Role of the maternal acute phase response and tumor necrosis factor alpha in the developmental toxicity of lipopolysaccharide in the CD-1 mouse

Distribution of endotoxin in maternal and fetal body with intrahepatic cholestasis of pregnancy and its association with adverse fetal outcome

BACKGROUND

Intrahepatic cholestasis of pregnancy is a pregnancy-specific liver disease. In this study, we sought to explore the distribution of lipopolysaccharide in the maternal body, and its effect on the fetal body in the intrahepatic cholestasis of pregnancy mice. It provides a new sight for the clinical treatment of women with intrahepatic cholestasis of pregnancy.

METHODS

The serum levels of lipopolysaccharide and lipopolysaccharide binding protein in women with intrahepatic cholestasis of pregnancy were analyzed. To assess the association between lipopolysaccharide levels and adverse fetal outcomes, ursodeoxycholic acid, resveratrol, and phosphatidylinositol-3-kinase inhibitor were employed in intrahepatic cholestasis of pregnancy mice, and we studied the fluorescence intensity and distribution of lipopolysaccharide in mice with intrahepatic cholestasis of pregnancy.

RESULTS

Our data indicated significantly elevated levels of lipopolysaccharide and lipopolysaccharide binding protein in women with intrahepatic cholestasis of pregnancy. In vivo fluorescence imaging revealed that the intensity of lipopolysaccharide in mice with intrahepatic cholestasis of pregnancy was higher than that in the control group, and decreased after ursodeoxycholic and resveratrol treatment. The fluorescence intensity analysis indicated that lipopolysaccharide levels in maternal liver, placenta, fetal brain and fetal liver were significantly higher in the intrahepatic cholestasis pregnancy mice group than in the control group.

CONCLUSIONS

This study provided evidence of endotoxin distribution in maternal liver, placenta, fetal liver and fetal brain in mice with intrahepatic cholestasis of pregnancy. Ursodeoxycholic acid and resveratrol treatment effectively reduced lipopolysaccharide levels in pregnant mice with intrahepatic cholestasis of pregnancy.

Effect of Sublethal Prenatal Endotoxaemia on Murine Placental Transport Systems and Lipid Homeostasis

Infection alters the expression of transporters that mediate the placental exchange of xenobiotics, lipids and cytokines. We hypothesized that lipopolysaccharide (LPS) modifies the expression of placental transport systems and lipid homeostasis. LPS (150 μg/kg; i.p.) treatments were administered for 4 h or 24 h, animals were euthanized at gestational days (GD) 15.5 or 18.5, and maternal blood, fetuses and placentae were collected. Increased rates of fetal demise were observed at GD15.5 following LPS treatment, whereas at GD18.5, high rates of early labour occurred and were associated with distinct proinflammatory responses. Lipopolysaccharide did not alter ATP-binding cassette (ABC) transporter mRNA expression but decreased fatty acid binding protein associated with plasma membrane (Fabppm) at GD15.5 (LPS-4 h) and increased fatty acid translocase (Fat/Cd36) mRNA at GD18.5 (LPS-4 h). At the protein level, breast cancer-related protein (Bcrp) and ABC sub-family G member 1 (Abcg1) levels were decreased in the placental labyrinth zone (Lz) at GD15.5, whereas P-glycoprotein (P-gp) and Bcrp Lz-immunostaining was decreased at GD18.5. In the placental junctional zone (Jz), P-gp, Bcrp and Abcg1 levels were higher at GD18.5. Specific maternal plasma and placental changes in triacylglycerol, free fatty acid, cholesterol, cholesterol ester and monoacylglycerol levels were detected in a gestational age-dependent manner. In conclusion, LPS-increased risk of fetal death and early labour were associated with altered placental ABC and lipid transporter expression and deranged maternal plasma and placental lipid homeostasis. These changes may potentially modify fetal xenobiotic exposure and placental lipid exchange in cases of bacterial infection.

Verbascoside-Rich Abeliophyllum distichum Nakai Leaf Extracts Prevent LPS-Induced Preterm Birth Through Inhibiting the Expression of Proinflammatory Cytokines from Macrophages and the Cell Death of Trophoblasts Induced by TNF-α

Background: Preterm birth is a known leading cause of neonatal mortality and morbidity. The underlying causes of pregnancy-associated complications are numerous, but infection and inflammation are the essential high-risk factors. However, there are no safe and effective preventive drugs that can be applied to pregnant women. Objective: The objectives of the study were to investigate a natural product, Abeliophyllum distichum leaf (ADL) extract, to examine the possibility of preventing preterm birth caused by inflammation. Methods: We used a mouse preterm birth model by intraperitoneally injecting lipopolysaccharides (LPS). ELISA, Western blot, real-time PCR and immunofluorescence staining analyses were performed to confirm the anti-inflammatory efficacy and related mechanisms of the ADL extracts. Cytotoxicity and cell death were measured using Cell Counting Kit-8 (CCK-8) analysis and flow cytometer. Results: A daily administration of ADL extract significantly reduced preterm birth, fetal loss, and fetal growth restriction after an intraperitoneal injection of LPS in mice. The ADL extract prevented the LPS-induced expression of TNF-α in maternal serum and amniotic fluid and attenuated the LPS-induced upregulation of placental proinflammatory genes, including IL-1β, IL-6, IL-12p40, and TNF-α and the chemokine gene CXCL-1, CCL-2, CCL3, and CCL-4. LPS-treated THP-1 cell-conditioned medium accelerated trophoblast cell death, and TNF-α played an essential role in this effect. The ADL extract reduced LPS-treated THP-1 cell-conditioned medium-induced trophoblast cell death by inhibiting MAPKs and the NF-κB pathway in macrophages. ADL extract prevented exogenous TNF-α-induced increased trophoblast cell death and decreased cell viability. Conclusions: We have demonstrated that the inhibition of LPS-induced inflammation by ADL extract can prevent preterm birth, fetal loss, and fetal growth restriction.

