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

Neuregulin-1 high-producer genotype is associated with a decreased risk of admission to the neonatal intensive care unit

BACKGROUND

Neuregulin (NRG1) is a developmental growth factor and homozygous C allele carriers at the NRG221533 locus are at reduced risk for developmental disability.

AIMS

To explore whether 1) the NRG221533 CC genotype is associated with a decreased likelihood of neonatal intensive care unit (NICU) admission; 2) NRG1 is present in the infant's systemic circulation; and 3) to comparatively investigate two additional proposed high-producer single nucleotide polymorphisms (SNPs) for the cytokines interleukin 6 (-572) and interleukin 10 (-1082), examining both gene product and the association for admission to the NICU.

STUDY DESIGN

IL6 and IL10 protein was measured in umbilical cord blood by a multiplex sandwich immunoassay and NRG1 by ELISA. Infants were screened for SNPs IL6 (-572), IL10 (-1082), and NRG221533. We defined IL6 (C), IL10 (G) and NRG1 (C) as high-producer alleles based on published data.

SUBJECTS

Unselected single-center convenience sample of 97 newborns with a gestational age of 25-33 weeks (N=18), 34-36 weeks (N=17), 37-38 weeks (N=28), and 39-41 weeks (N=34).

OUTCOME MEASURES

Prematurity (<37 completed weeks) and admission to NICU.

RESULTS

The SNP NRG221533 CC genotype was associated with reduced admission to the NICU, even after adjustment for confounders. Adjustment for high IL6 levels reduced the protective effect. NRG1 levels tended to increase with advancing gestational age. Unexpectedly, we found lower IL6 and IL10 levels in infants homozygous for the IL6 (C) and IL10 (G) alleles, and no associations between IL10 (-1082) and IL6 (-572) genotype and prematurity or admission to NICU.

CONCLUSIONS

The NRG221533 CC genotype might be protective in newborns. The protective effect might not be directly related to increased systemic NRG levels.

Histologic chorioamnionitis and acute neurologic impairment in premature infants

OBJECTIVE

To determine if histologic chorioamnionitis is associated with acute neurologic impairment as evaluated by auditory brainstem response in premature infants.

METHODS

A prospective study was performed to compare auditory neural function at birth between premature infants with maternal histologic chorioamnionitis and infants without maternal histologic chorioamnionitis. Our inclusion criteria was 28-33 weeks gestational age (GA) infants who had maternal placental histopathology performed. Infants with toxoplasmosis, other infections, rubella, cytomegalovirus and herpes simplex (TORCH) infections, chromosomal disorders, cranio-facial anomalies and/or unstable condition were excluded. Bilateral monaural auditory brainstem evoked responses were performed using 80 dB nHL click stimuli at a repetition rate of 29.9/s within 48 h after birth.

RESULTS

Of 101 infants who met study criteria, 29 infants were born with history of maternal histologic chorioamnionitis. There were no significant differences between infants with histologic chorioamnionitis and infants without histologic chorioamnionitis in perinatal factors except for GA, pregnancy induced hypertension, and exposure to antenatal magnesium sulphate. After controlling for confounders, histologic chorioamnionitis was not associated with prolonged absolute wave latencies I, III, and V and/or decreased frequency of mature auditory waveform compared to infants without histologic chorioamnionitis.

CONCLUSION

Histologic chorioamnionitis is not associated with neurologic impairment at birth in premature infants.

Notch signaling: key role in intrauterine infection/inflammation, embryonic development, and white matter damage?

The mechanisms or pathophysiologies that lead to cerebral white matter damage during development are complex and not fully understood. It is postulated that exposure of the preterm brain to inflammatory cytokines during intrauterine infection/inflammation contributes to brain white matter damage, and this damage may affect the function and differentiation of progenitor oligodendrocyte cells under physiological conditions. The Notch pathway, an important signaling pathway controlling various cells' differentiation, functions in the timing of oligodendrocyte differentiation, and Notch signaling may contribute to white matter damage and may mediate neurogenesis in a pathophysiological phase. Recent studies have led to recognition of the role of the Notch pathway in neurogenesis in cerebral ischemic damage and in myelination and axonal damage of neurodegenerative diseases. Moreover, Notch plays a critical role in steering an immune response toward inflammation by regulating expression of various cytokines and proinflammatory cytokines resulting in the activation of Notch signaling. Thus, the Notch signaling pathway likely plays a key role in intrauterine infection/inflammation, brain development, and white matter damage, and future research directed toward understanding its role will be important. Insofar as Notch signaling could have an important effect on neurogenesis, mobilization of progenitor cells is one strategy for compensating for the neuronal losses seen in white matter damage after intrauterine infection/inflammation.

Icariin attenuates lipopolysaccharide-induced microglial activation and resultant death of neurons by inhibiting TAK1/IKK/NF-kappaB and JNK/p38 MAPK pathways

Microglia in the central nervous system (CNS) play an important role in the initiation of neuroinflammatory response. Icariin, a compound from Epimedium brevicornum Maxim, has been reported to have anti-inflammatory effect on the macrophage cell line RAW264.7. However, it is currently unknown what anti-inflammatory role icariin may play in the CNS. Here, we reported the discovery that icariin significantly inhibited the release of nitric oxide (NO), prostaglandin E (PGE)-2, reactive oxygen species (ROS) and mRNA expression of proinflammatory cytokines such as tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta and IL-6 in lipopolysaccharide (LPS)-activated microglia. Icariin also inhibited the protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 in a dose-dependent manner. Further mechanism studies revealed that icariin blocked TAK1/IKK/NF-kappaB and JNK/p38 MAPK pathways. It was also found that icariin reduced the degeneration of cortical neurons induced by LPS-activated microglia in neuron-microglia co-culture system. Taken together these findings provide mechanistic insights into the suppressive effect of icariin on LPS-induced neuroinflammatory response in microglia, and emphasize the neuroprotective effect and therapeutic potential of icariin in neuroinflammatory diseases.

Periventricular leukomalacia and placental histopathologic abnormalities

OBJECTIVE

To estimate whether there are placental histopathologic abnormalities associated with neonatal periventricular leukomalacia (PVL), a major precursor of cerebral palsy.

METHODS

This is a case-control study of 167 neonates born between 23 and 34 weeks of gestation diagnosed with PVL by head ultrasonography within 6 weeks of birth, and 167 control neonates without neurologic morbidity matched by gestational age. Placentas for both case neonates and control neonates were reviewed by two perinatal pathologists who were blinded to neonatal course.

RESULTS

Neonates with PVL were significantly more likely to have positive neonatal blood (28.7%, 16.8%, P=.001) and cerebrospinal fluid (14.4%, 4.8%, P=.007) cultures. The ratio of placental weight to birth weight did not differ between groups, but neonates with PVL had significantly more chronic diffuse capsular deciduitis (20.4%, 10.8%, P=.02) and capsular decidual plasma cells (8.4%, 2.4%, P=.02). Conditional logistic regression adjusting for birth weight and the presence of multiple gestation in the identification of PVL showed a significant increase for diffuse capsular deciduitis (P=.02) and capsular decidual plasma cells (P=.03).

CONCLUSION

Periventricular leukomalacia has a significant but weak association with chronic diffuse capsular deciduitis and the presence of capsular decidual plasma cells, evidence of chronic infection but not histologic acute chorioamnionitis.

