Role of the fetus in perinatal infection and neonatal brain damage

Simulation of intra-amniotic infection and the fetal inflammatory response in a novel ex-vivo human umbilical cord perfusion model

OBJECTIVE

We aimed to design and test an ex-vivo human umbilical cord (HUC) perfusion model simulating a fetal inflammatory response (FIR) during intra-amniotic infection.

STUDY DESIGN

A 2-chamber model was designed to accommodate 2 pieces of umbilical cord. Cord perfusion was performed with placental blood. Intra-amniotic exposure to infectious organisms was simulated by adding lipopolysaccharide to the artificial amniotic fluid (AAF) compartment. As a measure of inflammatory response, we used interleukin 8 (IL-8) concentration in AAF and plasma by enzyme-linked immunosorbent assay (ELISA). Wilcoxon signed rank test was used for statistical analysis.

RESULTS

We established a stable physiological setup. Results revealed significantly elevated plasma IL-8 concentrations (n = 6, P < .05) in the blood compartment of umbilical cords exposed to lipopolysaccharide. Concentrations within AAF were not significantly elevated (n = 6, P = .3095).

CONCLUSION

Simulation of a FIR in an ex-vivo model of HUC perfusion under physiological conditions is possible. Further work is necessary to establish histological funisitis.

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.

Risk factors for cerebral palsy in term birth infants

PURPOSE

The aim of this study was to identify the antenatal, intrapartum and neonatal risk factors in term birth infants for cerebral palsy (CP) among babies in a hospital-based study.

MATERIALS AND METHODS

The medical records of children with cerebral palsy referred to our Pediatric Rehabilitation Department in Bialystok were reviewed. Antenatal, intrapartum, and neonatal events were compared among 213 children with CP and 280 controls in a retrospective study. We studied live births >36 weeks gestation born between January 1, 1990, and December 31, 2005.

RESULTS

Fifty-seven percent of the infants with CP were male. Spastic tetraplegia 78 (36.61%) and spastic hemiplegia 65 (30.51%) were the dominant types of CP. Factors associated with an increased risk of CP identified as antenatal and intrapartum risk factors were pre-eclampsia, abruptio placenta, and placenta previa. Birth asphyxia occurred significantly more often (p<0.001) in children with CP compared to controls. In the neonatal period, respiratory distress syndrome, meningitis and neonatal seizures were associated with an increased incidence of CP.

CONCLUSION

Our findings confirm that several antenatal, intrapartum and neonatal risk factors for CP in term birth infants contribute to the etiology of CP.

Microbiologic and histologic characteristics of the extremely preterm infant's placenta predict white matter damage and later cerebral palsy. the ELGAN study

Inflammatory phenomena seem to contribute to the occurrence of perinatal cerebral white matter damage and CP. The stimulus that initiates the inflammation remains obscure. One thousand two hundred forty-six infants born before the 28th postmenstrual week had a protocol ultrasound scan of the brain read concordantly by two independent sonologists. Eight hundred ninety-nine of the children had a neurologic examination at approximately 24-mo postterm equivalent. The placenta of each child had been biopsied under sterile conditions and later cultured. Histologic slides of the placenta were examined specifically for this study. Recovery of a single microorganism predicted an echolucent lesion, whereas polymicrobial cultures and recovery of skin flora predicted both ventriculomegaly and an echolucent lesion. Diparetic CP was predicted by recovery of a single microorganism, multiple organisms, and skin flora. Histologic inflammation predicted ventriculomegaly and diparetic CP. The risk of ventriculomegaly associated with organism recovery was heightened when accompanied by histologic inflammation, but the risk of diparetic CP was not. Low-virulence microorganisms isolated from the placenta, including common skin microflora, predict ultrasound lesions of the brain and diparetic CP in the very preterm infant. Organism recovery does not seem to be needed for placenta inflammation to predict diparetic CP.

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.

Modulation of fetal inflammatory response on exposure to lipopolysaccharide by chorioamnion, lung, or gut in sheep

OBJECTIVE

We hypothesized that fetal lipopolysaccharide exposures to the chorioamnion, lung, or gut would induce distinct systemic inflammatory responses.

STUDY DESIGN

Groups of 5-7 time-mated ewes were used to surgically isolate the fetal respiratory and the gastrointestinal systems from the amniotic compartment. Outcomes were assessed at 124 days gestational age, 2 days and 7 days after lipopolysaccharide (10 mg, Escherichia coli 055:B5) or saline solution infusions into the fetal airways or amniotic fluid.

RESULTS

Lipopolysaccharide induced systemic inflammatory changes in all groups in the blood, lung, liver, and thymic lymphocytes. Changes in lymphocytes in the posterior mediastinal lymph node draining lung and gut, occurred only after direct contact of lipopolysaccharide with the fetal lung or gut.

CONCLUSION

Fetal systemic inflammatory responses occurred after chorioamnion, lung, or gut exposures to lipopolysaccharide. The organ responses differed based on route of the fetal exposure.

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.

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.

Heart rate characteristics and neurodevelopmental outcome in very low birth weight infants

BACKGROUND

Sepsis in very low birth weight (VLBW) infants has been associated with an increased risk of adverse developmental outcome. We have identified abnormal heart rate characteristics (HRCs) that are predictive of impending sepsis, and we have developed a summary measure of an infant's abnormal HRCs during the neonatal hospitalization that we refer to as the cumulative HRC score (cHRC).

OBJECTIVE

In this study, we tested the hypothesis that increasing cHRC is associated with an increasing risk of adverse neurodevelopmental outcome in VLBW infants.

METHOD

Data were collected on 65 VLBW infants whose HRCs were monitored while in the neonatal intensive care unit and who were examined at 12 to 18 months adjusted age. Using the Bayley Scale of Infant Development-II, we identified delays in early cognitive function (i.e., Mental Developmental Index <70) and psychomotor development (i.e., Psychomotor Developmental Index <70). Cerebral palsy (CP) was diagnosed using a standard neurological examination.

