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Pranty AI, Shumka S, Adjaye J. Bilirubin-Induced Neurological Damage: Current and Emerging iPSC-Derived Brain Organoid Models. Cells 2022; 11:cells11172647. [PMID: 36078055 PMCID: PMC9454749 DOI: 10.3390/cells11172647] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 08/04/2022] [Accepted: 08/17/2022] [Indexed: 11/16/2022] Open
Abstract
Bilirubin-induced neurological damage (BIND) has been a subject of studies for decades, yet the molecular mechanisms at the core of this damage remain largely unknown. Throughout the years, many in vivo chronic bilirubin encephalopathy models, such as the Gunn rat and transgenic mice, have further elucidated the molecular basis of bilirubin neurotoxicity as well as the correlations between high levels of unconjugated bilirubin (UCB) and brain damage. Regardless of being invaluable, these models cannot accurately recapitulate the human brain and liver system; therefore, establishing a physiologically recapitulating in vitro model has become a prerequisite to unveil the breadth of complexities that accompany the detrimental effects of UCB on the liver and developing human brain. Stem-cell-derived 3D brain organoid models offer a promising platform as they bear more resemblance to the human brain system compared to existing models. This review provides an explicit picture of the current state of the art, advancements, and challenges faced by the various models as well as the possibilities of using stem-cell-derived 3D organoids as an efficient tool to be included in research, drug screening, and therapeutic strategies for future clinical applications.
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Abstract
Schizophrenia is a complex syndrome of unknown etiology and difficult to manage. Unconjugated bilirubin has been researched as a potential biological marker of this syndrome. The objective of this review article was to gather the studies published to date on the relationship between this molecule and schizophrenia. Broad inclusion criteria have been used (PRISMA) to include as many relevant studies as possible. Fourteen studies were selected: 3 analyzed the effects of unconjugated hyperbilirubinemia in animal models; 6 demonstrated an increased incidence of schizophrenia in patients with increased unconjugated bilirubin; 2 reported an increased incidence of the disease in patients with decreased unconjugated bilirubin; and 3 linked an increased incidence of schizophrenia with an increased excretion of the oxidative product of bilirubin, the so-called biopyrrins. Because of apparently contradictory reported results, the hypothesis that the relationship between schizophrenia and unconjugated bilirubin was not linear and that there was an inflammatory dysfunction explaining this was considered. The 2 most accepted models for the pathophysiology of schizophrenia are described, and the possible role of the molecule in each is clarified. The bilirubin buffer system and its role in antioxidant defense was explored. The average levels of unconjugated bilirubin in patients with schizophrenia, schizoaffective disorder, and bipolar disorder were also compared, having been hypothesized that these diseases could be different points of a same pathological spectrum. Finally, it was concluded that unconjugated bilirubin is a promising molecule that could be used as a possible biological marker for schizophrenia, and the necessity of subsequent efforts for its research was considered.
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Palmela I, Correia L, Silva RFM, Sasaki H, Kim KS, Brites D, Brito MA. Hydrophilic bile acids protect human blood-brain barrier endothelial cells from disruption by unconjugated bilirubin: an in vitro study. Front Neurosci 2015; 9:80. [PMID: 25821432 PMCID: PMC4358072 DOI: 10.3389/fnins.2015.00080] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2014] [Accepted: 02/24/2015] [Indexed: 12/13/2022] Open
Abstract
Ursodeoxycholic acid and its main conjugate glycoursodeoxycholic acid are bile acids with neuroprotective properties. Our previous studies demonstrated their anti-apoptotic, anti-inflammatory, and antioxidant properties in neural cells exposed to elevated levels of unconjugated bilirubin (UCB) as in severe jaundice. In a simplified model of the blood-brain barrier, formed by confluent monolayers of a cell line of human brain microvascular endothelial cells, UCB has shown to induce caspase-3 activation and cell death, as well as interleukin-6 release and a loss of blood-brain barrier integrity. Here, we tested the preventive and restorative effects of these bile acids regarding the disruption of blood-brain barrier properties by UCB in in vitro conditions mimicking severe neonatal hyperbilirubinemia and using the same experimental blood-brain barrier model. Both bile acids reduced the apoptotic cell death induced by UCB, but only glycoursodeoxycholic acid significantly counteracted caspase-3 activation. Bile acids also prevented the upregulation of interleukin-6 mRNA, whereas only ursodeoxycholic acid abrogated cytokine release. Regarding barrier integrity, only ursodeoxycholic acid abrogated UCB-induced barrier permeability. Better protective effects were obtained by bile acid pre-treatment, but a strong efficacy was still observed by their addition after UCB treatment. Finally, both bile acids showed ability to cross confluent monolayers of human brain microvascular endothelial cells in a time-dependent manner. Collectively, data disclose a therapeutic time-window for preventive and restorative effects of ursodeoxycholic acid and glycoursodeoxycholic acid against UCB-induced blood-brain barrier disruption and damage to human brain microvascular endothelial cells.
