The NRF2 knockout rat: a new animal model to study endothelial dysfunction, oxidant stress, and microvascular rarefaction

The effectiveness of prolonged hypothermic preservation of isolated rat hearts using oxygen, medical nitrous oxide and carbon monoxide gas mixtures

The possibility of using an oxygen-nitrous oxide mixture for prolonged hypothermic preservation of rat heart for 24 h was investigated. A comparative analysis of restoration of functional activity of hearts in the groups of 24-h preservation at +4 °C with different gases (O2, N2) and gas mixtures (CO + O2, N2O + O2, N2+O2, N2O + N2) was carried out. It was shown that the presence of oxygen in the gas mixture was the key factor for heart preservation. No stable heart preservation was observed in oxygen-free mixtures. At the same time, preservation in pure oxygen showed a significantly lower level of cardiac recovery compared to preservation in gas mixtures O2+CO (6.5 atm.) and O2+N2O (6.5 atm.). LVDP (left ventricular developed pressure) values were 30 ± 19 mmHg and 46 ± 9 mmHg, respectively, with no significant differences found. The decrease in LDVP after 24 h of storage was 26-40 % of the intact control. The results obtained indicate the presence of pronounced synergistic effects of both gases during 24-h heart preservation, which is confirmed by data of marker genes Nfe2l2, Nox1, Prdx1, Hif1a, Nos2, Slc2a4, Ucp-1, Jun, Casp3 expression analysis and myocardial infarction damage level data. The more frequent occurrence of arrhythmias was observed in the oxygen-nitrous oxide group compared with the CO group, and the mechanism of this phenomenon is unclear. Nevertheless, the already medically approved N2O + O2 gas mixture could serve as a balanced choice for future improvements, offering a shorter duration of cardiac preservation compared to the CO + O2 mixture, while ensuring safety in its use.

The glutathione-dependent neuroprotective activity of the blood-CSF barrier is inducible through the Nrf2 signaling pathway during postnatal development

BACKGROUND

Choroid plexuses regulate the exchanges between the blood and the CSF, and provide trophic factors necessary to brain development. They also express detoxifying enzymes that protect the developing brain from harmful substances. Targeting the Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) signaling pathway may enhance the detoxification capabilities of choroid plexuses that are linked to glutathione conjugation, but little is known about mechanisms of enzyme induction in this tissue.

METHODS

Rat pups were treated with dimethylfumarate and the subcellular localization of Nrf2 was analyzed in the choroidal tissue by confocal imaging. Glutathione-S-transferase (GST) activity was assessed ex vivo in the choroidal tissue, and 1-chloro-2,4-dinitrobenzene, a toxicant and prototypic GST substrate, was used to evaluate in vivo the efficiency of the glutathione-dependent enzymatic barrier function of choroid plexuses. Nrf2 knockout rat pups were used to establish the Nrf2 dependency of GST induction in this tissue.

RESULTS

We show an early postnatal expression of Nrf2 in the rat choroidal tissue. Treatment of rat pups with dimethylfumarate triggers Nrf2 nuclear translocation in choroidal epithelial cells. This treatment increases GST activity in choroid plexus, and reduces the blood-to-CSF permeation of 1-chloro-2,4-dinitrobenzene. In Nrf2 knockout rats, the constitutive activity of the choroidal glutathione-dependent detoxifying machinery is maintained, but the efficacy of dimethylfumarate to induce glutathione conjugation in the choroid plexuses is strongly reduced, indicating that dimethylfumarate acts mainly through the Nrf2 signaling pathway.

CONCLUSIONS

This work shows that the glutathione-dependent detoxifying function of the blood-CSF barrier can be pharmacologically enhanced through the Nrf2 signaling pathway to better protect the neural fluid environment from drug and toxic accumulation during the neonatal period.

Model organisms for investigating the functional involvement of NRF2 in non-communicable diseases

Non-communicable chronic diseases (NCDs) are most commonly characterized by age-related loss of homeostasis and/or by cumulative exposures to environmental factors, which lead to low-grade sustained generation of reactive oxygen species (ROS), chronic inflammation and metabolic imbalance. Nuclear factor erythroid 2-like 2 (NRF2) is a basic leucine-zipper transcription factor that regulates the cellular redox homeostasis. NRF2 controls the expression of more than 250 human genes that share in their regulatory regions a cis-acting enhancer termed the antioxidant response element (ARE). The products of these genes participate in numerous functions including biotransformation and redox homeostasis, lipid and iron metabolism, inflammation, proteostasis, as well as mitochondrial dynamics and energetics. Thus, it is possible that a single pharmacological NRF2 modulator might mitigate the effect of the main hallmarks of NCDs, including oxidative, proteostatic, inflammatory and/or metabolic stress. Research on model organisms has provided tremendous knowledge of the molecular mechanisms by which NRF2 affects NCDs pathogenesis. This review is a comprehensive summary of the most commonly used model organisms of NCDs in which NRF2 has been genetically or pharmacologically modulated, paving the way for drug development to combat NCDs. We discuss the validity and use of these models and identify future challenges.

Isoflavones Effects on Vascular and Endothelial Outcomes: How Is the Gut Microbiota Involved?

Isoflavones are a group of (poly)phenols, also defined as phytoestrogens, with chemical structures comparable with estrogen, that exert weak estrogenic effects. These phytochemical compounds have been targeted for their proven antioxidant and protective effects. Recognizing the increasing prevalence of cardiovascular diseases (CVD), there is a growing interest in understanding the potential cardiovascular benefits associated with these phytochemical compounds. Gut microbiota may play a key role in mediating the effects of isoflavones on vascular and endothelial functions, as it is directly implicated in isoflavones metabolism. The findings from randomized clinical trials indicate that isoflavone supplementation may exert putative effects on vascular biomarkers among healthy individuals, but not among patients affected by cardiometabolic disorders. These results might be explained by the enzymatic transformation to which isoflavones are subjected by the gut microbiota, suggesting that a diverse composition of the microbiota may determine the diverse bioavailability of these compounds. Specifically, the conversion of isoflavones in equol-a microbiota-derived metabolite-seems to differ between individuals. Further studies are needed to clarify the intricate molecular mechanisms behind these contrasting results.

Quantitative proteomic analyses uncover regulatory roles of Nrf2 in human endothelial cells

Nuclear factor erythroid 2-related factor 2 (Nrf2), a transcriptional regulator, is the predominant factor in modulating oxidative stress and other cellular signaling responses. Studies from our lab and others highlighted that activation of the Nrf2 pathway by small molecules improves endothelial function by suppressing oxidative and endoplasmic reticulum (ER) stress. However, the exact mechanisms by which Nrf2 elicits these effects are unknown. In the present study, we developed CRISPR/Cas9-mediated Nrf2 knocked-out human endothelial cells, and proteomic signature was studied using LC-MS/MS. We identified 723 unique proteins, of which 361 proteins were found to be differentially regulated and further screened in the Nrf2ome online database, where we identified a highly interconnected signaling network in which 70 proteins directly interact with Nrf2. These proteins were found to regulate some key cellular and metabolic processes in the regulation actin cytoskeleton, ER stress, angiogenesis, inflammation, Hippo signaling pathway, and epidermal growth factor/fibroblast growth factor (EGF/FGF) signaling pathway. Our findings suggest the role of Nrf2 in maintaining endothelium integrity and its relationship with the crucial cellular processes which help develop novel therapeutics against endothelial dysfunction and its associated complications.

Study of anti-fatigue activity of polysaccharide from fruiting bodies of Armillaria gallica

Fatigue is a common physiological response that is closely related to energy metabolism. Polysaccharides, as excellent dietary supplements, have been proven to have a variety of pharmacological activities. In this study, A 23.007 kDa polysaccharide from Armillaria gallica (AGP) was purified and performed structural characterization, including analysis of homogeneity, molecular weight and monosaccharide composition. Methylation analysis is used to analyze the glycosidic bond composition of AGP. The mouse model of acute fatigue was used to evaluate the anti-fatigue effect of AGP. AGP-treatment improved exercise endurance in mice and reduced fatigue symptoms caused by acute exercise. AGP regulated the levels of adenosine triphosphate, lactic acid, blood urea nitrogen and lactate dehydrogenase, muscle glycogen and liver glycogen of acute fatigue mice. AGP affected the composition of intestinal microbiota, the changes of some intestinal microorganisms are correlated with fatigue and oxidative stress indicators. Meanwhile, AGP reduced oxidative stress levels, increased antioxidant enzyme activity and regulated the AMP-dependent protein kinase/nuclear factor erythroid 2-related factor 2 signaling pathway. AGP exerted an anti-fatigue effect through modulation of oxidative stress, which is related to intestinal microbiota.

Structure and potential anti-fatigue mechanism of polysaccharides from Bupleurum chinense DC

Two polysaccharides, BCP-1 and BCP-2, were obtained from Bupleurum chinense DC. by water extraction and ultrafiltration. BCP-1 (1.04 × 10⁵ Da) and BCP-2 (2.14 × 10⁴ Da) were composed of Mannose, Rhamnose, Glucose, Galactose, Arabinose, and Galacturonic acid in different proportions. They both contained oligogalacturonides in their main chain. Besides, the backbone of BCP-1 was composed of 4-β-Galp and 4,6-β-Glcp, and branched at C4 of 4,6-β-Glcp. While BCP-2 contained a backbone of 3,5-α-Araf residues with branches at C3. BCP-2 effectively extended the forced swimming time, improved the glycogen reserves and antioxidant system, decreased the levels of blood urea nitrogen, lactic acid, lactate dehydrogenase and creatinine kinase expression. It alleviated physical fatigue through regulating 5'-AMP-activated protein kinase (AMPK) and Nuclear Factor erythroid 2-Related Factor 2 (Nrf2) signalling pathway in skeletal muscles. This study demonstrated that BCP-2 exhibited more effective anti-fatigue activity than BCP-1 potentially associated with its primary and higher structures.

