Vitamin E, γ-tocopherol, reduces airway neutrophil recruitment after inhaled endotoxin challenge in rats and in healthy volunteers

Subchronic intranasal lipopolysaccharide exposure induces pulmonary autoimmunity and glomerulonephritis in NZBWF1 mice

Lupus, a systemic autoimmune disease shaped by gene-environment interplay, often progresses to endstage renal failure. While subchronic systemic exposure to bacterial lipopolysaccharide (LPS) triggers autoimmunity and glomerulonephritis in lupus-prone mice, it is unknown if inhaling LPS, which is common in certain occupations, can similarly trigger lupus. Here we determined how subchronic intranasal (IN) LPS instillation influences autoimmunity and glomerulonephritis development in lupusprone NZBWF1 female mice. Briefly, mice were IN-instilled with vehicle or E. coli LPS (0.8 μg/g) twice weekly for 5 wk, followed by necropsy. For systemic comparison, additional cohorts of mice were injected with LPS intraperitoneally (IP) using identical doses/timing. Lungs were assessed for inflammatory and autoimmune responses and then related to systemic autoimmunity and glomerulonephritis. IN/LPS exposure induced in the lung: i) leukocyte infiltration, ii)mRNA signatures for cytokines, chemokines, IFN-regulated, and cell death-related genes, iii) ectopic lymphoid tissue formation, and iv)diverse IgM and IgG autoantibodies (AAbs). Pulmonary effects coincided with enlarged spleens, elevated plasma IgG AAbs, and inflamed IgG-containing kidney glomeruli. In contrast, IP/LPS treatment induced systemic autoimmunity and glomerulonephritis without pulmonary manifestations. Taken together, these preclinical findings suggest the lung could serve as a critical nexus for triggering autoimmunity by respirable LPS in genetically predisposed individuals.

β-Tocotrienol Decreases PDGF-BB-Induced Proliferation and Migration of Human Airway Smooth Muscle Cells by Inhibiting RhoA and Reducing ROS Production

BACKGROUND

Tocotrienols exhibit antioxidant and anti-inflammatory activities. RhoA, a small GTPase protein, plays a crucial role in regulating contractility in airway smooth muscle (ASM). Previous studies have demonstrated that γ-tocotrienols reduce ASM proliferation and migration by inhibiting the activation of RhoA. In this present study, we investigate the effect of another vitamin E isoform, β-tocotrienols, on human ASM cell proliferation and migration stimulated by platelet-derived growth factor-BB (PDGF-BB).

METHODS

Human ASM cells were pre-treated with β-tocotrienol prior to being stimulated with PDGF-BB to induce ASM cell proliferation and migration. The proliferation and migration of PDGF-BB-induced human ASM cells were assessed using colorimetric and transwell migration assays. The intracellular ROS assay kit was employed to quantify reactive oxygen species (ROS) in human ASM cells. Additionally, we explored the effect of β-tocotrienols on the signaling pathways involved in PDGF-BB-induced ASM proliferation and migration.

RESULTS

β-tocotrienol inhibited PDGF-BB-induced ASM cell proliferation and migration by reducing RhoA activation and ROS production. However, in this present study, β-tocotrienol did not affect the signaling pathways associated with cyclin D1, phosphorylated Akt1, and ERK1/2.

CONCLUSIONS

In conclusion, the inhibition of RhoA activation and ROS production by β-tocotrienol, resulting in the reduction in human ASM proliferation and migration, suggests its potential as a treatment for asthma airway remodeling.

Inhaled endotoxin induces a systemic neutrophil response without affecting cardiovascular measures in a randomized cross-over exposure study

OBJECTIVE

The gram-negative bacterial cell wall component endotoxin (lipopolysaccharide, LPS) is a key component of particulate matter (PM). PM exposure is associated with cardiovascular morbidity and mortality. However, the contribution of individual components of PM to acute and chronic cardiovascular measures is not clear. This study examines whether systemic inflammation induced by LPS inhalation causes acute changes in cardiovascular physiology measures.

MATERIALS AND METHODS

In this double blinded, placebo-controlled crossover study, fifteen adult volunteers underwent inhalation exposure to 20,000 EU Clinical Center Reference Endotoxin (CCRE). Peripheral blood and induced sputum neutrophils were obtained at baseline and six hours post-exposure. Blood pressure, measures of left ventricular function (ejection fraction (LVEF) and global longitudinal strain (LVGLS)), and indices of endothelial function (flow mediated dilation (FMD) and velocity time integral during hyperemia (VTIhyp)) were measured before and after treatment. Wilcoxon sign-rank tests and linear mixed models were used for statistical analysis.

RESULTS

In comparison with normal saline, LPS inhalation resulted in significant increases in peripheral blood and sputum neutrophils but was not associated with significant alterations in blood pressure, LVGLS, LVEF, FMD, or VTIhyp.

DISCUSSION AND CONCLUSIONS

In healthy adults, systemic inflammation after LPS inhalation was not associated with acute changes in cardiovascular physiology. Larger studies are needed to investigate the effects of other PM components on inflammation induced cardiovascular dysfunction.

Respiratory Health Effects of Air Pollutants

Air pollution is a risk factor for asthma and respiratory infection. Avoidance of air pollution is the best approach to mitigating the impacts of pollution. Personal preventive strategies are possible, but policy interventions are the most effective ways to prevent pollution and its effect on asthma and respiratory infection.

A pilot randomized clinical trial of γ-tocopherol supplementation on wood smoke-induced neutrophilic and eosinophilic airway inflammation

Background

Air pollutants, including particulates from wood smoke, are a significant cause of exacerbation of lung disease. γ-Tocopherol is an anti-inflammatory isoform of vitamin E that has been shown to reduce allergen-, ozone-, and endotoxin-induced inflammation.

Objective

The objective of this study was to determine whether γ-tocopherol would prevent experimental wood smoke-induced airway inflammation in humans.

Methods

This was a randomized, placebo-controlled clinical trial testing the effect of a short course of γ-tocopherol-enriched supplementation on airway inflammation following a controlled exposure to wood smoke particulates.

Results

Short-course γ-tocopherol intervention did not reduce wood smoke-induced neutrophilic airway inflammation, but it did prevent wood smoke-induced eosinophilic airway inflammation.

Conclusion

γ-Tocopherol is a potential intervention for exacerbation of allergic airway inflammation, but further study examining longer dosing periods is required.

