Abstract TP245: Unfavorable Role Of Autotaxin Lysophosphatidic Acid Axis During Ischemic Reperfusion In Stroke.

Abstract

Introduction: Stroke is a leading cause of death, also serious cause of long-term disability in the US. r-TPA and mechanical thrombectomy apply to 5-10% of patients, while others have the risk of intracerebral hemorrhage. Ischemic reperfusion following stroke exacerbates the condition and initiates various molecular signals. However, with a better therapeutic regimen, the detrimental effects can be limited. Lysophosphatidic acid (LPA) is a bioactive phospholipid regulated in physiological and pathological conditions. LPA is formed by the enzyme Autotaxin (ATX). ATX-LPA axis affects endothelial permeability in ischemic stroke. Hypothesis: ATX-LPA axis favors endothelial permeability in ischemic stroke. Methods: 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. LPA was analyzed in plasma with mass spectrometry and in tissue with immunohistochemistry. AR-2 probe fluorescence assay was used to measure ATX activity. Evans Blue Permeability in vivo was measured with infrared imager. Mitochondrial bioenergetics was measured with an XF24 analyzer. Permeability was studied using Electric Cell Substrate Impedance System (ECIS). Results: ATX enzymatic activity is prominently raised 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 (P<0.01) in I/R mice. LPA was increased in brain tissue along the vasculature, indicating an unfavorable role of ATX in maintaining endothelial integrity. LPA receptors were regulated differentially following stroke. Permeability measured in MBMEC showed that LPA treatment increased the permeability in a time and concentration-dependent manner. LPA treatment also increased superoxide in MBMEC suggesting redox imbalance with LPA exposure. Mitochondrial superoxide elevated following I/R was limited with ATX inhibitors which also restricted the permeability compared to that of the I/R mice Conclusion: LPA produced by ATX plays a significant role in ischemic stroke, increasing BBB permeability and elevating mitochondrial dysfunction. Targeting the ATX-LPA axis could be a better therapeutic avenue for stroke management.