Fatty acid-specific lipid remodeling shapes inflammatory responses and intestinal epithelial barrier functions.

Intestinal epithelial cells are the primary site for the absorption of dietary unsaturated fatty acids, yet the distinct effects of these fatty acids on epithelial barrier integrity and lipid homeostasis remain unclear. Here, we compared the effects of oleic acid (OA), linoleic acid (LA), and α-linolenic acid (ALA), respectively, in differentiated Caco-2 monolayers. LA markedly impaired epithelial barrier integrity, as indicated by disrupted tight junction organization, enhanced oxidative stress, and activation of TLR4/MyD88/NF-κB inflammatory signaling. By contrast, OA induced relatively mild alterations, whereas ALA better preserved epithelial homeostasis, accompanied by enhanced antioxidant defense and attenuated inflammatory signaling. Untargeted lipidomics revealed fatty acid-specific remodeling of cellular lipid homeostasis. LA promoted free fatty acid accumulation, sphingolipid/phospholipid imbalance, and cardiolipin remodeling, suggesting a lipid-disruptive profile associated with barrier dysfunction. Conversely, ALA enriched structural phospholipids, including PC, PE, PI, and PS, while limiting free fatty acid accumulation, indicating a membrane lipid profile favorable for epithelial stability and lipid homeostasis.