Chronic endotoxin exposure causes brain injury in the ovine fetus in the absence of hypoxemia

Fetal heart rate patterns complicated by chorioamnionitis and subsequent cerebral palsy in Japan

AIM

This retrospective study was performed to investigate whether certain fetal heart rate patterns were associated with subsequent cerebral palsy (CP) in infants with chorioamnionitis at or near term.

METHODS

We used cases registered by the Japan Obstetric Compensation System for CP, which is a nationwide population-based database. Among them, 133 infants with chorioamnionitis who were born at ≥34 weeks of gestation were enrolled. All infants underwent magnetic resonance imaging (MRI), and all fetal heart rate charts had been interpreted according to the National Institute of Child Health and Human Development criteria, focusing on antepartum and immediately before delivery.

RESULTS

The incidence of CP after chorioamnionitis at ≥34 weeks of gestation was 0.3 per 10 000 in Japan. Between the clinical (24%) and subclinical groups (76%), the incidence of abnormal fetal heart rate patterns did not differ. According to the MRI classification, 88% of the infants with CP showed hypoxic-ischemic encephalopathy. Half of the infants with CP experienced terminal bradycardia, leading to severe acidosis and exclusively to hypoxic-ischemic encephalopathy. In another half, who did not experience bradycardia, 80% had moderate acidosis (pH 7.00-7.20) resulting in hypoxic-ischemic encephalopathy, and the remaining 20% showed non-acidosis resulting in brain damage other than hypoxic-ischemic encephalopathy. The fetal heart rate patterns before the terminal bradycardia showed that the incidence rates of late deceleration or decreased variability were high (>60%).

CONCLUSION

Fifty percent of pregnant women with chorioamnionitis-related CP had terminal bradycardia that exclusively resulted in hypoxic-ischemic encephalopathy.

Alteration of the Oligodendrocyte Lineage Varies According to the Systemic Inflammatory Stimulus in Animal Models That Mimic the Encephalopathy of Prematurity

Preterm birth before the gestational age of 32 weeks is associated with the occurrence of specific white matter damage (WMD) that can compromise the neurological outcome. These white matter abnormalities are embedded in more global brain damage defining the encephalopathy of prematurity (EoP). A global reduction in white matter volume that corresponds to chronic diffuse WMD is the most frequent form in contemporary cohorts of very preterm infants. This WMD partly results from alterations of the oligodendrocyte (OL) lineage during the vulnerability window preceding the beginning of brain myelination. The occurrence of prenatal, perinatal and postnatal events in addition to preterm birth is related to the intensity of WMD. Systemic inflammation is widely recognised as a risk factor of WMD in humans and in animal models. This review reports the OL lineage alterations associated with the WMD observed in infants suffering from EoP and emphasizes the role of systemic inflammation in inducing these alterations. This issue is addressed through data on human tissue and imaging, and through neonatal animal models that use systemic inflammation to induce WMD. Interestingly, the OL lineage damage varies according to the inflammatory stimulus, i.e., the liposaccharide portion of the E.Coli membrane (LPS) or the proinflammatory cytokine Interleukin-1β (IL-1β). This discrepancy reveals multiple cellular pathways inducible by inflammation that result in EoP. Variable long-term consequences on the white matter morphology and functioning may be speculated upon according to the intensity of the inflammatory challenge. This hypothesis emerges from this review and requires further exploration.

Amniotic LPS-Induced Apoptosis in the Fetal Brain Is Suppressed by Vaginal LPS Preconditioning but Is Promoted by Continuous Ischemic Reperfusion

Chorioamnionitis (CAM) is an increasingly common disease affecting pregnant women which derives from bacterial vaginosis. In different clinical cases, it has been shown that CAM can cause multiple risk factors for fetal brain damage, such as infection, and intra-uterine asphyxia. However, the molecular mechanism remains unknown. In this study, we established a novel CAM mouse model by exposing pregnant mice to a combination of three risk factors: vaginal lipopolysaccharides (LPS), amniotic LPS, and ischemic reperfusion. We found amniotic LPS caused Parkinson's disease-like fetal brain damage, in a dose and time-dependent manner. Moreover, the mechanism of this fetal brain damage is apoptosis induced by amniotic LPS but it was inhibited by being pretreated with a vaginal LPS challenge before amniotic LPS injection. In contrast, amniotic LPS with continuous ischemic reperfusion caused a higher level of apoptotic cell death than amniotic LPS alone. In particular, a potential neuroprotective biomarker phosphorylation (p)-CREB (ser133) appeared in only vaginal LPS preconditioned before amniotic LPS, whereas ischemic reperfusion triggered IKK phosphorylation after amniotic LPS. Despite the need for many future investigations, this study also discussed a developed understanding of the molecular mechanism of how these phenotypes occurred.

Characterization of Fetal Brain Damage in Early Abortions of Ovine Toxoplasmosis

There is an unacknowledged clinical presentation of ovine toxoplasmosis characterized by early abortions and lesions of fetal leukoencephalomalacia. To investigate the pathogenesis of this condition, the extent and distribution of leukomalacia and the variations in the cell populations associated with it were characterized in 32 fetal brains from 2 previously published experimental studies of Toxoplasma gondii infection in pregnant sheep. Immunohistochemical labeling of βAPP allowed for the detection of leukomalacia in 100/110 (91%) studied samples. There was no clear influence of the challenge dose or the area of the brain (frontal lobe, corpus callosum, midbrain, and cerebellum). In tissues with leukomalacia, there was loss of oligodendrocytes and increased number of astrocytes and microglia both in the areas of necrosis but also in the surrounding area. These findings were similar to those described in ovine experimental models (inflammation syndrome and hypoxic models) of periventricular leukomalacia in humans. Thus, a fetal inflammatory syndrome may be involved in the pathogenesis of early abortion in ovine toxoplasmosis. However, further studies are needed to determine the pathogenesis of this clinical presentation because placental thrombosis and resulting hypoxia could also be responsible for the leukomalacia.

Effects of umbilical cord blood cells, and subtypes, to reduce neuroinflammation following perinatal hypoxic-ischemic brain injury

Background

It is well understood that hypoxic-ischemic (HI) brain injury during the highly vulnerable perinatal period can lead to cerebral palsy, the most prevalent cause of chronic disability in children. Recently, human clinical trials have reported safety and some efficacy following treatment of cerebral palsy using umbilical cord blood (UCB) cells. UCB is made up of many different cell types, including endothelial progenitor cells (EPCs), T regulatory cells (Tregs), and monocyte-derived suppressor cells (MDSCs). How each cell type contributes individually towards reducing neuroinflammation and/or repairing brain injury is not known. In this study, we examined whether human (h) UCB, or specific UCB cell types, could reduce peripheral and cerebral inflammation, and promote brain repair, when given early after perinatal HI brain injury.

Methods

HI brain injury was induced in postnatal day (PND) 7 rat pups and cells were administered intraperitoneally on PND 8. Behavioral testing was performed 7 days post injury, and then, brains and spleens were collected for analysis.

Results

We found in vitro that all UCB cell types, except for EPCs, were immunomodulatory. Perinatal HI brain injury induced significant infiltration of CD4+ T cells into the injured cerebral hemisphere, and this was significantly reduced by all hUCB cell types tested. Compared to HI, UCB, Tregs, and EPCs were able to reduce motor deficits, reduce CD4+ T cell infiltration into the brain, and reduce microglial activation. In addition to the beneficial effects of UCB, EPCs also significantly reduced cortical cell death, returned CD4+ T cell infiltration to sham levels, and reduced the peripheral Th1-mediated pro-inflammatory shift.

Conclusion

This study highlights that cells found in UCB is able to mediate neuroinflammation and is an effective neuroprotective therapy. Our study also shows that particular cells found in UCB, namely EPCs, may have an added advantage over using UCB alone. This work has the potential to progress towards tailored UCB therapies for the treatment of perinatal brain injury.

