RESUMO
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.
Assuntos
Canalículos Biliares/metabolismo , Doença Hepática Induzida por Substâncias e Drogas/genética , Colestase/genética , Junções Íntimas/metabolismo , Proteína da Zônula de Oclusão-2/genética , Membro 11 da Subfamília B de Transportadores de Cassetes de Ligação de ATP/genética , Membro 11 da Subfamília B de Transportadores de Cassetes de Ligação de ATP/metabolismo , Animais , Hidrocarboneto de Aril Hidroxilases/metabolismo , Ácidos e Sais Biliares/metabolismo , Canalículos Biliares/patologia , Doença Hepática Induzida por Substâncias e Drogas/tratamento farmacológico , Colagogos e Coleréticos/uso terapêutico , Ácido Cólico , Claudina-1/metabolismo , Família 2 do Citocromo P450/metabolismo , Proteínas do Citoesqueleto/metabolismo , Células Epiteliais , Feminino , Fibrose , Predisposição Genética para Doença , Hepatócitos , Masculino , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Knockout , Mutação , Oxazóis/uso terapêutico , Permeabilidade , Fatores de Proteção , RNA Mensageiro/metabolismo , Esteroide Hidroxilases/metabolismo , Junções Íntimas/ultraestrutura , Ácido Ursodesoxicólico/uso terapêutico , Proteína da Zônula de Oclusão-2/deficiênciaRESUMO
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.