Bilirubin-induced Brain Injury Research Articles

Dynamic whole-transcriptome landscape of acute bilirubin encephalopathy in newborns

Hyperbilirubinemia in newborns may progress to acute bilirubin encephalopathy (ABE), posing short- and long-term health risks. Despite extensive research identifying numerous mRNAs, lncRNAs, circRNAs, and miRNAs associated with brain injury, their roles in neonatal bilirubin-induced brain injury remain elusive. This study employed whole-transcriptome sequencing to ascertain the differentially expressed (DE) RNA profiles in a newborn ABE rat model, followed by bioinformatic analysis. A time-series competing endogenous RNA (ceRNA) regulatory network was established, and the expression trends of 9 arbitrarily chosen RNAs were verified through quantitative real-time polymerase chain reaction(qRT-PCR). In comparison with the control group, we identified 595, 888, and 1448 DE mRNAs; 22, 37, and 37 DE miRNAs; 1945, 1869, and 1997 DE lncRNAs; and 31, 28, and 36 DE circRNAs at 6 h, 12 h, and 24 h, respectively. Predominantly, these DERNAs contribute to biological functions and pathways associated with inflammation, immunity, metabolism, cell death, and neurodevelopmental regulation. Moreover, we constructed ceRNA networks of DE lncRNA/circRNA-DE miRNA-DE mRNA based on time series. The qRT-PCR expression trends for the selected 9 RNAs were generally similar to the RNA-seq outcomes. This investigation uniquely delineated the temporal expression patterns of mRNA and non-coding RNA in ABE, establishing ceRNA networks and identifying potential molecular mechanisms underlying bilirubin-induced hippocampal damage. Nonetheless, further studies are warranted to corroborate these findings in humans.

Docosahexaenoic Acid Supplementation for Neonatal Hyperbilirubinemia: A Double-Blind, Randomized Clinical Trial.

Docosahexaenoic acid (DHA) is an essential component for brain development during fetal and early postnatal life. Hyperbilirubinemia is characterized by abnormally high levels of bilirubin in the bloodstream, frequently leading to jaundice in newborns. In severe instances, this condition can progress to neurological damage or kernicterus, a form of brain damage. Initial cell-based experiments conducted by our research team revealed that DHA significantly enhances the survival rate of nerve cells treated with bilirubin and diminishes the oxidative stress indicated by reduced peroxide activity caused by unconjugated bilirubin (UCB). Further investigations through animal studies demonstrated that DHA effectively mitigates bilirubin-induced brain injury in neonatal rats. However, the potential of DHA to decrease the incidence of bilirubin-induced brain damage in clinical settings has not been previously explored or reported. Infants with neonatal hyperbilirubinemia (n = 30 per group) participated in a double-blind, randomized, placebo-controlled parallel study. They received either 100 mg/d DHA or placebo syrup immediately when they were diagnosed. The study found that the bilirubin level at 48 hours of treatment, serum neuron-specific enolase (NSE) levels, mean phototherapy duration, and abnormal rate of cranial magnetic resonance imaging (MRI) were lower in the DHA group than those in the control group (P < .05). These results suggested that DHA is effective as an adjuvant treatment for hyperbilirubinemia in children. It can reduce the incidence of neonatal hyperbilirubinemia brain injury and plays a certain protective role. Clinical study on protective effect of DHA on neonatal bilirubin injury is registered at Chinese Clinical Trial Registry as ChiCTR2300070250.

