Impact and mechanism of NEMO binding domain peptide on pulmonary inflammation and apoptosis of lung tissues in mice with acute respiratory distress syndrome / 中华危重病急救医学

ABSTRACT

Objective:To investigate the effect of NEMO binding domain peptide (NBDP) on lung inflammation and apoptosis in mice with acute respiratory distress syndrome (ARDS) and its mechanism.Methods:Thirty-six male BALB/c mice were divided into normal saline (NS) control group, ARDS model group, NBDP negative control group and 6, 12 and 18 μg NBDP pretreatment group by random number table method, with 6 mice in each group. ARDS mouse model was reproduced by aerosol inhalation lipopolysaccharide (LPS) 50 μL. An equivalent among of NS was inhaled in NS control group. The mice in NBDP negative control group were inhaled the materials similar to the non-functional NBDP 30 minutes before the aerosol inhalation LPS; 6, 12 and 18 μg of NBDP 50 μL were respectively inhaled in NBDP pretreatment groups. After inhalation of LPS for 6 hours, mice were sacrificed to get lung tissue and observe the degree of pathological injury and edema. Western blotting was used to detect the phosphorylation of nuclear factor-κB (NF-κB) pathway related proteins [NF-κB inhibitor (IκB) kinaseα/β(IKKα/β), IκBα and NF-κB p65; p-IKKα/β, p-IκBα, p-p65] and the expression of caspase-3 in lung tissue. The bronchoalveolar lavage fluid (BALF) was collected and the levels of inflammatory markers such as myeloperoxidase (MPO), interleukins (IL-1β, IL-8), and tumor necrosis factor-α (TNF-α) were detected by enzyme linked immunosorbent assay (ELISA).Results:ARDS model group had severe edema and hemorrhage, alveolar structure destruction, pulmonary hemorrhage and hyaline membrane formation etc. under light microscope, consistent with the pathological characteristics of ARDS lung tissue, suggesting that the ARDS model was successfully reproduced. ELISA showed that MPO, IL-1β, IL-8 and TNF-α levels of BALF in ARDS model group were obviously higher than those in NS control group. There were no significant differences in the above inflammatory indicators between NBDP negative control group and ARDS model group. The levels of MPO, IL-1β, IL-8 and TNF-α in NBDP pretreatment groups were significantly lower than those in ARDS model group in a dose-dependent manner, especially in 18 μg NBDP, the differences were statistically significant as compared with ARDS model group [MPO (ng/L) 393.32±19.35 vs. 985.87±101.50, IL-1β (ng/L) 43.05±5.11 vs. 97.68±10.88, IL-8 (ng/L) 84.64±2.32 vs. 204.00±17.37, TNF-α (ng/L) 229.13±17.03 vs. 546.73±62.72, all P < 0.05]. Western blotting showed that p-IKKα/β, p-IκBα, p-p65 and caspase-3 protein expressions in ARDS model group were significantly higher than those in NS control group. There was no significant difference in above NF-κB pathway and apoptosis-related protein expression between the NBDP negative control group and ARDS model group. The p-IKKα/β, p-IκBα, p-p65 and caspase-3 protein expression in NBDP pretreatment groups were significantly lower than those in ARDS model group in a dose-dependent manner, especially in 18 μg NBDP, the differences were statistically significant as compared with ARDS model group [p-IKKα/β protein (p-IKKα/β/β-actin) 0.15±0.02 vs. 0.42±0.04, p-IκBα protein (p-IκBα/β-actin) 0.10±0.01 vs. 0.93±0.30, p-p65 protein (p-p65/β-actin) 0.22±0.05 vs. 1.37±0.21, all P < 0.05]. Conclusion:NBDP can inhibit inflammatory response and apoptosis in ARDS lung tissue in a dose-dependent manner, and its mechanism is associated with interference NF-κB signaling pathway transduction.