Epigenetic effects of nano-sized materials

The transcriptomic signature of respiratory sensitizers using an alveolar model

Environmental contaminants are ubiquitous in the air we breathe and can potentially cause adverse immunological outcomes such as respiratory sensitization, a type of immune-driven allergic response in the lungs. Wood dust, latex, pet dander, oils, fragrances, paints, and glues have all been implicated as possible respiratory sensitizers. With the increased incidence of exposure to chemical mixtures and the rapid production of novel materials, it is paramount that testing regimes accounting for sensitization are incorporated into development cycles. However, no validated assay exists that is universally accepted to measure a substance's respiratory sensitizing potential. The lungs comprise various cell types and regions where sensitization can occur, with the gas-exchange interface being especially important due to implications for overall lung function. As such, an assay that can mimic the alveolar compartment and assess sensitization would be an important advance for inhalation toxicology. Some such models are under development, but in-depth transcriptomic analyses have yet to be reported. Understanding the transcriptome after sensitizer exposure would greatly advance hazard assessment and sustainability. We tested two known sensitizers (i.e., isophorone diisocyanate and ethylenediamine) and two known non-sensitizers (i.e., chlorobenzene and dimethylformamide). RNA sequencing was performed in our in vitro alveolar model, consisting of a 3D co-culture of epithelial, macrophage, and dendritic cells. Sensitizers were readily distinguishable from non-sensitizers by principal component analysis. However, few differentially regulated genes were common across all pair-wise comparisons (i.e., upregulation of genes SOX9, UACA, CCDC88A, FOSL1, KIF20B). While the model utilized in this study can differentiate the sensitizers from the non-sensitizers tested, further studies will be required to robustly identify critical pathways inducing respiratory sensitization.

Nanoparticles-induced potential toxicity on human health: Applications, toxicity mechanisms, and evaluation models

Nanoparticles (NPs) have become one of the most popular objects of scientific study during the past decades. However, despite wealth of study reports, still there is a gap, particularly in health toxicology studies, underlying mechanisms, and related evaluation models to deeply understanding the NPs risk effects. In this review, we first present a comprehensive landscape of the applications of NPs on health, especially addressing the role of NPs in medical diagnosis, therapy. Then, the toxicity of NPs on health systems is introduced. We describe in detail the effects of NPs on various systems, including respiratory, nervous, endocrine, immune, and reproductive systems, and the carcinogenicity of NPs. Furthermore, we unravels the underlying mechanisms of NPs including ROS accumulation, mitochondrial damage, inflammatory reaction, apoptosis, DNA damage, cell cycle, and epigenetic regulation. In addition, the classical study models such as cell lines and mice and the emerging models such as 3D organoids used for evaluating the toxicity or scientific study are both introduced. Overall, this review presents a critical summary and evaluation of the state of understanding of NPs, giving readers more better understanding of the NPs toxicology to remedy key gaps in knowledge and techniques.

An In Vitro Alveolar Model Allows for the Rapid Assessment of Particles for Respiratory Sensitization Potential

Dust, both industrial and household, contains particulates that can reach the most distal aspects of the lung. Silica and nickel compounds are two such particulates and have known profiles of poor health outcomes. While silica is well-characterized, nickel compounds still need to be fully understood for their potential to cause long-term immune responses in the lungs. To assess these hazards and decrease animal numbers used in testing, investigations that lead to verifiable in vitro methods are needed. To understand the implications of these two compounds reaching the distal aspect of the lungs, the alveoli, an architecturally relevant alveolar model consisting of epithelial cells, macrophages, and dendritic cells in a maintained submerged system, was utilized for high throughput testing. Exposures include crystalline silica (SiO₂) and nickel oxide (NiO). The endpoints measured included mitochondrial reactive oxygen species and cytostructural changes assessed via confocal laser scanning microscopy; cell morphology evaluated via scanning electron microscopy; biochemical reactions assessed via protein arrays; transcriptome assessed via gene arrays, and cell surface activation markers evaluated via flow cytometry. The results showed that, compared to untreated cultures, NiO increased markers for dendritic cell activation, trafficking, and antigen presentation; oxidative stress and cytoskeletal changes, and gene and cytokine expression of neutrophil and other leukocyte chemoattractants. The chemokines and cytokines CCL3, CCL7, CXCL5, IL-6, and IL-8 were identified as potential biomarkers of respiratory sensitization.

Immunotoxicity of metal and metal oxide nanoparticles: from toxic mechanisms to metabolism and outcomes

The influence of metal and metal oxide nanomaterials on various fields since their discovery has been remarkable. They have unique properties, and therefore, have been employed in specific applications, including biomedicine. However, their potential health risks cannot be ignored. Several studies have shown that exposure to metal and metal oxide nanoparticles can lead to immunotoxicity. Different types of metals and metal oxide nanoparticles may have a negative impact on the immune system through various mechanisms, such as inflammation, oxidative stress, autophagy, and apoptosis. As an essential factor in determining the function and fate of immune cells, immunometabolism may also be an essential target for these nanoparticles to exert immunotoxic effects in vivo. In addition, the biodegradation and metabolic outcomes of metal and metal oxide nanoparticles are also important considerations in assessing their immunotoxic effects. Herein, we focus on the cellular mechanism of the immunotoxic effects and toxic effects of different types of metal and metal oxide nanoparticles, as well as the metabolism and outcomes of these nanoparticles in vivo. Also, we discuss the relationship between the possible regulatory effect of nanoparticles on immunometabolism and their immunotoxic effects. Finally, we present perspectives on the future research and development direction of metal and metal oxide nanomaterials to promote scientific research on the health risks of nanomaterials and reduce their adverse effects on human health.

Gold nanoparticle intratesticular injections as a potential animal sterilization tool: Long-term reproductive and toxicological implications

This study aimed to evaluate the gold nanoparticles (AuNPs) animal sterilizing potential after intratesticular injections and long-term adverse reproductive and systemic effects. Adult male Wistar rats were divided into control and gold nanoparticle (AuNPs) groups. The rats received 200µL of saline or AuNPs solution (16µg/mL) on experimental days 1 and 7 (ED1 and ED7). After 150 days, the testicular blood flow was measured, and the rats were mated with females. After mating, male animals were euthanized for histological, cellular, and molecular evaluations. The female fertility indices and fetal development were also recorded. The results indicated increased blood flow in the testes of treated animals. Testes from treated rats had histological abnormalities, shorter seminiferous epithelia, and oxidative stress. Although the sperm concentration was lower in the AuNP-treated rats, there were no alterations in sperm morphology. Animals exposed to AuNPs had decreased male fertility indices, and their offspring had lighter and less efficient placentas. Additionally, the anogenital distance was longer in female fetuses. There were no changes in the histology of the kidney and liver, the lipid profile, and the serum levels of LH, testosterone, AST, ALT, ALP, albumin, and creatinine. The primary systemic effect was an increase in MDA levels in the liver and kidney, with only the liver experiencing an increase in CAT activity. In conclusion, AuNPs have a long-term impact on reproduction with very slight alterations in animal health. The development of reproductive biotechnologies that eliminate germ cells or treat local cancers can benefit from using AuNPs.

