Lipopolysaccharide (LPS)-induced intra-uterine fetal death (IUFD) in mice is principally due to maternal cause but not fetal sensitivity to LPS

Mouse Trophoblast Cells Have Attenuated Responses to TNF-α and IFN-γ and Can Avoid Synergic Cytotoxicity of the Two Cytokines

TNF-α and IFN-γ are two inflammatory cytokines that play critical roles in immune responses, but they can also negatively affect cell proliferation and viability. In particular, the combination of the two cytokines (TNF-α/IFN-γ) synergistically causes cytotoxicity in many cell types. We recently reported that mouse embryonic stem cells (ESCs) isolated from the blastocyst stage embryo do not respond to TNF-α and have limited response to IFN-γ, thereby avoiding TNF-α/IFN-γ cytotoxicity. The current study expanded our investigation to mouse trophoblast stem cells (TSCs) and their differentiated trophoblasts (TSC-TBs), the precursors and the differentiated cells of the placenta, respectively. In this study, we report that the combination of TNF-α/IFN-γ does not show the cytotoxicity to TSCs and TSC-TBs that otherwise effectively kills fibroblasts, similar to ESCs. Although ESCs, TSCs, and TSC-TBs are dramatically different in their growth rate, morphology, and physiological functions, they nevertheless share a similarity in being able to avoid TNF-α/IFN-γ cytotoxicity. We propose that this unique immune property may serve as a protective mechanism that limits cytokine cytotoxicity in the blastocyst. With molecular and cellular approaches and genome-wide transcriptomic analysis, we have demonstrated that the attenuated NF-κB and STAT1 transcription activation is a limiting factor that restricts the effect of TNF-α/IFN-γ on TSCs and TSC-TBs.

Comparison of maternal and neonatal survival exposed to humidifier disinfectants during perinatal periods: a case-series study

A humidifier disinfectant (HD) has been prohibited by the government due to its serious effects on the human body. Several studies on the relationship between HD and lung diseases have been performed independently on children and adults. However, there have been no reports on the effects of HD exposure on pregnant women and their foetuses. Therefore, the present study was conducted to investigate the effects of HD exposure on the foetuses of women who encountered HD during pregnancy. A total of 56 cases were recruited from 2017 to 2019 through the Korea Environmental Industry & Technology Institute, and data obtained from the medical records included maternal date of birth, maternal date of death, maternal start and end date of HD exposure, maternal date of symptom onset, neonatal birthday, neonatal birthweight, gestational age, and neonatal survival status within 28 days. All data were retrospectively investigated through medical records. Of the 47 mothers, 20 (42.6%) mothers survived, and 27 (57.4%) mothers died. In the group of survivors, there was a shorter period of total HD use, period of HD use before pregnancy and period of HD use to onset of symptoms. Shorter durations of HD use resulted in higher survival rate of mothers. HD use caused an increase in gestational age surviving foetuses, and foetal mortality increased when clinical symptoms developed before birth.

Central respiratory command and microglia: An early-life partnership

Microglia, brain-resident macrophages, are key players in brain development, regulating synapse density, shaping neural circuits, contributing to plasticity, and maintaining nervous tissue homeostasis. These functions are ensured from early prenatal development until maturity, in normal and pathological states of the central nervous system. Microglia dysfunction can be involved in several neurodevelopmental disorders, some of which are associated with respiratory deficits. Breathing is a rhythmic motor behavior generated and controlled by hindbrain neuronal networks. The operation of the central respiratory command relies on the proper development of these rhythmogenic networks, formation of their appropriate interactions, and their lifelong constant adaptation to physiological needs. This review, focusing exclusively on the perinatal period, outlines recent advances obtained in rodents in determining the roles of microglia in the establishment and functioning of the respiratory networks and their involvement in certain pathologies.

The fetal response to maternal inflammation is dependent upon maternal IL-6 in a murine model

BACKGROUND

The induction of maternal inflammation in mice leads to fetal injury that is believed to be IL-6 dependent. The fetal inflammatory response, defined by elevated fetal or amniotic fluid IL-6, has been described as a potential mechanism for subsequent fetal injury. The role of maternal IL-6 production and signaling in the fetal IL-6 response is currently unclear.

METHODS

Genetic and anti-IL-6 antibody strategies were used to systematically block the maternal IL-6 response during inflammation. Chorioamnionitis was induced using intraperitoneal injection of lipopolysaccharide (LPS) at mid gestation (E14.5) and late gestation (E18.5). This model was used in pregnant C57Bl/6 dams, IL6^-/- dams, C57Bl/6 dams treated with anti-IL-6 (blocks both classical and trans-signaling) or anti-gp130 antibodies (blocks trans-signaling only) and IL6^+/- dams. Six hours following LPS injection, maternal serum, placental tissue, amniotic fluid and fetal tissue or serum were collected. A bead-based multiplex assay was used to evaluate levels of IL-6, KC, IL-1β, TNF, IL-10, IL-22, IFN-γ, IL-13 and IL-17A.

RESULTS

Chorioamnionitis in C57Bl/6 dams was characterized by elevated maternal serum levels of IL-6, KC and IL-22 with litter loss during mid gestation. The fetal response to maternal inflammation in C57Bl/6 mice was primarily characterized by elevated levels of IL-6, KC and IL-22 in the placenta, amniotic fluid and fetus during both mid and late gestation. A global IL-6 knockout (IL6^-/-) eradicated the maternal, placental, amniotic fluid and fetal IL-6 response to LPS during mid and late gestation and improved litter survival, while minimally influencing the KC or IL-22 responses. Blocking maternal classical IL-6 signaling in C57Bl/6 dams at the time of LPS exposure diminished the maternal, placental, amniotic fluid and fetal IL-6 response during mid and late gestation, while blocking maternal IL-6 trans-signaling only affected fetal IL-6 expression. To evaluate whether maternal IL-6 was crossing the placenta and reaching the fetus, IL-6^+/- dams were utilized in the chorioamnionitis model. IL-6^+/- dams mounted a systemic inflammatory response following injection with LPS, characterized by elevated IL-6, KC and IL-22. IL-6^-/- pups born to IL6^+/- dams had decreased amniotic fluid levels of IL-6 and undetectable levels of fetal IL-6 compared to IL-6^+/+ littermate controls.

CONCLUSION

The fetal response to systemic maternal inflammation is dependent upon maternal IL-6 signaling, but maternal IL-6 is not crossing the placenta and reaching the fetus at detectable levels.

Maternal Neutrophil Depletion Fails to Avert Systemic Lipopolysaccharide-Induced Early Pregnancy Defects in Mice

Maternal infection-induced early pregnancy complications arise from perturbation of the immune environment at the uterine early blastocyst implantation site (EBIS), yet the underlying mechanisms remain unclear. Here, we demonstrated in a mouse model that the progression of normal pregnancy from days 4 to 6 induced steady migration of leukocytes away from the uterine decidual stromal zone (DSZ) that surrounds the implanted blastocyst. Uterine macrophages were found to be CD206⁺ M2-polarized. While monocytes were nearly absent in the DSZ, DSZ cells were found to express monocyte marker protein Ly6C. Systemic endotoxic lipopolysaccharide (LPS) exposure on day 5 of pregnancy led to: (1) rapid (at 2 h) induction of neutrophil chemoattractants that promoted huge neutrophil infiltrations at the EBISs by 24 h; (2) rapid (at 2 h) elevation of mRNA levels of MyD88, but not Trif, modulated cytokines at the EBISs; and (3) dose-dependent EBIS defects by day 7 of pregnancy. Yet, elimination of maternal neutrophils using anti-Ly6G antibody prior to LPS exposure failed to avert LPS-induced EBIS defects allowing us to suggest that activation of Tlr4-MyD88 dependent inflammatory pathway is involved in LPS-induced defects at EBISs. Thus, blocking the activation of the Tlr4-MyD88 signaling pathway may be an interesting approach to prevent infection-induced pathology at EBISs.

Dysbacteriosis induces abnormal neurogenesis via LPS in a pathway requiring NF-κB/IL-6

In this study, we identified elevated levels of LPS and suppressed neurogenesis in a successfully established mouse model of gut microbiota dysbiosis. We mimicked these phenotypes using mouse and chicken embryos exposed to LPS and found that dramatic variation in gene expression was due to changes in the dorsal-ventral patterning of the neural tube. Cell survival and excess ROS were also involved in this process. Antioxidant administration alleviated LPS-activated NF-κB signaling, while directly blocking NF-κB signaling altered the LPS-induced inhibition of neurogenesis. Furthermore, IL-6 was proven to play a vital role in the expression of crucial neurogenesis-related genes and NF-κB. In summary, we found that the suppression of neurogenesis induced by dysbacteriosis-derived LPS was significantly reversed in mice with fecal microbiota transplantation. This study reveals that gut dysbacteriosis-derived LPS impairs embryonic neurogenesis, and that the NF-κB/IL-6 pathway could be one of the main factors triggering the downstream signaling cascade.

