Exploring the role of reactive astrocytes in brain inflammation using a novel combinatorial strategy

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SUMMARY (from R01DA048815). While numerous transgenic tools and approaches exist for manipulation of gene expression in many cell types found in a healthy brain, tools designed to target and study cells present only in the diseased or damaged brain are lacking. Common to virtually all neurodegenerative diseases, brain injuries and infections are neuroinflammatory and immune responses characterized by changes in astrocytes. These cells ordinarily provide critical support for neurons, but become reactive astrocytes (RAs) in brain disease and inflammation. A longstanding and still unresolved issue is whether RAs contribute to or help alleviate disease progression. The objective of this application is to deliver to the neuroscience community a new combinatorial transgenic strategy and toolkit to specifically target RAs in disease. This toolkit will enable researchers to selectively alter (i.e., eliminate, increase, or decrease) gene expression only in RAs at any point in the progression of brain disease and inflammation. Astrocyte populations from acute and chronic methamphetamine use will be analyzed. Three aims are proposed: In Aim 1, we will characterize the Cre transgenic strategy to selectively manipulate gene expression only in RAs in diseased brains. In Aim 2, we will use the new approach to selectively ablate, prevent, or reprogram RAs into non-RAs at various stages of the acute and chronic inflammatory processes. Our work will provide new information on the role of RAs in the early vs. sustained stages of brain inflammation. In Aim 3, we will perform “translatome” analysis to identify the genes uniquely altered in reactive astrocytes during brain inflammation for the first time, providing novel targets for future study. Our innovative approach will allow detection of both inductions and reductions in gene expression with unprecedented signal-to-noise over existing approaches. The rationale for the proposed research is that improving understanding of the cellular and molecular mechanisms of brain disease will provide novel insights for the development of more effective treatments. We anticipate that this research will be transformative, as we will introduce to the research community a powerful new strategy to investigate the role of reactive cell types in any disease or disorder of the nervous system.