Toxicity of TiO2 Nanoparticles: Validation of Alternative Models.

There are many studies concerning titanium dioxide (TiO2) nanoparticles (NP) toxicity. Nevertheless, there are few publications comparing in vitro and in vivo exposure, and even less comparing air-liquid interface exposure (ALI) with other in vitro and in vivo exposures. The identification and validation of common markers under different exposure conditions are relevant for the development of smart and quick nanotoxicity tests. In this work, cell viability was assessed in vitro by WST-1 and LDH assays after the exposure of NR8383 cells to TiO2 NP sample. To evaluate in vitro gene expression profile, NR8383 cells were exposed to TiO2 NP during 4 h at 3 cm2 of TiO2 NP/cm2 of cells or 19 µg/mL, in two settings-submerged cultures and ALI. For the in vivo study, Fischer 344 rats were exposed by inhalation to a nanostructured aerosol at a concentration of 10 mg/m3, 6 h/day, 5 days/week for 4 weeks. This was followed immediately by gene expression analysis. The results showed a low cytotoxic potential of TiO2 NP on NR8383 cells. Despite the absence of toxicity at the doses studied, the different exposures to TiO2 NP induce 18 common differentially expressed genes (DEG) which are involved in mitosis regulation, cell proliferation and apoptosis and inflammation transport of membrane proteins. Among these genes, we noticed the upregulation of Ccl4, Osm, Ccl7 and Bcl3 genes which could be suggested as early response biomarkers after exposure to TiO2 NP. On the other hand, the comparison of the three models helped us to validate the alternative ones, namely submerged and ALI approaches.

Layer-by-Layer Self-Assembly of Polyelectrolytes on Superparamagnetic Nanoparticle Surfaces.

Designing and manufacturing multifunctional nanoparticles (NPs) are of considerable interest for both academic and industrial research. Among NPs used in this field, iron oxide NPs show low toxicity compared to metallic ones and are thus of high interest for biomedical applications. In this work, superparamagnetic Fe3-δO4-based core/shell NPs were successfully prepared and characterized by the combination of different techniques, and their physical properties were investigated. We demonstrate the efficiency of the layer-by-layer process to graft polyelectrolytes on the surface of iron oxide NPs. The influence of the polyelectrolyte chain configuration on the magnetic properties of the Fe3-δO4/polymer core/shell NPs was enlightened. The simple and fast process described in this work is efficient for the grafting of polyelectrolytes from surfaces, and thus, derived Fe3-δO4 NPs display both the physical properties of the core and of the macromolecular shell. Finally, the cytotoxicity toward the human THP-1 monocytic cell line of the core/shell NPs was assessed. The results showed that the polymer-capped Fe3-δO4 NPs exhibited almost no toxicity after 24 h of exposure at concentrations up to 25 µg mL-1. Our results show that these smart superparamagnetic nanocarriers with stealth properties are promising for applications in multimodal cancer therapy, including drug delivery.

Cytotoxicity, fluorescence tagging and gene-expression study of CuInS/ZnS QDS - meso (hydroxyphenyl) porphyrin conjugate against human monocytic leukemia cells.

The toxicity of heavy metals present in binary semiconductor nanoparticles also known as quantum dots (QDs) has hindered their wide applications hence the advent of non-toxic ternary quantum dots. These new group of quantum dots have been shown to possess some therapeutic action against cancer cell lines but not significant enough to be referred to as an ideal therapeutic agent. In this report, we address this problem by conjugating red emitting CuInS/ZnS QDs to a 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin -photosensitizer for improved bioactivities. The glutathione capped CuInS/ZnS QDs were synthesized in an aqueous medium using a kitchen pressure cooker at different Cu: In ratios (1:4 and 1:8) and at varied temperatures (95 °C, 190 °C and 235 °C). Optical properties show that the as-synthesized CuInS/ZnS QDs become red-shifted compared to the core (CuInS) after passivation with emission in the red region while the cytotoxicity study revealed excellent cell viability against normal kidney fibroblasts (BHK21). The highly fluorescent, water-soluble QDs were conjugated to 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin (mTHPP) via esterification reactions at room temperature. The resultant water-soluble conjugate was then used for the cytotoxicity, fluorescent imaging and gene expression study against human monocytic leukemia cells (THP-1). Our result showed that the conjugate possessed high cytotoxicity against THP-1 cells with enhanced localized cell uptake compared to the bare QDs. In addition, the gene expression study revealed that the conjugate induced inflammation compared to the QDs as NFKB gene was over-expressed upon cell inflammation while the singlet oxygen (1O2) study showed the conjugate possessed large amount of 1O2, three times than the bare porphyrin. Thus, the as-synthesized conjugate looks promising as a therapeutic agent for cancer therapy.

Genes expression profiling of alveolar macrophages exposed to non-functionalized, anionic and cationic multi-walled carbon nanotubes shows three different mechanisms of toxicity.

Functionalized multi-walled carbon nanotubes (MWCNT) have become the focus of increased research interest, particularly in their application as tools in different areas, such as the biomedical field. Despite the benefits associated with functionalization of MWCNT, particularly in overcoming issues relating to solubility, several studies have demonstrated that these functionalized nanoparticles display different toxicity profiles. For this study, we aim to compare NR8383 cells responses to three well-characterized MWCNT with varying functional groups. This study employed cytotoxicity assays, transcriptomics and proteomics to assess their toxicity using NR8383 rat alveolar macrophages as an in vitro model. The study findings indicated that all MWCNT altered ribosomal protein translation, cytoskeleton arrangement and induced pro-inflammatory response. Only functionalized MWCNT alter mTOR signaling pathway in conjunction with increased Lamtor gene expression. Furthermore, the type of functionalization was also important, with cationic MWCNT activating the transcription factor EB and inducing autophagy while the anionic MWCNT altering eukaryotic translation initiation factor 4 (EIF4) and phosphoprotein 70 ribosomal protein S6 kinase (p70S6K) signaling pathway as well as upregulation Tlr2 gene expression. This study proposes that MWCNT toxicity mechanisms are functionalization dependent and provides evidence that inflammatory response is a key event of carbon nanotubes toxicity.

