157 - Hypertension in pregnancy and cerebral vascular leak syndrome-a translational study

Publication Number: 157.5349

Manisha Singh, Baylor Scott and White, Temple, TX, United States; Sara Mohamed, Baylor Scott White McLane Children's Medical Center, Temple, TX, United States; Niraj Vora, Baylor Scott White McLane Children's Medical Center, LEANDER, TX, United States; Ram R.. Kalagiri, Baylor Scott White McLane Children's Medical Center, Temple, TX, United States; Mohammad N. Uddin, Baylor Scott White McLane Children's Medical Center, Austin, TX, United States

Background: Preeclampsia (preE) is a hypertensive disease during pregnancy with multiple pathophysiologic triggers. Vasogenic cerebral edema represents a breach of the blood-brain barrier (BBB) and is a potential preE complication.

Objective: We have shown urinary excretion of a cardiotonic steroid, marinobufagenin (MBG), is elevated prior to the development of symptoms. We investigated alterations in the endothelial cells of the cerebral circulation in rats rendered "preE", the effects of MBG on these alterations, and the underlying molecular mechanisms.

Design/Methods: (1) BBB permeability in preE rats was assessed by Evan’s blue (EB) dye extravasation into brain parenchyma by a fluorescent assay. (2) Human brain microvascular endothelial cells (HBMEC) were used to test for effects of MBG in vitro on monolayer permeability. In HBMEC, phosphorylation of ERK1/2, Jnk, p38, and Src was evaluated after MBG treatment. Apoptosis was evaluated through alterations in caspase 3/7 and annexin-V staining. Effects of MBG on endothelial tight junction proteins were assessed by immunofluorescence microscopy. (3) We recruited 30 PreE and 40 pregnant patients. MBG levels and angiogenic factors were assayed in patient’s urine.

Results: (1) In the striatum, the extent of dye extravasation was greater (p < 0.05) in preE rats than in controls (9.1 vs 6.2 µg EB/mg dry tissue). (2) Concentrations of MBG ≥ 1 nM significantly inhibited the proliferation of HBMEC by 50%. MBG also significantly increased monolayer permeability within 6 hours (1.5-fold), causing a significant decrease in the phosphorylation of ERK1/2 (80%), activation of the phosphorylation of Jnk (56%), p38 (71%), and Src (75%). The expression of caspases 3/7 was increased indicating activation of apoptosis (1.5-fold), which was prevented by p38 inhibition. Additionally, MBG caused disruption of endothelial adherens tight junction proteins. (3) The MBG levels were higher in preE patients compared to normal pregnancy (2340 vs 595 pg/mg creatinine). Angiogenic imbalance was observed in preE patients.

Conclusion(s): MBG may play an important role in cerebral edema and neurologic abnormalities in preE. This helps understand the ways in which pre-eclampsia causes cerebral insults. Plasma volume during pregnancy increases and maintaining endothelial integrity is essential to avoiding leakage into the extravascular compartment. Vascular endothelium is essential to helping maintain vascular permeability and research on endothelial barriers and junctions can provide valuable information to further managing pre-eclampsia and helping treat it.