ABSTRACT FINAL ID: 1682
TITLE: Systems biology approach to identify processes and early markers for fibrosis in metabolically-induced NASH in mice
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This work was supported by ZonMw (Program: MKMD, project 114025001).
Introduction: The LDLr-/-.Leiden mouse is a translational, diet-inducible model for non-alcoholic steatohepatitis (NASH) with associated fibrosis, displaying many clinically relevant features of NASH. Our goal is to identify processes and pathways involved in the onset and progression of NASH and fibrosis over time with specific emphasis on early detection of fibrosis. After identification of these processes, we aim to study whether these processes can be modulated by pharmacological interventions.
Materials and methods: Male LDLr-/-.Leiden mice were fed a high-fat diet (HFD) over a period of 30 weeks. Every 6 weeks mice were sacrificed and NASH and fibrosis were assessed by a pathologist. At each time point, analysis of new extra cellular matrix protein synthesis was performed using deuterated water labelling technology. Next Generation RNA sequencing technology was used to identify molecular processes related to lipid metabolism, inflammation and fibrosis. Age-matched chow-fed mice were used as controls. In a second experiment, male LDLr-/-.Leiden mice were fed a high-fat diet supplemented with either obeticholic acid (OCA; 30 mg/kg/day) or pioglitazone (PIO; 10 mg/kg/day). Effect of these interventions on onset (wk12) and progression of NASH and fibrosis (wk 24/30) were studied.
Results: In HFD-fed mice, onset of steatosis was observed at week 12, mild fibrosis at week 18 and moderate fibrosis at week 30. Dynamic protein profiling data was integrated with transcriptome data, revealing the time-resolved dynamics of four key processes involved in the development of NASH. Using integrative pathway analysis these early biological processes were associated with end-point molecular changes in relation to pathological fibrosis, thereby allowing us to generate a molecular signature representing the early onset of fibrosis. Pharmacological intervention affected development of steatosis and induced changes in the dynamic protein profiles for extra cellular matrix proteins, indicating an effect on our early fibrosis molecular signature. Transcriptome data is currently being analyzed.
Conclusions: In a time-resolved study we identified processes which contribute to the development of NASH/fibrosis. Using systems biology and data integrative approaches we were able to identify a liver specific molecular signature representing the onset of fibrosis (wk 12). Pharmacological interventions were able to modulate this early fibrosis molecular signature. This approach will help to identify biomarkers for onset of fibrosis and shorten the time frame of preclinical experiments.