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Affiliation(s)
- Inês Palmela
- Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa Lisbon, Portugal
| | - Leonor Correia
- Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa Lisbon, Portugal ; Department of Biochemistry and Human Biology, Faculdade de Farmácia, Universidade de Lisboa Lisbon, Portugal
| | - Rui F M Silva
- Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa Lisbon, Portugal ; Department of Biochemistry and Human Biology, Faculdade de Farmácia, Universidade de Lisboa Lisbon, Portugal
| | - Hiroyuki Sasaki
- Division of Fine Morphology, Core Research Facilities, The Jikei University School of Medicine Tokyo Japan
| | - Kwang S Kim
- Division of Infectious Diseases, Johns Hopkins University School of Medicine Baltimore, MA, USA
| | - Dora Brites
- Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa Lisbon, Portugal ; Department of Biochemistry and Human Biology, Faculdade de Farmácia, Universidade de Lisboa Lisbon, Portugal
| | - Maria A Brito
- Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa Lisbon, Portugal ; Department of Biochemistry and Human Biology, Faculdade de Farmácia, Universidade de Lisboa Lisbon, Portugal
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Cytochrome P450 2A5 and bilirubin: Mechanisms of gene regulation and cytoprotection. Toxicol Appl Pharmacol 2013; 270:129-38. [DOI: 10.1016/j.taap.2013.04.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 04/16/2013] [Accepted: 04/18/2013] [Indexed: 12/19/2022]
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Wang Y, Zhu Q, Luo C, Zhang A, Hei Z, Su G, Xia Z, Irwin MG. Dual Effects of Bilirubin on the Proliferation of Rat Renal NRK52E Cells and ITS Association with Gap Junctions. Dose Response 2012; 11:220-37. [PMID: 23930103 PMCID: PMC3682199 DOI: 10.2203/dose-response.12-003.hei] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
OBJECTIVE The effect of bilirubin on renal pathophysiology is controversial. This study aimed to observe the effects of bilirubin on the proliferation of normal rat renal tubular epithelial cell line (NRK52E) and its potential interplay with gap junction function. METHODS Cultured NRK52E cells, seeded respectively at high- or low- densities, were treated with varying concentrations of bilirubin for 24 hours. Cell injury was assessed by measuring cell viability and proliferation, and gap junction function was assessed by Parachute dye-coupling assay. Connexin 43 protein was assessed by Western blotting. RESULTS At doses from 17.1 to 513μmol/L, bilirubin dose-dependently enhanced cell viability and colony-formation rates when cells were seeded at either high- or low- densities (all p<0.05 vs. solvent group) accompanied with enhanced intercellular fluorescence transmission and increased Cx43 protein expression in high-density cells. However, the above effects of BR were gradually reversed when its concentration increased from 684 to 1026μmol/L. In high-density cells, gap junction inhibitor 12-O-tetradecanoylphorbol 13-acetate attenuated bilirubin-induced enhancement of colony-formation and fluorescence transmission. However, in the presence of high concentration bilirubin (1026μmol/L), activation of gap junction with retinoid acid decreased colony-formation rates. CONCLUSION Bilirubin can confer biphasic effects on renal NRK52E cell proliferation potentially by differentially affecting gap junction functions.