Mid-gestation low-dose LPS administration results in female-specific excessive weight gain upon a western style diet in mouse offspring

Gestational complications, including preeclampsia and gestational diabetes, have long-term adverse consequences for offspring's metabolic and cardiovascular health. A low-grade systemic inflammatory response is likely mediating this. Here, we examine the consequences of LPS-induced gestational inflammation on offspring's health in adulthood. LPS was administered to pregnant C57Bl/6J mice on gestational day 10.5. Maternal plasma metabolomics showed oxidative stress, remaining for at least 5 days after LPS administration, likely mediating the consequences for the offspring. From weaning on, all offspring was fed a control diet; from 12 to 24 weeks of age, half of the offspring received a western-style diet (WSD). The combination of LPS-exposure and WSD resulted in hyperphagia and increased body weight and body fat mass in the female offspring. This was accompanied by changes in glucose tolerance, leptin and insulin levels and gene expression in liver and adipose tissue. In the hypothalamus, expression of genes involved in food intake regulation was slightly changed. We speculate that altered food intake behaviour is a result of dysregulation of hypothalamic signalling. Our results add to understanding of how maternal inflammation can mediate long-term health consequences for the offspring. This is relevant to many gestational complications with a pro-inflammatory reaction in place.

The effect of intrauterine inflammation on mTOR signaling in mouse fetal brain

Fetuses exposed to an inflammatory environment are predisposed to long-term adverse neurological outcomes. However, the mechanism by which intrauterine inflammation (IUI) is responsible for abnormal fetal brain development is not fully understood. The mechanistic target of rapamycin (mTOR) signaling pathway is closely associated with fetal brain development. We hypothesized that mTOR signaling might be involved in fetal brain injury and malformation when fetuses are exposed to the IUI environment. A well-established IUI model was utilized by intrauterine injection of lipopolysaccharide (LPS) to explore the effect of IUI on mTOR signaling in mouse fetal brains. We found that microglia activation in LPS fetal brains was increased, as demonstrated by elevated Iba-1 protein level and immunofluorescence density. LPS fetal brains also showed reduced neuronal cell counts, decreased cell proliferation demonstrated by low Ki67-positive density, and elevated neuron apoptosis evidenced by high expression of cleaved Caspase 3. Furthermore, we found that mTOR signaling in LPS fetal brains was elevated at 2 hr after LPS treatment, declined at 6 hr and showed overall inhibition at 24 hr. In summary, our study revealed that LPS-induced IUI leads to increased activation of microglia cells, neuronal damage, and dynamic alterations in mTOR signaling in the mouse fetal brain. Our findings indicate that abnormal changes in mTOR signaling may underlie the development of future neurological complications in offspring exposed to prenatal IUI.

Dysbacteriosis-induced LPS elevation disturbs the development of muscle progenitor cells by interfering with retinoic acid signaling

Whether myogenesis is affected by the maternal gut dysbacteriosis still remains ambiguous. In this study, first we show the elevated level of lipopolysaccharides (LPS) in a gut microbiota dysbiosis mouse model. Second, we demonstrate that the diameter of muscle fibers, limb development, and somitogenesis were inhibited in both the gut microbiota dysbiosis and LPS exposed mice and chicken embryos. These might be due to LPS disturbed the cell survival and key genes which regulate the somitogenesis and myogenesis. RNA sequencing and subsequent validation experiments verified that retinoic acid (RA) signaling perturbation was mainly responsible for the aberrant somite formation and differentiation. Subsequently, we found that LPS-induced reactive oxygen species (ROS generation and antioxidant genes such as Nrf2, AKR1B10) contributed to the above -mentioned interference with RA signaling. These findings highlight that the gut microbiota homeostasis is also involved in regulating the development of muscle progenitor cells during pregnancy.

Sustained maternal inflammation during the early third-trimester yields intrauterine growth restriction, impaired skeletal muscle glucose metabolism, and diminished β-cell function in fetal sheep1,2

Maternal inflammation causes fetal intrauterine growth restriction (IUGR), but its impact on fetal metabolism is not known. Thus, our objective was to determine the impact of sustained maternal inflammation in late gestation on fetal inflammation, skeletal muscle glucose metabolism, and insulin secretion. Pregnant ewes were injected every third day from the 100th to 112th day of gestation (term = 150 d) with saline (controls) or lipopolysaccharide (LPS) to induce maternal inflammation and IUGR (MI-IUGR). Fetal femoral blood vessels were catheterized on day 118 to assess β-cell function on day 123, hindlimb glucose metabolic rates on day 124, and daily blood parameters from days 120 to 125. Fetal muscle was isolated on day 125 to assess ex vivo glucose metabolism. Injection of LPS increased (P < 0.05) rectal temperatures, circulating white blood cells, and plasma tumor necrosis factor α (TNFα) concentrations in MI-IUGR ewes. Maternal leukocytes remained elevated (P < 0.05) and TNFα tended to remain elevated (P < 0.10) compared with controls almost 2 wk after the final LPS injection. Total white blood cells, monocytes, granulocytes, and TNFα were also greater (P < 0.05) in MI-IUGR fetuses than controls over this period. MI-IUGR fetuses had reduced (P < 0.05) blood O2 partial pressures and greater (P < 0.05) maternofetal O2 gradients, but blood glucose and maternofetal glucose gradients did not differ from controls. Basal and glucose-stimulated insulin secretion were reduced (P < 0.05) by 32% and 42%, respectively, in MI-IUGR fetuses. In vivo hindlimb glucose oxidation did not differ between groups under resting conditions but was 47% less (P < 0.05) in MI-IUGR fetuses than controls during hyperinsulinemia. Hindlimb glucose utilization did not differ between fetal groups. At day 125, MI-IUGR fetuses were 22% lighter (P < 0.05) than controls and tended to have greater (P < 0.10) brain/BW ratios. Ex vivo skeletal muscle glucose oxidation did not differ between groups in basal media but was less (P < 0.05) for MI-IUGR fetuses in insulin-spiked media. Glucose uptake rates and phosphorylated-to-total Akt ratios were less (P < 0.05) in muscle from MI-IUGR fetuses than controls regardless of media. We conclude that maternal inflammation leads to fetal inflammation, reduced β-cell function, and impaired skeletal muscle glucose metabolism that persists after maternal inflammation ceases. Moreover, fetal inflammation may represent a target for improving metabolic dysfunction in IUGR fetuses.

The tracking of lipopolysaccharide through the feto-maternal compartment and the involvement of maternal TLR4 in inflammation-induced fetal brain injury

Problem

Exposure to intrauterine inflammation (IUI) has been shown to induce fetal brain injury and increase the risk of acquiring a neurobehavioral disorder. The trafficking of the inflammatory mediator, lipopolysaccharide (LPS), in the pregnant female reproductive tract in the setting of IUI and the precise mechanisms by which inflammation induces fetal brain injury are not fully understood.

Method of study

FITC‐labeled LPS was utilized to induce IUI on E15, tissues were collected, and fluorescence was visualized via the Spectrum IVIS. Embryo transfer was utilized to create divergent maternal and fetal genotypes. Wild‐type (WT) embryos were transferred into TLR4−/− pseudopregnant dams (TLR4−/−_mat/WT_fet). On E15, TLR4−/−_mat/WT_fet dams or their WT controls (WT_mat/WT_fet) received an intrauterine injection of LPS or phosphate‐buffered saline (PBS). Endotoxin and IL‐6 levels were assessed in amniotic fluid, and cytokine expression was measured via QPCR.

Results

Lipopolysaccharide trafficked to the uterus, fetal membranes, placenta, and the fetus and was undetectable in other tissues. Endotoxin was present in the amniotic fluid of all animals exposed to LPS. However, the immune response was blunted in TLR4−/−_mat/WT_fet compared with WT controls.

Conclusion

Intrauterine administered LPS is capable of accessing the entire feto‐placental unit with or without a functional maternal TLR4. Thus, bacteria or bacterial byproducts in the uterus may negatively impact fetal development regardless of the maternal genotype or endotoxin response. Despite the blunted immune response in the TLR4‐deficient dams, an inflammatory response is still ignited in the amniotic cavity and may negatively impact the fetus.

IL‐6 protein expression in the amniotic fluid of WTmat/WTfet and TLR4‐/‐mat/WTfet Pregnant females were treated with an intrauterine dose of LPS (250 μg) or PBS on E15. LPS injection resulted in significantly increased IL‐6 protein in WT animals (*, P = 0.0017) compared to controls. LPS did not significantly elevate IL‐6 levels in the TLR4‐/‐mat/WTfet animals. The WTmat/WTfet dams had a significantly higher immune response compared to their TLR4‐/‐mat/WTfet counterparts (#, P = 0.015).

