Dose-dependent induction of astrocyte activation and reactive astrogliosis in mouse brain following maternal exposure to carbon black nanoparticle

Nanoparticles toxicity: an overview of its mechanism and plausible mitigation strategies

Over the last decade, nanoparticles have found great interest among scientists and researchers working in various fields within the realm of biomedicine including drug delivery, gene delivery, diagnostics, targeted therapy and biomarker mapping. While their physical and chemical properties are impressive, there is growing concern about the toxicological potential of nanoparticles and possible adverse health effects as enhanced exposure of biological systems to nanoparticles may result in toxic effects leading to serious contraindications. Toxicity associated with nanoparticles (nanotoxicity) may include the undesired response of several physiological mechanisms including the distressing of cells by external and internal interaction with nanoparticles. However, comprehensive knowledge of nanotoxicity mechanisms and mitigation strategies may be useful to overcome the hazardous situation while treating diseases with therapeutic nanoparticles. With the same objectives, this review discusses various mechanisms of nanotoxicity and provides an overview of the current state of knowledge on the impact of nanotoxicity on biological control systems and organs including liver, brain, kidneys and lungs. An attempt also been made to present various approaches of scientific research and strategies that could be useful to overcome the effect of nanotoxicity during the development of nanoparticle-based systems including coating, doping, grafting, ligation and addition of antioxidants.

Nicotine suppresses crystalline silica-induced astrocyte activation and neuronal death by inhibiting NF-κB in the mouse hippocampus

AIMS

Exposure to crystalline silica (CS) in occupational settings induces chronic inflammation in the respiratory system and, potentially, the brain. Some workers are frequently concurrently exposed to both CS and nicotine. Here, we explored the impact of nicotine on CS-induced neuroinflammation in the mouse hippocampus.

METHODS

In this study, we established double-exposed models of CS and nicotine in C57BL/6 mice. To assess depression-like behavior, experiments were conducted at 3, 6, and 9 weeks. Serum inflammatory factors were analyzed by ELISA. Hippocampus was collected for RNA sequencing analysis and examining the gene expression patterns linked to inflammation and cell death. Microglia and astrocyte activation and hippocampal neuronal death were assessed using immunohistochemistry and immunofluorescence staining. Western blotting was used to analyze the NF-κB expression level.

RESULTS

Mice exposed to CS for 3 weeks showed signs of depression. This was accompanied by elevated IL-6 in blood, destruction of the blood-brain barrier, and activation of astrocytes caused by an increased NF-κB expression in the CA1 area of the hippocampus. The elevated levels of astrocyte-derived Lcn2 and upregulated genes related to inflammation led to higher neuronal mortality. Moreover, nicotine mitigated the NF-κB expression, astrocyte activation, and neuronal death, thereby ameliorating the associated symptoms.

CONCLUSION

Silica exposure induces neuroinflammation and neuronal death in the mouse hippocampal CA1 region and depressive behavior. However, nicotine inhibits CS-induced neuroinflammation and neuronal apoptosis, alleviating depressive-like behaviors in mice.

Effects of fine particulate matter on bone marrow-conserved hematopoietic and mesenchymal stem cells: a systematic review

The harmful effects of fine particulate matter ≤2.5 µm in size (PM2.5) on human health have received considerable attention. However, while the impact of PM2.5 on the respiratory and cardiovascular systems has been well studied, less is known about the effects on stem cells in the bone marrow (BM). With an emphasis on the invasive characteristics of PM2.5, this review examines the current knowledge of the health effects of PM2.5 exposure on BM-residing stem cells. Recent studies have shown that PM2.5 enters the circulation and then travels to distant organs, including the BM, to induce oxidative stress, systemic inflammation and epigenetic changes, resulting in the reduction of BM-residing stem cell survival and function. Understanding the broader health effects of air pollution thus requires an understanding of the invasive characteristics of PM2.5 and its direct influence on stem cells in the BM. As noted in this review, further studies are needed to elucidate the underlying processes by which PM2.5 disturbs the BM microenvironment and inhibits stem cell functionality. Strategies to prevent or ameliorate the negative effects of PM2.5 exposure on BM-residing stem cells and to maintain the regenerative capacity of those cells must also be investigated. By focusing on the complex relationship between PM2.5 and BM-resident stem cells, this review highlights the importance of specific measures directed at safeguarding human health in the face of rising air pollution.

US air pollution is associated with increased incidence of non-syndromic cleft lip/palate

Maternal cigarette use is associated with the fetal development of orofacial clefts. Air pollution should be investigated for similar causation. We hypothesize that the incidence of non-syndromic cleft lip with or without palate (NSCLP) and non-syndromic cleft palate (NSCP) would be positively correlated with air pollution concentration.

METHODS

The incidence of NSCLP and NSCP per 1000 live births from 2016 to 2020 was extracted from the Centers for Disease Control and Prevention Vital Statistics Database and merged with national reports on air pollution using the Environmental Protection Agency Air Quality Systems annual data. The most commonly reported pollutants were analyzed including benzene, sulfur dioxide (SO2), particulate matter (PM) 2.5, PM 10, ozone (O3), and carbon monoxide (CO). Multivariable negative binomial and Poisson log-linear regression models evaluated the incidence of NSCLP and NSCP as a function of the pollutants, adjusting for race. All p-values are reported with Bonferroni correction.

RESULTS

The median NSCLP incidence was 0.22/1000 births, and isolated NSCP incidence was 0.18/1000 births. For NSCLP, SO2 had a coefficient estimate (CE) of 0.60 (95% CI [0.23, 0.98], p < 0.007) and PM 2.5 had a CE of 0.20 (95% CI [0.10, 0.31], p < 0.005). Among isolated NSCP, no pollutants were found to be significantly associated.

CONCLUSION

SO2 and PM 2.5 were significantly correlated with increased incidence of NSCLP. The American people and perinatal practitioners should be aware of the connection to allow for risk reduction and in utero screening.

Longitudinal effects of environmental noise and air pollution exposure on autism spectrum disorder and attention-deficit/hyperactivity disorder during adolescence and early adulthood: The TRAILS study

BACKGROUND

Exposure to ambient noise and air pollution may affect the manifestation and severity of Autism Spectrum Disorder (ASD) and Attention-Deficit/Hyperactivity Disorder (ADHD). However, evidence is limited, and most studies solely assessed environmental exposures during pregnancy and early childhood.

OBJECTIVE

To examine the longitudinal effects of ambient noise and air pollutants on ASD and ADHD symptom severity during adolescence and early adulthood.

METHODS

Using a longitudinal design, we included 2750 children between 10 and 12 years old from the TRacking Adolescents' Individual Lives Survey (TRAILS) in the Netherlands, who were assessed in 6 waves from 2001 to 2017. ASD was measured by the Children's Social Behavior Questionnaire and the Adult Social Behavior Questionnaire. ADHD was measured by Child Behavior Checklist and the Adult Behavior Checklist. Ambient noise and air pollution exposures, including Ozone (O₃), soot, sulfur dioxide (SO₂), nitrogen dioxide (NO₂), particulate matter 2.5 (PM_2.5), and PM₁₀ were modeled at the residential level according to standardized protocols. The longitudinal associations between exposures and symptom outcomes were examined using linear mixed models.

RESULTS

We found evidence that higher levels of exposure to PM were associated with more severe ASD and ADHD symptoms. This association decreased over time. We did not observe any other consistent associations of noise or other air pollutants with ASD and ADHD severity.

CONCLUSION

The current study provides evidence for the negative impact of PM on ASD and ADHD symptoms. We did not find evidence of the negative health impact of other air pollutants and noise exposures on ASD or ADHD symptoms. Our study adds more evidence on the presence of associations between PM air pollution and neurodevelopmental diseases among adolescents and young adults.

