Long-Term Neurologic Consequences following Fetal Growth Restriction: The Impact on Brain Reserve.

BACKGROUND: Fetal growth restriction (FGR) corresponds to the fetus's inability to achieve an adequate weight gain based on genetic potential and gestational age. It is an important cause of morbidity and mortality. SUMMARY: In this review, we address the challenges of diagnosis and classification of FGR. We review how chronic fetal hypoxia impacts brain development. We describe recent advances on placental and fetal brain imaging using magnetic resonance imaging and how they offer new noninvasive means to study growth restriction in humans. We go on to review the impact of FGR on brain integrity in the neonatal period, later childhood, and adulthood and review available therapies. KEY MESSAGES: FGR consequences are not limited to the perinatal period. We hypothesize that impaired brain reserve, as defined by structure and size, may predict some concerning epidemiological data of impaired cognitive outcomes and dementia with aging in this group of patients.

A systematic review of immune-based interventions for perinatal neuroprotection: closing the gap between animal studies and human trials.

BACKGROUND: Perinatal infection/inflammation is associated with a high risk for neurological injury and neurodevelopmental impairment after birth. Despite a growing preclinical evidence base, anti-inflammatory interventions have not been established in clinical practice, partly because of the range of potential targets. We therefore systematically reviewed preclinical studies of immunomodulation to improve neurological outcomes in the perinatal brain and assessed their therapeutic potential. METHODS: We reviewed relevant studies published from January 2012 to July 2023 using PubMed, Medline (OvidSP) and EMBASE databases. Studies were assessed for risk of bias using the SYRCLE risk of bias assessment tool (PROSPERO; registration number CRD42023395690). RESULTS: Forty preclinical publications using 12 models of perinatal neuroinflammation were identified and divided into 59 individual studies. Twenty-seven anti-inflammatory agents in 19 categories were investigated. Forty-five (76%) of 59 studies reported neuroprotection, from all 19 categories of therapeutics. Notably, 10/10 (100%) studies investigating anti-interleukin (IL)-1 therapies reported improved outcome, whereas half of the studies using corticosteroids (5/10; 50%) reported no improvement or worse outcomes with treatment. Most studies (49/59, 83%) did not control core body temperature (a known potential confounder), and 25 of 59 studies (42%) did not report the sex of subjects. Many studies did not clearly state whether they controlled for potential study bias. CONCLUSION: Anti-inflammatory therapies are promising candidates for treatment or even prevention of perinatal brain injury. Our analysis highlights key knowledge gaps and opportunities to improve preclinical study design that must be addressed to support clinical translation.

Asphyxiated Neonates Treated with Hypothermia: Birth Place Matters.

OBJECTIVE: This study aimed to assess whether the hospital level of care where asphyxiated neonates treated with hypothermia were originally born influences their outcome. STUDY DESIGN: We conducted a retrospective cohort study of all asphyxiated neonates treated with hypothermia in a large metropolitan area. Birth hospitals were categorized based on provincially predefined levels of care. Primary outcome was defined as death and/or brain injury on brain magnetic resonance imaging (adverse outcome) and was compared according to the hospital level of care. RESULTS: The overall incidence of asphyxiated neonates treated with hypothermia significantly decreased as hospital level of care increased: 1 per 1,000 live births (109/114,627) in level I units; 0.9 per 1,000 live births (73/84,890) in level II units; and 0.7 per 1,000 live births (51/71,093) in level III units (p < 0.001). The rate of emergent cesarean sections and the initial pH within the first hour of life were significantly lower in level I and level II units compared with level III units (respectively, p < 0.001 and p = 0.002). In a multivariable analysis adjusting for the rates of emergent cesarean sections and initial pH within the first hour of life, being born in level I units was confirmed as an independent predictor of adverse outcome (adjusted odds ratio [OR] level I vs. level III 95% confidence interval [CI]: 2.13 [1.02-4.43], p = 0.04) and brain injury (adjusted OR level I vs. level III 95% CI: 2.41 [1.12-5.22], p = 0.02). CONCLUSION: Asphyxiated neonates born in level I units and transferred for hypothermia treatment were less often born by emergent cesarean sections, had worse pH values within the first hour of life, and had a higher incidence of adverse outcome and brain injury compared with neonates born in level III units. Further work is needed to optimize the initial management of these neonates to improve outcomes, regardless of the location of their hospital of birth. KEY POINTS: · The incidence of asphyxiated neonates treated with hypothermia varied by hospital level of care.. · Their rates of emergent cesarean sections and their initial pH within the first hour of life varied by hospital level of care.. · The hospital level of care was an independent predictor of their adverse outcome, defined as death and/or brain injury on brain MRI..

