Estrogen receptor and PI3K/Akt signaling pathway involvement in S-(-)equol-induced activation of Nrf2/ARE in endothelial cells

The cardiovascular toxicity of polystyrene microplastics in rats: based on untargeted metabolomics analysis

Background

Polystyrene microplastics (PS-MPs) exhibit multi-target, multi-dimensional, chronic, and low toxicity to the cardiovascular system. They enter the bloodstream through the gastrointestinal tract and respiratory system, altering blood parameters and conditions, inducing thrombotic diseases, and damaging myocardial tissue through the promotion of oxidative stress and inflammatory responses in myocardial cells. However, many of the links and mechanisms remain unclear.

Methods

In this study, 48 wistar rats were randomly divided into four groups and exposed to different concentrations of PS-MPs: control group (0 mg/kg/d), low dose group (0.5 mg/kg/d), middle dose group (5 mg/kg/d) and high dose group (50 mg/kg/d), with 12 rats in each group. After 90 consecutive days of intragastric administration of PS-MPs, biochemical markers in myocardium, aorta and blood were detected, and HE staining was performed to observe the toxic effects of PS-mps on cardiovascular system. Furthermore, non-targeted metabolomics methods were used to analyze the effect of PS-MPs exposure on the metabolism of cardiovascular system in rats, and to explore its potential molecular mechanism.

Results

The results revealed no pathological changes in the heart and aorta following PS-MPs exposure. However, the myocardial enzyme levels in the high dose PS-MPs group of rats showed a significant increase. Moreover, exposure to polystyrene microplastics caused a disorder in lipid metabolism in rats, and led to an increase in indicators of inflammation and oxidative stress in myocardial and aortic tissues, but resulted in a decrease in the level of IL-6. Untargeted metabolomics results showed that metabolites with antioxidant and anti-inflammatory effects, including equol and 4-hydroxybenzoic acid, were significantly upregulated.

Conclusion

These results suggest that long-term exposure to high concentrations of PS-MPs may lead to abnormal lipid metabolism and cardiovascular system damage. The mechanism may be related to oxidative stress and inflammatory response. Exogenous antioxidants and changes in own metabolites may have a protective effect on the injury. Therefore, understanding the toxicological mechanism of PS-MPs not only helps to elucidate its pathogenesis, but also provides new ideas for the treatment of chronic diseases.

An insight into role of amino acids as antioxidants via NRF2 activation

Oxidative stress can affect the protein, lipids, and DNA of the cells and thus, play a crucial role in several pathophysiological conditions. It has already been established that oxidative stress has a close association with inflammation via nuclear factor erythroid 2-related factor 2 (NRF2) signaling pathway. Amino acids are notably the building block of proteins and constitute the major class of nitrogen-containing natural products of medicinal importance. They exhibit a broad spectrum of biological activities, including the ability to activate NRF2, a transcription factor that regulates endogenous antioxidant responses. Moreover, amino acids may act as synergistic antioxidants as part of our dietary supplementations. This has aroused research interest in the NRF2-inducing activity of amino acids. Interestingly, amino acids' activation of NRF2-Kelch-like ECH-associated protein 1 (KEAP1) signaling pathway exerts therapeutic effects in several diseases. Therefore, the present review will discuss the relationship between different amino acids and activation of NRF2-KEAP1 signaling pathway pinning their anti-inflammatory and antioxidant properties. We also discussed amino acids formulations and their applications as therapeutics. This will broaden the prospect of the therapeutic applications of amino acids in a myriad of inflammation and oxidative stress-related diseases. This will provide an insight for designing and developing new chemical entities as NRF2 activators.

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.

Modulation of inflammatory, oxidative, and apoptotic stresses mediates the renoprotective effect of daidzein against glycerol-induced acute kidney injury in rats

Acute kidney injury (AKI) is a life-threatening complication that accompanies rhabdomyolysis. Daidzein is a dietary isoflavone that has various biological activities. This study examined the therapeutic potential of daidzein and the underlying mechanisms against AKI induced by glycerol in male rats. Animals were injected once with glycerol (50%, 10 ml/kg, intramuscular) for induction of AKI and pre-treated orally with daidzein (25, 50, and 100 mg/kg) for 2 weeks. Biochemical, histopathological, immunohistopathological, and molecular parameters were assessed to evaluate the effect of daidzein. The results revealed that the model group displayed remarkable functional, molecular, and structural changes in the kidney. However, pre-administration of daidzein markedly decreased the kidney relative weight as well as the levels of urea, creatinine, K, P, kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), and cystatin C. Further, daidzein lessened the rhabdomyolysis-related markers [lactate dehydrogenase (LDH) and creatine kinase (CK)]. Notably, the enhancement of the antioxidant biomarkers [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and reduced glutathione (GSH) is accompanied by a decrease in malondialdehyde (MDA) and nitric oxide (NO) levels. Moreover, upregulated gene expression levels of nuclear factor erythroid 2-related factor 2 (Nfe212) and hemeoxygenase-1 (Hmox1) were exerted by daidzein administration. Rats who received daidzein displayed markedly lower interleukin-1β (IL-1β), tumor nuclear factor-α (TNF-α), myleoperoxidase (MPO), and nuclear factor kappa B (NF-κB) levels together with higher interleukin-10 (IL-10) related to the model group. Remarkably, significant declines were noticed in the pro-apoptotic (Bax and caspase-3) and rises in antiapoptotic (Bcl-2) levels in the group that received daidzein. The renal histological screening validated the aforementioned biochemical and molecular alterations. Our findings support daidzein as a potential therapeutic approach against AKI-induced renal injury via suppression of muscle degradation, oxidative damage, cytokine release, and apoptosis.

Estrogenic flavonoids and their molecular mechanisms of action

Flavonoids are a major group of phytoestrogens associated with physiological effects, and ecological and social impacts. Although the estrogenic activity of flavonoids was reported by researchers in the fields of medical, environmental and food studies, their molecular mechanisms of action have not been comprehensively reviewed. The estrogenic activity of the respective classes of flavonoids, anthocyanidins/anthocyanins, 2-arylbenzofurans/3-arylcoumarins/α-methyldeoxybenzoins, aurones/chalcones/dihydrochalcones, coumaronochromones, coumestans, flavans/flavan-3-ols/flavan-4-ols, flavanones/dihydroflavonols, flavones/flavonols, homoisoflavonoids, isoflavans, isoflavanones, isoflavenes, isoflavones, neoflavonoids, oligoflavonoids, pterocarpans/pterocarpenes, and rotenone/rotenoids, was summarized through a comprehensive literature search, and their structure-activity relationship, biological activities, signaling pathways, and applications were discussed. Although the respective classes of flavonoids contained at least one chemical mimicking estrogen, the mechanisms varied, such as those with estrogenic, anti-estrogenic, non-estrogenic, and biphasic activities, and additional activities through crosstalk/bypassing, which exert biological activities through cell signaling pathways. Such mechanistic variations of estrogen action are not limited to flavonoids and are observed among other broad categories of chemicals, thus this group of chemicals can be termed as the "estrogenome". This review article focuses on the connection of estrogen action mainly between the outer and the inner environments, which represent variations of chemicals and biological activities/signaling pathways, respectively, and form the basis to understand their applications. The applications of chemicals will markedly progress due to emerging technologies, such as artificial intelligence for precision medicine, which is also true of the study of the estrogenome including estrogenic flavonoids.

Therapeutic antischizophrenic activity of prodigiosin and selenium co-supplementation against amphetamine hydrochloride-induced behavioural changes and oxidative, inflammatory, and apoptotic challenges in rats

Schizophrenia (SCZ), a multifactorial neuropsychiatric disorder, is treated with inefficient antipsychotics and linked to poor treatment outcomes. This study, therefore, investigated the combined administration of prodigiosin (PDG) and selenium (Na₂SeO₃) against SCZ induced by amphetamine (AMPH) in rats. Animals were allocated into four groups corresponding to their respective 7-day treatments: control, AMPH (2 mg/kg), PDG (300 mg/kg) + Na₂SeO₃ (2 mg/kg), and AMPH + PDG + Na₂SeO₃. The model group exhibited biochemical, molecular, and histopathological changes similar to those of the SCZ group. Contrastingly, co-administration of PDG and Na₂SeO₃ significantly increased the time for social interaction and decreased AChE and dopamine. It also downregulated the gene expression of NMDAR1 and restored neurotrophin (BDNF and NGF) levels. Further, PDG combined with Na₂SeO₃ improved the antioxidant defence of the hippocampus by boosting the activities of SOD, CAT, GPx, and GR. These findings were accompanied by an increased GSH, alongside decreased MDA and NO levels. Furthermore, schizophrenic rats having received PDG and Na₂SeO₃ displayed markedly lower IL-1β and TNF-α levels compared to the model group. Interestingly, remarkable declines in the Bax (pro-apoptotic) and increases in Bcl-2 (anti-apoptotic) levels were observed in the SCZ group that received PDG and Na₂SeO₃. The hippocampal histological examination confirmed these changes. Collectively, these findings show that the co-administration of PDG and Na₂SeO₃ may have a promising therapeutic effect for SCZ. This is mediated by mechanisms related to the modulation of cholinergic, dopaminergic, and glutaric neurotransmission and neurotrophic factors, alongside the suppression of oxidative damage, neuroinflammation, and apoptosis machinery.