Antenatal jaundice instruction and acute bilirubin encephalopathy in Nigeria

BackgroundAcute Bilirubin Encephalopathy (ABE) is common in Nigeria. Parents’ inability to recognize jaundice and delays in seeking care are significant barriers to its prevention.MethodsWe compared associations of (1) interactive antenatal maternal jaundice instruction with postnatal reinforcement, (2) standard postnatal instruction, and (3) no maternal instruction with the incidence of ABE among 647 jaundice admissions stratified for risk factors identified in initial descriptive analysis.ResultsEighty-three (83/647;12.8%) admissions developed ABE including eleven jaundice-related deaths. ABE was present at admission in 20/22 (90.9%) if mothers received no jaundice instruction and no antenatal care, 42/182 (23.1%) if received antenatal care but no instruction, 16/95 (16.8%) if received postnatal instruction only, and 4/337 (1.2%) if mothers received both antenatal and postnatal instruction (p < .001). ABE was highly associated with out-of-hospital delivery, number of antenatal clinic visits, and birth attendant, but these risks were mitigated by antenatal/postnatal instruction. Admission rates with bilirubin levels below treatment guidelines (12 mg/dL) were higher following instruction (30.7%) than with no instruction (14.4%). Limiting subjects to those meeting admission criteria increased ABE rates in all groups without altering conclusions.ConclusionInteractive antenatal instruction with postnatal reinforcement resulted in timely care seeking and a lower incidence of ABE.ImpactEmpowering mothers to participate in neonatal jaundice management is critical in low-income countries where jaundice monitoring and follow up are unreliable.Instructing mothers about jaundice in antenatal clinics with postnatal reinforcement is more effective than standard postpartum instruction in facilitating jaundice detection, timely care seeking, and lowering the incidence of acute bilirubin encephalopathy (ABE).Antenatal training also mitigates risks for ABE associated with out-of-hospital deliveries, limited antenatal care, and unskilled birth attendants.Impact: Adding structured jaundice instruction in antenatal clinics could greatly reduce bilirubin induced brain injury in countries where ABE is common.

Kernicterus in the 21st Century: Bilirubin-Induced Brain Injury Due to Glucose-6- Phosphate Dehydrogenase Deficiency (P5.6-064)

Kernicterus in the 21st Century: Bilirubin-Induced Brain Injury Due to Glucose-6- Phosphate Dehydrogenase Deficiency (P5.6-064)

Neonatal Jaundice.

Hyperbilirubinemia is a common occurrence in neonates; it may be physiological or pathological. Conjugated hyperbilirubinemia may result from medical or surgical causes, and can result in irreversible liver damage if untreated. The aim of imaging is the timely diagnosis of surgical conditions like biliary atresia and choledochal cysts. Abdominal ultrasound is the first line imaging modality, and Magnetic resonance cholangiopancreatography (MRCP) also has a role, especially in pre-operative assessment of choledochal cysts (CDCs). For biliary atresia, the triangular cord sign and gallbladder abnormalities are the two most useful ultrasound features, with a combined sensitivity of 95%. Liver biopsy has an important role in pre-operative evaluation; however, the gold standard for diagnosis of biliary atresia remains an intra-operative cholangiogram. Choledochal cysts are classified into types according to the number, location, extent and morphology of the areas of cystic dilatation. They are often associated with an abnormal pancreaticobiliary junction, which is best assessed on MRCP. Caroli's disease or type 5 CDC comprises of multiple intrahepatic cysts. CDCs, though benign, require surgery as they may be associated with complications like cholelithiasis, cholangitis and development of malignancy. Severe unconjugated hyperbilirubinemia puts neonates at high risk of developing bilirubin induced brain injury, which may be acute or chronic. Magnetic resonance imaging of the brain is the preferred modality for evaluation, and shows characteristic involvement of the globus pallidi, subthalamic nuclei and cerebellum - in acute cases, these areas show T1 hyperintensity, while chronic cases typically show hyperintensity on T2 weighted images.

Developmental influence of unconjugated hyperbilirubinemia and neurobehavioral disorders.

Bilirubin-induced brain injury in the neonatal period has detrimental effects on neurodevelopment that persist into childhood and adulthood, contributing to childhood developmental disorders. Unconjugated bilirubin is a potent antioxidant that may be useful for protecting against oxidative injuries, but it becomes a potent neurotoxin once it crosses the blood brain barrier. Because bilirubin toxicity involves a myriad of pathological mechanisms, can damage most types of brain cells, and affects brain circuits or loops that influence cognition, learning, behavior, sensory, and language, the clinical effects of bilirubin-induced neurotoxicity are likely to be manifold. One possible effect that several experts have identified is bilirubin-induced neurological dysfunction (subtle kernicterus). However, the underlying biological mechanisms or pathways by which subtle kernicterus could lead to developmental disorders has not been elucidated previously. Our aim in this review is to describe a spectrum of developmental disorders that may reflect subtle kernicterus and outline plausible biological mechanisms for this possible association. We review existing evidence that support or refute the association between unconjugated hyperbilirubinemia and developmental disorders, and limitations associated with these studies.

