Classically-activated macrophages elimination in tumor-conditioned medium by alternatively-activated macrophages

Abstract

Cellular interactions are critical during development, tissue fitness and epithelial tumor development. The expression levels of specific genes confer to tumoral cells a survival advantage versus the normal neighboring cells. As a consequence, cells surrounding tumors are eliminated and engulfed by macrophages. We propose a novel scenario in which circulating cells facing a tumor can reproduce these cellular interactions. In vitro cultured macrophages from murine bone marrow were used to investigate this hypothesis. M1 macrophages in tumoral medium upregulated markers of a suboptimal condition, such as Sparc and TyrRS, and undergo apoptosis. However, M2 macrophages display higher Myc expression levels and proliferate at the expense of M1. Resulting M1 apoptotic debris is engulfed by M2 in a Sparc- and TyrRS-dependent manner. These findings suggest that tumor-dependent macrophage elimination could deplete immune response against tumors. This possibility could be relevant for macrophage based anti-tumoral strategies.

Plasma Gelsolin Confers Chemoresistance in Ovarian Cancer by Resetting the Relative Abundance and Function of Macrophage Subtypes

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Reprogramming of breast tumor-associated macrophages with modulation of arginine metabolism

“…Type 2 immunogenic stimuli, such as IL4, IL13 and M-CSF, trigger M2-TAM polarization, leading to the induction of immune-suppressive Th2 responses. M2-TAMs also produce a large amount of polyamines (PAs), polycations that promote secretion of anti-inflammatory cytokines, namely, IL10 and TGFβ, to facilitate tumor growth (Chanput et al, 2013;Lolo et al, 2017;Martinez and Gordon, 2014;Zhang et al, 2016).…”