Seed nanopriming: How do nanomaterials improve seed tolerance to salinity and drought?

Salt and drought stress are major environmental issues world-widely. These stresses can result in failures of seed germination, limiting agricultural production. New approaches are needed to increase crop production, ensuring food safety, quality, and agriculture sustainability. Nanopriming (priming seeds with nanomaterials) is an emerging seed technology improving crop production under the drastic climate change associated with stress factors. The present review not only provided an overview of nanopriming achieved salt and drought tolerance but also tried to discuss the behind mechanisms. We argued that the physico-chemical properties of the nanomaterials are key factors affecting their negative or positive effects on seed germination in terms of seed nanopriming. Furthermore, we highlighted the possible critical role of seed coat anatomy in effective nanopriming, in terms of saving costs and reducing biosafety issues. This review aims to help researchers to better understand and follow this fast-developing, cost-effective, and environmentally friendly research area.

Advanced sanitation products infused with silver nanoparticles for viral protection and their ecological and environmental consequences

The outbreak of coronavirus ailments (COVID-19) in 2019 resulted in public health crisis leading to global pandemonium. In response to the high prevalence of disease transmission, governments all around the globe implemented emergency measures in various routes (e.g., social distancing, personal hygiene, and disinfection of public/private places) to curb/contain COVID-19 infections. The social media infodemic, released as uncensored publishing and/or views/recommendations, also triggered large-scale behavior changes such as the overuse of advanced sanitation products (ASPs) containing nanomaterials. The majority of these ASPs contain silver nanoparticles (AgNPs) as an active ingredient to enhance their antimicrobial potential. Ecotoxicological concerns such as the transformation and degradation of these AgNP-infused products in terrestrial or aquatic environments are under the jurisdiction of the EPA. However, they are not considered in the FDA approval process. In light of excessive consumption of ASPs, it is time to consider their ecotoxicological screening prior to market approval jointly by the FDA and EPA, along with the implementation of post-market surveillance strategies. At the same time, efforts should be put into running awareness programs to prevent the overuse of ASPs.

Nanomaterial-Augmented Formulation of Disinfectants and Antiseptics in Controlling SARS CoV-2

The worldwide COVID-19 pandemic has brought significant consideration toward innovative strategies for overcoming the viral spread. Nanotechnology will change our lives in several forms as its uses span from electronics to pharmaceutical procedures. The use of nanoparticles provides a possibility to promote new antiviral treatments with a low possibility of increasing drug resistance compared to typical chemical-based antiviral treatments. Since the long-term usage of disinfectants and antiseptics at high concentrations has deleterious impacts on well-being and the environment, this review was intended to discuss the antiviral activity of disinfectants and antiseptics required for their activity against respiratory viruses especially SARS-CoV-2. It could improve the inhibition of viral penetration into cells, solvation of the lipid bilayer envelope, and ROS production, therefore enhancing the effect of disinfectants. However, significant concerns about nanomaterial's hazardous effects on individuals and the environment are increasing as nanotechnology flourishes. In this review, we first discuss the significant and essential types of nanomaterials, especially silver and copper, that could be used as antiviral agents and their viral entry mechanisms into host cells. Further, we consider the toxicity on health, and environmental concerns of nanoparticles. Eventually, we present our outlook on the fate of nanomaterials toward viral diseases.

Epigenetic effects of graphene oxide and its derivatives: A mini-review

Graphene oxide (GO), an engineered nanomaterial, has a two-dimensional structure with carbon atoms arranged in a hexagonal array. While it has been widely used in many industries, such as biomedicine, electronics, and biosensors, there are still concerns over its safety. Recently, many studies have focused on the potential toxicity of GO. Epigenetic toxicity is an important aspect of a material's toxicological profile, since changes in gene expression have been associated with carcinogenicity and disease progression. In this review, we focus on the epigenetic alterations caused by GO, including DNA methylation, histone modification, and altered expression of non-coding RNAs. GO can affect DNA methyltransferase activity and disrupt the methylation of cytosine bases in DNA strands, leading to alteration of genome expression. Modulation of histones by GO, targeting histone deacetylase and demethylase, as well as dysregulation of miRNA and lncRNA expression have been reported. Further studies are required to determine the mechanisms of GO-induced epigenetic alterations.

Nanoparticle-Based Modification of the DNA Methylome: A Therapeutic Tool for Atherosclerosis?

Cardiovascular epigenomics is a relatively young field of research, yet it is providing novel insights into gene regulation in the atherosclerotic arterial wall. That information is already pointing to new avenues for atherosclerosis (AS) prevention and therapy. In parallel, advances in nanoparticle (NP) technology allow effective targeting of drugs and bioactive molecules to the vascular wall. The partnership of NP technology and epigenetics in AS is just beginning and promises to produce novel exciting candidate treatments. Here, we briefly discuss the most relevant recent advances in the two fields. We focus on AS and DNA methylation, as the DNA methylome of that condition is better understood in comparison with the rest of the cardiovascular disease field. In particular, we review the most recent advances in NP-based delivery systems and their use for DNA methylome modification in inflammation. We also address the promises of DNA methyltransferase inhibitors for prevention and therapy. Furthermore, we emphasize the unique challenges in designing therapies that target the cardiovascular epigenome. Lastly, we touch the issue of human exposure to industrial NPs and its impact on the epigenome as a reminder of the undesired effects that any NP-based therapy must avoid to be apt for secondary prevention of AS.

Mechanisms of immune response to inorganic nanoparticles and their degradation products

Careful assessment of the biological fate and immune response of inorganic nanoparticles is crucial for use of such carriers in drug delivery and other biomedical applications. Many studies have elucidated the cellular and molecular mechanisms of the interaction of inorganic nanoparticles with the components of the immune system. The biodegradation and dissolution of inorganic nanoparticles can influence their ensuing immune response. While the immunological properties of inorganic nanoparticles as a function of their physicochemical properties have been investigated in detail, little attention has been paid to the immune adverse effects towards the degradation products of these nanoparticles. To fill this gap, we herein summarize the cellular mechanisms of immune response to inorganic nanoparticles and their degradation products with specific focus on immune cells. We also accentuate the importance of designing new methods and instruments for the in situ characterization of inorganic nanoparticles in order to assess their safety as a result of degradation. This review further sheds light on factors that need to be considered in the design of safe and effective inorganic nanoparticles for use in delivery of bioactive and imaging agents.

