Vitamin E prevents NRF2 suppression by allergens in asthmatic alveolar macrophages in vivo

Dietary supplementations to mitigate the cardiopulmonary effects of air pollution toxicity: A systematic review of clinical trials

BACKGROUND

There is a consistent association between exposure to air pollution and elevated rates of cardiopulmonary illnesses. As public health activities emphasize the paramount need to reduce exposure, it is crucial to examine strategies like the antioxidant diet that could potentially protect individuals who are unavoidably exposed.

METHODS

A systematic search was performed in PubMed/Medline, EMBASE, CENTRAL, and ClinicalTrials.gov up to March 31, 2023, for clinical trials assessing dietary supplements against cardiovascular (blood pressure, heart rate, heart rate variability, brachial artery diameter, flow-mediated dilation, and lipid profile) or pulmonary outcomes (pulmonary function and airway inflammation) attributed to air pollution exposure.

RESULTS

After reviewing 4681 records, 18 studies were included. There were contradictory findings on the effects of fish oil and olive oil supplementations on cardiovascular outcomes. Although with limited evidence, fish oil offered protection against pulmonary dysfunction induced by pollutants. Most studies on vitamin C did not find protective cardiovascular effects; however, the combination of vitamin C and E offered protective effects against pulmonary dysfunction but showed conflicting results for cardiovascular outcomes. Other supplements like sulforaphane, L-arginine, n-acetylcysteine, and B vitamins showed potential beneficial effects but need further research due to the limited number of existing trials.

CONCLUSIONS

Although more research is needed to determine the efficacy and optimal dose of anti-inflammatory and antioxidant dietary supplements against air pollution toxicity, this low-cost preventative strategy has the potential to offer protection against outcomes of air pollution exposure.

Protective effects of inhaled antioxidants against air pollution-induced pathological responses

As the public health burden of air pollution continues to increase, new strategies to mitigate harmful health effects are needed. Dietary antioxidants have previously been explored to protect against air pollution-induced lung injury producing inconclusive results. Inhaled (pulmonary or nasal) administration of antioxidants presents a more promising approach as it could directly increase antioxidant levels in the airway surface liquid (ASL), providing protection against oxidative damage from air pollution. Several antioxidants have been shown to exhibit antioxidant, anti-inflammatory, and anti-microbial properties in in vitro and in vivo models of air pollution exposure; however, little work has been done to translate these basic research findings into practice. This narrative review summarizes these findings and data from human studies using inhaled antioxidants in response to air pollution, which have produced positive results, indicating further investigation is warranted. In addition to human studies, cell and murine studies should be conducted using more relevant models of exposure such as air-liquid interface (ALI) cultures of primary cells and non-aqueous apical delivery of antioxidants and pollutants. Inhalation of antioxidants shows promise as a protective intervention to prevent air pollution-induced lung injury and exacerbation of existing lung disease.

Macrophages Orchestrate Airway Inflammation, Remodeling, and Resolution in Asthma

Asthma is a heterogenous chronic inflammatory lung disease with endotypes that manifest different immune system profiles, severity, and responses to current therapies. Regardless of endotype, asthma features increased immune cell infiltration, inflammatory cytokine release, and airway remodeling. Lung macrophages are also heterogenous in that there are separate subsets and, depending on the environment, different effector functions. Lung macrophages are important in recruitment of immune cells such as eosinophils, neutrophils, and monocytes that enhance allergic inflammation and initiate T helper cell responses. Persistent lung remodeling including mucus hypersecretion, increased airway smooth muscle mass, and airway fibrosis contributes to progressive lung function decline that is insensitive to current asthma treatments. Macrophages secrete inflammatory mediators that induce airway inflammation and remodeling. Additionally, lung macrophages are instrumental in protecting against pathogens and play a critical role in resolution of inflammation and return to homeostasis. This review summarizes current literature detailing the roles and existing knowledge gaps for macrophages as key inflammatory orchestrators in asthma pathogenesis. We also raise the idea that modulating inflammatory responses in lung macrophages is important for alleviating asthma.

The Role of Vitamins in the Pathogenesis of Asthma

Vitamins play a crucial role in the proper functioning of organisms. Disturbances of their levels, seen as deficiency or excess, enhance the development of various diseases, including those of the cardiovascular, immune, or respiratory systems. The present paper aims to summarize the role of vitamins in one of the most common diseases of the respiratory system, asthma. This narrative review describes the influence of vitamins on asthma and its main symptoms such as bronchial hyperreactivity, airway inflammation, oxidative stress, and airway remodeling, as well as the correlation between vitamin intake and levels and the risk of asthma in both pre- and postnatal life.

Clinically proven natural products, vitamins and mineral in boosting up immunity: A comprehensive review

BACKGROUND

and Purposes: The terminology "immune boost-up" was the talk of the topic in this Covid-19 pandemic. A significant number of the people took initiative to increase the body's defense capacity through boosting up immunity worldwide. Considering this, the study was designed to explain the natural products, vitamins and mineral that were proved by clinical trail as immunity enhancer.

METHODS

Information was retrieved from SciVerse Scopus ® (Elsevier Properties S. A, USA), Web of Science® (Thomson Reuters, USA), and PubMed based on immunity, nutrients, natural products in boosting up immunity, minerals and vitamins in boosting up immunity, and immune booster agents.

RESULT

A well-defined immune cells response provide a-well functioning defense system for the human physiological system. Cells of the immune system must require adequate stimulation so that these cells can prepare themselves competent enough to fight against any unintended onslaught. Several pharmacologically active medicinal plants and plants derived probiotics or micronutrients have played a pivotal role in enhancing the immune boost-up process. Their role has been well established from the previous study. Immune stimulating cells, especially cells of acquired immunity are closely associated with the immune-boosting up process because all the immunological reactions and mechanisms are mediated through these cells.

CONCLUSION

This article highlighted the mechanism of action of different natural products, vitamins and mineral in boosting up the immunity of the human body and strengthening the body's defense system. Therefore, it is recommended that until the specific immune-boosting drugs are available in pharma markets, anyone can consider the mentioned products as dietary supplements to boost up the immunity.

Dietary Factors Associated with Asthma Development: A Narrative Review and Summary of Current Guidelines and Recommendations

Asthma is a complex disease, caused by a combination of genetic and environmental factors. The prevalence of asthma is increasing too rapidly to be attributable to genetic factors alone. Thus, environmental factors are becoming increasingly recognized as the cause of asthma. Modifying these environmental factors may be a simple approach for asthma prevention. To date, dietary intervention is an interesting modifiable factor because it can be implemented at the population level. The modification of systemic inflammation, oxidation, and microbial composition might be a mechanistic basis for prevention. This review summarizes the mechanistic basis and evidence from clinical studies on the association between dietary factors and asthma development. We also summarize the recommendations from many organizations and regional guidelines to assist the practicing physician to improve patient care.