Anti-Inflammatory Activity of Geraniol Isolated from Lemon Grass on Ox-LDL-Stimulated Endothelial Cells by Upregulation of Heme Oxygenase-1 via PI3K/Akt and Nrf-2 Signaling Pathways

Among the world's leading causes of cardiovascular disease, atherosclerosis is a chronic inflammatory disorder that affects the arteries. Both vasodilation and vasoconstriction, low levels of nitric oxide and high levels of reactive oxygen species and pro-inflammatory factors characterize dysfunctional blood vessels. Hypertension, and atherosclerosis, all start with this dysfunction. Geraniol, a compound of acyclic monoterpene alcohol, found in plants such as geranium, lemongrass and rose, is a primary constituent of essential oils. It shows a variety of pharmacological properties. This study aimed to investigate the impact of geraniol on Ox-LDL-induced stress and inflammation in human umbilical vein endothelial cells. In this study, HUVECs were treated with Ox-LDL or geraniol at different dose concentrations. MTT assay, Western blot, ROS generation and DNA fragmentation were used to evaluate geraniol's effects on Ox-LDL-induced HUVECs inflammation. The results show that geraniol pre-incubation ameliorates Ox-LDL-mediated HUVECs cytotoxicity and DNA fragmentation. The geraniol inhibited the production of pro-inflammatory cytokines by Ox-LDL, including TNF-α, IL-6 and IL-1β. In Ox-LDL-stimulated HUVECs, geraniol suppresses the nuclear translocation and activity of NF-ᴋB as well as phosphorylation of IkBα. Moreover, geraniol activated the PI3K/AKT/NRF2 pathway in HUVECs, resulting in an increase in the expression of HO-1. Taking our data together, we can conclude that, in HUVECs, geraniol inhibits Ox-LDL-induced inflammation and oxidative stress by targeting PI3/AKT/NRF2.

Potential Protective Mechanisms of S-equol, a Metabolite of Soy Isoflavone by the Gut Microbiome, on Cognitive Decline and Dementia

S-equol, a metabolite of soy isoflavone daidzein transformed by the gut microbiome, is the most biologically potent among all soy isoflavones and their metabolites. Soy isoflavones are phytoestrogens and exert their actions through estrogen receptor-β. Epidemiological studies in East Asia, where soy isoflavones are regularly consumed, show that dietary isoflavone intake is inversely associated with cognitive decline and dementia; however, randomized controlled trials of soy isoflavones in Western countries did not generally show their cognitive benefit. The discrepant results may be attributed to S-equol production capability; after consuming soy isoflavones, 40-70% of East Asians produce S-equol, whereas 20-30% of Westerners do. Recent observational and clinical studies in Japan show that S-equol but not soy isoflavones is inversely associated with multiple vascular pathologies, contributing to cognitive impairment and dementia, including arterial stiffness and white matter lesion volume. S-equol has better permeability to the blood-brain barrier than soy isoflavones, although their affinity to estrogen receptor-β is similar. S-equol is also the most potent antioxidant among all known soy isoflavones. Although S-equol is available as a dietary supplement, no long-term trials in humans have examined the effect of S-equol supplementation on arterial stiffness, cerebrovascular disease, cognitive decline, or dementia.

Role of Nuclear Factor Erythroid 2 (Nrf2) in the Recovery of Long COVID-19 Using Natural Antioxidants: A Systematic Review

Coronavirus disease 2019 (COVID-19) is an infectious disease with approximately 517 million confirmed cases, with the average number of cases revealing that patients recover immediately without hospitalization. However, several other cases found that patients still experience various symptoms after 3–12 weeks, which is known as a long COVID syndrome. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can activate nuclear factor kappa beta (NF-κβ) and unbind the nuclear factor erythroid 2-related factor 2 (Nrf2) with Kelch-like ECH-associated protein 1 (Keap1), causing inhibition of Nrf2, which has an important role in antioxidant response and redox homeostasis. Disrupting the Keap1–Nrf2 pathway enhances Nrf2 activity, and has been identified as a vital approach for the prevention of oxidative stress and inflammation. Hence, natural antioxidants from various sources have been identified as a promising strategy to prevent oxidative stress, which plays a role in reducing the long COVID-19 symptoms. Oxygen-rich natural antioxidant compounds provide an effective Nrf2 activation effect that interact with the conserved amino acid residues in the Keap1-binding pocket, such as Ser602, Ser363, Ser508, and Ser555. In this review, the benefits of various natural antioxidant compounds that can modulate the Nrf2 signaling pathway, which is critical in reducing and curing long COVID-19, are highlighted and discussed.

The role of phosphoinositide 3-kinases in immune-inflammatory responses: potential therapeutic targets for abdominal aortic aneurysm

The pathogenesis of abdominal aortic aneurysm (AAA) includes inflammatory responses, matrix metalloproteinases (MMPs) degradation, VSMC apoptosis, oxidative stress, and angiogenesis, among which the inflammatory response plays a key role. At present, surgery is the only curing treatment, and no effective drug can delay AAA progression in clinical practice. Therefore, searching for a signaling pathway related to the immune-inflammatory response is an essential direction for developing drugs targeting AAA. Recent studies have confirmed that the PI3K family plays an important role in many inflammatory diseases and is involved in regulating various cellular functions, especially in the immune-inflammatory response. This review focuses on the role of each isoform of PI3K in each stage of AAA immune-inflammatory response, making available explorations for a deeper understanding of the mechanism of inflammation and immune response during the formation and development of AAA.

Soy-Derived Equol Induces Antioxidant Activity in Zebrafish in an Nrf2-Independent Manner

Antioxidant effects of soy-derived isoflavones are predicted to be mediated by the Keap1-Nrf2 pathway. Recently, we constructed an assay system to evaluate the antioxidant effects of dietary phytochemicals in zebrafish and revealed a relationship between these effects and the Keap1-Nrf2 pathway. In this study, we used this system to examine the antioxidant effects of seven isoflavones. Among those seven, equol showed strong antioxidant effects when arsenite was used as an oxidative stressor. The antioxidant effect of equol was also shown in Nrf2-mutant zebrafish nfe2l2a^fh318, suggesting that this effect was not mediated by the Keap1-Nrf2 pathway. To elucidate this unidentified mechanism, the gene expression profiles of equol-treated larvae were analyzed using RNA-seq and qRT-PCR, while no noticeable changes were detected in the expression of genes related to antioxidant effects, except weak induction of Nrf2 target genes. Because nfe2l2a^fh318 is an amino acid-substitution mutant (Arg485Lue), we considered that the antioxidant effect of equol in this mutant might be due to residual Nrf2 activity. To examine this possibility, we generated an Nrf2-knockout zebrafish nfe2l2a^it321 using CRISPR-Cas9 and analyzed the antioxidant effect of equol. As a result, equol showed strong antioxidant effects even in Nrf2-knockout larvae, suggesting that equol indeed upregulates antioxidant activity in zebrafish in an Nrf2-independent manner.

