Inhibition of Thrombin-Activatable Fibrinolysis Inhibitor and Plasminogen Activator Inhibitor-1 Reduces Ischemic Brain Damage in Mice
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Background and Purpose—Cerebral ischemia and reperfusion is associated with activation of the coagulation cascade and fibrin deposition in cerebral microvessels. Both thrombin-activatable fibrinolysis inhibitor (TAFI) and plasminogen activator inhibitor-1 (PAI-1) attenuate fibrinolysis and are therefore attractive targets for the treatment of ischemic stroke.
Methods—TAFI and PAI-1 were inhibited by monoclonal antibodies in a mouse model of transient middle cerebral artery occlusion. Twenty-four hours after stroke, mice were neurologically scored, cerebral thrombotic burden was assessed, and brain infarct sizes were calculated.
Results—Inhibition of TAFI or PAI-1 significantly decreased cerebral infarct sizes by 50% 24 hours after stroke. This reduction in cerebral damage was associated with a significant decrease in fibrin(ogen) deposition in the ischemic brain. Concurrently, functional recovery of the animals was improved. Interestingly, combined targeting of TAFI and PAI-1 using low, and by themselves inactive, doses of antibodies improved cerebral blood flow and reduced cerebral fibrin(ogen) deposition and infarct sizes by 50%. When dual treatment was delayed to 1 hour after the start of reperfusion, it still reduced brain injury; however, this was not statistically significant.
Conclusions—Targeting of PAI-1 and TAFI is protective in an ischemic stroke model by attenuating fibrin(ogen) deposition, thereby improving reperfusion. Combined inhibition has a co-operative effect that could become useful in ischemic stroke therapy.
- plasminogen activator inhibitor-1
- reperfusion injury
- thrombin-activatable fibirinolysis inhibitor
- Received May 18, 2016.
- Revision received June 11, 2016.
- Accepted June 16, 2016.
- © 2016 American Heart Association, Inc.