RESULT

Increasing cHRC score was associated with an increased risk of CP (odds ratio per 1 standard deviation increase in cHRC: 2.6, 95% confidence limits: 1.42, 5.1) and delayed early cognitive development [odds ratio: 2.3 (1.3; 4.3)]. These associations remain statistically significant when adjusted for major cranial ultrasound abnormality. There was an association of increasing cHRC and delayed psychomotor development, which did not reach statistical significance [odds ratio: 1.7 (1.0, 3.0)].

CONCLUSION

Among VLBW infants, the cumulative frequency of abnormal HRCs, which can be assessed non-invasively in the neonatal intensive care unit, is associated with an increased risk of adverse neurodevelopmental outcome.

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.

Characterization of RAGE, HMGB1, and S100beta in inflammation-induced preterm birth and fetal tissue injury

Immune activation represents an adaptive reaction triggered by both noxious exogenous (microbes) and endogenous [high mobility group box-1 protein (HMGB1), S100 calcium binding proteins] inducers of inflammation. Cell stress or necrosis lead the release of HMGB1 and S100 proteins in the extracellular compartment where they act as damage-associated molecular pattern molecules (or alarmins) by engaging the receptor for advanced glycation end-products (RAGE). Although the biology of RAGE is dictated by the accumulation of damage-associated molecular pattern molecules at sites of tissue injury, the role of RAGE in mediating antenatal fetal injury remains unknown. First, we studied the relationships at birth between the intensity of human fetal inflammation and sRAGE (an endogenous RAGE antagonist), HMGB1, and S100beta protein. We found significantly lower sRAGE in human fetuses that mounted robust inflammatory responses. HMGB1 levels correlated significantly with levels of interleukin-6 and S100beta in fetal circulation. We then evaluated the levels and areas of tissue expression of RAGE, HMGB1, and S100beta in specific organs of mouse fetuses on E16. Using an animal model of endotoxin-induced fetal damage and preterm birth, we determined that inflammation induces a significant change in expression of RAGE and HMGB1, but not S100beta, at sites of tissue damage. Our findings indicate that RAGE and HMGB1 may be important mediators of cellular injury in fetuses delivered in the setting of inflammation-induced preterm birth.

A novel mouse model of Ureaplasma-induced perinatal inflammation: effects on lung and brain injury

Chorioamnionitis is associated with increased lung and brain injury in premature infants. Ureaplasma is the microorganisms most frequently associated with preterm birth. Whether Ureaplasma-induced antenatal inflammation worsens lung and brain injury is unknown. We developed a mouse model combining antenatal Ureaplasma infection and postnatal oxygen exposure. Intraamniotic Ureaplasma Parvum (UP) increased proinflammatory cytokines in placenta and fetal lungs. Antenatal exposure to UP or broth caused mild postnatal inflammation and worsened oxygen-induced lung injury. Antenatal UP exposure induced central microgliosis and disrupted brain development as detected by decreased number of calbindin-positive and calretinin-positive neurons in the neocortex. Postnatal oxygen decreased calretinin-positive neurons in the neocortex but combined with antenatal UP exposure did not worsen brain injury. Antenatal inflammation exacerbates the deleterious effects of oxygen on lung development, but the broth effects prohibit concluding that UP by itself is a compounding risk factor for bronchopulmonary dysplasia. In contrast, antenatal UP-induced inflammation alone is sufficient to disturb brain development. This model may be helpful in exploring the pathophysiology of perinatal lung and brain injury to develop new protective strategies.

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.

Animal models of perinatal hypoxic-ischemic brain damage

Animal models are often presumably the first step in determining mechanisms underlying disease, and the approach and effectiveness of therapeutic interventions. Perinatal brain damage, however, evolves over months of gestation, during the rapid maturation of the fetal and newborn brain. Despite marked advances in our understanding of these processes and technologic advances providing an improved window on the timing and duration of injury, neonatal brain injury remains a "moving target" regarding our ability to "mimic" its processes in an animal model. Moreover, interfering with normal processes of development as part of a therapeutic intervention may do "more harm than good." Hence, controversy continues over which animal model can reflect human disease states. Numerous models have provided information regarding the pathophysiology of brain damage in term and preterm infants. Our challenges consist of identifying infants at greatest risk for permanent injury, identifying the timing of injury, and adapting therapies that provide more benefit than harm. A combination of appropriately suitable animal models to conduct these studies will bring us closer to understanding human perinatal damage and the means to treat it.

Tumor necrosis factor receptor-1 is essential for LPS-induced sensitization and tolerance to oxygen-glucose deprivation in murine neonatal organotypic hippocampal slices

Inflammation and ischemia have a synergistic damaging effect in the immature brain. The role of tumor necrosis factor (TNF) receptors 1 and 2 in lipopolysaccharide (LPS)-induced sensitization and tolerance to oxygen-glucose deprivation (OGD) was evaluated in neonatal murine hippocampal organotypic slices. Hippocampal slices from balb/c, C57BL/6 TNFR1(-/-), TNFR2(-/-), and wild-type (WT) mice obtained at P6 were grown in vitro for 9 days. Preexposure to LPS immediately before OGD increased propidium iodide-determined cell death in regions CA1, CA3, and dentate gyrus from 4 up to 48 h after OGD (P<0.001). Extending the time interval between LPS exposure and OGD to 72 h resulted in tolerance, that is reduced neuronal cell death after OGD (P<0.05). Slices from TNFR1(-/-) mice showed neither LPS-induced sensitization nor LPS-induced tolerance to OGD, whereas both effects were present in slices from TNFR2(-/-) and WT mice. Cytokine secretion (TNFalpha and interleukin-6) during LPS exposure was decreased in TNFR1(-/-) slices and increased in TNFR2(-/-) as compared with WT slices. We conclude that LPS induces sensitization or tolerance to OGD depending on the time interval between exposure to LPS and OGD in murine hippocampal slice cultures. Both paradigms are dependent on signaling through TNFR1.

