those molecules. These findings will help design and discover new, more effective, and highly selective senotherapeutic agents.

Lotus root extract inhibits skin damage through suppression of collagenase production in vitro

Lotus root is a traditional food ingredient used primarily in Asia and is rich in polyphenols. To determine its potential use in antiphotoaging, polyphenols were extracted from lotus root with 50% ethanol, and the activity of matrix metalloproteinase (MMP) was measured in dermal cells treated with ultraviolet A (UVA). UVA exposure increased the gene expression of IL-1α, the mRNA levels of MMP-1, and hence, the levels of MMP-1 protein in HaCaT cells, whereas cells treated with lotus polyphenol (LP) normalized these values to the control. In the presence of LP at concentrations of 1 and 10 μg/mL, both the secretion of IL-1α and protein levels of MMP-1 in human keratinocyte cells significantly reduced. Similarly, in the LabCyte EPI-MODEL24, irradiation with UVA caused an increase in mRNA expression of IL-1α and MMP-1, which was prevented by adding LP to the cells. Our results with three different skin cells accordingly showed that LP may help maintain skin health through decreased levels of MMP-1 activity via its anti-inflammatory properties.

Polymethoxyflavones from Kaempferia parviflora ameliorate skin aging in primary human dermal fibroblasts and ex vivo human skin

Skin aging is accompanied by an increase in the number of senescent cells, resulting in various pathological outcomes. These include inflammation, impaired barrier function, and susceptibility to skin disorders such as cancer. Kaempferia parviflora (Thai black ginger), a medicinal plant native to Thailand, has been shown to counteract inflammation, cancer, and senescence. This study demonstrates that polymethoxyflavones (5,7-dimethoxyflavone, 5,7,4'-trimethoxyflavone, and 3,5,7,3',4'-pentamethoxyflavone) purified from K. parviflora rhizomes suppressed cellular senescence, reactive oxygen species, and the senescence-associated secretory phenotype in primary human dermal fibroblasts. In addition, they increased tropocollagen synthesis and alleviated free radical-induced cellular and mitochondrial damage. Moreover, the compounds mitigated chronological aging in a human ex vivo skin model by attenuating senescence and restoring expression of essential components of the extracellular matrix, including collagen type I, fibrillin-1, and hyaluronic acid. Finally, we report that polymethoxyflavones enhanced epidermal thickness and epidermal-dermal stability, while blocking age-related inflammation in skin explants. Our findings support the use of polymethoxyflavones from K. parviflora as natural anti-aging agents, highlighting their potential as active ingredients in cosmeceutical and nutraceutical products.

Evaluating the effect of Luffa cylindrica stem sap on dermal fibroblasts; An invitro study

Luffa cylindrica stem sap (LuCS) has been traditionally used as a facial cosmetic supplement to enhance the skin condition of Asians. However, LuCS has yet to be described and there is no solid scientific evidence regarding the use of LuCS as an anti-wrinkle agent. In the present study, we have evaluated the functional effect of LuCS and its underlying mechanisms based on scientific evidence. Treatment with LuCS stimulated the growth and migration of human skin fibroblasts. LuCS treatment activated EGFR signaling via the enhanced expression of EGFR and down-regulation of PPARγ in human skin fibroblasts. Exposure to LuCS induced the synthesis of cellular type I procollagen and elastin in consort with the down-regulation of various proteinases including MMP-1, -2 and -9 in human skin fibroblasts. LuCS treatment also reversed the skin damage induced by UV-A irradiation in human skin fibroblasts. 3-bromo-3-methylisoxazol-5-amine was identified as the functional component using UPLC-MS-MS analysis and increased production of cellular type I procollagen. Collectively, these results suggest the efficacy of LuCS supplementation in improving the skin condition via anti-wrinkle effect.

Protective Effect of Polymethoxyflavones Isolated from Kaempferia parviflora against TNF-α-Induced Human Dermal Fibroblast Damage

Similar to other organs, the skin undergoes a natural aging process. Moreover, constant direct exposure to environmental stresses, including ultraviolet irradiation, causes the signs of skin aging to appear rather early. Reactive oxygen species (ROS) and inflammatory responses accelerate skin damage in extrinsic aging. In this study, we aimed to investigate the skin protective effects of polymethoxyflavones found in Kaempferia parviflora against oxidative stress and inflammation-induced damage in human dermal fibroblasts (HDFs) stimulated by tumor necrosis factor-α (TNF-α). The experimental data identified 5,7,4' trimethoxyflavone (TMF) as the most potent constituent in preventing TNF-α-induced HDF damage among the tested compounds and it was not only effective in inhibiting matrix metalloproteinase-1 (MMP-1) production but also in stimulating collagen, type I, and alpha 1 (COLIA1) expression. TMF suppressed TNF-α-stimulated generation of ROS and pro-inflammatory mediators, such as cyclooxygenase-2 (COX-2), interleukin (IL)-1β, and IL-6 in HDFs. TMF also inhibited the pathways regulating fibroblast damage, including mitogen-activated protein kinase (MAPK), activator protein 1 (AP-1), and nuclear factor-kappa B (NF-κB). In conclusion, TMF may be a potential agent for preventing skin aging and other dermatological disorders associated with oxidative stress and inflammation.

