Curdione inhibits thrombin-induced platelet aggregation via regulating the AMP-activated protein kinase-vinculin/talin-integrin αIIbß3 sign pathway.

BACKGROUND: Curdione, a sesquiterpene compound isolated from the essential oil of Curcuma aromatica Salisb. inhibits platelet aggregation, suggesting its significant anticoagulant and antithrombotic effects. However, the mechanisms have not been fully elucidated. HYPOTHESIS: We hypothesized that curdione inhibits thrombin-induced platelet aggregation via regulating the AMP-activated protein kinase-vinculin/talin-integrin αIIbß3 signaling pathway. STUDY DESIGN: We performed in vitro assays to evaluate the effect of curdione on thrombin-induced expression levels of the AMPK signaling molecule and integrin αIIbß3 signaling pathway components. METHODS: Platelet proteins were extracted from washed human platelets, and the effects of curdione on thrombin-induced platelet aggregation were evaluated. The expression levels of the AMPK signaling molecule and integrin αIIbß3 signaling pathway-related proteins were examined using western blot and RT-PCR. The binding of vinculin and talin were studied using immunoprecipitation, double immunofluorescence staining and microscale thermophoresis. RESULTS: Platelet aggregation analysis showed that 0.02 U/ml thrombin significantly induces platelet aggregation. Western blot and RT-PCR analysis revealed that AMPK inhibits the vinculin/talin-mediated integrin αIIbß3 signaling pathway, and curdione downregulates the thrombin-induced expression of phosphorylated AMPK (P-AMPK) and P-integrin at both the protein and mRNA levels and downregulates vinculin and talin at the protein level. Furthermore, microscale thermophoresis experiments showed that curdione inhibits the binding of vinculin and talin. The results from the immunoprecipitation and double immunofluorescence staining were consistent with the results of the microscale thermophoresis experiments. CONCLUSION: Curdione inhibits thrombin-induced platelet aggregation via regulating the AMP-activated protein kinase-vinculin/talin-integrin αIIbß3 signaling pathway, which suggests its therapeutic potential in ethnomedicinal applications as an anti-platelet and anti-thrombotic compound to prevent thrombotic diseases.

Anti-thrombotic effect of rutin isolated from Dendropanax morbifera Leveille.

Dendropanax morbifera H. Lev. is well known in Korean traditional medicine for improvement of blood circulation. In this study, rutin, a bioflavonoid having anti-thrombotic and anticoagulant activities was isolated from a traditional medicinal plant, D. morbifera H. Lev. The chemical characteristics of rutin was studied to be quercetin 3-O-α-l-rhamnopyranosyl-(1-6)-ß-d-glucopyranoside using high performance liquid chromatography mass spectrometry (HPLC-MS), proton nuclear magnetic resonance ((1)H NMR) and carbon-13 nuclear magnetic resonance ((13)C NMR). Turbidity and fibrin clotting studies revealed that rutin reduces fibrin clot in concentration dependent manner. Rutin was found to prolong activated partial thromboplastin time (aPTT), prothrombin time (PT) and closure time (CT). Furthermore, it decreased the activity of pro-coagulant protein, thrombin. In vivo study showed that rutin exerted a significant protective effect against collagen and epinephrine (or thrombin) induced acute thromboembolism in mice. These results suggest that rutin has a potent to be an anti-thrombotic agent for cardiovascular diseases.

PDGFR-α inhibition preserves blood-brain barrier after intracerebral hemorrhage.

OBJECTIVE: Perihematomal edema results from disruption of the blood-brain barrier (BBB) by key mediators, such as thrombin, following intracerebral hemorrhage (ICH). Platelet-derived growth factor receptor alpha (PDGFR-α), a tyrosine kinase receptor, was found in previous studies to play a role in orchestrating BBB impairment. In the present study, we investigated the role of PDGFR-α following ICH-induced brain injury in mice, specifically investigating its effect on BBB disruption. METHODS: Brain injury was induced by autologous arterial blood (30 µl) or thrombin (5 U) injection into mice brains. A PDGFR antagonist (Gleevec) or agonist (PDGF-AA) was administered following ICH. PDGF-AA was injected with a thrombin inhibitor, hirudin, in ICH mice. Thrombin-injected mice were given Gleevec or PDGF-AA neutralizing antibody. A p38 mitogen-activated protein kinase (MAPK) inhibitor, SB203580, was delivered with PDGF-AA in naïve animals. Postassessment included neurological function tests, brain edema measurement, Evans blue extravasation, immunoprecipitation, western blot, and immunohistology assay. RESULTS: PDGFR-α suppression prevented neurological deficits, brain edema, and Evans blue extravasation at 24 to 72 hours following ICH. PDGFR-α activation led to BBB impairment and this was reversed by SB203580 in naïve mice. Thrombin inhibition suppressed PDGFR-α activation and exogenous PDGF-AA increased PDGFR-α activation, regardless of thrombin inhibition. Animals receiving a PDGF-AA-neutralizing antibody or Gleevec showed minimized thrombin injection-induced BBB impairment. INTERPRETATION: PDGFR-α signaling may contribute to BBB impairment via p38 MAPK-mediated matrix metalloproteinase (MMP) activation/expression following ICH, and thrombin may be the key upstream orchestrator. The therapeutic interventions targeting the PDGFR-α signaling may be a novel strategy to prevent thrombin-induced BBB impairment following ICH.

