Application of vitamin E to antagonize SWCNTs-induced exacerbation of allergic asthma

Mechanisms of exacerbation of Th2-mediated eosinophilic allergic asthma induced by plastic pollution derivatives (PPD): A molecular toxicological study involving lung cell ferroptosis and metabolomics

Polystyrene microplastics (PS-MP) and dibutyl phthalate (DBP) are plastic pollution derivatives (PPDs) commonly found in the natural environment. To investigate the effects of PPD exposure on the risk of allergic asthma, we established a PPD exposure group in a mouse model. The dose administered for PS-MP was 0.1 mg/d and for DBP was 30 mg/kg/d, with a 5-week oral administration period. The pathological changes of airway tissue and the increase of oxidative stress and inflammatory response confirmed that PPD aggravated eosinophilic allergic asthma in mice. The mitochondrial morphological changes and metabolomics of mice confirmed that ferrotosis and oxidative stress played key roles in this process. Treatment with 100 mg/Kg deferoxamine (DFO) provided significant relief, and metabolomic analysis of lung tissue supported the molecular toxicological. Our findings suggest that the increased levels of reactive oxygen species (ROS) in the lungs lead to Th2-mediated eosinophilic inflammation, characterized by elevated IL-4, IL-5, and eosinophils, and reduced INF-γ levels. This inflammatory response is mediated by the NFκB pathway and exacerbates type I hypersensitivity through increased IL-4 production. In this study, the molecular mechanism by which PPD aggravates asthma in mice was elucidated, which helps to improve the understanding of the health effects of PPD and lays a theoretical foundation for addressing the health risks posed by PPD.

Toxicity and Mechanisms of Engineered Nanoparticles in Animals with Established Allergic Asthma

Asthma is a chronic respiratory disease that is highly sensitive to environmental pollutants, including engineered nanoparticles (NPs). Exposure to NPs has become a growing concern for human health, especially for susceptible populations. Toxicological studies have demonstrated strong associations between ubiquitous NPs and allergic asthma. In this review, we analyze articles that focus on adverse health effects induced by NPs in animal models of allergic asthma to highlight their critical role in asthma. We also integrate potential mechanisms that could stimulate and aggravate asthma by NPs. The toxic effects of NPs are influenced by their physicochemical properties, exposure dose, duration, route, as well as the exposure order between NPs and allergens. The toxic mechanisms involve oxidative stress, various inflammasomes, antigen presenting cells, immune cells, and signaling pathways. We suggest that future research should concentrate on establishing standardized models, exploring mechanistic insights at the molecular level, assessing the combined effects of binary exposures, and determining safe exposure levels of NPs. This work provides concrete evidence of the hazards posed by NPs in animals with compromised respiratory health and supports the modifying role of NPs exposure in allergic asthma.

Plants anatomically engineered by nanomaterials

Anatomical characteristics are essential in determining the stress that affects plants. In addition, they provided a piece of evidence for environmental pollution. The increasing use of nanomaterials (EnNos) in industries, medicine, agriculture, and all fields. Nanomaterials also have many uses as a new science; they have toxic effects that have not been studied well. Therefore, this research was interested in recording recent studies on (EnNos) and their impact on the anatomical characteristics of plants. Moreover, the possibility of using anatomical characteristics as evidence of nano contamination (nanotoxicity) in plants comprises a crucial living component of the ecosystem. Studies on the effect of EnNos (carbon) on plant anatomy indicated that excess EnNos content affects the anatomical structure of the plant from the vital structures of the root, stem and leaves. Toxicological effect on xylem and phylum vessels from toxicological studies to date, Toxicological effects on EnNos of various kinds can be toxic if they are not bound to a substrate or freely circulating in living systems. Different types of EnNos, behavior, and plant capacity generate different paths. Moreover, different, or even conflicting, conclusions have been drawn from most studies on the interactions of EnNos with plants. Therefore, this paper comprehensively reviews studies on different types of carbon EnNos and their interactions with different plant species at the anatomical responses. Keywords: Anatomical characteristics, nanomaterials, nanotoxicity, Fullerene and Carbon Nanotubes

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.

