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Abcb4-defect cholangitis mouse model with hydrophobic bile acid composition by in vivo liver-specific gene deletion
Kota Tsuruya1, Keiko Yokoyama2, Yusuke Mishima1
1Division of Gastroenterology, Department of Internal Medicine, Tokai University School of Medicine, Isehara, Kanagawa, Japan; Department of Molecular Life Sciences, Tokai University School of Medicine, Isehara, Kanagawa, Japan.
Insights
Mice lacking the Abcb4 gene and specific rodent enzymes develop severe liver injury, mimicking human Progressive Familial Intrahepatic Cholestasis type 3 (PFIC3). This enhanced model aids in studying cholestatic liver diseases and developing treatments.
Area of Science:
- Hepatology
- Genetics
- Biochemistry
Background:
- Progressive Familial Intrahepatic Cholestasis (PFIC) is a severe childhood liver disease often necessitating transplantation.
- Mutations in the ABCB4 gene cause PFIC type 3 (PFIC3), affecting bile phosphatidylcholine transport.
- Existing Abcb4-deficient mouse models show milder PFIC3 phenotypes due to rodent-specific bile acid metabolism.
Purpose of the Study:
- To develop a more accurate mouse model for PFIC3 by combining Abcb4 deficiency with a human-like bile acid profile.
- To investigate the impact of a human-like bile acid composition on the severity of cholestatic liver injury.
Main Methods:
- Generated triple-gene-deficient mice (CYPDKO/abcb4-deficient) by deleting Abcb4 in mice lacking Cyp2c70 and Cyp2a12.
- Utilized adeno-associated viruses (AAVs) with SaCas9 and gRNAs for in vivo Abcb4 gene deletion.
- Analyzed liver injury, inflammatory and fibrotic markers, bile duct proliferation, and bile acid composition.
Main Results:
- Abcb4-deficient CYPDKO mice exhibited significantly more severe liver injury than Abcb4-deficient wild-type mice.
- Elevated inflammatory and fibrotic markers, bile duct cell proliferation, and immune cell infiltration were observed.
- These mice displayed a predominance of hydrophobic bile acids (taurine-conjugated chenodeoxycholic acid and lithocholic acid) and undetectable gallbladder phospholipids.
Conclusions:
- Triple-gene-deficient mice with a human-like bile acid profile and Abcb4 defect represent a superior model for severe cholestatic liver injury.
- This refined PFIC3 mouse model is valuable for understanding human cholestatic liver diseases and for preclinical therapeutic development.
Abstract:
Progressive familial intrahepatic cholestasis (PFIC) is a liver disease that occurs during childhood and requires liver transplantation. ABCB4 is localized along the canalicular membranes of hepatocytes, transports phosphatidylcholine into bile, and its mutation causes PFIC3. Abcb4 gene-deficient mice established as animal models of PFIC3 exhibit cholestasis-induced liver injury. However, their phenotypes are often milder than those of human PFIC3, partly because of the existence of large amounts of less toxic hydrophilic bile acids synthesized by the rodent-specific enzymes Cyp2c70 and Cyp2a12. Mice with double deletions of Cyp2c70/Cyp2a12 (CYPDKO mice) have a human-like hydrophobic bile acid composition. PFIC-related gene mutations were induced in CYPDKO mice to determine whether these triple-gene-deficient mice are a better model for PFIC. To establish a PFIC3 mouse model using CYPDKO mice, we induced abcb4 gene deletion in vivo using adeno-associated viruses expressing SaCas9 under the control of a liver-specific promoter and abcb4-target gRNAs. Compared to Abcb4-deficient wild-type mice, Abcb4-deficient CYPDKO mice showed more pronounced liver injury along with an elevation of inflammatory and fibrotic markers. The proliferation of intrahepatic bile ductal cells and hematopoietic cell infiltration were also observed. CYPDKO/abcb4-deficient mice show a predominance of taurine-conjugated chenodeoxycholic acid and lithocholic acid in the liver. In addition, phospholipid levels in the gallbladder bile were barely detectable. Mice with both human-like bile acid composition and Abcb4-defect exhibit severe cholestatic liver injury and are useful for studying human cholestatic diseases and developing new treatments.