Severe heat stress modulated nuclear factor erythroid 2-related factor 2 and macrophage migration inhibitory factor pathway in rat liver

Heat stress impairs physiology and overall functionality of the body at tissue and organ level in animals. Liver being a vital organ performs more than hundreds regulatory functions of the body. Present study investigates the modulation of molecular pathways that are responsible for liver damage triggered by heat stress. Male Sprague dawley rats were exposed to heat stress (45 °C) in heat simulation chamber till core temperature reaches 40 °C and 42 °C in 25 and 42 min respectively. For in-depth evaluation of liver functions during severe heat stress, hepatic transcriptome and proteome were analysed by microarray and two dimensional gel electrophoresis respectively. Results revealed major alterations in redox status, inflammation, mitochondrial dysfunction and proteostasis related pathways. Data of molecular pathway analysis demonstrate that nuclear factor erythroid 2-related factor 2 (NRF-2) mediated oxidative stress response and macrophage migration inhibitory factor (MIF) regulated inflammatory pathways were upregulated in severe heat stressed liver. Expression levels of downstream molecules of above pathways such as heat shock protein 90AB 1, peroxiredoxin 5, Jun N-terminal kinases 1/2, heme-oxygenase 1, apolipoprotein 1 and interleukin 10 were examined and result suggested the upregulation of these genes modulates the NRF-2 and MIF regulated pathways in heat stressed liver. Irregularity in molecular signalling networks lead to mitochondrial dysfunction indicated by upregulation of ATP synthase β and peroxiredoxin 1 along with decreased levels of glucose-6-phosphate dehydrogenase and enhanced activity of cytochrome c in liver mitochondria. Thus, current study demonstrated heat induced alterations in key liver functions were regulated by NRF-2 and MIF pathways.

Effects of Antioxidant Gene Overexpression on Stress Resistance and Malignization In Vitro and In Vivo: A Review

Reactive oxygen species (ROS) are normal products of a number of biochemical reactions and are important signaling molecules. However, at the same time, they are toxic to cells and have to be strictly regulated by their antioxidant systems. The etiology and pathogenesis of many diseases are associated with increased ROS levels, and many external stress factors directly or indirectly cause oxidative stress in cells. Within this context, the overexpression of genes encoding the proteins in antioxidant systems seems to have become a viable approach to decrease the oxidative stress caused by pathological conditions and to increase cellular stress resistance. However, such manipulations unavoidably lead to side effects, the most dangerous of which is an increased probability of healthy tissue malignization or increased tumor aggression. The aims of the present review were to collect and systematize the results of studies devoted to the effects resulting from the overexpression of antioxidant system genes on stress resistance and carcinogenesis in vitro and in vivo. In most cases, the overexpression of these genes was shown to increase cell and organism resistances to factors that induce oxidative and genotoxic stress but to also have different effects on cancer initiation and promotion. The last fact greatly limits perspectives of such manipulations in practice. The overexpression of GPX3 and SOD3 encoding secreted proteins seems to be the "safest" among the genes that can increase cell resistance to oxidative stress. High efficiency and safety potential can also be found for SOD2 overexpression in combinations with GPX1 or CAT and for similar combinations that lead to no significant changes in H₂O₂ levels. Accumulation, systematization, and the integral analysis of data on antioxidant gene overexpression effects can help to develop approaches for practical uses in biomedical and agricultural areas. Additionally, a number of factors such as genetic and functional context, cell and tissue type, differences in the function of transcripts of one and the same gene, regulatory interactions, and additional functions should be taken into account.

Antioxidant Polyphenols of Antirhea borbonica Medicinal Plant and Caffeic Acid Reduce Cerebrovascular, Inflammatory and Metabolic Disorders Aggravated by High-Fat Diet-Induced Obesity in a Mouse Model of Stroke

Metabolic disorders related to obesity and type 2 diabetes are associated with aggravated cerebrovascular damages during stroke. In particular, hyperglycemia alters redox and inflammatory status, leading to cerebral endothelial cell dysfunction, blood–brain barrier (BBB) disruption and brain homeostasis loss. Polyphenols constitute the most abundant dietary antioxidants and exert anti-inflammatory effects that may improve cerebrovascular complications in stroke. This study evaluated the effects of the characterized polyphenol-rich extract of Antirhea borbonica medicinal plant and its major constituent caffeic acid on a high-fat diet (HFD)-induced obesity mouse model during ischemic stroke, and murine bEnd3 cerebral endothelial cells in high glucose condition. In vivo, polyphenols administered by oral gavage for 12 weeks attenuated insulin resistance, hyperglycemia, hyperinsulinemia and dyslipidemia caused by HFD-induced obesity. Polyphenols limited brain infarct, hemorrhagic transformation and BBB disruption aggravated by obesity during stroke. Polyphenols exhibited anti-inflammatory and antioxidant properties by reducing IL-1β, IL-6, MCP-1, TNF-α and Nrf2 overproduction as well as total SOD activity elevation at the cerebral or peripheral levels in obese mice. In vitro, polyphenols decreased MMP-2 activity that correlated with MCP-1 secretion and ROS intracellular levels in hyperglycemic condition. Protective effects of polyphenols were linked to their bioavailability with evidence for circulating metabolites including caffeic acid, quercetin and hippuric acid. Altogether, these findings show that antioxidant polyphenols reduced cerebrovascular, inflammatory and metabolic disorders aggravated by obesity in a mouse model of stroke. It will be relevant to assess polyphenol-based strategies to improve the clinical consequences of stroke in the context of obesity and diabetes.

Recent Advances in the Production of Genome-Edited Rats

The rat is an important animal model for understanding gene function and developing human disease models. Knocking out a gene function in rats was difficult until recently, when a series of genome editing (GE) technologies, including zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and the type II bacterial clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated Cas9 (CRISPR/Cas9) systems were successfully applied for gene modification (as exemplified by gene-specific knockout and knock-in) in the endogenous target genes of various organisms including rats. Owing to its simple application for gene modification and its ease of use, the CRISPR/Cas9 system is now commonly used worldwide. The most important aspect of this process is the selection of the method used to deliver GE components to rat embryos. In earlier stages, the microinjection (MI) of GE components into the cytoplasm and/or nuclei of a zygote was frequently employed. However, this method is associated with the use of an expensive manipulator system, the skills required to operate it, and the egg transfer (ET) of MI-treated embryos to recipient females for further development. In vitro electroporation (EP) of zygotes is next recognized as a simple and rapid method to introduce GE components to produce GE animals. Furthermore, in vitro transduction of rat embryos with adeno-associated viruses is potentially effective for obtaining GE rats. However, these two approaches also require ET. The use of gene-engineered embryonic stem cells or spermatogonial stem cells appears to be of interest to obtain GE rats; however, the procedure itself is difficult and laborious. Genome-editing via oviductal nucleic acids delivery (GONAD) (or improved GONAD (i-GONAD)) is a novel method allowing for the in situ production of GE zygotes existing within the oviductal lumen. This can be performed by the simple intraoviductal injection of GE components and subsequent in vivo EP toward the injected oviducts and does not require ET. In this review, we describe the development of various approaches for producing GE rats together with an assessment of their technical advantages and limitations, and present new GE-related technologies and current achievements using those rats in relation to human diseases.

Assessment of Protection Offered By the NRF2 Pathway Against Hyperoxia-Induced Acute Lung Injury in NRF2 Knockout Rats

ABSTRACT

Nuclear factor erythroid 2-related factor (Nrf2) is a redox-sensitive transcription factor that responds to oxidative stress by activating expressions of key antioxidant and cytoprotective enzymes via the Nrf2-antioxidant response element (ARE) signaling pathway. Our objective was to characterize hyperoxia-induced acute lung injury (HALI) in Nrf2 knock-out (KO) rats to elucidate the role of this pathway in HALI. Adult Nrf2 wildtype (WT), and KO rats were exposed to room air (normoxia) or >95% O2 (hyperoxia) for 48 h, after which selected injury and functional endpoints were measured in vivo and ex vivo. Results demonstrate that the Nrf2-ARE signaling pathway provides some protection against HALI, as reflected by greater hyperoxia-induced histological injury and higher pulmonary endothelial filtration coefficient in KO versus WT rats. We observed larger hyperoxia-induced increases in lung expression of glutathione (GSH) synthetase, 3-nitrotyrosine (index of oxidative stress), and interleukin-1β, and in vivo lung uptake of the GSH-sensitive SPECT biomarker 99mTc-HMPAO in WT compared to KO rats. Hyperoxia also induced increases in lung expression of myeloperoxidase in both WT and KO rats, but with no difference between WT and KO. Hyperoxia had no effect on expression of Bcl-2 (anti-apoptotic protein) or peroxiredoxin-1. These results suggest that the protection offered by the Nrf2-ARE pathway against HALI is in part via its regulation of the GSH redox pathway. To the best of our knowledge, this is the first study to assess the role of the Nrf2-ARE signaling pathway in protection against HALI using a rat Nrf2 knockout model.

