Although the link between the inhalation of nanoparticles and cardiovascular disease is well established, the causal pathway between nanoparticle exposure and increased activity of blood coagulation factors remains unexplained. To initiate coagulation tissue factor bearing epithelial cell membranes should be exposed to blood, on the other side of the less than a micrometre thin air-blood barrier. For the inhaled nanoparticles to promote coagulation, they need to bind lung epithelial-cell membrane parts and relocate them into the blood. To assess this hypothesis, we use advanced microscopy and spectroscopy techniques to show that the nanoparticles wrap themselves with epithelial-cell membranes, leading to the membrane’s disruption. The membrane-wrapped nanoparticles are then observed to freely diffuse across the damaged epithelial cell layer relocating epithelial cell membrane parts over the epithelial layer. Proteomic analysis of the protein content in the nanoparticles wraps/corona finally reveals the presence of the coagulation-initiating factors, supporting the proposed causal link between the inhalation of nanoparticles and cardiovascular disease.
Many chronic diseases manifest in prolonged inflammation and often ignored dysregulated lipid metabolism. When associated with inhalation of nanomaterials, limited information is available on the relevant molecular events and their causal connections. This prevents reliable prediction of outcomes by efficient testing strategies. To unravel how acute nanomaterial exposure leads to chronic conditions, we employed advanced microscopy and omics in vitro and in vivo together with in silico modelling.For selected metal-oxide nanomaterials, we show that lung epithelial cells survive the exposure by excreting internalized nanomaterials and passivating them on the surface, employing elevated lipid synthesis. Macrophages, on the contrary, lose their integrity whilst degrading the passivized bio-nano agglomerates, releasing the nanomaterials, which are taken up again by the epithelial cells. Constant proinflammatory signalling recruits new phagocytes that feed the vicious cycle of events, resulting in a long-lasting response to a single exposure. The proposed mechanism explains the nanomaterialassociated in vivo chronic outcomes and allows its prediction based on in vitro measurements. Similar mechanisms may trigger other chronic diseases affecting millions of lives worldwide.
Although electrostatic modification of bacterial surfaces using polyelectrolytes (PEs) is a convenient and versatile tool for biotechnological processes, the ambiguities in toxicity of PEs between various bacteria and the insufficient understanding of the mechanism of action of cationic PEs and their nano-thick shells formed around the bacteria create a bottleneck of the approach. Here, we show how the viability of two bacterial strains, Escherichia coli and Pseudomonas stutzeri, both from the Gram-negative group differs, when the cells are exposed to cationic PEs under different conditions. Although the cell wall architecture of the strains should be structurally similar, we found that the viability of E. coli was not affected by the electrostatic deposition of polyethyleneimine (PEI) or poly(allylamine) hydrochloride (PAH), whereas for P. stutzeri the deposition resulted in high death rates. The cells of E. coli proved to be suitable templates for Layer-by-Layer (LbL) modification, while in P. stutzeri a modified protocol with mild conditions had to be used to ensure the viability of the cells. Super resolution stimulated emission depletion (STED) microscopy allowed us to clearly visualize that after PE deposition onto the surface of the cells, the PEs could penetrate inside the cells of P. stutzeri, while forming a capsule around E. coli as expected. Therefore, this knowledge will help us select the most appropriate combinations of strains and PEs, for biotechnological processes or biomedical application, preventing unwanted toxicity.
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