From Foods to Chemotherapeutics: The Antioxidant Potential of Dietary Phytochemicals

Food plants have been recognized for their medicinal properties for millennia, a concept supported by epidemiological studies indicating long-term health benefits for people consuming greater amounts of fruits and vegetables. As our technology and instrumentation advance, researchers have the ability to identify promising phytochemicals, and examine their potential benefits, or detriments, to human health. While results from trials investigating single chemical supplementation have sometimes produced negative health results, studies investigating the synergistic action of phytochemicals—either within our diet or as an adjuvant to radiation or chemotherapy—appear promising. Utilizing phytochemicals as synergistic agents may lower the chemotherapeutic doses needed to incur physiological results, while also using chemicals with fewer toxic effects. This review investigates a variety of plant-produced chemicals humans typically ingest, their impacts on overall health patterns, molecular mechanisms associated with their health impacts, and the potential of their synergistic use for therapeutic purposes.

The effect of vitamin E on the lipid environment of rat hepatocyte membranes

Tocopherol is one of the known beneficial natural antioxidants ensuring the optimal level of functioning of mammalian organisms. Numerous in vitro and in vivo experiments have shown that the biological role of vitamin E is to prevent the development of pathologies caused by oxidative stress. In particular, the role of enzymatic factors of lipid peroxidation and related inflammation as a result of eicosanoid synthesis was clearly shown. We studied changes in the structural and functional state of hepatocyte membranes in the classical model of E-hypovitaminosis caused by long-term (70 days) insufficient intake of vitamin E in the diet of rats. The test components were determined spectrophotometrically after appropriate chromatographic procedures. The amount of total and individual leukotrienes was determined by ELISA. Prolonged tocopherol deficiency in rats caused a 49.4% decrease in tocopherol, more than 27.0% – in cholesterol. Of the 8 individual phospholipids studied, 6 showed significant changes: a decrease in cardiolipin and phosphatidylserine, and an increase in phosphatidylethanolamine by 3.24 times, an increse in lysophosphatidylcholine by 86.9%, in phospha­tidylcholine by 52.8%, and in sphingomyelin by 30.6%, relative to control. There were changes in the levels of unsaturated fatty acids playing a significant role in the development of functional disorders in cells and affecting the metabolism of ecosanoids derived from arachidonic acid by the 5-lipoxygenase oxidation pathway. Changes in the levels of total and individual cysteinyl leukotrienes in the state of E-hypovitaminosis were revealed. Restoration of vitamin E intake returns most of the studied indicators such as tocopherol, cholesterol, polyunsaturated fatty acids to the control levels and activates the processes of sequential conversion of leukotrienes in the body of rats. The obtained results indicate the potentiating effect of vitamin E on metabolic processes in the body as a whole and in hepatocytes and eicosanoid metabolism. The degree of tocopherol intake allows one to influence the course of inflammatory processes associated with eicosanoids, not only through the impact on precursors, but also on the utilization of metabolites, including leukotrienes.

A vitamin E long-chain metabolite and the inspired drug candidate α-amplexichromanol relieve asthma features in an experimental model of allergen sensitization

Benefits for vitamin E intake in diseases with inflammatory components have been described and related in part, to endogenously formed metabolites (long-chain metabolites, LCM). Here, we have evaluated the role of LCM in relieving asthma features. To this aim, the endogenous vitamin E metabolite α-13'-carboxychromanol (α-T-13'-COOH) that acts as potent 5-lipoxygenase inhibitor has been administered either intraperitoneally or by oral gavage to BALB/c mice sensitized by subcutaneous injection of ovalbumin (OVA). We also have taken advantage of the metabolically stable α-T-13'-COOH derivative α-amplexichromanol (α-AC). Intraperitoneal treatment with α-T-13'-COOH reduced OVA-induced airway hyperreactivity (AHR) as well as peri-bronchial inflammatory cell infiltration. α-AC was more efficacious than α-T-13'-COOH, as demonstrated by better control of AHR and in reducing subepithelial thickening. Both compounds exerted their protective function by reducing pulmonary leukotriene C₄ levels. Beneficial effects of α-AC were coupled to inhibition of the sensitization process, as indicated by a reduction of IgE plasma levels, lung mast cell infiltration and Th2 immune response. Metabololipidomics analysis revealed that α-AC raises the pulmonary levels of prostanoids, their degradation products, and 12/15-lipoxygenase metabolites. Following oral administration, the pharmacodynamically different profile in α-T-13'-COOH and α-AC was abrogated as demonstrated by a similar and improved efficacy in controlling asthma features as well as by metabololipidomics analysis. In conclusion, this study highlights a role for LCM and of vitamin E derivatives as pharmacologically active compounds that ameliorate asthmatic features and defines an important role for endogenous vitamin E metabolites in regulating immune response underlying the sensitization process.

Nutraceuticals and mitochondrial oxidative stress: bridging the gap in the management of bronchial asthma

Asthma is a chronic inflammatory disease primarily characterized by inflammation and reversible bronchoconstriction. It is currently one of the leading causes of morbidity and mortality in the world. Oxidative stress further complicates the pathology of the disease. The current treatment strategies for asthma mainly involve the use of anti-inflammatory agents and bronchodilators. However, long-term usage of such medications is associated with severe adverse effects and complications. Hence, there is an urgent need to develop newer, novel, and safe treatment modalities for the management of asthma. This has therefore prompted further investigations and detailed research to identify and develop novel therapeutic interventions from potent untapped resources. This review focuses on the significance of oxidative stressors that are primarily derived from both mitochondrial and non-mitochondrial sources in initiating the clinical features of asthma. The review also discusses the biological scavenging system of the body and factors that may lead to its malfunction which could result in altered states. Furthermore, the review provides a detailed insight into the therapeutic role of nutraceuticals as an effective strategy to attenuate the deleterious effects of oxidative stress and may be used in the mitigation of the cardinal features of bronchial asthma.

Influence of the Bioactive Diet Components on the Gene Expression Regulation

Diet bioactive components, in the concept of nutrigenetics and nutrigenomics, consist of food constituents, which can transfer information from the external environment and influence gene expression in the cell and thus the function of the whole organism. It is crucial to regard food not only as the source of energy and basic nutriments, crucial for living and organism development, but also as the factor influencing health/disease, biochemical mechanisms, and activation of biochemical pathways. Bioactive components of the diet regulate gene expression through changes in the chromatin structure (including DNA methylation and histone modification), non-coding RNA, activation of transcription factors by signalling cascades, or direct ligand binding to the nuclear receptors. Analysis of interactions between diet components and human genome structure and gene activity is a modern approach that will help to better understand these relations and will allow designing dietary guidances, which can help maintain good health.