Antioxidant Intake and Biomarkers of Asthma in Relation to Smoking Status-A Review

Asthma is considered a chronic inflammatory disorder associated with airway hyperresponsiveness (AHR). Increased oxidative stress (OS) is a clinical feature of asthma, which promotes the inflammatory responses in bronchial/airway epithelial cells. Smokers and nonsmokers with asthma have been shown to have increases in several OS and inflammatory biomarkers. However, studies suggest significant differences in OS and inflammation biomarkers between smokers and nonsmokers. A few studies suggest associations between antioxidant intake from diet/supplements and asthma in patients with different smoking status. Evidence is lacking on the protective role of antioxidant vitamin and/or mineral consumption against asthma by smoking status with respect to inflammation and OS biomarkers. Therefore, the aim of this review is to highlight current knowledge regarding the relations between antioxidant intake, asthma, and its associated biomarkers, according to smoking status. This paper can be used to guide future research directions towards the health consequences of antioxidant intake in smoking and nonsmoking asthmatics.

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.

Gamma-tocopherol, a major form of vitamin E in diets: Insights into antioxidant and anti-inflammatory effects, mechanisms, and roles in disease management

γ-Tocopherol (γT) is a major form of vitamin E in the US diet and the second most abundant vitamin E in the blood and tissues, while α-tocopherol (αT) is the predominant vitamin E in tissues. During the last >25 years, research has revealed that γT has unique antioxidant and anti-inflammatory activities relevant to disease prevention compared to αT. While both compounds are potent lipophilic antioxidants, γT but not αT can trap reactive nitrogen species by forming 5-nitro-γT, and appears to show superior protection of mitochondrial function. γT inhibits ionophore-stimulated leukotrienes by blocking 5-lipoxygenase (5-LOX) translocation in leukocytes, decreases cyclooxygenase-2 (COX-2)-catalyzed prostaglandins in macrophages and blocks the growth of cancer cells but not healthy cells. For these activities, γT is stronger than αT. Moreover, γT is more extensively metabolized than αT via cytochrome P-450 (CYP4F2)-initiated side-chain oxidation, which leads to formation of metabolites including 13'-carboxychromanol (13'-COOH) and carboxyethyl-hydroxychroman (γ-CEHC). 13'-COOH and γ-CEHC are shown to be the predominant metabolites found in feces and urine, respectively. Interestingly, γ-CEHC has natriuretic activity and 13'-COOH inhibits both COX-1/-2 and 5-LOX activity. Consistent with these mechanistic findings of γT and metabolites, studies show that supplementation of γT mitigates inflammation and disease symptoms in animal models with induced inflammation, asthma and cancer. In addition, supplementation of γT decreased inflammation markers in patients with kidney diseases and mild asthma. These observations support that γT may be useful against inflammation-associated diseases.

Oxidized Phosphatidylcholines Induce Multiple Functional Defects in Airway Epithelial Cells

Oxidative stress is a hallmark of numerous airway diseases, contributing to extensive cell and tissue damage. Cell membranes and the airway mucosal lining are rich in phospholipids that are particularly susceptible to oxidative attack, producing bioactive molecules including oxidized phosphatidylcholines (OxPC). With the recent discovery of elevated OxPC in asthmatic patients after allergen challenge, we hypothesized that OxPC directly contribute to disease by inducing airway epithelial cell dysfunction. We found that OxPC induced concentration-dependent cell stress and loss of viability in BEAS-2B and Calu-3 cell lines and primary human epithelial cells. These responses corresponded with significant epithelial barrier dysfunction, which was further compounded when combining OxPC with an epithelial wound. OxPC inhibited DNA synthesis and migration required to re-establish barrier function, but cells recovered if OxPC were washed off soon after treatment. OxPC induced generation of reactive oxygen species, lipid peroxidation and mitochondrial dysfunction, raising the possibility that OxPC cause pathological lipid metabolism in a self-propagating cycle. The oxidative stress induced by OxPC could not be abrogated by putative OxPC receptor blockers, but partial recovery of barrier function, proliferation and lipid peroxidation could be achieved with the antioxidant n-acetyl cysteine. In summary, we have identified OxPC as a group of bioactive molecules that significantly impair multiple facets of epithelial cell function, consistent with pathological features of asthma. Further characterisation of the mechanisms by which OxPC affect epithelial cells could yield new insights into how oxidative stress contributes to the pathogenesis of airway disease.

Vitamin E beyond Its Antioxidant Label

Vitamin E, comprising tocopherols and tocotrienols, is mainly known as an antioxidant. The aim of this review is to summarize the molecular mechanisms and signaling pathways linked to inflammation and malignancy modulated by its vitamers. Preclinical reports highlighted a myriad of cellular effects like modulating the synthesis of pro-inflammatory molecules and oxidative stress response, inhibiting the NF-κB pathway, regulating cell cycle, and apoptosis. Furthermore, animal-based models have shown that these molecules affect the activity of various enzymes and signaling pathways, such as MAPK, PI3K/Akt/mTOR, JAK/STAT, and NF-κB, acting as the underlying mechanisms of their reported anti-inflammatory, neuroprotective, and anti-cancer effects. In clinical settings, not all of these were proven, with reports varying considerably. Nonetheless, vitamin E was shown to improve redox and inflammatory status in healthy, diabetic, and metabolic syndrome subjects. The anti-cancer effects were inconsistent, with both pro- and anti-malignant being reported. Regarding its neuroprotective properties, several studies have shown protective effects suggesting vitamin E as a potential prevention and therapeutic (as adjuvant) tool. However, source and dosage greatly influence the observed effects, with bioavailability seemingly a key factor in obtaining the preferred outcome. We conclude that this group of molecules presents exciting potential for the prevention and treatment of diseases with an inflammatory, redox, or malignant component.

Identification and treatment of T2-low asthma in the era of biologics

Currently, and based on the development of relevant biologic therapies, T2-high is the most well-defined endotype of asthma. Although much progress has been made in elucidating T2-high inflammation pathways, no specific clinically applicable biomarkers for T2-low asthma have been identified. The therapeutic approach of T2-low asthma is a problem urgently needing resolution, firstly because these patients have poor response to steroids, and secondly because they are not candidates for the newer targeted biologic agents. Thus, there is an unmet need for the identification of biomarkers that can help the diagnosis and endotyping of T2-low asthma. Ongoing investigation is focusing on neutrophilic airway inflammation mediators as therapeutic targets, including interleukin (IL)-8, IL-17, IL-1, IL-6, IL-23 and tumour necrosis factor-α; molecules that target restoration of corticosteroid sensitivity, mainly mitogen-activated protein kinase inhibitors, tyrosine kinase inhibitors and phosphatidylinositol 3-kinase inhibitors; phosphodiesterase (PDE)3 inhibitors that act as bronchodilators and PDE4 inhibitors that have an anti-inflammatory effect; and airway smooth muscle mass attenuation therapies, mainly for patients with paucigranulocytic inflammation. This article aims to review the evidence for noneosinophilic inflammation being a target for therapy in asthma; discuss current and potential future therapeutic approaches, such as novel molecules and biologic agents; and assess clinical trials of licensed drugs in the treatment of T2-low asthma.

