How does measurement of platelet P-selectin compare with other methods of measuring platelet function as a means of determining the effectiveness of antiplatelet therapy?

Measurement of P-selectin on activated platelets as a means of measuring platelet function utilizing the technology described here has the advantage of not requiring immediate access to specialist equipment and expertise. Blood samples are activated, fixed, stored, and transported to a central laboratory for flow cytometric analysis. Here we have compared P-selectin with other more traditional approaches to measuring platelet function in blood and/or platelet-rich plasma (PRP) from patients with acute coronary syndromes on treatment for at least 1 month with either aspirin and clopidogrel or aspirin with prasugrel. The comparators were light transmission aggregometry (LTA), VerifyNow and Multiplate aggregometry (for determining the effects of aspirin) and LTA, VerifyNow and Multiplate together with the BioCytex VASP phosphorylation assay (for the P2Y₁₂ antagonists). The P-selectin Aspirin Test revealed substantial inhibition of platelet function in all but three of 96 patients receiving aspirin with clopidogrel and in none of 51 patients receiving aspirin and prasugrel. The results were very similar to those obtained using LTA. There was only one patient with high residual platelet aggregation and low P-selectin expression. The same patients identified as “non-responders” to aspirin also presented with the highest residual platelet activity as measured using the VerifyNow system, although not quite as well separated from the other values. With the Multiplate test only one of these patients clearly stood out from the others. The results obtained using the P-selectin P2Y₁₂ Test in 102 patients taking aspirin and clopidogrel were similar to the more traditional approaches in that a wide scatter of results was obtained. Generally, high values seen with the P-selectin P2Y₁₂ Test were also high with the LTA, VerifyNow, Multiplate, and BioCytex VASP P2Y₁₂ Tests. Similarly, low residual platelet function using the P2Y₁₂ test was seen irrespective of the testing procedure used. However, there were differences in some patients. Prasugrel was always more effective than clopidogrel in inhibiting platelet function with none of 56 patients (P-selectin and VerifyNow), only 2 of 56 patients (Multiplate) and only 3 of 56 patients (Biocytex VASP) demonstrating high on-treatment residual platelet reactivity (HRPR) defined using previously published cut-off values. The exception was LTA where there were 11 of 56 patients with HRPR. It remains to be seen which experimental approach provides the most useful information regarding outcomes after adjusting therapies in treated patients.     

喉癌患者PAC-1、CD62P表达与临床病理特征和复发的关系

目的探讨喉癌患者血小板表面血小板膜糖蛋白Ⅱb/Ⅲa纤维蛋白原受体(PAC-1)、血小板P-选择素(CD62P)阳性表达率以及与患者临床病理特征和复发的关系。方法选取2014年1月~2015年12月间在我院耳鼻喉科手术治疗的116例喉癌患者,随访≥2年,并选取同期在我院体检的健康人群60例为对照组,采用流式细胞仪检测法检测外周血PAC-1和CD62P阳性率,并分析与临床病理特征、复发的关系。结果喉癌患者PAC-1和CD62P阳性表达率分别为(17.82±1.76)%和(22.87±3.13)%,明显高于健康人群(P<0.05);而且在喉癌患者PAC-1表达和CD62P表达呈正相关性(r=0.238,P<0.05)。T3-T4分期或N2-N3分期患者PAC-1和CD62P阳性表达率高于T1-T2分期或N0-N1分期患者(P<0.05)。另外远处转移组PAC-1和CD62P阳性表达率高于未发生转移组(P<0.05);随访期间有24例患者复发,复发率为20.69%。复发喉癌患者PAC-1、CD62P阳性表达率分别为(17.02±0.85)%和(21.84±1.17)%,明显高于未复发的喉癌患者(P<0.05)。经Logistics回归分析,PAC-1和CD62P是喉癌患者复发的独立危险因素(P<0.05)。结论PAC-1和CD62P阳性表达率与喉癌患者T分期、淋巴结转移和远处转移密切相关,同时可作为喉癌局部复发、区域淋巴结转移、远处转移的预测指标。     

Effect of steroids on the activation status of platelets in patients with Immune thrombocytopenia (ITP)

The activation status of platelets in Immune Thrombocytopenia (ITP) patients – which is still somewhat controversial – is of potential interest, because activated platelets tend to aggregate (leading to excessive clotting or thromboembolic events) but cannot do so when platelet numbers are low, as in ITP. Although corticosteroids are the first line of therapy in ITP, the effect of steroids on activation of platelets has not been evaluated so far. We examined the status of platelet activation (with and without stimulation with ADP) in ITP patients, at the start of therapy (pre-steroid treatment, naive) and post-steroid treatment (classified on the basis of steroid responsiveness). We used flow cytometry to evaluate the levels of expression of P-selectin, and PAC-1 binding to platelets of 55 ITP patients and a similar number of healthy controls, treated with and without ADP. We found that platelets in ITP patients exist in an activated state. In patients who are responsive to steroids, the treatment reverses this situation. Also, the fold activation of platelets upon treatment with ADP is more in healthy controls than in ITP patients; treatment with steroids causes platelets in steroid-responsive patients to become more responsive to ADP-activation, similar to healthy controls. Thus steroids may cause changes in the ability of platelets to get activated with an agonist like ADP. Our results provide new insights into how, and why, steroid therapy helps in the treatment of ITP.     