Modulatory Mechanism of Polyphenols and Nrf2 Signaling Pathway in LPS Challenged Pregnancy Disorders

Early embryonic loss and adverse birth outcomes are the major reproductive disorders that affect both human and animals. The LPS induces inflammation by interacting with robust cellular mechanism which was considered as a plethora of numerous reproductive disorders such as fetal resorption, preterm birth, teratogenicity, intrauterine growth restriction, abortion, neural tube defects, fetal demise, and skeletal development retardation. LPS-triggered overproduction of free radicals leads to oxidative stress which mediates inflammation via stimulation of NF-κB and PPARγ transcription factors. Flavonoids, which exist in copious amounts in nature, possess a wide array of functions; their supplementation during pregnancy activates Nrf2 signaling pathway which encounters pregnancy disorders. It was further presumed that the development of strong antioxidant uterine environment during gestation can alleviate diseases which appear at adult stages. The purpose of this review is to focus on modulatory properties of flavonoids on oxidative stress-mediated pregnancy insult and abnormal outcomes and role of Nrf2 activation in pregnancy disorders. These findings would be helpful for providing new insights in ameliorating oxidative stress-induced pregnancy disorders.

Obeticholic Acid Protects against Lipopolysaccharide-Induced Fetal Death and Intrauterine Growth Restriction through Its Anti-Inflammatory Activity

Farnesoid X receptor (FXR) is expressed in human and rodent placentas. Nevertheless, its function remains obscure. This study investigated the effects of obeticholic acid (OCA), a novel synthetic FXR agonist, on LPS-induced fetal death and intrauterine growth restriction. All pregnant mice except controls were i.p. injected with LPS (100 μg/kg) daily from gestational day (GD) 15 to GD17. Some pregnant mice were orally administered with OCA (5 mg/kg) daily from GD13 to GD17. As expected, placental FXR signaling was activated by OCA. OCA pretreatment protected against LPS-induced fetal death. In addition, OCA pretreatment alleviated LPS-induced reduction of fetal weight and crown-rump length. Additional experiments showed that OCA inhibited LPS-evoked TNF-α in maternal serum and amniotic fluid. Moreover, OCA significantly attenuated LPS-induced upregulation of placental proinflammatory genes including Tnf-α, Il-1β, IL-6, Il-12, Mip-2, Kc, and Mcp-1 By contrast, OCA elevated anti-inflammatory cytokine IL-10 in maternal serum, amniotic fluid, and placenta. Further analysis showed that OCA blocked nuclear translocation of NF-κB p65 and p50 subunits in trophoblast giant cells of the labyrinth zone. These results provide a mechanistic explanation for placental FXR-mediated anti-inflammatory activity. Overall, this study provides evidence for roles of FXR as an important regulator of placental inflammation.

Rosiglitazone pretreatment protects against lipopolysaccharide-induced fetal demise through inhibiting placental inflammation

Peroxisome proliferator-activated receptor (PPAR)-γ is highly expressed in human and rodent placentas. Nevertheless, its function remains obscure. The present study investigated the effects of rosiglitazone, a PPAR-γ agonist, on LPS-induced fetal death. All pregnant mice except controls were intraperitoneally injected with LPS (150 μg/kg) daily from gestational day (GD)15 to GD17. As expected, maternal LPS injection caused placental inflammation and resulted in 63.6% fetal death in dams that completed the pregnancy. Interestingly, LPS-induced fetal mortality was reduced to 16.0% when pregnant mice were pretreated with RSG. Additional experiment showed that rosiglitazone pretreatment inhibited LPS-induced expressions of tumor necrosis factor (Tnf)-α, interleukin (Il)-1β, Il-6, macrophage inflammatory protein (Mip)-2 and keratinocyte-derived chemokine (Kc) in mouse placenta. Although rosiglitazone had little effect on LPS-evoked elevation of IL-10 in amniotic fluid, it alleviated LPS-evoked release of TNF-α and MIP-2 in amniotic fluid. Further analysis showed that pretreatment with rosiglitazone, which activated placental PPAR-γ signaling, simultaneously suppressed LPS-evoked nuclear factor kappa B (NF-κB) activation and blocked nuclear translocation of NF-κB p65 and p50 subunits in trophoblast giant cells of the labyrinth layer. These results provide a mechanistic explanation for PPAR-γ-mediated anti-inflammatory activity in the placentas. Overall, the present study provides additional evidence for roles of PPAR-γ as an important regulator of placental inflammation.