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.

Interleukin-1 and ischemic brain injury in the newborn: development of a small molecule inhibitor of IL-1 receptor

Inflammation participates in the genesis and progression of hypoxic-ischemic brain injury. Interleukin (IL)-1 is a major pro-inflammatory cytokine, which plays a dominant role in hypoxic-ischemic (and postinfectious) brain damage. Abundant evidence reveals the principal involvement of IL-1 over other pro-inflammatory cytokines. IL-1 interacts with the IL-1 receptor I (IL-1RI). The natural IL-1 receptor antagonist (IL-1ra) is a large 17.5-kDa peptide that competes with IL-1 for its binding site on IL-1RI. Recombinant IL-1ra (Kineret) is effective in human inflammatory conditions. However, a number of drawbacks of IL-1ra limit its broader use; these include injection site reactions [70%], broad immunosuppression, and high costs. We hereby report the characterization of a small (peptide) IL-1RI antagonist we developed, namely rytvela (termed 101.10), and its efficacy in models of (gut) inflammation and of newborn hypoxic-ischemic brain injury. Experiments reveal that 101.10 is selective for the IL-1RI and inhibits to a variable extent different effects induced by IL-1. 101.10 is effective in vivo (on systemic as well as oral administration) in established models of inflammation involving IL-1, notably in inflammatory bowel disease, and is superior to dexamethasone. In a rat pup model of hypoxic-ischemic brain injury (Rice-Vannucci model), where IL-1 and IL-1R expression is increased, 101.10 preserved microvascular density, parenchymal integrity, and brain mass. In conclusion, we hereby describe for the first time the discovery of a stable, potent, and effective specific IL-1RI small (peptide) antagonist, namely 101.10 (rytvela), which exhibits allosteric modulatory properties, and is effective in vivo in models of inflammation (known to involve IL-1) and in particular in hypoxic-ischemic newborn brain injury. 101.10 (and small alike compounds) may be suitable alternatives to IL-1ra.

Inflammation in pregnancy: its roles in reproductive physiology, obstetrical complications, and fetal injury

Fetal development and growth occur in a sterile amniotic cavity while first exposure to microorganisms happens at birth. However, at least 25% of all preterm births, the leading cause of perinatal morbidity and mortality worldwide, occur in mothers with microbial invasion of the amniotic cavity. Microbial attack of the fetus takes place in approximately 10% of pregnancies with intra-amniotic infection, and the human fetus is capable of deploying an inflammatory response (cellular and humoral) in the mid-trimester of pregnancy. The onset of premature labor in the context of infection is mediated by pro-inflammatory cytokines, such as interleukin (IL)-1beta and tumor necrosis factor alpha (TNF-alpha), as these cytokines are produced by intrauterine tissues in response to microbial products, can stimulate prostaglandin production, and induce labor in animals. Moreover, knockout experiments suggest that infection is less likely to lead to premature labor when the IL-1 and TNF signaling pathways are disrupted. A fetal inflammatory systemic response occurs in a fraction of fetuses exposed to microorganisms in utero, and is associated with the impending onset of labor as well as multisystem organ involvement. Neonates born with funisitis, the histologic marker of such inflammation, are at increased risk for neurologic handicap and cerebral palsy. Evidence has begun to accumulate that gene-environment interactions determine the likelihood of preterm labor and delivery and, probably, the risk of fetal injury. Fetal inflammation has emerged as a major mechanism of disease responsible for complications in the perinatal period (in utero and in the first 28 days of life), as well as in infancy. Moreover, reprogramming of the fetal immune response may predispose to diseases in adulthood.

Modulation of peroxisome proliferator-activated receptor-alpha activity by N-acetyl cysteine attenuates inhibition of oligodendrocyte development in lipopolysaccharide stimulated mixed glial cultures

Glial cells secrete proinflammatory mediators in the brain in response to exogenous stimuli such as infection and injury. Previously, we documented that systemic maternal lipopolysaccharide (LPS)-exposure at embryonic gestation day 18 causes oligodendrocyte (OL)-injury/hypomyelination in the developing brain which can be attenuated by N-acetyl cysteine (NAC; precursor of glutathione). The present study delineates the underlying mechanism of NAC-mediated attenuation of inhibition of OL development in LPS-stimulated mixed glial cultures. Factors released by LPS-stimulated mixed glial cultures inhibited OL development as shown by decrease in both proliferation 3bromo-deoxyuridine+/chondroitin sulfate proteoglycan-NG2+, hereafter BrdU+/NG+ and differentiation (O4+ and myelin basic protein+) of OL-progenitors. Correspondingly, an impairment of peroxisomal proliferation was shown by a decrease in the level of peroxisomal proteins in the developing OLs following exposure to LPS-conditioned media (LCM). Both NAC and WY14643, a peroxisome proliferator-activated receptor (PPAR)-alpha agonist attenuated these LCM-induced effects in OL-progenitors. Similar to WY14643, NAC attenuated LCM-induced inhibition of PPAR-alpha activity in developing OLs. Studies conducted with cytokines and diamide (a thiol-depleting agent) confirmed that cytokines are active agents in LCM which may be responsible for inhibition of OL development via peroxisomal dysfunction and induction of oxidative stress. These findings were further corroborated by similar treatment of developing OLs generated from PPAR-alpha(-/-) and wild-type mice or B12 oligodendroglial cells co-transfected with PPAR-alpha small interfering RNAs/pTK-PPREx3-Luc plasmids. Collectively, these data provide evidence that the modulation of PPAR-alpha activity, thus peroxisomal function by NAC attenuates LPS-induced glial factors-mediated inhibition of OL development suggesting new therapeutic interventions to prevent the devastating effects of maternal infections.

