The anti-inflammatory actions of structurally distinct EPAC1 activators in 2D culture model of vascular inflammation

Atherosclerosis is considered as a progressive inflammatory disease of the arterial wall, which is characterized by endothelial dysfunction, macrophage polarization, vascular inflammation, and immune responses. Chronic inflammation also underly the pathogenesis of other diseases, including cancer, metabolic disorders, and autoimmune diseases, therefore, anti-inflammatory strategies are increasingly being considered as therapeutic approaches to improve the prevention and treatment of these diseases.

The cAMP sensor, EPAC1, has emerged as an important factor in the regulation of multiple inflammatory signalling pathways in vascular endothelial cells (VECs). We have discovered a series of small molecule synthetic compounds, which selectively modulate EPAC1 activity, independently of the closely related EPAC2 isoform and the cAMP-activated protein kinase, PKA.

The first EPAC1 partial agonist identified in our lab, I942, was shown to block pro-inflammatory IL-6 signalling by induction of SOCS3 expression and inhibition of the expression of pro-inflammatory cell adhesion molecule, VCAM1 in HUVECs.

Here we used EPAC1 agonists with improved potency, PWO577 and SY007, and found, using immunoblotting and RNA sequencing (RNA-Seq), that both EPAC1 activators suppressed IL-6-induced STAT3 activation and associated downstream gene expression, including inhibition of SOCS3, STAT3, IL6ST and JAK3 genes in HUVECs. This suggests that PWO77 and SY007 exert anti-inflammatory actions in VECs.

We would like to now determine, how PWO577 and SY007 control inflammatory responses in a 2D triple-cell culture model of vascular inflammation, which allows to study immune-vascular interplay that is central to the progression of atherosclerosis and CVDs. We found that pre-treatment of LPS-stimulated THP1 macrophages with PWO577 and SY007 inhibited NLRP3 inflammasome induction. The mutual interplay between vascular and immune cells in triple-cell culture model caused a massive blockade of expression of inflammatory genes, as shown by RNA-Seq analysis.

Therefore, the anti-inflammatory properties of our novel EPAC1 activators make them promising drug candidates for future treatment of human diseases, where dysregulation of EPAC1 is implicated.