Dose-dependent effects of anthocyanin supplementation on platelet function in subjects with dyslipidemia: A randomized clinical trial.

BACKGROUND: Dyslipidemia induces platelet hyperactivation and hyper-aggregation, which are linked to thrombosis. Anthocyanins could inhibit platelet function in vitro and in mice fed high-fat diets with their effects on platelet function in subjects with dyslipidemia remained unknown. This study aimed to investigate the effects of different doses of anthocyanins on platelet function in individuals with dyslipidemia. METHODS: A double-blind, randomized, controlled trial was conducted. Ninety-three individuals who were initially diagnosed with dyslipidemia were randomly assigned to placebo or 40, 80, 160 or 320 mg/day anthocyanin groups. The supplementations were anthocyanin capsules (Medox, Norway). Platelet aggregation by light aggregometry of platelet-rich plasma, P-selectin, activated GPⅡbⅢa, reactive oxygen species (ROS), and mitochondrial membrane potential were tested at baseline, 6 weeks and 12 weeks. FINDINGS: Compared to placebo group, anthocyanins at 80 mg/day for 12 weeks reduced collagen-induced platelet aggregation (-3.39±2.36%) and activated GPⅡbⅢa (-8.25±2.45%) (P < 0.05). Moreover, compared to placebo group, anthocyanins at 320 mg/day inhibited collagen-induced platelet aggregation (-7.05±2.38%), ADP-induced platelet aggregation (-7.14±2.00%), platelet ROS levels (-14.55±1.86%), and mitochondrial membrane potential (7.40±1.56%) (P < 0.05). There were dose-response relationships between anthocyanins and the attenuation of platelet aggregation, mitochondrial membrane potential and ROS levels (P for trend <0.05). Furthermore, significantly positive correlations were observed between changes in collagen-induced (r = 0.473) or ADP-induced (r = 0.551) platelet aggregation and ROS levels in subjects with dyslipidemia after the 12-week intervention (P < 0.05). INTERPRETATION: Anthocyanin supplementation dose-dependently attenuates platelet function, and 12-week supplementation with 80 mg/day or more of anthocyanins can reduce platelet function in individuals with dyslipidemia. FUNDING: None.

Ginsenosides Rb2 and Rd2 isolated from Panax notoginseng flowers attenuate platelet function through P2Y12-mediated cAMP/PKA and PI3K/Akt/Erk1/2 signaling.

Saponins derived from Panax notoginseng root are widely used as herbal medicines and dietary supplements due to their wide range of health benefits. However, the effects of those from Panax notoginseng flowers (PNF) on platelet function and thrombus formation remain largely unknown. Using a series of platelet function assays, we found that G-Rb2 and G-Rd2, among the ten PNF saponin monomers, significantly inhibited human platelet aggregation and activation induced by adenosine diphosphate (ADP) in vitro. The 50% inhibitory concentration (IC50) of G-Rb2 and G-Rd2 against ADP-induced platelet aggregation was 85.5 ± 4.5 µg mL-1 and 51.4 ± 4.6 µg mL-1, respectively. Mechanistically, G-Rb2 and G-Rd2 could effectively modulate platelet P2Y12-mediated signaling by up-regulating cAMP/PKA signaling and down-regulating PI3K/Akt/Erk1/2 signaling pathways. Co-incubation of the P2Y12 antagonist cangrelor with either G-Rb2 or G-Rd2 did not show significant additive inhibitory effects. G-Rb2 and G-Rd2 also substantially suppressed thrombus growth in a FeCl3-induced murine arteriole thrombosis model in vivo. Interestingly, G-Rd2 generally exhibited more potent inhibitory effects on platelet function and thrombus formation than G-Rb2. Thus, our data suggest that PNF-derived G-Rb2 and G-Rd2 effectively attenuate platelet hyperactivity through modulating signaling pathways downstream of P2Y12, which indicates G-Rb2 and G-Rd2 may play important preventive roles in thrombotic diseases.

Coenzyme Q10 attenuates platelet integrin αIIbß3 signaling and platelet hyper-reactivity in ApoE-deficient mice.