Beneficial Effect of Alcohol Withdrawal on Gut Permeability and Microbial Translocation in Patients with Alcohol Use Disorder

BACKGROUND

The human intestinal microbiota exerts beneficial or harmful effects in several disorders. Many factors, including alcohol consumption, may influence its composition and trigger bacterial translocation. Excessive alcohol consumption increases gut permeability and translocation of endotoxin into peripheral circulation. Although plasma endotoxin concentrations have been measured often, quantitative changes following alcohol withdrawal have never been described in subjects with alcohol use disorder (AUD). The aim of this study was to measure microbial translocation (MT) and gut permeability markers in patients with AUD, to compare these markers to healthy controls (HC) and to monitor markers during the first 6 weeks of abstinence.

METHODS

Sixty-five patients with AUD and hospitalized for alcohol withdrawal were included. Epidemiological, clinical, biological, and addictological data were gathered. Blood samples were collected at baseline, then 3 and 6 weeks after alcohol withdrawal. A hundred healthy volunteers were used as controls. Three markers of MT were monitored in plasma samples: sCD14 and lipopolysaccharide-binding protein (LBP) were quantified using ELISA, and 16S rDNA was quantified using real-time polymerase chain reaction. Zonulin and intestinal fatty acid binding protein (I-FABP) blood levels were also monitored as indirect markers of gut permeability, using ELISA.

RESULTS

At baseline, LBP, 16S rDNA, sCD14 and I-FABP markers were significantly higher in patients with AUD than in HC. Six weeks after alcohol withdrawal plasma levels of sCD14 and LBP decreased significantly. Cannabis consumption and body mass index (BMI) before alcohol withdrawal influenced baseline MT levels and the decrease in MT markers after 6 weeks. Finally, markers of MT and gut permeability did not correlate with each other before and after alcohol withdrawal.

CONCLUSIONS

Before alcohol withdrawal, MT markers were higher in patients with AUD than in HC. After 6 weeks of abstinence, an improvement in MT markers was observed. Our data suggest that there is a link between MT, its improvement, BMI, and cannabis consumption.

Perinatal Brain Injury As a Consequence of Preterm Birth and Intrauterine Inflammation: Designing Targeted Stem Cell Therapies

Chorioamnionitis is a major cause of preterm birth and brain injury. Bacterial invasion of the chorion and amnion, and/or the placenta, can lead to a fetal inflammatory response, which in turn has significant adverse consequences for the developing fetal brain. Accordingly, there is a strong causal link between chorioamnionitis, preterm brain injury and the pathogenesis of severe postnatal neurological deficits and cerebral palsy. Currently there are no treatments to protect or repair against brain injury in preterm infants born after pregnancy compromised by intrauterine infection. This review describes the injurious cascade of events in the preterm brain in response to a severe fetal inflammatory event. We will highlight specific periods of increased vulnerability, and the potential effects of therapeutic intervention with cell-based therapies. Many clinical trials are underway to investigate the efficacy of stem cells to treat patients with cerebral palsy. Stem cells, obtained from umbilical cord tissue and cord blood, normally discarded after birth, are emerging as a safe and potentially effective therapy. It is not yet known, however, which stem cell type(s) are the most efficacious for administration to preterm infants to treat brain injury-mediated inflammation. Individual stem cell populations found in cord blood and tissue, such as mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs), have a number of potential benefits that may specifically target preterm inflammatory-induced brain injury. MSCs have strong immunomodulatory potential, protecting against global and local neuroinflammatory cascades triggered during infection to the fetus. EPCs have angiogenic and vascular reparative qualities that make them ideal for neurovascular repair. A combined therapy using both MSCs and EPCs to target inflammation and promote angiogenesis for re-establishment of vital vessel networks is a treatment concept that warrants further investigation.

Human Amnion Epithelial Cells Protect Against White Matter Brain Injury After Repeated Endotoxin Exposure in the Preterm Ovine Fetus

Intrauterine inflammation is a significant cause of injury to the developing fetal brain. Using a preterm fetal sheep model of in utero infection, we asked whether human amnion epithelial cells (hAECs) were able to reduce inflammation-induced fetal brain injury. Surgery was undertaken on pregnant sheep at ∼105 days gestation (term is 147 days) for implantation of vascular catheters. Lipopolysaccharide (LPS; 150 ng/kg bolus) or saline was administered IV at 109, 110, and 111 days. Sixty million fluorescent-labeled hAECs were administered at 110, 111, and 112 days gestation via the brachial artery catheter. Brains were collected at 114 days for histological assessment. hAECs were observed within the cortex, white matter, and hippocampus. Compared to control lambs, LPS administration was associated with significant and widespread fetal brain inflammation and injury as evidenced by increased number of activated microglia in the periventricular white matter (p = 0.02), increased pyknosis, cell degeneration (p = 0.01), and a nonsignificant trend of fewer oligodendrocytes in the subcortical and periventricular white matter. Administration of hAECs to LPS-treated animals was associated with a significant mitigation in both inflammation and injury as evidenced by fewer activated microglia (p = 0.03) and pyknotic cells (p = 0.03), significantly more oligodendrocytes in the subcortical and periventricular white matter (p = 0.01 and 0.02, respectively), and more myelin basic protein-positive cells within the periventricular white matter (p = 0.02). hAEC administration to fetal sheep exposed to multiple doses of LPS dampens the resultant fetal inflammatory response and mitigates associated brain injury.

Chronic Exposure to Intra-Amniotic Lipopolysaccharide Affects the Ovine Fetal Brain

OBJECTIVE

Fetal brain injury is associated with chorioamnionitis, which is often present without signs of overt infection or fetal compromise. We aimed to determine if prolonged exposure to intrauterine inflammation caused by intra-amniotic infusion of lipopolysaccharide (LPS) would affect the fetal brain.

METHODS

At 80 days of pregnancy ewes bearing singletons had osmotic pumps implanted intra-amniotically to infuse Escherichia coli LPS (055:B5; n = 8) or saline (n = 7) for 28 days. At delivery (110 days), umbilical arterial blood and chorioamnion were assessed for inflammation; cytokine concentrations (interleukin [IL]-6 and IL-8) in amniotic fluid and fetal and maternal plasma were measured. The fetal cerebral hemispheres were examined for gross anatomical changes and the number of activated microglia/macrophages, astrocytes, and oligodendrocytes estimated after immunohistochemical staining.

RESULTS

Intra-amniotic administration of LPS caused chorioamnionitis, fetal leucocytosis, and a moderate to extensive infiltration of activated microglia/macrophages in the subcortical white matter in six of eight fetuses; the remaining two fetuses were less affected. Within these focal regions of damage there was an attenuation of astrocytic processes, axonal injury, and a reduction in the number of 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) immunoreactive oligodendrocytes in areas of extensive focal damage. In control fetuses there was mild (3/7) or no infiltration of activated microglia/macrophages in the subcortical white matter. Overall the infiltration of activated microglia/macrophages in the white matter was significantly greater in LPS-exposed fetuses compared to controls. In regions devoid of injury, the number of oligodendrocytes and astrocytes was not different between groups, nor was there a difference in the volume of cerebral white matter or density of blood vessels within the white matter. Amniotic fluid IL-6 and IL-8, and maternal plasma IL-8 concentrations were significantly increased by LPS infusion.

CONCLUSIONS

An increase in inflammatory cells and axonal disruption in the subcortical white matter of the fetal brain can accompany chorioamnionitis induced by intra-amniotic administration of LPS, but cystic lesions do not occur. Thus, the effect on the fetal brain is milder than that reported from animal models of acute fetal/intrauterine infection.

