Abstract 671: Exploiting macrophage differentiation and plasticity as an immunomodulating strategy

Abstract

Abstract The infiltration of macrophages into the tumor microenvironment (TME) is a well-known characteristic of tumor progression and therapy resistance. Depending on the signals derived from TME, macrophage plasticity allows them to undergo a variety of polarization states. Two extremes of macrophage polarization are M1 and M2 phenotypes. M1 macrophages provide enhanced anti-tumor inflammatory reaction while M2 macrophages are usually associated with tumor progression due to their immune suppression, angiogenesis and neovascularization promoting capabilities. Modulating the macrophage differentiation or polarization has emerged as a therapeutic strategy to synergize or complement current treatments. At Reaction Biology we have established human macrophage assay pipelines to evaluate the novel macrophage polarization compounds in vitro. Both, monocyte cell lines like THP-1, and and freshly isolated monocytes from donor derived PBMCs, are of great value. Donor derived differences could become an issue during the screening phase compared to the use of cell lines. Yet, after the screening phase, the evaluation across several healthy donors is crucial to assess the impact of a compound on the general population. Monocytes from primary human peripheral blood mononuclear cell (PBMC) are isolated, differentiated into naïve macrophages, and polarized. Effects of compounds modulating the differentiation and polarization of macrophages are analyzed by flow cytometry. Moreover, the functional reprogramming of monocytes and macrophages can be analyzed by measuring the phagocytic or tumor cell killing capacity via flow cytometry or using high content screening equipment. In the addition, a wide range of secreted cytokine can be quantified by MSD ELISA. Our data shows that human primary monocytes grown under M1 polarizing conditions express high levels of CD86 and HLA-DR in contrast to those cultivated under M2 polarizing conditions, with high expression of CD163 and CD206. A pH-sensitive phagocytosis could be shown for M2 macrophages. Modulation of surface markers from polarized macrophages under different treatment conditions could be observed, as well as changes in their functionality, supporting the translational value to evaluate the efficacy of immunomodulating compounds in vitro. Citation Format: Carla Castro, Philipp Metzger, Cynthia Obodozie, Holger Weber. Exploiting macrophage differentiation and plasticity as an immunomodulating strategy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 671.