Stressor-Dependant Changes in Immune Parameters in the Terrestrial Isopod Crustacean, Porcellio scaber: A Focus on Nanomaterials

Abstract

We compared the changes of selected immune parameters of Porcellio scaber to different stressors. The animals were either fed for two weeks with Au nanoparticles (NPs), CeO2 NPs, or Au ions or body-injected with Au NPs, CeO2 NPs, or lipopolysaccharide endotoxin. Contrary to expectations, the feeding experiment showed that both NPs caused a significant increase in the total haemocyte count (THC). In contrast, the ion-positive control resulted in a significantly decreased THC. Additionally, changes in phenoloxidase (PO)-like activity, haemocyte viability, and nitric oxide (NO) levels seemed to depend on the stressor. Injection experiments also showed stressor-dependant changes in measured parameters, such as CeO2 NPs and lipopolysaccharide endotoxin (LPS), caused more significant responses than Au NPs. These results show that feeding and injection of NPs caused an immune response and that the response differed significantly, depending on the exposure route. We did not expect the response to ingested NPs, due to the low exposure concentrations (100 μg/g dry weight food) and a firm gut epithelia, along with a lack of phagocytosis in the digestive system, which would theoretically prevent NPs from crossing the biological barrier. It remains a challenge for future research to reveal what the physiological and ecological significance is for the organism to sense and respond, via the immune system, to ingested foreign material.

Time-Course of the Innate Immune Response of the Terrestrial Crustacean Porcellio scaber After Injection of a Single Dose of Lipopolysaccharide

“…Body injections of P. scaber were performed between the 5th and 6th dorsal pereon segment using a 25-µL microsyringe (702N series, 33-gauge, blunt tip; Hamilton, Bonaduz, Switzerland) and a repeating dispenser (PB 600-1; Hamilton, Bonaduz, Switzerland), as described by Mayall et al. ( 20 ). The trauma control group was injected with 0.5 µL Dulbecco’s phosphate-buffered saline (DPBS; pH 7.1–7.5) and the experimental group was injected with the same volume of a sublethal dose of LPS (from Escherichia coli O111:B4; Sigma-Aldrich) dissolved in DPBS at a final concentration of 0.5 μg/μL.…”

“…In particular, studies on crustaceans stimulated with LPS have shown strong immunomodulatory changes (i.e., changes in immune-related parameters), indicating an induction of the immune system as a result of cytotoxicity of LPS ( 12 , 15 , 16 , 22 ). LPS-induced effects reported in most studies include a decrease in THC ( 12 , 16 ), changes in DHC ( 12 , 15 ), increased production of reactive oxygen species (ROS) and reactive nitrogen species (RNS; e.g., NO) ( 22 – 24 ), and decreased hemocyte viability ( 16 , 20 ). In addition, LPS-induced degranulation and release of components of the prophenoloxidase (proPO) system from hemocytes have also been reported, which leads to increased phenoloxidase activity ( 16 , 25 ).…”

Cross-Species Comparisons of Nanoparticle Interactions with Innate Immune Systems: A Methodological Review

“…There is the possibility for an alternative exposure scenario, with injection experiments delivering substances directly into the animals hemocoel, allowing for the study of the direct interaction of a known concentration of NPs with the hemocytes. This ensures NP and immune cell interaction [141,173].…”

“…Upon detecting a melanized pathogen or object, immune cells quickly encapsulate the material resulting in the elimination of the threat. PO activity can be assessed by monitoring the formation of a reddish-brown pigments in the hemolymph from an individual organism using spectrophotometry [44,173,240]. In bivalves, the presence of PO has been reported but its basal levels, the variation across species and especially its response to NP exposure remain poorly understood [83,255].…”

An Evolutionary and Environmental Perspective of the Interaction of Nanomaterials with the Immune System

“…In many other cases, it is possible to observe an immune reaction, with morphological and functional changes in innate immune cells; however, these changes are not long-lasting and do not hamper the organism’s integrity. This means that a successful immune reaction has taken place, which has recognised the nanomaterials as a possible threat and has acted to eliminate them and re-establish normal tissue/organism functions [ 4 , 5 , 6 , 7 ]. A very important point that should be considered is that exposure to nanomaterials may affect immunity indirectly by interacting with immune-modulating entities.…”