LEVEL OF EVIDENCE

II.

Human C-reactive protein enhances vulnerability of immature rats to hypoxic-ischemic brain damage: a preliminary study

In utero exposure to infection or inflammation is a strong and independent predictor of cerebral palsy. Using a rat model of neonatal hypoxic-ischemic (HI) encephalopathy, we investigated the hypothesis that C-reactive protein (CRP), which is not specific for infection, aggravates vulnerability of the immature brain to HI. Seven-day-old rats were divided into human CRP treated and control groups. After injection of each solution, they underwent left common carotid artery ligation and exposure to 8% hypoxia for 40 minutes. Human CRP, rat CRP, and interleukin 6 (IL-6) concentrations in serum were measured by enzyme-linked immunosorbent assay 30 to 60 minutes after injection of each solution. Four days later, microtubule-associated protein 2 (MAP-2) immunostaining was used to examine the brains for neuronal damage. Human CRP treatment significantly reduced the MAP-2 positive area ratio, compared with control group ( P < .05), suggesting that human CRP-enhanced susceptibility to HI-induced brain damage. Mean serum human CRP concentration in the human CRP group was 1823 +/- 520 ng/mL (range: 365-3964 ng/mL). Interleukin 6 concentrations in serum were moderately elevated in both groups, without significant differences, and rat CRP concentrations were within normal range. C-reactive protein makes the immature brain susceptible to HI insult, even if the insult causes little or no injury by itself.

Regulated on activation, normal T cell expressed and secreted and tumor necrosis factor-alpha in septic neonates

OBJECTIVE

Measuring serum tumour necrosis factor-alpha (TNF-alpha) and Regulated upon Activation Normal T cell Expressed and Secreated (RANTES) in neonatal sepsis and determining whether early and late onset sepsis were associated with differences in their concentrations.

STUDY DESIGN

In 15 neonates showing clinical signs of early- or late-onset infection, serum TNF-alpha and RANTES were determined at first suspicion of sepsis and before starting antibiotics. Fifteen healthy neonates were included as controls.

RESULTS

Serum TNF-alpha white blood cells and C-reactive protein (CRP) were significantly higher, whereas RANTES was significantly lower in the septic group compared with the non-septic group. There was no significant difference in RANTES or TNF-alpha levels between infants having early or late-onset sepsis. Similar to term neonates, premature neonates, responded to infection with increased TNF-alpha and decreased RANTES, with no statistical differences between both groups.

CONCLUSION

In this study TNF-alpha is the best diagnostic test of neonatal sepsis, followed by CRP, when evaluated at first suspicion of sepsis.

Interleukin-10/Ceftriaxone prevents E. coli-induced delays in sensorimotor task learning and spatial memory in neonatal and adult Sprague-Dawley rats

Intrauterine infection during pregnancy is associated with early activation of the fetal immune system and poor neurodevelopmental outcomes. Immune activation can lead to alterations in sensorimotor skills, changes in learning and memory and neural plasticity. Both interleukin-10 (IL-10) and Ceftriaxone have been shown to decrease immune system activation and increase memory capacity, respectively. Using a rodent model of intrauterine infection, we examined sensorimotor development in pups, learning and memory, via the Morris water maze, and long-term potentiation in adult rats. Pregnant rats at gestational day 17 were inoculated with 1 x 10(5) colony forming units of Escherichia coli (E. coli) or saline. Animals in the treatment group received IL-10/Ceftriaxone for 3 days following E. coli administration. Intrauterine infection delayed surface righting, negative geotaxis, startle response and eye opening. Treatment with IL-10/Ceftriaxone reduced the delay in these tests. Intrauterine infection impaired performance in the probe trial in the Morris water maze (saline 25.13+/-1.01; E. coli 20.75+/-1.01; E. coli+IL-10/Ceftriaxone 20.2+/-1.62) and reduced the induction of long-term potentiation (saline 141.5+/-4.3; E. coli 128.7+/-3.9; E. coli+IL-10/Ceftriaxone 140.0+/-10). In summary, the results of this study indicate that E. coli induced intrauterine infection delays sensorimotor and learning and memory, while IL-10/Ceftriaxone rescues some of these behaviors. These delays were also accompanied by an increase in interleukin-1beta levels, which indicates immune activation. IL-10/Ceftriaxone prevents these delays as well as decreases E. coli-induced interleukin-1beta activation and may offer a window of time in which suitable treatment could be administered.

Cytokine levels in neonatal necrotizing enterocolitis and long-term growth and neurodevelopment

OBJECTIVE

To investigate if circulating cytokines are related to growth and neurodevelopmental outcome following necrotizing enterocolitis (NEC).

STUDY DESIGN

Pro-inflammatory cytokine levels were measured prospectively in 40 neonates and compared with neurodevelopmental outcome. Cytokine levels were measured at the onset of feeding intolerance (Group II, n = 17) or NEC (Group III, n = 10) and at weeks 2-3 in control infants (Group I, n = 13). Neurodevelopmental outcome was assessed at the age of 24-28 months. Data were analysed using descriptive statistics, non-parametric tests and Student t-test.

RESULTS

Median birth weights (range) in groups I, II and III were 1120 (525-1564) g, 1068 (650-1937) g and 1145 (670-2833) g, and median gestational ages (range) were 28 (24-35) weeks 28 (24-35) weeks and 28 (25-37) weeks respectively. NEC occurred in 10 infants. Serum IL-6 (interleukin-6) was elevated in group III, (p = 0.03). Significant developmental delay was found in 12% of the infants in Group II and 20% of the infants in Group III, but no infant in group I. Five infants in group III with NEC (50%), had head ultrasound abnormalities. At 1 year of age, growth, weight and head circumference were significantly different in Group III, however, at two years of age, only height was significantly different, p < 0.02. Although there was wide variation, neonatal cytokine levels tended to be greater in the infants later found to have abnormal cognitive and psychomotor outcomes.

CONCLUSION

This study suggests that increased serum levels of pro-inflammatory cytokines may play a role in the poor growth and neurodevelopment associated with this high-risk population.

Prenatal infection and schizophrenia: a review of epidemiologic and translational studies

An emerging literature from epidemiologic, clinical, and preclinical investigations has provided evidence that gestational exposure to infection contributes to the etiology of schizophrenia. In recent years, these studies have moved from ecologic designs, which ascertain infection based on epidemics in populations, to investigations that have capitalized on reliable biomarkers in individual pregnancies. These studies have documented specific candidate infections that appear to be associated with an elevated risk of schizophrenia. Animal models of maternal immune activation inspired by this work have revealed intriguing findings indicating behavioral, neurochemical, and neurophysiologic abnormalities consistent with observations in schizophrenia. In parallel studies in humans and animals, investigators are working to uncover the cellular and molecular mechanisms by which in utero exposure to infection contributes to schizophrenia risk. In this review, the authors discuss and critically evaluate the epidemiologic literature on in utero exposure to infection and schizophrenia, summarize emerging animal models of maternal immune activation, and discuss putative unique and common mechanisms by which in utero exposure to infection alters neurodevelopment, potentially increasing susceptibility to schizophrenia. The promise of this work for facilitating the identification of susceptibility loci in genetic studies of schizophrenia is illustrated by examples of interaction between in utero exposure to infection and genetic variants. The authors then elaborate on possible implications of this work, including the use of preventive measures for reducing the incidence of schizophrenia. Finally, they discuss new approaches aimed at addressing current challenges in this area of research.

