The effects of maternal inflammation on neuronal development: possible mechanisms

That maternal inflammation adversely affects fetal brain development is well established. Less well understood are the mechanisms that account for neurodevelopmental disorders arising from maternal inflammation. This review seeks to begin an examination of possible sites and mechanisms of action whereby inflammatory cytokines – produced by the mother or by the fetal brain – could impact the developing fetus. We focus first on the placenta where cytokines maintain the immunological environment that prevents maternal rejection of the fetus. Following a brief examination of placental transfer of maternal cytokines, the focus turns on embryonic microglia, early and ubiquitous residents of the developing brain. Finally, a more intense examination of interleukin-6 (IL-6) and bone morphogenetic proteins (BMPs) provides examples of glial- or maternal-derived cytokines that are known to have profound effects on developing systems and that could, if dysregulated, have undesirable consequences for brain development.