Early prediction of adverse outcomes in infants with acute bilirubin encephalopathy

Predictive and diagnostic measures for kernicterus spectrum disorder: a prospective cohort study

BACKGROUND

Kernicterus spectrum disorder (KSD) resulting from neonatal hyperbilirubinemia remains a common cause of cerebral palsy worldwide. This 12-month prospective cohort study followed neonates with hyperbilirubinemia to determine which clinical measures best predict KSD.

METHODS

The study enrolled neonates ≥35 weeks gestation with total serum bilirubin (TSB) ≥ 20 mg/dl admitted to Aminu Kano Hospital, Nigeria. Clinical measures included brain MRI, TSB, modified bilirubin-induced neurologic dysfunction (BIND-M), Barry-Albright Dystonia scale (BAD), auditory brainstem response (ABR), and the modified KSD toolkit. MRI signal alteration of the globus pallidus was scored using the Hyperbilirubinemia Imaging Rating Tool (HIRT).

RESULTS

Of 25 neonates enrolled, 13/25 completed 12-month follow-up and six developed KSD. Neonatal BIND-M ≥ 3 was 100% sensitive and 83% specific for KSD. Neonatal ABR was 83% specific and sensitive for KSD. Neonatal HIRT score of 2 was 67% sensitive and 75% specific for KSD; this increased to 100% specificity and sensitivity at 12 months. BAD ≥ 2 was 100% specific for KSD at 3-12 months, with 50-100% sensitivity.

CONCLUSIONS

Neonatal MRIs do not reliably predict KSD. BIND-M is an excellent screening tool for KSD, while the BAD or HIRT score at 3 or 12 months can confirm KSD, allowing for early diagnosis and intervention.

IMPACT

The first prospective study of children with acute bilirubin encephalopathy evaluating brain MRI findings over the first year of life. Neonatal MRI is not a reliable predictor of kernicterus spectrum disorders (KSD). Brain MRI at 3 or 12 months can confirm KSD. The modified BIND scale obtained at admission for neonatal hyperbilirubinemia is a valuable screening tool to assess risk for developing KSD. The Barry Albright Dystonia scale and brain MRI can be used to establish a diagnosis of KSD in at-risk infants as early as 3 months.

Polyethylene glycol precipitation is an efficient method to obtain extracellular vesicle-depleted fetal bovine serum

Mesenchymal stromal/stem cell derived-extracellular vesicles (MSC-EVs) have gained interest as drug delivery nanoparticles, having immunoregulatory and potentiating tissue repair property. To maintain growth of MSCs and obtain pure MSC-derived EVs, the culture media should contain fetal bovine serum (FBS) devoid of EVs, as the presence of FBS EVs confounds the properties of MSC-EVs. Therefore, we tested three methods: 18h ultracentrifugation (UC) and ultrafiltration (UF), which are common FBS EV depletion methods in current MSC-EV research, and polyethylene glycol (PEG) precipitation to obtain three EV depleted FBS (EVdFBS) batches, and compared them to FBS and commercial (Com) EVdFBS on human adipose stem cell (hADSC) growth, differentiation, enrichment of EVs in hADSC supernatant and their biological function on collagen metabolism. Our comparative study showed UC and UF vary in terms of depletion efficiency and do not completely deplete EVs and affects the growth-promoting quality of FBS. Specifically, FBS EV depletion was comparable between PEG (95.6%) and UF (96.6%) but less by UC (82%), as compared to FBS. FBS protein loss was markedly different among PEG (47%), UF (87%), and UC (51%), implying the ratio of EV depletion over protein loss was PEG (2.03), UF (1.11), and UC (1.61). A significant decrease of TGFβ/Smad signaling, involving in MSC growth and physiology, was observed by UF. After 96 hours of exposure to 5% FBS or 5% four different EVdFBS cell growth media, the osteogenesis ability of hADSCs was not impaired but slightly lower mRNA expression level of Col2a observed in EVdFBS media during chondrogenesis. In consistent with low confluency of hADSCs observed by optical microscope, cell proliferation in response to 5% UF EVdFBS media was inhibited significantly. Importantly, more and purer ADSCs EVs were obtained from ADSCs cultured in 5% PEG EVdFBS media, and they retained bioactive as they upregulated the expression of Col1a1, TIMP1 of human knee synovial fibroblast. Taken together, this study showed that PEG precipitation is the most efficient method to obtain EV depleted FBS for growth of MSCs, and to obtain MSC EVs with minimal FBS EV contamination.

Bilirubin induces microglial NLRP3 inflammasome activation in vitro and in vivo

Despite current advancements in neonatal care, hyperbilirubinemia resulting in bilirubin-induced neurological dysfunction (BIND) continues to be one of the major reasons of mortality or lifelong disability. Although the exact mechanisms underlying brain injury upon bilirubin exposure remains unelucidated, inflammation is considered to be one of the major contributors to BIND. This study investigates the role of the NLRP3 inflammasome in bilirubin-induced injury using in vitro and in vivo models. We successfully demonstrated that the upregulation of NLRP3 expression is significantly associated with the release of active caspase-1 and IL-1β in N9 microglial cells exposed to bilirubin. Functional in vitro experiments with NLRP3 siRNA confirms that bilirubin-induced inflammasome activation and cell death are mediated by the NLRP3 inflammasome. Following injection of bilirubin into the cisterna magna of a neonatal mouse, activation of the NLRP3 inflammasome and microglia were determined by double staining with Iba1-NLRP3 and Iba1-Caspase-1. Upon injection of bilirubin into the cisterna magna, neuronal loss was significantly higher in the wild-type mouse compared to Nlrp3^-/- and Caspase-1^-/- strains. Collectively, these data indicate that NLRP3 inflammasome has a crucial role in microglial activation and bilirubin-induced neuronal damage.