Redox Activity of Flavonoids: Impact on Human Health, Therapeutics, and Chemical Safety

The cost-effectiveness of presently used therapies is a problem in overall redox-based management, which is posing a significant financial burden on communities across the world. As a result, sophisticated treatment models that provide notions of predictive diagnoses followed by targeted preventive therapies adapted to individual patient profiles are gaining global acclaim as being beneficial to patients, the healthcare sector, and society as a whole. In this context, natural flavonoids were considered due to their multifaceted antioxidant, anti-inflammatory, and anticancer effects as well as their low toxicity and ease of availability. The aim of this review is to focus on the capacity of flavonoids to modulate the responsiveness of various diseases and ailments associated with redox toxicity. The review will also focus on the flavonoids' pathway-based redox activity and the advancement of redox-based therapies as well as flavonoids' antioxidant characteristics and their influence on human health, therapeutics, and chemical safety. Research findings indicated that flavonoids significantly exhibit various redox-based therapeutic responses against several diseases such as inflammatory, neurodegenerative, cardiovascular, and hepatic diseases and various types of cancer by activating the Nrf2/Keap1 transcription system, suppressing the nuclear factor κB (NF-κB)/IκB kinase inflammatory pathway, abrogating the function of the Hsp90/Hsf1 complex, inhibiting the PTEN/PI3K/Akt pathway, and preventing mitochondrial dysfunction. Some flavonoids, especially genistein, apigenin, amentoflavone, baicalein, quercetin, licochalcone A, and biochanin A, play a potential role in redox regulation. Conclusions of this review on the antioxidant aspects of flavonoids highlight the medicinal and folk values of these compounds against oxidative stress and various diseases and ailments. In short, treatment with flavonoids could be a novel therapeutic invention in clinical trials, as we hope.

Small Interfering RNA in Colorectal Cancer Liver Metastasis Therapy

Colorectal cancer (CRC) is associated with numerous genetic disorders and cellular abnormalities, and liver metastasis is a common health concern in patients with CRC. Exploring newer and more efficient therapies to block liver metastasis is pivotal for prolonging patient survival. Therefore, small interfering RNAs (siRNAs) are expected to be remarkable tools capable of regulating gene expression by participating in a process called RNA interference (RNAi). RNAi is a biological process among eukaryotes wherein specific messenger RNA (mRNA) molecules are destroyed and gene expression is inhibited. This technology is a promising therapeutic agent in the treatment of CRC liver metastasis (CRLM). Nevertheless, crucial problems in siRNA therapeutics, including inherent poor serum stability and nonspecific uptake into biological systems, must be recognized. For this reason, delivery systems are being developed in an attempt to solve these problems. Here, we discuss the utility of siRNA therapy for the treatment of CRCLM by targeting the major metastasis-related signaling pathways. siRNA therapy has the potential to be one of the most effective methods for CRLM treatment in the future.

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.

Phytoestrogens (Resveratrol and Equol) for Estrogen-Deficient Skin-Controversies/Misinformation versus Anti-Aging In Vitro and Clinical Evidence via Nutraceutical-Cosmetics

The overarching theme for this review is perspective. Superfoods (a marketing term for fruits and vegetables, etc.) have a positive connotation, while many superfoods contain phytoestrogens, a term that is alarming to the public and has a negative connotation because phytoestrogens are endocrine-disruptors, even though they are strong antioxidants that have many health benefits. To understand phytoestrogens, this paper provides a brief summary of the characteristics of: (a) estrogens, (b) estrogen receptors (ER), (c) estrogen-deficient skin, (d) how perspective(s) get off track, (e) phytoestrogen food sources, and (f) misconceptions of phytoestrogens and food safety, in general, that influence person(s) away from what is true. Finally, a brief history of cosmetics to nutraceuticals is covered plus the characteristics of phytoestrogens, resveratrol and equol on: (g) estrogen receptor binding, (h) topical and oral dosing, and (i) in vitro, molecular mechanisms and select clinical evidence, where both phytoestrogens (resveratrol and equol) demonstrate promising applications to improve skin health is presented along with future directions of nutraceuticals. Perspective is paramount in understanding the controversies associated with superfoods, phytoestrogens, and endocrine-disruptors because they have both positive and negative connotations. Everyone is exposed to and consumes these molecules everyday regardless of age, gender, or geographic location around the world, and how we understand this is a matter of perspective.

Human umbilical cord mesenchymal stem cells reduce oxidative damage and apoptosis in diabetic nephropathy by activating Nrf2

Background

Mesenchymal stem cells (MSCs) have a therapeutic effect on diabetic nephropathy (DN) but the underlying mechanism remains unclear. This study was conducted to investigate whether human umbilical cord-MSCs (hUCMSCs) can induce oxidative damage and apoptosis by activating Nrf2.

Methods

We used a type 2 diabetic rat model and a high-glucose and fat-stimulated human glomerular mesangial cell (hGMC) model. Western blotting, RT-qPCR, and TUNEL staining were performed on animal tissues and cultured cells. Nuclear expression of Nrf2 was detected in the renal tissue. Furthermore, Nrf2 siRNA was used to examine the effects of hUCMSCs on hGMCs. Finally, the effect of hUCMSCs on the Nrf2 upstream signalling pathway was investigated.

Results

After treatment with hUCMSCs, Nrf2 showed increased expression and nuclear translocation. After Nrf2-specific knockout in hGMCs, the protective effect of hUCMSCs on apoptosis induced by high-glucose and fat conditions was reduced. Activation of the PI3K signalling pathway may be helpful for ameliorating DN using hUCMSCs.

Conclusions

hUCMSCs attenuated renal oxidative damage and apoptosis in type 2 diabetes mellitus and Nrf2 activation is one of the important mechanisms of this effect. hUCMSCs show potential as drug targets for DN.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02447-x.

S-Equol Protects Chondrocytes against Sodium Nitroprusside-Caused Matrix Loss and Apoptosis through Activating PI3K/Akt Pathway

Osteoarthritis (OA) is a common chronic disease with increasing prevalence in societies with more aging populations, therefore, it is causing more concern. S-Equol, a kind of isoflavones, was reported to be bioavailable and beneficial to humans in many aspects, such as improving menopausal symptoms, osteoporosis and prevention of cardiovascular disease. This study investigated the effects of S-Equol on OA progress in which rat primary chondrocytes were treated with sodium nitroprusside (SNP) to mimic OA progress with or without the co-addition of S-Equol for the evaluation of S-Equol's efficacy on OA. Results showed treatment of 0.8 mM SNP caused cell death, and increased oxidative stress (NO and H₂O₂), apoptosis, and proteoglycan loss. Furthermore, the expressions of MMPs of MMP-2, MMP-3, MMP-9, and MMP-13 and p53 were increased. The addition of 30 μM S-Equol could lessen those caused by SNP. Moreover, S-Equol activates the PI₃K/Akt pathway, which is an upstream regulation of p53 and NO production and is associated with apoptosis and matrix degradation. As a pretreatment of phosphoinositide ₃-kinases (PI₃K) inhibitor, all S-Equol protective functions against SNP decrease or disappear. In conclusion, through PI₃K/Akt activation, S-Equol can protect chondrocytes against SNP-induced matrix degradation and apoptosis, which are commonly found in OA, suggesting S-Equol is a potential for OA prevention.

Cannabidiol attenuates pulmonary arterial hypertension by improving vascular smooth muscle cells mitochondrial function

Rationale: Pulmonary arterial hypertension (PAH) is a chronic disease associated with enhanced proliferation of pulmonary artery smooth muscle cells (PASMCs) and dysfunctional mitochondria, and the clinical therapeutic option for PAH is very limited. Recent studies showed that cannabidiol (CBD), a non-psychoactive constituent of cannabinoids, possessed antioxidant effect towards several cardiovascular diseases, whereas the mechanistic effect of CBD in PAH is unknown.

Methods: In this study, the effects of CBD in PAH were determined by analyzing its preventive and therapeutic actions in PAH rodent models in vivo and PASMCs' proliferation test in vitro. Additionally, CBD's roles in mitochondrial function and oxidant stress were also assessed in PASMCs.

Results: We found that CBD reversed the pathological changes observed in both Sugen-hypoxia and monocrotaline-induced PAH rodent models in a cannabinoid receptors-independent manner. Our results also demonstrated that CBD significantly inhibited the PASMCs' proliferation in PAH mice with less inflammation and reactive oxygen species levels. Moreover, CBD alleviated rodent PAH by recovering mitochondrial energy metabolism, normalizing the hypoxia-induced oxidant stress, reducing the lactate overaccumulation and abnormal glycolysis.

Conclusions: Taken together, these findings confirm an important role for CBD in PAH pathobiology.