外周血指标对急性出血性脑卒中深静脉血栓的诊断价值研究

目的探讨P选择素、D-二聚体、同型半胱氨酸(Hcy)超敏C反应蛋白(hs-CRP)对急性出血性脑卒中的诊断价值。方法于2015年3月至2016年3月,根据血栓形成情况,将60例急性出血性脑卒中患者分为血栓组(28例)和非血栓组(32例)。20例体检健康纳入对照组。检测各研究组外周血P选择素、D-二聚体、Hcy、hs-CRP水平。结果血栓组患者年龄大于无血栓组(P0.05)。血栓组P选择素、D-二聚体水平高于无血栓组和对照组(P0.05);无血栓组P选择素、D-二聚体水平高于对照组(P0.05)。血栓组、无血栓组hs-CRP水平高于对照组(P0.05),但血栓组和无血栓组比较差异无统计学意义(P0.05)。P选择素、D-二聚体联合检测对DVT的诊断灵敏度和特异度分别为96.4%和83.3%,受试者工作特征曲线下面积为0.937。结论 P选择素和D-二聚体联合检测对脑卒中后DVT具有较高的诊断价值。     

槲皮素对急性肺损伤大鼠P-选择素的影响

目的探讨槲皮素 (quercetin)对内毒素急性肺损伤 (ALI)大鼠P 选择素的影响。方法 :应用脂多糖 (LPS ,6mg/kg ,iv)复制大鼠ALI模型。选用SD大鼠 2 4只 ,随机分成盐水对照组、内毒素组、槲皮素干预组。各组大鼠均于注射LPS或生理盐水 6h后放血处死 ,然后观察肺病理改变、肺湿 /干重比 (W /D)值及动脉血氧分压 (PaO2 )、值 ,放射免疫法测定血清和肺组织匀浆P 选择素浓度。结果 :注射LPS 6h后 ,W /D、肺组织匀浆MPO、血清和肺组织匀浆P 选择素含量均有显著升高 (P 0 .0 1) ,PaO2 显著降低 ;而预先给予槲皮素可显著缓解上述变化 (P 0 .0 1或P 0 .0 5 ) ,肺组织病理改变明显减轻。结论 :槲皮素能改善大鼠ALI时气体交换功能 ,抑制P 选择素的释放 ,对内毒素诱导的ALI有保护作用。     

Targeted gene disruption demonstrates that P-selectin glycoprotein ligand 1 (PSGL-1) is required for P-selectin-mediated but not E-selectin-mediated neutrophil rolling and migration

P-selectin glycoprotein ligand 1 (PSGL-1) is a mucin-like selectin counterreceptor that binds to P-selectin, E-selectin, and L-selectin. To determine its physiological role in cell adhesion as a mediator of leukocyte rolling and migration during inflammation, we prepared mice genetically deficient in PSGL-1 by targeted disruption of the PSGL-1 gene. The homozygous PSGL-1-deficient mouse was viable and fertile. The blood neutrophil count was modestly elevated. There was no evidence of spontaneous development of skin ulcerations or infections. Leukocyte infiltration in the chemical peritonitis model was significantly delayed. Leukocyte rolling in vivo, studied by intravital microscopy in postcapillary venules of the cremaster muscle, was markedly decreased 30 min after trauma in the PSGL-1-deficient mouse. In contrast, leukocyte rolling 2 h after tumor necrosis factor alpha stimulation was only modestly reduced, but blocking antibodies to E-selectin infused into the PSGL-1-deficient mouse almost completely eliminated leukocyte rolling. These results indicate that PSGL-1 is required for the early inflammatory responses but not for E-selectin-mediated responses. These kinetics are consistent with a model in which PSGL-1 is the predominant neutrophil P-selectin ligand but is not a required counterreceptor for E-selectin under in vivo physiological conditions.     

