Baicalein attenuates acute lung injury induced by intestinal ischemia/reperfusion via inhibition of nuclear factor-κ B pathway in mice / 中华危重病急救医学

ABSTRACT

Objective To investigate the effects of baicalein (Bai) on acute lung injury (ALI) induced by intestinal ischemia/reperfusion (I/R) and its mechanism in mice.Methods Twenty-four male C57BL/6J mice were divided into three groups by random number tablenamely sham group,I/R group and Bai+I/R group,with 8 mice in each group.Intestinal I/R induced lung injury model was reproduced by clamping superior mesenteric artery for 90 minutes,followed by reperfusion.Bai (100 mg/kg) was intraperitoneally injected 1 hour before ischemic challenge in the Bai+I/Rgroup.The mice in sham group underwent the similar procedure with I/R group but without vascular occlusion.All mice were sacrificed at 4 hours of reperfusion,and blood was collected from inferior vena cava and lung tissues were harvested.Lung tissues were stained with hematoxylin-eosin (HE),and histological changes were examined under light microscope for pathological score.Lung wet/dry (W/D) ratio was calculated.Lung cell apoptosis was determined by TdT-mediated dUTP nick end labeling (TUNEL) technique.Serum levels of tumor necrosis factor-α (TNF-α) and interleukin-6(IL-6) were determined by enzyme-linked immunosorbent assay (ELISA).The mRNA expressions of TNF-α and IL-6 in lung tissues were determined by real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR).The protein expression levels of cytoplasmic inhibitory factor-α of nuclear factor-κB (IκB-α) and nucleus NF-κB were determined by Western Blot.Results Under light microscope,a normal lung tissue structure was shown in the sham group and no evidence of obvious lung injury was found.In the I/R group,the alveolar structure was seriously damaged.The alveolar wall was widened and there was significant interstitial edema and leukocytes infiltration.In the Bai+I/R group,pathological damage was significantly decreased as indicated by reduced lung tissue edema and leukocytes infiltration.Compared with the sham group,the lung pathological scores,W/D ratio and cellular apoptosis in the I/R group were significantly increased.Bothserum TNF-α and IL-6 contents and lung TNF-α and IL-6 mRNA expressions were significantly increased.Furthermore,I/R significantly resulted in a decrease of IκB-α in the cytoplasm and an increase of NF-κB in the nucleus.Notably,Bai treatment significantly attenuated ALI induced by intestinal I/R injury.Compared with the I/R group,the lung pathological scores and W/D ratio in the Bai+I/R group were significantly decreased (lung pathological score4.59±1.17 vs.6.27±1.34,W/D ratio3.79±0.28 vs.4.32±0.57),cellular apoptosis was significantly decreased [(4.85 ± 2.47)％ vs.(8.15 ± 2.33)％],both serum TNF-α and IL-6 contents and lung TNF-α and IL-6 mRNA expressions were significantly decreased [serum TNF-α (pg/L)124.18±30.49 vs.167.72 ± 38.65,IL-6 (ng/L)1.65 ± 0.69 vs.2.43 ± 0.57;lung TNF-α mRNA (2-△△Ct4.75 ± 2.38 vs.7.69 ± 2.32,IL-6 mRNA (2-△△ Ct)16.45 ±4.39 vs.27.69 ± 6.82],additionally,Bai pretreatment significantly increased cytoplasmic IκB-α protein expression (gray value0.47 ± 0.11 vs.0.27 ± 0.09),while decreased nuclear NF-κB protein expression (gray value0.57 ± 0.13 vs.1.07 ± 0.14,all P ＜ 0.05).Conclusion Bai could attenuate intestinal I/R injury induced ALI via the inhibition of inflammation and apoptosis.