Study on the Local Anti-Osteoporosis Effect of Polaprezinc-Loaded Antioxidant Electrospun Membrane

Background

Compared with the healthy condition, osteoporotic bone defects are often accompanied by poor osteogenesis and excessive reactive oxygen species (ROS), which pose serious challenges to bone augmentation and repair by normal resorbable guided bone regeneration (GBR) membrane.

Purpose

Polaprezinc (PZ) was loaded into polycaprolactone/gelatin (PG) hybrid electrospun nanofibers to fabricate a GBR membrane with antioxidant and osteogenesis ability.

Methods

A series of physicochemical characterization were performed by scanning electron microscopy, Fourier-transform infrared spectroscopy, and water contact angle measurement. In addition to membrane degradation and PZ release detection, membranes were tested for cell viability, differentiation, and protein expression in MC3T3-E1 cells by CCK8, alkaline phosphatase activity, mineralization, and Western blotting assays. The membrane osteogenic capacity in cranial bone defects was studied by micro-CT in vivo.

Results

PZ was successfully doped into the PCL/GEL nanofibers to form a hydrophilic GBR membrane. The cumulative release of PZ was closely related to the membrane degradation behavior. PG/0.4%PZ membranes produced the best protective effect on cell proliferation/differentiation under oxidative stress microenvironment; however, the PG/0.8%PZ membrane was cytotoxic. Western blotting demonstrated that the PZ-loaded membrane upregulated the Nrf2/HO-1/SOD1 signaling molecules in a concentration-dependent manner. In addition, micro-CT results showed an abundant formation of new bones in the PG/0.4%PZ group compared to the PG group.

Conclusion

PZ-loaded degradable PG membranes (especially PG/0.4%PZ) have great potential to accelerate bone regeneration in oxidative stress-related diseases.

Cancer Chemopreventive Role of Dietary Terpenoids by Modulating Keap1-Nrf2-ARE Signaling System—A Comprehensive Update

ROS, RNS, and carcinogenic metabolites generate excessive oxidative stress, which changes the basal cellular status and leads to epigenetic modification, genomic instability, and initiation of cancer. Epigenetic modification may inhibit tumor-suppressor genes and activate oncogenes, enabling cells to have cancer promoting properties. The nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that in humans is encoded by the NFE2L2 gene, and is activated in response to cellular stress. It can regulate redox homoeostasis by expressing several cytoprotective enzymes, including NADPH quinine oxidoreductase, heme oxygenase-1, UDP-glucuronosyltransferase, glutathione peroxidase, glutathione-S-transferase, etc. There is accumulating evidence supporting the idea that dietary nutraceuticals derived from commonly used fruits, vegetables, and spices have the ability to produce cancer chemopreventive activity by inducing Nrf2-mediated detoxifying enzymes. In this review, we discuss the importance of these nutraceuticals in cancer chemoprevention and summarize the role of dietary terpenoids in this respect. This approach was taken to accumulate the mechanistic function of these terpenoids to develop a comprehensive understanding of their direct and indirect roles in modulating the Keap1-Nrf2-ARE signaling system.

Potential Protective Effects of Equol (Soy Isoflavone Metabolite) on Coronary Heart Diseases-From Molecular Mechanisms to Studies in Humans

Equol, a soy isoflavone-derived metabolite of the gut microbiome, may be the key cardioprotective component of soy isoflavones. Systematic reviews have reported that soy isoflavones have no to very small effects on traditional cardiovascular disease risk factors. However, the potential mechanistic mode of action of equol on non-traditional cardiovascular risk factors has not been systematically reviewed. We searched the PubMed through to July 2021 by using terms for equol and each of the following markers: inflammation, oxidation, endothelial function, vasodilation, atherosclerosis, arterial stiffness, and coronary heart disease. Of the 231 records identified, 69 articles met the inclusion criteria and were summarized. Our review suggests that equol is more lipophilic, bioavailable, and generally more potent compared to soy isoflavones. Cell culture, animal, and human studies show that equol possesses antioxidative, anti-inflammatory, and vasodilatory properties and improves arterial stiffness and atherosclerosis. Many of these actions are mediated through the estrogen receptor β. Overall, equol may have a greater cardioprotective benefit than soy isoflavones. Clinical studies of equol are warranted because equol is available as a dietary supplement.

NRF2 Activation and Downstream Effects: Focus on Parkinson's Disease and Brain Angiotensin

Reactive oxygen species (ROS) are signalling molecules used to regulate cellular metabolism and homeostasis. However, excessive ROS production causes oxidative stress, one of the main mechanisms associated with the origin and progression of neurodegenerative disorders such as Parkinson's disease. NRF2 (Nuclear Factor-Erythroid 2 Like 2) is a transcription factor that orchestrates the cellular response to oxidative stress. The regulation of NRF2 signalling has been shown to be a promising strategy to modulate the progression of the neurodegeneration associated to Parkinson's disease. The NRF2 pathway has been shown to be affected in patients with this disease, and activation of NRF2 has neuroprotective effects in preclinical models, demonstrating the therapeutic potential of this pathway. In this review, we highlight recent advances regarding the regulation of NRF2, including the effect of Angiotensin II as an endogenous signalling molecule able to regulate ROS production and oxidative stress in dopaminergic neurons. The genes regulated and the downstream effects of activation, with special focus on Kruppel Like Factor 9 (KLF9) transcription factor, provide clues about the mechanisms involved in the neurodegenerative process as well as future therapeutic approaches.

Traditional Chinese medicine as a therapeutic option for cardiac fibrosis: Pharmacology and mechanisms

Cardiovascular diseases are one of the leading causes of death worldwide and cardiac fibrosis is a common pathological process for cardiac remodeling in cardiovascular diseases. Cardiac fibrosis not only accelerates the deterioration progress of diseases but also becomes a pivotal contributor for futile treatment in clinical cardiovascular trials. Although cardiac fibrosis is common and prevalent, effective medicines to provide sufficient clinical intervention for cardiac fibrosis are still unavailable. Traditional Chinese medicine (TCM) is the natural essence experienced boiling, fry, and other processing methods, including active ingredients, extracts, and herbal formulas, which have been applied to treat human diseases for a long history. Recently, research has increasingly focused on the great potential of TCM for the prevention and treatment of cardiac fibrosis. Here, we aim to clarify the identified pro-fibrotic mechanisms and intensively summarize the application of TCM in improving cardiac fibrosis by working on these mechanisms. Through comprehensively analyzing, TCM mainly regulates the following pathways during ameliorating cardiac fibrosis: attenuation of inflammation and oxidative stress, inhibition of cardiac fibroblasts activation, reduction of extracellular matrix accumulation, modulation of the renin-angiotensin-aldosterone system, modulation of autophagy, regulation of metabolic-dependent mechanisms, and targeting microRNAs. We also discussed the deficiencies and the development direction of anti-fibrotic therapies on cardiac fibrosis. The data reviewed here demonstrates that TCM shows a robust effect on alleviating cardiac fibrosis, which provides us a rich source of new drugs or drug candidates. Besides, we also hope this review may give some enlightenment for treating cardiac fibrosis in clinical practice.

Biomimetics provides lessons from nature for contemporary ways to improve human health

Homo sapiens is currently living in serious disharmony with the rest of the natural world. For our species to survive, and for our well-being, we must gather knowledge from multiple perspectives and actively engage in studies of planetary health. The enormous diversity of species, one of the most striking aspects of life on our planet, provides a source of solutions that have been developed through evolution by natural selection by animals living in extreme environments. The food system is central to finding solutions; our current global eating patterns have a negative impact on human health, driven climate change and loss of biodiversity. We propose that the use of solutions derived from nature, an approach termed biomimetics, could mitigate the effects of a changing climate on planetary health as well as human health. For example, activation of the transcription factor Nrf2 may play a role in protecting animals living in extreme environments, or animals exposed to heat stress, pollution and pesticides. In order to meet these challenges, we call for the creation of novel interdisciplinary planetary health research teams.

Association of Nuclear Factor Erythroid-2-Related Actor 2 Gene Polymorphisms with Diabetic Nephropathy in Chinese Patients

Aim

Nuclear factor erythroid-2-related factor 2 (NRF2) has emerged as a therapeutic target in many diseases. To explore this further, we evaluated the relationships between the -617C/A (rs6721961) polymorphisms within the NRF2 promoter and diabetic nephropathy (DN) in Chinese Han patients with type 2 diabetes mellitus (T2DM).

Methods

A total of 883 subjects with T2DM (500 without and 383 with DN) were enrolled in this study. Multivariable linear regression models were carried out to assess the association of DN with the -617C/A (rs6721961) polymorphisms.

Results

The AA genotype frequencies in patients with DN were significantly lower than those in patients without DN (χ² = 8.04, p = 0.018). Multivariate logistic regression analyses showed that individuals with the AA genotype had a significantly lower risk for DN (OR 0.52; 95% CI 0.28, 0.94; p = 0.029) than those with the CC genotype. Moreover, AA carriers had a significantly lower risk of DN (OR 0.46; 95% CI 0.26, 0.82; p = 0.009) relative to those with the CC + CA genotype, even after adjusting for known DN risk factors.

