Human Preterm Newborns Research Articles

CD71 + erythroid cells promote intestinal symbiotic microbial communities in pregnancy and neonatal period

BackgroundThe establishment of microbial communities in neonatal mammals plays a pivotal role in shaping their immune responses to infections and other immune-related conditions. This process is influenced by a combination of endogenous and exogenous factors. Previously, we reported that depletion of CD71 + erythroid cells (CECs) results in an inflammatory response to microbial communities in newborn mice.ResultsHere, we systemically tested this hypothesis and observed that the small intestinal lamina propria of neonatal mice had the highest frequency of CECs during the early days of life. This high abundance of CECs was attributed to erythropoiesis niches within the small intestinal tissues. Notably, the removal of CECs from the intestinal tissues by the anti-CD71 antibody disrupted immune homeostasis. This disruption was evident by alteration in the expression of antimicrobial peptides (AMPs), toll-like receptors (TLRs), inflammatory cytokines/chemokines, and resulting in microbial dysbiosis. Intriguingly, these alterations in microbial communities persisted when tested 5 weeks post-treatment, with a more notable effect observed in female mice. This illustrates a sex-dependent association between CECs and neonatal microbiome modulation. Moreover, we extended our studies on pregnant mice, observing that modulating CECs substantially alters the frequency and diversity of their microbial communities. Finally, we found a significantly lower proportion of CECs in the cord blood of pre-term human newborns, suggesting a potential role in dysregulated immune responses to microbial communities in the gut.ConclusionsOur findings provide novel insights into pivotal role of CECs in immune homeostasis and swift adaptation of microbial communities in newborns. Despite the complexity of the cellular biology of the gut, our findings shed light on the previously unappreciated role of CECs in the dialogue between the microbiota and immune system. These findings have significant implications for human health.9S5HPFpJwLA9vyqyoAGSTRVideo

Caffeine Restores Background EEG Activity Independent of Infarct Reduction after Neonatal Hypoxic Ischemic Brain Injury

In human preterm newborns, caffeine increases brain activity and improves neurodevelopmental outcomes. In animal models of hypoxic ischemic brain injury, caffeine pretreatment reduces infarct volume. We studied the relationship between tissue neuroprotection and brain activity after injury to further understand caffeine neuroprotection. Rat dams received caffeine prior to birth or on postnatal day 3 (P3) through P16. Caffeine-treated and -untreated pups underwent the Vannucci procedure (unilateral carotid ligation, global hypoxia) on P2. A subset had EEG recordings. Brain hemispheric infarct volume was measured on P16. P2 hypoxic ischemia (HI) results in histologic brain injury (mean ± standard deviation infarct volume 10.3 ± 4.6%) and transient suppression of EEG activity. Caffeine pretreatment reduces brain injury (mean ± standard deviation infarct volume 1.6 ± 4.5%, p < 0.001) and improves amplitude-integrated EEG (aEEG) and EEG burst duration and amplitude. Caffeine treatment after HI does not reduce infarct volume (mean ± standard deviation 8.3 ± 4.1%, p = 1.0). However, caffeine posttreatment was equally effective at restoring aEEG amplitude and EEG burst duration and amplitude. Thus, caffeine supports brain background electrical activity independent of tissue neuroprotection.

Dextran sodium sulfate (DSS) induces necrotizing enterocolitis-like lesions in neonatal mice.