Cellular and Molecular Mechanisms of Toxicity of Ingested Titanium Dioxide Nanomaterials

An exponential increase in products containing titanium dioxide nanomaterials (TiO2), in agriculture, food and feed industry, lead to increased oral exposure to these nanomaterials (NMs). Thus, the gastrointestinal tract (GIT) emerges as a possible route of exposure that may drive systemic exposure, if the intestinal barrier is surpassed. NMs have been suggested to produce adverse outcomes, such as genotoxic effects, that are associated with increased risk of cancer, leading to a concern for public health. However, to date, the differences in the physicochemical characteristics of the NMs studied and other variables in the test systems have generated contradictory results in the literature. Processes like human digestion may change the NMs characteristics, inducing unexpected toxic effects in the intestine. Using TiO2 as case-study, this chapter provides a review of the works addressing the interactions of NMs with biological systems in the context of intestinal tract and digestion processes, at cellular and molecular level. The knowledge gaps identified suggest that the incorporation of a simulated digestion process for in vitro studies has the potential to improve the model for elucidating key events elicited by these NMs, advancing the nanosafety studies towards the development of an adverse outcome pathway for intestinal effects.

Selective cytotoxicity mechanisms and biodistribution of diamond nanoparticles on the skin cancer in C57 mouse

The cytotoxicity of diamond nanoparticles (DNs) to various cell lines has been on focus by numerous scientists. The cellular toxicity system of DNs has not been fully understood or explained in skin cancer, at this point. This research was carried out to discover and reveal the potential impacts of DNs on the secluded brain, heart, liver, kidney, and skin in addition to evaluation of their cytotoxicity mechanism under test conditions. Their biological activities, for example cell viability, the level of reactive oxygen species (ROS), lipid peroxidation, cytochrome c release and Apoptosis/Necrosis were evaluated. Additionally, the bio-distribution of these nanomaterials in tissues was examined in the C57 mouse. Relying on the findings of the investigation, DNs were found to increase the ROS level, Malondialdehyde (MDA) content, release of cytochrome c, and cell death in skin significantly compared to other groups. In the C57 mouse, DNs were observed to have accumulated in skin tissue more intensively than they did in other organs. The present study presents for the proof that DNs can completely induce cell death signaling in skin cancer without bringing about a high cytotoxicity in other tissues. Results suggest that DNs can be valuable in recognition of skin cancer.

Identification of DNA methylation by novel optical genosensing: A new platform in epigenetic study using biomedical analysis

Due to the important role of methylation in cancer, the use of sensitive analytical methods for early diagnosis and efficient clinical pharmacotherapy is highly demanded. In this study, an innovative label-free method has been developed for the recognition of methylated DNA in the promoter area of adenomatous polyposis coli gene (APC gene). Also, differentiation of unmethylated DNA (GCGGAGTGCGGGTCGGGAAGCGGA) from methylated cDNA (GC(M)GGAGTGC(M)GGGTC(M)GGGAAGC(M)GGA) was performed using optical synthesized probe (thionine-based polymer). Hybridization of pDNA (TCCGCTTCCCGACCCGCACTCCGC) with various types of cDNA sequences was studied by UV-visible and fluorescence spectroscopy. Also, some of the mismatch sequences {(GC(M)GGAGTAC(M)GGGTC(M)GGGAAGC(M)GGA) and (GCGGAGTACGGGTCGGGAAGCGGA)} were applied as negative control. For this purpose, The synthesized optical probe was characterized by transmission electron microscopy, atomic force microscopy, dynamic light scattering, zeta potential, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, UV-Vis, and fluorescence spectroscopy. Under optimal conditions, the analytical performance of engineered DNA-based assay was studied and exhibited excellent dynamic range (1 zM to 3 pM) with low limit of quantitation (LLOQ) of 1 zM. The designed DNA-based assay showed a high capability of discriminating methylation, unmethylated and mismatched sequences. The engineered genosensor is simple and inexpensive and can detect DNA methylation with high sensitivity. Therefore, the designed geno-assay could detect DNA methylation significantly and discriminate from unmethylated DNA. It is expected that the proposed geno-assay could be used for the detection of DNA methylation, genetic mutations, epigenetic alterations, and early stage diagnosis of various cancer toward efficient clinical pharmacotherapy.

Nanoparticles and trained immunity: Glimpse into the future

Emerging evidences show that innate immune cells can display changes in their functional programs after infection or vaccination, which lead to immunomodulation (increased or reduced responsiveness) upon secondary activation to the same stimuli or even to a different one. Innate cells acquire features of immunological memory, nowadays using the new term of "trained immunity" or "innate immune memory", which is different from the specific memory immune response elicited by B and T lymphocytes. The review focused on the concept of trained immunity, mostly on myeloid cells. Special attention is dedicated to the pathogen recognition along the evolution (bacteria, plants, invertebrate and vertebrate animals), and to techniques used to study epigenetic reprogramming and metabolic rewiring. Nanomaterials can be recognized by immune cells offering a very promising way to learn about trained immunity. Nanomaterials could be modified in order to immunomodulate the responses ad hoc. Many therapeutic possibilities are opened, and they should be explored.

Application of lateral flow and microfluidic bio-assay and biosensing towards identification of DNA-methylation and cancer detection: Recent progress and challenges in biomedicine

DNA methylation is an important epigenetic alteration that results from the covalent transfer of a methyl group to the fifth carbon of a cytosine residue in CpG dinucleotides by DNA methyltransferase. This modification mostly happens in the promoter region and the first exon of most genes and suppresses gene expression. Therefore, aberrant DNA methylation cause tumor progression, metastasis, and resistance to current anti-cancer therapies. So, the detection of DNA methylation is an important issue in diagnosis and therapy of most diseases. Conventional methods for the assay of DNA methylation and activity of DNA methyltransferases are time consuming. So, we need to multiplex operations and expensive instrumentation. To overcome the limitations of conventional methods, new methods such as microfluidic platforms and lateral flow tests have been developed to evaluate DNA methylation. The microfluidic tests are based on optical and electrical biosensing. These tests able us to can analyze DNA methylation with high efficiency and sensitivity without the need for expensive equipment and skilled people. Lateral flow strip tests are another type of rapid, simple, and sensitive test with advanced technology used to assess DNA methylation. Lateral flow strip tests are based on optical biosensors. This review attempts to evaluate new methods for assessing DNA extraction, DNA methylation and DNA methyltransferase activity as well as recent developments in microfluidic technology application for bisulfite treatment and restriction enzyme (bisulfite free), and lateral flow relying on their application in the field of recognition of DNA methylation in blood and body fluids. Also, the advantages and disadvantages of each test are reviewed. Finally, future prospects for the development of the microfluidics biodevices for the detection of DNA methylation is briefly discussed.