Alteration of the brain methylation landscape following postnatal inflammatory injury in rat pups.

Preterm infants are vulnerable to inflammation-induced white matter injury (WMI), which is associated with neurocognitive impairment and increased risk of neuropsychiatric diseases in adulthood. Epigenetic mechanisms, particularly DNA methylation, play a role in normal development and modulate the response to pathological challenges. Our aims were to determine how WMI triggered DNA methylation alterations in brains of neonatal rats and if such changes persisted over time. We used a robust model of WMI by injecting lipopolysaccharide (LPS) or sterile saline in the corpus callosum of 3-day-old (P3) rat pups. Brains were collected 24 hours (P4) and 21 days post-injection (P24). We extracted genomic DNA from the brain to establish genome-wide quantitative DNA methylation profiles using reduced representation bisulfite sequencing. Neonatal LPS exposure induced a persistent increased methylation of genes related to nervous system development and a reduced methylation of genes associated with inflammatory pathways. These findings suggest that early-life neuroinflammatory exposure impacts the cerebral methylation landscape with determining widespread epigenetic modifications especially in genes related to neurodevelopment.

Supervised machine learning quality control for magnetic resonance artifacts in neonatal data sets.

Quality control (QC) of brain magnetic resonance images (MRI) is an important process requiring a significant amount of manual inspection. Major artifacts, such as severe subject motion, are easy to identify to naïve observers but lack automated identification tools. Clinical trials involving motion-prone neonates typically pool data to obtain sufficient power, and automated quality control protocols are especially important to safeguard data quality. Current study tested an open source method to detect major artifacts among 2D neonatal MRI via supervised machine learning. A total of 1,020 two-dimensional transverse T2-weighted MRI images of preterm newborns were examined and classified as either QC Pass or QC Fail. Then 70 features across focus, texture, noise, and natural scene statistics categories were extracted from each image. Several different classifiers were trained and their performance was compared with subjective rating as the gold standard. We repeated the rating process again to examine the stability of the rating and classification. When tested via 10-fold cross validation, the random undersampling and adaboost ensemble (RUSBoost) method achieved the best overall performance for QC Fail images with 85% positive predictive value along with 75% sensitivity. Similar classification performance was observed in the analyses of the repeated subjective rating. Current results served as a proof of concept for predicting images that fail quality control using no-reference objective image features. We also highlighted the importance of evaluating results beyond mere accuracy as a performance measure for machine learning in imbalanced group settings due to larger proportion of QC Pass quality images.

Assessing therapeutic response non-invasively in a neonatal rat model of acute inflammatory white matter injury using high-field MRI.

Perinatal infection and inflammatory episodes in preterm infants are associated with diffuse white matter injury (WMI) and adverse neurological outcomes. Inflammation-induced WMI was previously shown to be linked with later hippocampal atrophy as well as learning and memory impairments in preterm infants. Early evaluation of injury load and therapeutic response with non-invasive tools such as multimodal magnetic resonance imaging (MRI) would greatly improve the search of new therapeutic approaches in preterm infants. Our aim was to evaluate the potential of multimodal MRI to detect the response of interleukin-1 receptor antagonist (IL-1Ra) treatment, known for its neuroprotective properties, during the acute phase of injury on a model of neonatal WMI. Rat pups at postnatal day 3 (P3) received intracerebral injection of lipopolysaccharide with systemic IL-1Ra therapy. 24 h later (P4), rats were imaged with multimodal MRI to assess microstructure by diffusion tensor imaging (DTI) and neurochemical profile of the hippocampus with 1H-magnetic resonance spectroscopy. Astrocyte and microglial activation, apoptosis and the mRNA expression of pro-inflammatory and necroptotic markers were assessed. During the acute phase of injury, neonatal LPS exposure altered the concentration of hippocampus metabolites related to neuronal integrity, neurotransmission and membrane integrity and induced diffusivity restriction. Just 24 h after initiation of therapy, early indication of IL-1Ra neuroprotective effect could be detected in vivo by non-invasive spectroscopy and DTI, and confirmed with immunohistochemical evaluation and mRNA expression of inflammatory markers and cell death. In conclusion, multimodal MRI, particularly DTI, can detect not only injury but also the acute therapeutic effect of IL-1Ra suggesting that MRI could be a useful non-invasive tool to follow, at early time points, the therapeutic response in preterm infants.