Supplementation with vitamin D3 during pregnancy protects against lipopolysaccharide-induced neural tube defects through improving placental folate transportation

Several reports demonstrated that maternal lipopolysaccharide (LPS) exposure at middle gestational stage caused neural tube defects (NTDs). This study investigated the effects of supplementation with vitamin D3 (VitD3) during pregnancy on LPS-induced NTDs. Pregnant mice except controls were ip injected with LPS (25 μg/kg) daily from gestational day (GD)8 to GD12. In LPS+VitD3 group, pregnant mice were orally administered with VitD3 (25 μg/kg) before LPS injection. As expected, a 5-day LPS injection resulted in 62.5% (10/16) of dams and 20.3% of fetuses with NTDs. Additional experiment showed that a 5-day LPS injection downregulated placental proton-coupled folate transporter (pcft) and reduced folate carrier 1 (rfc1), 2 major folate transporters in placentas. Consistent with downregulation of placental folate transporters, folate transport from maternal circulation into embryos was disturbed in LPS-treated mice. Interestingly, VitD3 not only inhibited placental inflammation but also attenuated LPS-induced downregulation of placental folate transporters. Correspondingly, VitD3 markedly improved folate transport from maternal circulation into the embryos. Importantly, supplementation with VitD3 during pregnancy protected mice from LPS-induced NTDs. Taken together, these results suggest that supplementation with VitD3 during pregnancy prevents LPS-induced NTDs through inhibiting placental inflammation and improving folate transport from maternal circulation into the embryos.

Orally administered melatonin prevents lipopolysaccharide-induced neural tube defects in mice

Lipopolysaccharide (LPS) has been associated with adverse pregnant outcomes, including fetal demise, intra-uterine growth restriction (IUGR), neural tube defects (NTDs) and preterm delivery in rodent animals. Previous studies demonstrated that melatonin protected against LPS-induced fetal demise, IUGR and preterm delivery. The aim of the present study was to investigate the effects of melatonin on LPS-induced NTDs. All pregnant mice except controls were intraperitoneally injected with LPS (25 µg/kg) daily from gestational day (GD)8 to GD12. Some pregnant mice were orally administered with melatonin (MT, 50 mg/kg) before each LPS injection. A five-day LPS injection resulted in 27.5% of fetuses with anencephaly, exencephaly or encephalomeningocele. Additional experiment showed that maternal LPS exposure significantly down-regulated placental proton-coupled folate transporter (pcft) and disturbed folate transport from maternal circulation through the placentas into the fetus. Interestingly, melatonin significantly attenuated LPS-induced down-regulation of placental pcft. Moreover, melatonin markedly improved the transport of folate from maternal circulation through the placentas into the fetus. Correspondingly, orally administered melatonin reduced the incidence of LPS-induced anencephaly, exencephaly or encephalomeningocele. Taken together, these results suggest that orally administered melatonin prevents LPS-induced NTDs through alleviating LPS-induced disturbance of folate transport from maternal circulation through the placenta into the fetus.

Maternal LPS exposure during pregnancy impairs testicular development, steroidogenesis and spermatogenesis in male offspring

Lipopolysaccharide (LPS) is associated with adverse developmental outcomes including embryonic resorption, fetal death, congenital teratogenesis and fetal growth retardation. Here, we explored the effects of maternal LPS exposure during pregnancy on testicular development, steroidogenesis and spermatogenesis in male offspring. The pregnant mice were intraperitoneally injected with LPS (50 µg/kg) daily from gestational day (GD) 13 to GD 17. At fetal period, a significant decrease in body weight and abnormal Leydig cell aggregations were observed in males whose mothers were exposed to LPS during pregnancy. At postnatal day (PND) 26, anogenital distance (AGD), a sensitive index of altered androgen action, was markedly reduced in male pups whose mothers were exposed to LPS daily from GD13 to GD 17. At PND35, the weight of testes, prostates and seminal vesicles, and serum testosterone (T) level were significantly decreased in LPS-treated male pups. At adulthood, the number of sperm was significantly decreased in male offspring whose mothers were exposed to LPS on GD 13-17. Maternal LPS exposure during gestation obviously diminished the percent of seminiferous tubules in stages I-VI, increased the percent of seminiferous tubules in stages IX-XII, and caused massive sloughing of germ cells in seminiferous tubules in mouse testes. Moreover, maternal LPS exposure significantly reduced serum T level in male mice whose mothers were exposed to LPS challenge during pregnancy. Taken together, these results suggest that maternal LPS exposure during pregnancy disrupts T production. The decreased T synthesis might be associated with LPS-induced impairments for spermatogenesis in male offspring.

HO-1 as modulator of the innate immune response in pregnancy

PROBLEM

The immune modulatory effect of heme oxygenase-1 (HO-1) is well documented in studies about sepsis and transplantation. This work evaluates the influence of HO-1 on the innate immune response during pregnancy.

METHOD OF STUDY

Human first-trimester trophoblasts derived from normal pregnancies or spontaneous abortions were analyzed for their basal HO-1, BCL-associated athanogene-1 (Bag-1), and cytokine production before and after LPS treatment. In vivo, pregnant Hmox1+/+ and Hmox1+/- female mice were treated with LPS, and the production of Bag-1 was evaluated.

RESULTS

Human trophoblasts up-regulated the expression of both HO-1 and pro-inflammatory cytokines after LPS treatment, whereas the basal level of HO-1 was higher in normal pregnancies. In vivo, HO-1 deficiency provoked diminished Bag-1 level upon LPS treatment.

CONCLUSION

HO-1 deficiency causes an inflammatory immune reaction and diminished expression of protective molecules in trophoblasts. Thus, HO-1 emerges as one important modulator of innate immune responses in pregnancy.

