Hyperbilirubinemia

Synthetic augmentation of bilirubin metabolism in human pluripotent stem cell-derived liver organoids

UGT1A1 (UDP glucuronosyltransferase family 1 member A1) is the primary enzyme required for bilirubin conjugation, which is essential for preventing hyperbilirubinemia. Animal models lack key human organic anion transporting polypeptides with distinct epigenetic control over bilirubin metabolism, necessitating a human model to interrogate the regulatory mechanism behind UGT1A1 function. Here, we use induced pluripotent stem cells to develop human liver organoids that can emulate conjugation failure phenotype. Bilirubin conjugation assays, chromatin immunoprecipitation, and transcriptome analysis elucidated the role of glucocorticoid antagonism in UGT1A1 activation. This antagonism prevents the binding of transcriptional repressor MECP2 at the expense of NRF2 with associated off-target effects. Therefore, we introduced functional GULO (L-gulonolactone oxidase) in human organoids to augment intracellular ascorbate for NRF2 reactivation. This engineered organoid conjugated more bilirubin and protected against hyperbilirubinemia when transplanted in immunosuppressed Crigler-Najjar syndrome rat model. Collectively, we demonstrate that our organoid system serves as a manipulatable model for interrogating hyperbilirubinemia and potential therapeutic development.

NAD+ attenuates bilirubin-induced augmentation of voltage-gated calcium currents in neurons of the ventral cochlear nucleus

Nicotinamide adenine dinucleotide (NAD+) is a ubiquitous molecule with wide-ranging roles in several cell processes, such as regulation of calcium homeostasis and protection against cell injuries. However, the roles of NAD+ in neuroprotection is poorly understood. The main neurons in ventral cochlear nucleus (VCN) are highly susceptible to bilirubin-associated excitotoxicity. We investigated the effects of NAD+ on VCN neurons by whole cell patch-clamp recordings. We found that NAD+ effectively reverses and inhibits bilirubin-mediated enhancement of voltage-gated calcium (VGCC) currents in VCN neurons. Moreover, NAD+ itself did not affect VGCC currents. These results collectively suggest that NAD+ may be neuroprotective by attenuating Ca²⁺ influx to suppress bilirubin-induced intracellular Ca²⁺ overloads. Our research provides a basis for evaluation of NAD+ as a promising therapeutic target for bilirubin encephalopathy and excitotoxicity associated with other neurological disorders.

Neonatal Hyperbilirubinemia

Neonatal hyperbilirubinemia (NH) is a common phenomenon. In most cases, NH is benign and transient. However, in severe NH cases, neonates can develop encephalopathy and kernicterus. With appropriate screening and treatment, these adverse sequelae can be prevented. This article aims to provide the reader with an in-depth understanding of (1) bilirubin metabolism, (2) risk factors for severe NH, (3) NH screening and treatment, (4) various etiologies of severe NH, and (5) consequences of severe, untreated NH. [Pediatr Ann. 2022;51(6):e219-e227.].

Does Jaundice in Newborn Infants Affect Exclusivity and Duration of Breastfeeding in Taiwan?

BACKGROUND

Cases of breastfeeding- and breast-milk-related jaundice tend to increase with increased rates of breastfeeding. Diagnoses of jaundice often lead mothers to discontinue breastfeeding because of assumptions that breastfeeding may exacerbate neonatal jaundice and lengthen the duration of phototherapy treatment.

PURPOSE

This study was designed to explore the effect of neonatal jaundice on breastfeeding duration and exclusivity during the first 4 months postpartum.

METHODS

This study applied a two-group comparative and follow-up design. The two groups comprised 135 and 160 mothers of infants, respectively, with and without neonatal jaundice. All of the participants were recruited from three certified baby-friendly hospitals in northern Taiwan. Follow-up was conducted by telephone at 1 and 4 months postpartum.

