Mononuclear Cells Negatively Regulate Endothelial Ca 2+ Signaling

Endothelial Ca signaling has important roles to play in maintaining pregnancy associated vasodilation in the utero-placenta. Inflammatory cytokines, often elevated in vascular complications of pregnancy, negatively regulate ATP-stimulated endothelial Ca signaling and associated nitric oxide production. However, the role of direct engagement of immune cells on endothelial Ca signaling and therefore endothelial function is unclear. To model immune-endothelial interactions, herein, we evaluate the effects of peripheral blood mononuclear cells (PBMCs) in short-term interaction with human umbilical vein endothelial cells (HUVECs) on agonist-stimulated Ca signaling in HUVECs. We find that mononuclear cells (10:1 and 25:1 mononuclear: HUVEC) cause decreased ATP-stimulated Ca signaling; worsened by activated mononuclear cells possibly due to increased cytokine secretion. Additionally, monocytes, natural killers, and T-cells cause decrease in ATP-stimulated Ca signaling using THP-1 (monocyte), NKL (natural killer cells), and Jurkat (T-cell) cell lines, respectively. PBMCs with Golgi-restricted protein transport prior to interaction with endothelial cells display rescue in Ca signaling, strongly suggesting that secreted proteins from PBMCs mediate changes in HUVEC Ca signaling. We propose that endothelial cells from normal pregnancy interacting with PBMCs may model preeclamptic endothelial-immune interaction and resultant endothelial dysfunction.