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Reduced Myelination and Increased Glia Reactivity Resulting from Severe Neonatal Hyperbilirubinemia.

ABSTRACT: Bilirubin-induced neurologic dysfunction (BIND) and kernicterus has been used to describe moderate to severe neurologic dysfunction observed in children exposed to excessive levels of total serum bilirubin (TSB) during the neonatal period. Here we use a new mouse model that targets deletion of the Ugt1 locus and the Ugt1a1 gene in liver to promote hyperbilirubinemia-induced seizures and central nervous system toxicity. The accumulation of TSB in these mice leads to diffuse yellow coloration of brain tissue and a marked cerebellar hypoplasia that we characterize as kernicterus. Histologic studies of brain tissue demonstrate that the onset of severe neonatal hyperbilirubinemia, characterized by seizures, leads to alterations in myelination and glia reactivity. Kernicterus presents as axonopathy with myelination deficits at different brain regions, including pons, medulla oblongata, and cerebellum. The excessive accumulation of TSB in the early neonatal period (5 days after birth) promotes activation of the myelin basic protein (Mbp) gene with an accelerated loss of MBP that correlates with a lack of myelin sheath formation. These changes were accompanied by increased astroglial and microglial reactivity, possibly as a response to myelination injury. Interestingly, cerebellum was the area most affected, with greater myelination impairment and glia burden, and showing a marked loss of Purkinje cells and reduced arborization of the remaining ones. Thus, kernicterus in this model displays not only axonal damage but also myelination deficits and glial activation in different brain regions that are usually related to the neurologic sequelae observed after severe hyperbilirubinemia.

SUBMITTER: Barateiro A

PROVIDER: S-EPMC4702100 | biostudies-literature | 2016 Jan

REPOSITORIES: biostudies-literature

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Reduced Myelination and Increased Glia Reactivity Resulting from Severe Neonatal Hyperbilirubinemia.

Barateiro Andreia A Chen Shujuan S Yueh Mei-Fei MF Fernandes Adelaide A Domingues Helena Sofia HS Relvas João J Barbier Olivier O Nguyen Nghia N Tukey Robert H RH Brites Dora D

Molecular pharmacology 20151019 1

Bilirubin-induced neurologic dysfunction (BIND) and kernicterus has been used to describe moderate to severe neurologic dysfunction observed in children exposed to excessive levels of total serum bilirubin (TSB) during the neonatal period. Here we use a new mouse model that targets deletion of the Ugt1 locus and the Ugt1a1 gene in liver to promote hyperbilirubinemia-induced seizures and central nervous system toxicity. The accumulation of TSB in these mice leads to diffuse yellow coloration of b ...[more]

PMID: 26480925

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Project description:Objective: We aimed to investigate the clinical and genetic risk factors associated with neonatal severe unconjugated hyperbilirubinemia. Methods: This was a retrospective, 1:1 matched, case-control study. We included 614 neonates diagnosed with severe unconjugated hyperbilirubinemia (serum total bilirubin level ≥425 μmol/L or serum total bilirubin concentration that met exchange transfusion criteria) from the China Neonatal Genomes Project in Children's Hospital of Fudan University. Clinical exome sequencing data were analyzed using a data analysis pipeline of Children's Hospital of Fudan University. The factors associated with severe unconjugated hyperbilirubinemia were assessed using univariable and multivariable logistic regression analyses. Interaction analyses were examined between clinical and genetic risk factors. Results: ABO/Rh incompatibility hemolysis (odds ratio [OR] 3.36, 95% confidence interval [CI] 2.32-4.86), extravascular hemorrhage (OR 2.95, 95% CI 2.24-3.89), weight loss (OR 5.46, 95% CI 2.88-10.36), exclusive breastmilk feeding (OR 3.56, 95% CI 2.71-4.68), and the homozygous mutant of UGT1A1 211G>A (OR 2.35, 95% CI 1.54-3.59) were all identified as factors significantly associated with severe unconjugated hyperbilirubinemia. The presence of UGT1A1 211G>A mildly increased the risk of severe unconjugated hyperbilirubinemia caused by ABO/Rh incompatibility hemolysis (OR 3.98, 95% CI 2.19-7.23), although the effect is not statistically significant. Conclusion: ABO/Rh incompatibility hemolysis, extravascular hemorrhage, weight loss, exclusive breastmilk feeding, and the homozygous mutant of UGT1A1 211G>A were found to be risk factors for severe unconjugated hyperbilirubinemia. Clinical factors remain the most crucial and preventable determinants in managing severe unconjugated hyperbilirubinemia, with a minimal genetic contribution. The establishment of preconception care practices and the reinforcement of screening for the aforementioned risk factors are essential steps for preventing severe unconjugated hyperbilirubinemia.

