Identifying nonalcoholic fatty liver disease patients with active fibrosis by measuring extracellular matrix remodeling rates in tissue and blood

Excess collagen synthesis (fibrogenesis) in the liver plays a causal role in the progression of nonalcoholic fatty liver disease (NAFLD). Methods are needed to identify patients with more rapidly progressing disease and to demonstrate early response to treatment. We describe here a novel method to quantify hepatic fibrogenesis flux rates both directly in liver tissue and non-invasively in blood. Twenty-one patients with suspected NAFLD ingested heavy water (2H2O, 50 ml aliquots) 2-3 times daily for 3 to 5 weeks prior to a clinically indicated liver-biopsy. Liver collagen fractional synthesis rate (FSR) and plasma lumican FSR were measured based on 2H labeling using tandem mass spectrometry. Patients were classified by histology for fibrosis stage (F0-F4) and as having non-alcoholic fatty liver (NAFL) or non-alcoholic steatohepatitis (NASH). Magnetic resonance elastography measurements of liver stiffness were also performed. Hepatic collagen FSR in NAFLD increased with advancing disease stage (e.g. higher in NASH than NAFL, positive correlation with fibrosis score and liver stiffness) and correlated with hemoglobin A1C. In addition, plasma lumican FSR demonstrated a significant correlation with hepatic collagen FSR. Conclusion: Utilizing a well-characterized cohort of patients with biopsy-proven NAFLD, this study demonstrates that hepatic scar in NASH is actively remodeled even in advanced fibrosis, a disease that is generally regarded as static and slowly progressive. Moreover, hepatic collagen FSR correlates with established risks for fibrotic disease progression in NASH and plasma lumican FSR correlates with hepatic collagen FSR, suggesting applications as direct or surrogate markers, respectively, of hepatic fibrogenesis in humans. This article is protected by copyright. All rights reserved.