A Novel 2-Hit Zebrafish Model to Study Early Pathogenesis of Non-Alcoholic Fatty Liver Disease.

Nonalcoholic fatty liver disease (NAFLD) is one of the most common liver diseases in adults. NAFLD progresses from benign liver fat accumulation to liver inflammation and cirrhosis, and ultimately leads to liver failure. Although several rodent models have been established for studying NAFLD, they have limitations that include cost, speed of disease development, key dissimilarities, and poor amenability to pharmacological screens. Here, we present a novel 2-hit zebrafish model to replicate aspects of NAFLD pathogenesis. We fed zebrafish larvae a high-fat diet (HFD) to drive liver fat accumulation (first hit). Next, we exacerbated liver-specific inflammation using a transgenic line ( fabp10-CETI-PIC3 ) that induces the expression of proinflammatory cytokines following induction with doxycycline (second hit). These hits promoted fat accumulation and liver inflammation, as demonstrated by the high expression of inflammatory cytokines, macrophage infiltration, stress induction, and hepatic lipid droplet accumulation. Furthermore, zebrafish in this paradigm showed deranged glucose metabolism. To validate a small-molecule screening approach, we treated HFD-fed fish with pioglitazone, a drug shown to be beneficial for NAFLD in humans, and measured a sharp reduction in liver lipid accumulation. These results demonstrate new utility for zebrafish in modeling early NAFLD pathogenesis and demonstrate their feasibility for in vivo screening of new pharmacological interventions.