Suppression of Human Platelet Activation via Integrin αIIbβ3 Outside-In Independent Signal and Reduction of the Mortality in Pulmonary Thrombosis by Auraptene.

Chih-Wei Hsia,Wan-Jung Lu,Cheng-Lin Tsai,Thanasekaran Jayakumar,Jiun-Yi Li,Chih-Hsuan Hsia,Joen-Rong Sheu,Marappan Velusamy

doi:10.3390/ijms20225585

Abstract

Auraptene is the most abundant coumarin derivative from plants. The pharmacological value of this compound has been well demonstrated, especially in the prevention of cancer and neurodegenerative diseases. Platelet activation is a major factor contributing to arterial thrombosis. Thus, this study evaluated the influence of auraptene in platelet aggregation and thrombotic formation. Auraptene inhibited platelet aggregation in human platelets stimulated with collagen only. However, auraptene was not effective in inhibiting platelet aggregation stimulated with thrombin, arachidonic acid, and U46619. Auraptene also repressed ATP release, [Ca2+]i mobilization, and P-selectin expression. Moreover, it markedly blocked PAC-1 binding to integrin αIIbβ3. However, it had no influence on properties related to integrin αIIbβ3-mediated outside-in signaling, such as the adhesion number, spreading area of platelets, and fibrin clot retraction. Auraptene inhibited the phosphorylation of Lyn-Fyn-Syk, phospholipase Cγ2 (PLCγ2), protein kinase C (PKC), Akt, and mitogen-activated protein kinases (MAPKs; extracellular-signal-regulated kinase (ERK1/2), and c-Jun N-terminal kinase (JNK1/2), but not p38 MAPK). Neither SQ22536, an adenylate cyclase inhibitor, nor ODQ, a guanylate cyclase inhibitor, reversed the auraptene-mediated inhibition of platelet aggregation. Auraptene reduced mortality caused by adenosine diphosphate (ADP)-induced pulmonary thromboembolism. In conclusion, this study provides definite evidence that auraptene signifies a potential therapeutic agent for preventing thromboembolic disorders.

Highlights

Nutritional substances play central roles in the prevention of various inflammatory ailments, including cardiovascular diseases (CVDs)
Auraptene inhibited the phosphorylation of Lyn-Fyn-Syk, phospholipase Cγ2 (PLCγ2), protein kinase C (PKC), Akt, and mitogen-activated protein kinases (MAPKs; extracellular-signal-regulated kinase (ERK1/2), and c-Jun N-terminal kinase (JNK1/2), but not p38 MAPK)
Inhibition was slight and not statistically significant for platelets stimulated with other agonists. This finding implies that auraptene-mediated inhibition of platelet aggregation occurs through a distinct PLC-dependent mechanism

Summary

Introduction

Nutritional substances play central roles in the prevention of various inflammatory ailments, including cardiovascular diseases (CVDs). Collagen contained in the basement membrane induces a shape change in the platelets, from discoid to spheroid, with pseudopodic projections of platelets [2], and the combined platelet secretion from granules contain substances, such as adenosine triphosphate (ATP), Ca2+, and fibrinogen, to strengthen platelet aggregation. The binding of fibrinogen to active high-affinity integrin αIIbβ becomes progressively irreversible, initiating a series of intracellular signaling events, including intracellular calcium mobilization, tyrosine phosphorylation of numerous proteins, activation of phosphoinositide metabolism, and cytoskeleton reorganization. This process is often referred to as outside-in signaling [3]

Methods

Results

Conclusion