Effects of lipopolysaccharide and dexamethasone on the biological characteristics of rats alveolar macrophage

Alveolar macrophages(AMs) play a central role in lung inflammation and acute lung injury, but also participate actively in the resolution of inflammation after activation. Macrophages (Mφ) represent a dynamic cell population that develops and operates within a changing microenvironment. However, it is not known how the biological characteristic of AM stimulates by lipopolysaccharide (LPS) or desamethasone (DEX) and the relationship between AM and inflammation. In this study, we first observed the morphology in AM isolated from rats differed according to the molecule used. We found that LPS-stimulated AM induced anti-apoptosis and had pro-inflammatory effects; dexamethasone induced AM apoptosis and had anti-inflammatory effects. These results suggested that a balance in macrophage activation, being either stimulated by LPS) or DEX, would be important to participate sequentially in both the induction and the resolution of inflammation. These findings may provide new insight into the lung inflammatory process as well as new fields of investigation for immunotherapy in the fields of acute lung injury/ acute respiratory distress syndrome.