Toxic effect of cooking oil fume (COF) on lungs: Evidence of endoplasmic reticulum stress in rat

BACKGROUND

Cooking oil fumes (COF) is one of the primary sources of indoor air pollution in China, which is associated with respiratory diseases such as acute lung injury and lung cancer. However, evidence of COF toxic effect was few.

OBJECTIVES

The research was aimed to investigate the toxic effect and the underlying mechanisms induced by COF.

METHODS

The female Wistar rats were randomly divided into several groups, including control group, COF exposure group and VE protection group, and instilled intratracheally with different COF suspensions (0.2, 2, 20 mg/kg) or saline once every 3 days for 30 days. After 24 h of final exposure, all rat were anesthetic euthanasia to draw materials. The alveolar lavage fluid (BALF) was for inflammatory cell count. The lung homogenate was to determine the biochemical indexes such as oxidative stress, apoptosis factors, carcinogenic toxicity and endoplasmic reticulum (ER) stress. The left lung was made for immunohistochemical and histopathological analysis.

RESULTS

The results showed that the levels of oxidative stress (ROS), apoptosis factors (NF-κB), carcinogenic toxicity (P53 and 8-OhdG), ER stress (IRE-1α and Caspase-12) in 2 mg/kg and 20 mg/kg COF exposure groups were significantly increased compared with the saline groups. The above pathological changes were improved after vitamin E (VE) supplementation. In addition, the immunohistochemical and histopathological analysis found the same trend.

CONCLUSION

The COF had health risk of heredity and potential carcinogenicity. Besides, COFs can not only induce oxidative stress, but also induce ER stress in lung and airway epithelial cells of female rats through the unfolded protein reaction (UPR) pathway. It revealed that the oxidative stress and ER stress interacted in aggravating lung injury. VE could effectively alleviate the lung injury causing by COF exposure.

The Toxicology of Engineered Nanomaterials in Asthma

PURPOSE OF REVIEW

The explosive growth of the nanotechnology industry has necessitated the examination of engineered nanomaterials (ENMs) for their toxicity. The unique properties that make ENMs useful also make them a health risk, and individuals with pre-existing diseases such as asthma are likely more susceptible. This review summarizes the current literature on the ability of ENMs to both exacerbate and directly cause asthma.

RECENT FINDINGS

Recent studies highlight the ability of metal nanoparticles (NPs) and carbon nanotubes (CNTs) to not only exacerbate pre-existing asthma in animal models but also initiate allergic airway disease directly. CNTs alone are shown to cause airway mucus production, elevated serum IgE levels, and increased T_H2 cytokine levels, all key indicators of asthma. The ability of ENMs to modulate the immune response in asthma varies depending on their physicochemical properties and exposure timing. CNTs consistently exacerbate asthma, as do Ni and TiO₂ NPs, whereas some NPs like Au attenuate asthma. Evidence is strong that ENMs can contribute to allergic airway disease; however, more work is required to determine their mechanisms, and more epidemiological studies are needed to validate results from animal models.

PM2.5 induced neurodegenerative-like changes in mice and the antagonistic effects of vitamin E

Neurodegenerative diseases (ND) affect a large and ever-growing population globally, resulting in heavy burdens for patients and their families. Though some specific genes related to ND have been identified, the genetic factors fail to fully account for the pathogenesis of ND. Therefore, the roles of the environment and life styles in the occurrence of ND are being actively probed. As a typical air pollutant, exposures to PM2.5 are linked to the occurrence of ND. However, there are still few studies on this exposure, particularly on the in vivo and molecular mechanisms of the ND-like lesions after PM2.5 exposure. To investigate this link further, C57BL/6J mice were exposed everyday to PM2.5 for one week. Then, resulting brain damage and upstream events were investigated. After acute PM2.5 exposure, several ND-like changes were detected, such as cognitive deficits, loss of neurons, protein aggregates etc. Oxidative stress and inflammation may be involved with these toxic mechanisms. These effects were blocked by concurrent administration of vitamin E (Vit E). Down-regulation of oxidative stress and inflammation were proposed to explain the antagonistic effects of Vit E.