Invited review: Cytochrome P450 enzyme involvement in health and inflammatory-based diseases of dairy cattle

Dairy cattle are at the greatest risk of developing diseases around the time of calving because of compromised immune responses and the occurrence of oxidative stress. Both the development of compromised immunity and oxidative stress are influenced directly or indirectly by the metabolism of polyunsaturated fatty acids (PUFA) and fat-soluble vitamins. The cytochrome P450 (CYP450) family of enzymes is central to the metabolism of both classes of these compounds, but to date, the importance of CYP450 in the health of dairy cattle is underappreciated. As certain CYP450 isoforms metabolize both PUFA and fat-soluble vitamins, potential interactions may occur between PUFA and fat-soluble vitamins that are largely unexplored. For example, one CYP450 that generates anti-inflammatory oxylipids from arachidonic acid additionally contributes to the activation of vitamin D. Other potential substrate interactions between PUFA and vitamins A and E may exist as well. The intersection of PUFA and fat-soluble vitamin metabolism by CYP450 suggest that this enzyme system could provide an understanding of how immune function and oxidant status interconnect, resulting in increased postpartum disease occurrence. This review will detail the known contributions of bovine CYP450 to the regulation of oxylipids with a focus on enzymes that may also be involved in the metabolism of fat-soluble vitamins A, D, and E that contribute to antioxidant defenses. Although the activity of specific CYP450 is generally conserved among mammals, important differences exist in cattle, such as the isoforms primarily responsible for activation of vitamin D that makes their specific study in cattle of great importance. Additionally, a CYP450-driven inflammatory positive feedback loop is proposed, which may contribute to the dysfunctional inflammatory responses commonly found during the transition period. Establishing the individual enzyme isoform contributions to oxylipid biosynthesis and the regulation of vitamins A, D, and E may reveal how the CYP450 family of enzymes can affect inflammatory responses during times of increased susceptibility to disease. Determining the potential effect of each CYP450 on disease susceptibility or pathogenesis may allow for the targeted manipulation of the CYP450 pathways to influence specific immune responses and antioxidant defenses during times of increased risk for health disorders.

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.

Clinical Impact Potential of Supplemental Nutrients as Adjuncts of Therapy in High-Risk COVID-19 for Obese Patients

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease (COVID-19) in China at the end of 2019 caused a major global pandemic and continues to be an unresolved global health crisis. The supportive care interventions for reducing the severity of symptoms along with participation in clinical trials of investigational treatments are the mainstay of COVID-19 management because there is no effective standard therapy for COVID-19. The comorbidity of COVID-19 rises in obese patients. Micronutrients may boost the host immunity against viral infections, including COVID-19. In this review, we discuss the clinical impact potential of supplemental nutrients as adjuncts of therapy in high-risk COVID-19 for obese patients.

Asthma: New Integrative Treatment Strategies for the Next Decades

Asthma is a chronic disease whose main anatomical-functional alterations are grouped into obstruction, nonspecific bronchial hyperreactivity, inflammation and airway remodeling. Currently, the Global Initiative of Asthma 2020 (GINA 2020) suggests classifying it into intermittent cases, slightly persistent, moderately persistent and severely persistent, thus determining the correct guidelines for its therapy. In general, the drugs used for its management are divided into two groups, those with a potential bronchodilator and the controlling agents of inflammation. However, asthmatic treatments continue to evolve, and notable advances have been made possible in biological therapy with monoclonal antibodies and in the relationship between this disease and oxidative stress. This opens a new path to dietary and herbal strategies and the use of antioxidants as a possible therapy that supports conventional pharmacological treatments and reduces their doses and/or adverse effects. This review compiles information from different published research on risk factors, pathophysiology, classification, diagnosis and the main treatments; likewise, it synthesizes the current evidence of herbal medicine for its control. Studies on integrative medicine (IM) therapies for asthmatic control are critically reviewed. An integrative approach to the prevention and management of asthma warrants consideration in clinical practice. The intention is to encourage health professionals and scientists to expand the horizons of basic and clinical research (preclinical, clinical and integrative medicine) on asthma control.

Nutrition and corticosteroids in the treatment of sarcoidosis

PURPOSE OF REVIEW

Sarcoidosis is a chronic disease, which is routinely treated with corticosteroids. Steroid resistance or steroid-induced adverse effects require alternatives. Other immune-modulating pharmacological treatments have been developed, and therefore expanded tremendously. Until now, the role of nutrition in the overall management of sarcoidosis has been neglected although anti-inflammatory properties of nutritional components have been known for many years now. New nutritional possibilities emerge from already existing data and offer new therapeutic avenues in the treatment of sarcoidosis.

RECENT FINDINGS

Various dietary components have been shown to reduce pulmonary inflammatory processes. It is increasingly recognized, however, that the specificity and magnitude of the effect of nutrition differs from pharmacological interventions. Conventional randomized clinical trials are less suitable to test the effect of nutrition in comparison with testing drugs. Mechanistic knowledge on the action of dietary components in conjunction with an increasing understanding of the molecular processes underlying steroid resistance (as investigated in asthma and COPD and unfortunately hardly in sarcoidosis) lead to exciting suggestions on combinations of nutrition/nutritional bioactive compounds and corticosteroids that may benefit sarcoidosis patients.

SUMMARY

In order to understand the effects of nutrition in chronic disease, it is important to elucidate mechanisms and pathways of effects. Several complementing lines of evidence should be integrated in order to be able to advise sarcoidosis patients on a healthy diet as such or in combination with prescribed anti-inflammatory therapy.

Effects of Palm Oil Tocotrienol-Rich Fraction (TRF) and Carotenes in Ovalbumin (OVA)-Challenged Asthmatic Brown Norway Rats

Synthetic therapeutic drugs for asthma, a chronic airway inflammation characterised by strong eosinophil, mast cell, and lymphocyte infiltration, mucus hyper-production, and airway hyper-responsiveness, exhibit numerous side effects. Alternatively, the high antioxidant potential of palm oil phytonutrients, including vitamin E (tocotrienol-rich fractions; TRF) and carotene, may be beneficial for alleviating asthma. Here, we determined the therapeutic efficacy of TRF, carotene, and dexamethasone in ovalbumin-challenged allergic asthma in Brown Norway rats. Asthmatic symptoms fully developed within 8 days after the second sensitization, and were preserved throughout the time course via intranasal ovalbumin re-challenge. Asthmatic rats were then orally administered 30 mg/kg body weight TRF or carotene. TRF-treated animals exhibited reduced inflammatory cells in bronchial alveolar lavage fluid. TRF- and carotene-treated rats exhibited notable white blood cell reduction comparable to that from dexamethasone. TRF- and carotene-treatment also downregulated pro-inflammatory markers (IL-β, IL-6, TNF-α), coincident with anti-inflammatory marker IL-4 and IL-13 upregulation. Treatment significantly reduced asthmatic rat plasma CRP and IgE, signifying improved systemic inflammation. Asthmatic lung histology displayed severe edema and inflammatory cell infiltration in the bronchial wall, whereas treated animals retained healthy, normal-appearing lungs. The phytonutrients tocotrienol and carotene thus exhibit potential benefits for consumption as nutritional adjuncts in asthmatic disease.

