Does amyloid β precursor protein gene expression have a role in diagnosis of biliary atresia?

Organoids in biliary atresia

Organoids are three-dimensional and self-organizing cell cultures of various lineages that resemble structures and functions of an organ in many ways, and they are versatile tools in disease modeling and patho-mechanistic study of human diseases affecting their tissues of origin. Biliary atresia (BA), a cholangiopathy affecting the bile ducts of the liver, is a heterogeneous and multifaceted liver disease of complex pathogenesis. Cholangiopathies refer to a category of liver diseases that affect the cholangiocytes, the epithelial cells lining the lumen of the biliary trees. Biliary organoids consist of cholangiocytes in a spherical monolayer epithelium, which favorably resembles the structures and functional properties of the bile duct cholangiocytes. Biliary tissue-derived cells, pluripotent stem cells or embryonic stem cells, and hepatic progenitor cells are capable of generating biliary organoids. In the last decade, a considerable advancement has been made in the generation of biliary organoids for modeling liver physiology and pathophysiology. Using biliary organoids, scientists have advanced our knowledge underlying the pathogenic roles of genetic susceptibility, dysregulated hepatobiliary development/structure, environmental factors, and dysregulated immune-inflammatory responses to an injury in BA. This review will summarize and discuss the derivation and the use of biliary organoids in the disease modeling and patho-mechanistic study of BA.

Amyloid precursor protein as a fibrosis marker in infants with biliary atresia

BACKGROUND

Biliary atresia (BA) is a rare condition of unknown origin in newborns with jaundice. In BA bile ducts are non-functional, causing neonatal cholestasis and following liver fibrosis and failure.

METHODS

This retrospective study included liver biopsies of 14 infants with BA aged [mean ± SD] 63 ± 23 days. Patients were grouped according to the clinical course (jaundice-free vs recurrent jaundice vs required liver transplantation or liver fibrosis (Ishak fibrosis score)) and followed for 1.61-5.64 years (mean 4.03). Transcriptome profiles were assessed using a panel of 768 fibrosis-specific genes, reanalyzed via qRT-PCR, and confirmed via immunostaining. Plasma from an additional 30 BA infants and 10 age-matched controls were used for amyloid precursor protein (APP) quantification by ELISA.

RESULTS

Different clinical outcome groups showed a homogeneous mRNA expression. Altered amyloid-metabolism-related gene expression was found between cases with Ishak fibrosis score greater than 4. Immunostaining confirmed a distinct presence of APP in the livers of all BA subjects. APP plasma levels were higher in BA than in age-matched controls and correlated with the histological fibrosis grade.

CONCLUSIONS

These results suggest that amyloidosis may contribute to BA and liver fibrosis, indicating that APP could serve as a potential liquid biomarker for these conditions.

IMPACT

Biliary atresia patients with higher fibrosis scores according to Ishak have higher hepatic expression of amyloid-related genes while amyloid precursor protein accumulates in the liver and increases in the circulation. After a recent study revealed beta-amyloid deposition as a mechanism potentially involved in biliary atresia, we were able to correlate amyloid-metabolism-related transcript levels as well as amyloid precursor protein tissue and plasma levels with the degree of hepatic fibrosis. These findings suggest that amyloid precursor protein is a fibrosis marker in infants with biliary atresia, reinforcing the role of amyloid metabolism in the pathogenesis of this serious disease.