Maternal intrauterine infection, cytokines, and brain damage in the preterm newborn

Adverse neurodevelopmental outcomes among extremely low birth weight infants with a normal head ultrasound: prevalence and antecedents

OBJECTIVE

Severe abnormalities of the head ultrasound (HUS) are important predictors of cerebral palsy (CP) and mental retardation, and a normal HUS usually ensures the absence of major impairments. With the increasing survival of extremely low birth weight (ELBW) infants (birth weight <1000 g), the prognostic significance of a normal HUS may differ. This study examined the prevalence of and risk factors for CP and impaired mental development among ELBW infants with a normal HUS.

METHODS

Study infants were ELBW infants who were cared for in Neonatal Research Network centers in the years 1995-1999, had a normal early and late HUS, survived to discharge, and returned for follow-up assessments at 18 to 22 months' corrected age. The outcomes of interest were a score <70 on the Bayley Scales of Infant Development-II Mental Developmental Index (MDI) and CP. Risk factors included maternal demographics; infant characteristics; and interventions or morbidities related to the lung, infection, and nutrition. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). A time-oriented approach was used to select variables for inclusion in logistic models.

RESULTS

Of 1749 infants with a normal early and late HUS (performed at a mean age of 6 and 47 days, respectively), 1473 (84%) returned for follow-up assessment. Infants had a birth weight of 792 +/- 134 g (mean +/- SD) and gestational age of 26 +/- 2 weeks. Rates of CP and MDI <70 were 9.4% and 25.3%, respectively, and 29.2% of infants had either CP or MDI <70. In multivariate analyses, factors associated with CP were male gender (OR: 1.8; 95% CI: 1.2-2.6), multiple birth, (OR: 1.6; 95% CI: 1.1-2.5), decreasing birth weight (OR: 1.3 for each 100-g decrease; 95% CI: 1.1-1.5), pneumothorax (OR: 2.3; 95% CI: 1.2-4.4), and days of conventional ventilation (OR: 1.2 for each additional 10 days; 95% CI: 1.1-1.3). With the exception of pneumothorax, these same factors were associated with MDI <70, in addition to less maternal education (OR: 1.4; 95% CI: 1.0-1.9) and Medicaid or lack of coverage for maternal insurance (OR: 1.7; 95% CI: 1.2-2.4).

CONCLUSIONS

Nearly 30% of ELBW infants with a normal HUS had either CP or a low MDI. Risk factors that are associated with this high rate of adverse outcomes include pneumothorax, prolonged exposure to mechanical ventilation, and educational and economic disadvantage. Improvements in pulmonary care to reduce duration of ventilation and avoid air leaks might improve neurodevelopmental outcome for ELBW infants.

A short cervix in women with preterm labor and intact membranes: a risk factor for microbial invasion of the amniotic cavity

OBJECTIVE

The purpose of this study was to determine whether there was a relationship between sonographic cervical length and the presence of culture-proven microbial invasion of the amniotic cavity in women with preterm labor and intact membranes.

STUDY DESIGN

Ultrasonography and amniocentesis were performed in 401 patients admitted with preterm labor (22-35 weeks) and cervical dilatation of < or = 3 cm, as assessed by digital examination. Cervical length was determined by transvaginal ultrasound at admission. Outcome variables were the presence of microbial invasion of the amniotic cavity (defined as a positive amniotic fluid culture) and the occurrence of preterm delivery before 35 weeks. Contingency tables, chi2 test, receiver-operator characteristic (ROC) curves, and logistic regression were used for statistical analysis.

RESULTS

The prevalence of microbial invasion of the amniotic cavity was 7% (28/401). Spontaneous preterm delivery (< or = 35 weeks) occurred in 21.4% (82/384) of patients. ROC curve analysis showed a significant relationship between the frequency of microbial invasion of the amniotic cavity and the length of the uterine cervix (area under the curve: 0.77; P < .005). Patients with a cervical length < 15 mm had a higher rate of a positive amniotic fluid culture than patients with a cervical length > or = 15 mm (26.3% [15/57] vs. 3.8% [13/344], respectively; P < .05). Moreover, patients with a short cervix (defined as < 15 mm) were more likely to deliver spontaneously before 35 weeks, 32 weeks, within 7 days, and within 48 hours of admission ( P < .05 for all comparisons). Forty percent of patients (161/401) had a cervical length > or = 30 mm. These patients had a very low risk of microbial invasion of the amniotic cavity (1.9% [3/161]), spontaneous delivery < or = 35 weeks (4.5% [7/154]), < or = 32 weeks (2.6% [2/76]), within 7 days (1.9% [3/154]), and within 48 hours (0% [0/154]) of admission.

CONCLUSION

Endovaginal ultrasonographic examination of the uterine cervix in women with preterm labor identifies patients at increased risk for intrauterine infection.

Developmental neuropathology of the second half of gestation

In this review we focus primarily on the events taking place in the second half of gestation. At second trimester end, human brain weight gain accelerates rapidly. Germinal matrix attains maximal absolute volume, only to ablate 50% over two gestational weeks. At 10 weeks of gestation interhemispheric, choroidal, and transverse fissures exist. Germinal matrix hemorrhages peak during its devolution and some of these rupture into the lateral ventricle. By 28 weeks homologous primary sulci are present, having appeared in both hemispheres at slightly different gestational ages. Secondary sulcation, during the third trimester, is hemispherically unique. Despite emphasis on neuronal vulnerability, prevalence of lesions in white matter exceeds that of gray matter and, within white matter, diffuse white matter astrocytosis prevalence exceeds that of focal necroses. Gray matter hypotensive lesions most commonly occur in the upper brainstem and thalami followed by convexity borderzone lesions causing sclerotic microgyria. White matter hypoplasia with normal gray matter volume is sometimes associated with hypomyelination.

Blood pressure in the neonate

The paper by Dannevig et al. in this issue of Acta Paediatrica carefully compares the agreement between blood pressure measurements made by three non-invasive blood pressure monitors with those made from an indwelling intra-arterial catheter. Non-invasive blood pressure monitoring is not particularly accurate for making measurements in neonates and generally overestimates the blood pressure as observed by others. Clinicians thus should be wary about using non-invasive blood pressure techniques as substitutes for monitoring by means of an intra-arterial catheter and transducer.

Pathophysiology of neonatal brain lesions: lessons from animal models of excitotoxicity

AIM

The pathophysiology of perinatal brain lesions is probably complex and multifactorial. The development and characterization of distinct yet complementary animal models should help to unravel the cellular and molecular mechanisms underlying perinatal brain lesions. This paper reviews experimental data obtained in animal models of neonatal excitotoxic brain lesions that closely mimic some of the lesions found in human cerebral palsy.

CONCLUSION

Available data point to a key role for brain macrophages and oligodendrocytes in neonatal rodent excitotoxic brain lesions and underline the impact of cytokines on these lesions.