Correction to: Protein and lipid homeostasis altered in rat macrophages after exposure to metallic oxide nanoparticles.

Unfortunately, the author names in the author group section were incorrectly captured in the published online paper.

Protein and lipid homeostasis altered in rat macrophages after exposure to metallic oxide nanoparticles.

Metal oxide nanoparticles (NPs), such as ZnO, ZnFe2O4, and Fe2O3, are widely used in industry. However, little is known about the cellular pathways involved in their potential toxicity. Here, we particularly investigated the key molecular pathways that are switched on after exposure to sub-toxic doses of ZnO, ZnFe2O4, and Fe2O3 in the in vitro rat alveolar macrophages (NR8383). As in our model, the calculated IC50 were respectively 16, 68, and more than 200 µg/mL for ZnO, ZnFe2O4, and Fe2O3; global gene and protein expression profiles were only analyzed after exposure to ZnO and ZnFe2O4 NPs. Using a rat genome microarray technology, we found that 985 and 1209 genes were significantly differentially expressed in NR8383 upon 4 h exposure to » IC50 of ZnO and ZnFe2O4 NPs, respectively. It is noteworthy that metallothioneins were overexpressed genes following exposure to both NPs. Moreover, Ingenuity Pathway Analysis revealed that the top canonical pathway disturbed in NR8383 exposed to ZnO and ZnFe2O4 NPs was eIF2 signaling involved in protein homeostasis. Quantitative mass spectrometry approach performed from both NR8383 cell extracts and culture supernatant indicated that 348 and 795 proteins were differentially expressed upon 24 h exposure to » IC50 of ZnO and ZnFe2O4 NPs, respectively. Bioinformatics analysis revealed that the top canonical pathways disturbed in NR8383 were involved in protein homeostasis and cholesterol biosynthesis for both exposure conditions. While VEGF signaling was specific to ZnO exposure, iron homeostasis signaling pathway was specific to ZnFe2O4 NPs. Overall, the study provides resource of transcriptional and proteomic markers of response to ZnO and ZnFe2O4 NP-induced toxicity through combined transcriptomics, proteomics, and bioinformatics approaches.

Single wall and multiwall carbon nanotubes induce different toxicological responses in rat alveolar macrophages.

Human exposure to airborne carbon nanotubes (CNT) is increasing because of their applications in different sectors; therefore, they constitute a biological hazard. Consequently, developing studies on CNT toxicity become a necessity. CNTs can have different properties in term of length, size and charge. Here, we compared the cellular effect of multiwall (MWCNTs) and single wall CNTs (SWCNTs). MWCNTs consist of multiple layers of graphene, while SWCNTs are monolayers. The effects of MWCNTs and SWCNTs were evaluated by the water-soluble tetrazolium salt cell proliferation assay on NR8383 cells, rat alveolar macrophage cell line (NR8383). After 24 hours of exposure, MWCNTs showed higher toxicity (50% inhibitory concentration [IC50 ] = 3.2 cm2 /cm2 ) than SWCNTs (IC50  = 44 cm2 /cm2 ). Only SWCNTs have induced NR8383 cells apoptosis as assayed by flow cytometry using the annexin V/IP staining test. The expression of genes involved in oxidative burst (Ncf1), inflammation (Nfκb, Tnf-α, Il-6 and Il-1ß), mitochondrial damage (Opa) and apoptotic balance (Pdcd4, Bcl-2 and Casp-8) was determined. We found that MWCNT exposure predominantly induce inflammation, while SWCNTs induce apoptosis and impaired mitochondrial function. Our results clearly suggest that MWCNTs are ideal candidates for acute inflammation induction. In vivo studies are required to confirm this hypothesis. However, we conclude that toxicity of CNTs is dependent on their physical and chemical characteristics.

Cytotoxicity and global transcriptional responses induced by zinc oxide nanoparticles NM 110 in PMA-differentiated THP-1 cells.

Despite a wide production and use of zinc oxide nanoparticles (ZnONP), their toxicological study is only of limited number and their impact at a molecular level is seldom addressed. Thus, we have used, as a model, zinc oxide nanoparticle NM110 (ZnO110NP) exposure to PMA-differentiated THP-1 macrophages. The cell viability was studied at the cellular level using WST-1, LDH and Alamar Blue® assays, as well as at the molecular level by transcriptomic analysis. Exposure of cells to ZnO110NP for 24 h decreased their viability in a dose-dependent manner with mean inhibitory concentrations (IC50) of 8.1 µg/mL. Transcriptomic study of cells exposed to two concentrations of ZnO110NP: IC50 and a quarter of it (IC50/4) for 4 h showed that the expressions of genes involved in metal metabolism are perturbed. In addition, expression of genes acting in transcription regulation and DNA binding, as well as clusters of genes related to protein synthesis and structure were altered. It has to be noted that the expressions of metallothioneins genes (MT1, MT2) and genes of heat-shock proteins genes (HSP) were strongly upregulated for both conditions. These genes might be used as an early marker of exposure to ZnONP. On the contrary, at IC50 exposure, modifications of gene expression involved in inflammation, apoptosis and mitochondrial suffering were noted indicating a less specific cellular response. Overall, this study brings a resource of transcriptional data for ZnONP toxicity for further mechanistic studies.