Silica nanoparticles induce endoplasmic reticulum stress response, oxidative stress and activate the mitogen-activated protein kinase (MAPK) signaling pathway

Selenium Nanoparticles as Neuroprotective Agents: Insights into Molecular Mechanisms for Parkinson's Disease Treatment

Oxidative stress and the accumulation of misfolded proteins in the brain are the main causes of Parkinson's disease (PD). Several nanoparticles have been used as therapeutics for PD. Despite their therapeutic potential, these nanoparticles induce multiple stresses upon entry. Selenium (Se), an essential nutrient in the human body, helps in DNA formation, stress control, and cell protection from damage and infections. It can also regulate thyroid hormone metabolism, reduce brain damage, boost immunity, and promote reproductive health. Selenium nanoparticles (Se-NPs), a bioactive substance, have been employed as treatments in several disciplines, particularly as antioxidants. Se-NP, whether functionalized or not, can protect mitochondria by enhancing levels of reactive oxygen species (ROS) scavenging enzymes in the brain. They can also promote dopamine synthesis. By inhibiting the aggregation of tau, α-synuclein, and/or Aβ, they can reduce the cellular toxicities. The ability of the blood-brain barrier to absorb Se-NPs which maintain a healthy microenvironment is essential for brain homeostasis. This review focuses on stress-induced neurodegeneration and its critical control using Se-NP. Due to its ability to inhibit cellular stress and the pathophysiologies of PD, Se-NP is a promising neuroprotector with its anti-inflammatory, non-toxic, and antimicrobial properties.

Microplastics and Oxidative Stress-Current Problems and Prospects

Microplastics (MPs) are plastic particles between 0.1 and 5000 µm in size that have attracted considerable attention from the scientific community and the general public, as they threaten the environment. Microplastics contribute to various harmful effects, including lipid peroxidation, DNA damage, activation of mitogen-activated protein kinase pathways, cell membrane breakages, mitochondrial dysfunction, lysosomal defects, inflammation, and apoptosis. They affect cells, tissues, organs, and overall health, potentially contributing to conditions like cancer and cardiovascular disease. They pose a significant danger due to their widespread occurrence in food. In recent years, information has emerged indicating that MPs can cause oxidative stress (OS), a known factor in accelerating the aging of organisms. This comprehensive evaluation exposed notable variability in the reported connection between MPs and OS. This work aims to provide a critical review of whether the harmfulness of plastic particles that constitute environmental contaminants may result from OS through a comprehensive analysis of recent research and existing scientific literature, as well as an assessment of the characteristics of MPs causing OS. Additionally, the article covers the analytical methodology used in this field. The conclusions of this review point to the necessity for further research into the effects of MPs on OS.

Legacy and Emerging Plasticizers and Stabilizers in PVC Floorings and Implications for Recycling

Hazardous chemicals in building and construction plastics can lead to health risks due to indoor exposure and may contaminate recycled materials. We systematically sampled new polyvinyl chloride floorings on the Swiss market (n = 151). We performed elemental analysis by X-ray fluorescence, targeted and suspect gas chromatography-mass spectrometry analysis of ortho-phthalates and alternative plasticizers, and bioassay tests for cytotoxicity and oxidative stress, and endocrine, mutagenic, and genotoxic activities (for selected samples). Surprisingly, 16% of the samples contained regulated chemicals above 0.1 wt %, mainly lead and bis(2-ethylhexyl) phthalate (DEHP). Their presence is likely related to the use of recycled PVC in new flooring, highlighting that uncontrolled recycling can delay the phase-out of hazardous chemicals. Besides DEHP, 29% of the samples contained other ortho-phthalates (mainly diisononyl and diisodecyl phthalates, DiNP and DiDP) above 0.1 wt %, and 17% of the samples indicated a potential to cause biological effects. Considering some overlap between these groups, they together make up an additional 35% of the samples of potential concern. Moreover, both suspect screening and bioassay results indicate the presence of additional potentially hazardous substances. Overall, our study highlights the urgent need to accelerate the phase-out of hazardous substances, increase the transparency of chemical compositions in plastics to protect human and ecosystem health, and enable the transition to a safe and sustainable circular economy.

An ancestral molecular response to nanomaterial particulates

The varied transcriptomic response to nanoparticles has hampered the understanding of the mechanism of action. Here, by performing a meta-analysis of a large collection of transcriptomics data from various engineered nanoparticle exposure studies, we identify common patterns of gene regulation that impact the transcriptomic response. Analysis identifies deregulation of immune functions as a prominent response across different exposure studies. Looking at the promoter regions of these genes, a set of binding sites for zinc finger transcription factors C2H2, involved in cell stress responses, protein misfolding and chromatin remodelling and immunomodulation, is identified. The model can be used to explain the outcomes of mechanism of action and is observed across a range of species indicating this is a conserved part of the innate immune system.

