Placental tumor necrosis factor-α protein expression during normal human gestation

Objective: Placental tumor necrosis factor-α (TNF-α) is a cell signaling protein. During pregnancy, TNF-α induces synthesis of matrix metalloproteinases (MMPs) which allows cytotrophoblasts to reach the spiral arteries deeper within the uterine decidua. TNF-α also augments apoptosis of vascular smooth muscle cells surrounding these arteries. In this study, chorionic villi TNF-α protein expression throughout normal human gestation were investigated. Methods: Placental chorionic villi tissues obtained from elective surgical terminations of pregnancy and from uncomplicated term births were assayed using EIA kits (Cayman Chemicals, Ann Arbor, MI, Item # 589201). Results: The median, 25th percentile and 75th percentile values in the first (N = 99), second (N = 58) and third trimester (N = 42) were: 36.46, 27.25, 45.90 pg/100 mg tissue; 55.43, 40.09, 110.88 pg/100 mg tissue; and 16.63, 9.32, 31.92 pg/100 mg tissue, respectively. Conclusions: Variations in placental TNF-α protein expression noted at different trimesters may suggest gestational age specific roles for the cytokine. The increase in TNF-α protein expression observed in the second trimester may be involved in upregulating synthesis of MMP and in augmenting apoptosis of vascular smooth muscle cells of the spiral arteries. A failure in this second trimester increase in TNF-α protein could contribute to gestational compromise.