Nrf2 Activation Provides Atheroprotection in Diabetic Mice Through Concerted Upregulation of Antioxidant, Anti-inflammatory, and Autophagy Mechanisms

Nrf2 Connects Cellular Autophagy and Vascular Senescence in Atherosclerosis: A Mini-Review

Nuclear factor erythroid 2-related factor 2 (Nrf2), a transcriptional factor that maintains intracellular redox equilibrium, modulates the expression of antioxidant genes, scavenger receptors, and cholesterol efflux transporters, all of which contribute significantly to foam cell development and plaque formation. Nrf2 has recently emerged as a key regulator that connects autophagy and vascular senescence in atherosclerosis. Autophagy, a cellular mechanism involved in the breakdown and recycling of damaged proteins and organelles, and cellular senescence, a state of irreversible growth arrest, are both processes implicated in the pathogenesis of atherosclerosis. The intricate interplay of these processes has received increasing attention, shedding light on their cumulative role in driving the development of atherosclerosis. Recent studies have revealed that Nrf2 plays a critical role in mediating autophagy and senescence in atherosclerosis progression. Nrf2 activation promotes autophagy, which increases lipid clearance and prevents the development of foam cells. Meanwhile, the activation of Nrf2 also inhibits cellular senescence by regulating the expression of senescence markers to preserve cellular homeostasis and function and delay the progression of atherosclerosis. This review provides an overview of the molecular mechanisms through which Nrf2 connects cellular autophagy and vascular senescence in atherosclerosis. Understanding these mechanisms can provide insights into potential therapeutic strategies targeting Nrf2 to modulate cellular autophagy and vascular senescence, thereby preventing the progression of atherosclerosis.

Activation of Nrf2 at Critical Windows of Development Alters Tissue-Specific Protein S-Glutathionylation in the Zebrafish (Danio rerio) Embryo

Activation of Nrf2-the master regulator of antioxidative response-at different stages of embryonic development has been shown to result in changes in gene expression, but the tissue-specific and downstream effects of Nrf2 activation during development remain unclear. This work seeks to elucidate the tissue-specific Nrf2 cellular localization and the downstream changes in protein S-glutathionylation during critical windows of zebrafish (Danio rerio) development. Wild-type and mutant zebrafish embryos with a loss-of-function mutation in Nrf2a were treated with two canonical activators, sulforaphane (SFN; 40 µM) or tert-butylhydroquinone (tBHQ; 1 µM), for 6 h at either pharyngula, hatching, or the protruding-mouth stage. Nrf2a protein and S-glutathionylation were visualized in situ using immunohistochemistry. At the hatching stage, Nrf2a protein levels were decreased with SFN, but not tBHQ, exposure. Exposure to both activators, however, decreased downstream S-glutathionylation. Stage- and tissue-specific differences in Nrf2a protein and S-glutathionylation were identified in the pancreatic islet and liver. Protein S-glutathionylation in Nrf2a mutant fish was increased in the liver by both activators, but not the islets, indicating a tissue-specific and Nrf2a-dependent dysregulation. This work demonstrates that critical windows of exposure and Nrf2a activity may influence redox homeostasis and highlights the importance of considering tissue-specific outcomes and sensitivity in developmental redox biology.

Molecular mechanisms and therapeutic potential of natural flavonoids in diabetic nephropathy: Modulation of intracellular developmental signaling pathways

Recognized as a common microvascular complication of diabetes mellitus (DM), diabetic nephropathy (DN) is the principal cause of chronic end-stage renal disease (ESRD). Patients with diabetes have an approximately 25% risk of developing progressive renal disease. The underlying principles of DN control targets the dual outcomes of blood glucose regulation through sodium glucose cotransporter 2 (SGLT 2) blockade and hypertension management through renin-angiotensin-aldosterone inhibition. However, these treatments are ineffective in halting disease progression to kidney failure and cardiovascular comorbidities. Recently, the dysregulation of subcellular signaling pathways has been increasingly implicated in DN pathogenesis. Natural compounds are emerging as effective and side-effect-free therapeutic agents that target intracellular pathways. This narrative review synthesizes recent insights into the dysregulation of maintenance pathways in DN, drawing from animal and human studies. To compile this review, articles reporting DN signaling pathways and their treatment with natural flavonoids were collected from PubMed, Cochrane Library Web of Science, Google Scholar and EMBASE databases since 2000. As therapeutic interventions are frequently based on the results of clinical trials, a brief analysis of data from current phase II and III clinical trials on DN is discussed.

High estrogen induces trans-differentiation of vascular smooth muscle cells to a macrophage-like phenotype resulting in aortic inflammation via inhibiting VHL/HIF1a/KLF4 axis

Estrogen is thought to have a role in slowing down aging and protecting cardiovascular and cognitive function. However, high doses of estrogen are still positively associated with autoimmune diseases and tumors with systemic inflammation. First, we administered exogenous estrogen to female mice for three consecutive months and found that the aorta of mice on estrogen develops inflammatory manifestations similar to Takayasu arteritis (TAK). Then, in vitro estrogen intervention was performed on mouse aortic vascular smooth muscle cells (MOVAS cells). Stimulated by high concentrations of estradiol, MOVAS cells showed decreased expression of contractile phenotypic markers and increased expression of macrophage-like phenotypic markers. This shift was blocked by tamoxifen and Krüppel-like factor 4 (KLF4) inhibitors and enhanced by Von Hippel-Lindau (VHL)/hypoxia-inducible factor-1α (HIF-1α) interaction inhibitors. It suggests that estrogen-targeted regulation of the VHL/HIF-1α/KLF4 axis induces phenotypic transformation of vascular smooth muscle cells (VSMC). In addition, estrogen-regulated phenotypic conversion of VSMC to macrophages is a key mechanism of estrogen-induced vascular inflammation, which justifies the risk of clinical use of estrogen replacement therapy.

Transcription factor Nrf2 activation regulates NETosis, endothelial injury, and kidney disease in myeloperoxidase-positive antineutrophil cytoplasmic antibody-associated vasculitis

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a systemic autoimmune disease pathologically characterized by vascular necrosis with inflammation. During AAV development, activated neutrophils produce reactive oxygen species (ROS), leading to the aberrant formation of neutrophil extracellular traps (NETs) via NETosis and subsequent fibrinoid vascular necrosis. Nuclear factor-erythroid 2-related factor 2 (Nrf2) functions as an intracellular defense system to counteract oxidative stress by providing antioxidant properties. Herein, we explored the role of Nrf2 in the pathogenesis of AAV. The role and mechanism of Nrf2 in ANCA-stimulated neutrophils and subsequent endothelial injury were evaluated in vitro using Nrf2 genetic deletion and Nrf2 activator treatment. In corresponding in vivo studies, the role of Nrf2 in ANCA-transfer AAV and spontaneous AAV murine models was examined. Pharmacological activation of Nrf2 in vitro suppressed ANCA-induced NET formation via the inhibition of ROS. In contrast, NET formation was enhanced in Nrf2-deficient neutrophils. Furthermore, Nrf2 activation protected endothelial cells from ANC-induced NETs-mediated injury. In vivo, Nrf2 activation ameliorated glomerulonephritis in two AAV models by upregulating antioxidants and inhibiting ROS-mediated NETs. Furthermore, Nrf2 activation restrained the expansion of splenic immune cells, including T lymphocytes and limited the infiltration of Th17 cells into the kidney. In contrast, Nrf2 genetic deficiency exacerbated vasculitis in a spontaneous AAV model. Thus, the pathophysiological process in AAV may be downregulated by Nrf2 activation, potentially leading to a new therapeutic strategy by regulating NETosis.

Novel Insight into the Effect of Probiotics in the Regulation of the Most Important Pathways Involved in the Pathogenesis of Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is considered one of the most common disorders worldwide. Although several treatment modalities have been developed, the existing interventions have not yielded the desired results. Therefore, researchers have focused on finding treatment choices with low toxicity and few adverse effects that could control T2DM efficiently. Various types of research on the role of gut microbiota in developing T2DM and its related complications have led to the growing interest in probiotic supplementation. Several properties make these organisms unique in terms of human health, including their low cost, high reliability, and good safety profile. Emerging evidence has demonstrated that three of the most important signaling pathways, including nuclear factor kappa B (NF-κB), phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt), and nuclear factor erythroid 2-related factor 2 (Nrf2), which involved in the pathogenesis of T2DM, play key functions in the effects of probiotics on this disease. Hence, we will focus on the clinical applications of probiotics in the management of T2DM. Then, we will also discuss the roles of the involvement of various probiotics in the regulation of the most important signaling pathways (NF-κB, PI3K/Akt, and Nrf2) involved in the pathogenesis of T2DM.