Conclusion

Our study indicated that the -617C/A polymorphism within the NRF2 promoter was significantly associated with DN in Chinese Han patients with T2DM.

Targeting Transcription Factor Nrf2 (Nuclear Factor Erythroid 2-Related Factor 2) for the Intervention of Vascular Cognitive Impairment and Dementia

Vascular cognitive impairment and dementia (VCID) is an age-related, mild to severe mental disability due to a broad panel of cerebrovascular disorders. Its pathobiology involves neurovascular dysfunction, blood-brain barrier disruption, white matter damage, microRNAs, oxidative stress, neuroinflammation, and gut microbiota alterations, etc. Nrf2 (Nuclear factor erythroid 2-related factor 2) is the master regulator of redox status and controls the transcription of a panel of antioxidative and anti-inflammatory genes. By interacting with NF-κB (nuclear factor-κB), Nrf2 also fine-tunes the cellular oxidative and inflammatory balance. Aging is associated with Nrf2 dysfunction, and increasing evidence has proved the role of Nrf2 in mitigating the VCID process. Based on VCID pathobiologies and Nrf2 studies from VCID and other brain diseases, we point out several hypothetical Nrf2 targets for VCID management, including restoration of endothelial function and neurovascular coupling, preservation of blood-brain barrier integrity, reduction of amyloidopathy, promoting white matter integrity, and mitigating oxidative stress and neuroinflammation. Collectively, the Nrf2 pathway could be a promising direction for future VCID research. Targeting Nrf2 would shed light on VCID managing strategies.

Rat models of human diseases and related phenotypes: a systematic inventory of the causative genes

The laboratory rat has been used for a long time as the model of choice in several biomedical disciplines. Numerous inbred strains have been isolated, displaying a wide range of phenotypes and providing many models of human traits and diseases. Rat genome mapping and genomics was considerably developed in the last decades. The availability of these resources has stimulated numerous studies aimed at discovering causal disease genes by positional identification. Numerous rat genes have now been identified that underlie monogenic or complex diseases and remarkably, these results have been translated to the human in a significant proportion of cases, leading to the identification of novel human disease susceptibility genes, helping in studying the mechanisms underlying the pathological abnormalities and also suggesting new therapeutic approaches. In addition, reverse genetic tools have been developed. Several genome-editing methods were introduced to generate targeted mutations in genes the function of which could be clarified in this manner [generally these are knockout mutations]. Furthermore, even when the human gene causing a disease had been identified without resorting to a rat model, mutated rat strains (in particular KO strains) were created to analyze the gene function and the disease pathogenesis. Today, over 350 rat genes have been identified as underlying diseases or playing a key role in critical biological processes that are altered in diseases, thereby providing a rich resource of disease models. This article is an update of the progress made in this research and provides the reader with an inventory of these disease genes, a significant number of which have similar effects in rat and humans.

Medicinal Plant Polyphenols Attenuate Oxidative Stress and Improve Inflammatory and Vasoactive Markers in Cerebral Endothelial Cells during Hyperglycemic Condition

Blood-brain barrier endothelial cells are the main targets of diabetes-related hyperglycemia that alters endothelial functions and brain homeostasis. Hyperglycemia-mediated oxidative stress may play a causal role. This study evaluated the protective effects of characterized polyphenol-rich medicinal plant extracts on redox, inflammatory and vasoactive markers on murine bEnd3 cerebral endothelial cells exposed to high glucose concentration. The results show that hyperglycemic condition promoted oxidative stress through increased reactive oxygen species (ROS) levels, deregulated antioxidant superoxide dismutase (SOD) activity, and altered expression of genes encoding Cu/ZnSOD, MnSOD, catalase, glutathione peroxidase (GPx), heme oxygenase-1 (HO-1), NADPH oxidase 4 (Nox4), and nuclear factor erythroid 2-related factor 2 (Nrf2) redox factors. Cell preconditioning with inhibitors of signaling pathways highlights a causal role of nuclear factor kappa B (NFκB), while a protective action of AMP-activated protein kinase (AMPK) on redox changes. The hyperglycemic condition induced a pro-inflammatory response by elevating NFκB gene expression and interleukin-6 (IL-6) secretion, and deregulated the production of endothelin-1 (ET-1), endothelial nitric oxide synthase (eNOS), and nitric oxide (NO) vasoactive markers. Importantly, polyphenolic extracts from Antirhea borbonica, Ayapana triplinervis, Dodonaea viscosa, and Terminalia bentzoe French medicinal plants, counteracted high glucose deleterious effects by exhibiting antioxidant and anti-inflammatory properties. In an innovative way, quercetin, caffeic, chlorogenic and gallic acids identified as predominant plant polyphenols, and six related circulating metabolites were found to exert similar benefits. Collectively, these findings demonstrate polyphenol protective action on cerebral endothelial cells during hyperglycemic condition.

Quercetin alleviates hyperthyroidism-induced liver damage via Nrf2 Signaling pathway

Quercetin is a plant flavonoid and has antioxidative properties. In this study, we evaluated the therapeutic effect of quercetin on thyroid dysfunction in L-thyroxin (LT4)-induced hyperthyroidism rats. LT4 was used to prepare the experimental hyperthyroidism model via the intraperitoneal injection. Quercetin was injected at a series doses (5, 50, and 100 mg/kg) to LT4-induced hypothyroidism rats once a day for 14 days. The body weight and food intake were measured once a week. The levels of thyroid hormones, liver function, oxidative stress markers, and antioxidant markers were measured using commercial enzyme-linked immunosorbent assay kits. Hematoxylin-eosin staining was used to observe the thyroid tissue histological changes. The levels of nuclear and total nuclear factor erythroid 2-related factor 2 (Nrf2) were determined by western blot. The liver oxidative stress markers in LT4-induced hyperthyroidism Nrf2 knockout rats were determined to evaluate the role of Nrf2 on quercetin induced protective effects. LT4 administration increased the levels of serum triiodothyronine and thyroxine, activity of oxidative stress markers with a parallel decrease in antioxidant markers and Nrf2. However, the simultaneous administration of quercetin, reversed all these effects indicating its potential in the regulation of hyperthyroidism. Furthermore, the loss function of Nrf2 diminished these effects resulting from the quercetin application, indicating the inhibitory effects caused by the quercetin may be involved in Nrf2 signaling pathway. These results indicate that quercetin could be used to protect against experimental hyperthyroidism-induced liver damage via Nrf2 signaling pathway.

Effect of Nearby Construction Activity on Endothelial Function, Sensitivity to Nitric Oxide, and Potassium Channel Activity in the Middle Cerebral Arteries of Rats

The present study assessed the effect of nearby construction activity on the responses of rat middle cerebral arteries (MCA) to the endothelium-dependent vasodilator acetylcholine and the NO donor sodium nitroprusside (SNP) and the activity of MaxiK potassium channels in MCA smooth muscle cells from male Sprague-Dawley rats. Two monitoring systems were used to assess vibrations in the animal rooms during and immediately after construction activities near the research building where the animal facility is located. One was a commercially available system; the other was a Raspberry-Pi (RPi)-based vibration monitoring system designed in our laboratory that included a small computing unit attached to a rolling sensor (low sensitivity) and a piezoelectric film sensor (high sensitivity). Both systems recorded increased levels of vibration during construction activity outside the building. During the construction period, vasodilator responses to acetylcholine and SNP were abolished, and MaxiK single-channel current opening frequency and open-state probability in cell-attached patches of isolated MCA myocytes were dramatically decreased. Recovery of acetylcholine- and SNP-induced dilation was minimal in MCA from rats studied after completion of construction but housed in the animal facility during construction, whereas responses to acetylcholine and SNP were intact in rats purchased, housed, and studied after construction. Baseline levels of vibration returned after the completion of construction, concomitant with the recovery of normal endothelium-dependent vasodilation to acetylcholine and of NO sensitivity assessed by using SNP in MCA from animals obtained after construction. The results of this study indicate that the vibration associated with nearby construction can have highly disruptive effects on crucial physiologic phenotypes.

Protective Effects of Antioxidant Polyphenols against Hyperglycemia-Mediated Alterations in Cerebral Endothelial Cells and a Mouse Stroke Model

SCOPE

Hyperglycemia alters cerebral endothelial cell and blood-brain barrier functions, aggravating cerebrovascular complications such as stroke during diabetes. Redox and inflammatory changes play a causal role. This study evaluates polyphenol protective effects in cerebral endothelial cells and a mouse stroke model during hyperglycemia.

METHODS AND RESULTS

Murine bEnd.3 cerebral endothelial cells and a mouse stroke model are exposed to a characterized, polyphenol-rich extract of Antirhea borbonica or its predominant constituent caffeic acid, during hyperglycemia. Polyphenol effects on redox, inflammatory and vasoactive markers, infarct volume, and hemorrhagic transformation are determined. In vitro, polyphenols improve reactive oxygen species levels, Cu/Zn superoxide dismutase activity, and both NAPDH oxidase 4 and nuclear factor erythroid 2-related factor 2 (Nrf2) gene expression deregulated by high glucose. Polyphenols reduce Nrf2 nuclear translocation and counteract nuclear factor-ĸappa B activation, interleukin-6 secretion, and the altered production of vasoactive markers mediated by high glucose. In vivo, polyphenols reduce cerebral infarct volume and hemorrhagic transformation aggravated by hyperglycemia. Polyphenols attenuate redox changes, increase vascular endothelial-Cadherin production, and decrease neuro-inflammation in the infarcted hemisphere.