Perinatal Breathing Patterns and Survival in Mice Born Prematurely and at Term

Infants born prematurely, often associated with maternal infection, frequently exhibit breathing instabilities that require resuscitation. We hypothesized that breathing patterns during the first hour of life would be predictive of survival in an animal model of prematurity. Using plethysmography, we measured breathing patterns during the first hour after birth in mice born at term (Term 19.5), delivered prematurely on gestational day 18.5 following administration of low-dose lipopolysaccharide (LPS; 0.14 mg/kg) to pregnant dams (LPS 18.5), or delivered on gestational day 18.7 or 17.5 by caesarian section (C-S 18.5 and C-S 17.5, respectively). Our experimental approach allowed us to dissociate effects caused by inflammation, from effects due to premature birth in the absence of an inflammatory response. C-S 17.5 mice did not survive, whereas mortality was not increased in C-S 18.5 mice. However, in premature pups born at the same gestational age (day 18.5) in response to maternal LPS injection, mortality was significantly increased. Overall, mice that survived had higher birth weights and showed eupneic or gasping activity that was able to transition to normal breathing. Some mice also exhibited a “saw tooth” breathing pattern that was able to transition into eupnea during the first hour of life. In contrast, mice that did not survive showed distinct, large amplitude, long-lasting breaths that occurred at low frequency and did not transition into eupnea. This breathing pattern was only observed during the first hour of life and was more prevalent in LPS 18.5 and C-S 18.5 mice. Indeed, breath tidal volumes were higher in inflammation-induced premature pups than in pups delivered via C-section at equivalent gestational ages, whereas breathing frequencies were low in both LPS-induced and C-section-induced premature pups. We conclude that a breathing pattern characterized by low frequency and large tidal volume is a predictor for the failure to survive, and that these characteristics are more often seen when prematurity occurs in the context of maternal inflammation. Further insights into the mechanisms that generate these breathing patterns and how they transition to normal breathing may facilitate development of novel strategies to manage premature birth in humans.

Prenatal inflammation impairs intestinal microvascular development through a TNF-dependent mechanism and predisposes newborn mice to necrotizing enterocolitis

Prenatal inflammation is a risk factor for necrotizing enterocolitis (NEC), and it increases intestinal injury in a rat NEC model. We previously showed that maldevelopment of the intestinal microvasculature and lack of vascular endothelial growth factor (VEGF) receptor 2 (VEGFR2) signaling play a role in experimental NEC. However, whether prenatal inflammation affects the intestinal microvasculature remains unknown. In this study, mouse dams were injected intraperitoneally with lipopolysaccharide (LPS) or saline at embryonic day 17. Neonatal intestinal microvasculature density, endothelial cell proliferation, and intestinal VEGF-A and VEGFR2 proteins were assessed in vivo. Maternal and fetal serum TNF concentrations were measured by ELISA. The impact of TNF on the neonatal intestinal microvasculature was examined in vitro and in vivo, and we determined whether prenatal LPS injection exacerbates experimental NEC via TNF. Here we found that prenatal LPS injection significantly decreased intestinal microvascular density, endothelial cell proliferation, and VEGF and VEGFR2 protein expression in neonatal mice. Prenatal LPS injection increased maternal and fetal serum levels of TNF. TNF decreased VEGFR2 protein in vitro in neonatal endothelial cells. Postnatal TNF administration in vivo decreased intestinal microvasculature density, endothelial cell proliferation, and VEGF and VEGFR2 protein expression and increased the incidence of severe NEC. These effects were ameliorated by stabilizing hypoxia-inducible factor-1α, the master regulator of VEGF. Furthermore, prenatal LPS injection significantly increased the incidence of severe NEC in our model, and the effect was dependent on endogenous TNF. Our study suggests that prenatal inflammation increases the susceptibility to NEC, downregulates intestinal VEGFR2 signaling, and affects perinatal intestinal microvascular development via a TNF mechanism. NEW & NOTEWORTHY This report provides new evidence that maternal inflammation decreases neonatal intestinal VEGF receptor 2 signaling and endothelial cell proliferation, impairs intestinal microvascular development, and predisposes neonatal mouse pups to necrotizing enterocolitis (NEC) through inflammatory cytokines such as TNF. Our data suggest that alteration of intestinal microvascular development may be a key mechanism by which premature infants exposed to prenatal inflammation are at risk for NEC and preserving the VEGF/VEGF receptor 2 signaling pathway may help prevent NEC development.

Maternal inflammation at midgestation impairs subsequent fetal myoblast function and skeletal muscle growth in rats, resulting in intrauterine growth restriction at term

Maternal inflammation induces intrauterine growth restriction (MI-IUGR) of the fetus, which compromises metabolic health in human offspring and reduces value in livestock. The objective of this study was to determine the effect of maternal inflammation at midgestation on fetal skeletal muscle growth and myoblast profiles at term. Pregnant Sprague-Dawley rats were injected daily with bacterial endotoxin (MI-IUGR) or saline (controls) from the 9th to the 11th day of gestational age (dGA; term = 21 dGA). At necropsy on dGA 20, average fetal mass and upper hindlimb cross-sectional areas were reduced (P < 0.05) in MI-IUGR fetuses compared with controls. MyoD⁺ and myf5⁺ myoblasts were less abundant (P < 0.05), and myogenin⁺ myoblasts were more abundant (P < 0.05) in MI-IUGR hindlimb skeletal muscle compared with controls, indicating precocious myoblast differentiation. Type I and Type II hindlimb muscle fibers were smaller (P < 0.05) in MI-IUGR fetuses than in controls, but fiber type proportions did not differ between experimental groups. Fetal blood plasma TNFα concentrations were below detectable amounts in both experimental groups, but skeletal muscle gene expression for the cytokine receptors TNFR1, IL6R, and FN14 was greater (P < 0.05) in MI-IUGR fetuses than controls, perhaps indicating enhanced sensitivity to these cytokines. Maternal blood glucose concentrations at term did not differ between experimental groups, but MI-IUGR fetal blood contained less (P < 0.05) glucose, cholesterol, and triglycerides. Fetal-to-maternal blood glucose ratios were also reduced (P < 0.05), which is indicative of placental insufficiency. Indicators of protein catabolism, including blood plasma urea nitrogen and creatine kinase, were greater (P < 0.05) in MI-IUGR fetuses than in controls. From these findings, we conclude that maternal inflammation at midgestation causes muscle-centric fetal programming that impairs myoblast function, increases protein catabolism, and reduces skeletal muscle growth near term. Fetal muscle sensitivity to inflammatory cytokines appeared to be enhanced after maternal inflammation, which may represent a mechanistic target for improving these outcomes in MI-IUGR fetuses.

Activation of CCL20 and its receptor CCR6 promotes endometrium preparation for implantation and placenta development during the early pregnancy period in pigs

The success of implantation and placentation during early pregnancy depends on the intrauterine environment of diverse histotrophs, including nutrients, growth factors, cytokines, and chemokines. Here, we determined the functional role and signal transduction of CC-motif chemokine 20 (CCL20) in the porcine endometrium during pregnancy. The expression of CCL20 and its receptor CCR6 was abundant in the glandular epithelium (GE) and luminal epithelium (LE) of the porcine endometrium during early pregnancy. Administration of CCL20 to porcine endometrial LE cells increased cellular proliferation with strong PCNA expression by activation of PI3K and MAPK signaling. Blocking PI3K and MAPK decreased the CCL20-mediated elevated proliferation of pLE cells. Moreover, the proliferation of pLE cells was enhanced by inhibiting the LPS-induced cytokines and tunicamycin-induced endoplasmic reticulum (ER) stress response proteins. Overall, these results suggest that CCL20 may improve the endometrial receptivity through inducing proliferative signal transduction in the porcine endometrium during the early gestational period.

A double-hit pre-eclampsia model results in sex-specific growth restriction patterns

Pre-eclampsia is a multifactorial pregnancy-associated disorder characterized by angiogenic dysbalance and systemic inflammation; however, animal models that combine these two pathophysiological conditions are missing. Here, we introduce a novel double-hit pre-eclampsia mouse model that mimics the complex multifactorial conditions present during pre-eclampsia and allows for the investigation of early consequences for the fetus. Adenoviral overexpression of soluble fms-like tyrosine kinase (sFlt-1) and lipopolysaccharide (LPS) administration at mid-gestation in pregnant mice resulted in hypertension and albuminuria comparable to that of the manifestation in humans. A metabolomics analysis revealed that pre-eclamptic dams have increased plasma concentrations of phosphadytilcholines. The fetuses of both sexes were growth restricted; however, in males a brain-sparing effect was seen as compensation for this growth restriction. According to the plasma metabolomics, male fetuses showed changes in amino acid metabolism, while female fetuses showed pronounced alterations in lipid metabolism. Our results show that combined exposure to sFlt-1 and LPS mimics the clinical symptoms of pre-eclampsia and affects fetal growth in a sex-specific manner, with accompanying metabolome changes.