Particulate matter and ultrafine particles in urban air pollution and their effect on the nervous system

According to the World Health Organization, both indoor and urban air pollution are responsible for the deaths of around 3.5 million people annually. During the last few decades, the interest in understanding the composition and health consequences of the complex mixture of polluted air has steadily increased. Today, after decades of detailed research, it is well-recognized that polluted air is a complex mixture containing not only gases (CO, NO_x, and SO₂) and volatile organic compounds but also suspended particles such as particulate matter (PM). PM comprises particles with sizes in the range of 30 to 2.5 μm (PM₃₀, PM₁₀, and PM_2.5) and ultrafine particles (UFPs) (less than 0.1 μm, including nanoparticles). All these constituents have different chemical compositions, origins and health consequences. It has been observed that the concentration of PM and UFPs is high in urban areas with moderate traffic and increases in heavy traffic areas. There is evidence that inhaling PM derived from fossil fuel combustion is associated with a wide variety of harmful effects on human health, which are not solely associated with the respiratory system. There is accumulating evidence that the brains of urban inhabitants contain high concentrations of nanoparticles derived from combustion and there is both epidemiological and experimental evidence that this is correlated with the appearance of neurodegenerative human diseases. Neurological disorders, such as Alzheimer's and Parkinson's disease, multiple sclerosis, and cerebrovascular accidents, are among the main debilitating disorders of our time and their epidemiology can be classified as a public health emergency. Therefore, it is crucial to understand the pathophysiology and molecular mechanisms related to PM exposure, specifically to UFPs, present as pollutants in air, as well as their correlation with the development of neurodegenerative diseases. Furthermore, PM can enhance the transmission of airborne diseases and trigger inflammatory and immune responses, increasing the risk of health complications and mortality. Therefore, understanding the different levels of this issue is important to create and promote preventive actions by both the government and civilians to construct a strategic plan to treat and cope with the current and future epidemic of these types of disorders on a global scale.

Carbonaceous Nanoparticle Air Pollution: Toxicity and Detection in Biological Samples

Among the different air pollutants, particulate matter (PM) is of great concern due to its abundant presence in the atmosphere, which results in adverse effects on the environment and human health. The different components of PM can be classified based on their physicochemical properties. Carbonaceous particles (CPs) constitute a major fraction of ultrafine PM and have the most harmful effects. Herein, we present a detailed overview of the main components of CPs, e.g., carbon black (CB), black carbon (BC), and brown carbon (BrC), from natural and anthropogenic sources. The emission sources and the adverse effects of CPs on the environment and human health are discussed. Particularly, we provide a detailed overview of the reported toxic effects of CPs in the human body, such as respiratory effects, cardiovascular effects, neurodegenerative effects, carcinogenic effects, etc. In addition, we also discuss the challenges faced by and limitations of the available analytical techniques for the qualitative and quantitative detection of CPs in atmospheric and biological samples. Considering the heterogeneous nature of CPs and biological samples, a detailed overview of different analytical techniques for the detection of CPs in (real-exposure) biological samples is also provided. This review provides useful insights into the classification, toxicity, and detection of CPs in biological samples.

Indirect mediators of systemic health outcomes following nanoparticle inhalation exposure

The growing field of nanoscience has shed light on the wide diversity of natural and anthropogenic sources of nano-scale particulates, raising concern as to their impacts on human health. Inhalation is the most robust route of entry, with nanoparticles (NPs) evading mucociliary clearance and depositing deep into the alveolar region. Yet, impacts from inhaled NPs are evident far outside the lung, particularly on the cardiovascular system and highly vascularized organs like the brain. Peripheral effects are partly explained by the translocation of some NPs from the lung into the circulation; however, other NPs largely confined to the lung are still accompanied by systemic outcomes. Omic research has only just begun to inform on the complex myriad of molecules released from the lung to the blood as byproducts of pulmonary pathology. These indirect mediators are diverse in their molecular make-up and activity in the periphery. The present review examines systemic outcomes attributed to pulmonary NP exposure and what is known about indirect pathological mediators released from the lung into the circulation. Further focus was directed to outcomes in the brain, a highly vascularized region susceptible to acute and longer-term outcomes. Findings here support the need for big-data toxicological studies to understand what drives these health outcomes and better predict, circumvent, and treat the potential health impacts arising from NP exposure scenarios.

In-utero exposure to air pollution and early-life neural development and cognition

Air pollution remains one of the major health threats around the world. Compared to adults, foetuses and infants are more vulnerable to the effects of environmental toxins. Maternal exposure to air pollution causes several adverse birth outcomes and may lead to life-long health consequences. Given that a healthy intrauterine environment is a critical factor for supporting normal foetal brain development, there is a need to understand how prenatal exposure to air pollution affects brain health and results in neurological dysfunction. This review summarised the current knowledge on the adverse effects of prenatal air pollution exposure on early life neurodevelopment and subsequent impairment of cognition and behaviour in childhood, as well as the potential of early-onset neurodegeneration. While inflammation, oxidative stress, and endoplasmic reticulum are closely involved in the physiological response, sex differences also occur. In general, males are more susceptible than females to the adverse effect of in-utero air pollution exposure. Considering the evidence provided in this review and the rising concerns of global air pollution, any efforts to reduce pollutant emission or exposure will be protective for the next generation.

A Novel Staining Method for Detection of Brain Perivascular Injuries Induced by Nanoparticle: Periodic Acid-Schiff and Immunohistochemical Double-Staining

Background: To protect developing brain from any unfavorable effects, it is necessary to construct experimental techniques that can sensitively detect and evaluate developmental toxicity. We have previously shown that brain perivascular tissues, especially perivascular macrophages (PVMs), respond sensitively even to weak stimuli by foreign toxicants such as low-dose exposure to nanoparticle. This paper shows the protocol of a novel staining method that enables easy detection and rapid evaluation of brain perivascular abnormalities.

Methods: As weak stimulus, low-dose of carbon black nanoparticle (95 μg/kg) or titanium dioxide nanoparticle (100 μg/kg) was intranasally administered to pregnant mice at gestational days 5 and 9. The offspring brains were used to confirm the properties of PVMs and to find suitable protocols for the detection and evaluation of the mild denaturation of PVMs. Furthermore, various procedures of novel combinational double staining including periodic acid-Schiff (PAS) staining and immunohistochemistry were examined. In addition, we checked the alterations in neurotransmitter levels and the behaviors of the offspring.

Results and discussion: Maternal exposure to low-dose of nanoparticle at levels where no significant effects on the brain were observed, such as abnormal behavior, alteration of neurotransmitter levels, or microglial activation, resulted in mild denaturation of the PVMs, which was captured by PAS staining. However, it was difficult to detect and determine slight histopathological alterations. Therefore, we established PAS-immunohistochemical double-staining method for the brain. This double staining method enabled easy detection and rapid evaluation of brain perivascular abnormalities and the relationship between PVMs and the surrounding cells. In addition, this double staining allows evaluation of the histopathological denaturation of the PVMs and the associated abnormalities in the surrounding tissues in the same section.

Conclusion: The slight responses of brain perivascular tissues, such as mild denaturation of PVMs, were sensitively and easily determined by the PAS-immunohistochemical double-staining method. This double staining method is a powerful tool to assess brain perivascular injuries including PVM denaturation and the relationship between the expression of various molecules and the morphology of PVMs. We propose that the observation of the tissue around brain blood vessels using the double staining provides potential endpoints to evaluate developmental neurotoxicity.

