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TNF-alpha has proved to be a successful target in the treatment of many peripheral inflammatory diseases, but the same interventions worsen immune-mediated CNS disease. However, anti-TNF-alpha strategies may offer promise as therapy for non-immune CNS injury. In this study, we have microinjected IL-1beta or lipopolysaccharide (LPS) into the rat brain as a simple model of brain injury and have systemically administered the TNF-alpha antagonist etanercept to discover whether hepatic TNF-alpha, produced as part of the acute-phase response to CNS injury, modulates the inflammatory response in the brain. We report a significant reduction in neutrophil numbers recruited to the IL-1beta- or LPS-challenged brain as a result of TNF-alpha inhibition. We also show an attenuation in the levels of hepatic mRNA including TNF-alpha mRNA and of TNF-alpha-induced genes, such as the chemokines CCL-2, CXCL-5, and CXCL-10, although other chemokines elevated by the injury were not significantly changed. The reduction in hepatic chemokine synthesis results in reduced numbers of circulating neutrophils, and also a reduction in the numbers recruited to the liver as a consequence of brain injury. These findings suggest that TNF-alpha inhibitors may reduce CNS inflammatory responses by targeting the hepatic acute-phase response, and thus therapies for brain injury need not cross the blood-brain barrier to be effective.

Original publication

DOI

10.1111/j.1471-4159.2007.04928.x

Type

Journal

J Neurochem

Publication Date

12/2007

Volume

103

Pages

2245 - 2255

Keywords

Acute Disease, Acute-Phase Reaction, Animals, Brain, Brain Injuries, Chemokines, Disease Models, Animal, Encephalitis, Etanercept, Gene Expression Regulation, Immunoglobulin G, Immunosuppressive Agents, Inflammation Mediators, Liver, Male, Rats, Rats, Wistar, Receptors, Tumor Necrosis Factor, Tumor Necrosis Factor-alpha