BALB/c mice divided into three groups: Normal, Control and ES-treated. Tumor-bearing mice were treated with ES-transduced cells or control cells over ten days. At the end of the study, plasma was collected, and pulmonary macrophages were isolated and used for FACS or RT-PCR. ELISA tests were used to analyze plasma and cell culture supernatant cytokines.
ES treatment significantly reduced the levels of anti-inflammatory and pro-angiogenic cytokines, including IL4, IL-10, IL-13 and VEGF. Gene expression of M2 markers, such as IL-10, Arg-1, VEGF and YM-1, declined significantly. Flow cytometry showed a reduction in the number of M2 F4/80 + CD36 + CD206 + CD209+ macrophages and in IL-10 secretion by these cells. Reduced levels of IL-10 were also found in the culture supernatants of the ES-treated group.
Our research corroborates previous observations that ES has an important anti-tumoral role. However, aside from promoting interferon-ɤ secretion and an effective T cell response, we show here that this switch is extended to TAMs, complicating the maintenance of pro-tumorigenic M2 macrophages and thus favoring tumor elimination.