Ticagrelor Conditioning Effects Are Not Additive to Cardioprotection Induced by Direct NLRP3 Inflammasome Inhibition: Role of RISK, NLRP3, and Redox Cascades

Abstract

Inhibition of either P2Y12 receptor or the nucleotide-binding oligomerization domain- (NOD-) like receptor pyrin domain containing 3 (NLRP3) inflammasome provides cardioprotective effects. Here, we investigate whether direct NLRP3 inflammasome inhibition exerts additive effects on myocardial protection induced by the P2Y12 receptor antagonist Ticagrelor. Ticagrelor (150 mg/kg) was orally administered to rats for three consecutive days. Then, isolated hearts underwent an ischemia/reperfusion (30 min ischemia/60 min reperfusion; IR) protocol. The selective NLRP3 inflammasome inhibitor INF (50 μM) was infused before the IR protocol to the hearts from untreated animals or pretreated with Ticagrelor. In parallel experiments, the hearts isolated from untreated animals were perfused with Ticagrelor (3.70 μM) before ischemia and subjected to IR. The hearts of animals pretreated with Ticagrelor showed a significantly reduced infarct size (IS, 49±3% of area at risk, AAR) when compared to control IR group (69±2% of AAR). Similarly, ex vivo administration of INF before the IR injury resulted in significant IS reduction (38±3% of AAR). Myocardial IR induced the NLRP3 inflammasome complex formation, which was attenuated by either INF pretreatment ex vivo, or by repeated oral treatment with Ticagrelor. The beneficial effects induced by either treatment were associated with the protective Reperfusion Injury Salvage Kinase (RISK) pathway activation and redox defence upregulation. In contrast, no protective effects nor NLRP3/RISK modulation were recorded when Ticagrelor was administered before ischemia in isolated heart, indicating that Ticagrelor direct target is not in the myocardium. Our results confirm that Ticagrelor conditioning effects are likely mediated through platelets, but are not additives to the ones achieved by directly inhibiting NLRP3.

An update on the regulatory mechanisms of NLRP3 inflammasome activation

“…121 However, another recent study showed that myocardial protection by ticagrelor is mediated through its antiplatelet properties and not an additive effect involving the inhibition of the NLRP3 inflammasome. 122 Understanding the mechanisms by which Cl − efflux controls NLRP3 inflammasome activation may facilitate the discovery of novel agents or drugs suitable for repurposing to increase clinical benefit for patients with one of a variety of NLRP3-related diseases.…”

Protective Role of Platelets in Myocardial Infarction and Ischemia/Reperfusion Injury

“…S1P and adenosine were shown to reach the highest concentrations in rat hearts protected by ticagrelor. Both S1P and adenosine are involved in RISK pathway activation in the heart [140]. Additionally, ticagrelor was able to prevent endothelial cells against apoptosis due to hypoxia stress.…”

“…e study of isolated rat hearts revealed that ticagrelor conditioning attenuated NLRP3 inflammasome complex formation through platelets. Cardioprotection evoked activation of RISK pathway and limitation of I/R-induced oxidative stress [140].…”

Potential Therapies to Protect the Aging Heart Against Ischemia/Reperfusion Injury

“…Mastracola et al tested the role of NLPR3 in C57B1 male mice fed with a high fat high fructose diet (HFHF) using an ex vivo I/R model. The authors found that the HFHF diet upregulated NLPR3 protein content, and this elevation downregulated the RISK/HIF-2alpha pathways (51)(52)(53). Furthermore, NLPR3 has also been proposed as a target in the aging myocardium.…”