Elevated IL-6 in Pre-Eclampsia Increases Neurite Growth and Mitochondrial Respiration in an in vitro Model of Neuronal Development

Pre-eclampsia (PE) is a common and serious hypertensive disorder of pregnancy, which affects 3-5% of first-time pregnancies and is a leading cause of maternal and neonatal morbidity and mortality. Prenatal exposure to PE is associated with an increased risk of neurodevelopmental disorders in affected offspring, although the cellular and molecular basis of this are largely unknown. In this study we examined the effects of exposure to maternal serum from women with PE or a healthy uncomplicated pregnancy on the survival, neurite growth and mitochondrial function of SH-SY5Y cells. We report that cells exposed to PE serum exhibited increased neurite growth and mitochondrial respiration, two important neurodevelopmental parameters, compared to those treated with control serum. Levels of the pleiotropic cytokine IL-6 were significantly elevated in the PE sera, and cells exposed to PE serum displayed increased phospho-STAT3 levels which is a key intracellular mediator of IL-6 signalling. Finally, we show that treating these cells with IL-6 alone is sufficient to induce a similar neurite growth and respiratory phenotype to PE serum-exposed cells. This suggests that elevated IL-6 seen in maternal serum in PE may be responsible at least in part for its inducing increased neurite growth and mitochondrial respiration in SH-SY5Y cells. Overall, this study demonstrates that there are circulating factors in the serum of women with pre-eclampsia that affect neuronal development and oxygen consumption differently to that of a healthy uncomplicated pregnancy, and that immune dysregulation via elevated IL-6 may be important in mediating these effects.