Abstract TP326: Nitro-Oleic Acid Ameliorates Blood-Brain Barrier Disruption and Promotes Neurovascular Protection After Ischemic Stroke

Abstract

Introduction: Nitro-oleic acid (OA-NO 2 ), a nitroalkene formed in nitric oxide-dependent oxidative reactions, has been found in human plasma and is thought to regulate pathophysiological functions. Recently, accumulating evidence suggests that OA-NO 2 may function as an anti-inflammatory mediator, and ameliorate the progression of diabetes and cardiovascular diseases. However, the role of OA-NO 2 in ischemic brain injury remains unexplored. Hypothesis: OA-NO 2 stabilizes the blood-brain barrier (BBB), and is a neurovascular-protective regulator in ischemic brain injury. Methods: C57BL/6 mice were subjected to 1h transient middle cerebral artery occlusion (MCAO) followed by 24-72h reperfusion. These mice were intravenously treated with vehicle, OA or OA-NO 2 at 2h after the onset of MCAO. BBB integrity was assessed by using fluorescent-dextrans. Brain water content was measured by using a dry-wet method. Brain infarct was analyzed by 2%TTC staining or anti-map2 immunostaining. Infiltration of peripheral immune cells into brain parenchyma were examined by immunofluorescent methods. Total RNA was extracted from brain tissues and the expression of BBB tight junctions (TJs) and pro-inflammatory cytokines was detected by qPCR, Western blotting, and ELISA. Results: Compared to OA and vehicle controls, intravenous administration of OA-NO 2 led to reduced BBB leakage in ischemic brains, evidenced by significantly reduced extravasation of BBB tracers and less brain water content. OA-NO 2 treated mice also exhibited a smaller brain infarct and improved neurological functions in response to ischemic insults. Also, OA-NO 2 significantly reduced BBB leakage-triggered infiltration of neutrophils and macrophages in the ischemic brains. Mechanistically, OA-NO 2 increased major endothelial TJs including Claudin 5 and ZO-1 levels in stroke mice. Treatment of OA-NO 2 also significantly inhibited stroke-induced pro-inflammatory cytokines, IL-6 and MCP-1, in mouse brains. Conclusions: OA-NO 2 preserves BBB integrity and confers neurovascular protection in ischemic brain damage. OA-NO 2 -mediated brain protection may help us to develop a novel therapeutic strategy for the treatment of ischemic stroke.