Sea Urchin Extracellular Proteins Design a Complex Protein Corona on Titanium Dioxide Nanoparticle Surface Influencing Immune Cell Behavior

Abstract

Extensive exploitation of titanium dioxide nanoparticles (TiO2NPs) augments rapid release into the marine environment. When in contact with the body fluids of marine invertebrates, TiO2NPs undergo a transformation and adhere various organic molecules that shape a complex protein corona prior to contacting cells and tissues. To elucidate the potential extracellular signals that may be involved in the particle recognition by immune cells of the sea urchin Paracentrotus lividus, we investigated the behavior of TiO2NPs in contact with extracellular proteins in vitro. Our findings indicate that TiO2NPs are able to interact with sea urchin proteins in both cell-free and cell-conditioned media. The two-dimensional proteome analysis of the protein corona bound to TiO2NP revealed that negatively charged proteins bound preferentially to the particles. The main constituents shaping the sea urchin cell-conditioned TiO2NP protein corona were proteins involved in cellular adhesion (Pl-toposome, Pl-galectin-8, Pl-nectin) and cytoskeletal organization (actin and tubulin). Immune cells (phagocytes) aggregated TiO2NPs on the outer cell surface and within well-organized vesicles without eliciting harmful effects on the biological activities of the cells. Cells showed an active metabolism, no oxidative stress or caspase activation. These results provide a new level of understanding of the extracellular proteins involved in the immune-TiO2NP recognition and interaction in vitro, confirming that primary immune cell cultures from P. lividus can be an optional model for swift and efficient immune-toxicological investigations.

Assessing Sunscreen Lifecycle to Minimize Environmental Risk Posed by Nanoparticulate UV-Filters – A Review for Safer-by-Design Products

“…The existence of a protein corona was detected at the ENM surface upon their entering in the biological medium (Marques-Santos et al, 2018), indicating that the ENMs interact with the components constituting the biological medium, which alters both their bioavailability and toxicity. Similar interaction was also observed with commercial TiO 2 UV-filters exposed to the P. lividus immune cells in vitro (Alijagic et al, 2019;Catalano, 2020). Cellular responses seem to depend on the composition of the corona in vivo and in vitro.…”

“…Cellular responses seem to depend on the composition of the corona in vivo and in vitro. For example, the main constituents of the protein corona on the surface of TiO 2 NP exposed to the supernatant of cultured sea urchin immune cells were identified as a subset of adhesion and cytoskeletal proteins (Alijagic et al, 2019). Primary sea urchin immune cell cultures show how simplified cell model can inform our understanding of complex networks in intact organism on focusing on the role of extracellular protein/peptide molecules/metabolites/other signals involved in cellular communication and potential particle functionalization (Pinsino and Alijagic, 2019).…”

The Crucial Role of Environmental Coronas in Determining the Biological Effects of Engineered Nanomaterials

“…[209] Likewise, protein corona on TiO 2 NPs formed in the celomic fluid of sea urchins have been found to contain many proteins involved in cellular adhesion, cytoskeletal organization, and immune response. [210]…”

Addressing Nanomaterial Immunosafety by Evaluating Innate Immunity across Living Species

“…The phagocytes of the sea urchin interact with NM (e.g., TiO 2 NP) by internalizing them both in vivo and in vitro. [16][17][18] These cells have a dendritic-like morphology and are the most abundant cell type present in the sea urchin body cavity fluid (>80%). Upon interaction with NM, sea urchin phagocytic cells potently respond with active phagocytosis, becoming strongly adherent and metabolically active.…”

“…Upon coating with these proteins, TiO 2 NP aggregated on the outer cell surface of phagocytes and were then internalized within well-organized vesicles without eliciting harmful effects. [16] Overall, data so far obtained in invertebrates indicate that, in each species, NM can be coated by different and peculiar proteins, which makes the biological implications less straightforward. [45] In addition, the results obtained in marine invertebrates suggest that the net surface charge retained by different NM in biological fluids is an important factor in the formation of a stable surface coating and for the consequent interaction with immune cells.…”