Project description:Rotor syndrome is an autosomal recessive disorder characterized by conjugated hyperbilirubinemia, near-absent hepatic uptake of anionic diagnostics, and coproporphyrinuria. The mechanistic basis of other hyperbilirubinemia syndromes is largely understood, but that of Rotor syndrome has remained enigmatic. The existing paradigm of hepatic bilirubin excretion postulates a unidirectional elimination pathway: Uptake of conjugated bilirubin from blood by hepatocytes, glucuronidation of bilirubin, and excretion of conjugated bilirubin into bile by ABCC2, a canalicular bilirubin-glucuronide and xenobiotic export pump. An analogous view holds for drugs conjugated in the liver. Here we demonstrate by molecular-genetic analysis of 8 Rotor-syndrome families that Rotor syndrome is a two-gene disorder, with impaired hepatic re-uptake of bilirubin-glucuronide caused by complete deficiencies in the hepatic organic anion transporting polypeptides OATP1B1 and OATP1B3.
Project description:Neonatal hyperbilirubinemia (jaundice) is common in infants, with extremely preterm infants (EPT, <28 weeks gestational age) being at high risk for bilirubin-induced neurotoxicity, resulting in neurodevelopmental impairment. Hyperbilirubinemia is treated using phototherapy to lower unconjugated bilirubin levels. However, the benefits and risks of phototherapy in EPTs have not been well studied, and bilirubin at low levels may be protective as an antioxidant. Phototherapy is associated with markers of oxidative stress in the plasma, but the effects of phototherapy on the hippocampus (HPC) are not known. Bilirubin and insults associated with EPTs impair hippocampal development, a brain structure critical for cognitive function, but their underlying mechanisms remain unknown. The effects of hyperbilirubinemia and phototherapy on the HPC were studied using a Gunn rat model. Jaundiced (jj) and non-jaundiced (Nj) pups were subjected to phototherapy from postnatal day 4 (P4) through P6. The HPC was harvested and processed for RNA sequencing. Serum bilirubin levels were elevated in jj compared to Nj control rats. Phototherapy significantly lowered serum bilirubin levels in jj rats. Compared to Nj rats, 1294 genes were differentially expressed in the jj hippocampal transcriptome and mapped onto the nervous system development, inflammation, and ferroptosis signaling pathways. Phototherapy induces 3297 differentially-expressed genes (DEGs) in rat hippocampal transcriptome compared to untreated rats. These DEGs were annotated to pathways regulating synaptogenesis, long-term potentiation, and neurogenesis. Both hyperbilirubinemia and phototherapy altered expression of 407 genes, which mapped onto hippocampal plasticity functions, including neuritogenesis and long-term potentiation. Our study demonstrates a model for investigating molecular effects of hyperbilirubemia and phototherapy in an EPT-equivalent Gunn rat pup. Our data revealed the effects of hyperbilirubinemia and phototherapy on signaling pathways critical for hippocampal development and plasticity.
Project description:Severe presentations of malaria, arising from Plasmodium spp. infection, are often associated with accumulation of circulating bilirubin, a condition known as hyperbilirubinemia or jaundice of malaria. Whether this represents an adaptive or maladaptive response to Plasmodium spp. infection is not understood. Departing from the textbook view of hyperbilirubinemia reflecting a failure to excrete bilirubin, we demonstrate that bilirubin production by biliverdin reductase A (BLVRA) partakes in a host adaptive response to malaria. Genetic Blvra deletion exacerbated malaria mortality in mice; This was associated with a >10-fold increase in parasite burden, compared to control mice expressing BLVRA, which cleared the parasite and survived malaria. At concentrations in the range of jaundice of malaria, unconjugated bilirubin arrested the proliferation and killed asexual blood stages of the human-infective P. falciparum in vitro. This was associated with disruption of the parasite’s mitochondrion and food vacuole as well as with the accumulation of hemozoin in the parasite’s cytoplasm. Moreover, bilirubin inhibited hemozoin (β-hematin) synthesis in vitro, a vital heme-detoxifying pathway targeted by Quinoline-based antimalarial drugs such as chloroquine. In conclusion, hyperbilirubinemia represents an evolutionary conserved metabolite-based resistance mechanism against malaria.