Combined Effects of Carotenoids and Polyphenols in Balancing the Response of Skin Cells to UV Irradiation

Oral carotenoids and polyphenols have been suggested to induce photo-protective effects. The aim of the study was to test whether the combination of carotenoids and polyphenols produce greater protective effects from UV-induced damage to skin cells. Such damage is characterized by inflammation and oxidative stress; thus, the photo-protective effect can be partially explained by modulating the nuclear factor kappa B (NFκB) and antioxidant response element/Nrf2 (ARE/Nrf2) transcription systems, known as important regulators of these two processes. Indeed, it was found in keratinocytes that carotenoids and polyphenols inhibit UVB-induced NFκB activity and release of cytokine IL-6. A combination of tomato extract with rosemary extract inhibited UVB-induced release of IL-6 more than each of the compounds alone. Moreover, this combination synergistically activated ARE/Nrf2 transcription systems. Inflammatory cytokines such as IL-6 and TNFα induce the expression of matrix metalloproteinases (MMPs), which leads to collagen breakdown; thus, it is important to note that carnosic acid reduced TNFα-induced MMP-1 secretion from human dermal fibroblasts. The in vitro results suggest beneficial effects of phytonutrient combinations on skin health. To assure that clinical experiments to prove such effects in humans are feasible, the human bioavailability of carotenoids from tomato extract was tested, and nearly a twofold increase in their plasma concentrations was detected. This study demonstrates that carotenoids and polyphenols cooperate in balancing UV-induced skin cell damage, and suggests that NFκB and ARE/Nrf2 are involved in these effects.

Skin photo-protection with phytochemicals against photo-oxidative stress, photo-carcinogenesis, signal transduction pathways and extracellular matrix remodeling-An overview

Excessive exposure of skin to UV radiation triggers the generation of oxidative stress, inflammation, immunosuppression, apoptosis, matrix-metalloproteases production, and DNA mutations leading to the onset of photo ageing and photo-carcinogenesis. At the molecular level, these changes occur via activation of several protein kinases as well as transcription pathways, formation of reactive oxygen species, and release of cytokines, interleukins and prostaglandins together. Current therapies available on the market only provide limited solutions and exhibit several side effects. The present paper provides insight into scientific studies that have elucidated the positive role of phytochemicals in counteracting the UV-induced depletion of antioxidant enzymes, increased lipid peroxidation, inflammation, DNA mutations, increased senescence, dysfunctional apoptosis and immune suppression. The contribution of phytochemicals to the downregulation of expression of oxidative-stress sensitive transcription factors (Nrf2, NF-Kb, AP-1 and p53) and protein kinases (MSK, ERK, JNK, p38 MAPK, p90RSK2 and CaMKs) involved in inflammation, apoptosis, immune suppression, extracellular matrix remodelling, senescence, photo ageing and photo-carcinogenesis, is also discussed. Conclusively, several phytochemicals hold potential for the development of a viable solution against UV irradiation-mediated photo ageing, photo-carcinogenesis and related manifestations.

Flavones reversibly inhibit Leishmania donovani tyrosine aminotransferase by binding to the catalytic pocket: An integrated in silico-in vitro approach

The current drugs for treating Leishmaniasis are toxic, non-economical and with the emergence of drug resistance makes the need for novel therapeutics urgent and necessary. In the current study, we report the identification of compounds TI 1-5 against tyrosine aminotransferase of L. donovani from a curated ZINC15 database containing 183,659 compounds. These flavonoid compounds had binding energies < -8 kcal/mol and interacted with the active site residues S151, K286, C290, and P291. Assessment of physicochemical descriptors and ADMET properties established the drug likeliness of these compounds. The all-atom molecular dynamic simulations of the TAT-TI complexes exhibited stable geometrical properties and further trajectory analysis revealed the high-affinity interactions of TI 1, 3, 4, and 5 with the active site residues. DFT calculations reported the high electrophilic nature of TI 2 while other TI compounds demonstrated good kinetic stability and reactivity. From in vitro studies, TI 3 and TI 4 had the highest inhibition with Ki values of 0.9 ± 0.2 μM and 0.30 ± 0.1 μM, respectively. Taken together, the results from this study indicate the potentiality of TI 1, 3, 4, and 5 as anti-leishmanial leads, and these compounds can be exploited to manage the growing Leishmaniasis crisis in the world.

