Potential Impact Of Nanoplastics On The Immune System And Associated Effects In Mice

The hazards of plastic particles to human health are well recognized.Large plastics that persist in the environment can decompose into microplastics(less than 5 mm)or nanoplastics(less than 1μm)after physical or chemical reactions.A large body of evidence indicates the ingestion of plastic particles by many aquatic and terrestrial organisms.Plastic particles have also been detected in human faeces and placentas.Recently,the role of plastic particles has been extensively studied in animals such as mice and rats.However,little is known about how plastic particles shape the immune environment once they enter the body.In this study,we got plastic particles of different sizes,from 500 nm to 2 μm,and evaluated their immunological effects in vivo by gavage them to mice.The research content is as follows:Chapter 1:The issue of plastic particle pollution in the environment and daily life was briefly described.The biological effects and mechanisms induced by the ingestion of plastic particles in vivo and in vitro were briefly summarized,and the research progress of the intestinal immune system was briefly summarized.Finally,the basis for the topic selection and research content of this thesis were discussed.Chapter 2:In this chapter,the characterization of plastic particles with different sizes was investigated.Scanning electron microscopy(SEM)and transmission electron microscopy(TEM)were used to observe the morphology of the plastic particles.Dynamic light scattering(DLS)showed the particle sizes of the two types of plastic particles.The chemical properties of plastic particles were analyzed by infrared spectroscopy and Zeta potential detection.Biological transmission electron microscopy was used to observe the phagocytosis of different plastic particles by macrophages.In addition,the characterization of the plastic particles after treatment with the lysosome mimic solution was also observed and analyzed.Chapter 3:We confirmed that micro-/nano-plastics but not microplastics caused lysosomal damage by confocal imaging and flow cytometry,and further explored the activation of lysosomal damage pathway by Western blot and enzyme-linked immunosorbent assay(ELISA).Finally,cytochalasin was used to inhibit cell phagocytosis to alleviate the micro-/nanoplastic-induced lysosomal damage and inflammatory cytokine release.Chapter 4:In a gavage mice model,the effect of plastic particles ingestion on intestinal immunity was investigated.Flow cytometry analysis was used to analyze the intestinal immune cell population after microplastic and nanoplastic treatment.Meanwhile,the antibiotic elimination experiment was used to investigate whether the interference of nanoplastics on intestinal immunity was dependent on the role of gut microbes.Chapter 5:In this chapter,we further used single-cell mRNA sequencing analysis to characterize the intestinal immune cell population at the gene level.In addition,an orthotopic mouse CT26 colon tumor model was constructed to explore whether the uptake of nanoplastics promoted tumor growth.Chapter 6:In the chronic gavage mice model of nanoplastics,behavioral changes,neuron damage,microglia activation and Th 17 cell differentiation were observed。Chapter 7:Study rescue strategies in a variety of therapeutic models including neutralizing IL-1β,blocking IL-1 signaling,inhibition of NLRP3 inflammasome,or interrupt nanoplastic uptake.The therapeutic effects of several models were confirmed by observing the behavior of mice and examining the related immune indexes of brain tissue.Chapter 8:Further studies on the in vitro and in vivo effects of another type of plastic,polystyrene nanoplastics,such as the activation of lysosomal damage pathways,immune environment analysis of the gut and brain,were conducted.In summary,our work provides a novel insight into the mechanism of gut-brain axis,delineates the brain damage caused by nanoplastics by disrupting intestinal immunity,leading to cognitive and memory impairment in mice,and highlights the importance of addressing the global plastic pollution problem.