The underdeveloped innate immunity in embryonic stem cells: The molecular basis and biological perspectives from early embryogenesis

Embryonic stem cells (ESCs) have been intensively studied as a promising cell source for regenerative medicine. The rapid advancements in the field have not only proven the feasibility of ESC-based cell therapy, but also led to a better understanding of pluripotent stem cells (PSCs) as a unique cell population at an early stage of embryogenesis. Recent studies have revealed that both human and mouse ESCs have attenuated innate immune responses to infectious agents and inflammatory cytokines. These findings raise interesting questions about the rationale for ESCs, the PSCs experimentally derived from preimplantation stage embryos, to not have an innate defense mechanism that has been adapted so well in somatic cells. All somatic cells have innate immune systems that can be activated by pathogen-associated molecular patterns (PAMPs) or cellular damage-associated molecular patterns (DAMPs), leading to production of cytokines. The underdeveloped innate immunity represents a unique property of PSCs that may have important implications. This review discusses the immunological properties of PSCs, the molecular basis underlying their diminished innate immune responses, and the hypothesis that the attenuated innate immune responses could be an adaptive mechanism that allows PSCs to avoid cytotoxicity associated with inflammation and immune responses during early embryogenesis.

Prenatal Programming of Neuroendocrine System Development by Lipopolysaccharide: Long-Term Effects

Various stress factors during critical periods of fetal development modulate the epigenetic mechanisms controlling specific genes, which can affect the structure and function of physiological systems. Maternal immune stress by bacterial infection simulated by lipopolysaccharide (LPS) in an experiment is considered to be a powerful programming factor of fetal development. Studies of the molecular mechanisms controlling the formation and functioning of physiological systems are in the pilot stage. LPSs are the most potent natural inflammation factors. LPS-induced increases in fetal levels of pro- and anti-inflammatory cytokines can affect brain development and have long-term effects on behavior and neuroendocrine functions. The degradation of serotonergic neurons induced by LPS in the fetus is attributed to the increased levels of interleukin (IL)-6 and tumor necrosis factor (TNFα) as well as to anxiety and depression in children. Dopamine deficiency causes dysthymia, learning disability, and Parkinson’s disease. According to our data, an LPS-induced increase in the levels of IL-6, leukemia inhibitory factor (LIF), and monocyte chemotactic protein (MCP-1) in maternal and fetal rats during early pregnancy disturbs the development and functioning of gonadotropin-releasing hormone production and reproductive systems. It is important to note the high responsiveness of epigenetic developmental mechanisms to many regulatory factors, which offers opportunities to correct the defects.

Microbiota-derived lipopolysaccharide retards chondrocyte hypertrophy in the growth plate through elevating Sox9 expression

Accumulating data show that the cytotoxicity of bacterial lipopolysaccharides (LPS) from microbiota or infection is associated with many disorders observed in the clinics. However, it is still obscure whether or not embryonic osteogenesis is affected by the LPS exposure during gestation. Using the early chicken embryo model, we could demonstrate that LPS exposure inhibits chondrogenesis of the 8-day chicken embryos by Alcian Blue-staining and osteogenesis of 17-day by Alcian Blue and Alizarin Red staining. Further analysis of the growth plates showed that the length of the proliferating zone (PZ) increases whereas that of the hypertrophic zone (HZ) decreased following LPS exposure. However there is no significant change on cell proliferation in the growth plates. Immunofluorescent staining, western blot analysis, and quantitive polymerase chain reaction revealed that Sox9 and Col2a1 are highly expressed at the messenger RNA level and their protein products are also abundant. LPS exposure causes a downregulation of Runx2 and Col10a1 expression in 8-day hindlimbs, and a suppression of Runx2, Col10a1, and Vegfa expression in 17-day phalanges. Knocking down Sox9 in ATDC5 cells by small interfering RNA transfection lead to the expression reduction of Col2a1, Runx2, and Col10a1, implying the vital role of Sox9 in the process of LPS-induced delay in the transition from proliferating chondrocytes to hypertrophic chondrocytes in the growth plate. In the presence of LPS, the antioxidant defense regulator nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is highly expressed, and the activities of superoxide dismutase 1 (SOD1), SOD2, and glutaredoxin rise in 17-day phalanges and ADTC5 cells. Simultaneously, an increase of intracellular ROS is observed. When Nrf2 expression was knocked down in ATDC5 cells, the expressions of Sox9, Col2a1, Runx2, Col10a1, and Vegfa were also going down as well. Taken together, our current data suggest that LPS exposure during gestation could restrict the chondrocytes conversion from proliferating to hypertrophic in the growth plate, in which LPS-induced Sox9 plays a crucial role to trigger the cascade of downstream genes by excessive ROS production and Nrf2 elevation.

HIV-Exposed Uninfected Infants in Zimbabwe: Insights into Health Outcomes in the Pre-Antiretroviral Therapy Era

The ZVITAMBO trial recruited 14,110 mother-infant pairs to a randomized controlled trial of vitamin A between 1997 and 2000, before the availability of antiretroviral therapy for HIV prophylaxis or treatment in Zimbabwe. The HIV status of mothers and infants was well characterized through 1-2 years of follow-up, leading to the largest cohort to date of HIV-exposed uninfected (HEU) infants (n = 3135), with a suitable comparison group of HIV-unexposed infants (n = 9510). Here, we draw on 10 years of published findings from the ZVITAMBO trial. HEU infants had increased morbidity compared to HIV-unexposed infants, with 50% more hospitalizations in the neonatal period and 30% more sick clinic visits during infancy, particularly for skin infections, lower respiratory tract infections, and oral thrush. HEU children had 3.9-fold and 2.0-fold higher mortality than HIV-unexposed children during the first and second years of life, respectively, most commonly due to acute respiratory infections, diarrhea/dysentery, malnutrition, sepsis, and meningitis. Infant morbidity and mortality were strongly related to maternal HIV disease severity, and increased morbidity remained until maternal CD4 counts were >800 cells/μL. HEU infants were more likely to be premature and small-for-gestational age than HIV-unexposed infants, and had more postnatal growth failure. Here, we propose a conceptual framework to explain the increased risk of infectious morbidity, mortality, and growth failure among HEU infants, hypothesizing that immune activation and inflammation are key drivers of both infection susceptibility and growth failure. Future studies should further dissect the causes of infection susceptibility and growth failure and determine the impact of ART and cotrimoxazole on outcomes of this vulnerable group of infants in the current era.

Considerations for the Optimization of Induced White Matter Injury Preclinical Models

White matter (WM) injury in relation to acute neurologic conditions, especially stroke, has remained obscure until recently. Current advances in imaging technologies in the field of stroke have confirmed that WM injury plays an important role in the prognosis of stroke and suggest that WM protection is essential for functional recovery and post-stroke rehabilitation. However, due to the lack of a reproducible animal model of WM injury, the pathophysiology and mechanisms of this injury are not well studied. Moreover, producing selective WM injury in animals, especially in rodents, has proven to be challenging. Problems associated with inducing selective WM ischemic injury in the rodent derive from differences in the architecture of the brain, most particularly, the ratio of WM to gray matter in rodents compared to humans, the agents used to induce the injury, and the location of the injury. Aging, gender differences, and comorbidities further add to this complexity. This review provides a brief account of the techniques commonly used to induce general WM injury in animal models (stroke and non-stroke related) and highlights relevance, optimization issues, and translational potentials associated with this particular form of injury.

Maternal immune activation evoked by polyinosinic:polycytidylic acid does not evoke microglial cell activation in the embryo

Several studies have indicated that inflammation during pregnancy increases the risk for the development of neuropsychiatric disorders in the offspring. Morphological brain abnormalities combined with deviations in the inflammatory status of the brain can be observed in patients of both autism and schizophrenia. It was shown that acute infection can induce changes in maternal cytokine levels which in turn are suggested to affect fetal brain development and increase the risk on the development of neuropsychiatric disorders in the offspring. Animal models of maternal immune activation reproduce the etiology of neurodevelopmental disorders such as schizophrenia and autism. In this study the poly (I:C) model was used to mimic viral immune activation in pregnant mice in order to assess the activation status of fetal microglia in these developmental disorders. Because microglia are the resident immune cells of the brain they were expected to be activated due to the inflammatory stimulus. Microglial cell density and activation level in the fetal cortex and hippocampus were determined. Despite the presence of a systemic inflammation in the pregnant mice, there was no significant difference in fetal microglial cell density or immunohistochemically determined activation level between the control and inflammation group. These data indicate that activation of the fetal microglial cells is not likely to be responsible for the inflammation induced deficits in the offspring in this model.