Delineation of the Individual Effects of Vitamin E Isoforms on Early Life Incident Wheezing

OBJECTIVES

To test the hypothesis that maternal plasma alpha-tocopherol levels are associated with protection from childhood wheeze and that this protection is modified by gamma-tocopherol.

STUDY DESIGN

We conducted a prospective nested study in the Infant Susceptibility to Pulmonary Infections and Asthma Following Respiratory Syncytial Virus Exposure birth cohort of 652 children with postpartum maternal plasma vitamin E isoforms used as a surrogate for pregnancy concentrations. Our outcomes were wheezing and recurrent wheezing over a 2-year period, ascertained using validated questionnaires. We assessed the association of alpha- and gamma-tocopherol with wheezing outcomes using multivariable adjusted logistic regression, and tested for interaction between the isoforms with respect to the risk for wheezing outcomes.

RESULTS

Children with wheezing (n = 547, n = 167; 31%) and recurrent wheezing (n = 545, n = 55; 10.1%) over a 2-year period were born to mothers with significantly lower postpartum maternal plasma concentrations of alpha-tocopherol, P = .016 and P = .007, respectively. In analyses of IQR increases, alpha-tocopherol was associated with decreased risk of wheezing (aOR 0.70 [95% CI 0.53,0.92]) and recurrent wheezing (aOR 0.63 [95% CI 0.42,0.95]). For gamma-tocopherol, the aOR for wheezing was 0.79 (95% CI 0.56-1.10) and the aOR for recurrent wheezing was 0.56 (95% CI 0.33-0.94, with nonmonotonic association). The association of alpha-tocopherol with wheezing was modified by gamma-tocopherol (P interaction = .05).

CONCLUSIONS

Increases in postpartum maternal plasma alpha-tocopherol isoform concentrations were associated with decreased likelihood of wheezing over a 2-year period. Gamma-tocopherol modified this association.

A Comparison of Vitamin E Status and Associated Pregnancy Outcomes in Maternal⁻Infant Dyads between a Nigerian and a United States Population

Oxidative stress is associated with adverse pregnancy outcomes, and vitamin E has powerful anti-oxidant properties with the potential to impact health outcomes. Tocopherol isomers of vitamin E differ in their ability to modulate inflammation and vary in concentration in diets containing high proportions of processed versus unprocessed foods. The purpose of this study was to compare vitamin E status and associated pregnancy outcomes (mode of delivery, chorioamnionitis, APGARs (measure of appearance, pulse, grimace, activity, respiration), gestational age at delivery, and fetal growth) between maternal–infant dyads in a developed and a developing nation to identify potentially modifiable differences that may impact pregnancy and neonatal outcomes and provide a way to improve maternal and neonatal health. Plasma tocopherol levels were evaluated in 189 Midwestern United States (US) mother–infant pairs and 99 Central Nigerian mother–infant pairs. Maternal and infant concentrations of α-, γ-, and δ-tocopherol were measured using HPLC with diode-array detection. Descriptive statistics were calculated and tocopherol concentrations were associated with clinical outcomes such as mode of delivery, chorioamnionitis, APGARS, and fetal growth. Alpha- and γ-tocopherol levels were higher in the US mothers, (alpha: 12,357.9 (175.23–34,687.75) vs. 8333.1 (1576.59–16,248.40) (mcg/L); p < 0.001) (gamma: 340.7 (224.59–4385.95) vs. 357.5 (66.36–1775.31) (mcg/L); p < 0.001), while δ-tocopherol levels were higher in the Nigerian mothers (delta: 261.7 (24.70–1324.71) vs. 368.9 (43.06–1886.47) (mcg/L); p < 0.001). US infants had higher γ-tocopherol levels than Nigerian infants (203.1 (42.53–1953.23) vs. 113.8 (0.00–823.00) (mcg/L); p < 0.001), while both the Nigerian mothers and infants had higher α:γ-tocopherol ratios (8.5 vs. 26.2, and 8.9 vs. 18.8, respectively; p < 0.001). Our results in both populations show associations between increased circulating γ-tocopherol and negative outcomes like Caesarian sections, in contrast to the associations with positive outcomes such as vaginal delivery seen with increased α:γ-tocopherol ratios. Growth was positively associated with α- and γ-tocopherols in cord blood in the US population, and with cord blood δ-tocopherols in the Nigerian population. Tocopherol levels likely impact health outcomes in pregnancy in a complicated metabolism across the maternal–fetal axis that appears to be potentially influenced by culture and available diet.

Update on Vitamin E and Its Potential Role in Preventing or Treating Bronchopulmonary Dysplasia

Vitamin E is obtained only through the diet and has a number of important biological activities, including functioning as an antioxidant. Evidence that free radicals may contribute to pathological processes such as bronchopulmonary dysplasia (BPD), a disease of prematurity associated with increased lung injury, inflammation and oxidative stress, led to trials of the antioxidant vitamin E (α-tocopherol) to prevent BPD with variable results. These trials were all conducted at supraphysiologic doses and 2 of these trials utilized a formulation containing a potentially harmful excipient. Since 1991, when the last of these trials was conducted, both neonatal management strategies for minimizing oxygen and ventilator-related lung injury and our understanding of vitamin E isoforms in respiratory health have advanced substantially. It is now known that there are differences between the effects of vitamin E isoforms α-tocopherol and γ-tocopherol on the development of respiratory morbidity and inflammation. What is not known is whether improvements in physiologic concentrations of individual or combinations of vitamin E isoforms during pregnancy or following preterm birth might prevent or reduce BPD development. The answers to these questions require adequately powered studies targeting pregnant women at risk of preterm birth or their premature infants immediately following birth, especially in certain subgroups that are at increased risk of vitamin E deficiency (e.g., smokers). The objective of this review is to compile, update, and interpret what is known about vitamin E isoforms and BPD since these first studies were conducted, and suggest future research directions.

Gamma tocopherol-enriched supplement reduces sputum eosinophilia and endotoxin-induced sputum neutrophilia in volunteers with asthma

BACKGROUND

We and others have shown that the gamma tocopherol (γT) isoform of vitamin E has multiple anti-inflammatory and antioxidant actions and that γT supplementation reduces eosinophilic and endotoxin (LPS)-induced neutrophilic airway inflammation in animal models and healthy human volunteers.

OBJECTIVE

We sought to determine whether γT supplementation reduces eosinophilic airway inflammation and acute neutrophilic response to inhaled LPS challenge in volunteers with asthma.

METHODS

Participants with mild asthma were enrolled in a double-blinded, placebo-controlled crossover study to assess the effect of 1200 mg of γT daily for 14 days on sputum eosinophils, mucins, and cytokines. We also assessed the effect on acute inflammatory response to inhaled LPS challenge following γT treatment, focusing on changes in sputum neutrophilia, mucins, and cytokines. Mucociliary clearance was measured using gamma scintigraphy.

