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.

Environmentally induced epigenetic toxicity: potential public health concerns.

Throughout our lives, epigenetic processes shape our development and enable us to adapt to a constantly changing environment. Identifying and understanding environmentally induced epigenetic change(s) that may lead to adverse outcomes is vital for protecting public health. This review, therefore, examines the present understanding of epigenetic mechanisms involved in the mammalian life cycle, evaluates the current evidence for environmentally induced epigenetic toxicity in human cohorts and rodent models and highlights the research considerations and implications of this emerging knowledge for public health and regulatory toxicology. Many hundreds of studies have investigated such toxicity, yet relatively few have demonstrated a mechanistic association among specific environmental exposures, epigenetic changes and adverse health outcomes in human epidemiological cohorts and/or rodent models. While this small body of evidence is largely composed of exploratory in vivo high-dose range studies, it does set a precedent for the existence of environmentally induced epigenetic toxicity. Consequently, there is worldwide recognition of this phenomenon, and discussion on how to both guide further scientific research towards a greater mechanistic understanding of environmentally induced epigenetic toxicity in humans, and translate relevant research outcomes into appropriate regulatory policies for effective public health protection.

Decreased translation of Dio3 mRNA is associated with drug-induced hepatotoxicity.

Recent work has demonstrated the importance of post-transcriptional gene regulation in toxic responses. In the present study, we used two rat models to investigate mRNA translation in the liver following xenobiotic-induced toxicity. By combining polysome profiling with genomic methodologies, we were able to assess global changes in hepatic mRNA translation. Dio3 (iodothyronine deiodinase type III) was identified as a gene that exhibited specific translational repression and had a functional role in a number of relevant canonical pathways. Western blot analysis indicated that this repression led to reduced D3 (the protein expressed by Dio3) levels, enhanced over time and with increased dose. Using Northern blotting techniques and qRT-PCR (quantitative reverse transcription-PCR), we confirmed further that there was no reduction in Dio3 mRNA, suggesting that translational repression of Dio3 is an important determinant of the reduced D3 protein expression following liver damage. Finally, we show that drug-induced hepatotoxicity appears to cause localized disruptions in thyroid hormone levels in the liver and plasma. We suggest that this leads to reduced translation of Dio3 mRNA, which results in decreased D3 production. It may therefore be possible that this is an important mechanism by which the liver can, upon early signs of damage, act rapidly to maintain its own energy equilibrium, thereby avoiding global disruption of the hypothalamic-pituitary-thyroid axis.

The potential impacts of micro-and-nano plastics on various organ systems in humans.

Humans are exposed to micro-and-nano plastics (MNPs) through various routes, but the adverse health effects of MNPs on different organ systems are not yet fully understood. This review aims to provide an overview of the potential impacts of MNPs on various organ systems and identify knowledge gaps in current research. The summarized results suggest that exposure to MNPs can lead to health effects through oxidative stress, inflammation, immune dysfunction, altered biochemical and energy metabolism, impaired cell proliferation, disrupted microbial metabolic pathways, abnormal organ development, and carcinogenicity. There is limited human data on the health effects of MNPs, despite evidence from animal and cellular studies. Most of the published research has focused on specific types of MNPs to assess their toxicity, while other types of plastic particles commonly found in the environment remain unstudied. Future studies should investigate MNPs exposure by considering realistic concentrations, dose-dependent effects, individual susceptibility, and confounding factors.

Variation in stability of endogenous reference genes in fallopian tubes and endometrium from healthy and ectopic pregnant women.

RT-qPCR is commonly employed in gene expression studies in ectopic pregnancy. Most use RN18S1, ß-actin or GAPDH as internal controls without validation of their suitability as reference genes. A systematic study of the suitability of endogenous reference genes for gene expression studies in ectopic pregnancy is lacking. The aims of this study were therefore to evaluate the stability of 12 reference genes and suggest those that are stable for use as internal control genes in fallopian tubes and endometrium from ectopic pregnancy and healthy non-pregnant controls. Analysis of the results showed that the genes consistently ranked in the top six by geNorm and NormFinder algorithms, were UBC, GAPDH, CYC1 and EIF4A2 (fallopian tubes) and UBC and ATP5B (endometrium). mRNA expression of NAPE-PLD as a test gene of interest varied between the groups depending on which of the 12 reference genes was used as internal controls. This study demonstrates that arbitrary selection of reference genes for normalisation in RT-qPCR studies in ectopic pregnancy without validation, risk producing inaccurate data and should therefore be discouraged.