Specific Lipopolysaccharide Serotypes Induce Differential Maternal and Neonatal Inflammatory Responses in a Murine Model of Preterm Labor

Intrauterine inflammation is recognized as a key mediator of both normal and preterm birth but is also associated with neonatal neurological injury. Lipopolysaccharide (LPS) is often used to stimulate inflammatory pathways in animal models of infection/inflammation-induced preterm labor; however, inconsistencies in maternal and neonatal responses to LPS are frequently reported. We hypothesized that LPS serotype-specific responses may account for a portion of these inconsistencies. Four different Escherichia coli LPS serotypes (O111:B4, O55:B5, O127:B8, and O128:B12) were administered to CD1 mice via intrauterine injection at gestational day 16. Although control animals delivered at term 60 ± 15 hours postinjection (p.i.), those administered with O111:B4 delivered 7 ± 2 hours p.i., O55:B5 delivered 10 ± 3 hours p.i., O127:B8 delivered 16 ± 10 hours p.i., and O128:B12 delivered 17 ± 2 hours p.i. (means ± SD). A correlation between the onset of preterm labor and myometrial activation of the inflammatory transcription factor, activator protein 1, but not NF-κB was observed. Specific LPS serotypes induced differential activation of downstream contractile and inflammatory pathways in myometrium and neonatal pup brain. Our findings demonstrate functional disparity in inflammatory pathway activation in response to differing LPS serotypes. Selective use of LPS serotypes may represent a useful tool for targeting specific inflammatory response mechanisms in these models.

Alkaline phosphatase protects lipopolysaccharide-induced early pregnancy defects in mice

Excessive cytokine inflammatory response due to chronic or superphysiological level of microbial infection during pregnancy leads to pregnancy complications such as early pregnancy defects/loss and preterm birth. Bacterial toxin lipopolysaccharide (LPS), long recognized as a potent proinflammatory mediator, has been identified as a risk factor for pregnancy complications. Alkaline phosphatase (AP) isozymes have been shown to detoxify LPS by dephosphorylation. In this study, we examined the role of alkaline phosphatase (AP) in mitigating LPS-induced early pregnancy complications in mice. We found that 1) the uterus prior to implantation and implantation sites following embryo implantation produce LPS recognition and dephosphorylation molecules TLR4 and tissue non-specific AP (TNAP) isozyme, respectively; 2) uterine TNAP isozyme dephosphorylates LPS at its sites of production; 3) while LPS administration following embryo implantation elicits proinflammatory cytokine mRNA levels at the embryo implantation sites (EISs) and causes early pregnancy loss, dephosphorylated LPS neither triggers proinflammatory cytokine mRNA levels at the EISs nor induces pregnancy complications; 4) AP isozyme supplementation to accelerate LPS detoxification attenuates LPS-induced pregnancy complications following embryo implantation. These findings suggest that a LPS dephosphorylation strategy using AP isozyme may have a unique therapeutic potential to mitigate LPS- or Gram-negative bacteria-induced pregnancy complications in at-risk women.

Effects of subcutaneous LPS injection on gestational length and intrauterine and neonatal mortality in mice

BACKGROUND

Infection during pregnancy can predispose offspring to develop various psychiatric disorders such as depression in later life. In order to investigate the potential mechanisms underlying these associations, animal models of maternal infection have been employed. As such, lipopolysaccharide (LPS) has been commonly used to mimic a bacterial infection in pregnant mice.

OBJECTIVE

The original aim of our study was to investigate the effects of different doses of subcutaneous LPS administration on affective behavior in adult mouse offspring. In the present paper, however, we report that subcutaneous LPS administration has a profound impact on gestational length, litter size, and perinatal mortality in the offspring, even at a relatively low dose.

METHODS

Pregnant mice were randomly divided into 3 groups, receiving either a high (2 mg/kg) or a low (0.5 mg/kg) dose of LPS or phosphate-buffered saline by means of subcutaneous injection. Subsequently, the effects on gestational length, litter size, and perinatal mortality in the offspring were assessed.

RESULTS

After subcutaneous injection with a high dose of LPS, we observed a significant decrease in gestational length and an increase in neonatal mortality. When the low dose was administered, a tendency towards a reduced litter size was observed, most likely reflecting increased intrauterine mortality in response to prenatal maternal LPS exposure.

CONCLUSIONS

We showed that subcutaneous administration of 2 mg/kg LPS to pregnant mice in the last phase of gestation should be avoided because of high offspring mortality rates, whereas subcutaneous injection of 0.5 mg/kg LPS seems to result in reabsorption of the fetuses.

Lipopolysaccharide-induced maternal inflammation affects the gonadotropin-releasing hormone neuron development in fetal mice

Recent studies provide evidence that prenatal immunological stress may affect the programming of reproductive health and sexual behavior in adult animals. The aim of this study was to investigate the influence of maternal inflammation, induced by an intraperitoneal (i.p.) injection of lipopolysaccharide (LPS, 45 µg/kg) on embryonic day 11.5 (E 11.5), on the development of the gonadotropin-releasing hormone (GnRH) system in mouse fetuses as well as on the proinflammatory cytokine level in pregnant mice and their fetuses. In the fetuses, the GnRH neuron migration from the olfactory pit to the forebrain was estimated on embryonic days 14.5 and 18.5. The levels of the proinflammatory cytokines interleukin (IL)-6, monocyte chemotactic protein (MCP)-1, tumor necrosis factor (TNF)-α and leukemia inhibitory factor (LIF) were measured with the cytometric bead and ELISA array method in the maternal and fetal blood, amniotic fluid and fetal cerebrospinal fluid (CSF). According to our data, activation of the immune system by LPS treatment on embryonic day 11.5 leads to an increased quantity of neurons in the nasal and olfactory bulb areas and a decreased quantity in the forebrain area on embryonic day 14.5. There was a slight decrease in the total number of neurons in the forebrain area on embryonic day 18.5. The levels of proinflammatory cytokines were significantly increased within 3 h after LPS treatment in the maternal and fetal blood, amniotic fluid and fetal CSF. IL-6-receptor immunoreactivity was detected on olfactory/vomeronasal axons. Thus, prenatal immunological stress delays the GnRH neuron migration in the nasal compartment of mouse fetuses, which may be mediated by the regulation of IL-6, MCP-1 and LIF secretion in the maternal-fetal system.

Lipopolysaccharide exposure during pregnancy leads to aortic dysfunction in offspring rats

BACKGROUND

Prenatal exposure to Lipopolysaccharide (LPS) produces hypertension in adult offspring rats. The present study was to explore the effects of prenatal inflammation on morphological and functional changes in the aorta from offspring rats and to further assess its susceptibility to cardiovascular diseases.

METHODS AND RESULTS

Pregnant rats were treated intraperitoneally on gestation Days 8, 10 and 12 with saline, LPS (0.79 mg/kg), or pyrrolidine dithiocarbamate (PDTC, 100 mg/kg)+LPS, respectively. Aortic ring reactivity and histopathological alteration were analyzed in offspring at the age of 12 weeks. The detections of connexin (Cx) 37, Cx40, Cx43, and Cx45, including immunofluorescent patterns, protein levels and mRNA expression in the aorta, were performed as well. Furthermore, the expressions of Nuclear factor (NF)-κB (p65), IκBα, phospho-IκBα and IκBβ were determined. The results showed that prenatal LPS exposure leads to morphological abnormalities and impaired aortic reactivity in offspring. Prenatal LPS exposure also decreased the protein and mRNA expression of Cx37 in the aorta from offspring rats. NF-κB and phospho-IκBα levels were both increased, IκBα level, however, was decreased in the aorta of offspring from the maternal LPS exposure compared to the controls. Simultaneously, PDTC treatment markedly reversed the action of LPS.

CONCLUSIONS

Decreased expression of Cx37 contributed to the aortic dysfunction of prenatal LPS exposure offspring, which should be associated with NF-κB activation.

Prenatal exposure to lipopolysaccharide combined with pre- and postnatal high-fat diet result in lowered blood pressure and insulin resistance in offspring rats

Background

Adult metabolic syndrome may in part have origins in fetal or early life. This study was designed to explore the effect of prenatal exposure to lipopolysaccharide and high-fat diet on metabolic syndrome in offspring rats.

Methods

32 pregnant rats were randomly divided into four groups, including Control group; LPS group (pregnant rats were injected with LPS 0.4 mg/kg intraperitoneally on the 8^th, 10^th and 12^th day of pregnancy); High-fat group (maternal rats had high-fat diet during pregnancy and lactation period, and their pups also had high-fat diet up to the third month of life); LPS + High-fat group (rats were exposed to the identical experimental scheme with LPS group and High-fat group).

Results

Blood pressure elevated in LPS group and High-fat group, reduced in LPS+High-fat group, accompanied by the increase of serum leptin level in LPS and High-fat group and increase of serum IL-6, TNF-a in High-fat group; both serum insulin and cholesterol increased in High-fat and LPS+High-fat group, as well as insulin in LPS group. HOMA-IR value increased in LPS, High-fat and LPS+High-fat group, and QUICKI decreased in these groups; H-E staining showed morphologically pathological changes in thoracic aorta and liver tissue in the three groups. Increased serum alanine and aspartate aminotransferase suggest impaired liver function in LPS+High-fat group.

Conclusion/Significance

Prenatal exposure to lipopolysaccharide combined with pre- and postnatal high-fat diet result in lowered blood pressure, insulin resistance and impaired liver function in three-month old offspring rats. The lowered blood pressure might benefit from the predictive adaptive response to prenatal inflammation.

