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Many components of the innate immune system are evolutionarily conserved and shared across many living organisms, from plants and invertebrates to humans. Therefore, these shared features can allow the comparative study of potentially dangerous substances, such as engineered nanoparticles (NPs). However, differences of methodology and procedure between diverse species and models make comparison of innate immune responses to NPs between organisms difficult in many cases. To this aim, this review provides an overview of suitable methods and assays that can be used to measure NP immune interactions across species in a multidisciplinary approach. The first part of this review describes the main innate immune defense characteristics of the selected models that can be associated to NPs exposure. In the second part, the different modes of exposure to NPs across models (considering isolated cells or whole organisms) and the main endpoints measured are discussed. In this synergistic perspective, we provide an overview of the current state of important cross-disciplinary immunological models to study NP-immune interactions and identify future research needs. As such, this paper could be used as a methodological reference point for future nano-immunosafety studies. All authors were supported by the EU H2020 project PANDORA, grant number 671881.

In this PhD thesis, the effects and interactions of nanoparticles-NPs with the marine mussel Mytilus galloprovincialis were investigated through several exposure pathways, implying the use of distinct methods, in vitro and in vivo. In a first part, in vitro model served to determine the functional immune responses upon short term exposure of Mytilus hemocytes using microscopy and spectrophotometric methods. In this line, several NPs were tested in suspensions in ASW-artificial seawater and hemolymph serum-HS and showed a general activation of the immune response of Mytilus hemocytes and hemolymph components (Chapter 1 and 2). The results obtained contribute to understand the mechanisms of actions of NPs due to their nature, size and coating and also underline the importance to consider the exposure medium in the characterization and exposure experiment. Complementary experiments were carried on the change in morphology after interactions with NPs, attesting for peculiar activation of the hemocytes according to the NPs types. In a second part, the effects of NPs were also investigated at different scale of the organism (from cell to tissues) using in vivo experiments, in which mussels were exposed for several days to selected NPs, before determining immune parameters and related parameters. Mussels exposed in vivo to nanoceria-nCeO2 (Chapter 3), showed specific immunomodulatory and antioxidant effects at different levels of biological organization in the absence of Cerium tissue accumulation. In addition, the microbiota present in hemolymph of mussels has shown to be affected upon nanotitanium dioxide-nTiO2 exposure (Chapter 4). The results attested for complex interactions between immune cells, the hemocytes, activated in presence of nTiO2, and created an unfriendly medium in hemolymph, that likely lead to affect the most sensible commensal bacterial communities present. Finally, newly design experiments were performed to investigate innate immune memory/training in Mytilus (Chapter 5). Growing proofs have shown that even relying on innate response, molluscs could present a certain type of memory and recall a response upon a second encounter, also called innate immune memory. Results showed that mussels can mount a more effective response upon re-exposure to a stimulus, PS-NH2 in the present case, to avoid to trigger further stress/damages repeatedly.

This conference report describes the training activities that took place in the frame of the Integrated in Situ Chemical MApping probe (SCHeMA) summer school organized from the 14th to the 16th of June 2016 in Bilbao (Spain)

This conference report describes the training activities that took place in the frame of the Integrated in Situ Chemical MApping probe (SCHeMA) summer school organized from the 14th to the 16th of June 2016 in Bilbao (Spain).

It is now recognized that host microbiome, the community of microorganisms that colonize the animal body (e.g. microbiota) and their genomes, play an important role in the health status of all organisms, from nutrient processing to protection from disease. In particular, the complex, bilateral interactions between the host innate immune system and the microbiota are crucial in maintaining whole body homeostasis. The development of nanotechnology is raising concern on the potential impact of nanoparticles-NPs on human and environmental health. Titanium dioxide-nTiO2, one of the most widely NP in use, has been shown to affect the gut microbiota of mammals and fish, as well as to potentially alter microbial communities. In the marine bivalve Mytilus galloprovincialis, nTiO2 has been previously shown to interact with hemolymph components, thus resulting in immunomodulation. However, no information is available on the possible impact of NPs on the microbiome of marine organisms. Bivalves host high microbial abundance and diversity, and alteration of their microbiota, in both tissues and hemolymph, in response to stressful conditions has been linked to a compromised health status and susceptibility to diseases. In this work, the effects of nTiO2 exposure (100 μg/L, 4 days) on Mytilus hemolymph microbiota were investigated by 16S rRNA gene-based profiling. Immune parameters were also evaluated. Although hemolymph microbiota of control and nTiO2-treated mussels revealed a similar core composition, nTiO2 exposure affected the abundance of different genera, with decreases in some (e.g. Shewanella, Kistimonas, Vibrio) and increases in others (e.g. Stenotrophomonas). The immunomodulatory effects of nTiO2 were confirmed by the increase in the bactericidal activity of whole hemolymph. These represent the first data on the effects of NPs on the microbiome of marine invertebrates, and suggest that the shift in hemolymph microbiome composition induced by nTiO2 may result from the interplay between the microbiota and the immune system This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement PANDORA N° 671881 and the EU project H2020 VIVALDI grant number N° 678589 SI