Expressions and effects of calcium-binding protein S100A8 and S100A9 in alveolar macrophages of rats

Objective To observe the expressions of calcium binding proteins S100A8 and S100A9 in alveolar macrophages (AM) of rats and their effects on the release of inflammatory mediators in AM of rats. Methods AM were isolated from rats and cultured in vitro.Different doses of S100A8 and S100A9 were treated to AM for six hours or 12 hours.Immunohistochemistry and in situ hybridization were performed to observe the expressions of S100A8/A9 protein, S100A8 mRNA and S100A9 mRNA in AM of rats.Enzyme linked immunosorbent assay was performed to detect the concentrations of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and IL-8 in supernatant of rat AM. Results (1)S100A8/A9 protein, S100A8 mRNA and S100A9 mRNA were expressed in the cytoplasm and on the cell membrane of rat AM.(2)Different doses of S100A8 and S100A9 were used to treat AM.The concentrations of TNF-α, IL-6 and IL-8 in supernatant of AM were correspondingly increasing with the increasing doses of S100A8 and S100A9.The differences between the groups were statistically significant (all P<0.05). (3)The same dose of S100A8 and S100A9 was administered to treat the rat AM for different times.The concentrations of TNF-α, IL-6 and IL-8 in supernatant of AM in the 12-hour group were significantly higher than those in the 6-hour group (all P<0.05). (4)AM were treated with the same dose of S100A8 and S100A9 for the same time.The concentrations of TNF-α and IL-8 in the supernatant of AM in the S100A8 group were higher than those in the S100A9 group (all P<0.05). The concentration of IL-6 in the supernatant of AM in the higher dose of S100A8 group was also higher than that in the same dose of S100A9 group (P<0.05). Conclusions S100A8 and S100A9 can be expressed in AM of rats.S100A8 and S100A9 stimulate the secretion of inflammatory mediators: TNF-α, IL-6 and IL-8 in the AM of rats in time-dependence and concentration-dependence.The stimulant effect of S100A8 on the secretion of TNF-α, IL-6 and IL-8 in AM of rats is significantly stronger than that of S100A9. Key words: Macrophages, alveolar; Inflammatory mediators; S100A8; S100A9