RESULTS

Mean breastfeeding duration was longer in the group of participants whose infants had neonatal jaundice (group with neonatal jaundice) than in the group whose infants did not have this condition (group without neonatal jaundice; 102.00 vs. 89.85 days, p = .007). The degree of breastfeeding was higher in the group with neonatal jaundice, although the difference was significant only at 1 month postpartum and not during hospitalization or at 4 months postpartum. The results of a Cox regression model showed that the group without neonatal jaundice was more likely to discontinue breastfeeding (adjusted hazard ratio = 1.68, 95% CI [1.08, 2.62]). A generalized estimating equation model suggests that infants with neonatal jaundice had a higher likelihood of being breastfed for at least half of their feedings (adjusted OR = 1.53, 95% CI [1.04, 2.25]).

CONCLUSIONS

On the basis of the results of this study, neonatal jaundice is not an obstacle to breastfeeding in pro-breastfeeding hospital environments. Participants whose infants developed neonatal jaundice were found in this study to breastfeed more often, which promotes breastfeeding success.

Neonatal Jaundice: Perception of Pregnant Women Attending Antenatal Clinic at a Tertiary Hospital in Southwest, Nigeria

Background: Severe neonatal jaundice (NNJ) remains a leading cause of preventable brain damage, mental handicap, physical disabilities, and early death among infants. Methods: Using a descriptive cross-sectional study design, information was gathered using a structured, pretested questionnaire from 518 pregnant women who attended the antenatal clinic at a tertiary Hospital in Southwest Nigeria. Results: Most (77%) of the respondents have heard about NNJ prior the survey. Most respondents (69.5%) demonstrated poor knowledge of the causes of NNJ. The majority, 98.4% had good attitude toward treatment of NNJ. Most respondents (72.1%) demonstrated poor knowledge of the correct treatment of NNJ. A quarter of the respondents knew no danger sign of NNJ. Conclusion: There is serious knowledge gap among the respondents about the causes, treatment, dangers signs and complications of NNJ. There is need for increased awareness campaign using every available means of reaching women of reproductive age group to reduce the consequences of this common neonatal problem.

Conformational Control of the Photodynamics of a Bilirubin Dipyrrinone Subunit: Femtosecond Spectroscopy Combined with Nonadiabatic Simulations

The photochemistry of bilirubin has been extensively studied due to its importance in the phototherapy of hyperbilirubinemia. In the present work, we investigated the ultrafast photodynamics of a bilirubin dipyrrinone subunit, vinylneoxanthobilirubic acid methyl ester. The photoisomerization and photocyclization reactions of its (E) and (Z) isomers were studied using femtosecond transient absorption spectroscopy and by multireference electronic structure theory, where the nonadiabatic dynamics was modeled with a Landau-Zener surface hopping technique. The following picture has emerged from the combined theoretical and experimental approach. Upon excitation, dipyrrinone undergoes a very fast vibrational relaxation, followed by an internal conversion on a picosecond time scale. The internal conversion leads either to photoisomerization or regeneration of the starting material. Further relaxation dynamics on the order of tens of picoseconds was observed in the ground state. The nonadiabatic simulations revealed a strong conformational control of the photodynamics. The ultrafast formation of a cyclic photochemical product from a less-populated conformer of the studied subunit was predicted by our calculations. We discuss the relevance of the present finding for the photochemistry of native bilirubin. The work has also pointed to the limits of semiclassical nonadiabatic simulations for simulating longer photochemical processes, probably due to the zero-point leakage issue.

Prevalence of and mothers' knowledge, attitude and practice towards glucose-6-phosphate dehydrogenase deficiency among neonates with jaundice: a cross-sectional study

BACKGROUND

Neonatal jaundice (NNJ) is a frequent complication of glucose-6-phosphate dehydrogenase (G6PD) deficiency.

OBJECTIVES

To estimate the prevalence of G6PD deficiency among neonates with jaundice and to assess mothers' perception towards G6PD and NNJ.

METHODS

A cross-sectional study was carried out on 487 ethnic Egyptian neonates with indirect hyperbilirubinaemia from June 2018 to July 2019. The collected data included maternal and neonatal characteristics. Laboratory investigations included serum bilirubin, reticulocyte count, ABO grouping, Rh typing and neonatal serum G6PD test. Mothers were interviewed individually using a structured, researcher-administered questionnaire to assess their perceptions of G6PD deficiency and NNJ.

