抑制Toll样受体4/核因子κB(TLR4/NF-κB)通路加重鲍曼不动杆菌感染大鼠的炎症

Blockade of TLR4/NF-κB pathway promotes the inflammation of Acinetobacter baumannii-infected rats

目的利用Toll样受体4(TLR4)抑制剂TAK-242处理大鼠,检测鲍曼不动杆菌(A.baumannii)感染过程中TLR4的作用。方法将健康雄性SD大鼠分为正常对照组、TAK-242处理组、A.baumannii接种组以及TAK-242和A.baumannii联合处理组。TAK-242处理组大鼠通过尾静脉注射TAK-242(1 mg/kg),感染大鼠通过气道接种方法接种A.baumannii。于接种后72 h,取肺组织匀浆后接种至LB培养基,进行肺组织细菌计数;HE染色观察肺组织炎症变化。收集支气管肺泡灌洗液(BALF),ELISA检测BALF中肿瘤坏死因子α(TNF-α)和白细胞介素6(IL-6)水平。分离外周血单个核细胞(PBMC),Western blot法检测PBMC中磷酸化核因子κBp65(p-NF-κBp65)的蛋白水平。结果免疫功能正常的大鼠感染A.baumannii 72 h后,肺内细菌基本被清除,而TAK-242处理的大鼠接种A.baumannii后,肺中细菌计数显著增加;正常大鼠感染后,肺部有轻微炎症,TAK-242处理的大鼠接种A.baumannii后肺部炎症较为明显;TAK-242处理的大鼠接种A.baumannii后,TNF-α和IL-6增加幅度小于正常感染组大鼠;正常大鼠感染A.baumannii 72 h后,PBMC中p-NF-κBp65蛋白水平升高,而经过TAK-242处理的大鼠感染后,PBMC中p-NF-κBp65的水平升高不明显。结论抑制TLR4/NF-κB通路引起大鼠A.baumannii感染加重。

Objective To explore the effects of TLR4 on Acinetobacter baumanni（ A. baumanni） infection in a rat model.Methods Healthy male SD rats were divided into normal control group,TAK-242 treated group,A. baumannii treated group,TAK-242 and A. baumannii combined treatment group. Rats of TAK-242-treated group were prepared by caudal vein injection of TAK-242（ 1 mg/kg）. A. baumannii were isolated from intensive care unit（ ICU） and the freshly grown bacteria（ 1 × 10~8 CFU/m L） were prepared. Each normal or TAK-242-treated rat was inoculated with 50 μL A. baumannii through trachea. The bronchoalveolar lavage fluid（ BALF） and blood were col ected at 72 hours after inoculation. The histopathology of lung was evaluated by HE staining. TNF-α and IL-6 were detected by ELISA. The level of phosphorylated NF-κBp65（ p-NF-κBp65） in peripheral blood mononuclear cel s（ PBMCs） was detected by Western blot analysis. Results A. baumannii were eliminated within 72 hours in normal rats,whereas bacteria continued to replicate rapidly in the lungs of TAK-242 ＆ A. baumannii treated group. The pulmonary inflammatory was more severe than the normal rats. The levels of TNF-α and IL-6 increased markedly after the infection. However,the levels of TNF-α and IL-6 in the TAK-242 combined with A. baumannii treated group were lower than those in the A. baumannii treated group. The level of p-NF-κBp65 increased significantly in the PBMCs of the normal rats 72 hours after infected with A. baumannii, but increased slightly in the TAK-242 combined with A. baumannii treated group. Conclusion TLR4/NF-κB pathway plays an important role in the process of A. baumannii infection,and TLR4 can be used as a target molecule in the treatment of A. baumannii infection.