The Ovine Fetal and Placental Inflammatory Response to Umbilical Cord Occlusions With Worsening Acidosis

We hypothesized that repetitive umbilical cord occlusions (UCOs) leading to severe acidemia will stimulate a placental and thereby fetal inflammatory response which will be exacerbated by chronic hypoxemia and low-grade bacterial infection. Chronically instrumented fetal sheep served as controls or underwent repetitive UCOs for up to 4 hours or until fetal arterial pH was <7.00. Normoxic-UCO and hypoxic-UCO fetuses had arterial O2 saturation pre-UCOs of >55% and <55%, respectively, while lipopolysaccharide (LPS)-UCO fetuses received LPS intra-amniotic (2 mg/h) starting 1 hour pre-UCOs. Fetal plasma and amniotic fluid were sampled for interleukin (IL) 6 and IL-1β. Animals were euthanized at 48 hours of recovery with placental cotyledons processed for measurement of macrophage, neutrophil, and mast cell counts. Repetitive UCOs resulted in severe fetal acidemia with pH approaching 7.00 for all 3 UCO groups. Neutrophils, while unchanged within the cotyledon fetal and intermediate zones, were ∼2-fold higher within the zona intima for all 3 UCO groups. However, no differences were observed in macrophage counts among the treatment groups and no cotyledon mast cells were seen. Fetal plasma and amniotic fluid cytokines remained little changed post-UCOs and/or at 1 and 48 hours of recovery in the normoxic-UCO and hypoxic-UCO groups but increased several fold in the LPS-UCO group with IL-6 plasma values at 1 hour recovery highly correlated with the nadir pH attained (r = -.97). As such, repetitive UCOs with severe acidemia can induce a placental inflammatory response and more so with simulated low-grade infection and likely contributing to cytokine release in the umbilical circulation.

Preterm birth, intrauterine infection, and fetal inflammation

Preterm birth (PTB) (delivery before 37 weeks’ gestation) is a leading cause of neonatal death and disease in industrialized and developing countries alike. Infection (most notably in high-risk deliveries occurring before 28 weeks’ gestation) is hypothesized to initiate an intrauterine inflammatory response that plays a key role in the premature initiation of labor as well as a host of the pathologies associated with prematurity. As such, a better understanding of intrauterine inflammation in pregnancy is critical to our understanding of preterm labor and fetal injury, as well as on-going efforts to prevent PTB. Focusing on the fetal innate immune system responses to intrauterine infection, the present paper will review clinical and experimental studies to discuss the capacity for a fetal contribution to the intrauterine inflammation associated with PTB. Evidence from experimental studies to suggest that the fetus has the capacity to elicit a pro-inflammatory response to intrauterine infection is highlighted, with reference to the contribution of the lung, skin, and gastrointestinal tract. The paper will conclude that pathological intrauterine inflammation is a complex process that is modified by multiple factors including time, type of agonist, host genetics, and tissue.

Could cord blood cell therapy reduce preterm brain injury?

Major advances in neonatal care have led to significant improvements in survival rates for preterm infants, but this occurs at a cost, with a strong causal link between preterm birth and neurological deficits, including cerebral palsy (CP). Indeed, in high-income countries, up to 50% of children with CP were born preterm. The pathways that link preterm birth and brain injury are complex and multifactorial, but it is clear that preterm birth is strongly associated with damage to the white matter of the developing brain. Nearly 90% of preterm infants who later develop spastic CP have evidence of periventricular white matter injury. There are currently no treatments targeted at protecting the immature preterm brain. Umbilical cord blood (UCB) contains a diverse mix of stem and progenitor cells, and is a particularly promising source of cells for clinical applications, due to ethical and practical advantages over other potential therapeutic cell types. Recent studies have documented the potential benefits of UCB cells in reducing brain injury, particularly in rodent models of term neonatal hypoxia–ischemia. These studies indicate that UCB cells act via anti-inflammatory and immuno-modulatory effects, and release neurotrophic growth factors to support the damaged and surrounding brain tissue. The etiology of brain injury in preterm-born infants is less well understood than in term infants, but likely results from episodes of hypoperfusion, hypoxia–ischemia, and/or inflammation over a developmental period of white matter vulnerability. This review will explore current knowledge about the neuroprotective actions of UCB cells and their potential to ameliorate preterm brain injury through neonatal cell administration. We will also discuss the characteristics of UCB-derived from preterm and term infants for use in clinical applications.

Impact of levosimendan on brain injury patterns in a lamb model of infant cardiopulmonary bypass

BACKGROUND

The effects of levosimendan (Levo) on injury patterns in the immature brain following cardiopulmonary bypass (CPB) are unknown.

METHODS

Eighteen 3- to 4-wk-old anesthetized lambs, instrumented with vascular catheters and aortic and right carotid artery flow probes, were allocated to non-CPB, CPB, or CPB+Levo groups (each n = 6). After 120 min CPB with 90 min aortic cross-clamp, CPB animals received dopamine, and CPB+Levo animals both dopamine and Levo, for 4 h. All lambs then underwent brain magnetic resonance imaging, followed by postmortem brain perfusion fixation for immunohistochemical studies.

RESULTS

In CPB lambs, aortic (P < 0.05) and carotid artery (P < 0.01) blood flows fell by 29 and 30%, respectively, between 2 and 4 h after cross-clamp removal but were unchanged in the CPB+Levo group. No brain injury was detectable with magnetic resonance imaging in either CPB or CPB+Levo lambs. However, on immunohistochemical analysis, white matter astrocyte density of both groups was higher than in non-CPB lambs (P < 0.05), while white matter microglial density was higher (P < 0.05), but markers of cortical oxidative stress were less prevalent in CPB+Levo than CPB lambs.

CONCLUSION

While Levo prevented early postoperative falls in cardiac output and carotid artery blood flow in a lamb model of infant CPB, this was associated with heterogeneous neuroglial activation and manifestation of markers of oxidative stress.

Antenatal antioxidant treatment with melatonin to decrease newborn neurodevelopmental deficits and brain injury caused by fetal growth restriction

Fetal intrauterine growth restriction (IUGR) is a serious pregnancy complication associated with increased rates of perinatal morbidity and mortality, and ultimately with long-term neurodevelopmental impairments. No intervention currently exists that can improve the structure and function of the IUGR brain before birth. Here, we investigated whether maternal antenatal melatonin administration reduced brain injury in ovine IUGR. IUGR was induced in pregnant sheep at 0.7 gestation and a subset of ewes received melatonin via intravenous infusion until term. IUGR, IUGR + melatonin (IUGR + MLT) and control lambs were born naturally, neonatal behavioral assessment was used to examine neurological function and at 24 hr after birth the brain was collected for the examination of neuropathology. Compared to control lambs, IUGR lambs took significantly longer to achieve normal neonatal lamb behaviors, such as standing and suckling. IUGR brains showed widespread cellular and axonal lipid peroxidation, and white matter hypomyelination and axonal damage. Maternal melatonin administration ameliorated oxidative stress, normalized myelination and rescued axonopathy within IUGR lamb brains, and IUGR + MLT lambs demonstrated significant functional improvements including a reduced time taken to attach to and suckle at the udder after birth. Based on these observations, we began a pilot clinical trial of oral melatonin administration to women with an IUGR fetus. Maternal melatonin was not associated with adverse maternal or fetal effects and it significantly reduced oxidative stress, as evidenced by reduced malondialdehyde levels, in the IUGR + MLT placenta compared to IUGR alone. Melatonin should be considered for antenatal neuroprotective therapy in human IUGR.

Imaging of an inflammatory injury in the newborn rat brain with photoacoustic tomography

Background

The precise assessment of cerebral saturation changes during an inflammatory injury in the developing brain, such as seen in periventricular leukomalacia, is not well defined. This study investigated the impact of inflammation on locoregional cerebral oxygen saturation in a newborn rodent model using photoacoustic imaging.

Methods

1 mg/kg of lipopolysaccharide(LPS) diluted in saline or saline alone was injected under ultrasound guidance directly in the corpus callosum of P3 rat pups. Coronal photoacoustic images were carried out 24 h after LPS exposure. Locoregional oxygen saturation (SO₂) and resting state connectivity were assessed in the cortex and the corpus callosum. Microvasculature was then evaluated on cryosection slices by lectin histochemistry.

Results

Significant reduction of SO₂ was found in the corpus callosum; reduced SO₂ was also found in the cortex ipsilateral to the injection site. Seed-based functional connectivity analysis showed that bilateral connectivity was not affected by LPS exposure. Changes in locoregional oxygen saturation were accompanied by a significant reduction in the average length of microvessels in the left cortex but no differences were observed in the corpus callosum.

Conclusion

Inflammation in the developing brain induces marked reduction of locoregional oxygen saturation, predominantly in the white matter not explained by microvascular degeneration. The ability to examine regional saturation offers a new way to monitor injury and understand physiological disturbance non-invasively.

Neonatal infection and 5-year neurodevelopmental outcome of very preterm infants

OBJECTIVE

To determine whether neonatal infections are associated with a higher risk of adverse neurodevelopment at 5 years of age in a population-based cohort of very preterm children.

