The induction effect of IL-6 in polarization process of macrophages to M2 type in vitro

LIU Miao; TANG Rong; JIANG Yi

doi:10.3969/j.issn.1002-7386.2017.08.001

Abstract：Objective To investigate the effects of IL-6 in polarization process of macrophages to M2 type,with macrophage cell line-RAW264.7 of mice being co-cultured with myeloma cell line KM3 in vitro.Methods The cells at exponential growth phase were divided into three groups: group A (KM3 cell),group B (RAW264.7 cell),group C (RAW264.7 cell +KM3 cell).After the cells were treated with ACTA (a specific inhibitor of IL-6) or rIL-6 (recombinant human IL-6),respectively,the proportion of F4/80+ CD206+ cells was detected.The expression levels of CCL22, IL-10, IL-12, TNF-α lpha were measured by RT-PCR and Western Blot, respectively.The content of IL-6 in culture supernatant was detected by ELISA.Results After RAW264.7 cells and KM3 cells were co-cultured for 24 hours, as compared with that in control group, the proportion of M2 type macrophages was significantly increased ( P <0.05),moreover after the cells were treated by ACTA, the expression of M2 type macrophages was obviously decreased ( P <0.05),however, after the cells were treated by rIL-6, the proportion of M2 macrophages was significantly increased ( P <0.05).As compared with those in group B, the expression levels of M2 macrophage related cytokines-CCL22 and IL-10 mRNA and protein were significantly up-regulated in group C ( P <0.05),but the expression levels of M1 macrophage related cytokines-IL-12, TNF-α lpha mRNA and protein were obviously down-regulated ( P <0.05).As compared with those in group A and group B, the levels of IL-6 in culture supernatant were significantly increased at 24h, 48h, 72h time points in group C ( P <0.05).When the cell counts of RAW264.7 cells or KM3 cells were changed by different concentration gradient, the expression levels of IL-6 were more easily influenced by the chages of RAW264.7 cell number.Conclusion After RAW264.7 cells are co-cultured with KM3 cells in vitro, the latter can induce the transformation of RAW264.7 cell into tumor-associated M2 macrophages, moreover, IL-6 may play an important role in the transformation process.