Effects of dexamethasone on the expressions of IL-1β and TNF-α in bronchoalveolar lavage fluid from rats with acute lung injury induced by lipopolysaccharide

Objective To explore the effects of dexamethasone on the expression of IL-1β and TNF-α in bronchoalveolar lavage fluid( BALF) from acute lung injury( ALI) induced by lipopolysaccharide in rats. Methods Forty-eight male SD rats were randomly divided into 3 groups: control group( n = 16), ALI group( n = 16) and dexamethasone intervention group( n = 16). The rats in ALI group were treated with lipopolysaccharide( LPS) by intratracheal instillation to induce acute lung injury,followed by injection of 1 mL normal saline,the rats in the dexamethasone intervention group were first treated with LPS and then with dexamethasone 3 mg / kg( dissolved in 1 ml NS) and the rats in control group were treated with normal saline. The animals in 3 groups were killed at 1st,2nd,4th and 8th hour after operation and then blood gas was monitored and the lung tissue wet / dry weight( W / D) was measured. The histopathology of lung injury was observed by light microscope,and the expressions of interleukin-1( IL-1β) and tumor necrosis factor-α( TNF-α) proteins in lung tissues were measured by enzyme linked immunosorbent assay( ELISA). Results Arterial partial pressure of oxygen( PaO 2) in ALI group and dexamethasone intervention group decreased rapidly after the rats were treated with LPS by intratracheal instillation. PaO 2 in ALI group was lower than that in dexamethasone intervention group( P 0. 05). The W / D value of ALI group and dexamethasone intervention group was significantly increased( P 0. 05),and the treatment group was lower than that of the ALI group( P 0. 05). The severity of lung injury,including lung swelling,neutrophil cells infiltration and hemorrhage,the treatment group showed milder than ALI group. The expressions of IL-1β and TNF-α in BALF from the ALI group rapidly increased after intratracheal injection and reached the peak at 4th hour. The expressions of IL-1β and TNF-α in the ALI group were higher than those in the dexamethasone intervention group at all time points( P 0. 05). No significant changes were observed in control group at various time points. Conclusion Dexamethasone can inhibit the expressions of IL-1β and TNF-α in injured lung tissue,improve oxygenation in respiration and relieve the damage of LPS-induced ALI in rats.