Silica nanoparticles induce ovarian granulosa cell apoptosis via activation of the PERK-ATF4-CHOP-ERO1α pathway-mediated IP3R1-dependent calcium mobilization

Ambient particulate matters (PMs) have adverse effects in human and animal female reproductive health. Silica nanoparticles (SNPs), as a major component of PMs, can induce follicular atresia via the promotion of ovarian granulosa cell apoptosis. However, the molecular mechanisms of apoptosis induced by SNPs are not very clear. This work focuses on revealing the mechanisms of ER stress on SNP-induced apoptosis. Our results showed that spherical Stöber SNPs (110 nm, 25.0 mg/kg b.w.) induced follicular atresia via the promotion of granulosa cell apoptosis by intratracheal instillation in vivo; meanwhile, SNPs decreased the viability and increase apoptosis in granulosa cells in vitro. SNPs were taken up and accumulated in the vesicles of granulosa cells. Additionally, our results found that SNPs increased calcium ion (Ca2+) concentration in granulosa cell cytoplasm. Furthermore, SNPs activated ER stress via an increase in the PERK and ATF6 pathway-related protein levels and IP3R1-dependent calcium mobilization via an increase in IP3R1 level. In addition, 4-PBA restored IP3R1-dependent calcium mobilization and decreased apoptosis via the inhibition of ER stress. The ATF4-C/EBP homologous protein (CHOP)-ER oxidoreductase 1 alpha (ERO1α) pathway regulated SNP-induced IP3R1-dependent calcium mobilization and cell apoptosis via ATF4, CHOP, and ERO1α depletion in ovarian granulosa cells. Herein, we demonstrate that ER stress cooperated in SNP-induced ovarian toxicity via activation of IP3R1-mediated calcium mobilization, leading to apoptosis, in which the PERK-ATF4-CHOP-ERO1α pathway plays an essential role in ovarian granulosa cells.

An ER-Horse Detonating Stress Cascade for Hepatocellular Carcinoma Nanotherapy

Persisting and excessive endoplasmic reticulum stress (ERS) can evoke rapid cell apoptosis. Therapeutic interference of ERS signaling holds enormous potential for cancer nanotherapy. Herein, a hepatocellular carcinoma (HCC) cell-derived ER vesicle (ERV) encapsulating siGRP94, denoted as ER-horse, has been developed for precise HCC nanotherapy. Briefly, ER-horse, like the Trojan horse, was recognized via homotypic camouflage, imitated the physiological function of ER, and exogenously opened the Ca²⁺ channel. Consequently, the mandatory pouring-in of extracellular Ca²⁺ triggered the aggravated stress cascade (ERS and oxidative stress) and apoptosis pathway with the inhibition of unfolded protein response by siGRP94. Collectively, our findings provide a paradigm for potent HCC nanotherapy via ERS signaling interference and exploring therapeutic interference of physiological signal transduction pathways for precision cancer therapy.

Polystyrene nanoplastics aggravates lipopolysaccharide-induced apoptosis in mouse kidney cells by regulating IRE1/XBP1 endoplasmic reticulum stress pathway via oxidative stress

Nanoplastics (NPs) pollution poses a huge threat to the ecosystem and has become one of the environmental pollutants that have attracted much attention. There is increasing evidence that both oxidative stress and endoplasmic reticulum stress (ERS) are associated with polystyrene nanoplastics (PS-NPs) exposure. Lipopolysaccharide (LPS) has been shown to induce apoptotic damage in various tissues, but whether PS-NPs can aggravate LPS-induced apoptosis in mouse kidneys through oxidative stress-regulated inositol-requiring enzyme 1 (IRE1)/X-box binding protein 1 (XBP1) ERS pathway remains unclear. In this study, based on the establishment of in vitro and in vivo PS-NPs and LPS exposure models alone and in combination in mice and HEK293 cells, the effects and mechanisms of PS-NPs on LPS-induced renal cell apoptosis were investigated. The results showed that PS-NPs could aggravate LPS-induced apoptosis. PS-NPs/LPS can induce ERS through oxidative stress, activate the IRE1/XBP1 pathway, and promote the expression of apoptosis markers (Caspase-3 and Caspase-12). Kidney oxidative stress, ERS, and apoptosis in PS-NPs + LPS combined exposure group were more severe than those in the single exposure group. Interestingly, 4-phenylbutyric acid-treated HEK293 cells inhibited the expression of the IRE1/XBP1 ERS pathway and apoptotic factors in the PS-NPs + LPS combined exposure group. N-acetyl-L-cysteine effectively blocked the activation of the IRE1/XBP1 ERS pathway, suggesting that PS-NPs-induced oxidative stress is an early event that triggers ERS. Collectively, these results confirmed that PS-NPs aggravated LPS-induced apoptosis through the oxidative stress-induced IRE1/XBP1 ERS pathway. Our study provides new insights into the health threats of PS-NPs exposed to mammals and humans.

Palladium Nanoparticle-Induced Oxidative Stress, Endoplasmic Reticulum Stress, Apoptosis, and Immunomodulation Enhance the Biogenesis and Release of Exosome in Human Leukemia Monocytic Cells (THP-1)

Background

Exosomes are endosome-derived nano-sized vesicles that have emerged as important mediators of intercellular communication and play significant roles in various diseases. However, their applications are rigorously restricted by the limited secretion competence of cells. Therefore, strategies to enhance the production and functions of exosomes are warranted. Studies have shown that nanomaterials can significantly enhance the effects of cells and exosomes in intercellular communication; however, how palladium nanoparticles (PdNPs) enhance exosome release in human leukemia monocytic cells (THP-1) remains unclear. Therefore, this study aimed to address the effect of PdNPs on exosome biogenesis and release in THP-1 cells.