Combined exposure to lead and microplastics increased risk of glucose metabolism in mice via the Nrf2/NF-κB pathway

The purpose of this study was to explore the effects of combined lead (Pb) and two types of microplastic (MP) (polyvinyl chloride [PVC] and polyethylene [PE]) exposure on glucose metabolism and investigate the role of the nuclear factor erythroid 2-related factor 2 (Nrf2)/nuclear factor-kappa B (NF-κB) signaling pathway in mediating these effects in mice. Adult C57BL/6J mice were randomly divided into four groups: control, Pb (100 mg/L), MPs (containing 10 mg/L PE and PVC), and Pb + MPs, each of which was treated with drinking water. Treatments were conducted for 6 weeks. Co-exposure to Pb + MPs exhibited increase glycosylated serum protein levels, insulin resistance, and damaged glucose tolerance compared with the control mice. Additionally, treatment with Pb + MPs caused more severe damage to hepatocytes than when exposed to them alone concomitantly, exposed to Pb + MPs exhibited improved the levels of interleukin-6, tumor necrosis factor-alpha, and malondialdehyde, but reduced superoxide dismutase, glutathione peroxidase, and catalase assay in livers. Furthermore, they increase the Kelch-like ECH-associated protein 1 (Keap1) and phosphorylated p-NF-κB protein levels but reduced the protein levels of heme oxygenase-1 and Nrf2, as well as increased Keap1 mRNA and Nrf2 mRNA. Co-exposure to Pb + MP impacts glucose metabolism via the Nrf2 /NF-κB pathway.

Advances in Nrf2 Signaling Pathway by Targeted Nanostructured-Based Drug Delivery Systems

Nanotechnology has gained significant interest in various applications, including sensors and therapeutic agents for targeted disease sites. Several pathological consequences, including cancer, Alzheimer's disease, autoimmune diseases, and many others, are mostly driven by inflammation and Nrf2, and its negative regulator, the E3 ligase adaptor Kelch-like ECH-associated protein 1 (Keap1), plays a crucial role in maintaining redox status, the expression of antioxidant genes, and the inflammatory response. Interestingly, tuning the Nrf2/antioxidant response element (ARE) system can affect immune-metabolic mechanisms. Although many phytochemicals and synthetic drugs exhibited potential therapeutic activities, poor aqueous solubility, low bioavailability, poor tissue penetration, and, consequently, poor specific drug targeting, limit their practical use in clinical applications. Also, the therapeutic use of Nrf2 modulators is hampered in clinical applications by the absence of efficient formulation techniques. Therefore, we should explore the engineering of nanotechnology to modulate the inflammatory response via the Nrf2 signaling pathway. This review will initially examine the role of the Nrf2 signaling pathway in inflammation and oxidative stress-related pathologies. Subsequently, we will also review how custom-designed nanoscale materials encapsulating the Nrf2 activators can interact with biological systems and how this interaction can impact the Nrf2 signaling pathway and its potential outcomes, emphasizing inflammation.

A Review of the Potential of Nuclear Factor [Erythroid-Derived 2]-like 2 Activation in Autoimmune Diseases

An autoimmune disease is the consequence of the immune system attacking healthy cells, tissues, and organs by mistake instead of protecting them. Inflammation and oxidative stress (OS) are well-recognized processes occurring in association with acute or chronic impairment of cell homeostasis. The transcription factor Nrf2 (nuclear factor [erythroid-derived 2]-like 2) is of major importance as the defense instrument against OS and alters anti-inflammatory activities related to different pathological states. Researchers have described Nrf2 as a significant regulator of innate immunity. Growing indications suggest that the Nrf2 signaling pathway is deregulated in numerous diseases, including autoimmune disorders. The advantageous outcome of the pharmacological activation of Nrf2 is an essential part of Nrf2-based chemoprevention and intervention in other chronic illnesses, such as neurodegeneration, cardiovascular disease, autoimmune diseases, and chronic kidney and liver disease. Nevertheless, a growing number of investigations have indicated that Nrf2 is already elevated in specific cancer and disease steps, suggesting that the pharmacological agents developed to mitigate the potentially destructive or transformative results associated with the protracted activation of Nrf2 should also be evaluated. The activators of Nrf2 have revealed an improvement in the progress of OS-associated diseases, resulting in immunoregulatory and anti-inflammatory activities; by contrast, the depletion of Nrf2 worsens disease progression. These data strengthen the growing attention to the biological properties of Nrf2 and its possible healing power on diseases. The evidence supporting a correlation between Nrf2 signaling and the most common autoimmune diseases is reviewed here. We focus on the aspects related to the possible effect of Nrf2 activation in ameliorating pathologic conditions based on the role of this regulator of antioxidant genes in the control of inflammation and OS, which are processes related to the progression of autoimmune diseases. Finally, the possibility of Nrf2 activation as a new drug development strategy to target pathogenesis is proposed.

Neuroprotective Effects of Phenolic Antioxidant Tert-butylhydroquinone (tBHQ) in Brain Diseases

Human life and health are gravely threatened by brain diseases. The onset and progression of the illnesses are influenced by a variety of factors, including pathogenic causes, environmental factors, mental issues, etc. According to scientific studies, neuroinflammation and oxidative stress play a significant role in the development and incidence of brain diseases by producing pro-inflammatory cytokines and oxidative tissue damage to induce inflammation and apoptosis. Neuroinflammation, oxidative stress, and oxidative stress-related changes are inseparable factors in the etiology of several brain diseases. Numerous neurodegenerative diseases have undergone substantial research into the therapeutic alternatives that target oxidative stress, the function of oxidative stress, and the possible therapeutic use of antioxidants. Formerly, tBHQ is a synthetic phenolic antioxidant, which has been widely used as a food additive. According to recent researches, tBHQ can suppress the processes that lead to neuroinflammation and oxidative stress, which offers a fresh approach to treating brain diseases. In order to achieve the goal of decreasing inflammation and apoptosis, tBHQ is a specialized nuclear factor erythroid 2-related factor (Nrf2) activator that decreases oxidative stress and enhances antioxidant status by upregulating the Nrf2 gene and reducing nuclear factor kappa-B (NF-κB) activity. This article reviews the effects of tBHQ on neuroinflammation and oxidative stress in recent years and looks into how tBHQ inhibits neuroinflammation and oxidative stress through human, animal, and cell experiments to play a neuroprotective role in Alzheimer's disease (AD), stroke, depression, and Parkinson's disease (PD). It is anticipated that this article will be useful as a reference for upcoming research and the creation of drugs to treat brain diseases.

Lipid-laden foam cells in the pathology of atherosclerosis: shedding light on new therapeutic targets

INTRODUCTION

Lipid-laden foam cells within atherosclerotic plaques are key players in all phases of lesion development including its progression, necrotic core formation, fibrous cap thinning, and eventually plaque rupture. Manipulating foam cell biology is thus an attractive therapeutic strategy at early, middle, and even late stages of atherosclerosis. Traditional therapies have focused on prevention, especially lowering plasma lipid levels. Despite these interventions, atherosclerosis remains a major cause of cardiovascular disease, responsible for the largest numbers of death worldwide.

AREAS COVERED

Foam cells within atherosclerotic plaques are comprised of macrophages, vascular smooth muscle cells, and other cell types which are exposed to high concentrations of lipoproteins accumulating within the subendothelial intimal layer. Macrophage-derived foam cells are particularly well studied and have provided important insights into lipid metabolism and atherogenesis. The contributions of foam cell-based processes are discussed with an emphasis on areas of therapeutic potential and directions for drug development.

EXERT OPINION

As key players in atherosclerosis, foam cells are attractive targets for developing more specific, targeted therapies aimed at resolving atherosclerotic plaques. Recent advances in our understanding of lipid handling within these cells provide insights into how they might be manipulated and clinically translated to better treat atherosclerosis.

Dietary exposure to the food preservative tert-Butylhydroquinone (tBHQ) impairs zebrafish (Danio rerio) survival, growth, organ development, and gene expression in Nrf2a-dependent and independent ways

Tert-Butylhydroquinone (tBHQ), a preservative used to prevent oxidative deterioration of oil, fat, and meat products, has been linked to both chemoprotective and adverse effects. This study investigates the impact of dietary tBHQ consumption on survival, growth parameters, organ development, and gene expression in zebrafish (Danio rerio). As tBHQ activates the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2a), a zebrafish line with a mutation in the DNA-binding domain of Nrf2a was used to identify Nrf2a-dependent vs independent effects. Homozygous Nrf2a wildtype (wt) and mutant (m) larvae were fed a diet containing 5% tBHQ or a control diet. Survival and growth parameters were assessed at 15 days and at 5 months, and samples were collected for RNA sequencing at 5 months. Dietary exposure to tBHQ throughout the larval and juvenile periods negatively impacted growth and survival. RNA-seq analysis found differentially expressed genes related to growth and development and upregulation of several immune system-related pathways. The findings herein demonstrate that dietary tBHQ exposure may impair growth and survival in both Nrf2a dependent and independent manners.

