Effect of Calcium-sensing Receptor on Human Macrophages Converting to Foam Cells With its Mechanisms

Objective: To study the expression of calcium-sensing receptor(CaR) in human macrophages and the effect of CaR on macrophages converting to foam cells with its mechanism.Methods: Human macrophages were treated with ox-LDL(100 mg/L) for 48 h to induce foam cell formation, the experimental foam cells were cultured in 3 groups for 48 h respectively. Blank control group, Foam cell + CaR agonists(Agonists) group and Foam cell + CaR inhibitor(Inhibitor) group. The CaR expression in macrophages was measured by immuno-fluorescence and Western blot analysis. The positive foam cell formation was detected by oil red O staining, the intracellular cholesterol metabolism in foam cell was observed by HPLC, the inflammatory cytokine secretion in foam cell culture supernatant was examined by ELISA, the protein expressions of CD36 and acyl-co A: cholesterol acyl-transferase(ACAT-1) in foam cells was measured by Western blot analysis.Results: Immuno-fluorescence and Western blot indicated CaR is expressed in human macrophages. Compared with Control group, Oil Red O staining and HPLC showed that Agonists group had less positive foam cell formation, decreased CE, FC, TC, and Inhibitor group had more positive foam cell formation, increased CE, FC, TC, all P0.05; ELISA presented that Agonists group had decreased TNF-α, MIF, increased anti-inflammatory cytokine IL-10, and Inhibitor group had increased TNF-α, MIF, decreased IL-10, all P0.05; Western blot analysis indicated that Agonists group had decreased protein expressions of CD36, ACAT-1 in foam cells, and Inhibitor group had increased protein expressions of CD36 and ACAT-1.Conclusion: CaR is expressed in human macrophages, the higher CaR expression may inhibit macrophages converting to foam cells.