Methods

Exosomes were isolated by ultracentrifugation and ExoQuick^TM and characterized by dynamic light scattering, nanoparticle tracking analysis system, scanning electron microscopy, transmission electron microscopy, EXOCET^TM assay, and fluorescence polarization. The expression levels of exosome markers were analyzed via quantitative reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay.

Results

PdNP treatment enhanced the biogenesis and release of exosomes by inducing oxidative stress, endoplasmic reticulum stress, apoptosis, and immunomodulation. The exosomes were spherical in shape and had an average diameter of 50–80 nm. Exosome production was confirmed via total protein concentration, exosome counts, acetylcholinesterase activity, and neutral sphingomyelinase activity. The expression levels of TSG101, CD9, CD63, and CD81 were significantly higher in PdNP-treated cells than in control cells. Further, cytokine and chemokine levels were significantly higher in exosomes isolated from PdNP-treated THP-1 cells than in those isolated from control cells. THP-1 cells pre-treated with N-acetylcysteine or GW4869 showed significant decreases in PdNP-induced exosome biogenesis and release.

Conclusion

To our knowledge, this is the first study showing that PdNPs stimulate exosome biogenesis and release and simultaneously increase the levels of cytokines and chemokines by modulating various physiological processes. Our findings suggest a reasonable approach to improve the production of exosomes for various therapeutic applications.

MicroRNA-383 promotes reactive oxygen species-induced autophagy via downregulating peroxiredoxin 3 in human glioma U87 cells

Peroxiredoxin 3 (PRDX3) is an abundant and effective enzyme, which aids in the removal of H₂O₂ in the mitochondria, thereby inhibiting cell autophagy. PRDX3 is a target protein of microRNA (miRNA/miR)-383, the overexpression of which has been found to inhibit the growth of glioma cells. We hypothesized that miR-383 serves an antitumor role by inhibiting oxidative stress during tumor growth. In the current study, human glioma U87 cells were transfected with pre-/short hairpin (sh)-PRDX3 vectors and miR-383 mimics/inhibitors. Apoptosis and reactive oxygen species (ROS) production were detected using flow cytometry. Autophagy was examined using acridine orange staining, and the expression of cytoplasmic autophagy-related proteins [autophagy-related protein 9 (ATG9), Ras-related protein Rab-1A (Rab1) and p62] was determined using western blot analysis. The interaction between miR-383 and PRDX3 was assessed using a dual-luciferase assay. The results indicated that both sh-PRDX3 and miR-383 mimics promoted apoptosis and increased the level of mitochondrial ROS, whilst acridine orange staining revealed that sh-PRDX3 promoted autophagy in U87 cells compared with that in the control cells. The detection of autophagic proteins indicated that sh-PRDX3 and miR-383 mimics increased the protein expression level of ATG9 and RAB1, and inhibited that of p62. On the contrary, the effect of miR-383 mimics was opposite to that of pre-PRDX3 in U87 cells. Reverse transcription-quantitative PCR and western blot assays revealed that miR-383 was negatively associated with PRDX3 in U87 cells. miR-383 was indicated to interact with PRDX3, as demonstrated using a dual-luciferase assay. In conclusion, the present study demonstrated that miR-383 induced cell apoptosis and mitochondrial ROS production by downregulating PRDX3 in U87 cells, thereby promoting oxidative stress-induced autophagy.

Combined Toxicity of Metal Nanoparticles: Comparison of Individual and Mixture Particles Effect

Toxicity of metal nanoparticles (NPs) are closely associated with increasing intracellular reactive oxygen species (ROS) and the levels of pro-inflammatory mediators. However, NP interactions and surface complexation reactions alter the original toxicity of individual NPs. To date, toxicity studies on NPs have mostly been focused on individual NPs instead of the combination of several species. It is expected that the amount of industrial and highway-acquired NPs released into the environment will further increase in the near future. This raises the possibility that various types of NPs could be found in the same medium, thereby, the adverse effects of each NP either could be potentiated, inhibited or remain unaffected by the presence of the other NPs. After uptake of NPs into the human body from various routes, protein kinases pathways mediate their toxicities. In this context, family of mitogen-activated protein kinases (MAPKs) is mostly efficient. Despite each NP activates almost the same metabolic pathways, the toxicity induced by a single type of NP is different than the case of co-exposure to the combined NPs. The scantiness of toxicological data on NPs combinations displays difficulties to determine, if there is any risk associated with exposure to combined nanomaterials. Currently, in addition to mathematical analysis (Response surface methodology; RSM), the quantitative-structure-activity relationship (QSAR) is used to estimate the toxicity of various metal oxide NPs based on their physicochemical properties and levels applied. In this chapter, it is discussed whether the coexistence of multiple metal NPs alter the original toxicity of individual NP. Additionally, in the part of "Toxicity of diesel emission/exhaust particles (DEP)", the known individual toxicity of metal NPs within the DEP is compared with the data regarding toxicity of total DEP mixture.

