Abstract 14155: Exposure to sFlt1-Induced Preeclampsia Enhances the Future Vascular Response to Hypertensive Stimuli in Mice in a Smooth Muscle Mineralocorticoid Receptor Dependent Manner

Abstract

Preeclampsia (PE), a syndrome of high blood pressure (BP) and renal damage in late pregnancy, is associated with increased soluble VEGF receptor (sFlt1) and survivors have increased risk of future hypertension with increased angiotensin II (AngII) and salt sensitivity. Since smooth muscle cell mineralocorticoid receptor (SMC-MR) can be activated by hypertensive stimuli, we hypothesized that high sFlt1 exposure during pregnancy may induce a post-partum state of enhanced vascular sensitivity via SMC-MR activation. A PE model was induced by transient viral expression of sFlt1 in pregnant C57Bl6 mice. Elevated serum sFlt1, BP and glomerular endotheliosis was confirmed which all resolve post-partum. Two months later, resistance arteries from post-PE mice show no change in vasoconstriction to AngII but with increased mRNA ratio of the pro-constrictive AngII receptor-1(ATR1) to the vasodilatory ATR2. In a small cohort of women with prior PE, we confirm salt sensitivity of BP thus, postpartum mice were implanted with telemetric BP monitors and exposed to high salt or AngII (600mg/kg/day) infusion. Mice with prior PE had a significantly increased BP response to hypertensive stimuli. Microvessels from mice after PE and hypertensive stimuli had enhanced ex vivo myogenic tone and AngII vasoconstriction. To test the direct impact of sFlt1 on SMC-MR function, cultured SMC (Pac1) were transiently exposed to sFlt1 (24 hours on then off) to mimic the post-PE state. SMC-MR transcriptional activity in response to aldosterone and AngII were significantly increased after sFlt1 exposure as measured by luciferase reporter assay. SMC-MR activation and target gene expression was also enhanced after sFlt1 exposure (including AT1R/AT2R ratio). Finally, the role of SMC-MR in the post-PE phenotype was tested in vivo by PE induction in SMC-MR-KO vs MR-intact littermates. Post partum, SMC-MR-KO mice were protected from the PE-induced increase in aortic stiffness, microvascular myogenic tone and AngII vasoconstriction. sFlt1-induced PE produces a state of enhanced sensitivity to AngII that may be mediated by increased activation of SMC-MR. These data support the use of MR antagonists to mitigate the increased risk of cardiovascular disease in women exposed to PE.