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PCSK9 Inhibitor Attenuates Platelet TLR4 in ACS and TLR4 Blockers Prevent PCSK9-Mediated Platelet Activation

Lingshan Qi1,2, Meng Yuan1, Xing Liu1

  • 1Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease, Department of Cardiology, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University.

Acta Cardiologica Sinica
|July 29, 2026
PubMed
Abstract

Insights

Proprotein convertase subtilisin/kexin type 9 (PCSK9) enhances platelet activation and thromboxane A2 release, which is mediated by Toll-like receptor 4 (TLR4). PCSK9 inhibitors reduce platelet TLR4 expression and aggregation in acute coronary syndrome patients.

Area of Science:

  • Cardiovascular Biology
  • Immunology
  • Platelet Physiology

Background:

  • Proprotein convertase subtilisin/kexin type 9 (PCSK9) is known to regulate platelet activation through various signaling pathways.
  • The precise mechanisms by which PCSK9 influences platelet function, particularly its interaction with specific receptors, require further elucidation.

Purpose of the Study:

  • To investigate the role of Toll-like receptor 4 (TLR4) in mediating PCSK9-induced platelet activation.
  • To determine the effect of PCSK9 inhibition on platelet TLR4 expression and function in patients with acute coronary syndrome (ACS).

Main Methods:

  • Quantification of platelet surface TLR4 expression via flow cytometry in 120 ACS patients treated with evolocumab.
  • In vitro assessment of platelet aggregation and thromboxane A2 (TXA2) release in response to PCSK9, evolocumab, and the TLR4 inhibitor resatorvid (TAK-242).
  • Immunofluorescence staining to examine the co-localization of TLR4 and PCSK9 in megakaryoblastic leukemia (MEG-01) cells.

Main Results:

  • PCSK9 significantly increased platelet aggregation and TXA2 release in vitro, effects abolished by evolocumab and TAK-242.
  • Evolocumab treatment in ACS patients led to reduced platelet surface TLR4 expression and decreased plasma TXA2 levels.
  • Dual immunofluorescence confirmed the co-localization of TLR4 and PCSK9 in MEG-01 cells, suggesting a potential interaction.

Conclusions:

  • This study provides the first evidence that PCSK9 inhibitors downregulate platelet TLR4 expression in ACS patients.
  • TLR4 inhibition counteracts the pro-aggregatory effects of PCSK9 on platelets, establishing a mechanistic link between PCSK9 and TLR4 signaling in platelet activation.
  • The observed co-localization of TLR4 and PCSK9 supports a potential direct interaction between these proteins in platelet regulation.
Keywords:
ACSPCSK9Platelet activationTLR4

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