Potential of NRF2 Pathway in Preventing Developmental and Reproductive Toxicity of Fine Particles

Air pollution is associated with significant adverse health effects. Recent studies support the idea that inhalation of fine particles can instigate extrapulmonary effects on the cardiovascular system through several pathways. The systemic transfer of ultrafine particles (UFPs) or soluble particle components (organic compounds and metals) is of particular concern. An integral role of reactive oxygen species (ROS)-dependent pathways has been suggested in systemic inflammatory responses and vascular dysfunction at the molecular level. Accumulating lines of evidence suggest that fine particles affect fetal development, giving rise to low birth weight and a reduction in fetal growth, and also affect the immune, cardiovascular, and central nervous systems. Oxidative stress plays an important role in fine particles toxicity; pre-treatment with antioxidants partially suppresses the developmental toxicity of fine particles. On the other hand, Nuclear factor erythroid-derived 2-like 2 (Nfe2l2), also known as NRF2, is a transcription factor essential for inducible and/or constitutive expression of phase II and antioxidant enzymes. Studies using Nrf2-knockout mice revealed that NRF2 dysfunction is intimately involved in the pathogenesis of various human diseases. Multiple single nucleotide polymorphisms (SNPs) have been detected in human NRF2 locus. An NRF2 gene SNP (−617C > A; rs6721961), located in the upstream promoter region, affects the transcriptional level of NRF2 and thereby the protein level and downstream gene expression. It has been reported that the SNP-617 is associated with various diseases. The onset and exacerbation of the diseases are regulated by genetic predisposition and environmental factors; some people live in the air-polluted environment but are not affected and remain healthy, suggesting the presence of individual differences in the susceptibility to air pollutants. NRF2 polymorphisms may also be associated with the fetal effects of fine particles exposure. Screening high-risk pregnant women genetically susceptible to oxidative stress and prevention by antioxidant interventions to protect fetal development in air-polluted areas should be considered. This article reviews the recent advances in our understanding of the fetal health effects of fine particles and describes potential chemoprevention via the NRF2 pathway to prevent the developmental and reproductive toxicity of fine particles.

Modelling of Stem Cells Microenvironment Using Carbon-Based Scaffold for Tissue Engineering Application-A Review

A scaffold is a crucial biological substitute designed to aid the treatment of damaged tissue caused by trauma and disease. Various scaffolds are developed with different materials, known as biomaterials, and have shown to be a potential tool to facilitate in vitro cell growth, proliferation, and differentiation. Among the materials studied, carbon materials are potential biomaterials that can be used to develop scaffolds for cell growth. Recently, many researchers have attempted to build a scaffold following the origin of the tissue cell by mimicking the pattern of their extracellular matrix (ECM). In addition, extensive studies were performed on the various parameters that could influence cell behaviour. Previous studies have shown that various factors should be considered in scaffold production, including the porosity, pore size, topography, mechanical properties, wettability, and electroconductivity, which are essential in facilitating cellular response on the scaffold. These interferential factors will help determine the appropriate architecture of the carbon-based scaffold, influencing stem cell (SC) response. Hence, this paper reviews the potential of carbon as a biomaterial for scaffold development. This paper also discusses several crucial factors that can influence the feasibility of the carbon-based scaffold architecture in supporting the efficacy and viability of SCs.

Neurovascular Alterations in Vascular Dementia: Emphasis on Risk Factors

Vascular dementia (VaD) constitutes the second most prevalent cause of dementia in the world after Alzheimer’s disease (AD). VaD regroups heterogeneous neurological conditions in which the decline of cognitive functions, including executive functions, is associated with structural and functional alterations in the cerebral vasculature. Among these cerebrovascular disorders, major stroke, and cerebral small vessel disease (cSVD) constitute the major risk factors for VaD. These conditions alter neurovascular functions leading to blood-brain barrier (BBB) deregulation, neurovascular coupling dysfunction, and inflammation. Accumulation of neurovascular impairments over time underlies the cognitive function decline associated with VaD. Furthermore, several vascular risk factors, such as hypertension, obesity, and diabetes have been shown to exacerbate neurovascular impairments and thus increase VaD prevalence. Importantly, air pollution constitutes an underestimated risk factor that triggers vascular dysfunction via inflammation and oxidative stress. The review summarizes the current knowledge related to the pathological mechanisms linking neurovascular impairments associated with stroke, cSVD, and vascular risk factors with a particular emphasis on air pollution, to VaD etiology and progression. Furthermore, the review discusses the major challenges to fully elucidate the pathobiology of VaD, as well as research directions to outline new therapeutic interventions.

Air pollution and children's health-a review of adverse effects associated with prenatal exposure from fine to ultrafine particulate matter

BACKGROUND

Particulate matter (PM), a major component of ambient air pollution, accounts for a substantial burden of diseases and fatality worldwide. Maternal exposure to PM during pregnancy is particularly harmful to children's health since this is a phase of rapid human growth and development.

METHOD

In this review, we synthesize the scientific evidence on adverse health outcomes in children following prenatal exposure to the smallest toxic components, fine (PM_2.5) and ultrafine (PM_0.1) PM. We highlight the established and emerging findings from epidemiologic studies and experimental models.

RESULTS

Maternal exposure to fine and ultrafine PM directly and indirectly yields numerous adverse birth outcomes and impacts on children's respiratory systems, immune status, brain development, and cardiometabolic health. The biological mechanisms underlying adverse effects include direct placental translocation of ultrafine particles, placental and systemic maternal oxidative stress and inflammation elicited by both fine and ultrafine PM, epigenetic changes, and potential endocrine effects that influence long-term health.

CONCLUSION

Policies to reduce maternal exposure and health consequences in children should be a high priority. PM_2.5 levels are regulated, yet it is recognized that minority and low socioeconomic status groups experience disproportionate exposures. Moreover, PM_0.1 levels are not routinely measured or currently regulated. Consequently, preventive strategies that inform neighborhood/regional planning and clinical/nutritional recommendations are needed to mitigate maternal exposure and ultimately protect children's health.

The Association between Preterm Birth and Ambient Air Pollution Exposure in Shiyan, China, 2015-2017

Shortening of the gestational duration has been found associated with ambient air pollution exposure. However, the critical exposure windows of ambient air pollution for gestational duration remain inconsistent, and the association between ambient air pollution and early term births (ETB, 37 to 38 weeks) has rarely been studied relative to preterm births (PTB, 28–37 weeks). A time-series study was conducted in Shiyan, a medium-sized city in China. Birth information was collected from the Shiyan Maternity and Child Health Hospital, and 13,111 pregnant women who gave birth between 2015 and 2017 were included. Data of the concentrations of air pollutants, including PM₁₀, PM_2.5, NO₂, and SO₂ and meteorological data, were collected in the corresponding gestational period. The Cox regression analysis was performed to estimate the relationship between ambient air pollution exposure and the risk of preterm birth after controlling the confounders, including maternal age, education, Gravidity, parity, fetal gender, and delivery mode. Very preterm birth (VPTB, 28–32 weeks) as a subtype of PTB was also incorporated in this study. The risk of VPTB and ETB was positively associated with maternal ambient air pollution exposure, and the correlation of gaseous pollutants was stronger than particulate matter. With respect to exposure windows, the critical trimester of air pollutants for different adverse pregnancy outcomes was different. The exposure windows of PM₁₀, PM_2.5, and SO₂ for ETB were found in the third trimester, with HRs (hazard ratios) of 1.06 (95%CI: 1.04, 1.09), 1.07 (95%CI: 1.04, 1.11), and 1.28 (95%CI: 1.20, 1.35), respectively. However, for NO₂, the second and third trimesters exhibited similar results, the HRs reaching 1.10 (95%CI: 1.03, 6.17) and 1.09 (95%CI: 1.03,1.15), respectively. This study extends and strengthen the evidence for a significant correlation between the ambient air pollution exposure during pregnancy and the risk of not only PTB but, also, ETB. Moreover, our findings suggest that the exposure windows during pregnancy vary with different air pollutants and pregnancy outcomes.

