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目的研究重症急性胰腺炎(severe acute pancreatitis,SAP)大鼠模型中是否存在从过度炎症反应状态向免疫抑制状态转变的病理生理过程以及免疫抑制转折点的发生时间。方法采用胰胆管逆行注射不同浓度牛磺胆酸钠的方法建立SAP大鼠模型;大鼠尾静脉注射不同浓度的铜绿假单胞菌(Pseudomonas aeruginosa,PA),观察大鼠7 d死亡率,筛选出PA亚致死剂量;然后在SAP建模后不同时间点给予亚致死剂量PA攻击,观察大鼠死亡率;在SAP建模后0 h、12 h、24 h给予PA攻击,ELISA检测各组大鼠血清、肝、肺及脾中TNF-α、IL-1β水平;在SAP建模后24 h给予PA攻击,五分类血液分析仪测定各组血常规,平板菌落计数的方法测定各组血清、肺及脾中细菌清除情况,ELISA检测各组大鼠血清、肝、肺及脾中TNF-α、IL-1β水平。结果采用胰胆管逆行注射5.0%牛磺胆酸钠的方法成功复制出48%死亡率的SAP大鼠模型;PA攻击大鼠的亚致死剂量为4.0×108CFU/kg;SAP大鼠在建模后不同时间点对PA的敏感性不同;SAP建模后24 h,大鼠对PA攻击呈现出高细菌敏感性,表现为血液中的高细菌负荷和低致炎细胞因子水平;此外,淋巴细胞和单核细胞数量和比例也呈现出显著降低状态。结论 SAP大鼠模型中存在从过度炎症反应状态向免疫抑制状态转变的病理生理过程;SAP大鼠模型建立后24 h是免疫抑制转折点。
Objective To investigate the pathophysiological process of transition from hyperactive inflammatory state to immunosuppressive state in rats with severe acute pancreatitis (SAP) and the time of onset of immunosuppressive turning point. Methods The rat model of SAP was established by retrograde injection of sodium taurocholate into pancreaticobiliary ducts. The rats were injected with different concentrations of Pseudomonas aeruginosa (PA) into the caudal vein to observe the mortality of rats for 7 days. Then the sub-lethal dose of PA was given out. Then the sublethal PA was given at different time points after SAP modeling to observe the death rate of rats. PA was given at 0, 12 and 24 h after SAP modeling. TNF-α and IL-1β levels in serum, liver, lung and spleen of rats. PA attack was given 24 h after SAP modeling. Blood samples of five groups were determined by blood analyzer. Bacterial eradication in lung and spleen was observed. The levels of TNF-α and IL-1β in serum, liver, lung and spleen of rats in each group were detected by ELISA. Results A 48% mortality SAP rat model was successfully obtained by retrograde injection of 5.0% sodium taurocholate into pancreaticobiliary duct. The sublethal dose of PA challenged rat was 4.0 × 108CFU / kg. After SAP model was established At different time points, the sensitivity to PA was different; at 24 h after SAP modeling, the rats exhibited high bacterial sensitivity to PA challenge with high bacterial load and low levels of pro-inflammatory cytokines in the blood; in addition, lymphocytes and The number and proportion of monocytes also showed a marked decrease. Conclusion There is pathophysiological process in the rat model of SAP from the state of over-inflammatory reaction to immunosuppressive state. The immunosuppressive turning point was observed 24 h after SAP rat model was established.