The reduction of circulating levels of IL-6 in pregnant women with preeclampsia by magnesium sulphate and nifedipine: In vitro evidence for potential mechanisms.

INTRODUCTION: Women with preeclampsia have elevated levels of inflammatory cytokines including IL-6. IL-6, which is known to activate endothelial cells and induce the production of necrotic trophoblastic debris from the placenta, may be important in the pathogenesis of preeclampsia. MgSO4 is a major therapy for the prevention of seizures in preeclampsia but it has been suggested to also have anti-inflammatory and vasodilatory properties.

METHODS: 22 pregnant women with preeclampsia and 68 normotensive controls were recruited and circulating IL-6 levels in these women were measured before MgSO4 and nifedipine treatment and after delivery. In addition, endothelial cells were treated with IL-6 or necrotic trophoblastic debris, generated from first trimester placental explants in the presence or absence of MgSO4in vitro, and cell-surface ICAM-1 was measured by ELISA. The levels of IL-6 in the culture medium were also measured. Furthermore nitric oxide synthetase activity in endothelial cells that had been treated with IL-6 was measured using l-NAME.

RESULTS: Circulating levels of IL-6 in preeclampsia were reduced significantly following administration of MgSO4. In vitro, MgSO4 reversed the activation of endothelial cells induced by IL-6 but not by necrotic trophoblastic debris. The effect of MgSO4 in reversing the IL-6 induced activation of endothelial cells was not dependent upon nitric oxide synthetase. Treating placental explants with MgSO4 prevented the production of necrotic trophoblastic debris induced by IL-6.

DISCUSSION: we demonstrated that IL-6 levels drop following treatment with MgSO4 and nifedipine in vivo, and have identified several mechanisms by which this positive effect on IL-6 may occur in vitro.