Effects of metal nanoparticles on tight junction-associated proteins via HIF-1α/miR-29b/MMPs pathway in human epidermal keratinocytes

Background

The increasing use of metal nanoparticles in industry and biomedicine raises the risk for unintentional exposure. The ability of metal nanoparticles to penetrate the skin ranges from stopping at the stratum corneum to passing below the dermis and entering the systemic circulation. Despite the potential health risks associated with skin exposure to metal nanoparticles, the mechanisms underlying the toxicity of metal nanoparticles on skin keratinocytes remain unclear. In this study, we proposed that exposure of human epidermal keratinocytes (HaCaT) to metal nanoparticles, such as nickel nanoparticles, dysregulates tight-junction associated proteins by interacting with the HIF-1α/miR-29b/MMPs axis.

Methods

We performed dose-response and time-response studies in HaCaT cells to observe the effects of Nano-Ni or Nano-TiO₂ on the expression and activity of MMP-2 and MMP-9, and on the expression of tight junction-associated proteins, TIMP-1, TIMP-2, miR-29b, and HIF-1α. In the dose-response studies, cells were exposed to 0, 10, or 20 μg/mL of Nano-Ni or Nano-TiO₂ for 24 h. In the time-response studies, cells were exposed to 20 μg/mL of Nano-Ni for 12, 24, 48, or 72 h. After treatment, cells were collected to either assess the expression of mRNAs and miR-29b by real-time PCR or to determine the expression of tight junction-associated proteins and HIF-1α nuclear accumulation by Western blot and/or immunofluorescent staining; the conditioned media were collected to evaluate the MMP-2 and MMP-9 activities by gelatin zymography assay. To further investigate the mechanisms underlying Nano-Ni-induced dysregulation of tight junction-associated proteins, we employed a HIF-1α inhibitor, CAY10585, to perturb HIF-1α accumulation in one experiment, and transfected a miR-29b-3p mimic into the HaCaT cells before Nano-Ni exposure in another experiment. Cells and conditioned media were collected, and the expression and activities of MMPs and the expression of tight junction-associated proteins were determined as described above.

Results

Exposure of HaCaT cells to Nano-Ni resulted in a dose-dependent increase in the expression of MMP-2, MMP-9, TIMP-1, and TIMP-2 and the activities of MMP-2 and MMP-9. However, exposure of cells to Nano-TiO₂ did not cause these effects. Nano-Ni caused a dose-dependent decrease in the expression of miR-29b and tight junction-associated proteins, such as ZO-1, occludin, and claudin-1, while Nano-TiO₂ did not. Nano-Ni also caused a dose-dependent increase in HIF-1α nuclear accumulation. The time-response studies showed that Nano-Ni caused significantly increased expressions of MMP-2 at 24 h, MMP-9 at 12, 24, and 48 h, TIMP-1 from 24 to 72 h, and TIMP-2 from 12 to 72 h post-exposure. The expression of miR-29b and tight junction-associated proteins such as ZO-1, occludin, and claudin-1 decreased as early as 12 h post-exposure, and their levels declined gradually over time. Pretreatment of cells with a HIF-1α inhibitor, CAY10585, abolished Nano-Ni-induced miR-29b down-regulation and MMP-2/9 up-regulation. Introduction of a miR-29b-3p mimic into HaCaT cells by transfection before Nano-Ni exposure ameliorated Nano-Ni-induced increased expression and activity of MMP-2 and MMP-9 and restored Nano-Ni-induced down-regulation of tight junction-associated proteins.

Conclusion

Our study herein demonstrated that exposure of human epidermal keratinocytes to Nano-Ni caused increased HIF-1α nuclear accumulation and increased transcription and activity of MMP-2 and MMP-9 and down-regulation of miR-29b and tight junction-associated proteins. Nano-Ni-induced miR-29b down-regulation was through Nano-Ni-induced HIF-1α nuclear accumulation. Restoration of miR-29b level by miR-29b-3p mimic transfection abolished Nano-Ni-induced MMP-2 and MMP-9 activation and down-regulation of tight junction-associated proteins. In summary, our results demonstrated that Nano-Ni-induced dysregulation of tight junction-associated proteins in skin keratinocytes was via HIF-1α/miR-29b/MMPs pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-021-00405-2.

Confirmatory assays for transient changes of omics in soil invertebrates - Copper materials in a multigenerational exposure

Environmental risk assessment (ERA) based on effects caused by chronic and longer term exposure is highly relevant. Further, if mechanistic based approaches (e.g. omics) can be included, beyond apical endpoints (e.g. reproduction), the prediction of effects increases. For Cu NMs (and CuCl₂) this has been studied in detail, covering multi-omics and apical effects using the soil standard species Enchytraeus crypticus. The intermediate level effects like cell/tissue and organ alterations represent a missing link. In the present study we aimed to: 1) perform long term exposure to Cu materials (full life cycle and multigeneration, 46 and 224 days) to collect samples; 2) perform histology and immunohistochemistry on collected samples at 12 time points and 17 treatments; 3) integrate all levels of biological organization onto an adverse outcome pathway (AOP) framework. CuO NMs and CuCl₂ caused both similar and different stress response, either at molecular initiating events (MIE) or key events (KEs) of higher level of biological organization. Cell/Tissue and organ level, post-transcriptional and transcriptional mechanisms, through histone modifications and microRNA related protein, were similarly affected. While both Cu forms affected the Notch signalling pathway, CuCl₂ also caused oxidative stress. Different mechanisms of DNA methylation (epigenetics) were activated by CuO NMs and CuCl₂ at the MIE.

Safe Nanoparticles: Are We There Yet?

The field of nanotechnology has grown over the last two decades and made the transition from the benchtop to applied technologies. Nanoscale-sized particles, or nanoparticles, have emerged as promising tools with broad applications in drug delivery, diagnostics, cosmetics and several other biological and non-biological areas. These advances lead to questions about nanoparticle safety. Despite considerable efforts to understand the toxicity and safety of these nanoparticles, many of these questions are not yet fully answered. Nevertheless, these efforts have identified several approaches to minimize and prevent nanoparticle toxicity to promote safer nanotechnology. This review summarizes our current knowledge on nanoparticles, their toxic effects, their interactions with mammalian cells and finally current approaches to minimizing their toxicity.

