Integrated proteomic and metabolomic analysis to assess the effects of pure and benzo[a]pyrene-loaded carbon black particles on energy metabolism and motility in the human endothelial cell line EA.hy926

Degenerative and Regenerative Actin Cytoskeleton Rearrangements, Cell Death, and Paradoxical Proliferation in the Gills of Pearl Gourami (Trichogaster leerii) Exposed to Suspended Soot Microparticles

The effect is studied of water-suspended soot microparticles on the actin cytoskeleton, apoptosis, and proliferation in the gill epithelium of pearl gourami. To this end, the fish are kept in aquariums with 0.005 g/L of soot for 5 and 14 days. Laser confocal microscopy is used to find that at the analyzed times of exposure to the pollutant zones appear in the gill epithelium, where the actin framework of adhesion belts dissociates and F-actin either forms clumps or concentrates perinuclearly. It is shown that the exposure to soot microparticles enhances apoptosis. On day 5, suppression of the proliferation of cells occurs, but the proliferation increases to the control values on day 14. Such a paradoxical increase in proliferation may be a compensatory process, maintaining the necessary level of gill function under the exposure to toxic soot. This process may occur until the gills' recovery reserve is exhausted. In general, soot microparticles cause profound changes in the actin cytoskeleton in gill cells, greatly enhance cell death, and influence cell proliferation as described. Together, these processes may cause gill dysfunction and affect the viability of fish.

The toxicity of nanoparticles and their interaction with cells: an in vitro metabolomic perspective

Nowadays, nanomaterials (NMs) are widely present in daily life due to their significant benefits, as demonstrated by their application in many fields such as biomedicine, engineering, food, cosmetics, sensing, and energy. However, the increasing production of NMs multiplies the chances of their release into the surrounding environment, making human exposure to NMs inevitable. Currently, nanotoxicology is a crucial field, which focuses on studying the toxicity of NMs. The toxicity or effects of nanoparticles (NPs) on the environment and humans can be preliminary assessed in vitro using cell models. However, the conventional cytotoxicity assays, such as the MTT assay, have some drawbacks including the possibility of interference with the studied NPs. Therefore, it is necessary to employ more advanced techniques that provide high throughput analysis and avoid interferences. In this case, metabolomics is one of the most powerful bioanalytical strategies to assess the toxicity of different materials. By measuring the metabolic change upon the introduction of a stimulus, this technique can reveal the molecular information of the toxicity induced by NPs. This provides the opportunity to design novel and efficient nanodrugs and minimizes the risks of NPs used in industry and other fields. Initially, this review summarizes the ways that NPs and cells interact and the NP parameters that play a role in this interaction, and then the assessment of these interactions using conventional assays and the challenges encountered are discussed. Subsequently, in the main part, we introduce the recent studies employing metabolomics for the assessment of these interactions in vitro.

Benzo(a)pyrene and cardiovascular diseases: An overview of pre-clinical studies focused on the underlying molecular mechanism

Benzo(a)pyrene (BaP) is a highly toxic and carcinogenic polycyclic aromatic hydrocarbon (PAH) whose toxicological effects in the vessel-wall cells have been recognized. Many lines of evidence suggest that tobacco smoking and foodborne BaP exposure play a pivotal role in the dysfunctions of vessel-wall cells, such as vascular endothelial cell and vascular smooth muscle cells, which contribute to the formation and worsening of cardiovascular diseases (CVDs). To clarify the underlying molecular mechanism of BaP-evoked CVDs, the present study mainly focused on both cellular and animal reports whose keywords include BaP and atherosclerosis, abdominal aortic aneurysm, hypertension, or myocardial injury. This review demonstrated the aryl hydrocarbon receptor (AhR) and its relative signal transduction pathway exert a dominant role in the oxidative stress, inflammation response, and genetic toxicity of vessel-wall cells. Furthermore, antagonists and synergists of BaP are also discussed to better understand its mechanism of action on toxic pathways.

Protective Effect of Nebivolol against Oxidative Stress Induced by Aristolochic Acids in Endothelial Cells

Aristolochic acids (AAs) are powerful nephrotoxins that cause severe tubulointerstitial fibrosis. The biopsy-proven peritubular capillary rarefaction may worsen the progression of renal lesions via tissue hypoxia. As we previously observed the overproduction of reactive oxygen species (ROS) by cultured endothelial cells exposed to AA, we here investigated in vitro AA-induced metabolic changes by 1H-NMR spectroscopy on intracellular medium and cell extracts. We also tested the effects of nebivolol (NEB), a β-blocker agent exhibiting antioxidant properties. After 24 h of AA exposure, significantly reduced cell viability and intracellular ROS overproduction were observed in EAhy926 cells; both effects were counteracted by NEB pretreatment. After 48 h of exposure to AA, the most prominent metabolite changes were significant decreases in arginine, glutamate, glutamine and glutathione levels, along with a significant increase in the aspartate, glycerophosphocholine and UDP-N-acetylglucosamine contents. NEB pretreatment slightly inhibited the changes in glutathione and glycerophosphocholine. In the supernatants from exposed cells, a decrease in lactate and glutamate levels, together with an increase in glucose concentration, was found. The AA-induced reduction in glutamate was significantly inhibited by NEB. These findings confirm the involvement of oxidative stress in AA toxicity for endothelial cells and the potential benefit of NEB in preventing endothelial injury.

