A fish intestinal in vitro model for investigation of lipid metabolism and steatosis

• Published in: Biochimica et biophysica acta. Molecular and cell biology of lipids 2025-01, Vol.1870 (1), p.159573, Article 159573
• Main Authors: Siciliani, Daphne, Ruyter, Bente, Løkka, Guro, Præsteng, Kirsti Elisabeth, Minghetti, Matteo, Kortner, Trond M.
• Format: Article
• Language: English
• Subjects: Animals; Cell Line; Enterocytes - metabolism; Fatty Acids - metabolism; Fatty Liver - metabolism; Fatty Liver - pathology; In vitro approaches; Intestinal Mucosa - metabolism; Intestinal steatosis; Intestines - metabolism; Intestines - pathology; Lipid Droplets - metabolism; Lipid Metabolism; Oleic acid; Oleic Acid - metabolism; Oncorhynchus mykiss - metabolism; Rainbow trout
• ISSN: 1388-1981; 1879-2618; 1879-2618
• DOI: 10.1016/j.bbalip.2024.159573

Choline is now recognized as an essential nutrient to ensure lipid transport in Atlantic salmon. Its deficiency leads to excessive lipid accumulation in the enterocytes, a condition known as steatosis. The knowledge of lipid metabolism and steatosis in fish remains limited, motivating the use of in vitro intestinal models to perform deeper explorations. This study aimed to create an in vitro steatosis model using RTdi-MI, a new cell line derived from the distal intestine of rainbow trout. Cells were exposed to varying oleic acid (OA) concentrations over different time points (24 h, 72 h, and 168 h). Results indicated that the increasing OA concentration enhanced intracellular lipid droplet formation. Quantitative lipid analysis confirmed OA accumulation, which intensified with prolonged exposure and increased OA dose. Moreover, all cells, including controls, exhibited fatty acid metabolic activity. Such outcome was confirmed by light and fluorescence microscopy. Additionally, RTdi-MI cells expressed genes involved in lipid metabolism and synthesis similar to in vivo conditions. Collectively, our findings demonstrate the ability of RTdi-MI cells to accumulate OA in intracellular lipid droplets and mirror in vivo steatosis conditions, offering a new tool for exploring fish intestinal lipid metabolism. •A new fish cell line mimics steatosis symptoms observed in fish intestinal tissue in vivo.•Intracellular lipid accumulation was demonstrated via morphological, molecular, and absolute quantification.•The fish cell line expresses several genes known to regulate lipid metabolism in vivo.