The Expression And Role Of Toll-like Receptor 5 In The Lung Tissues Of Rats With Acute Lung Injury Induced By Flagellin

Acute lung injury(ALI) is a kind of acute respiratory failure clinically characterized as the developing dyspnea. It is induced by various dangerous factors inside or outside pulmonary system with complicated pathogenesis. Until now there is still no effective therapeutic principles and mortality reaches as high as 50-70%. Toll-like receptor 5(TLR5) is a member of Toll-like receptors(TLRs)-a important family of trans-membrane receptors in immune system and it is the specific receptor of flagellin. Flagellin is the main protein of flagellar in gram-negative bacterin. It is now argued that flagellin is a strong inflammatory activator which can induce local and system inflammation via TLR5. It is also a potent mediator of sepsis-induced ALI. But the channel and mechanism of flagellin inducing ALI are not reported. This study made rat model of ALI by injecting flagellin, subsequently observed the expression of TLR5 and the activation of NF-κB to discuss the potential role and signal transduction pathway in the pathogenesis of flagellin-induced ALI.Methods: The flagellin from Escherichia coli through Acid-splitting was purified by applying AKTA Explorer purified system. Rat model of ALI was established by injecting flagellin. SD rats were randomly divided into control group, flagellin-hurted 1 group and flagellin-hurted 2 group. At 0,0.5,1,2,4 and 6h after hurted, the expression of TLR5 mRNA and NF-κB activity in the lung tissues of rats were detected by in situ hybridization(ISH) and electrophoretic mobility shift assay(EMSA) respectively. The partial pressure of oxygen in artery(PaO2) and the wet/dry ratio(W/D) of lung tissues were monitored and the pathological change of lung was observed at the same time.Results: (1) Molecular quantity of the purified flagellin was about 65KD by SDS-PAGE electrophoresis. (2) Western blotting analysis showed the purified flagellin strip was located at 65KD location. (3) The flagellin-induced ALI model of rat was successfully established by injecting flagellin. In the processes,①PaO2 of flagellin-hurted 1 and 2...