Phytogenic Bioactive Compounds Shape Fish Mucosal Immunity

Abstract

Aquaculture growth will unavoidably involve the implementation of innovative and sustainable production strategies, being functional feeds among the most promising ones. A wide spectrum of phytogenics, particularly those containing terpenes and organosulfur compounds, are increasingly studied in aquafeeds, due to their growth promoting, antimicrobial, immunostimulant, antioxidant, anti-inflammatory and sedative properties. This trend relies on the importance of the mucosal barrier in the fish defense. Establishing the phytogenics’ mode of action in mucosal tissues is of importance for further use and safe administration. Although the impact of phytogenics upon fish mucosal immunity has been extensively approached, most of the studies fail in addressing the mechanisms underlying their pharmacological effects. Unstandardized testing as an extended practice also questions the reproducibility and safety of such studies, limiting the use of phytogenics at commercial scale. The information presented herein provides insight on the fish mucosal immune responses to phytogenics, suggesting their mode of action, and ultimately encouraging the practice of reliable and reproducible research for novel feed additives for aquafeeds. For proper screening, characterization and optimization of their mode of action, we encourage the evaluation of purified compounds using in vitro systems before moving forward to in vivo trials. The formulation of additives with combinations of compounds previously characterized is recommended to avoid bacterial resistance. To improve the delivery of phytogenics and overcome limitations associated to compounds volatility and susceptibility to degradation, the use of encapsulation is advisable. Besides, newer approaches and dedicated methodologies are needed to elucidate the phytogenics pharmacokinetics and mode of action in depth.

A Bioactive Extract Rich in Triterpenic Acid and Polyphenols from Olea europaea Promotes Systemic Immunity and Protects Atlantic Salmon Smolts Against Furunculosis

“…The number of studies focused on the use of a wide variety of phytogenics as sustainable tools to be implemented in aquaculture production has dramatically increased in the last years. This has been mainly due to phytogenics’ growth-promoting, antimicrobial, immunostimulant, antioxidant, and anti-inflammatory properties ( 13 , 42 ). In this study, we have evaluated a new phytogenic feed additive rich in triterpenic compounds and polyphenols derived from olive fruit (AQUOLIVE ® ) on the systemic immune response and disease resistance in Atlantic salmon smolts.…”

Effects of Garlic Allium sativum Powder on Nutrient Digestibility, Haematology, and Immune and Stress Responses in Eurasian Perch Perca fluviatilis Juveniles

“…Garlic Allium sativum belongs to the Liliaceae family [6]. It has long been used as a herbal medicine and may be relevant to aquaculture because of its immunostimulant properties [7]. Garlic contains alliin, which has sulfur compounds including gamma-Animals 2021, 11, 2735 2 of 18 glutamyl-s-allyl-cysteine and S-allyl-L-cysteins sulfoxides.…”

Vaccination of Gilthead Seabream After Continuous Xenoestrogen Oral Exposure Enhances the Gut Endobolome and Immune Status via GPER1

“…In farmed teleost fish, the proper crosstalk between the commensal bacteria residing in the mucosa and the immune cells within the mucosal interphase is essential for controlling and preventing major immune disorders ( 53 , 54 ). This link highlights the critical importance of cautiously monitoring the immune interventions in the presence of exogenous elements from either a spontaneous or planned artificial origin (e.g., environmentally generated EDCs or vaccination) that may alter such delicate crosstalks.…”