RESULTS

The prevalence of G6PD deficiency was 10.10%. Neonates with G6PD deficiency showed higher levels of serum bilirubin (p<0.001). Male gender, family history of G6PD deficiency and consanguinity were risk factors for G6PD deficiency (OR=4.27, 95% CI 1.66 - 10.99; OR=9.54, 95% CI 4.80- 18.95; OR=10.219, 95% CI 5.39 - 19.33, respectively). Mothers' perceptions of NNJ and G6PD were low, with only 30% having good knowledge on NNJ and 17.10% on G6PD deficiency, 46.8% with positive attitude towards NNJ and 45.0% towards G6PD deficiency, and 29.9% with good practice towards NNJ and 19.9% towards G6PD deficiency.

CONCLUSION

G6PD deficiency seems to be an important cause of NNJ. Mothers' perceptions of both NNJ and G6PD deficiency were low. A mass health education programme on both of these diseases is needed to ensure better and early detection, good timing of treatment, and better prevention of the triggering factors to ensure better health for children.

Delayed cord clamping was not associated with an increased risk of hyperbilirubinaemia on the day of birth or jaundice in the first 4 weeks

AIM

Our aim was to investigate the effects of timing of cord clamping on the risk of hyperbilirubinaemia.

METHODS

We recruited 540 normal vaginal deliveries at the Paropakar Maternity and Women's Hospital in Kathmandu, Nepal, from October 2 to November 21, 2014. They were randomised into two groups: 257/270 were cord clamped within 60 seconds and 209/270 after 180 seconds. Transcutaneous bilirubin was measured at discharge and 24 hours. At 4 weeks, 506 mothers were successfully contacted by phone, and the health status of the baby and their history of jaundice and treatment was recorded.

RESULTS

Based on transcutaneous bilirubin at discharge, 22/261 (8.4%) in the early group and 25/263 (9.5%) in the delayed group (P = 0.76) were at high risk of subsequent hyperbilirubinemia. At the 4-week follow-up, jaundice was reported in 13/253 (5.1%) in the early and 17/253 (6.7%) in the delayed group (P = 0.57) and 3/253 (1.2 %) of the early and 1/253 (0.4%) of the delayed group (P = 0.62) received treatment. All analyses were based on intention-to-treat.

CONCLUSION

Delayed cord clamping was not associated with an increased risk of hyperbilirubinaemia during the first day of life or risk of jaundice within 4 weeks compared with the early group.

Influence of Moderate Hyperbilirubinemia on Cardiorespiratory Control in Preterm Lambs

Hyperbilirubinemia (HB) is responsible for neonatal jaundice in 60% of term newborns and 90% of preterm infants. Neonatal HB can induce neurological damage (acute HB encephalopathy) and has been associated with persistent apneas. The objective of the present study was to investigate the immediate and delayed effects of moderate, clinically-relevant HB on cardiorespiratory control in preterm lambs. Two groups of five preterm lambs, namely control and HB, were studied. At day five of life, moderate HB (150-250 μmol/L) was induced and maintained during 17 h in the HB group while control lambs received a placebo solution. Six hours after HB onset, 7-h polysomnographic recordings with electrocardiogram (ECG) and respiratory (RESP) signals were performed to assess the immediate effects of HB on heart rate variability (HRV), respiratory rate variability (RRV), and cardiorespiratory interrelations. Identical recordings were repeated 72 h after HB induction to examine the delayed effects of HB on HRV, RRV and cardiorespiratory interrelations. Our results demonstrate a higher HRV and vagal activity immediately after induction of moderate HB. Meanwhile, a decrease in respiratory rate with an increase in both long- and short-term RRV was also noted, as well as a higher amplitude of the respiratory sinus arrhythmia and cardiorespiratory coupling. Seventy-two hours later, the alterations in HRV, RRV, and cardiorespiratory interrelations were attenuated, although a number of them were still present, suggesting a lasting influence of HB on the basal control of the cardiorespiratory system. Our results pave the way for studies in human preterms to assess the relevance of monitoring HRV, RRV, and cardiorespiratory interrelations to detect the acute neurological effects of HB and consequently adapt the treatment of neonatal jaundice.