BackgroundNecrotizing enterocolitis (NEC) is an inflammatory bowel disease of preterm human newborns with yet unresolved etiology. An established neonatal murine model for NEC employs oral administration of lipopolysaccharides (LPS) combined with hypoxia/hypothermia. In adult mice, feeding dextran sodium sulfate (DSS) represents a well-established model for experimental inflammatory bowel disease. Here we investigated the effect of DSS administration on the neonatal murine intestine in comparison with the established NEC model.Methods3-day-old C57BL/6J mice were either fed formula containing DSS or LPS. LPS treated animals were additionally stressed by hypoxia/hypothermia twice daily. After 72 h, mice were euthanized, their intestinal tissue harvested and analyzed by histology, qRT-PCR and flow cytometry. For comparison, adult C57BL/6J mice were fed with DSS for 8 days and examined likewise. Untreated, age matched animals served as controls.ResultsAdult mice treated with DSS exhibited colonic inflammation with significantly increased Cxcl2 mRNA expression. In contrast, tissue inflammation in neonatal mice treated with DSS or LPS plus hypoxia/hypothermia was present in colon and small intestine as well. Comparative analysis of neonatal mice revealed a significantly increased lesion size and intestinal Cxcl2 mRNA expression after DSS exposure. Whereas LPS administration mainly induced local neutrophil recruitment, DSS treated animals displayed increased monocytes/macrophages infiltration.ConclusionsOur study demonstrates the potential of DSS to induce NEC-like lesions accompanied by a significant humoral and cellular immune response in the small and large intestine of neonatal mice. The new model therefore represents a good alternative to LPS plus hypoxia/hypothermia administration requiring no additional physical stress.

Venous lactate, pH and partial pressure of carbon dioxide levels as prognostic indicators in 110 premature calves with respiratory distress syndrome

Hyperlactatemia, hypercapnia, low pH and low oxygen saturation (SatO2) are commonly observed in premature calves. These clinical indicators are associated with increased mortality in preterm human newborns with respiratory distress...

Proteomic characterization of the acid-insoluble fraction of whole saliva from preterm human newborns

The acid-insoluble salivary proteome obtained by addition of TFA to whole human saliva from adults, preterm and at-term newborns has been analysed by 2-DE in order to evidence differences among the three groups, and integrate data previously obtained on the acid-soluble fraction. 2-DE spots differentially expressed among the three groups were submitted to in-gel tryptic digestion and the peptide mixtures analysed by high resolution HPLC–ESI–MS/MS. By this strategy, we identified 3 over-expressed proteins in at-term newborns with respect to preterm newborns and adults (BPI fold-containing family A member 1, annexin A1, and keratin type 1 cytoskeletal 13), and several over-expressed proteins in adults (fatty acid-binding protein, S100A6, S100A7, S100A9, prolactin-inducible protein, Ig kappa chain, cystatin SN, cystatin S/SA and α-amylase 1). Four spots, already detected but not characterized by other authors in human saliva 2-DE, were attributed to different protein species of S100A9 (long-type and long-type monophosphorylated, short-type and short-type monophosphorylated) by MS/MS analysis of tryptic peptides and sequential staining of 2-DE gels with Pro-Q Diamond, for specific detection of phosphoproteins, and total protein SYPRO Ruby stain. SignificanceDifferential protein expression analysis of the acid insoluble fraction of saliva from preterm, at-term newborns and adults has been performed in this study by coupling 2-DE analysis and high-resolution tandem mass spectrometry in order to complete the information previously obtained by top-down LC–MS only on the acid-soluble proteome. Several proteins identified in the acid insoluble fraction of both preterm newborn and adult saliva are not of glandular origin, being only prolactin-inducible protein, salivary cystatins, α-amylase and polymeric immunoglobulin receptor exclusive of salivary glands.Three proteins resulted increased in at-term newborns with respect to preterm newborns and adults: BPI fold-containing family A member 1, two proteoforms of annexin A1 and keratin type 1 cytoskeletal 13, while several proteins were significantly increased in adults.

Involvement of neuronal IL-1β in acquired brain lesions in a rat model of neonatal encephalopathy

