Beta-amyloid deposition around hepatic bile ducts is a novel pathobiological and diagnostic feature of biliary atresia

Babu, Rosana Ottakandathil; Lui, Vincent Chi Hang; Yan, Chen; Yiu, Rachel S.; Ye, Yongqin; Niu, Ben; Wu, Zhuangzhi; Zhang, Ruizhong; Yu, Michelle; Chung, Patrick Ho Yu; Wong, Kenneth Kak Yuen; Xia, Hongmei; Zhang, Michael Qi; Wang, Bin; Lendahl, Urban; Tam, Paul Kwong Hang

doi:10.1016/j.jhep.2020.06.012

Cited by 42 publications

(67 citation statements)

References 47 publications

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“…Functionally damaging variants included all protein-truncating variants and all missense or inframe coding variants that were predicted by SIFT as “deleterious”, by PolyPhen2 as “probably damaging” or that had a CADD score ≥ 20. Candidate gene mRNA and protein expression in liver or bile duct tissue were checked using the human tissue expression database in EMBL-EBI Expression Atlas ( www.ebi.ac.uk ) and our in-house BA liver organoid expression database [19] . The resulting rare, damaging biallelic variants were visually checked using Integrative Genomics Viewer (IGV).…”

Section: Methodsmentioning

confidence: 99%

“…Human foreskin fibroblast cells (BJ, CRL-2522; ATCC) were cultured in DMEM with 10% fetal bovine serum (FBS) and penicillin (100 IU/mL) and streptomycin (100 µg/mL) (Invitrogen). Human intra-hepatic cholangiocytes were derived from liver biopsy via the generation of bile duct organoids following our previously published protocol [19] . Human cholagniocytes were cultured as a monolayer on cover slip coated with Matrigel (356231; Corning Biocoat) in organoid medium until ready for short interfering RNAs (siRNA) transfection.…”

Section: Methodsmentioning

confidence: 99%

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Identification of a wide spectrum of ciliary gene mutations in nonsyndromic biliary atresia patients implicates ciliary dysfunction as a novel disease mechanism

Lam

Tang

et al. 2021

eBioMedicine

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Background Biliary atresia (BA) is the most common obstructive cholangiopathy in neonates, often progressing to end-stage cirrhosis. BA pathogenesis is believed to be multifactorial, but the genetic contribution, especially for nonsyndromic BA (common form: > 85%) remains poorly defined. Methods We conducted whole exome sequencing on 89 nonsyndromic BA trios to identify rare variants contributing to BA etiology. Functional evaluation using patients’ liver biopsies, human cell and zebrafish models were performed. Clinical impact on respiratory system was assessed with clinical evaluation, nasal nitric oxide (nNO), high speed video analysis and transmission electron microscopy. Findings We detected rare, deleterious de novo or biallelic variants in liver-expressed ciliary genes in 31.5% (28/89) of the BA patients. Burden test revealed 2.6-fold (odds ratio (OR) [95% confidence intervals (CI)]= 2.58 [1.15–6.07], adjusted p = 0.034) over-representation of rare, deleterious mutations in liver-expressed ciliary gene set in patients compared to controls. Functional analyses further demonstrated absence of cilia in the BA livers with KIF3B and TTC17 mutations, and knockdown of PCNT, KIF3B and TTC17 in human control fibroblasts and cholangiocytes resulted in reduced number of cilia. Additionally, CRISPR/Cas9-engineered zebrafish knockouts of KIF3B, PCNT and TTC17 displayed reduced biliary flow. Abnormally low level of nNO was detected in 80% (8/10) of BA patients carrying deleterious ciliary mutations, implicating the intrinsic ciliary defects. Interpretation Our findings support strong genetic susceptibility for nonsyndromic BA. Ciliary gene mutations leading to cholangiocyte cilia malformation and dysfunction could be a key biological mechanism in BA pathogenesis. Funding The study is supported by General Research Fund, HMRF Commissioned Paediatric Research at HKCH and Li Ka Shing Faculty of Medicine Enhanced New Staff Start-up Fund.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Identification of a wide spectrum of ciliary gene mutations in nonsyndromic biliary atresia patients implicates ciliary dysfunction as a novel disease mechanism

Lam

Tang

et al. 2021

eBioMedicine

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“…So far, Babu et al reported that cell junction defects were observed in BA patients and cultured cholangiocyte spheres 44 , while the correlation between these defects and BA development remains unknown. Gene sequencing analysis has suggested that genes associated with tight junctions and adherens junctions are enriched in aberrantly expressed gene sets 45 ; however, to the best of our knowledge, we have reported in detail for the first time that tight junctions and polarity complexes between parenchymal liver cells, including hepatocytes and cholangiocytes, are severely disrupted in BA livers.…”

Section: Discussionmentioning

confidence: 99%

Congenital biliary atresia is correlated with disrupted cell junctions and polarity caused by Cdc42 insufficiency in the liver