In vivo models for the evaluation of antithrombotics and thrombolytics.

The development and application of animal models of thrombosis have played a crucial role in the discovery and validation of novel drug targets and the selection of new agents for clinical evaluation, and have informed dosing and safety information for clinical trials. These models also provide valuable information about the mechanisms of action/interaction of new antithrombotic agents. Small and large animal models of thrombosis and their role in the discovery and development of novel agents are described. Methods and major issues regarding the use of animal models of thrombosis, such as positive controls, appropriate pharmacodynamic markers of activity, safety evaluation, species specificity, and pharmacokinetics, are highlighted. Finally, the use of genetic models of thrombosis/hemostasis and how these models have aided in the development of therapies that are presently being evaluated clinically are presented.

Blood-brain barrier breakdown and repair by Src after thrombin-induced injury.

OBJECTIVE: Thrombin mediates the life-threatening cerebral edema that occurs after intracerebral hemorrhage. Therefore, we examined the mechanisms of thrombin-induced injury to the blood-brain barrier (BBB) and subsequent mechanisms of BBB repair. METHODS: Intracerebroventricular injection of thrombin (20U) was used to model intraventricular hemorrhage in adult rats. RESULTS: Thrombin reduced brain microvascular endothelial cell (BMVEC) and perivascular astrocyte immunoreactivity-indicating either cell injury or death-and functionally disrupted the BBB as measured by increased water content and extravasation of sodium fluorescein and Evans blue dyes 24 hours later. Administration of nonspecific Src family kinase inhibitor (PP2) immediately after thrombin injections blocked brain edema and BBB disruption. At 7 to 14 days after thrombin injections, newborn endothelial cells and astrocytes were observed around cerebral vessels at the time when BBB permeability and cerebral water content resolved. Delayed administration of PP2 on days 2 through 6 after thrombin injections prevented resolution of the edema and abnormal BBB permeability. INTERPRETATION: Thrombin, via its protease-activated receptors, is postulated to activate Src kinase phosphorylation of molecules that acutely injure the BBB and produce edema. Thus, acute administration of Src antagonists blocks edema. In contrast, Src blockade for 2 to 6 days after thrombin injections is postulated to prevent resolution of edema and abnormal BBB permeability in part because Src kinase proto-oncogene members stimulate proliferation of newborn BMVECs and perivascular astrocytes in the neurovascular niche that repair the damaged BBB. Thus, Src kinases not only mediate acute BBB injury but also mediate chronic BBB repair after thrombin-induced injury.

Hyperbaric oxygen for experimental intracerebral hemorrhage.

Acute brain edema formation contributes to brain injury after intracerebral hemorrhage (ICH). It has been reported that hyperbaric oxygen (HBO) is neuroprotective in cerebral ischemia, subarachnoid hemorrhage, and brain trauma. In this study, we investigated the effects of HBO on brain edema following ICH in rats. Male Sprague-Dawley rats received intracerebral infusion of autologous whole blood, thrombin, or ferrous iron. HBO (100% O2, 3.0 ATA for 1 h) was initiated 1 h after intracerebral injection. Control rats were exposed to air at room pressure. Brains were sampled at 24 or 72 h for water content, ion measurement, and Western blot analysis. We found that 1 session of HBO reduced perihematomal brain edema (p < 0.05) 24 h after ICH. HBO also reduced heat shock protein-32 (HSP-32) levels (p < 0.05) in ipsilateral basal ganglia 24h after ICH. However, HBO failed to attenuate thrombin-induced brain edema and exaggerated ferrous iron-induced brain edema (p < 0.05). Three sessions of HBO also failed to reduce brain edema 72h after ICH. In summary, HBO reduced early perihematomal brain edema and HSP-32 levels in brain. HBO-related brain protection does not occur through reduction in thrombin toxicity because HBO failed to attenuate thrombin-induced brain edema. Our results also indicate that HBO treatment after hematoma lysis for ICH may be harmful, since HBO amplifies iron-induced brain edema.

Nestin expression after experimental intracerebral hemorrhage.