A systematic review of outdoor airborne fungal spore seasonality across Europe and the implications for health.

Fungal spores make up a significant proportion of organic matter within the air. Allergic sensitisation to fungi is associated with conditions including allergic fungal airway disease. This systematic review analyses outdoor fungal spore seasonality across Europe and considers the implications for health. Seventy-four studies met the inclusion criteria, the majority of which (n = 64) were observational sampling studies published between 1978 and 2020. The most commonly reported genera were the known allergens Alternaria and Cladosporium, measured in 52 and 49 studies, respectively. Both displayed statistically significant increased season length in south-westerly (Mediterranean) versus north-easterly (Atlantic and Continental) regions. Although there was a trend for reduced peak or annual Alternaria and Cladosporium spore concentrations in more northernly locations, this was not statistically significant. Peak spore concentrations of Alternaria and Cladosporium exceeded clinical thresholds in nearly all locations, with median peak concentrations of 665 and 18,827 per m3, respectively. Meteorological variables, predominantly temperature, precipitation and relative humidity, were the main factors associated with fungal seasonality. Land-use was identified as another important factor, particularly proximity to agricultural and coastal areas. While correlations of increased season length or decreased annual spore concentrations with increasing average temperatures were reported in multi-decade sampling studies, the number of such studies was too small to make any definitive conclusions. Further, up-to-date studies covering underrepresented geographical regions and fungal taxa (including the use of modern molecular techniques), and the impact of land-use and climate change will help address remaining knowledge gaps. Such knowledge will help to better understand fungal allergy, develop improved fungal spore calendars and forecasts with greater geographical coverage, and promote increased awareness and management strategies for those with allergic fungal disease.

Metabarcoding of Soil Fungi from Different Urban Greenspaces Around Bournemouth in the UK.

Soil microbes are important for public health. Increasing urbanisation is adversely affecting soil microbiota, which may be contributing to the global rise of immune-related diseases. Fungi are key components of urban environments that can be negatively impacted by altered land-use, land-management and climate change, and are implicated in the development and exacerbation of non-communicable diseases such as allergy, asthma and chronic inflammatory conditions. Fungal metagenomics is building knowledge on fungi within different environments (the environmental mycobiome), fungi on and within the human body (the human mycobiome), and their association with disease. Here, we demonstrate the added value of a multi-region metabarcoding approach to analyse soil mycobiomes from five urban greenspaces (lawns, parklands, bareground, young forest and old forest). While results were comparable across the three regions (ITS1, ITS2 and LSU), each identified additional fungal taxa that were unique to the region. Combining the results therefore provided a more comprehensive analysis across all fungal taxonomic ranks, identifying statistically significant differences in the fungal composition of the five soil types. Assignment of fungal taxa into ecological guilds revealed those differences of biological relevance to public health. The greatest differences were between the soil mycobiome of lawns and forests. Of most concern was the significant increase in the known human allergens Alternaria, Bipolaris, Cladosporium and Fusarium within urban lawn and parkland vs forest soils. By improving our understanding of local variations in fungal taxa across urban greenspaces, we have the potential to boost the health of local residents through improved urban planning.

Perturbation of microRNA signalling by doxorubicin in spermatogonial, Leydig and Sertoli cell lines in vitro.

