Cytokine Production and Cellular Localization in a Murine Model of Brain Inflammation

Brain inflammation is typically involved in the pathogenesis of acute conditions such as stroke and brain trauma and in chronic neurodegenerative diseases, for instance, Alzheimer’s disease. Accordingly, a well-characterized in vivo model of brain inflammation can be a useful tool to evaluate specific drug effects focused on various inflammation targets in the pharmaceutical drug discovery process. A model of brain inflammation was induced by the injection of β-amyloid peptide (αβ) or the bacterial endotoxin lipopolysaccharide (LPS) into the lateral ventricles of CD-I mice. The time course and dose response kinetics of cytokine and chemokine production were characterized. Levels of the pro-inflammatory cytokines IL-1α, IL-1β, IL-6 and the chemokine MCP-1 were significantly increased with respect to both time and dose in the cortex and hippocampus as determined by ELISA. Immunohistochemical assays were developed to detect IL-1β to determine cellular localization of this cytokine to microglia and astrocytes. Astrocytes were labeled with antibodies to glial fibrillary acidic protein (GFAP) and microglia were labeled with F4/80 antibodies. IL-1β was localized to cell type in frozen sections using double immunofluorescence (IMF) tags and were visualized with traditional fluorescence and confocal imaging.