Lipidomic analysis of mussel hemocytes exposed to polystyrene nanoplastics

Plastics production and usage has exponentially increased in the last decades around the world. Due to the insufficient waste management, a significant amount of plastic ends up in the environment, where they tend to fragment into micro- and nano-plastics (NPs), and accumulate in aquatic organisms with still unknown effects. Although studies have indicated that lipid metabolism is a main target of NPs, this mechanism has not been extensively explored. In this study, we evaluated changes in the lipidome of mussel hemocytes after exposure to polystyrene (PS) NPs of 50 and 500 nm, at two different concentrations (106 and 109 particles/mL) for 24 h. The lipidome of hemocytes, analyzed by FIA-ESI (±) Orbitrap, was characterized by a relatively high abundance of cholesteryl esters (CEs) and phosphatidylcholine-plasmalogens (PC–Os/PC-Ps), involved in cell's defense against oxidative stress and membrane reorganization. In hemocytes exposed to PS NPs, a number of highly unsaturated membrane lipids were down-regulated, indicating a reorganization of the cell membranes after exposure to the particles and an oxidation of lipids with a high number of double bonds. This reduction was more evident after exposure to 50 nm NPs –both concentrations- and 500 nm NPs –high concentration–. The analysis of culture medium suggested increased release of vesicles enriched in triglycerides (TGs). The relevance of these responses to NP exposure on the immune function of hemocytes remains to be investigated.This work was supported by Basque Government through a grant to the consolidated research group Cell Biology in Environmental Toxicology (IT1302-19 and IT1743-22), Spanish Ministry of Economy and Competitiveness project NACE (CTM 2016-81130-R), EU JRC CAS6 project “Towards a technological platform for nanoplastics detection” (CAS Project 30602) and project Ref. PGC 2018-097513-B-I00 [Ministerio de Ciencia, Innovación y Universidades (MCIU), la Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER)]. C. Porte is member of the SusPlast platform from the Spanish National Research Council (CSIC)