METHODS

We included all live births between 22 and 32 weeks of gestation, from 9 regions in France, in 1997 (EPIPAGE study). Of the 2665 live births, 2277 were eligible for a follow-up evaluation at 5 years of age: 1769 had a medical examination and 1495 underwent cognitive assessment. Cerebral palsy and cognitive impairment were studied as a function of early-onset sepsis (EOS) and late-onset sepsis (LOS), after adjustment for potential confounding factors, in multivariate logistic regression models.

RESULTS

A total of 139 (5%) of the 2665 live births included in the study presented with EOS alone (without associated LOS), 752 (28%) had LOS alone (without associated EOS), and 64 (2%) displayed both EOS and LOS. At 5 years of age, the frequency of cerebral palsy was 9% (157 of 1769) and that of cognitive impairment was 12% (177 of 1495). The frequency of cerebral palsy was higher in infants with isolated EOS (odds ratio [OR]: 1.70 [95% confidence interval (CI): 0.84-3.45]) or isolated LOS (OR: 1.71 [95% CI: 1.14-2.56]) than in uninfected infants, and this risk was even higher in cases of combined EOS and LOS (OR: 2.33 [95% CI: 1.02-5.33]). There was no association between neonatal infection and cognitive impairment.

CONCLUSIONS

Neonatal infections in these very preterm infants were associated with a higher risk of cerebral palsy at the age of 5 years, particularly in infants presenting with both EOS and LOS.

The immune consequences of preterm birth

Preterm birth occurs in 11% of live births globally and accounts for 35% of all newborn deaths. Preterm newborns have immature immune systems, with reduced innate and adaptive immunity; their immune systems may be further compromised by various factors associated with preterm birth. The immune systems of preterm infants have a smaller pool of monocytes and neutrophils, impaired ability of these cells to kill pathogens, and lower production of cytokines which limits T cell activation and reduces the ability to fight bacteria and detect viruses in cells, compared to term infants. Intrauterine inflammation is a major contributor to preterm birth, and causes premature immune activation and cytokine production. This can induce immune tolerance leading to reduced newborn immune function. Intrauterine inflammation is associated with an increased risk of early-onset sepsis and likely has long-term adverse immune consequences. Requisite medical interventions further impact on immune development and function. Antenatal corticosteroid treatment to prevent newborn respiratory disease is routine but may be immunosuppressive, and has been associated with febrile responses, reductions in lymphocyte proliferation and cytokine production, and increased risk of infection. Invasive medical procedures result in an increased risk of late-onset sepsis. Respiratory support can cause chronic inflammatory lung disease associated with increased risk of long-term morbidity. Colonization of the infant by microorganisms at birth is a significant contributor to the establishment of the microbiome. Caesarean section affects infant colonization, potentially contributing to lifelong immune function and well-being. Several factors associated with preterm birth alter immune function. A better understanding of perinatal modification of the preterm immune system will allow for the refinement of care to minimize lifelong adverse immune consequences.

Human amnion epithelial cells reduce fetal brain injury in response to intrauterine inflammation

Intrauterine infection, such as occurs in chorioamnionitis, is a principal cause of preterm birth and is a strong risk factor for neurological morbidity and cerebral palsy. This study aims to examine whether human amnion epithelial cells (hAECs) can be used as a potential therapeutic agent to reduce brain injury induced by intra-amniotic administration of lipopolysaccharide (LPS) in preterm fetal sheep. Pregnant ewes underwent surgery at approximately 110 days of gestation (term is approx. 147 days) for implantation of catheters into the amniotic cavity, fetal trachea, carotid artery and jugular vein. LPS was administered at 117 days; hAECs were labeled with carboxyfluorescein succinimidyl ester and administered at 0, 6 and 12 h, relative to LPS administration, into the fetal jugular vein, trachea or both. Control fetuses received an equivalent volume of saline. Brains were collected 7 days later for histological assessment of brain injury. Microglia (Iba-1-positive cells) were present in the brain of all fetuses and were significantly increased in the cortex, subcortical and periventricular white matter in fetuses that received LPS, indicative of inflammation. Inflammation was reduced in fetuses that received hAECs. In LPS fetuses, the number of TUNEL-positive cells was significantly elevated in the cortex, periventricular white matter, subcortical white matter and hippocampus compared with controls, and reduced in fetuses that received hAECs in the cortex and periventricular white matter. Within the fetal brains studied there was a significant positive correlation between the number of Iba-1-immunoreactive cells and the number of TUNEL-positive cells (R(2) = 0.19, p < 0.001). The administration of hAECs protects the developing brain when administered concurrently with the initiation of intrauterine inflammation.

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.

Increased number of cerebellar granule cells and astrocytes in the internal granule layer in sheep following prenatal intra-amniotic injection of lipopolysaccharide

Chorioamnionitis is an important problem in perinatology today, leading to brain injury and neurological handicaps. However, there are almost no data available regarding chorioamnionitis and a specific damage of the cerebellum. Therefore, this study aimed at determining if chorioamnionitis causes cerebellar morphological alterations. Chorioamnionitis was induced in sheep by the intra-amniotic injection of lipopolysaccharide (LPS) at a gestational age (GA) of 110 days. At a GA of 140 days, we assessed the mean total and layer-specific volume and the mean total granule cell (GCs) and Purkinje cell (PC) number in the cerebelli of LPS-exposed and control animals using high-precision design-based stereology. Astrogliosis was assessed in the gray and white matter (WM) using a glial fibrillary acidic protein staining combined with gray value image analysis. The present study showed an unchanged volume of the total cerebellum as well as the molecular layer, outer and inner granular cell layers (OGL and IGL, respectively), and WM. Interestingly, compared with controls, the LPS-exposed brains showed a statistically significant increase (+20.4%) in the mean total number of GCs, whereas the number of PCs did not show any difference between the two groups. In addition, LPS-exposed animals showed signs of astrogliosis specifically affecting the IGL. Intra-amniotic injection of LPS causes morphological changes in the cerebellum of fetal sheep still detectable at full-term birth. In this study, changes were restricted to the inner granule layer. These cerebellar changes might correspond to some of the motor or non-motor deficits seen in neonates from compromised pregnancies.

Blood pH and gases in fetuses in preterm labor with and without systemic inflammatory response syndrome

OBJECTIVE

Fetal hypoxemia has been proposed to be one of the mechanisms of preterm labor (PTL) and delivery. This may have clinical implications since it may alter: (i) the method/frequency of fetal surveillance and (ii) the indications and duration of tocolysis to an already compromised fetus. The aim of this study was to examine whether there is a difference in the fetal blood gas analysis [pH, PaO(2) and base excess (BE)] and in the prevalence of fetal acidemia and hypoxia between: (i) patients in PTL who delivered within 72 hours vs. those who delivered more than 72 hours after cordocentesis and (ii) patients with fetal inflammatory response syndrome (FIRS) vs. those without this condition.

STUDY DESIGN

Patients admitted with PTL underwent amniocentesis and cordocentesis. Ninety women with singleton pregnancies and PTL were classified according to (i) those who delivered within 72 hours (n = 30) and after 72 hours of the cordocentesis (n = 60) and (ii) with and without FIRS. FIRS was defined as a fetal plasma concentration of IL-6 > 11 pg/mL. Fetal blood gases were determined. Acidemia and hypoxemia were defined as fetal pH and PaO(2) below the 5th percentile for gestational age, respectively. For comparisons between the two study groups, ΔpH and ΔPaO(2) were calculated by adjusting for gestational age (Δ = observed value - mean for gestational age). Non-parametric statistics were employed.

RESULTS

No differences in the median Δ pH (-0.026 vs. -0.016), ΔPaO(2) (0.25 mmHg vs. 5.9 mmHg) or BE (-2.4 vs. -2.6 mEq/L) were found between patients with PTL who delivered within 72 hours and those who delivered 72 hours after the cordocentesis (p > 0.05 for all comparisons). Fetal plasma IL-6 concentration was determined in 63% (57/90) of fetuses and the prevalence of FIRS was 28% (16/57). There was no difference in fetal pH, PaO(2) and BE between fetuses with and without FIRS (p > 0.05 for all comparisons). Moreover, there was no difference in the rate of fetal acidemia between fetuses with and without FIRS (6.3 vs. 9.8%; p > 0.05) and fetal hypoxia between fetuses with or without FIRS (12.5 vs. 19.5%; p > 0.05).