Role of PI3K in the Progression and Regression of Atherosclerosis

Phosphatidylinositol 3 kinase (PI3K) is a key molecule in the initiation of signal transduction pathways after the binding of extracellular signals to cell surface receptors. An intracellular kinase, PI3K activates multiple intracellular signaling pathways that affect cell growth, proliferation, migration, secretion, differentiation, transcription and translation. Dysregulation of PI3K activity, and as aberrant PI3K signaling, lead to a broad range of human diseases, such as cancer, immune disorders, diabetes, and cardiovascular diseases. A growing number of studies have shown that PI3K and its signaling pathways play key roles in the pathophysiological process of atherosclerosis. Furthermore, drugs targeting PI3K and its related signaling pathways are promising treatments for atherosclerosis. Therefore, we have reviewed how PI3K, an important regulatory factor, mediates the development of atherosclerosis and how targeting PI3K can be used to prevent and treat atherosclerosis.

Effect of Quercetin on Lipids Metabolism Through Modulating the Gut Microbial and AMPK/PPAR Signaling Pathway in Broilers

The present study was conducted to investigate effects and mechanism of quercetin on lipids metabolism in broilers. 480 AA broilers were randomly allotted to four treatments (0, 0.2, 0.4, and 0.6 g/kg quercetin) for 42 days. Compared with the control, 0.6 g/kg quercetin significantly decreased percentage of abdominal fat (P < 0.05); 0.2, 0.4, and 0.6 g/kg quercetin significantly decreased relative abundance of Lachnospiraceae and Desulfovibrionaceae (P < 0.05, P < 0.05, P < 0.01; P < 0.01, P < 0.01, P < 0.01); 0.2 g/kg quercetin significantly increased mRNA expression of PI3K, AMPKα1, AMPKα2, AMPKβ2, LKB1 (P < 0.01, P < 0.01, P < 0.05, P < 0.01, P < 0.05), and significantly reduced mRNA expression of SREBP1 and PPARγ (P < 0.01, P < 0.05); 0.4 g/kg quercetin significantly increased mRNA expression of LKB1 and PKB (P < 0.05, P < 0.01) and significantly reduced mRNA expression of ACC, HMGR, PPARγ, and SREBP1 (P < 0.05, P < 0.01, P < 0.01, P < 0.01); 0.6 g/kg quercetin significantly increased mRNA expression of AMPKγ, LKB1, CPT1, PPARα, PKB (P < 0.01, P < 0.01, P < 0.01, P < 0.05, P < 0.05), and significantly reduced the mRNA expression of PI3K, ACC, HMGR, PPARγ, SREBP1 (P < 0.05, P < 0.05, P < 0.01, P < 0.01, P < 0.01); 0.2 g/kg quercetin significantly increased protein expression of AMPK (P < 0.01); 0.6 g/kg quercetin significantly increased protein expression of LKB1 (P < 0.01), 0.2 and 0.6 g/kg quercetin significantly increased protein expression of PI3K, PKB, CPT1 (P < 0.05, P < 0.01, P < 0.05, P < 0.01, P < 0.01, P < 0.01), and significantly reduced protein expression of ACC and SREBP1 (P < 0.01, P < 0.01, P < 0.01, P < 0.01). In conclusion, quercetin improved lipid metabolism by modulating gut microbial and AMPK/PPAR signaling pathway in broilers.

Advancements in therapeutic drugs targeting of senescence

Aging leads to a high burden on society, both medically and economically. Cellular senescence plays an essential role in the initiation of aging and age-related diseases. Recent studies have highlighted the therapeutic value of senescent cell deletion in natural aging and many age-related disorders. However, the therapeutic strategies for manipulating cellular senescence are still at an early stage of development. Among these strategies, therapeutic drugs that target cellular senescence are arguably the most highly anticipated. Many recent studies have demonstrated that a variety of drugs exhibit healthy aging effects. In this review, we summarize different types of drugs promoting healthy aging – such as senolytics, senescence-associated secretory phenotype (SASP) inhibitors, and nutrient signaling regulators – and provide an update on their potential therapeutic merits. Taken together, our review synthesizes recent advancements in the therapeutic potentialities of drugs promoting healthy aging with regard to their clinical implications.

Estrogen Receptors and Estrogen-Induced Uterine Vasodilation in Pregnancy

Normal pregnancy is associated with dramatic increases in uterine blood flow to facilitate the bidirectional maternal–fetal exchanges of respiratory gases and to provide sole nutrient support for fetal growth and survival. The mechanism(s) underlying pregnancy-associated uterine vasodilation remain incompletely understood, but this is associated with elevated estrogens, which stimulate specific estrogen receptor (ER)-dependent vasodilator production in the uterine artery (UA). The classical ERs (ERα and ERβ) and the plasma-bound G protein-coupled ER (GPR30/GPER) are expressed in UA endothelial cells and smooth muscle cells, mediating the vasodilatory effects of estrogens through genomic and/or nongenomic pathways that are likely epigenetically modified. The activation of these three ERs by estrogens enhances the endothelial production of nitric oxide (NO), which has been shown to play a key role in uterine vasodilation during pregnancy. However, the local blockade of NO biosynthesis only partially attenuates estrogen-induced and pregnancy-associated uterine vasodilation, suggesting that mechanisms other than NO exist to mediate uterine vasodilation. In this review, we summarize the literature on the role of NO in ER-mediated mechanisms controlling estrogen-induced and pregnancy-associated uterine vasodilation and our recent work on a “new” UA vasodilator hydrogen sulfide (H₂S) that has dramatically changed our view of how estrogens regulate uterine vasodilation in pregnancy.

Icariin Improves Age-Related Testicular Dysfunction by Alleviating Sertoli Cell Injury via Upregulation of the ERα/Nrf2-Signaling Pathway

Sertoli cells play crucial roles in spermatogenesis and are impaired by aging. Icariin, a flavonoid from Epimedium, has been reported to exhibit anti-aging effects and improve testicular dysfunction in the clinical setting. However, whether icariin improves age-related degeneration of testicular function via protection from Sertoli cell injury remains unclear. In the present study, we evaluated the protective effect of icariin on Sertoli cell injury and explored the possible mechanism(s) in vivo and in vitro. Dietary administration of icariin for 4 months significantly ameliorated the age-related decline in testicular function by increasing testicular and epididymal weights and indices, sperm count and sperm viability, testicular testosterone and estradiol concentrations, and seminiferous tubule diameters and heights. In addition, icariin protected age-related Sertoli cells from injury as evidenced by an analysis of Sertoli cell number, ultrastructure, and function. Such changes were accompanied by upregulation of ERα and Nrf2 signaling in Sertoli cells. Parallel in vitro studies also demonstrated that icariin inhibited untoward effects on the TM4 mouse Sertoli cell line with concomitant upregulation of ERα and Nrf2 signaling. Conversely, ERα siRNA reversed icariin-mediated protection of Sertoli cell injury. Our data suggest that icariin effectively ameliorates age-related degeneration of testicular function by alleviating Sertoli cell injury via the ERα/Nrf2 signal-transduction pathway. Thus, mitigating Sertoli cell damage via the ERα/Nrf2 signaling pathway likely represents a promising strategy for the prevention of age-related testicular dysfunction.

Involvement of Estrogen Receptor-α in the Activation of Nrf2-Antioxidative Signaling Pathways by Silibinin in Pancreatic β-Cells

Silibinin exhibits antidiabetic potential by preserving the mass and function of pancreatic β-cells through up-regulation of estrogen receptor-α (ERα) expression. However, the underlying protective mechanism of silibinin in pancreatic β-cells is still unclear. In the current study, we sought to determine whether ERα acts as the target of silibinin for the modulation of antioxidative response in pancreatic β-cells under high glucose and high fat conditions. Our in vivo study revealed that a 4-week oral administration of silibinin (100 mg/kg/day) decreased fasting blood glucose with a concurrent increase in levels of serum insulin in high-fat diet/streptozotocin-induced type 2 diabetic rats. Moreover, expression of ERα, NF-E2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1) in pancreatic β-cells in pancreatic islets was increased by silibinin treatment. Accordingly, silibinin (10 μM) elevated viability, insulin biosynthesis, and insulin secretion of high glucose/palmitate-treated INS-1 cells accompanied by increased expression of ERα, Nrf2, and HO-1 as well as decreased reactive oxygen species production in vitro. Treatment using an ERα antagonist (MPP) in INS-1 cells or silencing ERα expression in INS-1 and NIT-1 cells with siRNA abolished the protective effects of silibinin. Our study suggests that silibinin activates the Nrf2-antioxidative pathways in pancreatic β-cells through regulation of ERα expression.