Airborne fine particulate matter induces cognitive and emotional disorders in offspring mice exposed during pregnancy

Gestational exposure to PM_2.5 is associated with adverse postnatal outcomes. PM_2.5 can enter alveoli by using intratracheal instillation, even penetrate through lung cells into the blood circulation. Subsequently, they are transferred across the placenta and fetal blood brain barrier, causing the adverse birth outcomes of offspring. This study demonstrated that the gestational exposure resulted in cognitive and emotional disorders in female offspring although the offspring were not exposed to PM_2.5. Placental metabolic pathways modulated fetal brain development and played a pivotal role for maternal-placental-fetal interactions in the fetal programming of adult behavioral and mental disorders. Samples of fetus, offspring hippocampus and placenta from the mice exposed to PM_2.5 were investigated using a comprehensive approach including mass spectrometry-based lipidomics and three-dimensional imaging. The exposure induced the neuro-degeneration in hippocampus, impairment of placental cytoarchitecture, and reprogramming of lipidome, which might affect the modulation of maternal-fetal cross-talk and result in the behavior disorders of offspring. The variation of spatial distribution of lipids was profoundly affected in dorsal pallium and hippocampal formation regions of fetal brain, offspring hippocampus, as well as labyrinth and junctional zones of placenta. The abundance alteration of lipid markers associated with neurodegenerative diseases was validated in transgenic mouse model with Alzheimer's disease and human cerebrospinal fluid from patients with Parkinson's disease. The finding could help with the selection of more suitable heterogeneous-related substructures targeting PM_2.5 exposure and the exploration of PM_2.5-induced toxicological effects on neurodegenerative diseases.

Fetotoxicity of Nanoparticles: Causes and Mechanisms

The application of nanoparticles in consumer products and nanomedicines has increased dramatically in the last decade. Concerns for the nano-safety of susceptible populations are growing. Due to the small size, nanoparticles have the potential to cross the placental barrier and cause toxicity in the fetus. This review aims to identify factors associated with nanoparticle-induced fetotoxicity and the mechanisms involved, providing a better understanding of nanotoxicity at the maternal–fetal interface. The contribution of the physicochemical properties of nanoparticles (NPs), maternal physiological, and pathological conditions to the fetotoxicity is highlighted. The underlying molecular mechanisms, including oxidative stress, DNA damage, apoptosis, and autophagy are summarized. Finally, perspectives and challenges related to nanoparticle-induced fetotoxicity are also discussed.

Astrocyte responses to nanomaterials: Functional changes, pathological changes and potential applications

Astrocytes are responsible for regulating and optimizing the functional environment of neurons in the brain and can reduce the adverse impacts of external factors by protecting neurons. However, excessive astrocyte activation upon stimulation may alter their initial protective effect and actually lead to aggravation of injury. Similar to the dual effects of astrocytes in the response to injury within the central nervous system (CNS), nanomaterials (NMs) can have either toxic or beneficial effects on astrocytes, serving to promote injury or inhibit tumors. As the important physiological functions of astrocytes have been gradually revealed, the effects of NMs on astrocytes and the underlying mechanisms have become a new frontier in nanomedicine and neuroscience. This review summarizes the in vitro and in vivo findings regarding the effects of various NMs on astrocytes, focusing on functional alterations and pathological processes in astrocytes, as well as the possible underlying mechanisms. We also emphasize the importance of co-culture models in studying the interaction between NMs and cells of the CNS. Finally, we discuss NMs that have shown promise for application in astrocyte-related diseases and propose some challenges and suggestions for further investigations, with the aim of providing guidance for the widespread application of NMs in the CNS.

The Impact of Particulate Matter (PM2.5) on Human Retinal Development in hESC-Derived Retinal Organoids

Increasing evidence demonstrated that PM2.5 could cross the placenta and fetal blood-brain barrier, causing neurotoxicity of embryonic development. The retina, an embryologic extension of the central nervous system, is extremely sensitive and vulnerable to environmental insults. The adverse effects of PM2.5 exposure on the retina during embryonic neurodevelopment are still largely unknown. Our goal was to investigate the effect of PM2.5 on human retinal development, which was recapitulated by human embryonic stem cell (hESC)-derived retinal organoids (hEROs). In the present study, using the hEROs as the model, the influences and the mechanisms of PM2.5 on the developing retina were analyzed. It demonstrated that the formation rate of the hERO-derived neural retina (NR) was affected by PM2.5 in a concentration dosage-dependent manner. The areas of hEROs and the thickness of hERO-NRs were significantly reduced after PM2.5 exposure at the concentration of 25, 50, and 100 μg/ml, which was due to the decrease of proliferation and the increase of apoptosis. Although we did not spot significant effects on retinal differentiation, PM2.5 exposure did lead to hERO-NR cell disarranging and structural disorder, especially retinal ganglion cell dislocation. Transcriptome analysis showed that PM2.5 treatment was significantly associated with the mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K)/AKT pathways and reduced the level of the fibroblast growth factors (FGFs), particularly FGF8 and FGF10. These results provided evidence that PM2.5 exposure potentially inhibited proliferation and increased apoptosis at the early development stage of the human NR, probably through the MAPK and PI3K/Akt pathway. Our study suggested that exposure to PM2.5 suppressed cell proliferation and promoted cell apoptosis, thereby contributing to abnormal human retinal development.

Maternal PM2.5 exposure and abnormal placental nutrient transport

Epidemiological studies of human and animal experiments indicated that gestational exposure to atmospheric pollutants could be followed by the abnormal placental development. However, the effects of this exposure on the placental transportation for nutrients have not been systematically investigated. In this study, fine particulate matters (PM_2.5) samples were collected in Taiyuan and pregnant rodent models were administered with 3 mg/kg b.w. PM_2.5 by oropharyngeal aspiration every other day starting on embryonic day 0.5 (E0.5). Then the pregnant mice were sacrificed and their placentas were collected at different time points. The results showed that maternal PM_2.5 exposure (MPE) disrupted the expression of proliferating cell nuclear antigen (PCNA) at all time points and inhibited the cell proliferation in placenta. Following that, the capacity for placental nutrient transport was impaired. The changes at E18.5 were observed most significantly, showing the altered mRNA expression of amino acid, long-chain polyunsaturated fatty acid (LCPUFA), glucose and folate transporters. In addition, the glycogen content was elevated at E18.5, and the triglyceride content was increased at E13.5 and E15.5 and decreased at E18.5 in the placenta after MPE. In a word, the adverse effect induced by MPE revealed that MPE led tothe disruption on the nutrient supply to the developing fetus via modulating the abundance of placental nutrient transporters (PNT).

Carbon nanoparticles induce endoplasmic reticulum stress around blood vessels with accumulation of misfolded proteins in the developing brain of offspring

Nano-particulate air pollution threatens developing brains and is epidemiologically related to neurodegenerative diseases involving deposition of misfolded proteins. However, the mechanism underlying developmental neurotoxicity by nanoparticles remains unknown. Here, we report that maternal exposure to low doses of carbon black nanoparticle (CB-NP) induces endoplasmic reticulum (ER) stress associated with accumulation of misfolded proteins. Notably, offspring specifically showed high induction of ER stress in perivascular macrophages and reactive astrocytes only around brain blood vessels, along with accumulation of β-sheet-rich proteins regarded as misfolded proteins. Our results suggest that maternal CB-NP exposure induced ER stress in PVMs and reactive astrocytes around blood vessels in the brain of offspring in mice. The induction of ER stress accompanied by the perivascular accumulation of misfolded proteins is likely to be associated with perivascular abnormalities and neurodegeneration, and development of neurodegenerative diseases related to particulate air pollution.

