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

Gene-environment interaction and covariation in schizophrenia: the role of obstetric complications

While genetic factors account for a significant proportion of liability to schizophrenia, a body of evidence attests to a significant environmental contribution. Understanding the mechanisms through which genetic and environmental factors coalesce in influencing schizophrenia is critical for elucidating the pathways underlying psychotic illness and for developing primary prevention strategies. Although obstetric complications (OCs) remain among the most well-documented environmental indicators of risk for schizophrenia, the pathogenic role they play in the etiology of schizophrenia continues to remain poorly understood. A question of major importance is do these factors result from a genetic diathesis to schizophrenia (as in gene-environment covariation), act additively or interactively with predisposing genes for the disorder in influencing disease risk, or independently cause disease onset? In this review, we evaluate 3 classes of OCs commonly related to schizophrenia including hypoxia-associated OCs, maternal infection during pregnancy, and maternal stress during pregnancy. In addition, we discuss several mechanisms by which OCs impact on genetically susceptible brain regions, increasing constitutional vulnerability to neuromaturational events and stressors later in life (ie, adolescence), which may in turn contribute to triggering psychosis.

A prediction score model for risk factors of mortality in neonate with pulmonary hemorrhage: the experience of single neonatal intensive care unit in Southwest China

AIM

To establish a prediction score model for mortality of neonates with pulmonary hemorrhage (PH).

METHODS

Mortality risk factors of PH were analyzed by logistic regression analysis in 244 neonates retrospectively. A prediction score model was developed according to regression coefficients of risk factors. The receiver operating characteristic curve (ROC) was also constructed and the cutoff was determined.

RESULTS

The overall mortality rate of PH was 74.59% (182/244). More patients from multiple pregnancies were found in the death group than in the survivor group (20.1% vs. 3.2%, P = 0.023). The survivor group infants had higher birth weight in average than death group infants (2,787 g vs. 2,339 g, P = 0.000). Significant differences were found between survivor and death groups in the rates of intraventricular hemorrhage (IVH) (25.8% vs. 53.8%, P = 0.000), heart failure (22.6% vs. 48.9%, P = 0.000) and sepsis (3.2% vs. 16.5%, P = 0.008). Birth weight, IVH, heart failure and sepsis were identified as independent mortality risk factors by logistic regression analysis. A score model predicting death was developed according to the regression coefficients, with a sensitivity of 0.846, a specificity of 0.661, a positive predictive value of 0.88 and a negative predictive value of 0.594 at a cutoff of 9 points. The low risk group, with a score of 9 or less, had a lower mortality rate as compared with the high risk group (40.6% vs. 88%, P = 0.000).

CONCLUSIONS

Low birth weight, IVH, heart failure and sepsis were the risk factors for mortality of PH. Those infants with a predictive score of more than 9 were at high risk for death.

Corticosteroids reverse cytokine-induced block of survival and differentiation of oligodendrocyte progenitor cells from rats

Background

Periventricular leukomalacia (PVL) is a frequent complication of preterm delivery. Proinflammatory cytokines, such as interferon-γ (IFN-γ) and tumor necrosis factor α (TNF-α) released from astrocytes and microglia activated by infection or ischemia have previously been shown to impair survival and maturation of oligodendrocyte progenitors and could thus be considered as potential factors contributing to the generation of this disease. The first goal of the present study was to investigate whether exposure of oligodendrocyte precursors to these cytokines arrests the maturation of ion currents in parallel to its effects on myelin proteins and morphological maturation. Secondly, in the search for agents, that can protect differentiating oligodendrocyte precursor cells from cytokine-induced damage we investigated effects of coapplications of corticosteroids with proinflammatory cytokines on the subsequent survival and differentiation of oligodendrocyte progenitor cells.

Methods

To exclude influences from factors released from other cell types purified cultures of oligodendrocyte precursors were exposed to cytokines and/or steroids and allowed to differentiate for further 6 days in culture. Changes in membrane surface were investigated with capacitance recordings and Scanning Ion Conductance Microscopy. Na⁺- and K⁺- currents were investigated using whole cell patch clamp recordings. The expression of myelin specific proteins was investigated using western blots and the precursor cells were identified using immunostaining with A2B5 antibodies.

Results

Surviving IFN-γ and TNF-α treated cells continued to maintain voltage-activated Na⁺- and K⁺ currents characteristic for the immature cells after 6 days in differentiation medium. Corticosterone, dihydrocorticosterone and, most prominently dexamethasone, counteracted the deleterious effects of IFN-γ and TNF-α on cell survival, A2B5-immunostaining and expression of myelin basic protein. The most potent corticosteroid tested, dexamethasone, was shown to counteract cytokine effects on membrane surface extension and capacitance. Furthermore, coapplication of dexamethasone blocked the cytokine-induced downregulation of the inwardly rectifying potassium current in 80% of the precursor cells and restored the cytokine-blocked down-regulation of the voltage activated Na⁺- and K⁺ currents during subsequent differentiation.

Conclusion

Our results show that treatment of oligodendrocyte precursors with the inflammatory cytokines TNF-α and IFN-γ block the differentiation of oligodendrocyte precursors at the level of the differentiation of the voltage-gated ion currents. Co-treatment with corticosteroids at the time of cytokine application restores to a considerable extent survival and differentiation of oligodendrocytes at the level of morphological, myelin protein as well as ion current maturation suggesting the option for a functional restoration of cytokine-damaged immature oligodendrocytes.

Histological inflammatory responses in the placenta and early neonatal brain injury

We investigated the relationship between the severity of histological inflammatory responses in the placenta, chorionic plate, and umbilical cord in conjunction with the intraventricular hemorrhage (IVH) risk in premature infants. Clinical data were prospectively collected for 287 consecutive premature neonates born before 32 completed weeks of gestation and admitted to the level III neonatal intensive care unit of the Department of Pediatrics at Padua University from January 1999 to December 2004. Placental histology for histological chorioamnionitis (HCA) was graded and scored according to Redline and others. The diagnosis of IVH (grades I-IV) was graded according to Volpe's classification. Among the placentas of the 287 preterm examined infants, 68 (23.6%) were diagnosed with acute HCA. Overall incidence of IVH was 11.8%. Of 68 preterm neonates with HCA, 11 developed IVH (16.1%). Maternal HCA at the higher grades and stages increased the risk of IVH: 7 (64%) of the 11 preterm infants with maternal HCA grade 3 developed IVH (RR; 95% CI 2.05; 1.1-3.6) and 8 (73%) of the 11 preterm neonates with stage 3 developed IVH (RR; 95% CI 1.59; 1.0-2.5). Conversely, fetal inflammation was not associated with an increased risk of IVH. In conclusion, the IVH risk in preterm infants at less than 32 gestation weeks is significantly associated with severe grade and stage maternal HCA inflammatory scores.