Zhou

et al. 2021

Theranostics

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Rationale: Congenital biliary atresia (BA) is a destructive obliterative cholangiopathy of neonates that affects both intrahepatic and extrahepatic bile ducts. However, the cause of BA is largely unknown. Methods: We explored the cell junctions and polarity complexes in early biopsy BA livers by immunofluorescence staining and western blot. Cdc42, as a key cell junction and polarity regulator, was found dramatically decreased in BA livers. Therefore, in order to investigate the role of Cdc42 in BA development, we constructed liver-specific and tamoxifen induced cholangiocyte-specific Cdc42 deleted transgenic mice. We further evaluated the role of bile acid in aggravating biliary damage in Cdc42 insufficient mouse liver. Results: We found a dramatic defect in the assembly of cell junctions and polarity complexes in both cholangiocytes and hepatocytes in BA livers. This defect was characterized by the disordered location of cell junction proteins, including ZO1, β-catenin, E-cadherin and claudin-3. Cdc42 and its active form, Cdc42-GTP, which serves as a small Rho GTPase to orchestrate the assembly of polarity complexes with Par6/Par3/αPKC, were substantially reduced in BA livers. Selective Cdc42 deficiency in fetal mouse cholangiocytes resulted in histological changes similar to those found in human BA livers, including obstruction in both the intra- and extrahepatic bile ducts, epithelial atrophy, and the disruption of cell junction and polarity complexes. A reduction in bile acids notably improved the histology and serological indices in Cdc42-mutant mice. Conclusion: Our results illustrate that BA is closely correlated with the impaired assembly of cell junction and polarity complexes in liver cells, which is likely caused by Cdc42 insufficiency and aggravated by bile acid corrosion.

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“…Human foreskin fibroblast cells (BJ, CRL-2522; ATCC) were cultured in DMEM with 10% fetal bovine serum (FBS) and penicillin (100 IU/mL) and streptomycin (100 mg/mL) (Invitrogen). Human intra-hepatic cholangiocytes were derived from liver biopsy via the generation of bile duct organoids following our previously published protocol [19]. Human cholagniocytes were cultured as a monolayer on cover slip coated with Matrigel (356231; Corning Biocoat) in organoid medium until ready for short interfering RNAs (siRNA) transfection.…”

Section: Cell Culture and Transfectionmentioning

confidence: 99%

Identification of a Wide Spectrum of Ciliary Gene Mutations in Nonsyndromic Biliary Atresia Patients Implicates Ciliary Dysfunction as a Novel Disease Mechanism

Lam

Tang

et al. 2021

SSRN Journal

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Background: Biliary atresia (BA) is the most common obstructive cholangiopathy in neonates, often progressing to end-stage cirrhosis. BA pathogenesis is believed to be multifactorial, but the genetic contribution, especially for nonsyndromic BA (common form: > 85%) remains poorly defined. Methods: We conducted whole exome sequencing on 89 nonsyndromic BA trios to identify rare variants contributing to BA etiology. Functional evaluation using patients' liver biopsies, human cell and zebrafish models were performed. Clinical impact on respiratory system was assessed with clinical evaluation, nasal nitric oxide (nNO), high speed video analysis and transmission electron microscopy. Findings: We detected rare, deleterious de novo or biallelic variants in liver-expressed ciliary genes in 31.5% (28/ 89) of the BA patients. Burden test revealed 2.6-fold (odds ratio (OR) [95% confidence intervals (CI)]= 2.58 [1.15À6.07], adjusted p = 0.034) over-representation of rare, deleterious mutations in liver-expressed ciliary gene set in patients compared to controls. Functional analyses further demonstrated absence of cilia in the BA livers with KIF3B and TTC17 mutations, and knockdown of PCNT, KIF3B and TTC17 in human control fibroblasts and cholangiocytes resulted in reduced number of cilia. Additionally, CRISPR/Cas9-engineered zebrafish knockouts of KIF3B, PCNT and TTC17 displayed reduced biliary flow. Abnormally low level of nNO was detected in 80% (8/10) of BA patients carrying deleterious ciliary mutations, implicating the intrinsic ciliary defects. Interpretation: Our findings support strong genetic susceptibility for nonsyndromic BA. Ciliary gene mutations leading to cholangiocyte cilia malformation and dysfunction could be a key biological mechanism in BA pathogenesis.

show abstract

Beta-amyloid deposition around hepatic bile ducts is a novel pathobiological and diagnostic feature of biliary atresia

Cited by 42 publications

References 47 publications

Identification of a wide spectrum of ciliary gene mutations in nonsyndromic biliary atresia patients implicates ciliary dysfunction as a novel disease mechanism

Identification of a wide spectrum of ciliary gene mutations in nonsyndromic biliary atresia patients implicates ciliary dysfunction as a novel disease mechanism

Congenital biliary atresia is correlated with disrupted cell junctions and polarity caused by Cdc42 insufficiency in the liver

Identification of a Wide Spectrum of Ciliary Gene Mutations in Nonsyndromic Biliary Atresia Patients Implicates Ciliary Dysfunction as a Novel Disease Mechanism

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