Type 2 Immune Mechanisms in Carbon Nanotube-Induced Lung Fibrosis

T helper (Th) 2-dependent type 2 immune pathways have been recognized as an important driver for the development of fibrosis. Upon stimulation, activated Th2 immune cells and type 2 cytokines interact with inflammatory and tissue repair functions to stimulate an overzealous reparative response to tissue damage, leading to organ fibrosis and destruction. In this connection, type 2 pathways are activated by a variety of insults and pathological conditions to modulate the response. Carbon nanotubes (CNTs) are nanomaterials with a wide range of applications. However, pulmonary exposure to CNTs causes a number of pathologic outcomes in animal lungs, dominated by inflammation and fibrosis. These findings, alongside the rapidly expanding production and commercialization of CNTs and CNT-containing materials in recent years, have raised concerns on the health risk of CNT exposure in humans. The CNT-induced pulmonary fibrotic lesions resemble those of human fibrotic lung diseases, such as idiopathic pulmonary fibrosis and pneumoconiosis, to a certain extent with regard to disease development and pathological features. In fibrotic scenarios, immune cells are activated including varying immune pathways, ranging from innate immune cell activation to autoimmune disease. These events often precede and/or accompany the occurrence of fibrosis. Upon CNT exposure, significant induction and activation of Th2 cells and type 2 cytokines in the lungs are observed. Moreover, type 2 pathways are shown to play important roles in promoting CNT-induced lung fibrosis by producing type 2 pro-fibrotic factors and inducing the reparative phenotypes of macrophages in response to CNTs. In light of the vastly increased demand for nanosafety and the apparent induction and multiple roles of type 2 immune pathways in lung fibrosis, we review the current literature on CNT-induced lung fibrosis, with a focus on the induction and activation of type 2 responses by CNTs and the stimulating function of type 2 signaling on pulmonary fibrosis development. These analyses provide new insights into the mechanistic understanding of CNT-induced lung fibrosis, as well as the potential of using type 2 responses as a monitoring target and therapeutic strategy for human fibrotic lung disease.

Mechanistic insight into the impact of nanomaterials on asthma and allergic airway disease

Asthma is a chronic respiratory disease known for its high susceptibility to environmental exposure. Inadvertent inhalation of engineered or incidental nanomaterials is a concern for human health, particularly for those with underlying disease susceptibility. In this review we provide a comprehensive analysis of those studies focussed on safety assessment of different nanomaterials and their unique characteristics on asthma and allergic airway disease. These include in vivo and in vitro approaches as well as human and population studies. The weight of evidence presented supports a modifying role for nanomaterial exposure on established asthma as well as the development of the condition. Due to the variability in modelling approaches, nanomaterial characterisation and endpoints used for assessment in these studies, there is insufficient information for how one may assign relative hazard potential to individual nanoscale properties. New developments including the adoption of standardised models and focussed in vitro and in silico approaches have the potential to more reliably identify properties of concern through comparative analysis across robust and select testing systems. Importantly, key to refinement and choice of the most appropriate testing systems is a more complete understanding of how these materials may influence disease at the cellular and molecular level. Detailed mechanistic insight also brings with it opportunities to build important population and exposure susceptibilities into models. Ultimately, such approaches have the potential to more clearly extrapolate relevant toxicological information, which can be used to improve nanomaterial safety assessment for human disease susceptibility.