Inflammatory response and oxidative stress in developing rat brain and its consequences on motor behavior following maternal administration of LPS and perinatal anoxia

Cerebral palsy (CP) is a disorder of locomotion, posture and movement that can be caused by prenatal, perinatal or postnatal insults during brain development. An increased incidence of CP has been correlated to perinatal asphyxia and maternal infections during gestation. The effects of maternal exposure to low doses of bacterial endotoxin (lipopolysaccharide, LPS) associated or not with perinatal anoxia (PA) in oxidative and inflammatory parameters were examined in cerebral cortices of newborns pups. Concentrations of TNF-α, IL-1, IL-4, SOD, CAT and DCF were measured by the ELISA method. Other newborn rats were assessed for neonatal developmental milestones from day 1 to 21. Motor behavior was also tested at P29 using open-field and Rotarod. PA alone only increased IL-1 expression in cerebral cortex with no changes in oxidative measures. PA also induced a slight impact on development and motor performance. LPS alone was not able to delay motor development but resulted in changes in motor activity and coordination with increased levels of IL-1 and TNF-α expression associated with a high production of free radicals and elevated SOD activity. When LPS and PA were combined, changes on inflammatory and oxidative stress parameters were greater. In addition, greater motor development and coordination impairments were observed. Prenatal exposure of pups to LPS appeared to sensitize the developing brain to effects of a subsequent anoxia insult resulting in an increased expression of pro-inflammatory cytokines and increased free radical levels in the cerebral cortex. These outcomes suggest that oxidative and inflammatory parameters in the cerebral cortex are implicated in motor deficits following maternal infection and perinatal anoxia by acting in a synergistic manner during a critical period of development of the nervous system.

Protective effects of pentoxifylline on lipopolysaccharide-induced white matter injury in a rat model of periventricular leukomalasia

OBJECTIVE

To investigate the potential neuroprotective effect of maternal pentoxifylline (PNTX) treatment in endotoxin-induced periventricular leukomalasia (PVL) in the developing rat brain.

METHOD

Intraperitoneal injection of lipopolysaccharide was administered on two of three Wistar pregnant rats to establish PVL. To obtain PNTX-treated group, one of the two dams were injected with PNTX. The control group was treated with saline. Rat pups were grouped as control, maternal LPS-treated group and PNTX + LPS-treated group. At 7th postnatal days, apoptosis and hypomyelination were evaluated. Apoptosis was evaluated by caspase-3 and terminal deoxynucleotidyl transferase [TdT] dUTP nick endlabelling reaction (TUNEL) immunostaining. To assess hypomyelination, myelin basic protein (MBP) staining, as a marker of myelination, was evaluated.

RESULTS

MBP staining was significantly less and weaker in the brains of the LPS-treated group as compared with the PNTX-treated group. PNTX treatment significantly reduced the number of apoptotic cells in the periventricular WM shown on Tunel and caspase-3.

CONCLUSIONS

Presented study is first indicated that PNTX may provide protection against an LPS-induced inflammatory response and WMI in the developing rat brain. Our results also suggest that PNTX treatment in pregnant women with maternal or placental infection may minimize the risk of PVL and cerebral palsy.

The consequences of chorioamnionitis: preterm birth and effects on development

Preterm birth is a major cause of perinatal mortality and long-term morbidity. Chorioamnionitis is a common cause of preterm birth. Clinical chorioamnionitis, characterised by maternal fever, leukocytosis, tachycardia, uterine tenderness, and preterm rupture of membranes, is less common than subclinical/histologic chorioamnionitis, which is asymptomatic and defined by inflammation of the chorion, amnion, and placenta. Chorioamnionitis is often associated with a fetal inflammatory response. The fetal inflammatory response syndrome (FIRS) is defined by increased systemic inflammatory cytokine concentrations, funisitis, and fetal vasculitis. Clinical and epidemiological studies have demonstrated that FIRS leads to poor cardiorespiratory, neurological, and renal outcomes. These observations are further supported by experimental studies that have improved our understanding of the mechanisms responsible for these outcomes. This paper outlines clinical and experimental studies that have improved our current understanding of the mechanisms responsible for chorioamnionitis-induced preterm birth and explores the cellular and physiological mechanisms underlying poor cardiorespiratory, neural, retinal, and renal outcomes observed in preterm infants exposed to chorioamnionitis.

Placental-mediated increased cytokine response to lipopolysaccharides: a potential mechanism for enhanced inflammation susceptibility of the preterm fetus

BACKGROUND

Cerebral palsy is a nonprogressive motor impairment syndrome that has no effective cure. The etiology of most cases of cerebral palsy remains unknown; however, recent epidemiologic data have demonstrated an association between fetal neurologic injury and infection/inflammation. Maternal infection/inflammation may be associated with the induction of placental cytokines that could result in increased fetal proinflammatory cytokine exposure, and development of neonatal neurologic injury. Therefore, we sought to explore the mechanism by which maternal infection may produce a placental inflammatory response. We specifically examined rat placental cytokine production and activation of the Toll-like receptor 4 (TLR4) pathway in response to lipopolysaccharide exposure at preterm and near-term gestational ages.

METHODS

Preterm (e16) or near-term (e20) placental explants from pregnant rats were treated with 0, 1, or 10 μg/mL lipopolysaccharide. Explant integrity was assessed by lactate dehydrogenase assay. Interleukin-6 and tumor necrosis alpha levels were determined using enzyme-linked immunosorbent assay kits. TLR4 and phosphorylated nuclear factor kappa light chain enhancer of activated B cells (NFκB) protein expression levels were determined by Western blot analysis.

RESULTS

At both e16 and e20, lactate dehydrogenase levels were unchanged by treatment with lipopolysaccharide. After exposure to lipopolysaccharide, the release of interleukin-6 and tumor necrosis alpha from e16 placental explants increased by 4-fold and 8-9-fold, respectively (P < 0.05 versus vehicle). Conversely, interleukin-6 release from e20 explants was not significantly different compared with vehicle, and tumor necrosis alpha release was only 2-fold higher (P < 0.05 versus vehicle) following exposure to lipopolysaccharide. Phosphorylated NFκB protein expression was significantly increased in the nuclear fraction from placental explants exposed to lipopolysaccharide at both e16 and e20, although TLR4 protein expression was unaffected.

CONCLUSION

Lipopolysaccharide induces higher interleukin-6 and tumor necrosis alpha expression at e16 versus e20, suggesting that preterm placentas may have a greater placental cytokine response to lipopolysaccharide infection. Furthermore, increased phosphorylated NFκB indicates that placental cytokine induction may occur by activation of the TLR4 pathway.

Prenatal inflammation exacerbates hyperoxia-induced functional and structural changes in adult mice

Maternally derived inflammatory mediators, such as IL-6 and IL-8, contribute to preterm delivery, low birth weight, and respiratory insufficiency, which are routinely treated with oxygen. Premature infants are at risk for developing adult-onset cardiac, metabolic, and pulmonary diseases. Long-term pulmonary consequences of perinatal inflammation are unclear. We tested the hypothesis that a hostile perinatal environment induces profibrotic pathways resulting in pulmonary fibrosis, including persistently altered lung structure and function. Pregnant C3H/HeN mice injected with LPS or saline on embryonic day 16. Offspring were placed in room air (RA) or 85% O(2) for 14 days and then returned to RA. Pulmonary function tests, microCTs, molecular and histological analyses were performed between embryonic day 18 and 8 wk. Alveolarization was most compromised in LPS/O(2)-exposed offspring. Collagen staining and protein levels were increased, and static compliance was decreased only in LPS/O(2)-exposed mice. Three-dimensional microCT reconstruction and quantification revealed increased tissue densities only in LPS/O(2) mice. Diffuse interstitial fibrosis was associated with decreased micro-RNA-29, increased transforming growth factor-β expression, and phosphorylation of Smad2 during embryonic or early fetal lung development. Systemic maternal LPS administration in combination with neonatal hyperoxic exposure induces activation of profibrotic pathways, impaired alveolarization, and diminished lung function that are associated with prenatal and postnatal suppression of miR-29 expression.

Inflammatory-induced hibernation in the fetus: priming of fetal sheep metabolism correlates with developmental brain injury

Prenatal inflammation is considered an important factor contributing to preterm birth and neonatal mortality and morbidity. The impact of prenatal inflammation on fetal bioenergetic status and the correlation of specific metabolites to inflammatory-induced developmental brain injury are unknown. We used a global metabolomics approach to examine plasma metabolites differentially regulated by intrauterine inflammation. Preterm-equivalent sheep fetuses were randomized to i.v. bolus infusion of either saline-vehicle or LPS. Blood samples were collected at baseline 2 h, 6 h and daily up to 10 days for metabolite quantification. Animals were killed at 10 days after LPS injection, and brain injury was assessed by histopathology. We detected both acute and delayed effects of LPS on fetal metabolism, with a long-term down-regulation of fetal energy metabolism. Within the first 3 days after LPS, 121 metabolites were up-regulated or down-regulated. A transient phase (4–6 days), in which metabolite levels recovered to baseline, was followed by a second phase marked by an opposing down-regulation of energy metabolites, increased pO₂ and increased markers of inflammation and ADMA. The characteristics of the metabolite response to LPS in these two phases, defined as 2 h to 2 days and at 6–9 days, respectively, were strongly correlated with white and grey matter volumes at 10 days recovery. Based on these results we propose a novel concept of inflammatory-induced hibernation of the fetus. Inflammatory priming of fetal metabolism correlated with measures of brain injury, suggesting potential for future biomarker research and the identification of therapeutic targets.

