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Updated: Jun 28, 2025
Isolation of Cortical Microglia with Preserved Immunophenotype and Functionality From Murine Neonates
Published on: January 30, 2014
PM2.5 exposure upregulates pro-inflammatory protein expression in human microglial cells via oxidant stress and
Ling Zhang1, Fei Xu1, Yishu Yang1
1Henan International Collaborative Laboratory for Health Effects and Intervention of Air Pollution, School of Public Health, Xinxiang Medical University, Xinxiang, Henan Province 453003, China.
Abstract:
Exposure to ambient PM2.5 is associated with neurodegenerative disorders, in which microglia activation plays a critical role. Thus far, the underlying mechanisms for PM2.5-induced microglia activation have not been well elucidated. In this study, a human microglial cell line (HMC3) was used as the in vitro model to examine the inflammatory effect (hall marker of microglia activation) of PM2.5 and regulatory pathways. The expression of inflammatory mediators including interleukin-6 (IL-6) and cyclooxygenase-2 (COX-2) as well as the brain derived neurotrophic factor (BDNF) were determined by ELISA and/or real-time PCR, respectively. Flow cytometry was used to measure the production of intracellular reactive oxygen species (ROS). Western blot was used to measure protein levels of Toll-like receptor 4 (TLR4), NF-κB inhibitor α (IκBα) and COX-2. It was shown that PM2.5 stimulation increased IL-6 and COX-2 expression but decreased BDNF expression in a dose-dependent manner. Further studies showed that PM2.5 triggered the formation of ROS and pre-treatment with the ROS scavenger acetylcysteine (NAC) significantly suppressed PM2.5-induced IL-6 and COX-2 expression. Moreover, the nuclear factor kappa B (NF-κB) inhibitor BAY11-7085 or the TLR4 neutralizing antibody markedly blocked PM2.5-induced IL-6 and COX-2 expression. However, NAC or BAY11-7085 exhibited minimal effect on PM2.5-induced BDNF down-regulation. In addition, pre-treatment with BAY11-7085 or TLR4 neutralizing antibody reduced ROS production induced by PM2.5, and NAC pre-treatment inhibited TLR4 expression and NF-κB activation induced by PM2.5. Collectively, PM2.5 treatment induced IL-6 and COX-2 but suppressed BDNF expression. PM2.5-induced IL-6 and COX-2 expression was mediated by interactive oxidative stress and TLR4/NF-κB pathway.
Insights
Exposure to fine particulate matter (PM2.5) activates microglia, increasing inflammation and decreasing neuroprotective factors. This process involves oxidative stress and the Toll-like receptor 4/nuclear factor-kappa B pathway, contributing to neurodegeneration.
Area of Science:
- Neuroscience
- Environmental Health
- Toxicology
Background:
- Microglia activation is central to neurodegenerative disorders.
- Ambient PM2.5 exposure is linked to neurodegeneration, but mechanisms are unclear.
- Understanding PM2.5 effects on microglia is crucial for neuroprotection.
Purpose of the Study:
- To investigate the mechanisms of PM2.5-induced microglia activation.
- To examine the role of oxidative stress and the TLR4/NF-κB pathway.
- To assess the impact of PM2.5 on inflammatory mediators and BDNF.
Main Methods:
- Utilized human microglial cell line (HMC3) as an in vitro model.
- Measured inflammatory mediators (IL-6, COX-2) and BDNF expression via ELISA and qPCR.
- Assessed reactive oxygen species (ROS) production by flow cytometry and protein levels by Western blot.
Main Results:
- PM2.5 dose-dependently increased IL-6 and COX-2, while decreasing BDNF.
- PM2.5 induced ROS production; NAC, BAY11-7085, and TLR4 antibody mitigated inflammation.
- NAC and BAY11-7085 had minimal effect on BDNF downregulation, suggesting distinct pathways.
Conclusions:
- PM2.5 induces microglia activation, characterized by increased IL-6/COX-2 and decreased BDNF.
- PM2.5-induced inflammation is mediated by oxidative stress and the TLR4/NF-κB pathway.
- Targeting these pathways may offer therapeutic strategies for PM2.5-related neuroinflammation.