Activation of umbilical cord endothelial cells and fetal inflammatory response in preterm infants with chorioamnionitis and funisitis

Chorioamnionitis and funisitis are associated with preterm labor and postnatal morbidity. Activation of endothelium resulting in up-regulation of adhesion molecules seems to be a key mechanism in development of organ damage. We investigated whether chorioamnionitis with or without funisitis in preterm infants induced expression and shedding of adhesion molecules in the umbilical cord and resulted in increased concentrations of E-selectin, intercellular adhesion molecule (ICAM)-1, IL-1beta, IL-6, and IL-8 in the cord blood. Data were obtained by using immunohistochemistry and ELISA. Thirty-two preterm infants were divided into three groups according to histology: chorioamnionitis with funisitis, chorioamnionitis without funisitis, and controls without signs of inflammation. ICAM-1 expression on arterial endothelium was higher with funisitis compared with chorioamnionitis alone or with the control group. Similar results for ICAM-1 expression were found in venous endothelium, vascular walls, Wharton's jelly, and amnion epithelium. Endothelial E-selectin and vascular cell adhesion molecule (VCAM)-1 expression was only induced significantly with funisitis. Serum-concentrations of soluble ICAM-1 were higher with funisitis compared with chorioamnionitis alone or control group. Similarly, concentrations of soluble E-selectin, IL-1beta, IL-6, and IL-8 were increased exclusively with funisitis. In conclusion, only chorioamnionitis with funisitis was associated with systemic inflammation and endothelial activation with up-regulation and shedding of umbilical cord adhesion molecules. We speculate that this activation of endothelium may not be limited to the umbilical cord but may also involve other organs resulting in neonatal morbidity. This underlines the importance of funisitis as a risk factor for adverse outcome.

Corticothérapie post-natale chez le prématuré : bénéfices et risques

This review examines the risk/benefit ratio of postnatal steroid treatment in preterm infants and correlates epidemiological data with special emphasis on experimental evidence concening the impact of steroid on brain development. With all regimens, steroid treatment consistently reduced the need for assisted ventilation at 28 days of postnatal age or at term. However, neither oxygen at term nor neonatal mortality has been decreased by this treatment. Conversely, respiratory benefits should be weighed against several adverse effects: hyperglycemia, hypertension, gastrointestinal bleeding or perforation, increased risk of cerebral palsy. The impact of dexamethasone on brain development and risk factors of white matter damage could be involved in the association between postnatal steroid treatment and neurological impairment in treated infants. Injectable preparations of dexamethasone contain sulphiting preservatives which could account for the alterations in neuronal maturation observed in animal models. Early use of dexamethasone should especially be avoided for postnatal steroid treatment in premature infants. Other glucocorticoids as alternatives to dexamethasone need to be evaluated in appropriate and large controlled trials with long term follow up.

Antenatal risk factors associated with the development of lenticulostriate vasculopathy (LSV) in neonates

OBJECTIVE

To determine the antenatal risk factors associated with neonatal lenticulostriate vasculopathy (LSV).

STUDY DESIGN

Women in preterm labor were randomized to magnesium sulfate (MgSO4), other tocolytic, or saline control. The surviving babies underwent head ultrasounds (HUS) (weeks of life 1, 2, and 4) and periodic developmental examinations (months 4, 8, 12, and 18).

RESULTS

Of 140 infants, 17.1% (24) had neonatal intraventricular hemorrhage (IVH), and 10.0% (14) had LSV (half of the latter (7 of 14) had both IVH and LSV). In a regression model in which other risk factors were controlled for, the association between antenatal exposures to tocolytic MgSO4 >or=50 g and LSV were significant (adjusted odds ratio (OR), 8.3; 95% confidence interval (CI), 1.5 to 45.0; p=0.01).

CONCLUSION

Based on our data and their analyses, we infer that antenatal exposure to high-dosage, tocolytic MgSO4 may be associated with LSV.

Population based study on the outcome of small for gestational age newborns

OBJECTIVE

To explore whether and how population based data from a regional quality control programme can be used to investigate the hypothesis that small for gestational age (SGA) very low birthweight infants (VLBW, <1500 g) are at increased risk of death, severe intraventricular haemorrhage (IVH), and periventricular leucomalacia (PVL), but at decreased risk of respiratory distress syndrome (RDS).

METHODS

Analyses of population based perinatal/neonatal data (1991-96) from a quality control programme in Lower Saxony, Germany. After assessment of data validity and representativeness, exclusion criteria were defined: birth weight >90th centile, severe malformations, siblings of multiple births, and gestational age (GA) <25 or >29 weeks. Outcomes of interest were death, severe IVH, PVL, and RDS. Multivariable analyses were performed by Cox proportional hazard and logistic regression models.

RESULTS

Within the data validation procedure, an increase in proportions of both VLBW (from 0.95% in 1991 to 1.11% in 1996; +17%) and SGA (from 22.7% to 27.4%; +21%) infants became apparent (p<0.05). The study population consisted of 1623 infants (173 SGA). Mortality was 12.1% (n = 196), with an adjusted hazard ratio for SGA infants of 2.54, 95% confidence interval (CI) 1.70 to 3.79. Both groups were at similar risk of severe IVH (adjusted odds ratio 0.93, 95% CI 0.5 to 1.65) and PVL (1.54, 95% CI 0.78 to 2.87), but SGA infants had less RDS (0.57, 95% CI 0.35 to 0.93). Male sex, multiple birth, hypothermia (<35.5 degrees C), and sepsis were associated with IVH and RDS. Infants admitted to hospitals with <36 VLBW admissions/year had increased mortality (adjusted hazard ratio 1.56, 95% CI 1.12 to 2.18).

CONCLUSIONS

SGA VLBW infants are at increased risk of death, but not of IVH and PVL, and at decreased risk of RDS. That mortality is higher in smaller hospitals needs further investigation.

Identification of kynurenine pathway enzyme mRNAs and metabolites in human placenta: up-regulation by inflammatory stimuli and with clinical infection

OBJECTIVE

The purpose of this study was to determine whether placental-derived kynurenines (neuroactive metabolites that are derived from tryptophan) contributes to infection-mediated fetal cerebral injury.

STUDY DESIGN

Placentae and cord blood were obtained from term deliveries (n = 16) and preterm deliveries with or without intrauterine bacterial infection (n = 8 per group). We investigated whether the placenta expressed messenger RNAs of kynurenine metabolite-forming enzymes, the effects of infection in vivo on the expression of these enzymes by the placenta, the in vitro effects of bacterial endotoxin lipopolysaccharide on expression and kynurenine metabolite output by the placenta, and the kynurenine metabolite levels in umbilical cord blood.

RESULTS

Placentae expressed messenger RNA of tryptophan-degrading enzymes and synthesized several compounds. The expression of several enzymes increased significantly in placentae that were exposed to infection and/or lipopolysaccharide. Lipopolysaccharide also induced significant increases in placental kynurenine and quinolinic acid output. Kynurenine and quinolinic acid in cord blood of fetuses who were exposed to infection were elevated significantly.

CONCLUSION

Inflammatory mediated release of kynurenines from placentae exposes the fetus to significant amounts of potentially neurotoxic substances.

The vaginal inflammatory milieu and the risk of early premature preterm rupture of membranes

OBJECTIVE

The purpose of this study was to determine the association of vaginal pH > or =5.0 and vaginal neutrophils >5 per oil field with preterm rupture of membranes (PPROM).

STUDY DESIGN

This was a secondary analysis of the Vaginal Infections and Prematurity cohort, and was comprised of 12,734 evaluable women enrolled between 23 and 26 weeks' gestation. Women were tested for sexually transmitted infections and vaginal pH. Gram-stained smears were used for the detection of neutrophils.

RESULTS

In this analysis, 5751 (41.3%) women had neutrophils >5 per oil field, and 2500 (18.0%) had pH > or =5.0. Both elevated pH and neutrophils were present in 1149 women (8.3%). The concomitant presence of both neutrophils and elevated pH was significantly associated with PPROM at 24 to 32 weeks.

