摘要目的 探讨脂多糖(LPS)诱发小鼠血小板减少中血小板活化、血小板对Toll样受体4 (TLR4)的表达的变化及中性粒细胞对其影响.方法 中国医学科学院放射医学研究所ICR小鼠87只随机(随机数字法)分为健康对照(C)组、模型(M)组(3,6,12,24,48,72 h时点)及中性粒细胞减少症(NEP)组.M组尾静脉注射LPS 8 mg/kg后分别于相应时点取血,NEP组注射LPS 24 h前予尾静脉注射抗中性粒细胞单克隆抗体,注射LPS24h后取血.血细胞分析仪检测小鼠血小板参数:血小板计数(PC)、平均血小板体积( MPV)和血小板分布宽度(PDW)；ELISA法检测小鼠血浆肿瘤坏死因子-α(TNF-α)、巨噬细胞集落刺激因子(M-CSF)和可溶性CD40配体(sCD40 L)浓度；流式细胞仪检测血小板TLR4阳性表达率.组间比较采用单因素方差分析.结果 尾静脉注射LPS3h后小鼠PC(×109 L-1)下降30％[(719.8±135.9) vs.(1013.1±136.6,P＜0.01],24h内达谷值[(374.7±115.1) vs.(1013.1±136.6),P＜0.01]；MPV和PDW 12～48 h较C组增大(P＜0.01)；LPS攻击后6～24h血浆TNF-α,M-CSF,sCD40L显著升高(与C组比较P ＜0.01),PC与血浆M-CSF(r=-0.746,P＜0.01),sCD40L(r=-0.573,P＜ 0.001)水平负相关；LPS刺激6h后血小板TLR4阳性表达(％)较C组增加[ (50.37±3.20) vs.(45.76±2.49) P＜0.01]；NEP组血小板TLR4表达率(％)低于M组同时点[ (48.32±2.17) vs.(55.69±3.95,P＜0.01].结论 以sCD40L及M-CSF升高为代表的血小板过度活化与血小板TLR4表达中性粒细胞依赖性上调共同参与脂多糖诱发小鼠血小板减少.

abstractsObjective To determine the role of the platelet activation and the expression of platelet Toll-like receptor 4 (TLR4) in thrombocytopenia induced by lipopolysaccharide (LPS) in mice.Methods ICR mice were randomly (random number) divided into control group,model 3,6,12,24,48,72h groups and neutrocytopenia syndrome (NEP) group.The blood samples of mice in model groups were detected 3,6,12,24,48,and 72 hours after intravenous injection of LPS respectively.Anti- neutrophil monoclonal antibody was administered in the mice of NEP group 24 h before injection of LPS,and blood samples were collected 24 h after injection of LPS.The determination of platelet count (PC),mean platelet volume (MPV) and platelet distribution width (PDW) was carried out with full automatic hemocyte analyzer.The plasma tumor necrosis factor- α (TNF- α),macrophage colony stimulating factor (M-CSF) and soluble CD40 ligand (sCD40L) levels were measured by using ELISA.The rate of platelet TLR4 expression was detected by flow cytometry.Comparison between groups was carried out by using ANOVA statistical methods.Results PC was reduced by 30％ 3 h after intravenous injection of LPS,and reached the lowest level within 24 h (P ＜0.01 ).MPV and PDW were increased compared with healthy controls (P ＜0.01 ).Plasma TNF - α,M - CSF and sCD40L were significantly increased after LPS stimulation (P ＜0.01 ),and reached the peak during 6 ～ 24 h after LPS administration.PC had correlation with plasma levels of M - CSF ( r =- 0.746) and sCD40L ( r =- 0.573 ).The platelet TLR4 expression was significantly increased 6 h after LPS stimulation.The platelet TLR4 expression in NEP group was significantly lower than that in 24 h model group ( P ＜ 0.01 ).Conclusions The excessive activation platelet represented by increase in sCD40L,MPV,PDW and high levels of M-CSF in macrophages along with platelet TLR4 expression participate in the pathogenesis of thrombocytopenia.The up - regulation of the platelet TLR4 expression is dependent on neutrophils in case of thrombocytopenia induced by LPS.