The Constituent-Dependent Translocation Mechanism for PM<sub>2.5</sub> to Travel through the Olfactory Pathway
Sheng Wei, Ting Xu, Miao Cao, Huan Wang, Yiqun Song, Daqiang Yin
Abstract
High Resolution Image Download MS PowerPoint Slide The neurotoxic risk of PM 2.5 is of worldwide concern, but the pathways through which PM 2.5 gets to the central nervous system are still under debate. The olfactory pathway provides a promising shortcut to the brain, which bypasses the blood–brain barrier for PM 2.5 . However, direct evidence is lacking, and the translocation mechanism is still unclear. This study used the primary murine olfactory sensory neurons (OSNs) as an in vitro model to explore the translocation mechanism of PM 2.5 in the olfactory system. We found that PM 2.5 can be internalized into the OSNs via vesicle transportation. This process responds only to the water-insoluble compositions of PM 2.5 (WIS-PM 2.5 ) and cannot be affected by the water-soluble compositions of PM 2.5 (WS-PM 2.5 ). PM 2.5 can further disrupt the integrity of the barrier constituted by the OSNs, and WS-PM 2.5 plays a heightened role in inducing the damages. Our results suggested that both cellular and paracellular pathways are possibly involved in the translocation of PM 2.5 in the olfactory system. More advanced microscopy techniques need to be developed to explore the whole translocation process in the olfactory–brain pathway in both in vitro and in vivo models.