CONCLUSION

Elevated vaginal pH and neutrophils are most strongly associated with early third-trimester PPROM, reflecting the importance of infection and/or inflammation in the pathogenesis of this condition.

Preterm Premature Rupture of Membranes: Is There an Optimal Gestational Age for Delivery?

OBJECTIVE

To characterize neonatal and maternal morbidity and mortality rates in pregnancies complicated by preterm premature rupture of membranes (PROM) and determine whether there is an optimal delivery gestational age.

METHODS

We reviewed maternal and neonatal outcomes of women with PROM 24 weeks or more that resulted in delivery at less than 37 weeks at our institution from August 1998 to August 2000. Standardized management included the use of antibiotics, betamethasone at less than 32 weeks, and expectant management until 24 weeks or more. Outcomes evaluated included neonatal mortality, composite major and minor neonatal morbidity, individual major and minor neonatal morbidity rates, maternal infection morbidity, and maternal and neonatal length of stay. Gestational age-specific maternal and neonatal outcomes were compared with a referent group of pregnancies complicated by preterm PROM that delivered between 36 0/7 and 36 6/7 weeks of gestation.

RESULTS

During the study interval, 430 women with preterm PROM were identified. Composite major neonatal morbidity was significantly higher among pregnancies delivered at 33 weeks of gestation or less after preterm PROM as compared with those who delivered at 36 weeks. Composite neonatal minor morbidity was significantly higher among pregnancies delivered at 34 weeks or less after preterm PROM as compared with those who delivered at 36 weeks. However, there was no improvement in the composite major and minor neonatal morbidity rates for those pregnancies delivered beyond 34 weeks of gestation. Both maternal and infant length of stay were significantly longer for cases of preterm PROM delivered at 34 weeks or less as compared with those who delivered at 36 weeks.

CONCLUSION

Our findings suggest that expectant management of women at 34 weeks and beyond is of limited benefit.

White matter injury in the immature brain: role of interleukin-18

Inflammation is likely to be important in the pathophysiology of white matter damage in the immature brain. In order to investigate the involvement of interleukin (IL)-18, we subjected 9-day-old IL-18-deficient and wild-type (WT) mice to hypoxia-ischemia (HI) (unilateral carotid ligation and exposure to 10% oxygen) and white matter injury was evaluated after 3 days by immunostaining for myelin basic protein (MBP) and neurofilament (NF). The immunoreactivity of MBP was significantly higher by 92, 49 and 21%, respectively, in subcortical white matter, striatum and thalamus in IL-18-deficient mice versus WT mice following HI. Similarly, there was a more pronounced immunoreactivity of NF by 78% in the subcortical white matter in IL-18 KO versus WT mice. IL-18 was expressed by astrocytes and microglia, whereas the IL-18 receptor was mainly found in astrocytes localized in and around the subventricular white matter. Taken together, these results indicate that release of IL-18 may play an important role in the development of white matter injury in the neonatal brain.

The Pattern of Cerebral Injury in a Primate Model of Preterm Birth and Neonatal Intensive Care

Survivors of very premature birth face an increased risk of adverse motor, cognitive, and behavior sequelae. In order to understand the pathogenesis of these adverse outcomes, an animal model of premature birth and neonatal care in a species with a close similarity to the human infant is sought. In this histological and immunohistochemical study we have defined the pattern of cerebral injury in a premature baboon model undergoing similar neonatal intensive care to that of the human premature infant. Sixteen baboons were delivered at 125 days gestation (dg; term approximately184 dg) with 14 days neonatal intensive care and were compared with gestational control brains at 125, 140, and 160 dg. The premature baboons undergoing neonatal intensive care sustained a spectrum of neuropathologies including white matter injury, hemorrhage, and ventriculomegaly, which resemble lesions frequently observed in the human premature infant. These data suggest that the premature baboon is a model with similarities in maturation and pattern of cerebral injury to the human infant that may provide useful insights of relevance to the human preterm infant.

Animal models of preterm birth

Preterm birth continues to pose a significant clinical dilemma and contributes to both acute and long-term neonatal morbidity. Despite efforts, the incidence of preterm birth has not decreased, partly because of our lack of understanding of the mechanisms that trigger parturition. Animal models are essential research tools for investigating the pathways that promote preterm parturition and for testing therapeutic interventions. Growing evidence correlates infection or inflammation with preterm birth. Consequently, many investigators have created animal models that reflect these findings. Current models of preterm parturition include diverse species, varying means of inducing an inflammatory or infectious state, and different routes of administration. Although each of these models can advance our knowledge, it is important to understand their advantages, disadvantages and unique characteristics. An understanding of such models will hopefully promote continued research that will ultimately lead to a decrease in preterm birth and an improvement in neonatal outcome.

Combination treatment of neonatal rats with hypoxia-ischemia and endotoxin induces long-lasting memory and learning impairment that is associated with extended cerebral damage

OBJECTIVE

We assessed the long-term effects of perinatal hypoxia-ischemia and endotoxin on attention and short- and long-term memory in neonatal rats with the use of behavioral tasks and brain histologic results.

STUDY DESIGN

Four hours after injections of lipopolysaccharide (1 mg/kg, intraperitoneally) or saline solution, 7-day-old Wistar rat pups were subjected to unilateral hypoxia-ischemia for 1 hour. We studied 4 groups: controls (n = 43 rats), lipopolysaccharide alone (n = 12 rats), hypoxia-ischemia alone (n = 29 rats), and combined lipopolysaccharide + hypoxia-ischemia treatment (n = 34 rats). Seven to 16 weeks after the treatment, we measured attention with a choice reaction time task, short-term memory with an 8-arm radial maze task, and long-term memory with a water maze task. At 19 weeks of age, the brain was removed, fixed, and sectioned coronally; and the volume of each part was measured.

RESULTS

A loss of volume in the hippocampus was observed in the lipopolysaccharide, hypoxia-ischemia, and lipopolysaccharide + hypoxia-ischemia groups; a loss of striatum was observed in the hypoxia-ischemia and lipopolysaccharide + hypoxia-ischemia groups, but loss of cortex was observed only in the lipopolysaccharide + hypoxia-ischemia group. The lipopolysaccharide, hypoxia-ischemia, and lipopolysaccharide + hypoxia-ischemia groups showed significantly poorer performance (attention deficit) than controls in the choice reaction time task. Correct choices decreased, and error increased in the lipopolysaccharide + hypoxia-ischemia group compared with the other groups in the radial maze task, which shows short-term memory impairment. Swimming distance was significantly greater in the hypoxia-ischemia and lipopolysaccharide + hypoxia-ischemia groups than in the other 2 groups in the water maze test, which shows long-term memory impairment.

CONCLUSION

Combined lipopolysaccharide and hypoxia-ischemia treatment synergistically induced short-term memory impairment that is associated with loss of cortical volume.

The effect of the anti-inflammatory cytokines interleukin-4 and interleukin-10 on lipopolysaccharide-stimulated production of prostaglandin E2 by cultured human decidual cells

OBJECTIVE

We hypothesized that interleukin-4 (IL-4) and interleukin-10 (IL-10) diminish production of PGE2 by lipopolysaccharide (LPS)-stimulated cultured human decidual cells.

STUDY DESIGN

Decidual cells from six women undergoing elective cesarean delivery without labor at term were cultured to confluence and incubated with LPS (10 ng/mL) with and without IL-4 and IL-10 (10 ng/mL) and the supernatant assayed for PGE2.

