Perillaldehyde Inhibits AHR Signaling and Activates NRF2 Antioxidant Pathway in Human Keratinocytes

Navigating the Landscape of Coronary Microvascular Research: Trends, Triumphs, and Challenges Ahead

Coronary microvascular dysfunction (CMD) refers to structural and functional abnormalities of the microcirculation that impair myocardial perfusion. CMD plays a pivotal role in numerous cardiovascular diseases, including myocardial ischemia with non-obstructive coronary arteries, heart failure, and acute coronary syndromes. This review summarizes recent advances in CMD pathophysiology, assessment, and treatment strategies, as well as ongoing challenges and future research directions. Signaling pathways implicated in CMD pathogenesis include adenosine monophosphate-activated protein kinase/Krüppel-like factor 2/endothelial nitric oxide synthase (AMPK/KLF2/eNOS), nuclear factor erythroid 2-related factor 2/antioxidant response element (Nrf2/ARE), Angiotensin II (Ang II), endothelin-1 (ET-1), RhoA/Rho kinase, and insulin signaling. Dysregulation of these pathways leads to endothelial dysfunction, the hallmark of CMD. Treatment strategies aim to reduce myocardial oxygen demand, improve microcirculatory function, and restore endothelial homeostasis through mechanisms including vasodilation, anti-inflammation, and antioxidant effects. Traditional Chinese medicine (TCM) compounds exhibit therapeutic potential through multi-targeted actions. Small molecules and regenerative approaches offer precision therapies. However, challenges remain in translating findings to clinical practice and developing effective pharmacotherapies. Integration of engineering with medicine through microfabrication, tissue engineering and AI presents opportunities to advance the diagnosis, prediction, and treatment of CMD.

Q-switched Nd:YAG laser protects human keratinocytes from oxidative stress and inflammation via AhR-Nrf2 pathway

In recent years, some treatments for esthetic and pathologic skin conditions have increasingly been based on the use of non-ablative neodymium-doped yttrium aluminum garnet (Nd:YAG) laser due to its greater penetration ability than other types of lasers, few contraindications, minimal side effects, no damage for epidermidis and the rapid recovery of the treated patients. The skin is frequently exposed to many stressors such as radiation, toxic substances, metabolites, foods, mechanical insults, and allergen exposition that cause oxidative damage and have a decisive influence on the aging process. The imbalance between reactive oxygen species, reactive nitrogen species, and the malfunctioning of the antioxidant defense system promotes the establishment of an excessive inflammatory process, which can induce various diseases including cancer and neurodegenerative disorders. The present study investigated the cytoprotective function of Q-switched Nd:YAG laser against stress aging and cell injury in HaCaT cells. We evaluated the effect of the laser on antioxidant defenses, inflammation, metalloproteinases' expression, and the AhR-Nrf2 pathway. Q-switched Nd:YAG is able to upregulate the AhR pathway and the expression of IL-6 and TGF-β, which are involved in wound repair process, and to downregulate the expression of MMP-2 and 9, so preventing the collagen degradation. Q-switched Nd:YAG can stimulate the cellular antioxidant defenses by activating the AhR-Nrf2 system.

Jdp2 is a spatiotemporal transcriptional activator of the AhR via the Nrf2 gene battery

BACKGROUND

Crosstalk between the aryl hydrocarbon receptor (AhR) and nuclear factor (erythroid-derived 2)-like 2 (Nrf2) signaling is called the "AhR-Nrf2 gene battery", which works synergistically in detoxification to support cell survival. Nrf2-dependent phase II gene promoters are controlled by coordinated recruitment of the AhR to adjacent dioxin responsive element (DRE) and Nrf2 recruitment to the antioxidative response element (ARE). The molecular interaction between AhR and Nrf2 members, and the regulation of each target, including phase I and II gene complexes, and their mediators are poorly understood.