Persistent reduction in sialylation of cerebral glycoproteins following postnatal inflammatory exposure.

BACKGROUND: The extension of sepsis encompassing the preterm newborn's brain is often overlooked due to technical challenges in this highly vulnerable population, yet it leads to substantial long-term neurodevelopmental disabilities. In this study, we demonstrate how neonatal neuroinflammation following postnatal E. coli lipopolysaccharide (LPS) exposure in rat pups results in persistent reduction in sialylation of cerebral glycoproteins. METHODS: Male Sprague-Dawley rat pups at postnatal day 3 (P3) were injected in the corpus callosum with saline or LPS. Twenty-four hours (P4) or 21 days (P24) following injection, brains were extracted and analyzed for neuraminidase activity and expression as well as for sialylation of cerebral glycoproteins and glycolipids. RESULTS: At both P4 and P24, we detected a significant increase of the acidic neuraminidase activity in LPS-exposed rats. It correlated with significantly increased neuraminidase 1 (Neu1) mRNA in LPS-treated brains at P4 and with neuraminidases 1 and 4 at P24 suggesting that these enzymes were responsible for the rise of neuraminidase activity. At both P4 and P24, sialylation of N-glycans on brain glycoproteins decreased according to both mass-spectrometry analysis and lectin blotting, but the ganglioside composition remained intact. Finally, at P24, analysis of brain tissues by immunohistochemistry showed that neurons in the upper layers (II-III) of somatosensory cortex had a reduced surface content of polysialic acid. CONCLUSIONS: Together, our data demonstrate that neonatal LPS exposure results in specific and sustained induction of Neu1 and Neu4, causing long-lasting negative changes in sialylation of glycoproteins on brain cells. Considering the important roles played by sialoglycoproteins in CNS function, we speculate that observed re-programming of the brain sialome constitutes an important part of pathophysiological consequences in perinatal infectious exposure.

Choroidal Involution Is Associated with a Progressive Degeneration of the Outer Retinal Function in a Model of Retinopathy of Prematurity: Early Role for IL-1ß.

Retinopathy of prematurity (ROP), the most common cause of blindness in premature infants, has long been associated with inner retinal alterations. However, recent studies reveal outer retinal dysfunctions in patients formerly afflicted with ROP. We have recently demonstrated that choroidal involution occurs early in retinopathy. Herein, we investigated the mechanisms underlying the choroidal involution and its long-term impact on retinal function. An oxygen-induced retinopathy (OIR) model was used. In vitro and ex vivo assays were applied to evaluate cytotoxic effects of IL-1ß on choroidal endothelium. Electroretinogram was used to evaluate visual function. We found that proinflammatory IL-1ß was markedly increased in retinal pigment epithelium (RPE)/choroid and positively correlated with choroidal degeneration in the early stages of retinopathy. IL-1ß was found to be cytotoxic to choroid in vitro, ex vivo, and in vivo. Long-term effects on choroidal involution included a hypoxic outer neuroretina, associated with a progressive loss of RPE and photoreceptors, and visual deterioration. Early inhibition of IL-1ß receptor preserved choroid, decreased subretinal hypoxia, and prevented RPE/photoreceptor death, resulting in life-long improved visual function in IL-1 receptor antagonist-treated OIR animals. Together, these findings suggest a critical role for IL-1ß-induced choroidal degeneration in outer retinal dysfunction. Neonatal therapy using IL-1 receptor antagonist preserves choroid and prevents protracted outer neuroretinal anomalies in OIR, suggesting IL-1ß as a potential therapeutic target in ROP.

User-independent diffusion tensor imaging analysis pipelines in a rat model presenting ventriculomegalia: A comparison study.

