Intestinal Explant Cultures from Gilthead Seabream (Sparus aurata, L.) Allowed the Determination of Mucosal Sensitivity to Bacterial Pathogens and the Impact of a Plant Protein Diet.

David Sánchez Peñaranda,Silvia Martínez Llorens,Gaspar Pérez Martínez,Christine Bäuerl,Ana Tomás-Vidal,Guillem Estruch,Miguel Jover-Cerdá

doi:10.3390/ijms21207584

David Sánchez Peñaranda, Silvia Martínez Llorens + Show 5 more

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https://doi.org/10.3390/ijms21207584

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Abstract

The interaction between diet and intestinal health has been widely discussed, although in vivo approaches have reported limitations. The intestine explant culture system developed provides an advantage since it reduces the number of experimental fish and increases the time of incubation compared to similar methods, becoming a valuable tool in the study of the interactions between pathogenic bacteria, rearing conditions, or dietary components and fish gut immune response. The objective of this study was to determine the influence of the total substitution of fish meal by plants on the immune intestinal status of seabream using an ex vivo bacterial challenge. For this aim, two growth stages of fish were assayed (12 g): phase I (90 days), up to 68 g, and phase II (305 days), up to 250 g. Additionally, in phase II, the effects of long term and short term exposure (15 days) to a plant protein (PP) diet were determined. PP diet altered the mucosal immune homeostasis, the younger fish being more sensitive, and the intestine from fish fed short-term plant diets showed a higher immune response than with long-term feeding. Vibrio alginolyticus (V. alginolyticus) triggered the highest immune and inflammatory response, while COX-2 expression was significantly induced by Photobacterium damselae subsp. Piscicida (P. damselae subsp. Piscicida), showing a positive high correlation between the pro-inflammatory genes encoding interleukin 1β (IL1-β), interleukin 6 (IL-6) and cyclooxygenase 2(COX-2).

Highlights

In addition to the digestion and absorption of nutrients, the fish intestine is a complex biological system that represents a major defense barrier against pathogens and plays a crucial role in osmoregulation and immune and inflammatory response [1]
With the aim to evaluate the effect of a plant protein (PP) diet on inflammatory and immune gene expression in the gut, 240 fish were fed on fish meal (FM) diet and PP for 305 days
Two weeks before the end of the experiment, a group of animals from the FM group was introduced to the PP diet, in order to assess a possible short-term effect of the PP in adult fish

Summary

Introduction

In addition to the digestion and absorption of nutrients, the fish intestine is a complex biological system that represents a major defense barrier against pathogens and plays a crucial role in osmoregulation and immune and inflammatory response [1]. Bacterial challenges in vivo require specialized settings, expensive operating costs, and a high number of fish, and it is difficult to perform them and achieve the desired experimental working conditions [3]. In this regard, systems have been developed, based on the ex vivo maintenance of intestine fragments, to evaluate successfully the effect of different bacterial strains on intestinal health and provide very reliable information on the interactions between the bacteria and the host. These systems have been used to register responses to exposure to specific bacteria in human tissue explant cultures, at the gene expression level [12]

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