Immunological properties of human decidual macrophages – a possible role in intrauterine immunity

Abstract

Our aim was to investigate the contribution of decidual macrophages, which constitute an important immune component of the decidua in late gestation, to intrauterine defence mechanisms. Using flow cytometry we examined the ability of decidual macrophages, isolated from term decidua, to bind and phagocytose fluorescence-labelled bacterial and yeast bioparticles. We also assessed their ability to generate superoxide radicals and tumour necrosis factor-a following lipopolysaccharide challenge. Decidual macrophages bound bacterial and yeast particles in a dose-dependent manner, which subsequently led to phagocytosis. These macrophages also produced superoxide radicals and the pro-inflammatory cytokine TNF-a when challenged with bacterial lipopolysaccharides. These results suggest a role for decidual macrophages in pathogen recognition and clearance during pregnancy, and, therefore, they are likely to protect the fetus against intrauterine infections which might otherwise lead to preterm labour.

Macrophages at the Fetal–Maternal Interface Express Markers of Alternative Activation and Are Induced by M-CSF and IL-10

“…Interestingly, it was recently shown that the scavenger receptor CD163, being expressed in tissue resident Mf and involved in tissue homeostasis (56), also mediated the recognition and binding of bacteria by Mf (57). Singh et al (58) indeed reported that decidual Mf were highly capable of recognizing and phagocytosing bacteria. Further supporting this notion, M-CSF-deficient mice were more susceptible to pregnancy loss caused by Listeria monocytogenes infection (59), and IL-10-deficient mice were more susceptible to fetal loss induced by LPS (60,61) and the TLR9 ligand CpG (62), as compared with wild-type mice.…”

Tumor Necrosis Factor-α and Interleukin-1β Regulate Interleukin-8 Expression in Third Trimester Decidual Cells

“…33 Contact between bacteria or their toxic products; ie, LPS, lipid A, or lipoteichoic acid, triggers a signaling cascade in both immune and nonimmune cells that induces local proinflammation. 34 Recently, in an elegant study, LPS and GBS were each found to enhance TNF-␣ and IL-1␤ expression in full thickness amnion-choriodecidua membranes-mounted in Transwell chambers in which the upper and lower chambers are physically separated.…”

“…The choriodecidua proved more responsive than the amnion. 35 Observations that LPS targets decidual cells and decidual macrophages to secrete TNF-␣ and IL-1␤ 33,[35][36][37] constitute the initial steps of the scheme of infectioninduced PPROM depicted in Figure 8. The current study provides the next step in the proposed scheme by demonstrating that both cytokines enhance IL-8 expression in term decidual cells.…”

The Placenta in Toxicology. Part II

“…Although few studies have addressed the functional properties of decidual macrophages, they have indeed been shown to be suppressive (Mizuno, Aoki, and Kimbara 1994) and were also recently demonstrated to induce Treg cells, in a dNK cell-dependent manner (Vacca et al 2010). Nevertheless, the expression of pattern recognition receptors (CD163, CD206, and CD209) also suggests that decidual macrophages have the potential to clear infections, a function that was demonstrated by Singh et al (2005). Interestingly, M1-associated genes (e.g., IL1B, IL12RB2) appear to be hypermethylated, while M2-associated genes (e.g., A2M, IL10) are hypomethylated, indicating that the anti-inflammatory machinery of macrophages at the fetal-maternal interface is kept more accessible by epigenetic regulation (Kim et al 2012).…”