RESULTS

Fifteen subjects with mild asthma completed both arms of the study. Compared with placebo, γT notably reduced pre-LPS challenge sputum eosinophils and mucins, including mucin 5AC and reduced LPS-induced airway neutrophil recruitment 6 and 24 hours after challenge. Mucociliary clearance was slowed 4 hours postchallenge in the placebo group but not in the γT treatment group. Total sputum mucins (but not mucin 5AC) were reduced at 24 hours postchallenge during γT treatment compared with placebo.

CONCLUSIONS

When compared with placebo, γT supplementation for 14 days reduced inflammatory features of asthma, including sputum eosinophils and mucins, as well as acute airway response to inhaled LPS challenge. Larger scale clinical trials are needed to assess the efficacy of γT supplements as a complementary or steroid-sparing treatment for asthma.

Many tocopherols, one vitamin E

Four tocopherols are available in nature and are absorbed with the diet, but only one RRR-α-tocopherol satisfies the criteria of being a vitamin. The biological activity of the different tocopherols studied in the rat by the resorption-gestation test has been inconsistently extrapolated to human beings where the tocopherols have no influence on a successful pregnancy. Diminution of RRR-α-tocopherol intake results in diseases characterized by ataxia, whose pathogenetic mechanism, despite vigorous claims, has not been clarified. The calculation of the Daily Reference Intake (DRI), necessary to prevent disease, is based on an obsolete test, the peroxide-induced erythrocyte hemolysis, called the gold standard, but of highly questioned validity. If many epidemiological studies have given positive results, showing prevention by high vitamin E containing diets of cardiovascular events, neurodegenerative disease, macular degeneration and cancer, the clinical confirmatory intervention studies were mostly negative. On the positive side, besides preventing vitamin E deficiency diseases, vitamin E has shown efficacy as anti-inflammatory and immune boosting compound. It has also shown some efficacy in protecting against nonalcoholic hepato-steatosis. At a molecular level, vitamin E and some of its metabolites have shown capacity of regulating cell signaling and modulating gene transcription.

Advance of antioxidants in asthma treatment

Asthma is an allergic disease, characterized as a recurrent airflow limitation, airway hyperreactivity, and chronic inflammation, involving a variety of cells and cytokines. Reactive oxygen species have been proven to play an important role in asthma. The pathogenesis of oxidative stress in asthma involves an imbalance between oxidant and antioxidant systems that is caused by environment pollutants or endogenous reactive oxygen species from inflammation cells. There is growing evidence that antioxidant treatments that include vitamins and food supplements have been shown to ameliorate this oxidative stress while improving the symptoms and decreasing the severity of asthma. In this review, we summarize recent studies that are related to the mechanisms and biomarkers of oxidative stress, antioxidant treatments in asthma.

The effect of dietary components on inflammatory lung diseases - a literature review

Anti-inflammatory treatment in chronic inflammatory lung diseases usually involves glucocorticosteroids. With patients suffering from serious side effects or becoming resistant, specific nutrients, that are suggested to positively influence disease progression, can be considered as new treatment options. The dietary inflammatory index is used to calculate effects of dietary components on inflammation and lung function to identify most potent dietary components, based on 162 articles. The positive effects of n-3 PUFAs and vitamin E on lung function can at least partially be explained by their anti-inflammatory effect. Many other dietary components showed only small or no effects on inflammation and/or lung function, although the number of weighted studies was often too small for a reliable assessment. Optimal beneficial dietary elements might reduce the required amounts of anti-inflammatory treatments, thereby decreasing both side effects and development of resistance as to improve quality of life of patients suffering from chronic inflammatory lung diseases.

α-Tocopherol transfer protein mediates protective hypercapnia in murine ventilator-induced lung injury

RATIONALE

Hypercapnia is common in mechanically ventilated patients. Experimentally, 'therapeutic hypercapnia' can protect, but it can also cause harm, depending on the mechanism of injury. Hypercapnia suppresses multiple signalling pathways. Previous investigations have examined mechanisms that were known a priori, but only a limited number of pathways, each suppressed by CO₂, have been reported.

OBJECTIVE

Because of the complexity and interdependence of processes in acute lung injury, this study sought to fill in knowledge gaps using an unbiased screen, aiming to identify a specifically upregulated pathway.

METHODS AND RESULTS

Using genome-wide gene expression analysis in a mouse model of ventilator-induced lung injury, we discovered a previously unsuspected mechanism by which CO₂ can protect against injury: induction of the transporter protein for α-tocopherol, α-tocopherol transfer protein (αTTP). Pulmonary αTTP was induced by inspired CO₂ in two in vivo murine models of ventilator-induced lung injury; the level of αTTP expression correlated with degree of lung protection; and, absence of the αTTP gene significantly reduced the protective effects of CO₂. α-Tocopherol is a potent antioxidant and hypercapnia increased lung α-tocopherol in wild-type mice, but this did not alter superoxide generation or expression of NRF2-dependent antioxidant response genes in wild-type or in αTTP^-/- mice. In concordance with a regulatory role for α-tocopherol in lipid mediator synthesis, hypercapnia attenuated 5-lipoxygenase activity and this was dependent on the presence of αTTP.

CONCLUSIONS

Inspired CO₂ upregulates αTTP which increases lung α-tocopherol levels and inhibits synthesis of a pathogenic chemoattractant.

Neutrophilic inflammation in asthma: mechanisms and therapeutic considerations

INTRODUCTION

Neutrophilic airway inflammation represents a pathologically distinct form of asthma and frequently appears in symptomatic adulthood asthmatics. However, clinical impacts and mechanisms of the neutrophilic inflammation have not been thoroughly evaluated up to date. Areas covered: Currently, distinct clinical manifestations, triggers, and molecular mechanisms of the neutrophilic inflammation (namely Toll-like receptor, Th1, Th17, inflammasome) are under investigation in asthma. Furthermore, possible role of the neutrophilic inflammation is being investigated in respect to the airway remodeling. We searched the related literatures published during the past 10 years on the website of Pub Med under the title of asthma and neutrophilic inflammation in human. Expert commentary: Epidemiologic and experimental studies have revealed that the neutrophilic airway inflammation is induced by a wide variety of stimuli including ozone, particulate matters, cigarette smoke, occupational irritants, endotoxins, microbial infection and colonization, and aeroallergens. These triggers provoke diverse immune and inflammatory responses leading to progressive and sometimes irreversible airway obstruction. Clinically, neutrophilic airway inflammation is frequently associated with severe asthma and poor response to glucocorticoid therapy, indicating the need for other treatment strategies. Accordingly, therapeutics will be targeted against the main mediators behind the underlying molecular mechanisms of the neutrophilic inflammation.

