Correlation of tgfb2 mRNA expression to disease progression in a time course of chronic biliary liver disease

Question To identify the cellular source of TgfB2 in a time course of cholestatic liver disease using Abcb4-KO mice and PSC patients, and to correlate findings to disease stages.

Methods Liver samples from PSC liver biopsies and Abcb4-KO mice at the age of 2-, 6-, 8- and 12-months were stained for HE, Sirius Red and Orcein to visualize inflammation and fibrosis. Morphological evaluation was performed using Ishak and Nakanuma scoring systems. Tgfb2 mRNA expression was analysed by in situ hybridisation using the RNAscope technique and then compared to age matched wildtype Balb/c mice and disease-free human liver as well as PSC samples.

Results In Abcb4-KO tissues, we found an increase in grade and stage of fibrosis and inflammation with advancing disease progression using both scoring systems in comparison to wild type mice. Disease progression was faster in female than in male mice, especially with regard to inflammation. Subscores, e.g. portal tract inflammation and interface hepatitis increased first, while confluent necrosis occurred not before the age of 12 months. Tgfb2 mRNA was expressed in areas of proliferating bile ducts and fibrotically rearranged tissue at all stages of cholestatic disease. Both murine and human livers showing higher Ishak and Nakanuma scores also showed stronger tgfb2 expression, particularly in samples with a high grade of portal inflammation. We are currently performing costaining with cell type/cell fate markers to specifically identify the cell type that upregulates TGFb2 expression.

Conclusions The expression of tgfb2 mRNA increased with disease progression of Abcb4-KO mice, whereby prominent inflammatory grades present with the highest expression levels in mice and human.

Publication History

Article published online:
04 January 2021