Pentraxin 3 in amniotic fluid: a novel association with intra-amniotic infection and inflammation

OBJECTIVE

Pentraxin 3 (PTX3) is a soluble pattern recognition receptor (PRR) that has an important role in immunoregulation and vascular integrity. The aim of this study was to determine if PTX3 is present in amniotic fluid (AF) and whether its concentration changes with gestational age (GA), in the presence of preterm or term labor, and in cases of intra-amniotic infection/inflammation (IAI) associated with spontaneous preterm labor (PTL) or preterm prelabor rupture of membranes (PROM).

STUDY DESIGN

This cross-sectional study included the following groups: 1) mid-trimester (n=45); 2) uncomplicated pregnancies at term with (n=48) and without (n=40) spontaneous labor; 3) women with PTL and intact membranes who: a) delivered at term (n=44); b) delivered preterm without IAI (n=40); or c) delivered preterm with IAI (n=62); 4) women with preterm PROM with (n=63) and without (n=36) IAI. PTX3 concentration in AF was determined by ELISA. Non-parametric statistics were used for analyses.

RESULTS

1) Among women with PTL and intact membranes, the median AF PTX3 concentration was significantly higher in women with IAI than in those without IAI (7.95 ng/mL vs. 0.38 ng/mL; P<0.001) and than in those who delivered at term (0.55 ng/mL; P<0.001); 2) women with preterm PROM and IAI had a higher median AF PTX3 concentration than those without IAI (9.12 ng/mL vs. 0.76 ng/mL; P<0.001); 3) the median AF PTX3 concentration did not change with GA (mid-trimester: 0.79 ng/mL vs. term not in labor: 0.58 ng/mL; P=0.09); and 4) labor at term was not associated with a significant change of AF PTX 3 concentration (in labor: 0.54 ng/mL vs. not in labor: 0.58 ng/mL, P=0.9).

CONCLUSIONS

PTX3 is a physiologic constituent of the AF, and its median concentration is elevated in the presence of IAI, suggesting that PTX3 may play a role in the innate immune response against IAI.

Ovine proinflammatory cytokines cross the murine blood-brain barrier by a common saturable transport mechanism

OBJECTIVES

The cytokines interleukin (IL)-1beta and IL-6 are modulators of the neuroimmune axis and have been implicated in neuronal cell death cascades after ischemia or infection. Previous work has shown that some cross-species conservation exists between human and rodent blood-brain barrier (BBB) transport systems. To further assess cross-species conservation of cytokine transport across the BBB, the current studies investigated permeability and inhibition of ovine IL-1beta and IL-6 in the mouse.

METHODS

IL-1beta or IL-6 was radioactively labeled with (131)I and injected into the jugular vein at time zero. A subset of mice received 1 or 3 microg/mouse of an unlabeled ovine or murine cytokine (IL-1beta or IL-6) to assess self- and/or cross-inhibition of transport. Permeability was assessed using multiple-regression analysis.

RESULTS

There was a significant linear relationship for both ovine (131)I-IL-1beta and (131)I-IL-6 between brain/serum ratios and exposure time, indicating BBB permeability. Inclusion of 3 microg/mouse unlabeled ovine IL-1beta or IL-6 significantly reduced the transport of ovine (131)I-IL-1beta or (131)I-IL-6, respectively, across the BBB. Transport of both ovine (131)I-IL-1beta and (131)I-IL-6 was significantly inhibited by 1 microg/mouse of murine IL-1beta or IL-6, respectively. In contrast, 1 microg/mouse of unlabeled ovine IL-1beta or IL-6 did not inhibit the transport of murine (131)I-IL-1beta or (131)I-IL-6.

CONCLUSIONS

Ovine IL-1beta and IL-6 cross the mouse BBB by saturable transport. Inhibition of transport by murine homologs indicates that both species use the same transport mechanisms. Conversely, an inability of ovine cytokines to significantly inhibit the transport of murine cytokines indicates that mouse BBB has a lower affinity for ovine than murine cytokines. Knowledge of species-conserved BBB transport mechanisms may facilitate the development of novel animal models of central nervous system pathogenesis.

The transcriptome of the fetal inflammatory response syndrome

PROBLEM

The fetal inflammatory response syndrome (FIRS) is considered the counterpart of the systemic inflammatory response syndrome (SIRS), but similarities in their regulatory mechanisms are unclear. This study characterizes the fetal mRNA transcriptome of peripheral leukocytes to identify key biological processes and pathways involved in FIRS.

METHOD OF STUDY

Umbilical cord blood from preterm neonates with FIRS (funisitis, plasma IL-6 >11 pg/mL; n = 10) and neonates with no evidence of inflammation (n = 10) was collected at birth. Results Microarray analysis of leukocyte RNA revealed differential expression of 541 unique genes, changes confirmed by qRT-PCR for 41 or 44 genes tested. Similar to SIRS and sepsis, ontological and pathway analyses yielded significant enrichment of biological processes including antigen processing and presentation, immune response, and processes critical to cellular metabolism.

RESULTS

are comparable with microarray studies of endotoxin challenge models and pediatric sepsis, identifying 25 genes across all studies.

CONCLUSION

This study is the first to profile genome-wide expression in FIRS, which demonstrates a substantial degree of similarity with SIRS despite differences in fetal and adult immune systems.

Integrated review of cytokines in maternal, cord, and newborn blood: part II-- associations with early infection and increased risk of neurologic damage in preterm infants

A growing body of literature supports the relationship of maternal inflammation with preterm birth and adverse neonatal outcomes, including infection and central nervous system (CNS) dysfunction. Mediators of inflammation, most notably proinflammatory cytokines, have been implicated as having an association with and perhaps playing a causal role in the pathogenesis, leading to adverse neonatal outcomes. Even though the association of cytokines with early adverse neonatal outcomes has been actively pursued as a line of research, there has been little integration of diverse findings across studies. Therefore, the purpose of this systematic review was to appraise and classify empirical evidence from human studies for the association of cytokine levels in blood (serum, plasma, or cells; maternal, cord, or neonatal) with two adverse early outcomes in preterm infants: early infection and increased risk of neurologic damage. The review revealed that the proinflammatory cytokines most frequently linked with sepsis are in the interleukin (IL) 1 family as well as tumor necrosis factor alpha (TNF-alpha) and IL-6. The proinflammatory cytokines most frequently linked to neurologic insult in the reviewed studies were IL-1beta, IL-6, and IL-8. In all cases where IL-1beta was studied, the levels were increased when there was neurologic insult. A better understanding of the relationship of these inflammatory substances with these adverse conditions is needed for the future development of maternal and neonatal biobehavioral nursing research.

Amniotic fluid soluble human leukocyte antigen-G in term and preterm parturition, and intra-amniotic infection/inflammation

OBJECTIVE

Circulating soluble human leukocyte antigen-G (sHLA-G) has been associated with pregnancy complications, and determination of sHLA-G concentrations in amniotic fluid (AF) has been reported in normal pregnancies. Our aim was to determine if the AF concentrations of sHLA-G change with advancing gestation, spontaneous labor at term, and in patients with spontaneous preterm labor (PTL) with intact membranes, as well as in those with preterm prelabor rupture of membranes (PROM), in the presence or absence of intra-amniotic infection/inflammation (IAI).