RESULTS

PGE2 concentration in non-treated cells (NT) was 16,693+/-8991 pg/mL and in cells incubated with IL-4 alone was 13,490+/-5729 pg/mL, not statistically different from that of the NT cells. Incubation with LPS increased PGE2 concentration (32,540+/-18,795 pg/mL) compared to NT cells (p=0.02). PGE2 concentration in cells co-incubated with IL-4 and LPS (8975+/-5249 pg/mL) was lower than in the LPS-alone group (p=0.005). PGE2 concentration in cells co-incubated with IL-10 and LPS was 29,644+/-25,085 pg/mL, not different from the LPS-alone group.

CONCLUSIONS

IL-4 reduced LPS-stimulated PGE2 production in decidual cells while IL-10 did not. IL-4 is a potential immunomodulatory agent in decidual inflammation.

Non-human primate models of neonatal brain injury

Nonhuman primate species have been selectively used in the scientific investigation of adult and newborn neurological diseases. The rhesus monkey has been utilized in models of term asphyxial insults, accurately reflecting the mechanisms and neuropathology demonstrated in the newborn human infant. More recently, a premature baboon model developed for evaluation of bronchopulmonary dysplasia has been applied to the investigation of cerebral development and injury, revealing high similarity in neuropathology to the premature human infant. Given the differences in the outcomes of neuroprotective therapies between lower order species, such as the rat, and human trials in disorders such as stroke, nonhuman primate models may provide an invaluable resource for safety and efficacy testing before trials in human newborns. This article summarizes both models of brain injury. The histologic findings from the models are compared with neuropathological studies in human infants.

Fetal and neonatal inflammatory response and adverse outcome

This article will define the concept of fetal/neonatal inflammatory response, and examine the complex interaction between inflammation and neurotoxicity. There appear to be important interactions between infection/inflammation and hypoxia-ischaemia leading to cytokine release and subsequent brain injury. This article will also define adverse outcome and summarize the complexities inherent to neurodevelopmental assessment. Finally, this article will investigate the currently available evidence suggesting a link between inflammatory response and adverse neurodevelopmental outcome, and focus on those variables that need further study: timing and nature of the infectious/inflammatory process; established and new anti-insult strategies; morbidity in organs other than the brain; genetic influences; and environmental factors.

Maternal poly I:C exposure during pregnancy regulates TNF alpha, BDNF, and NGF expression in neonatal brain and the maternal-fetal unit of the rat

Maternal infection during pregnancy is associated with increased risk for neurodevelopmental disorders. Polyriboinosinic-polyribocytidilic acid (poly I:C) or saline was administered to rats to model maternal infection; levels of TNFalpha, brain-derived neurotrophic factor (BDNF), and nerve growth factor (NGF) were determined by ELISA. TNFalpha was significantly increased in maternal plasma, placenta, and amniotic fluid, while it was significantly decreased in fetal liver/spleen and neonatal brain. NGF and BDNF were significantly decreased in the placenta and fetal liver/spleen. There was no change in BDNF or NGF in the fetal or neonatal brain. Changes in TNFalpha, BDNF, and NGF after maternal exposure to poly I:C represent a potential mechanism through which maternal infection increases risk for neurodevelopmental disorders.

Periodontal disease and upper genital tract inflammation in early spontaneous preterm birth

OBJECTIVE

To estimate the relationship between maternal periodontal disease and both early spontaneous preterm birth and selected markers of upper genital tract inflammation.

METHODS

In this case-control study, periodontal assessment was performed in 59 women who experienced an early spontaneous preterm birth at less than 32 weeks of gestation, in a control population of 36 women who experienced an early indicated preterm birth at less than 32 weeks of gestation, and in 44 women with an uncomplicated birth at term (>or = 37 weeks). Periodontal disease was defined by the degree of attachment loss. Cultures of the placenta and umbilical cord blood, cord interleukin-6 levels, and histopathologic examination of the placenta were performed for all women.

RESULTS

Severe periodontal disease was more common in the spontaneous preterm birth group (49%) than in the indicated preterm (25%, P =.02) and term control groups (30%, P =.045). Multivariable analyses, controlling for possible confounders, supported the association between severe periodontal disease and spontaneous preterm birth (odds ratio 3.4, 95% confidence interval 1.5-7.7). Neither histologic chorioamnionitis, a positive placental culture, nor an elevated cord plasma interleukin-6 level was significantly associated with periodontal disease (80% power to detect a 50% difference in rate of histological chorioamnionitis, alpha = 0.05).

CONCLUSION

Women with early spontaneous preterm birth were more likely to have severe periodontal disease than women with indicated preterm birth or term birth. Periodontal disease was not associated with selected markers of upper genital tract inflammation.

LEVEL OF EVIDENCE

II-2

Interleukin-6 produces neuronal loss in developing cerebellar granule neuron cultures

CNS levels of the cytokine interleukin-6 (IL-6) are elevated during CNS injury and disease, but it is unclear if IL-6 contributes to the pathologic process. Our studies show that in a well-characterized CNS developmental model system, primary cultures of rodent cerebellar granule neurons, chronic exposure to IL-6 during neuronal development can result in cell damage and death in a subpopulation of developing granule neurons. Chronic exposure to IL-6 also increased the susceptibility of the granule neurons to a toxic insult produced by excessive activation of NMDA receptors. These results are consistent with a role for IL-6 in the neuropathology observed in the developing CNS during injury and disease.

Development of a guinea pig model of chorioamnionitis and fetal brain injury

OBJECTIVE

The purpose of this study was to develop a guinea pig model of chorioamnionitis to study the mechanisms that lead to fetal brain injury. Study design Pregnant guinea pigs at 70% gestation were inoculated intracervically with 1000 to 2500 colony-forming units of Escherichia coli. Guinea pigs were killed 2 to 3 days after bacterial inoculation. Maternal blood and fetal amniotic fluid samples were analyzed for proinflammatory cytokine tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6 levels with the use of enzyme-linked immunosorbent assay kits. Fetal brains were stained for evidence of cell death with NeuroTacs stain.

RESULTS

Of 34 maternal guinea pigs that were given an intracervical inoculation of E coli, 8 guinea pigs showed microbiologic evidence of chorioamnionitis in the amniotic fluid. Tumor necrosis factor-alpha and interleukin-6 were significantly higher (P<.05) in amniotic fluid samples that were obtained from sows that were subjected to intracervical inoculation with bacteria as compared with control animals (n=6 control maternal animals). These results were observed even if no bacteria were found subsequently on culture of the amniotic fluid from inoculated animals, which indicated that indirect exposure to infectious agents was sufficient to cause an elevated inflammatory response in the fetus. Levels of white matter injury were greater in fetuses that were exposed to bacterial infection in utero, as compared with control animals (P<.05). This result was found in the staining of periventricular and cortical white matter for the immunolabeling of activated caspase 3 and NeuroTacs staining for cells that exhibited evidence of apoptotic cell death (positive stain with evidence of karyorrhexis).

CONCLUSION

Intracervical inoculation with E coli results in chorioamnionitis in guinea pigs that is associated with fetal brain injury.

Umbilical cord plasma interleukin-6 concentrations in preterm infants and risk of neonatal morbidity

OBJECTIVE

This study was undertaken to evaluate the association between umbilical cord interleukin-6 (IL-6) levels and neonatal morbidity in infants born at less than 32 weeks' gestation.

STUDY DESIGN

Umbilical cord plasma IL-6 levels and neonatal outcomes were assessed in 309 infants born between 24 weeks and 0 days' and 31 weeks and 6 days' gestation.

