RESUMO
BACKGROUND AND AIMS: Hepatic crisis is an emergent complication affecting patients with sickle cell disease (SCD); however, the molecular mechanism of sickle cell hepatobiliary injury remains poorly understood. Using the knock-in humanized mouse model of SCD and SCD patient blood, we sought to mechanistically characterize SCD-associated hepato-pathophysiology applying our recently developed quantitative liver intravital imaging, RNA sequence analysis, and biochemical approaches. APPROACH AND RESULTS: SCD mice manifested sinusoidal ischemia, progressive hepatomegaly, liver injury, hyperbilirubinemia, and increased ductular reaction under basal conditions. Nuclear factor kappa B (NF-κB) activation in the liver of SCD mice inhibited farnesoid X receptor (FXR) signaling and its downstream targets, leading to loss of canalicular bile transport and altered bile acid pool. Intravital imaging revealed impaired bile secretion into the bile canaliculi, which was secondary to loss of canalicular bile transport and bile acid metabolism, leading to intrahepatic bile accumulation in SCD mouse liver. Blocking NF-κB activation rescued FXR signaling and partially ameliorated liver injury and sinusoidal ischemia in SCD mice. CONCLUSIONS: These findings identify that NF-κB/FXR-dependent impaired bile secretion promotes intrahepatic bile accumulation, which contributes to hepatobiliary injury of SCD. Improved understanding of these processes could potentially benefit the development of therapies to treat sickle cell hepatic crisis.
Assuntos
Anemia Falciforme/complicações , Bile/metabolismo , Colestase/etiologia , Insuficiência Hepática/etiologia , Fígado/patologia , Adolescente , Adulto , Anemia Falciforme/sangue , Anemia Falciforme/tratamento farmacológico , Anemia Falciforme/genética , Animais , Ductos Biliares Intra-Hepáticos/diagnóstico por imagem , Ductos Biliares Intra-Hepáticos/patologia , Colestase/patologia , Colestase/prevenção & controle , Modelos Animais de Doenças , Feminino , Técnicas de Introdução de Genes , Hemoglobina Falciforme/genética , Insuficiência Hepática/patologia , Insuficiência Hepática/prevenção & controle , Humanos , Microscopia Intravital , Fígado/diagnóstico por imagem , Masculino , Camundongos , Pessoa de Meia-Idade , NF-kappa B/antagonistas & inibidores , NF-kappa B/efeitos dos fármacos , NF-kappa B/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Transdução de Sinais/efeitos dos fármacos , Adulto JovemRESUMO
BACKGROUND AND AIMS: The Wnt/ß-catenin signaling pathway has a well-described role in liver pathobiology. Its suppression was recently shown to decrease bile acid (BA) synthesis, thus preventing the development of cholestatic liver injury and fibrosis after bile duct ligation (BDL). APPROACH AND RESULTS: To generalize these observations, we suppressed ß-catenin in Mdr2 knockout (KO) mice, which develop sclerosing cholangitis due to regurgitation of BA from leaky ducts. When ß-catenin was knocked down (KD) in KO for 2 weeks, hepatic and biliary injury were exacerbated in comparison to KO given placebo, as shown by serum biochemistry, ductular reaction, inflammation, and fibrosis. Simultaneously, KO/KD livers displayed increased oxidative stress and senescence and an impaired regenerative response. Although the total liver BA levels were similar between KO/KD and KO, there was significant dysregulation of BA transporters and BA detoxification/synthesis enzymes in KO/KD compared with KO alone. Multiphoton intravital microscopy revealed a mixing of blood and bile in the sinusoids, and validated the presence of increased serum BA in KO/KD mice. Although hepatocyte junctions were intact, KO/KD livers had significant canalicular defects, which resulted from loss of hepatocyte polarity. Thus, in contrast to the protective effect of ß-catenin KD in BDL model, ß-catenin KD in Mdr2 KO aggravated rather than alleviated injury by interfering with expression of BA transporters, hepatocyte polarity, canalicular structure, and the regenerative response. CONCLUSIONS: The resulting imbalance between ongoing injury and restitution led to worsening of the Mdr2 KO phenotype, suggesting caution in targeting ß-catenin globally for all cholestatic conditions.