METHODS

Knockdown and forced expression of AhR-Nrf2 battery members were used to examine the molecular interactions between the AhR-Nrf2 axis and AhR promoter activation. Sequential immunoprecipitation, chromatin immunoprecipitation, and histology were used to identify each protein complex recruited to their respective cis-elements in the AhR promoter. Actin fiber distribution, cell spreading, and invasion were examined to identify functional differences in the AhR-Jdp2 axis between wild-type and Jdp2 knockout cells. The possible tumorigenic role of Jdp2 in the AhR-Nrf2 axis was examined in mutant Kras-Trp53-driven pancreatic tumors.

RESULTS

Crosstalk between AhR and Nrf2 was evident at the transcriptional level. The AhR promoter was activated by phase I ligands such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) through the AhR-Jdp2-Nrf2 axis in a time- and spatial transcription-dependent manner. Jdp2 was a bifunctional activator of DRE- and ARE-mediated transcription in response to TCDD. After TCDD exposure, Jdp2 activated the AhR promoter at the DRE and then moved to the ARE where it activated the promoter to increase reactive oxygen species (ROS)-mediated functions such as cell spreading and invasion in normal cells, and cancer regression in mutant Kras-Trp53-driven pancreatic tumor cells.

CONCLUSIONS

Jdp2 plays a critical role in AhR promoter activation through the AhR-Jdp2-Nrf2 axis in a spatiotemporal manner. The AhR functions to maintain ROS balance and cell spreading, invasion, and cancer regression in a mouse model of mutant Kras-Trp53 pancreatic cancer. These findings provide new insights into the roles of Jdp2 in the homeostatic regulation of oxidative stress and in the antioxidation response in detoxification, inflammation, and cancer progression.

Galactomyces Ferment Filtrate Potentiates an Anti-Inflammaging System in Keratinocytes

Skincare products play a crucial role in preventing the dry skin induced by various causes. Certain ingredients can help to improve the efficacy of skincare products. Galactomyces ferment filtrate (GFF) is such a functional ingredient. Its use originated from the empirical observation that the hands of sake brewers who deal with yeast fermentation retain a beautiful and youthful appearance. Consequently, skincare products based on GFF are widely used throughout the world. Recent studies have demonstrated that GFF activates an aryl hydrocarbon receptor (AHR) and upregulates the expression of filaggrin, a pivotal endogenous source of natural moisturizing factors, in epidermal keratinocytes. It also activates nuclear factor erythroid-2-related factor 2 (NRF2), the antioxidative master transcription factor, and exhibits potent antioxidative activity against oxidative stress induced by ultraviolet irradiation and proinflammatory cytokines, which also accelerate inflammaging. GFF-mediated NRF2 activation downregulates the expression of CDKN2A, which is known to be overexpressed in senescent keratinocytes. Moreover, GFF enhances epidermal terminal differentiation by upregulating the expression of caspase-14, claudin-1, and claudin-4. It also promotes the synthesis of the antiinflammatory cytokine IL-37 and downregulates the expression of proallergic cytokine IL-33 in keratinocytes. In addition, GFF downregulates the expression of the CXCL14 and IL6R genes, which are involved in inflammaging. These beneficial properties might underpin the potent barrier-protecting and anti-inflammaging effects of GFF-containing skin formulae.

Recent Advances in the Role of Nuclear Factor Erythroid-2-Related Factor 2 in Spinal Cord Injury: Regulatory Mechanisms and Therapeutic Options

Nuclear factor erythroid-2-related factor 2 (Nrf2) is a pleiotropic transcription factor, and it has been documented that it can induce defense mechanisms both oxidative stress and inflammatory injury. At present, more and more evidences show that the Nrf2 signaling pathway is a key pharmacological target for the treatment of spinal cord injury (SCI), and activating the Nrf2 signaling pathway can effectively treat the inflammatory injury and oxidative stress after SCI. This article firstly introduces the biological studies of the Nrf2 pathway. Meanwhile, it is more powerful to explain that activating the Nrf2 signaling pathway can effectively treat SCI by deeply exploring the relationship between Nrf2 and oxidative stress, inflammatory injury, and SCI. In addition, several potential drugs for the treatment of SCI by promoting Nrf2 activation and Nrf2-dependent gene expression are reviewed. And some other treatment strategies of SCI by modulating the Nrf2 pathway are also summarized. It will provide new ideas and directions for the treatment of SCI.

