RNA-seq analysis identifies regulators of macrophage reprogramming from M2 to M1-like phenotype

We analyzed expression profiles of thioglyolate elicted peritoneal exudate cells (peritoneal macrophages). Peritoneal macrophages were polarized into M1 and M2 macrophages by activation with IFNgamma+ LPS and Il4, respectively. We predicted a gene-regulatory network, which consists of four transcription factors (E2f1,Myc, Stat6, Pparg) regulating metabolic genes, M1 and M2-associated genes. The predicted regulators were all active in M2 macrophages. We hypothesized that these transcription factors are essential regulators to maintain M2 phenotype. To further validate our findings, we treated M2-polarized macrophages with siRNA-pools targeting E2f1, Myc, Stat6 and Pparg. In this study, we observed a switch towards an M1-like phenotype after transfection of siRNA-pools. In addition, Inflammatory pathways were upreguated while fatty acid metabolism was down regulated. Overall design: RNA was extracted from murine peritoneal macrophages, untreated or treated with LPS+IFNgamma (M1 macrophage) and Il-4 (M2 macrophage). Furthermore, M2-polarized peritoneal macrophages were transfected with siRNA-pools targeting E2f1, Myc, Stat6, Pparg, negative siRNA-pool and mock. Untreated and M1-polarized peritoneal macrophages were treated with mock. The experiments were performed in tripicates.