Aquaculture Europe 2021

October 4 - 7, 2021

Funchal, Madeira

Add To Calendar 06/10/2021 16:50:0006/10/2021 17:10:00Europe/LisbonAquaculture Europe 2021PHYTOGENIC BIOACTIVE COMPOUNDS SHAPE FISH MUCOSAL IMMUNITYCaracas - 4th FloorThe European Aquaculture Societywebmaster@aquaeas.orgfalseDD/MM/YYYYaaVZHLXMfzTRLzDrHmAi181982

PHYTOGENIC BIOACTIVE COMPOUNDS SHAPE FISH MUCOSAL IMMUNITY

Joana P. Firmino*1, Jorge Galindo-Villegas2, Felipe E. Reyes-López3, Enric Gisbert4

 

1 TECNOVIT – FARMFAES, S.L., Alforja, Spain

2 Faculty of Biosciences and Aquaculture, Nord University, 8049 Bodø, Norway

3 Consorcio Tecnológico de Sanidad Acuícola, Ictio Biotechnologies S.A., Santiago, Chile

4 IRTA, Aquaculture Program, Sant Carles de la Ràpita, Spain

* Email : jfirmino@farmfaes.com

 



Introduction

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 (Reverter et al. 2021). Although the impact of such phytogenics upon fish mucosal immunity has been extensively evaluated, most of the studies fail in addressing the mechanisms underlying their pharmacological effects. Under this context, the present set of studies describe a holistic approach for evaluating the antiparasitic and antibacterial properties of a feed additive composed by microencapsulated carvacrol, thymol and garlic essential oil, as well as seeking to decipher its mode of action upon gilthead seabream mucosal tissues.

Materials and Methods

This presentation is based on recently developed results from our group. In particular, analyses performed in gills (Firmino et al. 2020), intestine (Firmino et al. 2021b) and skin (Firmino et al. 2021a) showed that these three tissues positively responded to the dietary administration of the phytogenics-based additive, although some variations in the mucosal transcriptional responses were observed among the different tissues. Besides, by combining the results obtained together with a profound literature review on the physiological and immunological mucosal responses of fish fed phytogenics, novel mechanisms are hypothesized to explain the mechanisms of cell activation that may be responsible for such mucosal immune-related responses.

Results and Discussion

From a global point of view, 759 DEGs were obtained in the gills of fish fed the phytogenics-supplemented diet, of which 53 of those DEGs were also modulated in the intestine and another 40 DEGs were also modulated in the skin. In the intestine, 581 DEGs were obtained; of them, 31 were modulated in the skin as well. Regarding the skin analysis, 534 total DEGs were obtained (Figure 1). Only 5 DEGs were shared among the three tissues analysed, suggesting tissue-dependent divergences in the mucosal responses. The different sets of common DEGs did not reveal noteworthy interactions when merged and submitted to an enrichment analysis. The fact that the modulation of genes that are differentially expressed in more than one of the studied tissues seems not to be connected and associated to specific biological processes reinforce the idea that each mucosal tissue responds in a distinct and singular way to the dietary administration of the functional feed additive. In this context, the gill was unexpectedly the tissue that revealed the highest number of DEGs promoted by the phytogenics-supplemented diet, rather than the intestine, which is the site of absorption of the feed additive and, a priori, the site where the major changes with regard to gene expression were expected. This difference in tissue susceptibility may be a consequence of the combination of several factors, such as the gills particular functionality and the mode of action of the phytogenics bioactive compounds.

The intrinsic physiology and anatomy of each mucosal tissue, the extrinsic environment that they are subjected to, their specific microbiota composition and/or its modulation are factors conditioning the different transcriptional profiles obtained (Cabillon and Lazado 2019). Additionally, the potential degradation of the bioactive compounds along the digestive tract and their different pharmacokinetics within each target tissue may also affect tissue-specific responses (Michiels et al. 2008). It is suggested that the terpenes and organosulfurs present in the studied feed additive display their mucosal immunomodulatory activity through the activation of Transient Receptor Potential (TRP) ion channels (Xu et al. 2006). In this sense, bioactive compounds may activate TRP channels leading to intracellular Ca2+ increase and non-canonical activation of the TAK complex. In parallel, stimulation by pathogen-associated molecular patterns (PAMPs) may facilitate the activation of TLR and TRP signalling pathways, which would explain the fish improved ability to cope with pathogenic challenges. This hypothesis opens interesting questions about at which extent gills, as a site of significant immunity and presence of ion channels due to its role in osmoregulation, may be susceptible to functional feed additives and recognized as promising target tissues for dietary therapeutic strategies.

Acknowledgements: This work has been supported by the project DIETAplus funded by the MAPAMA (Spain) and FEMP funds (EU). FER-L thanks the support of Fondecyt regular Nb. 1211841. JF have been subsidized by the Industrial PhD program of Generalitat de Catalunya and TECNOVIT-FARMFAES S.L.

References

Cabillon, N.A.R. and Lazado, C.C. (2019). Mucosal barrier functions of fish under changing environmental conditions. Fishes 4(1): 2.

Firmino, J.P., Fernández-Alacid, L., Vallejos-Vidal, E., et al. (2021a). Carvacrol, thymol, and garlic essential oil promote skin innate immunity in gilthead seabream (Sparus aurata) through the multifactorial modulation of the secretory pathway and enhancement of mucus protective capacity. Frontiers in Immunology 12(559): 633621.

Firmino, J.P., Vallejos-Vidal, E., Balebona, M.C., et al. (2021b). Diet, immunity, and microbiota interactions: An integrative analysis of the intestine transcriptional response and microbiota modulation in gilthead seabream (Sparus aurata) fed an essential oils-based functional diet. Frontiers in Immunology 12(356): 625297.

Firmino, J.P., Vallejos-Vidal, E., Sarasquete, C., et al. (2020). Unveiling the effect of dietary essential oils supplementation in Sparus aurata gills and its efficiency against the infestation by Sparicotyle chrysophrii. Scientific Reports 10(1): 17764.

Michiels, J., Missotten, J., Dierick, N., et al. (2008). In vitro degradation and in vivo passage kinetics of carvacrol, thymol, eugenol and trans-cinnamaldehyde along the gastrointestinal tract of piglets. Journal of the Science of Food and Agriculture 88(13), 2371-2381.

Reverter, M., Tapissier-Bontemps, N., Sarter, S., et al. (2021). Moving towards more sustainable aquaculture practices: a meta-analysis on the potential of plant-enriched diets to improve fish growth, immunity and disease resistance. Reviews in Aquaculture 13(1), 537-555.

Xu, H., Delling, M., Jun, J.C. and Clapham, D.E. (2006). Oregano, thyme and clove-derived flavors and skin sensitizers activate specific TRP channels. Nature Neuroscience 9(5), 628-635.