Zinc supplementation during pregnancy protects against lipopolysaccharide-induced fetal growth restriction and demise through its anti-inflammatory effect

LPS is associated with adverse developmental outcomes, including preterm delivery, fetal death, teratogenicity, and intrauterine growth restriction (IUGR). Previous reports showed that zinc protected against LPS-induced teratogenicity. In the current study, we investigated the effects of zinc supplementation during pregnancy on LPS-induced preterm delivery, fetal death and IUGR. All pregnant mice except controls were i.p. injected with LPS (75 μg/kg) daily from gestational day (GD) 15 to GD17. Some pregnant mice were administered zinc sulfate through drinking water (75 mg elemental Zn per liter) throughout the pregnancy. As expected, an i.p. injection with LPS daily from GD15 to GD17 resulted in 36.4% (4/11) of dams delivered before GD18. In dams that completed the pregnancy, 63.2% of fetuses were dead. Moreover, LPS significantly reduced fetal weight and crown-rump length. Of interest, zinc supplementation during pregnancy protected mice from LPS-induced preterm delivery and fetal death. In addition, zinc supplementation significantly alleviated LPS-induced IUGR and skeletal development retardation. Further experiments showed that zinc supplementation significantly attenuated LPS-induced expression of placental inflammatory cytokines and cyclooxygenase-2. Zinc supplementation also significantly attenuated LPS-induced activation of NF-κB and MAPK signaling in mononuclear sinusoidal trophoblast giant cells of the labyrinth zone. It inhibited LPS-induced placental AKT phosphorylation as well. In conclusion, zinc supplementation during pregnancy protects against LPS-induced fetal growth restriction and demise through its anti-inflammatory effect.

Immune stress in late pregnant rats decreases length of gestation and fecundity, and alters later cognitive and affective behaviour of surviving pre-adolescent offspring

Immune challenge during pregnancy is associated with preterm birth and poor perinatal development. The mechanisms of these effects are not known. 5α-Pregnan-3α-ol-20-one (3α,5α-THP), the neuroactive metabolite of progesterone, is critical for neurodevelopment and stress responses, and can influence cognition and affective behaviours. To develop an immune challenge model of preterm birth, pregnant Long-Evans rat dams were administered lipopolysaccharide [LPS; 30 μg/kg/ml, intraperitoneal (IP)], interleukin-1β (IL-1β; 1 μg/rat, IP) or vehicle (0.9% saline, IP) daily on gestational days 17-21. Compared to control treatment, prenatal LPS or IL-1β reduced gestational length and the number of viable pups born. At 28-30 days of age, male and female offspring of mothers exposed to prenatal IL-1β had reduced cognitive performance in the object recognition task compared to controls. In females, but not males, prenatal IL-1β reduced anxiety-like behaviour, indicated by entries to the centre of an open field. In the hippocampus, progesterone turnover to its 5α-reduced metabolites was lower in prenatally exposed IL-1β female, but not in male offspring. IL-1β-exposed males and females had reduced oestradiol content in hippocampus, medial prefrontal cortex and diencephalon compared to controls. Thus, immune stress during late pregnancy reduced gestational length and negatively impacted birth outcomes, hippocampal function and central neurosteroid formation in the offspring.

Melatonin alleviates lipopolysaccharide-induced placental cellular stress response in mice

Melatonin protects mice from lipopolysaccharide (LPS)-induced fetal death and intra-uterine growth retardation. Nevertheless, its molecular mechanism remains obscure. In the present study, we investigated the effects of melatonin on LPS-induced cellular stress in placenta. Pregnant mice were given with melatonin [5.0 mg/kg, intraperitoneal (i.p.)] 30 min before and 150 min after LPS (300 μg/kg, i.p.) on gestational day 15. Oxidative stress, endoplasmic reticulum (ER) stress, hypoxic stress, and heat stress in placenta were analyzed at 4 hr after LPS. As expected, maternal LPS administration resulted in placental glutathione (GSH) depletion and up-regulated the expression of placental antioxidative enzymes. In addition, LPS significantly increased the level of inducible nitric oxide synthase (iNOS) and enhanced the intensity of placental 3-nitrotyrosine residues. An ER stress, as determined by a decreased GRP78 expression, an obvious eIF2α and JNK phosphorylation, and an increased CHOP expression, were observed in placenta of pregnant mice injected with LPS. In addition, LPS significantly increased mRNA level of placental HIF-1α, VEGF, and ET-1, the markers of hypoxic stress. Heme oxygenase (HO)-1, a marker of heat stress, was also up-regulated in placenta of LPS-treated pregnant mice. Interestingly, LPS-induced placental oxidative stress, hypoxic stress, and ER stress were significantly alleviated when pregnant mice were given with melatonin, whereas melatonin had little effect on LPS-evoked placental HO-1 expression. In conclusion, maternally administered melatonin alleviates LPS-induced cellular stress in the placenta. Melatonin may be useful as pharmacological agents to protect the fetuses against LPS-induced intra-uterine fetal death and intra-uterine growth restriction.