Therapeutic Potential of Perillaldehyde in Ameliorating Vulvovaginal Candidiasis by Reducing Vaginal Oxidative Stress and Apoptosis

Vulvovaginal candidiasis (VVC) is one of the most frequent diseases induced by Candida albicans (C. albicans) during pregnancy, which results in enormous pain to women and their partners in daily life. Perillaldehyde (PAE), a natural monoterpenoid, has significant anti-microbial, anti-inflammatory and anti-oxidation effects. Reactive oxygen species (ROS) are key factors for the host to resist the invasion of fungi. However, excess ROS can cause additional damage independent of the pathogen itself, and the mechanism of ROS in VVC has not been investigated. In this murine study, we revealed that C. albicans infection increased the expression of NADPH oxidase 2 (NOX2) and the content of malonaldehyde (MDA). C. albicans inhibited the activity of antioxidant enzymes in the vagina, including superoxide dismutase (SOD), Catalase (CAT), glutathione peroxidase (GSH-PX) and heme oxygenase (HO-1), which were returned to normal levels after treatment with PAE. Furthermore, PAE inhibited the activities of Keap1 and promoted Nrf2 transfer from cytoplasm to nucleus, which were mediated by excessive accumulation of ROS in the VVC mice. In this study, we also indicated that PAE inhibited the apoptosis of vagina cells via Caspase 9- Caspase 7-PARP pathway and prevented the release of IL-1ꞵ in VVC mice. In summary, this study revealed that the treatment of VVC in mice with PAE might be mediated by inhibition of ROS, and established the therapeutic potential of PAE as an antifungal agent for the treatment of VVC.

Exploring the Critical Components and Therapeutic Mechanisms of Perilla frutescens L. in the Treatment of Chronic Kidney Disease via Network Pharmacology

Chronic kidney disease (CKD) is a chronic progressive disease that seriously threatens human health. Some patients will continue to progress into the CKD stage 3–5 (also called chronic renal failure), which is mainly manifested by a decline in renal function and multi-system damage. Perilla frutescens (L.) Britton. (Lamiaceae) is one of the most widely used traditional Chinese medicine (TCM) herbs in CKD, especially in CKD stage 3–5. But its active components and mechanisms are still unclear. In this study, we used network pharmacology to analyze the active components of P. frutescens and the main therapeutic targets for intervention in CKD stage 3–5. Then, the key components were selected for enrichment analysis and identified by high performance liquid chromatograph (HPLC). Finally, we verified the critical components through molecular docking, and in vitro experiments. The results show that 19 main active components of P. frutescens were screened, and 108 targets were intersected with CKD stage 3–5. The PPI network was constructed and found that the core nodes AKT1, TP53, IL6, TNF, and MAPK1 may be key therapeutic targets. Enrichment analysis shows that related targets may be involved in regulating various biological functions, and play a therapeutic role in CKD stage 3–5 by regulating apoptosis, T cell receptor, and PI3K-AKT signaling pathways. Molecular docking indicates that the key active components were well docked with its corresponding targets. Five active components were identified and quantified by HPLC. According to the results, luteolin was selected as the critical component for further verification. In vitro experiments have shown that luteolin can effectively alleviate adriamycin (ADR)-induced renal tubular apoptosis and suppress AKT and p53 phosphorylation. The effects of luteolin to reduce apoptosis may be mediated by inhibiting oxidative stress and downregulating the mitogen-activated protein kinase (MAPK) and p53 pathways. In general, we screened and analyzed the possible active components, therapeutic targets and pathways of P. frutescens for treating CKD. Our findings revealed that luteolin can reduce renal tubular epithelial cell apoptosis and may be the critical component of P. frutescens in the treatment of CKD. It provides references and direction for further research.