We have previously shown that in addition to its widely recognised cardiotoxicity, the chemotherapeutic doxorubicin (DOX) is able to induce transcriptional, microRNA (miRNA) and DNA methylation changes in the mouse testis. These changes perturb pathways involved in stress/cell death and survival and testicular function and lead to germ cell loss and reproductive organ damage. Here, we further investigated the differential miRNA expression induced by DOX in mouse spermatogonial (GC1), Leydig (TM3) and Sertoli (TM4) cell lines in vitro. We began by performing cell cycle analysis of the three mouse testicular cell lines to evaluate their sensitivity to DOX and thus select suitable doses for miRNA profiling. In keeping with our in vivo data, the spermatogonial cell line was the most sensitive, and the Sertoli cell line the most resistant to DOX-induced cell cycle arrest. We then further demonstrated that each cell line has a distinct miRNA profile, which is perturbed upon treatment with DOX. Pathway analysis identified changes in the miRNA-mediated regulation of specialised signalling at germ-Sertoli and Sertoli-Sertoli cell junctions following treatment with DOX. Amongst the most significant disease categories associated with DOX-induced miRNA expression were organismal injury and abnormalities, and reproductive system disease. This suggests that miRNAs play significant roles in both normal testicular function and DOX-induced testicular toxicity. Comparison of our in vitro and in vivo data highlights that in vitro cell models can provide valuable mechanistic information, which may also help facilitate the development of biomarkers of testicular toxicity and high-throughput in vitro screening methods to identify potential testicular toxicants.

Children's Environmental Health in Thailand: Past, Present, and Future.

BACKGROUND: There is increasing evidence of a link between environmental pollution and preventable diseases in developing countries, including Thailand. Economic development has generated several types of pollution that can affect population health. While these environmental health effects can be observed throughout life, pregnant women and children represent particularly vulnerable and sensitive groups. METHODS: The published epidemiological literature investigating environmental chemical exposure in Thai children was reviewed, highlighting those that investigated associations between exposure and subsequent health outcomes. RESULTS: The majority of the Thai epidemiological studies on environmental health in children were cross-sectional in design, with some demonstrating associations between exposure and outcome. The three main types of chemical exposure in Thai children were pesticides, heavy metals, and air pollution, which resulted from agricultural activities in countryside areas, industrial zones (both registered and unregistered establishments), mining, and traffic in inner cities. Major health outcomes included detrimental effects on cognitive function and cancer risk. Pesticide exposure was focused on, but not limited to, agricultural areas. The success of the Thai environmental policy to introduce lead-free petrol can be demonstrated by the decline of mean blood lead levels in children, particularly in urban areas. However, unregistered lead-related factories and smelters act as hidden sources. In addition, there is increasing concern, but little acknowledgement, about the effects of chronic arsenic exposure related to mining. Lastly, air pollution remains a problem in both dense city populations due to traffic and in rural areas due to contamination of indoor air and house dust with heavy metals, endotoxins and other allergens. CONCLUSIONS: The increasing number of published articles demonstrates an improved awareness of children's environmental health in Thailand. Chemical hazards, including the improper use of pesticides, environmental contamination with heavy metals (lead and arsenic), and air pollution in inner cities and indoor air, continue to be growing issues.

Perturbation of epigenetic processes by doxorubicin in the mouse testis.

Epigenetic processes play a major role in normal mammalian development, particularly during gametogenesis and early embryogenesis. Thus, perturbation of epigenetic processes in the testis by xenobiotics could have a major impact on testicular function and fertility, and potentially affect the development and health of subsequent generations. There has been substantial research into the epigenetic toxicity of environmental exposures over the last decade. However, few studies have focussed on pharmaceutical drugs, which due to the nature of their use are typically found at much higher concentrations within exposed individuals than environmental chemicals. Here, we investigated genome-wide changes in testicular mRNA transcription, microRNA expression and DNA methylation to assess the contribution of epigenetic mechanisms to the testicular toxicity induced by doxorubicin (DOX) as a representative, widely used and well-characterised anti-cancer drug. We demonstrated that DOX is able to induce transcriptional, microRNA and DNA methylation changes, which perturb pathways involved in stress/cell death and survival and testicular function and lead to germ cell loss and reproductive organ damage. This identified potential novel mechanisms of DOX-induced testicular toxicity for further focussed investigations. Such work is required to fully assess the role of epigenetics in toxicity, determine whether single and/or multigenerational epigenetic toxicity is a real public health concern, and begin to develop and incorporate relevant epigenetic endpoints into regulatory toxicology.