Zinc stabilized Nrf2 by inhibition of HDAC3 in human peripheral blood mononuclear cells

BACKGROUND

The transcription factor Nuclear factor erythroid 2-related factor 2 (Nrf2) induces several detoxifying proteins, which also include NAD(P)H quinone dehydrogenase 1 (NQO1) and heme oxygenase 1 (HO-1). The expression of these Nrf2-regulated proteins is important for the maintenance of the redox homeostasis in cells. The aim of this study was to investigate the effect of tert-butyl-hydrochinone (tBHQ) stimulation on human PBMC under normal condition and zinc depletion, respectively.

METHOD

Human peripheral blood mononuclear cells (PBMC) were treated with the Nrf2 activator tBHQ in combination with zinc to examine a possible correlation between zinc and redox homeostasis. Therefore, mRNA expression of Nrf2 and its downstream molecules NQO1 and HO-1 were investigated, as well as the protein synthesis of these. In addition, the effect of zinc on histone deacetylase 3 (HDAC3), which is a negative regulator for Nrf2 activity, was analyzed.

RESULTS

Either mRNA, protein expression or both of Nrf2, NQO1 and HO-1 are influenced by zinc. The analysis of HDAC3 shows a negative correlation between its activity and increasing zinc concentrations. By inhibiting HDAC3 zinc stabilizes Nrf2.

CONCLUSION

The results indicate that zinc emphasizes the induction of Nrf2 by its activator tBHQ through increasing gene and protein expression. Additionally, zinc supplementation inhibits HDAC3 activity resulting in reduced Keap1 mRNA expression and thereby stabilizing cytoplasmatic Nrf2. These findings suggests that zinc supplementation has beneficial effects on the redox balance in human cells.

Walnut inclusion in a palm oil-based atherogenic diet promotes traits predicting stable atheroma plaque in Apoe-deficient mice

Introduction

The lower rates of cardiovascular disease in Southern Europe could be partially explained by the low prevalence of lipid-rich atheroma plaques. Consumption of certain foods affects the progression and severity of atherosclerosis. We investigated whether the isocaloric inclusion of walnuts within an atherogenic diet prevents phenotypes predicting unstable atheroma plaque in a mouse model of accelerated atherosclerosis.

Methods

Apolipoprotein E-deficient male mice (10-week-old) were randomized to receive a control diet (9.6% of energy as fat, n = 14), a palm oil-based high-fat diet (43% of energy as fat, n = 15), or an isocaloric diet in which part of palm oil was replaced by walnuts in a dose equivalent to 30 g/day in humans (n = 14). All diets contained 0.2% cholesterol.

Results

After 15 weeks of intervention, there were no differences in size and extension in aortic atherosclerosis among groups. Compared to control diet, palm oil-diet induced features predicting unstable atheroma plaque (higher lipid content, necrosis, and calcification), and more advanced lesions (Stary score). Walnut inclusion attenuated these features. Palm oil-based diet also boosted inflammatory aortic storm (increased expression of chemokines, cytokines, inflammasome components, and M1 macrophage phenotype markers) and promoted defective efferocytosis. Such response was not observed in the walnut group. The walnut group's differential activation of nuclear factor kappa B (NF-κB; downregulated) and Nrf2 (upregulated) in the atherosclerotic lesion could explain these findings.

Conclusion

The isocaloric inclusion of walnuts in an unhealthy high-fat diet promotes traits predicting stable advanced atheroma plaque in mid-life mice. This contributes novel evidence for the benefits of walnuts, even in an unhealthy dietary environment.

Nrf2 Deficiency Exacerbated CLP-Induced Pulmonary Injury and Inflammation through Autophagy- and NF-κB/PPARγ-Mediated Macrophage Polarization

The balance between M1 and M2 macrophage polarization is involved in the regulation of pulmonary inflammation. Nuclear factor erythroid-derived 2-like 2 (Nfe2l2, also known as Nrf2), a nuclear transcription factor, is reported to play protective roles in acute lung injury (ALI) and inflammation, and increasing evidence indicates that the protective effects of Nrf2 are closely related to autophagy. This study aimed to explore whether Nrf2 is involved in sepsis-induced acute pulmonary injury and inflammation and in the role of macrophage polarization in the process. In the present study, sepsis patients, an Nrf2 knockout mouse that underwent cecal ligation and puncture (CLP), and lipopolysaccharide (LPS)-treated macrophage cell lines were employed to investigate the potential functions of Nrf2 in sepsis-induced lung injury and the underlying mechanisms. Clinical studies showed that the NRF2 mRNA level was inversely correlated with pulmonary inflammation and disease severity in patients with sepsis. Analyses in a CLP-treated Nrf2 knockout mouse model indicated that an Nrf2 deficiency promoted a CLP-induced increase in M1 macrophage polarization and apoptosis and inhibited CLP-induced upregulation of the autophagy level in lung tissues. Experiments in RAW264.7 cells revealed that Nrf2 overexpression inhibited M1 macrophage polarization but promoted M2 macrophage polarization by improving the autophagy, and Nrf2 overexpression promoted PPARγ but inhibited NF-κB nuclear translocation. In conclusion, these results indicate that Nrf2 plays a protective role in sepsis-induced pulmonary injury and inflammation through the regulation of autophagy- and NF-κB/PPARγ-mediated macrophage polarization.

Fenugreek Seed Galactomannan Aqueous and Extract Protects against Diabetic Nephropathy and Liver Damage by Targeting NF-κB and Keap1/Nrf2 Axis

This investigation was conducted to test the potential of the galactomannan (F-GAL) and aqueous extract (FS-AE) of the Fenugreek seed aqueous to prevent liver and kidney damage extracts in streptozotocin (STZ)-induced T1DM in rats. Non-diabetic and diabetic rats received the normal saline as a vehicle or were treated with FS-EA or F-GAL at a final concentration of 500 mg/kg/each. Treatments with both drugs reduced fasting hyperglycemia and improved serum and hepatic lipid profiles in the control and diabetic rats. Additionally, F-GAL and FS-AE attenuated the associated reduction in the mass and structure of the islets of Langerhans in diabetic rats and improved the structure of the kidneys and livers. In association, they also reduced the generation of reactive oxygen species (ROS), lipid peroxides, factor (TNF-α), interleukin-6 (IL-6), and nuclear levels of NF-κB p65, and improved serum levels of ALT, AST, albumin, and creatinine. However, both treatments increased hepatic and renal superoxide dismutase (SOD) in the livers and kidneys of both the control and diabetic-treated rats, which coincided with a significant increase in transcription, translation, and nuclear localization of Nrf2. In conclusion, FS-AE and F-GAL are effective therapeutic options that may afford a possible treatment for T1DM by attenuating pancreatic damage, hyperglycemia, hyperlipidemia, and hepatic and renal damage.

A Dual-Acting Nitric Oxide Donor and Phosphodiesterase 5 Inhibitor Activates Autophagy in Primary Skin Fibroblasts

Wound healing pathologies are an increasing problem in ageing societies. Chronic, non-healing wounds, which cause high morbidity and severely reduce the quality of life of affected individuals, are frequently observed in aged individuals and people suffering from diseases affected by the Western lifestyle, such as diabetes. Causal treatments that support proper wound healing are still scarce. Here, we performed expression proteomics to study the effects of the small molecule TOP-N53 on primary human skin fibroblasts and keratinocytes. TOP-N53 is a dual-acting nitric oxide donor and phosphodiesterase-5 inhibitor increasing cGMP levels to support proper wound healing. In contrast to keratinocytes, which did not exhibit global proteome alterations, TOP-N53 had profound effects on the proteome of skin fibroblasts. In fibroblasts, TOP-N53 activated the cytoprotective, lysosomal degradation pathway autophagy and induced the expression of the selective autophagy receptor p62/SQSTM1. Thus, activation of autophagy might in part be responsible for beneficial effects of TOP-N53.

Endothelial Dysfunction in the Context of Blood–Brain Barrier Modeling

Here, we discuss pathophysiological approaches to the defining of endothelial dysfunction criteria (i.e., endothelial activation, impaired endothelial mechanotransduction, endothelial-to-mesenchymal transition, reduced nitric oxide release, compromised endothelial integrity, and loss of anti-thrombogenic properties) in different in vitro and in vivo models. The canonical definition of endothelial dysfunction includes insufficient production of vasodilators, pro-thrombotic and pro-inflammatory activation of endothelial cells, and pathologically increased endothelial permeability. Among the clinical consequences of endothelial dysfunction are arterial hypertension, macro- and microangiopathy, and microalbuminuria. We propose to extend the definition of endothelial dysfunction by adding altered endothelial mechanotransduction and endothelial-to-mesenchymal transition to its criteria. Albeit interleukin-6, interleukin-8, and MCP-1/CCL2 dictate the pathogenic paracrine effects of dysfunctional endothelial cells and are therefore reliable endothelial dysfunction biomarkers in vitro, they are non-specific for endothelial cells and cannot be used for the diagnostics of endothelial dysfunction in vivo. Conceptual improvements in the existing methods to model endothelial dysfunction, specifically, in relation to the blood–brain barrier, include endothelial cell culturing under pulsatile flow, collagen IV coating of flow chambers, and endothelial lysate collection from the blood vessels of laboratory animals in situ for the subsequent gene and protein expression profiling. Combined with the simulation of paracrine effects by using conditioned medium from dysfunctional endothelial cells, these flow-sensitive models have a high physiological relevance, bringing the experimental conditions to the physiological scenario.