Oxidative stress induced by ultrafine carbon black particles can elicit apoptosis in vivo and vitro

Although carbon black (CB) particles have potential hazards to human health, the toxicological studies on CB are still limited. The purpose of this study was to investigate the effect of oxidative stress induced by ultrafine CB particles on apoptosis in vivo and vitro. Male C57BL/6 mice were inhalation exposed to CB for 28 days, and 16HBE cells were treated by CB particles and also added antioxidant (NAC). Antioxidant enzymes activities (CAT, SOD, GSH-Px) and ROS in the lungs and cells were evaluated. Apoptosis-related proteins (Bcl-2, Bax, Cleaved Caspase-3, pro-Caspase-3, Caspase-7, Caspase-8, Caspase-9, PARP-1) were tested by Western blot (WB), immunohistochemistry (IHC), and real-time PCR. The reduction of antioxidant enzymes activities and the addition of ROS in CB exposure groups were observed, and the gene and apoptosis-related proteins levels were increased in CB exposure mice. The results of CB-treated 16HBE cells were consistent with those of mice, and apoptosis rate was increased in CB-treated 16HBE cells. When the cells were treated with NAC, ROS induced by CB decreased, SOD and CAT activities of CB-treated 16HBE cells were increased. Apoptosis rate of 16HBE cells treated with NAC and CB was significantly decreased, and the expression of C-Caspase-3 was also decreased. Therefore, oxidative stress induced by ultrafine CB particles can elicit apoptosis in vivo and vitro. Antioxidants can significantly reduce oxidative damage and apoptosis induced by CB.

The health effects of ultrafine particles

Ultrafine particles (PM_0.1), which are present in the air in large numbers, pose a health risk. They generally enter the body through the lungs but translocate to essentially all organs. Compared to fine particles (PM_2.5), they cause more pulmonary inflammation and are retained longer in the lung. Their toxicity is increased with smaller size, larger surface area, adsorbed surface material, and the physical characteristics of the particles. Exposure to PM_0.1 induces cough and worsens asthma. Metal fume fever is a systemic disease of lung inflammation most likely caused by PM_0.1. The disease is manifested by systemic symptoms hours after exposure to metal fumes, usually through welding. PM_0.1 cause systemic inflammation, endothelial dysfunction, and coagulation changes that predispose individuals to ischemic cardiovascular disease and hypertension. PM_0.1 are also linked to diabetes and cancer. PM_0.1 can travel up the olfactory nerves to the brain and cause cerebral and autonomic dysfunction. Moreover, in utero exposure increases the risk of low birthweight. Although exposure is commonly attributed to traffic exhaust, monitored students in Ghana showed the highest exposures in a home near a trash burning site, in a bedroom with burning coils employed to abate mosquitos, in a home of an adult smoker, and in home kitchens during domestic cooking. The high point-source production and rapid redistribution make incidental exposure common, confound general population studies and are compounded by the lack of global standards and national reporting. The potential for PM_0.1 to cause harm to health is great, but their precise role in many illnesses is still unknown and calls for more research.

Tiny particles found in air pollution enter the body usually through the lungs and disperse to other organs, causing more inflammation and cellular toxicity than larger particles. Dean Schraufnagel from the University of Illinois at Chicago, USA, reviews the way by which nano-sized air pollutants threaten human health. He describes how ultrafine particles measuring less than 100 nanometres in diameter elicit greater inflammatory responses and stay in the lungs longer than larger particles. Repeated contact with extremely small particulate matter can trigger heart disease, diabetes, cancer, neurological disorders and respiratory ailments, especially among children and people with long-term occupational exposure. Much remains to be learned about the disease-causing properties of these nanoparticles and their long-term effects. Further developments in understanding remain handicapped by the lack of international standards and reporting measures.

Exposure to carbon black nanoparticles increases seizure susceptibility in male mice

Carbon black nanoparticles (CBNPs) can enter the central nervous system through blood circulation and olfactory nerves, affecting brain development or increasing neurological disease susceptibility. However, whether CBNPs exposure affects seizure is unclear. Herein, mice were exposed to two different doses of CBNPs (21 and 103 μg/animal) based on previous studies and the maximum exposure limitation (4 mg/m³) in occupational workplaces set by the Chinese government. In the pentylenetetrazol (PTZ) and kainic acid (KA) seizure models, high-dose CBNPs exposure increased seizure susceptibility in both models and increased spontaneous recurrent seizure (SRS) frequency in the KA model. In vivo local field potential (LFP) recording in KA model mice revealed that both low-dose and high-dose CBNPs exposure increased seizure-like event (SLE) frequency in the SRS interval but shortened SLE duration. Intriguingly, H&E staining and Nissl staining on brain tissue revealed that CBNPs exposure did not cause significant brain tissue morphology or neuronal damage. Detection of inflammatory factors, such as TNF-α, TGF-β1, IL-1β, and IL-6, in brain tissue showed that only high dose of CBNPs exposure increased the expression of cortical TGF-β1. By using the primary cultured neurons, we observed that CBNPs exposure not only significantly decreased the expression of the neuronal marker MAP2 but also enhanced the levels of action potential frequency in the neurons. In general, CBNPs exposure can affect abnormal epileptic discharges during the seizure interval and enhance susceptibility to frequent seizures. Our findings suggest that minimizing CBNPs exposure may be a potential way to prevent or ease seizure.

Chitosan coating does not prevent the effect of the transfer of green silver nanoparticles biosynthesized by Streptomyces malachitus into fetuses via the placenta

Green synthesized nanoparticles are more advantageous over conventionally prepared ones due to less toxicity, production cost, and environmental hazards. With the widespread of the utilization of nanoparticles, little is known about the maternal-fetal transplacental transfer of green nanoparticles. We have biosynthesized silver nanoparticles using metabolites of Streptomyces malachitus and sunlight then coated them with chitosan. These nanoparticles have been characterized and intraperitoneally administered at doses of 100 mg/kg on the 6^th, 8^th, and 10^th gestational days. On the 18^th day of pregnancy, both coated and non-coted NPs were detected in different maternal tissues, placenta, and in fetuses, as determined by estimation of silver content and observation by electron microscopy. Chitosan coating decreased the silver content in different tissues, maybe due to the larger size of coated nanoparticles that retards the transfer. The toxic effects on maternal and fetal tissues were proportional to their silver content, as determined by the liver and kidney functional analysis of pregnant rats and the ultrastructural and histopathological examination of the maternal liver, placenta and fetal liver. The present data suggest that green silver nanoparticles biosynthesized by Streptomyces malachitus cross the placenta and have toxic effects on maternal tissues, placenta, and fetus. Chitosan coating of these nanoparticles decreases the transfer, and consequently, the toxicity. However, it does not prevent this toxicity.

Transcriptomic analyses of the biological effects of black carbon exposure to A549 cells

Ambient black carbon (BC) is found to be associated with increased risk of diverse pulmonary diseases, including acute respiratory inflammation and decreased lung function. Freshly emitted BC (FBC) can be transformed into oxidized BC (OBC) through the photochemical oxidization in the air. How this oxidization process influences the toxicity of BC particles is unclear. Previous studies found FBC and OBC could induce oxidative stress and inflammation. This study aimed to further compare the regulating pathways and tried to reveal the crucial target genes caused by FBC and OBC in A549 cells based on transcriptomic data. A total of 47,000 genes in A549 cells after treated with FBC and OBC were examined using Affymetrix Human U133 plus 2.0 chips. Gene ontology (GO) classification (functional enrichment of differentially expressed genes) and Kyoto encyclopedia of genes and genomes (KEGG) classification (pathway enrichment of differentially expressed genes) were conducted and crucial genes were screened. The results showed that top 50 GO terms of FBC and OBC were not completely consistent. The Go term of cation channel was only identified in OBC group, probably caused by the characteristic that zeta potential of OBC is negative, while, that of FBC is positive. In addition transient receptor potential melastatin 7 (trpm7) gene was suggested to be closely related to this process caused by OBC. There are 47 identical pathways in FBC and OBC group among the top 50 KEGG. The inconsistent pathways are mostly related to inflammation with different up-regulation or down-regulation trends of crucial genes. The KEGG results suggested that FBC and OBC both cause inflammatory responses, but through different regulating pathways. In conclusion, OBC and FBC could induce similar toxic endpoints in A549 cells, but the underline regulating processes are not exactly the same.