Endoplasmic Reticulum Stress Provocation by Different Nanoparticles: An Innovative Approach to Manage the Cancer and Other Common Diseases

A proper execution of basic cellular functions requires well-controlled homeostasis including correct protein folding. Endoplasmic reticulum (ER) implements such functions by protein reshaping and post-translational modifications. Different insults imposed on cells could lead to ER stress-mediated signaling pathways, collectively called the unfolded protein response (UPR). ER stress is also closely linked with oxidative stress, which is a common feature of diseases such as stroke, neurodegeneration, inflammation, metabolic diseases, and cancer. The level of ER stress is higher in cancer cells, indicating that such cells are already struggling to survive. Prolonged ER stress in cancer cells is like an Achilles' heel, if aggravated by different agents including nanoparticles (NPs) may be exhausted off the pro-survival features and can be easily subjected to proapoptotic mode. Different types of NPs including silver, gold, silica, graphene, etc. have been used to augment the cytotoxicity by promoting ER stress-mediated cell death. The diverse physico-chemical properties of NPs play a great role in their biomedical applications. Some special NPs have been effectively used to address different types of cancers as these particles can be used as both toxicological or therapeutic agents. Several types of NPs, and anticancer drug nano-formulations have been engineered to target tumor cells to enhance their ER stress to promote their death. Therefore, mitigating ER stress in cancer cells in favor of cell death by ER-specific NPs is extremely important in future therapeutics and understanding the underlying mechanism of how cancer cells can respond to NP induced ER stress is a good choice for the development of novel therapeutics. Thus, in depth focus on NP-mediated ER stress will be helpful to boost up developing novel pro-drug candidates for triggering pro-death pathways in different cancers.

Small silica nanoparticles transiently modulate the intestinal permeability by actin cytoskeleton disruption in both Caco-2 and Caco-2/HT29-MTX models

Amorphous silica nanoparticles are widely used as pharmaceutical excipients and food additive (E551). Despite the potential human health risks of mineral nanoparticles, very few data regarding their oral toxicity are currently available. This study aims to evaluate and to understand the interactions of silica particles at 1 and 10 mg mL^-1 with the intestinal barrier using a Caco-2 monolayer and a Caco-2/HT29-MTX co-culture. A size- and concentration-dependent reversible increase of the paracellular permeability is identified after a short-term exposure to silica nanoparticles. Nanoparticles of 30 nm induce the highest transepithelial electrical resistance drop whereas no effect is observed with 200 nm particles. Additive E551 affect the Caco-2 monolayer permeability. Mucus layer reduces the permeability modulation by limiting the cellular uptake of silica. After nanoparticle exposure, tight junction expression including Zonula occludens 1 (ZO-1) and Claudin 2 is not affected, whereas the actin cytoskeleton disruption of enterocytes and the widening of ZO-1 staining bands are observed. A complete permeability recovery is concomitant with the de novo filament actin assembly and the reduction of ZO-1 bands. These findings suggest the paracellular modulation by small silica particles is directly correlated to the alteration of the ZO-actin binding strongly involved in the stability of the tight junction network.

Nanotoxicology data for in silico tools: a literature review

The exercise of non-testing approaches in nanoparticles (NPs) hazard assessment is necessary for the risk assessment, considering cost and time efficiency, to identify, assess, and classify potential risks. One strategy for investigating the toxicological properties of a variety of NPs is by means of computational tools that decode how nano-specific features relate to toxicity and enable its prediction. This literature review records systematically the data used in published studies that predict nano (eco)-toxicological endpoints using machine learning models. Instead of seeking mechanistic interpretations this review maps the pathways followed, involving biological features in relation to NPs exposure, their physico-chemical characteristics and the most commonly predicted outcomes. The results, derived from published research of the last decade, are summarized visually, providing prior-based data mining paradigms to be readily used by the nanotoxicology community in computational studies.

Interactions of nanomaterials with ion channels and related mechanisms

The pharmacological potential of nanotechnology, especially in drug delivery and bioengineering, has developed rapidly in recent decades. Ion channels, which are easily targeted by external agents, such as nanomaterials (NMs) and synthetic drugs, due to their unique structures, have attracted increasing attention in the fields of nanotechnology and pharmacology for the treatment of ion channel-related diseases. NMs have significant effects on ion channels, and these effects are manifested in many ways, including changes in ion currents, kinetic characteristics and channel distribution. Subsequently, intracellular ion homeostasis, signalling pathways, and intracellular ion stores are affected, leading to the initiation of a range of biological processes. However, the effect of the interactions of NMs with ion channels is an interesting topic that remains obscure. In this review, we have summarized the recent research progress on the direct and indirect interactions between NMs and ion channels and discussed the related molecular mechanisms, which are crucial to the further development of ion channel-related nanotechnological applications.

Penehyclidine hydrochloride defends against LPS-induced ALI in rats by mitigating endoplasmic reticulum stress and promoting the Hes1/Notch1 pathway

