Endogenous and exogenous protection of the BBB in stroke. Blood-brain barrier (BBB) dysfunction occurs in a wide variety of neurological diseases and injuries (e.g. stroke). Such dysfunction may participate in those states by enhancing the influx of leukocytes into the brain, allowing the entry of potentially neurotoxic blood components and causing vasogenic edema. In addition, it may affect disease treatment (e.g. hemorrhagic transformation is a major limiting factor for the use of tissue plasminogen activator-induced reperfusion therapy for ischemic stroke). There is, therefore, a great need for methods to protect the BBB. Therapeutic targets may potentially be identified by examining which endogenous mechanisms are altered in disease states. We have shown that preconditioning stimuli can protect the BBB and cerebral endothelial cells in vivo and in vitro. We have also shown that stroke-related factors cause a marked increase in the expression of the cystine/glutamate exchanger (system xc-), a regulator of intracellular glutathione, in cerebral endothelial cells. This exchanger is regulated by nrf2 (an anti-oxidant transcription factor) and xc- can be markedly upregulated by exposure to sulforaphane, an activator of Nrf2 and a component of cruciferous vegetables. These results have led us to hypothesize that: Nrf2 and the proteins it regulates (e.g. xCT, heme oxygenase 1 and ferritin) may be a target for protecting the BBB. As Nrf2 regulation of these proteins requires protein synthesis, we also hypothesize that the function of this system is to protect against delayed BBB disruption, particularly due to migrating leukocytes in ischemia. These hypotheses will be examined in five specific aims: 1+2) Determine whether upregulation of system xc- by stroke-related factors, inflammatory mediators or sulforaphane is protective. 3+4) Determine whether Nrf2 is activated in the cerebral endothelium after stroke or inflammation and whether its activation and the upregulation of downstream proteins will protect the cerebral endothelium. 5) Examines whether treatment with sulforaphane can protect the BBB in vivo.
These specific aims will be examined in vitro, to allow elucidation of molecular mechanisms, and in vivo, to determine pathophysiological relevance. The results should highlight endogenous BBB protective mechanisms and the potential exogenous compounds to activate or inhibit those mechanisms.

Public Health Relevance

Brain blood vessels have very specialized functions, forming a blood-brain barrier. Disuption of that barrier occurs in many neurological disorders and injuries, contributing to brain dysfunction. This proposal examines natural defense mechanisms that may protect the blood-brain barrier, how to activate those mechanisms or prevent their inactivation therapeutically.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
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Brain Injury and Neurovascular Pathologies Study Section (BINP)
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Bosetti, Francesca
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University of Michigan Ann Arbor
Schools of Medicine
Ann Arbor
United States
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Zhou, Ningna; Tang, Yang; Keep, Richard F et al. (2014) Antioxidative effects of Panax notoginseng saponins in brain cells. Phytomedicine 21:1189-95
Xi, Guohua; Hua, Ya; Keep, Richard F (2014) Blood pressure lowering and acute perihematomal brain edema after intracerebral hemorrhage. Stroke 45:1241-2
Xi, Guohua; Strahle, Jennifer; Hua, Ya et al. (2014) Progress in translational research on intracerebral hemorrhage: is there an end in sight? Prog Neurobiol 115:45-63
Sladojevic, Nikola; Stamatovic, Svetlana M; Keep, Richard F et al. (2014) Inhibition of junctional adhesion molecule-A/LFA interaction attenuates leukocyte trafficking and inflammation in brain ischemia/reperfusion injury. Neurobiol Dis 67:57-70
Keep, Richard F; Wang, Michael M; Xiang, Jianming et al. (2014) Full steam ahead with remote ischemic conditioning for stroke. Transl Stroke Res 5:535-7
Keep, Richard F; Xi, G; Hua, Y et al. (2011) Clot formation, vascular repair and hematoma resolution after ICH, a coordinating role for thrombin? Acta Neurochir Suppl 111:71-5
Smith, David E; Hu, Yongjun; Shen, Hong et al. (2011) Distribution of glycylsarcosine and cefadroxil among cerebrospinal fluid, choroid plexus, and brain parenchyma after intracerebroventricular injection is markedly different between wild-type and Pept2 null mice. J Cereb Blood Flow Metab 31:250-61
Xiang, Jianming; Jiang, Huidi; Hu, Yongjun et al. (2010) Kyotorphin transport and metabolism in rat and mouse neonatal astrocytes. Brain Res 1347:11-8
Keep, Richard F; Wang, Michael M; Xiang, Jianming et al. (2010) Is There A Place For Cerebral Preconditioning In The Clinic? Transl Stroke Res 1:4-18
Fisher, Stephen K; Heacock, Anne M; Keep, Richard F et al. (2010) Receptor regulation of osmolyte homeostasis in neural cells. J Physiol 588:3355-64

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