Association between genetic polymorphism of heme oxygenase 1 promoter and neonatal hyperbilirubinemia: a meta-analysis

Objective: The association between a (GT)_n dinucleotide length polymorphism in the promoter region of heme oxygenase 1 (HMOX1) and the risk of neonatal hyperbilirubinemia remains controversial. This meta-analysis was, therefore, performed with aims to examine the correlation between the HMOX1 (GT)_n repeat length polymorphism and neonatal hyperbilirubinemia susceptibility.Materials and methods: We searched the databases including PubMed, Embase, Cochrane Library, China national knowledge infrastructure (CNKI), and Wanfang Data, with all reviewed studies published before 28 June 2018. After the evaluation of quality, we used RevMan to perform the meta-analyses. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the effect of HMOX1 gene promoter polymorphisms on the risk of neonatal hyperbilirubinemia.Results: Seven studies, involving 584 patients with neonatal hyperbilirubinemia and 1655 controls, were included. A statistically significant association was found between the HMOX1 (GT)_n repeat length polymorphism and risk of neonatal hyperbilirubinemia under the allele (allele S vs. allele L: OR = 1.81, 95% CI = 1.22-2.67, p = .003), recessive (genotype SS vs. genotypes LS + LL: OR = 1.38, 95% CI = 1.02-1.86, p = .04), dominant (genotypes SS + LS vs. LL: OR = 1.37, 95% CI = 1.01-1.76, p = .01), and homozygous genetic models (genotype SS vs. genotype LL: OR = 1.47, 95% CI = 1.02-2.11, p = .003), but not under the heterozygous genetic model. Interestingly, subgroup analysis revealed that the cutoffs of the S allele < 25 showed significant associations in any of the five genetic models (allele S vs. allele L: OR = 2.26, 95% CI = 1.68-3.05, p < .00001; genotype SS vs. genotypes LS + LL: OR = 2.56, 95% CI = 1.41-4.65, p = .002; genotypes SS + LS vs. genotype LL: OR = 1.82, 95% CI = 1.28-2.59, p = .0009; genotype SS vs. genotype LL: OR = 3.09, 95% CI = 1.50-6.36, p = .002; genotype LS vs. genotype LL: OR = 1.64, 95% CI = 1.11-2.42, p = .01); however, this association was not observed in the cutoffs of the S allele ≥25.Conclusion: The results of this study indicate that there is a significant association between the HMOX1 (GT)_n repeat length polymorphism and susceptibility to neonatal hyperbilirubinemia. Newborns carrying shorter (GT)_n repeats in the HMOX1 gene promoter may have a higher risk of neonatal hyperbilirubinemia.

Bilirubin-induced neurotoxic and ototoxic effects in rat cochlear and vestibular organotypic cultures

Exposure to high levels of bilirubin in hyperbilirubinemia patients and animal models can result in sensorineural deafness. However, the mechanisms underlying bilirubin-induced damage to the inner ear, including the cochlear and vestibular organs, remain unknown. The present analyses of cochlear and vestibular organotypic cultures obtained from postnatal day 3 rats exposed to bilirubin at varying concentrations (0, 10, 50, 100, or 250 μM) for 24 h revealed that auditory nerve fibers (ANFs) and vestibular nerve endings were destroyed even at low doses (10 and 50 μM). Additionally, as the bilirubin dose increased, spiral ganglion neurons (SGNs) and vestibular ganglion neurons (VGNs) exhibited gradual shrinkage in conjunction with nuclei condensation or fragmentation in a dose-dependent manner. The loss of cochlear and vestibular hair cells (HCs) was only evident in explants treated with the highest concentration of bilirubin (250 μM), and bilirubin-induced major apoptosis most likely occurred via the extrinsic apoptotic pathway. Thus, the present results indicate that inner ear neurons and fibers were more sensitive to, and exhibited more severe damage following, bilirubin-induced neurotoxicity than sensory HCs, which illustrates the underlying causes of auditory neuropathy and vestibulopathy in hyperbilirubinemia patients.

The Late Preterm: A Population at Risk

Late preterm infants (LPIs) are born between 34 0/7 and 36 6/7 weeks' gestation and account for 72% of all preterm births in the United States. Born as much as 6 weeks early, the LPI misses the critical growth and development specific to the third trimester. The loss of this critical period leaves the LPI physiologically and metabolically immature and prone to various morbidities. Common morbidities include respiratory complications, feeding difficulty, hypoglycemia, temperature instability, hyperbilirubinemia, and neurodevelopmental delays.

