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P14 | Immune Handling of PET Nanoplastics in Pomacea Canaliculata: Accumulation by Circulating and Tissue-resident Hemocytes Following Acute Exposure
Summary
Scientists exposed freshwater snails to nanoplastics (tiny plastic particles smaller than a speck of dust, similar to those found in bottled water and everyday items) and found that immune cells quickly captured and stored the particles in the snails' kidneys without causing visible damage in the short term. While this is animal research, not human research, it matters because it shows how immune systems in living creatures actively respond to nanoplastics rather than ignoring them—raising questions about what happens with longer-term exposure, including in humans, where microplastics have already been found in blood and organs.
The contamination of freshwater ecosystems by nanoplastics (NPs) is a growing concern, yet the eco-immunological responses of freshwater invertebrates remain largely unexplored. We characterized the short-term fate and immunological impact of fluorescently labelled Polyethylene terephthalate (PET)-NPs (Nile Red, mean diameter 82 nm) in the eco-immunological model Pomacea canaliculata, a freshwater snail with remarkable physiological resilience and a well-characterised innate immune system. Animals were injected in foot with 5 or 10 mg/L PET-NPs and sacrificed at 24 or 72 hours post-injection (hpi). Fluorescence microscopy on cryosections revealed rapid PET-NPs accumulation in both kidneys, persisting up to 72 hpi independently of dose. Despite clear particle accumulation, histological examination showed no signs of tissue damage. Transcriptional analysis of stress (Pc-HSP70, Pc-HSP90) and immune (Pc-AIF1) markers revealed no organ-specific modulations, with downregulation at 72 hpi in the lower dose group. Circulating hemocytes from injected animals showed internalized PET-NPs in both adherent cells displaying pseudopodia and smaller, round hemocytes. Intercellular particle transfer via cytoplasmic protrusions was also observed, as reported in other mollusks. Ex vivo phagocytosis experiments confirmed a positive correlation between PET-NP concentration and phagocytic activity, significantly reduced by anticoagulant treatment, supporting active NPs internalization. These findings indicate that P. canaliculata rapidly sequesters PET-NPs in immune-associated tissues through hemocyte-mediated mechanisms, with limited short-term physiological impact. This study promotes P. canaliculata as a resilient model for eco-immunological research on NPs and lays the groundwork for future investigations into chronic exposure and immune modulation.Acknowledgements: This work was supported by the PRIN (PNRR) project NANOPIN, Mission 4 cod. 2022SAHTRX – CUP E53D23007600006.