Murohara T, Guo J P, Lefer A M
Department of Physiology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
J Pharmacol Exp Ther. 1995 Sep;274(3):1246-53.
Polymorphonuclear neutrophils (PMN) play an important role in myocardial ischemia/reperfusion (MI/R) injury; however, the role of neutrophilic proteases is less understood. The effects of a novel serine protease inhibitor (serpin), LEX032, were investigated in a murine model of MI (20 min) and R (24 hr) injury in vivo. LEX032 is a recombinant human alpha 1-antichymotrypsin in which six amino acid residues were replaced around the active center with those of alpha-1 protease inhibitor. LEX032 has the ability to inhibit both neutrophil elastase and cathepsin G, two major neutral serine proteases in neutrophils, as well as superoxide generation. LEX032 (25 or 50 mg/kg) administered i.v. 1 min before reperfusion significantly attenuated myocardial necrotic injury evaluated by cardiac creatine kinase loss compared to MI/R rats receiving only vehicle (P < .001). Moreover, cardiac myeloperoxidase activity, an index of PMN accumulation, in the ischemic myocardium was significantly attenuated by LEX032 as compared with rats receiving vehicle (P < .001). LEX032 also moderately attenuated leukotriene B4-stimulated PMN adherence to rat superior mesenteric artery endothelium and markedly diminished superoxide radical release from LTB4-stimulated PMN in vitro. In a glycogen-induced rat peritonitis model, LEX032 (50 mg/kg) significantly attenuated PMN transmigration into the peritoneal cavity in vivo. In conclusion, the recombinant serine protease inhibitor, LEX032, appears to be an effective agent for attenuating MI/R injury by inhibiting neutrophil-accumulation into the ischemic-reperfused myocardium and by inactivating cytotoxic metabolites (proteases and superoxide radical) released from neutrophils.
多形核中性粒细胞（PMN）在心肌缺血/再灌注（MI/R）损伤中起重要作用；然而，嗜中性蛋白酶的作用尚不太清楚。在体内MI（20分钟）和R（24小时）损伤的小鼠模型中研究了一种新型丝氨酸蛋白酶抑制剂（丝氨酸蛋白酶抑制剂）LEX032的作用。LEX032是一种重组人α1-抗糜蛋白酶，其活性中心周围的六个氨基酸残基被α-1蛋白酶抑制剂的氨基酸残基取代。LEX032能够抑制中性粒细胞弹性蛋白酶和组织蛋白酶G，这是中性粒细胞中的两种主要中性丝氨酸蛋白酶，以及超氧化物的产生。与仅接受载体的MI/R大鼠相比，在再灌注前1分钟静脉注射LEX032（25或50mg/kg）可显著减轻通过心脏肌酸激酶损失评估的心肌坏死损伤（P<.001）。此外，与接受载体的大鼠相比，LEX032显著减轻了缺血心肌中作为PMN积累指标的心脏髓过氧化物酶活性（P<.001）。LEX032还适度减轻了白三烯B4刺激的PMN对大鼠肠系膜上动脉内皮的粘附，并显著减少了体外LTB4刺激的PMN中超氧化物自由基的释放。在糖原诱导的大鼠腹膜炎模型中，LEX032（50mg/kg）在体内显著减轻了PMN向腹腔的迁移。总之，重组丝氨酸蛋白酶抑制剂LEX032似乎是一种有效的药物，可通过抑制中性粒细胞向缺血再灌注心肌中的积累以及使从中性粒细胞释放的细胞毒性代谢产物（蛋白酶和超氧化物自由基）失活来减轻MI/R损伤。