RESULTS

Mean IL-6 levels were higher in spontaneous (n = 193, 355 +/- 1822 pg/mL) compared with indicated preterm births (n = 116, 37 +/- 223 pg/mL, P < .0001). Adjusting for gestational age, a progressive relationship was noted between increasing IL-6 levels and increased risk of neonatal systemic inflammatory response syndrome (SIRS). IL-6 levels beyond the 90th percentile (> or =516.6 pg/mL) were also significantly associated with periventricular leukomalacia (PVL; odds ratio [OR] 15, 95% CI 2-149) and necrotizing enterocolitis (NEC; OR 6, 95% CI 1.1-33). In the multivariate analysis, an IL-6 level 107.7 pg/mL or greater (determined by receiver operating curve analysis) remained a significant independent risk factor for PVL (OR 30.3, 95% CI 4.5-203.6).

CONCLUSION

Umbilical cord IL-6 levels are higher in preterm infants born after spontaneous preterm labor or premature rupture of membranes. Elevated IL-6 levels are associated with an increased risk for SIRS, PVL, and NEC in infants born at less than 32 weeks' gestation.

Maternal infection-induced white matter injury is reduced by treatment with interleukin-10

OBJECTIVE

The purpose of this study was to test the hypothesis that interleukin-10 can prevent white matter injury in neonatal rats that are born to infected dams.

STUDY DESIGN

Timed pregnant rats (day 17) were assigned to the following treatment groups: (1) saline control (n = 5 rats), (2) Escherichia coli- infected (n = 10 rats), and (3) E coli + interleukin-10 (n = 5 rats). E coli was administered at a titer of 1 x 10(7) colony-forming units by intrauterine inoculation just above the cervix at the bifurcation of the uterine horns. Rat interleukin-10 was administered intravenously at a dose of 1 microg/kg of body weight. After delivery, the pups were maintained with dams until day 8, at which time they were placed under general anesthesia and perfused with saline solution followed by 10% paraformaldehyde. The brains were removed, placed in 30% sucrose solution, and then frozen at -20 degrees C until the preparation of the frozen sections. Standard hematoxylin/eosin staining was performed, and the brains were evaluated for matter necrosis, apoptotic cells, and ventricular swelling.

RESULTS

In pups that were born to infected dams, 11 of 38 pups (29%) displayed symmetric lesions around the lateral ventricles. These lesions were characterized by marked looseness/edema of the neuropil, foamy-appearing histiocytes, and granular neuropil breakdown. None of the pups (n = 17) that were born to interleukin-10-treated infected dams displayed this pattern of severe white matter injury.

CONCLUSION

These results suggest that maternal interleukin-10 therapy could provide neuroprotection for infants who are born to mothers with intrauterine infection.

Prematurity and intrauterine growth retardation--double jeopardy?

Premature infants born with IUGR are at a several-fold increased risk for mortality and major neonatal morbidities, including RDS, BPD, ROP, and NEC. These severe complications of prematurity are intensified by the effect of suboptimal fetal growth. The possible pathophysiologic processes initiated in utero and continuing after birth have been discussed. Recently reported data suggest that IUGR is a risk factor in programming for the later development of cardiovascular diseases, hypertension, and diabetes mellitus in adult life. Experimental research related to the pathophysiology and etiology of these conditions may enable appropriate intervention directed at reducing the excess risk associated with the short- and long-term mortality and morbidity among premature SGA infants.

Brain injury induced by intracerebral injection of interleukin-1beta and tumor necrosis factor-alpha in the neonatal rat

To examine the possible role of inflammatory cytokines in mediating neonatal brain injury, we investigated effects of intracerebral injection of IL-1beta (IL-1beta) or tumor necrosis factor-alpha (TNFalpha) on brain injury in the neonatal rat. A stereotaxic intracerebral injection of IL-1beta or TNFalpha (10 ng per pup) was performed in postnatal day 5 (P5) SD rats. Although no necrosis of neurons was found, increased astrogliosis, as indicated by GFAP positive staining was observed 24 and 72 h following the injection of IL-1beta or TNFalpha. IL-1beta induced apoptotic cell death in the rat brain 24 h after the injection, as indicated by increases in positive TUNEL staining and caspase-3 activity, and apoptotic cell death was partially blocked by systemic administration of NBQX, an antagonist of the AMPA glutamate receptor. IL-1beta also significantly reduced the number of developing oligodendrocytes (OLs) 24 h after the injection and this impairment was not prevented by NBQX. On the contrary, TNFalpha induced a much smaller increase in the number of TUNEL positive cells and did not reduce the number of developing OLs. By P8, myelin basic protein (MBP) was clearly detected in the control rat brain, while MBP positive staining was very weak, if any, in the IL-1beta treated rat brain. MBP expression in the TNFalpha treated rat brain was less affected. The overall results indicate that IL-1beta may directly cause injuries to developing OLs and impair myelination in the neonatal rat brain and TNFalpha may have different roles in mediating brain injury.

Obstetric risk factors and persistent increases in brain parenchymal echogenicity in preterm infants

OBJECTIVE

To assess the risk of persistent (>7 days) increases in brain parenchymal echogenicity in preterm infants and their association with known obstetric risk factors.

DESIGN

Case-control study of prospectively collected data.

SETTING

A University hospital in Northern Italy.

POPULATION

Eighty-five singleton infants between 24 and 34 weeks of gestation with a cranial ultrasonographic diagnosis of persistently increased parenchymal echogenicity without development of cystic degeneration, and 170 control infants with negative cranial ultrasonographic findings.

METHODS

A comparison of the prevalence of selected obstetric risk factors between infants with persistent echo-dense lesions and negative controls.

MAIN OUTCOME MEASURES

Odds ratios of persistent echo-dense lesions including first-degree interactions between variables.

RESULTS

After adjusting for birthweight, logistic regression analysis showed that the only factor associated with an increased risk of persistent brain echo-dense lesions in infants was multiple courses of antenatal steroids (OR = 2.14, 95% CI = 1.11-4.15, P= 0.024). In this group, the risk of persistent echo-dense lesions was particularly high in: (i) mothers receiving dexamethasone rather than betamethasone (P value for interaction = 0.015) and (ii) after expectant management of pre-eclampsia or intrauterine growth retardation (P value for interaction = 0.03).

CONCLUSIONS

Multiple doses of antenatal steroids, especially dexamethasone, could influence the prevalence of persistent increases in brain parenchymal echogenicity in preterm infants.

An Evidence-Based Approach to the Evaluation and Treatment of Premature Rupture of Membranes: Part I

Preterm premature rupture of membranes (PPROM) occurs in 3% of pregnancies and is responsible for one third of all preterm births. PPROM will affect 120,000 women in the United States each year. It is associated with significant maternal, fetal, and neonatal morbidity and mortality resulting from infection, umbilical cord compression, abruptio placentae, and prematurity. The etiology is multifactorial, but the most significant risk factors are previous preterm birth and previous preterm premature rupture of membranes. Accurate diagnosis is extremely important to assure proper treatment. Evaluation is based on patient history and clinical examination. This review presents the available evidence and grades it according to the U.S. Preventative Task Force recommendations. In part I of this review, the definition, pathophysiology, and methods of PPROM diagnosis are presented. In part II, the management, treatment, neonatal outcome, and the maternal and fetal evaluation of women with PPROM in the presence of cerclage and medical complications is reviewed.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to define the term: preterm premature rupture of membranes, to list the factors associated with premature rupture of membranes, and to outline the tests available for the diagnosis of intra-amniotic infection.

