Phoenixin 14 Inhibits High-Fat Diet-Induced Non-Alcoholic Fatty Liver Disease in Experimental Mice

Abstract

Introduction: Nonalcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases. The development of NAFLD is closely associated with hepatic lipotoxicity, inflammation, and oxidative stress. The new concept of NAFLD treatment is to seek molecular control of lipid metabolism and hepatic redox hemostasis. Phoenixin is a newly identified neuropeptide with pleiotropic effects. This study investigated the effects of phoenixin 14 against high-fat diet (HFD)-induced NAFLD in mice.

Materials and methods: For this study, we used HFD-induced NAFLD mice models to analyze the effect of phonenixin14. The mice were fed on HFD and normal diet and also given phoenixin 14 (100 ng/g body weight) by gastrogavage for 10 weeks. The peripheral blood samples were collected for biochemical assays. The liver tissues were examined for HFD-induced tissue fibrosis, lipid deposition and oxidative activity including SOD, GSH, and MDA. The liver tissues were analyzed for the inflammatory cytokines and oxidative stress pathway genes.

Results: The results indicate that phoenixin 14 significantly ameliorated HFD-induced obesity and fatty liver. The biochemical analysis of blood samples revealed that phoenixin 14 ameliorated HFD-induced elevated circulating alanine aminotransferase (ALT), aspartate aminotransferase (AST), total cholesterol, and triglyceride levels, suggesting that phoenixin 14 has a protective role in liver function and lipid metabolism. Hematoxylin-eosin (HE) and Oil Red O staining of the liver showed that phoenixin 14 alleviated HFD-induced tissue damage and lipid deposition in the liver. Furthermore, the mice administered with phoenixin 14 had increased hepatic SOD activity, increased production of GSH and reduced MDA activity, as well as reduced production of TNF-α and IL-6 suggesting that phoenixin 14 exerts beneficial effects against inflammation and ROS. The findings suggest an explanation of how mechanistically phoenixin 14 ameliorated HFD-induced reduced activation of the SIRT1/AMPK and NRF2/HO-1 pathways.

Conclusion: Collectively, this study revealed that phoenixin 14 exerts a protective effect in experimental NAFLD mice. Phoenixin could be of the interest in preventive modulation of NAFLD.

Keywords: NAFLD; NRF2/HO-1; SIRT1/AMPK; inflammation; nonalcoholic fatty liver disease; oxidative stress; phoenixin 14.

Figure 1

Administration of phoenixin 14 decreases body weight and liver weight in NAFLD experimental mice. Mice were divided into four groups: normal chow (NC) group; normal chow (NC) + phoenixin 14 group; a high-fat diet group (HFD) group; a high-fat diet + phoenixin 14 (100 ng/g body weight) group. (A) Body weights of mice; (B) Liver weights of mice (**P<0.01 vs vehicle group; ^##P<0.01 vs HFD group, ^$P>0.05 vs vehicle group).

Figure 2

Administration of phoenixin 14 improves liver function and increases lipid levels in NAFLD mice. (A) ALT; (B) AST; (C) Total cholesterol; (D) Triglyceride (*, **P<0.05, 0.01 vs vehicle group; ^##P<0.01 vs HFD group).

Figure 3

Administration of phoenixin 14 ameliorates hepatic tissue damage, lipid deposition, and fibrosis in HFD-fed mice. (A) Representative liver histological section images; (B) Representative images and quantitative graph of liver Oil Red staining for the four groups of mice; (C) Representative images and quantitative graph of Masson staining for the four groups of mice (**P<0.01 vs vehicle group; ^##P<0.01 vs HFD group).

Figure 4

Administration of phoenixin 14 ameliorates hepatic oxidative stress in NAFLD mice. (A) SOD activity; (B) GSH levels; (C) MDA levels (*, **P<0.05, 0.01 vs vehicle group; ^##P<0.01 vs HFD group).

Figure 5

Administration of phoenixin 14 reduces hepatic TNF-α and IL-6 production in NAFLD mice. (A) TNF-α; (B) IL-6 (*, **P<0.05, 0.01 vs vehicle group; ^##P<0.01 vs HFD group).

Figure 6

Administration of phoenixin 14 increases the hepatic expression of antioxidant regulators in NAFLD mice. (A) mRNA of NRF2, HO-1, and NQO-1; (B) Protein of NRF2, HO-1, and NQO-1 (^{*, &}P<0.05, vs vehicle group; ^#P<0.01 vs HFD group).

Figure 7

Administration of phoenixin 14 mitigates the hepatic reduction of SIRT1 expression and AMPK inactivation in NAFLD mice. Expression of SIRT1 and phosphorylated AMPKα (^{*, &}P<0.05, vs vehicle group; ^#P<0.01 vs HFD group).

Figure 8

Graphical summary of the mechanism described in this study.