Thymidine Phosphorylase Participates in Platelet Signaling and Promotes Thrombosis

Abstract

Rationale Platelets contain abundant thymidine phosphorylase (TYMP), which is highly expressed in diseases with high risk of thrombosis, such as atherosclerosis and type II diabetes. Objective Test the hypothesis that TYMP participates in platelet signaling and promotes thrombosis. Methods and Results By using a ferric chloride (FeCl3) induced carotid artery injury thrombosis model, we found time to blood flow cessation was significantly prolonged in Tymp−/− and Tymp+/− mice compared to wild type (WT) mice. Bone marrow transplantation and platelet transfusion studies demonstrated that platelet TYMP was responsible for the antithrombotic phenomenon in the TYMP deficient mice. Collagen-, collagen-related peptide (CRP)-, adenosine diphosphate-and/or thrombin-induced platelet aggregation were significantly attenuated in Tymp+/− and Tymp−/− platelets, and in WT or human platelets pretreated with TYMP inhibitor KIN59. Tymp deficiency also significantly decreased agonist-induced P-select in expression. TYMP contains an N-terminal SH3 domain binding proline-rich motif and forms a complex with the tyrosine kinases Lyn, Fyn and Yes in platelets. TYMP-associated Lyn was inactive in resting platelets, and TYMP trapped and diminished active Lyn after collagen stimulation. Tymp/Lyn double haploinsufficiency diminished the antithrombotic phenotype of Tymp+/− mice. TYMP deletion or inhibition of TYMP with KIN59 dramatically increased PECAM-1 tyrosine phosphorylation and diminished CRP or collagen induced AKT phosphorylation. In vivo administration of KIN59 significantly inhibited FeCl3 induced carotid artery thrombosis without affecting hemostasis. Conclusion TYMP participates in multiple platelet signaling pathways and regulates platelet activation and thrombosis. Targeting TYMP might be a novel anti-platelet and anti-thrombosis therapy.

Ferric Chloride-induced Murine Thrombosis Models

“…Thrombi start to enlarge from 3 – 4 min after removing the filter paper and these later formed thrombi are stable and usually are not washed away. The average occlusive time is 11.3 ± 3.16 min in the C57BL6 mice (n= 14) when 7.5% FeCl 3 is used 6,7,19 (Figure 5A and online video 1). In the previous studies we have demonstrated that both decrease and increase of FeCl 3 concentrations diminish the difference between an anti-thrombotic mouse strain and WT mice 6 ; From our experience, treatment of the carotid artery with 7.5% FeCl 3 for 1 min is sufficient to satisfy all of our purposes.…”

“…With a vision to minimize such variabilities and establish a uniformly reproducible in vivo model system, we have refined the FeCl 3 -induced carotid artery model that makes the data highly reproducible with minimal variation 6–10,16–19 . In this paper we describe and share the skills and report several representative experimental examples that can benefit from this model.…”

Platelet to lymphocyte ratio is associated with the severity of coronary artery disease and clinical outcomes of percutaneous coronary intervention in the Chinese Han population

“…Platelet activation is also significantly associated with platelet counts (20). Inappropriate platelet activation is an important pathogenic component of thrombosis at the site of vascular injury and leads to acute coronary syndrome (21). Meanwhile, platelets can secrete various cytokines, chemokines and other inflammatory mediators, such as interleukin (IL)-1, IL-3, and IL-6, potentially contributing to inflammatory processes by interacting with leukocytes (22).…”

Platelet-to-Lymphocyte Ratio Improves the Predictive Power of GRACE Risk Score for Long-Term Cardiovascular Events in Patients with Acute Coronary Syndrome

“…Clinical studies have demonstrated that higher baseline platelet counts are associated with CVD events [2], and platelet aggregation is significantly involved in platelet count [17]. Inappropriate platelet activation is an important pathogenic component of thrombosis at the site of vascular injury and leads to ACS [18]. Meanwhile, platelets can secret a variety of inflammatory mediators and potentially contribute to inflammatory processes by interacting with leukocytes [19].…”