Characterization of a thermotolerant aryl-alcohol oxidase from Moesziomyces antarcticus oxidizing 5-hydroxymethyl-2-furancarboxylic acid

The development of enzymatic processes for the environmentally friendly production of 2,5-furandicarboxylic acid (FDCA), a renewable precursor for bioplastics, from 5-hydroxymethylfurfural (HMF) has gained increasing attention over the last years. Aryl-alcohol oxidases (AAOs) catalyze the oxidation of HMF to 5-formyl-2-furancarboxylic acid (FFCA) through 2,5-diformylfuran (DFF) and have thus been applied in enzymatic reaction cascades for the production of FDCA. AAOs are flavoproteins that oxidize a broad range of benzylic and aliphatic allylic primary alcohols to the corresponding aldehydes, and in some cases further to acids, while reducing molecular oxygen to hydrogen peroxide. These promising biocatalysts can also be used for the synthesis of flavors, fragrances, and chemical building blocks, but their industrial applicability suffers from low production yield in natural and heterologous hosts. Here we report on heterologous expression of a new aryl-alcohol oxidase, MaAAO, from Moesziomyces antarcticus at high yields in the methylotrophic yeast Pichia pastoris (recently reclassified as Komagataella phaffii). Fed-batch fermentation of recombinant P. pastoris yielded around 750 mg of active enzyme per liter of culture. Purified MaAAO was highly stable at pH 2-9 and exhibited high thermal stability with almost 95% residual activity after 48 h at 57.5 °C. MaAAO accepts a broad range of benzylic primary alcohols, aliphatic allylic alcohols, and furan derivatives like HMF as substrates and some oxidation products thereof like piperonal or perillaldehyde serve as building blocks for pharmaceuticals or show health-promoting effects. Besides this, MaAAO oxidized 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) to FFCA, which has not been shown for any other AAO so far. Combining MaAAO with an unspecific peroxygenase oxidizing HMFCA to FFCA in one pot resulted in complete conversion of HMF to FDCA within 144 h. MaAAO is thus a promising biocatalyst for the production of precursors for bioplastics and bioactive compounds. KEY POINTS: • MaAAO from M. antarcticus was expressed in P. pastoris at 750 mg/l. • MaAAO oxidized 5-hydroxymethyl-2-furancarboxylic acid (HMFCA). • Complete conversion of HMF to 2,5-furandicarboxylic acid by combining MaAAO and UPO.

Protective Effects of Maclurin against Benzo[a]pyrene via Aryl Hydrocarbon Receptor and Nuclear Factor Erythroid 2-Related Factor 2 Targeting

Benzo[a]pyrene (B[a]P), a polycyclic aromatic hydrocarbon formed during the incomplete combustion of organic matter, has harmful effects. Therefore, much research is ongoing to develop agents that can mitigate the effects of B[a]P. The aim of this study was to examine the effect of maclurin, one component of the branches of Morus alba L., on the B[a]P-induced effects in HaCaT cells, a human keratinocyte cell line. Maclurin treatment inhibited aryl hydrocarbon receptor (AHR) signaling as evidenced by reduced xenobiotic response element (XRE) reporter activity, decreased expression of cytochrome P450 1A1 (CYP1A1), and reduced nuclear translocation of AHR. The B[a]P-induced dissociation of AHR from AHR-interacting protein (AIP) was suppressed by maclurin. Maclurin also inhibited the production of intracellular reactive oxygen species (ROS) induced by B[a]P. In addition, the antioxidant property of maclurin itself was demonstrated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. Furthermore, maclurin activated antioxidant response element (ARE) signaling through enhancement of ARE luciferase reporter activity and the expression of ARE-dependent genes including nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase-1 (HO-1). Nrf2 activation and its nuclear translocation were promoted by maclurin through p38 MAPK activation. These data indicate that maclurin had antagonistic activity against B[a]P effects through activation of Nrf2-mediated signaling and inhibition of AHR signaling and, suggesting its potential in protecting from harmful B[a]P-containing pollutants.

