Comparative study of nanoparticle uptake and impact in murine lung, liver and kidney tissue slices

To determine responses to nanoparticles in a more comprehensive way, current efforts in nanosafety aim at combining the analysis of multiple endpoints and comparing outcomes in different models. To this end, here we used tissue slices from mice as 3D ex vivo models and performed for the first time a comparative study of uptake and impact in liver, lung, and kidney slices exposed under the same conditions to silica, carboxylated and amino-modified polystyrene. In all organs, only exposure to amino-modified polystyrene induced toxicity, with stronger effects in kidneys and lungs. Uptake and distribution studies by confocal microscopy confirmed nanoparticle uptake in all slices, and, in line with what observed in vivo, preferential accumulation in the macrophages. However, uptake levels in kidneys were minimal, despite the strong impact observed when exposed to the amino-modified polystyrene. On the contrary, nanoparticle uptake and accumulation in macrophages were particularly evident in lung slices. Thus, tissue digestion was used to recover all cells from lung slices at different exposure times and to determine by flow cytometry detailed uptake kinetics in lung macrophages and all other cells, confirming higher uptake by the macrophages. Finally, the expression levels of a panel of targets involved in inflammation and macrophage polarization were measured to determine potential effects induced in lung and liver tissue. Overall, this comparative study allowed us to determine uptake and impact of nanoparticles in real tissue and identify important differences in outcomes in the organs in which nanoparticles distribute.

Amorphous silica nanoparticle-induced pulmonary inflammatory response depends on particle size and is sex-specific in rats

Due to mass production and extensive use, the potential adverse health effects of amorphous silica nanoparticles (ASiNPs) have received a significant attention from the public and researchers. However, the relationship between physicochemical properties of ASiNPs and their health effects is still unclear. In this study, we manufactured two types of ASiNPs of different diameters (20 and 50 nm) and compared the toxic response induced in rats after intratracheal instillation (75, 150 or 300 μg/rat). There were no dose-related differences in mortality, body weight gain or organ weight between the groups. However both types of ASiNPs significantly decreased the proportion of neutrophils in male rats, whereas the levels of hemoglobin and hematocrit were markedly reduced only in female rats instilled with 20 nm-ASiNPs. ASiNPs-induced lung tissue damage seemed to be more evident in the 20 nm ASiNP-treated group and in female rats than male rats. Similarly, expression of caveolin-1 and matrix metalloproteinase-9 seemed to be most notably enhanced in female rats treated with 20 nm-ASiNPs. The total number of bronchial alveolar lavage cells significantly increased in rats instilled with 20 nm-ASiNPs, accompanying a decrease in the proportion of macrophages and an increase in polymorphonuclear leukocytes. Moreover, secretion of inflammatory mediators clearly increased in human bronchial epithelial cells treated with 20 nm-ASiNPs, but not in those treated with 50 nm-ASiNPs. These results suggest that pulmonary effects of ASiNPs depend on particle size. Sex-dependent differences should also be carefully considered in understanding nanomaterial-induced adverse health effects.

Time-resolved characterization of the mechanisms of toxicity induced by silica and amino-modified polystyrene on alveolar-like macrophages

Macrophages play a major role in the removal of foreign materials, including nano-sized materials, such as nanomedicines and other nanoparticles, which they accumulate very efficiently. Because of this, it is recognized that for a safe development of nanotechnologies and nanomedicine, it is essential to investigate potential effects induced by nano-sized materials on macrophages. To this aim, in this work, a recently established model of primary murine alveolar-like macrophages was used to investigate macrophage responses to two well-known nanoparticle models: 50 nm amino-modified polystyrene, known to induce cell death via lysosomal damage and apoptosis in different cell types, and 50 nm silica nanoparticles, which are generally considered non-toxic. Then, a time-resolved study was performed to characterize in detail the response of the macrophages following exposure to the two nanoparticles. As expected, exposure to the amino-modified polystyrene led to cell death, but surprisingly no lysosomal swelling or apoptosis were detected. On the contrary, a peculiar mitochondrial membrane hyperpolarization was observed, accompanied by endoplasmic reticulum stress (ER stress), increased cellular reactive oxygen species (ROS) and changes of metabolic activity, ultimately leading to cell death. Strong toxic responses were observed also after exposure to silica, which included mitochondrial ROS production, mitochondrial depolarization and cell death by apoptosis. Overall, these results showed that exposure to the two nanoparticles led to a very different series of intracellular events, suggesting that the macrophages responded differently to the two nanoparticle models. Similar time-resolved studies are required to characterize the response of macrophages to nanoparticles, as a key parameter in nanosafety assessment.