Protective effect of diphlorethohydroxycarmalol isolated from Ishige okamurae against UVB-induced damage in vitro in human dermal fibroblasts and in vivo in zebrafish

Excessive exposure to ultraviolet (UV) irradiation from the sun is the primary environmental factor that causes aging of the skin. Most skin diseases caused by UV are attributed to UVB (280-320 nm). The purpose of this study is to investigate the protective effect of diphlorethohydroxycarmalol (DPHC), isolated from the marine brown alga, Ishige okamurae, against UVB-induced photodamage using both in vitro and in vivo models. Results indicate that DPHC remarkably inhibited commercial collagenase and elastase activities. It also reduced intracellular levels of ROS, improved cell viability and collagen content in UVB-irradiated human dermal fibroblasts (HDF cells). In addition, DPHC significantly inhibited activities of intracellular collagenase and elastase and reduced the expression of matrix metalloproteinases (MMPs) and pro-inflammatory cytokines. These events occurred through regulation of nuclear factor kappa B (NF-κB), activator protein 1 (AP-1), and mitogen-activated protein kinases (MAPKs) signaling pathways in UVB-irradiated HDF cells. Furthermore, DPHC also protected against in vivo photodamage by decreasing cell death through reducing lipid peroxidation and inflammatory response via decreasing ROS levels in UVB-irradiated zebrafish. In conclusion, DPHC has strong in vitro and in vivo photoprotective effects and has the potential to be used as an ingredient in pharmaceutical and cosmeceutical industries.

DNA damage in human skin and the capacities of natural compounds to modulate the bystander signalling

Human skin is a stratified organ frequently exposed to sun-generated ultraviolet radiation (UVR), which is considered one of the major factors responsible for DNA damage. Such damage can be direct, through interactions of DNA with UV photons, or indirect, mainly through enhanced production of reactive oxygen species that introduce oxidative changes to the DNA. Oxidative stress and DNA damage also associate with profound changes at the cellular and molecular level involving several cell cycle and signal transduction factors responsible for DNA repair or irreversible changes linked to ageing. Crucially, some of these factors constitute part of the signalling known for the induction of biological changes in non-irradiated, neighbouring cells and defined as the bystander effect. Network interactions with a number of natural compounds, based on their known activity towards these biomarkers in the skin, reveal the capacity to inhibit both the bystander signalling and cell cycle/DNA damage molecules while increasing expression of the anti-oxidant enzymes. Based on this information, we discuss the likely polypharmacology applications of the natural compounds and next-generation screening technologies in improving the anti-oxidant and DNA repair capacities of the skin.

The inhibitory effect of 5,7-DMF on pancreatic sphere-forming cell function mediated by FoxM1 gene expression

Pancreatic cancer is one of the major human malignant tumors severely endangering human health and life with high mortality due to the concealment of early symptoms and lack of effective therapies during advanced stages. The identification of pancreatic cancer stem cell functions has been as important strategy for understanding of pancreatic cancer biology and novel drug and therapy development. In the present study, we successfully isolated the pancreatic sphere-forming cells from pancreatic cancer cell line PANC-1 by sphere-forming method and we found that the sphere-forming ability and the cell migration rate of pancreatic sphere-forming cells were significantly inhibited by 5,7-DMF treatment, which was supported by the corresponding changes of several EMT biomarkers after being treated with 5,7-DMF. Moreover, we revealed here that the inhibition of pancreatic sphere-forming cells was mediated by the expression of FoxM1 gene, and also the expression of SOX2 gene was regulated by FoxM1 in pancreatic sphere-forming cells and involved in the inhibitory role of 5,7-DMF. These results provided important basis for the application of 5,7-DMF as a novel drug candidate for the pancreatic cancer treatment.

N-(4-bromophenethyl) Caffeamide Protects Skin from UVB-Induced Inflammation Through MAPK/IL-6/NF-κB-Dependent Signaling in Human Skin Fibroblasts and Hairless Mouse Skin

Long-term exposure to ultraviolet (UV) irradiation causes skin inflammation and aging. N-(4-bromophenethyl) caffeamide (K36H) possesses antioxidant and antimelanogenic properties. The present study investigated the effects of K36H on UVB-induced skin inflammation in human skin fibroblasts and hairless mice and evaluated the underlying mechanisms. The in vitro results indicated that K36H reduced UVB-induced mitogen-activated protein kinase (MAP kinase) expression. Furthermore, K36H treatment reduced cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) protein expression in UVB-irradiated fibroblasts by regulating IκB and nuclear factor-kappa B (NF-κB) expression. In the animal study, topically applied K36H markedly reduced inflammation and skin thickness and prevented photodamage to the skin of hairless mice. In addition, K36H inhibited the levels of UV-upregulated inflammation-related proteins levels such as IL-1, iNOS, and NF-κB in the dermis of hairless mice. Our findings demonstrated the antioxidant and anti-inflammatory properties of K36H in human skin fibroblasts and hairless mice. Therefore, K36H can be developed as an antiphotodamage and antiphotoinflammation agent.

