Effect of ticagrelor on endothelial calcium signalling and barrier function

Area of Science:

• Endothelial cell biology
• G protein-coupled receptor signaling
• Cardiovascular pharmacology

Background:

• The P2Y12 receptor is a Gi-coupled receptor that inhibits adenylyl cyclase, reducing intracellular cyclic adenosine monophosphate (cAMP).
• Endothelial barrier function is crucial for vascular health and is regulated by intracellular signaling pathways.
• P2Y12 receptor antagonists are used clinically, but their direct effects on endothelial cells require elucidation.

Purpose of the Study:

• To investigate whether AR-C66096 and ticagrelor, P2Y12 receptor antagonists, protect endothelial cell (EC) barrier function.
• To determine if these protective effects are mediated by changes in intracellular cAMP levels in ECs.
• To explore the mechanisms underlying the effects of these antagonists on EC permeability.

Main Methods:

• Primary human umbilical vein ECs (HUVECs) and human pulmonary microvascular ECs (hPMECs) were used.
• Intracellular cAMP levels were measured following treatment with AR-C66096 and ticagrelor.
• EC monolayer permeability was assessed by measuring hyperpermeability induced by thrombin, with and without antagonists.
• Intracellular calcium ([Ca2+]i) and myosin light chain (MLC) phosphorylation were analyzed.

Main Results:

• AR-C66096 (10 µM) significantly increased cAMP levels in ECs by 50%, while ticagrelor (2-10 µM) had no effect.
• AR-C66096 antagonized thrombin-induced hyperpermeability in both HUVECs and hPMECs.
• Ticagrelor did not affect basal EC permeability but sensitized ECs to thrombin-induced hyperpermeability and increased [Ca2+]i via extracellular influx, leading to MLC phosphorylation and potentiated permeability.

Conclusions:

• The P2Y12 receptor antagonist AR-C66096 demonstrates a protective effect on endothelial cells in vitro, potentially via increased intracellular cAMP.
• Ticagrelor, conversely, sensitizes the endothelial barrier function by inducing calcium influx and activating the EC contractile machinery.
• These findings highlight differential effects of P2Y12 antagonists on endothelial barrier integrity, with implications for their clinical use.