Amorphous Silica Nanoparticles Obtained by Laser Ablation Induce Inflammatory Response in Human Lung Fibroblasts

Silica nanoparticles (SiO₂ NPs) represent environmentally born nanomaterials that are used in multiple biomedical applications. Our aim was to study the amorphous SiO₂ NP-induced inflammatory response in MRC-5 human lung fibroblasts up to 72 hours of exposure. The intracellular distribution of SiO₂ NPs was measured by transmission electron microscopy (TEM). The lactate dehydrogenase (LDH) test was used for cellular viability evaluation. We have also investigated the lysosomes formation, protein expression of interleukins (IL-1β, IL-2, IL-6, IL-8, and IL-18), COX-2, Nrf2, TNF-α, and nitric oxide (NO) production. Our results showed that the level of lysosomes increased in time after exposure to the SiO₂ NPs. The expressions of interleukins and COX-2 were upregulated, whereas the expressions and activities of MMP-2 and MMP-9 decreased in a time-dependent manner. Our findings demonstrated that the exposure of MRC-5 cells to 62.5 µg/mL of SiO₂ NPs induced an inflammatory response.

Molecular and immunological toxic effects of nanoparticles

Nanoparticles have emerged as a boon for the public health applications such as drug delivery, diagnostic, and imaging. Biodegradable and non-bio degradable nanoparticles have been used at a large scale level to increase the efficiency of the biomedical process at the cellular, animal and human level. Exponential use of nanoparticles reinforces the adverse immunological changes at the human health level. Physical and chemical properties of nanoparticles often lead to a variety of immunotoxic effects such as activation of stress-related genes, membrane disruption, and release of pro-inflammatory cytokines. Delivered nanoparticles in animal or human interact with various components of the immune system such as lymphocytes, macrophages, neutrophils etc. Nanoparticles delivered above the threshold level damages the cellular physiology by the generation of reactive oxygen and nitrogen species. This review article represents the potential of nanoparticles in the field of nanomedicine and provides the critical evidence which leads to develop immunotoxicity in living cells and organisms by altering immunological responses.

Genotoxicity of synthetic amorphous silica nanoparticles in rats following short-term exposure. Part 1: oral route

Synthetic amorphous silica (SAS) in its nanosized form is now used in food applications although the potential risks for human health have not been evaluated. In this study, genotoxicity and oxidative DNA damage of two pyrogenic (NM-202 and 203) and two precipitated (NM-200 and -201) nanosized SAS were investigated in vivo in rats following oral exposure. Male Sprague Dawley rats were exposed to 5, 10, or 20 mg/kg b.w./day for three days by gavage. DNA strand breaks and oxidative DNA damage were investigated in seven tissues (blood, bone marrow from femur, liver, spleen, kidney, duodenum, and colon) with the alkaline and the (Fpg)-modified comet assays, respectively. Concomitantly, chromosomal damage was investigated in bone marrow and in colon with the micronucleus assay. Additionally, malondialdehyde (MDA), a lipid peroxidation marker, was measured in plasma. When required, a histopathological examination was also conducted. The results showed neither obvious DNA strand breaks nor oxidative damage with the comet assay, irrespective of the dose and the organ investigated. Similarly, no increases in chromosome damage in bone marrow or lipid peroxidation in plasma were detected. However, although the response was not dose-dependent, a weak increase in the percentage of micronucleated cells was observed in the colon of rats treated with the two pyrogenic SAS at the lowest dose (5 mg/kg b.w./day). Additional data are required to confirm this result, considering in particular, the role of agglomeration/aggregation of SAS NMs in their uptake by intestinal cells.