Prenatal inflammatory effects on nigrostriatal development in organotypic cultures

Maternal intrauterine infection, and the accompanying inflammation in the fetal brain, represent a significant risk to the developing fetus. Dopamine (DA) neurons have been shown to be particularly vulnerable to inflammation induced by injection of the bacterial endotoxin lipopolysaccharide (LPS). In order to further examine the nature of this vulnerability, we used a combination of in vivo prenatal LPS exposure, and in vitro analysis of nigrostriatal development in organotypic cultures prepared from LPS-exposed rat fetuses. Control co-cultures prepared from unexposed E14 substantia nigra (SN/VTA) and E21 striatum exhibited numerous DA neurons in the nigral piece and robust ingrowth into the striatal piece. When E14 SN/VTA was obtained from fetuses exposed to LPS (0.1 mg/kg) on E10, initial DA cell numbers and striatal innervation in co-cultures were normal, but at longer durations in vitro, a reduction in DA neurons was observed. When striatal tissue from fetuses exposed to LPS on E14 or E18 was used in combination with non-exposed SN/VTA, DA neurons initially exhibited a normal pattern of ingrowth into LPS-exposed striatum. However, with longer durations in vitro, DA neurons were lost more rapidly when co-cultured with LPS-exposed striatum. Despite the loss of DA neurons, striatal DA innervation was only reduced in cultures prepared with striatum exposed to LPS at E18, at the longest time period examined. Experiments in which unexposed SN/VTA was given the choice to grow toward control striatum or toward LPS-exposed striatum supported the idea that the tropic qualities of the striatum were not altered by LPS-induced inflammation. Thus, the inflammation induced by LPS not only affects the SN/VTA DA neurons, but also alters the neurotrophic--although not the neurotropic--characteristics of the striatum. Such alterations in nigrostriatal development may demonstrate how adverse perinatal events predispose the developing brain toward the later development of Parkinson's disease.

Early amplitude-integrated EEG correlates with cord TNF-alpha and brain injury in very preterm infants

AIM

To investigate if the early electroencephalogram (EEG) and amplitude-integrated EEG (aEEG) in very preterm infants is affected by perinatal inflammation and brain injury, and correlates with long-term outcome.

METHODS

Sixteen infants born at 24-28 gestational weeks (median 25.5) had continuous EEG/aEEG during the first 72 h of life. Minimum and maximum EEG interburst intervals (IBI), and aEEG amplitudes were semi-automatically quantified and averaged over the recording period. Neonatal brain injury was diagnosed with repeated cranial ultrasound investigations. Nine cytokines from four time-points were analyzed during the first 72 h (umbilical cord blood, 6, 24 and 72 h), and outcome was assessed at 2 years of corrected age.

RESULTS

Infants with neonatal brain injury (n=9) had prolonged IBI, 11.8 (9.6-23.2) sec versus 8.2 (7.1-11.6) sec in infants (n=7) without brain damage (p=0.005). Handicap at 2 years (n=8, including two infants without neonatally diagnosed brain injury) was associated with prolonged neonatal IBI and lower aEEG amplitudes. Also aEEG amplitudes were decreased in infants with neonatal brain injury. There was a significant positive correlation between the averaged IBI and cord blood TNF-alpha (rs=0.595, p=0.025).

CONCLUSION

Early EEG depression is associated with increased cord blood TNF-alpha, neonatal brain damage and handicap at 2 years.

Infection and fetal neurologic injury

PURPOSE OF REVIEW

Antepartum fetal exposure to infection/inflammation is a more important risk factor for brain injury than intrapartum hypoxia in both the term and preterm neonate. Such preexisting infection/inflammation might also provide the platform for subsequent intrapartum hypoxic-ischaemic damage. This review will discuss the complex interaction between fetal inflammatory response and neurotoxicity, and focus on the clinical implications of the synergistic interaction between infection/inflammation and hypoxia-ischaemia.

RECENT FINDINGS

Current evidence indicates that inflammatory mediators are directly neurotoxic, and also sensitize the fetal brain tissue to a greater magnitude of damage by subsequent hypoxia-ischaemia by lowering the threshold at which hypoxia initiates neuronal cell apoptosis/cell death.

SUMMARY

Further studies are urgently needed to characterize the fetuses at risk of damage, the duration of exposure required to cause injury, the influence of gestational age and whether Caesarean section may be protective. Until then clinicians should maintain a high level of surveillance in labours complicated by infection and avoid additional exposure to hypoxic-ischaemic insults.

Tumor necrosis factor alpha mediates lipopolysaccharide-induced microglial toxicity to developing oligodendrocytes when astrocytes are present

Reactive microglia and astrocytes are present in lesions of white matter disorders, such as periventricular leukomalacia and multiple sclerosis. However, it is not clear whether they are actively involved in the pathogenesis of these disorders. Previous studies demonstrated that microglia, but not astrocytes, are required for lipopolysaccharide (LPS)-induced selective killing of developing oligodendrocytes (preOLs) and that the toxicity is mediated by microglia-derived peroxynitrite. Here we report that, when astrocytes are present, the LPS-induced, microglia-dependent toxicity to preOLs is no longer mediated by peroxynitrite but instead by a mechanism dependent on tumor necrosis factor-alpha (TNFalpha) signaling. Blocking peroxynitrite formation with nitric oxide synthase (NOS) inhibitors or a decomposition catalyst did not prevent LPS-induced loss of preOLs in mixed glial cultures. PreOLs were highly vulnerable to peroxynitrite; however, the presence of astrocytes prevented the toxicity. Whereas LPS failed to kill preOLs in cocultures of microglia and preOLs deficient in inducible NOS (iNOS) or gp91(phox), the catalytic subunit of the superoxide-generating NADPH oxidase, LPS caused a similar degree of preOL death in mixed glial cultures of wild-type, iNOS-/-, and gp91(phox-/-) mice. TNFalpha neutralizing antibody inhibited LPS toxicity, and addition of TNFalpha induced selective preOL injury in mixed glial cultures. Furthermore, disrupting the genes encoding TNFalpha or its receptors TNFR1/2 completely abolished the deleterious effect of LPS. Our results reveal that TNFalpha signaling, rather than peroxynitrite, is essential in LPS-triggered preOL death in an environment containing all major glial cell types and underscore the importance of intercellular communication in determining the mechanism underlying inflammatory preOL death.

Maturation-dependent sensitivity of oligodendrocyte lineage cells to apoptosis: implications for normal development and disease

Apoptosis plays a crucial role in brain development by ensuring that only appropriately growing, migrating, and synapse-forming neurons and their associated glial cells survive. This process involves an intimate relationship between cell-cell interactions and developmental cues and is further impacted by environmental stress during neurogenesis and disease. Oligodendrocytes (OLs), the major myelin-forming cells in the central nervous system, largely form after this wave of neurogenesis but also show a selective vulnerability to cell death stimuli depending on their stage of development. This can affect not only embryonic and early postnatal brain formation but also the response to demyelinating pathologies. In the present review, we discuss the stage-specific sensitivity of OL lineage cells to damage-induced death and how this might impact myelin survival and regeneration during injury or disease.