The potential of natural products for targeting PPARα

Peroxisome proliferator activated receptors (PPARs) α, -γ and -β/δ are ligand-activated transcription factors and members of the superfamily of nuclear hormone receptor. These receptors play key roles in maintaining glucose and lipid homeostasis by modulating gene expression. PPARs constitute a recognized druggable target and indeed several classes of drugs used in the treatment of metabolic disease symptoms, such as dyslipidemia (fibrates, e.g. fenofibrate and gemfibrozil) and diabetes (thiazolidinediones, e.g. rosiglitazone and pioglitazone) are ligands for the various PPAR isoforms. More precisely, antidiabetic thiazolidinediones act on PPARγ, while PPARα is the main molecular target of antidyslipidemic fibrates. Over the past few years, our understanding of the mechanism underlying the PPAR modulation of gene expression has greatly increased. This review presents a survey on terrestrial and marine natural products modulating the PPARα system with the objective of highlighting how the incredible chemodiversity of natural products can provide innovative leads for this "hot" target.

Therapeutic Applications of Rose Hips from Different Rosa Species

Rosa species, rose hips, are widespread wild plants that have been traditionally used as medicinal compounds for the treatment of a wide variety of diseases. The therapeutic potential of these plants is based on its antioxidant effects caused by or associated with its phytochemical composition, which includes ascorbic acid, phenolic compounds and healthy fatty acids among others. Over the last few years, medicinal interest in rose hips has increased as a consequence of recent research that has studied its potential application as a treatment for several diseases including skin disorders, hepatotoxicity, renal disturbances, diarrhoea, inflammatory disorders, arthritis, diabetes, hyperlipidaemia, obesity and cancer. In this review, the role of different species of Rosa in the prevention of treatment of various disorders related to oxidative stress, is examined, focusing on new therapeutic approaches from a molecular point of view.

Ultraviolet B Inhibits IL-17A/TNF-α-Stimulated Activation of Human Dermal Fibroblasts by Decreasing the Expression of IL-17RA and IL-17RC on Fibroblasts

Background

Psoriasis is a chronic immune-mediated inflammatory disease, and a mixed Th1/Th17 cytokine environment plays a critical role in the pathogenesis of psoriasis. Dermal fibroblasts secrete certain cytokines such as IL-6, IL-8, and CXCL-1, contributing to the hyperproliferative state of the epidermis in psoriatic skin. Ultraviolet B (UVB) phototherapy is one of the most commonly used treatments in psoriasis but the influence of UVB on human dermal fibroblasts (HDFs) in psoriasis treatment is not completely understood.

Objectives

We conducted this study to mimic a psoriatic microenvironment in order to investigate and illustrate the combined effects of UVB, IL-17A, and TNF-α on HDFs.

Methods

The cultured HDFs were obtained from foreskin samples and divided into four groups, as follows: control; IL-17A/TNF-α; UVB; and IL-17A/TNF-α + UVB. Cultured HDFs were irradiated with 30 mJ/cm² UVB followed by addition of IL-17A/TNF-α and incubated for 24 h. We used real-time quantitative PCR, Western blot, ELISA analysis, and flow cytometry to examine gene and protein expression of related pro-inflammatory cytokines and chemokines and receptors.

Results

HDFs produced significant IL-6, IL-8, and CXCL-1 in response to IL-17A/TNF-α stimulation and UVB irradiation but UVB irradiation inhibited IL-17A/TNF-α-induced IL-6, IL-8, and CXCL-1 expression and downregulated the expression of IL-17RA and IL-17RC at both gene and protein levels. Additionally, UVB irradiation induced significant TGF-β1 protein secretion and expression of Smad3 mRNA and protein by HDFs. TGF-β1 significantly induced the expression of Smad3 mRNA and downregulated the IL-17RA and IL-17RC expression on HDFs.

Conclusion

UVB irradiation inhibits IL-17A/TNF-α-induced IL-6, IL-8, and CXCL-1 production in HDFs by decreasing the expression of IL-17RA and IL-17RC on fibroblasts through TGF-β1/Smad3 signaling pathway, which reveals a new mechanism of the therapeutic action of UVB on psoriasis.

A Mixture of Extracts of Kochia scoparia and Rosa multiflora with PPAR α/γ Dual Agonistic Effects Prevents Photoaging in Hairless Mice

Activation of peroxisome proliferator-activated receptors (PPAR) α/γ is known to inhibit the increases in matrix metalloproteinase (MMP) and reactive oxygen species (ROS) induced by ultraviolet light (UV). Extracts of natural herbs, such as Kochia scoparia and Rosa multiflora, have a PPAR α/γ dual agonistic effect. Therefore, we investigated whether and how they have an antiaging effect on photoaging skin. Eighteen-week-old hairless mice were irradiated with UVA 14 J/cm² and UVB 40 mJ/cm² three times a week for 8 weeks. A mixture of extracts of Kochia scoparia and Rosa multiflora (KR) was topically applied on the dorsal skin of photoaging mice twice a day for 8 weeks. Tesaglitazar, a known PPAR α/γ agonist, and vehicle (propylene glycol:ethanol = 7:3, v/v) were applied as positive and negative controls, respectively. Dermal effects (including dermal thickness, collagen density, dermal expression of procollagen 1 and collagenase 13) and epidermal effects (including skin barrier function, epidermal proliferation, epidermal differentiation, and epidermal cytokines) were measured and compared. In photoaging murine skin, KR resulted in a significant recovery of dermal thickness as well as dermal fibroblasts, although it did not change dermal collagen density. KR increased the expression of dermal transforming growth factor (TGF)-β. The dermal effects of KR were explained by an increase in procollagen 1 expression, induced by TGF-β, and a decrease in MMP-13 expression. KR did not affect basal transepidermal water loss (TEWL) or stratum corneum (SC) integrity, but did decrease SC hydration. It also did not affect epidermal proliferation or epidermal differentiation. KR decreased the expression of epidermal interleukin (IL)-1α. Collectively, KR showed possible utility as a therapeutic agent for photoaging skin, with few epidermal side effects such as epidermal hyperplasia or poor differentiation.

