Pathway analysis of systemic transcriptome responses to injected polystyrene particles in zebrafish larvae

Abstract

Microplastics are a contaminant of emergent concern in the environment, however, to date there is a limited understanding on their movement within organisms and the response of organisms. In the current study zebrafish embryos at different development stages were exposed to 700nm fluorescent polystyrene (PS) particles and the response pathway after exposure was investigated using imaging and transcriptomics. Our results show limited spreading of particles within the larvae after injection during the blastula stage. This is in contrast to injection of PS particles in the yolk of 2-day old embryos, which resulted in redistribution of the PS particles throughout the bloodstream, and accumulation in the heart region. Although injection was local, the transcriptome profiling showed strong responses of zebrafish embryos exposed to PS particle, indicating a systemic response. We found several biological pathways activated which are related to an immune response in the PS exposed zebrafish larvae. Most notably the complement system was enriched as indicated by upregulation of genes in the alternative complement pathway (e.g. cfhl3, cfhl4, cfb and c9). The fact that complement pathway is activated indicates that plastic microparticles are integrated in immunological recognition processes. This was supported by fluorescence microscopy results, in which we observed co-localisation of neutrophils and macrophages around the PS particles. Identifying these key events can be a first building block to the development of an adverse outcome pathway (AOP). These data subsequently can be used within ecological and human risk assessment.

Effects of polystyrene microbeads on cytotoxicity and transcriptomic profiles in human Caco‐2 cells

“…Besides, pathway analysis and signal‐net analysis revealed that PI3K/Akt, MAPK, and TNF signaling pathways were strongly influenced . When studying toxic effects of polystyrene microbeads in zebrafish larvae, transcriptome data showed that the genes related to alternative pathways of complement ( cfhl3 , cfhl4 , cfb , and c9 ) were up‐regulated . The combined analysis with the co‐localization of neutrophils and macrophages surround polystyrene microbeads suggested a close connection between MPs and immunological recognition in zebrafish larvae.…”

“…46 When studying toxic effects of polystyrene microbeads in zebrafish larvae, transcriptome data showed that the genes related to alternative pathways of complement (cfhl3, cfhl4, cfb, and c9) were up-regulated. 47 The combined analysis with the co-localization of neutrophils and macrophages surround polystyrene microbeads suggested a close connection between MPs and immunological recognition in zebrafish larvae. Our transcriptome data showed that the inflammatory/immune pathways were deeply influenced by PS-MPs, including PPAR signaling pathways, AMPK signaling pathways, Ras signaling pathway, Phospholipase D signaling pathway, N-Glycan biosynthesis, catalase, GSH, and other enzymes, which is consistent with the study of Lei et al 7 Exposure to some kind of MPs, such as polyamide, polyethylene, polypropylene, PVC, and polystyrene, demonstrated low casualty in Danio rerio but gut mucosa damage on the part of villi disruption and splitting of enterocytes and elevated GST enzyme activity throughout ten days of treatment.…”

Nanoparticles induce dermal and intestinal innate immune system responses in zebrafish embryos

“…Previous studies indi-424 cated, however, that injected PSNPs can activate pathways related to immune responses when 425 injected into the yolk of 2 days old zebrafish embryos (700 nm PSNPs) as well as in fathead 426 minnow plasma (41 nm PSNP). 46,47 Because of the compliment activation by PSNP 46 , a much 427 earlier response by macrophages could occur, which is not captured after 24 h of exposure in 428 this study or alternatively plastic particles might be ingested by non-immune cells which was 429 exemplified by Hosseini and colleagues…”

Transcriptomics in aquaculture: current status and applications

“…Transcriptome analysis of the zebrafish embryo after injecting the polystyrene particles led to the activation of complement system (Veneman et al . ). In the present circumstance of increased application of nanoparticles, liver transcriptome analysis demonstrated the harmful effect of iron oxide nanoparticles (Villacis et al .…”

“…), microplastics (Veneman et al . ; Détrée & Gallardo‐Escárate ), human pharmaceuticals (Hampel et al . ) and pharmaceutical pollutants (Saaristo et al .…”