The current study examines nestin expression after intracerebral hemorrhage (ICH), the role of different blood components in nestin upregulation, and the possibility that low doses of thrombin that induce tolerance to brain injury (thrombin preconditioning) might also induce nestin expression. Adult male Sprague-Dawley rats received an intracaudate injection of either whole blood, thrombin (1 or 5 U) or red blood cells (RBCs). Animals were sacrificed for single and double labeling immunohistochemistry to identify which cells express nestin, and for Western blotting to quantify nestin expression. By immunohistochemistry, nestin immunoreactivity was present in large numbers of astrocytes, surrounding the hematoma from day 3 to 1 week after ICH. After 2 weeks, nestin immunoreactivity was co-localized with a neuronal marker (neuronal specific enolase). By Western blot analysis, nestin was strongly expressed at day 3 (P<0.01) and 1 week (P<0.01), and expression persisted for at least 1 month (P<0.05). Intracerebral injection of thrombin or lysed RBCs resulted in a marked increase in nestin expression. Interestingly, injection of a low dose of thrombin that induces brain tolerance also upregulated nestin. The ICH-induced nestin expression in astrocytes may reflect an early response of these cells to injury, while the delayed expression in neurons might be a part of the adaptative response to injury perhaps leading to recovery of function. Nestin induction by a low dose of thrombin suggests that specific receptor-mediated pathways are involved in inducing nestin expression and that nestin may play a role in thrombin preconditioning.

Heparin treatment in thrombin-induced disseminated intravascular coagulation in the baboon.

BACKGROUND AND METHODS: We postulated that low-dose heparin (10 IU/kg.hr) administered as a continuous iv infusion may prevent or ameliorate the induction of thrombin-induced disseminated intravascular coagulation in baboons under general anesthesia. In a nonrandomized experiment lasting 8 hrs, animals were divided into three groups: 11 received thrombin only (group A); ten were pretreated with heparin before thrombin administration (group B); and 15 received heparin 2 hrs after disseminated intravascular coagulation was induced with thrombin (group C). All animals were monitored hemodynamically and coagulation tests were performed hourly. Tests included the following: one-stage prothrombin ratio; activated partial thromboplastin time; fibrinogen and fibrin degradation products; thrombin time; plasma fibrinogen level; antithrombin III and activated clotting time. After the acute phase of the experiment, the animals were observed for 6 days and a postmortem examination was performed on a survivor of each group. RESULTS: Six (55%) group A animals died within 6 days, while there were no deaths in group B and one animal (7%) died in group C. In group C, the administration of heparin could not normalize the clotting profile, but the mortality rate was significantly less than in group A. The prophylactic administration of heparin in group B prevented the induction of disseminated intravascular coagulation. The postmortem findings were of interest, but no statistically valid conclusions could be made, as only one autopsy was done for each group. However, the results suggest that heparin pretreatment may protect against lung edema and liver necrosis. CONCLUSIONS: The results suggest that heparin, in a dose of 10 IU/kg.hr iv, could possibly be safely used in patients at high risk of developing disseminated intravascular coagulation and in those patients with established disseminated intravascular coagulation.

Fibrin glue for the treatment of persistent lymphatic drainage.

A 7-year-old girl underwent resection of an abdominal wall lymphangiomatous tumor. Postoperative serous drainage, up to 300 mL per day, developed despite application of external pressure to the wound. Thirty-three days after the initial procedure, fibrin glue was applied to the draining tract. Concentrated fibrinogen was prepared from one unit of blood donated by the patient's mother. Ten milliliters fibrinogen and 10 mL thrombin (1,000 U/mL) were injected simultaneously through the wound drain as it was slowly removed, and pressure was reapplied for 48 hours. No further drainage occurred, and at 2- and 14-week follow-up examinations the wound had healed normally without reaccumulation of fluid. Fibrin glue successfully sealed this persistently draining abdominal wall tract. It is a painless, safe, and effective biologic sealant, and when prepared from homologous plasma it carries a low risk of virus transmission.

Evaluation of fibrin sealing for cardiovascular surgery.

Hemorrhage remains a problem in patients undergoing cardiovascular surgery. To evaluate fibrin sealant, a completely biodegradable hemostatic agent, three series of experiments were performed in mongrel dogs. In series I, 18 dogs had a 7 cm interposition of knitted Dacron (water porosity 1500 ml/min/cm2) in the descending aorta. In group A, all prostheses were treated with fibrin sealant and in group B by blood preclotting. Measurements of blood loss demonstrated 1.29 +/- 0.26 ml/min in group A as compared with 30.16 +/- 2.85 ml/min in group B (p less than .001). In series II, six dogs of each group were compared for thrombogenicity and platelet survival by using indium-111-labeled autologous platelets. According to Goldman et al., the thrombogenicity index was calculated. The mean thrombogenicity index for group A was 0.23 +/- 0.02 in contrast to 0.33 +/- 0.05 for group B (p greater than .05). Mean platelet survival was 5.59 +/- 0.23 days in group A in contrast to 5.34 +/- 0.05 days in group B (p greater than .05). In series III, the gluing potential was investigated by creating four types of injuries: four dogs had an aortic stab wound 3 to 5 mm, six dogs received a 10 to 15 mm stab wound to the left ventricle, seven dogs had a 3 cm laceration of the left atrial appendage, and four dogs had bilateral division of their carotid arteries. Wounds of the aorta and left atrial appendage were treated by partial clamping and the sole use of fibrin sealant, the carotid arteries were repaired by four simple sutures and fibrin sealant, and the left ventricular stab wounds were treated by the combined use of heterologous collagen and fibrin sealant without suture.(ABSTRACT TRUNCATED AT 250 WORDS)