Radiographic markers and therapeutic targets of cerebral edema after SAH

PROJECT SUMMARY/ABSTRACT Subarachnoid Hemorrhage (SAH) is a type of hemorrhagic stroke that affects ~500,000 people annually world- wide and causes significant mortality and long-term disability. Severe cerebral edema (CE) occurs in ~30-40% of SAH and contributes to poor long-term outcomes. Although CE has been implicated as an important pathophysiologic process after SAH, CE targeted therapeutics have not been explored. In this proposal, we address important barriers to the development of therapies targeting CE by 1) using a Dual-energy CT (DECT) based method for measuring brain water content (BWC) to develop a validated measure of CE after SAH and 2) identifying the role of miR-335-3p and miR-5585-5p in the mechanisms of CE after SAH. We have previously developed surrogate markers of CE using sulcal effacement measurements on computed tomography (CT) scans [Selective Sulcal Volume (SSV) and the Subarachnoid Hemorrhage Early Brain Edema Score (SEBES)]. Using these markers, combined with miRNA and proteomic analyses, our preliminary data show elevated miRNAs (miR-335p and miR-5585) and decreased proteins (including SCARA5, GPNMB, and NTRK2) in SAH patients with severe sulcal effacement. These miRNAs are predicted to downregulate Na+/K+ATPase (NKATP) expression as well as the proteins found to be decreased after SAH. NKATP is important for maintenance of cellular membrane potential and has been shown to be downregulated after SAH. Disruption of NKATP has been shown to cause cellular swelling which can lead to CE. Our preliminary data shows elevations in miR-335 and miR-5585, decreased Na/K ATPase α-1 subunit (an essential subunit of NKATP) and increased cellular edema in an in vitro SAH model. We also found miR-335 and miR-5585 elevations in brain tissue in an in vivo model with associated CE measured by MRI and ex-vivo methods. Despite the utility of SSV and SEBES, these markers only measure the sulcal spaces in the brain and are indirect measures of CE, limiting their utility. We have found that CE can be measured in brain parenchyma using DECT. This measure of brain parenchymal water content will address the limitations of indirect markers. We will employ a “bed-to-bench” approach, where a combination of DECT BWC techniques, plasma/cerebrospinal fluid samples and in vivo and in vitro models will be used to test the following specific aims. Aim 1 will test whether BWC is predictive of in-hospital complications and long- term outcomes. We will test if miR-335 and miR-5585 (markers of sulcal effacement) are also markers of BWC and if they are predictive of clinical outcomes. Aim 2 will investigate the mechanism of miR-335 and miR-5585 related CE and if antagonism can ameliorate their detrimental effects in an in vitro and in vivo model. We will perform the clinical study across two centers: UTHealth Houston and University of Maryland Medical Center. The completion of our proposal will establish a validated radiographic technique that represents CE and identify miRNA mediated pathways that can be targeted for future clinical trials to improve outcomes.