Lipopolysaccharide-induced peroxisomal dysfunction exacerbates cerebral white matter injury: attenuation by N-acetyl cysteine

Cerebral white matter injury during prenatal maternal infection characterized as periventricular leukomalacia is the main substrate for cerebral palsy (CP) in premature infants. Previously, we reported that maternal LPS exposure causes oligodendrocyte (OL)-injury/hypomyelination in the developing brain which can be attenuated by an antioxidant agent, N-acetyl cysteine (NAC). Herein, we elucidated the role of peroxisomes in LPS-induced neuroinflammation and cerebral white matter injury. Peroxisomes are important for detoxification of reactive oxidative species (ROS) and metabolism of myelin-lipids in OLs. Maternal LPS exposure induced selective depletion of developing OLs in the fetal brain which was associated with ROS generation, glutathione depletion and peroxisomal dysfunction. Likewise, hypomyelination in the postnatal brain was associated with decrease in peroxisomes and OLs after maternal LPS exposure. Conversely, NAC abolished these LPS-induced effects in the developing brain. CP brains imitated these observed changes in peroxisomal/myelin proteins in the postnatal brain after maternal LPS exposure. In vitro studies revealed that pro-inflammatory cytokines cause OL-injury via peroxisomal dysfunction and ROS generation. NAC or WY14643 (peroxisome proliferators activated receptor (PPAR)-alpha agonist) reverses these effects of pro-inflammatory cytokines in the wild-type OLs, but not in PPAR-alpha(-/-) OLs. Similarly treated B12 oligodenroglial cells co-transfected with PPAR-alpha siRNAs/pTK-PPREx3-Luc, and LPS exposed PPAR-alpha(-/-) pregnant mice treated with NAC or WY14643 further suggested that PPAR-alpha activity mediates NAC-induced protective effects. Collectively, these data provide unprecedented evidence that LPS-induced peroxisomal dysfunction exacerbates cerebral white matter injury and its attenuation by NAC via a PPAR-alpha dependent mechanism expands therapeutic avenues for CP and related demyelinating diseases.

Current definitions of hypotension do not predict abnormal cranial ultrasound findings in preterm infants

OBJECTIVE

Hypotension is a commonly treated complication of prematurity, although definitions and management guidelines vary widely. Our goal was to examine the relationship between current definitions of hypotension and early abnormal cranial ultrasound findings.

METHODS

We prospectively measured mean arterial pressure in 84 infants who were < or = 30 weeks' gestational age and had umbilical arterial catheters in the first 3 days of life. Sequential 5-minute epochs of continuous mean arterial pressure recordings were assigned a mean value and a coefficient of variation. We applied to our data 3 definitions of hypotension in current clinical use and derived a hypotensive index for each definition. We examined the association between these definitions of hypotension and abnormal cranial ultrasound findings between days 5 and 10. In addition, we evaluated the effect of illness severity (Score for Neonatal Acute Physiology II) on cranial ultrasound findings.

RESULTS

Acquired lesions as shown on cranial ultrasound, present in 34 (40%) infants, were not predicted by any of the standard definitions of hypotension or by mean arterial pressure variability. With hypotension defined as mean arterial pressure < 10th percentile (< 33 mmHg) for our overall cohort, mean value for mean arterial pressure and hypotensive index predicted abnormal ultrasound findings but only in infants who were > or = 27 weeks' gestational age and those with lower illness severity scores.

CONCLUSIONS

Hypotension as diagnosed by currently applied thresholds for preterm infants is not associated with brain injury on early cranial ultrasounds. Blood pressure management directed at these population-based thresholds alone may not prevent brain injury in this vulnerable population.

The fetal inflammatory response syndrome

The fetal inflammatory response syndrome (FIRS) is a condition characterized by systemic inflammation and an elevation of fetal plasma interleukin-6. This syndrome has been observed in fetuses with preterm labor with intact membranes, preterm prelabor rupture of the membranes, and also fetal viral infections such as cytomegalovirus. FIRS is a risk factor for short-term perinatal morbidity and mortality after adjustment for gestational age at delivery and also for the development of long-term sequelae such as bronchopulmonary dysplasia and brain injury. Multiorgan involvement in FIRS has been demonstrated in the hematopoietic system, thymus, adrenal glands, skin, kidneys, heart, lung, and brain. This article reviews the fetal systemic inflammatory response as a mechanism of disease. Potential interventions to control an exaggerated inflammatory response in utero are also described.

Perinatal brain damage causation

The search for causes of perinatal brain damage needs a solid theoretical foundation. Current theory apparently does not offer a unanimously accepted view of what constitutes a cause, and how it can be identified. We discuss nine potential theoretical misconceptions: (1) too narrow a view of what is a cause (causal production vs. facilitation), (2) extrapolating from possibility to fact (potential vs. factual causation), (3) if X, then invariably Y (determinism vs. probabilism), (4) co-occurrence in individuals vs. association in populations, (5) one cause is all that is needed (single cause attribution vs. multicausal constellations), (6) drawing causal inferences from very small numbers of observations (the tendency to generalize), (7) unstated causal inferences, (8) ignoring heterogeneity, and (9) failing to consider alternative explanations for what is observed. We hope that our critical discussion will contribute to fruitful research and help reduce the burden of perinatal brain damage.