BackgroundInfection-inflammation combined with hypoxia-ischemia (HI) is the most prevalent pathological scenario involved in perinatal brain damage leading to life-long neurological disabilities. Following lipopolysaccharide (LPS) and/or HI aggression, different patterns of inflammatory responses have been uncovered according to the brain differentiation stage. In fact, LPS pre-exposure has been reported to aggravate HI brain lesions in post-natal day 1 (P1) and P7 rat models that are respectively equivalent - in terms of brain development - to early and late human preterm newborns. However, little is known about the innate immune response in LPS plus HI-induced lesions of the full-term newborn forebrain and the associated neuropathological and neurobehavioral outcomes.MethodsAn original preclinical rat model has been previously documented for the innate neuroimmune response at different post-natal ages. It was used in the present study to investigate the neuroinflammatory mechanisms that underline neurological impairments after pathogen-induced inflammation and HI in term newborns.ResultsLPS and HI exerted a synergistic detrimental effect on rat brain. Their effect led to a peculiar pattern of parasagittal cortical-subcortical infarcts mimicking those in the human full-term newborn with subsequent severe neurodevelopmental impairments. An increased IL-1β response in neocortical and basal gray neurons was demonstrated at 4 h after LPS + HI-exposure and preceded other neuroinflammatory responses such as microglial and astroglial cell activation. Neurological deficits were observed during the acute phase of injury followed by a recovery, then by a delayed onset of profound motor behavior impairment, reminiscent of the delayed clinical onset of motor system impairments observed in humans. Interleukin-1 receptor antagonist (IL-1ra) reduced the extent of brain lesions confirming the involvement of IL-1β response in their pathophysiology.ConclusionIn rat pups at a neurodevelopmental age corresponding to full-term human newborns, a systemic pre-exposure to a pathogen component amplified HI-induced mortality and morbidities that are relevant to human pathology. Neuronal cells were the first cells to produce IL-1β in LPS + HI-exposed full-term brains. Such IL-1β production might be responsible for neuronal self-injuries via well-described neurotoxic mechanisms such as IL-1β-induced nitric oxide production, or IL-1β-dependent exacerbation of excitotoxic damage.

Top-down HPLC–ESI–MS detection of S-Glutathionylated and S-Cysteinylated Derivatives of Cystatin B and Its 1–53 and 54–98 Fragments in Whole Saliva of Human Preterm Newborns

Analysis by a HPLC-ESI-MS top-down proteomic platform of specimens of human preterm newborn whole saliva evidenced high relative amounts of cystatin B and its S-glutathionylated,S-cysteinylated, and S-S 2-mer (on Cys(3)) derivatives, decreasing as a function of postconceptional age (PCA). The percentage of S-unmodified cystatin B was higher than the S-modified isoforms in the early PCA period, differently from adults where cystatin B was detectable only as S-modified derivatives. The percentage of S-modified derivatives increased as a function of PCA, reaching at the normal term of delivery values similar to those determined in at-term newborns, babies, and adults. Moreover, in the early PCA period, high relative amounts of the 1-53 and 54-98 cystatin B fragments were detected, decreasing as a function of PCA and disappearing at the normal term of delivery. In agreement with intact cystatin B, fragment 1-53 was detectable as S-unmodified and S-modified derivatives, and their percentages changed accordingly with the percentages of intact proteins, suggesting that the fragmentation process could be subsequent to and independent from the S-modification of the protein. This study highlights specific enzymatic activity in the oral cavity of preterm newborns not present in at-term newborns and adults, which can be a clue to specialized pathways occurring during fetal oral development.

Hyperoxia Impairs Alveolar Formation and Induces Senescence Through Decreased Histone Deacetylase Activity and Up-Regulation of p21 in Neonatal Mouse Lung

Alveolar development comprises the transition of lung architecture from saccules to gas-exchange units during late gestation and early postnatal development. Exposure to hyperoxia disrupts developmental signaling pathways and causes alveolar hypoplasia as seen in bronchopulmonary dysplasia affecting preterm human newborns. Expanding literature suggests that epigenetic changes caused by environmental triggers during development may lead to heritable changes in gene expression. Given recent data on altered histone deacetylase (HDAC) activity in lungs of humans and animal models with airspace enlargement/emphysema, we hypothesized that alveolar hypoplasia from hyperoxia exposure in neonatal mice is a consequence of cell cycle arrest and reduced HDAC activity and up-regulation of the cyclin-dependent kinase inhibitor, p21. We exposed newborn mice to hyperoxia and compared lung morphologic and epigenetic changes to room air controls. Furthermore, we pretreated a subgroup of animals with the macrolide antibiotic azithromycin (AZM), known to possess antiinflammatory properties. Our results showed that hyperoxia exposure resulted in alveolar hypoplasia and was associated with decreased HDAC1 and HDAC2 and increased p53 and p21 expression. Furthermore, AZM did not confer protection against hyperoxia-induced alveolar changes. These findings suggest that alveolar hypoplasia caused by hyperoxia is mediated by epigenetic changes affecting cell cycle regulation/senescence during lung development.

