Abstract WP18: Nanoparticulate Matter Exposure Induces Mature Oligodendrocyte Cell Death And Promotes Oligodendrocyte Precursor Cell Proliferation

Introduction: Particulate matter exposure (PM), a component of air pollution, promotes neuroinflammation and oxidative stress, which can result in white matter injury. In response to injury, oligodendrocyte precursor cells (OPCs) proliferate and can differentiate into mature oligodendrocytes (mOL). This study aims to characterize the differential effect of nanoparticulate matter (nPM) exposure on OPCs and mOLs in a murine model. Hypothesis: We hypothesize that nPM exposure will induce OPC proliferation and result in mOL cell death. Methods: nPM (diameter ≤200nm) was collected near an urban area in Los Angeles heavily impacted by traffic-related emissions and re-aerosolized for exposure. Mice (C57BL6/J) aged 10 weeks were exposed to filtered air (FA) or nPM for 5 hours/ day, 3 days/ week, for 10 weeks (150 hours) (n=12/group). Total oligodendrocytes in the corpus callosum were assessed with Olig2 immunofluorescence. OPCs in the corpus callosum were assessed using immunofluorescent double-stains of Olig2 with platelet derived growth factor receptor alpha (PDGFRα). mOLs in the corpus callosum were assessed using immunofluorescent double-stains of Olig2 with CNPase. Two-tailed unpaired Student’s t-tests were used to analyze differences between nPM and FA cohorts. Data shown as mean ± standard deviation, units=cells/mm 2 . Results: Total oligodendrocyte cell counts in the corpus callosum were decreased in the nPM (679±88) group compared to FA (811±148, p=0.01). OPC cell counts in the corpus callosum were increased in the nPM cohort (87±12) compared to FA (72±21, p<0.05). mOL cell counts in the corpus callosum were decreased in the nPM group (420±71) compared to FA (602±123, p<0.001). Conclusions: nPM exposure induces mOL cell death and promotes OPC proliferation in the corpus callosum. Overall, oligodendrocytes are decreased in the corpus callosum following nPM exposure. These results suggest that an OPC maturation block may occur following nPM exposure.