The effect of mifepristone (RU486) on the endocannabinoid system in human plasma and first-trimester trophoblast of women undergoing termination of pregnancy.

INTRODUCTION: High anandamide (AEA) concentrations are detrimental for implantation and early pregnancy. Progesterone, essential for pregnancy, may keep AEA levels low by increasing fatty acid amide hydrolase (FAAH) expression. Here the effect of RU486, a P4 antagonist used to initiate medical termination of pregnancy (MTOP), on plasma AEA concentrations and the endocannabinoid system (ECS) in trophoblasts was examined. OBJECTIVE: Quantification of the endocannabinoid concentrations and expression of the ECS in trophoblast tissue of MTOP women and women undergoing surgical termination of pregnancy (STOP). DESIGN AND SETTING: A prospective study at the University Hospitals of Leicester National Health Service Trust. PATIENTS AND METHODS: AEA, N-oleoylethanolamine (OEA), and N-palmitolylethanolamine (PEA) concentrations in trophoblast tissues and blood samples from 68 MTOP and 15 STOP were analyzed by ultra-high-performance liquid chromatography-tandem mass spectrometry. ECS expression was determined by immunohistochemistry, quantitative RT-PCR, and Western blotting. RESULTS: Concentrations of AEA, OEA, and PEA were significantly higher in MTOP than STOP trophoblasts (P = .0062, P = .016, and P = .0029, respectively), whereas no significant differences in plasma AEA, OEA, and PEA concentrations were observed even though plasma AEA and PEA concentrations were significantly (P = .005 and P = .025, respectively) increased the day after RU486 administration in women undergoing MTOP. Changes in the immunohistochemical densities of the AEA modifying enzymes N-acylphophatidylethanolamine-phospholipase D (NAPE-PLD) and FAAH, and the cannabinoid receptors (CB1 and CB2) were observed with increased NAPE-PLD, FAAH, and CB1 expression seen in the trophoblast of MTOP patients. CONCLUSIONS: Trophoblast after MTOP demonstrated high AEA concentrations with increased expression of NAPE-PLD, FAAH, and CB1.

Smoking induces differential miRNA expression in human spermatozoa: a potential transgenerational epigenetic concern?

Recent work has suggested that environmental chemicals, including those contained in cigarette smoke, can have adverse effects on the exposed individuals as well as their future progeny. The mechanisms underlying transmission of environmentally induced phenotypes through the germ line are not well understood. However, a predominant process appears to be the establishment of permanent heritable epigenetic alterations, and a number of studies have implicated microRNAs in such processes. Here, we show that cigarette smoke induces specific differences in the spermatozoal microRNA content of human smokers compared with non-smokers, and that these altered microRNAs appear to predominantly mediate pathways vital for healthy sperm and normal embryo development, particularly cell death and apoptosis. microRNA-mediated perturbation of such pathways may explain how harmful phenotypes can be induced in the progeny of smokers.

Ectopic pregnancy is associated with high anandamide levels and aberrant expression of FAAH and CB1 in fallopian tubes.

CONTEXT: Ectopic pregnancy is associated with significant morbidity and mortality, but the molecular mechanisms underlying this condition remain unclear. Although the endocannabinoids, N-arachidonoylethanolamine (anandamide), N-oleoylethanolamine, and N-palmitoylethanolamine, are thought to play a negative role in ectopic pregnancy, their precise role(s) within the fallopian tube remains unclear. Anandamide activates cannabinoid receptors (CB1 and CB2) and, together with its degrading [e.g. fatty acid amide hydrolase (FAAH)] and synthesizing enzymes (e.g. N-acyl-phosphatidylethanolamine-specific phospholipase D), forms the endocannabinoid system. High anandamide levels are associated with tubal arrest of embryos in mice and may have a similar role in women. OBJECTIVE: The aims were to quantify the levels of the endocannabinoids and evaluate the expression of the modulating enzymes and the cannabinoid receptors in fallopian tubes of women with ectopic pregnancy compared to those of nonpregnant women. DESIGN AND SETTING: We conducted a prospective study at the University Hospitals of the Leicester National Health Service Trust. PARTICIPANTS AND METHODS: Fallopian tubes collected from women with ectopic pregnancy and nonpregnant women with regular menstrual cycles were used for quantification of endocannabinoids by ultra-HPLC tandem mass spectrometry, were fixed in formalin for immunohistochemistry, and had RNA extracted for RT-quantitative PCR or protein extracted for immunoblotting. RESULTS: Anandamide, but not N-oleoylethanolamine and N-palmitoylethanolamine, levels were significantly higher in ectopic fallopian tubes. Endocannabinoid levels from isthmus to ampulla were not significantly different. Cannabinoid receptors and endocannabinoid modulating enzymes were localized in fallopian tube epithelium by immunohistochemistry and showed reduced CB1 and FAAH expression in ectopic pregnancy. CONCLUSION: High anandamide levels and reduced expression of CB1 and FAAH may play a role in ectopic implantation.

