Liposome supplementation enhances host metabolism in a model symbiotic cnidarian

Abstract Stable cnidarian–dinoflagellate symbioses provide the trophic foundation of coral reef ecosystems. Understanding nutrient exchange underpinning this symbiosis, and the need for interventions to improve coral health via aquaculture, grow increasingly urgent as reefs face accelerating threats from climate change. Liposomes and lipid nanoparticles, widely used as delivery vehicles in biomedical science, are emerging as promising tools to supplement coral nutrition. However, physiological impacts of liposomes on cnidarians, including their uptake, nutritional value, and holobiont response, remain largely unexplored. Here, we delivered “empty” phosphatidylcholine liposomes to both symbiotic and aposymbiotic Exaiptasia diaphana , an anemone model for corals, and analyzed the host proteomic response via mass spectrometry. Liposome supplementation elicited broad proteome shifts, with notable overlap between symbiosis- and liposome-induced protein expression. Proteins involved in lipid catabolism, lipid transport, β-oxidation, lysosomal function, and protein translation were significantly more abundant, consistent with enhanced lipid processing and metabolic activity. Liposome supplementation, like symbiosis, suppressed both asexual reproduction and the expression of a suite of predation- and digestion-associated venom proteins and proteases, suggesting a conserved “sated” phenotype in response to lipid supply. Variations in feeding frequency with Artemia had minimal effect on the proteome. These data suggest that adult Exaiptasia may be capable of direct uptake of liposomes, and we propose a model offering a potential tool for probing lipid metabolism, signaling, and symbiotic function in cnidarians. Moreover, the ability to manipulate host physiology using defined lipid formulations holds potential for advancing coral aquaculture and stress resilience, including for reef restoration strategies.