The protective effects of GLP-1 receptor agonist lixisenatide on oxygen-glucose deprivation/reperfusion (OGD/R)-induced deregulation of endothelial tube formation

Acute myocardial infarction (AMI) is a complication of atherosclerosis that takes place in coronary arteries. Cardiac endothelial cells play a significant role in the pathogenesis of AMI. Oxygen-glucose deprivation/reperfusion (OGD/R) is widely used as a model to simulate AMI in vitro. Recently, antidiabetic GLP-1 receptor agonists have been shown to exert pleiotropic effects that modulate cardiovascular complications. In this study, we investigated the vascular effect of lixisenatide. We show that pre-treatment of endothelial cells with lixisenatide protected them from OGD/R-induced cytotoxicity and improved their viability. Pre-treatment with lixisenatide ameliorated OGD/R-induced ROS accumulation and disturbed endothelial tube formation. At the molecular level, lixisenatide mitigated OGD/R-induced reduced eNOS expression and NO production but further promoted the expression of the anti-oxidant regulators Nrf2 and HO-1. Mechanistically, we confirmed that the PI3K/Akt pathway is essential for mediating the effects of lixisenatide, and blockage of PI3K/Akt using the inhibitor LY294002 abolished the ameliorative effect of lixisenatide on ROS production and impaired tube formation. These data indicate that lixisenatide possesses a beneficial effect on the vasculature in a model of ischemia-induced endothelial injury. We conclude that the GLP-1 receptor agonist lixisenatide has pleiotropic properties that can modulate vascular function independent of its anti-glycemic effect.

Acute myocardial infarction (AMI) is a complication of atherosclerosis that takes place in coronary arteries.

Recent advances in the anti-aging effects of phytoestrogens on collagen, water content, and oxidative stress

Skin undergoes degenerative changes as it ages, which include the loss of elasticity, reductions in the epidermal thickness and collagen content, elastic fiber degeneration, and increased wrinkling and dryness. Skin aging can be significantly delayed by the administration of estrogen. Estrogen deficiency following menopause results in atrophic skin changes and the acceleration of skin aging. Estrogen administration has positive effects on human skin by delaying or preventing skin aging manifestations, but the use of estrogen replacement is a risk factor for breast and uterine cancer. Phytoestrogens are a large family of plant‐derived molecules possessing various degrees of estrogen‐like activity; they exhibit agonist or antagonist estrogenic properties depending on the tissue. These molecules could be ideal candidates to combat skin aging and other detrimental effects of hypoestrogenism. In this paper, we review the effects of phytoestrogens on human skin and the mechanisms by which phytoestrogens can alleviate the changes due to aging.

Dietary Polyphenols Targeting Arterial Stiffness: Interplay of Contributing Mechanisms and Gut Microbiome-Related Metabolism

Increased arterial stiffness is a degenerative vascular process, progressing with age that leads to a reduced capability of arteries to expand and contract in response to pressure changes. This progressive degeneration mainly affects the extracellular matrix of elastic arteries and causes loss of vascular elasticity. Recent studies point to significant interference of dietary polyphenols with mechanisms involved in the pathophysiology and progression of arterial stiffness. This review summarizes data from epidemiological and interventional studies on the effect of polyphenols on vascular stiffness as an illustration of current research and addresses possible etiological factors targeted by polyphenols, including pathways of vascular functionality, oxidative status, inflammation, glycation, and autophagy. Effects can either be inflicted directly by the dietary polyphenols or indirectly by metabolites originated from the host or microbial metabolic processes. The composition of the gut microbiome, therefore, determines the resulting metabolome and, as a consequence, the observed activity. On the other hand, polyphenols also influence the intestinal microbial composition, and therefore the metabolites available for interaction with relevant targets. As such, targeting the gut microbiome is another potential treatment option for arterial stiffness.

Conventional and electronic cigarettes dysregulate the expression of iron transporters and detoxifying enzymes at the brain vascular endothelium: In vivo evidence of a gender-specific cellular response to chronic cigarette smoke exposure

It is well established that tobacco smoking is associated with vascular endothelial dysfunction in a causative and dose dependent manner primarily related to the tobacco smoke (TS) content of reactive oxygen species (ROS), nicotine, and oxidative stress (OS) -driven inflammation. Preclinical studies have also shown that nicotine (the principal e-liquid's ingredient used in e-cigarettes (e-Cigs) can also cause OS, exacerbation of cerebral ischemia and secondary brain injury. Likewise, chronic e-Cig vaping could be prodromal to vascular endothelial dysfunctions. Herein, we provide direct evidence that similarly to TS, e-Cig promotes mitochondrial depolarization in primary brain vascular endothelial cells as well as the vascular endothelial cell line bEnd3. In addition, both TS and e-Cig exposure upregulated the transmembrane iron exporter Slc40a1 (crucial to maintain cellular iron and redox homeostasis) and that of porphyrin importer Abcb6 (linked to accelerated atherosclerosis). We then investigated in vivo whether gender plays a role in how chronic TS affect vascular endothelial functions. Our results clearly show chronic TS exposure differentially impacts the expression levels of Phase-II enzymes as well as the iron transporters previously investigated in vitro. Although the physiological implications of the gender-specific differential responses to TS are not fully clear, they do demonstrate that gender is a risk factor that needs to be investigated when assessing the potential impact of chronic smoking and perhaps e-Cig vaping.

Rhodobacter sphaeroides Extract Lycogen™ Attenuates Testosterone-Induced Benign Prostate Hyperplasia in Rats

Benign prostate hyperplasia (BPH) is one of the most common urological problems in mid-aged to elderly men. Risk factors of BPH include family history, obesity, type 2 diabetes, and high oxidative stress. The main medication classes for BPH management are alpha blockers and 5α-reductase inhibitors. However, these conventional medicines cause adverse effects. Lycogen™, extracted from Rhodobacter sphaeroides WL-APD911, is an anti-oxidant and anti-inflammatory compound. In this study, the effect of Lycogen™ was evaluated in rats with testosterone-induced benign prostate hyperplasia (BPH). Testosterone injections and Lycogen™ administration were carried out for 28 days, and body weights were recorded twice per week. The testosterone injection successfully induced a prostate enlargement. BPH-induced rats treated with different doses of Lycogen™ exhibited a significantly decreased prostate index (PI). Moreover, the Lycogen™ administration recovered the histological abnormalities observed in the prostate of BPH rats. In conclusion, these findings support a dose-dependent preventing effect of Lycogen™ on testosterone-induced BPH in rats and suggest that Lycogen™ may be favorable to the prevention and management of benign prostate hyperplasia.

Daidzein ameliorates spinal cord ischemia/reperfusion injury-induced neurological function deficits in Sprague-Dawley rats through PI3K/Akt signaling pathway

Daidzein (DZ) has a broad spectrum of biological activities, including antioxidant, anti-inflammatory and anticancer as well as cardio- and hepatoprotective properties. The present study was designed to elucidate the in-depth mechanism underlying the neuroprotective efficacy of DZ against spinal cord ischemic/reperfusion injury (SCII) in a rat model by comparison with the standard neuroprotective agent methylprednisolone (MP). A total of 48 rats were divided into four groups of twelve rats in each (n=12). In sham-operated group (Control) group, rats received only saline (Fogarty catheter was inserted without balloon inflation), whereas rats in the SCII induction group (SCII) were subjected to SCII insult by insertion of a Fogarty balloon catheter, which was inflated in the descending thoracic aorta to cause an occlusion. A proportion of rats was treated with DZ (20 mg/kg; DZ+SCII group) or MP (50 mg/kg; MP+SCII group) for seven days prior to and after SCII. The locomotor function (neurological activity) and antioxidant levels (superoxide dismutase and catalase) levels were significantly improved upon treatment with DZ and MP in comparison with those in the SCII group. A concomitant decline in edema, inflammatory markers (myeloperoxidase, tumor necrosis factor-α and nuclear factor κB p65), the apoptotic marker caspase-3 and the number of cells with terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling was also observed in the DZ and MP groups. The protein levels of phosphoinositide-3 kinase (PI3K), the phosphorylated Akt/Akt ratio and B-cell lymphoma 2 (Bcl-2) were substantially downregulated, while Bcl-2-associated X protein levels were upregulated SCII insult group, which was inhibited by treatment with DZ. To conclude, pre-treatment with DZ significantly improved the neurological function by upregulating PI3K/Akt signaling and thereby considerably attenuating the inflammatory response and apoptosis, thus maintaining the neuronal count in an SCII-induced rat model.