Activation of Peroxisome Proliferator-Activated Receptor Alpha Improves Aged and UV-Irradiated Skin by Catalase Induction

Peroxisome proliferator-activated receptor alpha (PPARα) is a nuclear hormone receptor involved in the transcriptional regulation of lipid metabolism, fatty acid oxidation, and glucose homeostasis. Its activation stimulates antioxidant enzymes such as catalase, whose expression is decreased in aged human skin. Here we investigated the expression of PPARα in aged and ultraviolet (UV)-irradiated skin, and whether PPARα activation can modulate expressions of matrix metalloproteinase (MMP)-1 and procollagen through catalase regulation. We found that PPARα mRNA level was significantly decreased in intrinsically aged and photoaged human skin as well as in UV-irradiated skin. A PPARα activator, Wy14643, inhibited UV-induced increase of MMP-1 and decrease of procollagen expression and caused marked increase in catalase expression. Furthermore, production of reactive oxygen species (ROS) was suppressed by Wy14643 in UV-irradiated and aged dermal fibroblasts, suggesting that the PPARα activation-induced upregulation of catalase leads to scavenging of ROS produced due to UV irradiation or aging. PPARα knockdown decreased catalase expression and abolished the beneficial effects of Wy14643. Topical application of Wy14643 on hairless mice restored catalase activity and prevented MMP-13 and inflammatory responses in skin. Our findings indicate that PPARα activation triggers catalase expression and ROS scavenging, thereby protecting skin from UV-induced damage and intrinsic aging.

The role of PPARγ-mediated signalling in skin biology and pathology: new targets and opportunities for clinical dermatology

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that modulate the expression of multiple different genes involved in the regulation of lipid, glucose and amino acid metabolism. PPARs and cognate ligands also regulate important cellular functions, including cell proliferation and differentiation, as well as inflammatory responses. This includes a role in mediating skin and pilosebaceous unit homoeostasis: PPARs appear to be essential for maintaining skin barrier permeability, inhibit keratinocyte cell growth, promote keratinocyte terminal differentiation and regulate skin inflammation. They also may have protective effects on human hair follicle (HFs) epithelial stem cells, while defects in PPARγ-mediated signalling may promote the death of these stem cells and thus facilitate the development of cicatricial alopecia (lichen planopilaris). Overall, however, selected PPARγ modulators appear to act as hair growth inhibitors that reduce the proliferation and promote apoptosis of hair matrix keratinocytes. The fact that commonly prescribed PPARγ-modulatory drugs of the thiazolidine-2,4-dione class can exhibit a battery of adverse cutaneous effects underscores the importance of distinguishing beneficial from clinically undesired cutaneous activities of PPARγ ligands and to better understand on the molecular level how PPARγ-regulated cutaneous lipid metabolism and PPARγ-mediated signalling impact on human skin physiology and pathology. Surely, the therapeutic potential that endogenous and exogenous PPARγ modulators may possess in selected skin diseases, ranging from chronic inflammatory hyperproliferative dermatoses like psoriasis and atopic dermatitis, via scarring alopecia and acne can only be harnessed if the complexities of PPARγ signalling in human skin and its appendages are systematically dissected.

Orange peel extract, containing high levels of polymethoxyflavonoid, suppressed UVB-induced COX-2 expression and PGE2 production in HaCaT cells through PPAR-γ activation

Ultraviolet light (UV) induces an inflammatory response in the skin by cyclooxygenase (COX)-2 expression and prostaglandin (PG) E2 production. Citrus peel has been used as a natural medicine. It contains polymethoxyflavonoids (PMFs) as a major ingredient, which have anti-inflammatory activity. We obtained orange peel extract containing high levels of PMFs. The extract suppressed UVB-induced COX-2 expression and PGE2 production in HaCaT cells. Furthermore, it was found that this extract acted as a peroxisome proliferator-activated receptor (PPAR)-γ agonist. The suppression of UVB-induced COX-2 expression by this extract was inhibited by GW 9662 and T0070907, which are both PPAR-γ antagonists. It is therefore suggested that orange peel extract, containing high levels of PMFs, suppresses UVB-induced COX-2 expression and PGE2 production through PPAR-γ. Hence, these extracts could provide useful protection against or alleviation of UV damage.