Epigenetics in Breast Cancer Therapy-New Strategies and Future Nanomedicine Perspectives

Epigenetic dysregulation has been recognized as a critical factor contributing to the development of resistance against standard chemotherapy and to breast cancer progression via epithelial-to-mesenchymal transition. Although the efficacy of the first-generation epigenetic drugs (epi-drugs) in solid tumor management has been disappointing, there is an increasing body of evidence showing that epigenome modulation, in synergy with other therapeutic approaches, could play an important role in cancer treatment, reversing acquired therapy resistance. However, the epigenetic therapy of solid malignancies is not straightforward. The emergence of nanotechnologies applied to medicine has brought new opportunities to advance the targeted delivery of epi-drugs while improving their stability and solubility, and minimizing off-target effects. Furthermore, the omics technologies, as powerful molecular epidemiology screening tools, enable new diagnostic and prognostic epigenetic biomarker identification, allowing for patient stratification and tailored management. In combination with new-generation epi-drugs, nanomedicine can help to overcome low therapeutic efficacy in treatment-resistant tumors. This review provides an overview of ongoing clinical trials focusing on combination therapies employing epi-drugs for breast cancer treatment and summarizes the latest nano-based targeted delivery approaches for epi-drugs. Moreover, it highlights the current limitations and obstacles associated with applying these experimental strategies in the clinics.

Carbon nanotubes affect early growth, flowering time and phytohormones in tomato

Carbon nanotube (CNT) applications are increasing in consumer products, including agriculture devices, making them an important contaminant to study in the field of plant nanotoxicology. Several studies have observed the uptake and effects of CNTs in plants. However, in other studies differing results were observed on growth and physiology depending on the plant species and type of CNT. This study focused on the effects of CNTs on plant phenotype with growth, time to flowering, fruiting time as endpoints, and physiology, through amino acid and phytohormone content, in tomato after exposure to multiple types of CNTs. Plants grown in CNT-contaminated soil exhibited a delay in early growth and flowering (especially in treatments of 1 mg/kg multi-walled nanotubes (MWNTs), 10 mg/kg MWNTs, and 1 mg/kg MWNTs-COOH). However, CNTs did not affect plant growth or height later in the life cycle. No significant differences in abscisic acid (ABA) and citrulline content were observed between the treated and control plants. However, single-walled nanotube (SWNT) exposure significantly increased salicylic acid (SA) content in tomato. These results suggest that SWNTs may elicit a stress response in tomatoes. Results from this study offer more insight into how plants respond and acclimate to CNTs. These results will lead to a better understanding of CNT impact on plant phenotype and physiology.

Genotoxicity of Nanomaterials: Advanced In Vitro Models and High Throughput Methods for Human Hazard Assessment-A Review

Changes in the genetic material can lead to serious human health defects, as mutations in somatic cells may cause cancer and can contribute to other chronic diseases. Genotoxic events can appear at both the DNA, chromosomal or (during mitosis) whole genome level. The study of mechanisms leading to genotoxicity is crucially important, as well as the detection of potentially genotoxic compounds. We consider the current state of the art and describe here the main endpoints applied in standard human in vitro models as well as new advanced 3D models that are closer to the in vivo situation. We performed a literature review of in vitro studies published from 2000-2020 (August) dedicated to the genotoxicity of nanomaterials (NMs) in new models. Methods suitable for detection of genotoxicity of NMs will be presented with a focus on advances in miniaturization, organ-on-a-chip and high throughput methods.

Effect of titanium dioxide nanoparticles on DNA methylation in multiple human cell lines

Nanoscale titanium dioxide (TiO2) is manufactured in wide scale, with a range of applications in consumer products. Significant toxicity of TiO2 nanoparticles has, however, been recognized, suggesting considerable risk to human health. To evaluate fully their toxicity, assessment of the epigenetic action of these nanoparticles is critical. However, only few studies are available examining capability of nanoparticles to alter epigenetic integrity. In the present study, the effect of TiO2 nanoparticles exposure on DNA methylation, a major epigenetic mechanism, was investigated in in vitro cellular model systems. A panel of cells relevant to portals of human exposure (Caco-2 (colorectal), HepG2 (liver), NL20 (lung), and A-431 (skin)) was exposed to TiO2 nanoparticles to assess effects on global methylation, gene-specific methylation, and expression levels of DNA methyltransferases, MBD2, and UHRF1. Global methylation was determined by enzyme-linked immunosorbent assay-based immunochemical analysis. Degree of promoter methylation across a defined panel of genes was evaluated using EpiTect Methyl II Signature PCR System Array technology. Expression of DNMT1, DNMT3a, DNMT3b, MBD2, and URHF1 was quantified by qRT-PCR. Decrease in global DNA methylation in cell lines Caco-2, HepG2, and A-431 exposed to TiO2 nanoparticles was shown. Across four cell lines, eight genes (CDKN1A, DNAJC15, GADD45A, GDF15, INSIG1, SCARA3, TP53, and BNIP3) were identified in which promotors were methylated after exposure. Altered expression of these genes is associated with disease etiology. The results also revealed aberrant expression of epigenetic regulatory genes involved in DNA methylation (DNMT1, DNMT3a, DNMT3b, MBD2, and UHRF1) in TiO2 exposed cells, which was cell type dependent. Findings from this study clearly demonstrate the impact of TiO2 nanoparticles exposure on DNA methylation in multiple cell types, supporting potential involvement of this epigenetic mechanism in the toxicity of TiO2 nanoparticles. Hence for complete assessment of potential risk from nanoparticle exposure, epigenetic studies are critical.

Multigenerational Exposure to WCCo Nanomaterials-Epigenetics in the Soil Invertebrate Enchytraeus crypticus

It has become clear how important it is to assess longer term effects of (nano) materials in the environment given the current evidence showing how epigenetics drives response mechanisms. Here we studied global DNA methylation in standard soil invertebrate Enchytraeus crypticus over 224 days when exposed to nanostructured tungsten carbide cobalt (WCCo nanomaterials (NMs)) and to cobalt (CoCl₂) in a multigenerational experiment. In order to assess the transgenerational effect, we used a multigenerational (MG) test design consisting of four generations in spiked soil followed by two generations in clean soil. Results showed that MG exposure to WCCo NMs caused global DNA methylation to increase, which continued in unexposed generations and was associated with an increase in reproduction (phenotypic effect). In general, WCCo NMs caused more (and more consistent) methylation than CoCl₂.