Penehyclidine hydrochloride (PHC) is a novel anticholinergic drug applied broadly in surgeries as a preanesthetic medication. A substantial amount of research indicates that PHC has lung defensive properties. Considering that endoplasmic reticulum (ER) stress exerts a crucial function in cell apoptosis associated with the lipopolysaccharides (LPS)-induced acute lung injury (ALI) model, we aimed to determine whether regulation of ER stress in the LPS-induced ALI model was associated with the lung defensive role of PHC. Adult male SD rats were administered LPS (5 mg/kg, intratracheally) followed by PHC (1.0 mg/kg, intravenously) for 24 h. The NR8383 alveolar macrophages were randomly separated into Sham, LPS (100 ng/mL), and PHC (1, 2.5, or 5 μg/mL) + LPS groups. PHC (1, 2.5, or 5 μg/mL) + LPS groups were treated with PHC alone for 1 h after LPS exposure. Posttreatment with PHC relieved LPS-induced pulmonary impairment and blocked LPS-mediated lung apoptosis, indicated by the downregulation of the lung apoptotic indicators malondialdehyde and superoxide dismutase in serum at 24 h after LPS-induced ALI. PHC (1-5 μg/mL) did not influence the activity of cultivated NR8383 alveolar macrophages in vitro. However, postconditioning with PHC dosage-dependently reduced LPS-mediated cell apoptosis. Additionally, many studies have indicated that PHC administration inhibits ER stress and initiates hairy and enhancer of split 1 (Hes1)/(Notch1) signaling by decreasing phosphorylated α subunit of eukaryotic initiation factor 2α (p-eIF2α)/eukaryotic translation initiation factor 2α (eIF2α) and Phospho-protein kinase R-like ER kinase (p-PERK)/ protein kinase R-like ER kinase (PERK) proportions; inhibiting C/EBP-homologous protein (CHOP), activating transcription factor 4 (ATF4), caspase-3, and Bcl2-associated x (Bax) activity; and enhancing notch1 intracellular domain (NICD), Notch1, B-cell lymphoma-2 (Bcl-2), and Hes1 activity in vivo and in vitro. In addition, the defensive functions of PHC on LPS-activated NR8383 alveolar macrophages were abrogated through the Notch1 pathway antagonist [(3,5-difluorophenacetyl)-1-alanyl] -phenylglycine-butyl ester (DAPT). In conclusion, PHC alleviates LPS-induced ALI by ameliorating ER stress-mediated apoptosis and promoting Hes1/Notch1 signaling in vivo and in vitro.

Acute Exposure to SiO2 Nanoparticles Affects Protein Synthesis in Bergmann Glia Cells

Attractive due to an alleged high biocompatibility, silica nanoparticles have been widely used in the field of nanomedicine; however, their proven capacity to induce the synthesis and release of pro-inflammatory cytokines in several cellular models has raised concern about their safety. Glutamate, the main excitatory amino acid transmitter triggers a wide variety of signal transduction cascades that regulate protein synthesis at transcriptional and translational levels. A stimulus-dependent dynamic change in the protein repertoire in neurons and glia cells is the molecular framework of higher brain functions. Within the cerebellum, Bergmann glia cells are the most abundant non-neuronal cells and span the entire molecular layer of the cerebellar cortex, wrapping the synapses in this structure. Taking into consideration the functional role of Bergmann glia in terms of the recycling of glutamate, lactate supply to neurons, and prevention of neurotoxic insults, we decided to investigate the possibility that silica nanoparticles affect Bergmann glia and by these means alter the major excitatory neurotransmitter system in the brain. To this end, we exposed cultured chick cerebellar Bergmann glia cells to silica nanoparticles and measured [³⁵S]-methionine incorporation into newly synthesized polypeptides. Our results demonstrate that exposure of the cultured cells to silica nanoparticles exerts a time- and dose-dependent modulation of protein synthesis. Furthermore, altered patterns of eukaryotic initiation factor 2 alpha and eukaryotic elongation factor 2 phosphorylation were present upon nanoparticle exposure. These results demonstrate that glia cells respond to the presence of this nanomaterial modifying their proteome, presumably in an effort to overcome any plausible neurotoxic effect.

In silico prediction of MicroRNA role in regulation of Zebrafish (Danio rerio) responses to nanoparticle exposure

The release of nanoparticles to the environment can affect health of the exposed organisms. MicroRNAs have been suggested as potential toxicology biomarkers, however the information about use of microRNA in aquatic organisms exposed to nanoparticles (NP) is limited. In silico analysis from publicly available gene expression data was performed. Data selection for the analysis was based on reported biological and pathological outcomes of NP induced toxicity in zebrafish. After identifying relevant genes, we constructed six miRNA-mRNA regulatory networks involved in nanoparticle induced toxicological responses in zebrafish. Based on our prediction and selection criteria we selected six miRNAs that overlapped in constructed networks with remarkable prediction score, and were validated by previous mammalian and zebrafish microRNA profiling studies: dre-miR-124, -144, -148, -155, -19a, -223. The results of this in silico analysis indicate that several highly conserved miRNAs likely have a regulatory role of organismal responses to nanoparticles, and can possibly be used as biomarkers of nanotoxicity in studies using zebrafish as model organism One health approaches.

Delivery of Conjugated Silicon Dioxide Nanoparticles Show Strong Anti-Proliferative Activities

Conjugation of different molecules is a promising approach to enhance the drug delivery and treatment. In the present study, here, we have synthesized silica oxide (SiO₂) nanoparticles conjugated with (3-Glycidyloxypropyl) trimethoxysilane (3GPS) and further reacted with 1,2,4-triazole (Tri), 3-aminotriazole (ATri), 5-aminetetrazole (Atet), imidazole (Imi). The structure, size, and morphology of nanocomposite materials were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) methods. These nanocomposite materials were tested on human colorectal carcinoma cells (HCT-116) to examine their anti-cancer capabilities by using MTT assay and morphometric analysis. Our results revealed that nanocomposite materials decreased cancer cell viability and cell proliferation and caused cell death in a concentration-dependent manner. Our findings demonstrate that SiO₂-conjugated nanocomposite materials possess strong anti-cancer capabilities and hold a great potential for the colon cancer treatments.