Prenatal exposure to maternal infections and epilepsy in childhood: a population-based cohort study

OBJECTIVE

We estimated the association between prenatal exposure to maternal infections and the subsequent risk for epilepsy in childhood.

METHODS

We included 90,619 singletons who were born between September 1997 and June 2003 in the Danish National Birth Cohort and followed them up to December 2005. Information on maternal infections during pregnancy (cystitis, pyelonephritis, diarrhea, coughs lasting >1 week, vaginal yeast infection, genital herpes, venereal warts, and herpes labialis) was prospectively reported by mothers in 2 computer-assisted telephone interviews in early and midgestation; information on maternal cystitis and pyelonephritis during late period of pregnancy was also collected in a third interview after birth. Children who received a diagnosis of epilepsy as inpatients or outpatients were retrieved from the Danish National Hospital Register. We identified 646 children with a diagnosis of epilepsy during up to 8 years of follow-up time. Cox proportional hazards regression models were used to estimate incidence rate ratio and 95% confidence interval.

RESULTS

Children who were exposed to maternal cystitis, pyelonephritis, diarrhea, coughs, and/or vaginal yeast infection some maternal infections in prenatal life had an increased risk for epilepsy. Coughs lasting >1 week were associated with an increased risk for epilepsy only in the first year of life, as was vaginal yeast infection only in children who were born preterm. These associations remained unchanged for children without cerebral palsy, congenital malformation, or a low Apgar score at 5 minutes.

CONCLUSIONS

Prenatal exposure to some maternal infections was associated with an increased risk for epilepsy in childhood.

MRC ORACLE Children Study. Long term outcomes following prescription of antibiotics to pregnant women with either spontaneous preterm labour or preterm rupture of the membranes

Background

The Medical Research Council (MRC) ORACLE trial evaluated the use of co-amoxiclav 375 mg and/or erythromycin 250 mg in women presenting with preterm rupture of membranes (PROM) ORACLE I or in spontaneous preterm labour (SPL) ORACLE II using a factorial design. The results showed that for women with a singleton baby with PROM the prescription of erythromycin is associated with improvements in short term neonatal outcomes, although co-amoxiclav is associated with prolongation of pregnancy, a significantly higher rate of neonatal necrotising enterocolitis was found in these babies. Prescription of erythromycin is now established practice for women with PROM. For women with SPL antibiotics demonstrated no improvements in short term neonatal outcomes and are not recommended treatment. There is evidence that both these conditions are associated with subclinical infection so perinatal antibiotic administration may reduce the risk of later disabilities, including cerebral palsy, although the risk may be increased through exposure to inflammatory cytokines, so assessment of longer term functional and educational outcomes is appropriate.

Methods

The MRC ORACLE Children's Study will follow up UK children at age 7 years born to 4809 women with PROM and the 4266 women with SPL enrolled in the earlier ORACLE trials. We will use a parental questionnaire including validated tools to assess disability and behaviour. We will collect the frequency of specific medical conditions: cerebral palsy, epilepsy, respiratory illness including asthma, diabetes, admission to hospital in last year and other diseases, as reported by parents.

National standard test results will be collected to assess educational attainment at Key Stage 1 for children in England.

Discussion

This study is designed to investigate whether or not peripartum antibiotics improve health and disability for children at 7 years of age.

Trial registration

The ORACLE Trial and Children Study is registered in the Current Controlled Trials registry. ISCRTN 52995660

Agomelatine, a melatonin receptor agonist with 5-HT(2C) receptor antagonist properties, protects the developing murine white matter against excitotoxicity

Periventricular leukomalacia is a major cause of cerebral palsy. Perinatal white matter lesions associated with cerebral palsy appears to involve glutamate excitotoxicity. When injected intracerebrally into newborn mice, the glutamatergic analog, ibotenate, induces white matter cysts mimicking human periventricular leukomalacia. Intraperitoneal injection of melatonin was previously shown to be neuroprotective in this mouse model. The goal of the present study was to compare in this model the protective effects of agomelatine (S 20098), a melatonin derivative, with melatonin. Mice that received intraperitoneal S 20098 or melatonin had significant reductions in size of ibotenate-induced white matter cysts when compared with controls. Although agomelatine and melatonin did not prevent the initial appearance of white matter lesions, they did promote secondary lesion repair. Interestingly, while melatonin effects were only observed when given within the first two hours following the excitotoxic insult, agomelatine was still significantly neuroprotective when administered eight hours after the insult. The protective effects of agomelatine and melatonin were counter-acted by co-administration of luzindole or S 20928, two melatonin receptor antagonists. Agomelatine, acting through melatonin receptors, could represent a promising new drug for treating human periventricular leukomalacia and have beneficial effects on neuroplasticity.

Using proteomic analysis of the human amniotic fluid to identify histologic chorioamnionitis

OBJECTIVE

To estimate the relationship between histologic chorioamnionitis and four amniotic fluid proteomic biomarkers characteristic of inflammation (defensins 2 and 1, calgranulins C and A).

METHODS

One hundred fifty-eight women with singleton pregnancies had a clinically indicated amniocentesis to rule out inflammation and infection in the context of preterm labor or preterm premature rupture of membranes. A proteomic fingerprint (Mass Restricted score) was generated from amniotic fluid using surface-enhanced laser desorption ionization time-of-flight mass spectrometry. The Mass Restricted score ranges from 0 to 4 (none to all four biomarkers present) in direct relationship with severity of intra-amniotic inflammation. Presence or absence of biomarkers was analyzed in relationship to placental pathology. Criteria for severity of histologic chorioamnionitis were 3 stages and 4 grades of inflammation of the amnion, choriodecidua and chorionic plate.

RESULTS

The prevalence of histologic chorioamnionitis was 64% (stage I 12%, stage II 16%, and stage III 37%). The Mass Restricted score significantly correlated with stages of histologic chorioamnionitis (r=0.539, P<.001), grades of choriodeciduitis (r=0.465, P<.001), and amnionitis (r=0.536, P<.001). African-American women were overrepresented in the group with severe inflammation (Mass Restricted score 3-4, P=.022). Of the four biomarkers of the Mass Restricted score, calgranulin C had the strongest relationship with presence of stage III chorioamnionitis, independent of race, amniocentesis-to-delivery interval, and gestational age.

CONCLUSION

Proteomic analysis of amniotic fluid provides an opportunity for early recognition of histologic chorioamnionitis. This methodology may in the future identify candidates for antenatal therapeutic interventions.

LEVEL OF EVIDENCE

II.

