A Study On The Acute Lung Injury Induced By Flagellin In Rats And The Pathogenesis

240 rats were randomly divided into four groups, including group 1(inject flagellin 5 μ g/kg), group 2(inject flagellin 50 μ g/kg), group 3(inject flagellin 500 μ g/kg) and control group(inject 0.9% sodium chloride solution). We investigated blood gas, assayed the level of TNF- α and IL-1 β in serum and BALF, observed the pathological changes of lung and examined the wet/dry ratio (W/D) of lung tissue at the time point of 2h, 4h, 6h, 12h ,24h and 48h after injecting flagellin or 0.9% sodium chloride solution.(1) There were no significant changes in PaO₂, W/D, pathological change of lung tissue at different points after injecting flagellin in rats of group 1 compared to rats in control group. At 2h, 4h and 6h after injecting flagellin, TNF- a concentration in serum and BALF was higher in group 1 than in control group. (2) At 2h and 4h after injecting flagellin, IL-1 β concentration in serum and BALF was significantly higher in group 2 than in control group. (3) At 2h, 4h, 6h and 12h after injecting flagellin, TNF-α concentration in serum and BALF was much higher in group 3 than in control group. At 2h, 4h and 6h after injecting flagellin, IL-1 β concentration in serum and BALF was much higher in group 3 than in control group. (4) PaO₂ was much lower in rats of group 2 and group 3 than rats of control group, and W/D was significantly higher in rats of group 2 and group 3 than rats of control group at different points after injecting flagellin. We discovered the assembling of polynuclear leucocyte in the lung and the thickening of alveolar septa in group 2 and group 3 after injecting flagellin.The ALI model of rat induced by flagellin was successfully established. PaO₂ significantly decreased, TNF- α , IL-1 β concentrations in serum and BALF increased markedly, and W/D of lung tissue increased, too, after injecting flagellin in rats. Flagellin( 50 μ g/kg) can induce the release of TNF- α , IL-1 β and assembling of polynuclear leucocyte in the lung, which may be one of the reasons that flagellin induce ALI and related to the activation of NF-κB by the combination of flagellin and Toll-like recepter(TLR5)...