Several different factors, including alcohol use and hepatitis C virus (HCV) infection, underlie chronic liver disease. Regardless of the cause, chronic liver disease progress in a similar fashion, ultimately resulting in hepatic fibrosis and loss of organ function. In this episode, Matthew Sweet and colleagues performed gene expression profiling on liver biopsies from patients at different stages of fibrosis with varying disease etiologies. Using this approach, the authors identified genes associated with advanced fibrosis and demonstrated that levels of at least one of the gene products, VCAN, is elevated in serum from patients with advanced fibrosis. Additionally, a set of steatosis-associated genes and serum markers was identified in an HCV patient cohort and validated in a murine model. These common gene signatures have potential as both biomarkers and therapeutic targets of chronic liver disease.
Chronic liver disease (CLD) is associated with tissue-destructive fibrosis. Considering that common mechanisms drive fibrosis across etiologies, and that steatosis is an important cofactor for pathology, we performed RNA sequencing on liver biopsies of patients with different fibrosis stages, resulting from infection with hepatitis C virus (HCV) (with or without steatosis) or fatty liver disease. In combination with enhanced liver fibrosis score correlation analysis, we reveal a common set of genes associated with advanced fibrosis, as exemplified by those encoding the transcription factor ETS-homologous factor (EHF) and the extracellular matrix protein versican (VCAN). We identified 17 fibrosis-associated genes as candidate EHF targets and demonstrated that EHF regulates multiple fibrosis-associated genes, including VCAN, in hepatic stellate cells. Serum VCAN levels were also elevated in advanced fibrosis patients. Comparing biopsies from patients with HCV with or without steatosis, we identified a steatosis-enriched gene set associated with advanced fibrosis, validating follistatin-like protein 1 (FSTL1) as an exemplar of this profile. In patients with advanced fibrosis, serum FSTL1 levels were elevated in those with steatosis (versus those without). Liver Fstl1 mRNA levels were also elevated in murine CLD models. We thus reveal a common gene signature for CLD-associated liver fibrosis and potential biomarkers and/or targets for steatosis-associated liver fibrosis.
Divya Ramnath, Katharine M. Irvine, Samuel W. Lukowski, Leigh U. Horsfall, Zhixuan Loh, Andrew D. Clouston, Preya J. Patel, Kevin J. Fagan, Abishek Iyer, Guy Lampe, Jennifer L. Stow, Kate Schroder, David P. Fairlie, Joseph E. Powell, Elizabeth E. Powell, Matthew J. Sweet