Background: Clinical and epidemiologic studies suggest a relationship between long-term nano-particulate matter (nPM) exposure and white matter injury1. Accumulating laboratory evidence suggests that nPM exposure causes inflammation in multiple brain regions2.
Objective: We sought to study the effects nano-particulate matter exposure on microglia activation and complement upregulation within the corpus callosum in a murine model.
Methods: C57 black 6J mice were randomized to re-aerosolized nPM (n=18, nPM <200 nm) or filtered air (n=18) cohorts. Exposures were conducted for a total of 150 cumulative hours. Post-exposure, brains were harvested and immunohistochemical analysis performed. Reactive microglia (IBA-1), reactive astrocytes (GFAP) and C5α deposition (C5α antibody) were quantified in the medial corpus callosum.
Results: There were significant differences in IBA-1 cell count staining between the groups (filtered air- 94.7± 18.87; nPM- 158.5 ± 41.69, p<0.05). No differences in GFAP cell count staining existed between the filtered air (677.5 ± 96.09) and nPM mice (656.6 ± 120.3, p=ns). There were significant differences in C5α density staining between filtered air (8.181 ± 3.863) and nPM mice (14.77 ± 5.989, p<0.01).
Conclusion: Chronic particulate matter exposure is associated with white matter changes in a murine model. Regional increases in microglia number and C5α deposition suggest an inflammatory mechanism.
References: 1. Calderon-Garciduenas L, Mora-Tiscareno A, Ontiveros E, Gomez-Garza G, Barragan-Mejia G, Broadway J, Chapman S, Valencia-Salazar G, Jewells V, Maronpot RR, Henriquez-Roldan C, Perez-Guille B, Torres-Jardon R, Herrit L, Brooks D, Osnaya-Brizuela N, Monroy ME, Gonzalez-Maciel A, Reynoso-Robles R, Villarreal-Calderon R, Solt AC, Engle RW. Air pollution, cognitive deficits and brain abnormalities: a pilot study with children and dogs. Brain Cogn. 2008;68(2):117-27. 2. Block, M. L., & Calderón-Garcidueñas, L. (2009). Air pollution: mechanisms of neuroinflammation and CNS disease. Trends in neurosciences, 32(9), 506-516.