Research progress of bilirubin-induced brain injury in preterm neonate

Clinical jaundice is present in the majority of the newborns, while bilirubin encephalopathy is one of the most serious complications.Preterm birth is high risk factors of bilirubin encephalopathy.Premature infants may develop bilirubin-induced central nervous system(CNS)injury even at total serum bilirubin(TSB)levels conventionally considered to be non-neurotoxic, and less frequently show the typical abnormal neuromotor clinical signs.Preterm birth is one of the risk factors of bilirubin encephalopathy.The potential for bilirubin-induced neurotoxicity in the premature neonate remains a clinical concern, while efforts to improve current clinical assessment and early diagnosis are certainly needed.Recently research on the molecular and cellular mechanism of bilirubin neurotoxicity and the clinical manifestations of bilirubin-induced CNS injury in the preterm neonate has made great progress, and it has been found that laboratory index and neuroimaging techniques are closely associated with early diagnosis of bilirubin-induced neurotoxicity in the preterm neonate. Key words: Bilirubin; Infant, premature; Neurotoxicity; Early diagnosis

Refractory Causes of Kernicterus in Developed Countries: Can We Eradicate G6PD Deficiency Triggered and Low-Bilirubin Kernicterus?

Glucose-6-phosphate dehydrogenase (G6PD) deficiency triggered and low-bilirubin kernicterus persist despite current prevention strategies. Review efforts to eradicate bilirubin induced brain injury in these two conditions including novel approaches to risk assessment and hyperbilirubinemia evaluation. In the case of G6PD deficiency, a heightened awareness of populations at risk and an expanded kernicterus prevention strategy focused on intensified parental engagement, education and counselling on neonatal jaundice is needed. In the case of low-bilirubin kernicterus, a renewed focus on identifying infants with hypoalbuminemia and implementation of hyperbilirubinemia treatment thresholds based on the bilirubin/albumin ratio is needed. Bilirubin binding panels when commercially available will prove valuable.

Interscapular site for transcutaneous bilirubin measurement in preterm infants: a better and safer screening site

To prevent bilirubin induced brain injury in the newborn, repeated blood withdrawals are necessary to ascertain bilirubin levels and institute care. Noninvasive, painless and bloodless screening using transcutaneous bilirubinometry is the standard of care for term and near term neonates but there is still debate about its use with preterm neonates. The aims of this study were to determine how transcutaneous bilirubin (TcB) level measured from the interscapular site related to total serum bilirubin (TSB) level and to compare performance of TcB from the forehead, sternum and interscapular sites in identifying preterm neonates in need of phototherapy. This was a cross sectional study conducted at Groote Schuur level III neonatal unit. Over a 5-month period 122 consecutive preterm neonates <35 weeks gestational age were enrolled. TcBs were measured over the forehead, sternum and interscapular area. Pearson's correlation coefficients and differences between TSB and TcBs were computed. P-value <0.05 was considered significant. The median gestational age of the study participants was 31 weeks (range: 24 to 34 weeks), the median TSB level was 81.5 μmol l(-1) (range: 25 to 229 μmol l(-1)) and 45% had a TSB at the phototherapy threshold. The correlation coefficients for TcBs ranged from 0.859 to 0.929 (P<0.001). The difference between TSB and TcBs ranged from -86 to +51 μmol l(-1). With respect to initiating phototherapy, the interscapular site had the highest sensitivity of 94% and lowest false negative rate of 6%. Using transcutaneous bilirubinometry, the interscapular site is superior and safer for screening preterm neonates.

Neurological dysfunction induced by bilirrubin

Introduction“Kernicterus” is a term currently used to describe bilirubin induced brain injury in the neuro-pathological studies. This is a confusing term and nowadays we prefer bilirubin encephalopathy or bilirubin induced neurological dysfunction. The clinical signs vary and it is clearly decreasing in prevalence in developed countries. Materials and methodsWe review a series of 7 patients with bilirubin encephalopathy and variable neurological manifestations, who were seen in the Neuropaediatric Department in the last 10 years. Only one patient died in the neonatal period with hyperbilirubinaemia, sepsis and multi-organ failure. ResultsDiverse aetiological factors were related to hyperbilirubinaemia. All patients had clinical symptoms due to hyperbilirubinaemia. Neuroimaging during the neonatal period showed involvement of the nucleus pallidus, with hyperintensity in T1 in the brain MR scan as the most consistent finding. All the patients who survived developed neurological signs and we try to correlate them with biochemical, clinical, neuroimaging and neurophysiological parameters. ConclusionsAn increase in the number of patients with bilirubin encephalopathy has been observed over the last few years, and we attempt to find out the causes. The increased survival of the low birth weight newborns, the increase in the immigration population and the use of diagnostic neuroimaging contribute to this increase. It is a great challenge for the neonatologist and for neuropaediatricians to prevent its occurrence and to minimise the effects of bilirubin encephalopathy.

