Immunoregulatory effects of emodin on macrophages during Brucella infection / 中华微生物学和免疫学杂志

ABSTRACT

Objective To study the immunoregulatory effects of emodin on macrophages during Brucella infection and to provide theoretical and experimental basis for developing new drugs to treat brucello-sis. Methods Bone marrow cells were isolated from BALB/c mice and cultured with MG-CSF to induce differentiation. Flow cytometry was used to detect the differentiation of bone marrow cells into macrophages (MΦ) by using FITC-labeled mouse anti-F4/80 antibody and PE-labeled anti-CD11b antibody. MTT meth-od was used to detect the influences of various concentrations of emodin on the survival rate of MΦ. Doxy-cycline was used as the control to compare half maximal inhibitory concentrations (IC50) of the two drugs. MΦ were cultured with Brucella at a ratio of 100 1 for 4 h. MΦ and Brucella were further cultured for 1, 6,12,24 and 48 h after adding emodin. Effects of emodin on the survival of MΦ were analyzed by colony counting method. ELISA was performed to detect the levels of TNF-α, IL-6 and IFN-γ in culture superna-tants. Results On day 8 of culturing,91.28% of bone marrow cells differentiated into macrophages. The IC50of emodin(608.4 μg/ml) was significantly higher than that of doxycycline(225.5 μg/ml). The logC-FU values of emodin stimulation groups (6,12,24 and 48 h) were significantly lower than those of blank control groups. Among all emodin stimulation groups, the 24 h group had the lowest logCFU value, which was also lower than that of the doxycycline treatment group. The levels of TNF-α,IL-6 and IFN-γ in 6,12 and 24 h emodin stimulations group increased significantly as compared with those of the corresponding con-trol groups. The levels of TNF-α, IL-6 and IFN-γ peaked at 24 h of culturing Brucella-infected MΦ with emodin. No significant difference in IFN-γ level was found between the 12 and 24 h emodin stimulation groups [(74.233 ±4.416) pg/ml vs (78.328 ±8.932) pg/ml]. Conclusion Emodin may enhance the ability of macrophages to kill Brucella through promoting the expression of TNF-α,IL-6 and IFN-γ.