Abstract W P236: Role of Leukocyte Cathepsin G in an Atherothrombotic Stroke Model
The majority of ischemic strokes in humans are caused by atheroemboli that originate from extracranial vessels, activate platelets and produce thrombi that occlude intracranial vessels. Most of the current stroke models do not simulate the mechanisms of endogenous thrombus interaction with blood elements, the vascular wall and its extracellular matrix, and thus do not translate well for the study of atherothrombotic mechanisms. To overcome these shortcomings, we developed an atherothrombotic stroke model. We used this model to determine the pathophysiologic role of leukocyte cathepsin G, a serine protease with pro-thrombotic properties, in stroke and to determine its suitability as a molecular target for therapy. We hypothesized that deficiency of cathepsin G will reduce intravascular thrombus formation, decrease infarct volume and improve neurobehavioral deficit in a mouse atherothrombotic stroke model.
Male C57Bl/6 (WT) and cathepsin G knockout mice (CG-/-) were used. A PE8 catheter was advanced into the ICA near the MCA origin and a reduction in cortical laser-Doppler flow was induced after a series of intra-arterial injections of collagen, a platelet activator and component of ruptured atherosclerotic plaque. Mice were sacrificed 3h post-collagen injection for histologic examination, or 48h post-collagen for infarct volume quantification and neurobehavioral assessment.
Gross examination of excised brains 3h post-collagen revealed thrombi within the main ICA in 71% (5/7) of WT mice and 0% of CG-/- mice (p=0.005), branches of the ICA in 0 WT mice and 29% (2/7) of CG-/- mice (p=0.13), in the main MCA in 43% (3/7) of WT mice and 0 CG-/- mice (p=0.05), and distal branches of the MCA in 100% (7/7) of WT and CG-/- mice. Immunofluorescence microscopy confirmed that platelets and fibrin were major components of these thrombi. Cerebral infarct in WT mice was 33% ± 9% of hemispheric volume and 19% ± 1% in CG-/- mice (p=0.02). Neurobehavioral deficit 48h post-collagen was reduced in CG-/- mice compared to WT.
Using a novel atherothrombotic stroke model, these data reveal an important role of cathepsin G in cerebrovascular thrombus formation and a novel mechanism linking inflammatory cells to ischemic brain injury- a link commonly observed in human clinical studies.
Author Disclosures: K.J. Schunke: None. R.C. Koehler: None. N. Faraday: None.
- © 2015 by American Heart Association, Inc.