Integrated Epigenetics, Transcriptomics, and Metabolomics to Analyze the Mechanisms of Benzo[a]pyrene Neurotoxicity in the Hippocampus

Benzo[a]pyrene (B[a]P) is a common environmental pollutant that is neurotoxic to mammals, which can cause changes to hippocampal function and result in cognitive disorders. The mechanisms of B[a]P-induced impairments are complex .To date there have been no studies on the association of epigenetic, transcriptomic, and metabolomic changes with neurotoxicity after B[a]P exposure. In the present study, we investigated the global effect of B[a]P on DNA methylation patterns, noncoding RNAs (ncRNAs) expression, coding RNAs expression, and metabolites in the rat hippocampus. Male Sprague Dawley rats (SD rats) received daily gavage of B[a]P (2.0 mg/kg body weight [BW]) or corn oil for 7 weeks. Learning and memory ability was analyzed using the Morris water maze (MWM) test and change to cellular ultrastructure in the hippocampus was analyzed using electron microscope observation. Integrated analysis of epigenetics, transcriptomics, and metabolomics was conducted to investigate the effect of B[a]P exposure on the signaling and metabolic pathways. Our results suggest that B[a]P could lead to learning and memory deficits, likely as a result of epigenetic and transcriptomic changes that further affected the expression of CACNA1C, Tpo, etc. The changes in expression ultimately affecting LTP, tyrosine metabolism, and other important metabolic pathways.

Toxicogenomics - What added Value Do These Approaches Provide for Carcinogen Risk Assessment?

It is still a major challenge to protect humans at workplaces and in the environment. To cope with this task, it is a prerequisite to obtain detailed information on the extent of chemical perturbations of biological pathways, in particular, adaptive vs. adverse effects and the dose-response relationships. This knowledge serves as the basis for the classification of non-carcinogens and carcinogens and for further distinguishing carcinogens in genotoxic (DNA damaging) or non-genotoxic compounds. Basing on quantitative dose-response relationships, points of departures can be derived for chemical risk assessment. In recent years, new methods have shown their capability to support the established rodent models of carcinogenicity testing. In vitro high throughput screening assays assess more comprehensively cell response. In addition, omics technologies were applied to study the mode of action of chemicals whereby the term "toxicogenomics" comprises various technologies such as transcriptomics, epigenomics, or metabolomics. This review aims to summarize the current state of toxicogenomic approaches in risk science and to compare them with established ones. For example, measurement of global transcriptional changes generates meaningful information for toxicological risk assessment such as accurate classification of genotoxic/non-genotoxic carcinogens. Alteration in mRNA expression offers previously unknown insights in the mode of action and enables the definition of key events. Based on these, benchmark doses can be calculated for the transition from an adaptive to an adverse state. In short, this review assesses the potential and challenges of transcriptomics and addresses the impact of other omics technologies on risk assessment in terms of hazard identification and dose-response assessment.

Effects of physical characteristics of carbon black on metabolic regulation in mice

Potential adverse effects of human exposure to carbon black (CB) have been reported, but limited knowledge regarding CB-regulated metabolism is currently available. To evaluate how physical parameters of CB influence metabolism, we investigated CB and diesel exhaust particles (DEPs) and attempted to relate various physical parameters, including the hydrodynamic diameter, zeta potential, and particle number concentrations, to lung energy metabolism in female BALB/c mice. A body weight increase was arrested by 3 months of exposure to CB of smaller-size fractions, which was negatively correlated with pyruvate in plasma. There were no significant differences in cytotoxic lactate dehydrogenase (LDH) or total protein in bronchoalveolar lavage fluid (BALF) after 3 months of CB exposure. However, we observed alterations in acetyl CoA and the NADP/NADPH ratio in lung tissues with CB exposure. Additionally, the NADP/NADPH ratio was associated with the zeta potential of CB. Mild peribronchiovascular and interstitial inflammation and multinucleated giant cells (macrophages) with a transparent and rhomboid appearance and containing foreign bodies were observed in lung sections. We suggest that physical characteristics of CB, such as the zeta potential, may disrupt metabolism after pulmonary exposure. These results, therefore, provide the first evidence of a link between pulmonary exposure to CB and metabolism.

