The Antimicrobial Peptide Cecropin AD Supplement Alleviated Soybean Meal-Induced Intestinal Inflammation, Barrier Damage, and Microbial Dysbiosis in Juvenile Turbot, Scophthalmus maximus

Abstract

This study aimed to investigate the benefit of dietary cecropin AD (CAD) on the intestinal health of turbot (Scophthalmus maximus) fed diets with a high level of soybean meal. A 12-week feeding trial was conducted with four isonitrogenous and isolipidic diets: a fishmeal-based diet (FM), a diet replacing 40% fish meal protein of FM diet with soybean meal protein (SBM), and the SBM diet supplemented with 0.5 g/kg (C1) and 1.0 g/kg (C2) CAD, respectively. The results of histology of distal intestine (DI) showed that turbots fed the SBM diet exhibited distinct symptoms of enteritis. However, fish fed diets with CAD supplementation kept the normal appearance of the DI which was similar to that in FM group. Compared with the SBM group, diet with CAD supplementation significantly decreased the gene expression of intestinal pro-inflammatory cytokines tumor necrosis factor-α (tnf-α), interleukin-1β (il-1β), interferon-gamma (ifn-γ), and nuclear factor-kappa B p65 (nf-κb p65), while up-regulated the gene expression of intestinal tight junction proteins claudin-3, claudin-4, occludin, and zonula occludens-1 (zo-1). Besides, diet C1 shaped the intestinal microbiota profile toward an anti-inflammatory phenotype represented by the increased abundance of Blutia, Firmicutes/Bacteroides ratio, and decreased Prevotellaceae. In conclusion, dietary CAD could positively modulate the intestinal health of turbot from the impairment induced by soybean meal, which expands its application to help fish better adapt to the increasing plant protein level in aquafeed.

Pap12-6: A host defense peptide with potent immunomodulatory activity in a chicken hepatic cell culture

“…In the present study, only Poly I:C-evoked inflammation resulted in an elevated level of IFN-γ, which increase was not significantly influenced by PAP. In contrast, according to bibliographic data, several other cationic HDPs of insect origin have been reported to affect the production of IFN-γ [37,60,69]. Still, it is of great importance to highlight that different HDPs display highly varied immunomodulatory activities, also depending on the specific experimental circumstances [7].…”

Intestinal absorption of bioactive oligopeptides: paracellular transport and tight junction modulation

“…In the intestine of turbot, dietary cecropin AD increases the gene expression levels of occludin, ZO-1, claudin-4, and claudin-3. 93 In the IPEC-J2 cell monolayer, cecropin A treatment enhances the TER and reduces paracellular permeability. More concretely, cecropin A stimulation increases the expression of claudin-1, occludin, and ZO-1 and cell membrane distribution by increasing CDX2 expression and promotes F-actin polymerization at cell boundaries.…”

Bioactive Peptide Discovery from Edible Insects for Potential Applications in Human Health and Agriculture

“…Different from the antibiotic combination, cecropin AD did not only increase the jejunal secretory immunoglobulins but also increased immunoglobulins and interleukins in serum, indicating a systemic immunomodulating effect of the peptide in weaned piglets. In soybean-meal fed turbot, dietary addition of cecropin AD from the previously described Bacillus subtilis expression system also positively modulated intestinal health and prevented the development of enteritis symptoms by shifting the intestinal microbiota towards an anti-inflammatory phenotype [ 85 ].…”