Dor fetal: motivo para preocupação?

IntroductionWith the evolution of Fetal Medicine and the increasing use of invasive techniques, it is mandatory to investigate if fetal pain is really an issue. MethodsA bibliographic search on scientific knowledge of fetal pain, its neuroanatomical and neurophysiological bases, consequences and clinical implications was conducted in Pubmed. ResultsDue to practical and ethical restrictions in using the human fetus in research, most of the evidence in this area is indirectly inferred from animal studies and through observations made in preterm human newborns. Pain perception is assumed from the integrity of neuroanatomic structures and its functionality, as well as from the endocrinal, hemodynamic and behavioral changes associated with pain. This perception is not likely to exist before 29-30 weeks of gestational age. The exposure to noxious stimulus in the perinatal period seems likely to cause to neurological development and behavioral changes, thereby fetal analgesia/anesthesia can mitigate the reaction to stress and thus avoid these deleterious long-term effects. ConclusionsGiven that pain is a subjective experience, its neurobiological understanding is far more complex than the basic knowledge of the anatomical and physiological ways of nociception. Available data derived from main studies in this area do not take into account the intrauterine environment idiossincracies and so can not prove the existence of fetal pain awareness. On the other hand, further investigation is needed to clarify the impact of fetal nociception in postnatal neurodevelopment, as well as the need for fetal analgesia/anesthesia.

The Surprising Composition of the Salivary Proteome of Preterm Human Newborn

Saliva is a body fluid of a unique composition devoted to protect the mouth cavity and the digestive tract. Our high performance liquid chromatography (HPLC)-electrospray ionization-MS analysis of the acidic soluble fraction of saliva from preterm human newborn surprisingly revealed more than 40 protein masses often undetected in adult saliva. We were able to identify the following proteins: stefin A and stefin B, S100A7 (two isoforms), S100A8, S100A9 (four isoforms), S100A11, S100A12, small proline-rich protein 3 (two isoforms), lysozyme C, thymosins β(4) and β(10), antileukoproteinase, histone H1c, and α and γ globins. The average mass value reported in international data banks was often incongruent with our experimental results mostly because of post-translational modifications of the proteins, e.g. acetylation of the N-terminal residue. A quantitative label-free MS analysis showed protein levels altered in relation to the postconceptional age and suggested coordinate and hierarchical functions for these proteins during development. In summary, this study shows for the first time that analysis of these proteins in saliva of preterm newborns might represent a noninvasive way to obtain precious information of the molecular mechanisms of development of human fetal oral structures.

Profound Lack of Interleukin (IL)–12/IL‐23p40 in Neonates Born Early in Gestation Is Associated with an Increased Risk of Sepsis

Infants born prematurely are highly vulnerable to infections and also exhibit a high susceptibility to organ damage due to inflammation. To investigate homeostatic immune control early in life, we used advanced multiparameter flow cytometry to compare responses to multiple Toll-like receptor (TLR) ligands in single cells and mononuclear cell populations in term neonates versus preterm neonates born before 29 weeks of gestation. Preterm neonates had globally attenuated TLR-stimulated interleukin (IL)-6, interferon-α, and, to a lesser extent, tumor necrosis factor-α responses but demonstrated relative preservation of anti-inflammatory IL-10 responses in monocytes and dendritic cell subtypes. Remarkably, preterm neonates were also profoundly deficient in the common IL-12 and IL-23 cytokines' p40 subunit, which is critical for immunity against a wide variety of microbial pathogens in mice. Consistent with the increased susceptibility to infections resulting from the lack of IL-12/IL-23 in human newborns, significantly lower serum p40 concentrations were observed at birth in infants who developed early-onset sepsis. To our knowledge, this study is the first detailed analysis of multiple TLR function in neonates born extremely premature. Although attenuation of proinflammatory pathways may protect against tissue-damaging immunity early in life, this previously unrecognized p40 immune deficiency appears to result in considerably increased susceptibility to infection in human preterm newborns.