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Affiliation(s)
- Yanling Wang
- Department of anesthesiology, the third affiliated hospital of Sun Yat-sen university. NO.600 Tianhe Road, Tianhe district, Guangzhou, China, 510630
| | - Qiongfang Zhu
- Department of Anesthesiology, the first affiliated hospital of Sun Yat-sen university. NO.58, Zhongshan Road II, Yuexiu district, Guangzhou, China
| | - Chenfang Luo
- Department of anesthesiology, the third affiliated hospital of Sun Yat-sen university. NO.600 Tianhe Road, Tianhe district, Guangzhou, China, 510630
| | - Ailan Zhang
- Department of anesthesiology, the third affiliated hospital of Sun Yat-sen university. NO.600 Tianhe Road, Tianhe district, Guangzhou, China, 510630
| | - Ziqing Hei
- Department of anesthesiology, the third affiliated hospital of Sun Yat-sen university. NO.600 Tianhe Road, Tianhe district, Guangzhou, China, 510630
| | - Guangjie Su
- Department of anesthesiology, the third affiliated hospital of Sun Yat-sen university. NO.600 Tianhe Road, Tianhe district, Guangzhou, China, 510630
| | - Zhengyuan Xia
- Department of Anesthesiology, University of Hong Kong. Room 424, 4th Floor, Block K, Queen Mary Hospital, 102 Pokfulam Road, Hong Kong, China
| | - Michael G. Irwin
- Department of Anesthesiology, University of Hong Kong. Room 424, 4th Floor, Block K, Queen Mary Hospital, 102 Pokfulam Road, Hong Kong, China
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Brites D. The evolving landscape of neurotoxicity by unconjugated bilirubin: role of glial cells and inflammation. Front Pharmacol 2012; 3:88. [PMID: 22661946 PMCID: PMC3361682 DOI: 10.3389/fphar.2012.00088] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Accepted: 04/23/2012] [Indexed: 12/13/2022] Open
Abstract
Unconjugated hyperbilirubinemia is a common condition in the first week of postnatal life. Although generally harmless, some neonates may develop very high levels of unconjugated bilirubin (UCB), which may surpass the protective mechanisms of the brain in preventing UCB accumulation. In this case, both short-term and long-term neurodevelopmental disabilities, such as acute and chronic UCB encephalopathy, known as kernicterus, or more subtle alterations defined as bilirubin-induced neurological dysfunction (BIND) may be produced. There is a tremendous variability in babies' vulnerability toward UCB for reasons not yet explained, but preterm birth, sepsis, hypoxia, and hemolytic disease are comprised as risk factors. Therefore, UCB levels and neurological abnormalities are not strictly correlated. Even nowadays, the mechanisms of UCB neurotoxicity are still unclear, as are specific biomarkers, and little is known about lasting sequelae attributable to hyperbilirubinemia. On autopsy, UCB was shown to be within neurons, neuronal processes, and microglia, and to produce loss of neurons, demyelination, and gliosis. In isolated cell cultures, UCB was shown to impair neuronal arborization and to induce the release of pro-inflammatory cytokines from microglia and astrocytes. However, cell dependent sensitivity to UCB toxicity and the role of each nerve cell type remains not fully understood. This review provides a comprehensive insight into cell susceptibilities and molecular targets of UCB in neurons, astrocytes, and oligodendrocytes, and on phenotypic and functional responses of microglia to UCB. Interplay among glia elements and cross-talk with neurons, with a special emphasis in the UCB-induced immunostimulation, and the role of sepsis in BIND pathogenesis are highlighted. New and interesting data on the anti-inflammatory and antioxidant activities of different pharmacological agents are also presented, as novel and promising additional therapeutic approaches to BIND.
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Affiliation(s)
- Dora Brites
- Neuron Glia Biology in Health and Disease Unit, Research Institute for Medicines and Pharmaceutical Sciences, Faculty of Pharmacy, University of Lisbon Lisbon, Portugal
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Bajo-Grañeras R, Ganfornina MD, Martín-Tejedor E, Sanchez D. Apolipoprotein D mediates autocrine protection of astrocytes and controls their reactivity level, contributing to the functional maintenance of paraquat-challenged dopaminergic systems. Glia 2011; 59:1551-66. [PMID: 21688324 DOI: 10.1002/glia.21200] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Accepted: 05/23/2011] [Indexed: 01/10/2023]
Abstract
The study of glial derived factors induced by injury and degeneration is important to understand the nervous system response to deteriorating conditions. We focus on Apolipoprotein D (ApoD), a Lipocalin expressed by glia and strongly induced upon aging, injury or neurodegeneration. Here we study ApoD function in the brain of wild type and ApoD-KO mice by combining in vivo experiments with astrocyte cultures. Locomotor performance, dopamine concentration, and gene expression levels in the substantia nigra were assayed in mice treated with paraquat (PQ). The regulation of ApoD transcription, a molecular screening of oxidative stress (OS)-related genes, cell viability and oxidation status, and the effects of adding human ApoD were tested in astrocyte cultures. We demonstrate that (1) ApoD is required for an adequate locomotor performance, modifies the gene expression profile of PQ-challenged nigrostriatal system, and contributes to its functional maintenance; (2) ApoD expression in astrocytes is controlled by the OS-responsive JNK pathway; (3) ApoD contributes to an autocrine protecting mechanism in astrocytes, avoiding peroxidated lipids accumulation and altering the PQ transcriptional response of genes involved in ROS managing and the inflammatory response to OS; (4) Addition of human ApoD to ApoD-KO astrocytes promotes survival through a mechanism accompanied by protein internalization and modulation of astroglial reactivity. Our data support that ApoD contributes to the endurance of astrocytes and decreases their reactivity level in vitro and in vivo. ApoD function as a maintenance factor for astrocytes would suffice to explain the observed protection by ApoD of OS-vulnerable dopaminergic circuits in vivo.