Functional effects of differentially expressed microRNAs in A549 cells exposed to MWCNT-7 or crocidolite

Multi-walled carbon nanotubes (MWCNT) are engineered nanomaterials widely used in industrial and biomedical applications. Yet, MWCNT inhalation may induce pulmonary adverse effects, and the MWCNT-7 (Mitsui-7) has been classified as possibly carcinogenic to humans. However, its molecular mechanisms of action are poorly understood and there are no biomarkers of exposure for occupational monitoring. Several pulmonary diseases, including lung cancer, have been associated with alterations in microRNA expression that are used as biomarkers of disease progression, and differentially-expressed microRNAs (DE miRNAs) can also allow understanding the molecular effects induced by a toxicant. In this study, we identify DE miRNAs in A549 alveolar epithelial cells following 24 h exposure to MWCNT-7 or crocidolite, as well as their enriched cellular functional pathways. These indicate that both materials change cell survival, differentiation and proliferative properties under the influence of AMPK, FoxO, TGF-β and Hippo pathways, and their metabolic activity and cell-to-cell communication. In addition, MWCNT-7 affects the actin cytoskeleton, ubiquitin mediated proteolysis, and ECM-receptor interactions; crocidolite the PI3K-Akt and mTOR pathways, endocytosis, and central carbon metabolism. Since deregulation of these pathways may be related to carcinogenesis, an interaction network of DE miRNAs and corresponding target cancer-related genes was constructed, highlighting the carcinogenic potential of Mitsui-7.

Epigenetic effects of (nano)materials in environmental species - Cu case study in Enchytraeus crypticus

Chemical stressors can induce epigenomic changes, i.e., changes that are transferred to the next generation, even when the stressor is removed. Literature on chemical induced epigenetic effects in environmental species is scarce. We here provide the first results on epigenetic effects caused by nanomaterials with an environmental OECD standard soil model species Enchytraeus crypticus species. We assessed the epigenetic potential in terms of global DNA methylation, gene-specific methylation via bisulfite sequencing and MS-HRM (Methylation Sensitive - High Resolution Melting), and gene expression qPCR for genes involved in DNA methylation, histone modifications, non-coding RNA and stress response mechanisms). We have exposed E. crypticus in a multigenerational (MG) test design to Cu (copper oxide nanomaterials (CuO NMs) and copper salt (CuCl₂)). To link possible epigenetic effects to population changes, we used exposure concentrations (ECx) that caused a 10% and 50% reduction in the reproductive output (10% and 50% are the standards for regulatory Risk Assessment), the organisms were exposed for five consecutive generations (F1-F5) plus two generations after transferring to clean media (F5-F7), 7 generations in a total of 224 days. Results showed that MG exposure to Cu increased global DNA methylation and corresponded with phenotypic effects (reproduction). Gene expression analyses showed changes in the epigenetic, stress and detoxification gene targets, depending on the generation and Cu form, also occurring in post-exposure generations, hence indicative of transgenerational effects. There were in general clear differences between organisms exposed to different Cu-forms, hence indicate nanoparticulate-specific effects.

Multi-generational effects under single and pulse exposure scenarios in two monophyletic Daphnia species

Anthropogenic activities commonly relate to a set of diffuse and point contamination sources, from industrial, domestic or agricultural outputs, characterized by a chemical cocktail exposure and consequent disturbances of natural ecosystems. Different species may present different sensitivities to contaminants, even when phylogenetically close. This study used two monophyletic Daphnia species from tropical and temperate environments, Daphnia similis and Daphnia magna respectively, to evaluate the variation of their sensitivity to Pb (if any) and fitness during a multi-generational exposure and recovery. To accomplish that, standard acute immobilization tests were done on specific generations. Tests were carried out with exposures to 1) potassium dichromate (K₂Cr₂O₇) to evaluate organisms' sensitivity/fitness, 2) Pb, to monitor variation on Pb sensitivity and 3) the fungicide mancozeb, providing a pulse toxicity approach on generational Pb acclimated daphnids. Since growth is an important trait related to organisms' fitness, organisms' size measurements were also monitored. In addition, organisms were maintained under two different dietary regimes. Our results indicate no variation on daphnids sensitivity to K₂Cr₂O₇, except for D. similis from a recovery period under food restriction. However, a lower Pb sensitivity was seen for both species throughout generations. Both species also showed that under food restriction neonates' sizes were larger than those kept under regular food, while reproduction was considerably reduced. Food restriction also generated opposite outcomes on both species, such as D. magna epigenetic changes and D. similis phenotypic acclimation to Pb. Besides, D. magna pre-exposed to Pb presented lower sensitivity to mancozeb, while the contrary was shown by D. similis. This study indicates that daphnids are capable of acquiring a lower sensitivity to Pb across a long-term exposure, and that Pb pre-exposure can affect the sensitivity to other chemicals. Also, different patterns in multi-generational responses from monophyletic species (especially under oligotrophic media, common on natural habitats) acknowledge the use of representative or native species to assess the effect of contaminants, since monophyletic species can provide different toxicity outputs.

Epigenetic Aspects of Engineered Nanomaterials: Is the Collateral Damage Inevitable?

The extensive application of engineered nanomaterial (ENM) in various fields increases the possibilities of human exposure, thus imposing a huge risk of nanotoxicity. Hence, there is an urgent need for a detailed risk assessment of these ENMs in response to their toxicological profiling, predominantly in biomedical and biosensor settings. Numerous "toxico-omics" studies have been conducted on ENMs, however, a specific "risk assessment paradigm" dealing with the epigenetic modulations in humans owing to the exposure of these modern-day toxicants has not been defined yet. This review aims to address the critical aspects that are currently preventing the formation of a suitable risk assessment approach for/against ENM exposure and pointing out those researches, which may help to develop and implement effective guidance for nano-risk assessment. Literature relating to physicochemical characterization and toxicological behavior of ENMs were analyzed, and exposure assessment strategies were explored in order to extrapolate opportunities, challenges, and criticisms in the establishment of a baseline for the risk assessment paradigm of ENMs exposure. Various challenges, such as uncertainty in the relation of the physicochemical properties and ENM toxicity, the complexity of the dose-response relationships resulting in difficulty in its extrapolation and measurement of ENM exposure levels emerged as issues in the establishment of a traditional risk assessment. Such an appropriate risk assessment approach will provide adequate estimates of ENM exposure risks and will serve as a guideline for appropriate risk communication and management strategies aiming for the protection and the safety of humans.

