整合素受体阻断剂的进展与临床评价

目的:论述整合素受体阻断剂的进展和临床评价。方法:收集国内、外相关文献并进行综合分析。结果与结论:整合素受体阻断剂在血小板黏附、聚集和释放等功能中发挥着重要的作用,对整合素受体(血小板膜糖蛋白GPⅡb/Ⅲa受体)选择性高,在与整合素构象变化有关的细胞信号双向跨膜传递对血小板功能的调控作用已日益受到关注,在治疗血栓、急性心肌梗死、急性冠脉综合征上展现了良好的临床治疗前景。     

糖蛋白Ⅱb/Ⅲa受体拮抗剂的研究进展

血小板膜糖蛋白IIb/IIIa(GPⅡb/Ⅲa)是血小板聚集的最终共同途径中的关键因素,特别是在动脉血栓形成过程中起着重要作用,因此阻断GP IIb/IIIa受体是治疗和预防血栓性疾病的重要措施。本文针对药物的作用途径及作用靶点,综述了近年来作用于血小板糖蛋白Ⅱb/Ⅲa受体拮抗剂的抗血小板聚集作用药物的研究进展。     

血栓烷A2受体信号传导及相关抗血小板药物研究进展

摘 要血栓烷A2受体广泛存在于人体不同的组织器官,属于G蛋白偶联受体超家族中的一种七重跨膜蛋白,在血小板膜上也有分布。血栓烷A2受体激活导致一系列连锁反应也是活化血小板的重要途径之一,进而促进止血和血栓形成。目前,抗血小板药物的研究主要集中在血小板活化通路中的受体和信号分子水平,血栓烷A2受体相关的抗血小板药物也受到广泛关注。了解血小板内该受体下的信号转导,对于探讨相关药物作用机制、开发新型或中药有效成分类抗血小板药物具有重要意义。     

平足蛋白及其受体CLEC-2参与神经炎症反应的研究进展

平足蛋白是一种分子量约40 kDa的Ⅰ型跨膜糖蛋白,血小板新型活化受体C型凝集素样受体2(CLEC-2)是平足蛋白的内源性受体。平足蛋白与CLEC-2相互作用在维持胚胎发育期脑血管完整性方面发挥重要作用;平足蛋白与CLEC-2相互作用参与诱导血小板活化、促进炎症反应等病理生理过程,并发挥重要作用。平足蛋白和CLEC-2在炎症和血栓形成中发挥重要作用,并且与神经系统相关疾病的预后具有相关性。本文综述平足蛋白及其受体CLEC-2参与神经炎症反应的研究进展。     

巴替非班对血小板聚集功能影响的研究

近些年来,无论是从治疗还是发病机制的角度,血小板功能活性在急性冠状动脉综合征(ACS)中的作用都越来越得到确认,目前已证实血小板膜糖蛋白(GP)Ⅱb/Ⅲa受体是一个理想的治疗动脉血栓的药物靶点.巴替非班属于新一代人工合成的血小板GPⅡb/Ⅲa受体拮抗剂,主要药理作用为降低血小板聚集功能,对血小板聚集抑制作用也有明显影响.     

血小板内皮聚集受体1及其介导的信号通路在血小板和内皮细胞中的作用研究进展

血小板内皮聚集受体1(platelet endothelial aggregation receptor 1, PEAR1)是2005年被发现的一种跨膜受体，主要在血小板和内皮细胞上表达。PEAR1是血小板与血小板间相互接触的受体蛋白，在血小板活化和聚集过程中起着重要作用。内皮细胞在维持血管张力和血管修复方面发挥重要作用，PEAR1通过影响其增殖和相关新生血管的形成，调控肿瘤的发生、发展过程。近年来，PEAR1逐渐被公认为是抗血栓药物的潜在靶点。本综述主要阐明血小板内皮聚集受体1在血小板和内皮细胞中的作用机制以及相关信号通路，为肿瘤相关血栓的药物治疗研究提供新思路。     

氯吡格雷抵抗及其对策

氯吡格雷在急性冠脉综合征和经皮冠状动脉介入治疗前后发挥重要作用。氯吡格雷是血小板膜上P2Y_(12)受体的拮抗药。氯吡格雷抵抗包括对氯吡格雷无反应和对氯吡格雷低反应。氯吡格雷抵抗者血小板聚集率高,易发生心血管事件。本文对氯吡格雷的作用机制、氯吡格雷抵抗原因及治疗对策等作一综述。     