CONCLUSIONS

Our data do not support a role for acute fetal hypoxemia and metabolic acidemia in the etiology of PTL and delivery.

The impact of intermittent umbilical cord occlusions on the inflammatory response in pre-term fetal sheep

Fetal hypoxic episodes may occur antepartum with the potential to induce systemic and cerebral inflammatory responses thereby contributing to brain injury. We hypothesized that intermittent umbilical cord occlusions (UCOs) of sufficient severity but without cumulative acidosis will lead to a fetal inflammatory response. Thirty-one chronically instrumented fetal sheep at ∼0.85 of gestation underwent four consecutive days of hourly UCOs from one to three minutes duration for six hours each day. Maternal and fetal blood samples were taken for blood gases/pH and plasma interleukin (IL)-1β and IL-6 levels. Animals were euthanized at the end of experimental study with brain tissue processed for subsequent counting of microglia and mast cells. Intermittent UCOs resulted in transitory fetal hypoxemia with associated acidemia which progressively worsened the longer umbilical blood flow was occluded, but with no cumulative blood gas or pH changes over the four days of study. Fetal arterial IL-1β and IL-6 values showed no significant change regardless of the severity of the UCOs, nor was there any evident impact on the microglia and mast cell counts for any of the brain regions studied. Accordingly, intermittent UCOs of up to three minutes duration with severe, but limited fetal hypoxemia and no cumulative acidemia, do not result in either a systemic or brain inflammatory response in the pre-term ovine fetus. However, fetal IL-1B and IL-6 values were found to be well correlated with corresponding maternal values supporting the placenta as a primary source for these cytokines with related secretion into both circulations. Female fetuses were also found to have higher IL-1β levels than males, indicating that gender may impact on the fetal inflammatory response to various stimuli.

Modeling the encephalopathy of prematurity in animals: the important role of translational research

Translational research in preterm brain injury depends upon the delineation of the human neuropathology in order that animal models faithfully reiterate it, thereby ensuring direct relevance to the human condition. The major substrate of human preterm brain injury is the encephalopathy of prematurity that is characterized by gray and white matter lesions reflecting combined acquired insults, altered developmental trajectories, and reparative phenomena. Here we highlight the key features of human preterm brain development and the encephalopathy of prematurity that are critical for modeling in animals. The complete mimicry of the complex human neuropathology is difficult in animal models. Many models focus upon mechanisms related to a specific feature, for example, loss of premyelinating oligodendrocytes in the cerebral white matter. Nevertheless, animal models that simultaneously address oligodendrocyte, neuronal, and axonal injury carry the potential to decipher shared mechanisms and synergistic treatments to ameliorate the global consequences of the encephalopathy of prematurity.

Changes in fetal thymic immune cell populations in a sheep model of intrauterine inflammation

Intrauterine inflammation is a common antecedent of preterm birth and can alter the development of the fetal thymus, the site of development, and maturation of T lymphocytes. The effects of intrauterine inflammation on specific thymic T lymphocyte populations are largely unknown. We hypothesized that intrauterine inflammation would alter fetal thymic T cell populations. Immunohistochemistry was used to quantitate the relative proportions of thymic cortical and medullary cell populations in fetal sheep 7 days after intra-amniotic lipopolysaccharide (LPS) injection. The proportions of CD8⁺and MHC II⁺ cells in the fetal thymus were reduced in response to LPS. The ratio of CD4:CD8 cells was increased by LPS exposure. No changes were observed in the percentage of CD4⁺, γδ(WC1)⁺, CD45R⁺B cells, or CD44⁺ cells. These studies indicate that intrauterine inflammation impacts thymic composition of CD8 T cells and the development and/or activation of CD4 T cells in the fetal thymus.

Inflammation during fetal and neonatal life: implications for neurologic and neuropsychiatric disease in children and adults

Inflammation is increasingly recognized as being of both physiological and pathological importance in the immature brain. The rationale of this review is to present an update on this topic with focus on long-term consequences of inflammation during childhood and in adults. The immature brain can be exposed to inflammation in connection with viral or bacterial infection during pregnancy or as a result of sterile central nervous system (CNS) insults. Through efficient anti-inflammatory and reparative processes, inflammation may resolve without any harmful effects on the brain. Alternatively, inflammation contributes to injury or enhances CNS vulnerability. Acute inflammation can also be shifted to a chronic inflammatory state and/or adversely affect brain development. Hypothetically, microglia are the main immunocompetent cells in the immature CNS, and depending on the stimulus, molecular context, and timing, these cells will acquire various phenotypes, which will be critical regarding the CNS consequences of inflammation. Inflammation has long-term consequences and could speculatively modify the risk of a variety of neurological disorders, including cerebral palsy, autism spectrum disorders, schizophrenia, multiple sclerosis, cognitive impairment, and Parkinson disease. So far, the picture is incomplete, and data mostly experimental. Further studies are required to strengthen the associations in humans and to determine whether novel therapeutic interventions during the perinatal period can influence the occurrence of neurological disease later in life.

The Long and the Short of it: Gene and Environment Interactions During Early Cortical Development and Consequences for Long-Term Neurological Disease

Cortical development is a complex amalgamation of proliferation, migration, differentiation, and circuit formation. These processes follow defined timescales and are controlled by a combination of intrinsic and extrinsic factors. It is currently unclear how robust and flexible these processes are and whether the developing brain has the capacity to recover from disruptions. What is clear is that there are a number of cognitive disorders or conditions that are elicited as a result of disrupted cortical development, although it may take a long time for the full pathophysiology of the conditions to be realized clinically. The critical window for the manifestation of a neurodevelopmental disorder is prolonged, and there is the potential for a complex interplay between genes and environment. While there have been extended investigations into the genetic basis of a number of neurological and mental disorders, limited definitive associations have been discovered. Many environmental factors, including inflammation and stress, have been linked to neurodevelopmental disorders, and it may be that a better understanding of the interplay between genes and environment will speed progress in this field. In particular, the development of the brain needs to be considered in the context of the whole materno-fetal unit as the degree of the metabolic, endocrine, or inflammatory responses, for example, will greatly influence the environment in which the brain develops. This review will emphasize the importance of extending neurodevelopmental studies to the contribution of the placenta, vasculature, cerebrospinal fluid, and to maternal and fetal immune response. These combined investigations are more likely to reveal genetic and environmental factors that influence the different stages of neuronal development and potentially lead to the better understanding of the etiology of neurological and mental disorders such as autism, epilepsy, cerebral palsy, and schizophrenia.

Inflammation in utero exacerbates ventilation-induced brain injury in preterm lambs

Cerebral blood flow disturbance is a major contributor to brain injury in the preterm infant. The initiation of ventilation may be a critical time for cerebral hemodynamic disturbance leading to brain injury in preterm infants, particularly if they are exposed to inflammation in utero. We aimed to determine whether exposure to inflammation in utero alters cardiopulmonary hemodynamics, resulting in cerebral hemodynamic disturbance and related brain injury during the initiation of ventilation. Furthermore, we aimed to determine whether inflammation in utero alters the cerebral hemodynamic response to challenge induced by high mean airway pressures. Pregnant ewes received intra-amniotic lipopolysaccharide (LPS) or saline either 2 or 4-days before preterm delivery (at 128 ± 1 days of gestation). Lambs were surgically instrumented for assessment of pulmonary and cerebral hemodynamics before delivery and positive pressure ventilation. After 30 min, lambs were challenged hemodynamically by incrementing and decrementing positive end-expiratory pressure. Blood gases, arterial pressures, and blood flows were recorded. The brain was collected for biochemical and histological assessment of inflammation, brain damage, vascular extravasation, hemorrhage, and oxidative injury. Carotid arterial pressure was higher and carotid blood flow was more variable in 2-day LPS lambs than in controls during the initial 15 min of ventilation. All lambs responded similarly to the hemodynamic challenge. Both 2- and 4-day LPS lambs had increased brain interleukin (IL)-1β, IL-6, and IL-8 mRNA expression; increased number of inflammatory cells in the white matter; increased incidence and severity of brain damage; and vascular extravasation relative to controls. Microvascular hemorrhage was increased in 2-day LPS lambs compared with controls. Cerebral oxidative injury was not different between groups. Antenatal inflammation causes adverse cerebral hemodynamics and increases the incidence and severity of brain injury in ventilated preterm lambs.