Administration of vitamin E attenuates airway inflammation through restoration of Nrf2 in a mouse model of asthma

Accumulating evidence reveals that ROS is one of the key mediators that contribute to the development of asthma. Studies on antioxidants have shown to have beneficial effects on asthma management. However, we still do not know the precise mechanism, and the effects depend on age. This study was conducted to assess the levels of ROS and the effect of antioxidants in younger and older mice using an eosinophilic asthma model. We analyzed airway hyperresponsiveness (AHR), cytokines in bronchoalveolar lavage fluid (BALF), inflammatory cell counts, and the expression levels of NFκB, Nrf2, EPx, and EDN in the lung tissue, as well as the level of ROS in the lung tissue and BALF. The degree of eosinophilia and the levels of IL-5, ROS, and NFκB were significantly increased, whereas the endogenous levels of vitamin E and Nrf2 were decreased in the lung and BALF in the older mice compared to younger mice. The administration of vitamin E attenuated AHR, airway inflammation, and the level of IL-13 and ROS and enhanced the Nrf2 level in the older mice compared to the younger mice. Taken together, vitamin E treatment may have the therapeutic potential through restoration of the Nrf2 level, especially in elderly asthma.

Effects of vitamin E and selenium on allergic rhinitis and asthma pathophysiology

Allergic diseases such as asthma and rhinitis are common health problems that affect hundreds of millions of people in the world. T helper 2 cytokines participate in the immune responses in these diseases. Vitamin E and selenium (Se) are supplementary factors which have immunomodulatory and antioxidant effects. The present study investigated the effects of vit E + Se administration on allergic symptoms in mice models of asthma and rhinitis. Mice were treated with vit E and Se, and the levels of IL-4, IL-5, IL-13, IL-25, IL-33, total IgE, and histamine were measured. Lung histopathology was also analyzed. Our results indicated that vit E could attenuate allergic rhinitis and asthma symptoms; nevertheless, treatment with Se alone was not effective in controlling allergic symptoms. We noticed reduced airway inflammation and constriction and mucus secretion in the mice, especially when vit E was used in combination with Se. Our result suggested that vit E, especially in combination with Se, could control allergic mediators and symptoms in rhinitis and asthma and reduce pulmonary inflammation and airway mucus secretion, helping to open obstructed bronchi.

The Effects of Antioxidant Supplements on the Inflammatory Gene Expression of Osteoarthritis-Like Chondrocytes

Osteoarthritis patients often experience pain and inflammation in joints. To understand whether antioxidant supplements could reduce inflammation and could potentially be applied for osteoarthritis treatment, vitamin E and resveratrol were investigated in this study. Hydrogen peroxide was used for inducing inflammation in porcine chondrocytes, and the lumen density was measured for the level of oxygen-derived free radicals. In total, 5, 50, 100, and 200 μM of vitamin E and resveratrol were analyzed for cell viability and the effect of lumen density. In addition, the expressions of IL-1β, TNF-α, MMP-1, MMP-13, and COL2A1 were investigated when treating chondrocytes with 100 μM vitamin E, 5 μM resveratrol, or their combination before or after hydrogen peroxide induction. Inducing chondrocytes with hydrogen peroxide for 30 min increased the level of lumen density sufficiently and stimulated the expression of inflammatory genes. All the concentrations of vitamin E and resveratrol showed good cell viability. Single treatment with either vitamin E or resveratrol reduced inflammatory gene expression, and combined treatment increased the expression of collagen type II. The results suggested that post-treatment with both vitamin E and resveratrol has a better effect on the reduction in inflammation in osteoarthritis-like chondrocytes.

Anti-allergic effects of vitamin E in allergic diseases: An updated review

Allergic diseases are caused by the immune system's response to innocent antigens called allergens. Recent decades have seen a significant increase in the prevalence of allergic diseases worldwide, which has imposed various socio-economic effects in different countries. Various factors, including genetic factors, industrialization, improved hygiene, and climate change contribute to the development of allergic diseases in many parts of the world. Moreover, changes in lifestyle and diet habits play pivotal roles in the prevalence of allergic diseases. Dietary changes caused by decreased intake of antioxidants such as vitamin E lead to the generation of oxidative stress, which is central to the development of allergic diseases. It has been reported in many articles that oxidative stress diverts immune responses to the cells associated with the pathogenesis of allergic diseases. The aim of this short review was to summarize current knowledge about the anti-allergic properties of vitamin E.

Rosmarinic acid attenuates chromium-induced hepatic and renal oxidative damage and DNA damage in rats

Hexavelant chromium (Cr (V1)) is a widely distributed environmental pollutant inducing damage in different organs of human and animals. The current study was designed to investigate the mechanistic role of rosmarinic acid (RA) to diminish chromium-induced hepatorenal oxidative damage and preneoplastic lesions in rats. Plant material was collected, identified, and extracted. The isolated RA was elucidated relying on the nuclear magnetic resonance spectroscopic data. Twenty-eight male Wistar rats received the following materials daily via oral gavage for 60 days; (Gp1): normal saline, (Gp2) 25 mg/kg.bwt RA, (Gp3) 10 mg/kg.bwt potassium dichromate (K2 Cr2 O7 ), (Gp4) K2 Cr2 O7  + RA. All rats were euthanized at the end of the experiment by cervical dislocation and the liver and kidney were collected. Prolonged continuous exposure of rats to chromium-induced oxidant/antioxidant imbalance manifested by significant elevation of malondialdehyde with reduction in reduced glutathione levels. Remarkable histopathological alterations in the liver and kidney tissue sections were recorded and confirmed by overexpression of the immunohistochemical staining of caspase-3, placental glutathione-S transferase, proliferating cell nuclear antigen together with a significant downregulation of nuclear factor erythroid-2 related factor 2 (Nrf2) gene and upregulation of nibrin gene. Observable improvements in the entire toxicopathological parameters were recorded in group cotreated with RA. Our findings revealed that Cr-induced preneoplastic lesions on the liver and kidney tissues of rats when exposed daily for long period of time, as well as confirmed the ability of RA to alleviate this toxicity through upregulation of Nrf2 pathway and its powerful antioxidant effects.

Lower serum levels of alpha tocopherol and lycopene are associated with higher pain and physical disability in subjects with primary knee osteoarthritis: A case-control study

Background: We aimed to determine dietary intake and serum concentration of α-tocopherol and lycopene in subjects with knee osteoarthritis (KOA) in relation to pain intensity and functional status and comparing them with healthy controls. Methods: This case-control study was conducted among 35 patients with primary KOA and 35 matched healthy subjects selected using convenience sampling method. Dietary intakes of alpha-tocopherol and lycopene were estimated from 24-hour dietary records. Visual Analogue Scale (VAS) and Western Ontario and McMaster (WOMAC) index were used to assess the pain and functional status, respectively. Results: Serum concentrations of alpha-tocopherol (0.024 ± 0.005 vs. 0.028 ± 0.007 μmol/ml, p-value =  0.021) and lycopene (0.616 ± 0.191 vs. 0.727 ± 0.159 μmol/l, p-value = 0.011) were significantly lower in OA patients in comparison with healthy controls. Dietary intake of alpha-tocopherol was negatively associated with total WOMAC score (r = -0.401, p-value = 0.021) and pain (r = -0.356, p-value = 0.042) and physical function (r = -0.355, p-value = 0.043) subscales. Dietary intake of lycopene was negatively associated with total WOMAC score (r = -0.616, p-value < 0.001) and pain (r = -0.348, p-value = 0.047) and physical function (r = -0.606, p-value < 0.001) subscales. Additionally, serum concentration of alpha-tocopherol was negatively associated with total WOMAC score (r = -0.574, p-value < 0.001) and physical function subscale (r = -0.571, p-value < 0.001). Serum concentration of lycopene was negatively associated with total WOMAC score (r = -0.360, p-value = 0.040) and physical function subscale (r = -0.350, p-value = 0.046) Conclusion: Serum concentrations of α-tocopherol and lycopene were significantly lower in patients with KOA than in healthy controls. Significant negative association was detected between serum concentration and dietary intake of α-tocopherol and lycopene with functional disability in patients with KOA.