Targeting of the Arpc3 actin nucleation factor by miR-29a/b regulates dendritic spine morphology.

Previous studies have demonstrated that microribonucleic acids (miRs) are key regulators of protein expression in the brain and modulate dendritic spine morphology and synaptic activity. To identify novel miRs involved in neuronal plasticity, we exposed adult mice to chronic treatments with nicotine, cocaine, or amphetamine, which are psychoactive drugs that induce well-documented neuroadaptations. We observed brain region- and drug-specific changes in miR expression levels and identified miR-29a/b as regulators of synaptic morphology. In vitro imaging experiments indicated that miR-29a/b reduce mushroom-shaped dendritic spines on hippocampal neurons with a concomitant increase in filopodial-like outgrowths, suggesting an effect on synapse formation via actin cytoskeleton remodeling. We identified Arpc3, a component of the ARP2/3 actin nucleation complex, as a bona fide target for down-regulation by miR-29a/b. This work provides evidence that targeting of Arpc3 by miR-29a/b fine tunes structural plasticity by regulating actin network branching in mature and developing spines.

Doxorubicin in vivo rapidly alters expression and translation of myocardial electron transport chain genes, leads to ATP loss and caspase 3 activation.

BACKGROUND: Doxorubicin is one of the most effective anti-cancer drugs but its use is limited by cumulative cardiotoxicity that restricts lifetime dose. Redox damage is one of the most accepted mechanisms of toxicity, but not fully substantiated. Moreover doxorubicin is not an efficient redox cycling compound due to its low redox potential. Here we used genomic and chemical systems approaches in vivo to investigate the mechanisms of doxorubicin cardiotoxicity, and specifically test the hypothesis of redox cycling mediated cardiotoxicity. METHODOLOGY/PRINCIPAL FINDINGS: Mice were treated with an acute dose of either doxorubicin (DOX) (15 mg/kg) or 2,3-dimethoxy-1,4-naphthoquinone (DMNQ) (25 mg/kg). DMNQ is a more efficient redox cycling agent than DOX but unlike DOX has limited ability to inhibit gene transcription and DNA replication. This allowed specific testing of the redox hypothesis for cardiotoxicity. An acute dose was used to avoid pathophysiological effects in the genomic analysis. However similar data were obtained with a chronic model, but are not specifically presented. All data are deposited in the Gene Expression Omnibus (GEO). Pathway and biochemical analysis of cardiac global gene transcription and mRNA translation data derived at time points from 5 min after an acute exposure in vivo showed a pronounced effect on electron transport chain activity. This led to loss of ATP, increased AMPK expression, mitochondrial genome amplification and activation of caspase 3. No data gathered with either compound indicated general redox damage, though site specific redox damage in mitochondria cannot be entirely discounted. CONCLUSIONS/SIGNIFICANCE: These data indicate the major mechanism of doxorubicin cardiotoxicity is via damage or inhibition of the electron transport chain and not general redox stress. There is a rapid response at transcriptional and translational level of many of the genes coding for proteins of the electron transport chain complexes. Still though ATP loss occurs with activation caspase 3 and these events probably account for the heart damage.