血小板P选择素阳性表达对脓毒症患者预后的预测价值

目的 评价脓毒症患者血液中血小板P选择素阳性表达率对脓毒症患者预后的预测价值。方法 回顾性分析江苏大学附属医院重症监护室(ICU)2016年12月—2018年12月期间收治20例脓毒症和17例脓毒症休克患者临床资料;同时选取20例该院体检中心的健康体检人员作为对照组。比较3组患者血小板P选择素阳性表达率的差异;采用相关分析法判断血小板P选择素阳性表达率与患者预后的相关性;利用受试者工作特征(ROC)曲线评价血小板P选择素对脓毒症患者28天病死率的预测价值。结果 脓毒症休克患者的血小板P选择素阳性率高于脓毒症组,亦高于对照组(F=55.578,P<0.01)。血小板P选择素阳性率与脓毒症患者ICU滞留时间成正性弱相关(r=0.367,P=0.025), 与28天病死率成正性强相关(r=0.679,P=0.000)。ROC曲线提示,血小板P选择素预测脓毒症患者28天病死率的截断值为28.54%,AUC为0.928,95%CI为0.842~1.014,敏感性72.73%,特异性96.15%。结论 血小板P选择素对脓毒症患者28天病死率具有较高的预测价值。     

P选择素、高敏C反应蛋白、血小板在冠心病及急性心梗的意义

目的 探讨P选择素(P-selectin)、高敏C反应蛋白(hs-CRP)、血小板在冠心病及急性心肌梗死患者血清中的变化及临床意义.方法 选取急性心肌梗死患者40例,冠心病患者40例,健康对照者40例.采用酶联免疫吸附试验(EL ISA)方法,测定血清中的P选择素、hs-CRP、血小板水平,运用q检验等统计学方法进行分析.结果 急性心梗患者P选择素显著高于冠心病组和对照组,冠心病组高于对照组,差异具有统计学意义.急性心梗患者hs-CRP明显高于冠心病组和对照组,冠心病组与对照组差异无统计学意义,血小板三组之间差异无统计学意义.结论 P选择素的变化是血小板活化较特异的指标,对缺血性心脏病的判定有重要价值,优于hs-CRP,联合检测hs-CRP更能反映冠心病的发展趋势.     

Effects of ethyl pyruvate on leukocyte-endothelial interactions in the mesenteric microcirculation during early sepsis treatment

OBJECTIVES:Experimental studies on sepsis have demonstrated that ethyl pyruvate is endowed with antioxidant and anti-inflammatory properties. This study aimed to investigate the effects of ethyl pyruvate on leukocyte-endothelial interactions in the mesenteric microcirculation in a live Escherichia coli-induced sepsis model in rats.METHODS:Male Wistar rats were administered an intravenous suspension of E. coli bacteria or were subjected to a sham procedure. Three hours after bacterial infusion, the rats were randomized into the following groups: a control group without treatment, a group treated with lactated Ringer''s solution (4 mL/kg, i.v.), and a group treated with lactated Ringer''s solution (4 mL/kg, i.v.) plus ethyl pyruvate (50 mg/kg). At 24 h after bacterial infusion, leukocyte-endothelial interactions were investigated using intravital microscopy, and the expression of P-selectin and intercellular adhesion molecule-1 was evaluated via immunohistochemistry. White blood cell and platelet counts were also determined at baseline and 3 h and 24 h after E. coli inoculation.RESULTS:The non-treated and lactated Ringer''s solution-treated groups exhibited increases in the numbers of rolling leukocytes (∼2.5-fold increase), adherent cells (∼3.0-fold), and migrated cells (∼3.5-fold) compared with the sham group. In contrast, treatment with Ringer''s ethyl pyruvate solution reduced the numbers of rolling, adherent and migrated leukocytes to the levels observed in the sham group. Additionally, the expression of P-selectin and intercellular adhesion molecule-1 was significantly increased on mesenteric microvessels in the non-treated group compared with the sham group (p<0.001). The expression of both adhesion molecules was reduced in the other groups, with ethyl pyruvate being more effective than lactated Ringer''s solution. Infusion of bacteria caused significant leukopenia (3 h), followed by leukocytosis with granulocytosis (24 h). There was also an intense and progressive reduction in the number of platelets. However, no differences were observed after treatment with the different solutions.CONCLUSIONS:The presented data suggest that ethyl pyruvate efficiently reduces the inflammatory response in the mesenteric microcirculation in an experimental model of sepsis induced by live E. coli and is associated, at least in part, with down-regulation of P-selectin and intercellular adhesion molecule-1.     

P-selectin-mediated platelet adhesion promotes tumor growth

Blood platelets foster carcinogenesis. We found that platelets are accumulated in human tumors. P-selectin deficiency and soluble P-selectin abolish platelet deposition within tumors, decreasing secretion of vascular endothelial growth factor and angiogenesis, thereby suppressing tumor growth. Binding of the P-selectin cytoplasmic tail to talin1 triggers the talin1 N-terminal head to interact with the β3 cytoplasmic tail. This activates αIIbβ3 and recruits platelets into tumors. Platelet infiltration into solid tumors occurs through a P-selectin-dependent mechanism.