Pregnancy exposure to carbon black nanoparticles exacerbates bleomycin-induced lung fibrosis in offspring via disrupting LKB1-AMPK-ULK1 axis-mediated autophagy

Accumulating evidence shows that carbon black nanoparticles (CBNPs) (one of the most used nanoparticles) can induce toxicity via induction of inflammation, oxidative stress and genotoxicity in vitro and in vivo, and epidemiological studies have indicated that the possible correlation between maternal immune activation and risk of developing neuropsychiatric disorder in the offspring. However, whether pregnancy exposure of CBNPs (Pr-CBNPs) enhances the susceptibility to bleomycin (BLM)-induced lung fibrosis in offspring is unknown. Herein, we demonstrated that Pr-CBNPs during gestational day 9-18 via intranasal administration could confer enhanced susceptibility to BLM-induced fibrotic response in offspring, including deteriorative lung pathologic changes and more collagen deposition. Intriguingly, we found that Pr-CBNPs repressed the activation of autophagy (an anti-fibrotic mechanism), which was moderately activated in offspring from mock group. Moreover, Pr-CBNPs was likely to disrupt the LKB1-AMPK-ULK1 axis (a key regulatory pathway for autophagy induction). In summary, this study provides the first evidence that pregnancy exposure to CBNPs can exacerbate BLM-induced lung fibrotic response in offspring probably through disruption of LKB1-AMPK-ULK1 axis-mediated autophagy.

Graphene oxide induces cardiovascular defects in developing zebrafish (Danio rerio) embryo model: In-vivo toxicity assessment

Graphene oxide (GO) has wide engineering applications in various areas, including electronics, energy storage, pharmaceuticals, nanomedicine, environmental remediation and biotechnology, because of its unique physico-chemical properties. In the present study, the risk-related information of GO was evaluated to examine the potential ecological and health risks of developmental toxicity. Although the overall developmental toxicity of GO has been well characterized in zebrafish, however, its release effect at a certain concentration of living organisms with specific cardiovascular defects remains largely elusive. Therefore, this study was conducted to further evaluate the toxicity of GO on embryonic development and cardiovascular defects in zebrafish embryos used as an in-vivo animal model. As a result, the presence of GO at a small concentration (0.1-0.3 mg/mL) does not affect the embryonic development. However, GO at higher concentrations (0.4-1 mg/mL) induces significant embryonic mortality, increase heartbeat, delayed hatching, cardiotoxicity, cardiovascular defects, retardation of cardiac looping, increased apoptosis and decreased hemoglobinization. These results provide valuable information that can be used to study the eco-toxicological effects of GO for assessing its bio-safety according to environmental concentration. In addition, the present results would also be usefully utilized for understanding the environmental risks associated with GO on human health in general.

Toxicity of carbon-based nanomaterials: Reviewing recent reports in medical and biological systems

Application of nanomaterials in our daily life is increasing, day in day out and concerns have raised about their toxicity for human and other organisms. In this manner, carbon-based nanomaterials have been applied to different products due to their unique physicochemical, electrical, mechanical properties, and biological compatibility. But, there are several reports about the negative effects of these materials on biological systems and cellular compartments. This review article describes the various types of carbon-based nanomaterials and methods that use for determining these toxic effects that are reported recently in the papers. Then, extensively discussed the toxic effects of these materials on the human and other living organisms and also their toxicity routs including Neurotoxicity, Hepatotoxicity, Nephrotoxicity, Immunotoxicity, Cardiotoxicity, Genotoxicity and epigenetic toxicity, Dermatotoxicity, and Carcinogenicity.

Effects of erythropoietin on bile duct ligation-induced neuro-inflammation in male rats

Hepatic encephalopathy (HE) is a brain disorder as a result of liver failure. Previous studies have indicated that erythropoietin (EPO) has neuroprotective effects in different neurological diseases. This study addressed the therapeutic effect of a four-week treatment with EPO on neuronal damages in bile duct-ligated rats. Forty male Wistar rats (250–280 g) were used in the present study. The animals were randomly divided into four groups consisting of 10 animals each, including sham, sham + EPO, bile duct ligation (BDL), and BDL + EPO. EPO was intraperitoneally administered every other day (5,000 U/Kg) in the last four weeks after BDL. Biochemical and histological studies were performed to evaluate neurodegeneration. The results revealed that BDL increases the level of hepatic enzymes and total bilirubin. Furthermore, neurodegeneration was significantly increased in the BDL group compared to sham groups. EPO preserved hepatic enzymes and total bilirubin in the treated group. In addition, EPO significantly decreased the neurodegeneration in BDL + EPO compared to the BDL group. Results of this study showed that EPO has neuroprotective effects in the rat model of HE, possibly due to its anti-inflammatory and anti-oxidant properties. Complementary studies are required to clarify the exact mechanisms.

Particle toxicology and health - where are we?

BACKGROUND

Particles and fibres affect human health as a function of their properties such as chemical composition, size and shape but also depending on complex interactions in an organism that occur at various levels between particle uptake and target organ responses. While particulate pollution is one of the leading contributors to the global burden of disease, particles are also increasingly used for medical purposes. Over the past decades we have gained considerable experience in how particle properties and particle-bio interactions are linked to human health. This insight is useful for improved risk management in the case of unwanted health effects but also for developing novel medical therapies. The concepts that help us better understand particles' and fibres' risks include the fate of particles in the body; exposure, dosimetry and dose-metrics and the 5 Bs: bioavailability, biopersistence, bioprocessing, biomodification and bioclearance of (nano)particles. This includes the role of the biomolecule corona, immunity and systemic responses, non-specific effects in the lungs and other body parts, particle effects and the developing body, and the link from the natural environment to human health. The importance of these different concepts for the human health risk depends not only on the properties of the particles and fibres, but is also strongly influenced by production, use and disposal scenarios.

CONCLUSIONS

Lessons learned from the past can prove helpful for the future of the field, notably for understanding novel particles and fibres and for defining appropriate risk management and governance approaches.

Exposure to carbon black nanoparticles during pregnancy persistently damages the cerebrovascular function in female mice

Maternal exposure to carbon black nanoparticles (CBNPs) during pregnancy have been well documented to induce harmful outcomes of offspring on brain function. However, it remains largely unknown whether females exposed to CBNPs during sensitive period of pregnancy can cause the neurotoxic effects on their own body after parturition. In this study, our results showed that pregnancy CBNPs exposure induced the persistent pathological changes in the cerebral cortex tissues and impaired cerebrovascular function of mice manifested by significant alterations of endothelin-1, endothelial nitric oxide synthase, vascular endothelial growth factor-A and ATP-binding cassette transporter G1. Intriguingly, we observed that these deleterious effects on brain and cerebrovascular functions in mice could persist for 49 days after delivery of pups. By using in vitro human umbilical vein endothelial cells, we further verified the potential vascular dysfunction after CBNPs exposure. In summary, our results provide the first evidence that pregnancy CBNPs exposure-induced brain pathological changes and cerebrovascular dysfunction can persist for a relative long time. These finding suggest exposure to CBNPs during sensitive stages of pregnancy may not only show the harmful effects on offspring neurodevelopment, but also result in the irreversible brain damage on mother body.