High Level of Uric Acid Promotes Atherosclerosis by Targeting NRF2-Mediated Autophagy Dysfunction and Ferroptosis

Atherosclerotic vascular disease (ASVD) is the leading cause of death worldwide. Hyperuricemia is the fourth risk factor for atherosclerosis after hypertension, diabetes, and hyperlipidemia. The mechanism of hyperuricemia affecting the occurrence and development of atherosclerosis has not been fully elucidated. Mononuclear macrophages play critical roles in all stages of atherosclerosis. Studies have confirmed that both hyperuricemia and ferroptosis promote atherosclerosis, but whether high level of uric acid (HUA) promotes atherosclerosis by regulating ferroptosis in macrophages remains unclear. We found that HUA significantly promoted the development of atherosclerotic plaque and downregulated the protein level of the NRF2/SLC7A11/GPX4 signaling pathway in ApoE−/− mice. Next, we evaluated the effect of HUA and ferroptosis inhibitor ferrostatin-1 (Fer-1) treatment on the formation of macrophage-derived foam cells. HUA promoted the formation of foam cells, decreased cell viability, and increased iron accumulation and lipid peroxidation in macrophages treated with oxidized low-density lipoprotein (oxLDL); these effects were reversed by Fer-1 treatment. Mechanistically, HUA significantly inhibited autophagy and the protein level of the NRF2/SLC7A11/GPX4 signaling pathway. Fer-1 activated autophagy and upregulated the level of ferroptosis-associated proteins. Moreover, an NRF2 inducer (tertbutyl hydroquinone (TBHQ)) and autophagy activator (rapamycin (RAPA)) could reverse the inhibitory effect of HUA on foam cell survival. Our results suggest that HUA-induced ferroptosis of macrophages is involved in the formation of atherosclerotic plaques. More importantly, enhancing autophagy and inhibiting ferroptosis by activating NRF2 may alleviate HUA-induced atherosclerosis. These findings might contribute to a deeper understanding of the role of HUA in the pathogenesis of atherosclerosis and provide a therapeutic target for ASVD associated with hyperuricemia.

Antioxidant Response Activating nanoParticles (ARAPas) localize to atherosclerotic plaque and locally activate the Nrf2 pathway

Atherosclerotic disease is the leading cause of death world-wide with few novel therapies available despite the ongoing health burden. Redox dysfunction is a well-established driver of atherosclerotic progression; however, the clinical translation of redox-based therapies is lacking. One of the challenges facing redox-based therapies is their targeted delivery to cellular domains of redox dysregulation. In the current study, we sought to develop Antioxidant Response Activating nanoParticles (ARAPas), encapsulating redox-based interventions, that exploit macrophage biology and the dysfunctional endothelium in order to selectively accumulate in atherosclerotic plaque. We employed flash nanoprecipitation (FNP) to synthesize bio-compatible polymeric nanoparticles encapsulating the hydrophobic Nrf2 activator drug, CDDO-Methyl (CDDOMe-ARAPas). Nuclear factor erythroid 2-related factor 2 (Nrf2)-activators are a promising class of redox-active drug molecules whereby activation of Nrf2 results in the expression of several antioxidant and cyto-protective enzymes that can be athero-protective. In this study, we characterize the physicochemical properties of CDDOMe-ARAPas as well as confirm their in vitro internalization by murine macrophages. Drug release of CDDOMe was determined by Nrf2-driven GFP fluorescence. Moreover, we show that these CDDOMe-ARAPas exert anti-inflammatory effects in classically activated macrophages. Finally, we show that CDDOMe-ARAPas selectively accumulate in atherosclerotic plaque of two widely-used murine models of atherosclerosis: ApoE^-/- and LDLr^-/- mice, and are capable of increasing gene expression of Nrf2-transcriptional targets in the atherosclerotic aortic arch. Future work will assess the therapeutic efficacy of intra-plaque Nrf2 activation with CDDOMe-ARAPas to inhibit atherosclerotic plaque progression. Overall, our present studies underline that targeting of atherosclerotic plaque is an effective means to enhance delivery of redox-based interventions.

Tert-Butylhydroquinone alleviates insulin resistance and liver steatosis in diabetes

OBJECTIVES:

This work aimed to determine tert-Butylhydroquinone (TBHQ)'s effects on insulin resistance (IR) and liver steatosis in diabetic animals and to explore the underpinning mechanisms.

MATERIALS AND METHODS:

Male ApoE^-/-mice underwent streptozocin (STZ) administration while receiving a sucrose/fat-rich diet for type 2 diabetes mellitus (T2DM) establishment. This was followed by a 6-week TBHQ administration. Body weight, fasting (FBG) and postprandial (PBG) blood glucose amounts, and insulin concentrations were measured, and the oral glucose tolerance test (OGTT) was carried out. Hematoxylin and eosin (H and E) staining and immunoblot were carried out for assessing histology and protein amounts in the liver tissue samples. In addition, cultured HepG2 cells were administered HClO and insulin for IR induction, and immunoblot was carried out for protein evaluation. Finally, the cells were stained with the Hoechst dye for apoptosis evaluation.

RESULTS:

The model animals showed T2DM signs, and TBHQ decreased FBG, ameliorated glucose tolerance and reduced liver steatosis in these animals. In addition, TBHQ markedly upregulated AMPKα2, GLUT4 and GSK3 β, as well as phosphorylated PI3K and AKT in the liver of mice with T2DM. In agreement, TBHQ decreased HClO-and insulin-related IR in cells and suppressed apoptosis through AMPKα2/PI3K/AKT signaling.

CONCLUSIONS:

TBHQ alleviates IR and liver steatosis in a mouse model of T2DM likely through AMPKα2/PI3K/AKT signaling.

Effect of autophagy on ferroptosis in foam cells via Nrf2

The progression of atherosclerotic plaque is accelerated by death of foam cells during the development of the plaque. There are several forms of foam cell death, such as autophagy and ferroptosis forms of cell death together are commonly predominant. Therefore, it is particularly important to study the crosstalk between various forms of cell death in atheroscler and ferroptosis. Although there is a dominant form of cell death that plays a role in the disease, motic plaques. Nuclear factor NF-E2-related factor (Nrf2) has been considered as a major regulator of antioxidant in previous studies, but recent studies have revealed that insufficient cellular autophagy can turn off Nrf2-mediated antioxidant defense while initiating Nrf2-manipulated iron deposition and lipid peroxidation, leading to the development of iron ferroptosis. The present experiment aimed to explain the regulatory mechanism between autophagy and ferroptosis through Nrf2. In this experiment, differentiated human THP-1 macrophages were used, which were treated with ox-LDL into foam cells with the addition of the autophagy inhibitor chloroquine (CQ), the inhibitor of Nrf2 (ML385), the promoter of Nrf2 (t-BHQ), and the inhibitor of ferroptosis (Liproxstatin-1), and the expression levels of autophagy-related proteins p62 and LC3, as well as Nrf2 and ferroptosis-related proteins xCT and GPX4 by WB, foam cell survival by CCK8, and intracellular reactive oxygen levels by Flow cytometry analysis and fluorescence microscopy. The effect of autophagy through Nrf2 on ferroptosis in foam cells was determined. The results revealed that insufficient autophagy in CQ-induced foam cells could lead to foam cell death in atherosclerotic plaques, and the cause of cell death was that insufficient autophagy in foam cells turned off the positive effect of Nfr2 antioxidant, initiated the negative effect of Nrf2 to promote intracellular reactive oxygen species production, and this negative effect promoted ferroptosis in foam cells.

A critical review on the health benefits of fish consumption and its bioactive constituents

As one of food sources, fish provides sufficient nutrition to human. Diverse nutrients in fish make fish an important nutrient source available easily across the globe. Fish is proven to possess several health benefits, such as anti-oxidation, anti-inflammation, wound healing, neuroprotection, cardioprotection, and hepatoprotection properties. Fish proteins, such as immunoglobins, act as defense agents against viral and bacterial infections and prevent protein-calorie malnutrition. Besides, fish oil constituents, such as polyunsaturated fatty acids (PUFAs), regulate various signaling pathways, such as nuclear factor kappa B pathway, Toll-like receptor pathway, transforming growth factor-β (TGF-β) pathway, and peroxisome proliferators activated receptor (PPAR) pathways. In this review, the literature about health benefits of fish consumption are accumulated from PubMed, Google Scholar, Scopus, and the mechanistic action of health benefits are summarized. Fish consumption at least twice per week as part of a healthy diet is beneficial for a healthy heart. More advances in this field could pose fish as a major nutrients source of foods.