A proof-of-concept clinical study examining the NRF2 activator sulforaphane against neutrophilic airway inflammation

Sulforaphane (SFN), a naturally occurring isothiocyanate found in cruciferous vegetables, is implicated as a possible therapy for airway inflammation via induction of the transcription factor NF-E2-related factor 2 (NRF2). In this proof-of-concept clinical study, we show that supplementation of SFN with broccoli sprout homogenate in healthy human subjects did not induce expression of antioxidant genes or protect against neutrophilic airway inflammation in an ozone-exposure model. Therefore, dietary sulforaphane supplementation is not a promising candidate for larger scale clinical trials targeting airway inflammation.

TRIAL REGISTRATION

NCT01625130 . Registered 19 June, 2012.

Vitamin E and the risk of childhood asthma

INTRODUCTION

Asthma, a heterogeneous disease with multiple phenotypes, remains a significant health problem. Present treatments are not curative and prevention should be our ultimate goal. Vitamin E supplementation presents a potential easy and cheap preventive therapy but the results of studies are confusing and sometimes contradictory. Clarification is needed.

AREAS COVERED

Animal studies and research in pregnant women suggest enhanced lifetime resistance to asthma with appropriate fetal exposure to vitamin E. Vitamin E's preventive role is complex and includes functional variations of the different isoforms. Expert commentary: We review the most recent literature on the role of vitamin E isoforms on: lung inflammation, immune development, animal and clinical studies during pregnancy, and the potential influence of vitamin E isoforms on asthma development in offspring. We point out where data are seemingly contradictory, explain why this is so, and comment on where further clarifying research is needed and its future direction.

γ-Tocopherol supplementation of allergic female mice augments development of CD11c+CD11b+ dendritic cells in utero and allergic inflammation in neonates

γ-Tocopherol increases responses to allergen challenge in allergic adult mice, but it is not known whether γ-tocopherol regulates the development of allergic disease. Development of allergic disease often occurs early in life. In clinical studies and animal models, offspring of allergic mothers have increased responsiveness to allergen challenge. Therefore, we determined whether γ-tocopherol augments development of allergic responses in offspring of allergic female mice. Allergic female mice were supplemented with γ-tocopherol starting at mating. The pups from allergic mothers developed allergic lung responses, whereas pups from saline-treated mothers did not respond to allergen challenge. The γ-tocopherol supplementation of allergic female mice increased the numbers of eosinophils twofold in the pup bronchoalveolar lavage and lungs after allergen challenge. There was also about a twofold increase in pup lung CD11b(+) subsets of CD11c(+) dendritic cells and in numbers of these dendritic cells expressing the transcription factor IRF4. There was no change in several CD11b(-) dendritic cell subsets. Furthermore, maternal supplementation with γ-tocopherol increased the number of fetal liver CD11b(+)CD11c(+) dendritic cells twofold in utero. In the pups, γ-tocopherol increased lung expression of the inflammatory mediators CCL11, amphiregulin, activin A, and IL-5. In conclusion, maternal supplementation with γ-tocopherol increased fetal development of subsets of dendritic cells that are critical for allergic responses and increased development of allergic responses in pups from allergic mothers. These results have implications for supplementation of allergic mothers with γ-tocopherol in prenatal vitamins.

Riboflavin attenuates lipopolysaccharide-induced lung injury in rats

Riboflavin (vitamin B2) is an easily absorbed micronutrient with a key role in maintaining health in humans and animals. It is the central component of the cofactors flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) and is therefore required by all flavoproteins. Riboflavin also works as an antioxidant by scavenging free radicals. The present study was designed to evaluate the effects of riboflavin against acute lungs injury induced by the administration of a single intranasal dose (20 μg/rat) of lipopolysaccharides (LPS) in experimental rats. Administration of LPS resulted in marked increase in malondialdehyde (MDA) level (p < 0.01) and MPO activity (p < 0.001), whereas marked decrease in glutathione (GSH) content (p < 0.001), glutathione reductase (GR) (p < 0.001) and glutathione peroxidase (p < 0.01) activity. These changes were significantly (p < 0.001) improved by treatment with riboflavin in a dose-dependent manner (30 and 100 mg/kg, respectively). Riboflavin (100 mg/kg, p.o.) showed similar protective effects as dexamethasone (1 mg/kg, p.o.). Administration of LPS showed marked cellular changes including interstitial edema, hemorrhage, infiltration of PMNs, etc., which were reversed by riboflavin administration. Histopathological examinations showed normal morphological structures of lungs tissue in the control group. These biochemical and histopathological examination were appended with iNOS and CAT gene expression. The iNOS mRNA expression was increased significantly (p < 0.001) and levels of CAT mRNA expression was decreased significantly (p < 0.001) in the animals exposed to LPS, while treatment with riboflavin significantly (p < 0.01) improved expression of both gene. In conclusion, the present study clearly demonstrated that riboflavin caused a protective effect against LPS-induced ALI. These results suggest that riboflavin may be used to protect against toxic effect of LPS in lungs.

Key role for scavenger receptor B-I in the integrative physiology of host defense during bacterial pneumonia

Scavenger receptor B-I (SR-BI) is a multirecognition receptor that regulates cholesterol trafficking and cardiovascular inflammation. Although it is expressed by neutrophils (PMNs) and lung-resident cells, no role for SR-BI has been defined in pulmonary immunity. Herein, we report that, compared with SR-BI(+/+) counterparts, SR-BI(-/-) mice suffer markedly increased mortality during bacterial pneumonia associated with higher bacterial burden in the lung and blood, deficient induction of the stress glucocorticoid corticosterone, higher serum cytokines, and increased organ injury. SR-BI(-/-) mice had significantly increased PMN recruitment and cytokine production in the infected airspace. This was associated with defective hematopoietic cell-dependent clearance of lipopolysaccharide from the airspace and increased cytokine production by SR-BI(-/-) macrophages. Corticosterone replacement normalized alveolar neutrophilia but not alveolar cytokines, bacterial burden, or mortality, suggesting that adrenal insufficiency derepresses PMN trafficking to the SR-BI(-/-) airway in a cytokine-independent manner. Despite enhanced alveolar neutrophilia, SR-BI(-/-) mice displayed impaired phagocytic killing. Bone marrow chimeras revealed this defect to be independent of the dyslipidemia and adrenal insufficiency of SR-BI(-/-) mice. During infection, SR-BI(-/-) PMNs displayed deficient oxidant production and CD11b externalization, and increased surface L-selectin, suggesting defective activation. Taken together, SR-BI coordinates several steps in the integrated neutrophilic host defense response to pneumonia.