Coenzyme Q10 (CoQ10) exists in a wide variety of foods and has promising cardiovascular benefits. However, its effects on platelets and integrin αIIbß3 signaling during atherosclerosis have not been previously explored. Here, apolipoprotein E-deficient (ApoE-/-) mice were fed a standard diet, high-fat diet (HFD) or CoQ10-supplemented HFD for 12 weeks. We found that CoQ10 supplementation in ApoE-/- mice significantly alleviated formation of HFD-induced atherosclerotic lesions, and attenuated platelet hyper-aggregation and granule secretion, including CD62P, CD63 and CD40 ligand (CD40L) expression and platelet factor-4, ß-thromboglobulin and activation normal T cell expressed and secreted (CCL5) release. CoQ10 supplementation decreased soluble fibrinogen and JON/A binding to αIIbß3 on activated platelets, indicating that αIIbß3-mediated inside-out signaling was attenuated. Additionally, CoQ10 down-regulated platelet αIIbß3 outside-in signaling including decreasing phosphorylation of the ß3 intracellular tail, cellular and sarcoma tyrosine-protein kinase (c-Src), and myosin light chain (MLC), and consistently attenuating platelet spreading and clot retraction. Importantly, platelet-monocyte aggregation that was primarily mediated by αIIbß3 and can be blocked using an αIIbß3-specific antagonist tirofiban was also markedly diminished by CoQ10. Thus, CoQ10 supplementation attenuates platelet hyper-reactivity via down-regulating both αIIbß3 inside-out and outside-in signaling, which may play important preventive roles in atherothrombosis.

Coenzyme Q10 Upregulates Platelet cAMP/PKA Pathway and Attenuates Integrin αIIbß3 Signaling and Thrombus Growth.

SCOPE: Platelet integrin αIIbß3 is the key mediator of atherothrombosis. Supplementation of coenzyme Q10 (CoQ10), a fat-soluble molecule that exists in various foods, exerts protective cardiovascular effects. This study aims to investigate whether and how CoQ10 acts on αIIbß3 signaling and thrombosis, the major cause of cardiovascular diseases. METHODS AND RESULTS: Using a series of platelet functional assays in vitro, it is demonstrated that CoQ10 reduces human platelet aggregation, granule secretion, platelet spreading, and clot retraction. It is further demonstrated that CoQ10 inhibits platelet integrin αIIbß3 outside-in signaling. These inhibitory effects are mainly mediated by upregulating cAMP/PKA pathway, where CoQ10 stimulates the A2A adenosine receptor and decreases phosphodiesterase 3A phosphorylation. Moreover, CoQ10 attenuates murine thrombus growth and vessel occlusion in a ferric chloride (FeCl3 )-induced thrombosis model in vivo. Importantly, the randomized, double-blind, placebo-controlled clinical trial in dyslipidemic patients demonstrates that 24 weeks of CoQ10 supplementation increases platelet CoQ10 concentrations, enhances the cAMP/PKA pathway, and attenuates αIIbß3 outside-in signaling, leading to decreased platelet aggregation and granule release. CONCLUSION: Through upregulating the platelet cAMP/PKA pathway, and attenuating αIIbß3 signaling and thrombus growth, CoQ10 supplementation may play an important protective role in patients with risks of cardiovascular diseases.

Anthocyanin Cyanidin-3-Glucoside Attenuates Platelet Granule Release in Mice Fed High-Fat Diets.

Platelet granule release is considered an important target for preventing and treating cardiovascular diseases (CVDs). Cyanidin-3-glucoside (Cy-3-g) is a predominant bioactive anthocyanin compound in many edible plants and has been reported to be protective against CVDs by attenuating platelet dysfunction. However, direct evidence of the action of Cy-3-g on platelet granule secretion in purified platelets from in vivo assays is still poor. In the present study, we demonstrated that dietary supplementation of purified Cy-3-g reduces serum lipid levels and facilitates down-regulation of the platelet granule release of substances such as P-selectin, CD40L, 5-HT, RANTES and TGF-ß1 in gel-filtered platelets, in addition to attenuating serum PF4 and ß-TG levels in mice fed high-fat diets. These results provide evidence that Cy-3-g protects against thrombosis and CVDs by inhibiting purified platelet granule release in vivo.