Cerebral palsy

Extreme prematurity confers about a 100-fold increase in the risk of cerebral palsy (CP), relative to birth at term gestation. Although CP is primarily a disorder of movement, many children with this disorder have other impairments which may affect their quality of life and life expectancy. Epidemiologic and clinical studies of cerebral palsy have benefited from recent efforts to develop greater uniformity of definition and classification. Particularly noteworthy is the development of the Gross Motor Function Classification System, which is a reliable and valid measure used with increasing frequency in observational and experimental studies. Also of great importance are efforts to quantify reliably the quality of life for children with cerebral palsy, thereby providing a target for medical and community interventions that aim to increase participation and well-being among affected children. During the late 1970s and early 1980s, the rate of CP actually rose, presumably as a result of increased survival of especially vulnerable infants who otherwise would have died. In developed countries over the past two decades (late 1980s to present), CP rates have been either stable or decreasing. Although considerable effort is being directed at prevention, the only perinatal interventions for which there is strong evidence of a beneficial effect on both mortality and the risk of CP is antenatal treatment of the mother with glucocorticoid.

C-Reactive Protein, Detected with a Highly Sensitive Assay, in Non-Infected Newborns and Those with Early Onset Infection

SUMMARY: BACKGOUND: The aim of this study was to investigate C-reactive protein (CRP), measured by a highly sensitive method (hsCRP) in non-infected newborns and in those with suspected early onset bacterial infection (EOBI) as well as to test whether EOBI would be detectable earlier by hsCRP than by a nephelometric CRP (nsCRP) assay (thresholds > 10 mg/l) or IL-8. PATIENTS AND METHODS: 106 neonates with signs of infection comprised the suspected EOBI group. 134 neonates with risk factors but confirmed exclusion of EOBI served as non-infected controls. RESULTS: In the non-infected group, hsCRP in the first 6 h after birth was low (0.7 mg/l; SD 0.16 mg/l) but showed an increase to 4.11 mg/l (SD 3.33 mg/l) at 72 h (p < 0.001 vs. 6 h). The sensitivity of hsCRP (cut-off 0.3 mg/l) vs. nsCRP for EOBI was 0.46 vs. 0.23 at 6 h after clinical suspicion. Of all parameters measured, IL-8 had the highest sensitivity and specificity to detect EOBI at 6 h (0.60 and 0.90), but declined after 12 and 24 h. CONCLUSION: Lowering the CRP detection threshold by a highly sensitive assay did not improve diagnostic accuracy for EOBI.

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.

Neuroprotective role of minocycline in co-cultures of human fetal neurons and microglia

Bacterial infections during pregnancy often result in premature birth and neonatal white matter damage. During these infections, microglia, the resident immune cells of the CNS, undergo activation and contribute to further neuronal damage of the CNS. Minocycline, a second-generation tetracycline antibiotic, inhibits microglial activation and protects neurons in rodents but data about its effects on human cells are limited. We studied the mechanism of the neuroprotective effect of minocycline in either purified cell cultures or co-cultures of microglia and neurons from human fetal brain during inflammation induced by lipopolysaccharide (LPS). In neuron/microglial co-cultures, minocycline treatment prevented activation and proliferation of microglia and protected neurons as demonstrated by decreased neuronal cell death and a shift of Bcl-2 family proteins toward anti-apoptotic ratio. Notably, neither minocycline nor LPS had an effect on neurons in purified neuronal cultures. The ability of minocycline to regulate activation of human fetal microglia might be relevant in therapies used towards treating neonatal CNS infections.

Bronchopulmonary dysplasia predicts adverse developmental and clinical outcomes in very-low-birthweight infants

This study examined the developmental and clinical outcomes in very-low-birthweight (VLBW; < or =1500g) infants with and without bronchopulmonary dysplasia (BPD) throughout infancy, and assessed if BPD predicted poor developmental outcome beyond the effects of other risk factors. One hundred and three VLBW infants (53 males, 50 females; mean gestational age 28wks [SD 2] birthweight 1041g [SD 261]) were graded for severity of BPD according to the American National Institutes of Health (NIH) consensus definition. Neuro-development was assessed using the Neonatal Neurobehavioral Examination-Chinese version, at 36 and 39 weeks' postmenstrual age, and the 2nd edition of the Bayley Scales of Infant Development at 6 and 12 months' corrected age. Clinical outcome was measured by means of rehospitalization for pulmonary causes and treatment with pulmonary medications. Compared with infants without BPD, infants with BPD had higher rates of clinical morbidity, and those with severe BPD further exhibited higher incidences of developmental delay throughout infancy. BPD predicts poor 1-year developmental and clinical outcomes in VLBW infants for which effects are well correlated to the NIH consensus definition.

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.

Relationship between serum lactate level and periventricular leukomalacia

In a case control study, we evaluated the serum lactate levels during the early days of life in preterm infants with periventricular leukomalacia (PVL), who were presumed to have suffered injury around birth. Thirteen infants diagnosed by ultrasonography as suffering from cystic PVL during the neonatal period and 26 normally developed infants matched by gestational age were enrolled in the study. The serum lactate level was measured repeatedly during the 72 h after birth. The mean serum lactate levels on admission were 2.95+/-0.43 and 3.21+/-0.29 mmol/L in the PVL and control groups, respectively. There was no statistically significant difference in the serum lactate level between the groups at any point during the first 72 h after birth. In conclusion, the serum lactate level was not elevated in preterm infants with PVL suggesting that the serum lactate level is not a useful predictor for the development of PVL in infants.

Neuroimaging of neonatal encephalopathies

Neonatal brain disorders consist of a wide chapter including brain malformations, hypoxic-ischemic encephalopathy (HIE), intracranial infections, perinatal trauma and metabolic encephalopathy. We will focus here on HIE, intracranial infections (especially materno-fetal infection with or without prolonged and/or premature rupture of membranes) and metabolic encephalopathy, those three conditions being the most frequent so far in our experience. Neonatal stroke is also analyzed. Moreover minor perinatal events might be superimposed on an already damaged (infective, edematous, metabolically abnormal or maldeveloped) brain, highlighting the main role and potential benefits of neuroimaging during the neonatal period. The different methods of brain imaging are thus reported with their advantages and disadvantages.

An adverse intrauterine environment: implications for injury and altered development of the brain

Abnormal development of the brain during fetal life is now thought to contribute to the aetiology of many functional and behavioural disorders that manifest throughout life. Many factors are likely to underlie such abnormal development including genetic makeup and an adverse intrauterine environment. This review will focus on prenatal hypoxic-ischemic injury and inflammatory/infective insults. A range of experimental models have been used to characterise lesions formed in response to these insults and to determine mechanisms of damage resulting from such events. Relatively brief periods of fetal hypoxia result in neuronal death (cerebellum, hippocampus, and cerebral cortex), white matter damage and reduced growth of neural processes. These effects are more profound at mid than late gestation. Chronic mild placental insufficiency can result in fetal growth restriction and deficits in neural connectivity and myelination. Exposure of the preterm fetus to inflammatory agents causes brain damage particularly in the white matter and this is exacerbated by hypoxia. These studies show that the timing, severity and nature of specific insults are critical in determining the pattern of injury and thus the extent to which neurological function will be affected postnatally. Defining the causes, patterns and mechanisms of brain injury is crucial if we are to develop rational neuroprotective strategies to reduce the burden of altered brain growth and poor functional and behavioural outcomes.