Automated analysis of diffusion tensor imaging (DTI) data is an appealing way to process large datasets in an unbiased manner. However, automation can sometimes be linked to a lack of interpretability. Two whole-brain, automated and voxelwise methods exist: voxel-based analysis (VBA) and tract-based spatial statistics (TBSS). In VBA, the amount of smoothing has been shown to influence the results. TBSS is free of this step, but a projection procedure is introduced to correct for residual misalignments. This projection assigns the local highest fractional anisotropy (FA) value to the mean FA skeleton, which represents white matter tract centers. For both methods, the normalization procedure has a major impact. These issues are well documented in humans but, to our knowledge, not in rodents. In this study, we assessed the quality of three different registration algorithms (ANTs SyN, DTI-TK and FNIRT) using study-specific templates and their impact on automated analysis methods (VBA and TBSS) in a rat pup model of diffuse white matter injury presenting large unilateral deformations. VBA and TBSS results were stable and anatomically coherent across the three pipelines. For VBA, in regions around the large deformations, interpretability was limited because of the increased partial volume effect. With TBSS, two of the three pipelines found a significant decrease in axial diffusivity (AD) at the known injury site. These results demonstrate that automated voxelwise analyses can be used in an animal model with large deformations.

Neonatal microglia: The cornerstone of brain fate.

Microglia, mainly known for their role in innate immunity and modulation of neuroinflammation, play an active role in central nervous system development and homeostasis. Depending on the context and environmental stimuli, microglia adopt a broad spectrum of activation status from pro-inflammatory, associated with neurotoxicity, to anti-inflammatory linked to neuroprotection. Pro-inflammatory microglial activation is a key hallmark of white matter injury in preterm infants and is involved in developmental origin of adult neurological diseases. Characterization of neonatal microglia function in brain development and inflammation has allowed the investigation of promising therapeutic targets with potential long-lasting neuroprotective effects. True prevention of neuro-degenerative diseases might eventually occur as early as the perinatal period.

New means to assess neonatal inflammatory brain injury.

Preterm infants are especially vulnerable to infection-induced white matter injury, associated with cerebral palsy, cognitive and psychomotor impairment, and other adverse neurological outcomes. The etiology of such lesions is complex and multifactorial. Furthermore, timing and length of exposure to infection also influence neurodevelopmental outcomes. Different mechanisms have been posited to mediate the observed brain injury including microglial activation followed by subsequent release of pro-inflammatory species, glutamate-induced excitotoxicity, and vulnerability of developing oligodendrocytes to cerebral insults. The prevalence of such neurological impairments requires an urgent need for early detection and effective neuroprotective strategies. Accordingly, noninvasive methods of monitoring disease progression and therapy effectiveness are essential. While diagnostic tools using biomarkers from bodily fluids may provide useful information regarding potential risks of developing neurological diseases, the use of magnetic resonance imaging/spectroscopy has emerged as a promising candidate for such purpose. Various pharmacological agents have demonstrated protective effects in the immature brain in animal models; however, few studies have progressed to clinical trials with promising results.

Definition and quantification of acute inflammatory white matter injury in the immature brain by MRI/MRS at high magnetic field.

BACKGROUND: Lipopolysaccharide (LPS) injection in the corpus callosum (CC) of rat pups results in diffuse white matter injury similar to the main neuropathology of preterm infants. The aim of this study was to characterize the structural and metabolic markers of acute inflammatory injury by high-field magnetic resonance imaging (MRI) magnetic resonance spectroscopy (MRS) in vivo. METHODS: Twenty-four hours after a 1-mg/kg injection of LPS in postnatal day 3 rat pups, diffusion tensor imaging and proton nuclear magnetic spectroscopy ((1)H NMR) were analyzed in conjunction to determine markers of cell death and inflammation using immunohistochemistry and gene expression. RESULTS: MRI and MRS in the CC revealed an increase in lactate and free lipids and a decrease of the apparent diffusion coefficient. Detailed evaluation of the CC showed a marked apoptotic response assessed by fractin expression. Interestingly, the degree of reduction in the apparent diffusion coefficient correlated strongly with the natural logarithm of fractin expression, in the same region of interest. LPS injection further resulted in increased activated microglia clustered in the cingulum, widespread astrogliosis, and increased expression of genes for interleukin (IL)-1, IL-6, and tumor necrosis factor. CONCLUSION: This model was able to reproduce the typical MRI hallmarks of acute diffuse white matter injury seen in preterm infants and allowed the evaluation of in vivo biomarkers of acute neuropathology after inflammatory challenge.

Severe central nervous system demyelination in Sanfilippo disease.

