BS7 Angiotensin-(1–9) inhibits neointima formation in a murine vein graft model and modulates ERK1/2 phosphorylation and microRNA-132 pathways in human vascular smooth muscle cells

Introduction Vascular smooth muscle cell (VSMC) migration is integral to vascular remodelling in acute vascular injury. The main effector of the renin angiotensin system (RAS), angiotensin II (AngII), is a key mediator of this remodelling. AngII has previously been shown to upregulate microRNA-132 (miR-132) expression in rat VSMC which may contribute to AngII-mediated vascular remodelling. The counter-regulatory axis of the RAS, consisting of ACE2/Ang-(1–7)/Mas has been reported to inhibit proliferation and migration of VSMC in vitro and neointimal (NI) formation in vivo. Here we investigated the effects of an alternative peptide of the counter-regulatory RAS, Ang-(1–9), on NI formation in murine vein grafts and investigated the role of AngII and Ang-(1–9) on miR-132 expression and migration in human saphenous vein VSMCs. Methods NI formation was induced by interposition of the vena cava into the carotid artery in C57bl6/J mice. Ang-(1–9) was delivered subcutaneously via minipump and NI formation quantified 28 days later. Primary human saphenous vein VSMCs (HSVSMC) were stimulated with AngII alone or in combination with Ang-(1–9) and/or a MEK1/2 inhibitor (U1026). Expression of miR-132 was measured by qRT-PCR. ERK1/2 phosphorylation was assessed via western blot. Migration was assessed in HSVSMC via scratch wound assay following transfection of miR-132 mimic or scrambled control and/or incubation with U0126. Results After 28 days Ang-(1–9) infusion significantly reduced NI formation in the grafted vessel of mice compared to control vein graft mice (29620 ± 3410 μm 2 vs 17640 ± 2049μm 2 ; p Conclusion This study demonstrates that Ang-(1–9) reduces NI formation in a murine vein graft model and prevents AngII-induced ERK1/2 phosphorylation, miR-132 expression and HSVSMC migration in vitro. This study provides insight into the protective role of Ang-(1–9) in human VSMC and may highlight novel therapeutic targets in the setting of acute vascular injury. Conflict of interest None