Antenatal infection/inflammation and fetal tissue injury

There is a clear association between antenatal infection/inflammation and preterm labour, with intrauterine infection complicating up to one third of preterm deliveries. In addition to this, there is now accumulating evidence that intrauterine infection and inflammation can lead to the development of a systemic inflammatory response in the fetus and subsequent tissue injury. The fetal inflammatory response is characterized by funisitis, high levels of pro-inflammatory cytokines in the amniotic fluid and cord blood, and systemic immune activation. This review discusses the evidence for this process and focuses on the clinical and experimental data supporting the hypothesis that these inflammatory processes contribute to brain and lung injury in the newborn.

ErbB receptors in fetal endothelium--a potential linkage point for inflammation-associated neonatal disorders

OBJECTIVE

ErbB receptors and their ligands play crucial roles in development. During late gestation, they might also be involved in the pathogenesis of prematurity-associated disorders. ErbB receptor dimerization leads to a diversity of biologic signals. We studied the expression and localization patterns of erbB receptors in the developing human umbilical endothelial cell system. It is still unclear, whether expression patterns might be developmentally regulated and depend on the cell type studied.

METHODS

Primary human umbilical venous endothelial cells (HUVEC) and arterial endothelial cells (HUAEC) were isolated between 24 and 42 weeks of gestation and used for immunoprecipitation, Western blotting, and confocal microscopy.

RESULTS

All four erbB receptors were present in HUVEC and HUAEC. Expression patterns were similar for cell types at gestational ages examined. ErbB4 always co-precipitated with erbB1 in both cell types independent of the gestational age. Confocal microscopy revealed that all erbB receptors were localized in the nucleus, erbB1 and erbB3 in the nucleoli, while erbB2 and erbB4 spared the nucleolar region. All receptors showed a tendency to co-localize. Growth factor stimulation altered localization patterns. Cellular subfractionation experiments for erbB4 largely confirmed microscopy results. Pretreatment with lipopolysaccharide enhanced this nuclear localization of erbB4, particularly of its intracellular domain.

CONCLUSIONS

All erbB receptors are present in both HUVEC and HUAEC at all gestational ages tested. ErbB receptor expression patterns were independent of the developmental stage of the endothelial cell, at least in the third trimester. We speculate that endothelial erbB receptors might play a role in normal development in mid and late gestation. We also speculate that these findings, together with the known involvement of erbB receptors in development, inflammation, and angiogenesis, will open new avenues for erbB receptor-related research in the pathogenesis of fetal and neonatal inflammation-associated disorders.

Low doses of ethanol and hypoxia administered together act synergistically to promote the death of cortical neurons

The majority of clinically relevant injuries to the developing brain are increasingly being recognized as the result of a combination of least two insults. Evidence from epidemiologic and clinical studies suggests that many of these insults do not cause injury in and of themselves. Rather, they act as predisposing factors (pre-conditioning cytotoxic factors, such as chronic ethanol consumption), increasing the susceptibility to a second, injury-producing (precipitating), unfavorable event (such as hypoxia-ischemia). In this study we make use of primary neuronal cultures to test, in a reproducible system, this two-hit hypothesis. We show that, when administered in combination, low levels of two clinically important environmental insults, hypoxia and ethanol, despite having minimal effects on their own, can act synergistically produce a significant degree of neuronal injury. We further show that one indicator of apoptotic cell death, activated caspase 3, undetectable in neurons subjected to low levels of either insult alone, is detectable when they are administered together.

Anti-inflammatory interventions in pregnancy: now and the future

A growing body of evidence implicates inflammatory pathways in adverse reproductive outcomes. This expanding evidence suggests that anti-inflammatory interventions may hold promise in reducing the maternal and neonatal morbidities and mortalities associated with these obstetrical complications. Preterm birth, preeclampsia, pregnancy loss and adverse neonatal outcomes have all been associated with the activation of inflammatory pathways during pregnancy. Because of the number of observational human studies, as well as animal models of preterm birth, the mechanisms by which inflammation may promote preterm parturition and adverse effects on the fetus are beginning to be elucidated. Although the future use of anti-inflammatory interventions in this context holds significant promise, much research is still warranted. Only when the pathogenesis of obstetrical complications is more fully understood can meaningful therapeutic interventions become a realistic goal.

Intestinal immune defences and the inflammatory response in necrotising enterocolitis

Necrotising enterocolitis is a devastating neonatal gastrointestinal emergency predominantly affecting low birth weight, premature infants and is accompanied by significant mortality and morbid sequelae. The pathophysiology remains obscure and the management of infants with necrotising enterocolitis has not changed since the recognition of this disease. Necrotising enterocolitis is most likely the clinical culmination of multiple different risk factors interacting with each other to produce bowel injury through a final, common inflammatory pathway. Here, we review intestinal immunity and the specific inflammatory mediators involved in this disease process.

Inflammation, brain damage and visual dysfunction in preterm infants

Antenatal intrauterine infection and the fetal inflammatory response appear to be important pathogenetic factors in preterm birth and subsequent neonatal disorders of the lung and brain. In this paper, we expand this concept to include visual dysfunction. Although present data tend to support our notion, we suggest that more experimental and epidemiological research is needed to elucidate mechanisms of infection/inflammation-induced damage to the eye and visual brain pathways of preterm infants.

The time of prenatal immune challenge determines the specificity of inflammation-mediated brain and behavioral pathology

Disturbance to early brain development is implicated in several neuropsychiatric disorders including autism, schizophrenia, and mental retardation. Epidemiological studies have indicated that the risk of developing these disorders is enhanced by prenatal maternal infection, presumably as a result of neurodevelopmental defects triggered by cytokine-related inflammatory events. Here, we demonstrate that the effects of maternal immune challenge between middle and late gestation periods in mice are dissociable in terms of fetal brain cytokine responses to maternal inflammation and the pathological consequences in brain and behavior. Specifically, the relative expression of pro- and anti-inflammatory cytokines in the fetal brains in response to maternal immune challenge may be an important determinant among other developmental factors for the precise pathological profile emerging in later life. Thus, the middle and late gestation periods correspond to two windows with differing vulnerability to adult behavioral dysfunction, brain neuropathology in early adolescence, and of the acute cytokine responses in the fetal brain.