Distribution of Lesions in Fetal Brains Following Experimental Infection of Pregnant Sheep With Toxoplasma gondii

Six ovine fetal brains were harvested 33 to 35 days postchallenge from 5 ewes, each of which was given 3000 Toxoplasma gondii oocysts on day 90 of pregnancy. Histopathologic examination of transverse sections taken at 13 levels in the fetal brains revealed the presence of toxoplasmosis-related lesions in all 6 brains. However, lesions were not randomly distributed ( P = .007); they were most numerous at the level of the optic tract, the rostral margin of the pons, and 4 mm caudal to the ansate sulcus and were absent in all sections at the level of the caudal cerebellum. Lesion distribution may be due to hemodynamic factors, differences in the expression of endothelial surface receptor molecules at the level of the blood-brain barrier, or the presence of localized permissive/inhibitory factors within the brain. The results have implications for the selection of areas of brain from aborted ovine fetuses to be examined histopathologically for laboratory diagnosis.

Proinflammatory and proapoptotic markers in relation to mono and di-cations in plasma of autistic patients from Saudi Arabia

Objectives

Autism is a developmental disorder characterized by social and emotional deficits, language impairments and stereotyped behaviors that manifest in early postnatal life. This study aims to clarify the relationship amongst absolute and relative concentrations of K⁺, Na⁺, Ca²⁺, Mg²⁺ and/or proinflammatory and proapoptotic biomarkers.

Materials and methods

Na⁺, K⁺, Ca²⁺, Mg²⁺, Na⁺/K⁺, Ca²⁺/Mg²⁺ together with IL6, TNFα as proinflammatory cytokines and caspase3 as proapoptotic biomarker were determined in plasma of 25 Saudi autistic male patients and compared to 16 age and gender matching control samples.

Results

The obtained data recorded that Saudi autistic patients have a remarkable lower plasma caspase3, IL6, TNFα, Ca²⁺ and a significantly higher K⁺ compared to age and gender matching controls. On the other hand both Mg²⁺ and Na⁺ were non-significantly altered in autistic patients. Pearson correlations revealed that plasma concentrations of the measured cytokines and caspase-3 were positively correlated with Ca²⁺ and Ca²⁺/K⁺ ratio. Reciever Operating Characteristics (ROC) analysis proved that the measured parameters recorded satisfactory levels of specificity and sensitivity.

Conclusion

Alteration of the selected measured ions confirms that oxidative stress and defective mitochondrial energy production could be contributed in the pathogenesis of autism. Moreover, it highlights the relationship between the measured ions, IL6, TNFα and caspase3 as a set of signalling pathways that might have a role in generating this increasingly prevalent disorder. The role of ions in the possible proinflammation and proapoptic mechanisms of autistics' brains were hypothesized and explained.

The biological basis of injury and neuroprotection in the fetal and neonatal brain

A compromised intrauterine environment that delivers low levels of oxygen and/or nutrients, or is infected or inflammatory, can result in fetal brain injury, abnormal brain development and in cases of chronic compromise, intrauterine growth restriction. Preterm birth can also be associated with injury to the developing brain and affect the normal trajectory of brain growth. This review will focus on the effects that episodes of perinatal hypoxia (acute, chronic, associated with inflammation or as an antecedent of preterm birth) can have on the developing brain. In animal models of these conditions we have found that relatively brief (acute) periods of fetal hypoxemia can have significant effects on the fetal brain, for example death of susceptible neuronal populations (cerebellum, hippocampus, cortex) and cerebral white matter damage. Chronic placental insufficiency which includes fetal hypoxemia, nutrient restriction and altered endocrine status can result in fetal growth restriction and long-term deficits in neural connectivity in addition to altered postnatal function, for example in the auditory and visual systems. Maternal/fetal inflammation can result in fetal brain damage, particularly but not exclusively in the white matter; injury is more pronounced when associated with fetal hypoxemia. In the baboon, in which the normal trajectory of growth is affected by preterm birth, there is a direct correlation between a higher flux in oxygen saturation and a greater extent of neuropathological damage. Currently, the only established therapy for neonatal encephalopathy in full term neonates is moderate hypothermia although this only offers some protection to moderately but not severely affected brains. There is no accepted therapy for injured preterm brains. Consequently the search for more efficacious treatments continues; we discuss neuroprotective agents (erythropoietin, N-acetyl cysteine, melatonin, creatine, neurosteroids) which we have trialed in appropriate animal models. The possibility of combining hypothermia with such agents or growth factors is now being considered. A deeper understanding of causal pathways in brain injury is essential for the development of efficacious strategies for neuroprotection.

Fetal lipopolysaccharide exposure modulates diet-dependent gut maturation and sensitivity to necrotising enterocolitis in pre-term pigs

Uterine infections during pregnancy predispose to pre-term birth and postnatal morbidity, but it is unknown how prenatal bacterial exposure affects maturation of the immature gut. We hypothesised that a prenatal exposure to gram-negative lipopolysaccharide (LPS) has immunomodulatory effects that improve resistance towards necrotising enterocolitis (NEC) in pre-term neonates. At approximately 85 % gestation, pig fetuses were injected intramuscularly with saline or LPS (0·014 mg/kg), or intra-amniotically with LPS (0·4 mg/kg). Pigs were delivered by caesarean section 3-5 d later and fed colostrum (C) or formula (F) for 48 h. Gut indices did not differ between pigs injected intramuscularly with saline or LPS, and these groups were therefore pooled into two control groups according to diet (control-F, n 32 and control-C, n 11). Control-F pigs showed reduced villus heights, mucosal structure, gut integrity, digestive enzymes, elevated NEC incidence (38 v. 0 %, P < 0·05) and several differentially expressed immune-related genes, relative to control-C pigs. Compared with the control-F and control-C groups, values in formula-fed pigs given intra-amniotic LPS formula (n 17) were intermediate for villus height, enzyme activities, intestinal permeability and NEC incidence (18 %, P = 0·2 relative to control-F), and numbers of differentially expressed immune genes. In conclusion, prenatal exposure of the fetal gut to Gram-negative bacteria may modulate the immediate postnatal response to an enteral diet and colonising bacteria.

The impact of chronic intrauterine inflammation on the physiologic and neurodevelopmental consequences of intermittent umbilical cord occlusion in fetal sheep

OBJECTIVE

To determine the effect of intrauterine inflammation on fetal responses to umbilical cord occlusion (UCO).

STUDY DESIGN

In pregnant sheep, lipopolysaccharide (LPS) or saline (SAL) was infused intra-amniotically for 4 weeks from 80 days of gestation (d). At 110 d, fetuses were instrumented for UCOs (5 × 2-minutes, 30-minute intervals: LPS + UCO, n = 6; SAL + UCO, n = 8) or no UCO (sham, n = 6) on 117 and 118 d. Tissues were collected at 126 d.

RESULTS

Fetal physiological responses to UCO were similar between LPS + UCO and SAL + UCO. Histologic chorioamnionitis and increased amniotic fluid interleukin 8 (IL-8) were observed in LPS + UCO pregnancies (versus SAL + UCO, P < .05). CNPase-positive oligodendrocyte number in the cerebral white matter was lower in LPS + UCO and SAL + UCO than sham (P < .05); there was no effect on astrocytes or activated microglia/macrophages. Two of the SAL + UCO fetuses had white matter lesions; none were observed in LPS + UCO or sham.

CONCLUSION

Chronic pre-existing intrauterine inflammation did not exacerbate fetal brain injury induced by intermittent UCO.