Neuroimaging in cerebral palsy

Parents and clinicians concerned about high-risk infants and children with motor delay or cerebral palsy seek information on cause, treatment, prognosis, and recurrence risk. Used in combination with history and examination, neuroimaging studies can improve diagnosis and management. In premature infants, cranial ultrasound is a reliable, noninvasive diagnostic modality. Nuclear magnetic resonance techniques including magnetic resonance imaging and diffusion weighted imaging can be used effectively in neonatal encephalopathies. In children with motor delay and cerebral palsy syndromes including spastic diplegia, quadriplegia, hemiplegia, and extrapyramidal movement disorders, conventional magnetic resonance imaging has become an important determinant of diagnosis and management. The aim of this article is to help clinicians select and interpret imaging studies of benefit in clinical care.

Inflammatory brain damage in preterm newborns--dry numbers, wet lab, and causal inferences

Epidemiologic observations support the contention that infection, inflammation, and neonatal white matter damage (WMD) are associated. We also have documentation from multiple experimental models that infection/inflammation can damage developing white matter. Based on these observations in humans and animals, we offer causal inferences using widely accepted causal criteria and the multivariable model of causation. As much as we want to, however, we are reluctant to state unequivocally that inflammation causes WMD in humans born much before term. The main reason is that we lack convincing evidence that inflammation precedes WMD (temporal evidence). We also need more (and more detailed) observational studies clarifying the presumed infection --> inflammation --> WMD sequence before we can initiate intervention trials to reduce the risk of WMD.

Intraventricular Hemorrhage and Periventricular Leukomalacia in Preterm Infants

OBJECTIVE

To evaluate whether intraventricular hemorrhage and periventricular leukomalacia are characterized by different risk factors.

METHODS

In a cohort of 653 consecutive singleton neonates born after preterm membrane rupture, spontaneous preterm labor, or indicated preterm delivery at 24 to 33 weeks of gestation from January 1, 1993, to December 31, 2002, we evaluated the obstetric and histopathologic placental variables in reference to the development of intraventricular hemorrhage (n = 44), periventricular leukomalacia (n = 19), or no ultrasonographic cerebral lesion (n = 589). Excluded were stillbirths and congenital anomalies. Statistical analysis included Fisher exact test, Student t test, and stepwise logistic regression analysis with a 2-tailed P <.05 considered significant.

RESULTS

Multivariate analysis showed that occurrence of neonatal intraventricular hemorrhage and periventricular leukomalacia were associated only with spontaneous prematurity (odds ratio = 1.9; 95% confidence interval 1.1-3.4) and gestational age at delivery in weeks (odds ratio = 0.8; 95% confidence interval 0.7-0.9). Neonates with intraventricular hemorrhage did not differ from those with periventricular leukomalacia in any obstetric or neonatal variable, but there was a higher risk of neurodevelopmental delay associated with periventricular leukomalacia.

CONCLUSION

Among premature infants born at less than 34.0 weeks of gestation, intraventricular hemorrhage and periventricular leukomalacia share common clinical characteristics, with spontaneous preterm delivery and gestational age at delivery as the only independent antenatal predictors.

Preterm twin gestation and cystic periventricular leucomalacia

OBJECTIVE

To identify risk factors for the development of cystic periventricular leucomalacia (PVL) in twin gestation.

DESIGN

Retrospective case-control study.

SETTING

Tertiary care university hospital, Department of Paediatrics, Division of Neonatology, Graz, Austria.

PATIENTS

Preterm twin gestations with one sibling having developed cystic PVL, diagnosed by ultrasound scans, compared with their co-twins without PVL, in hospital between 1988 and 2000.

MAIN OUTCOME MEASURES

Perinatal and postnatal risk factors for the development of PVL.

RESULTS

Eighteen preterm twin gestations were included. Monochorionicity was evident in 47% of the pregnancies, and twin to twin transfusion syndrome occurred in two cases (11%). Fetal distress correlated inversely with PVL (15% v 53%, p = 0.019, relative risk (RR) = 2.057, 95% confidence interval (CI) = 1.067 to 3.968). Hypocarbia with Pco(2) levels below 30 mm Hg (4 kPa) was diagnosed in 29% of the cases compared with 6% of the controls (p = 0.038, RR = 1.944, 95% CI = 1.113 to 3.396). There were no significant differences between groups with regard to premature rupture of the membranes, early onset infection, respiratory distress syndrome, mechanical ventilation, arterial hypotension, persistent ductus arteriosus, and hyperbilirubinaemia. Asphyxia was only evident in three controls. Three infants died and another three were lost to follow up. None of the cases compared with 62% of the controls were diagnosed as having developed normally (p < 0.001), and 14 cases (82%) compared with two controls (15%) developed cerebral palsy (p < 0.001).

CONCLUSION

Hypocarbia was the only risk factor strongly associated with cystic PVL. The general outcome of the infants was poor.

Prenatal infection and risk for schizophrenia: IL-1beta, IL-6, and TNFalpha inhibit cortical neuron dendrite development

Prenatal exposure to infection increases risk for schizophrenia, and we have hypothesized that inflammatory cytokines, generated in response to maternal infection, alter neuron development and increase risk for schizophrenia. We sought to study the effect of cytokines generated in response to infection-interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNFalpha), and interleukin-6 (IL-6)-on the dendritic development of cortical neurons. Primary mixed neuronal cultures were obtained from E18 rats and exposed to 0, 100, or 1000 units (U)/ml of IL-1beta, TNFalpha, IL-6, or IL-1beta+TNFalpha for 44 h. MAP-2-positive neurons were randomly identified for each condition and the number of primary dendrites, nodes, and total dendrite length was determined. We found that 100 U of TNFalpha significantly reduced the number of nodes (27%, p=0.02) and total dendritic length (14%, p=0.04), but did not affect overall neuron survival. A measure of 100 U IL-1beta+TNFalpha significantly reduced the number of primary dendrites (17%, p=0.006), nodes (32%, p=0.001), and total dendritic length (30%, p<0.0001), although it did not affect overall neuron survival. At 1000 U, each cytokine significantly reduced the number of primary dendrites (14-24%), nodes (28-37%), as well as total dendritic length (25-30%); neuron survival was reduced by 14-21%. These results indicate that inflammatory cytokines can significantly reduce dendrite development and complexity of developing cortical neurons, consistent with the neuropathology of schizophrenia. These findings also support the hypothesis that cytokines play a key mechanistic role in the link between prenatal exposure to infection and risk for schizophrenia.

Postnatal changes in cerebral oxygen extraction in the preterm infant are associated with intraventricular hemorrhage and hemorrhagic parenchymal infarction but not periventricular leukomalacia

Fluctuations in cerebral hemodynamics have been implicated in the pathogenesis of acquired brain damage in babies born prematurely. This study examined the changes in cerebral fractional oxygen extraction (FOE) over the first 3 d after birth in 25 very-low-birth-weight preterm infants. Twelve infants had no major cerebral injury and 13 had acquired brain injury; cystic periventricular leukomalacia (PVL) was present in 4 and intraventricular hemorrhage (IVH) in 9, of whom 2 also had hemorrhagic parenchymal infarction (HPI). Normal values (median, 5(th)-95(th) centiles) for cerebral FOE in very-low-birth-weight infants with no cerebral injury were 0.38 (0.23-0.53) on d 1, 0.31 (0.18-0.45) on d 2, and 0.28 (0.17-0.38) on d 3. Infants who developed cystic PVL had no significant change in cerebral FOE during the first 3 d after birth. By contrast, cerebral FOE fluctuated in infants with IVH over the 3 d of measurement, decreasing from d 1 to d 2 (p = 0.03) and increasing from d 2 to d 3 (p = 0.02). The highest cerebral FOE values were seen in the two infants with HPI. The different patterns of change in cerebral FOE with HPI and cystic PVL provide additional evidence that the pathogenesis of these two conditions is different. Because high cerebral FOE is likely to be a consequence of low cerebral oxygen delivery, probably because of low cerebral blood flow, our results indicate that fluctuations in cerebral blood flow may occur when there is IVH or HPI.

