TNF, IL-1, IL-6, IL-8 and soluble TNF receptors in relation to chorioamnionitis and premature labor

Inflammatory cytokines seem to play a key role in mechanisms initiati ng labor. Since cytokine levels are higher in preterm than in term la bor, it h been hypothesized that labor-inducing effects of cytokines are inhibited by an upregulated production of cytokine antagonists, s uch as soluble cytokine receptors, at early stages of gestation. In t his study, TNF, IL-1, IL-6, IL-8 and soluble TNF receptors (sTNFRs) w ere measured in amniotic fluid samples from a) 39 women in premature labor, b) 25 women who where not in labor but delivered prematurely, and c) 33 women in term labor. Fifty-four of the placentas from prema ture deliveries were evaluated for presence of histological chorioamn ionitis. Chorioamnionitis was associated with increased levels of TNF , IL-1 and IL-6, whereas elevated IL-1, IL-6 and IL-8 concentrations were found in premature parturition with no signs of infection. Conce ntrations of sTNFR were lower in preterm than in term deliveries. The present study confirms the participation of inflammatory cytokines i n parturition. Multivariate analysis suggests a dominant, role of IL- 1 in the presence of chorioamnionitis, whereas IL-6 seems to be more important during idiopathic premature labor. TNFR data do not support the hypothesis that production of cytokine antagonists is upregulate d prematurely to prevent partirution.