Kernicterus spectrum disorder is the permanent and highly disabling neurologic sequel of neonatal exposure to hyperbilirubinemia, presenting, among other symptoms, variable and untreatable motor disabilities. To search for potential biomolecular explanations, we used a Gunn rat colony exhibiting spontaneous hyperbilirubinemia and a large variability of motor deficits on a beam-walking test. Histological and microscopic analyses confirmed worsening damage in the cerebellum (Cll; hypoplasia, increased death of neurons, and disrupted astroglial structures) and parietal motor cortex (hCtx; increased cell sufferance and astrogliosis). Clustering and network analyses of transcriptomic data reveal rearrangement of the physiological expression patterns and signaling pathways associated with bilirubin neurotoxicity. Bilirubin content among hyperbilirubinemic (jj) animals is overlapped, which suggests that the amount of bilirubin challenge does not fully explain the tissue, transcriptomic, proteomic, and neurobehavioral alterations. The expression of nine genes involved in key postnatal brain development processes is permanently altered in a phenotype-dependent manner. Among them, Grm1, a metabotropic glutamatergic receptor involved in glutamate neurotoxicity, is consistently downregulated in both brain regions both at the transcriptomic and proteomic levels. Our results support the role of Grm1 and glutamate as biomolecular markers of ongoing bilirubin neurotoxicity, suggesting the possibility to improve diagnosis by 1H-MR spectroscopy.

• Keywords
• Grm1, Gunn rats, PKC3, calcium, dystonia, gene clustering, glutamate receptors, kernicterus spectrum disorder, neonatal jaundice, neurotoxicity,
• MeSH
• Bilirubin metabolism   MeSH
• Phenotype MeSH
• Kernicterus metabolism   genetics   MeSH
• Rats MeSH
• Disease Models, Animal MeSH
• Brain * metabolism   pathology   MeSH
• Animals, Newborn MeSH
• Hyperbilirubinemia, Neonatal * metabolism   genetics   pathology   MeSH
• Rats, Gunn MeSH
• Proteome * metabolism   MeSH
• Proteomics methods   MeSH
• Gene Expression Profiling MeSH
• Transcriptome * MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Bilirubin MeSH
• Proteome * MeSH

• Publication type
• Journal Article MeSH

• Publication type
• Journal Article MeSH
• Comment MeSH

The 'gold standard' treatment of severe neonatal jaundice is phototherapy with blue-green light, which produces more polar photo-oxidation products that are easily excreted via the bile or urine. The aim of this study was to compare the effects of bilirubin (BR) and its major photo-oxidation product lumirubin (LR) on the proliferation, differentiation, morphology, and specific gene and protein expressions of self-renewing human pluripotent stem cell-derived neural stem cells (NSC). Neither BR nor LR in biologically relevant concentrations (12.5 and 25 µmol/L) affected cell proliferation or the cell cycle phases of NSC. Although none of these pigments affected terminal differentiation to neurons and astrocytes, when compared to LR, BR exerted a dose-dependent cytotoxicity on self-renewing NSC. In contrast, LR had a substantial effect on the morphology of the NSC, inducing them to form highly polar rosette-like structures associated with the redistribution of specific cellular proteins (β-catenin/N-cadherin) responsible for membrane polarity. This observation was accompanied by lower expressions of NSC-specific proteins (such as SOX1, NR2F2, or PAX6) together with the upregulation of phospho-ERK. Collectively, the data indicated that both BR and LR affect early human neurodevelopment in vitro, which may have clinical relevance in phototherapy-treated hyperbilirubinemic neonates.

• Keywords
• bilirubin, neurodevelopment, phototherapy,
• Publication type
• Journal Article MeSH

Invasive bilirubin measurements remain the gold standard for the diagnosis and treatment of infants with severe neonatal hyperbilirubinemia. The present paper describes different methods currently available to assess hyperbilirubinemia in newborn infants. Novel point-of-care bilirubin measurement methods, such as the BiliSpec and the Bilistick, would benefit many newborn infants, especially in low-income and middle-income countries where the access to costly multi-analyzer in vitro diagnostic instruments is limited. Total serum bilirubin test results should be accurate within permissible limits of measurement uncertainty to be fit for clinical purposes. This implies correct implementation of internationally endorsed reference measurement systems as well as participation in external quality assessment programs. Novel analytic methods may, apart from bilirubin, include the determination of bilirubin photoisomers and bilirubin oxidation products in blood and even in other biological matrices. IMPACT: Key message: Bilirubin measurements in blood remain the gold standard for diagnosis and treatment of severe neonatal hyperbilirubinemia (SNH). External quality assessment (EQA) plays an important role in revealing inaccuracies in diagnostic bilirubin measurements. What does this article add to the existing literature? We provide analytic performance data on total serum bilirubin (TSB) as measured during recent EQA surveys. We review novel diagnostic point-of-care (POC) bilirubin measurement methods and analytic methods for determining bilirubin levels in biological matrices other than blood. Impact: Manufacturers should make TSB test results traceable to the internationally endorsed total bilirubin reference measurement system and should ensure permissible limits of measurement uncertainty.