Introduction: Chronic progressive neuroinflammation is a hallmark of neurological lysosomal storage diseases, including mucopolysaccharidosis III (MPS III or Sanfilippo disease). Since neuroinflammation is linked to white matter tract pathology, we analyzed axonal myelination and white matter density in the mouse model of MPS IIIC HgsnatP304L and post-mortem brain samples of MPS III patients. Methods: Brain and spinal cord tissues of human MPS III patients, 6-month-old HgsnatP304L mice and age- and sex-matching wild type mice were analyzed by immunofluorescence to assess levels of myelin-associated proteins, primary and secondary storage materials, and levels of microgliosis. Corpus callosum (CC) region was studied by transmission electron microscopy to analyze axon myelination and morphology of oligodendrocytes and microglia. Mouse brains were analyzed ex vivo by high-filed MRI using Diffusion Basis Spectrum Imaging in Python-Diffusion tensor imaging algorithms. Results: Analyses of CC and spinal cord tissues by immunohistochemistry revealed substantially reduced levels of myelin-associated proteins including Myelin Basic Protein, Myelin Associated Glycoprotein, and Myelin Oligodendrocyte Glycoprotein. Furthermore, ultrastructural analyses revealed disruption of myelin sheath organization and reduced myelin thickness in the brains of MPS IIIC mice and human MPS IIIC patients compared to healthy controls. Oligodendrocytes (OLs) in the CC of MPS IIIC mice were scarce, while examination of the remaining cells revealed numerous enlarged lysosomes containing heparan sulfate, GM3 ganglioside or "zebra bodies" consistent with accumulation of lipids and myelin fragments. In addition, OLs contained swollen mitochondria with largely dissolved cristae, resembling those previously identified in the dysfunctional neurons of MPS IIIC mice. Ex vivo Diffusion Basis Spectrum Imaging revealed compelling signs of demyelination (26% increase in radial diffusivity) and tissue loss (76% increase in hindered diffusivity) in CC of MPS IIIC mice. Discussion: Our findings demonstrate an important role for white matter injury in the pathophysiology of MPS III. This study also defines specific parameters and brain regions for MRI analysis and suggests that it may become a crucial non-invasive method to evaluate disease progression and therapeutic response.

In vivo assessment of myelination by phase imaging at high magnetic field.

The present study evaluated the potential of using the phase of T2* weighted MR images to characterize myelination during brain development and pathology in rodents at 9.4 T. Phase contrast correlated with myelin content assessed by histology and suggests that most contrast between white and cortical gray matter is modulated by myelin. Ex vivo experiments showed that gray-white matter phase contrast remains unchanged after iron extraction. In dysmyelinated shiverer mice, phase imaging correlated strongly with myelin staining, showing reduced contrast between white and gray matter when compared to healthy controls. We conclude that high-resolution phase images, acquired at high field, allow assessment of myelination and dysmyelination.

Delayed cortical impairment following lipopolysaccharide exposure in preterm fetal sheep.

OBJECTIVE: Preterm infants exhibit chronic deficits in white matter (WM) and cortical maturation. Although fetal infection/inflammation may contribute to WM pathology, the factors contributing to cortical changes are largely unknown. We examined the effect of fetal lipopolysaccharide (LPS) exposure on WM and cortical development as assessed by magnetic resonance imaging (MRI), electroencephalography (EEG), and histopathology in fetal sheep at preterm human equivalent age. METHODS: LPS was administered to fetal sheep at 102.5 ± 0.5 days of gestation. Continuous biophysical recordings were analyzed for 10 days after LPS. At postmortem, measurement of cerebral WM and cortical tissue volumes was achieved by stereological techniques. Specific effects of LPS on MRI-assessed T(1)-weighted and T(2)-weighted images, and immunohistochemical expression of oligodendrocytes, proliferating cells, cortical NeuN-positive and Nurr1-positive neurons (subplate marker), and cell death mechanisms were examined. RESULTS: We observed reductions in WM (~21%; LPS, 1.19 ± 0.04 vs control, 1.51 ± 0.07 cm(3); p < 0.001) and cortical (~18%; LPS, 2.34 ± 0.10 vs control, 2.85 ± 0.07 cm(3); p < 0.001) volumes, associated with overt and diffuse WM injury, T(1)-/T(2) -weighted signal alterations, and reduced numbers of WM oligodendrocytes (LPS, 485 ± 31 vs control, 699 ± 69 cells/mm(2); p = 0.0189) and NeuN-positive (LPS, 421 ± 71 vs control 718 ± 92 cells/mm(2); p = 0.04) and Nurr1-positive (control, 2.5 ± 0.6 vs LPS, 0.6 ± 0.1 cells/mm(2); p = 0.007) cortical neurons after LPS. Moreover, there was loss of the normal maturational increase in cortical EEG amplitude, which correlated with reduced cortical volumes. INTERPRETATION: Fetal exposure to LPS prior to myelination onset can impair both white matter and cortical development in a preclinical large animal model, supporting a role for maternal/fetal infection in the pathogenesis of preterm brain injury.

