[Long-term cerebral effects of perinatal inflammation]

Long-term outcomes of very low birth weight infants with spontaneous intestinal perforation: A retrospective case-matched cohort study

BACKGROUND

Spontaneous intestinal perforation (SIP) is an intestinal complication that occurs in very ill preterms. We investigated whether SIP survivors have worse neurodevelopmental and gastrointestinal outcomes and a poorer quality of life than controls.

METHODS

A retrospective case-matched cohort study was performed involving infants treated for SIP in a NICU between August 1994 and April 2014. Controls and SIP patients were matched to gestational age, gender, and birth period. Medical records were reviewed. Telephone surveys were conducted to evaluate the medical condition, quality of life (PedsQL™ 4.0), neuropsychiatric and gastrointestinal outcome. McNemar's and Wilcoxon tests were performed, and generalized linear models were computed.

RESULTS

Forty-nine SIP patients were included. The percentages of children with multiple disabilities (40% vs. 17%, OR = 3.3) and requiring physiotherapy (86% vs. 60%, OR = 4.77) were higher in the SIP group than in the control group. Intraventricular hemorrhage (IVH) led to a worse neurodevelopmental outcome regardless of SIP (OR = 8.79 for disability), and female gender was a protective factor against disability (OR = 0.06). Reported quality of life and gastrointestinal comorbidities did not differ between the two groups.

CONCLUSION

SIP survivors tend to be at risk of multiple disabilities. IVH and female gender influence the neurodevelopmental outcome regardless of SIP.

LEVELS OF EVIDENCE

Level III: case-control study.

In utero electroporation induces cell death and alters embryonic microglia morphology and expression signatures in the developing hypothalamus

Background

Since its inception in 2001, in utero electroporation (IUE) has been widely used by the neuroscience community. IUE is a technique developed to introduce plasmid DNA into embryonic mouse brains without permanently removing the embryos from the uterus. Given that IUE labels cells that line the ventricles, including radial fibers and migrating neuroblasts, this technique is an excellent tool for studying factors that govern neural cell fate determination and migration in the developing mouse brain. Whether IUE has an effect on microglia, the immune cells of the central nervous system (CNS), has yet to be investigated.

Methods

We used IUE and the pCIG2, pCIC-Ascl1, or pRFP-C-RS expression vectors to label radial glia lining the ventricles of the embryonic cortex and/or hypothalamus. Specifically, we conducted IUE at E14.5 and harvested the brains at E15.5 or E17.5. Immunohistochemistry, along with cytokine and chemokine analyses, were performed on embryonic brains with or without IUE exposure.

Results

IUE using the pCIG2, pCIC-Ascl1, or pRFP-C-RS vectors alone altered microglia morphology, where the majority of microglia near the ventricles were amoeboid and displayed altered expression signatures, including the upregulation of Cd45 and downregulation of P2ry12. Moreover, IUE led to increases in P2ry12⁻ cells that were Iba1⁺/IgG⁺ double-positive in the brain parenchyma and resembled macrophages infiltrating the brain proper from the periphery. Furthermore, IUE resulted in a significant increase in cell death in the developing hypothalamus, with concomitant increases in cytokines and chemokines known to be released during pro-inflammatory states (IL-1β, IL-6, MIP-2, RANTES, MCP-1). Interestingly, the cortex was protected from elevated cell death following IUE, implying that microglia that reside in the hypothalamus might be particularly sensitive during embryonic development.

Conclusions

Our results suggest that IUE might have unintended consequences of activating microglia in the embryonic brain, which could have long-term effects, particularly within the hypothalamus.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1213-6) contains supplementary material, which is available to authorized users.

Temporal Characterization of Microglia/Macrophage Phenotypes in a Mouse Model of Neonatal Hypoxic-Ischemic Brain Injury

Immune cells display a high degree of phenotypic plasticity, which may facilitate their participation in both the progression and resolution of injury-induced inflammation. The purpose of this study was to investigate the temporal expression of genes associated with classical and alternative polarization phenotypes described for macrophages and to identify related cell populations in the brain following neonatal hypoxia-ischemia (HI). HI was induced in 9-day old mice and brain tissue was collected up to 7 days post-insult to investigate expression of genes associated with macrophage activation. Using cell-markers, CD86 (classic activation) and CD206 (alternative activation), we assessed temporal changes of CD11b⁺ cell populations in the brain and studied the protein expression of the immunomodulatory factor galectin-3 in these cells. HI induced a rapid regulation (6 h) of genes associated with both classical and alternative polarization phenotypes in the injured hemisphere. FACS analysis showed a marked increase in the number of CD11b⁺CD86⁺ cells at 24 h after HI (+3667%), which was coupled with a relative suppression of CD11b⁺CD206⁺ cells and cells that did not express neither CD86 nor CD206. The CD11b⁺CD206⁺ population was mixed with some cells also expressing CD86. Confocal microscopy confirmed that a subset of cells expressed both CD86 and CD206, particularly in injured gray and white matter. Protein concentration of galectin-3 was markedly increased mainly in the cell population lacking CD86 or CD206 in the injured hemisphere. These cells were predominantly resident microglia as very few galectin-3 positive cells co-localized with infiltrating myeloid cells in Lys-EGFP-ki mice after HI. In summary, HI was characterized by an early mixed gene response, but with a large expansion of mainly the CD86 positive population during the first day. However, the injured hemisphere also contained a subset of cells expressing both CD86 and CD206 and a large population that expressed neither activation marker CD86 nor CD206. Interestingly, these cells expressed the highest levels of galectin-3 and were found to be predominantly resident microglia. Galectin-3 is a protein involved in chemotaxis and macrophage polarization suggesting a novel role in cell infiltration and immunomodulation for this cell population after neonatal injury.