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Affiliation(s)
- Raquel Bajo-Grañeras
- Instituto de Biología y Genética Molecular-Departamento de Bioquímica y Biología Molecular y Fisiología, Universidad de Valladolid-CSIC, Valladolid, Spain
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Abstract
Encephalopathy by hyperbilirubinemia in infants has been described for decades, but neither the underlying cellular and molecular mechanisms nor the selective pattern of bilirubin deposition in the brain is well understood. The brain is composed of highly specialized and diverse populations of cells, represented by neurons and glia that comprise astrocytes, oligodendrocytes, and microglia. Although microscopic evaluation of icteric brain sections revealed bilirubin within neurons, neuronal processes, and microglia, cell dependent-sensitivity to bilirubin toxicity and the role of each nerve cell type are poorly understood. Even less considered are glial and neuronal pathologic alterations as integrated phenomena. The available knowledge on reactivity of glial cells to bilirubin and on the impairment to neuronal network dynamics that it causes, here summarized, suggests that a better comprehension of the interplay between neurons and glia is essential to understand bilirubin neurotoxicity and highlight potential molecular targets that may lead to disease-modifying therapeutic approaches.
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Affiliation(s)
- Dora Brites
- Research Institute for Medicines and Pharmaceutical Sciences (iMedUL), Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal.
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Shapiro SM, Popelka GR. Auditory impairment in infants at risk for bilirubin-induced neurologic dysfunction. Semin Perinatol 2011; 35:162-70. [PMID: 21641490 DOI: 10.1053/j.semperi.2011.02.011] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Classical and subtypes of kernicterus associated with bilirubin toxicity can be differentiated in part with physiological auditory measures that include auditory-evoked potentials and measures of cochlear integrity. The combination of these auditory measures suggests that bilirubin exposure results in auditory system damage initially at the level of the brainstem, progressing to the level of the VIII cranial nerve and then to greater neural centers. There is no evidence of neural damage at the level of the cochlea. Auditory neural damage from bilirubin toxicity ranges from neural timing deficits, including neural firing delays and dyssynchrony, to neural response reduction and even elimination of auditory neural responses. This condition is comprehensively described as auditory neuropathy spectrum disorder. Independent measures of cochlear function and auditory neural function up to the level of the brainstem can effectively diagnose auditory neural damage resulting from bilirubin neurotoxicity. Intervention, including cochlear implants can be effective.
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Affiliation(s)
- Steven M Shapiro
- Division of Child Neurology, Department of Neurology, Medical College of Virginia Campus, Virginia Commonwealth University Medical Center, Richmond, VA 23298-0211, USA.
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10
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Oakes GH, Bend JR. Global changes in gene regulation demonstrate that unconjugated bilirubin is able to upregulate and activate select components of the endoplasmic reticulum stress response pathway. J Biochem Mol Toxicol 2010; 24:73-88. [PMID: 20196124 DOI: 10.1002/jbt.20313] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Elevated concentrations of unconjugated bilirubin (UCB) are responsible for neonatal jaundice and can eventually lead to kernicterus or death. The molecular mechanism of UCB toxicity is incompletely elucidated. The purpose of this study was to analyze changes in gene regulation mediated by UCB to determine novel pathways that contribute to UCB-mediated toxicity. We employed microarray analysis to determine changes in gene regulation mediated by UCB at both pro- (50 microM) and antioxidant (70 nM) concentrations in Hepa 1c1c7 cells at 1 and 6 h. The changes observed in select genes were validated with qPCR. Using immunoblot analysis, we validated these changes at the protein level for select genes and documented the activation of two proteins involved in the endoplasmic reticulum (ER) stress pathway, eIF2 alpha and PERK. Following treatment with 50 microM UCB, microarray analysis revealed the upregulation of many genes involved in ER stress (ATF3, BiP, CHOP, Dnajb1, and Herp). We demonstrate that upregulation of the proapoptotic transcription factor CHOP results in increased intracellular protein content. It was determined that activation of proteins involved in ER stress was an early event in UCB toxicity as eIF2 alpha and PERK were both phosphorylated and activated by 1 h posttreatment. We also demonstrate that procaspase-12 content, a proposed initiator caspase in ER stress-mediated apoptosis, is decreased by 4 h posttreatment. In conclusion, this study demonstrates that elevated concentrations of UCB (50 microM) are able to activate select components of the ER stress pathway in Hepa 1c1c7 cells, which may contribute to UCB-mediated apoptosis.