STUDY DESIGN

This cross-sectional study included the following groups: (1) mid-trimester (n = 55); (2) normal pregnancy at term with (n = 50) and without (n = 50) labor; (3) spontaneous PTL with intact membranes divided into: (a) PTL who delivered at term (n = 153); (b) PTL who delivered preterm without IAI (n = 108); and (c) PTL with IAI (n = 84); and (4) preterm PROM with (n = 46) and without (n = 44) IAI. sHLA-G concentrations were determined by ELISA. Non-parametric statistics were used for analysis.

RESULTS

(1) Among patients with PTL, the median AF sHLA-G concentration was higher in patients with IAI than in those without IAI or women that delivered at term (p < 0.001 for both comparisons); (2) Similarly, patients with preterm PROM and IAI had higher median AF sHLA-G concentrations than those without IAI (p = 0.004); (3) Among patients with PTL and delivery, those with histologic chorioamnionitis and/or funisitis had a higher median AF sHLA-G concentration than those without histologic inflammation (p < 0.001); and (4) The median AF sHLA-G concentration did not change with advancing gestational age.

CONCLUSIONS

AF sHLA-G concentrations are elevated in preterm parturition associated to IAI as well as in histologic chorioamnionitis. We propose that sHLA-G may participate in the regulation of the host immune response against intra-amniotic infection.

Intracranial hemorrhage in the preterm infant: understanding it, preventing it

New discoveries in neonatal imaging, cerebral monitoring, and hemodynamics, and greater understanding of inflammatory and genetic mechanisms involved in intracranial hemorrhage (ICH) in the preterm infant are creating opportunities for innovative early detection and prevention approaches. This article covers the spectrum of ICH in the preterm infant, including germinal matrix intraventricular hemorrhage, its complications, and associated phenomena, such as the emerging role of cerebellar hemorrhage. The overall aim of this article is to review the current knowledge of the mechanisms, diagnosis, outcome, and management of preterm ICH; to revisit the origins from which they develop; and to discuss future expectations.

Oxidative stress disrupts oligodendrocyte maturation

Periventricular white matter injury (PWMI) is the leading cause of chronic neurologic injury among survivors of preterm birth. The hallmark of PWMI is hypomyelination and a lack of mature, myelinating oligodendrocytes. Oligodendrocytes undergo a well-characterized lineage progression from neural stem cell to mature oligodendrocyte. Oligodendrocyte precursors have increased susceptibility to oxidative and free radical-mediated injury compared with mature oligodendrocytes as a result of lower levels of antioxidant enzymes and free radical scavengers. In this study, we show that oxidative stress disrupts oligodendrocyte differentiation by two mechanisms. First, oxidizing agents decrease the expression of key genes that promote oligodendrocyte differentiation from neural stem cells and increase the expression of genes known to inhibit differentiation. Second, global histone acetylation persists under conditions of oxidative stress, further contributing to the prevention of oligodendrocyte differentiation. Both of these mechanisms result in the arrest of oligodendrocyte differentiation without an increase in cell death.

The ELGAN study of the brain and related disorders in extremely low gestational age newborns

BACKGROUND

Extremely low gestational age newborns (ELGANs) are at increased risk for structural and functional brain abnormalities.

AIM

To identify factors that contribute to brain damage in ELGANs.

STUDY DESIGN

Multi-center cohort study.

SUBJECTS

We enrolled 1506 ELGANs born before 28 weeks gestation at 14 sites; 1201 (80%) survived to 2 years corrected age. Information about exposures and characteristics was collected by maternal interview, from chart review, microbiologic and histological examination of placentas, and measurement of proteins in umbilical cord and early postnatal blood spots.

OUTCOME MEASURES

Indicators of white matter damage, i.e. ventriculomegaly and echolucent lesions, on protocol cranial ultrasound scans; head circumference and developmental outcomes at 24 months adjusted age, i.e., cerebral palsy, mental and motor scales of the Bayley Scales of Infant Development, and a screen for autism spectrum disorders.

RESULTS

ELGAN Study publications thus far provide evidence that the following are associated with ultrasongraphically detected white matter damage, cerebral palsy, or both: preterm delivery attributed to preterm labor, prelabor premature rupture of membranes, or cervical insufficiency; recovery of microorganisms in the placenta parenchyma, including species categorized as human skin microflora; histological evidence of placental inflammation; lower gestational age at delivery; greater neonatal illness severity; severe chronic lung disease; neonatal bacteremia; and necrotizing enterocolitis.

CONCLUSIONS

In addition to supporting a potential role for many previously identified antecedents of brain damage in ELGANs, our study is the first to provide strong evidence that brain damage in extremely preterm infants is associated with microorganisms in placenta parenchyma.

Interleukin-1beta-induced brain injury in the neonatal rat can be ameliorated by alpha-phenyl-n-tert-butyl-nitrone

To examine the possible role of inflammatory cytokines in mediating perinatal brain injury, we investigated effects of intracerebral injection of interleukin-1beta (IL-1beta) on brain injury in the neonatal rat and the mechanisms involved. Intracerebral administration of IL-1beta (1 microg/kg) resulted in acute brain injury, as indicated by enlargement of ventricles bilaterally, apoptotic death of oligodendrocytes (OLs) and loss of OL immunoreactivity in the neonatal rat brain. IL-1beta also induced axonal and neuronal injury in the cerebral cortex as indicated by elevated expression of beta-amyloid precursor protein, short beaded axons and dendrites, and loss of tyrosine hydroxylase-positive neurons in the substantia nigra and the ventral tegmental areas. Administration of alpha-phenyl-n-tert-butyl-nitrone (PBN, 100 mg/kg i.p.) immediately after the IL-1beta injection protected the brain from IL-1beta-induced injury. Protection of PBN was linked with the attenuated oxidative stress induced by IL-1beta, as indicated by decreased elevation of 8-isoprostane content and by the reduced number of 4-hydroxynonenal or malondialdehyde or nitrotyrosine-positive cells following IL-1beta exposure. PBN also attenuated IL-1beta-stimulated inflammatory responses as indicated by the reduced activation of microglia. The finding that IL-1beta induced perinatal brain injury was very similar to that induced by lipopolysaccharide (LPS), as we previously reported and that PBN was capable to attenuate the injury induced by either LPS or IL-1beta suggests that IL-1beta may play a critical role in mediating brain injury associated with perinatal infection/inflammation.

Endoplasmic reticulum stress, inflammation, and perinatal brain damage

Inflammation seems to play a role in the pathogenesis of perinatal brain damage in fetuses/infants born much before term. We raise the possibility that noninflammatory phenomena induce endoplasmic reticulum stress, which, in turn, leads to the unfolded protein response, which is followed by apoptosis-promoting processes and inflammation. Perhaps by these events, noninflammatory stimuli lead to perinatal brain damage.