Uptake and intracellular fate of biocompatible nanocarriers in cycling and noncycling cells

AIM

To elucidate whether different cytokinetic features (i.e., presence or absence of mitotic activity) may influence cell uptake and distribution of nanocarriers, in vitro tests on liposomes, mesoporous silica nanoparticles, poly(lactide-co-glycolide) nanoparticles and nanohydrogels were carried out on C2C12 murine muscle cells either able to proliferate as myoblasts (cycling cells) or terminally differentiate into myotubes (noncycling cells).

MATERIALS & METHODS

Cell uptake and intracellular fate of liposomes, mesoporous silica nanoparticles, poly(lactide-co-glycolide) nanoparticles and nanohydrogels were investigated by confocal fluorescence microscopy and transmission electron microscopy.

RESULTS

Nanocarrier internalization and distribution were similar in myoblasts and myotubes; however, myotubes demonstrated a lower uptake capability.

CONCLUSION

All nanocarriers proved to be suitably biocompatible for both myoblasts and myotubes. The lower uptake capability of myotubes is probably due to different plasma membrane composition related to the differentiation process.

Necrotic, apoptotic and autophagic cell fates triggered by nanoparticles

Nanomaterials have gained a rapid increase in use in a variety of applications that pertain to many aspects of human life. The majority of these innovations are centered on medical applications and a range of industrial and environmental uses ranging from electronics to environmental remediation. Despite the advantages of NPs, the knowledge of their toxicological behavior and their interactions with the cellular machinery that determines cell fate is extremely limited. This review is an attempt to summarize and increase our understanding of the mechanistic basis of nanomaterial interactions with the cellular machinery that governs cell fate and activity. We review the mechanisms of NP-induced necrosis, apoptosis and autophagy and potential implications of these pathways in nanomaterial-induced outcomes. Abbreviations: Ag, silver; CdTe, cadmium telluride; CNTs, carbon nanotubes; EC, endothelial cell; GFP, green fluorescent protein; GO, graphene oxide; GSH, glutathione; HUVECs, human umbilical vein endothelial cells; NP, nanoparticle; PEI, polyethylenimine; PVP, polyvinylpyrrolidone; QD, quantum dot; ROS, reactive oxygen species; SiO2, silicon dioxide; SPIONs, superparamagnetic iron oxide nanoparticles; SWCNT, single-walled carbon nanotubes; TiO2, titanium dioxide; USPION, ultra-small super paramagnetic iron oxide; ZnO, zinc oxide.

Toxicological impact of acute exposure to E171 food additive and TiO2 nanoparticles on a co-culture of Caco-2 and HT29-MTX intestinal cells

TiO₂ particles are widely used in products for everyday consumption, such as cosmetics and food; their possible adverse effects on human health must therefore be investigated. The aim of this study was to document in vitro impact of the food additive E171, i.e. TiO₂, and of TiO₂ nanoparticles, on a co-culture of Caco-2 and HT29-MTX cells, which is an in vitro model for human intestine. Cells were exposed to TiO₂ particles three days after seeding, i.e. while they were not fully differentiated. Cell viability, reactive oxygen species (ROS) levels and DNA integrity were assessed, by MTT assay, DCFH-DA assay, alkaline and Fpg-modified comet assay and 8-oxo-dGuo measurement by HPLC-MS/MS. The mRNA expression of genes involved in ROS regulation, DNA repair via base-excision repair, and endoplasmic reticulum stress was assessed by RT-qPCR. Exposure to TiO₂ particles resulted in increased intracellular ROS levels, but did not impair cell viability and did not cause any oxidative damage to DNA. Only minor changes in mRNA expression were detected. Altogether, this shows that E171 food additive and TiO₂ nanoparticles only produce minor effects to this in vitro intestinal cell model.

Nanoparticles induce apoptosis via mediating diverse cellular pathways

With a special size and structure, nanoparticles (NPs) have excellent application prospects in various fields and are widely used in the biomedicine, cosmetics and chemical industries nowadays. However, there have been some reports on the biosafety of this new type of material, pointing out its cytotoxicity in inducing apoptosis. With different physicochemical properties in size, shape, surface charge, and ligand, NPs exhibit different biocompatibilities when interacting with different cells. Therefore, a comprehensive and deep study into the proapoptotic mechanism of NPs is necessary. In the present review, we summarize the NP-triggered apoptotic signal pathways in detail and highlight some important functional molecules involved. We hope our findings and perspectives provide a new direction for the sound development of nanotechnology in the future.

Silica nanoparticle-induced oxidative stress and mitochondrial damage is followed by activation of intrinsic apoptosis pathway in glioblastoma cells

Introduction

Recently, the focus of oncological research has been on the optimization of therapeutic strategies targeted at malignant diseases. Nanomedicine utilizing silicon dioxide nanoparticles (SiNPs) is one such strategy and is rapidly developing as a promising tool for cancer diagnosis, imaging, and treatment. Nevertheless, little is known about the mechanisms of action of SiNPs in brain tumors.