Molecular Understanding of the Cardiomodulation in Myocardial Infarction and the Mechanism of Vitamin E Protections

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Myocardial infarction is a major cause of deaths globally. Modulation of several molecular mechanisms occurs during the initial stages of myocardial ischemia prior to permanent cardiac tissue damage, which involves both pathogenic as well as survival pathways in the cardiomyocyte. Currently, there is increasing evidence regarding the cardioprotective role of vitamin E in alleviating the disease. This fat-soluble vitamin does not only act as a powerful antioxidant; but it also has the ability to regulate several intracellular signalling pathways including HIF-1, PPAR-γ, Nrf-2, and NF-κB that influence the expression of a number of genes and their protein products. Essentially, it inhibits the molecular progression of tissue damage and preserves myocardial tissue viability. This review aims to summarize the molecular understanding of the cardiomodulation in myocardial infarction as well as the mechanism of vitamin E protection.

The role of serum nuclear factor erythroid 2-related factor 2 in childhood bronchial asthma

Background: Asthma is one of the most common chronic airway disease of childhood. Poor asthma control has been associated with antioxidant deficiencies. Objective: To assess the association of bronchial asthma in Egyptian children with serum nuclear factor erythroid 2-related factor2 (NRF2) and its relation to disease severity. Subjects and methods: The study included 60 asthmatic children with comparable 60 controls (age ranged from 6-16 years). Subjects were classified according to the severity of asthma into mild or moderate asthma in group I, and severe asthma in group II. Antioxidant markers including superoxide-dismutase (SOD), glutathione peroxidase (GPX) and NRF2 were assessed once in blood and serum of both subjects and controls. Results: Mean serum NRF2 and GPX were significantly lower in asthmatic group than controls group (26.36 ± 4.18 pg/mL and 5.76 ± 0.81 mU/mL vs 29.05 ± 3.87 and 6.23 ± 0.97 respectively, p < 0.05). No significant difference was detected regarding SOD (p > 0.05). In severe bronchial asthma, mean serum NRF2 and GPX were significantly lower than in mild and moderate asthma (24.29 ± 1.86 pg/mL and 5.56 ± 0.67 mU/mL vs 27.95 ± 4.77 and 6.03 ± 0.90 respectively, p < 0.05). No significant difference was found in SOD regarding severity of bronchial asthma. Low NRF2 was the only predictor of the severity of bronchial asthma (OR = 0.749 and 95% CI 0.595 - 0.942). Conclusion: The pathogenesis of childhood bronchial asthma may be associated with low serum NRF2 which may be a strong predictor of the disease severity.

Role of Nrf2 and Its Activators in Respiratory Diseases

Transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) is a major regulator of antioxidant response element- (ARE-) driven cytoprotective protein expression. The activation of Nrf2 signaling plays an essential role in preventing cells and tissues from injury induced by oxidative stress. Under the unstressed conditions, natural inhibitor of Nrf2, Kelch-like ECH-associated protein 1 (Keap1), traps Nrf2 in the cytoplasm and promotes the degradation of Nrf2 by the 26S proteasome. Nevertheless, stresses including highly oxidative microenvironments, impair the ability of Keap1 to target Nrf2 for ubiquitination and degradation, and induce newly synthesized Nrf2 to translocate to the nucleus to bind with ARE. Due to constant exposure to external environments, including diverse pollutants and other oxidants, the redox balance maintained by Nrf2 is fairly important to the airways. To date, researchers have discovered that Nrf2 deletion results in high susceptibility and severity of insults in various models of respiratory diseases, including bronchopulmonary dysplasia (BPD), respiratory infections, acute respiratory distress syndrome (ARDS), chronic obstructive pulmonary disease (COPD), asthma, idiopathic pulmonary fibrosis (IPF), and lung cancer. Conversely, Nrf2 activation confers protective effects on these lung disorders. In the present review, we summarize Nrf2 involvement in the pathogenesis of the above respiratory diseases that have been identified by experimental models and human studies and describe the protective effects of Nrf2 inducers on these diseases.

Oxidative stress and macrophages: driving forces behind exacerbations of asthma and chronic obstructive pulmonary disease?

Oxidative stress is a common feature of obstructive airway diseases like asthma and chronic obstructive pulmonary disease (COPD). Lung macrophages are key innate immune cells that can generate oxidants and are known to display aberrant polarization patterns and defective phagocytic responses in these diseases. Whether these characteristics are linked in one way or another and whether they contribute to the onset and severity of exacerbations in asthma and COPD remain poorly understood. Insight into oxidative stress, macrophages, and their interactions may be important in fully understanding acute worsening of lung disease. This review therefore highlights the current state of the art regarding the role of oxidative stress and macrophages in exacerbations of asthma and COPD. It shows that oxidative stress can attenuate macrophage function, which may result in impaired responses toward exacerbating triggers and may contribute to exaggerated inflammation in the airways.

The Role of Vitamin E in Immunity

Vitamin E is a fat-soluble antioxidant that can protect the polyunsaturated fatty acids (PUFAs) in the membrane from oxidation, regulate the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS), and modulate signal transduction. Immunomodulatory effects of vitamin E have been observed in animal and human models under normal and disease conditions. With advances in understating of the development, function, and regulation of dendritic cells (DCs), macrophages, natural killer (NK) cells, T cells, and B cells, recent studies have focused on vitamin E’s effects on specific immune cells. This review will summarize the immunological changes observed with vitamin E intervention in animals and humans, and then describe the cell-specific effects of vitamin E in order to understand the mechanisms of immunomodulation and implications of vitamin E for immunological diseases.