Nrf2 Activation Is Involved in Cyclic Mechanical Stress-Stimulated Osteogenic Differentiation in Periodontal Ligament Stem Cells via PI3K/Akt Signaling and HO1-SOD2 Interaction

Nuclear factor erythroid-2-related factor-2 (Nrf2), the major transcriptional regulator in antioxidant response and cellular defense, had the vital effect on regulating osteogenic differentiation. Our previous study revealed that Nrf2 activation was involved in cyclic mechanical stress-stimulated osteogenic differentiation in the human periodontal ligament stem cells (PDLSCs). However, the mechanisms of Nrf2 underlying this process remained unclear. The goal of the study was to explore the mechanisms of Nrf2 in PDLSCs during cyclic mechanical stress-stimulated osteogenic differentiation via the tandem mass tag (TMT)-based liquid chromatography tandem-mass spectrometry (LC-MS/MS) analysis. And we applied tert-Butylhydroquinone (t-BHQ), the Nrf2 activator, to the orthodontic rats and detected the expression levels of the osteogenesis markers by immunohistochemistry (IHC) staining. Our results showed that Nrf2 activation in PDLSCs was involved in cyclic mechanical stress-stimulated osteogenic differentiation via phosphoinositide 3 kinase (PI3K)/protein kinase B (Akt) pathway. The protein-protein interaction between Akt and Nrf2 was detected. And the protein-protein interaction between heme oxygenase 1 (HO1) and superoxide dismutase 2 (SOD2), the downstream antioxidants of Nrf2, was associated with cyclic mechanical stress-stimulated osteogenic differentiation. T-BHQ enhanced the expression levels of the osteogenesis markers in orthodontic rats. Nrf2 might possess the potential to be a feasible molecular target in orthodontics.

Tert-butylhydroquinone attenuates osteoarthritis by protecting chondrocytes and inhibiting macrophage polarization

Aims

Tert-butylhydroquinone (tBHQ) has been identified as an inhibitor of oxidative stress-induced injury and apoptosis in human neural stem cells. However, the role of tBHQ in osteoarthritis (OA) is unclear. This study was carried out to investigate the role of tBHQ in OA.

Methods

OA animal model was induced by destabilization of the medial meniscus (DMM). Different concentrations of tBHQ (25 and 50 mg/kg) were intraperitoneally injected in ten-week-old female mice. Chondrocytes were isolated from articular cartilage of mice and treated with 5 ng/ml lipopolysaccharide (LPS) or 10 ng/ml interleukin 1 beta (IL-1β) for 24 hours, and then treated with different concentrations of tBHQ (10, 20, and 40 μM) for 12 hours. The expression levels of malondialdehyde (MDA) and superoxide dismutase (SOD) in blood were measured. The expression levels of interleukin 6 (IL-6), IL-1β, and tumour necrosis factor alpha (TNF-α) leptin in plasma were measured using enzyme-linked immunoabsorbent assay (ELISA) kits. The expression of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and mitogen-activated protein kinase (MAPK) signalling pathway proteins, and macrophage repolarization-related markers, were detected by western blot.

Results

Tert-butylhydroquinone significantly attenuated cartilage destruction in DMM-induced mice in vivo. It demonstrated clear evidence of inhibiting IL-1β-induced chondrocyte apoptosis, inflammation, and differentiation defect in vitro. Meanwhile, tBHQ inhibited LPS-induced activation of NF-κB and MAPK signalling pathways, and also inhibited LPS-induced reactive oxygen species production and macrophages repolarization in vitro.

Conclusion

Taken together, tBHQ might be a potential therapeutic strategy for protecting against OA development.

Cite this article: Bone Joint Res 2021;10(11):704–713.

Berberine Reduces Renal Cell Pyroptosis in Golden Hamsters with Diabetic Nephropathy through the Nrf2-NLRP3-Caspase-1-GSDMD Pathway

Objective. To observe the effect of berberine (BBR) on kidney cell pyroptosis in golden hamsters with diabetic nephropathy (DN) and to explore the molecular mechanism of its renal protection. Methods. Fifty clean-grade male golden hamsters were randomly divided into a control group (10) and a model building group (40). The DN model was established by high-sugar and high-fat feeding and injection of a small amount of STZ. After successful establishment of the model, they were randomly divided into a model group, western medicine group, and berberine high- and low-dose groups. The western medicine group was given irbesartan 13.5 mg/kg, and the berberine high- and low-dose groups were given BBR 200 mg/kg and 100 mg/kg, respectively, for 8 consecutive weeks. An automatic biochemical analyser was used to measure blood glucose, blood lipids, kidney function, MDA, and other indicators; radioimmunoassay was used to assess serum insulin; enzyme-linked immunosorbent assay (ELISA) was used to quantify IL-1β, IL-6, IL-18, TNF-α; HE, PAS, and Masson staining were used to observe kidney pathological tissue morphology; western blot and real-time fluorescent quantitative PCR were used to assess protein and mRNA expression of molecules, such as Nrf2, NLRP3, Caspase-1, and GSDMD; and TUNEL staining was used to detect DNA damage. SPSS statistical software was used for the data analysis. Results. The kidney tissues of golden hamsters in the control group were normal; Nrf2 was highly expressed, serum MDA level was low, NLRP3 expression in kidney tissue was not obvious, Caspase-1 and GSDMD were weakly expressed, and only a few TUNEL-positive cells were observed. Compared with the control group, the golden hamsters in the model group had obvious renal pathological damage; blood glucose, blood lipids, renal function-related indexes, insulin, and inflammatory factors IL-1β, IL-6, IL-18, and TNF-α were increased ( $P<0.05$ ); NLRP3, Caspase-1, and GSDMD expression was increased; Nrf2 expression was decreased; MDA level was increased ( $P<0.05$ ); and the number of TUNEL-positive cells was increased. Compared with the model group, the pathological morphology of the kidney tissue of golden hamsters in the three treatment groups was significantly improved; blood glucose, blood lipids, renal function, and the expression of inflammatory factors IL-1β and IL-6 were reduced ( $P<0.05$ ); NLRP3, Caspase-1, GSDMD, and other molecular proteins and mRNA expression were decreased; Nrf2 expression was increased; MDA level was decreased ( $P<0.05$ ); and the number of TUNEL-positive cells was decreased. Conclusion. DN golden hamster kidney NLRP3-Caspase-1-GSDMD signalling was enhanced. BBR can reduce oxidative stress damage by regulating antioxidative Nrf2 and then regulating NLRP3-Caspase-1-GSDMD signalling to inhibit pyroptosis, antagonizing DN inflammation-induced damage.

Mechanisms of Kidney Cell Pyroptosis in Chronic Kidney Disease and the Effects of Traditional Chinese Medicine

Chronic kidney disease (CKD) is a major public health issue that is highly prevalent worldwide. Pyroptosis is an important pathological mechanism underlying kidney cell damage in CKD and is associated with the classic caspase-1-mediated pathway and nonclassic caspase-4/5/11-mediated pathway. The NLRP3-caspase-1-GSDMD signaling pathway is the key mechanism of kidney cell pyroptosis in CKD, and noncoding RNAs such as lncRNAs and miRNAs are important regulators of kidney cell pyroptosis in CKD. In addition, the NLRP1/AIM2-caspase-1-GSDMD and caspase-3-GSDME signaling pathways have also been shown to mediate kidney cell pyroptosis. Traditional Chinese medicine (TCM) and extracts can interfere with the occurrence and development of kidney cell pyroptosis in CKD by inhibiting the NLRP3 signaling pathway and oxidative stress, activating Nrf-2 signaling, protecting mitochondrial integrity, regulating AMPK signaling, and regulating TXNIP/NLRP3 axis, which have become increasingly prominent. It is critical to explore the effects of TCM on kidney cell pyroptosis in CKD and its mechanisms to identify targets and develop new and effective drugs.

Tertiary butylhydroquinone alleviated liver steatosis and increased cell survival via β-arrestin-2/PI3K/AKT pathway

OBJECTIVES

This study aimed to evaluate the effects and the underlying mechanisms of tertiary butylhydroquinone (TBHQ) on diabetic liver steatosis and cell survival.

MATERIALS AND METHODS

We performed streptozocin injection and used a high-sugar-high-fat diet for mice to develop an animal model of type 2 diabetes mellitus (T2DM). Bodyweight, blood glucose levels, and content of insulin were measured on all of the mice. The liver tissues were observed by hematoxylin-eosin staining. Protein levels of the liver were measured by Western blot analysis in mice. Primary hepatocytes were induced by hypochlorous acid (HClO) and insulin to form insulin resistance (IR). Primary hepatocyte apoptosis was observed by Hoechst staining. The PI3K/AKT signaling pathway and β-arrestin-2 factor were evaluated by Western blot assay.

RESULTS

TBHQ reduced the blood glucose level and content of insulin in serum, increased body weight, and effectively alleviated liver steatosis in diabetic mice. TBHQ significantly up-regulated the expression of p-PI3K, p-AKT, GLUT4, GSK3β, and β-arrestin-2 in the liver of diabetic mice. Cell experiments confirmed that TBHQ increased the survival ability of primary hepatocytes, and TBHQ improved the expression of p-PI3K, p-AKT, GLUT4, and GSK3β by activating β-arrestin-2 in primary hepatocytes.