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Affiliation(s)
- Garth H Oakes
- Department of Physiology & Pharmacology, Siebens-Drake Medical Research Institute, Schulich School of Medicine & Dentistry, University of Western Ontario, 1400 Western Road, London, Ontario, Canada
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Taurine protects against bilirubin-induced neurotoxicity in vitro. Brain Res 2010; 1320:159-67. [DOI: 10.1016/j.brainres.2010.01.036] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Revised: 01/13/2010] [Accepted: 01/13/2010] [Indexed: 02/03/2023]
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12
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Chang FY, Lee CC, Huang CC, Hsu KS. Unconjugated bilirubin exposure impairs hippocampal long-term synaptic plasticity. PLoS One 2009; 4:e5876. [PMID: 19517010 PMCID: PMC2690688 DOI: 10.1371/journal.pone.0005876] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Accepted: 05/14/2009] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Jaundice is one of the most common problems encountered in newborn infants, due to immaturity of hepatic conjugation and transport processes for bilirubin. Although the majority of neonatal jaundice is benign, some neonates with severe hyperbilirubinemia develop bilirubin encephalopathy or kernicterus. Accumulation of unconjugated bilirubin (UCB) in selected brain regions may result in temporary or permanent impairments of auditory, motor, or cognitive function; however, the molecular mechanisms by which UCB elicits such neurotoxicity are still poorly understood. The present study is undertaken to investigate whether prolonged exposure of rat organotypic hippocampal slice cultures to UCB alters the induction of long-term synaptic plasticity. METHODOLOGY/PRINCIPAL FINDINGS Using electrophysiological recording techniques, we find that exposure of hippocampal slice cultures to clinically relevant concentrations of UCB for 24 or 48 h results in an impairment of CA1 long-term potentiation (LTP) and long-term depression (LTD) induction in a time- and concentration-dependent manner. Hippocampal slice cultures stimulated with UCB show no changes in the secretion profiles of the pro-inflammatory cytokines, interleukin-1beta and tumor necrosis factor-alpha, or the propidium ioide uptake. UCB treatment produced a significant decrease in the levels of NR1, NR2A and NR2B subunits of N-methyl-D-aspartate (NMDA) receptors through a calpain-mediated proteolytic cleavage mechanism. Pretreatment of the hippocampal slice cultures with NMDA receptor antagonist or calpain inhibitors effectively prevented the UCB-induced impairment of LTP and LTD. CONCLUSION/SIGNIFICANCE Our results indicate that the proteolytic cleavage of NMDA receptor subunits by calpain may play a critical role in mediating the UCB-induced impairment of long-term synaptic plasticity in the hippocampus. These observations provide new insights into the molecular mechanisms underlying UCB-induced impairment of hippocampal synaptic plasticity which, in turn, might provide opportunities for the development of novel therapeutic strategies that targets these pathways for treatment.
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Affiliation(s)
- Fang-Yu Chang
- Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Cheng-Che Lee
- Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Chiung-Chun Huang
- Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Kuei-Sen Hsu
- Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
- Center for Gene Regulation and Signal Transduction Research, National Cheng Kung University, Tainan, Taiwan
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Fernandes A, Vaz AR, Falcão AS, Silva RFM, Brito MA, Brites D. Glycoursodeoxycholic Acid and Interleukin-10 Modulate the Reactivity of Rat Cortical Astrocytes to Unconjugated Bilirubin. J Neuropathol Exp Neurol 2007; 66:789-98. [PMID: 17805009 DOI: 10.1097/nen.0b013e3181461c74] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The pathogenesis of bilirubin encephalopathy seems to result from accumulation of unconjugated bilirubin (UCB) within the brain. We have recently demonstrated that UCB causes astroglial release of proinflammatory cytokines and glutamate, as well as cell death. The bile acid glycoursodeoxycholic acid (GUDCA) and the anti-inflammatory cytokine interleukin (IL)-10 have been reported to modulate inflammation and cell survival. In this study we investigated the effect of these therapeutic agents on the astroglial response to UCB. Only GUDCA prevented UCB-induced astroglial death. The secretion of tumor necrosis factor-alpha (TNF-alpha) and IL-1beta elicited by UCB in astrocytes was reduced in the presence of GUDCA and IL-10, whereas the suppression of IL-6 was only counteracted by GUDCA. Neither GUDCA nor IL-10 modulated the accumulation of extracellular glutamate. Additionally, IL-10 markedly inhibited UCB-induced nuclear factor-kappaB nuclear translocation and cytokine mRNA expression, whereas GUDCA only prevented TNF-alpha mRNA expression. Moreover, GUDCA inhibited TNF-alpha- and IL-1beta-converting enzymes, preventing the maturation of these cytokines and their consequent release. Collectively, this study shows that IL-10 action is restricted to UCB-induced release of TNF-alpha and IL-1beta from the astrocytes, whereas GUDCA presents a more ubiquitous action on the astroglial reactivity to UCB. Hence, GUDCA may have potential benefits over an IL-10 therapeutic approach in reducing UCB-induced astrocyte immunostimulation and death.
