MULTI-TISSUE PROTEOMIC INSIGHTS REVEAL HOW A PHYTOBIOTIC-BASED ADDITIVE ACTIVATES AN INTEGRATED IMMUNE DEFENSE NETWORK IN GILTHEAD SEABREAM
Introduction
Fish rely on the complex interaction of innate and adaptive immunity to manage pathogens. However, intensive production conditions create stressors like high stocking densities, temperature fluctuations, and plant-based protein sources that act as catalysts for disease. These factors often lead to chronic inflammation, immune exhaustion, and physiological depression, resulting in significant economic losses. Dietary functional additives offer a preventive strategy to support health and reduce disease severity. This study utilized high-throughput proteomics to underline how a phytobiotic-based additive (Sanacore GM, Adisseo) enhances immunocompetence in fish.
Material and Methods
This trial utilized gilthead seabream (Sparus aurata) with an initial body weight of 100g. These fish were reared under optimal conditions at a density of 6kg m-3 for 6 weeks until reaching an average size of 160g. To study the proteome profiles, primary immunoregulatory organs were collected: the anterior intestine (frontline barrier), the liver (phagocytic coordination center), and the head kidney (primary immune cell factory). The analysis was performed using shotgun proteomics (LC-MS/MS) and advanced protein network analysis to identify differentially expressed proteins (DEPs) and their associated biological functions.
Results
The proteomic analysis revealed a total of 2,197 annotated DEPs across the three tissues, revealing that the additive provides a holistic reinforcement of the fish's integrated immune defense network. Rather than independent tissue reactions, the phytobiotic-based additive facilitated a synchronized defense system starting at the frontline barrier and extending through systemic regulation. In the intestine, the additive improved early sensing of threats via the antigen presentation pathway and boosted the ability of local cells to neutralize pathogens through phagocytosis before they could enter the body. It also activated the PPAR pathway to maintain gut integrity through antioxidant and anti-inflammatory responses, reducing the overall infection pressure on the fish. The liver supported this effort by organizing the movement of immune cells via cytoskeletal reorganization and utilizing specialized chaperone proteins to keep proteins correctly folded and functional during stress. Additionally, the liver enhanced MHC class I peptide presentation to help the system mount stronger downstream responses. Finally, the head kidney acted as a high-power regulatory center by significantly increasing the production of defense molecules, including antimicrobial peptides (AMPs) and cytokines. It accelerated pathogen recognition through MHC class I and II molecules and triggered targeted apoptosis in infected cells to stop disease from spreading through the body.
Conclusion
Sanacore GM serves as a comprehensive immunoregulator that synchronizes early pathogen detection in the gut with efficient cellular coordination in the liver and powerful systemic execution in the head kidney. By reinforcing physical barriers and accelerating pathogen recognition, the additive ensures a faster and more efficient immune response under production conditions.
Figure 1. Schematic overview of the three key immunoregulatory tissues analyzed in gilthead seabream.
Figure 1. Schematic overview of the three key immunoregulatory tissues analyzed in gilthead seabream.