博莱霉素致肺纤维化大鼠模型的纤溶变化及低分子肝素的作用

Changes of Fibrinolysis in Rats with Bleomycin-induced Pulmonary Fibrosis and the Effects of Low Molecular Weight Heparin

目的探讨博莱霉素诱导大鼠肺纤维化过程中纤溶变化与肺纤维化的关系,观察低分子肝素的作用并探讨其机制。方法75只Wistar大鼠分为低分子肝素(LMWH)组、强的松组、低分子肝素和强的松联合用药组、模型组、对照组。应用气管内灌注博莱霉素A5制备大鼠肺纤维化模型,于第15天开始每天给药(低分子肝素或强的松或联合给药),第28、42、56天取肺组织行苏木精-伊红和Masson染色以观察其病理变化,免疫组织化学方法测定纤维蛋白溶解酶原激活物抑制因子-1(PAI-1)的表达,加钙法测定优球蛋白溶解时间(ELT)。结果模型组PAI-1表达明显升高、ELT延长(均P<0.05),肺纤维化严重,但PAI-1表达与时间无相关性;LMWH组PAI-1表达持续降低,较强的松组显著,ELT明显缩短(均P<0.05),肺纤维化程度减轻;联合用药组肺纤维化程度减轻、PAI-1表达降低、ELT明显缩短(均P<0.05)。结论大鼠肺纤维化出现PAI-1高表达、ELT延长,纤溶活性下降。而LMWH能减轻大鼠肺纤维化,与强的松联合应用效果更明显,可能与抑制PAI-1表达、缩短ELT,提高纤溶活性有关。

Objective To study the changes of fibrinolysis and their relation to pulmonary fibrosis during bleomycin-induced lung fibrosis in rats,and investigate the role and mechanism of low molecular weight heparin（LMWH）.Methods Seventy-five Wistar rats were randomly divided into LMWH group,prednisone group,LMWH plus prednisone group,model group,and control group.Fibrosis was induced in rats by intratracheal instillation of bleomycine,then the rats received daily administration from the 15th day（LMWH or prednisone or combined treatment）.At the day 28,42,and 56 the rats were sacrificed in batches,and the sections of lungs were stained with HE and Masson＇s trichrome to evaluate the pathological changes.The expression of plasminogen activator inhibitor-1（PAI-1） in lung tissues was detected by means of immunohistochemistry.Euglobulin lysis time（ELT） was tested by adding quantitive calcium.Results The increased expression of PAI-1,prolonged ELT and severe pulmonary fibrosis were observed in the model group（all P〈0.05）.But there was no correlation between PAI-1 level and time in the model group.The expression of PAI-1 was decreased persistently in the LMWH group as compared with prednisone group.Moreover ELT was significantly shortened（all P〈0.05）,and pulmonary fibrosis was alleviated.The pulmonary fibrosis was alleviated,the expression of PAI-1 up-regulated,and ELT prolonged in combined treatment group（all P〈0.05）.Conclusion In rats with pulmonary fibrosis,the expression of PAI-1 was up-regulated,ELT prolonged,and fibrinolysis activity decreased.LMWH could attenuate pulmonary fibrosis of rats,and exert more significant effect in combination with prednisone probably by inhibiting the expression of PAI-1,shortening ELT,and increasing fibrinolysis activity in rats.