2025-03-24 | GSE254821 | GEO
Project description:Hyperbilirubinemia and photosensitivity in southdown sheep
Project description:Rotor syndrome is an autosomal recessive disorder characterized by conjugated hyperbilirubinemia, near-absent hepatic uptake of anionic diagnostics, and coproporphyrinuria. The mechanistic basis of other hyperbilirubinemia syndromes is largely understood, but that of Rotor syndrome has remained enigmatic. The existing paradigm of hepatic bilirubin excretion postulates a unidirectional elimination pathway: Uptake of conjugated bilirubin from blood by hepatocytes, glucuronidation of bilirubin, and excretion of conjugated bilirubin into bile by ABCC2, a canalicular bilirubin-glucuronide and xenobiotic export pump. An analogous view holds for drugs conjugated in the liver. Here we demonstrate by molecular-genetic analysis of 8 Rotor-syndrome families that Rotor syndrome is a two-gene disorder, with impaired hepatic re-uptake of bilirubin-glucuronide caused by complete deficiencies in the hepatic organic anion transporting polypeptides OATP1B1 and OATP1B3. SNP genotyping was performed on 22 samples - 10 affected and 12 healthy siblings from 8 Rotor-syndrome families. Affymetrix GeneChip Command Console software was used for image processing and CEL files were processed by Affymetrix GTC using the BRLMM-P-Plus algorithm and regional GC correction configuration for Copy Number/LOH analysis. The HapMap270 file supplied by Affymetrix was used as the reference.
Project description:Hyperbilirubinemia and phototherapy differentially alter hippocampal transcriptomic patterns in a Gunn rat model of neonatal hyperbilirubinemia.
Project description:Bilirubin toxicity to the CNS has been widely studied for decades, and shown impacting potential toxic/adaptation mechanisms by a significant modulation of gene expression, suggesting that mechanisms having crucial role on the regulation of gene expression, such as epigenetic mechanisms, should have a strong impact in unconjugated bilirubin toxicity. In this work, we followed the levels of histone 3 acetylation (H3K14Ac) in the cerebellum (Cll) of the developing (2, 9, 17 days after the birth and in adult age) Gunn rat (the natural model for neonatal hyperbilirubinemia and kernicterus) by Western blot, discovering an age specific alteration of the H3K14Ac in the hyperbilirubinemic animals. Then, the H3K14Ac linked chromatin was immune-precipitated and submitted to sequencing (ChIP-Seq). The GeneOntology analysis revealed that almost the 45% of H3K14Ac ChiP-Seq TSS-promoter genes were involved in the CNS development.
2018-09-13 | GSE109145 | GEO
Project description:Beneficial changes in gut microbiota after phototherapy for neonatal hyperbilirubinemia
| PRJNA1096251 | ENA
Project description:Changes in the Gut Microbiota of Neonates with Hyperbilirubinemia Reaching Phototherapy Thresholds
Project description:Gunn rats bear a mutation within the uridine diphosphate glucuronosyltransferase-1A1 (Ugt1A1) gene resulting in high serum bilirubin levels as seen in Crigler-Najjar syndrome. In the present study, the Gunn rat was used as an animal model for heritable liver dysfunction. Human pluripotent stem cell-derived mesenchymal stem cells (iMSCs) were transplanted into Gunn rats after partial hepatectomy. The iMSCs engrafted and survived in the liver for up to 2 months without the need for immunosuppression. The transplanted iMSCs differentiated into functional hepatocytes and partially suppressed hyperbilirubinemia. Furthermore, human Albumin as well as the human immunomodulatory factors, RANTES and SERPINE1, were detected in the rat serum upon iMSC transplantation. The differentiation of iMSCs into hepatocytes was confirmed by qPCR and/or immunohistochemistry, detecting expression of human hepatocyte nuclear factor 4α, UGT1A1, cytokeratin 18, α-fetoprotein and Albumin. These findings indicate transplanted iMSCs differentiated into hepatocytes and thus contributed to tissue repair in an injury model of hepatocyte-based liver regeneration.