Maternal obesity alters fetal neuroinflammation in a murine model of preterm birth.

BACKGROUND: Preterm birth from intrauterine infection is a leading cause of neonatal neurologic morbidity. Likewise, maternal obesity is associated with intra-amniotic infection and inflammation. Whether maternal obesity is a risk factor for fetal brain injury that occurs with premature birth remains unknown. This study hypothesized that maternal obesity intensifies fetal neuroinflammation in the setting of premature delivery. OBJECTIVE: This study aimed to examine the influence of maternal obesity on perinatal neuroinflammatory responses that arise with preterm birth using a murine model. STUDY DESIGN: Dams with obesity were generated via a high-fat diet that was maintained throughout pregnancy. In parallel, dams without obesity (normal) received a control diet. All dams were paired with males on normal diet. Pregnant dams were randomized to receive an intrauterine administration of bacterial endotoxin (lipopolysaccharide) or the vehicle (phosphate-buffered saline) on embryo day 15.5 of what is typically a 19- to 21-day gestation. Fetal brains were harvested 6 hours after intrauterine administrations, and the expressions of key inflammatory cytokines (Il1b, Il6, and Tnf) and panels of metabolic, immune, and inflammatory genes were analyzed. RESULTS: With the phosphate-buffered saline, there was no difference in gene expression related to maternal obesity. There were substantial differences in Il6 and immune/inflammatory expression profiles in fetal brains from dams with obesity vs normal dams that received lipopolysaccharide. Few differences were observed among the metabolic genes examined under these conditions. The gene expression pattern associated with maternal obesity correlated with pathways related to white matter injury. CONCLUSION: The expression of neuroinflammatory markers instigated by bacterial endotoxin via intrauterine lipopolysaccharide was greater in embryo brains obtained from dams with obesity. Expression profiles suggest that in combination with intrauterine inflammation, maternal obesity may increase the risk of fetal white matter injury. Further investigation is warranted to understand the relationship between maternal health and neurologic outcomes associated with prematurity.

Understanding the Mechanism and Extent of Transplacental Transfer of (-)-∆9 -Tetrahydrocannabinol (THC) in the Perfused Human Placenta to Predict In Vivo Fetal THC Exposure.

Cannabis use during pregnancy may cause fetal toxicity driven by in utero exposure to (-)-∆9 -tetrahydrocannabinol (THC) and its psychoactive metabolite, (±)-11-hydroxy-∆9 -THC (11-OH-THC). THC concentrations in the human term fetal plasma appear to be lower than the corresponding maternal concentrations. Therefore, we investigated whether THC and its metabolites are effluxed by placental transporters using the dual cotyledon, dual perfusion, term human placenta. The perfusates contained THC alone (5 µM) or in combination (100-250 nM) with its metabolites (100 nM or 250 nM 11-OH-THC, 100 nM COOH-THC), plus a marker of P-glycoprotein (P-gp) efflux (1 or 10 µM saquinavir), and a passive diffusion marker (106 µM antipyrine). All perfusions were conducted with (n = 7) or without (n = 16) a P-gp/BCRP (breast-cancer resistance protein) inhibitor, 4 µM valspodar. The maternal-fetal and fetal-maternal unbound cotyledon clearance indexes (m-f-CLu,c,i and f-m-CLu,c,i ) were normalized for transplacental antipyrine clearance. At 5 µM THC, the m-f-CLu,c,i , 5.1 ± 2.1, was significantly lower than the f-m-CLu,c,i , 13 ± 6.1 (P = 0.004). This difference remained in the presence of valspodar or when the lower THC concentrations were perfused. In contrast, neither metabolite, 11-OH-THC/COOH-THC, had significantly different m-f-CLu,c,i vs. f-m-CLu,c,i . Therefore, THC appears to be effluxed by placental transporter(s) not inhibitable by the P-gp/BCRP antagonist, valspodar, while 11-OH-THC and COOH-THC appear to passively diffuse across the placenta. These findings plus our previously quantified human fetal liver clearance, extrapolated to in vivo, yielded a THC fetal/maternal steady-state plasma concentration ratio of 0.28 ± 0.09, comparable to that observed in vivo, 0.26 ± 0.10.

Estrogen receptor 1 appears essential for fetal viability in a murine model of premature birth.