Antenatal risk factors for cerebral palsy

Two of every 1000 live-born children develop cerebral palsy (CP). The aetiology of CP is often unclear and because CP is a symptom complex rather than a disease, clinically defined at 4-5 years of age, it is not surprising that there are considerable problems associated with epidemiological studies of its aetiology. The only reason for the CP concept is that it emanates from an insult to a growing, developing brain and a dynamic clinical picture from static pathology. Evidence suggests that 70-80% of CP cases are due to prenatal factors and that birth asphyxia plays a relatively minor role (<10%). Some antenatal risk factors are repeatedly observed to be related to CP: low gestational age, male gender, multiple gestation, intrauterine viral infections and maternal thyroid abnormalities. Recently, intrauterine infection/inflammation with a maternal response (consisting of chorioamnionitis) and a fetal inflammatory response (consisting of funicitis or elevated interleukin-6 in fetal plasma) has been found to be related to white matter injury and CP. Some risk factors are associated with CP at all gestational ages whereas others mostly affect term or preterm infants, e.g. intrauterine growth restriction seems to be a risk factor in term infants. There also seems to be an association between autoimmune and coagulation disorders and CP.

Prolonged in utero meconium exposure impairs spatial learning in the adult rat. Central Prize Award

OBJECTIVE

The purpose of this study was to examine the effects of prolonged in utero meconium exposure on adult learning and memory, as measured by the Morris water maze.

STUDY DESIGN

Timed pregnant Long-Evans rats were studied. On gestational day 20 (term, 21 days of gestation), laparotomy was performed, and each maternal animal received an injection of clear amniotic fluid or meconium-stained amniotic fluid into each gestational sac. The laparotomy incision was closed, and the animals received postoperative monitoring through delivery. On postnatal days 145 to 148, the offspring underwent Morris water maze testing. The mean (+/-SEM) for the latency time was reported for each day's trial and compared between groups.

RESULTS

There were significant differences between meconium-stained amniotic fluid group and clear amniotic fluid group in the mean time to platform on day 1 (82.7 +/- 1.8 seconds vs 75.9 +/- 3.0 seconds; P=.04), day 2 (60.5 +/- 3.5 seconds vs 47. 8 +/- 4.6 seconds; P=.03), and day 3 (56.5 +/- 4.5 seconds vs 34.7 +/- 4.4 seconds; P=.001). However, there were no differences on days 4 and 5. There were also no differences between recall and response learning trials that were done after a 12-day retention period.

CONCLUSION

In the absence of hypoxia or infection, prolonged in utero meconium exposure is associated with a delay of spatial learning in the adult rat.

Expression of glial fibrillary acidic protein in developing rat brain after intrauterine infection

In order to investigate the neuropathological effects on the developing rat brain after intrauterine infection, identification of GFAP was observed. Escherichia coli (E. coli) was inoculated into uterine horn of pregnant rats when gestation was 70% complete (15 days) and the control group was inoculated with normal saline. Immunohistochemistry was used for evaluation of GFAP expression in pup brains at postnatal day 1 (P1), P3, P7, P14 and P21, and RT-PCR was used to analyze GFAP mRNA, interleukin-1beta, mRNA (IL-1beta mRNA) and tumor necrosis factor-alpha mRNA (TNF-alpha mRNA) expression in pup brains at P1, P3 and P7. At P1 and P3, GFAP was expressed very scarcely in periventricular white matter but not in other brain regions between the two groups. Compared with the control group, at P7 GFAP expression of the E. coli-treated pups was remarkably increased in periventricular white matter and hippocampus. The E. coli-treated pups at P14 showed a marked increase of GFAP expression in periventricular white matter, corpus callosum and cortex. However, no significant difference in levels of GFAP expression in any brain regions were found at P21 between the two groups. GFAP mRNA expression of the E. coli-treated pups was higher than the control at P1 and P3, but there was no significant difference between the two groups at P7. IL-1beta mRNA and TNF-alpha mRNA expressions of the E. coli-treated pups were higher than the control at P1 but there was no significant difference between the two groups at P3 and P7. These present results suggest that intrauterine infection could increase GFAP expression in the pup brain and indicate that intrauterine infection might damage the developing white matter and IL-1beta, TNF-alpha might be a mechanism mediating between the two events.

Inflammatory markers in intrauterine and fetal blood and cerebrospinal fluid compartments are associated with adverse pulmonary and neurologic outcomes in preterm infants

Recent evidence strongly implicates the inflammatory response to intrauterine infection in the pathogenesis of neonatal brain and lung injury. We hypothesized that lung and brain injury in preterm infants occurs during a common developmental window of vulnerability as the result of an inflammatory response in different compartments. To determine whether inflammatory markers in these compartments are associated with bronchopulmonary dysplasia (BPD) or cranial ultrasound (CUS) abnormalities in infants <33 wk gestation age (GA) and <1501 g birth weight, we analyzed placental pathology and serum and cerebrospinal fluid (CSF) IL-6, IL-1beta, and tumor necrosis factor-alpha (TNF-alpha) concentrations in 276 infants. Logistic regressions were performed stratified by GA. Histologic chorioamnionitis was significantly associated with BPD in infants </=28 wk GA (OR 3.6, p = 0.027). Maternal stage of chorioamnionitis significantly correlated with severity of BPD. Presence of a fetal inflammatory response indicated by fetal vasculitis or elevated cytokines was not associated with the development of BPD. Serum IL-6 >/=17 pg/mL was associated with an abnormal CUS in infants >28 wk GA (OR 3.36, p = 0.023) but not </=28 wk GA. CSF concentrations of IL-6 >/=6.5 pg/mL and TNF-alpha >/=3 pg/mL were associated with abnormal CUS in infants </=28 wk GA (IL-6 OR 3.0; TNF-alpha OR 3.5; p < 0.05 each case) but not >/=28 wk GA. These data suggest that in infants </=28 wks GA, BPD may be initiated by inflammatory mediators in amniotic fluid, but brain injury may involve variations in the systemic inflammatory response.

Brain development during fetal life: influences of the intra-uterine environment

The intrauterine environment can significantly affect fetal brain development. Here we review our recent findings using animal models that mimic adverse intrauterine conditions which could exist during human pregnancy. We have focused on effects of both acute and chronic hypoxic and inflammatory insults. Relatively brief periods of hypoxemic compromise can have significant effects on the fetal brain causing neuronal loss and cerebral white matter damage. Subtle brain injury can occur, for example to a particular class of neuron, and this can have a significant effect on the function of a specific system. Chronic mild placental insufficiency can result in long term deficits in neuronal connectivity affecting function postnatally as demonstrated in the auditory and visual systems. Repeated acute exposure to an inflammatory agent results in diffuse subcortical white matter damage and in some cases periventricular necrosis. We have demonstrated that the timing and severity of these prenatal insults are determinants of the outcomes, in terms of the severity of the damage and the regions of the brain affected.

