ObjectiveTo explore the anti-inflammatory mechanism of the proteasome inhibitor MG-132 on rats with acute lung injury (ALI). Methods54 male SD rats were randomly divided into a control group,an ALI group,and a MG-132 group. LPS (5 mg/kg) was injected via tail vein in the ALI group and the MG-132 grouop,while the normal saline was given instead in the control group. MG-132 (10 mg/kg) was injected intraperitoneally at 30 min before LPS administration in the MG-132 group. Six rats in each group were sacrificed at 2,4,and 8h after normal saline or LPS administration. Then the following parameters were observed including pathology changes of lung tissue,wet to dry weight ratio of lung tissue (W/D),the levels of ICAM-1 and TNF-α in bronchoalveolar lavage fluid (BALF) by ELISA,and the protein level of nuclear factor-kappa B P65 (NF-κB P65) in lung tissue by Western blot. ResultsThe pathological observation showed the typical ALI performance,as obvious pulmonary tissue congestion,edema,a large number of inflammatory cells infiltration in the ALI group. These inflammatory performance were obviously alleviated in the MG-132 group. Compared with the control group,the W/D,the levels of ICAM-1 and TNF-α in BALF,and the expression of the protein NF-κB P65 in lung tissue at 2,4 and 6h in the ALI group were significantly increased(P<0.05). Above parameters were significantly decreased in the MG-132 group compared with the ALI group. The expression of the protein NF-κB P65 was significantly positively related with the levels of ICAM-1 and TNF-α in BALF(P<0.01). ConclusionMG-132 can suppress inflammatory response in endotoxin-induced acute lung injury,which may be related to inhibition of NF-κB activation.