Effects of ovariectomy on antioxidant defence systems in the right ventricle of female rats with pulmonary arterial hypertension induced by monocrotaline

The aim of this study was to evaluate the impact of ovariectomy on oxidative stress in the right ventricle (RV) of female rats with pulmonary arterial hypertension (PAH) induced by monocrotaline (MCT). Rats were divided into 4 groups (n = 6 per group): sham (S), sham + MCT (SM), ovariectomized (O), and ovariectomized + MCT (OM). MCT (60 mg·kg^-1 i.p.) was injected 1 week after ovariectomy or sham surgery. Three weeks later, echocardiographic analysis and RV catheterisation were performed. RV morphometric, biochemical, and protein expression analysis through Western blotting were done. MCT promoted a slight increase in pulmonary artery pressure, without differences between the SM and OM groups, but did not induce RV hypertrophy. RV hydrogen peroxide increased in the MCT groups, but SOD, CAT, and GPx activities were also enhanced. Non-classical antioxidant defenses diminished in ovariectomized groups, probably due to a decrease in the nuclear factor Nrf2. Hemoxygenase-1 and thioredoxin-1 protein expression was increased in the OM group compared with SM, being accompanied by an elevation in the estrogen receptor β (ER-β). Hemoxygenase-1 and thioredoxin-1 may be involved in the modulation of oxidative stress in the OM group, and this could be responsible for attenuation of PAH and RV remodeling.

Resveratrol, 4' Acetoxy Resveratrol, R-equol, Racemic Equol or S-equol as Cosmeceuticals to Improve Dermal Health

Phytochemicals are botanical compounds used in dermatology applications as cosmeceuticals to improve skin health. Resveratrol and equol are two of the best-known polyphenolic or phytoestrogens having similar chemical structures and some overlapping biological functions to 17β-estradiol. Human skin gene expression was reviewed for 28 different biomarkers when resveratrol, 4′ acetoxy resveratrol (4AR), R-equol, racemic equol or S-equol were tested. Sirtuin 1 activator (SIRT 1) was stimulated by resveratrol and 4AR only. Resveratrol, R-equol and racemic equol were effective on the aging biomarkers proliferating cell nuclear factor (PCNA), nerve growth factor (NGF), 5α-reductase and the calcium binding proteins S100 A8 and A9. Racemic equol and 4AR displayed among the highest levels for the collagens, elastin and tissue inhibitor of the matrix metalloproteinase 1 (TIMP 1). S-equol displayed the lowest level of effectiveness compared to the other compounds. The 4AR analog was more effective compared to resveratrol by 1.6-fold. R-equol and racemic equol were almost equal in potency displaying greater inhibition vs. resveratrol or its 4′ analog for the matrix metalloproteinases (MMPs), but among the inflammatory biomarkers, resveratrol, 4AR, R-equol and racemic equol displayed high inhibition. Thus, these cosmeceuticals display promise to improve dermal health; however, further study is warranted to understand how phytochemicals protect/enhance the skin.

Bioactive polyphenols and cardiovascular disease: chemical antagonists, pharmacological agents or xenobiotics that drive an adaptive response?

Polyphenols are widely regarded to have a wide range of health-promoting qualities, including beneficial effects on cardiovascular disease. Historically, the benefits have been linked to their well-recognized powerful antioxidant activity. However, the concept that the beneficial effects are attributable to direct antioxidant activity in vivo does not pay sufficient heed to the fact that polyphenols degrade rapidly, are poorly absorbed and rapidly metabolized, resulting in very low bioavailability. This review explores alternative mechanisms by which polyphenols, or their metabolites, exert biological activity via mechanisms that can be activated by physiologically relevant concentrations. Evidence is presented to support the action of phenolic derivatives on receptors and signalling pathways to induce adaptive responses that drive changes in endogenous antioxidant, antiplatelet, vasodilatory and anti-inflammatory effects. The implications are that in vitro antioxidant measures as predictors of polyphenol protective activity in vivo hold little relevance and that closer attention needs to be paid to bioavailable metabolites to understand the mode of action of these diet-derived components.

LINKED ARTICLES

This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

Equol Attenuates Atherosclerosis in Apolipoprotein E-Deficient Mice by Inhibiting Endoplasmic Reticulum Stress via Activation of Nrf2 in Endothelial Cells

The development of atherosclerosis is closely related to excessive endoplasmic reticulum stress (ERs). Equol reportedly protects against cardiovascular disease; however, the underlying mechanism for this protection remains unknown. Herein, the mechanisms contributing to the atheroprotective effect of equol were addressed using apolipoprotein E knockout (apoE-/-) mice fed a high-fat diet (HFD) with or without equol. Equol intervention reduced atherosclerotic lesions in the aorta in HFD-fed apoE-/- mice. Plasma lipid analysis showed that equol intervention reduced triglycerides, total cholesterol and LDL-cholesterol and increased HDL-cholesterol. Additionally, equol administration decreased lipid accumulation in the liver. Simultaneously, equol treatment inhibited cell apoptosis induced by t-BHP and thapsigargin in human umbilical vein endothelial cells (HUVECs). Furthermore, equol treatment attenuated palmitate, t-BHP or thapsigargin-induced upregulation of ER stress markers, including p-PERK, p-eIF2α, GRP78, ATF6 and CHOP proteins expression. The same tendency was also observed in aortic lysates in apoE-/- mice fed with equol plus HFD compared with HFD alone. Moreover, equol treatment dose dependently activated the Nrf2 signaling pathway under oxidative stress. Additionally, elevation of Nrf2 induction was found in aortic lysates in apoE-/- mice fed with a HFD diet containing equol compared with a HFD diet without equol. Importantly, Nrf2 siRNA interference induced CHOP and attenuated the effect of equol to inhibit t-BHP mediated CHOP induction, furthermore, abrogated cell apoptosis induced by t-BHP, suggesting a role for Nrf2 in the protective effect of equol in HUVECs. Collectively, these findings implicate that the improvement of atherosclerosis by equol through attenuation of ER stress is mediated, at least in part, by activating the Nrf2 signaling pathway.

Synthesis and cytotoxicity evaluation of 3-amino-2-hydroxypropoxyisoflavone derivatives

Soy isoflavones exert a wide variety of biological activities, such as antioxidant, anti-inflammatory and anti-cancer properties. Nuclear factor erythroid 2-related factor 2 (Nrf2), a bZip transcription factor, plays a key role in soy isoflavones induced protection against oxidative stress and cancer. To obtain more effective isofavones, a series of 7,4'-bis-(3-amino-2-hydroxypropoxy), 7 or 4'-(3-amino-2-hydroxypropoxy) isoflavone derivatives have been synthesized as potential antitumor agents and Nrf2/ARE (antioxidant response element) activators. The cytotoxicity of these compounds in human cancer cell lines MDA-MB-231, HT-29, HCT116, HepG2 and 7402 was tested by MTT assay. In this study, the cytotoxicity of compound 3b exhibited highest cytotoxic activity and at the safety dose range, it also strongly up-regulated antioxidant response element (ARE)-luciferase reporter activity. In addition, compound 3b induced Nrf2 nuclear translocation and upregulated its downstream target genes NQO-1 and HO-1 at protein level. Taken together, our results suggest that compound 3b could be a potential agent for cancer themotherapy or cancer chemoprevention.

Edaravone protects rats and human pulmonary alveolar epithelial cells against hyperoxia injury: heme oxygenase-1 and PI3K/Akt pathway may be involved

PURPOSE/AIM

Hyperoxic acute lung injury (HALI) is a clinical syndrome as a result of prolonged supplement of high concentrations of oxygen. As yet, no specific treatment is available for HALI. The present study aims to investigate the effects of edaravone on hyperoxia-induced oxidative injury and the underlying mechanism.

MATERIALS AND METHODS

We treated rats and human pulmonary alveolar epithelial cells with hyperoxia and different concentration of edaravone, then examined the effects of edaravone on cell viability, cell injury and two oxidative products. The roles of heme oxygenase-1 (HO-1) and PI3K/Akt pathway were explored using Western blot and corresponding inhibitors.