Blood-Brain Interfaces and Bilirubin-Induced Neurological Diseases

The endothelium of the brain microvessels and the choroid plexus epithelium form highly specialized cellular barriers referred to as blood-brain interfaces through which molecular exchanges take place between the blood and the neuropil or the cerebrospinal fluid, respectively. Within the brain, the ependyma and the pia-glia limitans modulate exchanges between the neuropil and the cerebrospinal fluid. All these interfaces are key elements of neuroprotection and fulfill trophic functions; both properties are critical to harmonious brain development and maturation. By analogy to hepatic bilirubin detoxification pathways, we review the transport and metabolic mechanisms which in all these interfaces may participate in the regulation of bilirubin cerebral bioavailability in physiologic conditions, both in adult and in developing brain. We specifically address the role of ABC and OATP transporters, glutathione-S-transferases, and the potential involvement of glucuronoconjugation and oxidative metabolic pathways. Regulatory mechanisms are explored which are involved in the induction of these pathways and represent potential pharmacological targets to prevent bilirubin accumulation into the brain. We then review the possible alteration of the neuroprotective and trophic barrier functions in the course of bilirubin-induced neurological dysfunctions resulting from hyperbilirubinemia. Finally, we highlight the role of the blood-brain and blood-CSF barriers in regulating the brain biodisposition of candidate drugs for the treatment or prevention of bilirubin-induced brain injury.

Sex-Specific Regional Brain Bilirubin Content in Hyperbilirubinemic Gunn Rat Pups

Background: The hyperbilirubinemic j/j Gunn rat is frequently used to study the effects of neonatal hyperbilirubinemia on the developing central nervous system (CNS). Despite evidence that the cerebellar region and males are predisposed to bilirubin-induced brain injury in this animal model, there are limited regional and no sex-specific brain bilirubin content data. Objective/Methods: To characterize and contrast the regional (cortex, brainstem, cerebellum) and sex-specific CNS bilirubin contents of hyperbilirubinemic j/j Gunn rat pups and their age-matched (15–19 days) nonjaundiced J/j counterparts. Pups were injected 24 h prior to sacrifice with sulfadimethoxine (200 mg/kg i.p.) to enhance the CNS bilirubin content. Results: The CNS bilirubin contents in each region and total serum bilirubin levels were significantly greater in jaundiced j/j pups versus nonjaundiced J/j pups. Within the sulfadimethoxine-treated male j/j cohort, the mean brain bilirubin content was highest in the cerebellum (18.9 ± 7.8 µg/g), intermediate in the brainstem (10.7 ± 8.0 µg/g), and lowest in the cortex (4.7 ± 3.0 µg/g) (F = 11.31, p < 0.001 by ANOVA), and the cerebellar bilirubin level was significantly higher than in the littermate-matched sulfadimthoxine-treated j/j female pups (p < 0.02). The serum albumin levels were not different between j/j male and j/j female pups. Conclusions: We conclude that the brain bilirubin content of hyperbilirubinemic j/j Gunn rat pups is greater than in nonjaundiced J/j pups and varies as a function of CNS region and sex. We speculate that the higher cerebellar bilirubin content may preferentially predispose male j/j Gunn rat pups to bilirubin-induced neurotoxicity.

The Effect of Instituting a Prehospital-Discharge Newborn Bilirubin Screening Program in an 18-Hospital Health System