Absence of pestivirus antigen in brains with white matter damage

We previously suggested that antenatal pestivirus infection might play a role in the pathogenesis of perinatal brain white matter damage (WMD) in preterm infants. We have now examined 22 brains from stillborns and deceased newborns (both preterm and term) for the presence of bovine virus diarrhoea virus (BVDV) antigen. The brains of five females and five males with WMD (median gestational age 36.5wks), and nine female and three male controls (median gestational age 36.5wks) were used in the study. No BVDV antigen was detected in any of the 22 brains. We conclude that brain infection with BVDV is unlikely to play a role in WMD pathogenesis among preterm or term newborns. Further research is needed to test the hypothesis that intrauterine exposure to pestivirus antigen elicits a fetal inflammatory response which then contributes to WMD.

Perinatal infections, prematurity and brain injury

PURPOSE OF REVIEW

The association between perinatal infection and brain injury is widely accepted but a cause-and-effect relationship has not yet been proven. This article summarizes available evidence and current primary publications for debate.

RECENT FINDINGS

Work completed during the review period has reinforced current understanding of perinatal infection, prematurity and brain injury. In animal experiments: lipopolysaccharides have been further implicated in brain injury, not only as a cause of brain injury but also as mediators of preconditioning and protection. Recent studies suggest that cerebral injury following low-dose lipopolysaccharide administration may become compensated in adulthood. Other studies have emphasized the complexity of the response by showing that plasma cytokine levels may not reflect those in the central nervous system or inflammatory events in the brain.

SUMMARY

Perinatal infection and maternofetal inflammation is strongly associated with preterm birth. Inflammation probably represents an important mechanism for cerebral damage, and both overt lesions and maldevelopment can result. Epidemiological data and multiple animal models to link infection, inflammation and brain damage exist, but proof of causation is elusive.

Maternal exposure to LPS induces hypomyelination in the internal capsule and programmed cell death in the deep gray matter in newborn rats

Epidemiologic and experimental findings implicate maternal infection in the etiology of injury to brain white matter, which may lead to cerebral palsy in preterm newborns. In the present study, inflammation and brain damage in 1- and 7-d-old rats were investigated after maternal inflammation. Intraperitoneal injection of 300 microg/kg of Escherichia coli lipopolysaccharide was administered to pregnant Wistar rats at d 19 and 20 of gestation (LPS group). Control females received a saline injection. Proinflammatory cytokines IL-1beta, tumor necrosis factor-alpha, and IL-6 expression in the fetal brain were determined by reverse transcription quantitative polymerase chain reaction. Brain injury was examined in 16-mum coronal brain sections by GFAP, MBP, caspase-3 immunohistochemistry, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling. Expression of IL-1beta was significantly increased 3 d after maternal administration (P1). A significant increase in cell death occurred at P1 and P7 in specific brain areas, i.e. in the subventricular striatal zone at P1, and in 1) the periventricular striatum, 2) the periventricular white matter, and 3) the germinative ventricular zone at P7. We also observed typical astrogliosis and strong hypomyelination in the external and internal capsule in the LPS group at P7. These results demonstrate that maternal LPS treatment induces persistent fetal inflammatory reactions associated with significant white matter injury in progeny at P1 and P7. This model should be relevant for the study of the pathophysiological mechanisms involved in cerebral white matter damage in preterm human newborns and in the development of therapeutic strategies.

White matter damage and chemokine induction in developing rat brain after intrauterine infection

In order to investigate the neuropathological effects on the developing rat brain after intrauterine infection, identification of glail fibrillary acidic protein (GFAP), 2', 3'-cyclic nucleotide phosphodiesterase (CNPase), and neurofilament (NF) 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, CNPase, and NF expression in pup brains at postnatal day 7 (P7) and reverse transcriptase-PCR (RT-PCR) to analyze macrophage inflammatory protein-1 alpha mRNA (MIP-1 alpha mRNA), macrophage inflammatory protein-1 beta mRNA (MIP-1beta mRNA), the regulated upon activation normal T expressed and secreted chemokine mRNA (RANTES mRNA) and Eotaxin mRNA expression in pup brains at P1, P3 and P7. The numbers of GFAP-positive cells of the E. coli-treated group pups were marked increased in periventricular white matter and hippocampus at P7 compared with the control group but no significant different levels of GFAP expression in corpus callosum were found between two groups. The integrate density (ID) of CNPase-positive staining of the Escherichia coli-treated group pups were marked decreased in periventricular white matter and corpus callosum at P7 compared with the control group. The ID of NF-positive staining of the Escherichia coli-treated group pups were marked decreased in periventricular white matter at P7 compared with the control group and no significant different levels of NF expression in corpus callosum were found between two groups. The expression of MIP-1 alpha mRNA and MIP-1 beta mRNA in brain of the E. coli-treated pup rat were higher than the control at P1, but the expression of MIP-1 alpha mRNA and MIP-1 beta mRNA in brain of the pup rat at P3 and P7 had no significant difference between two groups. The alteration of expression of GFAP, CNPase, and NF in the brain of neonatal rats after intrauterine infection suggested that intrauterine infection could cause neonatal white matter damage. Moreover, the transient increase in expression of chemokine such as MIP-1 alpha, MIP-1 beta in neonatal brain after intrauterine infection indicated that MIP-1 alpha, MIP-1 beta may be a mechanism mediating between the neonatal white matter damage and the intrauterine infection.

