Department of Pediatrics, Division of Hematology/Oncology, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania, USA.
University of Pittsburgh School of Medicine.
JCI Insight. 2024 Mar 8;9(5):e174575. doi: 10.1172/jci.insight.174575.
Thrombosis and inflammation are intimately linked and synergistically contribute to the pathogenesis of numerous thromboinflammatory diseases, including sickle cell disease (SCD). While platelets are central to thrombogenesis and inflammation, the molecular mechanisms of crosstalk between the 2 remain elusive. High-mobility group box 1 (HMGB1) regulates inflammation and stimulates platelet activation through Toll-like receptor 4. However, it remains unclear whether HMGB1 modulates other thrombotic agonists to regulate platelet activation. Herein, using human platelets, we demonstrate that HMGB1 significantly enhanced ADP-mediated platelet activation. Furthermore, inhibition of the purinergic receptor P2Y12 attenuated HMGB1-dependent platelet activation. Mechanistically, we show that HMGB1 stimulated ADP secretion, while concomitantly increasing P2Y12 levels at the platelet membrane. We show that in SCD patients, increased plasma HMGB1 levels were associated with heightened platelet activation and surface P2Y12 expression. Treatment of healthy platelets with plasma from SCD patients enhanced platelet activation and surface P2Y12, and increased sensitivity to ADP-mediated activation, and these effects were linked to plasma HMGB1. We conclude that HMGB1-mediated platelet activation involves ADP-dependent P2Y12 signaling, and HMGB1 primes platelets for ADP signaling. This complementary agonism between ADP and HMGB1 furthers the understanding of thromboinflammatory signaling in conditions such as SCD, and provides insight for therapeutic P2Y12 inhibition.
血栓形成和炎症密切相关，并协同促进许多血栓炎症性疾病的发病机制，包括镰状细胞病（SCD）。虽然血小板是血栓形成和炎症的核心，但两者之间相互作用的分子机制仍不清楚。高迁移率族蛋白 B1（HMGB1）通过 Toll 样受体 4 调节炎症并刺激血小板活化。然而，HMGB1 是否调节其他血栓形成激动剂来调节血小板活化仍不清楚。在此，我们使用人血小板证明 HMGB1 显著增强了 ADP 介导的血小板活化。此外，嘌呤能受体 P2Y12 的抑制减弱了 HMGB1 依赖的血小板活化。从机制上讲，我们表明 HMGB1 刺激了 ADP 的分泌，同时增加了血小板膜上的 P2Y12 水平。我们表明，在 SCD 患者中，血浆中 HMGB1 水平的升高与血小板活化和表面 P2Y12 表达增加有关。用 SCD 患者的血浆处理健康血小板可增强血小板活化和表面 P2Y12，并增加对 ADP 介导的活化的敏感性，这些作用与血浆 HMGB1 有关。我们得出结论，HMGB1 介导的血小板活化涉及 ADP 依赖性 P2Y12 信号转导，并且 HMGB1 使血小板对 ADP 信号敏感。ADP 和 HMGB1 之间的这种互补激动作用加深了对 SCD 等情况下血栓炎症信号的理解，并为 P2Y12 抑制的治疗提供了见识。