心脏瓣膜置换术中应用乌司他丁保护血小板功能的临床研究

目的探讨心脏瓣膜置换术中应用乌司他丁对血小板功能的保护作用。方法 70例心脏瓣膜置换术患者随机分为两组:对照组和乌司他丁组,每组35例。对照组行常规手术,乌司他丁组在预充液中一次性加入乌司他丁2万U/kg;选取4个时段抽血测定血小板膜糖蛋白受体GPⅠb、GPⅡb/Ⅲa和血小板计数;记录术后心包、纵隔引流血量及输血量。结果 GPⅠb、GPⅡb/Ⅲa在对照组和乌司他丁组之间的比较有统计学意义(P<0.05)。血小板计数组间比较无统计学意义(P>0.05)。乌司他丁组术后引流血量明显少于对照组(P<0.05)。两组术后输血量无统计学意义。结论心脏瓣膜置换术中应用的乌司他丁通过保护血小板膜糖蛋白受体而对血小板功能有部分保护作用,从而减轻术后非外科性出血,可取代抑肽酶作为心脏瓣膜置换术的血小板保护用药。     

血管性血友病因子对冠心病发生影响的研究进展

von Willebrand因子又称血管性血友病因子,通过特异的血小板膜受体(糖蛋白Ιb-IX复合物)介导血小板与内皮下层的黏附,是一个反应内皮损伤的标志物,其增高有利于血小板的黏附。vWF与冠心病的发生相关,是反映内皮细胞受损的可靠指标之一。本研究通过对vWF生物学特点、生理功能、作用机理及对冠心病发生影响的相关论文的研究整理,为临床探讨冠心病影响因素及治疗提供参考依据。     

AoGDW肽抑制血小板聚集的作用机制

目的研究RGD(精氨酸-甘氨酸-天门冬氨酸)肽衍生物-AoGDW(ω-氨基辛酸-甘氨酸-天门冬氨酸-色氨酸)抑制血小板聚集的作用机制。方法采用双色荧光标记以及流式细胞技术检测AoGDW肽对CD41抗体与血小板GPⅡb/Ⅲa受体结合的抑制作用以及对血小板膜上P-选择素表达的影响。结果随着AoGDW肽浓度的增加,CD41抗体与活化血小板GPⅡb/Ⅲa受体结合率呈现下降趋势,相对于阴性对照组,P<0.01。但CD41抗体与静止血小板GPⅡb/Ⅲa受体的结合率以及CD62p抗体与静止血小板P选择素的结合率与阴性对照组相比,P>0.05。结论AoG-DW肽是通过占据血小板上纤维蛋白原的结合位点即活化的GPⅡb/Ⅲa受体而发挥抑制血小板聚集的作用,并且不具有活化血小板的作用,是一种选择性的GPⅡb/Ⅲa受体拮抗剂。     

On the mechanism of plasmin-induced platelet aggregation. Implications of the dual role of granule ADP

Plasmin-induced platelet aggregation has been considered to be a cause of reocclusion after thrombolytic treatment with plasminogen activators. However, little is known regarding the mechanism and regulation of plasmin-induced platelet aggregation. In this study, we demonstrated that plasmin causes the degranulation of platelets, and that ADP released from granules plays a crucial role in the induction of platelet aggregation. This conclusion is supported by results showing that both ADP antagonists and ADPase can inhibit the effect of plasmin on platelets. We also demonstrated that pretreatment of platelets with ADP makes the platelets more sensitive to plasmin, and plasmin-induced platelet aggregation is, therefore, observed at lower concentrations where no aggregation occurs in quiescent platelets. In other words, it is thought that ADP potentiates the plasmin-induced aggregation. The effect of ADP was inhibited by N(6)-[2-(methylthio)-ethyl]-2-(3,3, 3-trifluoropropyl)thio-5'-adenylic acid, monoanhydride with dichloromethylenebisphosphonic acid (AR-C69931), a selective antagonist for the P2T(AC) subtype of P2 receptor, but not by the P2Y1 receptor-selective antagonist adenosine 3'-phosphate 5'-phosphosulfate (A3P5PS). The P2X1 receptor agonist alpha, beta-methylene adenosine 5'-triphosphate (alpha,beta-MeATP) did not mimic the action of ADP. These data indicate that ADP potentiates plasmin-induced platelet aggregation via the P2T(AC) receptor. In addition, epinephrine, a typical G(i) agonist against platelets, could potentiate the plasmin-induced platelet aggregation, suggesting that the signal via the G(i) protein is involved in potentiating the plasmin-induced platelet aggregation, ADP is secreted from platelet granules, and concomitantly works in conjunction with plasmin in a P2T(AC) receptor-mediated manner.     