Identification of Genetic Risk Factors for Neonatal Hyperbilirubinemia in Fujian Province, Southeastern China: A Case-Control Study

To date, the genetic risk factors for neonatal hyperbilirubinemia remain unknown in Southeastern China. This case-control study aimed to identify the genetic risk factors for neonatal hyperbilirubinemia in Fujian, Southeastern China. A total of 286 hyperbilirubinemic newborns were enrolled as a case group, and 250 randomly selected newborns without jaundice or with a bilirubin level that was lower than the threshold required for phototherapy served as controls. The serum levels of total bilirubin, unconjugated bilirubin, and direct bilirubin were measured, and the common genetic loci in UGT1A1, OATP1B1, and HO-1 genes were genotyped. Higher incidence of ABO incompatibility and G6PD deficiency was detected in the case group compared to the control group (P < 0.01). There were significant differences in the frequencies of rs4148323 and rs1805173 genotypes between the case and control groups (P < 0.05). At the rs4148323 locus, the frequencies of GA heterozygotes and AA mutant homozygotes were higher in the case group than in the control group (P < 0.05), and at the rs1805173 locus, the frequencies of LS, MS, and SS genotypes were higher in the case group than in the control group (P < 0.05). A higher frequency of rs4148323 A allele and rs1805173 S allele was detected in the case group compared to the control group (P = 0). Additionally, multivariate logistic regression analysis identified that the mutant genotype of rs4148323 in the UGT1A1 gene, ABO incompatibility, G6PD deficiency, and SS genotype at rs1805173 locus of the HO-1 gene were genetic risk factors of neonatal hyperbilirubinemia. Our data demonstrate that G211 mutation in the UGT1A1 gene, ABO incompatibility, G6PD deficiency, and the SS genotype of the repeats in the promoter region of the HO-1 gene are risk factors for neonatal hyperbilirubinemia in Fujian, Southeastern China.

Bilirubin augments Ca2+ load of developing bushy neurons by targeting specific subtype of voltage-gated calcium channels

Neonatal brain is particularly vulnerable to pathological levels of bilirubin which elevates and overloads intracellular Ca²⁺, leading to neurotoxicity. However, how voltage-gated calcium channels (VGCCs) are functionally involved in excess calcium influx remains unknown. By performing voltage-clamp recordings from bushy cells in the ventral cochlear nucleus (VCN) in postnatal rat pups (P4-17), we found the total calcium current density was more than doubled over P4-17, but the relative weight of VGCC subtypes changed dramatically, being relatively equal among T, L, N, P/Q and R-type at P4-6 to predominantly L, N, R over T and P/Q at P15-17. Surprisingly, acute administration of bilirubin augmented the VGCC currents specifically mediated by high voltage-activated (HVA) P/Q-type calcium currents. This augment was attenuated by intracellular loading of Ca²⁺ buffer EGTA or calmodulin inhibitory peptide. Our findings indicate that acute exposure to bilirubin increases VGCC currents, primarily by targeting P/Q-type calcium channels via Ca²⁺ and calmodulin dependent mechanisms to overwhelm neurons with excessive Ca²⁺. Since P/Q-subtype calcium channels are more prominent in neonatal neurons (e.g. P4-6) than later stages, we suggest this subtype-specific enhancement of P/Q-type Ca²⁺ currents likely contributes to the early neuronal vulnerability to hyperbilirubinemia in auditory and other brain regions.

Strategies for neonatal hyperbilirubinemia: a literature review

"Common" neonatal jaundice can lead to dangerous levels of hyperbilirubinemia, causing neurological damage and even death. This article outlines evidence-based assessment techniques, management guidelines, and treatments for neonatal hyperbilirubinemia, addressing complexities that have arisen with new technologies and research results. We also explicate the role of the nurse in both prevention and care of patients and families who are affected by hyperbilirubinemia and jaundice.

Low-cost home-use light-emitting-diode phototherapy as an alternative to conventional methods

BACKGROUND

The aim of our study was to evaluate whether a portable, light-weight, light-emitting-diode phototherapy unit designed for home use is as effective as conventional blue-light fluorescent phototherapy (CFP) for treating hyperbilirubinemia in neonates.

