Ambient fine
particulate matter (PM) is a global public and environmental problem. PM is closely associated with several neurological diseases, which typically involve
neuroinflammation. We investigated the impact of PM exposure on
neuroinflammation using both in vivo (in a juvenile rat model with PM exposure concentrations of 1, 2, and 10 mg/kg for 28 days) and in vitro (in BV-2 and HT-22 cell models with PM concentrations of 50-200 μg/ml for 24 h). We observed that PM exposure induced the activation of the NLRP3
inflammasome, leading to the production of IL-1β and
IL-18 in the rat hippocampus and BV-2 cells. Furthermore, inhibition of the NLRP3
inflammasome with
MCC950 effectively reduced
neuroinflammation and ameliorated hippocampal damage. In addition, autophagy activation was observed in the hippocampus of PM-exposed rats, and the promotion of autophagy by
rapamycin (Rapa) effectively attenuated the NLRP3-mediated
neuroinflammation induced by PM exposure. However, autophagic flow was blocked in BV-2 cells exposed to PM, and Rapa failed to ameliorate NLRP3
inflammasome activation. We found that autophagy was activated in HT-22 cells exposed to PM and that treatment with Rapa reduced the release of
reactive oxygen species (ROS) and
malondialdehyde (MDA), as well as cell apoptosis. In a subsequent coculture model of BV-2 and HT-22 cells, we observed the activation of the NLRP3
inflammasome in BV-2 cells when the HT-22 cells were exposed to PM, and this activation was alleviated when PM-exposed HT-22 cells were pretreated with Rapa. Overall, our study revealed that PM exposure triggered hippocampal
neuroinflammation by activating the NLRP3
inflammasome. Notably, autophagy mitigated NLRP3
inflammasome activation, potentially by reducing neuronal ROS and apoptosis. This research emphasized the importance of reducing PM exposure and provided valuable insight into its neurotoxicity.