The Role of Vitamin E in Preventing and Treating Osteoarthritis - A Review of the Current Evidence

Osteoarthritis is a debilitating disease of the joint involving cartilage degeneration and chondrocytes apoptosis. Oxidative stress is one of the many proposed mechanisms underpinning joint degeneration in osteoarthritis. The current pharmacotherapies emphasize pain and symptomatic management of the patients but do not alter the biological processes underlying the cartilage degeneration. Vitamin E is a potential agent to prevent or treat osteoarthritis due to its antioxidant and anti-inflammatory effects. This review aims to summarize the current evidence on the relationship between vitamin E and osteoarthritis derived from preclinical and human studies. Cellular studies showed that vitamin E mitigated oxidative stress in cartilage explants or chondrocyte culture invoked by mechanical stress or free radicals. Animal studies suggested that vitamin E treatment prevented cartilage degeneration and improve oxidative status in animal models of osteoarthritis. Low circulating or synovial vitamin E was observed in human osteoarthritic patients compared to healthy controls. Observational studies also demonstrated that vitamin E was related to induction or progression of osteoarthritis in the general population. Vitamin E supplementation might improve the outcomes in patients with osteoarthritis, but negative results were also reported. Different isomers of vitamin E might possess distinct anti-osteoarthritic effects. As a conclusion, vitamin E may retard the progression of osteoarthritis by ameliorating oxidative stress and inflammation of the joint. Further studies are warranted to develop vitamin E as an anti-osteoarthritis agent to reduce the global burden of this disease.

Insights on Localized and Systemic Delivery of Redox-Based Therapeutics

Reactive oxygen and nitrogen species are indispensable in cellular physiology and signaling. Overproduction of these reactive species or failure to maintain their levels within the physiological range results in cellular redox dysfunction, often termed cellular oxidative stress. Redox dysfunction in turn is at the molecular basis of disease etiology and progression. Accordingly, antioxidant intervention to restore redox homeostasis has been pursued as a therapeutic strategy for cardiovascular disease, cancer, and neurodegenerative disorders among many others. Despite preliminary success in cellular and animal models, redox-based interventions have virtually been ineffective in clinical trials. We propose the fundamental reason for their failure is a flawed delivery approach. Namely, systemic delivery for a geographically local disease limits the effectiveness of the antioxidant. We take a critical look at the literature and evaluate successful and unsuccessful approaches to translation of redox intervention to the clinical arena, including dose, patient selection, and delivery approach. We argue that when interpreting a failed antioxidant-based clinical trial, it is crucial to take into account these variables and importantly, whether the drug had an effect on the redox status. Finally, we propose that local and targeted delivery hold promise to translate redox-based therapies from the bench to the bedside.

Exposure to diisodecyl phthalate exacerbated Th2 and Th17-mediated asthma through aggravating oxidative stress and the activation of p38 MAPK

Diisodecyl phthalate (DIDP) is considered to be one of the less toxic phthalates. However epidemiological studies suggest that DIDP is associated with the occurrence of asthma. The effect of DIDP exposure on allergic asthma and the underlying mechanism have not been fully elucidated. Here, mice were exposed to DIDP and sensitization with OVA. The results demonstrated that DIDP exposure aggravated allergic asthma. Exposure to 15 mg/kg/day DIDP markedly exacerbated airway remodeling and promoted airway hyperresponsiveness (AhR). The study suggests that exposure to DIDP not only promotes a predominant Th2 response, but also induces Th17-type immunity. The induced allergic asthma was accompanied by elevation of IgE, an increase in TSLP expression and exacerbation of oxidative stress. Inhibition of oxidative stress by Vitamin E effectively alleviated the airway remodeling and AhR induced by DIDP and OVA sensitization. Treatment with Vitamin E inhibited the Th2 response and the production of TSLP. Blocking the activation of p38 MAPK by SB203580 prevented elevation of IL-1β and IL-17A induced by DIDP and OVA sensitization and effectively alleviated Th17 type asthmatic lesions. These results suggest that exposure to DIDP exacerbates the Th2 and Th17 response through aggravating oxidative stress and activation of the p38 MAPK pathway.

Standardized extract of Bacopa monnieri (CDRI-08): Effect on germ cell dynamics and possible mechanisms of its beneficial action on spermatogenesis and sperm quality in male mice

Bacopa monnieri (BM) is used in traditional medicine as nerve tonic. We have recently shown that CDRI-08, a standardized extract of BM, improves testicular functions and epididymal sperm quality in Parkes (P) mice. The aim of the present study was to investigate the effect of CDRI-08 on germ cell dynamics and mechanisms of its action on spermatogenesis and sperm quality in P mice, and to determine the chemical profile of the extract. CDRI-08 (40 and 80 mg/kg body weight) was orally administered to male mice for 28 days. Germ cell dynamics, oxidative stress parameters in testis and sperm, and expressions of nuclear factor-erythroid-2-related factor-2 (Nrf2), phosphorylated protein kinase B (p-Akt) and upstream kinases in mitogen-activated protein kinase (MAPK) pathway namely MAP2K1, MAP2K2 and MKK4 in the testis were evaluated. The treatment potentiated germ cell dynamics and improved sperm quality by enhancing antioxidant enzymes activities. The beneficial effects of CDRI-08 in the testis involve p-Akt-mediated activation of Nrf2, thereby enhancing antioxidant enzymes activities; upregulation of MAP2K1 and MAP2K2 and suppression of MKK4 are also implicated in this action. A total of 26 phytocomponents were identified in CDRI-08 by GC-MS. The results suggest that CDRI-08 also may prove useful in improving reproductive health in males.

Vitamin E antagonizes ozone-induced asthma exacerbation in Balb/c mice through the Nrf2 pathway

Millions of people are regularly exposed to ozone, a gas known to contribute significantly to worsening the symptoms of patients with asthma. However, the mechanisms underlying these ozone exacerbation effects are not fully understood. In this study, we examined the exacerbation effect of ozone in OVA-induced asthma mice and tried to demonstrate the protective mechanism of vitamin E (VE). An asthma mouse model was established, and used to identify the exacerbating effects of ozone by assessing cytokine and serum immunoglobulin concentrations, airway leukocyte infiltration, histopathological changes in lung tissues, and airway hyper-responsiveness. We then determined the amount of reactive oxygen species (ROS) accumulated, the extent to which VE induced ROS elimination, and examined the antagonistic effects of VE on the ozone-induced exacerbating effects. This study showed that 1-ppm ozone exposure could exacerbate OVA-induced asthma in mice. More importantly we found that ozone induced oxidative stress in asthmatic airways may lead to the inhibition of Nuclear factor-erythroid 2-related factor 2 (Nrf2), and may subsequently induce even more exaggerated oxidative stress associated with asthma exacerbation. Through VE induced Nrf2 activation and the subsequent increase in Nrf2 target protein expression, this study suggests a novel mechanism for alleviating ozone exacerbated asthma symptoms.