Maternal antenatal complications and the risk of neonatal cerebral white matter damage and later cerebral palsy in children born at an extremely low gestational age

In a 2002-2004 prospective cohort study of deliveries of infants at <28 weeks at 14 US centers, the authors sought the antecedents of white matter damage evident in newborn cranial ultrasound scans (ventriculomegaly and an echolucent lesion) and of cerebral palsy diagnoses at age 2 years. Of the 1,455 infants enrolled, those whose mothers received an antenatal steroid tended to have lower risks of ventriculomegaly and an echolucent lesion than their peers (10% vs. 23%, P < 0.001 and 7% vs. 11%, P = 0.06, respectively). Risk of ventriculomegaly was increased for infants delivered because of preterm labor (adjusted odds ratio (OR) = 2.3, 95% confidence interval (CI): 1.1, 4.9), preterm premature rupture of fetal membranes (OR = 3.6, 95% CI: 1.5, 8.7), and cervical insufficiency (OR = 2.8, 95% CI: 1.4, 5.5) when compared with infants delivered because of preeclampsia. Risk of an echolucent lesion was increased for infants delivered because of preterm labor (OR = 2.7, 95% CI: 1.2, 5.7) and intrauterine growth retardation (OR = 3.3, 95% CI: 1.2, 9.4). The doubling of diparesis risk associated with preterm labor and with preterm premature rupture of fetal membranes did not achieve statistical significance, nor did the doubling of quadriparesis risk and the tripling of diparesis risk associated with cervical insufficiency.

Fragment Bb in amniotic fluid: evidence for complement activation by the alternative pathway in women with intra-amniotic infection/inflammation

OBJECTIVE

Fragment Bb is an activator of the alternative pathway of the complement system. Recently, increased first trimester maternal plasma concentrations of this fragment were reported in patients destined to have a spontaneous preterm delivery before 34 weeks of gestation. The aim of this study was to determine whether the amniotic fluid (AF) concentrations of fragment Bb change with gestational age, spontaneous labor (term and preterm) and in the presence of intra-amniotic infection/inflammation (IAI).

STUDY DESIGN

This cross-sectional study included patients in the following groups: (1) mid-trimester (n = 64); (2) term in spontaneous labor (n = 70); (3) term not in labor (n = 43); (4) spontaneous preterm labor (PTL) who delivered at term (n = 76); (5) PTL without IAI who delivered preterm (n = 73); (6) PTL with IAI (n = 76); (7) preterm prelabor rupture of membranes (PROM) without IAI (n = 71); and (8) preterm PROM with IAI (n = 71). Fragment Bb concentration in AF was determined by an enzyme-linked immunoassay. Non-parametric statistics were used for analyses.

RESULTS

(1) Fragment Bb was detected in all AF samples (n = 544); (2) The median AF concentration of fragment Bb in patients at term not in labor was significantly higher than that of those in the mid-trimester [2.42 microg/ml, interquartile range (IQR) 1.78-3.22 vs. 1.64 microg/ml, IQR 1.06-3.49; p < 0.001]; (3) Among patients with PTL, those with IAI had a higher median AF fragment Bb concentration than that of woman without IAI, who delivered preterm (4.82 microg/ml, IQR 3.32-6.08 vs. 3.67 microg/ml, IQR 2.35-4.57; p < 0.001) and than that of women with an episode of PTL, who delivered at term (3.21 microg/ml, IQR 2.39-4.16; p < 0.001); (4) Similarly, among patients with preterm PROM, the median AF fragment Bb concentration was higher in individuals with IAI than in those without IAI (4.24 microg/ml, IQR 2.58-5.79 vs. 2.79 microg/ml, IQR 2.09-3.89; p < 0.001). (5) Among patients at term, the median AF fragment Bb concentration did not differ between women with spontaneous labor and those without labor (term in labor: 2.47 microg/ml, IQR 1.86-3.22; p = 0.97).

CONCLUSIONS

(1) Fragment Bb, an activator of the alternative complement pathway, is a physiologic constituent of the AF, and its concentration increases with advancing gestational age; (2) AF concentrations of fragment Bb are higher in pregnancies complicated with IAI; and (3) labor at term is not associated with changes in the AF concentrations of fragment Bb. These findings suggest a role for fragment Bb in the host immune response against IAI.

The negative regulators of the host immune response: an unexplored pathway in preterm birth

OBJECTIVE

Toll-like receptors (TLRs) are essential mediators of host immunity. TLR activation must be tightly regulated to prevent an exaggerated immune response from devastating the host. These studies assessed the expression of negative regulators (interleukin receptor-associated kinase [IRAK]-3, IRAK-1, Fas-associated protein with death domain) during pregnancy and in preterm birth (PTB).

STUDY DESIGN

Tissues (uterine, cervix, placenta, and spleens) from the following experimental groups were harvested: (1) nonpregnant mice, (2) pregnant mice across gestation, (3) murine model of PTB, and (4) pregnant mice exposed to medroxyprogesterone acetate (MPA).

RESULTS

Negative regulators are differentially expressed in the uterus during pregnancy. In the setting of PTB, IRAK-3 is significantly increased in the uterus and cervix but not the placenta. In maternal spleens, IRAK-3 and IRAK-1 are increased in response to intrauterine inflammation. MPA can increase IRAK expression in cervical tissues.

CONCLUSION

Negative regulators of the maternal immune response may play an important role in protecting pregnancies from an exaggerated inflammatory response.

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.

Intrauterine endotoxin administration leads to white matter diffusivity changes in newborn rabbits

Maternal intrauterine inflammation has been implicated in the development of periventricular leukomalacia and white matter injury in the neonate. We hypothesized that intrauterine endotoxin administration would lead to microstructural changes in the neonatal rabbit white matter in vivo that could be detected at birth using diffusion tensor magnetic resonance imaging (MRI). Term newborn rabbit kits (gestational age 31 days) born to dams exposed to saline or endotoxin in utero on gestational day 28 underwent diffusion tensor imaging, and brain sections were stained for microglia. Comparison between normal and endotoxin groups showed significant decreases in both fractional anisotropy and eigenvalue (e(1)) in all periventricular white matter regions that showed an increase in the number of activated microglial cells, indicating that after maternal inflammation, microglial infiltration may predominantly explain this change in diffusivity in the immediate neonatal period. Diffusion tensor imaging may be a clinically useful tool for detecting neuroinflammation induced by maternal infection in neonatal white matter.

''Intraventricular'' hemorrhage and cystic periventricular leukomalacia in preterm infants: how are they related?

Intraventricular hemorrhage and cystic periventricular leukomalacia are often co-occurring characteristics of brain damage in preterm infants. Using data from 1016 infants born before 30 completed weeks' gestational age, we sought to clarify the relationship between severe intraventricular hemorrhage and cystic periventricular leukomalacia, with special emphasis on common antecedents and potential confounding. After comparing risk factors for intraventricular hemorrhage grades 1 through 4 and cystic periventricular leukomalacia, it appears the risk patterns for intraventricular hemorrhage grade 3, intraventricular hemorrhage grade 4, and cystic periventricular leukomalacia differ. The association between intraventricular hemorrhage grade 3 and cystic periventricular leukomalacia differs appreciably from the association between intraventricular hemorrhage grade 4 and cystic periventricular leukomalacia, supporting the notion that intraventricular hemorrhage grade 3 and intraventricular hemorrhage grade 4 are different entities. The presence of intraventricular hemorrhage grade 3 and intraventricular hemorrhage grade 4 increases the risk of cystic periventricular leukomalacia, even after adjusting for potential confounders. This raises the possibility that intraventricular hemorrhage grade 3 and intraventricular hemorrhage grade 4 cause cystic periventricular leukomalacia.