Materials and methods

Here, we explored the effects of 5-15 nm SiNPs in the human glioblastoma cell line LN229. In this respect, MTT assays, microscopic observations, flow cytometry analyses, and luminescent assays were performed. Moreover, RT-qPCR and Western blot analyses were done to determine gene and protein expressions.

Results

We demonstrated that SiNPs triggered evident cytotoxicity, with microscopic observations of the nuclei, annexin V-fluorescein isothiocyanate/propidium iodide staining, and elevated caspase 3/7 activity, suggesting that SiNPs predominantly induced apoptotic death in LN229 cells. We further showed the occurrence of oxidative stress induced by enhanced reactive oxygen-species generation. This effect was followed by deregulated expression of genes encoding the antioxidant enzymes SOD1, SOD2, and CAT, and impaired mitochondria function. SiNP- induced mitochondrial dysfunction was characterized by membrane-potential collapse, ATP depletion, elevated expression of BAX, PUMA, and NOXA with simultaneous downregulation of BCL2/BCL2L1, and activation of caspase 9. Moreover, RT-qPCR and Western blot analyses demonstrated increased levels of the endoplasmic reticulum stress markers GRP78, GRP94, and DDIT3, as well as strongly increased expressions of the IL1B and COX2 genes, suggesting activation of endoplasmic reticulum stress and a proinflammatory response.

Conclusions

Altogether, our data indicate that in LN229 cells, SiNPs evoke cell death via activation of the intrinsic apoptosis pathway and suggest that other aspects of cellular function may also be affected. As such, SiNPs represent a potentially promising agent for facilitating further progress in brain cancer therapy. However, further exploration of SiNP long-term toxicity and molecular effects is necessary prior to their widespread application.

Toxicity of inhaled particulate matter on the central nervous system: neuroinflammation, neuropsychological effects and neurodegenerative disease

Particulate matter (PM) combined with meteorological factors cause the haze, which brings inconvenience to people's daily life and deeply endanger people's health. Accumulating literature, to date, reported that PM are closely related to cardiopulmonary disease. Outpatient visits and admissions as a result of asthma and heart attacks gradually increase with an elevated concentration of PM. Owing to its special physicochemical property, the brain could be a potential target beyond the cardiopulmonary system. Possible routes of PM to the brain via a direct route or stimulation of pro-inflammatory cytokines have been reported in several documents concerning toxicity of engineered nanoparticles in rodents. Recent studies have demonstrated that PM have implications in oxidative stress, inflammation, dysfunction of cellular organelles, as well as the disturbance of protein homeostasis, promoting neuron loss and exaggerating the burden of central nervous system (CNS). Moreover, the smallest particles (nano-sized particles), which were involved in inflammation, reactive oxygen species (ROS), microglial activation and neuron loss, may accelerate the process of the neurodevelopmental disorder and neurodegenerative disease. Potential or other undiscovered mechanisms are not mutually exclusive but complementary aspects of each other. Epidemiology studies have shown that exposure to PM could bring about neurotoxicity and play a significant role in the etiology of CNS disease, which has been gradually corroborated by in vivo and in vitro studies. This review highlights research advances on the health effects of PM with an emphasis on neurotoxicity. With the hope of enhancing awareness in the public and calling for prevention and protective measures, it is a critical topic that requires proceeding exploration. Copyright © 2017 John Wiley & Sons, Ltd.

Differential cytotoxic and inflammatory potency of amorphous silicon dioxide nanoparticles of similar size in multiple cell lines

The likelihood of environmental and health impacts of silicon dioxide nanoparticles (SiNPs) has risen, due to their increased use in products and applications. The biological potency of a set of similarly-sized amorphous SiNPs was investigated in a variety of cells to examine the influence of physico-chemical and biological factors on their toxicity. Cellular LDH and ATP, BrdU incorporation, resazurin reduction and cytokine release were measured in human epithelial A549, human THP-1 and mouse J774A.1 macrophage cells exposed for 24 h to suspensions of 5-15, 10-20 and 12 nm SiNPs and reference particles. The SiNPs were characterized in dry state and in suspension to determine their physico-chemical properties. The dose-response data were simplified into particle potency estimates to facilitate the comparison of multiple endpoints of biological effects in cells. Mouse macrophages were the most sensitive to SiNP exposures. Cytotoxicity of the individual cell lines was correlated while the cytokine responses differed, supported by cell type-specific differences in inflammation-associated pathways. SiNP (12 nm), the most cytotoxic and inflammogenic nanoparticle had the highest surface acidity, dry-state agglomerate size, the lowest trace metal and organics content, the smallest surface area and agglomerate size in suspension. Particle surface acidity appeared to be the most significant determinant of the overall biological activity of this set of nanoparticles. Combined with the nanoparticle characterization, integration of the biological potency estimates enabled a comprehensive determination of the cellular reactivity of the SiNPs. The approach shows promise as a useful tool for first-tier screening of SiNP toxicity.

Silica nanoparticles induce endoplasmic reticulum stress response and activate mitogen activated kinase (MAPK) signalling

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Effects of silica nanoparticles (SiO₂-NPs) were investigated in Huh7 cells.

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SiO₂-NPs induced ER stress response and activated MAPK pathway.

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SiO₂-NPs induced inflammatory reaction by induction of TNF-α.

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Activation of MAPK may lead to activation of AP-1 complex.