Chronic interleukin-6 alters the level of synaptic proteins in hippocampus in culture and in vivo

There is now considerable evidence that the level of expression of the proinflammatory cytokine, interleukin-6 (IL-6), is increased in the central nervous system (CNS) during neuroinflammatory conditions such as occurs in neurological disorders and in disease and injury. However, our understanding of the consequences of increased expression of IL-6 on the CNS is still limited, especially with respect to the developing nervous system, which is known to be particularly vulnerable to environmental factors. To address this issue, we investigated the properties of cultured hippocampal neurons exposed chronically to IL-6 during the main period of morphological and physiological development, which occurs during the first 2 weeks of culture. IL-6 was tested at 500 U/mL, considered to reflect a pathophysiologic concentration. The morphological features of neuronal development in the control and IL-6-treated cultures appeared similar. However, Western blot analysis showed a significant reduction in the level of Group-II metabotropic receptors (mGluR2/3) and L-type Ca(2+) channels in the IL-6-treated cultures. A similar reduction in mGluR2/3 and L-type Ca(2+) channel protein was observed in transgenic mice that over-express IL-6 in the CNS through astrocyte production starting early in development. Analysis of Ca(2+) signals produced by spontaneous synaptic network activity in the hippocampal cultures and effects of a mGluR2/3 agonist and antagonist showed that the reduced levels of mGluR2/3 impact on the functional properties of hippocampal synaptic network activity. These results have important implications relative to the mechanisms responsible for altered CNS function during conditions associated with increased levels of IL-6 in the CNS.

Reduced IL-10 production and -receptor expression in neonatal T lymphocytes

AIM

To further evaluate the underlying mechanism of a formerly demonstrated immature anti-inflammatory response in neonates (1).

METHODS

Interleukin (IL)-10 production was measured by enzyme-linked immunosorbent-assay (ELISA) after anti-CD3/anti-CD28 costimulation of neonatal and adult T cells. IL-10 receptor expression on T lymphocytes, B lymphocytes and monocytes were analysed by flow cytometry in neonates and adult controls.

RESULTS

After anti-CD3/anti-CD28 costimulation, IL-10 production of neonatal T lymphocytes was profoundly reduced (median 247 pg/mL vs. 1062 pg/mL, p < 0.0001). IL-10 receptor expression was diminished on neonatal T lymphocytes compared to adults (3% vs. 39.5% IL-10 receptor positive lymphocytes; p < 0.0001). On neonatal B lymphocytes and monocytes the IL-10 receptor expression was comparable to adult controls.

CONCLUSION

The strongly reduced IL-10 receptor expression on the main immune regulative T lymphocytes in conjunction with a significantly impaired synthesis of IL-10 may play a crucial role in the formerly demonstrated deficient anti-inflammatory immune response in neonates.

Dose-dependent lipopolysaccharide-induced fetal brain injury in the guinea pig

OBJECTIVE

This study determined whether a lipopolysaccharide (LPS) dose-dependent increase in fetal brain injury occurs to further characterize the relationship between maternal inflammation and fetal brain injury.

STUDY DESIGN

Pregnant guinea pigs (n = 59) at 70% gestation were injected intraperitoneally with 1, 5, 25, 50, 100, 200, or 300 microg LPS per kilogram of maternal body weight or an equivalent volume of vehicle. Animals were killed 7 days later. Maternal serum and amniotic fluid samples were assayed for proinflammatory cytokines tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6 using enzyme-linked immunosorbent assay kits. Fetal brains (n = 72) were stained for evidence of cell death with NeuroTACS stain.

RESULTS

Seven days after LPS injections, cytokine concentrations in maternal serum and amniotic fluid were not different (P > .05) from controls. Levels of cell death in all brain regions examined were highest following the maternal administration of 300 mug/kg LPS (P < .05). The dose effect was brain region-dependent (P < .05).

CONCLUSION

A threshold of maternal infection/inflammation exists, beyond which demonstrable fetal brain injury may result.

A device for adsorbing unbound, unconjugated bilirubin and its effects in vitro and in a hyperbilirubinemic newborn piglet

AIMS

A novel blood purification material that we previously reported as a superantigen- and cytokine-adsorbing device (SCAD) was evaluated for its ability to adsorb unbound, unconjugated bilirubin (UUBil) in vitro and in vivo.

METHODS

In albumin-containing buffer, UUBil was dissolved and circulated through the SCAD column. Also, bilirubin was infused into low-body weight newborn piglets and hemoperfused for 3 h over SCAD columns.

RESULTS

In albumin-containing buffer, concentration of bilirubin decreased from 34 to 0.6 mg/dL within 5 h and the SCAD fiber turned brown, indicating that bilirubin was adsorbed onto the surface of the adsorbent and was not degraded during the circulation. Using the hyperbilirubinemia swine, clearances of total bilirubin (TBil), direct bilirubin (DBil), and indirect bilirubin (IdBil) were significantly higher (P<0.01) in the SCAD group compared with the control group. The clearances of TBil, DBil, and IdBil at 3 h after the initiation of the bilirubin infusion were 0.47, 0.53, and 0.45 mL/min, respectively, at a blood flow rate of 2.5 mL/min, and this result indicates that almost 20% of bilirubins were adsorbed to the SCAD column in a single passage.

CONCLUSION

These results provide initial evidence that SCAD treatment is effective in the removal of UUBil and can be performed safely in newborn animals.

Intrauterine infection induced oligodendrocyte injury and inducible nitric oxide synthase expression in the developing rat brain

AIMS

In order to investigate the neuropathological effect on the developing rat brain after intrauterine infection, 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) and inducible nitric oxide synthase (iNOS) were evaluated.

METHODS

Escherichia coli (E. coli) was inoculated into the uterine cervix of the time-pregnant rats and controls were injected with normal saline. Immunohistochemical staining for CNPase was performed to assess oligodendrocyte injury in pup brains at postnatal day 1, 3 and 7 (P1, P3, and P7). Immunohistochemistry was used to evaluate iNOS expression and quantitative reverse transcriptase PCR to analyze iNOS mRNA expression in pup brains at P1, P3 and P7. Nitrate reductase method was used for detection of nitric oxide (NO) concentration in pup brains at P1, P3 and P7.

RESULTS

The immunohistochemical staining for CNPase in the E. coli-treated group showed a decrease compared with the control in periventricular white matter at P7. Obvious immunohistochemical staining of iNOS was observed in periventricular white matter of the E. coli-treated pup brains at P1. The expression of iNOS mRNA in the E. coli-treated pup brains increased at P1 and P3, but there was no significant difference at P7 compared with controls. Similarly, the NO concentration increased in the E. coli-treated pup brains at P1 and P3, and no significant difference was found at P7 compared with controls.

CONCLUSIONS

The alteration of CNPase expression indicates that intrauterine infection could cause oligodendrocyte injury in the developing brain. Moreover, the increased expression of iNOS followed by the increasing NO concentration after intrauterine infection suggests that iNOS might be a key mediator between the intrauterine infection and oligodendrocyte injury in the developing brain.