Perillaldehyde Inhibition of cGAS Reduces dsDNA-Induced Interferon Response

Cyclic GMP-AMP synthase (cGAS), serving as a primary sensor of intracellular DNA, is essential to initiate anti-microbial innate immunity. Inappropriate activation of cGAS by self-DNA promotes severe autoinflammatory diseases such as Aicardi-Goutières syndrome (AGS); thus, inhibition of cGAS may provide therapeutic benefit in anti-autoimmunity. Here we report that perillaldehyde (PAH), a natural monoterpenoid compound derived from Perilla frutescens, suppresses cytosolic-DNA-induced innate immune responses by inhibiting cGAS activity. Mice treated with PAH are more susceptible to herpes simplex virus type 1 (HSV-1) infection. Moreover, administration with PAH markedly ameliorates self-DNA-induced autoinflammatory responses in a mouse model of AGS. Collectively, our study reveals that PAH can effectively inhibit cGAS-STING signaling and could be developed toward the treatment of cGAS-mediated autoimmune diseases.

Dimethyl sulfoxide stimulates the AhR-Jdp2 axis to control ROS accumulation in mouse embryonic fibroblasts

The aryl hydrocarbon receptor (AhR) is a ligand-binding protein that responds to environmental aromatic hydrocarbons and stimulates the transcription of downstream phase I enzyme–related genes by binding the cis element of dioxin-responsive elements (DREs)/xenobiotic-responsive elements. Dimethyl sulfoxide (DMSO) is a well-known organic solvent that is often used to dissolve phase I reagents in toxicology and oxidative stress research experiments. In the current study, we discovered that 0.1% DMSO significantly induced the activation of the AhR promoter via DREs and produced reactive oxygen species, which induced apoptosis in mouse embryonic fibroblasts (MEFs). Moreover, Jun dimerization protein 2 (Jdp2) was found to be required for activation of the AhR promoter in response to DMSO. Coimmunoprecipitation and chromatin immunoprecipitation studies demonstrated that the phase I–dependent transcription factors, AhR and the AhR nuclear translocator, and phase II–dependent transcription factors such as nuclear factor (erythroid-derived 2)–like 2 (Nrf2) integrated into DRE sites together with Jdp2 to form an activation complex to increase AhR promoter activity in response to DMSO in MEFs. Our findings provide evidence for the functional role of Jdp2 in controlling the AhR gene via Nrf2 and provide insights into how Jdp2 contributes to the regulation of ROS production and the cell spreading and apoptosis produced by the ligand DMSO in MEFs.

Aryl Hydrocarbon Receptor and Dioxin-Related Health Hazards-Lessons from Yusho

Poisoning by high concentrations of dioxin and its related compounds manifests variable toxic symptoms such as general malaise, chloracne, hyperpigmentation, sputum and cough, paresthesia or numbness of the extremities, hypertriglyceridemia, perinatal abnormalities, and elevated risks of cancer-related mortality. Such health hazards are observed in patients with Yusho (oil disease in Japanese) who had consumed rice bran oil highly contaminated with 2,3,4,7,8-pentachlorodibenzofuran, polychlorinated biphenyls, and polychlorinated quaterphenyls in 1968. The blood concentrations of these congeners in patients with Yusho remain extremely elevated 50 years after onset. Dioxins exert their toxicity via aryl hydrocarbon receptor (AHR) through the generation of reactive oxygen species (ROS). In this review article, we discuss the pathogenic implication of AHR in dioxin-induced health hazards. We also mention the potential therapeutic use of herbal drugs targeting AHR and ROS in patients with Yusho.

Gastrodin Promotes the Survival of Random-Pattern Skin Flaps via Autophagy Flux Stimulation

The random-pattern flap has a significant application in full mouth restoration (reconstructive surgery) and plastic surgery owing to an easy operation with no axial vascular restriction. However, distal necrosis after flap operation is still considered the most common complication which makes it the Achilles heel in the clinical application of random-pattern flaps. A Chinese medicinal herb named gastrodin is an effective active ingredient of Gastrodia. Herein, the existing study explored the significant potential of gastrodin on flap survival and its underlying mechanism. Our obtained results show that gastrodin will significantly improve flap survival, reduce tissue edema, and increase blood flow. Furthermore, our studies reveal that gastrodin can promote angiogenesis and reduce the apoptotic process as well as oxidative stress. The results of immunohistochemistry and immunoblotting revealed that gastrodin has a role in the elevation of autophagy flux which results in induced autophagy. The use of 3MA (3-methyladenine) for the inhibition of induced autophagy significantly weakened the underlying benefits of gastrodin treatment. Taken together, our obtained results confirmed that gastrodin is an effective drug that can considerably promote the survival rate of flaps (random pattern) via enhancing autophagy. Enhanced autophagy is correlated with the elevation of angiogenesis, reduced level of oxidative stress, and inhibition of cell apoptosis.

