Proteomic Changes in Intracranial Blood During Human Ischemic Stroke

Abstract

IntroductionSince 2015, mechanical thrombectomy is the standard treatment for emergent large vessel occlusion stroke. The previously published Blood and Clot Thrombectomy Registry and Collaboration (BACTRAC) protocol (clinicaltrials.gov NCT03153683) utilizes thrombectomy to isolate distal blood within the artery immediately downstream from the clot, peripheral blood proximal to the clot, and the thrombus.MethodsTissue samples were obtained in accordance with the established BACTRAC protocol and immediately frozen at −80°C. For this study, we compared the intracranial intraluminal blood distal to the thrombus, using each subject’s systemic arterial blood as an internal comparative control. 40μl aliquots of plasma were thawed and randomized to 96‐well plates and shipped on dry ice to Olink Proteomics (Olink Proteomics, Boston, MA). Cardiometabolic and inflammatory panels were run on 1μl aliquots using a proximity extension assay (PEA) with proximal blood plasma as an internal control for each subject and distal blood plasma as the injury site sample. Protein data were analyzed as average protein expression levels in distal plasma as compared to average protein expression levels in proximal plasma.Results25 adult subjects (>18yrs) were included in the study, of which 15 (60%) were female. Median age was 64 (24–91). 16 subjects (64%) had hypertension, 15 (60%) had BMI > 25, 10 (40%) were active smokers, 6 (24%) had previous stroke, 4 (16%) had type II diabetes, and 4 (16%) had hyperlipidemia. Mean infarct time was 513 ± 246 minutes and mean infarct volume was 58,172 ± 82,284 mm3. Proteins with the greatest change in expression in the cardiometabolic panel were superoxide dismutase 1 (SOD1), CD59, lipocalin‐2 (LCN2), and defensin alpha 1 (DEFA1). Proteins with greatest change in expression in the inflammatory panel were interleukin 4 (IL‐4), AXIN1, interleukin 1 alpha (IL‐1a), sirtuin 2 (SIRT2), interleukin 5 (IL‐5) and leukemia inhibitory factor (LIF). There was a significant sex difference in expression levels of interleukin 20 receptor subunit alpha (IL‐20RA) (p=0.04) and IL‐4 (p=0.03).ConclusionsThese protein data show a complex set of intraluminal responses occurring distal to the thrombus in acute ischemic stroke. Changes in SOD1, LIF, and SIRT2 demonstrate neuroprotective and anti‐inflammatory activity, LCN2 and DEFA1 suggest a response similar to antimicrobial activity, and proteins such as IL‐4 and IL‐5 suggest eosinophil activation and a Th2 phenotype. Future studies will focus on the relationships of proteins with infarct time, infarct volume, and functional outcomes. Such analyses will provide insight into the initial molecular and cell signaling in response to ischemic stroke in the human condition.Support or Funding InformationThe project described was supported by the National Center for Advancing Translational Sciences, through Grant UL1TR001998 and UKHealthCare. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. Grant through Center for Clinical and Translational Science