脂多糖预处理对大鼠肝移植再灌注期肝脏的保护作用及机制

Protective effect of lipopolysaccharide preconditioning on ischemia/reperfusion injury of rat graft liver

目的探讨脂多糖LPS预处理对大鼠肝移植再灌注期肝脏的保护作用及机制。方法90只雄性SD大鼠,分为假手术组(Sham组)、原位肝移植组(OLT组)和原位肝移植+LPS预处理组(LPS组)。Sham组只开腹分离肝十二指肠韧带,OLT组和LPS组按两袖套法进行肝移植。Sham组于分离肝十二指肠韧带后0、60、180 m in,OLT组和LPS组于门静脉血流恢复后0、60、180 m in分别测定各时相点血清TNF-α、ALT、AST水平及肝组织NF-κB活性,并取肝组织行光镜、电镜检查。结果再灌注后0、60、180 m in,OLT组与LPS组的NF-κB活性、TNF-α含量均高于Sham组(P<0.01);再灌注后60、180 m in,OLT组的NF-κB活性以及TNF-α含量均明显高于LPS组(P<0.01),且OLT组的ALT、AST水平明显高于LPS组(P<0.01),光镜及电镜下观察OLT组肝组织损害较LPS组重。结论肝移植再灌注期内毒素信号转导通路的NF-κB活性增强,产生炎性介质对移植肝造成损害;LPS预处理可降低肝移植再灌注期肝脏NF-κB活性和炎性介质的产生,从而减轻肝脏的损害。

Objective To investigate the protective effect and the possible mechanism of lipopolysaccharide （LPS） preconditioning on ischemia/reperfusion injury of rat graft liver. Methods Male Sprague-Dawley rats were divided into three groups （n = 30 in each group） ： sham operation group （Sham group）, orthotopic liver transplantation group （ OLT group） and LPS preconditioning group （ LPS group）. Only dissecting hepatoduodenal ligament was perfomed in Sham group. On day one, 0.1 mg/kg LPS and on day 2, 3, 4, 5, 0.5 mg/kg LPS for LPS rats and 0.5 ml PBS pathogen-free solution for OLT rats was injected through caudal vein before OLT was performed by two-cuff method in the two group rats on day 8. The levels of tumor necrosis factor-α （TNF-α）, ALT, AST in inferior caval vein blood and the activities of NF-κB in hepatic tissue were de- tected at 0, 60, 180 min after dissecting hepatoduodenal ligament in Sham group and after portal vein reperfusion in OLT group and LPS group. The morphological changes of hepatic tissue were observed through light microscope and electron microscope at different time points. Results As compared with Sham group at the different time points respectively, the activities of NF-κB and the levels of TNF-α were higher in OLT group and LPS group （P 〈0.01 ）. These indexes were evidently higher in OLT group than in LPS group （P 〈0.01 ） at 60 min and 180 rain after reperfusion. Furthermore, the levels of ALT and AST in OLT group were significantly higher than in LPS group （P 〈0.01 ） at 60 min and 180 min after reperfusion. Similarly, the histologic damage in the hepatic tissue in OLT group was more serious than in LPS group. Conclusion The activities of NF-κB in endotoxin signaling pathways were enhanced and the numerous inflammatory mediators were released to damage the graft liver. LPS preconditioning could decrease the activities of NF-κB and the release of inflammatory mediators to protect the graft liver against ischemia/reperfusion injury.