Perillaldehyde Ameliorates Aspergillus fumigatus Keratitis by Activating the Nrf2/HO-1 Signaling Pathway and Inhibiting Dectin-1-Mediated Inflammation

Purpose

The purpose of this study was to investigate the therapeutic effect of perillaldehyde (PAE) on Aspergillus fumigatus (A. fumigatus) keratitis.

Methods

Human corneal epithelial cells (HCECs) were pretreated with PAE and stimulated with A. fumigatus mycelium. C57BL/6 mice were infected with A. fumigatus and treated with or without PAE 1 day after infection. Clinical scores, PCR, ELISA, and Western blotting were used to detect the expression of pro-inflammatory mediators, dendritic cell-associated c-type lectin-1 (Dectin-1), nuclear factor (erythroid-derived 2) like 2 (Nrf2), and heme oxygenase (HO-1). Nrf2 expression in HCECs pretreated with PAE was observed by immunofluorescence. NIMP-R14 protein expression and localization in mouse corneas were observed by immunofluorescence staining after treatment with PAE. Corneal colony counting, time-kill tests, and mycelial transformation inhibition tests were used to evaluate the antifungal effect of PAE.

Results

C57BL/6 mice treated with PAE at 1 day after infection had a lower clinical score and decreased IL-1β, TNF-α, IL-6, Dectin-1, and MPO levels. PAE treatment significantly reduced neutrophil recruitments to the corneal stroma. Compared with the DMSO-treated group, PAE treatment significantly decreased mRNA and protein levels of pro-inflammatory cytokines and Dectin-1 in HCECs. PAE pretreatment before A. fumigatus stimulation obviously elevated the mRNA and protein levels of components of the Nrf2/HO-1 axis. HCECs pretreated with PAE before infection showed a weakened ability to inhibit inflammation in the presence of brusatol (BT; an Nrf2 inhibitor) or ZnPP (an HO-1 inhibitor). PAE treatment significantly reduced the fungal load of C57BL/6 mouse corneas and inhibited fungal growth in vitro.

Conclusions

These data proved that PAE may ameliorate A. fumigatus keratitis by activating the Nrf2/HO-1 signaling pathway and inhibiting the Dectin-1 mediated inflammatory response and neutrophil recruitment. Furthermore, PAE exerts direct fungicidal activity on A. fumigatus.

Regulation of Skin Barrier Function via Competition between AHR Axis versus IL-13/IL-4‒JAK‒STAT6/STAT3 Axis: Pathogenic and Therapeutic Implications in Atopic Dermatitis

Atopic dermatitis (AD) is characterized by skin inflammation, barrier dysfunction, and chronic pruritus. As the anti-interleukin-4 (IL-4) receptor α antibody dupilumab improves all three cardinal features of AD, the type 2 cytokines IL-4 and especially IL-13 have been indicated to have pathogenic significance in AD. Accumulating evidence has shown that the skin barrier function is regulated via competition between the aryl hydrocarbon receptor (AHR) axis (up-regulation of barrier) and the IL-13/IL-4‒JAK‒STAT6/STAT3 axis (down-regulation of barrier). This latter axis also induces oxidative stress, which exacerbates inflammation. Conventional and recently developed agents for treating AD such as steroid, calcineurin inhibitors, cyclosporine, dupilumab, and JAK inhibitors inhibit the IL-13/IL-4‒JAK‒STAT6/STAT3 axis, while older remedies such as coal tar and glyteer are antioxidative AHR agonists. In this article, I summarize the pathogenic and therapeutic implications of the IL-13/IL-4‒JAK‒STAT6/STAT3 axis and the AHR axis in AD.