CONCLUSION

Polyphenols protect against hyperglycemia-mediated alterations in cerebral endothelial cells and a mouse stroke model. It is relevant to assess polyphenol benefits to improve cerebrovascular damages during diabetes.

Oxidative Stress and Microvessel Barrier Dysfunction

Clinical and experimental evidence indicate that increased vascular permeability contributes to many disease-associated vascular complications. Oxidative stress with increased production of reactive oxygen species (ROS) has been implicated in a wide variety of pathological conditions, including inflammation and many cardiovascular diseases. It is thus important to identify the role of ROS and their mechanistic significance in microvessel barrier dysfunction under pathological conditions. The role of specific ROS and their cross talk in pathological processes is complex. The mechanisms of ROS-induced increases in vascular permeability remain poorly understood. The sources of ROS in diseases have been extensively reviewed at enzyme levels. This review will instead focus on the underlying mechanisms of ROS release by leukocytes, the differentiate effects and signaling mechanisms of individual ROS on endothelial cells, pericytes and microvessel barrier function, as well as the interplay of reactive oxygen species, nitric oxide, and nitrogen species in ROS-mediated vascular barrier dysfunction. As a counter balance of excessive ROS, nuclear factor erythroid 2 related factor 2 (Nrf2), a redox-sensitive cell-protective transcription factor, will be highlighted as a potential therapeutic target for antioxidant defenses. The advantages and limitations of different experimental approaches used for the study of ROS-induced endothelial barrier function are also discussed. This article will outline the advances emerged mainly from in vivo and ex vivo studies and attempt to consolidate some of the opposing views in the field, and hence provide a better understanding of ROS-mediated microvessel barrier dysfunction and benefit the development of therapeutic strategies.

The Effects of Dietary Supplements that Overactivate the Nrf2/ARE System

Background:

Inflammation is one of the most misunderstood aspects of human health. People have been encouraged to eat foods that have a high antioxidant capacity, and in vitro tests for total antioxidant capacity emerged. They were based on measuring the destruction of oxidized test compounds in direct reactions with the antioxidants in foods. Many dietary supplements arrived in the market. They contained purified antioxidants, such as resveratrol and EGCG that were and still are widely assumed by many to be quite healthy at any dose.

Methods:

The literature on inflammation and the Nrf2/ARE antioxidant system was searched systematically. Articles from prestigious, peer-reviewed journals were obtained and read. The information obtained from them was used to write this review article.

Results:

Over 150 articles and books were read. The information obtained from them showed that very few dietary antioxidants exert their effects by reacting directly with Reactive Oxygen and Nitrogen Species (RONS). Instead, most of the effective antioxidants activate the endogenous Nrf2/ARE antioxidant system. This helps prevent smoldering inflammation and the diseases that it can cause. However, when overactivated or activated constitutively, the Nrf2/ARE antioxidant system can cause some of these diseases, including many types of multidrug resistant cancer, autoimmune, neurodegenerative and cardiovascular diseases.

Conclusion:

Even though green tea, as well as many fruits, vegetables and spices are quite healthy, dietary supplements that deliver much higher doses of antioxidants may not be. People who are diagnosed with cancer and plan to start chemotherapy and/or radiotherapy should probably avoid such supplements. This is because multidrug resistant tumors can hijack and overactivate the Nrf2/ARE antioxidant system.

Cis-element architecture of Nrf2-sMaf heterodimer binding sites and its relation to diseases

Cellular detoxication is essential for health because it provides protection against various chemicals and xenobiotics. The KEAP1-NRF2 system is important for cellular defense against oxidative and electrophilic stresses as NRF2 activates the transcription of an array of cytoprotective genes, including drug-metabolizing and antioxidant enzymes, in a stress-dependent manner. The CNC family of transcription factors, including NRF2, form heterodimers with small Maf (sMaf) proteins and bind to consensus DNA sequences that have been referred to as antioxidant response element, electrophile response element, or NF-E2-binding element. These sequences are now collectively called CNC-sMaf binding element (CsMBE). In addition to forming a heterodimer with CNC proteins, sMaf proteins can form homodimers and recognize regulatory motifs called Maf recognition element (MARE). Although the CsMBE sequence substantially overlaps with that of MARE, the sequences differ. NRF2 selectively recognizes CsMBE, which is critical for cytoprotection. Recent advances in high-throughput sequencing and population-scale genome analysis provide new insights into the transcriptional regulation involved in the stress response. The integration of a genome-wide map of NRF2 occupancy with disease-susceptibility loci reveals the associations between polymorphisms in CsMBE and disease risk, information useful for the personalized medicine of the future.

Endothelium-mediated contributions to fibrosis

Fibrosis, characterized by abnormal and excessive deposition of extracellular matrix, results in compromised tissue and organ structure. This can lead to reduced organ function and eventual failure. Although activated fibroblasts, called myofibroblasts, are considered the central players in fibrosis, the contribution of endothelial cells to the inception and progression of fibrosis has become increasingly recognized. Endothelial cells can contribute to fibrosis by acting as a source of myofibroblasts via endothelial-mesenchymal transition (EndoMT), or by becoming senescent, by secretion of profibrotic mediators and pro-inflammatory cytokines, chemokines and exosomes, promoting the recruitment of immune cells, and by participating in vascular rarefaction and decreased angiogenesis. In this review, we provide an overview of the different aspects of fibrosis in which endothelial cells have been implicated.

Nrf2 in liver toxicology

Liver plays essential roles in the metabolism of many endogenous chemicals and exogenous toxicants. Mechanistic studies in liver have been at the forefront of efforts to probe the roles of bioactivation and detoxication of environmental toxins and toxicants in hepatotoxicity. Moreover, idiosyncratic hepatoxicity remains a key barrier in the clinical development of drugs. The now vast Nrf2 field emerged in part from biochemical and molecular studies on chemical inducers of hepatic detoxication enzymes and subsequent characterization of the modulation of drug/toxicant induced hepatotoxicities in mice through disruption of either Nrf2 or Keap1 genes. In general, loss of Nrf2 increases the sensitivity to such toxic chemicals, highlighting a central role of this transcription factor and its downstream target genes as a modifier to chemical stress. In this review, we summarize the impact of Nrf2 on the toxicology of multiple hepatotoxicants, and discuss efforts to utilize the Nrf2 response in predictive toxicology.

Impact of High Salt Diet on Cerebral Vascular Function and Stroke in Tff3-/-/C57BL/6N Knockout and WT (C57BL/6N) Control Mice

High salt (HS) dietary intake leads to impaired vascular endothelium-dependent responses to various physiological stimuli, some of which are mediated by arachidonic acid (AA) metabolites. Transgenic Tff3^−/− gene knockout mice (Tff3^−/−/C57BL/6N) have changes in lipid metabolism which may affect vascular function and outcomes of stroke. We aimed to study the effects of one week of HS diet (4% NaCl) on vascular function and stroke induced by transient occlusion of middle cerebral artery in Tff3^−/− and wild type (WT/C57BL/6N) mice. Flow-induced dilation (FID) of carotid artery was reduced in WT-HS mice, but not affected in Tff3^−/−-HS mice. Nitric oxide (NO) mediated FID. NO production was decreased with HS diet. On the contrary, acetylcholine-induced dilation was significantly decreased in Tff3^−/− mice on both diets and WT-HS mice. HS intake and Tff3 gene depletion affected the structural components of the vessels. Proteomic analysis revealed a significant effect of Tff3 gene deficiency on HS diet-induced changes in neuronal structural proteins and acute innate immune response proteins’ expression and Tff3 depletion, but HS diet did not increase the stroke volume, which is related to proteome modification and upregulation of genes involved mainly in cellular antioxidative defense. In conclusion, Tff3 depletion seems to partially impair vascular function and worsen the outcomes of stroke, which is moderately affected by HS diet.

Short-term pharmacological activation of Nrf2 ameliorates vascular dysfunction in aged rats and in pathological human vasculature. A potential target for therapeutic intervention

Oxidative stress contributes to endothelial dysfunction, a key step in cardiovascular disease development. Ageing-related vascular dysfunction involves defective antioxidant response. Nuclear factor erythroid 2-like-2 (Nrf2), orchestrates cellular response to oxidative stress. We evaluated the impact of Nrf2-activation on endothelium-dependent and H2O2-mediated vasodilations in: aorta (RA), mesenteric artery (RMA), coronary artery (RCA) and corpus cavernosum (RCC) from ageing rats and in human penile arteries (HPRA) and corpus cavernosum (HCC) from erectile dysfunction (ED) patients. Relaxant responses were evaluated in organ chambers and wire myographs. Nrf2 content and heme oxygenase-1 (HO-1) were determined by ELISA. Superoxide and Nrf2 were detected by immunofluorescence. Pharmacological activation of Nrf2 with sulforaphane (SFN) improved NO- and endothelium-derived hyperpolarizing factor-mediated endothelium-dependent vasodilation and H2O2-induced relaxation in vascular beds from aging rats. SFN-induced effects were associated with increased Nrf2 (RMA, RCA) and reduced superoxide detection in RCA. Improvement of vascular function was confirmed in HPRA and HCC from ED patients and mimicked by another Nrf2 activator, oltipraz. Nrf2 increase and superoxide reduction together with HO-1 increase by Nrf2 activation was evidenced in HCC from ED patients. PDE5 inhibitor-induced relaxations of HPRA and HCC from ED patients were enhanced by SFN. Nrf2 short-term pharmacological activation attenuates age-related impairment of endothelium-dependent and reactive oxygen species (ROS)-induced vasodilation in different rat and human vascular territories by upregulation of Nrf2-related signaling and decreased oxidative stress. In ED patients target tissues, Nrf2 potentiates the functional effect of ED conventional pharmacological therapy suggesting potential therapeutic implication.