Evidence for the presence of N-formyl-methionyl-leucyl-phenylalanine (fMLP) receptor ligands in human amniotic fluid and fMLP receptor modulation by physiological labour

OBJECTIVES

The presence of amniotic binding sites for N-formyl-methionyl-leucyl-phenylalanine (fMLP), an inflammatory peptide, and its ability to induce prostaglandin E2 synthesis in the human amnion prompted us to investigate for: (1) the presence of fMLP receptor ligands (fMLPRL) in the amniotic fluid; (2) expression of the fMLP receptor in amniotic tissue; (3) the effect of amniotic fMLPRL on neutrophil cyclic AMP (cAMP) level and calcium concentration ([Ca2+]i) during physiological pregnancy and labour.

METHODS

Binding assays were performed on neutrophils to determine the presence of fMLRL in the amniotic fluid at the 17th week of pregnancy, as well as at term, before and after the onset of labour. The expression of fMLP receptor mRNA was evaluated by RT-PCR, the cAMP level by a radiochemical assay, and the calcium concentration by Fura-2 AM fluorescence measurement.

RESULTS

fMLPRLs were detectable in amniotic fluid throughout pregnancy, and their levels did not vary during gestation. Labour significantly increased both the amniotic fMLPRL level and the expression of fMLP receptor in amnion tissue. The increased amniotic fMLPRL concentration noted during labour significantly increased neutrophil cAMP level and [Ca2+]i.

CONCLUSIONS

These findings demonstrate for the first time the presence of fMLP receptor ligands in amniotic fluid, and indicate a modulation of the fMLP system by the events of physiological labour.

Transfer of Proinflammatory Cytokines Across Term Placenta

OBJECTIVE

Increased concentrations of proinflammatory cytokines in amniotic fluid indicate the presence of intra-amniotic inflammation and increase the risk of preterm birth, cerebral palsy, and bronchopulmonary dysplasia. The purpose of this study was to find out if the proinflammatory cytokines, tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-1beta, and IL-6, transfer across the placenta, and thereby determine whether intra-amniotic inflammatory response, measured from the amniotic fluid, is of maternal or fetal origin.

METHODS

Nineteen placentas from healthy women undergoing elective cesarean delivery at term with intact membranes and without labor, were dually perfused ex vivo in an open circulation system for either 30 minutes or 2 hours. Tumor necrosis factor-alpha, IL-1beta, and IL-6 were added to maternal or fetal circulation in a concentration usually found in chorioamnionitis. As a reference, placentas without added cytokine were also perfused. The concentrations of cytokines were determined by enzyme immunoassays (enzyme-linked immunosorbent assay [ELISA]).

RESULTS

After the addition of the cytokine to the arterial perfusate, the venous concentration on the same side of the placenta increased rapidly and reached a plateau at 10 minutes. No transfer of any cytokine in either direction was detected. Some endogenous release of IL-6 was observed in response to the perfusion.

CONCLUSION

Proinflammatory cytokines do not cross normal term placenta.

Maternal infection and adverse fetal and neonatal outcomes

Adverse pregnancy outcomes can follow direct placental, fetal, or neonatal infection, or preterm birth associated with vaginal, cervical, intrauterine, or even nonpelvic infections. These latter infections appear to be associated with the majority of very early preterm births, and may explain some of the long-term neurologic damage associated with preterm birth. Bacterial vaginosis and its associated intrauterine infections likely contribute far more to the overall burden of adverse pregnancy outcomes than the more classical perinatal infections such as rubella and syphilis.

Antenatal events causing neonatal brain injury in premature infants

Understanding possible causes of neonatal brain injury is important for perinatal nurses because neonatal brain injury predicts subsequent infant mortality and morbidity in the premature infant. The pathogenesis of the brain injury, germinal matrix/intraventricular hemorrhage and white matter damage, is usually related to a hypoxic event. The hypoxic event may occur in utero, resulting from various conditions, such as maternal infection, maternal alcohol consumption, maternal smoking, placental bleeding disorders, maternal hypercoagulability conditions, metabolic disorders (diabetes and hyperthyroidism), and oligohydramnios. Strategies for prevention beginning before and in pregnancy are needed.

Lipopolysaccharide induces both a primary and a secondary phase of sensitization in the developing rat brain

Data indicate that bacterial products in combination with other antenatal or postnatal exposures increase the risk of perinatal brain injury. We have previously shown that administration of lipopolysaccharide (LPS) 4 h before hypoxia-ischemia (HI) increases brain injury in 7-d-old rats. The mechanisms behind such sensitization are unclear, but contrasts against a preconditioning effect of LPS given 1-3 d before ischemia in adult animals. To investigate how the effects of LPS depend on the time interval between administration and HI in the developing brain, we evaluated the effect of varying time interval (2-72 h) between LPS and HI, the duration of HI (20 or 50 min), and age of the rat pups (postnatal d 4 or 7). Outcome was assessed by brain injury scoring of specific regions. We found that LPS reduced brain injury (by 78%) when administered 24 h before 50 min of HI. However, when LPS was administered 6 h before either 20 or 50 min of HI, brain injury was increased by 2026% and 137%, respectively. Even LPS given 72 h before HI increased injury, both when LPS was administered at postnatal d 4 (by 446%) and 7 (by 77%). In conclusion, LPS enhanced vulnerability in the developing brain both in the acute (4-6 h) and the chronic (72 h) phase after administration, whereas an intermediate interval between LPS and HI had the opposite effect. The long-term sensitizing effect of LPS has not been previously described.

Mechanisms of hypoxic-ischemic injury in the term infant

The pathogenesis of hypoxic-ischemic brain injury in the term infant is multifactorial and complex. Over the past decade the investigative emphasis has turned to cellular and molecular mechanisms of injury, and it has been increasingly recognized that the neonatal brain differs vastly from the adult brain in terms of response to hypoxia-ischemia. This review will discuss the initiation and evolution of brain injury in the term neonate, and the inherent biochemical and physiologic qualities of the neonatal brain that make its response to hypoxia-ischemia unique. Attention will be given to specific areas of investigation including excitotoxicity, oxidative stress, and inflammation. The coalescence of these entities to a final common pathway of hypoxic-ischemic brain injury will be emphasized.