High-field diffusion tensor imaging characterization of cerebral white matter injury in lipopolysaccharide-exposed fetal sheep.

BACKGROUND: In gyrencephalic species such as sheep, precise anatomical and microstructural characterization of the consequences of fetal inflammation remains scarce. The goal of this study was to characterize changes in white matter (WM) structure using advanced magnetic resonance imaging (MRI) following lipopolysaccharide (LPS) exposure in the preterm-equivalent fetal sheep. METHODS: Preterm (0.7 gestation) fetal sheep received vehicle (Sham group) or LPS (LPS group), and fetal brains were collected 10 d later for subsequent ex vivo MRI. T1-weighted (T(1)W), T2-weighted (T(2)W), and diffusion tensor imaging (DTI) data were collected. RESULTS: Fetuses exposed to LPS exhibited reductions in WM volume and corpus callosum thickness at 10 d recovery. Characteristic patterns of diffuse and focal WM lesions (necrosis or cysts) could be identified by various T1, T2, and DTI signal changes. CONCLUSION: Fetal LPS exposure induces a pattern of injury characterized by diffuse and focal WM injury that closely reproduces that observed clinically in preterm infants. This work provides anatomical and microstructural MRI assessment, as well as histopathological correlates, of the consequences of LPS exposure in an animal model with a WM structure similar to that of the human brain. This work will help to further our understanding of MRI changes in preterm infants.

Non-invasive in vivo MRI detects long-term microstructural brain alterations related to learning and memory impairments in a model of inflammation-induced white matter injury.

Magnetic resonance imaging (MRI) is currently under investigation as a non-invasive tool to monitor neurodevelopmental trajectories and predict risk of cognitive deficits following white matter injury (WMI) in very preterm infants. In the present study, we evaluated the capacity of multimodal MRI (high-resolution T2-weighted imaging and diffusion tensor imaging)to assess changes following WMI and their relationship to learning and memory performance in Wistar rats as it has been demonstrated for preterm infants. Multimodal MRI performed at P31-P32 shown that animals exposed to neonatal LPS could be classified into two groups: minimal and overt injury. Animals with overt injury had significantly enlarged ventricles, hippocampal atrophy, diffusivity changes in hippocampal white and gray matter, in the striatum and the cortex. Following neonatal LPS exposure, animals presented learning and memory impairments as shown at the fear conditioning test at P36-P38. The severity of learning and memory deficits was related to increased mean diffusivity in the hippocampal region. In conclusion, non-invasive multimodal MRI (volumetric and DTI) assessed and classified the extent of injury at long-term following neonatal LPS exposure. Microstructural changes in the hippocampus at DTI were associated to learning and memory impairments. This further highlights the utility of multimodal MRI as a non-invasive quantitative biomarker following perinatal inflammation.

Modulatory effect of IL-1 inhibition following lipopolysaccharide-induced neuroinflammation in neonatal microglia and astrocytes.

