Maternal second trimester serum tumor necrosis factor-alpha-soluble receptor p55 (sTNFp55) and subsequent risk of preeclampsia

Preeclampsia is characterized by diffuse vascular endothelial dysfunction. Tumor necrosis factor-alpha (TNF-alpha), which plays a key role in the cyto kine network responsible for immunoregulation, is also known to contribute to endothelial dysfunction and other metabolic disturbances noted in preecl ampsia. Results from cross-sectional studies and one longitudinal study ind icate that TNF-alpha (or its soluble receptor, sTNFp55) is increased in the peripheral circulation and amniotic fluid of women with preeclampsia as co mpared with normotensive women. Between December 1993 and August 1994, pred iagnostic sTNFp55 concentrations (a marker of excessive TNF-alpha release) were measured in 35 women with preeclampsia and 222 normotensive women to d etermine whether elevations precede the clinical manifestation of the disor der. Logistic regression procedures were used to calculate maximum likeliho od estimates of odds ratios and 95% confidence intervals. Mean second trime ster (15-22 weeks' gestation) serum sTNFp55 concentrations, measured by enz yme-linked immunosorbent assay, were 14.4% higher in preeclamptic women tha n in normotensive controls (716.6 pg/ml (standard deviation 193.6) vs. 626. 4 pg/ml (standard deviation 158.0); p = 0.003). The relative risk of preecl ampsia increased across successively higher quintiles of sTNFp55 (odds rati os were 1.0, 1.3, 2.1, and 3.7, with the lowest quintile used as the refere nt; p for trend = 0.007). After adjustment for maternal age, adiposity, and parity, the relative risk between extreme quintiles was 3.3 (95% confidenc e interval 0,8-13.4). These findings indicate that the level of TNF-alpha i n maternal circulation is increased prior to the clinical manifestation of the disorder, and they are consistent with the hypothesized role of cytokin es in mediating endothelial dysfunction and the pathogenesis of preeclampsi a. Further work is needed to identify modifiable risk factors for the exces sive synthesis and release of TNF-alpha in pregnancy, and to assess whether lowering of TNF-alpha concentrations in pregnancy alters the incidence and severity of preeclampsia.