Role of arachidonic acid in leukotriene B(4)-induced guinea-pig eosinophil homotypic aggregation

The activation of eosinophils with the lipid mediator, leukotriene B(4), induces their homotypic aggregation. Upon activation with leukotriene B(4), eosinophils release a significant amount of arachidonic acid, a process dependent on the activation of phospholipase A(2). Here, we have evaluated whether arachidonic acid could induce aggregation of eosinophils and whether the release of arachidonic acid mediated the aggregation induced by leukotriene B(4). The exogenous administration of arachidonic acid induced a concentration-dependent eosinophil homotypic aggregation. Pretreatment of eosinophils with a 5-lipoxygenase inhibitor or a leukotriene B(4) receptor antagonist abrogated arachidonic-acid-induced aggregation. Arachidonic acid induced a significant increase in leukotriene B(4) levels and desensitised leukotriene B(4)-induced aggregation in a dose-dependent manner. Moreover, this desensitisation was effectively reversed by a 5-lipoxygenase inhibitor. However, arachidonic acid failed to induce a rise in intracellular Ca(2+) in eosinophils and failed to desensitise these cells to rises in intracellular Ca(2+) induced by leukotriene B(4). Pretreatment of eosinophils with the phospholipase A(2) inhibitor, mepacrine, inhibited the aggregation responses induced by 1 nM leukotriene B(4) by approximately 50% but had no significant effect on the other concentrations of leukotriene B(4) tested (0.1 to 100 nM). In conclusion, arachidonic acid stimulates eosinophil aggregation indirectly via the release of leukotriene B(4). Although a significant amount of arachidonic acid is released in response to activation of eosinophils with leukotriene B(4), the arachidonic acid released does appear to play a major role in mediating leukotriene B(4)-induced eosinophil aggregation.     

Development of dual-acting benzofurans for thromboxane A2 receptor antagonist and prostacyclin receptor agonist: synthesis, structure-activity relationship, and evaluation of benzofuran derivatives

Prostacyclin (PGI(2)) is an unstable, powerful endogenous inhibitor of platelet aggregation, and thromboxane A(2) (TXA(2)) is an unstable endogenous arachidonic acid metabolite that plays a pivotal role in platelet aggregation and vasoconstriction. The balance between TXA(2) and PGI(2) greatly affects maintenance of the homeostasis of the circulatory system. A novel series of benzofuran-7-yloxyacetic acid derivatives was discovered as potent dual-acting agents to block the thromboxane A(2) receptor and to activate the prostacyclin receptor. Synthesis, structure-activity relationship, and in vitro and ex vivo pharmacology of this series of compounds are described. The most potent in the series was {3-[2-(1,1-diphenylethylsulfanyl)ethyl]-2-hydroxymethylbenzofuran-7-yloxy}acetic acid diethanolamine salt (7) with K(i) of 4.5 nM for thromboxane receptor antagonism and K(i) of 530 nM for prostacyclin receptor agonism. Remarkably, compound 7 is a promising candidate for novel treatment as an antithrombotic agent with other cardiovascular actions to avoid hypotensive side effects.     

Antiplatelet activity of carnosol is mediated by the inhibition of TXA2 receptor and cytosolic calcium mobilization

Carnosol, a naturally occurring phenolic diterpene found in rosemary, has been reported to exhibit antioxidant, anticancer and hepatoprotective effects. In the present study, the antiplatelet activity of carnosol was investigated. Carnosol concentration-dependently inhibited washed rabbit platelet aggregation induced by collagen and arachidonic acid (AA), with IC(50) values of 5.5+/-0.3 and 42.5+/-0.9 microM, respectively, while failed to inhibit that induced by, ADP and thrombin. Consist with inhibition of collagen-induced platelet aggregation, carnosol revealed blocking of collagen-mediated cytosolic calcium mobilization, serotonin secretion and arachidonic acid liberation. However, contrary to the inhibition of AA-induced platelet aggregation, carnosol has no effect on AA-mediated TXA(2) and PGD(2) formation, indicating carnosol may directly inhibit TXA(2) receptor, which was supported by the finding that carnosol potently inhibited U46619 (a TXA(2) mimic)-induced platelet aggregation, with an IC(50) value of 22.0+/-2.5 microM. In addition, the U46619-induced concentration-response curve was downward shifted by the application of carnosol at concentrations of 22 and 50 microM, indicating a typical non-competitive antagonism on TXA(2) receptor. Taken together, these results suggest that antiplatelet activity of carnosol may be mediated by the inhibition of TXA(2) receptor and cytosolic calcium mobilization, and carnosol has a potential to be developed as a novel-antiplatelet agent.     

