More recently, we have shown that IL1B induces an array of chemokines that promote monocyte/macrophage chemotaxis. Thus, TNF and IL1B may induce multiple macrophage-monocyte/macro-phage-recruiting chemokines that overcome the inhibitory effects of constitutively expressed MIF.
The effects of TNF and IL1B on CSF1 levels shown in the current study delineate a novel mechanism by which inflammatory cytokines can affect pregnancy.
Several lines of evidence indicate that CSF1 plays important roles in regulating placental function and growth. In the mouse, CSF1 induces placental DNA synthesis in vitro. In humans, both CSF1 and the CSF1 receptor are highly expressed in the placenta, whereas CSF1 stimulates human trophoblast hCG production in vitro. A role for CSF1 in placental and fetal growth is further supported by the observation that CSF1 levels in the amniotic fluid are decreased in patients with intrauterine growth retardation. Therefore during pregnancy, IL1B and TNF may indirectly regulate placental function and growth through the induction of decidual CSF1 production.