Abstract 362: Endothelial Increase In Autotaxin Regulates Cerebral Vascular Permeability During Ischemic Reperfusion

Abstract

Introduction: Pathological progression of stroke is aided by ischemic reperfusion during the treatment procedure. Various molecular signals initiated during ischemic reperfusion exacerbates the disease leading to endothelial permeability. However, a detailed molecular therapeutic regimen with r-TPA and mechanical thrombectomy could limit the detrimental effects. Lysophosphatidic acid (LPA) is a bioactive phospholipid regulated in physiological and pathological conditions. LPA is produced by the enzyme autotaxin (ATX). ATX-LPA axis have been observed to deteriorate physiological status in various diseases. In cerebral ischemic-reperfusion, the ATX-LPA axis could regulate the endothelium disruption. Hypothesis: Increased ATX expression in endothelium disrupts the endothelial barrier by increasing LPA during ischemic-reperfusion. Methods: For the in-vitro study, oxygen and glucose deprivation and reperfusion (OGDR) were carried out in mouse brain microvascular endothelial cells (MBMEC).For invivo transient middle cerebral artery occlusion with 90 minutes of ischemia and 24 hours of reperfusion (I/R) was used as a stroke model in mice. Electric Cell Substrate Impedance System (ECIS) and Evan Blue was used for permeability study for invitro and invivo respectively. AR-2 probe fluorescence assay was used to measure ATX activity. Results: ATX expression was increased (P<0.05) in MBMEC with OGDR suggesting ATX regulation in endothelial cells following ischemic-reperfusion. Permeability measured with ECIS in MBMEC showed that LPA treatment increased the permeability in a time and concentration-dependent manner. The protein levels of junctional proteins such as βcatenin, Claudin5, VEcadherin, and Zo1 weresignificantly (P<0.05) decreased with LPA exposure. In invivo stroke model ATX enzymatic activity is prominently raised (P<0.01) in I/R mice compared to sham mice. Increased ATX activity coheres with the Evans Blue permeability in the mice brain. Simultaneously LPA levels are elevated in I/R mice. LPA produced during the process can disrupt the blood-brain barrier, increasing cerebral permeability. Conclusion: Inhibition of the ATX-LPA axis prospects to be a better therapeutic avenue for cerebral ischemic reperfusion.