CONCLUSION

TBHQ could alleviate liver steatosis and increase cell survival, and the mechanism is due in part to β-arrestin-2 activation.

The potential role of Keap1-Nrf2 pathway in the pathogenesis of Alzheimer's disease, type 2 diabetes, and type 2 diabetes-related Alzheimer's disease

Kelch-like ECH associated-protein 1 (Keap1)-nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway is thought to be the key regulatory process defensing oxidative stress in multiple organs. Type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD) are both serious global health problems with high prevalence. A growing number of literatures have suggested a possible link between Keap1-Nrf2 signaling pathway and the pathological changes of T2DM, AD as well as T2DM-related AD. The current review mainly discusses how the damaged Keap1-Nrf2 signaling pathway leads to dysregulated redox molecular signaling, which may contribute to the pathogenesis of AD and T2DM-related cognitive dysfunction, as well as some compounds targeting this pathway. The further exploration of the mechanisms of this pathway could provide novel therapeutic strategies to improve cognitive function, through restoration of expression or translocation of Nrf2 and scavenging excessive free radicals.

Protective Effect of Yi Shen Pai Du Formula against Diabetic Kidney Injury via Inhibition of Oxidative Stress, Inflammation, and Epithelial-to-Mesenchymal Transition in db/db Mice

OBJECTIVE

Diabetic kidney disease (DKD) is one of the most common chronic microvascular complications of diabetes; however, there remains a lack of effective therapeutic strategies. Yi Shen Pai Du Formula (YSPDF), a traditional Chinese medicine preparation, has been clinically used in treating chronic kidney disease (CKD) for more than 20 years. However, whether YSPDF has a therapeutic effect on DKD has not been studied.

METHODS

This study was conducted to investigate the effect of YSPDF administration on db/db mice, a model of type 2 diabetes that develops DKD, and reveal its underlying mechanism of action through a high glucose- (HG-) induced renal injury cell model.

RESULTS

We found that YSPDF significantly improved numerous biochemical parameters (fasting blood glucose, serum creatinine, blood urea nitrogen, 24 h urine total protein, total cholesterol, and total triglycerides) and ameliorated the abnormal histology and fibrosis of renal tissue. Moreover, the status of oxidative stress and levels of inflammatory cytokines (TNF-α, IL-6, IL-1β, and MCP-1) were markedly inhibited by YSPDF treatment. YSPDF treatment significantly mitigated renal fibrosis, with evidence suggesting that this was by inhibiting epithelial-to-mesenchymal transition (EMT) via suppression of the TGF-β1/Smad pathway. Interestingly, the expression of Nrf2, HO-1, and NQO1, proteins known to be associated with oxidative stress, were significantly increased upon administration of YSPDF. The levels of NLRP3 inflammasome proteins, including NLRP3, ASC, caspase-1, and cleaved caspase-1 were decreased in the YSPDF-treated group. Cell experiments showed that YSPDF inhibited EMT and the NLRP3 inflammasome in HG-exposed HK-2 cells, possibly via activation of Nrf2.

CONCLUSION

Our study indicates that YSPDF may ameliorate renal damage in db/db mice via inhibition of oxidative stress, inflammation, and EMT, with the mechanism potentially being related to the activation of the Nrf2 pathway.

The intervention of tert-butylhydroquinone protects ethanol-induced gastric ulcer in type II diabetic rats: the role of Nrf2 pathway

Ethanol consumption increases the prevalence of gastric ulcer (GU) in rats with type II diabetes (T2D). Induction of GU by absolute ethanol (5 mL/kg or 3.94 g/kg) in the animal model resembles human ulcer characteristics. The aim was to investigate the role of the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway in the treatment of GU in diabetic condition. The rats were exposed to absolute ethanol 1 h before sacrifice and T2D was induced by combined exposure of high-fat diet and low dose streptozotocin. Pretreatment of tert-butylhydroquinone (tBHQ) (25 and 50 mg/kg), metformin (500 mg/kg), and omeprazole (20 mg/kg) were given once daily for last three consecutive weeks. In ethanol-exposed diabetic rats, pretreatment with tBHQ, omeprazole, and metformin reduced gastric mucosal lesion, ulcer index, histological alterations, malondialdehyde level, and apoptosis. Furthermore, the intervention of tBHQ, omeprazole, and metformin improved the integrity of the stomach mucosa, glutathione, gastric pH, collagen, and goblet cells. tBHQ treatment improved ethanol-induced alterations of Nrf2, catalase, heat shock protein 70 (HSP70), NF-κB, and endothelin-1 expressions in diabetic rats. In diabetic conditions, the incidence of GU is increased due to elevated levels of reactive oxygen species, inflammatory mediators, depleted levels of cellular antioxidants, and altered gastric parameters. The tBHQ intervention could be a rational strategy to protect these changes.

Regulatory Role of Nrf2 Signaling Pathway in Wound Healing Process

Wound healing involves a series of cellular events in damaged cells and tissues initiated with hemostasis and finally culminating with the formation of a fibrin clot. However, delay in the normal wound healing process during pathological conditions due to reactive oxygen species, inflammation and immune suppression at the wound site represents a medical challenge. So far, many therapeutic strategies have been developed to improve cellular homeostasis and chronic wounds in order to accelerate wound repair. In this context, the role of Nuclear factor erythroid 2-related factor 2 (Nrf2) during the wound healing process has been a stimulating research topic for therapeutic perspectives. Nrf2 is the main regulator of intracellular redox homeostasis. It increases cytoprotective gene expression and the antioxidant capacity of mammalian cells. It has been reported that some bioactive compounds attenuate cellular stress and thus accelerate cell proliferation, neovascularization and repair of damaged tissues by promoting Nrf2 activation. This review highlights the importance of the Nrf2 signaling pathway in wound healing strategies and the role of bioactive compounds that support wound repair through the modulation of this crucial transcription factor.

Nrf2 activation is involved in osteogenic differentiation of periodontal ligament stem cells under cyclic mechanical stretch

During orthodontic treatment, mechanical stretch serves a crucial function in osteogenic differentiation of periodontal ligament stem cells (PDLSCs). Up-regulated reactive oxygen species (ROS) level is a result of cyclic mechanical stretch in many cell types. Nuclear factor erythroid-2-related factor-2 (Nrf2) is a master regulator in various antioxidants expression. However, it is not known whether cyclic mechanical stretch could induce the ROS generation in PDLSCs and whether Nrf2 participated in this process. The present study was aimed to investigate the role of Nrf2 in PDLSCs under cyclic mechanical stretch. Our results showed that cyclic mechanical stretch increased ROS level and the nuclear accumulation of Nrf2 during osteoblast differentiation. Knocking down Nrf2 by siRNA transfection increased ROS formation and suppressed osteogenic differentiation in PDLSCs. T-BHQ, a Nrf2 activator, promoted the osteogenic differentiation in PDLSCs under cyclic mechanical stretch, and improved the microstructure of alveolar bone during orthodontic tooth movement in rats by employing micro-CT system. Taken together, Nrf2 activation was involved in osteogenic differentiation under cyclic mechanical stretch in PDLSCs. T-BHQ could promote the osteogenic differentiation in vitro and in vivo, suggesting a promising option for the remodeling of the alveolar bone during orthodontic tooth movement.

Nuclear Factor Erythroid 2 Related Factor 2 Activator JC-5411 Inhibits Atherosclerosis Through Suppression of Inflammation and Regulation of Lipid Metabolism

Phenethyl isothiocyanate is widely present in cruciferous vegetables with multiple biological effects. Here we reported the antiatherogenic effects and the underlying mechanisms of JC-5411 (Phenethyl isothiocyanate formulation) in vitro and in vivo. Luciferase reporter assay showed that JC-5411 increased the activity of nuclear factor erythroid 2-related factor 2 (Nrf2) and antioxidant response element (ARE). JC-5411 treatment significantly increased the protein expression of Nrf2 and its downstream target gene hemeoxygenase 1 (HO-1) in liver of apolipoprotein E deficient (ApoE^−/−) mice. Importantly, JC-5411 treatment significantly reduced atherosclerotic plaque area in both en face aorta and aortic sinus when compared with model group in WD induced ApoE^−/− mice. JC-5411 obviously decreased proinflammatory factors’ levels in serum of ApoE^−/− mice, LPS stimulated macrophages and TNFα induced endothelial cells, respectively. JC-5411 significantly decreased the levels of total cholesterol (TC) and triglyceride (TG) in both serum and liver of ApoE^−/− mice and hyperlipidemic golden hamsters. Mechanism studies showed that JC-5411 exerted anti-inflammatory effect through activating Nrf2 signaling and inhibiting NF-κB and NLRP3 inflammasome pathway. JC-5411 exerted regulating lipid metabolism effect through increasing cholesterol transfer proteins (ABCA1 and LDLR) expression, regulating fatty acids synthesis related genes (p-ACC, SCD1 and FAS), and increasing fatty acids β-oxidation (CPT1A) in vivo. Furthermore, JC-5411 treatment had a favorable antioxidant effect in ApoE^−/− mice by increasing the antioxidant related genes expression. Taken together, we conclude that JC-5411 as a Nrf2 activator has anti-inflammatory, rebalancing lipid metabolism, and antioxidant effects, which makes it as a potential therapeutic agent against atherosclerosis.