Value of vaginal fluid proinflammatory cytokines for the prediction of early-onset neonatal infection in preterm premature rupture of the membranes

The usefulness of vaginal fluid proinflammatory cytokine assays in the prediction of neonatal congenital infection was evaluated. Sixty-two women between 24 and 34 weeks of pregnancy, complicated by premature rupture of the membranes, were divided into those who delivered newborns with (n = 21) and without (n = 41) signs of infection. Concentrations of all studied cytokines were higher in women who delivered babies with infection. The cutoff values of interleukin-1alpha (IL-1alpha) and IL-1beta > or = 400, IL-6 > or = 2000, and IL-8 > or = 2100 pg/mL predicted infection with a sensitivity of 57%, 57%, 33%, and 76%, a specificity of 73%, 73%, 93%, and 59%, a positive predictive value of 52%, 52%, 70%, and 48%, and a negative predictive value of 77%, 77%, 73%, and 83%, respectively. Receiver operating characteristic (ROC) curve analysis revealed that the predictive performance of the four studied cytokines was comparable. In conclusion, vaginal fluid cytokines after premature rupture of the membranes have moderately predictive value of whether or not a neonate will develop early sepsis.

Innate immune function of the human decidual cell at the maternal–fetal interface

The aim of the study was to investigate the innate immune function of decidual cells from term unlabored pregnancies by determining Toll-like receptor presence and function. Using immunohistochemistry, reverse transcriptase polymerase chain reaction and NF-kappaB-luciferase plasmid transfection, Toll-like receptor presence and function was determined. Decidual cells express Toll-like receptors 1, 2, 4 and 6 which respond to lipopolysaccharide and peptidoglycan stimulation producing Interleukin-8. Decidual cells from women at term have innate immune function and are capable of producing Interleukin responses to bacterial ligands.

Interleukin 10 Regulates Inflammatory Cytokine Synthesis to Protect Against Lipopolysaccharide-Induced Abortion and Fetal Growth Restriction in Mice1

Interleukin 10 (IL10) is a potent immune-regulating cytokine and inhibitor of inflammatory cytokine synthesis. To evaluate the anti-inflammatory role of IL10 in pregnancy, the response of genetically IL10-deficient mice to low-dose lipopolysaccharide (LPS)-induced abortion was examined. When IL10-null mutant C57Bl/6 (Il10(-/-)) and control (Il10(+/+)) mice were administered low-dose LPS on Day 9.5 of gestation, IL10 deficiency predisposed to fetal loss accompanied by growth restriction in remaining viable fetuses, with an approximately 10-fold reduction in the threshold dose for 100% abortion. After LPS administration, inflammatory cytokines tumor necrosis factor-alpha (TNFA) and IL6 were markedly increased in serum, uterine, and conceptus tissues in Il10(-/-) mice compared with Il10(+/+) mice, with elevated local synthesis of Tnfa and Il6 mRNAs in the gestational tissues. IL1A and IL12p40 were similarly elevated in serum and gestational tissues, whereas interferon gamma (IFNG) and soluble TNFRII content were unchanged in the absence of IL10. Recombinant IL10 rescued the increased susceptibility to LPS-induced fetal loss in Il10(-/-) mice but did not improve outcomes in Il10(+/+) mice. IL10 genotype also influenced the responsiveness of mice to a TNFA antagonist, etanercept. Fetal loss in Il10(-/-) mice was partly alleviated by moderate or high doses of etanercept, whereas Il10(+/+) mice were refractory to high-dose etanercept, consistent with attenuation by IL10 status of TNFA bioavailability after etanercept treatment. These data show that IL10 modulates resistance to inflammatory stimuli by downregulating expression of proinflammatory cytokines TNFA, IL6, IL1A, and IL12, acting to protect against inflammation-induced pathology in the implantation site.

Mild oliguria in preterm infants who later developed periventricular leukomalacia

The aim of this study is to determine whether or not renal involvement was present during the early neonatal period in preterm infants with PVL. We conducted a case-control study. The following items were evaluated; urine output, serum levels of sodium (Na), potassium (K), chloride (Cl), urea nitrogen (UN), and creatinine (Cr). The factors that could influence the urine output were also compared between the PVL and the control group. The mean urine output during the first 24h in the PVL group was 19.8ml/kg/day, and was significantly lower than in the control group (28.8ml/kg/day, p<0.05). The mean UN and Cr were not significantly different between the two groups. The minimal serum Na and Cl levels in the PVL group were significantly lower (128.3 and 94.3mEq/l) than those in the control group (134.8 and 100.7mEq/l, p<0.01 each). The maximal serum K level was significantly higher in the PVL group (6.47mEq/l) as compared to the control group (5.57mEq/l, p<0.05). There were no differences in any postnatal variables between the two groups. The preterm infants who later developed PVL had mild but significant oliguria during the first 24h of life. This suggests that preterm infants with PVL will have renal involvement immediately after birth.

Improved neurodevelopmental outcomes for extremely low birth weight infants in 2000-2002

BACKGROUND

Neurodevelopmental impairment of extremely low birth weight infants increased in the 1990s. Modern therapeutic changes may have influenced more recent neonatal outcomes.

OBJECTIVE

We sought to compare neonatal therapies and outcomes among all extremely low birth weight infants born in 2000-2002 (period III) to 2 previous periods: 1982-1989 (period I) and 1990-1999 (period II).

METHODS

The population included 496 extremely low birth weight infants born at our perinatal center during period I, 749 during period II, and 233 during period III. Therapies, rates of death, and survival with and without impairment at 20 months' corrected age were compared.

RESULTS

Between periods I and II, survival increased from 49% to 68% as did neonatal morbidity. This resulted in increased survival without impairment but also increased survival with impairment. Changes in therapy during period III included an increase in antenatal steroid use and a decrease in postnatal steroid use, although the rate of chronic lung disease did not change. Sepsis decreased, as did severe intraventricular hemorrhage. On follow-up, the rate of cerebral palsy decreased from 13% to 5%, resulting in a decrease in neurodevelopmental impairment from 35% to 23%. As a result, during period III versus II, survival without impairment increased, whereas survival with impairment decreased.

CONCLUSION

Since 2000, neurodevelopmental impairment has decreased among extremely low birth weight infants. A variety of perinatal and neonatal factors were associated with the improved outcomes including increased antenatal steroid use and cesarean section delivery, as well as decreased sepsis, severe cranial ultrasound abnormalities, and postnatal steroid use despite no change in the rate of chronic lung disease.

The role of inflammation and infection in preterm birth

Inflammation has been implicated in the mechanisms responsible for preterm and term parturition, as well as fetal injury. Out of all of the suspected causes of preterm labor and delivery, infection and/or inflammation is the only pathological process for which both a firm causal link with preterm birth has been established and a molecular pathophysiology defined. Inflammation has also been implicated in the mechanism of spontaneous parturition at term. Most cases of histopathological inflammation and histological chorioamnionitis, both in preterm and term labor, are sub-clinical in nature. The isolation of bacteria in the amniotic fluid, known as microbial invasion of the amniotic cavity, is a pathological finding; the frequency of which is dependent upon the clinical presentation and gestational age. This article reviews the role of inflammation in preterm and term parturition.