Apocynin and Tempol ameliorate dietary sodium-induced declines in cutaneous microvascular function in salt-resistant humans

It has previously been shown that high dietary salt impairs vascular function independent of changes in blood pressure. Rodent studies suggest that NADPH-derived reactive oxygen species mediate the deleterious effect of high salt on the vasculature, and here we translate these findings to humans. Twenty-nine healthy adults (34 ± 2 yr) participated in a controlled feeding study. Participants completed 7 days of a low-sodium diet (LS; 20 mmol sodium/day) and 7 days of a high-sodium diet (HS; 300 mmol sodium/day) in random order. All participants were salt resistant, defined as a ≤5-mmHg change in 24-h mean BP determined while on the LS and HS diets. Laser Doppler flowmetry was used to assess cutaneous vasodilation in response to local heating (42°C) during local delivery of Ringer's (n = 29), 20 mM ascorbic acid (AA; n = 29), 10 µM Tempol (n = 22), and 100 µM apocynin (n = 22). Additionally, endothelial cells were obtained in a subset of participants from an antecubital vein and stained for nitrotyrosine (n = 14). Cutaneous vasodilation was attenuated by the HS diet compared with LS [LS 93.0 ± 2.2 vs. HS 86.8 ± 2.0 percentage of maximal cutaneous vascular conductance (%CVCmax); P < 0.05] and was restored by AA during the HS diet (AA 90.7 ± 1.2 %CVCmax; P < 0.05 vs. HS). Cutaneous vasodilation was also restored with the local infusion of both apocynin (P < 0.01) and Tempol (P < 0.05) on the HS diet. Nitrotyrosine expression was increased on the HS diet compared with LS (P < 0.05). These findings provide direct evidence of dietary sodium-induced endothelial cell oxidative stress and suggest that NADPH-derived reactive oxygen species contribute to sodium-induced declines in microvascular function. NEW & NOTEWORTHY High-sodium diets have deleterious effects on vascular function, likely mediating, in part, the increased cardiovascular risk associated with a high sodium intake. Local infusion of apocynin and Tempol improved microvascular function in salt-resistant adults on a high-salt diet, providing evidence that reactive oxygen species contribute to impairments in microvascular function from high salt. This study provides insight into the blood pressure-independent mechanisms by which dietary sodium impairs vascular function. Listen to this article's corresponding podcast at https://ajpheart.podbean.com/e/dietary-sodium-oxidative-stress-and-microvascular-function/ .

Magnesium lithospermate B protects the endothelium from inflammation-induced dysfunction through activation of Nrf2 pathway

Magnesium lithospermate B (MLB) is an active component of Salvia miltiorrhiza Radix, a traditional Chinese herb used in treating cardiovascular diseases. In this study, we investigated the protective effects of MLB against inflammation-induced endothelial dysfunction in vitro and in vivo, and the underlying mechanisms. Endothelial dysfunction was induced in human dermal microvascular endothelial cells (HMEC-1) in vitro by lipopolysaccharide (LPS, 1 μg/mL). We showed that pretreatment with MLB (10-100 μM) dose-dependently inhibited LPS-induced upregulation of inflammatory cytokines ICAM1, VCAM1, and TNFα, which contributed to reduced leukocytes adhesion and attenuation of endothelial hyperpermeability in HMEC-1 cells. SD rats were injected with LPS (10 mg/kg, ip) to induce endothelial dysfunction in vivo. We showed that pretreatment with MLB (25-100 mg/kg, ip) dose-dependently restored LPS-impaired endothelial-dependent vasodilation in superior mesenteric artery (SMA), attenuated leukocyte adhesion in mesenteric venules and decreased vascular leakage in the lungs. We further elucidated the mechanisms underlying the protective effects of MLB, and revealed that MLB pretreatment inhibited NF-κB activation through inhibition of IκBα degradation and subsequent phosphorylation of NF-κB p65 in vitro and in vivo. In HMEC-1 cells, MLB pretreatment activated the nuclear factor erythroid-2-related factor 2 (Nrf2) pathway. Knockdown of Nrf2 with siRNA abolished the inhibitory effects of MLB on IκBα degradation and ICAM1 up-regulation, which were mimicked by PKC inhibition (Gö6983) or PI3K/Akt inhibition (LY294002). In summary, our results demonstrate that MLB inhibits NF-κB activation through PKC- and PI3K/Akt-mediated Nrf2 activation in HMEC-1 cells and protects against LPS-induced endothelial dysfunction in murine model of acute inflammation.

NRF2 activation with Protandim attenuates salt-induced vascular dysfunction and microvascular rarefaction

HYPOTHESIS

This study tested the hypothesis that dietary activation of the master antioxidant and cell protective transcription factor nuclear factor, erythroid -2-like 2 (NRF2), protects against salt-induced vascular dysfunction by restoring redox homeostasis in the vasculature.

METHODS

Male Sprague-Dawley rats and Syrian hamsters were fed a HS (4.0% NaCl) diet containing ~60 mg/kg/day Protandim supplement for 2 weeks and compared to controls fed HS diet alone.

RESULTS

Protandim supplementation restoredendothelium-dependent vasodilation in response to acetylcholine (ACh) in middle cerebral arteries (MCA)of HS-fed rats and hamster cheek pouch arterioles, and increased microvessel density in the cremastermuscle of HS-fed rats. The restored dilation to ACh in MCA of Protandim-treated rats was prevented by inhibiting nitric oxide synthase (NOS) with L-NAME [100 μM] and was absent in MCA from Nrf2^(-/-) knockout rats fed HS diet. Basilar arteries from HS-fed rats treated with Protandim exhibited significantly lower staining for mitochondrial oxidizing species than untreated animals fed HS diet alone; and Protandim treatment increased MnSOD (SOD2) protein expression in mesenteric arteries of HS-fed rats.

CONCLUSIONS

These results suggest that dietary activation of NRF2 protects against salt-induced vascular dysfunction, vascular oxidative stress, and microvascular rarefaction by upregulating antioxidant defenses and reducing mitochondrial ROS levels.

Mapping genetic modifiers of radiation-induced cardiotoxicity to rat chromosome 3

Radiation therapy is used in ~50% of cancer patients to reduce the risk of recurrence and in some cases improve survival. Despite these benefits, doses can be limited by toxicity in multiple organs, including the heart. The underlying causes and biomarkers of radiation-induced cardiotoxicity are currently unknown, prompting the need for experimental models with inherent differences in sensitivity and resistance to the development of radiation-induced cardiotoxicity. We have identified the parental SS (Dahl salt-sensitive/Mcwi) rat strain to be a highly-sensitized model of radiation-induced cardiotoxicity. In comparison, substitution of rat chromosome 3 from the resistant BN (Brown Norway) rat strain onto the SS background (SS-3BN consomic) significantly attenuated radiation-induced cardiotoxicity. SS-3BN rats had less radiation-induced cardiotoxicity than SS rats, as measured by survival, pleural and pericardial effusions, echocardiogram parameters, and histological damage. Mast cells, previously shown to have predominantly protective roles in radiation-induced cardiotoxicity, were increased in the more resistant SS-3BN hearts postradiation. RNA sequencing from SS and SS-3BN hearts at 1 wk postradiation revealed 5,098 differentially expressed candidate genes across the transcriptome and 350 differentially expressed genes on rat chromosome 3, which coincided with enrichment of multiple pathways, including mitochondrial dysfunction, sirtuin signaling, and ubiquitination. Upstream regulators of enriched pathways included the oxidative stress modulating transcription factor, Nrf2, which is located on rat chromosome 3. Nrf2 target genes were also differentially expressed in the SS vs. SS-3BN consomic hearts postradiation. Collectively, these data confirm the existence of heritable modifiers in radiation-induced cardiotoxicity and provide multiple biomarkers, pathways, and candidate genes for future analyses. NEW & NOTEWORTHY This novel study reveals that heritable genetic factors have the potential to modify normal tissue sensitivity to radiation. Gene variant(s) on rat chromosome 3 can contribute to enhanced cardiotoxicity displayed in the SS rats vs. the BN and SS-3BN consomic rats. Identifying genes that lead to understanding the mechanisms of radiation-induced cardiotoxicity represents a novel method to personalize radiation treatment, as well as predict the development of radiation-induced cardiotoxicity.

High salt diet impairs cerebral blood flow regulation via salt-induced angiotensin II suppression

OBJECTIVES

This study sought to determine whether salt-induced ANG II suppression contributes to impaired CBF autoregulation.