Oxidized graphene-aggravated allergic asthma is antagonized by antioxidant vitamin E in Balb/c mice

Nanomaterials have been widely used in a number of applications; however, these nanomaterials may potentially be risky for human health, particularly for the respiratory system. In this study, we used a mouse asthma model to study whether graphene oxide (GO), a promising carbonaceous nanomaterial with unique physicochemical properties, aggravates allergic asthma via the oxidative stress pathway. Mice were sensitized with ovalbumin (OVA) to trigger immune reactions, while vitamin E (Ve) was administered as an antioxidant. Our results showed that GO aggravated OVA-induced allergic asthma in mice, as suggested by increased reactive oxygen species (ROS), elevated total immunoglobulin E (IgE), upregulated Th2 response, and the aggravation of allergic asthma symptoms, such as airway remolding, collagen deposition with mucus hypersecretion, and airway hyperresponsiveness (AHR). The administration of Ve dramatically attenuated all of the above effects. In conclusion, Ve showed anti-allergic properties in antagonizing the exacerbation of allergic asthma induced by GO, providing a new possibility for the treatment of allergic asthma.

Inflammatory Stress Sensitizes the Liver to Atorvastatin-Induced Injury in ApoE-/- Mice

Statins, which are revolutionized cholesterol-lowing agents, have been reported to have unfavorable effects on the liver. Inflammatory stress is a susceptibility factor for drug-induced liver injury. This study investigated whether inflammatory stress sensitized the liver to statin-induced toxicity in mice and explored the underlying mechanisms. We used casein injection in ApoE-/- mice to induce inflammatory stress. Half of the mice were orally administered atorvastatin (10mg/kg/d) for 8 weeks. The results showed that casein injection increased the levels of serum pro-inflammatory cytokines (IL-6 and TNFα). Atorvastatin treatment increased serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in casein injection mice. Moreover, atorvastatin treatment exacerbated hepatic steatosis, inflammation and fibrosis, as well as increased hepatic reactive oxygen species (ROS) and malondialdehyde in casein injection mice. However, above changes were not observed in atorvastatin treated alone mice. The protein expression of liver nuclear factor erythroid 2-related factor 2 (Nrf2) and the mRNA expressions of Nrf2 target genes were increased, together with the enhancement of activities of hepatic catalase and superoxide dismutase in atorvastatin treated alone mice, but these antioxidant responses were lost in mice treated with atorvastatin under inflammatory stress. This study demonstrates that atorvastatin exacerbates the liver injury under inflammatory stress, which may be associated with the loss of adaptive antioxidant response mediated by Nrf2.

Acute exposure of ozone induced pulmonary injury and the protective role of vitamin E through the Nrf2 pathway in Balb/c mice

Ozone (O₃) in the lower atmosphere is generally derived from various sources of human activity. It has become a major air pollutant in China and has been shown to adversely affect the health of humans and animals. We undertook a study to ascertain the molecular mechanism of ozone induced lung injury in mice and tried to demonstrate the protective mechanism of vitamin E. In this study, mice were exposed to clean air and three different concentrations of ozone. Oxidative stress (reactive oxygen species and malondialdehyde) and Th cytokines in the lung, serum IgE, as well as histopathological examination and the airway hyper-responsiveness (AHR) test were used to reflect inflammation and damage to the lungs of ozone-exposed mice. We then chose an effective concentration of ozone and combined treatment with vitamin E (VE) to explore the underlying mechanism of ozone-induced lung damage. The results of immunological and inflammatory biomarkers (total-immunoglobulin (Ig) E and Th cytokines) as well as histopathological examination and AHR assessment supported the notion that high doses of ozone (>0.5 ppm) could induce inflammation and lung injury in mice and that this induction was counteracted by concurrent administration of VE. The elimination of oxidative stress, the reduced Th2 responses and Ig production, and the relief of lung damage were proposed to explain the molecular mechanism of ozone induced lung injury. We also showed that VE, an antioxidant that enhanced the expression of Nrf2 and up-regulated the antioxidant genes HO-1 and NQO1, could decrease the levels of oxidative stress and alleviate ozone-induced lung injury.

Systemic inflammation and oxidative stress in hemodialysis patients are associated with down-regulation of Nrf2

BACKGROUND

Oxidative stress and inflammation are common features and the main mediators of progression of chronic kidney disease (CKD) and its cardiovascular complications. Under normal conditions, oxidative stress activates the transcription factor, nuclear factor E2-related factor 2 (Nrf2), which is the master regulator of genes encoding antioxidant and detoxifying enzymes and related proteins. The available data on expression of Nrf2 and its key target gene products in CKD patients is limited. We therefore investigated this topic in a group of CKD patients on hemodialysis.

METHODS

Twenty adult hemodialysis (HD) patients (aged 54.9 ± 15.2 years) and 11 healthy individuals (aged 50.9 ± 8.0 years) were enrolled. Peripheral blood mononuclear cells (PBMC) were isolated and processed for expression of nuclear factor-κB (NF-κB), Nrf2, heme oxygenase-1 and NADPH: quinoneoxidoreductase 1 (NQO1) by quantitative real-time polymerase chain reaction and western blot analysis. Plasma malondialdehyde (MDA) and tumor necrosis factor-alpha (TNF-α) levels were measured.

RESULTS

Peripheral blood mononuclear cells from HD patients had significantly lower NQO1 and Nrf2 mRNA expressions (0.58 ± 0.35 vs. 1.13 ± 0.64, p = 0.005), and significantly higher NF-κB expression (2.18 ± 0.8 vs. 1.04 ± 0.22, p = 0.0001) compared to the healthy individuals. The NF-κB expression was inversely correlated with Nrf2 levels (r = -0.54, p < 0.01) in CKD patients. Plasma MDA and TNF-α levels were significantly higher in CKD patients than in the healthy individuals.

CONCLUSIONS

Up-regulation of NFκB in the CKD patients' PBMC is coupled to down-regulation of Nrf2 and NQO1 expression. These observations are consistent with recent findings in CKD animals and point to the contribution of the impaired Nrf2 system in the pathogenesis of oxidative stress and inflammation in hemodialysis patients.

Regulation of Nrf2-an update

Nrf2:INrf2 (Keap1) are cellular sensors of oxidative and electrophilic stress. Nrf2 is a nuclear factor that controls the expression and coordinated induction of a battery of genes that encode detoxifying enzymes, drug transporters, antiapoptotic proteins, and proteasomes. In the basal state, Nrf2 is constantly degraded in the cytoplasm by its inhibitor, INrf2. INrf2 functions as an adapter for Cul3/Rbx1 E3 ubiquitin ligase-mediated degradation of Nrf2. Chemicals, including antioxidants, tocopherols including α-tocopherol (vitamin E), and phytochemicals, and radiation antagonize the Nrf2:INrf2 interaction and lead to the stabilization and activation of Nrf2. The signaling events involve preinduction, induction, and postinduction responses that tightly control Nrf2 activation and repression back to the basal state. Oxidative/electrophilic signals activate unknown tyrosine kinases in a preinduction response that phosphorylates specific residues on Nrf2 negative regulators, INrf2, Fyn, and Bach1, leading to their nuclear export, ubiquitination, and degradation. This prepares nuclei for unhindered import of Nrf2. Oxidative/electrophilic modification of INrf2 cysteine 151 followed by PKC phosphorylation of Nrf2 serine 40 in the induction response results in the escape or release of Nrf2 from INrf2. Nrf2 is thus stabilized and translocates to the nucleus, resulting in a coordinated activation of gene expression. This is followed by a postinduction response that controls the "switching off" of Nrf2-activated gene expression. GSK3β, under the control of AKT and PI3K, phosphorylates Fyn, leading to Fyn nuclear localization. Fyn phosphorylates Nrf2 Y568, resulting in nuclear export and degradation of Nrf2. The activation and repression of Nrf2 provide protection against oxidative/electrophilic stress and associated diseases, including cancer. However, deregulation of INrf2 and Nrf2 due to mutations may lead to nuclear accumulation of Nrf2 that reduces apoptosis and promotes oncogenesis and drug resistance.