Outcome Analysis of Severe Hyperbilirubinemia in Neonates Undergoing Exchange Transfusion

OBJECTIVE

Severe neonatal hyperbilirubinemia can cause neurological disability or mortality if not effectively managed. Exchange transfusion (ET) is an efficient treatment to prevent bilirubin neurotoxicity. The purpose of this study was to evaluate outcomes in severe neonatal hyperbilirubinemia with ET and to identify the potential risk factors for poor outcomes.

METHODS

Newborns of ≥28 weeks of gestational age with severe hyperbilirubinemia who underwent ET from January 2015 to August 2019 were included. Demographic data were recorded and analyzed according to follow-up outcomes at 12 months of corrected age. Poor outcomes were defined as death due to bilirubin encephalopathy or survival with at least one of the following complications: cerebral palsy, psychomotor retardation (psychomotor developmental index < 70), mental retardation (mental developmental index < 70), or hearing impairment.

RESULTS

A total of 524 infants were eligible for recruitment to the study, and 62 infants were lost to follow-up. The outcome data from 462 infants were used for grouping analysis, of which 398 cases (86.1%) had normal outcomes and 64 cases (13.9%) suffered poor outcomes. Bivariate logistic regression analysis showed that peak total serum bilirubin (TSB) (odds ratio [OR] = 1.011, 95% confidence interval [CI] = 1.008-1.015, p = 0.000) and sepsis (OR = 4.352, 95% CI = 2.013-9.409, p < 0.001) were associated with poor outcomes of hyperbilirubinemia. Receiver operator characteristic curve analysis showed that peak TSB ≥452.9 µmol/L could predict poor outcomes of severe hyperbilirubinemia.

CONCLUSION

Peak TSB and sepsis were associated with poor outcomes in infants with severe hyperbilirubinemia, and peak TSB ≥452.9 µmol/L could predict poor outcomes.

The development and validation of a predictive model for neonatal phototherapy outcome using admission indicators

Delayed exchange transfusion therapy (ETT) after phototherapy failure for newborns with severe hyperbilirubinemia could lead to serious complications such as bilirubin encephalopathy (BE). In this current manuscript we developed and validated a model using admission data for early prediction of phototherapy failure. We retrospectively examined the medical records of 292 newborns with severe hyperbilirubinemia as the training cohort and another 52 neonates as the validation cohort. Logistic regression modeling was employed to create a predictive model with seven significant admission indicators, i.e., age, past medical history, presence of hemolysis, hemoglobin, neutrophil proportion, albumin (ALB), and total serum bilirubin (TSB). To validate the model, two other models with conventional indicators were created, one incorporating the admission indicators and phototherapy failure outcome and the other using TSB decrease after phototherapy failure as a variable and phototherapy outcome as an outcome indicator. The area under the curve (AUC) of the predictive model was 0.958 [95% confidence interval (CI): 0.924-0.993] and 0.961 (95% CI: 0.914-1.000) in the training and validation cohorts, respectively. Compared with the conventional models, the new model had better predictive power and greater value for clinical decision-making by providing a possibly earlier and more accurate prediction of phototherapy failure. More rapid clinical decision-making and interventions may potentially minimize occurrence of serious complications of severe neonatal hyperbilirubinemia.

Childhood neurodevelopmental outcomes of survivors of acute bilirubin encephalopathy: A retrospective cohort study

BACKGROUND

Reports on childhood neurodevelopmental and neurosensory outcomes following acute bilirubin encephalopathy from low- and middle-income countries are scarce.

AIM

This study aimed to analyze the neurodevelopmental and neurosensory outcomes of survivors of acute bilirubin encephalopathy.

STUDY DESIGN

Retrospective cohort.

SUBJECTS

Neonates with admission diagnosis of acute bilirubin encephalopathy were followed up and assessed for neuromotor, neurodevelopmental and neurosensory functions between 18 m and 12.5 years of age.

RESULTS

In 67 neonates with acute bilirubin encephalopathy, a composite outcome of cerebral palsy or death was observed in 33 (49%) subjects. Choreo-athetoid cerebral palsy [19 (73%)] was the most common type observed. Sensori-neural hearing loss was observed in 46 (79%) subjects. Subjects with cerebral palsy had significantly low Developmental profile-3 scores in all assessed domains. Neonates with an early-stage acute bilirubin encephalopathy (aOR (95% C.I): 0.12 (0.05-0.71); p = 0.02) and those with a normal neurological examination at discharge (aOR (95% C.I): 0.11 (0.06-0.7); p = 0.049) had significantly lower odds of the primary outcome.

CONCLUSIONS

Majority of survivors of acute bilirubin encephalopathy had adverse outcomes during childhood in the form of cerebral palsy and sensory-neural hearing loss. Cognitive functions were better preserved than the language and general development in the affected children.