Platelets contribute to postnatal occlusion of the ductus arteriosus

The ductus arteriosus (DA) is a fetal shunt vessel between the pulmonary artery and the aorta that closes promptly after birth. Failure of postnatal DA closure is a major cause of morbidity and mortality particularly in preterm neonates. The events leading to DA closure are incompletely understood. Here we show that platelets have an essential role in DA closure. Using intravital microscopy of neonatal mice, we observed that platelets are recruited to the luminal aspect of the DA during closure. DA closure is impaired in neonates with malfunctioning platelet adhesion or aggregation or with defective platelet biogenesis. Defective DA closure resulted in a left-to-right shunt with increased pulmonary perfusion, pulmonary vascular remodeling and right ventricular hypertrophy. Our findings indicate that platelets are crucial for DA closure by promoting thrombotic sealing of the constricted DA and by supporting luminal remodeling. A retrospective clinical study revealed that thrombocytopenia is an independent predictor for failure of DA closure in preterm human newborns, indicating that platelets are likely to contribute to DA closure in humans.

Thymosin β4 and β10 Levels in Pre-Term Newborn Oral Cavity and Foetal Salivary Glands Evidence a Switch of Secretion during Foetal Development

BackgroundThymosin β4, its sulfoxide, and thymosin β10 were detected in whole saliva of human pre-term newborns by reversed-phase high performance chromatography coupled to electrospray ion-trap mass spectrometry.Methodology/Principal FindingsDespite high inter-individual variability, concentration of β-thymosins increases with an inversely proportional trend to postmenstrual age (PMA: gestational age plus chronological age after birth) reaching a value more than twenty times higher than in adult whole saliva at 190 days (27 weeks) of PMA (thymosin β4 concentration: more than 2.0 µmol/L versus 0.1 µmol/L). On the other hand, the ratio between thymosin β4 and thymosin β10 exhibits a constant value of about 4 along all the range of PMA (190–550 days of PMA) examined. In order to investigate thymosin β4 origin and to better establish the trend of its production as a function of gestational age (GA), immunohistochemical analysis of major and minor salivary glands of different pre-term fetuses were carried out, starting from 84 days (12 weeks) of gestational age. Reactive granules were seen in all glands with a maximum of expression around 140–150 days of GA, even though with high inter- and intra-individual variability. In infants and adults reactive granules in acinar cells were not observed, but just a diffuse cytoplasmatic staining in ductal cells.SignificanceThis study outlines for the first time that salivary glands during foetal life express and secrete peptides such as β-thymosins probably involved in the development of the oral cavity and its annexes. The secretion increases from about 12 weeks till to about 21 weeks of GA, subsequently it decreases, almost disappearing in the period of expected date of delivery, when the gland switches towards the secretion of adult specific salivary peptides. The switch observed may be an example of further secretion switches involving other exocrine and endocrine glands during foetal development.

IL-2 receptor gene expression and IL-2 production by human preterm newborns' cells.

IL-2 receptor (IL-2R) gene expression in human umbilical cord blood mononuclear cells (CBMC) of preterm and term newborns was examined following stimulation for 18 h with phytohaemagglutinin (PHA) and compared with that of adult peripheral blood mononuclear cells (PBMC; mothers and control group). mRNA for IL-2R could not be detected in CBMC of preterm infants, whereas the mRNA levels for IL-2R found in full term neonates were similar to those observed in PBMC of adults. IL-2 activity in conditioned medium (CM) of mononuclear cells stimulated with either optimal or suboptimal PHA concentrations for 24 h and 48 h was also determined. At 24 h of stimulation, IL-2 activity found in CM obtained from CBMC of preterm and term newborns was significantly higher than that found in CM of adults' PBMC. A further enhancement of IL-2 activity (six to eight times) was observed in CM of preterm and term cells stimulated for 48 h, whereas no significant difference was found in IL-2 activity in CM from adult cells tested at the two incubation periods. The present findings may provide an additional explanation for the impaired function of the immune system, and the high susceptibility to infections observed in preterm newborns.

