穿心莲内酯在铜绿假单胞菌诱导的大鼠肺部感染模型中的抗炎作用及其作用机制

摘要

目的：探讨穿心莲内酯在大鼠铜绿假单胞菌（PA ）肺部感染时的抗炎作用及可能的机制。方法采用气管滴注法建立大鼠PA肺部感染模型。先分为不同时间感染组（0、24、48、72和96 h），分别取大鼠静脉血及肺泡灌洗液进行白细胞计数及分类计数，并用逆转录-聚合酶链反应（PCR）检测肺组织匀浆中 Toll 样受体4（TLR4）的变化，选一峰值时间点；后分为感染组、溶剂组和给药组（5、10、15和20μg/g体重给予穿心莲内酯），于峰值点取上述标本做相应指标检测。结果 PA感染后，大鼠血液白细胞总数于24 h下降，随后上升，于48 h达峰值；肺泡灌洗液细胞总数上升，于48 h达峰值。48 h组血白细胞、肺泡灌洗液白细胞和肺组织匀浆液中TLR4 mRNA水平较其他组高；给予穿心莲内酯后血液白细胞、肺泡灌洗液细胞总数和TLR4 mRNA有不同程度下降，呈剂量依赖关系。结论 PA肺部感染可引起TLR4 mRNA的改变，穿心莲内酯可有效抑制PA感染引起的肺部炎症反应，其可能通过调控TLR4 mRNA的表达来实现。%Objective To investigate the anti-inflammatory role and mechanism of andrographolide on Pseudomonas aeruginosa (PA)-induced lung inflammation in rats.Methods The rat′s model of PA-induced lung inflammation was established and classified into different time groups(0,24,48,72 and 96h).The white blood cell count and leukocyte classification were determined in blood and bronchoalveolar lavage fluid.Reverse transcription polymerase chain reaction (PCR)was used to determine the level of Toll-like receptor 4 (TLR4)in lung tissue,a peak time point was selected, and the subjects were classified into infection group,solvent group and treatment group(5,10,15 and 20μg/g body weight for andrographolide),and the rat blood,bronchoalveolar lavage fluid and lung tissue at the peak time point were used for testing various indicators.Results After PA inflammation,the white blood cell count decreased in 24 h,then increased and reached the peak point at 48 h .The total cell count in bronchoalveolar lavage fluid reached the peak point at 48 h.The mRNA expressions of TLR4 in white blood cell,bronchoalveolar lavage fluid and lung tissue were higher than the others.After receiving andrographolide,the white blood cell count,the total cell count of bronchoalveolar lavage fluid and TLR4 mRNA decreased to various degrees,and had dose-dependent manner.Conclusions PA-induced lung inflammation is related with TLR4 mRNA expression changes,and andrographolide can effectively suppress lung inflammation induced by PA.Its anti-inflammatory mechanism may be achieved through the regulation of TLR4 mRNA expression.