Improved synthetic routes to the novel thromboxane receptor antagonist ICI 192605: activity of synthetic 1,3-dioxane intermediates

A study of the synthetic routes to the thromboxane receptor antagonist ICI 192605 4(Z)-6-(2-o-chlorophenyl-4-o-hydroxyphenyl-1,3-dioxan-cis-5-yl) hexenoic acid is described which led to an improvement in overall synthetic yield from 20 to 55%. Invitro thromboxane receptor antagonist data are reported for the novel 1,3-dioxane synthetic intermediates. These data indicated that shortening of the side chain in an appropriately substituted 2,2-dimethyl-1,3-dioxane (e.g. ICI 180080) from a heptenoic acid, to a hexenoic acid, had little effect on thromboxane receptor antagonist potency (pA2 = 7.5 rabbit thoracic aorta for the heptenoic acid ICI 180080 and pA2 = 6.9 for the corresponding hexenoic acid. Human platelet aggregation pA2 values were 6.7 and 7.0, respectively).     

木瓜蛋白酶体外对血小板聚集的抑制作用

目的：以洗涤血小板为模型,观察木瓜蛋白酶在体外对血小板聚集的抑制作用,以探讨其抗血栓作用的可能机制。方法：将不同剂量木瓜蛋白酶与洗涤血小板作用,以血小板聚集分析仪检测ADP、花生四烯酸（AA）、胶原和凝血酶诱导的血小板最大聚集率,以流式细胞仪检测活化血小板膜纤维蛋白原受体（FIB-R）和P-选择素表达水平,以SDS-PAGE分析血小板肌动蛋白聚合体的变化。检测ADP诱导的原发性高血压（PH）及急性心肌梗死（AMI）患者血小板最大聚集率和FIB-R表达水平。结果：木瓜蛋白酶剂量依赖性地抑制血小板聚集,降低血小板最大聚集水平,血小板聚集水平与木瓜蛋白酶剂量呈负相关（P〈0.01）。木瓜蛋白酶剂量依赖性地抑制ADP诱导的血小板FIB-R表达,降低FIB-R表达水平（P〈0.01）。木瓜蛋白酶降低ADP诱导的血小板膜P-选择素表达水平和抑制肌动蛋白聚合体增加（P〈0.01）。木瓜蛋白酶抑制PH及AMI患者血小板聚集和FIB-R表达（P〈0.01）。结论：木瓜蛋白酶通过抑制活化血小板膜纤维蛋白原受体的表达,并抑制肌动蛋白聚合以及释放反应从而剂量依赖性地抑制血小板的聚集反应,有抗血栓形成作用。     

Inhibition of platelet aggregation by vanilloid‐like agents is not mediated by transient receptor potential vanilloid‐1 channels or cannabinoid receptors

Vanilloid‐like agents, including capsaicin, N‐arachidonoyl‐dopamine and N‐oleoyldopamine inhibit platelet aggregation, however little is known about the precise mechanism(s) of action. The authors have previously shown that blocking of the capsaicin receptor, transient receptor potential vanilloid‐1 (TRPV1), does not interfere with capsaicin action during adenosine diphosphate (ADP)‐induced aggregation. This research is extended to investigate the effect of these vanilloid‐like‐agents on platelet count, and to test whether the effect of these agents is mediated through TRPV1 and/or cannabinoid (CB1 and CB2) receptors in the presence of other agonists, including collagen and arachidonic acid. Incubation of platelets with each of the individual vanilloids, or with receptor antagonists of TRPV1 (SB452533), CB1 (AM251) and CB2 (AM630), for up to 2 h did not significantly affect the platelet count. Similarly, the effect of individual vanilloids on the inhibition of platelet aggregation was not significantly different in the presence of receptor agonists compared to control, irrespective of the agonist used, suggesting that the inhibitory effect of vanilloids on platelet aggregation is independent of TRPV1, CB1 and CB2 receptors. Further research on the antiplatelet activity of vanilloids should focus on mechanisms other than those associated with vanilloid receptors.     

Activation of rabbit platelets by Ca2+ influx and thromboxane A2 release in an external Ca(2+)-dependent manner by zooxanthellatoxin-A, a novel polyol.