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Affiliation(s)
- Adelaide Fernandes
- Centro de Patogénese Molecular-Unidade de Biologia Molecular e Biopatologia Experimental, and Research Institute for Medicines and Pharmaceutical Sciences, Faculdade de Farmácia, University of Lisbon, Lisbon, Portugal
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Hankø E, Hansen TWR, Almaas R, Rootwelt T. Recovery after short-term bilirubin exposure in human NT2-N neurons. Brain Res 2006; 1103:56-64. [PMID: 16814266 DOI: 10.1016/j.brainres.2006.05.083] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2005] [Revised: 05/13/2006] [Accepted: 05/17/2006] [Indexed: 11/25/2022]
Abstract
We used human NT2-N neurons to investigate delayed effects of short-term exposure to unconjugated bilirubin (UCB). Cell viability was evaluated with MTT reduction assays and nuclear morphology. A 6-h exposure to 1, 5, or 25 microM UCB and serum deprivation (SED) significantly diminished MTT reduction. 96 h after rescue of neurons with removal of UCB and re-incubation in the original serum-containing medium, delayed effects were evident as recovery (1 microM UCB), intermediate cell death (5 microM UCB), or near complete cell death (25 microM UCB). The impact of 6 h of SED alone appeared to be modest in rescued neurons. In this model, co-treatment with the specific caspase-3 inhibitor, zDEVD.FMK (100 microM), or the pancaspase inhibitor zVAD.FMK (100 microM) did not improve viability in rescued neurons exposed to 5 microM UCB, while treatment with the NMDA receptor antagonist MK-801 (1 microM) enhanced the number of undamaged nuclei (86 +/- 14% versus 50 +/- 12%, P = 0.001). MK-801 had, however, no impact on MTT reduction. In a different model with a 102-h continuous exposure to UCB and SED, we found a significant additional toxic impact of serum deprivation. Separate experiments suggested that this was a result of late caspase-mediated toxicity. We conclude that UCB-mediated effects may be reversible in this model. Blockade of excitotoxic mechanisms, but not caspase activity may prevent delayed cell death.
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Affiliation(s)
- Erik Hankø
- Department of Pediatric Research, Rikshospitalet-Radiumhospitalet Medical Center, University of Oslo, Oslo, Norway.
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15
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Fernandes A, Falcão AS, Silva RFM, Gordo AC, Gama MJ, Brito MA, Brites D. Inflammatory signalling pathways involved in astroglial activation by unconjugated bilirubin. J Neurochem 2006; 96:1667-79. [PMID: 16476078 DOI: 10.1111/j.1471-4159.2006.03680.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
During neonatal hyperbilirubinaemia, astrocytes activated by unconjugated bilirubin (UCB) may contribute to brain toxicity through the production of cytokines. As a first step in addressing the signal transduction cascades involved in the UCB-induced astroglial immunological response, we tested whether tumour necrosis factor (TNF)-alpha receptor 1 (TNFR1), mitogen-activated protein kinase (MAPK) and nuclear factor kappaB (NF-kappaB) would be activated in astrocytes exposed to UCB, and examined the profile of cytokine production. Astrocyte cultures stimulated with UCB showed a rapid rise in TNFR1 protein levels, followed by activation of the MAPKs p38, Jun N-terminal kinase1/2 and extracellular signal-regulated kinase1/2, and NF-kappaB. Interestingly, the induction of these signal effectors preceded the early up-regulation of TNF-alpha and interleukin (IL)-1beta mRNAs, and later secretion of TNF-alpha, IL-1beta and IL-6. Treatment of astrocytes with UCB also induced cell death, with levels comparable to those obtained after exposure of astrocytes to recombinant TNF-alpha and IL-1beta. Moreover, loss of cell viability and cytokine secretion were reduced when the NF-kappaB signal transduction pathway was inhibited, suggesting a key role for NF-kappaB in the astroglial response to UCB. These results demonstrate the complexity of the molecular mechanisms involved in cell injury by UCB during hyperbilirubinaemia and provide a basis for the development of novel therapeutic strategies.