Pretreatment with N-acetyl cysteine suppresses chronic reactive astrogliosis following maternal nanoparticle exposure during gestational period

Early pregnant employees are potentially and unintendedly exposed to industrial chemicals including nanoparticles. Developmental toxicity of nanoparticle exposure has been concerned because exposure to fine particle including carbon black nanoparticle (CB-NP) during the brain developmental stage enhances the risk of brain disorders. Maternal CB-NP exposure dose-dependently induces astrogliosis, which is an abnormal increase in the reactive astrocytes with glial fibrillary acidic protein (GFAP) and aquaporin-4 overexpression due to the destruction of nearby neurons and blood vessels. The present study aimed to investigate protective effects of antioxidants on the histopathological denaturation with astrogliosis following maternal CB-NP exposure in offspring mice, thereby to evaluate the role of oxidative stress on the developmental toxicity. Pregnant ICR mice were treated with CB-NP by intranasal instillation on gestational days 5 and 9. N-acetyl cysteine (NAC) or ascorbic acid was intraperitoneally administered to the pregnant mice 1 h prior to CB-NP instillation. The brains were collected from 6- to 12-week-old offspring mice and analyzed using western blotting and immunohistochemistry. NAC suppressed GFAP overexpression in 6- and 12-week-old offspring mice following maternal CB-NP exposure. However, NAC did not suppress aquaporin-4 overexpression following maternal CB-NP exposure. Ascorbic acid did not suppress, but rather slightly and significantly enhanced the expression of GFAP and aquaporin-4. These results indicate that astrogliosis by maternal CB-NP exposure is partially prevented by NAC pretreatment. Oxidative stress is a possible key factor of developmental neurotoxicity of maternal NP exposure. This study will contribute to elucidating the mechanisms underlying the effects of developmental neurotoxicity of NPs.

The combined effects of silicon dioxide nanoparticles and cold air exposure on the metabolism and inflammatory responses in white adipocytes

The potential hazard of nanoparticles (NPs) from air pollution has attracted widespread attention. Though the toxicology of NPs has been intensively studied, few works have been reported on the combined effect of silicon dioxide (SiO2) NPs and cold air exposure at the cellular level. Herein, we evaluated the combined effect of SiO2 NPs and cold exposure on metabolism and the inflammatory responses in white adipocytes by qRT-PCR in vitro. After SiO2 NP or cold exposure, there were significant changes in the expressions of adipogenic genes and proinflammatory cytokine genes in white adipocytes. The mRNA levels of IL-6, IL-8, TNF-α and IL-1β were upregulated by SiO2 NP or cold exposure, and more so in the combined group. The expressions of the proinflammatory cytokine genes IL-6, IL-8, TNF-α and IL-1β increased highly significantly (P < 0.01) in the SiO2 NP alone group and the combined group, compared with the control. The expressions of the cold group tended to be upregulated significantly compared with the control in IL-6 (P < 0.01) and IL-8 (P < 0.05). The results demonstrated that there was antagonistic effect between SiO2 NPs and cold air on the plasticity and metabolism in white adipocytes, where the main effect of cold air on the plasticity and metabolism was significant (P < 0.05). However, there was a synergistic effect between SiO2 NPs and cold air on the toxic effects in white adipocytes, in which the main effect of SiO2 NPs on the toxic effects was significant (P < 0.05). In conclusion, SiO2 NPs combined with cold exposure induced a stronger inflammatory response and influenced the plasticity and metabolism in white adipocytes, accompanied by more serious health hazards.

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.

Silica dioxide nanoparticles combined with cold exposure induce stronger systemic inflammatory response

Growing concern has been raised over the potential hazard of nanoparticles (NPs) on human health from ambient particulate air pollution. Silicon dioxide (SiO₂) NPs are one of the most widely used nanoparticles in many sectors of industry. Research on NPs has focused mainly on their toxicity in organs. Meanwhile, NPs are present in the air year-round, but are more serious in winter. Thus, the aim of this study was to evaluate the inflammatory response to SiO₂ NPs using in vivo test systems. The composition of particulate matter is complicated; however, elemental silicon accounts for a significant proportion. Cold exposure can induce many kinds of systemic reactions. Thus, the second aim of this study was also to evaluate the combined effect of NPs and cold exposure on human health. There is little research on the combined effects of nanoparticles and cold on inflammation. Sprague-Dawley rats were randomly divided into four groups: those exposed to SiO₂ NPs by intratracheal instillation, those exposed to at 4 °C 4 h/day for 4 weeks, a combined SiO₂ NPs and cold exposure group, and a control group. Inflammatory cell infiltration in the lungs was mainly observed after exposure to SiO₂ NPs or cold. Hematoxylin and eosin staining revealed that inflammation of the lungs was more serious in the combined group. In the white adipose tissue and brown adipose tissue of the combined groups, the mRNA expressions of pro-inflammatory cytokines were upregulated. In conclusion, SiO₂ NPs combined with cold exposure induced a stronger systemic inflammatory response, accompanied by more serious health hazards.