Nutrition and respiratory health--feature review

Diet and nutrition may be important modifiable risk factors for the development, progression and management of obstructive lung diseases such as asthma and chronic obstructive pulmonary disease (COPD). This review examines the relationship between dietary patterns, nutrient intake and weight status in obstructive lung diseases, at different life stages, from in-utero influences through childhood and into adulthood. In vitro and animal studies suggest important roles for various nutrients, some of which are supported by epidemiological studies. However, few well-designed human intervention trials are available to definitively assess the efficacy of different approaches to nutritional management of respiratory diseases. Evidence for the impact of higher intakes of fruit and vegetables is amongst the strongest, yet other dietary nutrients and dietary patterns require evidence from human clinical studies before conclusions can be made about their effectiveness.

The shifting perception on antioxidants: the case of vitamin E and β-carotene

Antioxidants are vital for aerobic life, and for decades the expectations of antioxidants as health promoting agents were very high. However, relatively recent meta-analyses of clinical studies show that supplementation of antioxidants does not result in the presumed health benefit, but is associated with increased mortality. The dilemma that still needs to be solved is: what are antioxidants in the end, healthy or toxic? We have evaluated this dilemma by examining the presumed health effects of two individual antioxidants with opposite images i.e. the “poisonous” β-carotene and the “wholesome” vitamin E and focused on one aspect, namely their role in inducing BPDE-DNA adducts. It appears that both antioxidants promote DNA adduct formation indirectly by inhibition of the protective enzyme glutathione-S-transferase π (GST π). Despite their opposite image, both antioxidants display a similar type of toxicity. It is concluded that, in the appreciation of antioxidants, first their benefits should be identified and substantiated by elucidating their molecular mechanism. Subsequently, the risks should be identified including the molecular mechanism. The optimal benefit–risk ratio has to be determined for each antioxidant and each individual separately, also considering the dose.

•

To date, the debate on the health benefit of antioxidants continues.

•

The effect of vitamin E and β-carotene on BPDE-DNA adduct formation was evaluated.

•

Both antioxidants promote DNA adduct formation by inhibition of GST π.

•

Accurate benefit–risk analyses give a balanced view on the effects of antioxidants.

Anti-TNF inhibits the airways neutrophilic inflammation induced by inhaled endotoxin in human

BACKGROUND

Inhaled endotoxin induces airways'neutrophilia, in human. TNF-a being a key cytokine in the response to endotoxin, the effect of anti-TNF on the endotoxin-induced neutrophilic response was evaluated among healthy volunteers.

METHODS

Among a population of 30 healthy subjects, an induced-sputum was collected 2 weeks before, and 24 hours after an inhalation of 20 mcg endotoxin (E. coli 026:B6). Then, the subjects were randomized into 3 parallel groups treated with control, oral methylprednisolone 20 mg/day during 7 days or anti-TNF (adalimumab, Humira®, Abbott) 40 mg s.c.. One week later, an induced-sputum was sampled, 24 hours after an inhalation of endotoxin.

RESULTS

After endotoxin inhalation, the number of total cells, neutrophils and macrophages was significantly increased (p <0.001). Compared to the response to endotoxin among the control group, anti-TNF inhibited the endotoxin-induced neutrophil influx, both in relative (51.3 (±6.4)% versus 26.2 (±5.3)%, p <0.002) and in absolute values (1321 (443-3935) cells/mcL versus 247 (68-906) cells/mcL, p <0.02). The endotoxin-induced neutrophilic response was not significantly modified among the control group and oral corticosteroid group.

CONCLUSIONS

While oral corticosteroid had no effect, anti-TNF inhibited the neutrophil influx in sputum, induced by inhalation of endotoxin, in human subject. The endotoxin model could be an early predictor of clinical efficacy of novel therapeutics.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02252809 (EudraCT2008-005526-37).

IL-1 receptor antagonist reduces endotoxin-induced airway inflammation in healthy volunteers

BACKGROUND

Asthma with neutrophil predominance is challenging to treat with corticosteroids. Novel treatment options for asthma include those that target innate immune activity. Recent literature has indicated a significant role for IL-1β in both acute and chronic neutrophilic asthma.

OBJECTIVE

This study used inhaled endotoxin (LPS) challenge as a model of innate immune activation to (1) assess the safety of the IL-1 receptor antagonist anakinra in conjunction with inhaled LPS and (2) to test the hypothesis that IL-1 blockade will suppress the acute neutrophil response to challenge with inhaled LPS.

METHODS

In a phase I clinical study 17 healthy volunteers completed a double-blind, placebo-controlled crossover study in which they received 2 daily subcutaneous doses of 1 mg/kg anakinra (maximum dose, 100 mg) or saline (placebo). One hour after the second treatment dose, subjects underwent an inhaled LPS challenge. Induced sputum was assessed for neutrophils 4 hours after inhaled LPS. The effect of anakinra compared with placebo on airway neutrophil counts and airway proinflammatory cytokine levels after LPS challenge was compared by using a linear mixed-model approach.

RESULTS

Anakinra pretreatment significantly diminished airway neutrophilia compared with placebo. LPS-induced IL-1β, IL-6, and IL-8 levels were significantly reduced during the anakinra treatment period compared with those seen after placebo. Subjects tolerated the anakinra treatment well without an increased frequency of infections attributable to anakinra treatment.

CONCLUSIONS

Anakinra effectively reduced airway neutrophilic inflammation and resulted in no serious adverse events in a model of inhaled LPS challenge. Anakinra is a potential therapeutic candidate for treatment of asthma with neutrophil predominance in diseased populations.

Vitamin E and D regulation of allergic asthma immunopathogenesis

Asthma occurs as complex interactions of the environmental and genetics. Clinical studies and animal models of asthma indicate dietary factors such as vitamin E and vitamin D as protective for asthma risk. In this review, we discuss opposing regulatory functions of tocopherol isoforms of vitamin E and regulatory functions of vitamin D in asthma and how the variation in global prevalence of asthma may be explained, at least in part, by these dietary components.

Natural forms of vitamin E: metabolism, antioxidant, and anti-inflammatory activities and their role in disease prevention and therapy

The vitamin E family consists of four tocopherols and four tocotrienols. α-Tocopherol (αT) is the predominant form of vitamin E in tissues and its deficiency leads to ataxia in humans. However, results from many clinical studies do not support a protective role of αT in disease prevention in people with adequate nutrient status. On the other hand, recent mechanistic studies indicate that other forms of vitamin E, such as γ-tocopherol (γT), δ-tocopherol, and γ-tocotrienol, have unique antioxidant and anti-inflammatory properties that are superior to those of αT in prevention and therapy against chronic diseases. These vitamin E forms scavenge reactive nitrogen species, inhibit cyclooxygenase- and 5-lipoxygenase-catalyzed eicosanoids, and suppress proinflammatory signaling such as NF-κB and STAT3/6. Unlike αT, other vitamin E forms are significantly metabolized to carboxychromanols via cytochrome P450-initiated side-chain ω-oxidation. Long-chain carboxychromanols, especially 13'-carboxychromanols, are shown to have stronger anti-inflammatory effects than unmetabolized vitamins and may therefore contribute to the beneficial effects of vitamin E forms in vivo. Consistent with mechanistic findings, animal and human studies show that γT and tocotrienols may be useful against inflammation-associated diseases. This review focuses on non-αT forms of vitamin E with respect to their metabolism, anti-inflammatory effects and mechanisms, and in vivo efficacy in preclinical models as well as human clinical intervention studies.

