AG and SD contributed equally to this work.
Proinflammatory mediators released by activated microglia induces neuronal death in Japanese encephalitis
Article first published online: 3 JAN 2007
Copyright © 2007 Wiley-Liss, Inc.
Volume 55, Issue 5, pages 483–496, 1 April 2007
How to Cite
Ghoshal, A., Das, S., Ghosh, S., Mishra, M. K., Sharma, V., Koli, P., Sen, E. and Basu, A. (2007), Proinflammatory mediators released by activated microglia induces neuronal death in Japanese encephalitis. Glia, 55: 483–496. doi: 10.1002/glia.20474
- Issue published online: 26 JAN 2007
- Article first published online: 3 JAN 2007
- Manuscript Accepted: 22 NOV 2006
- Manuscript Received: 19 JUL 2006
- Department of Biotechnology. Grant Number: BT/PR/5799/MED/14/698/2005
While a number of studies have documented the importance of microglia in central nervous system (CNS) response to injury, infection and disease, little is known regarding its role in viral encephalitis. We therefore, exploited an experimental model of Japanese Encephalitis, to better understand the role played by microglia in Japanese Encephalitis Virus (JEV) infection. Lectin staining performed to assess microglial activation indicated a robust increase in reactive microglia following infection. A difference in the topographic distribution of activated, resting, and phagocytic microglia was also observed. The levels of various proinflammatory mediators, such as inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (Cox-2), IL-6, IL-1β, TNF-α, and MCP-1 that have been implicated in microglial response to an activational state was significantly elevated following infection. These cytokines exhibited region selective expression in the brains of infected animals, with the highest expression observed in the hippocampus. Moreover, the expression of neuronal specific nuclear protein NeuN was markedly downregulated during progressive infection indicating neuronal loss. In vitro studies further confirmed that microglial activation and subsequent release of various proinflammatory mediators induces neuronal death following JEV infection. Although initiation of immune responses by microglial cells is an important protective mechanism in the CNS, unrestrained inflammatory responses may result in irreparable brain damage. Our findings suggest that the increased microglial activation following JEV infection influences the outcome of viral pathogenesis. It is likely that the increased microglial activation triggers bystander damage, as the animals eventually succumb to infection. © 2007 Wiley-Liss, Inc.