Abstract

Objective: Bacterial Vaginosis (BV) is associated with a 1.4-fold increased risk of preterm birth. Studies have shown that there is a higher incidence of spontaneous preterm birth and poorer neonatal outcome in pregnancies with a male fetus. We have shown previously that Lactobacillus rhamnosus GR-1 cell culture supernatant up-regulates IL-10 output in LPS-treated human placental trophoblast cells. We hypothesize that lactobacilli exerts its anti-inflammatory effect through up-regulation of G-CSF which is dependent on the sex of the fetus. Methods: Term placentae were collected from women undergoing elective Caesarean section. Placental trophoblasts were isolated using established primary culture protocols. Cells were treated with lipopolysaccharide (LPS) in the presence or absence of pretreatments with GR-1 cell culture supernatant or chemical inhibitors of the intracellular signaling pathways. Phosphorylations of p38 and STAT3 were measured by Western Blot analysis and output of G-CSF and IL-10 were determined by ELISA. Results: G-CSF output was increased relative to control only in the female placental trophoblast cells treated with LPS (>233.1-fold), GR-1 cell culture supernatant (>588.7-fold) and a combination of both treatments (>737.1-fold) (n=6 females, n=5 males, p=0.002). Phosphorylation of STAT-3 was up-regulated with GR-1 supernatant alone (>1.7-fold) and when combined with LPS (>1.8-fold) (n=10, p=0.018). In addition, p38 phosphorylation was increased with LPS (>1.3-fold), GR-1 supernatant (>2.1-fold) and combination of both treatments (>2.1-fold) (n=4, p=0.005). IL-10 output was inhibited by both JAK and p38 inhibitors (n=9, P<0.05). Conclusion: We conclude that lactobacilli upregulates the anti-inflammatory G-CSF in placental trophoblast cells of pregnancies with female but not male fetuses which may explain the adverse pregnancy outcomes seen with male fetuses. Lactobacilli also acts to increase the IL-10 output through activation of JAK/STAT and MAPK pathways. We propose that the upregulation of the anti-inflammatory G-CSF and IL-10 by probiotic lactobacilli may counter the effects of pathogenic bacteria in infection driven preterm birth.