Placental histological examination and the relationship with oxidative stress in preterm infants

BACKGROUND

Prenatal conditions of enhanced oxidative stress (OS) linked to inflammation or hypoxia have been associated with impaired fetal growth and preterm delivery. Little is known regarding biomarkers of OS in the cord blood of preterm infants and placental histological patterns.

OBJECTIVES

To test the hypothesis that placental lesions indicating chorioamnionitis (CA) or vascular underperfusion (VU) are associated with increased OS in the offspring.

METHODS

120 neonates born below 29⁺⁶ weeks of gestational age (GA) were enrolled. Histological characteristics of placentas from their mothers were classified as normal (CTRL group), histological CA (HCA) and vascular underperfusion (VU). Serum concentrations of isoprostanes (IsoPs), non-protein bound iron (NPBI) and advanced oxidative protein products (AOPP), were determined in cord blood.

RESULTS

IsoPs, NPBI and AOPP were significantly increased in HCA group compared to CTRL group. The multivariable regression model, adjusted for GA, maternal age, parity, maternal diabetes, maternal obesity and presence/absence of fetal growth restriction (FGR), showed a significant association between the presence of HCA and increased OS biomarkers levels in cord blood (IsoPs: p = 0.006; NPBI: p = 0.014; AOPP: p = 0.007). Placental VU lesions were significantly associated with higher umbilical IsoPs, NPBI and AOPP levels (IsoPs: p = 0.008; NPBI: p = 0.002; AOPP: p = 0.040). In the cases of placental VU lesions associations were also found between high AOPP levels and low GA (p = 0.002) and the presence of fetal growth restriction (p = 0.014).

CONCLUSIONS

Placental lesions indicating inflammation or impaired perfusion are associated with higher cord blood levels of OS biomarkers explaining the fetal susceptibility to oxidative injury and the need of antioxidant protection.

Impact of inhaled nitric oxide on white matter damage in growth-restricted neonatal rats

BACKGROUND

Fetal growth restriction is the second leading cause of perinatal morbidity and mortality, and neonates with intrauterine growth retardation (IUGR) have increased neurocognitive and neuropsychiatric morbidity. These neurocognitive impairments are mainly related to injury of the developing brain associated with IUGR. Growing evidence from preclinical models of brain injury in both adult and neonatal rodents supports the view that nitric oxide can promote neuroprotection.

METHODS

In a model of IUGR induced by protracted gestational hypoxia leading to diffuse white matter injury, we subjected neonatal rats to low dose (5 ppm) but long-lasting (7 d) exposure to inhaled NO (iNO). We used a combination of techniques, including immunohistochemistry, quantitative PCR, and cognitive assessment, to assess neuroprotection.

RESULTS

Antenatal hypoxia-induced IUGR was associated with severe neuroinflammation and delayed myelination. iNO exposure during the first postnatal week significantly attenuated cell death and microglial activation, enhanced oligodendroglial proliferation and finally improved myelination. Remarkably, iNO was associated with the specific upregulation of P27kip1, which initiates oligodendrocytic differentiation. Finally, iNO counteracted the deleterious effects of hypoxia on learning abilities.

CONCLUSION

This study provides new evidence that iNO could be effective in preventing brain damage and/or enhancing repair of the developing brain.

Prevention of cerebral palsy, autism spectrum disorder, and attention deficit-hyperactivity disorder

This hypothesis states that cerebral palsy (CP), autism spectrum disorder (ASD), and attention-deficit/hyperactivity disorder (ADHD) are all caused by an exaggerated central nervous system inflammatory response to a prenatal insult. This prenatal insult may be one or more episodes of ischemia-reperfusion, an infectious disease of the mother or the fetus, or other causes of maternal inflammation such as allergy or autoimmune disease. The resultant fetal inflammatory hyper-response injures susceptible neurons in the developing white matter of the brain in specific areas at specific gestational ages. The exaggerated neuroinflammatory response is theorized to occur between about 19 and 34 post-conception weeks for CP, about 32 and 40 weeks for ADHD, and about 36 and 48 weeks (i.e. 2 months after delivery) for ASD. The exaggerated inflammatory response is hypothesized to occur because present diets limit intake of effective antioxidants and omega-3 polyunsaturated fatty acids while increasing intake of omega-6 polyunsaturated fatty acids. Oxidation products of the omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) limit neuroinflammation while oxidation products of the omega-6 fatty acid arachidonic acid exacerbate inflammation. Preventative treatment should begin in all pregnant women during the first trimester and should include both DHA and an effective antioxidant for prevention of neuroinflammation. The suggested antioxidant would be N-acetylcysteine, though melatonin could be chosen instead. Combined DHA and NAC therapy is theorized to decrease the incidence of the three disorders by more than 75%.