RESULTS

The results showed that edaravone reduced lung biochemical alterations induced by hyperoxia and mortality of rats, dose-dependently alleviated cell mortality, cell injury, and peroxidation of cellular lipid and DNA oxidative damage. It upregulated cellular HO-1 expression and activity, which was reversed by PI3K/Akt pathway inhibition. The administration of zinc protoporphyrin-IX, a HO-1 inhibitor, and LY249002, a PI3K/Akt pathway inhibitor, abolished the protective effects of edaravone in cells.

CONCLUSIONS

This study indicates that edaravone protects rats and human pulmonary alveolar epithelial cells against hyperoxia-induced injury and the antioxidant effect may be related to upregulation of HO-1, which is regulated by PI3K/Akt pathway.

Nuclear Factor Erythroid 2-Related Factor 2 Deficiency Results in Amplification of the Liver Fat-Lowering Effect of Estrogen

Transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) regulates multiple biologic processes, including hepatic lipid metabolism. Estrogen exerts actions affecting energy homeostasis, including a liver fat-lowering effect. Increasing evidence indicates the crosstalk between these two molecules. The aim of this study was to evaluate whether Nrf2 modulates estrogen signaling in hepatic lipid metabolism. Nonalcoholic fatty liver disease (NAFLD) was induced in wild-type and Nrf2-null mice fed a high-fat diet and the liver fat-lowering effect of exogenous estrogen was subsequently assessed. We found that exogenous estrogen eliminated 49% and 90% of hepatic triglycerides in wild-type and Nrf2-null mice with NAFLD, respectively. This observation demonstrates that Nrf2 signaling is antagonistic to estrogen signaling in hepatic fat metabolism; thus, Nrf2 absence results in striking amplification of the liver fat-lowering effect of estrogen. In addition, we found the association of trefoil factor 3 and fatty acid binding protein 5 with the liver fat-lowering effect of estrogen. In summary, we identified Nrf2 as a novel and potent inhibitor of estrogen signaling in hepatic lipid metabolism. Our finding may provide a potential strategy to treat NAFLD by dually targeting Nrf2 and estrogen signaling.

Effects of equol on H2O2-induced oxidative stress in primary chicken intestinal epithelial cells

This experiment investigated the antioxidant effects of equol on oxidative stress induced by H2O2 in chicken intestinal epithelial cells (IEC). IEC, from Lingnan yellow broiler chick embryos at embryonic day 18, were cultured in Dulbecco's modified Eagle's medium/F12. Cells were pretreated with 0, 10, 100, or 500 nM equol for 24 h before exposure to 300 μM H2O2 during a further 24 h. Oxidative damage was assessed by photomicrographs of cells, measuring cell proliferation, malondialdehyde (MDA) content, and antioxidative capacity from cellular total superoxide dismutase (T-SOD) activity, as well as the relative expressions of Nrf2, Bcl-2, SOD-1, GSH-Px3, Claudin-1 Treatment with 300 μM H2O2 caused serious damage to cells, with fewer normal intestinal epithelial cells, revealed by photomicroscopy. Treatment with 300 μM H2O2 significantly decreased live cell numbers compared with controls and prior treatment with equol had no effect in offsetting this action of H2O2 (P > 0.05). Compared with the cells treated just with H2O2, pre-treatment with 10, 100 and 500 nM equol significantly enhanced T-SOD activity (P < 0.05), while 10 and 100 nM equol before H2O2 significantly enhanced T-SOD activity compared with the untreated controls (P < 0.05). In cells pre-treated with 100 nM equol, the relative abundance of Nrf2 transcripts increased from the controls (P < 0.05) but expressions of Bcl-2, GSH-Px3, or SOD-1 were unaffected (P > 0.05). Pre-treatment with 10 and 100 nM equol significantly increased the transcript abundance of Claudin-1 (P < 0.05). Equol is shown here to protect IECs from oxidative damage by promoting the expression of antioxidant genes, increasing the activities of antioxidant enzymes, and by enhancing antioxidant capacity; 100 nM equol appeared to be the most effective concentration.

Ampelopsin protects endothelial cells from hyperglycemia-induced oxidative damage by inducing autophagy via the AMPK signaling pathway

Diabetic angiopathy is a major diabetes-specific complication that often begins with endothelial dysfunction induced by hyperglycemia; however, the pathological mechanisms of this progression remain unclear. Ampelopsin is a natural flavonol that has strong antioxidant activity, but little information is available regarding its antidiabetic effect. This study focused on the effect of ampelopsin on hyperglycemia-induced oxidative damage and the underlying mechanism of this effect in human umbilical vein endothelial cells (HUVECs). We found that hyperglycemia impaired autophagy in HUVECs through the inhibition of AMP-activated protein kinase (AMPK), which directly led to endothelial cell damage. Ampelopsin significantly attenuated the detrimental effect of hyperglycemia-induced cell dysfunction in a concentration-dependent manner in HUVECs. Ampelopsin significantly upregulated LC3-II, Beclin1, and Atg5 protein levels but downregulated p62 protein levels in HUVECs. Transmission electron microscopy and confocal microscopy indicated that ampelopsin notably induced autophagosomes and LC3-II dots, respectively. Additionally, the autophagy-specific inhibitor 3-MA, as well as Atg5 and Beclin1 siRNA pretreatment, markedly attenuated ampelopsin-induced autophagy, which subsequently abolished the protective effect of ampelopsin against hyperglycemia in HUVECs. Moreover, ampelopsin also increased AMPK activity and inhibited mTOR (mammalian target of rapamycin) complex activation. Ampelopsin-induced autophagy was attenuated by the AMPK antagonist compound C but strengthened by the AMPK agonist AICAR (5-minoimidazole-4-carboxamide ribonucleotide). Furthermore, AMPK siRNA transfection eliminated ampelopsin's alleviation of cell injury induced by hyperglycemia. The protective effect of ampelopsin against hyperglycemia-induced cell damage, which functions by targeting autophagy via AMPK activation, makes it a promising pharmacological treatment for type-2 diabetes.

Hypoxanthine uptake by skeletal muscle microvascular endothelial cells from equilibrative nucleoside transporter 1 (ENT1)-null mice: effect of oxidative stress

Adenosine is an endogenous regulator of vascular tone. This activity of adenosine is terminated by its uptake and metabolism by microvascular endothelial cells (MVEC). The predominant transporter involved is ENT1 (equilibrative nucleoside transporter subtype 1). MVEC also express the nucleobase transporter (ENBT1) which is involved in the cellular flux of adenosine metabolites such as hypoxanthine. Changes in either of these transport systems would impact the bioactivity of adenosine and its metabolism, including the formation of oxygen free radicals. MVEC isolated from skeletal muscle of ENT1(+/+) and ENT1(-/-) mice were subjected to oxidative stress induced by simulated ischemia/reperfusion or menadione. The functional activities of ENT1 and ENBT1 were assessed based on zero-trans influx kinetics of radiolabeled substrates. There was a reduction in the rate of ENBT1-mediated hypoxanthine uptake by ENT1(+/+) MVEC treated with menadione or after exposure to conditions that simulate ischemia/reperfusion. In both cases, the superoxide dismutase mimetic MnTMPyP attenuated the loss of ENBT1 activity, implicating superoxide radicals in the response. In contrast, MVEC isolated from ENT1(-/-) mice showed no reduction in ENBT1 activity upon treatment with menadione or simulated ischemia/reperfusion, but they did have a significantly higher level of catalase activity relative to ENT1(+/+) MVEC. These data suggest that ENBT1 activity is decreased in MVEC in response to the increased superoxide radical that is associated with ischemia/reperfusion injury. MVEC isolated from ENT1(-/-) mice do not show this reduction in ENBT1, possibly due to increased catalase activity.

