Different effects of IL-13 and IL-4 on Mφ in the presence of IL-10

Tumor-associated macrophages (TAM) represent an abundant cell population of the immune infiltrate in solid tumors and have been shown to orchestrate escape from immune surveillance. Macrophages display a very plastic phenotype which is recapitulated in vitro by classifying certain subsets according to exposure with defined, individual cytokines. The tumor-promoting M2 macrophages are polarized in vitro by differentiating human monocyte-derived macrophages with the T helper cell type 2 (Th2) response cytokines interleukin-4 and interleukin-13 or the immunosuppressive cytokine interleukin-10. Notably, only the latter macrophage subset undergoes apoptosis when treated with the colony stimulating factor 1 receptor (CSF1R) blocking antibody emactuzumab. However, under physiologic conditions the phenotype of TAM is shaped by a combination of cytokines. Hence, we evaluated if the addition of IL-10 to IL-4 or IL-13 differentiated macrophages is able to override IL-4/-13 mediated signaling and to restore susceptibility to emactuzumab. Though addition of IL-10 did not restore emactuzumab susceptibility, we surprisingly detected that only IL-4 differentiated macrophages sustained their specific marker expression while IL-10 skewed the IL-13 differentiated macrophage profile towards the IL-10 regulated phenotype. In-depth characterization by gene expression profiling revealed unique signatures of IL-4+IL-10 and IL-13+IL-10 differentiated macrophage subsets characterized by upregulation of the canonical NFκB signaling or Wnt/β-catenin signaling pathways, respectively. In silico-based analysis of a large cohort of cancer patients revealed distinct interleukin-4 or interleukin-13 overexpression patterns in a subset of patients with partial co-expression of IL-10 but almost absent IL-4/IL-13 co-expression. These patients may have less TAM depletion under therapy with CSF1R inhibitors. Five different macrophage subtypes were differentiated for six days with respect to different cytokines and transcriptomically profiled with three biological replicates derived from three different human, healthy volunteer donors