Impact of biopersistent fibrous dusts on glycolysis, glutaminolysis and serine metabolism in A549 cells

The conversion rates of different metabolic pathways summarized as a metabolic signature mirror the physiological functions and the general physiological status of a cell. The present study compared the impact of crocidolite and chrysotile asbestos, glass fibers and multi‑walled carbon nanotubes (MWCN) of two different lengths (1‑2 µm and 5‑15 µm) on the conversion rates in glycolysis, glutaminolysis and serine metabolism of A549 cells. The concentration tested was 1 µg/cm2 for all fibers. A concentration of 5 µg/cm2 was additionally used for chrysotile and crocidolite, and 25 µg/cm2 for glass fibers and MWCN. With respect to the inhibitory effect on cell proliferation and the extent of metabolic alterations, the present study revealed the following ranking among the fibers tested: Chrysotile>crocidolite>glass fibers>MWCN 5‑15 µm>MWCN 1‑2 µm. For the asbestos and glass fibers this ranking correlated best with the number of fibers. It appeared that the results observed for MWCN did not match this correlation. However, electron microscopy revealed an agglomeration of MWCN. The agglomeration decreased the toxicologically relevant number of fibers by forming larger particle‑like shapes and explained the smaller effects of MWCN 5‑15 µm and 1‑2 µm on cell proliferation and metabolism.

Co-exposure to amorphous silica nanoparticles and benzo[a]pyrene at low level in human bronchial epithelial BEAS-2B cells

Both ultrafine particles (UFP) and polycyclic aromatic hydrocarbons (PAHs) are widely present in the environment, thus increasing their chances of exposure to human in the daily life. However, the study on the combined toxicity of UFP and PAHs on respiratory system is still limited. In this study, we examined the potential interactive effects of silica nanoparticles (SiNPs) and benzo[a]pyrene (B[a]P) in bronchial epithelial cells (BEAS-2B). Cells were exposed to SiNPs and B[a]P alone or in combination for 24 h. Co-exposure to SiNPs and B[a]P enhanced the malondialdehyde (MDA) contents and reduced superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities significantly, while the reactive oxygen species (ROS) generation had a slight increase in the exposed groups compared to the control but not statistically significant. Cell cycle arrest induced by the co-exposure showed a significant percentage increase in G2/M phase cells and a decrease in G0/G1 phase cells. In addition, there was a significant increase in BEAS-2B cells multinucleation as well as DNA damage. Cellular apoptosis was markedly increased even at the low-level co-exposure. Our results suggest that co-exposure to SiNPs and B[a]P exerts synergistic and additive cytotoxic and genotoxic effects.

Combined toxicity of silica nanoparticles and methylmercury on cardiovascular system in zebrafish (Danio rerio) embryos

This study was to investigate the combined toxicity of silica nanoparticles (SiNPs) and methylmercury (MeHg) on cardiovascular system in zebrafish (Danio rerio) embryos. Ultraviolet absorption analysis showed that the co-exposure system had high absorption and stability. The dosages used in this study were based on the NOAEL level. Zebrafish embryos exposed to the co-exposure of SiNPs and MeHg did not show any cardiovascular malformation or atrioventricular block, but had an inhibition effect on bradycardia. Using o-Dianisidine for erythrocyte staining, the cardiac output of zebrafish embryos was decreased gradually in SiNPs, MeHg, co-exposure groups, respectively. Co-exposure of SiNPs and MeHg enhanced the vascular endothelial damage in Tg(fli-1:EGFP) transgenic zebrafish line. Moreover, the co-exposure significantly activated the oxidative stress and inflammatory response in neutrophils-specific Tg(mpo:GFP) transgenic zebrafish line. This study suggested that the combined toxic effects of SiNPs and MeHg on cardiovascular system had more severe toxicity than the single exposure alone.

Inflammatory response and blood hypercoagulable state induced by low level co-exposure with silica nanoparticles and benzo[a]pyrene in zebrafish (Danio rerio) embryos

Given the severe situation of world-wide particulate matter air pollution, it is urgent to explore the combined effects of particulate matter components on cardiovascular system. Using zebrafish model, this study was aimed to determine whether the low level co-exposure to silica nanoparticles (SiNPs) and benzo[a]pyrene (B[a]P) had a pronounced cardiovascular toxicity than the single exposure to either SiNPs or B[a]P alone. The FTIR and TGA analysis showed that the co-exposure system possessed of high absorption and thermal stability. Embryos exposed to SiNPs or B[a]P alone did not show cardiac toxicity phenotype at the NOAEL level. However, embryos co-exposed to SiNPs and B[a]P exhibited pericardial edema and bradycardia. While ROS generation remained unaffected, the co-exposure induced significant neutrophil-mediated inflammation and caused erythrocyte aggregation in caudal vein of embryos. Microarray analysis and STC analysis were performed to screen the cardiovascular-related differential expression genes and the expression trend of genes in each group. The co-exposure of SiNPs and B[a]P significantly enhanced the expression of proinflammatory and procoagulant genes. Moreover, the co-exposure markedly increased the phosphorylated AP-1/c-Jun and induced TF expression, but not NF-κB p65. This study for the first time demonstrated the inflammatory response and blood hypercoagulable state were triggered by the combination of SiNPs and B[a]P at low level exposure.