Peptoid-Substituted Hybrid Antimicrobial Peptide Derived from Papiliocin and Magainin 2 with Enhanced Bacterial Selectivity and Anti-inflammatory Activity

Antimicrobial peptides (AMPs) are important components of the host innate immune system. Papiliocin is a 37-residue AMP purified from larvae of the swallowtail butterfly Papilio xuthus. Magainin 2 is a 23-residue AMP purified from the skin of the African clawed frog Xenopus laevis. We designed an 18-residue hybrid peptide (PapMA) incorporating N-terminal residues 1-8 of papiliocin and N-terminal residues 4-12 of magainin 2, joined by a proline (Pro) hinge. PapMA showed high antimicrobial activity but was cytotoxic to mammalian cells. To decrease PapMA cytotoxicity, we designed a lysine (Lys) peptoid analogue, PapMA-k, which retained high antimicrobial activity but displayed cytotoxicity lower than that of PapMA. Fluorescent dye leakage experiments and confocal microscopy showed that PapMA targeted bacterial cell membranes whereas PapMA-k penetrated bacterial cell membranes. Nuclear magnetic resonance experiments revealed that PapMA contained an N-terminal α-helix from Lys(3) to Lys(7) and a C-terminal α-helix from Lys(10) to Lys(17), with a Pro(9) hinge between them. PapMA-k also had two α-helical structures in the same region connected with a flexible hinge residue at Nlys(9), which existed in a dynamic equilibrium of cis and trans conformers. Using lipopolysaccharide-stimulated RAW264.7 macrophages, the anti-inflammatory activity of PapMA and PapMA-k was confirmed by inhibition of nitric oxide and inflammatory cytokine production. In addition, treatment with PapMA and PapMA-k decreased the level of ultraviolet irradiation-induced expression of genes encoding matrix metalloproteinase-1 (MMP-1), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) in human keratinocyte HaCaT cells. Thus, PapMA and PapMA-k are potent peptide antibiotics with antimicrobial and anti-inflammatory activity, with PapMA-k displaying enhanced bacterial selectivity.

Dihydroavenanthramide D prevents UV-irradiated generation of reactive oxygen species and expression of matrix metalloproteinase-1 and -3 in human dermal fibroblasts

Ultraviolet B (UVB) radiation induces photoageing by upregulating the expression of matrix metalloproteinases (MMPs) in human skin cells. Dihydroavenanthramide D (DHAvD) is a synthetic analog to naturally occurring avenanthramide, which is the active component in oats. Although anti-inflammatory, anti-atherosclerotic and antioxidant effects have been reported, the antiphotoageing effects of DHAvD are yet to be understood. In this study, we investigated the inhibitory effects of DHAvD on UVB-induced production of reactive oxygen species (ROS) and expression of MMPs, and its molecular mechanism in UVB-irradiated human dermal fibroblasts. Western blot and real-time PCR analyses revealed that DHAvD inhibited UVB-induced MMP-1 and MMP-3 expression. It also significantly blocked UVB-induced ROS generation in fibroblasts. Additionally, DHAvD attenuated UVB-induced phosphorylation of MAPKs, activation of NF-κB and AP-1. DHAvD regulates UVB-irradiated MMP expression by inhibiting ROS-mediated MAPK/NF-κB and AP-1 activation. DHAvD may be a useful candidate for preventing UV light-induced skin photoageing.

N-Phenethyl caffeamide and photodamage: protecting skin by inhibiting type I procollagen degradation and stimulating collagen synthesis

Skin is mainly damaged by genetic and environmental factors such as ultraviolet (UV) light and pollutants. UV light is a well-known factor that causes various types of skin damage and premature aging. Reactive oxygen species (ROS) are commonly involved in the pathogenesis of skin damage by activating the metalloproteinases that break down type I collagen. This study investigated the antioxidant and antiphotodamage activity and mechanisms of N-phenethyl caffeamide (K36) in human skin fibroblasts. The results indicated that K36 demonstrated strong 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging activity, which dose-dependently reduced the production of UVB-induced intracellular ROS in human dermal fibroblasts. K36 prevented UVB-irradiation-induced type I collagen degradation by inhibiting the expression of matrix metalloproteins-1, -3, and -9 and the phosphorylation of mitogen-activated protein (MAP) kinases. Furthermore, K36 elevated collagen synthesis in skin fibroblasts by inhibiting UVB-induced Smad7 overexpression. K36 downregulated the expression of the transcription factor, activator protein-1 (AP-1). Our results indicated that K36 exhibited antioxidant properties and prevented skin collagen degradation caused by UV exposure and the stimulation of collagen synthesis, which suggests the potential use of K36 in preventing photodamage.