• MeSH
• Bilirubin blood   MeSH
• Biomarkers blood   MeSH
• Humans MeSH
• Infant, Newborn MeSH
• Hyperbilirubinemia, Neonatal blood   diagnosis   therapy   MeSH
• Jaundice, Neonatal blood   diagnosis   therapy   MeSH
• Neonatal Screening * MeSH
• Point-of-Care Testing * MeSH
• Predictive Value of Tests MeSH
• Prognosis MeSH
• Reproducibility of Results MeSH
• Severity of Illness Index MeSH
• Up-Regulation MeSH
• Check Tag
• Humans MeSH
• Infant, Newborn MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH
• Names of Substances
• Bilirubin MeSH
• Biomarkers MeSH

For severe unconjugated hyperbilirubinemia the gold standard treatment is phototherapy with blue-green light, producing more polar photo-oxidation products, believed to be non-toxic. The aim of the present study was to compare the effects of bilirubin (BR) and lumirubin (LR), the major BR photo-oxidation product, on metabolic and oxidative stress markers. The biological activities of these pigments were investigated on several human and murine cell lines, with the focus on mitochondrial respiration, substrate metabolism, reactive oxygen species production, and the overall effects on cell viability. Compared to BR, LR was found to be much less toxic, while still maintaining a similar antioxidant capacity in the serum as well as suppressing activity leading to mitochondrial superoxide production. Nevertheless, due to its lower lipophilicity, LR was less efficient in preventing lipoperoxidation. The cytotoxicity of BR was affected by the cellular glycolytic reserve, most compromised in human hepatoblastoma HepG2 cells. The observed effects were correlated with changes in the production of tricarboxylic acid cycle metabolites. Both BR and LR modulated expression of PPARα downstream effectors involved in lipid and glucose metabolism. Proinflammatory effects of BR, evidenced by increased expression of TNFα upon exposure to bacterial lipopolysaccharide, were observed in murine macrophage-like RAW 264.7 cells. Collectively, these data point to the biological effects of BR and its photo-oxidation products, which might have clinical relevance in phototherapy-treated hyperbilirubinemic neonates and adult patients.

• Keywords
• antioxidant, bilirubin, cell respiration, intracellular metabolite, lumirubin,
• Publication type
• Journal Article MeSH

BACKGROUND: Severe hyperbilirubinemia can cause permanent neurological damage in particular in neonates, whereas mildly elevated serum bilirubin protects from various oxidative stress-mediated diseases. The present work aimed to establish the intracellular unconjugated bilirubin concentrations (iUCB) thresholds differentiating between anti- and pro-oxidant effects. METHODS: Hepatic (HepG2), heart endothelial (H5V), kidney tubular (HK2) and neuronal (SH-SY5Y) cell lines were exposed to increasing concentration of bilirubin. iUCB, cytotoxicity, intracellular reactive oxygen species (ROS) concentrations, and antioxidant capacity (50% efficacy concentration (EC50)) were determined. RESULTS: Exposure of SH-SY5Y to UCB concentration > 3.6 µM (iUCB of 25 ng/mg) and >15 µM in H5V and HK2 cells (iUCB of 40 ng/mg) increased intracellular ROS production (p < 0.05). EC50 of the antioxidant activity was 21 µM (iUCB between 5.4 and 21 ng/mg) in HepG2 cells, 0.68 µM (iUCB between 3.3 and 7.5 ng/mg) in SH-SY5Y cells, 2.4 µM (iUCB between 3 and 6.7 ng/mg) in HK2 cells, and 4 µM (iUCB between 4.7 and 7.5 ng/mg) in H5V cells. CONCLUSIONS: In all the cell lines studied, iUCB of around 7 ng/mg protein had antioxidant activities, while iUCB > 25 ng/mg protein resulted in a prooxidant and cytotoxic effects. UCB metabolism was found to be cell-specific resulting in different iUCB.

• Keywords
• ROS, antioxidant, bilirubin, bilirubin neurotoxicity, redox state,
• MeSH
• Antioxidants pharmacology   MeSH
• Bilirubin pharmacology   MeSH
• Carcinoma, Hepatocellular drug therapy   metabolism   pathology   MeSH
• Hyperbilirubinemia physiopathology   MeSH
• Humans MeSH
• Liver Neoplasms drug therapy   metabolism   pathology   MeSH
• Neuroblastoma drug therapy   metabolism   pathology   MeSH
• Oxidation-Reduction MeSH
• Oxidative Stress drug effects   MeSH
• Oxidants pharmacology   MeSH
• Reactive Oxygen Species metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Antioxidants MeSH
• Bilirubin MeSH
• Oxidants MeSH
• Reactive Oxygen Species MeSH

Bilirubin is a yellow endogenous derivate of the heme catabolism. Since the 1980s, it has been recognized as one of the most potent antioxidants in nature, able to counteract 10,000× higher intracellular concentrations of H2O2. In the recent years, not only bilirubin, but also its precursor biliverdin, and the enzymes involved in their productions (namely heme oxygenase and biliverdin reductase; altogether the "yellow players"-YPs) have been recognized playing a protective role in diseases characterized by a chronic prooxidant status. Based on that, there is an ongoing effort in inducing their activity as a therapeutic option. Nevertheless, the understanding of their specific contributions to pathological conditions of the central nervous system (CNS) and their role in these diseases are limited. In this review, we will focus on the most recent evidence linking the role of the YPs specifically to neurodegenerative and neurological conditions. Both the protective, as well as potentially worsening effects of the YP's activity will be discussed.

• Keywords
• bilirubin, bilirubin oxidation products, biliverdin, biliverdin reductase, central nervous system (CNS), heme, heme oxygenase, neurodegenerative diseases, yellow players,
• Publication type
• Journal Article MeSH
• Review MeSH