Chorioamnionitis and brain damage in the preterm newborn

AIM

To evaluate the association between histological chorioamnionitis and brain damage (intraventricular hemorrhage and cystic periventricular leukomalacia) in the preterm newborn.

METHODS

This was a retrospective study on neonates born at less than 34 weeks gestational age, and their respective mothers, at three tertiary medical centers in the north of Portugal, from January 2001 to December 2002.

RESULTS

The study included 452 newborns (235 male/217 female; birth weight 1440 (515-2620) grams; gestational age 31 (23-33) weeks), 125 from mothers whose placenta showed signs of chorioamnionitis and 327 from mothers without the condition. The association between histological chorioamnionitis and: (1) intraventricular hemorrhage grades I-IV was OR 1.43 (95% CI 0.49-3.94); (2) intraventricular hemorrhage grades III and IV was OR 2.49 (95% CI 1.20-5.11); (3) cystic periventricular leukomalacia was OR 3.02 (95% CI 1.50-6.07). The association, adjusted for birth weight and gestational age, between chorioamnionitis and: (1) intraventricular hemorrhage grades III and IV was OR 0.94 (95% CI 0.39-2.28); (2) cystic periventricular leukomalacia was OR 1.94 (95% CI 1.03-4.61). The association between histological chorioamnionitis with funisitis and/or vasculitis and: (1) intraventricular hemorrhage grades I to IV was OR 1.27 (95% CI 0.52-3.10); (2) cystic periventricular leukomalacia was OR 2.08 (95% CI 0.72-5.98).

CONCLUSION

This study confirms the association between histological chorioamnionitis and cystic periventricular leukomalacia, but was unable to confirm the association between histological chorioamnionitis and intraventricular hemorrhage.

Adverse neurodevelopmental outcome in preterm infants: risk factor profiles for different gestational ages

AIM

Assessment of risk predictors for adverse neurodevelopmental outcome at 1 year of age in preterm infants with a gestational age <30 weeks (Group I) and 30-32 weeks (Group II).

METHODS

Between January 2003 and December 2006, we prospectively enrolled 310 live-born infants between 23 and 32 weeks of gestation. The association between candidate risk factors and delayed motor or mental development (Bayley Scales of infant development II; psychomotor or mental developmental index <85) was analysed by means of logistic regression analysis.

RESULTS

Two hundred and fifty infants were eligible for follow-up, and 205 (82.0%) completed the follow-up visit. Intracerebral haemorrhage, small for gestational age and late-onset sepsis were associated with an increased risk for delayed development in Group I (p < 0.05, each). Premature rupture of membranes was a risk condition relevant to Group II. Antenatal steroids were associated with a decreased risk of neurodevelopmental delay in both groups.

CONCLUSION

This study identified distinct risk factors for adverse outcome in preterm infants of lower (<30 weeks) and higher (30-32 weeks) gestational age. In the lower gestational age group, neonatal risk predictors are most important. Antenatal steroids appear to decrease the risk for adverse outcome in both age groups.

Transient lipopolysaccharide-induced cytokine responses in the maternal serum and amniotic fluid of the guinea pig

OBJECTIVE

The aim of this study was to characterize the pregnant guinea pig cytokine time course following a maternal inflammatory insult.

STUDY DESIGN

Pregnant guinea pigs (n = 34) were injected intraperitoneally with 100 microg/kg lipopolysaccharide (LPS) at 70% gestation and euthanized at 24 hours, 48 hours, or 5 days. Control animals were euthanized at 70% gestation without LPS exposure. Interleukin (IL)-6, IL-1beta, and tumor necrosis factor-alpha (TNF-alpha) were quantified in the maternal serum and amniotic fluid by an enzyme-linked immunosorbent assay.

RESULTS

IL-6 and IL-1beta concentrations were elevated in the maternal serum at 24 hours and returned to control levels by 5 days. In the amniotic fluid, IL-6 peaked at 48 hours and IL-1beta at 24 hours. TNF-alpha levels were not significantly increased.

CONCLUSION

Maternal intraperitoneal LPS injection produces transient increases in cytokine concentrations in the maternal serum and amniotic fluid within 5 days, further implicating the cytokines as mediators of fetal white matter damage.

Relationships among prenatal aeroallergen exposure and maternal and cord blood IgE: project ACCESS

BACKGROUND

Whereas some evidence suggests that antigen sensitization may begin prenatally, the influence of maternal allergen exposure during pregnancy has not been fully elucidated.

OBJECTIVES

We examined the relationship between prenatal maternal aeroallergen exposure and cord blood total IgE and the potential mediating/indirect effect of maternal immune response.

METHODS

This study was performed in 301 mother-infant pairs enrolled in the Asthma Coalition on Community, Environment, and Social Stress (ACCESS) project, a study examining the effects of prenatal and early life social and physical environmental exposures on urban asthma risk. Dust samples collected prenatally from mothers' bedrooms were analyzed for cockroach and dust mite allergens. Cord blood was analyzed for total IgE, and maternal serum collected during pregnancy for total and specific IgE. We assessed the relationship between prenatal exposure and cord blood total IgE and the potential mediation effect adjusting for maternal age, race, education, smoking status, and dust collection season; and child's sex and season of birth.

RESULTS

In multivariate models, elevated prenatal dust mite levels (>0.2 microg/g) increased cord blood IgE concentrations by 29% (P = .08), and continuous dust mite concentration was associated with a significant nonlinear increase in cord blood IgE (P = .02). Elevated prenatal exposure to cockroach allergen (>2 U/g) was not associated with cord blood IgE, but showed a significant indirect relationship through maternal total IgE (beta = 0.23; 95% CI, 0.08-0.41).

CONCLUSION

These results demonstrate that maternal prenatal exposure to household allergens may affect cord blood IgE, albeit the underlying mechanism may be allergen-specific.

Maternal genitourinary infection and risk of cerebral palsy

AIM

To examine the association between genitourinary infection during pregnancy and cerebral palsy (CP) in children.

METHOD

Medicaid and birth certificate data were obtained for 135 835 pregnant women with singleton births paid for by Medicaid from 1996 to 2002. Linked Medicaid billing data were obtained for their children in 2007. The association between maternal genitourinary infection and CP was modeled using generalized estimating equations.

RESULTS

Maternal genitourinary infection was significantly associated with CP (odds ratio [OR]=1.27, p=0.007). Additional analyses revealed that the association was strongly significant for preterm or low birthweight infants when maternal infection was diagnosed in the first two trimesters of pregnancy (OR=1.62, p<0.001). This association remained (OR=1.72, p<0.001) when the model was limited to cases of CP diagnosed by at least two different clinicians. Infection was not significantly associated with CP in term or normal-birthweight infants.

INTERPRETATION

Maternal genitourinary infection occurring in the first two trimesters was associated with increased risk of CP in preterm or low-birthweight children. Additional research is needed to determine whether this association is affected by antimicrobial treatment.

A multicenter study on the clinical outcome of chorioamnionitis in preterm infants

OBJECTIVE

The purpose of this study was to examine the effects of clinical maternal chorioamnionitis on morbidity and mortality rates among infants who are at < 33 weeks of gestation, adjusted for patient characteristics that included admission neonatal illness severity (Score for Neonatal Acute Physiology, version II; SNAP-II).

