Differential Levels of Interleukin 6 in Maternal and Cord Sera and Placenta in Women with Pre-Eclampsia

Abstract

Background: Interleukin 6 (IL-6) is a T helper 2 cytokine with a variety of properties including pro-inflammatory characteristics. It has, therefore, been implicated in the pathophysiology of abnormal pregnancies. Objective: To investigate the association between IL-6 and pre-eclampsia by estimating the differential levels of IL-6 in maternal and cord serum and supernatant of homogenized placental tissue. Methods: 50 primigravidae with pre-eclampsia and 50 matched normotensive primigravidae served as controls. At delivery, maternal and cord blood were collected and the serum extracted. Placental blocks were homogenized and sonicated in RPMI solution and the supernatant collected. The total protein concentration was determined and IL-6 levels assayed with an ELISA technique. Results: Placental IL-6 (170 and 186 pg/mg protein) was threefold that in the maternal (64 and 58 pg/mg protein) and cord serum (63 and 72 pg/mg protein; p < 0.01). There was no significant difference in the mean IL-6 levels in maternal and cord serum or placenta in both pre-eclamptic women and normotensive controls nor in pre-eclamptic patients with babies with intra-uterine growth restriction or in pre-eclamptic patients with babies with an appropriate birth weight and in normotensive controls. Conclusion: There are no differences in the maternal and cord sera and placental levels of IL-6 in pre-eclamptic and normotensive women, indicating that IL-6 may not have a role in the pathophysiology of pre-eclampsia.

Maternal Inflammatory Response in Severe Preeclamptic and Preeclamptic Pregnancies

“…The finding for IL-6 is in line with previous reports on elevated plasma levels of IL-6 in women with preeclampsia compared with normal pregnancies [18][19][20]. In contrast, Al-Othman et al found no difference in IL-6 levels in serum between preeclampsia and normal pregnancy [21]. We found increased levels of TNF-α for women with preeclampsia compared with normal pregnancies (P < 0.003).…”

Preeclampsia-Related Inflammatory Cytokines Regulate Interleukin-6 Expression in Human Decidual Cells

“…Moreover, unlike the decidual cells, IL-6 immunostaining was localized primarily around the cell membranes in adjacent interstitial cytotrophoblasts. Previous publications observed that IL-6 expression was either unchanged 18,[32][33][34] or even reduced, 35 in preeclamptic versus control placentas, but did not specifically examine IL-6 expression in interstitial cytotrophoblasts. Therefore, this differential localization of IL-6 suggests a potential, previously undisclosed, paracrine interaction in which IL-6 is synthesized and secreted by decidual cells and then targets neighboring interstitial trophoblasts.…”

“…29 That IL-6 also interferes with endothelial cell function 30,31 suggests that preeclampsia-associated elevated plasma IL-6 levels contribute to the systemic endothelial activation and vascular damage that culminates in the maternal syndrome. Several studies examined the placenta as a source of excess circulating IL-6, but found that IL-6 expression was either unchanged 18,[32][33][34] or reduced 35 in preeclamptic versus control placentas.…”

Reduced Endothelial NO-cGMP–Mediated Vascular Relaxation and Hypertension in IL-6–Infused Pregnant Rats

“…28 -30 TNF-␣ is known to activate other cytokines such as interleukin-6 (IL-6). 31,32 Although some studies suggest that the maternal and cord sera and placental levels of IL-6 may not be different between preeclamptic and normotensive women, 33 several other studies have shown that the plasma levels of IL-6 are elevated Ϸ2-to 3-fold in women with preeclampsia. 23,25,28,34 Additionally, our preliminary observations have shown that chronic elevation of plasma IL-6 Ϸ2-fold in late pregnant rats is associated with significant increases in blood pressure.…”