Galuteolin suppresses proliferation and inflammation in TNF-α-induced RA-FLS cells by activating HMOX1 to regulate IKKβ/NF-κB pathway

OBJECTIVE

Galuteolin (Galu) is a substance extracted and purified from honeysuckle. The purpose of this study was to explore the effects of Galu on the TNF-α-induced RA-FLS cells (synoviocytes) and reveal its potential molecular mechanism from the perspectives of anti-apoptosis and anti-inflammation.

METHODS

After TNF-α stimulation, cell proliferation of RA-FLS was assessed by CCK-8 assay. TUNEL staining was used to detect the apoptosis. Western blot was used to detect the expressions of Iκκβ, p-p65, p65, p-IκB, IκB, Cleaved-caspase3, Caspase-3, Bcl-2, and Bax. HO-1 were determined by RT-PCR. The contents of pro-inflammatory cytokines IL-1β, IL-6, IL-8, and MMP-1 were determined by ELISA.

RESULTS

Galu significantly suppressed cell proliferation in a dose-dependent manner. Additionally, Galu obviously promotes cell apoptosis rate of RA-FLS cells and elevated the expression levels of HO-1, caspase-3, and Bax, while reducing the expression level of Bcl-2. Furthermore, Galu apparently inhibited the levels of Iκκβ, p-p65, and p-IκB. Moreover, Galu also significantly reduced the levels of pro-inflammatory factors IL-1β, IL-6, IL-8, and MMP-1 in RA-FLS cells.

CONCLUSION

Galuteolin exerts protective effects against TNF-α-induced RA-FLS cells by inhibiting apoptosis and inflammation, which can guide the clinical use of rheumatoid arthritis.

Regulation of Filaggrin, Loricrin, and Involucrin by IL-4, IL-13, IL-17A, IL-22, AHR, and NRF2: Pathogenic Implications in Atopic Dermatitis

Atopic dermatitis (AD) is an eczematous, pruritic skin disorder with extensive barrier dysfunction and elevated interleukin (IL)-4 and IL-13 signatures. The barrier dysfunction correlates with the downregulation of barrier-related molecules such as filaggrin (FLG), loricrin (LOR), and involucrin (IVL). IL-4 and IL-13 potently inhibit the expression of these molecules by activating signal transducer and activator of transcription (STAT)6 and STAT3. In addition to IL-4 and IL-13, IL-22 and IL-17A are probably involved in the barrier dysfunction by inhibiting the expression of these barrier-related molecules. In contrast, natural or medicinal ligands for aryl hydrocarbon receptor (AHR) are potent upregulators of FLG, LOR, and IVL expression. As IL-4, IL-13, IL-22, and IL-17A are all capable of inducing oxidative stress, antioxidative AHR agonists such as coal tar, glyteer, and tapinarof exert particular therapeutic efficacy for AD. These antioxidative AHR ligands are known to activate an antioxidative transcription factor, nuclear factor E2-related factor 2 (NRF2). This article focuses on the mechanisms by which FLG, LOR, and IVL expression is regulated by IL-4, IL-13, IL-22, and IL-17A. The author also summarizes how AHR and NRF2 dual activators exert their beneficial effects in the treatment of AD.

Chloracne and Hyperpigmentation Caused by Exposure to Hazardous Aryl Hydrocarbon Receptor Ligands

Dioxins and dioxin-like compounds are environmental pollutants that are hazardous to human skin. They can be present in contaminated soil, water, and air particles (such as ambient PM_2.5). Exposure to a high concentration of dioxins induces chloracne and hyperpigmentation. These chemicals exert their toxic effects by activating the aryl hydrocarbon receptor (AHR) which is abundantly expressed in skin cells, such as keratinocytes, sebocytes, and melanocytes. Ligation of AHR by dioxins induces exaggerated acceleration of epidermal terminal differentiation (keratinization) and converts sebocytes toward keratinocyte differentiation, which results in chloracne formation. AHR activation potently upregulates melanogenesis in melanocytes by upregulating the expression of melanogenic enzymes, which results in hyperpigmentation. Because AHR-mediated oxidative stress contributes to these hazardous effects, antioxidative agents may be potentially therapeutic for chloracne and hyperpigmentation.