METHODS

Cerebral autoregulation was evaluated with LDF during graded reductions of blood pressure. Autoregulatory responses in rats fed HS (4% NaCl) diet vs LS (0.4% NaCl) diet were analyzed using linear regression analysis, model-free analysis, and a mechanistic theoretical model of blood flow through cerebral arterioles.

RESULTS

Autoregulation was intact in LS-fed animals as MAP was reduced via graded hemorrhage to approximately 50 mm Hg. Short-term (3 days) and chronic (4 weeks) HS diet impaired CBF autoregulation, as evidenced by progressive reductions of laser Doppler flux with arterial pressure reduction. Chronic low dose ANG II infusion (5 mg/kg/min, i.v.) restored CBF autoregulation between the pre-hemorrhage MAP and 50 mm Hg in rats fed short-term HS diet. Mechanistic-based model analysis showed a reduced myogenic response and reduced baseline VSM tone with short-term HS diet, which was restored by ANG II infusion.

CONCLUSIONS

Short-term and chronic HS diet lead to impaired autoregulation in the cerebral circulation, with salt-induced ANG II suppression as a major factor in the initiation of impaired CBF regulation.

Hyperglycemia modulates redox, inflammatory and vasoactive markers through specific signaling pathways in cerebral endothelial cells: Insights on insulin protective action

Type 2 diabetes is associated with major vascular dysfunctions, leading to clinical complications such as stroke. It is also known that hyperglycemia dysregulates blood-brain barrier homeostasis by altering cerebral endothelial cell function. Oxidative stress may play a critical role. The aim of this study was to evaluate the effect of hyperglycemia and insulin on the production of redox, inflammatory and vasoactive markers by cerebral endothelial cells. Murine bEnd.3 cerebral endothelial cells were exposed to hyperglycemia in the presence or not of insulin. Results show that hyperglycemia altered the expression of genes encoding the ROS-producing enzyme Nox4, antioxidant enzymes Cu/ZnSOD, catalase and HO-1 as well as Cu/ZnSOD, MnSOD and catalase enzymatic activities, leading to a time-dependent modulation of ROS levels. Cell preconditioning with inhibitors targeting PI3K, JNK, ERK, p38 MAPK or NFĸB signaling molecules partly blocked hyperglycemia-induced oxidative stress. Conversely, AMPK inhibitor exacerbated ROS production, suggesting a protective role of AMPK on the antioxidant defense system. Hyperglycemia also modulated both gene expression and nuclear translocation of the redox-sensitive transcription factor Nrf2. Moreover, hyperglycemia caused a pro-inflammatory response by activating NFĸB-AP-1 pathway and IL-6 secretion. Hyperglycemia reduced eNOS gene expression and NO levels, while increasing ET-1 gene expression. Importantly, insulin counteracted all the deleterious effects of hyperglycemia. Collectively, these results demonstrate that hyperglycemia dysregulated redox, inflammatory and vasoactive markers in cerebral endothelial cells. Insulin exerted a protective action against hyperglycemia effects. Thus, it will be of high interest to evaluate the benefits of antioxidant and anti-inflammatory strategies against hyperglycemia-mediated vascular complications in type 2 diabetes.

Effects of Hepatic Ischemia-Reperfusion Injuries and NRF2 on Transcriptional Activities of Bile Transporters in Rats

BACKGROUND

The effect of hepatic ischemia-reperfusion injury (IRI) on bile transporter (BT) gene expression is unknown. We hypothesized that abnormal expression of BTs during hepatic IRI is dependent on nuclear factor erythroid 2-related factor 2 (NRF2), which contributes to the cholestasis after reperfusion.

METHODS

Sham surgery and short (60 min) or long (90 min) periods of warm ischemia time (WIT) with or without reperfusion for 24 h were applied to wild-type Sprague-Dawley rats and Nrf2 knockout rats (n = 5 per group). At each stage of IRI, the serum levels of aminotransferase, total bilirubin, and bile acids were measured. In addition, hepatic tissue was sampled to determine the histologic score of IRI (Suzuki score), measure adenosine triphosphate (ATP), and identify the quantitative real-time polymerase chain reactions of BTs (Oatp1, Ntcp, Mrp2, Bsep, and Mrp3).

RESULTS

In short periods of WIT, BT expression increased during the ischemia stage and returned to the baseline after reperfusion. However, in long periods of WIT, BT expression did not increase after ischemia and decreased further after reperfusion. Short WIT did not increase BT expression in Nrf2 knockout animals. The level of BT expression was correlated with the Suzuki score, the serum levels of aminotransferase, bilirubin, and bile acids, and tissue ATP level. Stepwise multiple regression analysis derived equations to predict the Suzuki score (R² = 76.8, P < 0.001), serum total bilirubin (R² = 61.2, P < 0.001), and tissue ATP (R² = 61.1, P < 0.001).

CONCLUSIONS

Short WIT induces the transcriptional activities of BT, whereas long WIT depresses them, and the effect was blunted by Nrf2 knockout status. BT expression can be considered a surrogate marker for hepatic IRI.

High salt intake shifts the mechanisms of flow-induced dilation in the middle cerebral arteries of Sprague-Dawley rats

The goal of the present study was to examine the effect of 1 wk of high salt (HS) intake and the role of oxidative stress in changing the mechanisms of flow-induced dilation (FID) in isolated pressurized middle cerebral arteries of male Sprague-Dawley rats ( n = 15–16 rats/group). Reduced FID in the HS group was restored by intake of the superoxide scavenger tempol (HS + tempol in vivo group). The nitric oxide (NO) synthase inhibitor Nω-nitro-l-arginine methyl ester, cyclooxygenase inhibitor indomethacin, and selective inhibitor of microsomal cytochrome P-450 epoxidase activity N-(methylsulfonyl)-2-(2-propynyloxy)-benzenehexanamide significantly reduced FID in the low salt diet-fed group, whereas FID in the HS group was mediated by NO only. Cyclooxygenase-2 mRNA (but not protein) expression was decreased in the HS and HS + tempol in vivo groups. Hypoxia-inducible factor-1α and VEGF protein levels were increased in the HS group but decreased in the HS + tempol in vivo group. Assessment by direct fluorescence of middle cerebral arteries under flow revealed significantly reduced vascular NO levels and increased superoxide/reactive oxygen species levels in the HS group. These results suggest that HS intake impairs FID and changes FID mechanisms to entirely NO dependent, in contrast to the low-salt diet-fed group, where FID is NO, prostanoid, and epoxyeicosatrienoic acid dependent. These changes were accompanied by increased lipid peroxidation products in the plasma of HS diet-fed rats, increased vascular superoxide/reactive oxygen species levels, and decreased NO levels, together with increased expression of hypoxia-inducible factor-1α and VEGF.

NEW & NOTEWORTHY High-salt (HS) diet changes the mechanisms of flow-induced dilation in rat middle cerebral arteries from a combination of nitric oxide-, prostanoid-, and epoxyeicosatrienoic acid-dependent mechanisms to, albeit reduced, a solely nitric oxide-dependent dilation. In vivo reactive oxygen species scavenging restores flow-induced dilation in HS diet-fed rats and ameliorates HS-induced increases in the transcription factor hypoxia-inducible factor-1α and expression of its downstream target genes.

Oxidative Stress, Intrauterine Growth Restriction, and Developmental Programming of Type 2 Diabetes

Intrauterine growth restriction (IUGR) leads to reduced birth weight and the development of metabolic diseases such as Type 2 diabetes in adulthood. Mitochondria dysfunction and oxidative stress are commonly found in key tissues (pancreatic islets, liver, and skeletal muscle) of IUGR individuals. In this review, we explore the role of oxidative stress in IUGR-associated diabetes etiology.

Activation of Nrf2 signaling by salvianolic acid C attenuates NF‑κB mediated inflammatory response both in vivo and in vitro

Neurodegenerative diseases are closely related to neuroinflammation. Drugs targeting inflammation have been proved to be effective in many animal models. Salvianolic acid C (SalC) is a compound isolated from Salvia miltiorrhiza Bunge, a plant with reported effects of inhibiting inflammation. However, the anti-inflammation effects and biological mechanisms of SalC on LPS-stimulated neuroinflammation remain unknown. The aim of this paper was to study its protective effects and its anti-inflammation mechanisms. LPS was used both in vivo and in vitro to induce neuroinflammation in SD rats and microglia cells. MTT assay was carried out to detect cell viability. The levels of TNF‑α, IL‑1β, IL‑6, IL‑10 and PGE₂ were detected by ELISA method. The expressions of p‑AMPK, p‑NF‑κB p65, p‑IκBα, Nrf2, HO‑1 and NQO1 proteins were examined by Western blot analysis. The nuclear translocation of NF‑κB p65 was studied by immunofluorescence assay. The specific Nrf2 siRNA was used to clarify the interaction between Nrf2 and NF‑κB p65. The AMPK inhibitor Compound C was used study the upstream protein of Nrf2. Results showed that LPS induced the overexpression of inflammatory cytokines and mediated the phosphorylation and nuclear translocation of NF‑κB p65 in rat brains and microglia cells. SalC reversed the inflammatory response induced by LPS and inhibited the NF‑κB activation. SalC also upregulated the expression of p‑AMPK, Nrf2, HO‑1 and NQO1. But the anti-inflammation and NF‑κB inhibition effects of SalC were attenuated by transfection with specific Nrf2 siRNA or interference with the potent AMPK inhibitor Compound C. In conclusion, SalC inhibited LPS-induced inflammatory response and NF‑κB activation through the activation of AMPK/Nrf2 signaling both in vivo and in vitro.