METHODS

A total of 50 patients were recruited sequentially for treatment using CFP (n = 25) and the home-type phototherapy unit (n = 25).

RESULTS

The average rate of decrease in bilirubin levels was 0.17 ± 0.02 and 0.20 ± 0.01 mg/dL/hours at the end of 24 hours in the groups receiving phototherapy by CFP and home-type phototherapy units, respectively. There was no statistically significant difference in the rate of the decrease in bilirubin levels between the groups (p = 0.104).

CONCLUSIONS

It has been shown that the home-type phototherapy unit is as effective as CFP units in the treatment of neonatal hyperbilirubinemia and has the potential to become a standard of care for treatment of jaundiced neonates.

Clinical and pharmacogenetic factors affecting neonatal bilirubinemia following atazanavir treatment of mothers during pregnancy

A theoretical concern exists that atazanavir (ATV) use during pregnancy may exacerbate physiologic neonatal hyperbilirubinemia. The aim of this substudy was to evaluate patterns of neonatal bilirubin following ATV/ritonavir (RTV) treatment of pregnant mothers and clinical and pharmacogenetic factors that may correlate. The design involved a subanalysis of study AI424182, a multicenter, open-label, prospective, single-arm Phase I study. The study had two treatment arms: (1) ATV/RTV 300/100 mg once daily or (2) ATV/RTV 400/100 mg once daily, both in combination with zidovudine/lamivudine 300/150 mg twice daily. Total bilirubin was assessed at baseline, each visit, and delivery day for mothers and on days 1 (delivery day), 3, 5, and 7 and weeks 2 and 6 for neonates. Blood samples were obtained for UGT1A1 genotyping and ATV cord blood concentration. Bilirubin elevation of any grade occurred in 14/40 neonates (35%). All Grade 3 to 4 bilirubin abnormalities (n=7) occurred after day 14. The pattern of neonatal bilirubin levels reported was consistent with neonatal physiologic elevations of bilirubin. Little correlation was observed between either maternal bilirubin levels over the last 4 weeks of pregnancy (including delivery) or ATV cord concentration and neonatal bilirubin. There was a significant association between UGT1A1 genotype and bilirubin grade in the maternal population (p=0.0006) but not neonates (p=0.49). Neither neonatal UGT1A1 genotype nor cord blood ATV concentration is a good predictor of neonatal hyperbilirubinemia. ATV/RTV treatment of mothers does not appear to exacerbate neonatal physiologic hyperbilirubinemia.

Taurine attenuates bilirubin-induced neurotoxicity in the auditory system in neonatal guinea pigs

OBJECTIVES

Previous work showed that taurine protects neurons against unconjugated bilirubin (UCB)-induced neurotoxicity by maintaining intracellular calcium homeostasis, membrane integrity, and mitochondrial function, thereby preventing apoptosis from occurring, in primary neuron cultures. In this study, we investigated whether taurine could protect the auditory system against the neurotoxicity associated with hyperbilirubinemia in an in vivo model.

METHODS

Hyperbilirubinemia was established in neonatal guinea pigs by intraperitoneal injection of UCB. Hearing function was observed in electrocochleograms (ECochGs) and auditory brainstem responses (ABRs) recorded before and 1, 8, 24, and 72 h after UCB injection. For morphological evaluations, animals were sacrificed at 8h post-injection, and the afferent terminals beneath the inner hair cells (IHCs), spiral ganglion neurons (SGNs), and their fibers were examined.

RESULTS

It was found that UCB injection significantly increased latencies and inter-wave intervals, and thresholds of ABR and compound action potentials, and caused marked damage to type I SGNs, their axons, and terminals to cochlear IHCs. When baby guinea pigs were pretreated with taurine for 5 consecutive days and then injected with bilirubin, electrophysiological abnormalities and morphological damage were attenuated significantly in both the peripheral and central auditory system.

CONCLUSIONS

From these observations, it was concluded that taurine limited bilirubin-induced neural damage in the auditory system. These findings may contribute to the development of taurine as a broad-spectrum agent for preventing and/or treating hearing loss in neonatal jaundice.