STUDY DESIGN

With multivariate logistic regression analysis, prospectively collected hospital outcomes from the Canadian Neonatal Network of singleton infants with birth gestational age of < 33 weeks and clinical chorioamnionitis were compared retrospectively with nonexposed infants.

RESULTS

Of 3094 infants, 477 infants (15.4%) who were exposed to clinical chorioamnionitis had significantly higher admission SNAP-II scores. Bivariate analysis revealed that the neonatal mortality rate was increased significantly in the chorioamnionitis group (10.6% vs 6.1%). Multivariate regression analysis with adjustment for illness severity indicated that chorioamnionitis was associated with an increased risk of early sepsis (odds ratio, 5.54; 95% confidence interval, 2.87-10.69) and severe intraventricular hemorrhage (odds ratio, 1.62; 95% confidence interval, 1.17-2.24) but not neonatal death.

CONCLUSION

Preterm infants who are exposed to clinical chorioamnionitis have an increased risk of early-onset sepsis and severe intraventricular hemorrhage.

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.

Cystic periventricular leukomalacia in preterm infants: an analysis of obstetric risk factors

OBJECTIVE

To identify obstetric risk factors and to elucidate the effect of prolonged rupture of the membranes on the development of cystic periventricular leukomalacia (PVL) in preterm infants.

METHODS

A retrospective case-control study of 95 preterm infants with the diagnosis of PVL and 245 healthy controls matched for gestational age. A total of 52 antenatal, intrapartum and neonatal characteristics were studied by univariate methods and logistic regression.

RESULTS

Preterm premature rupture of membranes (PPROM) (odds ratio 2.1 [95% CI 1.3-3.4], P=.003), gestational age at PPROM (P=.025), prolonged rupture of membranes (P<.0001), administration of tocolytic agents (1.8 [1.1-3.0], P=.019) and antibiotics (1.9 [1.2-3.1], P=.008) were associated with PVL. The use of tocolytic agents >24 h (P=.008), prolonged latency between the increase in maternal leukocyte count and birth (P=.034), spontaneous onset of labor (1.8 [1.0-2.9], P=.026), vaginal delivery (1.7 [1.1-2.8], P=.029) and male gender (1.5 [1.0-2.0], P=.04) were found more frequently in PVL cases. Preeclampsia (0.4 [0.1-0.9], P=.034), hypertension at booking (P=.009), sonographic IUGR (P=.020), abnormal blood flow of the umbilical artery (P=.032) and cesarean section without labor (0.5 [0.3-0.8], P=.006) were found less frequently. In logistic regression analysis, prolonged rupture of the membranes (P=.748), preeclampsia (P=.973), the use of antibiotics (P=.617) and beta-sympathomimetic tocolytic agents (P=.563) lost statistical significance, whereas birth weight (P=.036) became significant.

CONCLUSION

PPROM and prolonged rupture of the membranes may provoke adverse effects on the neurodevelopmental outcome of the preterm fetus. These findings may have implications on the obstetric management of PPROM beyond 30 weeks of gestation. Cesarean section without labor was less likely associated with the diagnosis of PVL.

Factors involved in inflammation-induced developmental white matter damage

Developmental white matter damage is a brain pathology associated with several long-term neurological disorders. An inflammatory insult has been suggested as the major instigating event. This study investigated the relative influence of inflammation, blood-brain barrier permeability and glial ontogeny in white matter damage. Systemic inflammation was induced in Monodelphis domestica (opossum) by serial intraperitoneal injections of lipopolysaccharide at different stages of brain development. Volume of white matter was estimated for the external capsule. Blood-brain barrier permeability was assessed immunocytochemically. Quantitative RT-PCR was used to measure relative levels of mRNA for IL-1beta, IL-6 and COX-2. Developmental changes in numbers and appearance of microglia and astrocytes were estimated. Results showed that in response to systemic inflammation, white matter was reduced in the external capsule during a circumscribed period only. At the same developmental stage blood-brain barrier permeability was altered, cerebral inflammatory response was present and numbers of microglia increased. However, the periods of altered blood-brain barrier permeability and the cerebral inflammatory response were longer than the period of the external capsule's susceptibility to white matter damage, which coincided with the developmental increase in the number of astrocytes in this tract. Thus, the mechanism of white matter damage following systemic inflammation is multifactorial, including cerebral inflammation and breakdown of brain barriers occurring simultaneously at specific stages of glial cell development.

Genetic susceptibility to infection-mediated preterm birth

Preterm birth is a heterogeneous disorder that is responsible for significant neonatal morbidity and mortality. Intrauterine infection is implicated in a significant proportion of preterm birth-particularly in early gestation. Epidemiologic evidence supports a genetic component to infection overall and preterm birth in particular. Furthermore, a number of studies examining genes involved in pathogen recognition and our response to pathogens suggest a genetic susceptibility to infection-mediated preterm birth. On the whole, however, these studies have been difficult to replicate and explain only a small portion of the phenotypic variation in preterm birth. Given this, methodological considerations are emphasized to improve our understanding of the genetic susceptibility to infection-mediated preterm birth.

Soluble receptor for advanced glycation end products (sRAGE) and endogenous secretory RAGE (esRAGE) in amniotic fluid: modulation by infection and inflammation

OBJECTIVE

The receptor for advanced glycation end products (RAGE) has been proposed to participate in the innate and adaptive immune responses. RAGE can induce production of pro-inflammatory cytokines and chemokines, as well as neutrophil chemotaxis in a manner that may be suppressed or stimulated by soluble, truncated forms of RAGE including the soluble form of RAGE (sRAGE) and endogenous secretory RAGE (esRAGE). The objective of this study was to determine whether intra-amniotic infection/inflammation (IAI) is associated with changes in the amniotic fluid concentration of sRAGE and esRAGE.

STUDY DESIGN

Amniotic fluid (AF) was retrieved from patients in the following groups: 1) mid-trimester (14-18 weeks of gestation; n=68); 2) term not in labor (n=24); 3) term in labor (n=51); 4) preterm labor and intact membranes (n=124); and 5) preterm PROM (n=80). Intra-amniotic infection and inflammation were defined as the presence of a positive amniotic fluid culture for microorganisms and an AF interleukin-6 concentration >or=2.6 ng/mL, respectively. The AF concentration of sRAGE and esRAGE were determined using specific and sensitive ELISAs which measured total immunoreactive sRAGE and esRAGE, respectively. Patients were matched for gestational age at amniocentesis to compare the AF concentration of sRAGE and esRAGE in patients with and without IAI. Non-parametric statistics were used for analysis and a P<0.05 was considered significant.

RESULTS

1) Patients at term not in labor had higher median AF concentrations of sRAGE and esRAGE than those in the mid-trimester (P<0.001 for both comparisons) and those at term in labor (P=0.03 and P=0.04, respectively); 2) patients with preterm labor and intact membranes with intra-amniotic infection/inflammation (IAI) had higher median AF concentrations of sRAGE and esRAGE than those without IAI (P=0.02 and P=0.005, respectively); 3) similarly, patients with preterm PROM with IAI had higher median AF concentrations of sRAGE and esRAGE than those without IAI (P=0.03 and P=0.02, respectively).

CONCLUSION

Intra-amniotic infection/inflammation is associated with increased amniotic fluid concentrations of sRAGE and esRAGE. Changes in the amniotic fluid concentration of sRAGE and esRAGE may represent part of the immune response to intra-amniotic infection/inflammation.