Tert-butylhydroquinone mitigates Carbon Tetrachloride induced Hepatic Injury in mice

Tert-butylhydroquinone (tBHQ) is an antioxidant compound that exhibits cytoprotective effect in many tissues under pathological condition. However, its role in carbon tetrachloride (CCL4) induced liver injury is still unclear. Here we established a carbon tetrachloride induced hepatic injury model in mice to determine whether tBHQ can mitigate CCL4 induced liver damage. In our study, we found tBHQ exhibited protective effects in CCL4 treated mice model. TBHQ markedly improved hepatic function and decreased hepatic histopathological damage in vivo. In addition, tBHQ reduced levels of pro-inflammatory cytokines in mice model. Moreover, tBHQ mitigated apoptosis of hepatocytes, oxidative stress and lipid peroxidation in vivo and in vitro. We also found the possible mechanism of protective effects of tBHQ was associated with activation of Nrf2/ heme oxygenase-1 (HO-1) pathway. In conclusion, our study revealed tBHQ can be a potential therapeutic drug in treatment of acute hepatic injury.

Protective role of NRF2 in macrovascular complications of diabetes

Macrovascular complications develop in over a half of the diabetic individuals, resulting in high morbidity and mortality. This poses a severe threat to public health and a heavy burden to social economy. It is therefore important to develop effective approaches to prevent or slow down the pathogenesis and progression of macrovascular complications of diabetes (MCD). Oxidative stress is a major contributor to MCD. Nuclear factor (erythroid‐derived 2)‐like 2 (NRF2) governs cellular antioxidant defence system by activating the transcription of various antioxidant genes, combating diabetes‐induced oxidative stress. Accumulating experimental evidence has demonstrated that NRF2 activation protects against MCD. Structural inhibition of Kelch‐like ECH‐associated protein 1 (KEAP1) is a canonical way to activate NRF2. More recently, novel approaches, such as activation of the Nfe2l2 gene transcription, decreasing KEAP1 protein level by microRNA‐induced degradation of Keap1 mRNA, prevention of proteasomal degradation of NRF2 protein and modulation of other upstream regulators of NRF2, have emerged in prevention of MCD. This review provides a brief introduction of the pathophysiology of MCD and the role of oxidative stress in the pathogenesis of MCD. By reviewing previous work on the activation of NRF2 in MCD, we summarize strategies to activate NRF2, providing clues for future intervention of MCD. Controversies over NRF2 activation and future perspectives are also provided in this review.

Diabetic Kidney Disease: Challenges, Advances, and Opportunities

BACKGROUND

Diabetic kidney disease (DKD) is the most common cause of the end-stage renal disease (ESRD). Regardless of intensive treatments with hyperglycemic control, blood pressure control, and the use of renin-angiotensin system blockades, the prevalence of DKD remains high. Recent studies suggest that the spectrum of DKD has been changed and many progresses have been made to develop new treatments for DKD. Therefore, it is time to perform a systemic review on the new developments in the field of DKD.

SUMMARY

Although the classic clinical presentation of DKD is characterized by a slow progression from microalbuminuria to macroalbuminuria and by a hyperfiltration at the early stage and progressive decline of renal function at the late stage, recent epidemiological studies suggest that DKD patients have a variety of clinical presentations and progression rates to ESRD. Some DKD patients have a decline in renal function without albuminuria but display prominent vascular and interstitial fibrosis on renal histology. DKD patients are more susceptible to acute kidney injury, which might contribute to the interstitial fibrosis. A large portion of type 2 diabetic patients with albuminuria could have overlapping nondiabetic glomerular disease, and therefore, kidney biopsy is required for differential diagnosis for these patients. Only a small portion of DKD patients eventually progress to end-stage renal failure. However, we do not have sensitive and specific biomarkers to identify these high-risk patients. Genetic factors that have a strong association with DKD progression have not been identified yet. A combination of circulating tumor necrosis factor receptor (TNFR)1, TNFR2, and kidney injury molecular 1 provides predictive value for DKD progression. Artificial intelligence could enhance the predictive values for DKD progression by combining the clinical parameters and biological markers. Sodium-glucose co-transporter-2 inhibitors should be added to the new standard care of DKD patients. Several promising new drugs are in clinical trials.

KEY MESSAGES

Over last years, our understanding of DKD has been much improved and new treatments to halt the progression of DKD are coming. However, better diagnostic tools, predictive markers, and treatment options are still urgently needed to help us to better manage these patients with this detrimental disease.

Inflammatory Targets in Diabetic Nephropathy

One of the most frequent complications in patients with diabetes mellitus is diabetic nephropathy (DN). At present, it constitutes the first cause of end stage renal disease, and the main cause of cardiovascular morbidity and mortality in these patients. Therefore, it is clear that new strategies are required to delay the development and the progression of this pathology. This new approach should look beyond the control of traditional risk factors such as hyperglycemia and hypertension. Currently, inflammation has been recognized as one of the underlying processes involved in the development and progression of kidney disease in the diabetic population. Understanding the cascade of signals and mechanisms that trigger this maladaptive immune response, which eventually leads to the development of DN, is crucial. This knowledge will allow the identification of new targets and facilitate the design of innovative therapeutic strategies. In this review, we focus on the pathogenesis of proinflammatory molecules and mechanisms related to the development and progression of DN, and discuss the potential utility of new strategies based on agents that target inflammation.

Ethanol-induced gastric ulcer in rats and intervention of tert-butylhydroquinone: Involvement of Nrf2/HO-1 signalling pathway

Gastric ulcer (GU) is the most common health concern that occurs due to alcohol consumption, smoking and physiological stress. Ethanol-induced GU in animal model resembles the pathophysiology of human ulcer. The present study was designed to investigate the cytoprotective and anti-inflammatory properties of tert-butylhydroquinone (tBHQ), a nuclear factor erythroid 2-related factor 2 (Nrf2) activator, against gastric mucosal damage induced by acute exposure of ethanol (5 ml/kg). The intervention of tBHQ (25 and 50 mg/kg, per os (po)) and omeprazole (20 mg/kg, po) was done for 10 consecutive days. Omeprazole was chosen as a standard drug because it is prescribed for the treatment of GU. Pretreatment of tBHQ decreased gastric mucosal lesion, ulcer index, apoptotic cells and lipid peroxidation level induced by ethanol. Furthermore, the intervention of tBHQ increased gastric mucosa integrity, pH, reduced glutathione, collagen and mucus-producing goblet cells. Intervention of tBHQ increased the expression of antioxidant markers such as Nrf2, haeme oxygenase-1 and catalase and decreased the expressions of inflammatory markers such as nuclear factor kappa-light-chain-enhancer of activated B cells and cyclooxygenase-2. The cytoprotective potential of tBHQ against gastric mucosal damage might be due to its ability to enhance cellular antioxidants and anti-inflammatory responses.

The pivotal role of nuclear factor erythroid 2-related factor 2 in diabetes-induced endothelial dysfunction

Endothelial dysfunction (ED) is a key event in the onset and progression of vascular complications associated with diabetes. Regulation of endothelial function and the underlying signaling mechanisms in the progression of diabetes-induced vascular complications have been well established. Recent studies indicate that increased oxidative stress is an important determinant of endothelial injury and patients with hypertension display ED mediated by impaired Nitric Oxide (NO) availability. Further, oxidative stress is known to be associated with inflammation and ED in vascular remodeling and diabetes-associated hypertension. Numerous strategies have been developed to improve the function of endothelial cells and increasing number of evidences highlight the indispensable role of antioxidants in modulation of endothelium-dependent vasodilation responses. Nuclear factor Erythroid 2-related factor 2 (Nrf2), is the principal transcriptional regulator, that is central in mediating oxidative stress signal response. Having unequivocally established the relationship between type 2 diabetes mellitus (T2DM) and oxidative stress, the pivotal role of Nrf2/Keap1/ARE network, has taken the center stage as target for developing therapies towards maintaining the cellular redox environment. Several activators of Nrf2 are known to combat diabetes-induced ED and few are currently in clinical trials. Focusing on their therapeutic value in diabetes-induced ED, this review highlights some natural and synthetic molecules that are involved in the modulation of the Nrf2/Keap1/ARE network and its underlying molecular mechanisms in the regulation of ED. Further emphasis is also laid on the therapeutic benefits of directly up-regulating Nrf2-mediated antioxidant defences in regulating endothelial redox homeostasis for countering diabetes-induced ED.