PROBLEM: Protective effects for adult neurological disorders have been attributed to sex hormones. Using a murine model of prematurity, we evaluated the role of estrogen signaling in the process of perinatal brain injury following exposure to intrauterine inflammation. METHOD OF STUDY: Intrauterine lipopolysaccharide (LPS) was used to invoke preterm labor and fetal neuroinflammation. Fetal brains were analyzed for changes in Esr1, Esr2 and Cyp19. Dams heterozygous for the Esr1 knockout allele were also given intrauterine LPS to compare delivery and offspring viability to wild type controls. RESULTS: The upregulation in inflammatory cytokines was accompanied by an increase in Esr1 and Esr2 transcripts, though protein levels declined. Cyp19 did not differ by mRNA or protein abundance. Offspring from Esr1 mutants were larger, had a longer gestation and significantly greater mortality. CONCLUSIONS: Estrogen signaling is altered in the fetal brains of preterm offspring exposed to neuroinflammatory injury. The reduction of Esr1 and Esr2 proteins with LPS suggests that these proteins are degraded. It is possible that transcriptional upregulation of Esr1 and Esr2 occurs to compensate for the loss of these proteins. Alternatively, the translation of Esr1 and Esr2 mRNAs may be disrupted with LPS while a feedback mechanism upregulates transcription. Intact Esr1 signaling is also associated with early preterm delivery following exposure to intrauterine LPS. A loss of one Esr1 allele delays this process, but appears to do so at the cost of fetal viability. These results suggest estrogen signaling plays opposing roles between maternal and fetal responses to preterm birth.

Longitudinal Proteomic Analysis of Plasma across Healthy Pregnancies Reveals Indicators of Gestational Age.

Longitudinal changes in the blood proteome during gestation relate to fetal development and maternal homeostasis. Charting the maternal blood proteome in normal pregnancies is critical for establishing a baseline reference when assessing complications and disease. Using mass spectrometry-based shotgun proteomics, we surveyed the maternal plasma proteome across uncomplicated pregnancies. Results indicate a significant rise in proteins that govern placentation and are vital to the development and health of the fetus. Importantly, we uncovered proteome signatures that strongly correlated with gestational age. Fold increases and correlations between the plasma concentrations of ADAM12 (ρ = 0.973), PSG1 (ρ = 0.936), and/or CSH1/2 (ρ = 0.928) with gestational age were validated with ELISA. Proteomic and validation analyses demonstrate that the maternal plasma concentration of ADAM12, either independently or in combination with either PSG1 or CSH1/2, correlates with gestational age within ±8 days throughout pregnancy. These findings suggest that the gestational age in healthy pregnancies may be determined by referencing the concentration of select plasma proteins.

ZIKV can infect human term placentas in the absence of maternal factors.

Zika virus infection can result in devastating pregnancy outcomes when it crosses the placental barrier. For human pregnancies, the mechanisms of vertical transmission remain enigmatic. Utilizing a human placenta-cotyledon perfusion model, we examined Zika virus exposure in the absence of maternal factors. To distinguish responses related to viral infection vs. recognition, we evaluated cotyledons perfused with either active or inactivated Zika virus. Active Zika virus exposure resulted in infection, cell death and syncytium injury. Pathology corresponded with transcriptional changes related to inflammation and innate immunity. Inactive Zika virus exposure also led to syncytium injury and related changes in gene expression but not cell death. Our observations reveal pathologies and innate immune responses that are dependent on infection or virus placenta interactions independent of productive infection. Importantly, our findings indicate that Zika virus can infect and compromise placentas in the absence of maternal humoral factors that may be protective.

Correction: The orphan nuclear receptor Nr4a1 mediates perinatal neuroinflammation in a murine model of preterm labor.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The orphan nuclear receptor Nr4a1 mediates perinatal neuroinflammation in a murine model of preterm labor.

Prematurity is associated with perinatal neuroinflammation and injury. Screening for genetic modulators in an LPS murine model of preterm birth revealed the upregulation of Nr4a1, an orphan nuclear transcription factor that is normally absent or limited in embryonic brains. Concurrently, Nr4a1 was downregulated with magnesium sulfate (MgSO4) and betamethasone (BMTZ) treatments administered to LPS exposed dams. To understand the role of Nr4a1 in perinatal brain injury, we compared the preterm neuroinflammatory response in Nr4a1 knockout (KO) versus wild type (wt) mice. Key inflammatory factors Il1b, Il6 and Tnf, and Iba1+ microglia were significantly lower in Nr4a1 KO versus wt brains exposed to LPS in utero. Treatment with MgSO4/BMTZ mitigated the neuroinflammatory process in wt but not Nr4a1 KO brains. These results correspond with a reduction in cerebral hemorrhage in wt but not mutant embryos from dams given MgSO4/BMTZ. Further analysis with Nr4a1-GFP-Cre × tdTomato loxP reporter mice revealed that the upregulation of Nr4a1 with perinatal neuroinflammation occurs in the cerebral vasculature. Altogether, this study implicates Nr4a1 in the developing vasculature as a potent mediator of neuroinflammatory brain injury that occurs with preterm birth. It is also possible that MgSO4/BMTZ mitigates this process by direct or indirect inhibition of Nr4a1.