Innate immunity: toll-like receptors and some more. A brief history, basic organization and relevance for the human newborn

The discovery of Toll-like receptors (TLRs) as essential components of the innate immune system has greatly advanced our knowledge and understanding of immune responses to infection and how these are regulated. Innate immunity in general and TLRs in particular play a crucial role in the front line of host defenses against microbes, but also are a key element in the proper functioning of the immune system at large in vertebrate animals. The innate immune system has been identified as a collection of factors, both cell-associated and cell-free, that comprises an impressively effective and well-organized system that is capable of immediate recognition of a whole array of microbes and microbial components. The cell-bound TLRs fulfill a central role in the process from pathogen recognition to activation of adaptive immunity. From the cell-free factors the plasma protein mannose-binding lectin (MBL) has been studied most extensively. Associations have already been documented between TLR polymorphisms in man and TLR deficiency in animals and an increased susceptibility to infection. The effect of MBL on infectious disease susceptibility only seems to emerge when host defenses are compromised by a severe underlying condition. The functional state of the various components of innate immunity at birth is largely unknown and only recently a number of studies have assessed this feature of the innate immune system. In addition, for the human newborn the innate immune system may have a broader significance; it may well be the key system determining the course of inflammatory events associated with premature birth, a notion that is emphasized by the recently described association between TLR polymorphisms and prematurity. However, there are still many open questions, particularly about the exact relation between individual TLRs and infectious disease susceptibility and how TLRs cooperate in resistance to infection and in initiating adaptive immune responses. With regard to the human newborn, the most relevant question that needs to be resolved is the precise role of innate immunity in the pathogenesis of prematurity.

Erythropoietin attenuates lipopolysaccharide-induced white matter injury in the neonatal rat brain

Periventricular leukomalacia (PVL), a common neonatal brain white matter (WM) lesion, is frequently associated with cerebral palsy. Growing evidence has indicated that in addition to ischemia/reperfusion injury, cytokine-induced brain injury associated with maternal or fetal infection may also play an important role in the pathogenesis of PVL. Recent studies have shown that administration of lipopolysaccharide (LPS) to pregnant rats causes enhanced expression of the cytokines, i.e., IL-1 beta, TNF-alpha, and IL-6, in fetal brains. In recent years, it has been shown that erythropoietin (EPO) has a critical role in the development, maintenance, protection and repair of the nervous system. In the present study we investigated the effect of EPO on LPS-induced WM injury in Sprague-Dawley rats. LPS (500 microg/kg) suspension in pyrogen-free saline was administered intraperitoneally to pregnant rats at 18 and 19 days of gestation. The control group was treated with pyrogen-free saline. They were given 5,000 U/kg recombinant human EPO. Seven-day-old Sprague-Dawley rat pups were divided into four groups: control group, LPS-treated group, prenatal maternal EPO-treated group (5,000 U/kg, intraperitoneally given to pregnant rats at 18 and 19 days of gestation), and postnatal EPO-treated group (5,000 U/kg, intraperitoneally given to 1-day-old rat pups). Cytokine induction in the postnatal 7-day-old (P7) rat brain after maternal administration of LPS was determined by the ELISA method. The proinflammatory cytokine levels (IL-1 beta, TNF-alpha, and IL-6) in P7 rat pup brains were significantly increased in the LPS-treated group as compared with the control group. Prenatal maternal EPO treatment significantly reduced the concentration of TNF-alpha and IL-6 in the newborn rat brain following LPS injection. The concentration of IL-1 beta was decreased in the intrauterine EPO treatment group. Postnatal EPO treatment significantly decreased only the IL-6 concentration in the newborn rat brain following LPS injection. The concentration of cytokines, IL-1 beta and TNF-alpha, was reduced in the postnatal EPO treatment group. We demonstrated here that LPS administration in pregnant rats at gestational day 18 and 19 induced WM injury in P7 progeny characterized by apoptosis. Prenatal maternal and postnatal EPO treatment significantly reduced the number of apoptotic cells in the periventricular WM. Using immunohistochemistry techniques, we investigated the effects of maternal administration of LPS on myelin basic protein (MBP) staining, as a marker of myelination in the periventricular area in the neonatal rat brain. MBP staining was significantly less and weaker in the brains of the LPS-treated group as compared with the prenatal maternal EPO-treated group. However, the postnatal EPO treatment did not prevent LPS-stimulated loss of MBP-positive staining. In conclusion, especially prenatal maternal EPO treatment attenuates LPS-induced injury by reducing the expression of inflammatory cytokines and sparing MBP in the neonatal rat brain. While the postnatal EPO treatment prevented LPS-induced brain injury this effect was partial. To our knowledge, this is the first study that demonstrates a protective effect of EPO on LPS-induced WM injury in the developing brain. Regarding the wide use of EPO in premature newborns, this agent maybe potentially beneficial in treating LPS-induced brain injury in the perinatal period.

Astrocytes and developmental white matter disorders

There is an increasing awareness that the astrocytes in the immature periventricular white matter are vulnerable to ischemia and respond to inflammation. Here we provide a synopsis of the articles that have evaluated the causes and consequences of developmental brain injuries to white matter astrocytes as well as the consequences of several genetic mutations that result in abnormal astrocyte development. Emerging data suggest that the astrocytes are not simply responding to the injury but are likely victims as well as culprits. Given the important roles that astrocytes play in maintaining ionic, neurotransmitter, and metabolic homeostasis in the brain, a more thorough understanding of the mechanisms that lead to their incapacitation, demise, or reactions as well as a better understanding of the stimuli that regulate their neuroprotective and regenerative properties will enable these cells to be manipulated to preserve the integrity of white matter and to potentially provide therapeutics to enhance neonatal regeneration and recovery from brain injury.

Neonatal mortality and morbidity after aggressive long-term tocolysis for preterm premature rupture of the membranes

OBJECTIVE

To test the hypothesis that predischarge morbidity and mortality are not increased for infants admitted to our neonatal intensive care unit and whose mothers had tocolysis for >48 h plus antibiotics and steroids (aggressive long-term tocolysis) after preterm premature rupture of the membranes (PPROM) as compared with gestational age-matched infants born to mothers not treated for PPROM.

METHODS

A retrospective cohort study was conducted on live preterm births (<or=36.0 weeks) admitted to the neonatal intensive care unit between January 1, 1999 and June 30, 2003, comparing singletons born to mothers with PPROM+tocolysis for >48 h (n=137, group 1) with singletons born to all other mothers matched for group-1 gestational age at delivery (n=628, group 2), excluding severe maternal complications such as insulin-dependent diabetes and preeclampsia in both groups. Primary outcome was the predischarge mortality and morbidity of the neonates.

