Effect of bone mesenchymal stem cells on pathological changes and expression of interleukin-6 and -8 in the lung tissue in acute lung injury model of juvenile mice

Abstract

Objective To detect the changes in expression levels of interleukin(IL)-6 and IL-8 in the lungs of juvenile mice with acute lung injury(ALI) induced by aerosol inhalation of lipopolysaccharide(LPS). To observe the degree of reparation of lung damage after intervening with exogenous bone mesenchymal stem cells (BMSCs). Methods Seventy-two SPF grade male SD juvenile mice were randomly divided into 3 groups: control group, model group, and treatment group.Each group was randomly divided into 4 subgroups at 6 h, 12 h, 24 h, and 48 h after the building of model(6 mice per group). The model group were inhaled by LPS (5 mg/ml, 2 ml, 30 min) to prepare the ALI model.The control group were inhaled by the same volume of physiological saline (2ml, 30min) during the same period.As for the treatment group, BMSCs was injected into the tail vein one hour after inhalation of LPS (1×106/ml, 0.1 ml/kg). Meanwhile, the model group and the control group were injected intravenously with equal volume (0.1 ml/kg) of Dulbecco′s modified eagle medium.The ratioes of wet weight and dry weight of the lungs(W/D)were detected.The pathological changes in lungs were observed by optical microscope.The numbers of cells in the bronchoalveolar lavage fluid (BALF) at each time point were counted under a microscope and the protein concentrations were measured by bicinchoninic acid method.The changes of IL-6 and IL-8 protein content in lung tissue fluid were measured by applying Western Blot method. Results Compared with the control group, the ratioes of W/D in the lung of mice at each time piont of the model group were significantly higher; the W/D ratioes of the lungs in the treatment group were significantly lower than those of model group(P<0.05). In accordance with histopathological observations, the lung tissue of the juvenile mice in the model group showed alveolar diffuse congestion, hemorrhage, pulmonary edema, obvious inflammatory cell infiltration in the alveolar cavity and blood vessel wall, marked thickening of the alveolar wall and other obvious lung injury changes; while the lung tissue injury of treatment group was significantly less than that of the model group.Compared with the control group, the numbers of cells in the BALF of the model group were significantly higher than those of the control group at each time point; the numbers of BALF cells in the treatment group were significantly lower than those of the model group(P<0.05). Western Blot test showed that expressions of IL-6 and IL-8 protein in the lung tissue of the model group were significantly higher than those of the control group at each time point, and expressions of IL-6 and IL-8 protein in the treatment group were significantly lower than those in the model group(P<0.05). Conclusion The protein expressions of IL-6 and IL-8 are increased in the lung tissues in the juvenile mice model of ALI induced by aerosol inhalation of LPS.BMSCs can decrease the expression of IL-6 and IL-8, and alleviate the degree of inflammatory injury at 6 h, 12 h, 24 h, 48 h time points after the ALI juvenile mice model being induced by aerosol inhalation of LPS. Key words: Bone mesenchymal stem cells; Lipopolysaccharide; Acute lung injury; Interleukin 6; Interleukin 8