Renal injury and Nrf2 modulation in mouse kidney following chronic exposure to TiO₂ nanoparticles

TiO₂ nanoparticles (NPs) are used in the food industry but have potential toxic effects in humans and animals. TiO₂ NPs impair renal function and cause oxidative stress and renal inflammation in mice, associated with inhibition of nuclear factor erythroid-2-related factor 2 (Nrf2), which regulates genes encoding many antioxidants and detoxifying enzymes. This study determined whether TiO₂ NPs activated the Nrf2 signaling pathway. Mice exhibited accumulation of reactive oxygen species and peroxidation of lipid, protein, and DNA in the kidney, coupled with renal dysfunction, glutathione depletion, inflammatory cell infiltration, fatty degeneration, and apoptosis. These were associated with increased expression of NOX4, cyclooxygenase-2, and nuclear factor-κB. Oxidative stress and inflammation were accompanied by decreased expression of Nrf2 and down-regulation of its target gene products including heme oxygenase 1, glutamate-cysteine ligase catalytic subunit, and glutathione S-transferase. Chronic TiO₂ NP exposure is associated with suppression of Nrf2, which contributes to the pathogenesis of oxidative stress and inflammation.

Effects of ex vivo γ-tocopherol on airway macrophage function in healthy and mild allergic asthmatics

Elevated inflammation and altered immune responses are features found in atopic asthmatic airways. Recent studies indicate γ-tocopherol (GT) supplementation can suppress airway inflammation in allergic asthma. We studied the effects of in vitro GT supplementation on receptor-mediated phagocytosis and expression of cell surface molecules associated with innate and adaptive immunity on sputum-derived macrophages. Cells from nonsmoking healthy (n = 6) and mild house dust mite-sensitive allergic asthmatics (n = 6) were treated ex vivo with GT (300 µM) or saline (control). Phagocytosis of opsonized zymosan A bioparticles (Saccharomyces cerevisiae) and expression of surface molecules associated with innate and adaptive immunity were assessed using flow cytometry. GT caused significantly decreased (p < 0.05) internalization of attached zymosan bioparticles and decreased (p < 0.05) macrophage expression of CD206, CD36 and CD86 in allergic asthmatics but not in controls. Overall, GT caused downregulation of both innate and adaptive immune response elements, and atopic status appears to be an important factor.

Role of impaired Nrf2 activation in the pathogenesis of oxidative stress and inflammation in chronic tubulo-interstitial nephropathy

BACKGROUND

Tubulo-interstitial nephropathy (TIN) is a common cause of chronic kidney disease (CKD). Consumption of an adenine-containing diet causes the accumulation of 2,8-dihydroxyadenine in the renal tubules triggering intense chronic TIN and progressive CKD in rats. CKD in this model is associated with, and largely driven by, oxidative stress and inflammation. Oxidative stress and inflammation in rats with spontaneous focal segmental glomerulosclerosis and rats with CKD induced by 5/6 nephrectomy are associated with an impaired activation of nuclear factor-erythroid-2-related factor 2 (Nrf2) which is the master regulator of genes encoding many antioxidant and detoxifying enzymes. The effect of TIN on the Nrf2 pathway and its key target genes is unknown and was investigated here.

METHODS

Sprague-Dawley rats were randomized to control and adenine-treated (rat chow-containing 0.7% adenine for 2 weeks) groups and followed up for 4 weeks.

RESULTS

The adenine-treated animals exhibited marked azotemia, impaired urinary concentrating capacity, intense tubular and glomerular damage, interstitial inflammation and fibrosis. This was associated with an increased expression of NAD(P)H oxidase, cyclooxygenase-2 and 12-lipoxygenase, and activation of NF-κB, the master regulator of pro-inflammatory cytokines and chemokines. Oxidative stress and inflammation in the kidneys of adenine-treated animals was accompanied by an impaired activation of Nrf2 and down-regulation of its target gene products including, catalase, heme oxygenase-1 and glutamate-cysteine ligase.

CONCLUSIONS

Chronic TIN is associated with impaired Nrf2 activity which contributes to the pathogenesis of oxidative stress and inflammation and amplifies their damaging effects on the kidney.

Vitamin E supplementation and lifespan in model organisms

We have conducted a comprehensive literature review regarding the effect of vitamin E on lifespan in model organisms including single-cell organisms, rotifers, Caenorhabditis elegans, Drosophila melanogaster and laboratory rodents. We searched Pubmed and ISI Web of knowledge for studies up to 2011 using the terms "tocopherols", "tocotrienols", "lifespan" and "longevity" in the above mentioned model organisms. Twenty-four studies were included in the final analysis. While some studies suggest an increase in lifespan due to vitamin E, other studies did not observe any vitamin E-mediated changes in lifespan in model organisms. Furthermore there are several studies reporting a decrease in lifespan in response to vitamin E supplementation. Different outcomes between studies may be partly related to species-specific differences, differences in vitamin E concentrations and the vitamin E congeners administered. The findings of our literature review suggest that there is no consistent beneficial effect of vitamin E on lifespan in model organisms which is consistent with reports in human intervention studies.

Asthmatic airway neutrophilia after allergen challenge is associated with the glutathione S-transferase M1 genotype

RATIONALE

Asthma is a heterogeneous lung disorder characterized by airway inflammation and airway dysfunction, manifesting as hyperresponsiveness and obstruction. Glutathione S-transferase M1 (GSTM1) is a multifunctional phase II enzyme and regulator of stress-activated cellular signaling relevant to asthma pathobiology. A common homozygous deletion polymorphism of the GSTM1 gene eliminates enzyme activity.

OBJECTIVES

To determine the effect of GSTM1 on airway inflammation and reactivity in adults with established atopic asthma in vivo.

METHODS

Nineteen GSTM1 wild-type and eighteen GSTM1-null individuals with mild atopic asthma underwent methacholine and inhaled allergen challenges, and endobronchial allergen provocations through a bronchoscope.

