Genetic Ablation of Extra Domain A of Fibronectin in Hypercholesterolemic Mice Improves Stroke Outcome by Reducing Thrombo-Inflammation
Background—The fibronectin splicing variant containing extra domain A (Fn-EDA) is present in negligible amounts in the plasma of healthy humans, but markedly elevated in patients with comorbid conditions including diabetes and hypercholesterolemia, which are risk factors for stroke. It remains unknown, however, whether Fn-EDA worsens stroke outcomes in such conditions. We determined the role of Fn-EDA in stroke outcome in a model of hypercholesterolemia, the apolipoprotein E-deficient (Apoe-/-) mouse.
Methods and Results—In a transient cerebral ischemia/reperfusion injury model, Apoe-/- mice expressing Fn deficient in EDA (Fn-EDA-/-Apoe-/- mice) exhibited smaller infarcts and improved neurological outcomes at days 1 and 8 (P<0.05 vs. Apoe-/- mice). Concomitantly, intracerebral thrombosis (assessed by fibrin (ogen) deposition) and postischemic inflammation (phospho-NF-κB p65, phospho IKKα/β, IL1-β and TNFα) within lesions of Fn-EDA-/-Apoe-/- mice were markedly decreased (P<0.05 vs. Apoe-/- mice). In a FeCl3 injury-induced carotid artery thrombosis model, thrombus growth rate and the time to occlusion were prolonged in Fn-EDA-/-Apoe-/- mice (P<0.05 vs. Apoe-/- mice). Genetic ablation of TLR4 improved stroke outcome in Apoe-/- mice (P<0.05) but had no effect on stroke outcome in Fn-EDA-/-Apoe-/- mice. Bone marrow transplantation experiments revealed that non-hematopoietic cell-derived Fn-EDA exacerbates stroke through TLR4 expressed on hematopoietic cells. Infusion of a specific inhibitor of Fn-EDA into Apoe-/- mouse 15 minutes after reperfusion significantly improved stroke outcome.
Conclusions—Hypercholesterolemic mice deficient in Fn-EDA exhibit reduced cerebral thrombosis and less inflammatory response after ischemia/reperfusion injury. These findings suggest that targeting Fn-EDA could be an effective therapeutic strategy in stroke associated with hypercholesterolemia.
- Received March 17, 2015.
- Revision received August 14, 2015.
- Accepted September 9, 2015.