Sargahydroquinoic acid inhibits TNFα-induced AP-1 and NF-κB signaling in HaCaT cells through PPARα activation

Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily of ligand-activated transcription factors and expressed in various cell types in the skin, including keratinocytes, fibroblasts and infiltrating immune cells. Thus, their ligands are targets for the treatment of various skin disorders, such as photo-aging and chronological aging of skin. Intensive studies have revealed that PPARα/γ functions in photo-aging and age-related inflammation by regulating matrix metalloproteinases (MMPs) via activator protein-1 (AP-1) and nuclear factor kappa B (NF-κB). However, the detailed mechanism of PPARα/γ's role in skin aging has not yet been elucidated. In this study, we confirmed that sargahydroquinoic acid (SHQA) as a PPARα/γ ligand significantly decreased Tumor Necrosis Factor-alpha (TNFα)-induced MMP-2/-9 expression by downregulating TNFα-induced transcription factors, subsequently reducing IκBα degradation and blocking NF-κB p65 nuclear translocation in HaCaT human epidermal keratinocyte cells. Treatment of cells with SHQA and GW6471 (PPARα antagonist) not bisphenol A diglycidyl ether (PPARγ antagonists), reversed the effect on TNFα-induced inflammatory signaling pathway activation. Taken together, our data suggest that SHQA inhibit TNFα-induced MMP-2/-9 expression and age-related inflammation by suppressing AP-1 and NF-κB pathway via PPARα.

The protective effect of Kaempferia parviflora extract on UVB-induced skin photoaging in hairless mice

BACKGROUND

Chronic skin exposure to ultraviolet (UV) light increases reactive oxygen species (ROS) and stimulates the expression of matrix metalloproteinases (MMPs) through c-Jun and c-Fos activation. These signaling cascades induce the degradation of extracellular matrix (ECM) components, resulting in photoaging.

METHODS

This study evaluated the preventive effect of the ethanol extract of Kaempferia parviflora Wall. ex. Baker (black ginger) on UVB-induced photoaging in vivo. To investigate the antiphotoaging effect of K. parviflora extract (KPE), UVB-irradiated hairless mice administered oral doses of KPE (100 or 200 mg/kg/day) for 13 weeks.

RESULTS

In comparison to the UVB control group, KPE significantly prevented wrinkle formation and the loss of collagen fibers with increased type I, III, and VII collagen genes (COL1A1, COL3A1, and COL7A1). The decrease in wrinkle formation was associated with a significant reduction in the UVB-induced expression of MMP-2, MMP-3, MMP-9, and MMP-13 via the suppression of c-Jun and c-Fos activity. KPE also increased the expression of catalase, which acts as an antioxidant enzyme in skin. In addition, expression of inflammatory mediators, such as nuclear factor kappa B (NF-κB), interleukin-1β (IL-1β), and cyclooxygenase-2 (COX-2), was significantly reduced by KPE treatment.

CONCLUSION

The results show that oral administration of KPE significantly prevents UVB-induced photoaging in hairless mice, suggesting its potential as a natural antiphotoaging material.

Role of PPAR, LXR, and PXR in epidermal homeostasis and inflammation

Epidermal lipid synthesis and metabolism are regulated by nuclear hormone receptors (NHR) and in turn epidermal lipid metabolites can serve as ligands to NHR. NHR form a large superfamily of receptors modulating gene transcription through DNA binding. A subgroup of these receptors is ligand-activated and heterodimerizes with the retinoid X receptor including peroxisome proliferator-activated receptor (PPAR), liver X receptor (LXR) and pregnane X receptor (PXR). Several isotypes of these receptors exist, all of which are expressed in skin. In keratinocytes, ligand activation of PPARs and LXRs stimulates differentiation, induces lipid accumulation, and accelerates epidermal barrier regeneration. In the cutaneous immune system, ligand activation of all three receptors, PPAR, LXR, and PXR, has inhibitory properties, partially mediated by downregulation of the NF-kappaB pathway. PXR also has antifibrotic effects in the skin correlating with TGF-beta inhibition. In summary, ligands of PPAR, LXR and PXR exert beneficial therapeutic effects in skin disease and represent promising targets for future therapeutic approaches in dermatology. This article is part of a Special Issue entitled The Important Role of Lipids in the Epidermis and their Role in the Formation and Maintenance of the Cutaneous Barrier. Guest Editors: Kenneth R. Feingold and Peter Elias.

Photoprotective effect of libanoridin isolated from Corydalis heterocarpa on UVB stressed human keratinocyte cells

Ultraviolet-B (UVB) irradiation acts primarily on the epidermal basal cell layer of the skin, inducing harmful biological effects. In this study, we have investigated the effect of libanoridin isolated from Corydalis heterocarpa against UVB-induced damage in human keratinocyte (HaCaT) cells and the molecular mechanism underlying those effects. Treatment with libanoridin inhibited the cell cytotoxicity and LDH induced by UVB exposure at 40 mJ/cm(2). Additionally, expression levels of type IV collagenases (MMP-2, MMP-9) were decreased by libanoridin. Furthermore, MMP tissue inhibitors were enhanced followed by treatment with libanoridin. Moreover, UVB-induced activation of phosphorylation of three MAPKs such as JNK, ERK, p38 and AP-1 transcription factor were decreased by treatment with libanoridin. Our present study demonstrates that libanoridin has the abilities to inhibit UVB-induced cellular damage via ASK1-MAPK and AP-1 signalling pathways. Therefore, libanoridin may be used as an effective natural compound to prevent skin damage due to UVB exposure.