Age- and gender-dependent impairments of neurobehaviors in mice whose mothers were exposed to lipopolysaccharide during pregnancy

Lipopolysaccharide (LPS)-induced intrauterine infection has been associated with neurodevelopmental injury in rodents. The purpose of the present study was to analyze the dynamic changes of neurobehaviors in mice whose mothers were exposed to LPS during pregnancy. The pregnant mice were intraperitoneally (i.p.) injected with LPS (8 microg/kg) daily from gestational day (gd) 8 to gd 15. A battery of neurobehavioral tasks was performed in mice at postnatal day (PND) 70, 200, 400 and 600. Results showed that the spatial learning and memory ability, determined by radial six-arm water maze (RAWM), were obviously impaired in two hundred-day-old female mice and four hundred-day-old male mice whose mothers were exposed to LPS during pregnancy. Open field test showed that the number of squares crossed and peripheral time, a marker of anxiety and exploration activity, were markedly increased in two hundred-day-old female mice following prenatal LPS exposure. In addition, prenatal LPS exposure significantly shortened the latency to the first grid crossing in six hundred-day-old female offspring. Moreover, sensorimotor impairment in the beam walking was observed in two hundred-day-old female mice whose mothers were exposed to LPS during pregnancy. Species-typical behavior examination showed that prenatal LPS exposure markedly increased weight burrowed in seventy-day-old male offspring and six hundred-day-old female offspring. Correspondingly, prenatal LPS exposure significantly reduced weight hoarded in two hundred-day-old female offspring. Taken together, these results suggest that prenatal LPS exposure induces neurobehavioral impairments at adulthood in an age- and gender-dependent manner.

Maternally administered melatonin differentially regulates lipopolysaccharide-induced proinflammatory and anti-inflammatory cytokines in maternal serum, amniotic fluid, fetal liver, and fetal brain

Lipopolysaccharide (LPS) has been associated with adverse developmental outcome, including intra-uterine fetal death and intra-uterine growth retardation. In the LPS model, tumor necrosis factor alpha (TNF-alpha) is the major mediator leading to intra-uterine fetal death and intra-uterine growth retardation. Interleukin (IL)-10 protects rodents against LPS-induced intra-uterine fetal death and intra-uterine growth retardation. Melatonin is an immunomodulator. In the present study, we investigated the effect of maternally administered melatonin on LPS-induced proinflammatory and anti-inflammatory cytokines in maternal serum, amniotic fluid, fetal liver and fetal brain. The time pregnant mice were injected with melatonin [5.0 mg/kg, intraperitoneal (i.p.)] 30 min before LPS (500 microg/kg, i.p.) on gestational day 17. As expected, TNF-alpha, IL-1beta, IL-6 and IL-10 were obviously increased in maternal serum and amniotic fluid in response to LPS. In addition, maternal LPS exposure significantly increased the levels of TNF-alpha, IL-1beta, IL-6 and IL-10 in fetal liver, and TNF-alpha and IL-10 in fetal brain. Melatonin pretreatment significantly attenuated LPS-evoked elevation of TNF-alpha in maternal serum. On the contrary, melatonin aggravated LPS-induced increase in IL-10 in maternal serum. Melatonin had no effect on LPS-evoked IL-1beta and IL-6 in maternal serum and amniotic fluid. Interestingly, maternally administered melatonin also significantly attenuated LPS-evoked elevation of TNF-alpha in fetal brain, whereas the indole aggravated LPS-induced increase in IL-10 in fetal liver. Taken together, these results indicate that maternally administered melatonin differentially regulates LPS-induced proinflammatory and anti-inflammatory cytokines in maternal serum, amniotic fluid, fetal liver, and fetal brain.

Effects of low-dose lipopolysaccharide (LPS) pretreatment on LPS-induced intra-uterine fetal death and preterm labor

Lipopolysaccharide (LPS) has been associated with adverse developmental outcome, including embryonic resorption, intra-uterine fetal death (IUFD), intra-uterine growth retardation (IUGR) and preterm delivery in rodents. The purpose of the present study was to investigate whether administration of a low-dose LPS to the pregnant mice induce a reduced sensitivity to subsequent high-dose LPS-induced IUFD and preterm labor. We found that LPS-induced IUFD was obviously attenuated when the pregnant mice were pretreated with low-dose LPS (10 microg/kg, i.p.) 24h before high-dose LPS (120 microg/kg, i.p.). Consistent with its protective effect, when administered 24h before high-dose LPS, low-dose LPS pretreatment obviously inhibited the releases of tumor necrosis factor alpha (TNF-alpha) in maternal serum and amniotic fluid and attenuated LPS-induced placental lipid peroxidation and GSH depletion. However, when administered 4h before high-dose LPS, low-dose LPS pretreatment did not induced a reduced sensitivity to subsequent high-dose LPS-induced release of TNF-alpha in maternal serum and amniotic fluid. Actually, low-dose LPS pretreatment 4h before high-dose LPS worsened LPS-induced oxidative stress in mouse placenta and increased nitric oxide production in maternal serum and amniotic fluid. Correspondingly, low-dose LPS pretreatment 4h before high-dose LPS aggravated LPS-induced IUFD. Taken together, these results indicate that whether a low-dose LPS exposure during pregnancy produce LPS hyporesponsiveness depends on the interval between the two doses of LPS. When administered 24h before high-dose LPS, a low-dose LPS pretreatment induces a reduced sensitivity to subsequent high-dose LPS-induced IUFD, TNF-alpha production and oxidative stress.