Neonatal cerebral white matter injury in preterm infants is associated with culture positive infections and only rarely with metabolic acidosis

OBJECTIVE

Neonatal cerebral white matter injury represents a major precursor for neurological impairment and cerebral palsy. Our objective was to identify risk factors associated with its development.

STUDY DESIGN

This retrospective case-control study of all births between 23 and 34 weeks gestation at a single university hospital between May 1994 and September 2001 identified 150 cases with white matter injury characterized by periventricular leukomalacia or ventricular dilatation from white matter atrophy that were chromosomally normal and did not have other congenital anomalies. Cases were matched to controls without brain injury by the next delivery within 7 days of their gestational age.

RESULTS

There were small differences between controls and cases in gestational age (27.5 +/- 2.7, 27.4 +/- 2.6 weeks, P = .01) and birth weight (1053 +/- 402, 966 +/- 285 g, P = .002) that were statistically but not clinically significant. There was no difference in the percentage of controls and cases delivered by cesarean (45%, 49%, P = .64). There were no differences between controls and cases in umbilical arterial pH (7.27 +/- 0.11, 7.25 +/- 0.15, P = .19), base excess (-2.1 +/- 2.7, -3.0 +/- 4.1 mmol/L, P = .28), pH less than 7.0 (2/122 [2%], 3/107 [3%], P = 1.0), or base excess less than -12 mmol/L (4/121 [3%], 6/106 [6%], P = .75). The cases had a significant increase in positive blood (19%, 29%, P = .036), cerebrospinal fluid (6%, 17%, P = .002), and tracheal (9%, 22%, P = .003) cultures during the neonatal period. Conditional logistic regression showed a significant association among multiple gestations ( P = .02), intraventricular hemorrhage ( P < .001), and positive tracheal cultures ( P = .02) with cerebral white matter injury.

CONCLUSION

Culture-positive infection was associated with an increased risk of cerebral white matter injury in preterm neonates. Intrapartum hypoxia-ischemia as manifested by metabolic acidosis was rarely associated with white matter injury and was not different from the incidence in premature neonates without injury.

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.

Lung and Brain Damage in Preterm Newborns

The relationships among bronchopulmonary dysplasia (BPD), brain white matter damage (WMD) and cerebral palsy (CP) are far from simple. Apparently, BPD and WMD are not associated, while BPD and CP are. The most likely explanation for this paradox is that ultrasound imaging does not identify all the WMD that might lead to CP ('tip-of-the-iceberg effect'). We discuss further methodological inconsistencies, etiological peculiarities related to antenatal infection/inflammation, and intervention-related issues. In particular, we expand on the multiple-hit scenario in the etiology of BPD and offer support for the hypothesis that it is not lung disease, but factors associated with lung disease (e.g. postnatal steroid exposure) that increase the risk for developmental disability in childhood.

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.

Cerebral palsy

Cerebral palsy, a range of non-progressive syndromes of posture and motor impairment, is a common cause of disability in childhood. The disorder results from various insults to different areas within the developing nervous system, which partly explains the variability of clinical findings. Management options include physiotherapy, occupational and speech therapy, orthotics, device-assisted modalities, pharmacological intervention, and orthopaedic and neurosurgical procedures. Since 1980, modification of spasticity by means of orally administered drugs, intramuscular chemodenervation agents (alcohol, phenol, botulinum toxin A), intrathecally administered drugs (baclofen), and surgery (neurectomy, rhizotomy) has become more frequent. Family-directed use of holistic approaches for their children with cerebral palsy includes the widespread adoption of complementary and alternative therapies; however, the prevalence of their use and the cost of these options are unknown. Traditional medical techniques (physiotherapy, bracing, and orthopaedic musculoskeletal surgery) remain the mainstay of treatment strategies at this time. This seminar addresses only the musculoskeletal issues associated with cerebral palsy and only indirectly discusses the cognitive, medical, and social issues associated with this diagnosis.

Maternal and obstetric risk factors for sudden infant death syndrome in the United States

OBJECTIVE

The objectives of this study were to 1). study the incidence of sudden infant death syndrome (SIDS) among singleton births in the United States and 2). identify maternal and obstetric risk factors for SIDS.

METHODS

A cohort of all live births in the United States from 1995 to 1998, formed the source population (n = 15627404). The data were obtained from the National Centers for Health Statistics Linked Births and Infant Deaths File. A nested case-control study was used to examine risk factors for SIDS. From this birth cohort, all SIDS deaths (n = 12404) were first identified (case group). From the remaining non-SIDS births, a 4-fold larger sample (n = 49616) was randomly selected as a control group.

RESULTS

The overall incidence of SIDS was 81.7 per 100000 live births. More mothers in the case group than in the control group were reported to have placenta previa (odds ratio [OR]: 1.70; 95% confidence interval [CI] 1.24, 2.33), abruptio placentae (OR 1.57; 95% CI 1.24, 1.98), premature rupture of membranes (OR 1.48; 95% CI 1.33, 1.66), or small for gestational age (OR 1.40; 95% CI 1.30, 1.50 for the 10th percentile). SIDS cases were also more likely to be male. Mothers of cases were more likely to be younger, less educated, and nonwhite, and more of them smoked during pregnancy and did not attend prenatal care.

CONCLUSION

This analysis confirms the importance of several well known demographic and lifestyle risk factors for SIDS. In addition, placental abnormalities were risk factors for SIDS.

LEVEL OF EVIDENCE

II-2