The neural and vascular effects of killed Su-Streptococcus pyogenes (OK-432) in preterm fetal sheep

Fetal exposure to inflammatory mediators is associated with a greater risk of brain injury and may cause endothelial dysfunction; however, nearly all the evidence is derived from gram-negative bacteria. Intrapleural injections of OK-432, a killed Su-strain of Streptococcus pyogenes, has been used to treat fetal chylothorax. In this study, we evaluated the neural and cardiovascular effects of OK-432 in preterm fetal sheep (104 +/- 1 days, term 147 days). OK-432 (0.1 mg, n = 6) or saline vehicle (n = 7) was infused in the fetal pleura, and fetuses were monitored for 7 days. Blood samples were taken routinely for plasma nitrite measurement. Fetal brains were taken for histological assessment at the end of the experiment. Between 3 and 7 h postinjection, OK-432 administration was associated with transient suppression of fetal body and breathing movements and electtroencephalogram activity (P < 0.05), increased carotid and femoral vascular resistance (P < 0.05), but no change in blood pressure. Brain activity and behavior then returned to normal except in one fetus that developed seizures. OK-432 fetuses showed progressive, sustained vasodilatation (P < 0.05), with lower blood pressure after 4 days (P < 0.05), but normal heart rate. There were no changes in plasma nitrite levels. Histological studies showed bilateral infarction in the dorsal limb of the hippocampus of the fetus that developed seizures, but no injury in other fetuses. We conclude that a single low-dose injection of OK-432 can be associated with risk of focal cerebral injury in the preterm fetus and chronic central and peripheral vasodilatation that does not appear to be mediated by nitric oxide.

Erythropoietin is neuroprotective in a preterm ovine model of endotoxin-induced brain injury

Intrauterine infection and inflammation have been linked to preterm birth and brain damage. We hypothesized that recombinant human erythropoietin (rhEPO) would ameliorate brain damage in anovine model of fetal inflammation. At 107 +/- 1 day of gestational age (DGA), chronically catheterized fetal sheep received on 3 consecutive days 1) an intravenous bolus dose of lipopolysaccharide ([LPS] approximately 0.9 microg/kg; n = 8); 2) an intravenous bolus dose of LPS, followed at 1 hour by 5,000 IU/kg of rhEPO (LPS + rhEPO, n = 8); or 3) rhEPO (n = 5). Untreated fetuses (n = 8) served as controls. Fetal physiological parameters were monitored, and fetal brains and optic nerves were histologically examined at 116 +/- 1 DGA. Exposure to LPS, but not to rhEPO alone or saline, resulted in fetal hypoxemia, hypotension (p < 0.05), brain damage, including white matter injury, and reductions in numbers of myelinating oligodendrocytes in the corticospinal tract and myelinated axons in the optic nerve (p < 0.05 for both). Treatment of LPS-exposed fetuses with rhEPO did not alter the physiological effects of LPS but reduced brain injury and was beneficial to myelination in the corticospinal tract and the optic nerve. This is the first study in a long-gestation species to demonstrate the neuroprotective potential of rhEPO in reducing fetal brain and optic nerve injury after LPS exposure.

Acute and chronic effects of endotoxin on cerebral circulation in lambs

The impact of endotoxemia on cerebral endothelium and cerebral blood flow (CBF) regulation was studied in conscious newborn lambs. Bacterial endotoxin [LPS, 2 μg/kg iv] was infused on 3 consecutive days. Cerebrovascular function was assessed by monitoring CBF and cerebral vascular resistance (CVR) over 12 h each day and by the endothelium-dependent vasodilator bradykinin (BK) ( n = 10). Inflammatory responses were assessed by plasma tumor necrosis factor-α (TNF-α, n = 5). Acutely, LPS disrupted the cerebral circulation within 1 h, with peak cerebral vasoconstriction at 3 h (CBF −28 and CVR +118%, P < 0.05) followed by recovery to baseline by 12 h. TNF-α and body temperature peaked ∼1 h post-LPS. BK-induced vasodilatation (CVR −20%, P < 0.05) declined with each LPS infusion, was abolished after 3 days, and remained absent for at least the subsequent 5 days. Histological evidence of brain injury was found in four of five LPS-treated newborns. We conclude that endotoxin impairs cerebral perfusion in newborn lambs via two mechanisms: 1) acute vasoconstriction (over several hours); and 2) persistent endothelial dysfunction (over several days). Endotoxin-induced circulatory impairments may place the newborn brain at prolonged risk of CBF dysregulation and injury as a legacy of endotoxin exposure.

Erythropoietin ameliorates damage to the placenta and fetal liver induced by exposure to lipopolysaccharide

Intrauterine infection and inflammation have been causally linked to preterm birth and fetal brain injury. Using an ovine model of endotoxin-induced brain injury we have recently shown that recombinant human erythropoietin (rhEPO) reduces brain injury and protects against damage to myelination in major myelinated axon tracts. Our present objective was to determine whether rhEPO is also protective of the placenta and the fetal liver, organs which could influence fetal well-being. At 107 +/- 1 days of gestational age (DGA) chronically catheterized fetal sheep were randomly assigned to receive, on 3 consecutive days, either: 1) an i.v. bolus dose of lipopolysaccharide (LPS; approximately 0.9 microg/kg; n = 8); 2) i.v. bolus dose of LPS, followed at 1 h by 5000 IU/kg of rhEPO (LPS + rhEPO, n = 8); 3) rhEPO (n = 3). Seven untreated fetuses served as controls (n = 7). The placenta and fetal liver were examined histologically at 116 +/- 1 DGA; a placental injury index was formulated comprising measures of placental area, apoptosis, tissue injury and the size of the intervillous space. In LPS-exposed fetuses this index was greater than in control or rhEPO alone fetuses (p < 0.02). Treatment of LPS-exposed fetuses with rhEPO resulted in a reduction in the index (p < 0.05) and in the extent of liver necrosis. We conclude that rhEPO offers protection to the placenta and fetal liver in the presence of acute inflammation.

Systemic and cerebral inflammatory response to umbilical cord occlusions with worsening acidosis in the ovine fetus

OBJECTIVE

We hypothesized that repetitive umbilical cord occlusions (UCOs) with worsening acidosis will lead to a fetal inflammatory response.

STUDY DESIGN

Chronically instrumented fetal sheep underwent a series of UCOs until fetal arterial pH decreased to <7.00. Maternal and fetal blood samples were taken for blood gases/pH and plasma interleukin (IL)-1B and IL-6 levels. Animals were euthanized at 24 hours of recovery with brain tissue processed for subsequent measurement of microglia and mast cell counts.

RESULTS

Repetitive UCOs resulted in a severe degree of fetal acidemia. Fetal plasma IL-1B values were increased approximately 2-fold when measured at maximal fetal acidosis and again at 1-2 hours of recovery. Fetal microglia cells were increased approximately 2-fold in the white matter and hippocampus, while mast cells were increased approximately 2-fold in the choroid plexus and now evident in the thalamus when analyzed at 24 hours recovery.

CONCLUSION

Repetitive UCOs leading to severe acidemia in the ovine fetus near term will result in an inflammatory response both systemically and locally within the brain.

A history of our understanding of cerebral vascular development and pathogenesis of perinatal brain damage over the past 30 years

This article reviews our studies focusing on cerebral vascular development, the pathogenesis of subependymal/intraventricular hemorrhage (SEH/IVH), periventricular leukomalacia (PVL), and pontosubicular neuron necrosis (PSN). Their pathogenesis consists of predisposing developmental and causal factors. SEH/IVH may be caused by reperfusion or overperfusion following ischemia in the subependymal germinal matrix with characteristic vasculature. The cause of PVL is multifactorial (ie, ischemia and inflammation), predisposed by the maturational status of the vasculature and oligodendroglia in the white matter. Focal PVL is ischemic necrosis, and diffuse PVL or white matter injury may include cytotoxic damage. PSN has an apoptotic character, and may be induced by ischemic and oxidative stress on specific immature neurons. Further studies on preventive and therapeutic measures are necessary in clinical, pathologic, and experimental fields. The monitoring and control methods of brain hemodynamics and cellular stability should be more developed to prevent brain damages.