Nanosized carbon black exposure induces neural injury: effects on nicotinamide adenine dinucleotide phosphate oxidases and endoplasmic reticulum stress

Carbon black in ambient air is believed to be the cause of many diseases; however, its potential neural toxicity and the underlying mechanisms remain poorly understood. The present study is to evaluate the toxic effects of carbon black nanoparticles, Printex 90, on the neural cell line PC-12. The study revealed that Printex 90 treatment significantly decreased cell viability, accompanied by an enormous increase in reactive oxygen species generation and a decrease in ATP. Additionally, NOX2 and NOX4, 4-hydroxynonenal, endoplasmic reticulum (ER) stress marker proteins (IRE-1α, ATF-6, GRP78, PERK and the downstream target protein CHOP) and antioxidative enzymes (glutathione and superoxide dismutase) were evaluated. It showed that Printex 90 significantly upregulated 4-hydroxynonenal, NOX2 and NOX4 expression, and the levels, or activity, of glutathione and superoxide dismutase, were markedly reduced. For the ER stress-associated proteins, Printex 90 induced a significant increase of IRE-1α, ATF-6, GRP78, p-PERK and CHOP expression. Collectively, these results demonstrate that NOX and ER stress are involved in Printex 90-mediated neural damage. Therefore, decreased ER stress and NOX-derived reactive oxygen species generation may provide compensatory protective effects and attenuate Printex 90-induced neural injury.

Modifications of autophagy influenced the Alzheimer-like changes in SH-SY5Y cells promoted by ultrafine black carbon

Ambient ultrafine black carbon (uBC) can potentially cross blood-brain barrier, however, very little is currently known about the effects they may have on central nervous system. This study aimed to explore the roles of autophagy in Alzheimer-like pathogenic changes promoted by uBC in SH-SY5Y cells. We firstly found uBC could cause cytotoxicity and oxidative stress in SH-SY5Y cells. Additionally we found uBC initiated progressive development of Alzheimer's disease (AD) associated features, mainly including neuro-inflammation and phosphorylation of tau protein (p-Tau) accumulation. Meanwhile, autophagy process was activated by uBC probably through phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) pathway. RNA interference and autophagosome-lysosome fusion inhibitor were applied to block autophagy process at different stages. Autophagy dysfunction at the initial membrane expansion stage could aggravate p-Tau accumulation and other Alzheimer-like changes in SH-SY5Y cells promoted by uBC. However, autophagy inhibition at the final stage could alleviate p-Tau accumulation caused by uBC. This suggested that inhibition of the infusion of autophagosome and lysosome could possibly activate ubiquitination degradation pathway to regulate p-Tau equilibrium in SH-SY5Y cells. Our findings further raise the concerns about the effects of uBC on the risk of AD and indicate potential roles of autophagy in early Alzheimer-like pathogenic changes caused by ambient uBC.

Pristine graphene induces cardiovascular defects in zebrafish (Danio rerio) embryogenesis

The multiple effect of pristine graphene (pG) toxicity on cardiovascular developmental defects was assessed using zebrafish as a model. Recently, the nanotoxicity is emerging as a critical issue, and it is more significant in embryogenesis. Especially, graphene and its derivatives have attracted a lot of interest in biomedical applications. However, very little is known about the toxic effects of pG which has been widely used carbon nanomaterial according to concentration and its effects on biological and cardiovascular development. In the present study, we examined the development of zebrafish embryos by exposing to pG (5, 10, 15, 20 and 25 μg/L) under different developmental toxicity end-points such as cardiotoxicity, cardiovascular defect, retardation of cardiac looping, apoptosis and globin expression analysis. For this, the developmental cardiotoxicity of pG at different concentrations and the specific cardiovascular defects thereof were elucidated for the first time. As a result, the exposure to pG was found to be a potential risk factor to cardiovascular system of zebrafish embryos. However, a further study on the variations of physical, molecular properties and mechanisms of nanotoxicity which vary depending on production method and surface functionalization is required. In addition, the potential risks of pG flakes to aquatic organisms and human health should be considered or checked before releasing them to the environment.

Nanoparticulate matter exposure results in neuroinflammatory changes in the corpus callosum

Epidemiological studies have established an association between air pollution particulate matter exposure (PM2.5) and neurocognitive decline. Experimental data suggest that microglia play an essential role in air pollution PM-induced neuroinflammation and oxidative stress. This study examined the effect of nano-sized particulate matter (nPM) on complement C5 deposition and microglial activation in the corpus callosum of mice (C57BL/6J males). nPM was collected in an urban Los Angeles region impacted by traffic emissions. Mice were exposed to 10 weeks of re-aerosolized nPM or filtered air for a cumulative 150 hours. nPM-exposed mice exhibited reactive microglia and 2-fold increased local deposition of complement C5/ C5α proteins and complement component C5a receptor 1 (CD88) in the corpus callosum. However, serum C5 levels did not differ between nPM and filtered air cohorts. These findings demonstrate white matter C5 deposition and microglial activation secondary to nPM exposure. The C5 upregulation appears to be localized to the brain.

Maternal inhalation of carbon black nanoparticles induces neurodevelopmental changes in mouse offspring

Background

Engineered nanoparticles are smaller than 100 nm and designed to improve or creating even new physico-chemical properties. Consequently, toxicological properties of materials may change as size reaches the nm size-range. We examined outcomes related to the central nervous system in the offspring following maternal inhalation exposure to nanosized carbon black particles (Printex 90).

Methods

Time-mated mice (NMRI) were exposed by inhalation, for 45 min/day to 0, 4.6 or 37 mg/m³ aerosolized carbon black on gestation days 4–18, i.e. for a total of 15 days. Outcomes included maternal lung inflammation (differential cell count in bronchoalveolar lavage fluid and Saa3 mRNA expression in lung tissue), offspring neurohistopathology and behaviour in the open field test.

Results

Carbon black exposure did not cause lung inflammation in the exposed females, measured 11 or 28–29 days post-exposure. Glial fibrillary acidic protein (GFAP) expression levels were dose-dependently increased in astrocytes around blood vessels in the cerebral cortex and hippocampus in six weeks old offspring, indicative of reactive astrogliosis. Also enlarged lysosomal granules were observed in brain perivascular macrophages (PVMs) in the prenatally exposed offspring. The number of parvalbumin-positive interneurons and the expression levels of parvalbumin were decreased in the motor and prefrontal cortices at weaning and 120 days of age in the prenatally exposed offspring. In the open field test, behaviour was dose-dependently altered following maternal exposure to Printex 90, at 90 days of age. Prenatally exposed female offspring moved a longer total distance, and especially males spent significantly longer time in the central zone of the maze. In the offspring, the described effects were long-lasting as they were present at all time points investigated.

Conclusion

The present study reports for the first time that maternal inhalation exposure to Printex 90 carbon black induced dose-dependent denaturation of PVM and reactive astrocytes, similarly to the findings observed following maternal exposure to Printex 90 by airway instillation. Of note, some of the observed effects have striking similarities with those observed in mouse models of neurodevelopmental disorders.

Electronic supplementary material

The online version of this article (10.1186/s12989-018-0272-2) contains supplementary material, which is available to authorized users.