Prophylactic maternal n-acetylcysteine before lipopolysaccharide suppresses fetal inflammatory cytokine responses

OBJECTIVE

Maternal infection or inflammation may induce fetal inflammatory responses and potentially fetal brain injury. We sought to determine whether prophylactic n-acetylcysteine (NAC), a known antiinflammatory, may modulate the fetal cytokine response to maternal lipopolysaccharide (LPS).

STUDY DESIGN

Pregnant Sprague Dawley rats (20/21 days = 0.95 gestation; n = 35) received intraperitoneal NAC (300 mg/kg) or saline at time 0 and LPS (500 microg/kg) or saline at 30 minutes. An additional group received NAC following saline. At 6 hours, rats were killed and interleukin (IL)-6, IL-1 beta, and IL-10 levels were determined in fetal and maternal blood.

RESULTS

Following maternal LPS, fetal blood IL-6 (median [25th, 75th] 50 [27, 50] to 2072 [448, 4853] pg/mL) and IL-1 beta (74 [10, 139] to 391 [284, 797] pg/mL) significantly increased. NAC before LPS significantly reduced the fetal IL-6 and IL-1 beta response. Fetal IL-10 was not attenuated by any treatment. NAC attenuated both maternal pro- and antiinflammatory responses to LPS.

CONCLUSION

Maternal NAC suppressed fetal and maternal inflammatory responses to maternal LPS. These results suggest that prophylactic NAC may protect the fetus from maternal inflammation.

Maternal exposure to endotoxin delays alveolarization during postnatal rat lung development

Maternal bacterial infections adversely affect lung development by crossing the placental barrier and infecting the developing fetus. The underlying mechanism negatively affecting pulmonary development remains unknown. Herein, we investigated whether a systemic maternal infection affects postnatal inflammation and alveolar development. Pregnant rats were injected with 2.5 mg/kg LPS on day 20 and 21 (term = 22 days). Postnatal (PN0-21) mRNA and protein expression of cytokines (IL-1beta, IL-6, IL-10, CXCL1/2, TNFalpha) and genes implicated in alveologenesis [tropoelastin, lysyl oxidase (LOX), lysyl oxidase-like (LOXL)1, tenascin-C (TNC), fibulin 5, vascular endothelial growth factor (VEGF-A), VEGF receptor (VEGFR)2, VEGFR1, platelet-derived growth factor (PDGF)A, PDGFB, and PDGFRalpha] were quantified by real-time PCR and beadlyte technology. Lung transcript and protein levels of IL-1beta, IL-6, and CXCL1/2 were significantly greater in LPS-exposed pups than those of control pups at PN0, 2, 6, 10, and 14. Bronchoalveolar lavage fluid (BALF) of LPS-exposed animals contained significantly more macrophages at PN2 and 14 than BALF of control pups. Morphometric analysis revealed that LPS-exposed animals had fewer and larger alveoli, fewer secondary septa, and decreased peripheral vessel density when compared with control pups. This morphological delay in alveolar development disappeared after PN14. Tropoelastin, LOXL1, VEGF, VEGFR2, and PDGFRalpha mRNA expression of LPS-exposed animals was significantly greater than those of control animals in PN2-14 lungs. TNC, LOX, fibulin 5, VEGFR1, PDGFA, and PDGFB expression was not affected by maternal LPS exposure. Together, the data demonstrate that maternal exposure to endotoxin results in a prolonged pulmonary inflammation postnatally, altered gene expression of molecules implicated in alveologenesis, and delayed morphological maturation of the lung.

Tumor necrosis factor alpha partially contributes to lipopolysaccharide-induced downregulation of CYP3A in fetal liver: its repression by a low dose LPS pretreatment

With embryonic development, fetal hepatocytes gradually express various types of cytochromes P450 (CYPs) that play a key role in the detoxification of xenobiotics. In the present study, we showed that maternal lipopolysaccharide (LPS) exposure downregulated cyp3a11 mRNA and CYP3A protein in fetal liver. The increased level of TNF-alpha protein in fetal liver, transferred from either the maternal circulation or amniotic fluid, seems to be associated with LPS-induced downregulation of cyp3a11 mRNA and CYP3A protein in fetal liver. Interestingly, a low dose LPS (10mug/kg) pretreatment attenuated LPS-induced downregulation of cyp3a11 mRNA and CYP3A protein in fetal liver. Correspondingly, a low dose LPS pretreatment attenuated LPS-induced downregulation of pregnane X receptor (pxr) in fetal liver. Additional experiment showed that a low dose LPS pretreatment decreased the level of TNF-alpha in maternal serum and amniotic fluid and counteracted LPS-induced expression of TNF-alpha mRNA in maternal liver and placenta. Although a low dose LPS pretreatment alleviated LPS-induced increase in TNF-alpha in fetal liver, it had little effect on TNF-alpha mRNA in fetal liver. These results suggest that a low dose LPS pretreatment protects fetuses against LPS-induced downregulation of hepatic cyp3a11 and pxr expression through the repression of maternally sourced TNF-alpha production.

Maternal endotoxin-induced preterm birth in mice: fetal responses in toll-like receptors, collectins, and cytokines

Major cause of prematurity is spontaneous preterm birth (PTB) associated with intrauterine inflammation. Our aim was to establish a model of endotoxin Lipopolysaccharide-induced PTB of live-born pups and to study early immune activation in fetal and maternal compartments. Expression of several proteins that bind microbes (Toll-like receptors TLR4, TLR2; surfactant proteins SP-A, SP-D) was analyzed. At 16 or 17 d of gestation, C57BL/6 dams received a single dose of intraperitoneal LPS, leading to PTB within 17 h. Cytokine levels increased in maternal serum, followed by a modest increase in fetal serum and in amniotic fluid. In uterus, placenta, and fetal membranes, LPS mostly increased the expressions of TLR, SPs, and cytokines. The number of TLR2-positive macrophages increased in labyrinthine placenta. In fetal lung, intestine, liver, and brain there were modest changes in cytokine expressions. In fetal lung, SP and TLR mRNAs decreased and TLR2-positive macrophages redistributed around vessels. LPS-induced fetal deaths associated with early age (16 d gestation) rather than with proinflammatory activation. Here we propose that maternal LPS response leads to PTB and acute decrease of immune proteins in epithelial lining of fetal lung. Instead, acceleration of lung maturity has been previously observed in intraamniotic inflammation.

Activated protein C reduces endotoxin-induced white matter injury in the developing rat brain

Periventricular leukomalacia (PVL), the dominant form of brain injury in premature infants, is characterized by white matter injury (WMI) and is associated with cerebral palsy. The pathogenesis of PVL is complex and likely involves ischemia/reperfusion, free radical formation, excitotoxicity, impaired regulation of cerebral blood flow, a procoagulant state, and inflammatory mechanisms associated with maternal and/or fetal infection. Using an established animal model of human PVL, we investigated whether activated protein C (APC), an anti-coagulant factor with anti-inflammatory, anti-apoptotic, anti-oxidant, and cytoprotective activities, could reduce endotoxin-induced WMI in the developing rat brain. Intraperitoneal injections of lipopolysaccharide (LPS) (0.5 mg/kg body weight) were given at embryonic days 18 (E18) and 19 (E19) to pregnant Sprague-Dawley rats; control rats were injected with sterile saline. A single intravenous injection of recombinant human (rh) APC (0.2 mg /kg body weight) was given to pregnant rats following the second LPS dose on embryonic day 19 (E19). Reduced cell death in white matter and hypomyelination were shown on TUNEL and myelin basic protein (MBP) staining, respectively, on late postnatal days (P7) in APC-treated groups. There were significantly fewer TUNEL+nuclei in the periventricular WM in the APC+LPS group than in the untreated LPS group. Compared to the APC+LPS and control group, MBP expression was weak in the LPS group on P7, indicating endotoxin-induced hypomyelination in the developing rat brain. APC attenuated the LPS-induced protein expression of inflammatory cytokines, tumor necrosis factor-alpha, and interleukin-6, as evaluated by ELISA in neonatal rat brains. A single intraperitoneal injection of rhAPC (0.2 mg/kg body weight) to neonatal rats on P1 also had similar protective and anti-inflammatory effects against maternally administered LPS. Collectively, these data support the hypothesis that APC may provide protection against an endotoxin-evoked inflammatory response and WMI in the developing rat brain. Moreover, our results suggest that the possible use of APC in treatment of preterm infants and pregnant women with maternal or placental infection may minimize the risk of PVL and cerebral palsy.