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MESH Headings
- Animals
- Animals, Newborn
- Astrocytes/drug effects
- Astrocytes/metabolism
- Bilirubin/metabolism
- Bilirubin/toxicity
- Brain/immunology
- Brain/metabolism
- Brain/physiopathology
- Cell Death/drug effects
- Cell Death/immunology
- Cells, Cultured
- Cytokines/immunology
- Cytokines/metabolism
- Cytokines/toxicity
- Encephalitis/etiology
- Encephalitis/immunology
- Encephalitis/metabolism
- Gliosis/etiology
- Gliosis/immunology
- Gliosis/metabolism
- Hyperbilirubinemia, Neonatal/immunology
- Hyperbilirubinemia, Neonatal/metabolism
- Hyperbilirubinemia, Neonatal/physiopathology
- MAP Kinase Signaling System/drug effects
- MAP Kinase Signaling System/physiology
- NF-kappa B/drug effects
- NF-kappa B/metabolism
- Nerve Degeneration/chemically induced
- Nerve Degeneration/immunology
- Nerve Degeneration/metabolism
- Rats
- Rats, Wistar
- Receptors, Tumor Necrosis Factor/drug effects
- Receptors, Tumor Necrosis Factor/metabolism
- Receptors, Tumor Necrosis Factor, Type I
- Signal Transduction/immunology
- Tumor Necrosis Factor Decoy Receptors
- Up-Regulation/drug effects
- Up-Regulation/immunology
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Affiliation(s)
- Adelaide Fernandes
- Centro de Patogénese Molecular, UBMBE, Faculdade de Farmácia, University of Lisbon, Lisbon, Portugal
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16
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Falcão AS, Fernandes A, Brito MA, Silva RFM, Brites D. Bilirubin-induced inflammatory response, glutamate release, and cell death in rat cortical astrocytes are enhanced in younger cells. Neurobiol Dis 2005; 20:199-206. [PMID: 16242628 DOI: 10.1016/j.nbd.2005.03.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2005] [Revised: 02/25/2005] [Accepted: 03/03/2005] [Indexed: 11/21/2022] Open
Abstract
Unconjugated bilirubin (UCB) encephalopathy is a predominantly early life condition resulting from the impairment of several cellular functions in the brain of severely jaundiced infants. However, only few data exist on the age-dependent effects of UCB and their association with increased vulnerability of premature newborns, particularly in a sepsis condition. We investigated cell death, glutamate efflux, and inflammatory cytokine dynamics after exposure of astrocytes at different stages of differentiation to clinically relevant concentrations of UCB and/or lipopolysaccharide (LPS). Younger astrocytes were more prone to UCB-induced cell death, glutamate efflux, and inflammatory response than older ones. Furthermore, in immature cells, LPS exacerbated UCB effects, such as cell death by necrosis. These findings provide a basis for the increased susceptibility of premature newborns to UCB deleterious effects, namely when associated with sepsis, and underline how crucial the course of cell maturation can be to UCB encephalopathy during moderate to severe neonatal jaundice.
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Affiliation(s)
- Ana S Falcão
- Centro de Patogénese Molecular (UBMBE), Faculdade de Farmácia, University of Lisbon, Av. Forças Armadas, 1600-083 Lisboa, Portugal
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17
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Abstract
Unconjugated bilirubin (UCB), at slightly elevated unbound concentrations, is toxic to astrocytes and neurons, damaging mitochondria (causing impaired energy metabolism and apoptosis) and plasma membranes (causing oxidative damage and disrupting transport of neurotransmitters). Accumulation of UCB in the CSF and CNS is limited by its active export, probably mediated by MRP1/Mrp1 present in choroid plexus epithelia, capillary endothelia, astrocytes and neurons. Upregulation of MRP1/Mrp1 protein levels by UCB might represent an important adaptive mechanism that protects the CNS from UCB toxicity. These concepts could explain the varied susceptibility of newborns to bilirubin neurotoxicity and the occurrence of neurological damage at plasma UCB concentrations well below therapeutic guidelines, and are relevant to the increasing prevalence of bilirubin encephalopathy in newborns.
