Microglial activation, recruitment and phagocytosis as linked phenomena in ferric oxide nanoparticle exposure

Microglia as the resident macrophage-like cells in the central nervous system (CNS) play a pivotal role in the innate immune responses of CNS. Understanding the reactions of microglia cells to nanoparticle exposure is important in the exploration of neurobiology of nanoparticles. Here we provide a systemic mapping of microglia and the corresponding pathological changes in olfactory-transport related brain areas of mice with Fe2O3-nanoparticle intranasal treatment. We showed that intranasal exposure of Fe2O3 nanoparticle could lead to pathological alteration in olfactory bulb, hippocampus and striatum, and caused microglial proliferation, activation and recruitment in these areas, especially in olfactory bulb. Further experiments with BV2 microglial cells showed the exposure to Fe2O3 nanoparticles could induce cells proliferation, phagocytosis and generation of ROS and NO, but did not cause significant release of inflammatory factors, including IL-1β, IL-6 and TNF-α. Our results indicate that microglial activation may act as an alarm and defense system in the processes of the exogenous nanoparticles invading and storage in brain.

► Mice were intranasally exposed to Fe2O3 nanoparticles.
► Provide a systemic mapping of microglia and the corresponding pathological changes in brain areas of mice.
► The exposure caused microglia proliferation, activation and recruitment in the brain.
► Induce microglial cells proliferation, phagocytosis and generation of ROS and NO.
► Microglial activation act as an alarm and defense system in the processes of nanoparticles in brain.