Interleukin 10 Regulates Inflammatory Cytokine Synthesis to Protect Against Lipopolysaccharide-Induced Abortion and Fetal Growth Restriction in Mice1

Interleukin 10 (IL10) is a potent immune-regulating cytokine and inhibitor of inflammatory cytokine synthesis. To evaluate the anti-inflammatory role of IL10 in pregnancy, the response of genetically IL10-deficient mice to low-dose lipopolysaccharide (LPS)-induced abortion was examined. When IL10-null mutant C57Bl/6 (Il10(-/-)) and control (Il10(+/+)) mice were administered low-dose LPS on Day 9.5 of gestation, IL10 deficiency predisposed to fetal loss accompanied by growth restriction in remaining viable fetuses, with an approximately 10-fold reduction in the threshold dose for 100% abortion. After LPS administration, inflammatory cytokines tumor necrosis factor-alpha (TNFA) and IL6 were markedly increased in serum, uterine, and conceptus tissues in Il10(-/-) mice compared with Il10(+/+) mice, with elevated local synthesis of Tnfa and Il6 mRNAs in the gestational tissues. IL1A and IL12p40 were similarly elevated in serum and gestational tissues, whereas interferon gamma (IFNG) and soluble TNFRII content were unchanged in the absence of IL10. Recombinant IL10 rescued the increased susceptibility to LPS-induced fetal loss in Il10(-/-) mice but did not improve outcomes in Il10(+/+) mice. IL10 genotype also influenced the responsiveness of mice to a TNFA antagonist, etanercept. Fetal loss in Il10(-/-) mice was partly alleviated by moderate or high doses of etanercept, whereas Il10(+/+) mice were refractory to high-dose etanercept, consistent with attenuation by IL10 status of TNFA bioavailability after etanercept treatment. These data show that IL10 modulates resistance to inflammatory stimuli by downregulating expression of proinflammatory cytokines TNFA, IL6, IL1A, and IL12, acting to protect against inflammation-induced pathology in the implantation site.

Erythropoietin attenuates lipopolysaccharide-induced white matter injury in the neonatal rat brain

Periventricular leukomalacia (PVL), a common neonatal brain white matter (WM) lesion, is frequently associated with cerebral palsy. Growing evidence has indicated that in addition to ischemia/reperfusion injury, cytokine-induced brain injury associated with maternal or fetal infection may also play an important role in the pathogenesis of PVL. Recent studies have shown that administration of lipopolysaccharide (LPS) to pregnant rats causes enhanced expression of the cytokines, i.e., IL-1 beta, TNF-alpha, and IL-6, in fetal brains. In recent years, it has been shown that erythropoietin (EPO) has a critical role in the development, maintenance, protection and repair of the nervous system. In the present study we investigated the effect of EPO on LPS-induced WM injury in Sprague-Dawley rats. LPS (500 microg/kg) suspension in pyrogen-free saline was administered intraperitoneally to pregnant rats at 18 and 19 days of gestation. The control group was treated with pyrogen-free saline. They were given 5,000 U/kg recombinant human EPO. Seven-day-old Sprague-Dawley rat pups were divided into four groups: control group, LPS-treated group, prenatal maternal EPO-treated group (5,000 U/kg, intraperitoneally given to pregnant rats at 18 and 19 days of gestation), and postnatal EPO-treated group (5,000 U/kg, intraperitoneally given to 1-day-old rat pups). Cytokine induction in the postnatal 7-day-old (P7) rat brain after maternal administration of LPS was determined by the ELISA method. The proinflammatory cytokine levels (IL-1 beta, TNF-alpha, and IL-6) in P7 rat pup brains were significantly increased in the LPS-treated group as compared with the control group. Prenatal maternal EPO treatment significantly reduced the concentration of TNF-alpha and IL-6 in the newborn rat brain following LPS injection. The concentration of IL-1 beta was decreased in the intrauterine EPO treatment group. Postnatal EPO treatment significantly decreased only the IL-6 concentration in the newborn rat brain following LPS injection. The concentration of cytokines, IL-1 beta and TNF-alpha, was reduced in the postnatal EPO treatment group. We demonstrated here that LPS administration in pregnant rats at gestational day 18 and 19 induced WM injury in P7 progeny characterized by apoptosis. Prenatal maternal and postnatal EPO treatment significantly reduced the number of apoptotic cells in the periventricular WM. Using immunohistochemistry techniques, we investigated the effects of maternal administration of LPS on myelin basic protein (MBP) staining, as a marker of myelination in the periventricular area in the neonatal rat brain. MBP staining was significantly less and weaker in the brains of the LPS-treated group as compared with the prenatal maternal EPO-treated group. However, the postnatal EPO treatment did not prevent LPS-stimulated loss of MBP-positive staining. In conclusion, especially prenatal maternal EPO treatment attenuates LPS-induced injury by reducing the expression of inflammatory cytokines and sparing MBP in the neonatal rat brain. While the postnatal EPO treatment prevented LPS-induced brain injury this effect was partial. To our knowledge, this is the first study that demonstrates a protective effect of EPO on LPS-induced WM injury in the developing brain. Regarding the wide use of EPO in premature newborns, this agent maybe potentially beneficial in treating LPS-induced brain injury in the perinatal period.

Disruption of interleukin-18, but not interleukin-1, increases vulnerability to preterm delivery and fetal mortality after intrauterine inflammation

Preterm birth is a major contributor of adverse perinatal outcome. Clinical data suggest that an inflammatory response is important in the process leading to preterm labor. By using a recently introduced mouse model of localized intrauterine lipopolysaccharide-induced inflammation, the effect of interleukin (IL)-18 gene disruption and/or IL-18 neutralization as well as combined IL-1alpha/beta gene disruption on inflammation-induced fetal loss was investigated. The frequency of preterm fetal loss was significantly higher in IL-18 knockout mice (58.9%) and in mice administered IL-18-binding protein (59.7%) compared to wild-type controls (34.7%). The rate of fetal loss was not affected by IL-1alpha/beta gene deficiency (38.7%). Decreased IL-18 protein expression combined with elevated IL-12 protein expression in uterine tissue of IL-18 knockout mice and IL-18-binding protein-treated animals was noticed. These data demonstrate that preterm pregnancy loss in response to intrauterine inflammation was enhanced by disruption of the IL-18 gene and/or IL-18 neutralization, events that may relate to exaggerated Th1 responses because of an increased IL-12/IL-18 ratio.

Lipopolysaccharide-induced inflammation and perinatal brain injury

Both energy failure and infections are important risk factors for brain injury in term and preterm infants. In this review we focus on recent experimental studies that have examined the effects of lipopolysaccharide (LPS) exposure to the fetus or neonate and the interaction of LPS with other events. Intracerebral LPS injections induce a marked cerebral cytokine response and prominent white matter lesions. LPS administered intravenously to the fetus also induces gross lesions, which are mainly localised to the white matter and are accompanied by activation of inflammatory cells. Cerebral effects following fetal LPS exposure via more distant routes, such as intracervical, intrauterine or maternal LPS administration, are characterised by reductions in oligodendrocyte or myelin markers without macroscopic lesions being evident. Both antenatal and neonatal LPS exposures increase the sensitivity of the brain to subsequent hypoxic/ischaemic events, even in adulthood. These studies suggest that fetal inflammation is the strongest predictor of brain lesions.

The role of cytokines in mediating effects of prenatal infection on the fetus: implications for schizophrenia

Maternal infections with bacterial or viral agents during pregnancy are associated with an increased incidence of schizophrenia in the offspring at adulthood although little is known about the mechanism by which maternal infection might affect fetal neurodevelopment. Exposure of pregnant rodents to the bacterial endotoxin, lipopolysaccharide (LPS), results in behavioral deficits in the adult offspring that are relevant to schizophrenia. It is however unknown whether these effects are due to the direct action of the inflammatory stimulus on the developing fetus, or due to secondary immune mediators (cytokines) activated at maternal/fetal sites. In this study we sought to elucidate the site of action of LPS, following a single intraperitoneal (i.p.) injection, in pregnant rats at gestation day 18. Animals received 5 muCi of iodinated LPS ((125)I-LPS) and its distribution was assessed in maternal/fetal tissues (1-8 h). In addition, induction of the inflammatory cytokines, TNF-alpha, IL-1beta and IL-6, was measured in maternal/fetal tissues following maternal LPS challenge (0.05 mg/kg, i.p.) (2-8 h). (125)I-LPS was detected in maternal tissues and placenta, but not the fetus. This distribution was accompanied by significant increases in TNF-alpha, IL-1beta and IL-6 in maternal plasma and placenta, but not in fetal liver or brain. A significant increase in IL-1beta was however detected in fetal plasma, possibly due to transfer from the maternal circulation or placenta. Collectively, these data suggest that effects of maternal LPS exposure on the developing fetal brain are not mediated by the direct action of LPS, but via indirect actions at the level of the maternal circulation or placenta.