Hedgehog pathway and pediatric nonalcoholic fatty liver disease

Area of Science:

• Hepatology
• Developmental Biology
• Molecular Signaling

Background:

• Histology of pediatric nonalcoholic fatty liver disease (NAFLD) differs from adults, but the reasons are unclear.
• Hedgehog (Hh) signaling, crucial for organogenesis, is normally downregulated in adult livers but can be reinduced by injury.
• Adolescent liver development involves the loss of Hh ligand-producing/responding cells, a process potentially disrupted by fatty liver disease.

Purpose of the Study:

• To investigate the role of Hedgehog (Hh) pathway activation in pediatric NAFLD histology.
• To determine if Hh pathway activity differs in children based on age, gender, and puberty status.
• To correlate Hh pathway activation with histological features like inflammation and fibrosis in pediatric NAFLD.

Main Methods:

• Immunohistochemistry was performed on liver biopsy slides from 56 children with NAFLD.
• Assessed Hh pathway activation by quantifying Hh-ligand-producing cells and Hh-responsive (Gli2-positive) cells.
• Correlated Hh pathway markers with clinical and histological data, including fibrosis stage and portal inflammation.

Main Results:

• Fibrosis stage significantly correlated with Hh pathway activity (ligand-producing cells: P < 0.0001; Gli2(+) cells: P = 0.0013).
• The number of Gli2(+) cells also correlated with portal inflammation grade (P = 0.0012).
• Higher portal/periportal Hh-ligand production was associated with male gender, as were ductular proliferation and portal fibrosis in prepubescent males.

Conclusions:

• The portal/periportal progenitor compartment in prepubescent male livers shows elevated Hh pathway activity.
• This heightened Hh signaling may explain unique pediatric NAFLD histology by promoting a fibroductular response.
• Hh pathway activation is a key factor in the distinct histological presentation of pediatric NAFLD.