中文摘要：

探讨阻断细胞外高迁移率簇蛋白B1（HMGBI）功能对阿霉素诱导型心肌损伤的预防作用及其机制。HMGBl阻断剂甘草甜素于阿霉素造模前1h及造模后每天按10mg／只的剂量腹腔注射，第14天结束实验。利用超声心动和血流动力学检测心脏功能，免疫组化和天狼猩红染色观察心脏局部炎症及胶原沉积情况，免疫共沉淀和免疫共聚焦显微镜分析HMGBl与TLR2相互作用，Immunoblot检测HMGBl、MyD88、p65NF-kB及phospho．p65NF-kB蛋白含量。结果表明，与正常对照组相比，阿霉素处理引起HMGBl表达明显增加。阻断HMGBl抑制阿霉素引起的心功能失调、炎症反应及心肌纤维化。甘草甜素抑制HMGBl与TLR2相互作用以及TLR2下游信号激活。以上结果提示，阻断HMGBl通过抑制TLR2信号通路，可以改善阿霉素诱导的心肌损伤。

英文摘要：

This study aims to investigate the preventive role and potential mechanisms of blocking extracellular HMGB 1 function on doxorubicin induced cardiac injury. Mice were treated with HMGB 1 blocker glycyrrhizin 1 h before and one time every day （intraperitoneal, 10 mg per mouse） after doxorubicin injection, and sacrificed on the day 14 after doxorubicin challenge. Cardiac function was evaluated by echocardiography and hemodynamic measurement. Myocardial inflammation and collagen deposition were analyzed by immunohistochemistry and picrosirius red staining. The interaction of HMGB1 and TLR2 was assessed by co-immunoprecipitation and confocal microscopy. The protein contents of HMGB1, MyD88, p65NF-kB and phospho-p65NF-kB were measured by Immunoblot. Compared with mice treated with saline, doxorubicin treatment led to an upregulation in HMGB1 expression. Blocking HMGB1 activity with glycyrrhizin protected mice against cardiac dysfunction, inflammatory response, and cardiac fibrosis induced by doxorubicin challenge. Glycyrrhizin inhibited the interaction of HMGB1 and TLR2, and blocked the downstream signaling of TLR2. In conclusion, blocking HMGB1 protected against doxorubicin induced cardiac injury by inhibiting TLR2 signaling pathway.