tPA Mobilizes Immune Cells That Exacerbate Hemorrhagic Transformation in Stroke

Circ Res. 2021 Jan 8;128(1):62-75. doi: 10.1161/CIRCRESAHA.120.317596. Epub 2020 Oct 19.

Abstract

Rationale: Hemorrhagic complications represent a major limitation of intravenous thrombolysis using tPA (tissue-type plasminogen activator) in patients with ischemic stroke. The expression of tPA receptors on immune cells raises the question of what effects tPA exerts on these cells and whether these effects contribute to thrombolysis-related hemorrhagic transformation.

Objective: We aim to determine the impact of tPA on immune cells and investigate the association between observed immune alteration with hemorrhagic transformation in ischemic stroke patients and in a rat model of embolic stroke.

Methods and results: Paired blood samples were collected before and 1 hour after tPA infusion from 71 patients with ischemic stroke. Control blood samples were collected from 27 ischemic stroke patients without tPA treatment. A rat embolic middle cerebral artery occlusion model was adopted to investigate the underlying mechanisms of hemorrhagic transformation. We report that tPA induces a swift surge of circulating neutrophils and T cells with profoundly altered molecular features in ischemic stroke patients and a rat model of focal embolic stroke. tPA exacerbates endothelial injury, increases adhesion and migration of neutrophils and T cells, which are associated with brain hemorrhage in rats subjected to embolic stroke. Genetic ablation of annexin A2 in neutrophils and T cells diminishes the effect of tPA on these cells. Decoupling the interaction between mobilized neutrophils/T cells and the neurovascular unit, achieved via a S1PR (sphingosine-1-phosphate receptor) 1 modulator RP101075 and a CCL2 (C-C motif chemokine ligand 2) synthesis inhibitor bindarit, which block lymphocyte egress and myeloid cell recruitment, respectively, attenuates hemorrhagic transformation and improves neurological function after tPA thrombolysis.

Conclusions: Our findings suggest that immune invasion of the neurovascular unit represents a previously unrecognized mechanism underlying tPA-mediated brain hemorrhage, which can be overcome by precise immune modulation during thrombolytic therapy.

Keywords: brain ischemia; immune system; inflammation; stroke; tissue-type plasminogen activator.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Annexin A2 / metabolism
  • Cell Line
  • Chemokine CCL2 / metabolism
  • Chemotaxis, Leukocyte / drug effects
  • Disease Models, Animal
  • Embolic Stroke / blood
  • Embolic Stroke / drug therapy*
  • Embolic Stroke / immunology
  • Female
  • Fibrinolytic Agents / administration & dosage
  • Fibrinolytic Agents / toxicity*
  • Humans
  • Infarction, Middle Cerebral Artery / blood
  • Infarction, Middle Cerebral Artery / drug therapy*
  • Infarction, Middle Cerebral Artery / immunology
  • Infusions, Intravenous
  • Intracranial Hemorrhages / blood
  • Intracranial Hemorrhages / chemically induced*
  • Intracranial Hemorrhages / immunology
  • Ischemic Stroke / blood
  • Ischemic Stroke / drug therapy*
  • Ischemic Stroke / immunology
  • Male
  • Neutrophil Infiltration / drug effects
  • Neutrophils / drug effects*
  • Neutrophils / immunology
  • Neutrophils / metabolism
  • Rats
  • Rats, Wistar
  • Sphingosine-1-Phosphate Receptors / metabolism
  • T-Lymphocytes / drug effects*
  • T-Lymphocytes / immunology
  • T-Lymphocytes / metabolism
  • Thrombolytic Therapy*
  • Tissue Plasminogen Activator / administration & dosage
  • Tissue Plasminogen Activator / toxicity*

Substances

  • Annexin A2
  • Anxa2 protein, rat
  • Ccl2 protein, rat
  • Chemokine CCL2
  • Fibrinolytic Agents
  • S1PR1 protein, rat
  • Sphingosine-1-Phosphate Receptors
  • Tissue Plasminogen Activator