Transient Inhibition of Astrocytogenesis in Developing Mouse Brain Following Postnatal Caffeine Exposure

Caffeine is frequently administered in human preterm newborns. Although some data suggest a potential risk for the developing brain, its impact has not been fully evaluated. We used a murine model of postnatal caffeine treatment in which mouse pups received intraperitoneal injections of caffeine from postnatal days 3 to 10. Caffeine exposure resulted in a transient reduction of glial fibrillary acidic protein and S100beta protein expression in various brain areas during the first 2 postnatal weeks (19.8% and 23.2% reduction in the hippocampus at P15, respectively). This effect was dose-dependent and at least partly involved a reduction of glial proliferation, as a caffeine-induced decrease of 5-bromodeoxyuridine incorporation was observed in the dentate gyrus and subventricular zone (25.8% and 26.6%, respectively) and no increase of programmed cell death (cleaved caspase-3 immunostaining) was observed at postnatal day 7. This effect could be reproduced with an antagonist of A(2a) adenosine receptor (A(2a)R) and was blocked by co-injection of an agonist. These results suggest that postnatal caffeine treatment might induce an alteration of astrocytogenesis via A(2a)R blockade during brain development. Although no obvious neuritic abnormalities (microtubule-associated protein 2 and synaptophysin immunostaining) were observed, postnatal caffeine treatment could have long-term consequences on brain function.

Can We Define the Pathogenesis of Human Periventricular White-Matter Injury Using Animal Models?

In this issue, Dr Back et al present an elegant model of periventricular white-matter injury using fetal sheep between 90 and 120 days of gestation. This gestational epoch corresponds especially nicely to the neurodevelopment of oligodendrocytes, seen in the preterm human infant between 24 and 28 weeks of age. Although a number of fetal sheep models have been described and used to mimic hypoxic-ischemic or inflammatory insults to the developing brain (reviewed in Hagberg et al), the model described in this article has the added benefit of correlating the molecular and cell fate commitment of oligodendrocytes with changes in cerebral blood flow as measured by high-resolution spatially defined techniques performed in utero. A careful analysis of oligodendroglial lineage progression has been done and compared with that reported previously by the authors for humans, showing a tight correlation. Given that impaired cerebrovascular autoregulation in the setting of blood pressure instability has been implicated in the pathogenesis of periventricular white-matter injury, the authors used fluorescently labeled microspheres to determine spatial blood flow of the ovine fetus. They found that even basal blood flow was markedly lower in parietal and frontal periventricular white matter than in many thalamic nuclei and the cortex. They are now poised to study the effects of regional and global ischemia and infection on flow to vulnerable regions and subsequent development of white matter as it relates to oligodendrocyte maturation. In fact, in a recent publication, Riddle et al showed that spatial heterogeneity in oligodendrocyte lineage is actually linked to stage at maturation when the insult occurs rather than to cerebral blood flow. In human preterm newborns, a wide range of abnormalities have been described using magnetic resonance imaging (MRI) that supersede our previous thinking that the disease is restricted to periventricular leucomalacia. In fact, it appears that the periventricular leukomalacia described by Banker and Larroche is now decreasing, but periventricular white-matter injury is not. For example, white-matter injury can be patchy or diffuse, accompanied by ventriculomegaly, or the latter seen in isolation. Hemorrhage can also be seen in these fragile newborns in both the cerebrum and the cerebellum. Do the animal models reflect these variations? The recently described baboon model sustains a spectrum of neuropathologies, including those described above for humans. The value of the baboon model is that no insult is being created or inflicted on the animals; rather, they are just being born prematurely and being subjected to that which would be experienced by the human preterm newborn. The white-matter injury seen in the baboons ranges from small patches of reactive astrocytosis to cystic lesions. Hemorrhages seen in the baboons ranged from ventricular, white matter, germinal matrix, subarachnoid, to cerebellar in location. Importantly, gray-matter injury is also seen in this model, as well as in the fetal sheep model described by Back et al. Hippocampal damage, as well as cortical and deep gray-matter injury, is documented. Although the degree of ischemia certainly predicts gray-matter damage in the fetal sheep model, it appears that the heterogeneity seen in the periventricular white matter is more closely associated with oligodendrocyte lineage susceptibility. Therefore, it is important to get the modeling precise because the degree of injury and the age at which the insult is experienced will dictate the outcome. In a few recent studies, the degree of white-matter injury seen on early MRI in newborn humans can predict neurodevelopmental outcome in the first few years of life. A study by Shah et al showed that cerebellar volumes are smaller in preterm infants at term equivalent compared with term controls. The reduction in volume was associated with the degree of whitematter injury. Cognitive and motor developmental outcomes were principally mediated by the white-matter injury. A study by Miller et al also showed that an abnormal outcome was associated with increasing severity of white-matter injury, as well as ventriculomegaly and intraventricular hemorrhage. In the chronically instrumented fetal sheep, a number of insults can be created, such as intermittent ischemia or hypoxia, systemic hypotension, raised intracranial pressure, and even the administration of infectious agents or drugs that can disturb brain development. This capability allows for the creation of a variety of lesions that can be studied pathogenetically in greater detail. Like other models before it, this model attempts to address the complexities of the pathophysiology of white-matter injury in Received May 3, 2006. Accepted for publication May 3, 2006. Address correspondence to Dr Donna M. Ferriero, Departments of Neurology and Pediatrics, University of California-San Francisco, 513 Parnassus Avenue, C215, San Francisco, CA 94143-0663. Tel: 415-5025820; fax: 415-502-5821; e-mail: ferrierod@neuropeds.ucsf.edu. DOI 10.2310/7010.2006.00171

