Obeticholic Acid Protects Against Lipopolysaccharide-induced Fetal Death And Intrauterine Growth Restriction Through Its Anti-Inflammatory

Background Lipopolysaccharide(LPS)is a toxic component of cell walls in gramnegative bacteria and is widely present in the digestive tracts of humans and animals,exposure to maternal gestational LPS can lead to adverse pregnancy outcomes such as IUGR.Farnesoid X receptor(FXR)is a nuclear receptor that plays an important role in the regulation of bile acid homeostasis and is expressed in both human and rodent placenta.Recent studies have shown that FXR has anti-inflammatory effects.Obeticholic acid(OCA),a novel synthetic FXR agonist,is currently in Phase II trials for the treatment of non-alcoholic steatohepatitis.Objective The objective of this study was to investigate whether OCA protects the intrauterine growth restriction(IUGR)induced by LPS and fetal death,and initially clarifies its mechanism.Methods This study includes the following two experiments.Experiment 1: to investigate the effects of pretreatment with OCA on LPS-induced fetal death and growth restriction,forty-eight ICR mice were randomly divided into four groups by body weight on the 13 th day of gestation(GD13).In LPS alone and OCA+LPS groups,pregnant mice were given intraperitoneal injection of LPS at 100 ?g/kg every day from GD15 to GD17.The dose of LPS used in the present study referred to our previous study.In OCA alone and OCA+LPS groups,pregnant mice were orally administered with OCA(5 mg/kg)daily from GD13 to GD17.All dams were sacrificed on GD18 and anesthetized with an eyeball to collect the blood of the female rats and the uterus weight was recorded.For each litter,the number of live fetuses,dead fetuses and resorption sites were counted.Live fetuses were weighed and crown-rump length was measured.Experiment 2: to investigate the effects of OCA on LPS-induced placental inflammation,forty-eight ICR mice were randomly divided into 6 groups according to body weight on GD13.In LPS alone and OCA+LPS groups,pregnant mice were given 100?g/kg LPS intraperitoneally on GD15 days.In OCA alone and LPS+OCA groups,pregnant mice were orally administered with OCA(5 mg/kg)daily from GD13 to GD15.All dams were sacrificed either 1 h or 6 h after LPS injection.Maternal serum and fetal amniotic fluid were collected to detect TNF-? and IL-10 levels.Placenta collection for real-time RT-PCR and immunoblot analysis.Some placentas were collected for immunohistochemistry.Results OCA alone did not elevate fetal mortality.Intraperitoneal injection with LPS daily from GD15 to GD17 resulted in 100 %(12/12)of pregnant mice with dead fetuses.The number of dead fetuses per litter was 3.3 in LPS group.The number of dead fetuses per litter was reduced to 0.4 in OCA-pretreated mice.The results showed that OCA pretreatment reduced LPS-induced fetal death and IUGR.Additional experimental results show that,OCA activates placental FXR signaling.OCA pretreatment inhibited the secretion of TNF-? in LPS-induced maternal serum and amniotic fluid and inhibited the LPS-induced upregulation of proinflammatory cytokines and chemokines.Pregnant maternal serum,amniotic fluid and placenta of OCA-treated pregnant rats had elevated levels of anti-inflammatory cytokine IL-10.Immunohistochemistry showed that pretreatment with OCA significantly attenuated LPS-evoked nuclear translocation of placental NF-?B p65 and p50 in mononuclear sinusoidal trophoblast gaint cells of the labyrinth zone.Conclusions OCA protects LPS-induced IUGR and fetal death by activating FXR signaling.