Surfactant protein D modulates levels of IL-10 and TNF-α in intrauterine compartments during lipopolysaccharide-induced preterm birth

Abstract

Prematurity is the main cause of perinatal mortality and morbidity, and preterm birth is often associated with intrauterine inflammation. Surfactant protein D (SP-D) functions in lung homeostasis and has multiple roles in innate immunity. It is present in amniotic fluid and in gestational tissues. We propose that SP-D may regulate intrauterine inflammatory responses related to preterm labor. Our aim was to investigate the role of SP-D in lipopolysaccharide-induced preterm birth in mice that overexpress rat SP-D (rSP-D) under the human SP-C promoter. SP-D protein in amniotic fluid and in gestational tissues was detected by western analysis. TNF-α, IL-10, and IL-6 concentrations in serum and amniotic fluid and mRNA levels in gestational tissues were quantified using cytometric bead array and ribonuclease protection assay, respectively. Increased levels of SP-D protein were detected in the amniotic fluid and gestational tissues of rSP-D mice. Lipopolysaccharide given at 17 days post-coitum to rSP-D dams led to preterm birth of live-born offspring within 18 h. Preterm birth of live-born pups was induced with a lower dose of lipopolysaccharide compared to wild-type mice. In rSP-D mice, the lipopolysaccharide-induced levels of TNF-α and IL-10 in amniotic fluid and fetal serum and the expression of IL-10 in placenta and fetal membranes were significantly different from wild-type mice. We conclude that SP-D in fetal and gestational tissues modulates the levels of intrauterine inflammatory mediators involved in preterm birth and may contribute to inflammatory processes related to spontaneous preterm labor.