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Affiliation(s)
- J Donald Ostrow
- Research Service, VA Puget Sound Health Care System-Seattle Division, and GI/Hepatology Division, Department of Medicine, University of Washington School of Medicine, Seattle, WA 98108-1597, USA
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18
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Brito MA, Brites D. Effect of acidosis on bilirubin-induced toxicity to human erythrocytes. Mol Cell Biochem 2003; 247:155-62. [PMID: 12841643 DOI: 10.1023/a:1024111613327] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Unconjugated bilirubin binds to erythrocytes, eliciting crenation, lipid elution and hemolysis. The present work attempts to establish the role of acidosis on bilirubin-induced toxicity to human erythrocytes. To this end, pH values ranging from 7.0-8.0 were used to induce a different representation of acid and anionic bilirubin species, respectively. Erythrocytes from healthy donors were incubated with bilirubin and albumin (3:1, molar ratio), during 4 h. Erythrocyte-bound bilirubin was evaluated by albumin or chloroform extraction in an attempt to assess either mono- and dianion bilirubin adsorbed on the cell surface or colloidal aggregates, respectively. Cytotoxicity indicators, such as the morphological index, and the extent of phospholipids and hemoglobin release were also determined. The results showed that as pH drops from 8.0-7.0, less bilirubin is removed by albumin and more become recovered by chloroform. The data corroborate the predominance of anionic and non-aggregated bilirubin species at pH 8.0 with dimers and precipitates occurring at 7.0. In accordance, crenation and cell lysis were four times increased at acidic pH. In contrast, elution of phospholipids was 1.5 times less evident at the same pH, thus suggesting that formation of bilirubin complexes with membrane phospholipids may have contributed to prevent their release. In conclusion, both anionic and acid bilirubin species interact with human erythrocytes leading to cytotoxic alterations that may determine definitive lesions. Nevertheless, increased vulnerability to crenation and hemolysis are more likely to occur in acidic conditions pointing to the bilirubin precipitates as the main candidates of bilirubin-induced toxicity to erythrocytes.
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Affiliation(s)
- Maria Alexandra Brito
- Centro de Patogénese Molecular, Faculdade de Farmácia, University of Lisbon, Lisbon, Portugal.
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19
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Silva RFM, Rodrigues CMP, Brites D. Rat cultured neuronal and glial cells respond differently to toxicity of unconjugated bilirubin. Pediatr Res 2002; 51:535-41. [PMID: 11919342 DOI: 10.1203/00006450-200204000-00022] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
High levels of unconjugated bilirubin (UCB) can be neurotoxic. Nevertheless, the mechanism of UCB interaction with neural cells is still unknown. This study investigates whether cultured rat neurons and astrocytes respond differently to UCB exposure. UCB toxicity was evaluated by lactate dehydrogenase release, induction of apoptosis, cytoskeleton degeneration, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction, and glutamate uptake. Primary cultures of rat brain astrocytes and neurons were incubated at 37 degrees C with 85.5 microM UCB plus 28.5 microM albumin for 4 h. In assays of glutamate uptake, cells were exposed to 80-120 microM UCB plus 100 microM albumin for 15 min. The results showed that after incubation with 85.5 microM UCB, lactate dehydrogenase release was greater in neurons than in astrocytes (38% versus 14%, p < 0.05). Also, levels of apoptosis were markedly enhanced in neurons (29% versus 19%, p < 0.01). In accordance, neuronal cytoskeleton disassembly was evident during incubation with 85.5 microM UCB, whereas equivalent effects on astrocytes required as much as 171 microM. Conversely, inhibition of MTT metabolism and glutamate uptake by UCB was more pronounced in astrocytes than in neurons (74% versus 60%, p < 0.05 and 41% to 56% versus 25% to 33%, p < 0.05, respectively). In conclusion, the study demonstrates that astrocytes are more susceptible to inhibition of glutamate uptake and MTT reduction by UCB, whereas neurons are more sensitive to cell death by necrosis or apoptosis. These results suggest that UCB is toxic to both astrocytes and neurons, although through distinct pathways.
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Affiliation(s)
- Rui F M Silva
- Centro de Patogénese Molecular, Faculdade de Farmácia, University of Lisbon, Lisbon, Portugal
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20
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Affiliation(s)
- Adam Jonas
- Department of Pediatrics, Harbor-UCLA Medical Center, Torrance, CA, U.S.A
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