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.

Radial organization of developing preterm human cerebral cortex revealed by non-invasive water diffusion anisotropy MRI.

Cerebral cortical development involves a complex cascade of events which are difficult to visualize in intact, living subjects. In this study, we apply diffusion tensor imaging (DTI) to the evaluation of cortical development in human infants ranging from 26 to 41 weeks gestational age (GA). Apparent diffusion of water in cortex is maximally anisotropic at 26 weeks GA and anisotropy values approach zero by 36 weeks GA. During this period, the major eigenvector of the diffusion tensor in cerebral cortex is oriented radially across the cortical plate, in accord with a predominately radial deployment of its neuronal constituents. Values for the rotationally averaged water diffusion coefficient increase between 26 and 32 weeks GA, then decrease thereafter. These changes in DTI parameters are specific to cerebral cortex and reflect changes in underlying cortical architecture and formation of neuronal connections. Because of its correlation with tissue microstructure and non-invasive nature, DTI offers unique insight into cortical development in preterm human newborns and, potentially, detection of derangements of its basic cytoarchiteture.

Caffeine does not affect excitotoxic brain lesions in newborn mice

Caffeine is frequently administered to human pre-term newborns although its neurological impact has not been fully evaluated. In the present study performed in mice, we examined the effects of caffeine administration on neonatal excitotoxic lesions of the periventricular white matter, which mimics several aspects of human periventricular leukomalacia. In this model, caffeine exposure did not worsen white matter lesions. These data suggest that neonatal caffeine administration might not affect clastic lesions in pre-term infants.

An ultrastructural study of brown adipose tissue in pre-term human new-borns

The ultrastructure of brown adipose tissue (BAT), the thermogenic type of adipose tissue, was investigated in biopsies from 4 pre-term human new-borns delivered at 25–27 week's gestational age and compared with peri-renal brown fat from 2 adult patients with phaeochromocytoma (a condition of brown fat activation). The cell size of brown adipocytes was smaller in pre-term new-borns than in adult patients; adipocytes were almost exclusively multilocular, suggesting active thermogenesis. In 3 of the pre-term new-borns, brown adipocyte ultrastructure indicated a good to high degree of differentiation (in particular at the level of mitochondria) as compared with activated brown fat cells found in adult patients; in one pre-term infant the tissue morphology was obviously suggestive of an earlier, proliferative phase of development and the differentiation process of brown adipocytes could be traced in some detail. The results suggest that (a) brown adipose tissue may be fairly well-differentiated and thermogenetically active in pre-term human new-borns weighing about 750 g at birth; (b) brown adipocytes apparently develop from vessel-associated cells, the early signs of adipocyte differentiation being glycogen and lipid accumulation; (c) the ultrastructural morphology of mitochondria in well-differentiated BAT from pre-term infants can strictly resemble that found in active brown adipose tissue of adult phaeochromocytoma patients.