Abstract WMP113: Red Blood Cells From Stroke Patients With Admission Hyperglycemia Induces Brain Endothelial Dysfunction

Abstract

Background: Beyond its traditional role as oxygen carriers, red blood cells (RBCs) are increasingly recognized to participate in regulating vascular function. Many RBC disorders, such as sickle cell disease, are associated with vascular complications resulting in stroke. Our recent study revealed that admission hyperglycemia in stroke patients intensifies oxidative stress in RBCs. We hypothesize that RBCs that are altered by hyperglycemia may perturb endothelial function. Method: Brain endothelial cells were incubated with RBCs isolated from stroke patients with admission hyperglycemia (hyper-RBC) and normoglycemia (normo-RBC) (n=3/group). Mass spectrometry was used to profile the changes in endothelial cells. Functional alterations were assessed by gene set enrichment analysis (GSEA). Significant changes were verified using qPCR and western blot. Result: Compared to normo-RBC, hyper-RBC activates cell adhesion process and toll like receptor signaling in brain endothelial cells (Fig A, B). Cell adhesion molecules (ICAM1, VCAM1) and toll like receptor TLR4 were upregulated at both mRNA and protein levels (Fig C, D), which may promote vaso-occlusion and inflammation. In contrast, vasoregulation was deactivated by hyper-RBC (Fig A, B). The expression of eNOS was downregulated and the bioavailability of vasodilator NO was decreased, consistent with impaired vasodilation (Fig C, D). Notably, the changes induced by hyper-RBC could be reversed by pretreating hyper-RBC with ROS scavenger TEMPOL. The upregulation of ICAM1, VCAM1 and TLR4 in hyper-RBC-treated cells was attenuated by TEMPOL pretreatment, and eNOS expression and NO bioavailability were also restored by TEMPOL (Fig C, D). Conclusion: Intensified oxidative stress in RBCs induced by admission hyperglycemia in stroke patients can cause endothelial dysfunction. Further studies are underway to validate these targets, and ask whether these mechanisms may exacerbate brain injury in stroke patients.