Use of whole genome expression analysis in the toxicity screening of nanoparticles

The use of nanoparticles (NPs) offers exciting new options in technical and medical applications provided they do not cause adverse cellular effects. Cellular effects of NPs depend on particle parameters and exposure conditions. In this study, whole genome expression arrays were employed to identify the influence of particle size, cytotoxicity, protein coating, and surface functionalization of polystyrene particles as model particles and for short carbon nanotubes (CNTs) as particles with potential interest in medical treatment. Another aim of the study was to find out whether screening by microarray would identify other or additional targets than commonly used cell-based assays for NP action. Whole genome expression analysis and assays for cell viability, interleukin secretion, oxidative stress, and apoptosis were employed. Similar to conventional assays, microarray data identified inflammation, oxidative stress, and apoptosis as affected by NP treatment. Application of lower particle doses and presence of protein decreased the total number of regulated genes but did not markedly influence the top regulated genes. Cellular effects of CNTs were small; only carboxyl-functionalized single-walled CNTs caused appreciable regulation of genes. It can be concluded that regulated functions correlated well with results in cell-based assays. Presence of protein mitigated cytotoxicity but did not cause a different pattern of regulated processes.

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Regulated functions were screened using whole genome expression assays.

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Polystyrene particles regulated more genes than short carbon nanotubes.

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Protein coating of polystyrene particles did not change regulation pattern.

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Functions regulated by microarray were confirmed by cell-based assay.

Nanomedicine as an innovative therapeutic strategy for pediatric lung diseases

Nanomedicine is a rapidly emerging technology and represents an innovative field for therapy. Nanomaterials have intrinsically defined features for biomedical applications due to the high specific surface area, the amazing diversity, versatility in structure and function and the possibility of surface charge. In particular, the functionalization of targeting or stimuli-responsive unit on the surface of these materials gives them specific targeted therapeutic properties. There are many pediatric lung diseases that could potentially benefit from nanomedicine. Herein, we aim to review various drug carrier systems and release systems specifically targeting pediatric lung diseases. The injection of nanomedicine into in vivo models and their elimination will also be discussed. Finally, the potential toxicity of nanomaterials will be addressed.

Cytokine production by co-cultures exposed to monodisperse amorphous silica nanoparticles: the role of size and surface area

The aim of this study was to test the influence of nanoparticle size and surface area (SA) on cytokine secretion by co-cultures of pulmonary epithelial cells (A549), macrophages (differentiated THP-1 cells) and endothelium cells (EA.hy926) in a two-compartment system. We used monodisperse amorphous silica nanoparticles (2, 16, 60 and 104 nm) at concentrations of 5 μg/cm² cell culture SA or 10 cm² particle SA/cm². A549 and THP-1 cells were exposed to nanoparticles for 24h, in the presence of EA.hy926 cells cultured in an insert introduced above the bi-culture after 12h. Supernatants from both compartments were recovered and TNF-α, IL-6, IL-8 and MIP-1α were measured. Significant secretion of all cytokines was observed for the 2 nm particles at both concentrations and in both compartments. Larger particles of 60 nm induced significant cytokine secretion at the dose of 10 cm² particle SA/cm². The use of multiple cellular types showed that cytokine secretion in single cell cultures is amplified or mitigated in co-cultures. The release of pro-inflammatory mediators by endothelial cells not directly exposed to nanoparticles indicates a possible endothelium activation after inhalation of silica particles. This work shows the role of size and SA in cellular response to amorphous nanosilica.