The Weinstein Laboratory
Dr. Jonathan Weinstein is the principal investigator of the Weinstein Laboratory in the Department of Neurology, University of Washington School of Medicine. The main focus of research in the Weinstein lab is to elucidate the role of microglial cell activation in the neuroinflammatory response associated with ischemic preconditioning and stroke. Ischemic preconditioning (IPC) in the brain is a robust neuroprotective phenomenon in which a brief ischemic exposure increases resistance to the injurious effects of subsequent prolonged ischemia. Microglia (Fig. 1), the brain's resident tissue macrophages, are the primary mediators of neuroinflammation and are critical in the pathophysiology of stroke. Mechanistic information on the function of microglia in ischemia is limited and the role of microglia in IPC is unknown. All projects in our laboratory focus on characterizing the role of microglia in both IPC and stroke.
Stroke is the leading cause of serious long-term disability in the United States and few stroke patients qualify for the only FDA approved therapy, IV tPA. Thus, our ultimate goal is to improve the understanding of the mechanisms of neuroinflammation in stroke and identify possible molecular targets for therapeutic intervention.
The Weinstein Lab employs both in vivo and in vitro experimental models of ischemia to study microglial responses. For our in vivo studies, we couple the mouse middle cerebral artery occlusion (MCAO) stroke model with ex vivo flow cytometric isolation of microglia from cortex. In order to determine infarct volume in our stroked mice we use both MRI and standard histological methods (Fig.2).
We carry out cell targeted microarray analyses on the sorted cortical microglia (Fig.3). Using this approach we are able to compare the microglial response to IPC/ischemia in wild-type mice with that of microglia in selected knockout and transgenic lines. Correspondingly, we are able to elucidate the effects of experimental treatments on a variety of outcome parameters.
For our in vitro experimental paradigm we expose cultured primary mouse microglia to hypoxic/hypoglycemic conditions and then we monitor an array of experimental parameters. Past studies have included characterizing the cellular consequences of microglial activation by the blood coagulation proteinase thrombin -- an important factor in stroke pathophysiology. Our more recent work has implicated both Toll-like receptor-4 (TLR4) and type 1 interferon (IFN)-stimulated genes as key mediators of the microglial response to ischemia/IPC. Both TLR4 and the IFN family of cytokines are recognized as key components of the innate immune response. Ongoing projects in our laboratory are examining how disruption of the TLR4 and/or type 1 IFN signaling pathways, specifically in microglia, can affect both IPC and stroke.