Spontaneous occurrence of photoageing-like phenotypes in the dorsal skin of old SAMP1 mice, an oxidative stress model

Skin photoageing is a complex, multifactorial process and both intrinsic and extrinsic factors may contribute to its pathogenesis. The ultraviolet-irradiated hairless mouse has been used as an animal model for photoageing, but this model mimics only the 'extrinsic' aspects. Here, we show that skin from old SAMP1 mice, a model for higher oxidative stress and senescence acceleration, exhibited histological and gene expression changes similar to those in human photoaged skin without ultraviolet irradiation. These changes include an increase in elastic fibre and glycosaminoglycan histologically, an upregulation of several proinflammatory cytokines and matrix metalloproteinases, and an increase in lipid peroxide. We propose that SAMP1 mice are a spontaneous animal model for photoageing caused by an exaggerated intrinsic mechanism, namely, higher oxidative status. This mouse model is useful to explore the link between oxidative stress and photoageing, and to evaluate the efficacy of antioxidants.

Azelaic acid reduced senescence-like phenotype in photo-irradiated human dermal fibroblasts: possible implication of PPARγ

Azelaic acid (AzA) has been used for the treatment for inflammatory skin diseases, such as acne and rosacea. Interestingly, an improvement in skin texture has been observed after long-time treatment with AzA. We previously unrevealed that anti-inflammatory activity of AzA involves a specific activation of PPARγ, a nuclear receptor that plays a relevant role in inflammation and even in ageing processes. As rosacea has been considered as a photo-aggravated disease, we investigated the ability of AzA to counteract stress-induced premature cell senescence (SIPS). We employed a SIPS model based on single exposure of human dermal fibroblasts (HDFs) to UVA and 8-methoxypsoralen (PUVA), previously reported to activate a senescence-like phenotype, including long-term growth arrest, flattened morphology and increased synthesis of matrix metalloproteinases (MMPs) and senescence-associated β-galactosidase (SA-β-gal). We found that PUVA-treated HDFs grown in the presence of AzA maintained their morphology and reduced MMP-1 release and SA-β-galactosidase-positive cells. Moreover, AzA induced a reduction in ROS generation, an up-modulation of antioxidant enzymes and a decrease in cell membrane lipid damages in PUVA-treated HDFs. Further evidences of AzA anti-senescence effect were repression of p53 and p21, increase in type I pro-collagen and abrogation of the enhanced expression of growth factors, such as HGF and SCF. Interestingly, PUVA-SIPS showed a decreased activation of PPARγ and AzA counteracted this effect, suggesting that AzA effect involves PPARγ modulation. All together these data showed that AzA interferes with PUVA-induced senescence-like phenotype and its ability to activate PPAR-γ provides relevant insights into the anti-senescence mechanism.

Expression and Function of PPARs in Placenta

Peroxisome proliferator-activated receptors (PPAR) are members of the superfamily of nuclear hormone receptors involved in embryonic development and differentiation of several tissues including placenta, which respond to specific ligands such as polyunsaturated fatty acids by altering gene expression. Three subtypes of this receptor have been discovered, each evolving to achieve different biological functions. The PPARs also control a variety of target genes involved in lipid homeostasis. Similar to other nuclear receptors, the transcriptional activity of PPARs is affected not only by ligand-stimulation but also by crosstalk with other molecules. For example, both PPARs and the RXRs are ligand-activated transcription factors that coordinately regulate gene expression. In addition, several mechanisms underlying negative regulation of gene expression by PPARs have been shown. It is suggested that PPARs are key messengers responsible for the translation of nutritional stimuli into changes in gene expression pathways for placental development.

Decursin inhibits UVB-induced MMP expression in human dermal fibroblasts via regulation of nuclear factor-κB

Decursin, a coumarin compound, was originally isolated from the roots of Angelica gigas almost four decades ago, and it was found to exhibit cytotoxicity against various types of human cancer cells and anti-amnesic activity in vivo through the inhibition of AChE activity. However, the anti-skin photoaging effects of decursin have not been reported to date. In the present study, we investigated the inhibitory effects of decursin on the expression of matrix metalloproteinase (MMP)-1 and MMP-3 in human dermal fibroblast (HDF) cells. Western blot analysis and real-time PCR revealed that decursin inhibited the ultraviolet (UV)B-induced expression of MMP-1 and MMP-3 in a dose-dependent manner. Decursin significantly blocked the UVB-induced activation of nuclear factor-κB (NF-κB). However, decursin showed no effect on MAPK or AP-1 activity. In this study, decursin prevented the UVB-induced expression of MMPs via the inhibition of NF-κB activation. In conclusion, decursin may be a potential agent for the prevention and treatment of skin photoaging.