Objective: To investigate whether the treatment of oxidized low density lipoprotein (ox-LDL) could reduce ceruloplasmin (Cp) expression and then, influence iron efflux in macrophages.
Methods: RAW264.7 cells were treated by lipopolysaccharides (LPS), ferric ammonium citrate (FAC), deferoxamine (DFO) and ox-LDL. Biochemical analysis and histological assays were performed to detect the iron-related protein including ferritin (Ft), transferrin receptor (TfR), ferroportin 1 (FPN1) and Cp. And the cholesterol enzyme was used to evaluate cells' cholesterol content.
Results: Western blot showed that protein level of FPN1, Ft increased and protein level of TfR decreased after the treatment of FAC. The mRNA level (t=-5.995, P=0.019) and the oxidative activity (t=-9.875, P=0.001) of Cp increased significantly after the treatment of LPS+FAC compared to control group. The treatment of ox-LDL could reduce protein level of Cp compared to LPS treated cells and no different protein levels of Ft and Ferroportin was found after the treatment of ox-LDL as shown by Western blot. The protein level, ferroxidase activities (t=6.663, P=0.003) and mRNA levels (t=8.948, P=0.001) of Cp in LPS+ox-LDL+FAC group were reduced than LPS+FAC group. The protein levels of Ft and FPN1 in LPS+ox-LDL+FAC group was significant higher than LPS+FAC group as shown by Western blot.
Conclusion: The findings suggest that the expression of Cp is reduced in foam cells and leads to obstructed iron efflux in iron overloaded foam cells.