1. Zooxanthellatoxin-A (ZT-A), a novel polyhydroxylated long chain compound, isolated from a symbiotic marine alga Simbiodinium sp., caused aggregation in rabbit washed platelets in a concentration-dependent manner (1-4 microM), accompanied by an increase in cytosolic Ca2+ concentration ([Ca2+]i). 2. ZT-A did not cause platelet aggregation or increase [Ca2+]i in a Ca(2+)-free solution, and Cd2+ (0.1-1 mM), Co2+ (1-10 mM) and Mn2+ (1-10 mM) inhibited ZT-A-induced aggregation. SK&F96365 (1-100 microM), a receptor operated Ca2+ channel antagonist, and mefenamic acid (0.1-10 microM), a non-specific divalent cation channel antagonist, inhibited platelet aggregation and the increase in [Ca2+]i induced by ZT-A. 3. Indomethacin (0.1-10 microM), a cyclo-oxygenase inhibitor, and SQ-29548 (0.1-10 microM), a thromboxane A2 (TXA2) receptor antagonist, inhibited platelet aggregation and the increase in [Ca2+]i induced by ZT-A. 4. Methysergide (0.01-1 microM), a 5-HT2 receptor antagonist, inhibited ZT-A-induced platelet aggregation but did not affect the increase in [Ca2+]i induced by ZT-A. 5. Tetrodotoxin (1 microM), a Na+ channel blocker and chlorpheniramine (1 microM), a H1-histamine receptor antagonist, neither affected ZT-A-induced platelet aggregation nor the increase in [Ca2+]i induced by ZT-A. 6. Genistein (1-100 microM), a protein tyrosine kinase inhibitor, and staurosporine (0.01-1 microM), a protein kinase C inhibitor, also inhibited ZT-A-induced platelet aggregation. 7. The present results suggest that ZT-A elicits Ca(2+)-influx from platelet plasma membranes. The resulting increase in [Ca2+]i subsequently stimulates the secondary release of TXA2 from platelets.(ABSTRACT TRUNCATED AT 250 WORDS)     

Structure-activity relationships associated with 3,4,5-triphenyl-1H-pyrazole-1-nonanoic acid, a nonprostanoid prostacyclin mimetic.

A series of phenylated pyrazoloalkanoic acid derivatives were synthesized and evaluated as inhibitors of ADP-induced human platelet aggregation. 3,4,5-Triphenyl-1H-pyrazole-1-nonanoic acid (8d), with an IC50 of 0.4 microM, was the most potent inhibitor identified in this study. Biochemical studies determined that 8d increased intraplatelet cAMP accumulation and stimulated platelet membrane-bound adenylate cyclase in a concentration-dependent fashion. Displacement of [3H]iloprost by 8d from platelet membranes indicated that the platelet prostacyclin (PGI2) receptor is the locus of biological action. Structure-activity studies demonstrated that the minimum structural requirements for binding to the platelet PGI2 receptor and inhibition of ADP-induced platelet aggregation within this series are a vicinally diphenylated pyrazole substituted with an omega-alkanoic acid side chain eight or nine atoms long. Potency depended upon both side-chain length and its topological relationship with the two phenyl rings.     

ADP can induce aggregation of human platelets via both P2Y(1) and P(2T) receptors

1. In the present study we have investigated the roles of P2Y(1) and P(2T) receptor subtypes in adenosine 5'-diphosphate (ADP)-induced aggregation of human platelets in heparinized platelet rich plasma. 2. The response to ADP can be characterized as the initial rate or the maximum or final extent of aggregation. The response profile is determined by the concentration of ADP used, being transient at lower and sustained at higher concentrations. 3. The P2Y(1) receptor antagonist, adenosine-3'-phosphate-5'-phosphate (A3P5P) competitively antagonized the initial rate of aggregation (pK(B) 5. 47) and transformed the response profile to a slowly developing but sustained response. Both maximum and final extents were also inhibited by A3P5P although not in a competitive manner (Schild slope <1). 4. The P(2T) receptor antagonist, AR-C67085, competitively antagonized the final extent of aggregation (pK(B) 8.54), transforming the response profile to one of rapid, transient aggregation. Its effect on maximum extent (the most widely used index of aggregation) was complex, and further supported the involvement of both receptor subtypes in the aggregation response. 5. ADP-induced aggregation is a complex phenomenon, the nature of which is determined by the relative occupancy of the two receptor subtypes. While P2Y(1) receptor activation causes a rapid and transient aggregation, the extent of sustained aggregation is determined by the level of P(2T) receptor occupancy. Hence, detailed analysis of the aggregation response is essential to correctly define the purinergic pharmacology of the platelet and interpretation of results is critically dependent on the response index chosen.