The inhibitor of autophagy SBI-0206965 aggravates atherosclerosis through decreasing myeloid-derived suppressor cells

Atherosclerosis (AS) is currently the leading cause of mortality worldwide, with the development of new strategies to prevent the formation and rupture of atherosclerotic plaques being a paramount area of research. Amounting evidence suggests autophagy has an important role in the pathogenesis of AS and may be a potential therapeutic target. In this study, the effect of SBI-0206965(6965), a novel inhibitor of autophagy, was tested on the development of AS in apolipoprotein E deficient (ApoE^−/−) mice. Systemic application of 6965 was found to aggravate AS, with increased plaque size and decreased plaque stability in comparison with the control. Of note, it was observed that 6965 decreased the proportion of myeloid-derived suppressor cells (MDSCs). Further investigation demonstrated MDSCs markedly alleviated AS in ApoE^−/− mice; while 6965 reduced the viability and promoted apoptosis of MDSCs in vitro. This is the first study describing an association between autophagy and MDSCs in AS models, providing a novel mechanism to potentially target in the management of this condition.

Autophagy as a novel therapeutic target in vascular calcification

The autophagy pathway is a key regulator of cellular metabolism and homeostasis, and plays a critical role in maintaining normal vascular cell function. It is well recognised that autophagy can regulate endothelial cell homeostasis, vascular smooth muscle cell (VSMC) phenotype transition, and calcium (Ca²⁺) homeostasis in VSMCs. Emerging evidence has demonstrated that autophagy directly protects against vascular calcification (VC). Crosstalk between endosomes, dysfunctional mitochondria, autophagic vesicles and Ca²⁺ and phosphate (Pi) enriched matrix vesicles (MVs) may underpin the pathogenesis of VC. In this review, we summarize the current experimental evidence in understanding how autophagy maintains normal vascular cell function and its protective role against vascular calcification. We also discuss the underlying molecular and cellular mechanisms through which autophagy inhibits vascular calcification. Pharmacological modulation of autophagy may offer an exciting new strategy for the treatment of vascular calcification.

Loss of exosomal MALAT1 from ox-LDL-treated vascular endothelial cells induces maturation of dendritic cells in atherosclerosis development

Objectives: Maturation of dendritic cells (DCs) contributes to atherosclerosis (AS) development. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a long non-coding RNA (lncRNA) that is involved in tumorigenesis. This study was designed to explore the role of exosomes from oxidized low-density lipoprotein (oxLDL)-treated vascular endothelial cells (VECs) in regulating DCs maturation in AS, and to elucidate whether MALAT1 was involved in this process.

Methods: Human umbilical VECs (HUVECs) were treated with or without ox-LDL, after which exosomes were isolated and then co-cultured with immature DCs (iDCs). The phenotypic profile and cell endocytosis in DCs were examined to assess the degree of maturation of DCs. The interaction between MALAT1 and NRF2 protein in DCs was evaluated using RNA pull-down assay and RNA immunoprecipitation. A mouse model of AS was eatablished by feeding ApoE knockout (ApoE^−/-) mice with a high-fat diet for 12 weeks.

Results: The ox-LDL-HUVECs-Exos exhibited lower MALAT1 expression when compared with HUVECs-Exos. Furthermore, exosomes from ox-LDL-treated MALAT1-overexpressing-HUVECs (ox-LDL-HUVECs-Exos^Lv-MALAT1) released elevated expression of MALAT1 to iDCs, which interacted with NRF2 and activated NRF2 signaling, and thereby inhibited ROS accumulation and DCs maturation. Further in vivo experiments showed that a decrease in MALAT1 content in mouse VECs-Exos might be associated with mouse AS progression.

Conclusion: Loss of exosomal MALAT1 from ox-LDL-treated VECs induces DCs maturation in atherosclerosis development.

Unraveling the Role of Inflammation in the Pathogenesis of Diabetic Kidney Disease

Diabetic kidney disease (DKD) remains the leading cause of end-stage renal disease (ESRD) and is therefore a major burden on the healthcare system. Patients with DKD are highly susceptible to developing cardiovascular disease, which contributes to increased morbidity and mortality rates. While progress has been made to inhibit the acceleration of DKD, current standards of care reduce but do not eliminate the risk of DKD. There is growing appreciation for the role of inflammation in modulating the process of DKD. The focus of this review is on providing an overview of the current status of knowledge regarding the pathologic roles of inflammation in the development of DKD. Finally, we summarize recent therapeutic advances to prevent DKD, with a focus on the anti-inflammatory effects of newly developed agents.

Is there a role for autophagy in ascending aortopathy associated with tricuspid or bicuspid aortic valve?

Autophagy is a conserved process by which cytoplasmatic elements are sequestered in vesicles and degraded after their fusion with lysosomes, thus recycling the precursor molecules. The autophagy-mediated removal of redundant/harmful/damaged organelles and biomolecules plays not only a replenishing function, but protects against stressful conditions through an adaptive mechanism. Autophagy, known to play a role in several pathological conditions, is now gaining increasing attention also in the perspective of the identification of the pathogenetic mechanisms at the basis of ascending thoracic aortic aneurysm (TAA), a localized or diffused dilatation of the aorta with an abnormal widening greater than 50 percent of the vessel's normal diameter. TAA is less frequent than abdominal aortic aneurysm (AAA), but is encountered with a higher percentage in patients with congenital heart disease or known genetic syndromes. Several biological aspects of TAA pathophysiology remain to be elucitated and therapeutic needs are still widely unmet. One of the most controversial and epidemiologically important forms of TAA is that associated with the congenital bicuspid malformation of the aortic valve (BAV). Dysregulated autophagy in response, for example, to wall shear stress alterations, has been demonstrated to affect the phenotype of vascular cells relevant to aortopathy, with potential consequences on signaling, remodeling, and angiogenesis. The most recent findings and hypotheses concerning the multiple aspects of autophagy and of its dysregulation are summarized, both in general and in the context of the different vascular cell types and of TAA progression, with particular reference to BAV-related aortopathy.

Macrophage Death as a Pharmacological Target in Atherosclerosis

Atherosclerosis is a chronic inflammatory disorder characterized by the gradual build-up of plaques within the vessel wall of middle-sized and large arteries. Over the past decades, treatment of atherosclerosis mainly focused on lowering lipid levels, which can be accomplished by the use of statins. However, some patients do not respond sufficiently to statin therapy and therefore still have a residual cardiovascular risk. This issue highlights the need for novel therapeutic strategies. As macrophages are implicated in all stages of atherosclerotic lesion development, they represent an important alternative drug target. A variety of anti-inflammatory strategies have recently emerged to treat or prevent atherosclerosis. Here, we review the canonical mechanisms of macrophage death and their impact on atherogenesis and plaque stability. Macrophage death is a prominent feature of advanced plaques and is a major contributor to necrotic core formation and plaque destabilization. Mechanisms of macrophage death in atherosclerosis include apoptosis, passive or accidental necrosis as well as secondary necrosis, a type of death that typically occurs when apoptotic cells are insufficiently cleared by neighboring cells via a phagocytic process termed efferocytosis. In addition, less-well characterized types of regulated necrosis in macrophages such as necroptosis, pyroptosis, ferroptosis, and parthanatos may occur in advanced plaques and are also discussed. Autophagy in plaque macrophages is an important survival pathway that protects against cell death, yet massive stimulation of autophagy promotes another type of death, usually referred to as autosis. Multiple lines of evidence indicate that a better insight into the different mechanisms of macrophage death, and how they mutually interact, will provide novel pharmacological strategies to resolve atherosclerosis and stabilize vulnerable, rupture-prone plaques.

Carnosol as a Nrf2 Activator Improves Endothelial Barrier Function Through Antioxidative Mechanisms

Oxidative stress is the main pathogenesis of diabetic microangiopathy, which can cause microvascular endothelial cell damage and destroy vascular barrier. In this study, it is found that carnosol protects human microvascular endothelial cells (HMVEC) through antioxidative mechanisms. First, we measured the antioxidant activity of carnosol. We showed that carnosol pretreatment suppressed tert-butyl hydroperoxide (t-BHP)-induced cell viability, affected the production of lactate dehydrogenase (LDH) as well as reactive oxygen species (ROS), and increased the produce of nitric oxide (NO). Additionally, carnosol promotes the protein expression of vascular endothelial cadherin (VE-cadherin) to keep the integrity of intercellular junctions, which indicated that it protected microvascular barrier in oxidative stress. Meanwhile, we investigated that carnosol can interrupt Nrf2-Keap1 protein−protein interaction and stimulated antioxidant-responsive element (ARE)-driven luciferase activity in vitro. Mechanistically, we showed that carnosol promotes the expression of heme oxygenase 1(HO-1) and nuclear factor-erythroid 2 related factor 2(Nrf2). It can also promote the expression of endothelial nitric oxide synthase (eNOS). Collectively, our data support the notion that carnosol is a protective agent in HMVECs and has the potential for therapeutic use in the treatments of microvascular endothelial cell injury.