Activation of Autophagy Relieves Linoleic Acid-Induced Inflammation in Large Yellow Croaker (Larimichthys crocea).

Bo Yang,Kangsen Mai,Renlei Ji,Qinghui Ai,Qiang Chen,Qiuchi Chen,Wei Fang,Wei Xu,Xueshan Li

doi:10.3389/fimmu.2021.649385

Abstract

High levels of soybean oil (SO) in fish diets enriched with linoleic acid (LA, 18:2n-6) could induce strong inflammation. However, the molecular mechanism underlying LA-induced inflammation in the liver of large yellow croaker (Larimichthys crocea) has not been elucidated. Based on previous research, autophagy has been considered a new pathway to relieve inflammation. Therefore, the present study was performed to investigate the role of autophagy in regulating LA-induced inflammation in the liver of large yellow croaker in vivo and in vitro. The results of the present study showed that activation of autophagy in liver or hepatocytes could significantly reduce the gene expression of proinflammatory factors, such as tumor necrosis factor α (TNFα) and interleukin 1β (IL1β). The results of the present study also showed that inhibition of autophagy could upregulate the gene expression of proinflammatory factors and downregulate the gene expression of anti-inflammatory factors in vivo and in vitro. Furthermore, autophagy could alleviate LA-induced inflammatory cytokine gene expression in vivo and in vitro, while inhibition of autophagy obtained the opposite results. In conclusion, our study shows that autophagy could regulate inflammation and alleviate LA-induced inflammation in the liver of large yellow croaker in vivo and in vitro for the first time, which may offer considerable benefits to the aquaculture industry and human health.

Highlights

Fish oil (FO) contains a relatively high content of long-chain polyunsaturated fatty acids (LCPUFAs) and is the major lipid component of traditional fish diets
Compared with the control group, 1.0 mg/kg RAPA injection for 12 h significantly increased the transcript expression levels of the anti-inflammatory cytokine IL10 and significantly decreased the transcript expression levels of the proinflammatory cytokines tumor necrosis factor a (TNFa) and interleukin 1b (IL1b) (P < 0.05) (Figure 1C); in addition, 1.0 mg/kg RAPA injection for 48 h significantly decreased the transcript expression levels of the proinflammatory cytokines TNFa and IL1b (P < 0.05) (Figure 1D). These results indicate that activation of autophagy could downregulate the inflammation level in vivo
Treatment with 200 nM RAPA for 12 h significantly decreased the transcript expression levels of the proinflammatory cytokines TNFa, IL10, IFNg, and MyD88 and significantly increased the transcript expression levels of antiinflammatory Arg I and IL10 (P < 0.05) (Figure 2D). These results indicate that activation of autophagy could downregulate the inflammation level in vitro

Summary

Introduction

Fish oil (FO) contains a relatively high content of long-chain polyunsaturated fatty acids (LCPUFAs) and is the major lipid component of traditional fish diets. Increasing demand, uncertain availability and high price of fish oil have necessitated the search for alternative lipid sources [1]. Soybean oil has abundant linoleic acid content, considerable output and an acceptable price and represents a promising alternative to fish oil. Numerous studies have demonstrated that high linoleic acid levels in diets could lead to a decrease in growth, antioxidant capacity and immunity in large yellow croaker [2, 3]. Many studies on the nutritional immunity of Autophagy Relieves LA-Induced Inflammation large yellow croaker have been conducted in recent years [4]. No information is available on the molecular solution of linoleic acid-induced inflammation

Methods

Results

Conclusion