University Honors

Exposure to airborne fungal allergens has been increasingly recognized as a potential environmental factor influencing neuroimmune function. We use the airborne fungal allergen, Alternaria alternata, to examine how such exposure to the allergen affects microglial morphology and population within the nucleus tractus solitarii (NTS) of the brainstem, a critical region involved in autonomic respiratory regulation. To simulate he environment of the fungal allergen polluted air, mice were exposed to the ultrafine aerosolized non-infectious particulates of A. alternata in chambers for one week. After the mice were exposed, whole brains were collected and the NTS regions of the brainstem were cryosectioned 5 micrometers. To identify the presence of microglia and their processes, the brainstem slices used ionized calcium-binding adapter molecule-1 (Iba-1) labeling. There were three methods of microglial activity analysis: single-cell tracing, long-axis measurement, and population quantification. After immunofluorescence confocal microscopy, single-cells were 3-dimensionally reconstructed using the Neurolucida software and analyzed using Sholl analysis. The Sholl analysis suggests there were no significant change in microglial morphology between control and A. alternata exposed male mice. Long-axis measurements of microglial process length and population quantification was conducted using the FIJI software. Long-axis measurements of single-cell microglia in NTS also showed no significant change between control and A. alternata male mice. In addition to single-cell analyses, microglial population quantifications showed no significant changes between control and A. alternata mice, for both sexes of mice. We conclude that males continue to show no changes in morphology when exposed to the fungal allergen A. alternata in NTS, where future analysis of female mice may show sex-specific differences in microglial activity and morphology expression.