Second-trimester histopathological placental findings in maternal-fetal inflammatory response syndrome

Immature delivery is frequently associated with a maternal-fetal inflammatory response at the placental level. The aims of this study were to determine the prevalence, staging, and grading of histological findings (associated with acute maternal-fetal inflammatory response syndrome) in placentas of immature fetuses and to establish the relationship between maternal and fetal responses and its frequency distribution by fetal weight. The studied placentas corresponded to fetuses with weights ranging between 12 g and 625 g. The inflammatory response was classified according to the criteria published by the Perinatal Section of the Society for Pediatric Pathology. Of the 354 placentas analyzed, 231 (65.3%) showed acute inflammatory response. In 98.7% of the cases, inflammation was classified as maternal inflammatory response (MIR) and in 49.8% as fetal inflammatory response (FIR). In 49.1% of the cases, MIR was accompanied by FIR, whereas only 3 cases of FIR did not show MIR. As their stages increased, fetal response rates and the severity of MIR and FIR grew at higher stages of maternal response. Although the frequency of MIR was similar in different fetal weight groups, that of FIR increased with weight and gestational age.

Prenatal lipopolysaccharide does not accelerate progressive dopamine neuron loss in the rat as a result of normal aging

We previously demonstrated that in utero exposure to the bacteriotoxin lipopolysaccharide (LPS) led to the birth of rat pups with fewer than normal dopamine (DA) neurons. These animals exhibited significant neuroinflammation in the nigrostriatal pathway creating the possibility that they could exhibit further, progressive DA neuron loss over their lives. To study this possibility, we injected gravid female rats i.p. at 10,000 endotoxin units (EUs) of LPS per kg or saline at embryonic (E) day 10.5 and assigned pups to sacrifice groups at 4, 14 and 17 months such that littermates were sacrificed at each end point. The effects of prenatal LPS on DA cell counts and striatal DA were significantly reduced relative to controls whereas DA activity and numbers of activated microglia (OX-6ir cell) were statistically increased. However, the progressive DA neuron loss was parallel to that of the controls suggesting that prenatal LPS does not produce an accelerated rate of DA neuron loss. Interestingly, locomotor activity was increased after 3 months in animals exposed to LPS prenatally, but by 16 months, was significantly reduced relative to controls. Additionally, animals exposed to LPS prenatally exhibited Lewy body-like inclusions that were first seen in 14 month old animals. These data broadly support previous studies demonstrating that prenatal exposure to LPS, as frequently occurs in humans as part of Bacterial Vaginosis, leads to the birth of animals with fewer than normal DA neurons. The progressive DA neuron loss seen in these animals is, however, primarily a result of normal aging.

Cytokines and perinatal brain damage

Perinatal brain damage has been implicated in the pathogenesis of neurodevelopmental impairments and psychiatric illnesses. This article reviews evidence that infection outside of the brain can damage the brain, and discusses specific cytokines and pathomechanisms that probably mediate the putative effect of remote infection on the developing brain. Events associated with increased circulating inflammatory cytokines, chemokines, and immune cells are described. Finally, studies of genetic variation in susceptibility to cytokine-related brain damage are reviewed.

Resistin in amniotic fluid and its association with intra-amniotic infection and inflammation

OBJECTIVE

Intra-amniotic infection/inflammation (IAI) is one of the most important mechanisms of disease in preterm birth. Resistin is an adipocytokine that has been linked to insulin resistance, diabetes, obesity and inflammation. The objective of this study was to determine if resistin is present in amniotic fluid (AF) and if its concentration changes with gestational age, in the presence of labour, and in IAI in patients with spontaneous preterm labour (PTL) and intact membranes, preterm prelabour rupture of membranes (PPROM) and clinical chorioamnionitis.

STUDY DESIGN

This cross-sectional study included 648 patients in the following groups: (1) women in the mid-trimester of pregnancy (14-18 weeks) who underwent amniocentesis for genetic indications and delivered a normal neonate at term (n = 61); (2) normal pregnant women at term with (n = 49) and without (n = 50) spontaneous labour; (3) patients with an episode of PTL and intact membranes who were classified into: (a) PTL who delivered at term (n = 153); (b) PTL who delivered preterm (<37 weeks gestation) without IAI (n = 108); and (c) PTL with IAI (n = 84); (4) women with PPROM with (n = 47) and without (n = 44) IAI; and (5) patients with clinical chorioamnionitis at term with (n = 22) and without (n = 30) microbial invasion of the amniotic cavity. Resistin concentration in AF was determined by enzyme-linked immunoassay. Non-parametric statistics were used for analyses.

RESULTS

(1) Resistin was detected in all AF samples; (2) the median AF resistin concentration at term was significantly higher than in the mid-trimester (23.6 ng/mL vs. 10 ng/mL; p < 0.001); (3) among patients with PTL, the median AF resistin concentration was significantly higher in patients with IAI than in those without IAI (144.9 ng/mL vs. 18.7 ng/mL; p < 0.001) and those with PTL and intact membranes who delivered at term (144.9 ng/mL vs. 16.3 ng/mL; p < 0.001); (4) patients with PPROM with IAI had a significantly higher median AF resistin concentration than those without IAI (132.6 ng/mL vs. 13 ng/mL; p < 0.001); (5) no significant differences were observed in the median AF resistin concentration between patients with spontaneous labour at term and those at term not in labour (28.7 ng/mL vs. 23.6 ng/mL; p = 0.07); and (6) AF resistin concentration > or =37 ng/mL (derived from a receiver-operating characteristic curve) had a sensitivity of 85.4% and a specificity of 94.3% for the diagnosis of intra-amniotic inflammation.

CONCLUSIONS

Resistin is a physiologic constituent of the AF, and its concentrations in AF: (1) are significantly elevated in the presence of IAI; (2) increase with advancing gestation; and (3) do not change in the presence of spontaneous labour at term. We propose that resistin may play a role in the innate immune response against intra-amniotic infection.

Intrauterine administration of endotoxin leads to motor deficits in a rabbit model: a link between prenatal infection and cerebral palsy

OBJECTIVE

This study was undertaken to determine whether maternal intrauterine endotoxin administration leads to neurobehavioral deficits in newborn rabbits.

STUDY DESIGN

Pregnant New Zealand white rabbits were injected with 1 mL saline solution (n = 8) or 20 microg/kg of lipopolysaccharide in saline solution (n = 8) into the uterine wall on day 28/31 of gestation. On postnatal day 1, kits (saline solution [n = 30] and lipolysaccharide in saline solution [n = 18] from 4 consecutive litters) underwent neurobehavioral testing. Neonatal brains were stained for microglial cells and myelin.

RESULTS

Kits in the lipopolysaccharide in saline solution group were hypertonic and demonstrated significant impairment in posture, righting reflex, locomotion, and feeding, along with neuroinflammation indicated by activated microglia and hypomyelination in the periventricular regions. A greater mortality was noted in the lipopolysaccharide in saline solution group (16 stillbirths from 3 litters vs 3 from 1 litter).

CONCLUSION

Maternal intrauterine endotoxin administration leads to white matter injury and motor deficits in the newborn rabbit, resulting in a phenotype that resembles those found in periventricular leukomalacia and cerebral palsy.