RESULTS

In the group with post-PPROM tocolysis which lasted for 14.4+/-14.0 days with a latency of 15.3+/-15.3 days (time from PPROM to delivery) and 14.4+/-14.0 days (time from the start of tocolysis to delivery), the predischarge mortality and morbidity was not increased compared to the non-treated group. The 1- and 10-min Apgar scores of between 1 and 7 were less frequent with tocolysis (p<0.05), and oxygen use was less frequent (26.3 vs. 36.3%, p=0.03) and shorter (8.7 vs. 19.6 days, p=0.03). However, amniotic fluid infection syndrome and latency (i.e. >1 week) are the most potential predictors of the respiratory distress syndrome in addition to gestational age at delivery in pregnancies with post-PPROM tocolysis.

CONCLUSIONS

Amniotic fluid infection syndrome and a latency of >1 week achieved by aggressive post-PPROM tocolysis lessens the advantages of extended gestational age and decreased predischarge neonatal morbidity. These findings may have important implications for the clinical management of PPROM.

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.

A rapid MMP-8 bedside test for the detection of intra-amniotic inflammation identifies patients at risk for imminent preterm delivery

OBJECTIVE

Matrix metalloproteinase-8 (MMP-8) is an enzyme that is released during neutrophil activation. MMP-8 amniotic fluid concentrations are elevated not only in patients with intra-amniotic infection, but also in patients with negative amniotic fluid cultures who deliver preterm neonates. The objective of this study was to determine whether the results of a rapid MMP-8 bedside test predict imminent preterm delivery. This test can be performed in 15 minutes and without laboratory equipment.

STUDY DESIGN

Amniotic fluid was retrieved from 331 patients admitted with increased preterm uterine contractions and intact membranes who met the inclusion criteria. Amniotic fluid was processed for microbial cultures, Gram stain, glucose concentration, and white blood cell count. Amniotic fluid samples were stored, and the MMP-8 rapid test was performed after delivery. End points included spontaneous preterm delivery within 48 hours, 7 days, and 14 days. Diagnostic indices, predictive values, and likelihood ratios were calculated.

RESULTS

The prevalence of spontaneous preterm delivery within 48 hours, 7 days, and 14 days was 11.6% (38/327), 20.2% (66/327), and 24.5% (80/327), respectively (4 patients with augmentation of labor were excluded). A positive MMP-8 rapid test had a positive predictive value of 70% (23/33) for the identification of patients who delivered spontaneously within 48 hours, and 94% (31/33) for patients who were delivered within 7 days and 14 days (likelihood ratios: 17.5 [95% CI, 9-33.9], 61.3 [95% CI, 15.1-250], and 50 [95% CI, 12-196], respectively).

CONCLUSION

The MMP-8 rapid test can identify patients at risk for preterm delivery within 7 days and 14 days. Moreover, a positive MMP-8 rapid test result can identify patients with intra-amniotic infection/inflammation with a high sensitivity and specificity. This rapid test will give clinicians a fast and accurate assessment of the inflammatory status of the amniotic cavity and allow for better identification of patients at risk for impending preterm delivery.

Essential Role for IL-10 in Resistance to Lipopolysaccharide-Induced Preterm Labor in Mice

IL-10 is highly expressed in the uterus and placenta and is implicated in controlling inflammation-induced pathologies of pregnancy. To investigate the role of IL-10 in regulating preterm labor, the response of IL-10 null mutant mice to low-dose LPS in late gestation was evaluated. When IL-10 null mutant C57BL/6 (IL-10(-/-)) and control (IL-10(+/+)) mice were administered LPS on day 17 of pregnancy, the dose of LPS required to elicit 50% preterm fetal loss was 10-fold lower in IL-10(-/-) mice than in IL-10(+/+) mice. Surviving fetuses in IL-10(-/-) mice exhibited fetal growth restriction at lower doses of LPS than IL-10(+/+) mice. Marked elevation of LPS-induced immunoactive TNF-alpha and IL-6 was evident in the serum, uterus, and placenta of IL-10(-/-) mice, and TNF-alpha and IL-6 mRNA expression was elevated in the uterus and placenta, but not the fetus. Serum IL-1alpha, IFN-gamma, and IL-12p40 were increased and soluble TNFRII was diminished in the absence of IL-10, with these changes also reflected in the gestational tissues. Administration of rIL-10 to IL-10(-/-) mice attenuated proinflammatory cytokine synthesis and alleviated their increased susceptibility to preterm loss. Exogenous IL-10 also protected IL-10(+/+) mice from fetal loss. These data show that IL-10 modulates resistance to inflammatory stimuli by down-regulating proinflammatory cytokines in the uterus and placenta. Abundance of endogenous IL-10 in gestational tissues is therefore identified as a critical determinant of resistance to preterm labor, and IL-10 may provide a useful therapeutic agent in this common condition.

Tumour Necrosis Factor-alpha Converting Enzyme in Human Gestational Tissues from Pregnancies Complicated by Chorioamnionitis

Chorioamnionitis increases the risk of preterm labour and is associated with adverse neonatal outcomes including cerebral palsy. Tumour necrosis factor-alpha (TNF-alpha) derived from the gestational tissues (placenta, fetal membranes and maternal decidua) is thought to play a pivotal role in the induction of cytokine response in chorioamnionitis. Tumour necrosis factor-alpha converting enzyme (TACE) is essential for the release of TNF-alpha. Our aim was to determine whether the expression of TACE is increased in human gestational tissues from pregnancies complicated by chorioamnionitis, and whether lipopolysaccharide (LPS) causes increased expression of TACE in the human gestational tissues in vitro. The immunostaining of TACE was generally more intense, in particular in the syncytiotrophoblast and stromal cells, in villous samples from pregnancies complicated by chorioamnionitis than those from normal pregnancies. Increased immunoreactivity of TACE was also noted in the amnion and choriodecidua. In parallel, there was an increased infiltration of monocytes/macrophages within the villous stroma and choriodecidua. As a complement to our in vivo findings, LPS significantly increased the levels of mRNA and protein of TACE in a dose-dependent response in villous and fetal membrane explant cultures. Together, our results imply a potential role of TACE in the pathogenesis of chorioamnionitis.

Maternal infection and white matter toxicity

Studies examining maternal infection as a risk factor for neurological disorders in the offspring have suggested that altered maternal immune status during pregnancy can be considered as an adverse event in prenatal development. Infection occurring in the mother during the gestational period has been implicated in multiple neurological effects. The current manuscript will consider the issue of immune/inflammatory conditions during prenatal development where adverse outcomes have been linked to maternal systemic infection. The discussions will focus primary on white matter and oligodendrocytes as they have been identified as target processes. This white matter damage occurs in very early preterm infants and in various other human diseases currently being examined for a linkage to maternal or early developmental immune status. The intent is to draw attention to the impact of altered immune status during pregnancy on the offspring for the consideration of such contributing factors to the general assessment of developmental neurotoxicology.