Project description:Neonatal hyperbilirubinemia (jaundice) is common in infants, with extremely preterm infants (EPT, <28 weeks gestational age) being at high risk for bilirubin-induced neurotoxicity, resulting in neurodevelopmental impairment. Hyperbilirubinemia is treated using phototherapy to lower unconjugated bilirubin levels. However, the benefits and risks of phototherapy in EPTs have not been well studied, and bilirubin at low levels may be protective as an antioxidant. Phototherapy is associated with markers of oxidative stress in the plasma, but the effects of phototherapy on the hippocampus (HPC) are not known. Bilirubin and insults associated with EPTs impair hippocampal development, a brain structure critical for cognitive function, but their underlying mechanisms remain unknown. The effects of hyperbilirubinemia and phototherapy on the HPC were studied using a Gunn rat model. Jaundiced (jj) and non-jaundiced (Nj) pups were subjected to phototherapy from postnatal day 4 (P4) through P6. The HPC was harvested and processed for RNA sequencing. Serum bilirubin levels were elevated in jj compared to Nj control rats. Phototherapy significantly lowered serum bilirubin levels in jj rats. Compared to Nj rats, 1294 genes were differentially expressed in the jj hippocampal transcriptome and mapped onto the nervous system development, inflammation, and ferroptosis signaling pathways. Phototherapy induces 3297 differentially-expressed genes (DEGs) in rat hippocampal transcriptome compared to untreated rats. These DEGs were annotated to pathways regulating synaptogenesis, long-term potentiation, and neurogenesis. Both hyperbilirubinemia and phototherapy altered expression of 407 genes, which mapped onto hippocampal plasticity functions, including neuritogenesis and long-term potentiation. Our study demonstrates a model for investigating molecular effects of hyperbilirubemia and phototherapy in an EPT-equivalent Gunn rat pup. Our data revealed the effects of hyperbilirubinemia and phototherapy on signaling pathways critical for hippocampal development and plasticity.

Project description:IntroductionSevere hyperbilirubinaemia in newborns can be easily complicated by acute bilirubin encephalopathy or even kernicterus, which could lead to neurological sequelae or death. However, there is no systematic study of the management of severe hyperbilirubinaemia in China. The Neonatal Severe Hyperbilirubinemia Online Registry study aims to investigate the management of jaundice before admission, risk factors and outcomes of severe hyperbilirubinaemia in a real-world setting in China.Methods and analysisThis is a prospective, multicentre, open, observational cohort study. From May 2020 to April 2023, more than 2000 patients with neonatal severe hyperbilirubinaemia from 13 tertiary hospitals in Jiangsu Province will join the study. Demographic data and treatment information will be collected from their clinical data. Management measures for jaundice before admission will be collected by the WeChat applet (called 'Follow-up of jaundice') after being provided by the patient's guardian using a mobile phone. Follow-up data will include cranial MRI examination results, brainstem auditory-evoked potential or automatic auditory brainstem response, physical examination results and Griffiths Development Scales-Chinese at the corrected ages of 3-6 months and 1 and 2 years. Results and conclusions will be recorded using 'Follow-up of jaundice.' In-hospital outcomes, including severity of hyperbilirubinaemia (severe, extreme, hazardous), acute bilirubin encephalopathy (mild, moderate, severe) and survival status (death or survival), will be collected at discharge. Follow-up outcomes will include loss to follow-up, survival status and kernicterus (yes or no) at 2 years. The research will enhance our comprehensive knowledge of jaundice management before admission, risk factors and outcomes of severe hyperbilirubinaemia in China, which will ultimately help to reduce the incidence of neonatal severe hyperbilirubinaemia.Ethics and disseminationOur protocol has been approved by the Medical Ethics Committee of Nanjing Maternity and Child Health Care Hospital. We will present our findings at national conferences and peer-reviewed paediatrics journals.Trial registration numberNCT04251286.

Project description:BACKGROUND:Available evidence suggests that low- and middle-income countries (LMICs) bear the greatest burden of severe neonatal hyperbilirubinemia characterized by disproportionately high rates of morbidity, mortality and neurodevelopmental disorders compared to high-income countries. We set out to identify the risk factors that contribute to the burden of severe hyperbilirubinemia in the most developmentally disadvantaged LMICs to highlight areas for action and further research. METHODS:We systematically searched PubMed, Scopus, Ovid EMBASE, Cumulative Index to Nursing and Allied Health Literature (CINAHL), WHO Library Database (WHOLIS), African Index Medicus (AIM), African Journals Online (AJOL), LILACS, and IndMed for reports published between January 1990 and June 2014. We included only studies that controlled for the effects of confounding variables in determining maternal and infant risk factors for severe hyperbilirubinemia. We conducted meta-analysis of the eligible studies and computed the summary risk estimates with random effects models. RESULTS:A total of 13 studies with 1,951 subjects and 32,208 controls from India, Nigeria, Pakistan, Nepal and Egypt were identified and analyzed. The pooled data showed that primiparity (OR, 1.59; 95% CI:1.26-2.00), delivery outside public hospitals (OR, 6.42; 95% CI:1.76-23.36), ABO incompatibility (OR, 4.01; 95% CI:2.44-6.61), Rhesus hemolytic disease (OR, 20.63; 95% CI:3.95-107.65), G6PD deficiency (OR, 8.01; 95% CI:2.09-30.69), UGT1A1 polymorphisms (OR, 4.92; 95% CI:1.30-18.62), low gestational age (OR, 1.71; 95% CI:1.40-2.11), underweight/weight loss (OR, 6.26; 95% CI:1.23-31.86), sepsis (OR, 9.15; 95% CI:2.78-30.10) and high transcutaneous/total serum bilirubin levels (OR, 1.46; 95% CI:1.10-1.92) placed infants at increased risk of severe hyperbilirubinemia or bilirubin induced neurologic dysfunctions. Low social class was not associated with an increased risk of severe hyperbilirubinemia. CONCLUSIONS:Infants at risk of severe hyperbilirubinemia in LMICs are associated with maternal and neonatal factors that can be effectively addressed by available interventions to curtail the disease burden prevailing in the affected countries.

Dataset Information

Reduced Myelination and Increased Glia Reactivity Resulting from Severe Neonatal Hyperbilirubinemia.

Publications

Reduced Myelination and Increased Glia Reactivity Resulting from Severe Neonatal Hyperbilirubinemia.

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