Diesel exhaust particles have been found to disrupt the functions of microglia, the brain’s immune cells, according to a study by the University of Eastern Finland. Published in Environment International, the research highlights how traffic-related air pollution may contribute to brain inflammation and neurodegenerative diseases.
The study utilised human induced pluripotent stem cell-derived microglia (iMGLs) to examine the effects of diesel particles from various engines and fuels. Findings indicated that particles from older engines with outdated emission controls caused significant transcriptional and functional changes in microglia. In contrast, particles from renewable diesel in Euro 6-compliant vehicles had minimal impact.
Microglia are crucial for clearing cellular debris and maintaining brain homeostasis. Disruption of these processes can lead to chronic neuroinflammation, elevating the risk of neurodegenerative diseases. Dr. Sohvi Ohtonen, the study’s first author, stated, “Microglia are the brain’s first line of defense. We observed that particles from diesel engines with older emission technology significantly impaired microglial functions, including waste clearance and inflammation control. Although modern filtration systems reduce these harmful effects, traffic-related pollution remains a serious health concern.”
Diesel particles, rich in black carbon and polycyclic aromatic hydrocarbons (PAHs), activated stress and immune signalling pathways such as TREM1 and Toll-like receptor signalling. The affected microglia exhibited impaired lysosomal function and phagocytosis, essential processes for maintaining a healthy brain environment.
While modern emission controls appear to mitigate the most harmful effects on microglia, the study underscores that prolonged exposure to diesel pollution could heighten the risk of neuroinflammation and neurodegenerative diseases through chronic alterations in microglial activity.
This research received funding from the European Union’s Horizon 2020 and MSCA COFUND programmes, the Research Council of Finland, and the Päivikki and Sakari Sohlberg Foundation. Czech partners were funded by the Ministry of Education, Youth and Sports of the Czech Republic and the European Structural and Investments Funds.
