Objective: The Toll-like receptor-2 and -4 recognize microbial products that are associated with gram-positive and gram-negative bacteria, respectively. This study examined Toll-like receptor-2 and -4 expression in fetal membranes in response to labor at term and histologic chorioamnionitis.
Study design: Immunohistochemistry and real-time quantitative reverse transcriptase-polymerase chain reaction were used to examine the chorioamnion from patients with (1) preterm labor and intact membranes, (2) preterm premature rupture of membranes who were delivered < or =34 weeks of gestation, and (3) women at term with or without labor. All groups were stratified on the basis of the presence of histologic chorioamnionitis.
Results: Toll-like receptor-2 expression was significantly higher in patients with chorioamnionitis than in patients without this condition (all P < .05). The Toll-like receptor-2 and -4 messenger RNA amounts were significantly higher in membranes from women at term with spontaneous labor than women who were not in labor ( P = .001 and .002, respectively). Toll-like receptor-2 expression was polarized to the basal surface of amniotic epithelial cells in patients without chorioamnionitis, but this distribution was lost in the presence of inflammation.
Conclusion: Spontaneous labor at term and preterm delivery with histologic chorioamnionitis, regardless of the membrane status (intact or ruptured), are associated with an increased expression of Toll-like receptor-2 and -4 in the chorioamniotic membranes. These observations have implications for understanding the biologic nature of innate immunity.