The maternal-fetal interface is critically important since is at this level that uteroplacental and fetoplacental blood flows are regulated and dysfunctions are seen in diseases of pregnancy, e.g. preeclampsia. Vasodilation is controlled by PGI2 and Nitric Oxide (NO) of endothelial origin and locally shows obligatory requirements for cell-cell communication via Gap junctions, a common theme in this PO-1. Uterine Artery Endothelial Cells in Pregnancy (P-UAEC) and HUVECs undergo Programmed Adaptation to maintain NO production via a Connexin (Cx) 43 mediated mechanisms. HYPOTHESIS Aim 1: Endothelial Programmed Adaptation is modulated by the Gap junction protein Cx43 that is elevated directly by Shear Stress via cAMP and/or cGMP to maintain vasodilator (PGI2 and NO) production. Purpose Aim 1: To determine in P-UAECs, HUVECs and HUAECs the effects of: 1) acute vs. prolonged Laminar Shear Stress on levels of phosphorylated and total Cx43 & eNOS and vasodilator production (PGI2 and NO) relative to cyclic nucleotide (cAMP and cGMP) adaptation; 2) inhibition of PKA, PKG, Adenylate Cyclase and sol Guanylate Cyclase; and 3) Indomethacin and L-NAME on these shear stress responses. HYPOTHESIS Aim 2: These important shear stress-mediated vasodilator mechanisms are abrogated by patho-physiologic levels of representative cytokines elevated in preeclampsia [VEGF and Tumor Necrosis Factor] via functional Gap junction disruption. We hypothesize that shear stress elevates cAMP /cGMP which is protective for maintaining vasodilator production via Gap junction assembly. Purpose Aim 2: To determine in P-UAECs, HUVECs and HUAECs if these cytokines disrupt the shear stress-associated cyclic nucleotide Gap junction-mediated vasodilator mechanisms we will evaluate: 1) effects of treatment with VEGF and TNF on the acute and prolonged laminar shear stress responses; 2) the therapeutic protective effects 8-Br-cAMP and 8-Br-cGMP on VEGF and TNF disruption of shear stress responses; and 3) the therapeutic protective effects cAMP phosphodiesterase (PDE)2, cAMP PDES, cAMP PDE4, or cGMP PDE5 inhibitors on VEGF and TNF disruption of shear stress responses. These data provide the first mechanistic framework for understanding the interactions between shear stress-mediated cyclic nucleotides for therapeutic protective actions and Gap junctions to regulate endothelial vasodilator (PGI2 & NO) production and it's abrogation via cytokine (VEGF & TNF) mediated disruption of cell-cell communication.
These studies represent major advancements in understanding the protective (therapeutic) effects of shear stress mediators on molecular/signaling mechanisms regulating uterine and placental endothelial adaptation via Gap junction-mediated cell-cell communication at the maternal-fetal interface. These mechanisms underlying uterine and placental endothelial vasodilator (PGI2 and NO) dysfunction caused by cytokines (VEGF and TNF) in preeclampsia and their abrogation by shear stress induced cAMP/cGMP.
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