Reactive oxygen species are involved in lipopolysaccharide-induced intrauterine growth restriction and skeletal development retardation in mice

OBJECTIVE

Maternal infection is a cause of adverse developmental outcomes including embryonic resorption, intrauterine fetal death, and preterm labor. Lipopolysaccharide-induced developmental toxicity at early gestational stages has been well characterized. The purpose of the present study was to investigate the effects of maternal lipopolysaccharide exposure at late gestational stages on intrauterine fetal growth and skeletal development and to assess the potential role of reactive oxygen species in lipopolysaccharide-induced intrauterine fetal growth restriction and skeletal development retardation.

STUDY DESIGN

The timed pregnant CD-1 mice were intraperitoneally injected with lipopolysaccharide (25 to 75 microg/kg per day) on gestational day 15 to 17. To investigate the role of reactive oxygen species on lipopolysaccharide-induced intrauterine fetal growth restriction and skeletal development retardation, the pregnant mice were injected with alpha-phenyl-N-t-butylnitrone (100 mg/kg, intraperitoneally) at 30 minutes before lipopolysaccharide (75 microg/kg per day, intraperitoneally), followed by an additional dose of alpha-phenyl-N-t-butylnitrone (50 mg/kg, intraperitoneally) at 3 hours after lipopolysaccharide. The number of live fetuses, dead fetuses, and resorption sites was counted on gestational day 18. Live fetuses in each litter were weighed. Crown-rump and tail lengths were examined and skeletal development was evaluated.

RESULTS

Maternal lipopolysaccharide exposure significantly increased fetal mortality, reduced fetal weight and crown-rump and tail lengths of live fetuses, and retarded skeletal ossification in caudal vertebrae, anterior and posterior phalanges, and supraoccipital bone in a dose-dependent manner. Alpha-phenyl-N-t-butylnitrone, a free radical spin-trapping agent, almost completely blocked lipopolysaccharide-induced fetal death (63.2% in lipopolysaccharide group versus 6.5% in alpha-phenyl-N-t-butylnitrone + lipopolysaccharide group, P < .01). In addition, alpha-phenyl-N-t-butylnitrone significantly reversed lipopolysaccharide-induced intrauterine growth restriction and skeletal development retardation. However, aminoguanidine, a selective inhibitor of inducible nitric oxide synthase, had little effect. Furthermore, lipopolysaccharide-induced intrauterine fetal death, intrauterine fetal growth restriction, and skeletal development retardation were associated with lipid peroxidation and glutathione depletion in maternal liver, placenta, and fetal liver. Alpha-phenyl-N-t-butylnitrone significantly attenuated lipopolysaccharide-induced lipid peroxidation and glutathione depletion in maternal liver, placenta, and fetal liver.

CONCLUSION

Maternal lipopolysaccharide exposure at late gestational stages results in intrauterine fetal growth restriction and skeletal development retardation in mice. Reactive oxygen species might be, at least in part, involved in lipopolysaccharide-induced intrauterine fetal growth restriction and skeletal development retardation.

Dietary zinc supplementation ameliorates LPS-induced teratogenicity in mice

Maternal infection during the first trimester of pregnancy has been associated with preterm birth, spontaneous abortion, growth retardation, and congenital anomalies. Previously, our group has shown that subcutaneous injection of zinc prevents endotoxin [lipopolysaccharide (LPS)]-induced teratogenicity. The purpose of this study was to investigate whether increasing or decreasing dietary zinc alters the teratogenic effects of LPS. Female C57BL6 mice were mated and fed diets containing 5, 35, or 100 mg/kg zinc. On gestational day (GD) 8, pregnant dams were injected with either LPS (0.5 mg/kg s.c.) or saline and killed on GD18. LPS-treated fetuses from dams fed 5 and 35 mg/kg zinc diet had a significantly higher number of abnormalities per litter (2- and 1- fold saline controls, respectively) compared with those from LPS + zinc supplemented dams, which were not significantly different from the saline control groups. The beneficial effect and importance of zinc was also reflected in the larger size of fetuses (weight and crown-rump length) from the LPS + zinc-supplemented treatment group. We have demonstrated that low dietary zinc during exposure to infection (i.e. LPS) in pregnancy augments the negative impact of LPS alone, and that dietary zinc supplementation throughout pregnancy ameliorates LPS-induced teratogenicity.

Ascorbic acid protects against lipopolysaccharide-induced intra-uterine fetal death and intra-uterine growth retardation in mice

