ABSTRACT
BACKGROUND: Statins are widely used to lower lipids and reduce cardiovascular events. In vitro studies and small studies in patients with hyperlipidemias show statins inhibit tissue factor (TF) and blood coagulation mechanisms. We assessed the effects of simvastatin on TF and coagulation biomarkers in patients entered in STATCOPE, a multicenter, randomized, placebo-controlled trial of simvastatin (40 mg daily) versus placebo on exacerbation rates in patients with chronic obstructive pulmonary disease (COPD). METHODS: In 227 patients (114 simvastatin, 113 placebo; mean [± standard error of the mean] age 62 ± 0.53 years, 44.5% women) we measured (baseline, and 6 and 12 months): whole blood membrane TF-procoagulant activity (TF-PCA) and plasma factors VIIa, VII, VIII, fibrinogen, TF antigen, tissue factor pathway inhibitor (TFPI), thrombin-antithrombin complexes (TAT), and D-dimer. We excluded patients with diabetes, cardiovascular disease, and those taking or requiring a statin. RESULTS: In the statin group, there was a small increase in TF-PCA (from 25.18 ± 1.08 to 30.36 ± 1.10 U/ml; p = .03) over 12 months; factors VIIa and VIII, fibrinogen, TAT, and D-dimer did not change. Plasma TFPI (from 52.4 ± 1.75 to 44.7 ± 1.78 ng/ml; p < .0001) and FVIIC (1.23 ± 0.04 to 1.15 ± 0.03 U/ml; p = .03) decreased and correlated with total cholesterol levels. No changes in biomarkers were observed with placebo. CONCLUSIONS: In contrast to previous studies on statins, in COPD patients without diabetes, cardiovascular disease, or requiring a statin treatment, simvastatin (40 mg per day) did not decrease TF or factors VIIa and VIII, fibrinogen, TAT, or D-dimer. The decreases in TFPI and factor VII reflect the decrease in serum lipids.
Subject(s)
Pulmonary Disease, Chronic Obstructive , Thromboplastin , Blood Coagulation , Factor VIIa , Female , Humans , Male , Middle Aged , Pulmonary Disease, Chronic Obstructive/diagnosis , Pulmonary Disease, Chronic Obstructive/drug therapy , Simvastatin/therapeutic useABSTRACT
ADP-induced thromboxane generation depends on Src family kinases (SFKs) and is enhanced with pan-protein kinase C (PKC) inhibitors, but it is not clear how these two events are linked. The aim of the current study is to investigate the role of Y311 phosphorylated PKCδ in regulating ADP-induced platelet activation. In the current study, we employed various inhibitors and murine platelets from mice deficient in specific molecules to evaluate the role of PKCδ in ADP-induced platelet responses. We show that, upon stimulation of platelets with 2MeSADP, Y311 on PKCδ is phosphorylated in a P2Y1/Gq and Lyn-dependent manner. By using PKCδ and Lyn knockout murine platelets, we also show that tyrosine phosphorylated PKCδ plays a functional role in mediating 2MeSADP-induced thromboxane generation. 2MeSADP-induced PKCδ Y311 phosphorylation and thromboxane generation were potentiated in human platelets pre-treated with either a pan-PKC inhibitor, GF109203X or a PKC α/ß inhibitor and in PKC α or ß knockout murine platelets compared to controls. Furthermore, we show that PKC α/ß inhibition potentiates the activity of SFK, which further hyper-phosphorylates PKCδ and potentiates thromboxane generation. These results show for the first time that tyrosine phosphorylated PKCδ regulates ADP-induced thromboxane generation independent of its catalytic activity and that classical PKC isoforms α/ß regulate the tyrosine phosphorylation on PKCδ and subsequent thromboxane generation through tyrosine kinase, Lyn, in platelets.