Humans may be exposed to engineered silica nanoparticles (SiO₂-NPs) but potential adverse effects are poorly understood, in particular in relation to cellular effects and modes of action. Here we studied effects of SiO₂-NPs on cellular function in human hepatoma cells (Huh7). Exposure for 24 h to 10 and 50 μg/ml SiO₂-NPs led to induction of endoplasmic reticulum (ER) stress as demonstrated by transcriptional induction of DNAJB9, GADD34, CHOP, as well as CHOP target genes BIM, CHAC-1, NOXA and PUMA. In addition, CHOP protein was induced. In addition, SiO₂-NPs induced an inflammatory response as demonstrated by induction of TNF-α and IL-8. Activation of MAPK signalling was investigated employing a PCR array upon exposure of Huh7 cells to SiO₂-NPs. Five of 84 analysed genes, including P21, P19, CFOS, CJUN and KSR1 exhibited significant transcriptional up-regulation, and 18 genes a significant down-regulation. Strongest down-regulation occurred for the proto-oncogene BRAF, MAPK11, one of the four p38 MAPK genes, and for NFATC4. Strong induction of CFOS, CJUN, FRA1 and CMYC was found after exposure to 50 μg/ml SiO₂-NPs for 24 h. To analyse for effects derived from up-regulation of TNF-α, Huh7 cells were exposed to SiO₂-NPs in the presence of the TNF-α inhibitor sauchinone, which reduced the induction of the TNF-α transcript by about 50%. These data demonstrate that SiO₂-NPs induce ER stress, MAPK pathway and lead to inflammatory reaction in human hepatoma cells. Health implications of SiO₂-NPs exposure should further be investigated for a risk assessment of these frequently used nanoparticles.

Fluorescence and electron microscopy to visualize the intracellular fate of nanoparticles for drug delivery

In order to design valid protocols for drug release via nanocarriers, it is essential to know the mechanisms of cell internalization, the interactions with organelles, and the intracellular permanence and degradation of nanoparticles (NPs) as well as the possible cell alteration or damage induced. In the present study, the intracellular fate of liposomes, polymeric NPs and mesoporous silica NPs (MSN) has been investigated in an in vitro cell system by fluorescence and transmission electron microscopy. The tested nanocarriers proved to be characterized by specific interactions with the cell: liposomes enter the cells probably by fusion with the plasma membrane and undergo rapid cytoplasmic degradation; polymeric NPs are internalized by endocytosis, occur in the cytoplasm both enclosed in endosomes and free in the cytosol, and then undergo massive degradation by lysosome action; MSN are internalized by both endocytosis and phagocytosis, and persist in the cytoplasm enclosed in vacuoles. No one of the tested nanocarriers was found to enter the nucleus. The exposure to the different nanocarriers did not increase cell death; only liposomes induced a reduction of cell population after long incubation times, probably due to cell overloading. No subcellular damage was observed to be induced by polymeric NPs and MSN, whereas transmission electron microscopy revealed cytoplasm alterations in liposome-treated cells. This important information on the structural and functional relationships between nanocarriers designed for drug delivery and cultured cells further proves the crucial role of microscopy techniques in nanotechnology.

Tight junction between endothelial cells: the interaction between nanoparticles and blood vessels

Since nanoparticles are now widely applied as food additives, in cosmetics and other industries, especially in medical therapy and diagnosis, we ask here whether nanoparticles can cause several adverse effects to human health. In this review, based on research on nanotoxicity, we mainly discuss the negative influence of nanoparticles on blood vessels in several aspects and the potential mechanism for nanoparticles to penetrate endothelial layers of blood vessels, which are the sites of phosphorylation of tight junction proteins (claudins, occludins, and ZO (Zonula occludens)) proteins, oxidative stress and shear stress. We propose a connection between the presence of nanoparticles and the regulation of the tight junction, which might be the key approach for nanoparticles to penetrate endothelial layers and then have an impact on other tissues and organs.

Ameliorative Influence of Green Tea Extract on Copper Nanoparticle-Induced Hepatotoxicity in Rats

The potential toxicity of copper nanoparticles (CNPs) to the human health and environment remains a critical issue. In the present study, we investigated the protective influence of an aqueous extract of green tea leaves (GTE) against CNPs-induced (20-30 nm) hepatotoxicity. Four different groups of rats were used: group I was the control, group II received CNPs (40 mg/kg BW), group III received CNPs plus GTE, and group IV received GTE alone. We highlighted the hepatoprotective effect of GTE against CNPs toxicity through monitoring the alteration of liver enzyme activity, antioxidant defense mechanism, histopathological alterations, and DNA damage evaluation. The rats that were given CNPs only had a highly significant elevation in liver enzymes, alteration in oxidant-antioxidant balance, and severe pathological changes. In addition, we detected a significant elevation of DNA fragmentation percentage, marked DNA laddering, and significance over expression of both caspase-3 and Bax proteins. The findings for group III clarify the efficacy of GTE as a hepatoprotectant on CNPs through improving the liver enzyme activity, antioxidant status, as well as suppressing DNA fragmentation and the expression of the caspase-3 and Bax proteins. In conclusion, GTE was proved to be a potential hepatoprotective additive as it significantly ameliorates the hepatotoxicity and apoptosis induced by CNPs.