Lipopolysaccharide (LPS) has been associated with adverse developmental outcomes including embryonic resorption, intra-uterine fetal death (IUFD), intra-uterine growth retardation (IUGR) and preterm labor. Reactive oxygen species (ROS) mediate LPS-induced developmental toxicity. Ascorbic acid is an antioxidant. In the present study, we investigated the effect of ascorbic acid on LPS-induced IUFD and IUGR in mice. All ICR pregnant mice except controls received an intraperitoneal (75 microg/kg, i.p.) injection of LPS daily on gd 15-17. The experiment was carried out in three different modes. In mode A, the pregnant mice were pretreated with a single dose (500 mg/kg, i.p.) of ascorbic acid before LPS. In mode B, the pregnant mice were administered with a single dose (500 mg/kg, i.p.) of ascorbic acid at 3h after LPS. In mode C, the pregnant mice were administered with 500 mg/kg (i.p.) of ascorbic acid at 30 min before LPS, followed by additional dose (500 mg/kg, i.p.) of ascorbic acid at 3h after LPS. The number of live fetuses, dead fetuses and resorption sites was counted on gd 18. Live fetuses in each litter were weighed. Crown-rump and tail lengths were examined and skeletal development was evaluated. Results showed that maternally administered LPS significantly increased fetal mortality, decreased fetal weight and crown-rump and tail lengths of live fetuses, and retarded skeletal ossification in caudal vertebrae, anterior and posterior phalanges, and supraoccipital bone. LPS-induced IUFD and IUGR were associated with lipid peroxidation and GSH depletion in maternal liver, placenta and fetal liver. Pre-treatment with ascorbic acid significantly attenuated LPS-induced lipid peroxidation, decreased fetal mortality, and reversed LPS-induced fetal growth and skeletal development retardation. By contrast to pre-treatment, post-treatment with ascorbic acid had less effect on LPS-induced IUFD, although post-treatment significantly attenuated LPS-induced lipid peroxidation and reversed LPS-induced fetal growth and skeletal development retardation. Furthermore, post-treatment with ascorbic acid reduced the protective effects of pre-treatment on LPS-induced IUFD. All these results suggest that pre-treatment with ascorbic acid protected against LPS-induced fetal death and reversed LPS-induced growth and skeletal development retardation via counteracting LPS-induced oxidative stress, whereas post-treatment had less effect on LPS-induced IUFD.

Melatonin protects against lipopolysaccharide-induced intra-uterine fetal death and growth retardation in mice

Lipopolysaccharide (LPS) has been associated with adverse developmental outcomes, including intra-uterine fetal death (IUFD) and intra-uterine growth retardation (IUGR). However, the exact mechanism for LPS-induced IUFD and IURD remains unclear. LPS stimulates macrophages to generate reactive oxygen species (ROS). Therefore, we hypothesize that ROS may be involved in LPS-induced IUFD and IURD. Melatonin is a powerful endogenous antioxidant. In this study, we investigated the protective effects of melatonin on LPS-induced IUFD and IURD in ICR mice. All pregnant mice except controls received an intraperitoneal (75 microg/kg, i.p.) injection of LPS on gestational day (gd) 15-17. The experiment was carried out in two different modes. In mode A, the pregnant mice received two doses of melatonin within 24 hr, one (5 or 10 mg/kg) injected immediately after LPS and the other (5 or 10 mg/kg) injected at 3 hr after LPS. In mode B, the pregnant mice were pretreated with 10 mg/kg of melatonin 18 hr before LPS and then received two doses of melatonin in 24 hr, one (10 mg/kg) injected immediately after LPS and the other (10 mg/kg) injected 3 hr after LPS. The number of live fetuses, dead fetuses and resorption sites were counted on gd 18. Live fetuses in each litter were weighed. Crown-rump and tail lengths were examined and skeletal development was evaluated. Results showed that post-treatments with melatonin significantly attenuated LPS-induced IUFD in a dose-dependent manner. Surprisingly, pre- plus post-treatments with melatonin almost blocked LPS-induced IUFD. In addition, both post-treatments and pre- plus post-treatments with melatonin significantly alleviated LPS-induced decreases in crown-rump and tail lengths and reversed LPS-induced skeletal developmental retardation. However, melatonin had little effect on LPS-induced decrease in fetal weight. Furthermore, pre- plus post-treatments with melatonin significantly attenuated LPS-induced lipid peroxidation in maternal liver. These results indicate that melatonin protects against LPS-induced IURD and IUGR via counteracting LPS-induced oxidative stress.

Tumor necrosis factor alpha partially contributes to lipopolysaccharide-induced intra-uterine fetal growth restriction and skeletal development retardation in mice

Maternal infection is a cause of adverse developmental outcomes. Lipopolysaccharide (LPS)-induced embryonic resorption, intra-uterine fetal death (IUFD) and preterm labor have been well characterized. In the present study, we investigated the effects of maternal LPS exposure on intra-uterine fetal growth and skeletal development. All pregnant mice except controls received an intraperitoneal injection of LPS (75 microg/kg) on gestational days (GD) 15-17. The number of live fetuses, dead fetuses and resorption sites was counted on GD 18. Live fetuses in each litter were weighed. Crown-rump and tail lengths were examined and skeletal development was evaluated. As expected, perinatal LPS exposure resulted in 63.2% fetal death. LPS significantly lowered fetal weight, reduced crown-rump and tail lengths, and retarded skeletal ossification in caudal vertebrae, anterior and posterior phalanges, and supraoccipital bone. Additional experiment showed that a single dose of LPS (75 microg/kg, i.p.) on GD 15 increased the expression of TNF-alpha mRNA in maternal liver and placenta and TNF-alpha concentration in maternal serum and amniotic fluid. Furthermore, pentoxifylline, an inhibitor of TNF-alpha synthesis, significantly inhibited TNF-alpha production, reduced fetal mortality, and reversed LPS-induced fetal intra-uterine growth restriction and skeletal development retardation. Taken together, these results suggest that TNF-alpha is, at least in part, involved in LPS-induced intra-uterine fetal death, intra-uterine growth restriction and skeletal development retardation.

