Integrative Transcriptomic and microRNAomic Profiling Reveals Immune Mechanism for the Resilience to Soybean Meal Stress in Fish Gut and Liver.

Nan Wu,Biao Wang,Ying-Yin Cheng,Yong-An Zhang,Xiang-Yang Zhang,Dan-Dan Chen,Xian-Mei Li,Zheng-Wei Cui,Zhao-Xi Wang,Xuan Xu

doi:10.3389/fphys.2018.01154

Abstract

In aquafeeds, fish-meal has been commonly replaced with plant protein, which often causes enteritis. Currently, foodborne enteritis has few solutions in regards to prevention or cures. The recovery mechanism from enteritis in herbivorous fish may further help understand prevention or therapy. However, few reports could be found regarding the recovery or resilience to fish foodborne enteritis. In this study, grass carp was used as an animal model for soybean meal induced enteritis and it was found that the fish could adapt to the soybean meal at a moderate level of substitution. Resilience to soybean meal stress was found in the 40% soybean meal group for juvenile fish at growth performance, morphological and gene expression levels, after a 7-week feeding trial. Furthermore, the intestinal transcriptomic data, including transcriptome and miRNAome, was applied to demonstrate resilience mechanisms. The result of this study revealed that in juvenile grass carp after a 7-week feeding cycle with 40% soybean meal, the intestine recovered via enhancing both an immune tolerance and wound healing, the liver gradually adapted via re-balancing immune responses, such as phagosome and complement cascades. Also, many immune factors in the gut and liver were systemically revealed among stages of on-setting, remising, and recovering (or relief). In addition, miRNA regulation played a key role in switching immune states. Thus, the present data systemically demonstrated that the molecular adaptation mechanism of fish gut-liver immunity is involved in the resilience to soybean meal stress.

Highlights

With the rapid expansion of the fish farming industry and the limited availability of catching wild fish, the global contribution of fish-meal (FM) to aquafeeds has dramatically decreased (Krol et al, 2016)
In common carp (Cyprinus carpio L.), after 5-weeks of continuous feeding with 20% soybean meal (SBM), the recovery from soybean meal induced enteritis (SBMIE) was assessed and it was found that most of the assessed parameters appeared to return to around normal levels, yet the supranuclear vacuoles (SNV) did not appear to be the normal size and the lamina propria (LP) was still thicker (Uran et al, 2008). These findings suggest that a certain degree of resilience to SBM stress possibly exists, at least in omnivorous fish and speculatively in herbivorous fish
To evaluate the growth performance and survival (Table 2) of fish fed with diets containing graded levels of SBM, parameters, including initial body weight (IBW), percentage weight gain [WG(%)], feed efficiency (FE), food take (FI), survival rate (%)

Summary

Introduction

With the rapid expansion of the fish farming industry and the limited availability of catching wild fish, the global contribution of fish-meal (FM) to aquafeeds has dramatically decreased (Krol et al, 2016). In fish foodborne enteritis, such as soybean meal induced enteritis (SBMIE), the immunity of both the gut and liver have been revealed to be strongly disturbed (De Santis et al, 2015). The gut-liver immunity has been suggested to be in mammals (Trivedi and Adams, 2016), and in fish (Wu et al, 2016) This was based on many different immune processes that were revealed by several systemic studies of both the gut and liver (De Santis et al, 2015; Wu et al, 2016). A study on both the gut and liver is important to reveal the mechanism involved in nutritional stress caused by SBM

Methods

Results

Conclusion