Low blood pressure among very-low-birth-weight infants with fetal vessel inflammation

OBJECTIVE

To test the hypothesis that fetal vessel inflammation (FVI: funisitis and/or fetal vasculitis) is associated with lower blood pressure (BP) over the first week of life and an increased risk of periventricular leukomalacia (PVL) among premature infants.

STUDY DESIGN

A total of 255 infants born at <1350 g to normotensive mothers were stratified by gestational age (GA) and grouped by presence/absence of FVI on placental pathology. Daily highest (Hi) and lowest (Lo) systolic BP (BP(sys)), mean BP (BP(mn)) and diastolic BP (BP(dia)) over first 7 days of life were analyzed by repeated measures ANOVA and regression analysis. Cranial ultrasounds were obtained at 2 weeks of life.

RESULTS

Infants > or =30 weeks gestation with FVI had lower HiBP(sys), HiBP(mn), HiBP(dia), LoBP(sys), LoBP(mn) and LoBP(dia) (p<0.001) than did infants without FVI. Infants with PVL (all < or =27 weeks gestation) had lower LoBP(mn) and LoBP(dia) (p<0.01) than controls. FVI did not increase the risk of PVL in these infants.

CONCLUSION

FVI and PVL are associated with reduced BP over the first week of life.

Developmentally regulated IkappaB expression in intestinal epithelium and susceptibility to flagellin-induced inflammation

Necrotizing enterocolitis is a devastating inflammatory condition of the intestine that occurs almost exclusively in premature newborns. Although its exact pathogenesis is unclear, we have postulated that it may result from a predisposition of the immature intestine to mount an unusually robust and damaging response to microbial infection. In support of this idea, we report that the IL-8 response of an immature human enterocyte cell line to bacterial infection was significantly higher than that of a mature enterocyte cell line. The response in both cell lines was flagellin-dependent. Corresponding to the difference in IL-8 production, the immature enterocytes expressed appreciably lower levels of specific IkappaB genes when compared with the mature enterocytes. Similar developmentally regulated differences in cytokine response and IkappaB expression were also seen in primary rat enterocytes, indicating that these observations were not peculiarities of the cell lines. Furthermore, when the level of IkappaBalpha expression was increased in the immature cell line by transfection, the flagellin-dependent IL-8 response was attenuated. Thus, we have demonstrated a previously undescribed developmental regulation of IkappaB expression in the intestine involved in modulating the IL-8 response to bacterial infection, which may contribute to the pathogenesis of age-specific inflammatory bowel diseases such as necrotizing enterocolitis.

Intrauterine infection/inflammation during pregnancy and offspring brain damages: possible mechanisms involved

Intrauterine infection is considered as one of the major maternal insults during pregnancy. Intrauterine infection during pregnancy could lead to brain damage of the developmental fetus and offspring. Effects on the fetal, newborn, and adult central nervous system (CNS) may include signs of neurological problems, developmental abnormalities and delays, and intellectual deficits. However, the mechanisms or pathophysiology that leads to permanent brain damage during development are complex and not fully understood. This damage may affect morphogenic and behavioral phenotypes of the developed offspring, and that mice brain damage could be mediated through a final common pathway, which includes over-stimulation of excitatory amino acid receptor, over-production of vascularization/angiogenesis, pro-inflammatory cytokines, neurotrophic factors and apoptotic-inducing factors.

Transfer of inflammatory cytokines across the placenta

OBJECTIVE

The purpose of this study was to determine whether the placental transfer of interleukin (IL)-1alpha, IL-6, and tumor necrosis factor-alpha (TNF-alpha) occurs.

METHODS

Four normal-term placentas were perfused for maternal-fetal transfer of the cytokines, 2 placentas for fetal-maternal transfer, and 4 additional placentas were used for an endogenous control. The ex vivo isolated cotyledon human placental perfusion model was used. The reference compound antipyrine was used to determine the transport fraction and clearance index of the cytokines. The cytokines were added to either the maternal or fetal circulations, and samples were collected for 1 hour in a constant-flow open circulation. Cytokine levels were compared between the study and control placentas. Concentrations of the cytokines were measured by sandwich enzyme immunoassay.

RESULTS

The clearance index for the maternal-fetal transfer of IL-1alpha and TNF-alpha was 0.001, suggesting minimal transfer to the fetal circulation. The clearance index for IL-6 was 0.30, indicating transfer to the fetal circulation. When the cytokines were added to the fetal circulation, the clearance index for IL-1alpha was 0.001, again indicating minimal transfer. The clearance index for TNF-alpha in the fetal-maternal study was not determined. IL-6 had a clearance index of 0.23, which was similar to that observed with maternal-fetal transfer. IL-6 concentrations in the study placentas were higher than the concentrations found in the controls.

CONCLUSION

There appears to be bidirectional transfer of IL-6 in the healthy-term human placental perfusion model.

LEVEL OF EVIDENCE

II-2

Coagulation, inflammation, and the risk of neonatal white matter damage

Indicators of coagulation activation are sometimes increased in the blood of newborns and adults who have a systemic inflammatory response. These coagulation factors have the ability to exacerbate inflammation, which in turn can promote coagulation. Therapies directed solely at coagulation factors and therapies directed solely at inflammation factors have not proved effective in reducing mortality in adults with a systemic inflammatory response syndrome and multi-organ dysfunction (SIRS/MOD). On the other hand, the only therapy that has reduced mortality in SIRS/MOD is activated protein C, which has both anti-coagulation and anti-inflammatory effects. This and other observations support the view that activated coagulation factors enhance inflammation. Since newborns at risk of cerebral white matter damage and cerebral palsy are more likely than their peers to have a systemic inflammatory response, which is sometimes accompanied by elevated blood levels of coagulation factors, we suggest that activated coagulation factors contribute to the occurrence of cerebral white matter damage by exacerbating inflammatory phenomena, rather than by occluding cerebral blood vessels.

Over-expression of S100B protein in children with cerebral palsy or delayed development

S100B protein plays a role in promoting the maturation of a variety of neurons in many different CNS regions. Behavioral dysfunction in S100B over-expressed transgenic mice and the chronic elevation of S100B in Down's syndrome and in schizophrenia suggest that S100B over-expression is related to abnormal brain function. Therefore, we believed that the over-expression of S100B protein might be implicated in developmental brain dysfunction. The purpose of this study was to evaluate the serum S100B protein levels in patients with developmental brain dysfunction, such as cerebral palsy and delayed development, and to determine the clinical relevance of serum S100B protein in these patients. The mean values of serum S100B protein were significantly increased in both conditions. Patients with cerebral palsy had a S100B protein level of 3455.8 +/- 5004.6 ng/L and those with delayed development of 2557.0 +/- 2321.0 ng/L, compared with a normal control level of 583.8 +/- 483.0 ng/L (P < 0.05). The over-expression of S100B (defined as the normal mean plus three standard deviations) was found in 47.1% of the total patient group (delayed development (47.5%) and cerebral palsy (47.0%)). The frequency of over-expression was not significantly related to clinical diagnosis, disease severity or to brain MRI findings. However, patients who had periventricular leukomalacia by brain MRI showed a wide range and very high levels of S100B exceeding 10,000 ng/L in some cases. These findings suggest that the pathogenesis implied by the over-expression of S100B protein during brain development may play a role in developmental brain dysfunction.