Effect of N-Acetylcysteine on Lipopolysaccharide-Induced Intra-uterine Fetal Death and Intra-uterine Growth Retardation in Mice

Lipopolysaccharide (LPS) has been associated with adverse developmental outcome, including embryonic resorption, intra-uterine fetal death (IUFD), intra-uterine growth retardation (IUGR), and preterm delivery. Reactive oxygen species (ROS) have been associated with LPS-induced developmental toxicity. N-acetylcysteine (NAC) is a glutathione (GSH) precursor and direct antioxidant. The present study investigated the effects of NAC on LPS-induced IUFD and IUGR. All pregnant mice except controls were injected with LPS (75 microg/kg, ip) on gestational day (GD) 15-17. NAC was administered in two different modes. In mode A, the pregnant mice were pretreated with two doses of NAC (either 50 plus 25 mg/kg or 200 plus 100 mg/kg) before LPS, one (either 50 or 200 mg/kg) at 12 h before LPS and the other (either 25 or 100 mg/kg) at 15 min before LPS. In mode B, the pregnant mice were administered with two doses of NAC (either 50 plus 25 mg/kg or 200 plus 100 mg/kg) in 24 h, one (either 50 or 200 mg/kg) injected immediately after LPS and the other (either 25 or 100 mg/kg) injected 3 h after LPS. The number of live fetuses, dead fetuses and resorption sites was counted on GD 18. Live fetuses in each litter were weighed. Crown-rump and tail lengths were measured and skeletal development was evaluated. Results showed that pretreatment with NAC significantly alleviated LPS-induced fetal mortality and reversed LPS-induced growth and skeletal development retardation. Correspondingly, pretreatment with NAC significantly attenuated LPS-induced elevation in TNF-alpha concentration in maternal serum and amniotic fluid and lipid peroxidation in maternal and fetal livers. By contrast to pretreatment, posttreatment with NAC had no effect on LPS-induced TNF-alpha production and lipid peroxidation. When administered after LPS, NAC did not protect against LPS-induced IUFD and IUGR and in fact aggravated LPS-induced preterm labor. All these results indicate that NAC had a dual effect on LPS-induced IUFD and IUGR. Pretreatment with NAC improves fetal survival and reverses LPS-induced fetal growth and skeletal development retardation, whereas posttreatment with NAC aggravates LPS-induced preterm labor.

Mechanism of acute fetal cardiovascular depression after maternal inflammatory challenge in mouse

Intra-amniotic lipopolysaccharide (LPS) causes an acute inflammatory response and cardiac dysfunction in fetal mice. We hypothesized that the placenta protects the fetus against maternally administered bacterial toxins, delaying the onset of a fetal inflammatory response and vascular compromise. At 14 to 15 days of gestation, DBA mice were randomized to receive LPS (2.4 mg/kg) or vehicle intraperitoneally. Doppler ultrasonography of fetal cardiovascular hemodynamics was performed before and 6 hours after maternal LPS. Six hours after the LPS, maternal serum concentrations of tumor necrosis factor-alpha and interleukin (IL)-6 (P < 0.05) were increased. Placenta showed severe maternal vascular dilatation and congestion. The expressions of tumor necrosis factor-alpha, IL-1alpha, and IL-6 (P < 0.05) were increased, and the expression of Toll-like receptor 4 was constitutive in placenta. The expression of Toll-like receptor 2 increased (P < 0.05) and was detected in labyrinthine macrophages. No inflammatory activation was found in fetal tissues, and amniotic fluid revealed no significant increase in cytokines. The ultrasonographic examination demonstrated increased fetal cardiac afterload after LPS, with 65% of the fetuses exhibiting atrioventricular valve regurgitation. In conclusion, maternal inflammatory insult activates placental labyrinthine macrophages leading to an acute increase in placental vascular resistance and fetal cardiac dysfunction without an inflammatory response in fetus.

Antagonism of croton oil inflammation by topical emu oil in CD-1 mice

Emu oil is derived from the emu (Dromaius novaehollandiae), which originated in Australia, and has been reported to have anti-inflammatory properties. Inflammation was induced in anesthetized CD-1 mice by applying 50 microL of 2% croton oil to the inner surface of the left ear. After 2 h, the area was treated with 5 microL of emu, fish, flaxseed, olive, or liquified chicken fat, or left untreated. Animals were euthanized at 6 h postapplication of different oils, and earplugs (EP) and plasma samples were collected. Inflammation was evaluated by change in earlobe thickness, increase in weight of EP tissue (compared to the untreated ear), and induction in cytokines interleukin (IL)-1alpha and tumor necrosis factor-alpha (TNF-alpha) in EP homogenates. Although reductions relative to control (croton oil) were noted for all treatments, auricular thickness and EP weights were significantly reduced (-72 and -71%, respectively) only in the emu oil-treated group. IL-1alpha levels in homogenates of auricular tissue were significantly reduced in the fish oil (-57%) and emu oil (-70%) groups relative to the control group. The cytokine TNF-alpha from auricular homogenates was significantly reduced in the olive oil (-52%) and emu oil (-60%) treatment groups relative to the control group. Plasma cytokine levels were not changed by croton oil treatment. Although auricular thickness and weight were significantly correlated with each other (r = 0.780, P < 0.003), auricular thickness but not weight was significantly correlated with cytokine IL-alpha (r = 0.750, P < 0.006) and TNF-alpha (r = 0.690, P < 0.02). These studies indicate that topical emu oil has anti-inflammatory properties in the CD-1 mouse that are associated with decreased auricular thickness and weight, and with the cytokines IL-1alpha and TNF-alpha.