Intraperitoneal Injection Is Not a Suitable Administration Route for Single-Walled Carbon Nanotubes in Biomedical Applications

Given the extensive application of carbon nanotubes (CNTs) in biomedical fields, there is increasing concern regarding unintentional health impacts. Research into safe usage is therefore increasingly necessary. This study investigated the responses of the mouse brain to single-walled CNTs (SWCNTs) delivered via intraperitoneal (IP) injection and compared these results with the previous study where SWCNTs were delivered via intravenous (IV) injection so as to explore which administration route is potentially better for SWCNTs application. This study suggests SWCNTs delivered via IP injection can have negative effects on the mouse brain through oxidative stress and inflammation at high concentration exposure, but these responses were not consistent and showed no dose-dependent effect. In a previous study, the results showed that IV-delivered SWCNTs induced a more consistent and dose-dependent effect. The comparison of the 2 studies suggested that using SWCNTs at a safe dosage delivered via IV injection may be a better administration route for SWCNTs in biomedical applications.

House dust mite-induced asthma causes oxidative damage and DNA double-strand breaks in the lungs

BACKGROUND

Asthma is related to airway inflammation and oxidative stress. High levels of reactive oxygen and nitrogen species can induce cytotoxic DNA damage. Nevertheless, little is known about the possible role of allergen-induced DNA damage and DNA repair as modulators of asthma-associated pathology.

OBJECTIVE

We sought to study DNA damage and DNA damage responses induced by house dust mite (HDM) in vivo and in vitro.

METHODS

We measured DNA double-strand breaks (DSBs), DNA repair proteins, and apoptosis in an HDM-induced allergic asthma model and in lung samples from asthmatic patients. To study DNA repair, we treated mice with the DSB repair inhibitor NU7441. To study the direct DNA-damaging effect of HDM on human bronchial epithelial cells, we exposed BEAS-2B cells to HDM and measured DNA damage and reactive oxygen species levels.

RESULTS

HDM challenge increased lung levels of oxidative damage to proteins (3-nitrotyrosine), lipids (8-isoprostane), and nucleic acid (8-oxoguanine). Immunohistochemical evidence for HDM-induced DNA DSBs was revealed by increased levels of the DSB marker γ Histone 2AX (H2AX) foci in bronchial epithelium. BEAS-2B cells exposed to HDM showed enhanced DNA damage, as measured by using the comet assay and γH2AX staining. In lung tissue from human patients with asthma, we observed increased levels of DNA repair proteins and apoptosis, as shown by caspase-3 cleavage, caspase-activated DNase levels, and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling staining. Notably, NU7441 augmented DNA damage and cytokine production in the bronchial epithelium and apoptosis in the allergic airway, implicating DSBs as an underlying driver of asthma pathophysiology.

CONCLUSION

This work calls attention to reactive oxygen and nitrogen species and HDM-induced cytotoxicity and to a potential role for DNA repair as a modulator of asthma-associated pathophysiology.

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.

Diet and asthma: an update

PURPOSE OF REVIEW

Our objective was to provide an overview and discussion of recent experimental studies, epidemiologic studies, and clinical trials of diet and asthma. We focus on dietary sources and vitamins with antioxidant properties [vitamins (A, C, and E), folate, and omega-3 and omega-6 polyunsaturated fatty acids (n-3 and n-6 PUFAs)].

RECENT FINDINGS

Current evidence does not support the use of vitamin A, vitamin C, vitamin E, or PUFAs for the prevention or treatment of asthma or allergies. Current guidelines for prenatal use of folate to prevent neural tube defects should be followed, as there is no evidence of major effects of this practice on asthma or allergies. Consumption of a balanced diet that is rich in sources of antioxidants (e.g. fruits and vegetables) may be beneficial in the primary prevention of asthma.

