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

Abhishek Kulkarni,Ryan M Anderson,Sara Ibrahim,Ebru Ermis,Amina Basha,Isra Haider,Raghavendra G Mirmira,Emma Montgomery

doi:10.3390/biomedicines10020479

Abstract

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.

Highlights

In the United States, the number of Nonalcoholic fatty liver disease (NAFLD) cases is projected to expand to 100.9 million in 2030, and the global prevalence is estimated at around 25% [1]
NAFLD comprises a broad spectrum of liver damage, which can range from macrovesicular steatosis to steatohepatitis (NASH), fibrosis and liver injury to cirrhosis, and hepatocellular carcinoma (HCC) [2]
We found that glucose was elevated relative to controls under all conditions tested (Figure 5A), though the highest levels were measured in larvae subjected to the Li-PIC3+high-fat diet (HFD) combined treatment

Summary

Introduction

In the United States, the number of NAFLD cases is projected to expand to 100.9 million in 2030, and the global prevalence is estimated at around 25% [1]. NAFLD comprises a broad spectrum of liver damage, which can range from macrovesicular steatosis to steatohepatitis (NASH), fibrosis and liver injury to cirrhosis, and hepatocellular carcinoma (HCC) [2]. Compared to the incidence of HCC in other liver diseases, a larger percentage of HCCs that arise in NASH occur before patients are cirrhotic, leading to larger and less treatable tumors [3]. There has been a growing interest in learning the pathogenesis of NAFLD and identifying key steps in development that could help stop the progression of the disease, no cure and few therapies have been developed. There is a multiple-hit theory for the pathogenesis of NAFLD [4,5].

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Discussion

Conclusion