Inflammatory cells and cytokines in the Olfactory Bulb of a rat model of neuroinflammation; Insights into neurodegeneration?

Abstract

This study examined inflammatory cell and cytokine production in brain tissue from a lipopolysaccharide (LPS) treated rat model that mimics many of the neuropathologic changes associated with neurodegenerative diseases. We monitored the appearance of glial cell line‐derived neurotrophic factor (GDNF) and circulating nitric oxide (NO) levels, as well as immune system associated cells in a selected area of the brain, the olfactory lobe. Our hypothesis was that LPS treatment stimulates temporal changes within the brain and these responses included immune cell recruitment, increased tissue levels of immune modulating cytokines and NO, as well as greater glial cell activation resulting in increased production of GDNF. Our animal model of systemic LPS treatment lead to an increase in the concentrations of circulating cytokines including TNF‐α, IL‐Iβ and IL‐6, with a maximum response 6 hours post LPS. Concomitant with cytokine elevations, circulating NO levels were elevated for several hours post LPS. Brain content of GDNF was also elevated over a similar time frame. Lymphocytes, neutrophils, macrophages, plasma cells and cytokines were all seen in various areas of LPS treated brains. Our results suggest an involvement of both the peripheral and the central nervous system immune components in response to inflammation and inflammatory episodes.