Integrated Hepatic Lipidome Analysis in Aging Mice

The liver is a metabolically active organ vital for carbohydrate, protein, and lipid metabolism as well as detoxification of harmful substances. Here, we integrated multiple reaction monitoring (MRM) profiling, untargeted lipidomics, and desorption electrospray ionization-mass spectrometry imaging (DESI-MSI) to identify age-associated changes in lipid profiles in the liver of adult mice across three age groups: adult (3-4 months), midaged (10 months), and old (19-21 months). Comparative lipidomic analysis revealed age-dependent remodeling of membrane phospholipids and sphingolipids. Aging was associated with significant alterations of phosphatidylcholines (PC), lysophosphatidylcholines (LPC), phosphatidylserines (PS), phosphatidylethanolamines (PE), and phosphatidylinositols (PI), characterized by reduced levels of unsaturated PC species (PC 36:5, PC 36:4) and saturated PC 32:0 alongside increased LPCs and highly unsaturated PC 40:7. In parallel, sphingolipids were also altered, with increased ceramides (Cer 34:1; O2, CerP 36:1; O2, ACer 59:1; O2) and sphingomyelins (SM 34:1; O2, SM 34:0; O2), and decreased levels of longer-chain sphingomyelins (SM 40:1; O2, SM 42:1; O2, SM 40:2; O2) compared with adult and midaged mice. Additionally, DESI-MSI revealed age-associated changes in monounsaturated (palmitoleic, oleic, eicosenoic) and polyunsaturated (linoleic, docosahexaenoic) fatty acids. These lipid alterations were consistently observed across multiple mass spectrometry platforms, including spatially resolved lipid distributions obtained by DESI-MSI, and are linked to membrane structure, signaling, and metabolism, providing new insights into age-related liver dysfunction.