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Updated: Sep 22, 2025
Isolation of Cortical Microglia with Preserved Immunophenotype and Functionality From Murine Neonates
Published on: January 30, 2014
HMGB1-NLRP3-P2X7R pathway participates in PM2.5-induced hippocampal neuron impairment by regulating microglia
Chong Liu1, Yingjie She1, Jia Huang1
1School of Basic Medical Sciences, Experimental Center for Medical Research, Neurologic Disorders and Regeneration Repair Lab of Shandong Higher Education, Weifang Medical University, Weifang, China.
Abstract:
Neuroinflammation is a key mechanism underlying the cognitive impairment induced by PM2.5, and activated microglia plays an important role in this process. However, the mechanisms by which activated microglia induced by PM2.5 impair hippocampal neurons have not been fully elucidated. In this study, we focused on the role of HMGB1-NLRP3-P2X7R pathway which mediated the microglia activation in hippocampal neurons impairment induced by PM2.5 using a co-culture model of microglia and hippocampal neurons. We found that PM2.5 resulted in activated microglia and HMGB1-NLRP3 inflammatory pathway, and elevated proinflammatory cytokines of IL-18 and IL-1β in a dose-dependent manner. Notably, we next utilized previously reported pharmacological inhibitors or siRNA for HMGB1 and found that they significantly inhibited the activation of downstream NLRP3 and MAPK pathways derived from PM2.5 exposure, and down-regulated IL-18 and IL-1β in microglia. Furthermore, we employed co-cultured hippocampal neurons and microglia and found that reducing HMGB1 significantly decreased neuron impairment, apoptosis related protein of cl-caspase3, synaptic damage, and neurotransmitter receptor of 5-HT2A, along with notably elevated presynaptic and postsynaptic proteins of SYP and PSD-95, as well as learning and memory related proteins of p-CREB and BDNF. The neuronal impairment induced by PM2.5 could not be prevented in the case of simultaneous employment of HMGB1 siRNA and NLRP3 agonist. After silencing NLRP3 alone in microglia, hippocampal neurons demonstrated decreased excessive autophagy and up-regulated synaptic protein of GAP43 as well as learning and memory related protein of NCAM1. Therefore, we further studied how hippocampal neurons affected microglia under PM2.5 exposure, Further investigation indicated that silencing HMGB1 could affect the activation of P2X7R and reduce the release of ATP from hippocampal neurons, thus protecting the interaction between microglia and hippocampal neurons. The present work suggests that regulation of HMGB1-NLRP3-P2X7R pathway can inhibit the microglia activation induced by PM2.5 to alleviate hippocampal neuron impairment and stabilize the microenvironment between microglia and neurons. This contributes to maintaining the normal function of hippocampal neurons and alleviating the cognitive impairment derived from PM2.5 exposure.
Insights
Exposure to fine particulate matter (PM2.5) triggers neuroinflammation and cognitive decline. Targeting the HMGB1-NLRP3-P2X7R pathway in microglia can protect hippocampal neurons from PM2.5-induced damage.
Area of Science:
- Neuroscience
- Toxicology
- Cell Biology
Background:
- Particulate matter (PM2.5) exposure is linked to cognitive impairment.
- Neuroinflammation, driven by activated microglia, is a key mechanism in this impairment.
- The precise mechanisms of PM2.5-induced microglial activation and subsequent hippocampal neuron damage remain unclear.
Purpose of the Study:
- To investigate the role of the HMGB1-NLRP3-P2X7R pathway in PM2.5-induced neuroinflammation and hippocampal neuron impairment.
- To elucidate the molecular mechanisms by which PM2.5 affects microglia-neuron interactions.
- To identify potential therapeutic targets for mitigating PM2.5-related cognitive deficits.
Main Methods:
- Utilized a co-culture model of microglia and hippocampal neurons.
- Administered PM2.5 exposure to the co-culture system.
- Employed pharmacological inhibitors and small interfering RNA (siRNA) targeting HMGB1 and NLRP3.
- Assessed microglial activation, inflammatory cytokine release (IL-18, IL-1β), neuronal apoptosis, synaptic integrity, and expression of key proteins (SYP, PSD-95, p-CREB, BDNF).
Main Results:
- PM2.5 exposure dose-dependently activated microglia and the HMGB1-NLRP3 pathway, increasing IL-18 and IL-1β.
- HMGB1 inhibition significantly reduced NLRP3 and MAPK pathway activation, decreased inflammatory cytokines, and protected neurons from impairment, apoptosis, and synaptic damage.
- Silencing NLRP3 in microglia reduced neuronal autophagy and improved synaptic and learning/memory related proteins.
- HMGB1 reduction also affected P2X7R activation and ATP release from hippocampal neurons, preserving microglia-neuron interactions.
Conclusions:
- The HMGB1-NLRP3-P2X7R pathway is crucial in mediating PM2.5-induced microglial activation and hippocampal neuron impairment.
- Targeting this pathway can inhibit PM2.5-induced neuroinflammation and protect cognitive function.
- Modulating HMGB1 and NLRP3 offers a potential therapeutic strategy against PM2.5-related cognitive deficits.