Antifatigue Potential Activity of Sarcodon imbricatus in Acute Excise-Treated and Chronic Fatigue Syndrome in Mice via Regulation of Nrf2-Mediated Oxidative Stress

Sarcodon imbricatus (SI), a precious edible fungus, contains 35.22% of total sugar, 18.33% of total protein, 24 types of fatty acid, 16 types of amino acid, and 8 types of minerals. Encouragingly, it is rich in potential antioxidants such as total polyphenols (0.41%), total sterols (3.16%), and vitamins (0.44%). In the present study, the antifatigue properties of SI and its potential mechanisms of action were explored by the experiments on acute excise-treated mice and chronic fatigue syndrome (CFS) mice. SI (0.25, 0.5, and 1 g/kg) significantly enhanced exercise tolerance in the weight-loaded forced swimming test (FST) and rota-rod test (RRT) and reduced the immobility in the tail suspension test on CFS mice. SI markedly increased the levels of glycogen in the liver and adenosine triphosphate (ATP) in the liver and muscle and decreased the lactic acid (LD) and blood urea nitrogen (BUN) content in both acute swimming-treated mice and CFS mice. SI improved the endogenous cellular antioxidant enzyme contents in the two mouse models by improving the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and reducing reactive oxygen species (ROS) and malondialdehyde (MDA) levels in serum, liver, and muscle, respectively. In CFS mice, the enhanced expression levels of nuclear factor erythroid-2-related factor 2 (Nrf2), SOD1, SOD2, heme oxygenase-1 (HO-1), and catalase (CAT) in the liver were observed after a 32-day SI administration. Our data indicated that SI possessed antifatigue activity, which may be related to its ability to normalize energy metabolism and Nrf2-mediated oxidative stress. Consequently, SI can be expected to serve as a novel natural antifatigue supplement in health foods.

NFE2-Related Transcription Factor 2 Coordinates Antioxidant Defense with Thyroglobulin Production and Iodination in the Thyroid Gland

BACKGROUND

The thyroid gland has a special relationship with oxidative stress. While generation of oxidative substances is part of normal iodide metabolism during thyroid hormone synthesis, the gland must also defend itself against excessive oxidation in order to maintain normal function. Antioxidant and detoxification enzymes aid thyroid cells to maintain homeostasis by ameliorating oxidative insults, including during exposure to excess iodide, but the factors that coordinate their expression with the cellular redox status are not known. The antioxidant response system comprising the ubiquitously expressed NFE2-related transcription factor 2 (Nrf2) and its redox-sensitive cytoplasmic inhibitor Kelch-like ECH-associated protein 1 (Keap1) defends tissues against oxidative stress, thereby protecting against pathologies that relate to DNA, protein, and/or lipid oxidative damage. Thus, it was hypothesized that Nrf2 should also have important roles in maintaining thyroid homeostasis.

METHODS

Ubiquitous and thyroid-specific male C57BL6J Nrf2 knockout (Nrf2-KO) mice were studied. Plasma and thyroids were harvested for evaluation of thyroid function tests by radioimmunoassays and of gene and protein expression by real-time polymerase chain reaction and immunoblotting, respectively. Nrf2-KO and Keap1-KO clones of the PCCL3 rat thyroid follicular cell line were generated using CRISPR/Cas9 technology and were used for gene and protein expression studies. Software-predicted Nrf2 binding sites on the thyroglobulin enhancer were validated by site-directed in vitro mutagenesis and chromatin immunoprecipitation.

RESULTS

The study shows that Nrf2 mediates antioxidant transcriptional responses in thyroid cells and protects the thyroid from oxidation induced by iodide overload. Surprisingly, it was also found that Nrf2 has a dramatic impact on both the basal abundance and the thyrotropin-inducible intrathyroidal abundance of thyroglobulin (Tg), the precursor protein of thyroid hormones. This effect is mediated by cell-autonomous regulation of Tg gene expression by Nrf2 via its direct binding to two evolutionarily conserved antioxidant response elements in an upstream enhancer. Yet, despite upregulating Tg levels, Nrf2 limits Tg iodination both under basal conditions and in response to excess iodide.

CONCLUSIONS

Nrf2 exerts pleiotropic roles in the thyroid gland to couple cell stress defense mechanisms to iodide metabolism and the thyroid hormone synthesis machinery, both under basal conditions and in response to excess iodide.

Evaluation of Vascular Control Mechanisms Utilizing Video Microscopy of Isolated Resistance Arteries of Rats

This protocol describes the use of in vitro television microscopy to evaluate vascular function in isolated cerebral resistance arteries (and other vessels), and describes techniques for evaluating tissue perfusion using Laser Doppler Flowmetry (LDF) and microvessel density utilizing fluorescently labeled Griffonia simplicifolia (GS1) lectin. Current methods for studying isolated resistance arteries at transmural pressures encountered in vivo and in the absence of parenchymal cell influences provide a critical link between in vivo studies and information gained from molecular reductionist approaches that provide limited insight into integrative responses at the whole animal level. LDF and techniques to selectively identify arterioles and capillaries with fluorescently-labeled GS1 lectin provide practical solutions to enable investigators to extend the knowledge gained from studies of isolated resistance arteries. This paper describes the application of these techniques to gain fundamental knowledge of vascular physiology and pathology in the rat as a general experimental model, and in a variety of specialized genetically engineered "designer" rat strains that can provide important insight into the influence of specific genes on important vascular phenotypes. Utilizing these valuable experimental approaches in rat strains developed by selective breeding strategies and new technologies for producing gene knockout models in the rat, will expand the rigor of scientific premises developed in knockout mouse models and extend that knowledge to a more relevant animal model, with a well understood physiological background and suitability for physiological studies because of its larger size.

KEAP1 and Done? Targeting the NRF2 Pathway with Sulforaphane

BACKGROUND

Since the re-discovery of sulforaphane in 1992 and the recognition of the bioactivity of this phytochemical, many studies have examined its mode of action in cells, animals and humans. Broccoli, especially as young sprouts, is a rich source of sulforaphane and broccoli-based preparations are now used in clinical studies probing efficacy in health preservation and disease mitigation. Many putative cellular targets are affected by sulforaphane although only one, KEAP1-NRF2 signaling, can be considered a validated target at this time. The transcription factor NRF2 is a master regulator of cell survival responses to endogenous and exogenous stressors.

SCOPE AND APPROACH

This review summarizes the chemical biology of sulforaphane as an inducer of NRF2 signaling and efficacy as an inhibitor of carcinogenesis. It also provides a summary of the current findings from clinical trials using a suite of broccoli sprout preparations on a series of short-term endpoints reflecting a diversity of molecular actions.

KEY FINDINGS AND CONCLUSIONS

Sulforaphane, as a pure chemical, protects against chemical-induced skin, oral, stomach, colon, lung and bladder carcinogenesis and in genetic models of colon and prostate carcinogenesis. In many of these settings the antitumorigenic efficacy of sulforaphane is dampened in Nrf2-disrupted animals. Broccoli preparations rich in glucoraphanin or sulforaphane exert demonstrable pharmacodynamic action in over a score of clinical trials. Measures of NRF2 pathway response and function are serving as guideposts for the optimization of dose, schedule and formulation as clinical trials with broccoli-based preparations become more commonplace and more rigorous in design and implementation.

Cardiac and renal upregulation of Nox2 and NF-κB and repression of Nox4 and Nrf2 in season- and diabetes-mediated models of vascular oxidative stress in guinea-pig and rat

The superoxide-forming NADPH oxidase homologues, Nox1, Nox2, and Nox5, seem to mediate the pro-atherosclerotic vascular phenotype. The hydrogen peroxide-forming Nox4 afforded vascular protection, likely via NF-E2-related factor-2 (Nrf2) activation and/or Nox2 downregulation in transgenic mice. We hypothesized that oxidative stress in the intact vasculature involves, aside from the upregulation of the superoxide-forming Noxs, the downregulation of the Nox4/Nrf2 pathway. Guinea-pigs and rats were studied either in winter or in summer, and the streptozotocin diabetic rats in winter. Plasma nitrite, and superoxide production by isolated hearts were measured, while frozen tissues served in biochemical analyses. Summer in both species and diabetes in rats downregulated myocardial Nox4 while reciprocally upregulating Nox2 and Nox5 in guinea-pigs, and Nox2 in rats. Simultaneously, myocardial Nrf2 activity and the expression of the Nrf2-directed heme oxygenase-1 and endothelial NO synthase were reduced while activity of the nuclear factor κB (NF-κB) and the expression of NF-κB-directed inducible NO synthase and the vascular cell adhesion molecule-1 were increased. Cardiac superoxide production was increased while plasma nitrite was decreased reciprocally. Analogous disregulation of Noxs, Nrf2, and NF-κB, occurred in diabetic rat kidneys. Given the diversity of the experimental settings and the uniform pattern of the responses, we speculate that: (1) chronic vascular oxidative stress is a nonspecific (model-, species-, organ-independent) response involving the induction of Nox2 (and Nox5 in guinea-pigs) and the NF-κB pathway, and the repression of Nox4 and the Nrf2 pathway; and (2) the systems Nox2-NF-κB and Nox4-Nrf2 regulate each other negatively.