Abstract WMP81: FGF21 Reduces Post-Stroke Blood Brain Barrier Damage in Diabetic db/db Male Mice

Abstract

Background and Purpose: Our previous studies demonstrated that recombinant human Fibroblast growth factor 21 (rFGF21), an endocrine member of the FGF family is potently beneficial for improving long-term neurological outcomes of type 2 diabetes (T2D) stroke mice. Here we tested hypothesis that rFGF21 protects against post-stroke BBB damage by PPARγ activation of cerebral micovascular endothelium. Methods: T2D db/db mice and their non-diabetic counterparts db/+ mice were subjected to focal stroke of dMCAO. Four experimental groups: 1) db/+ stroke, 2) db/db stroke, 3) db/db stroke+rFGF21, and 4) db/db stroke+rFGF21+GW9662. rFGF21 (1.5mg/kg, i.p.) was injected at 6 hours after stroke and PPARγ inhibitor GW9662 (4mg/kg, i.p.) was injected 30 min prior to rFGF21 treatment. At 24 hours post-stroke, we collected peri-infarct nuclear fraction for PPARγ-DNA binding activity assay using EMSA, microvascular isolation for RT-PCR analyzing mRNA levels of proteins constituting BBB junctional complex (occluding, clauding-5, VE-cadherin and ZO-1) and PPARγ targeted downstream genes (CD36 and FABP4) as indicators of PPARγ activity in microvasculature. BBB permeability was assessed by measuring 3kDa FITC-dextran or Evans blue extravasations at 48 hour post-stroke. Results: Ischemic stroke induced a significant decrease of PPARγ-DNA binding activity and mRNA levels of BBB junctional proteins in peri-infarct area, and a significant increase of BBB permeability in diabetic db/db stroke mice compared to db/+ stroke mice. Changes of mRNA levels of CD36 and FABP4 in brain microvascular isolation were consistent with changes of PPARγ-DNA binding activity. rFGF21 administration significantly increased PPARγ-DNA binding activity, elevated mRNA levels of BBB junctional complex proteins and ameliorated BBB leakage. However, pre-treatment of GW9662 partially abolished the post-stroke BBB protective effects of rFGF21. Conclusions: rFGF21 has strong protective effects in acute BBB leakage after stroke, and the underlying mechanisms is partially via increase in PPARγ-DNA binding activity and mRNA expression of BBB junctional complex proteins. Together with our previous investigations, rFGF21 might be a promising candidate for treating diabetic stroke.