Protease activated receptor-4: ready to be part of the antithrombosis spectrum

PURPOSE OF REVIEW: Cardiovascular disease is a major cause of death worldwide. Platelets play a key role in this pathological process. The serine protease thrombin is a critical regulator of platelet reactivity through protease activated receptors-1 (PAR1) and PAR4. Since targeting PAR4 comes with a low chance for bleeding, strategies blocking PAR4 function have great antithrombotic potential. Here, we reviewed the literature on platelet PAR4 with a particular focus on its role in thromboinflammation. RECENT FINDINGS: Functional PAR4 variants are associated with reduced venous thrombosis risk (rs2227376) and increased risk for ischemic stroke (rs773902). Recent advances have allowed for the creation of humanized mouse lines in which human PAR4 is express instead of murine PAR4. This has led to a better understanding of the discrepancies between human and murine PAR4. It also made it possible to introduce single nucleotide polymorphisms (SNPs) in mice allowing to directly test the in vivo functional effects of a specific SNP and to develop in vivo models to study mechanistic and pharmacologic alterations induced by a SNP. SUMMARY: PAR4 plays an important role in cardiovascular diseases including stroke, myocardial infarction and atherosclerosis. Targeting PAR4 hold great potential as a safe antithrombotic strategy.