INTRODUCTION: Inflammation-induced white matter injury (WMI) in preterm infants is characterized by microglia activation, astrogliosis, oxidative stress and neurodevelopmental impairments. Microglia and astrocytes activation can be described under a broad spectrum of activation profile with extremes described as pro-inflammatory/neurotoxic (M1 microglia or A1 astrocyte) or anti-inflammatory/neuroprotective (M2 microglia or A2 astrocyte) in response to stimuli including lipopolysaccharide (LPS) and interleukin 1 (IL-1). As IL-1 signalling pathway has been posited as a major driver of inflammation-induced perinatal WMI, our aim was to evaluate the contribution of IL-1 modulation in LPS-induced microglia and astrocyte activation. METHODS: Primary neonatal cell co-cultures of astrocytes and microglia were treated with LPS (100 ng/ml) for 8 h or 24 h. Two distinct IL-1 receptor antagonists, Rytvela or Kineret (1 µg/ml), were added simultaneously with LPS to respectively modulate or block IL-1 receptor. Medium was collected to measure levels of IL-1ß. Expression of markers related to pro- and anti-inflammatory microglia and astrocyte activation profiles and antioxidant genes were assessed. RESULTS: At 8 h, LPS exposure induced pro- (M1/A1) and anti-inflammatory (M2/A2) marker expression and inhibited antioxidant gene expression in microglia and astrocytes. By 24 h, continuous LPS exposure increased pro-inflammatory and neurotoxic microglial and astrocytic markers (M1/A1), as well as antioxidant genes. Administration of IL-1 antagonists Rytvela and Kineret with continuous LPS exposure had no significant effect on modulation of specific microglia and astrocyte activation pathways. DISCUSSION/CONCLUSION: We show that LPS effects on in vitro neonatal microglia and astrocytes co-cultures are time dependent eliciting a number of pro- and anti-inflammatory responses during the acute phase of inflammation (8 h), which shift towards pro-inflammatory and neurotoxic factors by 24 h. Although LPS-induced inflammation led to abundant IL-1 expression, IL-1 inhibition had no significant impact on in vitro modulation of microglia and astrocyte activation pathways towards M2 and A2 activation profile.

Self-healing, stretchable, and highly adhesive hydrogels for epidermal patch electrodes.

Flexible, self-healing and adhesive conductive materials with Young's modulus matching biological tissues are highly desired for applications in bioelectronics. Here, we report self-healing, stretchable, highly adhesive and conductive hydrogels obtained by mixing polyvinyl alcohol, sodium tetraborate and a screen printing paste containing the conducting polymer Poly (3,4-ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT:PSS) and diol additives. The as prepared hydrogels exhibited modelling ability, high adhesion on pig skin (1.96 N/cm2), high plastic stretchability (>10000%), a moderate conductivity, a low compressive modulus (0.3-3.7 KPa), a good strain sensitivity (gauge factor = 3.88 at 500% strain), and remarkable self-healing properties. Epidermal patch electrodes prepared using one of our hydrogels demonstrated high-quality recording of electrocardiography (ECG) and electromyography (EMG) signal. Because of their straightforward fabrication, outstanding mechanical properties and possibility to combine the electrode components in a single material, hydrogels based on PVA, borax and PEDOT:PSS are highly promising for applications in bioelectronics and wearable electronics. STATEMENT OF SIGNIFICANCE: Soft materials with electrical conductivity are investigated for healthcare applications, such as electrodes to measure vital signs that can easily adapt to the shape and the movements of human skin. Conductive hydrogels (i.e. gels containing water) are ideal materials for this purpose due softness and flexibility. In this this work, we report hydrogels obtained mixing an electrically conductive polymer, a water-soluble biocompatible polymer and a salt. These materials show high adhesion on skin, electrical conductivity and ability to self-repair after a mechanical damage. These hydrogels were successfully used to fabricate electrode to measure cardiac and muscular electrical signals.

Diffusion characteristics associated with neuronal injury and glial activation following hypoxia-ischemia in the immature brain.

To identify quantitative MRI indices of injury in the brain following neonatal hypoxic-ischemic brain injury, we subjected mouse pups to hypoxia-ischemia on postnatal day 7 and obtained conventional and diffusion-weighted in vivo images of the brain 24 h later followed by histological assessment. T(2)-weighted images showed increased signal intensity in the CA1 and CA2 regions of the hippocampus ipsilateral to the injury and adjacent white matter. In contrast, diffusion imaging showed reduced apparent diffusion coefficient (ADC) values in CA1 and CA2, but increased values in the adjacent white matter. Histological analysis showed widespread gliosis with degenerating oligodendrocytes in the ipsilateral hippocampus. In addition, white matter areas that were abnormal by MRI showed an increase in the number of activated microglia (CD45 positive cells). Activated caspase-3 immunostaining showed a marked increase in neurons in the hippocampal regions corresponding to those with reduced ADC, and a quantitative measure of staining showed a statistically significant correlation with the ADC. In contrast, ADC was higher in adjacent white matter, where histology showed activation of microglia and reactive oligodendrocytes but not caspase-3 activation. These results suggest that the ADC response differs between areas of neuronal injury as compared with those showing glial changes without marked cell death.