Abstract WP443: KLF2 Protects Against Ischemic Stroke by Regulating Endothelial Blood Brain Barrier Function
Background During an ischemic stroke normal brain endothelial function is abrogated resulting in blood brain barrier (BBB) breakdown with subsequent infiltration of activated inflammatory blood cells, ultimately leading to neuronal cell death. Kruppel-like factor 2 (KLF2) is regulated by flow, is highly expressed in vascular endothelial cells, and serves as a key molecular switch regulating endothelial function and promoting vascular health.
Purpose To determine the role of KLF2 in ischemic stroke.
Methods and Results—To examine the specific role of KLF2 in the brain and cerebrovascular disease, we performed ischemic strokes and conducted BBB assays in KLF2 deficient (K2-/-), KLF2 overexpressing (K2tg), and control mice. K2-/- mice exhibited larger strokes in the transient middle cerebral artery occlusion model (95% greater stroke volume vs. control; n=10-20/group; P=0.001) and significant impairment in BBB function as assessed by in vivo real time quantitative PET analysis and evans blue dye (EBD) assays (86% greater EBD permeability vs. control; n=3/group; P=0.002). In contrast, K2tg mice were protected against ischemic stroke (49% smaller stroke volume vs. control; n=8-9/group, P=0.004) and demonstrated less impairment in BBB function (30% less EBD permeability vs control; n=3/group; P=0.003). In concordance, gain and loss of function studies in primary brain microvascular ECs using transwell assays revealed KLF2 to be BBB protective (32% less permeability in adenoviral KLF2 overexpression vs. control; P=0.005 and 107% greater permeability in siRNA mediated KLF2 knockdown vs. control; P<0.0005). Mechanistically, KLF2 was demonstrated to regulate the critical BBB tight junction factor occludin, both in vitro (7.0±0.3 fold expression in adenoviral KLF2 overexpression vs. control; P<0.0001 and 0.43±0.03 fold expression in siRNA mediated KLF2 knockdown vs. control; P<0.0005) and in vivo (0.56±0.11 fold expression in K2-/- vs. control; n=4-7/group; P=0.01 and 2.5±0.5 fold expression in K2tg vs. control; n=3-4/group; P<0.05).
Conclusions These data are first to identify KLF2 as a key regulator of brain endothelial function and cerebrovascular homeostasis, thereby serving as a novel neuroprotective factor in ischemic stroke.
- © 2012 by American Heart Association, Inc.