Effect of Methyl Prednisolone on high mobility protein 1 expression in LPS-induced acute lung injury

Objective To explore the function of high mobility group box1(HMGB1) in rats′lung tissue with acute lung injury induced by lipopolysaccharide and the intervention effect of Methyly Prednisolone Injection. Methods Fifty-four male SD rats were randomly divided into three groups: control group(n=18, injected 1 m L/kg saline through tail vein after the 2 m L/kg saline was injected), ALI group(n=18, injected 1 m L/kg saline through tail vein after the 6 mg/kg lipopolysaccharide was injected), MPN group(n=18, injected 20 mg/kg Methyl Prednisolone through tail vein after the6 mg/kg lipopolsaccharide was injected). Six rats of each group were killed at the twelve hour, twenty-four hour and thirty-six hour after the lipopolsaccharide was injected. Rats′blood from carotid artery was collected for vigor analysis.The HMGB1 m RNA and its protein expression of the rats′lung was measured by immunohistochemistry and RT-PCR in different periods of each group. At the same time the pathological changes of the lung tissues, and the proportion of wet and dry(W/D) were observed. Results Little HMGB1 m RNA and its protein was expressed in the lung tissue of control group, but was increased quickly in ALI group and MPN group with peak levels being present at 24 h, which significantly higher than that in control group(P 0.05). HMGB1 m RNA and its protein in MPN group was less expressed than that in ALI group(P 0.05). The proportion of wet and dry in ALI group and MPN group increased significantly,which was higher than that in control group(P 0.01), but the proportion of wet and dry in MPN group was lower than that in ALI group in different times(P 0.05 or P 0.01). Compared with control group, it was observed different degrees of damage of lung′s pathological structure in ALI group and MPN group. There was more inflammatory cell and cell necrosis in ALI group. Conclusion It shows HMGB1 m RNA and its protein has a persistent high levels of expression on the stage of inflammation. This uncontrolled inflammation reaction contributes to the development of acute lung injury. Methyl Prednisolone, which through the effect of the expression of HMGB1 m RNA and its protein, has a protective effect to acute lung injury induced by lipopolysaccharide.