Macrophage Polarization Modulates FcγR- and CD13-Mediated Phagocytosis and Reactive Oxygen Species Production, Independently of Receptor Membrane Expression

Abstract

In response to microenvironmental cues, macrophages undergo a profound phenotypic transformation acquiring distinct activation phenotypes ranging from pro-inflammatory (M1) to anti-inflammatory (M2). To study how activation phenotype influences phagocytosis and production of reactive oxygen species (ROS) mediated by receptors for IgG antibodies (Fcγ receptors) and by CD13, human monocyte-derived macrophages were polarized to distinct phenotypes using IFN-γ (Mϕ-IFN-γ), IL-4 (Mϕ-IL-4), or IL-10 (Mϕ-IL-10). Phenotypically, Mϕ-IFN-γ were characterized as CD14+CD80+CD86+ cells, Mϕ-IL-4 as CD209highCD206+CD11b+CD14low, and Mϕ-IL-10 as CD16+CD163+ cells. Compared to non-polarized macrophages, FcγRI expression increased in Mϕ-IFN-γ and Mϕ-IL-10 and FcγRIII expression increased in Mϕ-IL-10. None of the polarizing cytokines modified FcγRII or CD13 expression. Functionally, we found that cytokine-mediated activation significantly and distinctively affected FcγR- and CD13-mediated phagocytosis and ROS generation. Compared to non-polarized macrophages, FcγRI-, FcγRII-, and CD13-mediated phagocytosis was significantly increased in Mϕ-IL-10 and decreased in Mϕ-IFN-γ, although both cytokines significantly upregulated FcγRI expression. IL-10 also increased phagocytosis of Escherichia coli, showing that the effect of IL-10 on macrophage phagocytosis is not specific for a particular receptor. Interestingly, Mϕ-IL-4, which showed poor FcγR- and CD13-mediated phagocytosis, showed very high phagocytosis of E. coli and zymosan. Coupled with phagocytosis, macrophages produce ROS that contribute to microbial killing. As expected, Mϕ-IFN-γ showed significant production of ROS after FcγRI-, FcγRII-, or CD13-mediated phagocytosis. Unexpectedly, we found that Mϕ-IL-10 can also produce ROS after simultaneous stimulation through several phagocytic receptors, as coaggregation of FcγRI/FcγRII/CD13 induced a belated but significant ROS production. Together, these results demonstrate that activation of macrophages by each cytokine distinctly modulates expression of phagocytic receptors, FcγR- and CD13-mediated phagocytosis, and ROS production.

A Foreign Body Response‐on‐a‐Chip Platform

“…Similarly, the M1/M2 differentiation of the human primary monocytes was also analyzed and it was found that, for the specific donor shown in Figure S2 in the Supporting Information, in either absence or presence of Ti microbeads in the bottom tissue chamber of the bioreactor, the primary monocytes expressed both M1‐ and M2‐associated surface markers approximately in equal ratio, with most cells exhibiting double stains. The differences of M1/M2 differentiation in response to the Ti microbeads between the human primary monocytes and the THP‐1 monocytes could possibly be explained by the fact that, in the cell line, the expression of each marker is induced in response to different environmental stimuli, while in the primary cells, these markers are constitutively expressed and the intensities of expressions change when responding to different stimuli . Indeed, when we examined the FBR of monocytes derived from three different donors, it was found that, interestingly, different individuals exhibited varying degrees of immune responses to the same Ti microbeads (Figure d).…”

Macrophages: Their role, activation and polarization in pulmonary diseases

“…Usually, it was presumed that changes in expression levels of these receptors determines the extent of phagocytosis. However, it has now been confirmed that macrophage polarization state determines the extent of phagocytosis and ROS production rather than the changes in receptor expression (Mendoza-Coronel and Ortega, 2017). Further, pattern recognition leads to release of cytokines involved in initial response.…”

Children with oligoarticular Juvenile Idiopathic Arthritis have skewed synovial monocyte polarization pattern with functional impairment – a distinct inflammatory pattern for oligoarticular juvenile arthritis

“…M1(IFNγ) monocytes have an increased surface expression of CD40 and CD80, and produce pro-in ammatory cytokines, such as IL-1β and TNF (7,9). These cells have also been shown to have decreased Fc-mediated phagocytosis (10). In contrast, M2(IL-4) monocytes express high levels of CD206, TGM2 and PPARγ (11).…”