Glucocorticoids induce differentiation of monocytes towards macrophages that share functional and phenotypical aspects with erythroblastic island macrophages

Abstract

The classical central macrophage found in erythroblastic islands plays an important role in erythroblast differentiation, proliferation and enucleation in the bone marrow. Convenient human in vitro models to facilitate the study of erythroid-macrophage interactions are desired. Recently, we demonstrated that cultured monocytes/macrophages enhance in vitro erythropoiesis by supporting hematopoietic stem and progenitor cell survival. Herein, we describe that these specific macrophages also support erythropoiesis. Human monocytes cultured in serum-free media supplemented with stem cell factor, erythropoietin, lipids and dexamethasone differentiate towards macrophages expressing CD16, CD163, CD169, CD206, CXCR4 and the phagocytic TAM-receptor family. Phenotypically, they resemble both human bone marrow and fetal liver resident macrophages. This differentiation is dependent on glucocorticoid receptor activation. Proteomic studies confirm that glucocorticoid receptor activation differentiates monocytes to anti-inflammatory tissue macrophages with a M2 phenotype, termed GC-macrophages. Proteins involved in migration, tissue residence and signal transduction/receptor activity are upregulated whilst lysosome and hydrolase activity GO-categories are downregulated. Functionally, we demonstrate that GC-macrophages are highly mobile and can interact to form clusters with erythroid cells of all differentiation stages and phagocytose the expelled nuclei, recapitulating aspects of erythroblastic islands. In conclusion, glucocorticoid-directed monocyte differentiation to macrophages represents a convenient model system to study erythroid-macrophage interactions.

Effects of tumor grade and dexamethasone on myeloid cells in patients with glioma

“…16 Here we confirm these findings and show that HLA-DR/DP/DQ loss in Dex-treated patients is independent of disease grade (Figure 6A). Consistent with the fact that the gene for CD163 is glucocorticoid-regulated, 18,22,29 we found that CD163 was expressed on a higher percentage of circulating CD14+ monocytes in Dex-treated low and high-grade glioma patients (Figure 6B). In contrast, we see no change in the frequency of the commonly used MDSC marker CD33 (Figure 6C) or the T cell suppressive marker PD-L1 (Figure 6D), indicating that Dex doesn’t universally suppress surface protein expression, but may have specific targets.…”

“…20-22 A recent study evaluating grades II-IV astrocytomas demonstrates that CD163 mRNA expression increases with increasing grade of astrocytoma, and that CD163+ cells produce IL-10 in the GBM tumor microenvironment. 23 Furthermore, this report suggests that CD163 could be used as a prognostic indicator for grade III astroctyomas.…”

“…14 Although glucocorticoid signaling increases expression of CD163 on myeloid cells, 22,29 the effects on accumulation of CD163+ cells in tumor tissue are less well understood. Recent work suggests that variation in the expression of macrophage immune modulatory proteins is more critical to disease progression than macrophage accumulation within the tumor.…”

Large-scalein-vitroproduction of red blood cells from human peripheral blood mononuclear cells

“…In contrast, EM supplemented with cHSA, dHSA, or rHSA showed a significantly increased erythroid expansion potential with limited spontaneous differentiation and a complete absence of non-erythroid cells (Figure 1A and Figure S1A). Of note, PBMC contain primarily T-cells, myeloid cells and B-cells and only on average 0.16% CD34 + HSPC that are capable of differentiating into erythroid cells 17,19 . Therefore, expansion curves using PBMC as a starting material show a drop in expansion between day 0 and day 5, caused by a loss of these non-proliferating immune effector cells 17,18 .…”

“…We have previously shown that enucleated cRBC can be generated starting from adult peripheral blood mononuclear cells (PBMC), a better accessible source than cord blood CD34 + cells and allows adult autologous cRBC 17 . Importantly, the erythroid yield from PBMC is 10-15 fold increased compared to CD34 + cells isolated from a similar amount of PBMC, due to support from CD14 + cells present in PBMC 17–19 .…”