MEASUREMENTS AND MAIN RESULTS

The influx of inflammatory cells, panels of cytokines and chemokines linked to asthmatic inflammation, F(2)-isoprostanes (markers of oxidative stress), and IgE were measured in bronchoalveolar lavage fluid at baseline and 24 hours after allergen instillation. Individuals with asthma with the GSTM1 wild-type genotype had greater baseline and allergen-provoked airway neutrophilia and concentrations of myeloperoxidase than GSTM1-null patients. In contrast, the eosinophilic inflammation was unaffected by GSTM1. The allergen-stimulated generation of acute-stress and proneutrophilic mediators, tumor necrosis factor-α, CXCL-8, IL-1β, and IL-6, was also greater in the GSTM1 wild-type patients. Moreover, post-allergen airway concentrations of IgE and neutrophil-generated mediators, matrix metalloproteinase-9, B-cell activating factor, transforming growth factor-β1, and elastase were higher in GSTM1 wild-type individuals with asthma. Total airway IgE correlated with B-cell activating factor concentrations. In contrast, levels of F(2)-isoprostane were comparable in both groups. Finally, GSTM1 wild-type individuals with asthma required lower threshold concentrations of allergen to produce bronchoconstriction.

CONCLUSIONS

The functional GSTM1 genotype promotes neutrophilic airway inflammation in humans with atopic asthma in vivo.

Ankaflavin, a novel Nrf-2 activator for attenuating allergic airway inflammation

The role of inflammation-induced oxidative stress in the pathogenesis and progression of chronic inflammatory airways diseases has received increasing attention in recent years. Nuclear factor-erythroid 2 related factor 2 (Nrf-2) is the primary transcription factor that regulates the expression of antioxidant and detoxifying enzymes. In this study, yellow pigment ankaflavin (AK), derived from Monascus-fermented products, elevated nuclear Nrf-2 protein translocation in both the A549 lung cell line and the lungs of ovalbumin (OVA)-challenged mice. Furthermore, AK increased the mRNA expression of antioxidant enzymes regulated by Nrf-2, leading to a reduction in allergen-driven airway inflammation, mucus cell hyperplasia, and eosinophilia in OVA-challenged mice. Additionally, AK prevented T-cell infiltration and Th2 cytokines including interleukin (IL)-4, IL-5, and IL-13 generation in bronchial alveolar lavage fluid. The adhesion molecules ICAM-1, VCAM-1, and eotaxin were substantially reduced by AK treatment. Importantly, the inhibitory effect of AK on adhesion molecule production and immune cell infiltration was abolished by Nrf-2 small interfering RNA. This is the first study to illustrate that AK acts as a novel Nrf-2 activator for modulating the oxidative stress pathway to improve the lung injury and ameliorate the development of airway inflammation.

Bardoxolone methyl decreases megalin and activates nrf2 in the kidney

Inflammation and oxidative stress are hallmarks and mediators of the progression of CKD. Bardoxolone methyl, a potent activator of the nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated antioxidant and anti-inflammatory response, increases estimated GFR and decreases BUN, serum phosphorus, and uric acid concentrations in patients with moderate to severe CKD. However, it also increases albuminuria, which is associated with inflammation and disease progression. Therefore, we investigated whether this bardoxolone methyl-induced albuminuria may result from the downregulation of megalin, a protein involved in the tubular reabsorption of albumin and lipid-bound proteins. Administration of bardoxolone methyl to cynomolgus monkeys significantly decreased the protein expression of renal tubular megalin, which inversely correlated with the urine albumin-to-creatinine ratio. Moreover, daily oral administration of bardoxolone methyl to monkeys for 1 year did not lead to any adverse effects on renal histopathologic findings but did reduce serum creatinine and BUN, as observed in patients with CKD. Finally, the bardoxolone methyl-induced decrease in megalin corresponded with pharmacologic induction of renal Nrf2 targets, including NAD(P)H:quinone oxidoreductase 1 enzyme activity and glutathione content. This result indicates that Nrf2 may have a role in megalin regulation. In conclusion, these data suggest that the increase in albuminuria that accompanies bardoxolone methyl administration may result, at least in part, from reduced expression of megalin, which seems to occur without adverse effects and with strong induction of Nrf2 targets.

Natural-source d-α-tocopheryl acetate inhibits oxidant stress and modulates atopic asthma in humans in vivo

BACKGROUND

Asthma is associated with oxidant stress and diminished antioxidant defenses. Yet, the mechanistic role of oxidant stress and antioxidant supplementation in human asthmatics remains uncertain. We determined the effect of high doses of the antioxidant natural-source d-α-tocopheryl acetate for 16 weeks on allergen-induced airway oxidant stress, inflammation, and bronchial responsiveness to methacholine and allergen in atopic asthmatics in vivo.

METHODS

Thirty-three mild atopic asthmatics underwent bronchoscopy with baseline bronchoalveolar lavage and segmental allergen challenge. The allergen-challenged airway was lavaged 24 h later. At least 3 weeks later, patients underwent inhaled challenges with methacholine and specific allergen. Volunteers took 1500 IU of natural-source d-α-tocopheryl acetate daily for at least 16 weeks. At the end of the treatment, the two bronchoscopies and inhaled methacholine and allergen challenges were repeated. F(2)-isoprostanes, specific markers of oxidant stress, and selected Th1 and Th2 cytokines were analyzed in the lavage fluid.

RESULTS

Following supplementation of natural-source d-α-tocopheryl acetate, plasma concentrations of α-tocopherol increased and γ-tocopherol decreased. Both baseline and allergen-induced F(2)-isoprostanes significantly decreased, providing biochemical evidence for an antioxidant effect. Natural-source d-α-tocopheryl acetate reduced allergen-provoked concentrations of interleukin 3 and interleukin 4 and augmented levels of interleukin 12 in bronchoalveolar lavage fluid. Natural-source d-α-tocopheryl acetate improved airway responsiveness to methacholine but did not alter airway reactivity to specific allergen.

CONCLUSIONS

Inhibition of oxidant stress by natural-source d-α-tocopheryl acetate modulates allergic inflammation and airway hyperresponsiveness in human atopic asthmatics in vivo. These results need to be confirmed by a randomized placebo-controlled trial.

Fat-soluble vitamins and atopic disease: what is the evidence?

The prevalence of asthma and other atopic disorders continues to increase worldwide. Examination of the epidemiologic patterns has revealed that this rise has occurred primarily in western, industrialised countries and countries transitioning to this lifestyle. While many changes have occurred in human populations over the years, it has been hypothesised that some of the relevant changes that have led to the rise in asthma and atopic disorders have been the changes from a traditional diet to a more western diet consisting of decreased intake of fruits and vegetables (sources of antioxidant vitamins and carotenoids) leading to decreased intakes of vitamins E and A, and a decrease in sun exposure (e.g. greater time spent indoors and heavy use of sunscreen) leading to decreased circulating levels of vitamin D. This review will examine the evidence for an effect of fat-soluble vitamins (vitamins A, D and K) on the development and severity of asthma and allergies. While observational studies suggest that these vitamins may play a salutary role in asthma and allergies, large, well-designed clinical trials are lacking. Of the fat-soluble vitamins, vitamin D holds great promise as an agent for primary and secondary prevention of disease. Ongoing clinical trials will help determine whether results of observational studies can be applied to the clinical setting.