Effect of T-helper 1 cytokines on secretion of T-helper 2 cytokines by term trophoblast cells in culture

A successful pregnancy has been postulated to be the result of a discrete balance between T-helper 1 (Th1) and T-helper 2 (Th2) type cytokines involved in growth and development of the conceptus. The aim of the present study was to examine the effect of Th1 cytokines (interleukin-1β (IL-1β) and tumor necrosis factor-alpha (TNFα)) on the release of Th2 cytokines including IL-6 and IL-10 by trophoblast cells obtained from term placenta. Trophoblast cells isolated by enzymatic disaggregation and Percoll gradient fractionation were cultured in supplemented medium alone or with varying concentrations of the selected recombinant cytokines. After 48 h of incubation, samples of the culture supernatant were analyzed for the Th2 cytokines IL-6 and IL-10 using specific ELISA assays. Both IL-1β and TNFα had no effect on the cell number and viability as determined by MTT assay. IL-1β significantly stimulated trophoblast release of IL-6 in a dose-dependent manner (3.3-, 5.5-, 10.3- and 22.4-fold higher compared to the control at 10, 50, 100, 500 U IL-1β/ml respectively, p <0.05). TNFα also stimulated release of IL-6 by these cells. However, the stimulation at lower concentrations was not very high and a significant (p <0.05) stimulation was observed only at higher concentrations (1.1-, 1.3-, 2.6- and 5.9-fold higher at 500, 1000, 1500, 2000 U TNFα/ml respectively). In contrast, neither IL-1β or TNFα exerted any significant effect on IL-10 release by term trophoblast cells (p > 0.05). The results of this study provide evidence that production of Th2 cytokines might be under the control of different regulatory pathways.