Peptide composition of stroke causing emboli correlate with serum Markers of atherosclerosis and inflammation

Abstract

Introduction: The specifc protein composition of stroke-causing emboli is unknown. Because ischemic stroke has a varied etiology, it is possible that the composition of the thrombus from which an embolus originated will have distinctive molecular characteristics refective of the underlying pathophysiology. We used mass spectrometry to evaluate the protein composition of retrieved emboli from patients with differing stroke etiologies and correlated the protein levels to serum predictors of atherosclerosis. Methods: Emboli from 20 consecutive acute stroke patients were retrieved by thrombectomy during routine stroke care. Thrombus proteins were extracted, digested, and multidimensional fractionation of peptides was performed. Fractionated peptides underwent nano-liquid chromatography with tandem mass spectrometry. Spectra were searched using Mascot software in which results with p < 0.05 (95% confdence interval) were considered signifcant and indicating identity. The results were correlated to A1C, low-density lipoprotein (LDL), and erythrocyte sedimentation rate (ESR) taken on admission. results: Eleven patients had atrial fbrillation, four had signifcant proximal vessel atherosclerosis, two were cryptogenic, and three had other identifed stroke risk factors (left ventricular thrombus, dissection, endocarditis). Eighty-one common proteins (e.g., hemoglobin, fbrin, actin) were found in all 20 emboli. Serum LDL levels correlated with Septin-2 (rs = 0.78, p = 0.028), Phosphoglycerate Kinase 1 (rs = 0.75, p = 0.036), Integrin Alpha-M (rs = 0.68, p = 0.033) and Glucose-6-phosphate dehydrogenase (rs = 0.63, p = 0.05). Septin-7 levels inversely correlated to ESR (rs = -0.84, p = 0.01). No signifcant protein correlations to A1C or tPA use were found. conclusion: Our exploratory study presents mass spectrometry analysis of thrombi retrieved from acute stroke patients and correlates the thrombus proteome to clinical features of the patient. Notably, we found proteins associated with infammation (e.g., Integrin Apha-M) in emboli from patients with high LDL. Although these fndings are tempered by a small sample size, we provide preliminary support for the feasibility of utilizing proteomic analysis of emboli to discover proteins that may be used as markers for stroke etiology.