Consequently, binding of the IL6/sIL6R complex to gp130 on VECs leads to receptor clustering and activation of the JAK/STAT3 and ERK, MAPK and PI3K signalling pathways. Since gp130 is present on all cells, trans-signalling therefore dramatically increases the range of cell targets for IL6 signalling to include VECs. During trans-signalling, IL6 binds to soluble forms of the IL6 receptor α (sIL6Rα), allowing activation of gp130, even in cells that do not normally express the IL6Rα subunit, such as VECs. It is IL6 receptor “trans-signalling” that is thought to underlie the pro-inflammatory actions of IL6 in a variety of diseases, including atherosclerosis. Finally, cadherin molecules at adherens junctions mediate trans-endothelial migration of monocytes. Initial engagement of monocytes with the endothelium involves rolling adhesion mediated by E-selectin (SELE), followed by firm adhesion mediated by interactions between integrins expressed on leukocytes and adhesion molecules (ICAM1, VCAM1) expressed on endothelial cells. IL6 affects vascular endothelial cells (VECs) by triggering counter-productive angiogenesis, through vascular endothelial growth factor (VEGF) production, and increasing the secretion of chemokines, like the chemokine (C-C motif) ligand 2 (CCL2), also referred to as monocyte chemo-attractive protein 1 (MCP-1), that recruit monocytes to the inflamed endothelium. IL6 localises to atherosclerotic plaques and promotes chronic, low-level vascular inflammation, leading to neointimal thickening, vascular dysfunction, hypertension and increased risk of myocardial infarction. The increased inflammatory activity associated with atherosclerosis is partially brought about by increased levels of pro-inflammatory cytokines in the circulation, particularly IL6, which is associated with a twofold increase in CVDs and mortality in elderly patients. Overall, I942 represents the first non-cyclic nucleotide EPAC1 agonist in cells with the ability to suppress IL6 signalling and inflammatory gene expression in VECs.Ītherosclerosis is a serious cardiovascular disease (CVD), which arises from chronic localised inflammation at coronary and carotid arterial branch points, and remains the principal cause of death in the developed world ( ) despite changes in lifestyle and the widespread use of anti-hypertensive and lipid-lowering drugs.

I942 and 007 also inhibited IL6-induced expression of VCAM1 at the protein level and blocked VCAM1-dependent monocyte adhesion to HUVECs. The majority of genes identified were suppressed by I942, 007 and F/R treatment and many were involved in the control of key vascular functions, including the gene for the cell adhesion molecule, VCAM1. This identified 425 I942-regulated genes that were also regulated by the EPAC1-selective cyclic AMP analogue, 007, and the cyclic AMP-elevating agents, forskolin and rolipram (F/R). RNA sequencing was carried out to further identify I942-regulated genes in HUVECs. SOCS3 induction by I942 in HUVECs was blocked by the EPAC1 antagonist, ESI-09, and EPAC1 siRNA, but not by the broad-spectrum protein kinase A (PKA) inhibitor, H89, indicating that I942 regulates SOCS3 gene expression through EPAC1. We demonstrate that I942 promotes EPAC1 and Rap1 activation in HEK293T cells and induces SOCS3 expression and suppresses IL6-stimulated JAK/STAT3 signalling in HUVECs. Here, for the first time, we use the non-cyclic nucleotide EPAC1 agonist, I942, to determine its actions on cellular EPAC1 activity and cyclic AMP-regulated gene expression in VECs. Exchange protein activated by cyclic AMP (EPAC1) suppresses multiple inflammatory actions in vascular endothelial cells (VECs), partly due to its ability to induce expression of the suppressor of cytokine signalling 3 (SOCS3) gene, the protein product of which inhibits interleukin 6 (IL6) signalling through the JAK/STAT3 pathway.

Non cyclic amp molecule