Astrocyte-derived retinoic acid: a novel regulator of blood-brain barrier function in multiple sclerosis

Multiple sclerosis (MS) lesions are characterized by the presence of activated astrocytes, which are thought to actively take part in propagating lesion progression by secreting pro-inflammatory mediators. Conversely, reactive astrocytes may exert disease-dampening effects through the production of trophic factors and anti-inflammatory mediators. Astrocytic control of the blood-brain barrier (BBB) is crucial for normal brain homeostasis and BBB disruption is a well-established early event in MS lesion development. Here, we set out to unravel potential protective effects of reactive astrocytes on BBB function under neuroinflammatory conditions as seen in MS, where we focus on the role of the brain morphogen retinoic acid (RA). Immunohistochemical analysis revealed that retinaldehyde dehydrogenase 2 (RALDH2), a key enzyme for RA synthesis, is highly expressed by reactive astrocytes throughout white matter lesions compared to control and normal appearing white matter. In vitro modeling of reactive astrocytes resulted in increased expression of RALDH2, enhanced RA synthesis, and a protective role for astrocyte-derived RA on BBB function during inflammation-induced barrier loss. Furthermore, RA induces endothelial immune quiescence and decreases monocyte adhesion under inflammatory conditions. Finally, we demonstrated that RA attenuated oxidative stress in inflamed endothelial cells, through activation of the antioxidant transcription factor nuclear factor E2 related factor 2. In summary, RA synthesis by reactive astrocytes represents an endogenous protective response to neuroinflammation, possibly aimed at protecting the BBB against inflammatory insult. A better understanding of RA signaling in MS pathophysiology may lead to the discovery of novel targets to halt disease progression.

Estrogen receptor-mediated resveratrol actions on blood-brain barrier of ovariectomized mice

To test whether resveratrol provides benefits via estrogen receptors (ERs) in the blood-brain barrier of estrogen-deficient females, ovariectomized mice were treated with resveratrol then were subjected to transient middle cerebral artery occlusion (MCAO). Compared with vehicle treatment, resveratrol reduced infarct volume and neurologic deficits after MCAO. Basal tight junction (TJ) protein levels in the brain were increased by resveratrol. After MCAO, blood-brain barrier breakdown reduced levels of TJ proteins, and induction of HIF-1α and VEGF were attenuated by resveratrol. These effects were reversed by the ERs antagonist, ICI182,780. In mouse brain, endothelial cells (bEnd.3) exposed to hypoxia, resveratrol treatment protected the cells against cytotoxicity, increases of paracellular permeability and changes in levels of TJ protein and HIF-1α/VEGF proteins. These effects were reversed by ICI182,780 but not by specific ERα or ERβ antagonists, indicating nonspecific ER mediated effects. Altogether, these results showed that neuroprotective effects of resveratrol in ovariectomized mice were mediated by ERs and associated with tightening of blood-brain barrier, suggesting that resveratrol can be an alternative to estrogens to protect the brains of estrogen-deficient females against ischemic insult.

Bioavailability, bioactivity and impact on health of dietary flavonoids and related compounds: an update

There is substantial interest in the role of plant secondary metabolites as protective dietary agents. In particular, the involvement of flavonoids and related compounds has become a major topic in human nutrition research. Evidence from epidemiological and human intervention studies is emerging regarding the protective effects of various (poly)phenol-rich foods against several chronic diseases, including neurodegeneration, cancer and cardiovascular diseases. In recent years, the use of HPLC-MS for the analysis of flavonoids and related compounds in foods and biological samples has significantly enhanced our understanding of (poly)phenol bioavailability. These advancements have also led to improvements in the available food composition and metabolomic databases, and consequently in the development of biomarkers of (poly)phenol intake to use in epidemiological studies. Efforts to create adequate standardised materials and well-matched controls to use in randomised controlled trials have also improved the quality of the available data. In vitro investigations using physiologically achievable concentrations of (poly)phenol metabolites and catabolites with appropriate model test systems have provided new and interesting insights on potential mechanisms of actions. This article will summarise recent findings on the bioavailability and biological activity of (poly)phenols, focusing on the epidemiological and clinical evidence of beneficial effects of flavonoids and related compounds on urinary tract infections, cognitive function and age-related cognitive decline, cancer and cardiovascular disease.

Cytoprotection "gone astray": Nrf2 and its role in cancer

Nrf2 has gained great attention with respect to its pivotal role in cell and tissue protection. Primarily defending cells against metabolic, xenobiotic and oxidative stress, Nrf2 is essential for maintaining tissue integrity. Owing to these functions, Nrf2 is regarded as a promising drug target in the chemoprevention of diseases, including cancer. However, much evidence has accumulated that the beneficial role of Nrf2 in cancer prevention essentially depends on the tight control of its activity. In fact, the deregulation of Nrf2 is a critical determinant in oncogenesis and found in many types of cancer. Therefore, amplified Nrf2 activity has profound effects on the phenotype of tumor cells, including radio/chemoresistance, apoptosis protection, invasiveness, antisenescence, autophagy deficiency, and angiogenicity. The deregulation of Nrf2 can result from various epigenetic and genetic alterations directly affecting Nrf2 control or from the complex interplay of Nrf2 with numerous oncogenic signaling pathways. Additionally, alterations of the cellular environment, eg, during inflammation, contribute to Nrf2 deregulation and its persistent activation. Therefore, the status of Nrf2 as anti- or protumorigenic is defined by many different modalities. A better understanding of these modalities is essential for the safe use of Nrf2 as an activation target for chemoprevention on the one hand and as an inhibition target in cancer therapy on the other. The present review mainly addresses the conditions that promote the oncogenic function of Nrf2 and the resulting consequences providing the rationale for using Nrf2 as a target structure in cancer therapy.

Attenuation of Aβ25-35-induced parallel autophagic and apoptotic cell death by gypenoside XVII through the estrogen receptor-dependent activation of Nrf2/ARE pathways

Amyloid-beta (Aβ) has a pivotal function in the pathogenesis of Alzheimer's disease. To investigate Aβ neurotoxicity, we used an in vitro model that involves Aβ25-35-induced cell death in the nerve growth factor-induced differentiation of PC12 cells. Aβ25-35 (20μM) treatment for 24h caused apoptotic cell death, as evidenced by significant cell viability reduction, LDH release, phosphatidylserine externalization, mitochondrial membrane potential disruption, cytochrome c release, caspase-3 activation, PARP cleavage, and DNA fragmentation in PC12 cells. Aβ25-35 treatment led to autophagic cell death, as evidenced by augmented GFP-LC3 puncta, conversion of LC3-I to LC3-II, and increased LC3-II/LC3-I ratio. Aβ25-35 treatment induced oxidative stress, as evidenced by intracellular ROS accumulation and increased production of mitochondrial superoxide, malondialdehyde, protein carbonyl, and 8-OHdG. Phytoestrogens have been proved to be protective against Aβ-induced neurotoxicity and regarded as relatively safe targets for AD drug development. Gypenoside XVII (GP-17) is a novel phytoestrogen isolated from Gynostemma pentaphyllum or Panax notoginseng. Pretreatment with GP-17 (10μM) for 12h increased estrogen response element reporter activity, activated PI3K/Akt pathways, inhibited GSK-3β, induced Nrf2 nuclear translocation, augmented antioxidant responsive element enhancer activity, upregulated heme oxygenase 1 (HO-1) expression and activity, and provided protective effects against Aβ25-35-induced neurotoxicity, including oxidative stress, apoptosis, and autophagic cell death. In conclusion, GP-17 conferred protection against Aβ25-35-induced neurotoxicity through estrogen receptor-dependent activation of PI3K/Akt pathways, inactivation of GSK-3β and activation of Nrf2/ARE/HO-1 pathways. This finding might provide novel insights into understanding the mechanism for neuroprotective effects of phytoestrogens or gypenosides.

BRCA1 and estrogen/estrogen receptor in breast cancer: where they interact?

BRCA1 mainly acts as a tumor suppressor and BRCA1 mutation correlates with increased cancer risk. Although it is well recognized that BRCA1 related tumorigenesis is mainly caused by the increased DNA damage and decreased genome stability, it is not clear that why BRCA1 related patients have higher risk for cancer development mainly in estrogen responsive tissues such as breast and ovary. Recent studies suggested that BRCA1 and E-ER (estrogen and estrogen receptor) signaling synergistically regulate the mammary epithelial cell proliferation and differentiation. In this current presentation, we reviewed the correlation between mammary gland epithelial cell transformation and the status of BRCA1 and ER. Then the mechanisms of BRCA1 and E-ER interaction at both gene transcription level and protein-protein interaction level are discussed. Furthermore, the tumorigenic mechanisms are discussed by focusing on the synergistic effect of BRCA1 and E-ER on cell metabolism, ROS management, and antioxidant activity in mammary gland epithelial cells. Also, the possibility of cell de-differentiation promoted by coordinated effect between BRCA1 mutation and E-ER signal is explored. Together, the currently available evidences suggest that BRCA1 mutation and E-ER signal together, contribute to breast tumorigenesis by providing the metabolic support for cancer cell growth and even may directly be involved in promoting the de-differentiation of cancer-prone epithelial cells.