No genome-wide DNA methylation changes found associated with medium-term reduced graphene oxide exposure in human lung epithelial cells

The presence of nanomaterials in our everyday life is ever increasing, and so too are concerns about the possible health consequences of exposure to them. While evidence of their biological activity is growing, there is still scant knowledge of the epigenetic mechanisms that could be at play in these processes. Moreover, the great variability in the chemical and physical structures of these compounds handicaps the study of their possible health risks. Here we have synthesized reduced graphene oxide (rGO) through the thermal exfoliation/reduction of graphite oxide, and characterized the resulting material. We have then made use of Illumina's MethylationEPIC arrays and bisulphite pyrosequencing to analyse the genome-wide and global DNA methylation dynamics associated with the medium-term exposure of human lung epithelial cells to rGO at concentrations of 1 and 10 µg/mL. The results show no genome-wide or global DNA methylation changes associated with either condition. Our observations thus suggest that medium-term rGO exposure does not have significant effects on the DNA methylation patterns of human lung epithelial cells.

N-acetylcysteine reverses the decrease of DNA methylation status caused by engineered gold, silicon, and chitosan nanoparticles

Introduction: Engineered nanoparticles (ENPs) are one of the most widely used types of nanomaterials. Recently, ENPs have been shown to cause cellular damage by inducing ROS (reactive oxygen species) both directly and indirectly, leading to the changes in DNA methylation levels, which is an important epigenetic mechanism. In this study, we investigated the effect of ENP-induced ROS on DNA methylation.

Materials and methods: Human embryonic kidney and human keratinocyte (HaCaT) cells were exposed to three different types of ENPs: gold nanoparticles, silicon nanoparticles (SiNPs), and chitosan nanoparticles (CSNPs). We then evaluated the cytotoxicity of the ENPs by measuring cell viability, morphology, cell apoptosis, cell proliferation, cell cycle distribution and ROS levels. Global DNA methylation levels was measured using 5-methylcytosine immunocytochemical staining and HPLC analysis. DNA methylation levels of the transposable elements, long interspersed element-1 (LINE-1) and Alu, were also measured using combined bisulfite restriction analysis technique. DNA methylation levels of the TEs LINE-1 and Alu were also measured using combined bisulfite restriction analysis technique.

Results: We found that HaCaT cells that were exposed to SiNPs exhibited increased ROS levels, whereas HaCaT cells that were exposed to SiNPs and CSNPs experienced global and Alu hypomethylation, with no change in LINE-1 being observed in either cell line. The demethylation of Alu in HaCaT cells following exposure to SiNPs and CSNPs was prevented when the cells were pretreated with an antioxidant.

Conclusion: The global DNA methylation that is observed in cells exposed to ENPs is associated with methylation of the Alu elements. However, the change in DNA methylation levels following ENP exposure is specific to particular ENP and cell types and independent of ROS, being induced indirectly through disruption of the oxidative defense process.

Multi-generational exposure to Pb in two monophyletic Daphnia species: Individual, functional and population related endpoints

To better evaluate chemical damage in chronically contaminated habitats, a nine-generational exposure to Lead (Pb) was done with two monophyletic Daphnia species, from temperate (Daphnia magna) and tropical (Daphnia similis) environments. The multi-generational test consisted generally of a continuous Pb exposed set of organisms, plus an extra control set running simultaneously. To assess daphnids recovery after Pb exposure, some organisms from the sixth generation were transferred to clean media for three extra generations (recovery period; F6 to F9), while others were keep Pb exposed. All setups (control, Pb exposure and recovery period) were submitted to two different dietary regimes, the standard (3 × 10⁵ cells/mL) and restricted food (1.5 × 10⁵ cells/mL) regimes. To evaluate the effects of generational Pb exposure and food regimes, individual, functional and population related endpoints were assessed (number of offspring, body length and rate of population increase (r) and feeding rate (FR)). The tests were conducted on the first (F0) and last generations (F9). No differences were shown on number of offspring and feeding among F9 control and continuous Pb exposed D. magna, although a higher r was shown for F9 Pb exposed organisms. F9 Pb exposed D. similis also presented a higher r than F9 control, however, lethality was induced at high Pb exposure levels. At food restriction the patterns were opposite and D. magna died at high Pb exposure while Pb exposed D. similis was the only setup (compared to control and recovery period) to survive at high Pb exposure levels. Regarding the recovery period, D. magna (standard food) did not cope well with the Pb re-exposure and lethality was induced, while D. similis indicate a decreased Pb sensitivity (only setup that survived high Pb exposure levels). Under food restriction, both species presented a decreased Pb sensitivity and consequent failed recovery (possibly due to epigenetic changes). Both species presented similar patterns regarding generations. Organisms from F0 presented enhanced reproductive outputs in comparison to F9 and the contrary occurred to the FR (even in control organisms). Data show an acclimation under a generational Pb exposure, which could increase the population of adapted organisms in natural habitats. And, since there was not a full recovery after three generations in clean media, an indication of epigenetic changes for both species may also be considered.

Towards DNA methylation detection using biosensors

DNA methylation, a stable and heritable covalent modification which mostly occurs in the context of a CpG dinucleotide, has great potential as a biomarker to detect disease, provide prognoses and predict therapeutic responses. It can be detected in a quantitative manner by many different approaches both genome-wide and at specific gene loci, in various biological fluids such as urine, plasma, and serum, which can be obtained without invasive procedures. The current, classical methods are effective in studying DNA methylation patterns, however, for the most part; they have major drawbacks such as expensive instruments, complicated and time consuming protocols as well as relatively low sensitivity, and high false positive rates. To overcome these obstacles, great efforts have been made toward the development of reliable sensor devices to solve these limitations, providing sensitive, fast and cost-effective measurements. The use of biosensors for DNA methylation biomarkers has increased in recent years, because they are portable, simple, rapid, and inexpensive which offers a straightforward way to detect methylated biomarkers. In this review, we give an overview of the conventional techniques for the detection of DNA methylation and then will focus on recent advances in biosensor based methylation detection that eliminate bisulfite conversion and PCR amplification.

Toxicological status of nanoparticles: What we know and what we don't know

The field of nanotechnology has grown exponentially during the last few decades, due in part to the use of nanoparticles in many manufacturing processes, as well as their potential as clinical agents for treatment of diseases and for drug delivery. This has created several new avenues by which humans can be exposed to nanoparticles. Unfortunately, investigations assessing the toxicological impacts of nanoparticles (i.e. nanotoxicity), as well as their possible risks to human health and the environment, have not kept pace with the rapid rise in their use. This has created a gap-in-knowledge and a substantial need for more research. Studies are needed to help complete our understanding of the mechanisms of toxicity of nanoparticles, as well as the mechanisms mediating their distribution and accumulation in cells and tissues and their elimination from the body. This review summarizes our knowledge on nanoparticles, including their various applications, routes of exposure, their potential toxicity and risks to human health.

