Analysis of liver repair mechanisms in alagille syndrome and biliary atresia reveals a role for notch signaling

Luca Fabris, Massimiliano Cadamuro, Maria Guido, Carlo Spirli, Romina Fiorotto, Michele Colledan, Giuliano Torre, Daniele Alberti, Aurelio Sonzogni, Lajos Okolicsanyi, Mario Strazzabosco

Research output: Contribution to journalArticlepeer-review

Abstract

Patients with Alagille syndrome (AGS), a genetic disorder of Notch signaling, suffer from severe ductopenia and cholestasis, but progression to biliary cirrhosis is rare. Instead, in biliary atresia (BA) severe cholestasis is associated with a pronounced "ductular reaction" and rapid progression to biliary cirrhosis. Given the role of Notch in biliary development, we hypothesized that defective Notch signaling would influence the reparative mechanisms in cholestatic cholangiopathies. Thus we compared phenotype and relative abundance of the epithelial components of the hepatic reparative complex in AGS (n = 10) and BA (n = 30) using immunohistochemistry and computer-assisted morphometry. BA was characterized by an increase in reactive ductular and hepatic progenitor cells, whereas in AGS, a striking increase in intermediate hepatobiliary cells contrasted with the near absence of reactive ductular cells and hepatic progenitor cells. Hepatocellular mitoinhibition index (p21waf1/Ki67) was similar in AGS and BA. Fibrosis was more severe in BA, where portal septa thickness positively correlated with reactive ductular cells and hepatic progenitor cells. AGS hepatobiliary cells failed to express hepatic nuclear factor (HNF) 1β, a biliary-specific transcription factor. These data indicate that Notch signaling plays a role in liver repair mechanisms in postnatal life: its defect results in absent reactive ductular cells and accumulation of hepatobiliary cells lacking HNF1β, thus being unable to switch to a biliary phenotype.

Original languageEnglish
Pages (from-to)641-653
Number of pages13
JournalAmerican Journal of Pathology
Volume171
Issue number2
DOIs
Publication statusPublished - Aug 2007

ASJC Scopus subject areas

  • Pathology and Forensic Medicine

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