Stroke is a major medical concern for United States military veterans. Disruption of the blood-brain barrier (BBB) is a catastrophic event in the pathogenesis of ischemic/reperfusion (I/R) brain injury. Our recent studies suggested that structural alterations in brain endothelial cells (EC), including abnormal actin polymerization and the resulting redistribution of junctional proteins, is a novel mechanism responsible for early BBB leakage after I/R (30 min-3h); while matrix metalloproteinase (MMP) 2/9 activation, a predominant mechanism thought to contribute to post-stroke BBB disruption, contribute to the BBB leakage to larger molecules (>40kDa) in a relatively delayed manner. Therefore, restoring EC structure/function may offer an innovative therapeutic strategy for early BBB protection against I/R, while blocking MMP2/9 may provide a relatively delayed protection to BBB. Heat shock protein 27 (HSP27), a member of the small heat shock protein family, confers neuroprotection in several models of CNS diseases, including I/R brain injury. In addition to its well-known protein chaperone and anti-apoptotic functions, HSP27 may act as a potent actin depolymerization factor in certain cell types such as EC, thus potentially inhibiting actin polymerization-mediated BBB disruption. Further, HSP27 may inhibit the activation of NF-kappaB, a central signaling molecule for the production of MMP2/9 and pro-inflammatory mediators. We recently observed that HSP27 is transiently upregulated in brain EC after I/R. However, the precise role of HSP27 in the functional integrity of EC following I/R and the underlying mechanism remain unknown. Using transgenic mice overexpressing HSP27 and the lentiviral gene-transfection approach, we have obtained novel pilot data showing that HSP27 overexpression protects the endothelium from I/R-induced hyperpermeability in vitro and in vivo; that HSP27 inhibited oxygen glucose deprivation-induced actin polymerization and redistribution of junctional proteins in EC; and that intravenous administration of HSP27 containing a cell permeable transduction domain (TAT-HSP27) enabled rapid delivery of the protein into brain micro-vasculatures, reduced BBB damage and inhibited MMP2/9 activity after I/R. This proposal will further explore the BBB protective effect of HSP27 on I/R brain injury and elucidate the underlying mechanisms. The central hypothesis to be tested is that HSP27 protects BBB against I/R injury by stabilizing EC cytoskeletal organization in microvasculature early after I/R and inhibiting the production of MMP2/9 as well as pro-inflammatory proteins. The following specific aims are proposed:
Aim 1 : To determine whether endothelial targeted overexpression of HSP27 is sufficient to provide early protection on BBB integrity and to confer long term protection against cerebral I/R.
Aim 2 : Test the hypothesis that HSP27 protects endothelial integrity following I/R by dualistic mechanisms: stabilizing the actin cytoskeleton and inhibiting NFkB-dependent MMP2/9 production and inflammation.
Aim 3 : Test the hypothesis that post-stroke delivery of TAT-HSP27 to EC protects against BBB damage and improves outcomes in both young adult and aged mice. The proposed study attempts to develop HSP27 into a novel, clinically feasible therapeutic strategy to ameliorate post-stroke BBB damage, brake down the progression of brain damage, and improve long-term neurological functions in stroke victims. The successful completion of this proposed study will help improve the quality of life for veterans suffering from stroke.

Public Health Relevance

Stroke is a devastating clinical condition for which an effective neuroprotective treatment is currently unavailable. We have identified HSP27 as a promising therapeutic agent for the treatment of ischemic stroke. The objective of this proposal is to investigate whether and how HSP27 protects against the loss of blood brain barrier integrity after ischemic/reperfusion brain injury in both young and aged rodents. This information will be valuable for future development of new therapeutic strategies for the treatment of stroke and, possibly, other neurological disorders.

Agency
National Institute of Health (NIH)
Institute
Veterans Affairs (VA)
Type
Non-HHS Research Projects (I01)
Project #
5I01BX002495-04
Application #
9378086
Study Section
Neurobiology C (NURC)
Project Start
2014-10-01
Project End
2019-09-30
Budget Start
2017-10-01
Budget End
2018-09-30
Support Year
4
Fiscal Year
2018
Total Cost
Indirect Cost
Name
Veterans Health Administration
Department
Type
DUNS #
033127569
City
Pittsburgh
State
PA
Country
United States
Zip Code
15240
Hu, Xiaoming; De Silva, T Michael; Chen, Jun et al. (2017) Cerebral Vascular Disease and Neurovascular Injury in Ischemic Stroke. Circ Res 120:449-471
Mao, Leilei; Li, Peiying; Zhu, Wen et al. (2017) Regulatory T cells ameliorate tissue plasminogen activator-induced brain haemorrhage after stroke. Brain 140:1914-1931
Jiang, Xiaoyan; Andjelkovic, Anuska V; Zhu, Ling et al. (2017) Blood-brain barrier dysfunction and recovery after ischemic stroke. Prog Neurobiol :
Yang, Yuanyuan; Liu, Huan; Zhang, Haiyue et al. (2017) ST2/IL-33-Dependent Microglial Response Limits Acute Ischemic Brain Injury. J Neurosci 37:4692-4704
Cai, Wei; Zhang, Kai; Li, Peiying et al. (2017) Dysfunction of the neurovascular unit in ischemic stroke and neurodegenerative diseases: An aging effect. Ageing Res Rev 34:77-87
Shi, Yejie; Jiang, Xiaoyan; Zhang, Lili et al. (2017) Endothelium-targeted overexpression of heat shock protein 27 ameliorates blood-brain barrier disruption after ischemic brain injury. Proc Natl Acad Sci U S A 114:E1243-E1252
Shi, Yejie; Leak, Rehana K; Keep, Richard F et al. (2016) Translational Stroke Research on Blood-Brain Barrier Damage: Challenges, Perspectives, and Goals. Transl Stroke Res 7:89-92
Zhang, Wenting; Zhang, Hui; Mu, Hongfeng et al. (2016) Omega-3 polyunsaturated fatty acids mitigate blood-brain barrier disruption after hypoxic-ischemic brain injury. Neurobiol Dis 91:37-46
Shi, Yejie; Zhang, Lili; Pu, Hongjian et al. (2016) Rapid endothelial cytoskeletal reorganization enables early blood-brain barrier disruption and long-term ischaemic reperfusion brain injury. Nat Commun 7:10523
Suenaga, Jun; Hu, Xiaoming; Pu, Hongjian et al. (2015) White matter injury and microglia/macrophage polarization are strongly linked with age-related long-term deficits in neurological function after stroke. Exp Neurol 272:109-19