A Current Overview of the Biological and Cellular Effects of Nanosilver

Nanosilver plays an important role in nanoscience and nanotechnology, and is becoming increasingly used for applications in nanomedicine. Nanosilver ranges from 1 to 100 nanometers in diameter. Smaller particles more readily enter cells and interact with the cellular components. The exposure dose, particle size, coating, and aggregation state of the nanosilver, as well as the cell type or organism on which it is tested, are all large determining factors on the effect and potential toxicity of nanosilver. A high exposure dose to nanosilver alters the cellular stress responses and initiates cascades of signalling that can eventually trigger organelle autophagy and apoptosis. This review summarizes the current knowledge of the effects of nanosilver on cellular metabolic function and response to stress. Both the causative effects of nanosilver on oxidative stress, endoplasmic reticulum stress, and hypoxic stress—as well as the effects of nanosilver on the responses to such stresses—are outlined. The interactions and effects of nanosilver on cellular uptake, oxidative stress (reactive oxygen species), inflammation, hypoxic response, mitochondrial function, endoplasmic reticulum (ER) function and the unfolded protein response, autophagy and apoptosis, angiogenesis, epigenetics, genotoxicity, and cancer development and tumorigenesis—as well as other pathway alterations—are examined in this review.

RNA-sequencing reveals long-term effects of silver nanoparticles on human lung cells

Despite a considerable focus on the adverse effects of silver nanoparticles (AgNPs) in recent years, studies on the potential long-term effects of AgNPs are scarce. The aim of this study was to explore the effects of AgNPs following repeated low-dose, long-term exposure of human bronchial epithelial cells. To this end, the human BEAS-2B cell line was exposed to 1 µg/mL AgNPs (10 nm) for 6 weeks followed by RNA-sequencing (RNA-Seq) as well as genome-wide DNA methylation analysis. The transcriptomics analysis showed that a substantial number of genes (1717) were differentially expressed following AgNP exposure whereas only marginal effects on DNA methylation were observed. Downstream analysis of the transcriptomics data identified several affected pathways including the ‘fibrosis’ and ‘epithelial-mesenchymal transition’ (EMT) pathway. Subsequently, functional validation studies were performed using AgNPs of two different sizes (10 nm and 75 nm). Both NPs increased collagen deposition, indicative of fibrosis, and induced EMT, as evidenced by an increased invasion index, anchorage independent cell growth, as well as cadherin switching. In conclusion, using a combination of RNA-Seq and functional assays, our study revealed that repeated low-dose, long-term exposure of human BEAS-2B cells to AgNPs is pro-fibrotic, induces EMT and cell transformation.

Multigenerational exposure to silver ions and silver nanoparticles reveals heightened sensitivity and epigenetic memory in Caenorhabditis elegans

The effects from multigenerational exposures to engineered nanoparticles (ENPs) in their pristine and transformed states are currently unknown despite such exposures being an increasingly common scenario in natural environments. Here, we examine how exposure over 10 generations affects the sensitivity of the nematode Caenorhabditis elegans to pristine and sulfidized Ag ENPs and AgNO3 We also include populations that were initially exposed over six generations but kept unexposed for subsequent four generations to allow recovery from exposure. Toxicity of the different silver forms decreased in the order AgNO3, Ag ENPs and Ag2S ENPs. Continuous exposure to Ag ENPs and AgNO3 caused pronounced sensitization (approx. 10-fold) in the F2 generation, which was sustained until F10. This sensitization was less pronounced for Ag2S ENP exposures, indicating different toxicity mechanisms. Subtle changes in size and lifespan were also measured. In the recovery populations, the sensitivity to Ag ENPs and AgNO3 resulting from the initial multigenerational exposure persisted. Their response sensitivity for all endpoints was most closely related to the last ancestral exposed generation (F5), rather than unexposed controls. The mechanisms of transgenerational transfer of sensitivity are probably organized through the epigenome, and we encourage others to investigate such effects as a priority for mechanistic toxicology.

Epigenetic changes in the early stage of silica-induced cell transformation

The increasing use of nanomaterials in numerous domains has led to growing concern about their potential toxicological properties, and the potential risk to human health posed by silica nanoparticles remains under debate. Recent studies proposed that these particles could alter gene expression through the modulation of epigenetic marks, and the possible relationship between particle exposure and these mechanisms could represent a critical factor in carcinogenicity. In this study, using the Bhas 42 cell model, we compare the effects of exposure to two transforming particles, a pyrogenic amorphous silica nanoparticle NM-203 to those of the crystalline silica particle Min-U-Sil® 5. Short-term treatment by Min-U-Sil® 5 decreased global DNA methylation and increased the expression of the two de novo DNMTs, DNMT3a and DNMT3b. NM-203 treatment affected neither the expression of these enzymes nor DNA methylation. Moreover, modified global histone H4 acetylation status and HDAC protein levels were observed only in the Min-U-Sil® 5-treated cells. Finally, both types of particle treatment induced strong c-Myc expression in the early stage of cell transformation and this correlated with enrichment in RNA polymerase II as well as histone active marks on its promoter. Lastly, almost all parameters that were modulated in the early stage were restored in transformed cells suggesting their involvement mainly in the first steps of cell transformation.

Nanomedicine and epigenome. Possible health risks

Nanomedicine is an emerging field that combines knowledge of nanotechnology and material science with pharmaceutical and biomedical sciences, aiming to develop nanodrugs with increased efficacy and safety. Compared to conventional therapeutics, nanodrugs manifest higher stability and circulation time, reduced toxicity and improved targeted delivery. Despite the obvious benefit, the accumulation of imaging agents and nanocarriers in the body following their therapeutic or diagnostic application generates concerns about their safety for human health. Numerous toxicology studies have demonstrated that exposure to nanomaterials (NMs) might pose serious risks to humans. Epigenetic modifications, representing a non-genotoxic mechanism of toxicant-induced health effects, are becoming recognized as playing a potential causative role in the aetiology of many diseases including cancer. This review i) provides an overview of recent advances in medical applications of NMs and ii) summarizes current evidence on their possible epigenetic toxicity. To discern potential health risks of NMs, since current data are mostly based upon in vitro and animal models, a better understanding of functional relationships between NM exposure, epigenetic deregulation and phenotype is required.