Fetal inflammatory response and brain injury in the preterm newborn

Preterm birth can be caused by intrauterine infection and maternal/fetal inflammatory responses. Maternal inflammation (chorioamnionitis) is often followed by a systemic fetal inflammatory response characterized by elevated levels of proinflammatory cytokines in the fetal circulation. The inflammation signal is likely transmitted across the blood-brain barrier and initiates a neuroinflammatory response. Microglial activation has a central role in this process and triggers excitotoxic, inflammatory, and oxidative damage in the developing brain. Neuroinflammation can persist over a period of time and sensitize the brain to subinjurious insults in early and chronic phases but may offer relative tolerance in the intermediate period through activation of endogenous anti-inflammatory, protective, and repair mechanisms. Neuroinflammatory injury not only destroys what exists but also changes what develops.

Effect of intrauterine inflammation on fetal cerebral hemodynamics and white-matter injury in chronically instrumented fetal sheep

OBJECTIVE

The purpose of this study was to analyze the effects of intrauterine inflammation on cerebral hemodynamics and white-matter injury in premature fetal sheep.

STUDY DESIGN

Fetuses were given an intravenous infusion of granulocyte colony-stimulating factor and an intraamniotic infusion of endotoxin; the fetuses were then assigned randomly to an acute hemorrhage group, an exchange transfusion group, or a control group. During each insult, the cerebral hemodynamics were assessed with near-infrared spectroscopy. Finally, the fetuses were processed for neuropathologic analysis and compared statistically.

RESULTS

Necrotizing funisitis and chorioamnionitis were induced in all the fetuses. A significant decrease in the blood oxygen content and an increase in the brain total hemoglobin level were observed after the endotoxin infusion. Soon after hemodynamic insult, the fetuses in both the acute hemorrhage and the exchange transfusion groups showed an abrupt decrease in the total brain hemoglobin level; 4 of the 5 fetuses in each treatment group, but none of the fetuses in the control group, exhibited periventricular leukomalacia.

CONCLUSION

Hemorrhagic hypotension or anemic hypoxemia might induce a sudden cessation of fetal brain-sparing effects through progressive inflammatory hypoxemia, which results in focal white-matter injuries.

Endotoxin has acute and chronic effects on the cerebral circulation of fetal sheep

We studied the impact of endotoxemia on cerebral blood flow (CBF), cerebral vascular resistance (CVR), and cerebral oxygen transport (O2 transport) in fetal sheep. We hypothesized that endotoxemia impairs CBF regulation and O2 transport, exposing the brain to hypoxic-ischemic injury. Responses to lipopolysaccharide (LPS; 1 μg/kg iv on 3 consecutive days, n = 9) or normal saline ( n = 5) were studied. Of LPS-treated fetuses, five survived and four died; in surviving fetuses, transient cerebral vasoconstriction at 0.5 h (ΔCVR approximately +50%) was followed by vasodilatation maximal at 5–6 h (ΔCVR approximately −50%) when CBF had increased (approximately +60%) despite reduced ABP (approximately −20%). Decreased CVR and increased CBF persisted 24 h post-LPS and the two subsequent LPS infusions. Cerebral O2 transport was sustained, although arterial O2 saturation was reduced ( P < 0.05). Histological evidence of neuronal injury was found in all surviving LPS-treated fetuses; one experienced grade IV intracranial hemorrhage. Bradykinin-induced cerebral vasodilatation (ΔCVR approximately −20%, P < 0.05) was abolished after LPS. Fetuses that died post-LPS ( n = 4) differed from survivors in three respects: CVR did not fall, CBF did not rise, and O2 transport fell progressively. In conclusion, endotoxin disrupts the cerebral circulation in two phases: 1) acute vasoconstriction (1 h) and 2) prolonged vasodilatation despite impaired endothelial dilatation (24 h). In surviving fetuses, LPS causes brain injury despite cerebral O2 transport being maintained by elevated cerebral perfusion; thus sustained O2 transport does not prevent brain injury in endotoxemia. In contrast, cerebral hypoperfusion and reduced O2 transport occur in fetuses destined to die, emphasizing the importance of sustaining O2 transport for survival.

Bacterial cell wall products increases stabilization of HIF-1 alpha in an oligodendrocyte cell line preconditioned by cobalt chloride or desferrioxamine

We examined the effect of lipopolysaccharide (LPS) or lipotechoic acid (LTA) on the regulation of hypoxia inducible factor (HIF-1) alpha on the MO3.13 cells, a human oligodendroglial cell line. Our study shows that MO3.13 cells express the toll like receptors (TLR's) but do not increase cellular levels of HIF-1 alpha following exposure to bacterial cell wall products. When MO3.13 cells were preconditioned by desferrioxamine (DFO) or cobalt chloride (CoCl(2)) and then treated with either LPS or LTA, HIF-1 alpha levels were higher than that induced by DFO or CoCl(2) alone. The increase in HIF-1 alpha was due to increased protein stability that was mediated by activation of the ERK-MAP kinase pathway.

Recurrent postnatal infections are associated with progressive white matter injury in premature infants

OBJECTIVE

Our objective was to identify clinical predictors of progressive white matter injury.

METHODS

We evaluated 133 infants of <34 weeks of gestation at birth from 2 university hospitals. Infants underwent MRI twice, initially when in stable condition for transport and again at term-equivalent age or before transfer or discharge. Two neuroradiologists who were blinded to the clinical course graded MRI white matter injury severity by using a validated scale. Potential risk factors were extracted from medical charts.

RESULTS

Twelve neonates (9.0%) had progressive white matter injury. In the unadjusted analysis of 10 newborns without Candida meningoencephalitis, recurrent culture-positive postnatal infection and chronic lung disease were associated with progressive white matter injury. Exposure to multiple episodes of culture-positive infection significantly increased the risk of progressive white matter injury. Of the 11 neonates with >1 infection, 36.4% (4 infants) had progressive injury, compared with 5.0% (6 infants) of those with <or=1 infection. Of the 35 infants with chronic lung disease, 17.1% (6 infants) had progressive injury, compared with 4.3% (4 infants) of those without chronic lung disease. After adjustment for gestational age at birth, the association between infection and white matter injury persisted, whereas chronic lung disease was no longer a statistically significant risk factor.

CONCLUSIONS

Recurrent postnatal infection is an important risk factor for progressive white matter injury in premature infants. This is consistent with emerging evidence that white matter injury is attributable to oligodendrocyte precursor susceptibility to inflammation, hypoxia, and ischemia.

Alcohol, intestinal bacterial growth, intestinal permeability to endotoxin, and medical consequences: summary of a symposium

This report is a summary of the symposium on Alcohol, Intestinal Bacterial Growth, Intestinal Permeability to Endotoxin, and Medical Consequences, organized by National Institute on Alcohol Abuse and Alcoholism, Office of Dietary Supplements, and National Institute of Diabetes and Digestive and Kidney Diseases of National Institutes of Health in Rockville, Maryland, October 11, 2006. Alcohol exposure can promote the growth of Gram-negative bacteria in the intestine, which may result in accumulation of endotoxin. In addition, alcohol metabolism by Gram-negative bacteria and intestinal epithelial cells can result in accumulation of acetaldehyde, which in turn can increase intestinal permeability to endotoxin by increasing tyrosine phosphorylation of tight junction and adherens junction proteins. Alcohol-induced generation of nitric oxide may also contribute to increased permeability to endotoxin by reacting with tubulin, which may cause damage to microtubule cytoskeleton and subsequent disruption of intestinal barrier function. Increased intestinal permeability can lead to increased transfer of endotoxin from the intestine to the liver and general circulation where endotoxin may trigger inflammatory changes in the liver and other organs. Alcohol may also increase intestinal permeability to peptidoglycan, which can initiate inflammatory response in liver and other organs. In addition, acute alcohol exposure may potentiate the effect of burn injury on intestinal bacterial growth and permeability. Decreasing the number of Gram-negative bacteria in the intestine can result in decreased production of endotoxin as well as acetaldehyde which is expected to decrease intestinal permeability to endotoxin. In addition, intestinal permeability may be preserved by administering epidermal growth factor, l-glutamine, oats supplementation, or zinc, thereby preventing the transfer of endotoxin to the general circulation. Thus reducing the number of intestinal Gram-negative bacteria and preserving intestinal permeability to endotoxin may attenuate alcoholic liver and other organ injuries.