Shift in Immune Parameters After Repeated Exposure to Nanoplastics in the Marine Bivalve Mytilus

Abstract

Bivalves are widespread in coastal environments subjected to a wide range of environmental fluctuations: however, the rapidly occurring changes due to several anthropogenic factors can represent a significant threat to bivalve immunity. The mussel Mytilus spp. has extremely powerful immune defenses toward different potential pathogens and contaminant stressors. In particular, the mussel immune system represents a significant target for different types of nanoparticles (NPs), including amino-modified nanopolystyrene (PS-NH 2) as a model of nanoplastics. In this work, the effects of repeated exposure to PS-NH 2 on immune responses of Mytilus galloprovincialis were investigated after a first exposure (10 µg/L; 24 h), followed by a resting period (72-h depuration) and a second exposure (10 µg/L; 24 h). Functional parameters were measured in hemocytes, serum, and whole hemolymph samples. In hemocytes, transcription of selected genes involved in proliferation/apoptosis and immune response was evaluated by qPCR. First exposure to PS-NH 2 significantly affected hemocyte mitochondrial and lysosomal parameters, serum lysozyme activity, and transcription of proliferation/apoptosis markers; significant upregulation of extrapallial protein precursor (EPp) and downregulation of lysozyme and mytilin B were observed. The results of functional hemocyte parameters indicate the occurrence of stress conditions that did not however result in changes in the overall bactericidal activity. After the second exposure, a shift in hemocyte subpopulations, together with reestablishment of basal functional parameters and of proliferation/apoptotic markers, was observed. Moreover, hemolymph bactericidal activity, as well as transcription of five out of six immune-related genes, all codifying for secreted proteins, was significantly increased. The results indicate an overall shift in immune parameters that may act as compensatory mechanisms to maintain immune homeostasis after a second encounter with PS-NH 2 .

Interaction between Macrophages and Nanoparticles: In Vitro 3D Cultures for the Realistic Assessment of Inflammatory Activation and Modulation of Innate Memory

“…While it is now clear that many NPs do not have the capacity for activating human monocytes if they are endotoxin-free [ 12 , 13 , 35 , 36 , 39 ], some data point to the possibility that they can prime monocytes and induce innate memory, which then changes the secondary reaction of cells to a subsequent stimulation [ 28 , 29 , 30 , 31 , 32 ]. We have examined the capacity of AuNPs to induce innate memory in monocytes from six different donors in 2D and 3D cultures.…”

“…While our understanding of innate memory is still largely incomplete, it is tempting to speculate that engineered NPs might be used for a targeted reprogramming of innate immunity for preventive and therapeutic scopes, such as in vaccination and immunotherapy [ 24 , 25 , 26 , 27 ]. Few recent studies show that indeed NPs may prime human monocytes and vertebrate/invertebrate macrophages and induce a modification of their response to a subsequent inflammatory challenge [ 28 , 29 , 30 , 31 , 32 ]. In this study, we have examined the memory-inducing capacity of AuNPs on human primary monocytes to define the most suitable conditions for a realistic evaluation.…”

Immunotoxicity and intestinal effects of nano- and microplastics: a review of the literature

“…Exposure of mussels to amino-modified PS nanoparticles (50 nm, 10 μg/L) induced changes in hemocytes, depending on the duration of exposure. After a 24 h exposure, the hemocytes presented mitochondrial and lysosomal disturbances [103]. After two 24 h periods of exposure 72 h apart, levels of bactericidal activity and immune-related gene transcription were found to be elevated.…”

Addressing Nanomaterial Immunosafety by Evaluating Innate Immunity across Living Species

“…The results indicate both tolerance and potentiation as compensatory mechanisms to maintain immune homeostasis after a second encounter with PS-NH 2 , representing a form of immune memory. [233] The same forms of innate memory, "tolerance" and "trained immunity/potentiation," are documented in mammals/vertebrates. Although the innate memory can be induced by any type of exposure, most of our knowledge on the tolerance phenomenon comes from study on LPS exposure, while that on trained immunity/potentiation is mainly related to exposure to Bacillus Calmette-Guérin (BCG) or to fungal cell wall β-glucans.…”