PARTICLE SHAPE AND INTRINSIC CELLULAR VARIABILITY SHAPE THE RESPONSES OF MACROPHAGES TO POLYSTYRENE NANO AND MICRO PARTICLES

International audienceNanoparticles and among them nanoplastics are generally considered to induce more biological effects than bigger particles because of their greater penetration in bodies and cells. Nevertheless, it is known that particles up to a few microns can translocate through the epithelial barriers and be transported to distal organs. As the particles surface and mass increase with the square and the cube of the size, it may be anticipated that microparticles may induce stronger effects than smaller ones, especially when their size begins to approach the size of the cells. To investigate this hypothesis, we exposed macrophages (i.e. cells that are able to scavenge particles over a wide size range) to polystyrene particles of 0.1, 1 and 10 µm in diameter, and analyzed their responses by a proteomic approach. This analysis showed an important common core response for the three particles sizes, but also that larger particles induced a more important response than smaller ones at equal mass concentration. As this suggested a role of the internalized plastic mass in the response, we also investigated an often-overlooked parameter, i.e. the heterogeneity of the cells in their propensity to internalize (plastic) particles. We showed that macrophages vary greatly in their ability to internalize plastic particles. Quite interestingly, “the appetite came with the eating”, so that the final population of cells exposed to a single concentration of plastic particles is indeed a mix of cells with very different loads of internalized plastics. Unsurprisingly, heavily-loaded cells show stronger responses than lightly-loaded cells. We also showed that plastic particles persist in macrophages.When brought together, these data draw a picture where the maintenance of the function of the immune system is assured by the lightly-loaded cells, while the heavily-loaded cells may induce local effects. This balance may change over time in case of continuous exposure, because of particle accumulation

PARTICLE SHAPE AND INTRINSIC CELLULAR VARIABILITY SHAPE THE RESPONSES OF MACROPHAGES TO POLYSTYRENE NANO AND MICRO PARTICLES

International audienceNanoparticles and among them nanoplastics are generally considered to induce more biological effects than bigger particles because of their greater penetration in bodies and cells. Nevertheless, it is known that particles up to a few microns can translocate through the epithelial barriers and be transported to distal organs. As the particles surface and mass increase with the square and the cube of the size, it may be anticipated that microparticles may induce stronger effects than smaller ones, especially when their size begins to approach the size of the cells. To investigate this hypothesis, we exposed macrophages (i.e. cells that are able to scavenge particles over a wide size range) to polystyrene particles of 0.1, 1 and 10 µm in diameter, and analyzed their responses by a proteomic approach. This analysis showed an important common core response for the three particles sizes, but also that larger particles induced a more important response than smaller ones at equal mass concentration. As this suggested a role of the internalized plastic mass in the response, we also investigated an often-overlooked parameter, i.e. the heterogeneity of the cells in their propensity to internalize (plastic) particles. We showed that macrophages vary greatly in their ability to internalize plastic particles. Quite interestingly, “the appetite came with the eating”, so that the final population of cells exposed to a single concentration of plastic particles is indeed a mix of cells with very different loads of internalized plastics. Unsurprisingly, heavily-loaded cells show stronger responses than lightly-loaded cells. We also showed that plastic particles persist in macrophages.When brought together, these data draw a picture where the maintenance of the function of the immune system is assured by the lightly-loaded cells, while the heavily-loaded cells may induce local effects. This balance may change over time in case of continuous exposure, because of particle accumulation

How Reversible Are the Effects of Fumed Silica on Macrophages? A Proteomics-Informed View.

International audienceSynthetic amorphous silica is one of the most used nanomaterials, and numerous toxicological studies have studied its effects. Most of these studies have used an acute exposure mode to investigate the effects immediately after exposure. However, this exposure modality does not allow the investigation of the persistence of the effects, which is a crucial aspect of silica toxicology, as exemplified by crystalline silica. In this paper, we extended the investigations by studying not only the responses immediately after exposure but also after a 72 h post-exposure recovery phase. We used a pyrolytic silica as the test nanomaterial, as this variant of synthetic amorphous silica has been shown to induce a more persistent inflammation in vivo than precipitated silica. To investigate macrophage responses to pyrolytic silica, we used a combination of proteomics and targeted experiments, which allowed us to show that most of the cellular functions that were altered immediately after exposure to pyrolytic silica at a subtoxic dose, such as energy metabolism and cell morphology, returned to normal at the end of the recovery period. However, some alterations, such as the inflammatory responses and some aldehyde detoxification proteins, were persistent. At the proteomic level, other alterations, such as proteins implicated in the endosomal/lysosomal pathway, were also persistent but resulted in normal function, thus suggesting cellular adaptation

Influences of Nanoparticles Characteristics on the Cellular Responses: The Example of Iron Oxide and Macrophages

International audienceIron oxide nanoparticles/microparticles are widely present in a variety of environments, e.g., as a byproduct of steel and iron degradation, as, for example, in railway brakes (e.g., metro station) or in welding fumes. As all particulate material, these metallic nanoparticles are taken up by macrophages, a cell type playing a key role in the innate immune response, including pathogen removal phagocytosis, secretion of free radical species such as nitric oxide or by controlling inflammation via cytokine release. In this paper, we evaluated how macrophages functions were altered by two iron based particles of different size (100 nm and 20 nm). We showed that at high, but subtoxic concentrations (1 mg/mL, large nanoparticles induced stronger perturbations in macrophages functions such as phagocytic capacity (tested with fluorescent latex microspheres) and the ability to respond to bacterial endotoxin lipopolysaccharide stimulus (LPS) in secreting nitric oxide and pro-cytokines (e.g., Interleukin-6 (IL-6) and Tumor Necrosis Factor (TNF)). These stronger effects may correlate with an observed stronger uptake of iron for the larger nanoparticles

How reversible are the effects of silver nanoparticles on macrophages? A proteomic-instructed view

International audienceSilver nanoparticles are known to strongly affect biological systems, and numerous toxicological studies have investigated their effects. Most of these studies examine the effects immediately following acute exposure. In this work, we have conducted further investigation by studying not only the acute, post-exposure response, but also the cellular response after a 72 hour-recovery-phase post exposure. As a biological model we have used macrophages, which are very important cells with respect to their role in the immune response to particulate materials. To investigate the response of macrophages to nanoparticles and their recovery post exposure, we have used a combination of proteomics and targeted experiments. These experiments provided evidence that the cellular reaction to nanoparticles, including the reaction during the recovery phase, is a very active process involving massive energy consumption. Pathways such as the oxidative stress response, central and lipid metabolism, protein production and quality control are strongly modulated during the cellular response to nanoparticles, and restoration of basic cellular homeo-stasis occurs during the recovery period. However, some specialized macrophage functions, such as lipopolysaccharide-induced cytokine and nitric oxide production, did not return to their basal levels even 72 hours post exposure, showing that some effects of silver nanoparticles persist even after exposure has ceased