Dysregulation of major functional genes in frontal cortex by maternal exposure to carbon black nanoparticle is not ameliorated by ascorbic acid pretreatment

Recent cohort studies have revealed that perinatal exposure to particulate air pollution, including carbon-based nanoparticles, increases the risk of brain disorders. Although developmental neurotoxicity is currently a major issue in the toxicology of nanoparticles, critical information for understanding the mechanisms underlying the developmental neurotoxicity of airway exposure to carbon black nanoparticle (CB-NP) is still lacking. In order to investigate these mechanisms, we comprehensively analyzed fluctuations in the gene expression profile of the frontal cortex of offspring mice exposed maternally to CB-NP, using microarray analysis combined with Gene Ontology information. We also analyzed differences in the enriched function of genes dysregulated by maternal CB-NP exposure with and without ascorbic acid pretreatment to refine specific alterations in gene expression induced by CB-NP. Total of 652 and 775 genes were dysregulated by CB-NP in the frontal cortex of 6- and 12-week-old offspring mice, respectively. Among the genes dysregulated by CB-NP, those related to extracellular matrix structural constituent, cellular response to interferon-beta, muscle organ development, and cysteine-type endopeptidase inhibitor activity were ameliorated by ascorbic acid pretreatment. A large proportion of the dysregulated genes, categorized in hemostasis, growth factor, chemotaxis, cell proliferation, blood vessel, and dopaminergic neurotransmission, were, however, not ameliorated by ascorbic acid pretreatment. The lack of effects of ascorbic acid on the dysregulation of genes following maternal CB-NP exposure suggests that the contribution of oxidative stress to the effects of CB-NP on these biological functions, i.e., cell migration and proliferation, blood vessel maintenance, and dopaminergic neuron system, may be limited. At least, ascorbic acid pretreatment is hardly likely to be able to protect the brain of offspring from developmental neurotoxicity of CB-NP. The present study provides insight into the mechanisms underlying developmental neurotoxicity following maternal nanoparticle exposure.

Early life exposure to air pollution particulate matter (PM) as risk factor for attention deficit/hyperactivity disorder (ADHD): Need for novel strategies for mechanisms and causalities

Epidemiological studies have demonstrated that air pollution particulate matter (PM) and adsorbed toxicants (organic compounds and trace metals) may affect child development already in utero. Recent studies have also indicated that PM may be a risk factor for neurodevelopmental disorders (NDDs). A pattern of increasing prevalence of attention deficit/hyperactivity disorder (ADHD) has been suggested to partly be linked to environmental pollutants exposure, including PM. Epidemiological studies suggest associations between pre- or postnatal exposure to air pollution components and ADHD symptoms. However, many studies are cross-sectional without possibility to reveal causality. Cohort studies are often small with poor exposure characterization, and confounded by traffic noise and socioeconomic factors, possibly overestimating the study associations. Furthermore, the mechanistic knowledge how exposure to PM during early brain development may contribute to increased risk of ADHD symptoms or cognitive deficits is limited. The closure of this knowledge gap requires the combined use of well-designed longitudinal cohort studies, supported by mechanistic in vitro studies. As ADHD has profound consequences for the children affected and their families, the identification of preventable risk factors such as air pollution exposure should be of high priority.

Maternal Exposure to PM2.5 during Pregnancy Induces Impaired Development of Cerebral Cortex in Mice Offspring

Air pollution is a serious environmental health problem closely related to the occurrence of central nervous system diseases. Exposure to particulate matter with an aerodynamic diameter less than or equal to 2.5 µm (PM_2.5) during pregnancy may affect the growth and development of infants. The present study was to investigate the effects of maternal exposure to PM_2.5 during pregnancy on brain development in mice offspring. Pregnant mice were randomly divided into experimental groups of low-, medium-, or high-dosages of PM_2.5, a mock-treated group which was treated with the same amount of phosphate buffer solution (PBS), and acontrol group which was untreated. The ethology of offspring mice on postnatal days 1, 7, 14, 21, and 30, along with neuronal development and apoptosis in the cerebral cortex were investigated. Compared with the control, neuronal mitochondrial cristae fracture, changed autophagy characteristics, significantly increased terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) positive cell rate, and mRNA levels of apoptosis-related caspase-8 and caspase-9 were found in cerebral cortex of mice offspring from the treatment groups, with mRNA levels of Bcl-2 and ratio of Bcl-2 to Bax decreased. Treatment groups also demonstrated enhanced protein expressions of apoptosis-related cleaved caspase-3, cleaved caspase-8 and cleaved caspase-9, along with declined proliferating cell nuclear antigen (PCNA), Bcl-2, and ratio of Bcl-2 to Bax. Open field experiments and tail suspension experiments showed that exposure to high dosage of PM_2.5 resulted in decreased spontaneous activities but increased static accumulation time in mice offspring, indicating anxiety, depression, and social behavioral changes. Our results suggested that maternal exposure to PM_2.5 during pregnancy might interfere with cerebral cortex development in mice offspring by affecting cell apoptosis.

Cellular responses of human astrocytoma cells to dust from the Acheson process: An in vitro study

Silicon carbide (SiC) is largely used in various products such as diesel particulate filters and solar panels. It is produced through the Acheson process where aerosolized fractions of SiC and other by-products are generated in the work environment and may potentially affect the workers' health. In this study, dust was collected directly on a filter in a furnace hall over a time period of 24h. The collected dust was characterized by scanning electron microscopy and found to contain a high content of graphite particles, and carbon and silicon containing particles. Only 6% was classified as SiC, whereof only 10% had a fibrous structure. To study effects of exposure beyond the respiratory system, neurotoxic effects on human astrocytic cells, were investigated. Both low, occupationally relevant, and high doses from 9E-6μg/cm² up to 4.5μg/cm² were used, respectively. Cytotoxicity assay indicated no effects of low doses but an effect of the higher doses after 24h. Furthermore, investigation of intracellular reactive oxygen species (ROS) indicated no effects with low doses, whereas a higher dose of 0.9μg/cm² induced a significant increase in ROS and DNA damage. In summary, low doses of dust from the Acheson process may exert no or little toxic effects, at least experimentally in the laboratory on human astrocytes. However, higher doses have implications and are likely a result of the complex composition of the dust.

Current understanding of the toxicological risk posed to the fetus following maternal exposure to nanoparticles

INTRODUCTION

With the broad use of nanotechnology, the number and variety of nanoparticles that humans can be exposed to has further increased. Consequently, there is growing concern about the potential effect of maternal exposure to various nanoparticles during pregnancy on a fetus. However, the nature of this risk is not fully known. Areas covered: In this review, materno-fetal transfer of nanoparticles through the placenta is described. Both prenatal and postnatal adverse effects, such as fetal resorption, malformation and injury to various organs in mice exposed to nanoparticles are reviewed. The potential mechanisms of toxicity are also discussed. Expert opinion: The toxicology and safe application of recently developed nanoparticles has attracted much attention in the past few years. Although many studies have demonstrated the toxicology of nanoparticles in various species, only a small number of studies have examined the effect on a fetus after maternal exposure to nanoparticles. This is particularly important, because the developing fetus is especially vulnerable to the toxic effects of nanoparticles during fetal development due to the unique physical stage of the fetus. Nanoparticles may directly or indirectly impair fetal development and growth after maternal exposure to nanoparticles.

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.

Molecular Mechanisms of Developmental Toxicity Induced by Graphene Oxide at Predicted Environmental Concentrations

Developmental toxicity is a critical issue in nanotoxicity. However, very little is known about the effects of graphene oxide (GO, a widely used carbon material) at predicted environmental concentrations on biological development or the specific molecular mechanisms. The present study established that the development of zebrafish embryos exposed to trace concentrations (1-100 μg/L) of GO was impaired because of DNA modification, protein carbonylation and excessive generation of reactive oxygen species (ROS), especially the superoxide radical. Noticeably, there was a nonmonotonic response of zebrafish developmental toxicity to GO at μg/L to mg/L levels. Transcriptomics analysis revealed that disturbing collagen- and matrix metalloproteinase (MMP)-related genes affected the skeletal and cardiac development of zebrafish. Moreover, metabolomics analysis showed that the inhibition of amino acid metabolism and the ratios of unsaturated fatty acids (UFAs) to saturated fatty acids (SFAs) contributed to the above developmental toxicity. The present work verifies the developmental toxicity of GO at trace concentrations and illustrates for the first time the specific molecular mechanisms thereof. Because of the potential developmental toxicity of GO at trace concentrations, government administrators and nanomaterial producers should consider its potential risks prior to the widespread environmental exposure to GO.