Environmental Stressors on Skin Aging. Mechanistic Insights

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

Lentinan inhibits oxidative stress and inflammatory cytokine production induced by benzo(a)pyrene in human keratinocytes

BACKGROUND

Benzo(a)pyrene, a major environmental pollutant, is known to accelerate skin aging through oxidative stress, increase the production of inflammatory mediators, and cause skin cancer. Lentinan, prepared from Lentinus edodes (Shiitake mushroom), has been reported to exhibit anti-coagulant, anti-viral, anti-cancer, anti-tumor, and anti-coagulant effects. However, the effect of lentinan on human keratinocytes treated with benzo(a)pyrene is unknown.

AIMS

The aim of this study was to explore whether lentinan inhibits benzo(a)pyrene-induced oxidative stress and inflammatory cytokine production in human keratinocytes.

METHODS

We investigated the effect of lentinan on benzo(a)pyrene-induced oxidative stress indicators (malondialdehyde, superoxide dismutase, and glutathione peroxidase) in human immortalized keratinocytes (HaCaT cells). We also assessed the production of inflammatory factors interleukin-8 and chemokine ligand-2 induced by benzo(a)pyrene exposure at both mRNA and protein levels.

RESULTS

Lentinan inhibited oxidative stress induced by benzo(a)pyrene, as shown by the concentration-dependent reduction in reactive oxygen species in HaCaT cells. In addition, malondialdehyde levels were reduced to 53% of those of cells treated with benzo(a)pyrene without lentinan. The activities of superoxide dismutase and glutathione peroxidase were approximately 18- and 2.7-fold higher in benzo(a)pyrene-treated cells with lentinan than in those without lentinan. Moreover, lentinan significantly reduced interleukin-8 and chemokine ligand-2 mRNA and protein levels.

CONCLUSIONS

These findings suggest that lentinan has two biological activities that are potentially useful for managing inflammatory skin diseases or disorders related to oxidative stress induced by benzo(a)pyrene. Therefore, cosmetics containing L edodes have promising dermatological applications, with potential utility in protecting the skin against environmental pollutants.

Salvianolic Acid B Promotes the Survival of Random-Pattern Skin Flaps in Rats by Inducing Autophagy

Random-pattern skin flap transplantation is frequently applied in plastic and reconstructive surgery. However, the distal part of the flap often suffers necrosis due to ischemia. In this study, the effects of salvianolic acid B (Sal B) on flap survival were evaluated, and the underlying mechanisms were investigated. Sal B improved the survival area, reduced tissue edema, and increased the number of microvessels in skin flaps after 7 days, whereas an autophagy inhibitor (3-methyladenine) reversed the Sal B-induced increase in flap viability. In addition, Sal B stimulated angiogenesis, inhibited apoptosis, reduced oxidative stress, and upregulated autophagy in areas of ischemia. Moreover, the effects of Sal B on angiogenesis, apoptosis, and oxidative stress were reversed by autophagy inhibition. Overall, our findings suggest that Sal B has pro-angiogenesis, anti-apoptosis, and anti-oxidative stress effects by stimulating autophagy, which enhances the survival of random-pattern skin flaps.

Therapeutic Agents with AHR Inhibiting and NRF2 Activating Activity for Managing Chloracne

Chloracne is the major skin symptom caused by dioxin intoxication. Dioxin activates the aryl hydrocarbon receptor (AHR)–cytochrome p450 1A1 (CYP1A1) system, generates oxidative stress, and induces hyperkeratinization of keratinocytes and sebocytes leading to chloracne. Nuclear factor-erythroid 2-related factor-2 (NRF2) is a master switch that induces the expression of various antioxidative enzymes, such as heme oxygenase-1. Cinnamaldehyde is an antioxidant phytochemical that inhibits AHR–CYP1A1 signaling and activates the NRF2–antioxidative axis. The cinnamaldehyde-containing Kampo herbal medicine Keishibukuryogan is capable of improving chloracne in Yusho patients who are highly contaminated with dioxin. Agents with dual functions in promoting AHR–CYP1A1 inhibition and NRF2 activation may be useful for managing dioxin-related health hazards.