Kernicterus is a rare but devastating condition. The prevention of bilirubin-induced brain injury is based on the detection of infants at risk for developing severe hyperbilirubinemia. In an 18-hospital health system, Intermountain Health Care (IHC), we initiated a program of predischarge bilirubin screening of all neonates and coupled this with a results assessment using a percentile-based nomogram. Data during 2 periods of time, before versus after initiating the program, were compared to assess the effect of the program on significant hyperbilirubinemia and rehospitalization. We conducted a historic cohort study involving all neonates delivered at > or =35 weeks' gestation, within IHC's 18-hospital system, during 2 periods of time: March 1, 2001, to December 31, 2002, versus January 1, 2003, to December 31, 2004. A bilirubin screening program, instituted in December 2002, called for a total serum bilirubin (TSB) or transcutaneous bilirubin measurement to be performed on every neonate either at the recognition of clinical jaundice or before discharge regardless of whether jaundice was observed. For nonjaundiced neonates, the nursery staff was encouraged to obtain the screening TSB at the same time they obtained the state-mandated newborn screen for inborn errors of metabolism. Bilirubin values were plotted on an hour-specific nomogram and the corresponding percentile was used to guide evaluation, therapy, and follow-up. This study compared TSB data and readmission data for a 2-year period before versus a 2-year period after implementing the program. The study involved 101272 neonates: 48789 in period 1 and 52483 in period 2. Before the program, 1 in every 77 neonates born at an IHC hospital had 1 or more serum bilirubin levels >20 mg/dL. After initiating the program, the incidence fell to 1 in 142 and the number of neonates with a level >25 mg/dL fell from 1 in 1522 before to 1 in 4037 after. The rate of hospital readmission with a primary diagnosis of jaundice fell from 0.55% in period 1 to 0.43% in period 2. Initiating a program of bilirubin screening in a multihospital health system, coupled with evaluating the results using a percentile-based nomogram, reduced the proportion of neonates with significant hyperbilirubinemia and reduced the rate of hospital readmissions with jaundice.

Definition of the Clinical Spectrum of Kernicterus and Bilirubin-Induced Neurologic Dysfunction (BIND)

Kernicterus, currently used to describe both the neuropathology of bilirubin-induced brain injury and its associated clinical findings, is a complex syndrome. The neurobiology of kernicterus, including the determinants and mechanisms of neuronal injury, is discussed along with traditional and evolving definitions ranging from classical kernicterus with athetoid cerebral palsy, impaired upward gaze and deafness, to isolated conditions, for example, auditory neuropathy or dys-synchrony (AN/AD), and subtle bilirubin-induced neurological dysfunction (BIND). The clinical expression of BIND varies with location, severity, and time of assessment, influenced by the amount, duration and developmental age of exposure to excessive free bilirubin. Although total serum bilirubin (TSB) is important, kernicterus cannot be defined based solely on TSB. For study purposes kernicterus may be defined in term and near-term infants with TSB > or = 20 mg/dl using abnormal muscle tone on examination, auditory testing diagnostic of AN/AD, and magnetic resonance imaging showing bilateral lesions of globus pallidus+/-subthalamic nucleus.

An Introduction to the Papers Presented at the NICHD Conference on Prevention of Bilirubin-Induced Brain Injury and Kernicterus

In this and in future issues of the Journal of Perinatology, articles will appear based on the presentations made at the conference, From Bench to Bedside: Preventing Bilirubin-Induced Brain Injury (BIBI) in the Newborn and Kernicterus in the 21st Century. The Conference, sponsored by the National Institute of Child Health and Human Development (NICHD, part of the National Institutes of Health, and the Department of Health and Human Services), was held in Bethesda, Maryland, in June 2003. An Executive Summary of the proceedings is also being published.1

Role of Glutamate Receptor-Mediated Excitotoxicity in Bilirubin-Induced Brain Injury in the Gunn Rat Model

Severe hyperbilirubinemia in neonates with prematurity and/or systemic illnesses such as hemolytic disease, acidosis, and hypoxemia enhances their risk for developing cerebral palsy, paralysis of ocular upgaze, and deafness. This neurologic syndrome has been associated with selective neuronal vulnerability in the basal ganglia, certain brainstem nuclei, and Purkinje cells. However, the mechanism by which bilirubin damages neurons remains unclear. In these studies, we found that intracerebral injection ofN-methyl-d-aspartate (NMDA), an excitotoxic analogue of glutamate, caused greater injury in jaundiced 7-day-old Gunn (jj) rat pups than in nonjaundiced heterozgous (Nj) littermate controls. NMDA injection caused even greater injury when protein-bound bilirubin was displaced with the sulfonamide drug sulfadimethoxine in jaundiced homozygous pups. In additional experiments, the acute signs of bilirubin-mediated neuronal injury, induced in homozygous (jj) Gunn rats by treatment with sulfonamide, were reduced by concurrent treatment with the NMDA-type glutamate channel antagonist (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohept-5,10-imine (MK-801, dizocilpine). The results suggest that bilirubin may cause encephalopathy and neuronal injury, at least in part, through an NMDA receptor-mediated excitotoxic mechanism. This conclusion is consistent with clinical observations that bilirubin encephalopathy is synergistically worsened by hypoxemia, which also shares an excitotoxic mechanism of neuronal injury.