Decidual macrophages bind to and phagocytose bacteria, regulate placental apoptosis, and are involved in clearance of placental apoptotic cells. Conversely, macrophages are also a source of factors that may lead to adverse effects on the conceptus. Tissue macrophages synthesize and secrete the Th1 cytokines interferon-gamma and TNF, as well as the effector molecules nitric oxide and prostaglandins. Consequently, mechanisms that ensure the regulation of macrophage numbers at the fetal-maternal interface are likely to play crucial roles in the establishment and maintenance of pregnancy.
CSF1 and MIF are known to exert opposite effects on macrophage chemotaxis, with CSF1 promoting and MIF inhibiting migration. Moreover, MIF specifically inhibits MCP-1-driven monocyte and macrophage migration. The results of the current study support the involvement of these antagonistic cytokines in controlling the decidual macrophage population. They suggest that variability in the magnitude of CSF1 release from TNF- and IL1B-stimulated decidual cells can have physiologic or pathologic consequences.