Vitamin E, γ-tocopherol, diminishes ex vivo basophil response to dust mite allergen

Epidemiologic studies suggest that dietary vitamin E is a candidate intervention for atopic disease. We used in vitro and ex vivo exposures to test the hypothesis that the most common dietary isoform of vitamin E, γ-tocopherol (γT), could suppress FcεRI-mediated basophil activation. Rat basophilic leukemia (RBL)-SX38 cells that express human FcεRI were treated with or without γT, followed by stimulation with α-IgE. In the ex vivo study, 20 Der f 1-allergic volunteers consumed a γT-enriched supplement for 7 days. Their basophils were challenged ex vivo with α-IgE and graded doses of Der f 1 before and after the supplementation period. γt treatment of RBL-SX38 cells significantly reduced basophil degranulation and de novo TH2 cytokine production. Daily consumption of a γT-rich supplement by dust mite-allergic volunteers reduced basophil activation after ex vivo dust mite challenge. Vitamin E supplements rich in γT may be useful adjuncts in decreasing atopic disease.

The vitamin E isoforms α-tocopherol and γ-tocopherol have opposite associations with spirometric parameters: the CARDIA study

Background

Clinical studies of the associations of vitamin E with lung function have reported conflicting results. However, these reports primarily examine the α-tocopherol isoform of vitamin E and have not included the isoform γ-tocopherol which we recently demonstrated in vitro opposes the function of α-tocopherol. We previously demonstrated, in vitro and in animal studies, that the vitamin E isoform α-tocopherol protects, but the isoform γ-tocopherol promotes lung inflammation and airway hyperresponsiveness.

Methods

To translate these findings to humans, we conducted analysis of 4526 adults in the Coronary Artery Risk Development in Young Adults (CARDIA) multi-center cohort with available spirometry and tocopherol data in blacks and whites. Spirometry was obtained at years 0, 5, 10, and 20 and serum tocopherol was from years 0, 7 and 15 of CARDIA.

Results

In cross-sectional regression analysis at year 0, higher γ-tocopherol associated with lower FEV₁ (p = 0.03 in blacks and p = 0.01 in all participants) and FVC (p = 0.01 in blacks, p = 0.05 in whites, and p = 0.005 in all participants), whereas higher α-tocopherol associated with higher FVC (p = 0.04 in blacks and whites and p = 0.01 in all participants). In the lowest quartile of α-tocopherol, higher γ-tocopherol associated with a lower FEV₁ (p = 0.05 in blacks and p = 0.02 in all participants). In contrast, in the lowest quartile of γ-tocopherol, higher α-tocopherol associated with a higher FEV₁ (p = 0.03) in blacks. Serum γ-tocopherol >10 μM was associated with a 175–545 ml lower FEV₁ and FVC at ages 21–55 years.

Conclusion

Increasing serum concentrations of γ-tocopherol were associated with lower FEV1 or FVC, whereas increasing serum concentrations of α-tocopherol was associated with higher FEV1 or FVC. Based on the prevalence of serum γ-tocopherol >10 μM in adults in CARDIA and the adult U.S. population in the 2011 census, we expect that the lower FEV₁ and FVC at these concentrations of serum γ-tocopherol occur in up to 4.5 million adults in the population.

Supplementation with γ-tocopherol attenuates endotoxin-induced airway neutrophil and mucous cell responses in rats

Neutrophil-mediated tissue injury is a shared pathogenesis of both chronic pulmonary diseases and acute responses to pathogens, allergens, and airborne pollutants. Interventions to minimize toxic effects of neutrophil-derived oxidants and proteases are usually limited to corticosteroids, which can have adverse side effects. We used a rodent model of endotoxin-induced lung injury to test the hypothesis that the dietary supplement γ-tocopherol (γT), a natural form of vitamin E with antioxidant and novel anti-inflammatory properties, will protect from adverse nasal and pulmonary inflammatory responses induced by endotoxin (lipopolysaccharide; LPS). Male Fisher F344 rats were intranasally (i.n.) instilled with LPS for 2 consecutive days. Beginning 2 days before i.n. LPS, the rats were gavaged daily with 30mg/kg γT. Twenty-four hours after the last i.n. LPS, bronchoalveolar lavage fluid (BALF) was collected, and pulmonary and nasal tissues were analyzed for gene expression and morphometric analyses of neutrophils and intraepithelial mucosubstances (IM). LPS caused increased BALF total cells (70% increase), neutrophils (300%), protein (35%), PGE2 (500%), and secreted mucins (75%). Robust increases in neutrophils and IM were detected in conducting airways. Pulmonary expression of MUC5AC, MIP-2, CINC-1, and MCP-1 was elevated three- to eightfold by LPS. Treatment with γT inhibited LPS-induced increases in BALF total cells, neutrophils, protein, PGE2, and secreted mucins, as well as IM and tissue neutrophil influx. Furthermore γT induced the expression of the regulatory cytokines IL-10 and IFN-γ while decreasing MUC5AC, MIP-2, CINC-1, and MCP-1. These data demonstrate novel therapeutic effects of the dietary vitamin E γT promoting anti-inflammatory pathways to protect from neutrophil-mediated lung injury.

Vitamin E isoforms as modulators of lung inflammation

Asthma and allergic diseases are complex conditions caused by a combination of genetic and environmental factors. Clinical studies suggest a number of protective dietary factors for asthma, including vitamin E. However, studies of vitamin E in allergy commonly result in seemingly conflicting outcomes. Recent work indicates that allergic inflammation is inhibited by supplementation with the purified natural vitamin E isoform α-tocopherol but elevated by the isoform γ-tocopherol when administered at physiological tissue concentrations. In this review, we discuss opposing regulatory effects of α-tocopherol and γ-tocopherol on allergic lung inflammation in clinical trials and in animal studies. A better understanding of the differential regulation of inflammation by isoforms of vitamin E provides a basis towards the design of clinical studies and diets that would effectively modulate inflammatory pathways in lung disease.

Two faces of vitamin E in the lung

Asthma and allergic lung disease occur as complex environmental and genetic interactions. Clinical studies of asthma indicate a number of protective dietary factors, such as vitamin E, on asthma risk. However, these studies have had seemingly conflicting outcomes. In this perspective, we discuss opposing regulatory effects of tocopherol isoforms of vitamin E, mechanisms for tocopherol isoform regulation of allergic lung inflammation, association of vitamin E isoforms with outcomes in clinical studies, and how the variation in global prevalence of asthma may be explained, at least in part, by vitamin E isoforms.