RESUMEN
BACKGROUND & AIMS: Liver tight junctions (TJs) establish tissue barriers that isolate bile from the blood circulation. TJP2/ZO-2-inactivating mutations cause progressive cholestatic liver disease in humans. Because the underlying mechanisms remain elusive, we characterized mice with liver-specific inactivation of Tjp2. METHODS: Tjp2 was deleted in hepatocytes, cholangiocytes, or both. Effects on the liver were assessed by biochemical analyses of plasma, liver, and bile and by electron microscopy, histology, and immunostaining. TJ barrier permeability was evaluated using fluorescein isothiocyanate-dextran (4 kDa). Cholic acid (CA) diet was used to assess susceptibility to liver injury. RESULTS: Liver-specific deletion of Tjp2 resulted in lower Cldn1 protein levels, minor changes to the TJ, dilated canaliculi, lower microvilli density, and aberrant radixin and bile salt export pump (BSEP) distribution, without an overt increase in TJ permeability. Hepatic Tjp2-defcient mice presented with mild progressive cholestasis with lower expression levels of bile acid transporter Abcb11/Bsep and detoxification enzyme Cyp2b10. A CA diet tolerated by control mice caused severe cholestasis and liver necrosis in Tjp2-deficient animals. 1,4-Bis[2-(3,5-dichloropyridyloxy)]benzene ameliorated CA-induced injury by enhancing Cyp2b10 expression, and ursodeoxycholic acid provided partial improvement. Inactivating Tjp2 separately in hepatocytes or cholangiocytes showed only mild CA-induced liver injury. CONCLUSION: Tjp2 is required for normal cortical distribution of radixin, canalicular volume regulation, and microvilli density. Its inactivation deregulated expression of Cldn1 and key bile acid transporters and detoxification enzymes. The mice provide a novel animal model for cholestatic liver disease caused by TJP2-inactivating mutations in humans.
Asunto(s)
Canalículos Biliares/metabolismo , Enfermedad Hepática Inducida por Sustancias y Drogas/genética , Colestasis/genética , Uniones Estrechas/metabolismo , Proteína de la Zonula Occludens-2/genética , Miembro 11 de la Subfamilia B de Transportador de Casetes de Unión al ATP/genética , Miembro 11 de la Subfamilia B de Transportador de Casetes de Unión al ATP/metabolismo , Animales , Hidrocarburo de Aril Hidroxilasas/metabolismo , Ácidos y Sales Biliares/metabolismo , Canalículos Biliares/patología , Enfermedad Hepática Inducida por Sustancias y Drogas/tratamiento farmacológico , Colagogos y Coleréticos/uso terapéutico , Ácido Cólico , Claudina-1/metabolismo , Familia 2 del Citocromo P450/metabolismo , Proteínas del Citoesqueleto/metabolismo , Células Epiteliales , Femenino , Fibrosis , Predisposición Genética a la Enfermedad , Hepatocitos , Masculino , Proteínas de la Membrana/metabolismo , Ratones , Ratones Noqueados , Mutación , Oxazoles/uso terapéutico , Permeabilidad , Factores Protectores , ARN Mensajero/metabolismo , Esteroide Hidroxilasas/metabolismo , Uniones Estrechas/ultraestructura , Ácido Ursodesoxicólico/uso terapéutico , Proteína de la Zonula Occludens-2/deficienciaRESUMEN
Epstein-Barr virus (EBV) is associated with a variety of tumors and nonmalignant conditions. Latent EBV genomes in cells, including tumor cells, are often CpG methylated, whereas virion DNA is not CpG methylated. We demonstrate that methyl CpG binding magnetic beads can be used to fractionate among sources of EBV DNA (DNA extracted from laboratory-purified virions vs DNA extracted from latently infected cell lines). We then applied the technique to plasma specimens and showed that this technique can distinguish EBV DNA from patients with EBV-associated tumors (nasopharyngeal carcinoma, Hodgkin lymphoma) and viral DNA from patients without EBV-associated tumors, including immunocompromised patients and patients with EBV(-) Hodgkin lymphoma.