SUMMARY

None of the vitamins or nutrients examined is consistently associated with asthma or allergies. In some cases, further studies of the effects of a vitamin or nutrient on specific asthma phenotypes (e.g. vitamin C to prevent viral-induced exacerbations) are warranted. Clinical trials of 'whole diet' interventions to prevent asthma are advisable on the basis of existing evidence.

Effects of engineered nanomaterials on plants growth: an overview

Rapid development and wide applications of nanotechnology brought about a significant increment on the number of engineered nanomaterials (ENs) inevitably entering our living system. Plants comprise of a very important living component of the terrestrial ecosystem. Studies on the influence of engineered nanomaterials (carbon and metal/metal oxides based) on plant growth indicated that in the excess content, engineered nanomaterials influences seed germination. It assessed the shoot-to-root ratio and the growth of the seedlings. From the toxicological studies to date, certain types of engineered nanomaterials can be toxic once they are not bound to a substrate or if they are freely circulating in living systems. It is assumed that the different types of engineered nanomaterials affect the different routes, behavior, and the capability of the plants. Furthermore, different, or even opposing conclusions, have been drawn from most studies on the interactions between engineered nanomaterials with plants. Therefore, this paper comprehensively reviews the studies on the different types of engineered nanomaterials and their interactions with different plant species, including the phytotoxicity, uptakes, and translocation of engineered nanomaterials by the plant at the whole plant and cellular level.

Autophagy as a Possible Underlying Mechanism of Nanomaterial Toxicity

The rapid development of nanotechnologies is raising safety concerns because of the potential effects of engineered nanomaterials on human health, particularly at the respiratory level. Since the last decades, many in vivo studies have been interested in the pulmonary effects of different classes of nanomaterials. It has been shown that some of them can induce toxic effects, essentially depending on their physico-chemical characteristics, but other studies did not identify such effects. Inflammation and oxidative stress are currently the two main mechanisms described to explain the observed toxicity. However, the exact underlying mechanism(s) still remain(s) unknown and autophagy could represent an interesting candidate. Autophagy is a physiological process in which cytoplasmic components are digested via a lysosomal pathway. It has been shown that autophagy is involved in the pathogenesis and the progression of human diseases, and is able to modulate the oxidative stress and pro-inflammatory responses. A growing amount of literature suggests that a link between nanomaterial toxicity and autophagy impairment could exist. In this review, we will first summarize what is known about the respiratory effects of nanomaterials and we will then discuss the possible involvement of autophagy in this toxicity. This review should help understand why autophagy impairment could be taken as a promising candidate to fully understand nanomaterials toxicity.

Potential Occupational Risks Associated with Pulmonary Toxicity of Carbon Nanotubes

Given their remarkable properties, carbon nanotubes (CNTs) have made their way through various industrial and medicinal applications and the overall production of CNTs is expected to grow rapidly in the next few years, thus requiring an additional recruitment of workers. However, their unique applications and desirable properties are fraught with concerns regarding occupational exposure. The concern about worker exposure to CNTs arises from the results of recent animal studies. Short-term and sub-chronic exposure studies in rodents have shown consistent adverse health effects such as pulmonary inflammation, granulomas, fibrosis, genotoxicity and mesothelioma after inhalation or instillation of several types of CNTs. Furthermore, physicochemical properties of CNTs such as dispersion, functionalization and particle size can significantly affect their pulmonary toxicity. Risk estimates from animal studies necessitate implementation of protective measures to limit worker exposure to CNTs. Information on workplace exposure is very limited, however, studies have reported that CNTs can be aerosolized and attain respirable airborne levels during synthesis and processing activities in the workplace. Quantitative risk assessments from sub-chronic animal studies recommend the health-based need to reduce exposures below the recommended exposure limit of 1 µg/m³. Practice of prevention measures including the use of engineering controls, personal protective equipment, health surveillance program, safe handling and use, as well as worker training can significantly minimize worker exposure and improve worker health and safety.